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  • 1995-1999  (180)
  • 1970-1974
  • 1920-1924
  • 1880-1889
  • 1800-1809
  • 1997  (180)
  • crystal structure  (134)
  • Ultrastructure
  • 1
    Electronic Resource
    Electronic Resource
    Synthesis and Characterization of the Isocyanide Ligated Centered Zirconium Halide Cluster [(Zr6Be)Cl12(CNXyl)6] (1997)
    Springer
    Journal of cluster science 8 (1997), S. 521-531 
    Details
    ISSN: 1572-8862
    Keywords: Zirconium clusters ; isocyanide ; synthesis ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The first isocyanide ligated hexanuclear zirconium halide cluster is reported. The unoxidized [(Zr6Be)Cl12(CNXyl)6] (CNXyl = 2,6-dimethylphenyl isocyanide) was obtained from the solid state precursor K3Zr6Cl15Be by dissolution in CH3CN in the presence of CNXyl. The CNXyl ligands occupy all the axial positions on the cluster. The compound was recrystallized from CH2Cl2 and Et2O. [(Zr6Be)Cl12(CNXyl)6].2CH2Cl2 crystallizes in the space group $${\text{P}}\overline {\text{1}} $$ (#2) with a = 12.092(5) Å, b=12.728(5) Å, c = 14.102(8) Å, α = 104.98(4)°, β =107.11°, γ = 100.94°, V = 1919(2) Å3, Z = l, R = 11.3% and R W = 27.0%. For the bound isocyanide ligands, v CN increases to 2140 cm−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022605113866
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  • 2
    Electronic Resource
    Electronic Resource
    Reactions of the Dirhenium(II) Complexes Re2 X 4(μ-dppm)2 (X=Cl, Br; dppm=Ph2PCH2PPh2) with Isocyanides. Part XV: A Fifth Structural Isomer of the [Re2Cl3(μ-dppm)2(CO)(CNXyl)2]+ Cation (Xyl = 2, 6-Dimethylphenyl) (1997)
    Springer
    Journal of cluster science 8 (1997), S. 547-551 
    Details
    ISSN: 1572-8862
    Keywords: Rhenium ; dirhenium complexes ; rhenium–rhenium multiple bonds ; isocyanide ligands ; carbonyl ligand ; structural isomers ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The reaction of the unsymmetrical, coordinatively unsaturated dirhenium(II) complex [(XylNC)(OC)CIRe(μ-dppm)2ReCl2]O3SCF3 (dppm = Ph2PCH2PPh2) with one equivalent of XylNC in CH2Cl2 affords a fifth structural isomer of the [Re2Cl3(μ-dppm)2(CO)(CNXyl)2] + cation; this is believed to have a CO-bridged structure of the type [(XylNC)ClRe(μ-Cl)(μ-CO)(μ-dppm)2ReCl(CNXyl)]+. The latter complex reacts with a further equivalent of XylNC in the presence of Tl+ to form the [Re2Cl2(μ-dppm)2(CO)(CNXyl)3]2+ cation, which has been shown by IR spectroscopy, and by the X-ray crystallographic characterization of its neutral congener Re2Cl2(μ-dppm)2(CO)(CNXyl)3, to contain a very weak and unsymmetrical CO bridge.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022609214775
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  • 3
    Electronic Resource
    Electronic Resource
    Dynamics of the ultrastructural changes in blood and lymphatic capillaries of bronchi in inflammation and following endobronchial laser therapy (1997)
    Springer
    Virchows Archiv 431 (1997), S. 283-290 
    Details
    ISSN: 1432-2307
    Keywords: Key words Inflammation of the bronchi ; Bronchial biopsy ; Ultrastructure ; Vessels ; Laser therapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  An ultrastructural and autoradiographic analysis of changes in 188 biopsy specimens of bronchial mucosa of the large bronchi from 76 patients with chronic inflammatory lung diseses was carried out. Fibrosis results in an apparent reduction of metabolic activity in endothelial cells, affecting the proliferation of basal cells with changes in cell differentiation. Endobronchial laser therapy with an helium-neon laser induces proliferative and metabolic processes in the lamina propria of the bronchial mucosa with hyperaemia, intensive diapedesis of leucocytes and formation of leucocytic infiltrations and granulation tissue. The proliferative and metabolic activity of endothelial and stromal cells increases, and delicate fibrous connective tissue is formed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004280050100
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  • 4
    Electronic Resource
    Electronic Resource
    Fixation of human detrusor smooth muscle cells: role of osmolarity and magnesium ions on the ultrastructural morphology (1997)
    Springer
    Urological research 25 (1997), S. 283-289 
    Details
    ISSN: 1434-0879
    Keywords: Detrusor ; Fixation ; Magnesium Osmolarity ; Smooth muscle cells ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Magnesium ions added to fixatives for processing to Transmission Electron Microscopy (TEM) have been claimed to cause relaxation of detrusor smooth muscle cells [1]. This should facilitate the morphologic evaluation of the tissue. However, magnesium ions are osmotically active and their addition may cause the fixative to become hypertonic to the tissue. To ascertain whether the presence of magnesium ions causes significant changes compared to those found where the osmolarity is raised without the presence of magnesium, human detrusor specimens were fixed in glutaraldehyde to which increasing amounts of MgCl2 or NaCl were added in different concentrations. With the addition of increasing amounts of MgCl2 and NaCl, the osmolarity of the fixative increased, causing significant changes in the morphology and morphometry of the tissue. The intercellular distances increased, the cells shrank and the shape of the cells changed from smooth and rounded to spiky and angulated. With regard to its muscle-relaxing effect, it was not possible to distinguish the specimens fixed in magnesium-containing fixatives from those without. In this study it was not possible to prove any relaxing effect of magnesium ions added to the fixative. On the contrary the magnesium ions caused an increase in the osmolarity, with significant changes in both the morphometry and the morphology of the human detrusor smooth muscle cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00942099
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  • 5
    Electronic Resource
    Electronic Resource
    Eosinophilic intranuclear inclusions in the hippocampal pyramidal neurons of a patient with amyotrophic lateral sclerosis (1997)
    Springer
    Acta neuropathologica 93 (1997), S. 532-536 
    Details
    ISSN: 1432-0533
    Keywords: Key words Neuronal intranuclear inclusion ; Amyotrophic lateral sclerosis ; Ammon’s horn ; Ultrastructure ; Ubiquitin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report the presence of round eosinophilic intranuclear inclusions in a patient with sporadic amyotrophic lateral sclerosis (ALS). The inclusions were limited to the hippocampal pyramidal neurons; they were frequently encountered in the CA1 and CA2 regions and much less frequently in the CA3 and CA4 regions and in the subiculum. Ultrastructurally, they consisted of randomly oriented straight filaments, each about 8–14 nm in diameter, some of which had a tubular appearance in cross-section. Electron-dense, granular material was intermingled with the filaments. Immunohistochemically, all the inclusions were positive for ubiquitin, but were negative for several kinds of cytoskeletal protein, including actin, glial fibrillary acidic protein, vimentin, neurofilament polypeptides, keratin, tubulin, tau protein and microtubule-associated protein 2. To our knowledge, this type of neuronal intranuclear inclusion has not so far been reported in ALS, and its distribution limited to the hippocampal formation is of great interest.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010050649
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  • 6
    Electronic Resource
    Electronic Resource
    Spatial distribution of β-spectrin in normal and dystrophic human skeletal muscle (1997)
    Springer
    Acta neuropathologica 94 (1997), S. 240-246 
    Details
    ISSN: 1432-0533
    Keywords: Keywords Spectrin ; Dystrophin ; Ultrastructure ; Duchenne muscular dystrophy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Spectrin, a major component of the erythrocyte membrane skeleton, has previously been shown to form a two-dimensional lattice in erythrocytes, and in avian or chicken skeletal muscle. Those results were mainly obtained with antibodies against α-spectrin. Using immunofluorescence of semithin cryosections and single muscle fiber preparations, we show here that β-spectrin forms a costameric network which covers the plasma membrane of human skeletal muscle. These spectrin costameres are correlated with the Z-bands. They are longitudinally connected by fine strands and interrupted by myonuclear lacunae. Under mechanical stretching, the costameres retained their correlation to the Z-bands in normal and dystrophin-deficient muscle, up to the point at which the sarcolemma was disrupted. In stretched muscle, in some regions of the stretched fibers in which the costameres seemed to form double strands, the usually 1:1 correlation of spectrin to the Z-bands changed to a 2:1 relation. In dystrophin-deficient muscle, the costameric scaffold of spectrin in the well-preserved fibers appeared normal, indicating that spectrin can be correctly localized in the absence of dystrophin and that the subcellular spectrin organization does not primarily depend on dystrophin expression. The regular organization and the correlation of spectrin costameres to the Z-bands was notable even in stretched Duchenne muscular dystrophy (DMD) muscle. On the other hand, single teased muscle fibers of DMD muscle showed various degrees of morphological alterations of the costameric network, ranging from a focal disarray to complete loss of costameric organization. Because these findings indicate that the costameric spectrin scaffold undergoes secondary changes during the course of the dystrophic process in dystrophin-deficient muscle, spectrin staining of isolated muscle fibers may also serve as a tool to monitor the effect of gene therapy experiments at the single fiber level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010050699
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  • 7
    Electronic Resource
    Electronic Resource
    Reinnervation of cat pacinian corpuscles after nerve crush (1997)
    Springer
    Acta neuropathologica 93 (1997), S. 285-293 
    Details
    ISSN: 1432-0533
    Keywords: Key words Pacinian corpuscles ; Reinnervation after ; axotomy ; Regenerated axon terminals ; Ultrastructure ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The reinnervation pattern of crural pacinian corpuscles was examined by light and electron microscopy in eight adult cats of both sexes 3–18 months after sciatic nerve crush. Normal pacinian corpuscles are each supplied with a single myelinated axon and a single cylindrical axon terminal which may branch in the distal part of the inner core. Reinnervation of these vibroreceptors was very satisfactory after sciatic nerve crush: in a sample of 68 corpuscles examined 3–18 months after the operation, 92.6% were found reinnervated, while only 7.4% remained denervated. At the nerve entry, 84.2% of the reinnervated corpuscles were supplied with a single myelinated axon, while 15.8% received two myelinated axons; some of the axons branched before or after entering the inner core. Near the mid-level of the inner core, 60.3% of 63 reinnervated corpuscles were innervated with a single axon terminal, 22.2% were biterminal, while 17.5% had three or more terminals. Regenerated axon terminals induced the formation of thin lamellar layers in the axial region of the original core and, exceptionally, also at the outer aspect of the original core. In monoterminal corpuscles, the shape and ultrastructure of regenerated endings resembled those of normal controls, whereas in multiterminal corpuscles their shape and profiles were variable. In contrast to previous reports, reinnervated corpuscles did not ultimately become monoterminal. On the contrary, the mean number of 1.3 terminals found in reinnervated crural corpuscles at 3–5 months increased to 1.9 terminals per corpuscle 6–18 months after axotomy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010050616
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  • 8
    Electronic Resource
    Electronic Resource
    Characterization of a prolonged regenerative attempt by diffusely injured axons following traumatic brain injury in adult cat: a light and electron microscopic immunocytochemical study (1997)
    Springer
    Acta neuropathologica 94 (1997), S. 329-337 
    Details
    ISSN: 1432-0533
    Keywords: Key words Regeneration ; Diffuse axonal injury ; GAP43 ; Neurofilament ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Traumatic brain injury in animals and humans is well known to cause axonal damage diffusely scattered throughout the brain without evidence of other brain parenchymal change. This observation has prompted some to posit that such damaged axons are well positioned to mount a regenerative attempt. The present study uses an immunocytochemical marker specific for regenerating neurites to explore this issue. Further, in an attempt to expedite and enhance any potential regenerative effort, this study evaluates the efficacy of intrathecally applied nerve growth factor. Three sets of experiments were performed in adult cats. One group of animals was subjected to moderate fluid percussion brain injury and followed for 7 or 14 days post injury, with the continuous intraventricular infusion of nerve growth factor delivered by implanted osmotic pumps. These animals were compared to a second group of time-matched, sham-operated animals receiving artificial cerebrospinal fluid infusion. To assess axonal damage immunohistochemical staining for the low molecular weight neurofilament subunit (NF-L) was carried out using an NR4 monoclonal antibody. To localize axons exhibiting a regenerative response immunohistochemical staining for the growth associated protein GAP43 was employed. In sham controls, at the light microscopic level NF-L-immunoreactive axonal swellings were numerous at 7 days, but by 14 days post injury their frequency declined markedly. In contrast, GAP43-immunoreactive, disconnected reactive axonal swellings were rarely observed at 7 days but were numerous at 14 days. Ultrastructural analysis at 14 days post injury of carefully matched sections revealed reactive axons demonstrating sprouting consistent with a regenerative effort. Analysis of tissue from animals of 14 days of survival indicated that supplementation with nerve growth factor did not appear to enhance the capacity of damaged brain axons to mount a regenerative attempt. Rather, it appears that regenerative efforts seen reflect a spontaneous response. A third group of adult cats, subjected to the same injury but not subjected to osmotic pump implantation, was allowed to survive for 22–28 days. Animals in this group also demonstrated GAP43 immunoreactivity in reactive axonal swellings in the brain stem. This study demonstrates that diffusely injured axons can mount a sustained regenerative attempt that is associated with a reorganization of their cytoskeleton and accompanied by an up-regulation of growth-associated proteins.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010050715
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  • 9
    Electronic Resource
    Electronic Resource
    Morphological and functional analysis of PTA granules in human NK cells (1997)
    Springer
    Anatomy and embryology 196 (1997), S. 215-226 
    Details
    ISSN: 1432-0568
    Keywords: Key words Natural killer cells ; Ultrastructure ; Parallel tubular arrays ; Perforin ; Granzyme B ; Chondroitin sulfate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Human natural killer (NK) cells contain unique granules with parallel tubular arrays (PTA granules) of approximately 30 nm diameter that can be seen only by electron microscopy. In order to clarify the role of PTA granules in NK cell-mediated cytolysis we examined these structures with regard to frequency and expression of lytic proteins (perforin, granzymes). NK cells (CD3−, CD16+, CD56+) were obtained from heparinized blood of healthy donors and enriched by double-step negative selection using mAb coupled to magnetic beads. PTA granules were found in 31.3% of freshly separated NK cells. When NK cells were cultivated, even in the presence of various stimulating agents (rhIL-2, rhIL-4, rhIL-6, rhIL-12, GM-CSF, rhIFNα, anti-CD16 mAb, dexamethasone), PTA granules disappeared and transformed into conventional primary lysosomes. By immune electron microscopy using antibodies directed against perforin and granzyme B we observed distinct immuno-reactivity in the tubules and in the tubule-associated faintly electron-dense matrix of PTA granules. Immuno-labelling for perforin and granzyme B was also found in the fine granular matrix of primary lysosomes. Finally, we tested the distribution of chondroitin 4-sulfate which is suggested to inactivate lytic proteins. Immuno-reactivity for chondroitin 4-sulfate was detected only in the moderately electron-dense matrix but not in the tubules of PTA granules. These observations indicate that perforin and granzyme B are stored in an inactive form in PTA tubules due to highly ordered paracrystalline protein folding. As soon as the tubules decay the lytic proteins are kept in an environment of chondroitin 4-sulfate for inactivation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004290050092
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  • 10
    Electronic Resource
    Electronic Resource
    Intracytoplasmic chromophobe inclusion bodies in an anaplastic meningioma (1997)
    Springer
    Acta neuropathologica 93 (1997), S. 421-425 
    Details
    ISSN: 1432-0533
    Keywords: Key words Meningioma ; Inclusion body ; Vimentin ; Immunocytochemistry ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Intracytoplasmic inclusion bodies are rarely found in meningiomas. A 74-year-old woman had an anaplastic meningioma with intracytoplasmic chromophobe inclusion bodies (CIB) histologically. These CIB were various shapes, e.g. round, teardrop-like, fusiform, horseshoe-like, crescentic and perinuclear. The size of CIB ranged from 7 to 14 μm and the nuclei of the tumor cells with CIB were often eccentric. Most CIB were immunopositive only for vimentin, staining more intensely than surrounding cytoplasm in a comparative study using adjacent sections stained with hematoxylin-eosin and vimentin. CIB showed loosely textured filamentous structures which were in parallel and entangled arrangements ultrastructurally. The diameter of the filaments was 13–14 nm and they were thicker than normal intermediate filaments. Moreover, these filaments appeared to be studded with granular and fuzzy substances. These findings suggest that CIB are mainly composed of abnormally synthesized and arranged vimentin filaments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010050634
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  • 11
    Electronic Resource
    Electronic Resource
    Ultrastructural concomitants of hypoxia-induced angiogenesis (1997)
    Springer
    Acta neuropathologica 93 (1997), S. 579-584 
    Details
    ISSN: 1432-0533
    Keywords: Key words Hypobaric hypoxia ; Cerebral ; microvasculature ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Prolonged hypoxia results in structural and functional adaptive responses to improve tissue oxygen delivery. Structural changes within the brain include vascular proliferation and elongation. The aim of the current study was to investigate whether ultrastructural changes in capillary walls also occur as part of the adaptive response. Adult rats were exposed to 2 or 3 weeks of moderate hypobaric hypoxia at 0.5 atmospheres and their cerebral microvasculature examined using quantitative ultrastructural methods. We found that hypoxic rats had an 18% increase in their brain capillary diameter but no change in endothelial wall thickness, basement membrane thickness, or coverage of the endothelial wall by pericytes. The increased diameter of cerebral capillaries may play an important role in decreasing the resistance to capillary perfusion which is brought about by the increased erythrocyte fraction in the blood of hypoxic rats. Ultrastructural features relevant to the blood-brain barrier were maintained in hypoxic rats. Pericytes, that are thought to form a second line of defense in the blood-brain barrier, maintained their numerical and size relationships to the endothelial cells. Endothelial junctions were unchanged and endothelial vesicles were somewhat lower in density than normal at 2 weeks of hypoxia, but had regained their normal density by 3 weeks. Mitochondria of the brain capillary endothelial cells maintained normal numerical and volume densities in hypoxia, but the mitochondria of the surrounding neuropil were decreased significantly by about 30%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010050654
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  • 12
    Electronic Resource
    Electronic Resource
    Central neurocytoma: an immunohistochemical, ultrastructural and cell culture study (1997)
    Springer
    Acta neuropathologica 94 (1997), S. 425-435 
    Details
    ISSN: 1432-0533
    Keywords: Key words Cell culture ; Central neurocytoma ; Histogenesis ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To clarify the histogenesis and differentiation potential of central neurocytoma, a pathological investigation of seven tumors from three patients was conducted using immunohistochemistry and ultrastructural analysis in addition to systematic in vitro studies. Six tumors were studied immunohistochemically and five were examined ultrastructurally. All cases that were immunostained were positive for synaptophysin in nuclear-free neuropil islands. In five tumors, a few tumor cells, in addition to reactive astrocytes, were positive for glial fibrillary acidic protein (GFAP). Vimentin staining was also positive in a few tumor cells of five specimens. Neurofilament staining was always negative. All cases for which ultrastructure was examined showed various synaptic abnormalities. Cultured cells were subdivided into three distinct tumor cell types: neuronal cells which stained for neurofilament proteins with neurosecretory granules; small flat undifferentiated cells with a high nuclear-cytoplasmic ratio and scant cytoplasmic organelles; and small round or multipolar astrocytic cells with 10-nm intermediate filaments which stained for GFAP. Our tissue culture studies disclosed that cultured neurocytoma cells form a cellular mosaic similar to subependymal plate layers that are composed of mitotically active cells, neurons and glia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010050729
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  • 13
    Electronic Resource
    Electronic Resource
    The ultrastructure of skin from a patient with mucopolysaccharidosis IIID (1997)
    Springer
    Acta neuropathologica 93 (1997), S. 210-213 
    Details
    ISSN: 1432-0533
