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  • 1985-1989  (116)
  • 1975-1979  (508)
  • 1890-1899
  • 1800-1809
  • 1988  (116)
  • 1975  (508)
  • Industrial Chemistry  (453)
  • Electron microscopy  (171)
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Years
  • 1985-1989  (116)
  • 1975-1979  (508)
  • 1890-1899
  • 1800-1809
Year
Keywords
  • 1
    Electronic Resource
    Electronic Resource
    On the ultrastructure of ependymomas — A semiquantitative analysis of diagnostic criteria in 21 cases with special reference to glycogen as a marker (1988)
    Springer
    Neurosurgical review 11 (1988), S. 67-76 
    Details
    ISSN: 1437-2320
    Keywords: Electron microscopy ; ependymoma ; glycogen ; ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report our results on the ultrastructure of 21 ependymomas and establish the following diagnostic criteria: 1. Glycogen is the most frequently encountered criterion, followed by desmosomes, cilia, basal bodies and microvilli. Fifteen tumors had 3 or more of these features. 2. The allegedly typical nuclear pattern was found in only 6 cases. 3. Special ultrastructural features seen include basement membranes in a mid-thoracic ependymoma. Furthermore we propose the hypothesis that glycogen might be involved in cilia assembly.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01795697
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  • 2
    Electronic Resource
    Electronic Resource
    Origin and direction of replication in mitochondrial plasmid DNAs of broad bean,Vicia faba (1988)
    Springer
    Current genetics 14 (1988), S. 163-170 
    Details
    ISSN: 1432-0983
    Keywords: Plant mtDNA ; Electron microscopy ; Restriction enzymes ; Hairpin structures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Broad bean (Vicia faba) mitochondrial DNA (mtDNA) includes three circular plasmids: mt-plasmid 1 (1,704 ntp), mt-plasmid 2 (1,695 ntp) and mt-plasmid 3 (1,476 ntp). Partially replicated circular forms of these mt-plasmids have been observed in electron microscope preparations. Restriction enzymes that cleave either mt-plasmid 2 (but not mt-plasmids 1 and 3) or mt-plasmid 3 (but not mt-plasmids 1 and 2) were used to generate linear forms of partially replicated mt-plasmid 2 and mt-plasmid 3 molecules. Analyses of these linearized replicative intermediates, observed by electron microscopy, indicated that in both mt-plasmid 2 and mt-plasmid 3 replication originates at a specific location and proceeds in the same, single direction around the molecules. The replication origins of mt-plasmid 2 and mt-plasmid 3 map close to sequences that can fold into hairpin structures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00569340
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  • 3
    Electronic Resource
    Electronic Resource
    Malignant peripheral neuroectodermal tumours of bone other than Askin's neoplasm: characterization of 14 new cases with immunohistochemistry and electron microscopy (1988)
    Springer
    Virchows Archiv 412 (1988), S. 421-430 
    Details
    ISSN: 1432-2307
    Keywords: Neuroectodermal bone tumours ; Immunochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Peripheral neuroectodermal tumours (PNET) of bone are rare and mimick those seen in soft tissue (peripheral neuroepithelioma of soft tissue). Their differential diagnosis from Ewing's sarcoma (Es) is extremely difficult by optical means. Here we report 14 new cases of PNET of bone (other than Askin's neoplasm) located primarily in the limbs, pelvic girdle and scapula. Clinically and radiologically they displayed Ewing's sarcoma-like features: mean age was 14.4 years, male/ female ratio being 3:11. Metastasis was present in 6 cases at diagnosis (5 with bone metastasis). Prognosis was poor; thirteen patients died; only one with a metatarsal located tumour is alive and free of disease. The mean survival rate was 25 months following diagnosis and treatment with radio- and multimodal chemotherapy. Histologically the 14 cases displayed Homer-Wright rosettes and pseudorosette-like structures, as well as a fibrillary background and lobular pattern. Immunohistochemistry revealed positivity in a number of neural markers when using paraffin-embedded material: NSE, B-2-microglobuline, HNK-1 (leu-7) and E-36 antibodies. At EM level the cell cytoplasms evidenced dense-core granules with neurosecretion, neurotubules and intermediate filaments like those seen in peripheral neuroepithelioma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00750576
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  • 4
    Electronic Resource
    Electronic Resource
    Alveolar soft part sarcoma (1988)
    Springer
    Virchows Archiv 412 (1988), S. 499-513 
    Details
    ISSN: 1432-2307