    Keywords: Key words Mucopolysaccharidosis IIID ; Skin ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Mucopolysaccharidosis IIID (MPS-IIID) is the rarest of the MPS-III syndromes. It is caused by deficient activity of lysosomal N-acetylglucosamine-6-sulfatase (G6S). To date, the clinical and biochemical features of seven patients with MPS-IIID have been reported, but no biopsy or autopsy findings have been described. The purpose of this report is to define the ultrastructure of affected cells seen in a skin biopsy from a 14-year-old boy. The child presented with progressive mental deterioration, hyperactivity and mild to moderate dysmorphism. The diagnosis of a mucopolysaccharidosis was suggested, but the initial urine analyses were negative for elevated mucopolysaccharides, and only the third analysis showed abnormal excretion of heparan sulfate. Because of the diagnostic difficulties posed by this case, a skin biopsy was performed for morphological and biochemical studies. Numerous vacuoles were noted in Schwann cells, fibroblasts, smooth muscle cells, eccrine gland and ductal epithelium in resin-embedded sections stained with toluidine blue. Ultrastructurally, many lysosomes were distended with abundant, fibrillar material. Occasionally, lamellated membranous structures were present within the same lysosomes. These findings are consistent with those seen in other forms of MPS, in which the lysosomal storage occurs predominantly, but not exclusively, in mesenchymal cells. Furthermore, deficient activity of G6S was confirmed in cultured skin fibroblasts. This study demonstrates that electron microscopy of skin biopsies is a useful method for identification of patients with clinical features of MPS-IIID whether or not heparan sulfaturia is present.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010050605
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  • 14
    Electronic Resource
    Electronic Resource
    An unusual meningioma variant with glial fibrillary acidic protein expression (1997)
    Springer
    Acta neuropathologica 94 (1997), S. 499-503 
    Details
    ISSN: 1432-0533
    Keywords: Key words Meningioma ; Immunohistochemistry ; Glial fibrillary acidic protein ; Ultrastructure ; Intercellular lumina
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We studied a recurrent meningioma located in the right frontal lobe. The tumor showed high cellularity and the cells had plump, hyalinous cytoplasm. Immunohistochemically, almost all the tumor cells were positive for epithelial membrane antigen and vimentin, and unexpectedly, glial fibrillary acidic protein (GFAP). Ultrastructural investigation revealed abundant 8- to 10-nm filaments in the cytoplasm. Conspicuous interdigitations with numerous desmosomes were present. Frequently, intracellular and intercellular lumina lined by microvilli were also found. We considered the present case to be an unusual variant of meningioma with GFAP expression. A few cases of meningioma with triple expression of GFAP, vimentin and cytokeratin have been reported previously. However, the present case showed obvious pathological differences from these, and had no immunoreactivity for cytokeratin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010050739
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  • 15
    Electronic Resource
    Electronic Resource
    Ultrastructural changes in rat locus coeruleus induced by chronic opioids (1997)
    Springer
    Acta neuropathologica 94 (1997), S. 109-115 
    Details
    ISSN: 1432-0533
    Keywords: Key words Locus coeruleus ; Ultrastructure ; Dihydroetorphine ; Morphine ; Opioids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The locus coeruleus (LC) is a major noradrenergic nucleus in the brain. The activity of the LC neurons is chronically regulated by opioids. So far, very little is known about the morphological changes induced by chronic treatment with opioids. In the present study, the effects of chronic treatment with morphine and dihydroetorphine, a new narcotic analgesic with lower physical dependence potential than morphine, were investigated on the ultrastructure of the rat LC. Rats received saline or increasing doses of morphine or dihydroetorphine for 5 days by twice daily subcutaneous injections. Withdrawal was precipitated in half of the opioid-treated rats by a single intraperitoneal injection of naloxone 4 h after the last injections of opioids. The ultrastructure of the LC was examined by electron microscopy. Results showed that chronic morphine treatment induced a marked injury to the LC neurons. The primary changes in the cell body were the indentation of nuclei, the fragmentation and degranulation of rough endoplasmic reticulum, as well as the disaggregation of polyribosomes. Myelinoid bodies were seen in the processes. An accumulation of presynaptic vesicles was observed in some of the terminals which formed synaptic junctions with the LC neurons as compared to the normal controls. Naloxone-precipitated withdrawal from morphine did not stop the morphine-induced injury on the LC neurons except that less accumulation of presynaptic vesicles occurred. Chronic dihydroetorphine treatment only induced a slight change in the ultrastructure of the LC neurons. These results indicate that the LC neurons are more vulnerable to chronic treatment with morphine than to that with dihydroetorphine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010050681
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  • 16
    Electronic Resource
    Electronic Resource
    Immunocytochemical and ultrastructural study of pericapillary rosettes in amyotrophic lateral sclerosis (1997)
    Springer
    Acta neuropathologica 94 (1997), S. 338-344 
    Details
    ISSN: 1432-0533
    Keywords: Key words Amyotrophic lateral sclerosis ; Pericapillary rosette ; Immunocytochemistry ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This report concerns a comparative immunocytochemical and ultrastructural investigation on pericapillary rosettes (PR) in the lumbar spinal cords of 21 patients with amyotrophic lateral sclerosis (ALS) and 18 age-matched neurologically normal individuals. The purpose of the study was to determine the alteration of PR in relation to the neuronal loss in ALS. The PR were almost always positively immunostained for phosphorylated neurofilament, and some PR immunoreacted with antibodies to synaptophysin and β-amyloid precursor protein. This finding suggests that axonal transport, whether fast or slow, is impaired in the terminal portion of the axon that reaches the capillaries. Some PR were also positively immunostained by the antibody against ubiquitin, anti-calbindin-D 28 K antibody, anti-parvalbumin antibody and the antibody to superoxide dismutase 1. Morphometrically, the number of PR in the anterior horns and lateral column was markedly diminished in ALS compared with controls. At the ultrastructural level, the PR consisted mostly of unmyelinated degenerated axons, and were frequently found outside the basal laminae of the endothelial cell and of the astrocytic foot processes on the opposite side of the capillary, and less often in the space between the two basal laminae. The data indicate that the fate of PR is intimately associated with the neuronal loss of the anterior horn cells and with degenerative change of nerve fibers extending from their mother neurons to the capillaries.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010050716
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  • 17
    Electronic Resource
    Electronic Resource
    The mineralization of mantle dentine and of circumpulpal dentine in the rat: an ultrastructural and element-analytical study (1997)
    Springer
    Anatomy and embryology 195 (1997), S. 289-297 
    Details
    ISSN: 1432-0568
    Keywords: Key words Mineralization ; Dentine ; Ultrastructure ; Elementanalysis ; Collagen fibrils
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The purpose of this study was to compare the biomineralization of circumpulpal dentine with that of mantle dentine by ultrastructural and element-analytical techniques. Forty upper second molar germs of 10-day-old albino rats were cryofixed in liquid nitrogen-cooled propane and embedded in resin after freeze drying. Semithin dry sections were cut for analyzing the calcium and phosphorus concentration in initial mantle dentine, at the mineralization front of circumpulpal dentine, in the middle region of circumpulpal dentine and in mantle dentine peripheral to circumpulpal dentine. For the morphological evaluation of mineral deposits we compared ultrathin and unstained sections of cryofixed molars with chemically fixed molars. For both dentine types it was found that they develop via identical steps of mineral formation at collagen fibrils and non-collagenous matrix molecules. In circumpulpal dentine no globular mineral protrusions along the mineralization front (i.e. calcospherites) and no indications of interglobular dentine at the transition from circumpulpal dentine to mantle dentine were present. The von Korff fibres were not only visible in mantle dentine but also in circumpulpal dentine. Matrix vesicles were present only during the formation of an initial coherent layer of mantle dentine and could not be observed during successive formation of mantle dentine and circumpulpal dentine. The element-analytical data did not demonstrate any difference in the mineral content between the two dentine types. Therefore, we conclude that mantle dentine and circumpulpal dentine in the rat molar possess a high degree of structural and chemical similarity and that only the extent of terminal branching of the odontoblast processes gives an approximate estimation of the thickness of mantle dentine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004290050048
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  • 18
    Electronic Resource
    Electronic Resource
    Crural Herbst corpuscles in chicken and quail: numbers and structure (1997)
    Springer
    Anatomy and embryology 196 (1997), S. 323-333 
    Details
    ISSN: 1432-0568
    Keywords: Key words Herbst mechanoreceptors ; Sensory axons ; White Leghorns ; Japanese quail ; Ultrastructure ; Quantitative study
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Herbst corpuscles were studied in the crural region of perinatal and adult chicken and quail in order to find out their number and dimensions and to learn more about their structure, especially in relation to size. Crural corpuscles are arrayed in an encapsulated string between tibia and fibula. They are closely packed together; a small number of corpuscles is found apart from the string, often attached to the periost. The strings of corpuscles are approximately 40 mm long in adult chicken and 20 mm long in the quail. The crural region of the chicken contains 382.8 ± 90.9 (mean ± SD) corpuscles, the numbers ranging from 301 to 582; in the quail, the mean number is 119.2 ± 27.9, with a range from 83 to 167 corpuscles. In the chicken, one axon supplies an average of 1.60 corpuscles; in the quail, the relation of axons to corpuscles is approximately 0.92. In both species, final numbers of crural corpuscles are already attained before hatching and no difference is found in the mean number and range of corpuscles between perinatal and adult birds. In both chicken and quail, individual strings contain corpuscles of various sizes, from large to very small. The chicken corpuscles are generally twice as large in diameter and often longer than those of the quail. The corpuscles are composed of an axon terminal that projects two rows of axonal spines into the clefts of the inner core and ends with an ultraterminal bulb; the terminal is surrounded with a bilaterally symmetrical inner core, amorphous inner space containing collagen fibrils of various thickness, and a capsule. Large chicken corpuscles contain inner cores composed of up to 100 lamellae, while quail inner cores have half that number at the most. The capsules are usually composed of 8 to 10 lamellar layers in both species, but they are thicker in the chicken than in the quail. The possible functional significance of individual structural components of Herbst corpuscles is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004290050101
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  • 19
    Electronic Resource
    Electronic Resource
    Electron microscopy and morphometry enhances differentiation of epidermolysis bullosa subtypes. With normal values for 24 parameters in skin (1997)
    Springer
    Archives of dermatological research 289 (1997), S. 631-639 
    Details
    ISSN: 1432-069X
    Keywords: Key words Diagnosis ; Mechanobullous disease ; Skin ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Electron microscopy combined with morphometry was used to establish values for 24 parameters in normal skin. These results were compared with those similarly obtained from samples of epidermolysis bullosa with a view to facilitating classification of the disease. Six of the eight subtypes of epidermolysis bullosa investigated could be differentiated. Four subtypes showed values for structural components in intact skin which were outside the normal range: (1) epidermolysis bullosa simplex generalisata gravis (hemidesmosomes); (2) epidermolysis bullosa dystrophica Pasini and (3) Cockayne-Touraine (anchoring fibrils); and (4) epidermolysis bullosa acquisita (anchoring fibrils, hemidesmosomes, and lamina lucida and lamina densa aspects of the dermoepidermal junction). Two subtypes revealed specific features which could be assessed qualitatively: distinctive, circumscribed, clumped tonofilament bodies were present in basal keratinocytes from epidermolysis bullosa herpetiformis Dowling-Meara and thick (30 nm diameter) cross-striated anchoring fibrils were absent in epidermolysis bullosa dystrophica generalisata gravis. Epidermolysis bullosa simplex Köbner and Weber-Cockayne forms could not be distinguished.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004030050252
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  • 20
    Electronic Resource
    Electronic Resource
    Waxy corn starch affecting texture and ultrastructure of sardine surimi gels (1997)
    Springer
    Zeitschrift für Lebensmittel-Untersuchung und -Forschung 204 (1997), S. 121-128 
    Details
    ISSN: 1431-4630
    Keywords: Key words Surimi ; Sardine ; Starch ; Texture ; Water holding capacity ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  The effect of waxy corn starch (WCS) on the texture, water-holding capacity and microstructure of sardine (Sardina pilchardus) surimi gels in two different systems was studied. In the type A system, increasing amounts of WCS (2, 4, 6 or 8 g/100 g surimi) were added to surimi while maintaining the gel moisture constant at 78%; in the type B system, WCS was added without correcting the gel moisture. Gels were made using two different heat treatments [heat-induced setting (HS) and direct cooking (DC)]. When starch was replaced by surimi (type A) and a heat treatment was applied that favoured formation of a preliminary actomyosin (AM) network (i.e. HS), gel strength (GS) was lower than in the control and decreased as more starch was added, despite an increase in the amount of water held by the gel. Scanning electron microscopy (SEM) showed that the matrix network was fibrillar with a globular surface. Starch appeared to be totally gelatinized and surrounded by a continuous matrix. When the amount of dry matter in gels was increased (type B), in no case did starch have a reinforcing effect, despite an increasing water-holding capacity; SEM showed a denser continuous matrix surrounding the gelatinized starch. Both types of gel made using the heat treatment that allows simultaneous gelling of surimi and gelatinization of starch (i.e. DC) exhibited much poorer GS than did HS gels, while addition of starch made practically no difference to gel texture. The findings suggest that the effect of starch is related to the type of gel matrix that forms upon addition of ingredients. Although such gels contained more water or dry matter, their texture parameters were lower, possibly because of the type of network formed by sardine surimi. Nonetheless, gels of acceptable quality were successfully made with added starch by incorporating less surimi.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002170050048
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  • 21
    Electronic Resource
    Electronic Resource
    An ultrastructural study of the mature spermatozoid of the fern Asplenium trichomanes L. subsp. trichomanes (1997)
    Springer
    Sexual plant reproduction 10 (1997), S. 142-148 
    Details
    ISSN: 1432-2145
    Keywords: Key words Asplenium trichomanes L. subsp. trichomanes ; Ferns ; Spermatozoids ; Flagella ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Asplenium trichomanes L. subsp. trichomanes spermatozoids are spirals of about five turns. Keels link the elements of the microtubular ribbon with the plates of the lamellar layer (LL) which are uninterrupted, parallel and curved with an inner angle of about 150°. Electron-opaque filaments connect the microtubules of the multilayered structure (MLS) and the osmiophilic crest, the LL and the MLS-associated mitochondrion and the latter and the plasmalemma. The nucleus occupies the 2.5–3 posterior turns and has an inner honeycomb-shaped chromatin mass and an outer highly condensed chromatin mass with randomly scattered electron-transparent areas. The basal bodies of the ca. 50 flagella are bounded by a reticulum of granular material which forms a plug inside their proximal region; the proximal region of the flagellum has a 9 + 0 pattern. The axoneme has a 9 + 2 pattern.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004970050081
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  • 22
    Electronic Resource
    Electronic Resource
    Mechanical isolation and ultrastructural characterization of viable egg cells in Plumbago zeylanica (1997)
    Springer
    Sexual plant reproduction 10 (1997), S. 368-373 
    Details
    ISSN: 1432-2145
    Keywords: Key words Egg-cell isolation (angiosperm) ; Micromanipulation ; Plumbagozeylanica ; Viable egg ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  A protocol for isolating viable eggs in Plumbago zeylanica by mechanical dissection is reported. The optimum solution for isolation was 0.8 M mannitol + 10 mM MOPS + 10 mM CaCl2, (pH 4.5–5.0) with an osmolality of 860–940 mmol/kg. Eggs retain their viability for at least 24 h. Isolated eggs were true protoplasts without cell walls and could tolerate osmolality of 437 mmol/kg to 965 mmol/kg. Observation of the isolated eggs using transmission electron microscopy indicated that they were well preserved and reflected the ultrastructure of physiologically active cells, displaying features similar to those of in vivo egg cells. Notable differences include the absence of a filiform apparatus and the accumulation of dense particles in the plastids, which was most conspicuous in egg cells that were damaged during isolation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004970050111
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  • 23
    Electronic Resource
    Electronic Resource
    Ultrastructural changes in motor endplates of the lumbrical muscles of rats induced by a microsomal Ca2+ ATPase inhibitor, 2,5-di(tert-butyl)-1,4-hydroquinone (1997)
    Springer
    Archives of toxicology 72 (1997), S. 115-118 
    Details
    ISSN: 1432-0738
    Keywords: Key words 2 ; 5-di(tert-butyl)-1 ; 4-Hydroquinone ; Ca2+ ATPase inhibitor ; Neurotoxicity ; Ultrastructure ; Motor endplate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Female Wistar rats were treated orally for 5 days with 80 mg/kg body weight of 2,5-di(tert-butyl)-1,4-hydroquinone (DTBHQ), a microsomal Ca2+ ATPase inhibitor. Motor endplates of the lumbrical muscles were examined by light and electron microscopy. There was a decrease in body weight in the treated rats from the first day after administration, and toxic signs appeared after the third day, such as adoption of a prone position, salivation, lacrymation, and an abnormal gait and/or muscle weakness. No remarkable macroscopic or light microscopic changes were noted in the lumbrical muscles as well as other peripheral nerves of hind legs of the treated rats killed 1 day after the last DTBHQ treatment. Ultrastructurally, neurotoxicity characterized by loss of synaptic vesicles and mitochondria in the motor endplates, and by destruction of the motor terminals was detected in the lumbrical muscles of the treated rats. These results strongly indicate that DTBHQ targets the motor endplates in the rat lumbrical muscles and suggest that the resultant damage is responsible for the appearance of neurological signs, such as an abnormal gait and loss of muscle control.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002040050477
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  • 24
    Electronic Resource
    Electronic Resource
    Thermal latent coordination compounds (1997)
    Springer
    Journal of thermal analysis and calorimetry 50 (1997), S. 569-586 
    Details
    ISSN: 1572-8943
    Keywords: crystal structure ; metal(II) picolinate and quinaldinate ; thermal degradation of imidazole and pyrazole complexes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Complexes of the type M(Pa)2(HAz)2 and M(QA)2(HAz)2 (M=cobalt(II) and nickel(II); HPa=picolinic acid, HQa=quinaldic acid; HAz=azoles like imidazole (Him), pyrazole (HPz), benzimidazole (HBzIm) etc.) show a similar thermal behaviour. In the first step of decomposition the corresponding azolinium picolinates or quinaldinates (H2AzPa, H2AzQa) are split off with formation of polymeric mixed ligand complexes M(Pa)(Az) or M(Qa)(Az). X-ray analysis of Co(Qa)2(HBzIm)2 XIIIa illustrates a proton transfer and a subsequent thermal removal of benzimidazolinium quinaldinate (H2BzImQa): Hydrogen bridges from pyrrole nitrogen of the benzimidazole to the non-coordinated oxygen of the quinaldinate predetermine the thermal initiated proton transfer. The high volatility of the heterocyclic acids and the nitrogen coordination are responsible for the formation of the mixed ligand complex Co(Qa)(BzIm) XIVa. Exceptions are the complexes M(Pa)2(HPz)2 XIa-b and M(Qa)2(HIm)2 XVIIa-b. Pyrazole is eliminated from the complexes XIa-b with formation of the solvent-free inner complex M(Pa)2 XIIa-b. From compounds XVIIIa-b quinaldic acid or their decomposition products are split off and a high temperature modification of M(Im)2 XVIIIa-b is formed at elevated temperature. XVIIIa-b are decomposed to the cyanides M(CN)2 similarly to the thermal behaviour of Cu(Im). In the first step the thermal degradation of imidazole and pyrazole adducts of copper(II) picolinates and quinaldinates is characterized by the elimination of azoles. The reason for this thermal behaviour is the weaker coordination of the azole heterocycles in copper chelate compounds.
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    URL: http://dx.doi.org/10.1007/BF01979029
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  • 25
    Electronic Resource
    Electronic Resource
    Structures and tautomeric interconversions of anthraquinone imine derivatives (1997)
    Springer
    Structural chemistry 8 (1997), S. 197-204 
    Details
    ISSN: 1572-9001
    Keywords: Tautomerism ; anthraquinone ; crystal structure ; semiempirical computations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Substituted 1-hydroxy-9,10-anthraquinone-9-imines have been found to exhibit tautomeric interconversions between the 9,10- and 1,10-quinonoid forms in the solid state as well as in solution. Single-crystal X-ray crystallography was used to study the structures of 4-(N-acetyl-p-tolylamino)-9-amino-1,10-anthracenedione and 4-hydroxy-1-phenylamino-10-mesitylimino-9(10H)-anthracenone at ambient and low temperatures. The former compound gave crystals belonging to the monoclinic space group P2l/c and, at 295 K,a=9.684(2),b=16.371(3),c=12.097(2) å,Β=110.41(1)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02263507
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  • 26
    Electronic Resource
    Electronic Resource
    Synthesis and structure of 5-methoxy-4-methylbenzopsoralen (1997)
    Springer
    Structural chemistry 8 (1997), S. 453-457 
    Details
    ISSN: 1572-9001
    Keywords: Benzopsoralen ; photochemotherapeutic agent ; crystal structure ; molecular mechanics ; AM1 theoretical calculations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract 5-Methoxy-4-methyl-2H-benzofuro[3,2-g]benzo-1-pyran-2-one was synthesized and its crystal structure was determined and compared with the optimal conformation arrived at by MM and AM1 theoretical calculations. The latter indicated that the tetracyclic skeleton is planar with total length (C2–C8) 9.23 å, and that the line joining the conters of the terminal-benzene and furan rings makes an angle of 30.5
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02311704
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  • 27
    Electronic Resource
    Electronic Resource
    Ultrastructural study of human herpesvirus-7 replication in tissue culture (1997)
    Springer
    Virchows Archiv 430 (1997), S. 417-426 
    Details
    ISSN: 1432-2307
    Keywords: Key words HHV-7 ; Viral replication ; Virus morphology ; Ultrastructure ; Herpesviruses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Human herpesvirus 7 (HHV-7) was grown in a CD4+ lymphoblastic cell line (SupT1) and in cord blood mononuclear cells (CBMC). Virus infection was demonstrated by immunohistology with positive control sera, with monoclonal antibodies and by in situ hybridization for viral DNA. Cytopathic effects following HHV-7 infection generally resemble those after HHV-6 infection but are less pronounced. The ultrastructural appearance of HHV-7 and the replicative stages were similar to those described by Kramarsky and Sander for HHV-6. There were some minor discrepancies, including quite an extensive and space-filling tegument, a slightly different structure of the nucleoid, the frequent finding of nucleocapsids without any visible core and apparently scarce or delicate spikes on the envelope. These differences may suggest HHV-7 rather than HHV-6, but this finding needs confirmation. Mature HHV-7 particles measured 170 nm in diameter, with nucleocapsids of 90–95 nm and a tegument of about 30 nm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004280050051
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  • 28
    Electronic Resource
    Electronic Resource
    Reversibility of omeprazole-evoked changes in the ultrastructure of ECL cells in the rat stomach (1997)
    Springer
    Cell & tissue research 291 (1997), S. 91-95 
    Details
    ISSN: 1432-0878
    Keywords: Key words ECL cells ; Omeprazole ; Granules/vesicles ; Ultrastructure ; Stomach ; Rat (Sprague Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  The ECL cells are histamine- and peptide hormone-producing endocrine cells in the rat oxyntic mucosa. They are rich in secretory vesicles and also contain microvesicles and electron-dense granules. They operate under the control of circulating gastrin. In the present study, we examined the ECL-cell ultrastructure after long term treatment with omeprazole, which is known to induce hypergastrinemia, and after withdrawal of the drug. Rats received omeprazole (400 µmol/kg per day, orally) for 16 days and were killed 1, 5, 20, or 40 days after the last dose of the drug. Oxyntic mucosal specimens were processed for electron microscopy. Electron micrographs of ECL-cell profiles were analyzed planimetrically. The ECL-cell profile area increased promptly in response to omeprazole, the secretory vesicles and granules were reduced in number and volume density, the microvesicles were unchanged in number but reduced in volume density, and vacuoles appeared. Within a week after stopping the omeprazole treatment, the numbers and volume densities of secretory vesicles and microvesicles returned to pre-stimulation values. Also, the vacuoles disappeared promptly. The ECL-cell profile area decreased below the pre-stimulation level within five days after stopping treatment, while, in contrast, the granules increased in number and volume density. Somewhat surprisingly, the cell size and the granule compartment did not return to normal until 40 days after stopping treatment.
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    URL: http://dx.doi.org/10.1007/s004410050982
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  • 29
    Electronic Resource
    Electronic Resource
    Exocytosis in the antral gastrin cells of mouse, rat, and guinea pig after stimulation by carbamylcholine (1997)
    Springer
    Cell & tissue research 289 (1997), S. 463-472 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Exocytosis ; Endocytosis ; Gastrin cells ; Carbamylcholine ; Ultrastructure ; Pyloric antrum ; Guinea pig (Hartley) ; Mouse (ICR) ; Rat (Sprague Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. In order to capture the exocytotic figures of gastrin cells in the pyloric antrum of the stomach, we examined antral cells of the mouse, rat, and guinea pig by electron microscopy following stimulation with the cholinergic secretagogue carbamylcholine. Increased numbers of omega profiles indicative of exocytosis were seen in the basal or lateral cell membrane after stimulation with carbamylcholine. The number of exocytotic figures in stimulated gastrin cells was higher in the guinea pig than in the mouse and rat. Coated and non-coated omega profiles and coated pits in the plasma membrane were smaller than the secretory granules. Omega profiles with or without electron-dense contents were seen. Coated and non-coated vesicles were often visible near the plasma membrane of stimulated gastrin cells in all three species, large cytoplasmic vacuoles also being found in the guinea pig. In the mouse pretreated with horseradish peroxidase, reaction deposits were observed in the omega profiles and in microvesicles near the plasma membrane. These results suggest that, after exocytosis, membrane retrieval and endocytosis occur in the gastrin cells.
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    URL: http://dx.doi.org/10.1007/s004410050892
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  • 30
    Electronic Resource
    Electronic Resource
    Development of striated rootlets during ciliogenesis in the human oviduct epithelium (1997)
    Springer
    Cell & tissue research 290 (1997), S. 39-42 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Ciliogenesis ; Striated rootlets ; Oviduct ; Ciliated cells ; Ultrastructure ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Striated rootlets in ciliated cells are conical banded structures composed of longitudinally aligned filaments. The formation of striated rootlets during ciliognesis in the human oviduct epithelium was studied by electron microscopy. Primitive rootlets appeared at the proximal side of basal bodies before or at the same time as ciliary budding. After the formation of several striations, the tip of the rootlets extended deeply toward the interior of the cell and became differentiated into two distinct parts, viz., the proximal conical part connected to the basal body and the distal fibrillar part. The periodicity of the striations in the fibrillar part was 68.5±2.95 nm, about 5 nm longer than that of the conical part (63.9±2.25 nm). The dark band in the striation was thicker in the fibrillar part than in the conical part. Since the fibrillar part was not observed in the mature cilium, this part was considered as being either degraded or changed into the conical part during ciliogenesis.
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    URL: http://dx.doi.org/10.1007/s004410050905
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  • 31
    Electronic Resource
    Electronic Resource
    Platelet/endothelial cell adhesion molecule-1 (PECAM-1) is localized over the entire plasma membrane of endothelial cells (1997)
    Springer
    Cell & tissue research 290 (1997), S. 623-631 
    Details
    ISSN: 1432-0878
    Keywords: Key words: PECAM-1 (platelet/endothelial cell adhesion molecule-1) ; Endothelium ; HUVEC (human umbilical vein endothelial cells) ; Myocardium ; Ultrastructure ; Human ; Rabbit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The subcellular localization of PECAM-1 in endothelial cells was examined by using advanced morphological techniques, such as confocal scanning microscopy and immunolabeling procedures for electron microscopy. The localization of PECAM-1 was studied immunohistochemically with five specific monoclonal antibodies and one polyclonal antibody (all anti-human) in human and rabbit myocardium and in isolated endothelial cells. In vivo, PECAM-1 was localized uniformly on the plasma membrane of all vascular endothelial cells, predominantly on the luminal side of vessels. No specific increase in labeling was found at sites of cell-to-cell contact. In vitro, primary isolated cells (human umbilical vein endothelial cells) showed continuous labeling of the entire cell membrane. Cells of higher passages were labeled in a manner similar to freshly isolated cells. Our findings refute the commonly accepted hypothesis that PECAM-1 is localized only at cell-to-cell contacts. Further, we have not been able to confirm the hypothesis regarding the important mechanical role of PECAM-1 in stabilizing the endothelial monolayer. Since PECAM-1 is also expressed on platelets and is known to bind to itself, the way in which PECAM-1-positive endothelial cells are protected against binding of PECAM-1-positive platelets remains unclear. In view of these findings, the role of PECAM-1 in the leukocyte migration cascade needs to be re-evaluated.
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    URL: http://dx.doi.org/10.1007/s004410050968
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  • 32
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    Electronic Resource
    The peroxisomes of the hepatopancreas in two species of chitons (1997)
    Springer
    Cell & tissue research 290 (1997), S. 655-664 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Peroxisomes ; Ultrastructure ; Digestive gland ; Acanthochiton crinita ; Lepidochitona cinerea (Mollusca ; Polyplacophora)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract . This paper presents the first description of peroxisomes in polyplacophorans. As in other molluscs, the hepatopancreas of chitons is composed of basophilic and digestive cells. In the basophilic cells, the endoplasmic reticulum is abundant and several Golgi stacks can be observed. These cells also possess secretion granules and vacuoles with spherites. The digestive cells are mainly characterized by the presence of many food vacuoles. Several peroxisomes were observed in the basophilic cells of Acanthochiton crinita, most of them almost spherical. The matrix is filled with tubular structures and a crystalline nucleoid is also present in these organelles. In the digestive cells of A. crinita, peroxisomes are also almost spherical and possess two kinds of nucleoids. One of them presents a diamond shape and a bundle of tubular structures forms a second kind of nucleoid, which shows an elongated form. In Lepidochitona cinerea, the peroxisomes of basophilic cells are spherical or oval. Within the matrix, a cluster of dense rods and a prismatic nucleoid were observed. In the digestive cells of this species, almost spherical or oval peroxisomes are common, but they are smaller than the peroxisomes of the preceding cells. Nucleoids were not detected, but a few dense rods could be observed in the matrix. In both cell types of the two species, catalase activity was detected in the peroxisomal matrix. In addition, the elongated nucleoid of A. crinita digestive-cell peroxisomes and the nucleoid of L. cinerea basophilic-cell peroxisomes also present catalase activity.
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    URL: http://dx.doi.org/10.1007/s004410050971
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  • 33
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    Electronic Resource
    Mucosal surface area in chicken small intestine during development (1997)
    Springer
    Cell & tissue research 290 (1997), S. 71-78 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Development ; Mucosal surface area ; Ultrastructure ; Villus ; Microvillus ; Morphometric analysis ; Chicken
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The mucosal surface area of the chicken duodenum, jejunum, and ileum was determined during development (from 1-day to 12-week-old animals). The morphometric analysis was performed at three magnification levels. The nominal (serosal) surface area was determined at the macroscopic level, from intestinal length and perimeter. Villus and microvillus amplification factors were estimated at light-microscopic and transmission electron-microscopic levels, respectively. The results show, during the period considered: (1) a similar increase in nominal surface area for the three segments (6.5 to 7.2-fold), (2) a rise followed by a slight decrease in the villus amplification factor in the third week of age in the duodenum, a two-fold increase of this variable in the jejunum and no significant developmental variations in the ileum, (3) an increase in the microvillus amplification factor of 1.5-fold in the duodenum and jejunum and of 1.2-fold in the ileum, although a pronounced decrease in the first week of age was observed in the three segments. In conclusion, total mucosal surface area increased, from 1 day to 12 week, 12- to 13-fold in the duodenum and ileum and 20-fold in the jejunum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050909
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    Electronic Resource
    Apical tubular network in the rat kidney proximal tubule cells studied by thick-section and scanning electron microscopy (1997)
    Springer
    Cell & tissue research 288 (1997), S. 317-325 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Kidney (proximal tubule) ; Apical tubule ; Endosome ; Ultrastructure ; Endocytosis ; Membrane recycling ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The apical cytoplasm of several absorbing epithelia contains well-developed apical tubules (AT) which contribute to membrane recycling from endocytic vacuoles to the apical cell membrane. In this study, we examined three-dimensional structures of the AT in rat kidney proximal tubule cells by transmission and scanning electron microscopy. In thin sections, the AT appeared as straight tubules with a rather constant diameter (70–90 nm), but others were curved and, occasionally, branching. No AT were labeled with the marker for the external cell surface (ruthenium red) or exhibited histochemical enzyme activity for lysosomal hydrolase (acid phosphatase). After intravenous injection of horseradish peroxidase, it was absorbed in the kidney proximal tubule cells and the AT were labeled with HRP reaction products. Stereo-viewing of the labeled AT in thick sections revealed that they formed an interconnected tubular network. Scanning electron microscopy allowed a three-dimensional view of the AT, in which a network of branching and anastomosing tubules was revealed. These observations indicate that the AT are intracellular endosomal compartments which form an extensive tubular network in the apical cytoplasm. The possibility that this apical tubular network serves as a large membrane store for membrane recycling is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050817
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    Electronic Resource
    Ultrastructural characterisation of cells specialised for nitrogen fixation in a non-heterocystous cyanobacterium,Trichodesmium spp. (1997)
    Springer
    Protoplasma 197 (1997), S. 76-85 
    Details
    ISSN: 1615-6102
    Keywords: Cell differentiation ; Immunolocalisation ; Nitrogenase ; Non-heterocystous cyanobacteria ; Trichodesmium ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Trichodesmium is the first described example of a filamentous cyanobacterium without heterocysts that contains cells specialised for nitrogen fixation. The ultrastructure of cells with and without nitrogenase were compared using primarilyTrichodesmium tenue Wille, but alsoT. thiebautii Gomont andT. erythraeum Ehrenberg et Gomont. Immunohistochemistry demonstrated that the cytoplasm of certain cells was densely labelled with antibodies against Fe-protein (dinitrogenase reductase). Comparative TEM-image analysis revealed that these cells were also distinguished by a denser thylakoid network, dividing the vacuole-like space into smaller units. The nitrogenase-containing cells also exhibited less extensive gas vacuoles as well as fewer and smaller cyanophycin granules compared to cells which lacked nitrogenase. Carboxysomes were present in both cell types in equal proportion. Longitudinal sections showed that cells with nitrogenase were arranged adjacent to each other, and that groups of cells with and without nitrogenase may coexist in the same trichome. The correlation between modifications in ultrastructure and the presence of nitrogenase suggests a new type of cyanobacterial cell specialisation related to nitrogen fixation. The results obtained also question the systematic affiliation of the genusTrichodesmium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01279886
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    Electronic Resource
    Ultrastructural localization of basic proteins ofBlastocystis hominis (1997)
    Springer
    Protoplasma 200 (1997), S. 31-34 
    Details
    ISSN: 1615-6102
    Keywords: Blastocystis hominis ; Central vacuole ; Accumulation ; Basic proteins ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Basic proteins ofBlastocystis hominis were detected by the ammoniacal silver and ethanolic phosphotungstic acid techniques using electron microscopy. The central vacuole showed many silver grains when treated with ammoniacal silver and an increased electron density when treated with phosphotungstic acid. The intensity of positive reactions correlated with the electron density of the central vacuole, because cells having an electron-lucent central vacuole showed no silver grain deposits. Since it is known that the concentration of electron-dense materials in the central vacuole increases during log phase of growth, and then decreases in stationary phase, this organelle must accumulate basic proteins during cell growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01280732
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  • 37
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    Electronic Resource
    Physiological and structural changes in the chloroplast of the green alga Micrasterias denticulata induced by UV-B simulation (1997)
    Springer
    Plant ecology 128 (1997), S. 55-64 
    Details
    ISSN: 1573-5052
    Keywords: Algae ; Chloroplast ; Micrasterias ; Photosynthesis ; Ultrastructure ; UV-B
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Exposure of postmitotic growing and non-growing cells of the unicellular green alga Micrasterias denticulata to different UV-B cut-off wavelengths together with simulated sunlight in a sun simulator has revealed a marked resistence of the algae against strong irradiation. While down to a cut-off wavelength of 284 nm irradiated during the most sensitive stage of cell development chloroplast ultrastructure remains unaffected, severe changes in arrangement and structure of stroma and grana thylakoids occur only at the lowest cut-off wavelengths of 280 and 275 nm. The structural alterations end up in a more or less complete desintegration of grana and stroma thylakoids with the remaining membraneous structures appearing in negative staining thus indicating drastic changes in membrane composition. Photosynthetic activity determined by chlorophyll fluorescence (ratio of variable to maximal fluorescence) and oxygen evolution responded more sensitively to UV-B irradiation. With decreasing UV cut-off wavelengths and prolonged incubation a decrease of photochemistry of PS II occured reaching its lowest values after 60 min at 275 and 280 nm. Oxygen production was even maintained under strong UV irradiation with a cut-off wavelenght of 275 nm up to 15 min. With prolonged UV-B treatment any activity was lost. HPLC separations of pigments exhibited the appearance of break-down products (mainly derivatives of chl b and chl a) with decreasing cut-off wavelength and increasing exposure time. The xanthophyll cycle pigments seemed to be unaffected at least for an irradiation period of 60 to 90 min at low UV cut-offs. Possible mechanisms of UV stress avoidance or protection are discussed with regard to the varying altitudes of the natural habitats of the algae.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009754722357
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  • 38
    Electronic Resource
    Electronic Resource
    The crystal and molecular structures of cellulose I and II (1997)
    Springer
    Glycoconjugate journal 14 (1997), S. 677-690 
    Details
    ISSN: 1573-4986
    Keywords: molecular dynamics ; crystal structure ; cellulose I and II
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The paper describes molecular dynamics (MD) simulations on the crystal structures of the Iβ and II phases of cellulose. Structural proposals for each of these were made in the 1970s on the basis of X-ray diffraction data. However, due to the limited resolution of these data some controversies remained and details on hydrogen bonding could not be directly obtained. In contrast to structure factor amplitudes in X-ray diffraction, energies, as obtained from MD simulations, are very sensitive to the positions of the hydroxyl hydrogen atoms. Therefore the latter technique is very suitable for obtaining such structural details. MD simulations of the Iβ phase clearly shows preference for one of the two possible models in which the chains are packed in a parallel orientation. Only the parallel-down mode (in the definition of Gardner and Blackwell (1974) J Biopolym 13: 1975-2001) presents a stable structure. The hydrogen bonding consists of two intramolecular hydrogen bonds parallel to the glycosidic linkage for both chains, and two intralayer hydrogen bonds. The layers are packed hydrophobically. All hydroxymethyl group are positioned in the tg conformation. For the cellulose II form it was found that, in contrast to what seemed to emerge from the X-ray fibre diffraction data, both independent chains had the gt conformation. This idea already existed because of elastic moduli calculations and 13C-solid state NMR data. Recently, the structure of cellotetraose was determined. There appear to be a striking similarity between the structure obtained from the MD simulations and this cellotetraose structure in terms of packing of the two independent molecules, the hydrogen bonding network and the conformations of the hydroxymethyl group, which were also gt for both molecules. The structure forms a 3D hydrogen bonded network, and the contribution from electrostatics to the packing is more pronounced than in case of the Iβ structure. In contrast to what is expected, in view of the irreversible transition of the cellulose I to II form, the energies of the Iβ form is found to be lower than that of II by 1 kcal mol-1 per cellobiose.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018509231331
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  • 39
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    Electronic Resource
    Ultrastructural study of the proboscis endothelium of Riseriellus occultus (Nemertea, Heteronemertea) (1997)
    Springer
    Hydrobiologia 365 (1997), S. 121-127 
    Details
    ISSN: 1573-5117
    Keywords: Riseriellus occultus ; Heteronemertea ; Proboscis ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have examined with transmission electron microscopythe epithelial layer exposed to the rhynchocoel fluidof the proboscis in the heteronemertine Riseriellus occultus. This epithelium is organized asa monociliated, pseudostratified myoepitheliumconsisting of two cell types: apically situatedmonociliated supportive cells and subapical myocyteslacking cilia. The low supportive cells form acontinuous adluminal sheet and reach with numerouscytoplasmic processes into the extracellular matrix;these cells are characterized by numerous, irregularlyshaped, apical folds projecting into the rhynchocoelfluid, delimiting broad extracellular spaces. Theauthors suppose that both apical and basal folds couldaccommodate stretching of the endothelium when theproboscis is everted. The apical folds of thesupportive cells increase the interface of these withthe rhynchocoel fluid; this feature, together with thepresence of pinocytotic vesicles in such cells,suggest that they could be involved in the exchange ofsubstances between the rhynchocoel fluid and theproboscis. The myocytes are scattered singly withinthe monociliated pseudostratified myoepithelium. Theyare situated between the supportive cells and thesubjacent extracellular matrix. Basement membraneseparating both cells types is lacking. Myofibrillarparts protrude basally from the myocyte somata. Themyofibrillar parts lie in direct apposition to theextracellular matrix, and are oriented circular to thelongitudinal axis of the proboscis. We consider themyocytes to be intra-epithelial, myoepithelial cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003101703985
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    Electronic Resource
    Immunohistochemical and electron microscopical characterization of stromal cells in nasopharyngeal angiofibromas (1997)
    Springer
    European archives of oto-rhino-laryngology and head & neck 254 (1997), S. 196-199 
    Details
    ISSN: 1434-4726
    Keywords: Nasopharyngeal angiofibroma ; Ultrastructure ; Myofibroblast ; Immunohistochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Twenty-eight cases of nasopharyngeal angiofibroma were studied immunohistochemically for cytoskeletal phenotyping of stromal cells. Electron microscopy was also used to study the ultrastructure of five of the tumors. All typical stromal cells showed intensive immunostaining for vimentin, but were negative for smooth muscle actin and desmin. Ultrastructurally, most of these cells appeared to be exclusively fibroblasts. However, in some areas stromal cells were seen that morphologically resembled myofibroblasts by their shapes and arrangement, and were characterized by the coexpression of vimentin and smooth muscle actin. Electron microscopy confirmed their myofibroblastic nature. The present study showed that the typical stromal cells in nasopharyngeal angiofibromas were fibroblasts and not myofibroblasts. In these tumors myofibroblasts occurred only focally, in connection with fibrotic areas and exclusively as a vimentin+/actin+ cytoskeletal phenotype. This indicates that myofibroblasts are not primary stromal tumor cells in nasopharyngeal angiofibromas, but occur due to regressive changes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00879273
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  • 41
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    Electronic Resource
    Structural maturation of the interface region between the stria vascularis and spiral ligament in the neonatal rat cochlea (1997)
    Springer
    European archives of oto-rhino-laryngology and head & neck 254 (1997), S. 73-77 
    Details
    ISSN: 1434-4726
    Keywords: Development ; Stria vascularis ; Spiral ligament ; Ultrastructure ; Rat cochlea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The ultrastructural morphology of the interface region between the stria vascularis (SV) and spiral ligament (SL) was examined in the neonatal rat cochlea via transmission electron microscopy. At postnatal day (PND) 3, morphology of both basal cells and fibrocytes was simple and immature. Only a small number of fibrocytes was observed in the SL. Intercellular junctions between basal cells and fibrocytes, and between adjacent fibrocytes, were few. At PND 7, the number of fibrocytes increased, and more organelles appeared within their cytoplasm. From PND 11 to 14, nuclei of the basal cells appeared to be more spindle-shaped and contained more heterochromatin. The cytoplasm of the fibrocytes was pale, and a greater number of cytoplasmic vesicles and mitochondria emerged. More intercellular junctions were observed between basal cells and fibrocytes at the interface region and between fibrocytes in the SL. By PND 21, the morphology of basal cells and fibrocytes and their intercellular junctionsappeared to be adult-like. These morphological observations correlate with previous reports on the functional maturation of the developing rat cochlea.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01526182
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  • 42
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    The molecular complex of dibenz[a,c]anthracene and trinitrobenzene (1997)
    Springer
    Structural chemistry 8 (1997), S. 141-147 
    Details
    ISSN: 1572-9001
    Keywords: Dibenzanthracene ; trinitrobenzene complex ; trinitrobenzene complex ; π-complex ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The crystal structure of the complex between the polycyclic aromatic hydrocarbon di-benz[a,c]anthracene and 1,3,5-trinitrobenzene is reported. The crystals are triclinic, space group P¯1 with unit cell dimensionsa=7.277(2) å,b=11.237(6) å, andc=13.902(5) å,α= 104.13(4)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02262849
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    Large differences are observed between the crystal and solution quaternary structures of allosteric aspartate transcarbamylase in the R state (1997)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 27 (1997), S. 110-117 
    Details
    ISSN: 0887-3585
    Keywords: small-angle scattering ; x-rays ; allosteric enzymes ; crystal structure ; rigid body modeling ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Solution scattering curves evaluated from the crystal structures of the T and R states of the allosteric enzyme aspartate transcarbamylase from Escherichia coli were compared with the experimental x-ray scattering patterns. Whereas the scattering from the crystal structure of the T state agrees with the experiment, large deviations reflecting a significant difference between the quaternary structures in the crystal and in solution are observed for the R state. The experimental curve of the R state was fitted by rigid body movements of the subunits in the crystal R structure which displace the latter further away from the T structure along the reaction coordinates of the T→R transition observed in the crystals. Taking the crystal R structure as a reference, it was found that in solution the distance between the catalytic trimers along the threefold axis is 0.34 nm larger and the trimers are rotated by 11° in opposite directions around the same axis; each of the three regulatory dimers is rotated by 9° around the corresponding twofold axis and displaced by 0.14 nm away from the molecular center along this axis. Proteins 27:110-117 © 1997 Wiley-Liss, Inc.