    Keywords: Alveolar soft part sarcoma ; Cytology ; Electron microscopy ; Immunohistochemistry ; DNA analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The type, differentiation and histogenesis of the tumor cells of alveolar soft part sarcoma (ASPS) have been analyzed in a series of ten cases by a light-microscopic, ultrastructural, immunohistochemical and cytologic investigation and quantitative DNA analysis. Four tumors deviated from ordinary ASPS: three were wholly or partly of the so-called pleomorphic variant of ASPS and a fourth tumor showed calcifications of the psammoma body type. The ultrastructural findings and immunohistochemical demonstration of desmin supported the hypothesis of a rhabdomyomatous differentiation and gave no support to epithelial (negative immunoreactions for cytokeratins, epithelial membrane antigen, HMFG-1 and -2, tissue polypeptide antigen (TPA)) or neuroectodermal (negative for S-100 protein, glial fibrillary acidic protein, neurofilaments) differentiation. The negative immunoreactions for vimentin and myoglobin and the positive reaction for neuron specific enolase (NSE) do not exclude a rhabdomyomatous differentiation since in rhabdomyosarcomas the undifferentiated rhabdomyoblasts generally contain vimentin and the differentiated tumor cells contain myoglobin and rhabdomyosarcoma has previously been reported as being positive for NSE. The production of external lamina material peripherally in the tumor cell nests and around vessels in the vascular septa was demonstrated both ultrastructurally and by immunohistochemistry using antibodies against collagen IV and laminin. The cytologic appearance in smears obtained by fine-needle aspiration from a case of the pleomorphic variant showed some resemblance to that of a carcinoma. The seven tumors with an ordinary cell appearance were found to show a diploid DNA-distribution at a quantitative analysis performed on paraffin sections, while the three tumors wholly or partly of the pleomorphic type showed an additional tetraploid peak.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00844286
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  • 5
    Electronic Resource
    Electronic Resource
    Ultrastructural and immunohistochemical findings in oral hairy leukoplakia (1988)
    Springer
    Virchows Archiv 412 (1988), S. 533-542 
    Details
    ISSN: 1432-2307
    Keywords: Hairy leukoplakia ; Electron microscopy ; Epstein-Barr virus ; Candida albicans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Three cases of HL from the lateral border of the tongue of male homosexual AIDS patients were investigated by thin section electron microscopy. Keratinocytes contained condensed chromatin in their pyknotic nuclei and a few organelles in the oedematous cytoplasm. Chromatin was in close association to the nuclear membrane and showed a punched-out appearance. Particles typical of the herpes virus group were abundant in the upper two thirds of the epithelium in all three cases. Virus particles were seen frequently in the nuclei of the ballooned keratinocytes, but rarely in cells containing Candida albicans. Viral nucleocapsids were observed budding at the inner nuclear membrane, thereby acquiring the prospective viral envelope. Complete, enveloped virions were found in the endoplasmic reticulum and in the extracellular space. These virions were identified immunohistochemically as Epstein-Barr virus (EBV) using two monoclonal antibodies directed against EBV capsid and membrane antigen, respectively. Candida albicans was observed in the stratum corneum and in the upper layer of the stratum spinosum. Special cytoplasmic tubular structures arranged in parallel bundles were found in koilocytotic cells in addition to characteristic membrane structures composed of undulating convoluted membranes. Epithelial basement membranes were always intact.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00844289
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  • 6
    Electronic Resource
    Electronic Resource
    Ultrastructural features of acute monoblastic leukaemia cells: A multivariate morphometric analysis (1988)
    Springer
    Virchows Archiv 414 (1988), S. 21-27 
    Details
    ISSN: 1432-2307
    Keywords: Monoblastic leukaemia ; Electron microscopy ; Morphometry ; Multivariate statistics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Morphometric studies were carried out on five ultrastructural measures of size or quantity of some of the intracellular organelles in monoblasts obtained from six patients diagnosed as having acute monoblastic leukaemia and also on monocytes from six normal controls. The morphometric measures were analysed using a one way multivariate analysis of variance (MANOVA) to see whether acute monoblastic leukaemic cells differed from those of normals. It was found that there was a highly significant decrease both in the surface to volume ratio of mitochondria and also in the surface to volume ratio of the nucleus. The possible physiological significance of these structural changes is stressed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00749734