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  • 44
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    Electronic Resource
    Bactericidal antibody recognition of a PorA epitope of Neisseria meningitidis: Crystal structure of a Fab fragment in complex with a fluorescein-conjugated peptide (1997)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 29 (1997), S. 113-125 
    Details
    ISSN: 0887-3585
    Keywords: bactericidal antibody ; crystal structure ; Neisseria meningitidis ; peptide-fluorescein conjugate ; PorA outer membrane protein ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Class 1 outer membrane protein PorA of Neisseria meningitidis is a vaccine candidate against bacterial meningitis. Antibodies against PorA are able to induce complement-mediated bacterial killing and thereby play an important role in protection against meningococcal disease. Bactericidal antibodies are all directed against variable regions VR1 and VR2 of the PorA sequence, corresponding to loops 1 and 4 of a two-dimensional topology model of the porin with eight extracellular loops. We have determined the crystal structure to 2.6 Å resolution of the Fab fragment of bactericidal antibody MN12H2 against meningococcal PorA in complex with a linear fluorescein-conjugated peptide TKDTNNNL derived from the VR2 sequence of sero-subtype P1.7,16 (residues 180-187) from meningococcal strain H44/76. The peptide folds deeply into the binding cavity of the Fab molecule in a type I β-turn, with the minimal P1.16 epitope DTNNN virtually completely buried. The structure reveals H-bonds and van der Waals interactions with all minimal epitope residues and one essential salt bridge between Asp-182 of the peptide and His-31 of the MN12H2 light chain. The key components of the recognition of PorA epitope P1.16 by bactericidal antibody MN12H2 correspond well with available thermodynamic data from binding studies. Furthermore, they indicate the structural basis of an increased endemic incidence of infection by group B meningococci in England and Wales since 1981 associated with the occurrence of an Neisseria meningitidis escape mutant (strain MC58). The observed three-dimensional conformation of the peptide provides a rationale for the development of a synthetic peptide vaccine against meningococcal disease. Proteins 29:113-125, 1997. © 1997 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
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  • 45
    Electronic Resource
    Electronic Resource
    Computational, pulse-radiolytic, and structural investigations of lysine-136 and its role in the electrostatic triad of human C u,Z n superoxide dismutase (1997)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 29 (1997), S. 103-112 
    Details
    ISSN: 0887-3585
    Keywords: Brownian dynamics ; molecular recognition ; site-directed mutagenesis ; facilitated diffusion ; crystal structure ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Key charged residues in Cu,Zn superoxide dismutase (Cu,Zn SOD) promote electrostatic steering of the superoxide substrate to the active site Cu ion, resulting in dismutation of superoxide to oxygen and hydrogen peroxide. Lys-136, along with the adjacent residues Glu-132 and Glu-133, forms a proposed electrostatic triad contributing to substrate recognition. Human Cu,Zn SODs with single-site replacements of Lys-136 by Arg, Ala, Gln, or Glu or with a triple-site substitution (Glu-132 and Glu-133 to Gln and Lys-136 to Ala) were made to test hypotheses regarding contributions of these residues to Cu,Zn SOD activity. The structural effects of these mutations were modeled computationally and validated by the X-ray crystallographic structure determination of Cu,Zn SOD having the Lys-136-to-Glu replacement. Brownian dynamics simulations and multiple-site titration calculations predicted mutant reaction rates as well as ionic strength and pH effects measured by pulse-radiolytic experiments. Lys-136-to-Glu charge reversal decreased dismutation activity 50% from 2.2 × 109 to 1.2 × 109 M-1 s-1 due to repulsion of negatively charged superoxide, whereas charge-neutralizing substitutions (Lys-136 to Gln or Ala) had a less dramatic influence. In contrast, the triple-mutant Cu,Zn SOD (all three charges in the electrostatic triad neutralized) surprisingly doubled the reaction rate compared with wild-type enzyme but introduced phosphate inhibition. Computational and experimental reaction rates decreased with increasing ionic strength in all of the Lys-136 mutants, with charge reversal having a more pronounced effect than charge neutralization, implying that local electrostatic effects still govern the dismutation rates. Multiple-site titration analysis showed that deprotonation events throughout the enzyme are likely responsible for the gradual decrease in SOD activity above pH 9.5 and predicted a pKa value of 11.7 for Lys-136. Overall, Lys-136 and Glu-132 make comparable contributions to substrate recognition but are less critical to enzyme function than Arg-143, which is both mechanistically and electrostatically essential. Thus, the sequence-conserved residues of this electrostatic triad are evidently important solely for their electrostatic properties, which maintain the high catalytic rate and turnover of Cu,Zn SOD while simultaneously providing specificity by selecting against binding by other anions. Proteins 29:103-112, 1997. © 1997 Wiley-Liss, Inc.
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  • 46
    Electronic Resource
    Electronic Resource
    The crystal structure of 1,4-benzenedithiol by rietveld analysis and studies on the mechanism of solid-state addition polymerization of 1,4-benzenedithiol to 1,4-diethynylbenzene (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 1621-1625 
    Details
    ISSN: 0887-624X
    Keywords: 1,4-benzenedithiol ; 1,4-diethynylbenzene ; crystal structure ; solid-state polymerization ; layer structure ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The crystal structure of 1,4-benzenedithiol (BDT) was determined by the Rietveld method based on the calculation of the atomic coordinates of the BDT molecule using the Molecular Mechanics Program (MMP2). The refined crystal structure of BDT was monoclinic P21/c with dimensions, a = 7.795, b = 7.290, c = 5.955 Å, β = 92.16°, z = 2. The R factor of the refined structure was 0.038. Using above results, the mechanism of solid-state addition polymerization of BDT to 1,4-diethynylbenzene (DEB) was studied. Sublimed BDT piles up onto glass plate substrate and forms the layer structure along with the a axis. An inclination angle of the piled BDT column was 60° toward the substrate surface. DEB crystal structure was also monoclinic P21/c with a = 4.007, b = 6.018; c = 15.340 Å, β = 91.42°, z = 2. Sublimation of equimolar mixture of BDT and DEB gave a crystal having 1 : 1 composition, in which DEB column is situated between the columns of BDT. Relative arrangement of both monomers was suitable for the addition of —SH and —C=CH groups, since the distance between the two groups is 3.3 Å by CERIUS II calculation. Therefore, the addition polymerization of BDT to DEB easily proceeded by UV irradiation and the resulting polymer had a highly layer structure along with the a axis of BDT crystal. Tentatively estimated crystal structure of polymer obtained is monoclinic with a = 7.73, b = 7.30, c = 5.95 Å, β = 92.16°. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1621-1625, 1997
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    An ultrastructural study of oncocytoma and oncocytic carcinoma of the parotid gland (1997)
    Springer
    Medical molecular morphology 30 (1997), S. 31-36 
    Details
    ISSN: 1860-1499
    Keywords: Parotid gland ; Oncocytoma ; Oncocytic carcinoma ; Mitochondria ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract One case of oncocytoma and another of oncocytic carcinoma of the parotid gland are reported with ultrastructural studies. The incidence of oncocytoma varies from 0.1% to 1.4% of all parotid gland tumors, while oncocytic carcinoma is extremely rate. The oncocytoma was composed of polyhedral cells with fine eosinophilic granular cytoplasm and a rounded nucleus. The tumor cell clusters were surrounded by basement membrane. The tumor cells of the oncocytic carcinoma were also characterized by eosinophilic cytoplasm, but cellular atypia and mitotic figures were found. Electron microscopically, the cytoplasm of the oncocytoma was packed with abundant mitochondria. They were oval or elongated in shape with stacked cristae. Although the tumor cells of the oncocytic carcinoma also contained many mitochondria, their number was less than that of the benign case, and stacked cristae were very few. Basement membrane was not seen. The ultrastructural characteristics of oncocytoma and oncocytic carcinoma of the parotid gland are discussed with reference to previous reports.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01458349
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  • 48
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    Ultrastructural and biochemical studies of ischemic preconditioning using an adenosine receptor blocker and an ATP-sensitive K channel opener (1997)
    Springer
    Medical molecular morphology 30 (1997), S. 63-69 
    Details
    ISSN: 1860-1499
    Keywords: Preconditioning ; Ultrastructure ; Ischemia and reperfusion ; Adenosine receptor ; Nicorandil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effect of preconditioning (PC) on acute ischemic myocardial injury was investigated in an openchest dog model. Preconditioned dogs received four 5-min occlusions of the left anterior descending coronary artery (LAD), each separated by 10 min of reperfusion. Four groups were used to assess the effect: non-PC group (G-1), PC group (G-2), 8-phenyltheophylline-(adenosine receptor blocker) infused PC group (G-3), and nicorandil- (ATP-sensitive K-channel opener) infused PC group (G-4). The LAD was occluded for 60 min, followed by 60 min of reperfusion in all dogs. The rate of ultrastructural myocardial severe injury was 26% in G-1, 0% in G-2, 5% in G-3, and 0% in G-4. Biochemical analayses also indicated higher values of myocardial contractile function in G-2 and G-4 than G-1 and G-3. These data suggest that the adenosine receptor and K channel may play a key role in PC.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01545083
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  • 49
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    Ultrastructural localization of calcium in rat retina with oxalate pyroantimonate and energy-dispersive X-ray detector (1997)
    Springer
    Medical molecular morphology 30 (1997), S. 76-80 
    Details
    ISSN: 1860-1499
    Keywords: Ultrastructure ; Retina ; Rat ; Oxalate ; Potassium pyroantimonate ; X-ray analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Intracellular calcium plays an important role in the intracellular signal transduction as one of the second messengers. In this study, we examined the ultrastructural distribution of calcium in rat retina, using the oxalate pyroantimonate technique and X-ray microanalysis. Large amounts of precipitates were observed inside the disc of outer segments of photoreceptor cells (OS) and the synaptic vesicles of the inner (IPL) and outer plexiform layer (OPL). Precipitates also were observed in the ribosome-rich regions in the cytoplasm and the euchromatinic part in the cell nuclei of the ganglion, amacrine, and bipolar and horizontal cells. However, few precipitates were found in the inner segment of the photoreceptor cells and the retinal pigment epithelium (RPE). X-ray microanalysis with an energydispersive X-ray detector revealed that these precipitates had a peak of antimony and calcium. Therefore, it was suggested that these precipitates were Ca[Sb(OH)6]2, the reaction products of the oxalate-pyroantimonate technique. Our findings showed that calcium precipitates are abundant in retinal regions that are related to visual transmission.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01545085
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    Electronic Resource
    Electronic Resource
    Cardiomyopathy secondary to systemic triglyceride storage disease (1997)
    Springer
    Medical molecular morphology 30 (1997), S. 88-91 
    Details
    ISSN: 1860-1499
    Keywords: Systemic triglyceride storage disease ; Cardiomyopathy ; Endomyocardial biopsy ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Ultrastructural changes of a biopsied myocardium were observed by transmission electron microscopy in a patient with cardiomyopathy secondary to systemic triglyceride storage disease with Jordans' anomaly. There were many lipid droplets in the cardiocytes, and lipofuscin and mitochondria were increased. The volume fraction of myofibrils in the cardiocytes decreased because of an abundance of lipid droplets and mitochondriosis. Myocardial contractility may have been reduced by myofibrillar scarcity and low energy production resulting from an abnormality in the metabolism of fatty acids in the cardiocytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01545087
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    An ultrastructural study of the influence of radiation against cell line-derived human oral malignant melanoma (1997)
    Springer
    Medical molecular morphology 30 (1997), S. 81-87 
    Details
    ISSN: 1860-1499
    Keywords: Oral malignant melanoma ; Ultrastructure ; Radiosensitivity ; Nucleus ; Melanosome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The response to radiation of the SSM-1 cell line, derived from oral malignant melanoma, was investigated by survival curve and by light and electron microscopic abservation. Survival curve of the cells was investigated by the colony formation assay. X-irradiation with 2, 4, and 8 Gy was performed against the cell line. Morphological changes of the cells at 6, 24, 72, and 120h after irradiation were examined by both light and electron microscopy. The survival curve of the SSM-1 cells showed higher radiosensitivity than that of cutaneous melanoma cell lines. Giant cells and multinucleated cells were found only 120h after 8Gy irradiation. Ultrastructural observation revealed changes in nucleus and melanosomes; melanosomes increased in number at 120h after 8Gy irradiation. Further alterations after irradiation were noticed primarily in the nucleus. Radiosensitivity of the SSM-1 cell line derived from oral malignant melanoma was higher than that of cutaneous melanoma cell lines. The results of this study may support the concept that radiotherapy is effective for oral malignant melanoma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01545086
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    Electronic Resource
    Electronic Resource
    Muscle spindles in immobilized muscle: electron microscopic study of recovery (1997)
    Springer
    Medical molecular morphology 30 (1997), S. 102-109 
    Details
    ISSN: 1860-1499
    Keywords: Ultrastructure ; Rats ; Muscle spindles ; Immobilization ; Recovery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This study is concerned with the morphological recovery process of muscle spindles following a long period of immobilization. The right hindlimbs of rats were fixed with a plaster cast for 4 weeks. Thereafter, four groups of rats were examined by electron microscopy. One group served as the control after the cast was removed. The other three groups were examined after free walking for 4, 8, and 12 weeks, respectively. The muscle spindles (tibialis anterior muscle) of the individual animals were then ultrastructurally analyzed. The morphological alterations (of the outer capsule, intrafusal muscle fibers, and intrafusal nerve components) gradually recovered during free walking and regained almost all normal features in 12 weeks after returning to walking.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01545090
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  • 53
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    Effects of short-term treatment with ethanol on the ultrastructure of the adult golden hamster parathyroid gland (1997)
    Springer
    Medical molecular morphology 30 (1997), S. 148-153 
    Details
    ISSN: 1860-1499
    Keywords: Parathyroid gland ; Ultrastructure ; Golden hamster ; Ethanol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Several previous studies have indicated that ingestion of ethanol can induce hypocalcemia or osteoporosis. However, few data are available concerning the effects of ethanol on the parathyroid gland. To clarify the mechanism of ethanol-induced hypocalcemia, we studied the ultrastructure to the parathyroid gland in golden hamsters after shortterm treatment with ethanol. Ethanol was administered by gavage via an intragastric tube at 6g/kg of 50% ethanol in distilled water. The mean serum calcium concentration was significantly low at 3 and 5h after administration. The Golgi complexes of the parathyroid chief cells significantly decreased 1 and 3h after administration. The lipid droplets and the large vacuolar bodies significantly increased 5h after administration. These findings suggest that the cellular activity of the parathyroid gland is suppressed after shortterm treatment with ethanol.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01545316
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  • 54
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    Ultrastructural changes and localization of nitri oxide synthase in rat lung induced by endotoxin administration (1997)
    Springer
    Medical molecular morphology 30 (1997), S. 177-184 
    Details
    ISSN: 1860-1499
    Keywords: Nitric oxide synthase (NOS) ; Endotoxin ; Lung ; Ultrastructure ; In situ hybridization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To evaluate the relationship between pulmonary damage and the induction of nitric oxide synthase (NOS) in endotoxin shock, we injected 10mg/kg ofE. coli endotoxin intraperitoneally to Wistar male rats and observed the changes of the lung during the following 8h by electron microscopy, immunoelectron microscopy, and in situ hybridization. Morphological observation revealed infiltration of macrophages, aggregation of neutrophil in stasis in vascular lumens, and intraalveolar hemorrhage accompanied by epithelial damage. Endothelial constitutive NOS (ecNOS) was immunohistochemically localized in the endoplasmic reticulum of the endothelium of pulmonary arteries and in the cytoplasm of bronchial epithelial cells of control rats. After endotoxin administration, inducible NOS (iNOS) was detected in vascular endothelial cells, vascular smooth muscle cells, bronchial epithelial cells, bronchial smooth muscle cells, alveolar epithelial cells, and macrophages. Reverse transcription polymerase cham reaction (RTPCR) confirmed the expression of ecNOS mRNA and iNOS mRNA in the lung in endotoxin-treated rats and controls. In situ hybridization showed that ecNOS mRNA was expressed in vascular endothelial cells of pulmonary arteries in control rats. After endotoxin administration, iNOS mRNA was expressed in vascular endothelial cells. vascular smooth muscle cells, bronchial epithelial cells, alveolar epithelial cells, and macrophages that had infiltrated the alveolar and perivascular regions. After endotoxin administration, morphological changes and NO overproduction were observed, and it is concluded that NO may play an important role in maintaining the homeostasis of the bloodair barrier in pulmonary structures.
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    URL: http://dx.doi.org/10.1007/BF01545768
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    Squamous cell characteristics in small cell carcinoma of the uterine cervix: histological, immunohistochemical, and ultrastructural study in xenografted small cell carcinoma (1997)
    Springer
    Medical molecular morphology 30 (1997), S. 202-208 
    Details
    ISSN: 1860-1499
    Keywords: Uterine cervix ; Small cell carcinoma ; Xenograft ; Immunohistochemistry ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Small cell carcinoma of the uterine cervix is a rare type of gynecological tumor that frequently expresses neuroendocrine differentiation. Its histological origin is unclear. We examined the histopathological characteristics of small cell cervical carcinoma in a patient with elevated serum adrenocorticotropin hormone. We then studied the morphological alteration in xenotransplanted tumors (passages 1–9) using immunohistochemistry and electron microscopy. The primary cervical tumor was characterized by a sheetlike arrangement of uniform small cells with hyperchromatic nuclei and a high nucleocytoplasmic ratio. A ribbon-like or trabecular pattern was also observed in a small area of the tumor. Neuron-specific enolase, chromogranin A, and S-100 were positive for the tumor cells, but cytokeratin was negative. Dense-core granules were detected by electron microscopy. In the xenografted tumor, a serial change from squamous cells to round-to-oval cells was observed. Cytokeratin was immunohistochemically stained in the squamous tumor cells but not in the other tumor cells. In contrast, chromogranin A was stained in some of the round-to-oval cells. Basal lamina underlaid the squamous tumor cells, and desmosome-like junctions were apparent. The cytoplasm was filled with well-differentiated organelles including electron-dense tonofilaments. Elliptical tumor cells resembled the primary carcinoma ultrastructurally. These findings suggest that small cell cervical carcinoma with neuroendocrine properties shares the characteristics of squamous cell carcinoma.
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    URL: http://dx.doi.org/10.1007/BF01545771
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    Crystal Structures of 1,3-Calix[4]-bis-crown-6·3CH3CN and 1,3-Calix[4]-bis-(benzo-crown-6)·3 CH3CN (1997)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 27 (1997), S. 169-178 
    Details
    ISSN: 1573-1111
    Keywords: Bridged calix[4]arene ; ditopic receptor ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The crystal structures of a new solvate of the ditopic receptor 1,3-calix[4]-bis-crown-6, Bis-C6, and of 1,3-calix[4]-bis-(benzo-crown-6), Bis-benzoC6, are reported. Bis-C6.3 CH3CN (1) crystallizes in the monoclinic space group P21/n, a = 14.388(3), b = 26.947(8), c = 14.707(4) Å, β = 113.19(3)°, V = 5241(5) Å3, Z = 4. Refinement led to a final conventional R value of 0.092 for 2723 reflections. The structure of (1) differs from the previously reported structure of Bis-C6.4 CH3CN by the conformation of one crown either chain. Two acetonitrile molecules are in the close neighbourhood of the crown ether cavities. Bis-benzoC6.3 CH3CN (2) crystallizes in the monoclinic space group P21/c, a = 10.391(4), b = 17.264(11), c = 30.426(9) Å, β = 94.62(3)°, V = 5440(7) Å3, Z = 4. Refinement led to a final conventional R value of 0.106 for 2965 reflections. Two acetonitrile molecules are located near the crown ether cavities, as in (1). One of the crown ether conformations is the same as in the binuclear caesium complex of Bis-benzoC6, supporting the hypothesis of a preorganization of this ligand towards the complexation of this ion; the second crown ether chain is partially disordered.
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    URL: http://dx.doi.org/10.1023/A:1007990208036
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    X-Ray Structure and Proton NMR Study of a Hexacoordinated Lithium Complex (1997)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 28 (1997), S. 125-140 
    Details
    ISSN: 1573-1111
    Keywords: X-ray ; crystal structure ; Li-complex ; triamides ; 1H-NMR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The structure of the lithium complex with1,3,5-tris[oxymethylene(N,N-dicyclohexyl)carboxyamido]cyclohexanehas been determined by the X-ray method.The compound is triclinic, space group P¯1,a = 15.623(3), b = 19.279(4),c = 19.295(4)Å α = 102.32(3), β = 92.45(3),γ = 105.67(3)0, V = 5436(2)Å3, Z = 4. Itscomposition is represented by the formulaC48H82N3O6LiI 0.5H2O. The lithium cationis encapsulated in a polar pseudo-cavity of six oxygen atoms of the ligandmolecule and displays a distorted trigonal prism coordination. The conformationof the ligand in the solid state complex has been compared with the conformationof the complex in solution determined by 1H-NMR measurements. Supplementary data relevant to this publication have been deposited with the British Library, No. SUP 82224 (21 pages).
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    URL: http://dx.doi.org/10.1023/A:1007955923966
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  • 58
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    Inclusion Compounds of NaI with 13-Membered Azo- and Azoxycrown Ethers (1997)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 28 (1997), S. 17-32 
    Details
    ISSN: 1573-1111
    Keywords: Azocrown ether ; azoxycrown ether ; sodium complexes ; crystal structure ; X-ray analysis ; conformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Sodium iodide complexes of 13-membered azo-(I)and azoxycrown ethers (II) have been synthesized. Compound I[Na(L1 trans)2]⋅I⋅H2O is triclinic witha = 11.53(2), b = 15.74(2), c = 19.17(2) Å,α = 98.93(9), β = 105.51(9),γ = 89.20(9) deg.; Z = 4, space groupP1. Compound II [Na(L2)2]⋅I is orthorhombic witha = 12.451(2), b = 13.796(3), c = 18.667(4)Å; Z = 4, space group P212121. In bothcomplexes the cation is coordinated tochain oxygen atoms and to one nitrogen atom of the azoor azoxy unit. The ability of bothligands to form complexes in relation to thegeometry of the azo or azoxy subunit of themacrocycle is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007929726695
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  • 59
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    Polymorphism of Inclusion Complexes and Unsolvated Hosts. II. Structure of the β-Dimorph of the Host-Guest Complex of Dianilinegossypol with Ethylacetate (1997)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 27 (1997), S. 105-112 
    Details
    ISSN: 1573-1111
    Keywords: β-Dimorph ; crystal structure ; dianilinegossypol ethylacetate 1 : 1 clathrate ; packing motifs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Depending on crystallization conditions, dianilinegossypol and ethylacetate form low (ambient temperature, α-phase) and high temperature (t = 35°C, β-phase) clathrate modifications. The structure of the α-phase has been discussed earlier [1]. Crystals of the 1 : 1 β-phase complex, C42H40O6N2·C4O2H8, are monoclinic, space group P21/c, a = 11.362(6), b = 19.479(9), c = 19.085(9) Å, β = 103.21(4)°, V = 4112(3)Å3, Z = 4, R = 0.084 for 3210 observed reflections. In these complexes centrosymmetric dimers of dianilinegossypol molecules formed via O(5)—H···O(3) hydrogen bonds are associated into columns by a weak O(8)—H···O(7) H-bond. A difference in the structure of these two phases is in the packing mode of the columns. The angle formed by intersecting host columns is about 126° for the α-phase and 104° for the β-modification. Guest molecules are hydrogen bonded to the host molecules via an O(1)—H···O(10) bond and are accommodated in channels in α-phase complex and in cavities in β-phase complex.
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    URL: http://dx.doi.org/10.1023/A:1007908530132
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  • 60
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    Crystal Structure of a Uranyl/p-tert-Butylcalix[5]arene Complex (1997)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 27 (1997), S. 13-20 
    Details
    ISSN: 1573-1111
    Keywords: Uranyl complexes ; calixarenes ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The synthesis and crystal structure of the inclusion complex between uranyl and p-tert-butylcalix[5]arene are reported. [UO2 (p-tert-butylcalix[5]arene-4H]2- · $${\text{2HNE}}_{{\text{t}}_{\text{3}} }^{\text{ + }} $$ &·2MeOH(1) crystallizes in the monoclinic space group C2/c, a = 30.06(2), b = 18.20(3), c = 31.35(2) Å, β = 128.51(6)°, V = 13423(40) Å3, Z = 8. Refinement led to a final conventional R value of 0.043 for 4155 reflections. The uranyl ion is bonded, in its equatorial plane, to the five oxygen atoms of the calixarene, four of which are deprotonated. A protonated triethylamine molecule is located inside the calixarene cavity and hydrogen bonded to a uranyl oxygen atom, and another one outside and hydrogen bonded to a calixarene oxygen atom. The calixarene conformation is the usual cone one.
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    URL: http://dx.doi.org/10.1023/A:1007938218723
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    Synthesis, Structure and Alkali Metal Ion Binding Properties of a Podand Polyether Derived from Calix[4]arene, 5,11,17,23-tetra-tert-butyl-25,27-di(phenylmethoxy)-26,28-di(2‘-methoxyethoxy)-calix[4]arene (1997)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 27 (1997), S. 291-302 
    Details
    ISSN: 1573-1111
    Keywords: Calix[4]arene ; polyether ; crystal structure ; alkali metal ion binding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The ligand 5,11,17,23-tetra-t-butyl-25,27-di(phenylmethoxy)-26,28-di(2-methoxy-ethoxy)calix[4]arene,designed as an analogue of some calixcrown speciesin order to evaluate possible origins of their selectivity in alkali metal ion binding, has been synthesised and structurally characterised by X-ray crystallography. The crystals are monoclinic, P21/n, a = 15.940(6), b = 19.388(5), c = 20.020(5) Å,β = 109.10(2) deg., Z = 4, conventional R on |F| being 0.073 for 3454 independent, ’observed‘ (I 〉 3σ(I)) reflections. 1H-NMR studies in 1:1 CD3CN/CDCl3solvent have shown that the ligand exerts a strong preference for the lighteralkali metal ions (Li+ and Na+) contrary to the binding behaviour of knowncalixcrowns. This may reflect interactions restricted to the lower rim donor atoms without concomitant interaction with the calixarene π-electrons, perhaps because the latter interactions are substituted by those with the benzyl group π-electrons.
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    URL: http://dx.doi.org/10.1023/A:1007981710765
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    Polymorphism of Inclusion Complexes and Unsolvated Hosts. V. Crystal Structure of the α-Dimorph of the 1 : 2 Dianilinegossypol–DMSO Complex and a 1 : 1 : 1 Inclusion Complex Based on a Mixed Dianilinegossypol/1,4-Dioxane Host Matrix and 1,2-Dichloroethane Guest (1997)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 29 (1997), S. 23-32 
    Details
    ISSN: 1573-1111
    Keywords: Dianilinegossypol ; crystal structure ; host–guest complexes ; H-bond ; α- and β-dimorphs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Dianilinegossypol forms a 1 : 2 host-guest complex with DMSO:monoclinic, space group P21/n, a = 8.522(3), b = 18.034(4), c= 28.462(6) Å, β = 94.14(2)°, V = 4362Å3, Z = 4, D x = 1.26 g cm-3, T = 295 K.Final R value is 0.102 for 1793 observed reflections. A 1 : 1 : 1 adduct ofdianilinegossypol with 1,4-dioxane and 1,2-dichloroethane is found to beisostructural with the dianilinegossypol complex with DMSO: monoclinic,space group P21/n, a = 8.281(2), b = 19.245(3), c = 27.970(7)Å, β = 95.18°, V = 4439 Å3, Z = 4, D x =1.28 g cm-3, T = 295 K. Final R value is 0.114 for 2458observed reflections.The host molecules are associated by O(4)—H ...O(3) H-bonds toinfinite chains running in the direction of the c-axis The chains areincorporated into layers through 1,4-dioxane or DMSO molecules havingH-bonds with dianilinegossypol molecules. Another DMSO or 1,2-dichloroethanemolecule is included as a guest in the channels formed between the layers.At 60 °C a cryptate-type inclusion complex of dianilinegossypol isformed with DMSO or 1,4-dioxane. It is isostructural with the acetonecomplex reported in Part IV of the present series.
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    URL: http://dx.doi.org/10.1023/A:1007992116261
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    p-tert-Butylcalix[5]arene: a New Synthetic Pathway and Crystal Structure of the N,N-Dimethylformamide Complex (1997)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 29 (1997), S. 175-185 
    Details
    ISSN: 1573-1111
    Keywords: p-tert-Butylcalix[5]arene ; synthesis ; complexation ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The formation of p-tert-butylcalix[5]arene by the opening ofp-tert-butyldihomooxacalix [4]arene and the addition of a monomer has beenstudied. Various facets, including the effects of bases and the nature ofthe monomer added to the p-tert-butyldihomooxacalix[4]arene, have beeninvestigated. p-tert-Butylcalix[5]arene can be prepared in yields up to30%. The structure of its 1 : 2 complex with DMF has been determinedby X-ray crystallography. Crystals are triclinic, space group P¯1, a =1428.2(3) pm, b = 1837.3(3) pm, c = 1276.1(2) pm, α = 108.98(1)°,β = 105.02(2)°, γ = 95.21(1)°, Z = 2, D c = 1.059 kg m-3,final R value = 0.087. The macrocycle adopts a cone conformation, one guestenclosed inside the cavity, the other one outside.
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    URL: http://dx.doi.org/10.1023/A:1007907525620
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    Synthesis of Two New Glycophanes Comprised of Thioglucose Molecules Linked by Hydrocarbons (1997)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 29 (1997), S. 335-346 
    Details
    ISSN: 1573-1111
    Keywords: Glycophane ; macrocycle ; carbohydrate ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Preparation of two new glycophanes is reported. These compounds arecomprised of two glucose molecules linked by hydrocarbon units at the 1,1′ and 3, 3′ or 3, 3′ and 6, 6′ positions. Thecrystal structure of one of the glycophanes is also described.
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    URL: http://dx.doi.org/10.1023/A:1007952822709
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    Neuronal differentiation of human neuroblastoma SH-SY5Y cells by gangliosides (1997)
    Springer
    Brain tumor pathology 14 (1997), S. 5-11 
    Details
    ISSN: 1861-387X
    Keywords: Gangliosides ; Neuronal differentiation ; Neuroblastoma ; Ganglioneuroblastoma ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Exogenous administration of gangliosides induced neuronal differentiation with prominent neuritogenesis in human neuroblastoma SH-SY5Y cells in vitro. Neuritogenesis was characterized by ruffling of the cell membrane, the development of lamellipodia and filopodia, and the subsequent elongation and branching of the neurites ultrastructurally. Both axons and neurites were identified. Increased numbers of cell organelles in the neurites and cell bodies were noted. Nonsynaptic contacts and gap junctions formed between neurites or between each neurite and cell body. These findings could be implicated in histopathologic changes from neuroblastoma to ganglioneuroblastoma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02478862
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    Primary leptomeningeal meningiomatosis with widespread whorl formation (1997)
    Springer
    Brain tumor pathology 14 (1997), S. 139-143 
    Details
    ISSN: 1861-387X
    Keywords: Primary leptomeningeal meningiomatosis ; Meningioma ; Whorl formation ; Immunohistochemistry ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report a 10-year-old girl with a primary leptomeningeal tumor. She presented with a 5-week history of increased intracranial pressure, progressive cranial nerve deficits, and spinal compression signs. She had previously had a granulosa cell tumor, a benign estrogen-producing ovarian tumor, which was resected 6 months before the initial neurological symptoms developed. At autopsy, the brain and spinal cord showed diffuse neoplastic involvement of the leptomeninges. The tumor was composed of small cells with a high nucleus/cytoplasm ratio, which were immunoreactive for vimentin but not for epithelial membrane antigen or cytokeratin. In addition, the tumor contained many small cellular whorls with desmosome-like junctional complexes between the cells, suggesting that the tumor was a meningioma, basically of the meningothelial type. The term ‘meningeal meningiomatosis’ has been used synonymously with “primary meningeal sarcomatosis”. The present tumor was considered to be a rare example of “meningeal meningiomatosis” of true meningothelial cell origin.