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  • 7
    Electronic Resource
    Electronic Resource
    Osteosarcoma with a clear-cell component (1988)
    Springer
    Virchows Archiv 412 (1988), S. 273-279 
    Details
    ISSN: 1432-2307
    Keywords: Osteosarcoma ; Clear cell ; Histopathology ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The reports concerns the light microscopical and ultrastructural findings obtained in three conventional osteosarcomas with an unusually high admixture of clear cells, whose presence appeared to be responsible for the marked change in the histological pattern of these tumours. In the tumours with a prevailing fibroblastic component the clear cells were either irregularly scattered throughout the tumour in the form of small groups, or they formed large groups sharply demarcated against the fusicellular areas of the tumours. In two cases it was shown that their cytoplasm contained exaggerated glycogen deposits accompanied by the formation of glycogen-containing phagolysosomes and occasional empty vacuoles. In the third case the clear cells showed vacuolar degeneration with numerous single-membrane-bound, empty vacuoles. In contrast to the clear-cell chondrosarcoma we did not find S-100 protein in clear cells of our osteosarcomas. Such findings could be particularly significant in the differential diagnosis of bone tumours.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00737152
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  • 8
    Electronic Resource
    Electronic Resource
    Oncocytomas and null cell adenomas of the human pituitary: Morphometric and in vitro functional comparison (1988)
    Springer
    Virchows Archiv 413 (1988), S. 333-339 
    Details
    ISSN: 1432-2307
    Keywords: Electron microscopy ; Morphometry ; Null cell adenoma ; Oncocytoma ; Pituitary adenoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In this study, light microscopic and ultrastructural morphometric features of oncocytomas and null cell adenomas were compared and the morphometric data were correlated with in vitro endocrine activity. All tumours were unassociated with clinical or biochemical evidence of hormone excess and were diagnosed as oncocytomas or null cell adenomas, using histology, immunohistochemistry and electron microscopy. In oncocytomas, when compared with null cell adenomas, light microscopic morphometry revealed that total cell areas were significantly larger and nuclear cytoplasmic ratios were smaller due to an increase in cytoplasmic areas. Ultrastructural morphometry disclosed an abundance of mitochondria in oncocytomas. Absolute volumes of cytoplasmic organelles per cell were not reduced in oncocytomas compared with those of null cell adenomas. These results indicate that accumulating mitochondria do not replace other cytoplasmic organelles, and furthermore that the functional potential of oncocytomas is not lost. In vitro study demonstrated the production of pituitary hormones, primarily gonadotropins in oncocytomas and null cell adenomas. It can be concluded that oncocytomas, which represent the final stage of oncocytic transformation, have a close relationship with null cell adenomas based on morphometric comparison as well as in vitro studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00783026
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  • 9
    Electronic Resource
    Electronic Resource
    Small cell neuroendocrine carcinoma of the urinary bladder (1988)
    Springer
    Virchows Archiv 413 (1988), S. 505-512 
    Details
    ISSN: 1432-2307
    Keywords: Neuroendocrine differentiation ; Immunohistochemistry ; Electron microscopy ; Small cell undifferentiated bladder carcinoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Small cell carcinoma with the histological appearance of pulmonary small cell carcinoma is a rare tumour in the urinary bladder. In previous case reports the neuroendocrine nature of small cell bladder carcinoma has been accepted, but on review the evidence for true neuroendocrine differentiation appears unsatisfactory. In this study the histological, immunohistochemical and ultrastructural characteristics of three cases of small cell carcinoma of the urinary bladder are described. Ultrastructurally, the cytoplasm of all three tumours contained neurosecretory-type granules and each of the tumours demonstrated positive immunoreaction for two or more neuroendocrine markers, from a panel including neuron-specific enolase, chromogranin A, Leu-7, bombesin and synaptophysin. Although the combination of ultrastructural and immunohistochemical examination obviously offers the strongest evidence in establishing neuroendocrine differentiation, it is argued that immunohistochemistry alone may also yield important information in demonstrating a neuroendocrine nature, provided that at least neuron-specific enolase and synaptophysin are included as markers. The clinical relevance of identifying neuroendocrine differentiation in small cell bladder carcinoma is suggested by the favourable response to combination chemotherapy in two of our cases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00750391