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    URL: http://dx.doi.org/10.1007/BF02478883
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    Synthesis, conformation, and biological activity of two fMLP-OMe analogues containing the new 2-[2′-(methylthio) ethyl] methionine residue (1997)
    New York : Wiley-Blackwell
    Biopolymers 42 (1997), S. 415-426 
    Details
    ISSN: 0006-3525
    Keywords: chemotaxis ; conformation ; crystal structure ; Cα-tetrasubstituted amino acids ; formylpeptides ; 2-[2′-(methylthio)ethyl]methionine ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The new Cα-tetrasubstituted α-amino acid residue 2-[2′-(methylthio) ethyl]methionine (Dmt) has been introduced into the reference chemotactic tripeptide HCO-Met-Leu-Phe-OMe (fMLP-OMe) in place of the leucine or methionine, respectively. The biological activity of the new analogues [Dmt2] fMLP-OMe (2) and [Dmt1] fMLP-OMe (3) has been determined; whereas 2 is active toward human neutrophils, stimulating directed migration, superoxide anion generation, and lysozyme release, 3 results practically inactive in all tested assays. A conformational analysis on 2 and 3 has been performed in solution by using ir absorption and 1H-nmr. The conformation of 2 was also examined in the crystal by x-ray diffraction methods. Both 2 and 3 adopt fully extended conformation in correspondence with the Dmt residue. Biological and conformational results are discussed and compared with related previously studied models. © 1997 John Wiley & Sons, Inc. Biopoly 42: 415-426, 1997
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    Role of two consecutive α,β-dehydrophenylalanines in peptide structure: Crystal and molecular structure of Boc-Leu-ΔPhe-ΔPhe-Ala-Phe-NHMe (1997)
    New York : Wiley-Blackwell
    Biopolymers 42 (1997), S. 373-382 
    Details
    ISSN: 0006-3525
    Keywords: x-ray diffraction ; crystal structure ; dehydrophenylalanine ; constrained peptides ; 310-helix ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An Nα-protected model pentapeptide containing two consecutive ΔPhe residues, Boc-Leu-ΔPhe-ΔPhe-Ala-Phe-NHMe, has been synthesized by solution methods and fully characterized. 1H-nmr studies provided evidence for the occurrence of a significant population of a conformer having three consecutive, intramolecularly H-bonded β-bends in solution. The solid state structure has been determined by x-ray diffraction methods. The crystals grown from aqueous methanol are orthorhombic, space group P212121, a = 11.503(2), b = 16.554(2), c = 22.107(3) Å, V = 4209(1) Å,3 and Z = 4. The x-ray data were collected on a CAD4 diffractometer using CuKa radiation (λ = 1.5418 Å). The structure was determined using direct methods and refined by full-matrix least-squares procedure. The R factor is 5.3%. The molecule is characterized by a right handed 310-helical conformation (〈φ〉 = -68.2°, 〈ψ〉 = -26.3°), which is made up of two consecutive type III β-bends and one type I β-bend. In the solid state the helical molecules are aligned head-to-tail, thus forming long rod like structures. A comparison with other peptide structures containing consecutive ΔPhe residues is also provided. The present study confirms that the -ΔPhe-ΔPhe-sequence can be accommodated in helical structures. © 1997 John Wiley & Sons, Inc. Biopoly 42: 373-382, 1997
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    RNA crystallography (1997)
    New York : Wiley-Blackwell
    Biopolymers 44 (1997), S. 3-21 
    Details
    ISSN: 0006-3525
    Keywords: RNA ; x-ray crystallography ; crystal structure ; transfer RNA ; ribozyme ; catalytic RNA ; internal loop ; review ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The current state of three-dimensional structure analysis of RNA by x-ray crystallograpy is summarized. The methods of sample preparation, crystallization, data collection, and structure solution are discussed, followed by a review of the RNA structures that have been determined and of common structural features, and finally, an appraisal of future prospects for x-ray crystal structure analysis of RNA. © 1997 John Wiley & Sons, Inc. Biopoly 44: 3-21, 1997
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    Crystalline structure of poly(methyl-n-propylsilane) (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 35 (1997), S. 1533-1543 
    Details
    ISSN: 0887-6266
    Keywords: polysilane ; lamellar microstructure ; crystal structure ; crystallization kinetics ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The thermal behavior and physical structure of atactic poly(methyl-n-propylsilane) (PMPrS) have been investigated by complementary techniques. Temperature-dependent wide-angle X-ray scattering as well as thermal analysis clearly indicate that atactic PMPrS crystallizes below 40°C in a monoclinic lattice with PMPrS adopting an all-trans planar zigzag conformation. Above 40°C, the polymer is in the isotropic amorphous state. A restricted analysis of the structure factors of PMPrS has been performed, indicating that the zigzag planes most probably lie in (110) planes. The chains pack with little interpenetration, and the crystals may be considered as bundles of long, closely packed prisms. The restricted interlocking of neighboring chains results, in turn, in a poor register of the chains along the c-axis. Moreover, transmission electron microscopy reveals that the crystallized polymer adopts a lamellar microstructure, with parallel lamellae tending to form tight bundles. Both electron microscopy and small-angle X-ray scattering indicate crystal thicknesses of about 60 Å. Finally, PMPrS was found to crystallize with a nucleation-controlled type of kinetics. Avrami exponents were calculated as n ≈ 1, suggesting a fibrillar growth geometry compatible with the absence of spherulitic superstructure. A double-melting behavior is also observed for PMPrS. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 1533-1543, 1997
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    Electron diffraction and computer modeling of poly(naphthalic anhydride) crystal structure (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 35 (1997), S. 1575-1588 
    Details
    ISSN: 0887-6266
    Keywords: poly(naphthalic anhydride) ; crystal structure ; electron diffraction ; confined thin film melt polymerization ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Single crystals of poly(naphthalic anhydride) (PNA) have been grown using our confined thin film melt polymerization technique. Lamellae, 70-100 Å thick, are found for the crystals polymerized at 180°C with thinner lamellae for a 200°C polymerization temperature. In addition, irregular lath-shaped crystals are found for both polymerization temperatures, apparently formed by a solid-state polymerization process within the original needle-like monomer crystals. The crystal structure of PNA has been studied by electron diffraction (ED) and computer modeling based on seven different zonal ED patterns. It is found that, in most cases, two or three different zonal patterns are superimposed with a common plane, suggesting variable chain tilting even in individual lamellae. Shearing of the material shortly after the initiation of polymerization, permitted obtaining an additional [010] zone ED pattern. A monoclinic unit cell with one chain, two repeat units is proposed based on measurements of 21 independent reflections; the space group is Pc11; a = 6.26 Å, b = 4.33 Å, c = 18.60 Å, and α = 122.5°. The computer-simulated (Cerius2) molecular conformation and chain packing are described with the corresponding simulated electron diffraction patterns being in good agreement with the observed ones. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 1575-1588, 1997
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    Hexabromotricyclobutabenzene and Hexabromohexaradialene: Their Nickel-Mediated One-Pot Syntheses and Crystal Structure (1997)
    Weinheim : Wiley-Blackwell
    Chemistry - A European Journal 3 (1997), S. 208-210 
    Details
    ISSN: 0947-6539
    Keywords: crystal structure ; cyclobutenes ; nickel ; radialenes ; radical reactions ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of hexakis(dibromomethyl)benzene with [(Bu3P)2-Ni(COD)] (COD = 1,5-cyclooctadiene) in DMF at 65-70°C yielded a mixture of the title compounds. The mixture was separated by column chromatography to yield hexabromotricyclobutabenzene (3 a) and hexabromohexaradialene (4) in 24 and 16% yields, respectively. 1H and 13C NMR spectroscopy suggest that 3 is obtained as the syn-all-trans isomer 3 a, and the symmetric anti-all-trans isomer 3 b is not obtained at all. The X-ray structures of 3 a and 4 are reported. The hexaradialene 4 has a chair conformation, and deviates from planarity by 43.6°. Heat or radical impurities cause the clean transformation of 3 a to 4.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/chem.19970030207
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    Two New Closely Related MoV Hydroxymonophosphates Built Up of Cd[Mo6P4O25(OH)6]2 And Cd[Mo6P4O26(OH)5]2 ClustersDedicated to Professor H. G. von Schnering on the occasion of his retirement (1997)
    Weinheim : Wiley-Blackwell
    Chemistry - A European Journal 3 (1997), S. 1797-1800 
    Details
    ISSN: 0947-6539
    Keywords: cadmium ; crystal structure ; hydrothermal synthesis ; hydroxyphosphate ; molybdenum ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two new molybdenum(v) hydroxyphosphates have been synthesized hydrothermally, Na2Cd3(Mo2O4OH)6-(PO4)2(PO3OH)6[N(CH3)4]4·10H20 (1) and Cd9(Mo2O4OH)12(PO4)6(PO3OH)10-[N(CH3)4]8·15H2O (2). Their structures have been determined from single-crystal X-ray diffraction. The water molecules and hydroxyl groups have been deduced from valence calculations. Both compounds crystallize in the triclinic space group P1, with the cell parameters for 1 a = 12.340(2), b = 12.596(1), c = 14.717(2) Å, α = 107.24(1)°, β = 89.83(1)°, γ = 114.31(1)°, V = 1972.3(4) Å3, and for 2 a = 11.942(1), b = 13.339(2), c = 26.765(3) Å, α = 85.33(1)°, β = 86.87(1)°, γ = 64.08(1)°, V = 3821.3(9) Å3. The two frameworks can be described on the basis of similar [Mo6P4X31]n- (X = O, OH) anionic clusters, but 1 is a tridimensional structure, whereas 2 exhibits a monodimensional structure.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/chem.19970031111
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    Morphology, crystal structure, and orientation of poly-p-oxybenzoate on mica (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 35 (1997), S. 1807-1820 
    Details
    ISSN: 0887-6266
    Keywords: poly(p-oxybenzoate) ; confined thin film melt polymerization ; epitaxy ; mica substrate ; morphology ; crystal structure ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polymerization of p-acetoxybenzoic acid between mica sheets, from both the melt and dilute solution, in a wide range of polymerization temperatures (180-400°C) yields an epitaxial-like overgrowth of PpOBA on the mica cleavage surface. The PpOBA overgrowth forms long rows by lateral aggregation of ribbon crystals situated in three substrate directions rotated by 60°. The c-axes of the PpOBA phase I and II lattices are parallel to the 001 plane of the mica, coinciding with the a-axes of the mica hexagonal structure. The aI- and bII-axes lie predominantly on the mica surface. The surface-orienting effect is tentatively attributed to surface steps and or/polar effects; lattice matching does not occur. The recrystallization of bulk polymer samples previously prepared also leads to ordering between mica like that in melt or solution polymerization. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 1807-1820, 1997
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    Structural transformation of ultra-high modulus and molecular weight polyethylene fibers by high-temperature wide-angle X-ray diffraction (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 35 (1997), S. 623-630 
    Details
    ISSN: 0887-6266
    Keywords: ultra-high modulus and molecular weight polyethylene fibers (UHM-WPE) ; high-temperature wide-angle x-ray diffraction (HTWAXD) ; crystal structure ; orthorhombic/monoclinic/pseudohexagonal transformation ; annealing and thermal behavior ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Wide-angle x-ray diffraction (WAXD) of the ultra-high modulus and molecular weight polyethylene (UHMWPE) fibers at room temperature shows a predominantly orthorhombic structure with trace amount of nonorthorhombic crystals and very low amorphous contents. The calculated unit cell dimensions a and b of the orthorhombic crystals are 7.36 (±0.04) Å, and 4.89 (±0.04) Å, respectively. The apparent crystallite sizes perpendicular to the orthorhombic 110 and 200 reflection planes are 169.8 and 143.4 Å, respectively. The crystallite size perpendicular to the nonorthorhombic 010 reflection is 149.4 Å. The crystal density is calculated to be 1.02 g/cc. With increasing temperature, the thermal expansion coefficient in the a direction is much higher than that in the b direction which explains the structural transformation from the orthorhombic crystals to a pseudohexagonal form. Tension along the fiber axis while being heated during the high-temperature x-ray diffraction (HTWAXD) scanning has shown enhanced structural transformation from the orthorhombic form to the monoclinic form. Structural transformation from the orthorhombic form to the pseudohexagonal phase is not observed on the UHMWPE fibers under axial tension or annealing conditions in HTWAXD. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys, 35: 623-630, 1997
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    A study of the dilation of the unit cell of metallocene isotactic poly(propylenes): The monoclinic form (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 35 (1997), S. 2511-2521 
    Details
    ISSN: 0887-6266
    Keywords: isotactic poly(propylenes) ; unit-cell density ; crystal structure ; unit-cell parameters ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The lattice parameters of a series of monoclinic metallocene poly(propylenes) of constant molecular weight are measured as a function of defect content, that vary between 0.3 and 2.35 total defects per 100 monomeric units. The parameters are also measured as a function of molecular weight for a fixed defect content and as a function of the crystallization temperature. The b axis is found to increase with decreasing isothermal crystallization temperature whereas only small changes are found for samples rapidly crystallized. The a and c axis showed basically no variation with crystallization temperature. The parameters of the unit cell were essentially constant with varying defect content in the poly(propylene) chain. Lack of observed effect on the dilation of the unit cell by increasing defects is a consequence of the rapid crystallization required to ensure formation of monoclinic crystals. The unit cell parameters increased as a mild function of the molecular weight. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 2511-2521, 1997
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    Crystal structure of the bovine α-chymotrypsin:kunitz inhibitor complex. An example of multiple protein:protein recognition sitesThis paper is dedicated to Professor A. Ballio on the occasion of his 75th birthday. (1997)
    Chicester [u.a.] : Wiley-Blackwell
    Journal of Molecular Recognition 10 (1997), S. 26-35 
    Details
    ISSN: 0952-3499
    Keywords: bovine α-chymotrypsin ; bovine basic pancreatic trypsin inhibitor (Kunitz-type inhibitor) ; serine proteinase:Kunitz inhibitor complex ; crystal structure ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The crystal structure of bovine α-chymotrypsin (α-CHT) in complex with the bovine basic pancreatic trypsin inhibitor (BPTI) has been solved and refined at 2.8 Å resolution (R-factor=0.18). The proteinase:inhibitor complex forms a compact dimer (two α-CHT and two BPTI molecules), which may be stabilized by surface-bound sulphate ions, in the crystalline state. Each BPTI molecule, at opposite ends, is contacting both proteinase molecules in the dimer, through the reactive site loop and through residues next to the inhibitor's C-terminal region. Specific recognition between α-CHT and BPTI occurs at the (re)active site interface according to structural rules inferred from the analysis of homologous serine proteinase:inhibitor complexes. Lys15, the P1 residue of BPTI, however, does not occupy the α-CHT S1 specificity pocket, being hydrogen bonded to backbone atoms of the enzyme surface residues Gly216 and Ser217. © 1997 John Wiley & Sons, Ltd.
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    Metal-Template Electrophilic Substitution on Phenols: Synthesis and Crystal Structure of Bromomagnesium Phenolate and Its Reactive Complex with para-IsopropylbenzaldehydeDedicated to the memory of Professor Giuseppe Casnati on the 4th anniversary of his death (1997)
    Weinheim : Wiley-Blackwell
    Chemistry - A European Journal 3 (1997), S. 1269-1272 
    Details
    ISSN: 0947-6539
    Keywords: crystal structure ; electrophilic aromatic substitutions ; magnesium ; regioselectivity ; template synthesis ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The crystal structures of the bromomagnesium phenolate 5 and its complex 7 with para-isopropylbenzaldehyde are reported; for the first time it has been possible to demonstrate that the reactive complex 7, responsible for the complete ortho-regioselective control in the alkylation of phenoxymagnesium bromides with aldehydes, is not obtained by simple replacement of the ethereal ligand but by expansion of the metal coordination sphere from 4 (usual tetrahedral configuration) to 5. We infer from 1H NMR studies that the magnesium coordination of complex 7 in solution is analogous to that shown in the solid state, with a complexed ethereal molecule.
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    URL: http://dx.doi.org/10.1002/chem.19970030814
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    Synthesis of Pyrazinoporphyrazine Derivatives Functionalised with Tetrathiafulvalene (TTF) Units: X-Ray Crystal Structures of Two Related ttf Cyclophanes and Two Bis(1,3-Dithiole-2-Thione) IntermediatesDedicated to Professor Fabian Gerson on the occasion of his retirement (1997)
    Weinheim : Wiley-Blackwell
    Chemistry - A European Journal 3 (1997), S. 1679-1690 
    Details
    ISSN: 0947-6539
    Keywords: crystal structure ; cyclophanes ; electrochemistry ; porphyrazines ; tetrathiafulvalenes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The pyrazinoporphyrazine system 13 (metal-free, zinc and copper derivatives) has been synthesised by tetramerisation of 2,3-dicyanopyrazine monomer unit 10. The structure of 13a-c has been established by 1H NMR spectroscopy, UV/Vis spectrophotometry, MALDI-TOF mass spectrometry, cyclic voltammetry and differential pulse voltammetry. The electrochemical redox behaviour of 13a-c is strongly solvent dependent. The expected two-stage oxidation of the tetrathiafulvalene (TTF) units of 13a-c was observed in a range of solvents; in addition, oxidation and reduction of the pyrazinoporphyrazine core of the metal-free derivative 13a was detected in benzonitrile. On excitation of 13 in the Q-band region no fluorescence was observed, which is presumably the consequence of intramolecular charge transfer between the TTF moieties and the excited state of the central porphyrazine. Molecular modelling studies on 13a and 13c are reported. During the course of this work, the novel TTF macrocycles 11 and 20 were synthesised; their X-ray crystal structures reveal severely bent TTF units, the conformations of which are discussed in detail. The X-ray crystal structures of the bis(1,3-dithiole) systems 15 and 18 have also been determined.
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    URL: http://dx.doi.org/10.1002/chem.19970031018
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    The Unusual Properties of 5-Methyl-4,5,6,7-Tetrahydro-1H-Indazole in the Solid State (1997)
    Weinheim : Wiley-Blackwell
    Chemistry - A European Journal 3 (1997), S. 121-126 
    Details
    ISSN: 0947-6539
    Keywords: crystal structure ; NMR spectroscopy ; proton transfer ; pyrazoles ; tautomerism ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The crystal structure of the title compound was determined by X-ray analysis at 200 K. Three independent molecules form a trimer joined by strong and linear N-H … N hydrogen bonds. There is another centrosymmetrically related trimer in the unit cell. Both tautomers (1H and 2H) are present in each trimer. Disorder of the NH protons involved in the N-H … N hydrogen bonds has been observed. Solid-state 13C CPMAS NMR was used to establish the dynamic nature of the NH-proton disorder, the title compound being the first example of proton transfer in a tautomeric mixture of pyrazoles with an equilibrium constant other than 1.
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    URL: http://dx.doi.org/10.1002/chem.19970030119
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    Synthese und Kristallstruktur von Bis(1,2-dimethyl-5-nitro-imidazol)dichlorocobalt(II) (1997)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1201-1202 
    Details
    ISSN: 0044-2313
    Keywords: Cobalt(II) complex ; 1,2-dimethyl-5-nitro-imidazole ligand ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Crystal Structure of Bis(1,2-dimetyl-5-nitro-imidazole)dichlorocobalt(II)Bis(1,2-dimethyl-5-nitro-imidazol)dichlorocobalt(II) was obtained by reaction of CoCl2 · 6 H2O with 1,2-dimethyl-5-nitro-imidazole in methanol. The compound forms blue crystals which were characterized by IR and UV-vis spectroscopy and by an X-ray crystal structure determination. Co(C5H7N3O2)2Cl2: tetragonal, space group I42d, Z = 8, a = 1142.1(1) pm, c = 2577.3(2) pm. R = 0.036 for 670 independent reflexions. The Co atom is tetrahedrally surrounded by two chlorine and two N atoms at distances of 222.8(2) and 203.5(4) pm.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19976230802
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    Tetraammin-Lithium-Kationen zur Stabilisierung phenylsubstituierter Zintl-Anionen: Die Verbindung [Li(NH3)4]2[Sn2Ph4] (1997)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1503-1505 
    Details
    ISSN: 0044-2313
    Keywords: Ditetraammine lithium tetraphenyldistannide ; synthesis ; single-crystals ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tetraammine Lithium Cations Stabilizing Phenylsubstituted Zintl-Anions: The Compound [Li(NH3)4]2[Sn2Ph4]Ruby-red, brittle single crystals of [Li(NH3)4]2[Sn2Ph4] were synthesized by the reaction of diphenyltin dichloride and metallic lithium in liquid ammonia at -35°C. The structure was determined from X-ray singlecrystal diffractometer data: Space group, P1, Z = 1, a = 9.462(2) Å, b = 9.727(2) Å, c = 11.232(2) Å, α = 66.22(3)°, β = 85.78(3)°, γ = 61.83(3)°, R1 (F02 ≥ 4σF02) = 5.13%, wR2 (F02 ≥ 4σF02) = 10.5%, N(F02 ≥ 4σF02) = 779, N(Var.) = 163.The compound contains to Sb2Ph4 isosteric centres [Sn2Ph4]2- as anions which are connected to rods by lithium cations in distorted tetrahedral coordination by ammonia. These rods are arranged parallel to one another in the b,c-plane, but stacked along [100].
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    URL: http://dx.doi.org/10.1002/zaac.19976231006
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    Bi13Pt3I7: Ein Subiodid mit einer pseudosymmetrischen Schichtstruktur (1997)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1535-1541 
    Details
    ISSN: 0044-2313
    Keywords: Bismuth platinum iodide ; subhalide ; crystal structure ; pseudo-symmetry ; stacking faults ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Bi13Pt3I7: A Subiodide with a Pseudo-Symmetric Layer StructureThe reaction of PtI2 with Bi and BiI at 630 K yields black, lustrous, air insensitive crystals of the subiodide Bi13Pt3I7. The layered crystal structure (triclinic, C1, a = 1581.0(2) pm, b = 912.6(1) pm, c = 2149.6(6) pm, α = 90.03(2)°, β = 96.96(2)°, γ = 90.11(1)°, V = 3078.6 · 106 pm3) contains edge-sharing [PtBi8/2] cubes, which form nets of Kagomé type. Iodine atoms fill the hexagonal-prismatic voids therein. These ∞2[(PtBi8/2)3I] layers are alternately separated by layers of iodine atoms or ∞1[BiI4-] zigzag-chains. The marked pseudo-symmetry of the structure favours stacking faults, which cause streaks of diffuse scattering in the diffraction pattern.
    Notes: Aus der Reaktion von PtI2 mit Bi und BiI bei 630 K erhält man schwarze, metallisch glänzende und luftbeständige Kristalle des Subiodids Bi13Pt3I7. In der schichtartig aufgebauten Kristallstruktur (triklin, C1, a = 1581,0(2) pm, b = 912,6(1) pm, c = 2149,6(6) pm, α = 90,03(2)°, β = 96,96(2)°, γ = 90,11(1)°, V = 3078,6 · 106 pm3) liegen Kagomé-Netze aus kantenverknüpften [PtBi8/2]-Würfeln vor, deren hexagonal-prismatische Lücken mit Iodatomen gefüllt sind. Diese ∞2[(PtBi8/2)3I]-Schichten sind abwechselnd durch eine Lage von Iodatomen oder eine Schicht aus parallel angeordneten ∞1[BiI4-]-Zickzackketten getrennt. Die in der Struktur stark ausgeprägte Pseudosymmetrie begünstigt Stapelfehler, welche sich auch in diffusen Streifen im Beugungsbild äußern.
    Additional Material: 6 Ill.
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    Zur Kristallstruktur von CaZn2(OH)6 · 2 H2O (1997)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1287-1289 
    Details
    ISSN: 0044-2313
    Keywords: Calcium hexahydroxodizincate dihydrate ; synthesis ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Crystal Structure of CaZn2(OH)6 · 2 H2OThe electrochemical oxidation of zinc in a zinc/iron-pair leads in an aqueous NH3 solution of calciumhydroxide at room temperature to colourless crystals of CaZn2(OH)6 · 2 H2O. The X-ray structure determination was now successful including all hydrogen positions.P21/c, Z = 2, a = 6.372(1) Å, b = 10.940(2) Å, c = 5.749(2) Å, β = 101.94(2)° N(F2o ≥ 3σF2o) = 809, N(Var.) = 69, R/RW = 0.011/0.012The compound CaZn2(OH)6 · 2H2O contains Zn2+ in tetrahedral coordination by OH- and Ca2+ in octahedral coordination by four OH- and two H2O. The tetrahedra around Zn2+ form corner sharing chains, three-dimensionally linked by isolated polyhedra around Ca2+. Weak hydrogen bridge bonds result between H2O as donor and OH-.
    Notes: Die elektrochemische Oxidation von Zink in einem Zink/Eisen-Paar führt in einer wäßrigen NH3-Lösung von Calciumhydroxid bei Raumtemperatur zu farblosen Kristallen von CaZn2(OH)6 · 2 H2O. An ihnen wurde röntgenographisch die Struktur jetzt einschließlich aller H-Lagen bestimmt.P21/c, Z = 2, a = 6,372(1) Å, b = 10,940(2) Å, c = 5,749(2) Å, β = 101,94(2)° Z(F2o ≥ 3σF2o) = 809, Z(Var.) = 69, R/RW = 0,011/0,012In CaZn2(OH)6 · 2 H2O ist Zn2+ tetraedrisch von OH- und Ca2+ oktaedrisch von vier OH- und zwei H2O umgeben. Die Tetraeder um Zn2+ bilden Ketten über gemeinsame Ecken, die durch voneinander isolierten Oktaedern um Ca2+ dreidimensional verknüpft werden. Es liegen schwache H-Brückenbindungen von H2O als Donator zu OH- vor.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19976230819
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    Pseudoelementverbindungen. XI. [1] Untersuchungen zum Komplexbildungsverhalten von Cyanamidonitrat [NO2NCN]-Professor Wolfgang Beck zum 65. Geburtstag gewidmet (1997)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1299-1305 
    Details
    ISSN: 0044-2313
    Keywords: Pseudoelement compounds ; cyanamidonitrate ; copper(I) ; silver(I) ; platinum(II) ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Pseudoelement Compounds. XI. [1] Investigations on the Coordination Behaviour of Cyanamidonitrate [NO2NCN]-With the ionic, potentially ambidentate ligand cyanamidonitrate complexes of the types [MX(PPh3)3], [MX(PPh3)2]2 (M=CuI, AgI) and trans-[Pt(H)X(PPh3)2] (X-=[NO2NCN]-) are introduced. The new compounds are characterized by 1H NMR, 31P NMR, and IR spectroscopy. The crystal structures of [Cu(NO2NCN)(PPh3)2]2 and [Ag(NO2NCN)(PPh3)2]2 are reported. In the complexes [MX(PPh3)3] and trans-[Pt(H)X(PPh3)2] cyanamidonitrate is unidentately coordinated through the nitrile group end-on. In the dimeric complexes [MX(PPh3)2]2 the anion acts bidentately as a bridging ligand. Surprisingly, both coordinative bonds are formed through nitrogen atoms of the NCN group.
    Notes: Es werden mit dem ionischen, potentiell ambidenten Liganden Cyanamidonitrat Komplexe der Typen [MX(PPh3)3], [MX(PPh3)2]2 (M=CuI, AgI) sowie trans-[Pt(H)X(PPh3)2] (X-=[NO2NCN]-) vorgestellt. Die Verbindungen wurden 1H-NMR-, 31P-NMR- und IR-spektroskopisch charakterisiert. Für [Cu(NO2NCN)(PPh3)2]2 und [Ag(NO2NCN)(PPh3)2]2 liegen Kristallstrukturanalysen vor.Cyanamidonitrat wird in den Komplexen [MX(PPh3)3] und trans-[Pt(H)X(PPh3)2] einzähnig über das endständige N-Atom der Nitrilgruppe koordiniert. In den dimeren Komplexen [MX(PPh3)2]2 liegt das Anion als zweizähniger Brükkenligand vor. Überraschend werden beide koordinativen Bindungen über die Stickstoffatome der NCN-Gruppe ausgebildet.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19976230821
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  • 86
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    Kristallstruktur der Tieftemperaturmodifikation von RuTe2 (1997)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1657-1660 
    Details
    ISSN: 0044-2313
    Keywords: Ruthenium ; chalcogenide ; chemical transport ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Crystal Structure of the Low Temperature Modification of RuTe2Black shining, platelet like single crystals of α-RuTe2 were obtained by chemical transport reaction with Cl2/AlCl3 (crystal dimensions up to 1 mm). The crystal structure of this low temperature modification of α-RuTe2 hitherto only known from powder measurements, was redetermined at room temperature by single crystal X-ray diffraction on a four-circle diffractometer. α-RuTe2 crystallizes in the marcasit structure typ in the orthorhombic spacegroup Pnnm (No. 58) with the lattice constants a = 528.12(13), b = 639.43(19), c = 400.85(13) pm.
    Notes: Durch chemischen Transport mit dem Transportmittel Cl2/AlCl3 konnten schwarzglänzende, plattenartige Einkristalle von α-RuTe2 erhalten werden (Kantenlänge bis zu 1 mm). Die Kristallstruktur dieser bisher nur aus Pulverdaten bekannten Tieftemperaturmodifikation von RuTe2 wurde röntgenographisch an einem Einkristall auf einem Vierkreisdiffraktometer bei Raumtemperatur neu bestimmt. α-RuTe2 kristallisiert im Markasit-Strukturtyp in der orthorhombischen Raumgruppe Pnnm (Nr. 58) mit den Gitterkonstanten a = 528,12(13), b = 639,43(19), c = 400,85(13) pm.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19976231029
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  • 87
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    Mesityloxomolybdän- und -wolfram-Verbindungen. I. Die Struktur von LiMoO2Me2Mes(OEt2)2 (1997)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1661-1664 
    Details
    ISSN: 0044-2313
    Keywords: Organo molybdenum compounds ; oxo complexes ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Mesityl Oxo Molybdenum and Tungsten Compounds. I. Structure of LiMoO2Me2Mes(OEt2)2LiMoO2Me2Mes(OEt2)2 2 is prepared by literature method [2] from MoO2Mes2 1 and LiMe. Its x-ray structure and NMR-spectral data are presented. 2 adopts a dimer structure in which two [MoO2Me2Mes]- anions are linked via two bridging [Li(OEt2)2]+ cations bonded to the oxo ligands. The resulting [‥OMoOLi‥]2 ring is planar.
    Notes: Die Struktur der bekannten, aus MoO2Mes2 1 und LiMe dargestellten Verbindung LiMoO2Me2Mes(OEt2)2 2 [2] sowie ihre NMR-spektroskopischen Daten werden mitgeteilt. 2 bildet ein in der Raumgruppe P1 kristallisierendes Dimer durch Verknüpfung zweier [MoO2Me2Mes]--Anionen über Oxo-Liganden durch zwei Kationen [Li(OEt2)2]+. Der gebildete [‥OMoOLi‥]2- Achtring ist eben.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19976231030
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    Die 3-(N,N-Dimethylamino)prop-1-enyl-Gruppe als Chelatligand in Organoindium-Verbindungen (1997)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1679-1683 
    Details
    ISSN: 0044-2313
    Keywords: Organoindium compounds ; chelate complexes ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The 3-(N,N-Dimethylamino)prop-1-enyl Group as a Chelate Ligand in Indium OrganylsInBr3 reacts with Me2NCH2CH=CHMgCl (molar ratio 1 : 2) to form (Me2NCH2CH=CH)2InBr (1) as the first indium alkenyl compound with amino-functionalized alkenyl groups. The X-ray structure determination shows the formation of a chelate complex. 1 crystallizes in the orthorhombic space group Fddd with the unit cell parameters a = 14.904(2) Å, b = 17.140(1) Å and c = 21.035(2) Å. By reaction of Me2InBr with Me2NCH2CH=CHMgCl (molar ratio 1 : 1) (Me2NCH2CH=CH)InMe2 (2) is formed as a colorless, at room temperature liquid, monomeric compound. The n.m.r. and mass spectra are discussed.
    Notes: InBr3 reagiert mit Me2NCH2CH=CHMgCl (Molverhältnis 1 : 2) in Diethylether als Lösungsmittel zu (Me2NCH2CH=CH)2InBr (1), der ersten Indium-Alkenylverbindung mit aminofunktionalisierten Alkenylresten. Die Röntgenkristallstrukturanalyse zeigt das Vorliegen eines Chelatkomplexes an. 1 kristallisiert orthorhombisch in der Raumgruppe Fddd mit Z = 16, a = 14,904(2) Å, b = 17,1405(14) Å und c = 21,035(2) Å. Aus Me2InBr und Me2NCH2CH=CHMgCl (Molverhältnis 1 : 1) wurde (Me2NCH2CH=CH)InMe2 (2) als farblose, bei Raumtemperatur flüssige, monomere Verbindung erhalten. Die 1H- und 13C-NMR-Spektren sowie Massenspektren werden mitgeteilt.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19976231033
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    Contributions on thermal behaviour and crystal chemistry of anhydrous phosphates. XIX. Tri-chromium(II)-bis-phosphate Cr3(PO4)2 (≙ Cr6(PO4)4) - A transition metal(II)-orthophosphate with new structure type (1997)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1672-1678 
    Details
    ISSN: 0044-2313
    Keywords: Chromium(II)-orthophosphate ; crystal growth ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Beiträge zum thermischen Verhalten und zur Kristallchemie von wasserfreien Phosphaten. XIX. Tri-chrom(II)-bis-phosphat Cr3(PO4)2 (≙ Cr6(PO4)4) - Ein Übergangsmetall(II)- Orthophosphat mit neuem StrukturtypIntensiv blau-violette Kristalle des bislang unbekannten Tri-chrom(II)-bis-phosphats, Cr3(PO4)2, entstehen bei der Reduktion von CrPO4 mit Chrom oberhalb von 1050°C (evakuierte Quarzglasampullen, wenige mg NH4I oder I2 als Mineralisator). Die Kristallstruktur von Cr3(PO4)2 enthält sechs kristallographisch unabhängige Cr2+ in der Elementarzelle (P212121, Z = 8, a = 8,4849(10) Å, b = 10,3317(10) Å, c = 14,206(3) Å). Davon sind fünf in der ersten Koordinationssphäre von vier Sauerstoffatomen leicht verzerrt quadratisch-planar umgeben (1,96 Å ≤ d(Cr—O) ≤ 2.15 Å). Deren Koordination wird vervollständigt durch zwei bzw. drei weiter entfernte Sauerstoffatome (2,32 Å ≤ d(Cr—O) ≤ 3,21 Å). Das sechste Cr2+-Ion ist stark verzerrt oktaedrisch koordiniert (d(Cr—O): 1,97, 2,04, 2,15, 2,28, 2,29, 2,53 Å).Die vier kristallographisch unterschiedlichen [PO4]-Gruppen zeigen nur geringe Abweichungen von der Geometric eines idealen Tetraeders (1,51 Å ≤ d(P—O) ≤ 1,57 Å; 104,3° ≤ ∠(O—P—O) ≤ 114,4°).Für die Cr2+ wurde mit μexp = 4,28(2) μB (θP = -54,8(5) K) ein ungewöhnlich niedriges mittleres magnetische Moment gefunden.
    Notes: Deep blue-violet single crystals of hitherto unknown chromous orthophosphate have been obtained reducing CrPO4 by elemental Cr at temperatures above 1050°C in evacuated silica ampoules (NH4I or I2 as mineraliser). The complex structure of Cr3(PO4)2 (P212121, Z = 8, a = 8.4849(10) Å, b = 10.3317(10) Å, c = 14.206(2) Å) contains six crystallographically independent Cr2+ per unit cell. Five of them are coordinated by four oxygen atoms which form a distorted (roof shaped) square plane as first coordination sphere at interatomic distances 1.96 Å ≤ d(Cr—O) ≤ 2.15 Å. Their coordination is completed by additional oxygen atoms (2 or 3) at distances 2.32 Å ≤ d(Cr—O) ≤ 3.21 Å. The sixth Cr2+ shows six-fold octahedral coordination with strong radial distortion (d(Cr—O): 1.97, 2.04, 2.15, 2.28, 2.29, 2.53 Å).The four different [PO4] groups exhibit only minor deviations from ideal tetrahedral geometry (1.51 Å ≤ d(P—O) ≤ 1.57 Å, 104.3° ≤ ∠(O—P—O) ≤ 114.4°).An unusually low magnetic moment μexp = 4.28(2) μB (θP = -54.8(5) K) has been observed for Cr2+.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19976231032
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    Über den Einfluß von Temperatur, Druck und Substitution auf die Kristallstruktur von ARh2P2 (A = Ca, Sr, Eu, Ba)Professor Welf Bronger zum 65. Geburtstag gewidmet (1997)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1418-1424 
    Details
    ISSN: 0044-2313
    Keywords: Ternary Rhodium phosphides ; crystal structure ; phase transition ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: About the Effect of Temperature, Pressure, and Substitution on the Crystal Structure of ARh2P2 (A = Ca, Sr, Eu, Ba)Four compounds ARh2P2 (A = Ca, Sr, Eu, Ba) were prepared by heating mixtures of the elements and investigated by means of single crystal X-ray methods. They crystallize in the ThCr2Si2 type structure (I4/mmm; Z = 2) with P—P distances along [001] reaching from 2.26 Å (CaRh2P2) to 3.74 Å (BaRh2P2). With increasing temperature (EuRh2P2) or increasing pressure (SrRh2P2) a first order phase transition occurs with strong changes of the P—P distances. Substitution of the atoms changes the bond lengths of the compounds too.
    Notes: Vier Verbindungen ARh2P2 (A = Ca, Sr, Eu, Ba) wurden durch Erhitzen entsprechender Elementgemenge dargestellt und hinsichtlich ihrer Kristallstruktur mit Hilfe von Einkristallmethoden charakterisiert. Sie kristallisieren in der tetragonalen ThCr2Si2-Struktur (I4/mmm; Z = 2) und unterscheiden sich im wesentlichen durch ihre P—P-Abstände längs [001]. Diese reichen von 2,26 Å bei CaRh2P2 bis 3,74 Å bei BaRh2P2 und verändern sich drastisch im Zuge von Phasenumwandlungen 1. Ordnung durch Temperaturerhöhung bei EuRh2P2 sowie unter erhöhtem Druck bei SrRh2P2. Substitution übt ebenfalls einen großen Einfluß auf den Strukturfeinbau der Verbindungen aus.
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    URL: http://dx.doi.org/10.1002/zaac.19976230917
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    Zur Kristallstruktur von Tb2Se3 (1997)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1744-1746 
    Details
    ISSN: 0044-2313
    Keywords: Terbium sesquiselenide ; chemical transport ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Crystal Structure of Tb2Se3Single crystals of Tb2Se3 could be prepared by chemical transport reaction with AlCl3. By starting from TbSe1.9 and terbium metal black needles of Tb2Se3 in the U2S3 type structure with the space group Pnma and a = 1113,0(1) pm, b = 402,4(1) pm and c = 1095,1(3) pm were obtained.
    Notes: Einkristalle von Tb2Se3 konnten durch chemischen Transport mit AlCl3 dargestellt werden. Ausgehend von pulverförmigem TbSe1,9 und Terbiummetall wurden schwarze, nadelförmige Einkristalle von Tb2Se3 im U2S3-Strukturtyp mit der Raumgruppe Pnma und a = 1113,0(1) pm, b = 402,4(1) pm und c = 1095,1(3) pm erhalten.
    Additional Material: 5 Tab.
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    URL: http://dx.doi.org/10.1002/zaac.19976231113
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    Nitridsulfidchloride der Lanthanide: III. Synthese und Kristallstruktur von Pr5N3S2Cl2Professor Rudolf Hoppe zum 75. Geburtstag gewidmet (1997)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1747-1752 
    Details
    ISSN: 0044-2313
    Keywords: Lanthanides ; nitride sulfide chlorides ; Pr5N3S2Cl2 ; synthesis ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Nitride Sulfide Chlorides of the Lanthanides. III. Synthesis and Crystal Structure of Pr5N3S2Cl2By reacting praseodymium with sulfur, sodium azide and praseodymium trichloride in sealed, evacuated silica tubes (850°C, 7 d), the nitride sulfide chloride Pr5N3S2Cl2 is obtained in case of a 4:2:1:1 molar ratio of the reactants (Pr:S:NaN3:PrCl3). A slight excess of trichloride or the addition of NaCl as a flux supports the yield of brownish red, rod-shaped transparent crystals which prove to be stable against hydrolysis. The crystal structure (monoclinic, C2/m (no. 12), a = 1540.2(1), b = 400.92(3), c = 1656.3(1) pm, β = 101.24(1)°, Z = 4, R = 0.039, Rw = 0.028) was determined by means of X-ray single crystal data. Thus five crystallographically different cations (Pr3+) are present which with three distinct kinds of nitride anions (N3-) build up two types of translationally commensurate chains from interconnected [NPr4] tetrahedra. With an additional edge per “chain-link” in chain I, two single chains ∞1[NPr3/3ePr1/1t]3+ (≡∞1[NPr2]3+) of cis-edge connected [NPr4] tetrahedra (known from the Sm4N2S3-type structure) are condensed into the double chain ∞1[(N1){(Pr1)(2+2)/(2+2)e,e(Pr2)(2+1)/(2+1)e,v}(N2)(Pr3)1/1t]3+ (≡∞1[N2Pr3]3+). Chain II consists of two single chains ∞1[NPr2/2vPr2/1t] 6+ (≡∞1[NPr3]6+) of vertex-connected [NPr4] tetrahedra (known from the Sm3NS3-type structure), which are condensed to the double chain ∞1[(N3)(Pr4)2/2e(Pr5)2/2v]3+ (≡∞1[NPr2]3+) via an additional edge per “chain-link” too. Both types of chains are bundled along [010] like a closest packing of rods. Four crystallographically different but by X-ray diffraction indistinguishable anions S2- and Cl- hold both cationic double chains together and also adjust the charge balance in a molar ratio of 1 : 1.
    Notes: Durch Umsetzung von Praseodym mit Schwefel, Natriumazid und Praseodymtrichlorid in evakuierten Quarzglasampullen (850°C, 7 d) wird bei molaren Verhältnissen der Edukte (Pr:S:NaN3:PrCl3) von 4:2:1:1 das Nitridsulfidchlorid Pr5N3S2Cl2 erhalten. Ein geringer Überschuß an Trichlorid oder der Zusatz von NaCl als Flußmittel fördert die Bildung von braunroten, stäbchenförmigen, transparenten Kristallen, die sich als unempfindlich gegenüber Hydrolyse erweisen. Die Kristallstruktur (monoklin, C2/m (Nr. 12); a = 1540,2(1); b = 400,92(3); c = 1656,3(1) pm; β = 101,24(1)°, Z = 4; R = 0,039; Rw = 0,028) wurde röntgenographisch anhand von Einkristalldaten bestimmt. Danach liegen fünf kristallographisch unterschiedliche Kationen. (Pr3+) vor, die mit drei verschiedenen Sorten von Nitridionen (N3-) zwei Typen translationskommensurabler Stränge aus verknüpften [NPr4]-Tetraedern bilden. In Strang I werden zwei Einfachketten ∞1[NPr3/3kPr1/1t]3+ (≡∞1[NPr2]3+) cis-kantenverknüpfter [NPr4]-Tetraeder (bekannt aus der Sm4N2S3-Struktur) über eine zusätzliche Kante pro „Kettenglied“ zur Doppelkette ∞1[(N1){(Pr1)(2+2)/(2+2)k,k(Pr2)(2+1)/(2+1)k,e}(N2)(Pr3)1/1t]3+ (≡∞1[N2Pr3]3+) verknüpft. Strang II besteht aus zwei Einfachketten ∞1[NPr2/2ePr2/1t]6+ (≡∞1[NPr3]6+) eckenverknüpfter [NPr4]-Tetraeder (bekannt aus der Sm3NS3-Struktur), die über eine zusätzliche Kante pro „Kettenglied“ zur Doppelkette ∞1[(N3)(Pr4)2/2k(Pr5)2/2e]3+ (≡∞1[NPr2]3+) kondensiert sind. Beide Strangsorten ordnen sich längs [010] nach dem Motiv einer dichtesten Stabpackung an. Vier kristallographisch unterschiedliche, röntgenographisch jedoch nicht unterscheidbare Anionen S2- und Cl- sorgen für den Zusammenhalt der kationischen Doppelketten und regeln im molaren Verhältnis von 1 : 1 auch den Ladungsausgleich.
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    URL: http://dx.doi.org/10.1002/zaac.19976231114
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    Darstellung und Struktur eines Ammoniumdiamidodioxophosphats(V), NH4PO2(NH2)2Professor Rudolf Hoppe zum 75. Geburtstag gewidmet (1997)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1786-1790 
    Details
    ISSN: 0044-2313
    Keywords: Ammonium diamido dioxo phosphate(V) ; synthesis ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Structure of an Ammonium Diamidodioxophosphate(V), NH4PO2(NH2)2The ammonolysis of P3N5 under ammonothermal conditions (T = 400°C, p(NH3) = 6 kbar, 14 d in autoclaves) in the presence of small definite amounts of water leads to the formation of NH4PO2(NH2)2. The structure was solved by single crystal X-ray methods.NH4PO2(NH2)2: P21/c (Nr. 14), a = 6.886(1) Å, b = 8.366(2) Å, c = 9.151(2) Å, β = 111.78(3)°, Z = 4, R1/wR2 = 0.026/0.072, Z(Fo2 〉 2σ(Fo2)) = 1183, N(variables) = 87. In NH4PO2(NH2)2 the anions [PO2(NH2)2]- are linked to chains by N—H … N and N—H … O bridge bonds. The ammonium ions are located between these chains and are donors for N—H … O bridge bonds which connect the chains three-dimensionally.
    Notes: Bei Ammonolysen von P3N5 unter ammonothermalen Bedingungen (T = 400°C und p(NH3) = 6 kbar 14 d in Autoklaven) führt eine geringe, definierte Menge Wasser zur Bildung von NH4PO2(NH2)2. Die Struktur wurde röntgenographisch am Einkristall bestimmt.NH4PO2(NH2)2: P21/c (Nr. 14), a = 6,886(1) Å, b = 8,366(2) Å, c = 9,151(2) Å, β = 111,78(3)°, Z = 4, R1/wR2 = 0,026/0,072, Z(Fo2 〉 2σ(Fo2)) = 1183, Z(Variable) = 87. In NH4PO2(NH2)2 sind Anionen [PO2(NH2)2]-, über N—H … N und N—H … O Brückenbindungen zu unendlichen Ketten verknüpft. Die Ammoniumionen liegen zwischen den Ketten und wirken als Donatoren für N—H … O Brückenbindungen, die die Ketten dreidimensional verknüpfen.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19976231121
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    Die Kristallstruktur von (Al0,5Ga0,5)CuOAsO4 - Kupfer zwischen planarer und geschlossener KoordinationProfessor Rudolf Hoppe zum 75. Geburtstag gewidmet (1997)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1781-1785 
    Details
    ISSN: 0044-2313
    Keywords: Copper ; aluminium ; gallium ; oxide arsenate ; crystal structure ; oxidation of alloys ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Crystal Structure of (Al0,5Ga0,5)CuOAsO4 - Copper Intermediate between Planar and Closed CoordinationSingle crystals of the new oxide arsenate (Al0.5Ga0.5)CuOAsO4 (monoclinic, P21/c, a = 734.3(2) pm, b = 1024.79(9) pm, c = 563.4(2) pm, β = 99.93(1)°, Z = 4) were obtained by reaction of Al/As/Cu/Ga-alloys with oxygen. The crystal structure was determined from four-circle diffractometer data (w2R = 0.039 for 1211 F2 values and 76 parameters). The structure contains [Cu2O6] double squares arranged in slabs perpendicular to the a axis such that a [4 + 1]-coordination of the copper atoms by oxygen atoms results which is intermediate between square-planar and square-pyramidal. Along [100] layers of corner sharing (Al/Ga)O4 and AsO4 tetrahedra are alternating with buckled Cu layers.
    Notes: Einkristalle des neuen Oxidarsenats (Al0,5Ga0,5)CuOAsO4 (monoklin, P21/c, a = 734,3(2) pm, b = 1024,79(9) pm, c = 563,4(2) pm, β = 99,93(1)°, Z = 4) wurden durch Oxidation von Al/As/Cu/Ga-Legierungen im Sauerstoffstrom erhalten. Die Kristallstruktur wurde aus Vierkreisdiffraktometer-Daten bestimmt (w2R = 0,039 für 1211 F2-Werte und 76 Parameter). [Cu2O6]-Doppelquadrate sind in Schichten senkrecht zur a-Achse so angeordnet, daß für Kupfer eine [4 + 1]-Koordination durch Sauerstoffatome resultiert, die als Übergang von quadratisch-planarer zu quadratisch-pyramidaler Koordination interpretiert werden kann. In [100]-Richtung wechseln Schichten aus eckenverknüpften (Al/Ga)O4- und AsO4-Tetraedern mit gewellten Cu-Schichten ab.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19976231120
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    Na4AuTl, die erste ternäre Verbindung im System Natrium/Gold/Thallium (1997)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1621-1624 
    Details
    ISSN: 0044-2313
    Keywords: Sodium auride thallide ; gold chains ; thallium dumb-bells, synthesis ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Na4AuTl, the First Ternary Compound in the System Sodium/Gold/ThalliumSilver coloured, brittle single crystals of Na4AuTl were obtained by the reaction of NaN3, gold sponge and TlN3 at 773 K. The structure was determined from X-ray single-crystal diffractometry data: \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm space}\,{\rm group}\,{\rm Fmmm,}\,{\rm Z = 8,}\,{\rm a = 5}{\rm .453(1)}\mathop {\rm A}\limits^ \circ,\,{\rm b = 10}{\rm .006(2)}\,\,\mathop {\rm A}\limits^ \circ,\,{\rm c = 23}{\rm .387(5)}\,\mathop {\rm A}\limits^ \circ $$\end{document} Na4AuTl crystallizes in a new structure type with separated gold and thallium partial structures. These consist of linear ∞1[Au2/2] chains and [Tl2] dumb-bells. Structural relationships between Na2Au and the Na Au partial structure of Na4AuTl are discussed.
    Notes: Silberfarbene, spröde Einkristalle eines bislang unbekannten Na4AuTl wurden durch Umsetzung von NaN3, Goldschwamm und TlN3 bei 773 K erhalten. Die Struktur wurde aus Röntgen-Einkristall-Diffraktometerdaten bestimmt: \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm Raumgruppe}\,{\rm Fmmm,}\,{\rm Z = 8,}\,{\rm a = 5,453(1)}\mathop {\rm A}\limits^ \circ,\,{\rm b = 10,006(2)}\,\,\mathop {\rm A}\limits^ \circ,\,{\rm c = 23,387(5)}\,\mathop {\rm A}\limits^ \circ $$\end{document} Na4AuTl kristallisiert in einem neuen Strukturtyp mit voneinander separierten Gold- und Thallium-Teilstrukturen, die aus linearen ∞1[Au2/2]-Ketten und [Tl2]-Hanteln aufgebaut sind. Strukturbeziehungen zwischen Na2Au und der Na—Au-Teilstruktur von Na4AuTl werden diskutiert.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19976231023
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    Untersuchungen an Natriumtrifluormethylsulfonat - Kristallstruktur und Phasenumwandlung des Monohydrats und Natriumionenleitfähigkeit des wasserfreien Salzes (1997)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1625-1632 
    Details
    ISSN: 0044-2313
    Keywords: Sodium trifluormethanesulfonate ; monohydrate ; crystal structure ; phase transition ; sodium ionic conduction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Studies on Sodium Trifluormethanesulfonate - Crystal Structure and Phase Transition of Sodium Trifluormethanesulfonate Monohydrate and Sodium Ion Conductivity of Anhydrous Sodium TrifluormethanesulfonateAccording to the results of temperature dependent powder diffractometry (Guinier-Simon-technique) sodium trifluormethanesulfonate monohydrate is dimorphous. The phase transition occurs at -35°C. The room-temperature modification crystallizes monoclinic in space group P21/c with the lattice parameters a = 941.6(5) pm, b = 654.3(2) pm, c = 1062.4(5) pm and β = 107.73(2)°. The crystal structure consists of double layers of trifluormethanesulfonate anions, the lipophilic CF3-groups pointing at each other. Sodium is coordinated by four oxygen atoms from four different anions and by two molecules of crystal water. The resulting polyhedron may be addressed as a distorted octahedron. The low-temperature modification crystallizes orthorhombic in space group Pnma with the lattice parameters a = 645.31(9) pm, b = 538.03(9) pm, c = 1745.3(3) pm. The loss of crystal water occurs at 136°C. Anhydrous sodium trifluormethanesulfonate shows a phase transition at 252°C. The high-temperature modification is a good sodium ionic conductor (σ = 4.1 · 10-1 Ω-1 cm-1 at 250°C).
    Notes: Nach Kühl-Guinier-Simon-Untersuchungen ist Natriumtrifluormethylsulfonatmonohydrat dimorph. Die Phasenumwandlung erfolgt bei -35°C. Die Raumtemperaturmodifikation kristallisiert monoklin in der Raumgruppe P21/c mit den Gitterkonstanten a = 941,6(5) pm, b = 654,3(2) pm, c = 1062,4(5) pm und β = 107,73(2)°. In der Kristallstruktur liegen Doppelschichten aus Trifluormethylsulfonatanionen vor, in denen die unpolaren CF3-Gruppen einander zugewandt sind. Natrium wird von jeweils einem Sauerstoffatom aus vier verschiedenen Anionen sowie von zwei Kristallwassermolekülen koordiniert und erreicht eine verzerrt oktaedrische Koordination. Die Tieftemperaturmodifikation kristallisiert orthorhombisch in der Raumgruppe Pnma mit den Gitterkonstanten a = 645,31(9) pm, b = 538,03(9) pm, c = 1745,3(3) pm. Die Abgabe von einem Mol Kristallwasser erfolgt bei 136°C. Wasserfreies Natriumtrifluormethylsulfonat zeigt eine Phasenumwandlung in eine Hochtemperaturmodifikation bei 252°C, die eine gute Natriumionenleitfähigkeit zeigt (σ = 4,1 · 10-1 Ω-1 cm-1 bei 250°C).
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19976231024
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    Darstellung und Kristallstrukturanalyse von Bis(π-pentamethylcyclopentadienyl) (2-methylen)(3-diphenylmethylen)oxatitanacyclobutan Cp*2 (1997)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 654-658 
    Details
    ISSN: 0044-2313
    Keywords: Titanium ; vinylidcne complexes ; cycloaddition reaction ; oxatitanacyclobnlanes ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Preparation and Crystal Structure of Bis(π-pentamethylcyclopentadienyl) (2-methylene)(3-diphenylmethylene)oxatitanacyclobutane Cp*2 The title complex 5 was synthesized by a [2 + 2]-cycloaddition reaction of diphenytkelene and the titanaallene fragment [Cp2*Ti=C=CH2] (3). Complex 5 was characterized using 1H and 13C NMR spectra and by X-ray structure analysis, respectively.
    Notes: Der Titelkomplex 5 wurde durch [2 + 2]-Cycloaddition von Diphenylketen mit dem Titanaallenfragment [Cp2*Ti=C=CH2] (3) erhalten. Verbindung 5 wurde 1H- und 13C-NMR-spektroskopisch, sowie durch eine Einkristallstrukturanalyse charakterisiert.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.199762301104
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    Derivate des Imidazols. XXIII. 2-Iminoimidazolin-Derivate des Magnesiums und AluminiumsProfessor Günter Schmid zum 60. Geburtstag gewidmet (1997)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 554-560 
    Details
    ISSN: 0044-2313
    Keywords: Magnesium ; aluminium ; 2-iminoimidazoline complexes ; imidazole derivatives ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Imidazole Derivatives. XXIII. 2-Iminoimidazoline Derivatives of Magnesium and Aluminum1,3-dimethyl-2-iminoimidazoline (7, ImNH) forms with MgI2 the complex [(ImNH)4Mg]I2 (8). Whose X-ray structure analysis implies the presence of NHN bridges in the cation. With MeMgI and n-Bu2Mg the polymeric coordination compounds [(ImN)MgI]n (9) and [(ImN)2Mg]n (10) are formed. 7 and it's trimethylsilyl derivative 12 react with AlMe2Cl to give the ionic complexes [(ImNR)2AlMe2]Cl (11, 13, R = H, SiMe3) which are stable with respect to the formation of imidazol-2-imino complexes. The adduct ImNSiMe3 · AlCl3 (14) accessible from the reaction of 12 and AlCl3 eliminates chlorotrimethylsilane on heating to give the trimeric imino complex [(ImN)AlCl2]3 (15); the X-ray structure of 15 confirms the high π-donor properties of the imino substituent.
    Notes: 1,3-Dimethyl-2-iminoirnidazolin (7, ImNH) bildet mit MgI2 den Komplex [(ImNH)4Mg]I2 (8), dessen Kristallstrukturanalyse das Vorliegen von NHN-Brücken innerhalb des Kations glaubhaft macht. Mit MeMgI und n-Bu2Mg werden die Koordinationspolymeren [(ImN)Mgl]n (9) und [(ImN)2Mg]n (10) gebildet. 7 und dessen Trimethylsilyl-Derivat ImNSiMe3 (12) reagieren mit AlMe2Cl zu den ionischen Komplexen [(ImNR)2AlMe2]Cl (11, 13; R = H, SiMe3), die sich als thermisch stabil bezüglich der Bildung von Imidazol-2-imino-Komplexen erweisen. Das aus 12 und AlCl3 zugängliche Addukt ImNSiMe3 · AlCl3, (14) eliminiert bei thermischer Belastung Chlortrimethylsilan: die strukturanalytische Charakterisierung des trimeren Imino-Komplexes [(ImN)AlCl2]3 (15) belegt die hohe π-Donorkapazität des Imino-Substituenten.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19976230186
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    K3[SnSb3], eine Zintl-Phase mit ∞1[SnSb3]3--BändernProfessor Joachim Strähle zum 60. Geburtstag gewidmet (1997)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 561-564 
    Details
    ISSN: 0044-2313
    Keywords: Tripotassium triantimonidostannate(II) ; anionic chains of six-membered rings ; crystal structure ; Zintl phase ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: K3[SnSb3], a Zintl Phase with ∞1[SnSb3]3- ChainsThe metallic lustrous air sensitive compound K3[SnSb3] was prepared from melts of mixtures of the elements. K3[SnSb3] crystallizes in the monoclinic system, group C2/m (No 12), Z = 2, with lattice constants a = 1768.6(2) pm, b = 428.1(1) pm. c = 604.5(1) pm, β = 95.72(5)°. In the anionic partial structure six-membered rings [Sn2Sb4] with chair conformation are connected via common edges to infinite chains ∞1[SnSb3]3-. The potassium cations separate the chains from each other.
    Notes: Die metallisch glänzende, sehr hydrolyseempfindliche Verbindung K3[SnSb3] wurde aus Schmelzreaktionen, ausgehend von Gemengen der Elemente erhalten. K3[SnSb3] kristallisiert monoklin in der Raumgruppe C2/m (Nr, 12), Z = 2, mit den Gitterkonstanten a = 1768,6(2) pm, b = 428,1(1) pm, c = 694,5(1) pm, β = 95,72(5)°. In der Anionenteilstruktur sind [Sn2Sb4]-Sechsringe in Sesselkonformation über zwei gegenüberliegende Kanten zu eindimensional unendlichen ∞1[SnSb3]3--Bändern verknüpft. Die Kaliumkationen separieren die Bänder voneinander.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19976230187
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    Se17[NbCl6]2 und Se17[TaBr6]2 - zwei neue Vertreter des Strukturtyps Se17[MX6]2Professor Joachim Strähle zum 60. Geburtstag gewidmet (1997)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 780-784 
    Details
    ISSN: 0044-2313
    Keywords: Heptadecaselenium(2+) ; Hexachloroniobate(-) ; Hexabromotantalate(-) ; solvothermal reactions ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Se17[NbCl6]2 and Se17[TaBr6]2 - Two New Compounds in the Structure Type Sel7[MX6]2The reaction of Se, SeCl4 and NbCl5 in SnCl4 in a sealed glass ampoule at 150°C yields Se17[NbCl6]2 and from Se, SeBr4 and TaBr5 in SiBr4 under the same conditions Se17[TaBr6]2 is formed. Both compounds crystallize triclinic in form of black moisture sensitive crystals, space group P1, Z = 2 (Se17[NbCl6]2: a = 1322.3(5) pm, b = 1309.0(6) pm, c = 1144.9(4) pm, α = 99.18(3)°, β = 99.55(3)°, γ = 112.17(3)°; Se17[TaBr6]2; 1354.5(7) pm, b = 1346.0(9) pm c = 1179.5(6) pm, α = 99.26(5)°, β = 97.81(4)°, γ = 112.52(5)°). Both are isotypic to the previously reported Se17[WCl6]2. The structures are built of octahedral [NbCl6] and [TaBr6] ions, respectively, and of (Se17)2+ ions The cations consist of two Se7 rings which are connected by a Se3 chain, and thus contain two three-coordinate Se atoms which carry formally the positive charge.
    Notes: Durch solvothermale Reaktion von Se, SeCl4 und NbCl5 in SnCl4 in einer geschlossenen Ampulle bei 150°C entsteht Se17[NbCl6]2 und aus Se, SeBr4 und TaBr5 in SiBr4 unter analogen Bedingungen Se17[TaBr6]2. Beide Verbindungen kristallisieren triklin in Form schwarzer, hydrolyseempfindlicher Kristalle, Raumgruppe P1, Z = 2 (Se17[NbCl6]2: a = 1322,3(5) pm, b = 1309,0(6) pm, c = 1144,9(4) pm, α = 99,18(3)°, β = 99,55(3)°, γ = 112,17(3)°; Se17[TaBr6]2: 1354,5(7) pm, b = 1346,0(9) pm, c = 1179,5(6) pm, α = 99,26(5)° β = 97,81(4)°, γ = 112,52(5)°) und sind isotyp zu Se17[WCl6]2 Die Strukturen sind aus oktaedrischen [NbCl6]- - bzw. [TaBr6]-- und aus (Se17)2+-Ionen aufgebaut, die aus jeweils zwei Se7-Ringen bestehen, die über eine Se3-Brücke verknüpft sind. Jedes Ion enthält zwei dreibindige Se-Atome, die formal die positive Ladung tragen.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.199762301123
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