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  • 10
    Electronic Resource
    Electronic Resource
    Do folliculo-stellate adenomas of the pituitary gland exist or are they intrasellar meningiomas? (1988)
    Springer
    Acta neuropathologica 77 (1988), S. 219-223 
    Details
    ISSN: 1432-0533
    Keywords: Meningioma ; Folliculo-stellate cell ; Pituitary neoplasm ; Electron microscopy ; Immunochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A tumor arising in the pituitary fossa and having some of the histological and ultrastructural features of a recently described tumor, purportedly originating from the folliculo-stellate cells of the anterior pituitary, is presented. The results of our ultrastructural and immunohistochemical studies, however, favored a meningeal origin and suggested that the neoplasm was most likely a secretory meningioma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00687435
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  • 11
    Electronic Resource
    Electronic Resource
    Structural changes in the rat brain after carotid infusions of hyperosmolar solutions (1988)
    Springer
    Acta neuropathologica 77 (1988), S. 5-13 
    Details
    ISSN: 1432-0533
    Keywords: Blood-brain barrier ; Hyperosmolar solutions ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Infusion of hypertonic solutions into the carotid artery is one method by which the blood-brain barrier (BBB) can be opened transiently in experimental animals. This technique has also been tried in clinical situations in which an enhanced uptake of intravenously injected chemotherapeutic drugs into the brain is desired. We have previously found that infusion of hypertonic mannitol or urea into the carotid artery of the rat, leading to a BBB opening, is associated with light microscopic signs of cellular damage in the brain parenchyma. An electron microscopic study has now been made to obtain more detailed information about the events taking place in the rat brain 1 to 72 h after an intracarotid infusion of hyperosmolar solution of mannitol. Toluidine blue-stained semithin epon sections were also available for high-resolution light microscopy of brain samples from urea-infused animals. Intravenously injected Evan's blue dye was used to confirm that BBB opening had occurred as a consequence of the carotid infusions. The infused hemispheres had numerous structural changes. The dominating light microscopic alteration was the presence of multifocal lesions in the gray or the white matter with closely packed microvacuoles causing status spongiosus. Ultrastructurally the microvacuoles corresponded to very pronounced watery swelling of astrocytic processes and to a minor degree to expansion of dendrites and axons. There was also a light or moderate perivascular astrocytic swelling. In the “spongy” lesions as well as occasionally in non-vacuolated parts of the cerebral cortex, there were collapsed electron-dense neurons with pronounced mitochondrial alterations such as severe swelling associated with rupture of christae. Rats with a survival period of 24 h or 72 h showed several disintegrating neurons and accumulation of macrophages. This study shows that carotid infusion of hypertonic mannitol in the rat may cause pronounced neuronal changes as well as multifocal astrocytic swelling. The severity of the nerve cell changes and the presence of macrophages indicate that some of the alterations are irreversible and thus, such a procedure may not be as safe as previously suggested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00688236
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  • 12
    Electronic Resource
    Electronic Resource
    Nerve cell injury in the brain of stroke-prone spontaneously hypertensive rats (1988)
    Springer
    Acta neuropathologica 76 (1988), S. 227-237 
    Details
    ISSN: 1432-0533
    Keywords: Stroke-prone spontaneously hypertensive rats ; Blood-brain barrier ; Brain edema ; Nerve cell injury ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The brain lesions in stroke-prone spontaneously hypertensive rats (SHRSP) are characterized by multifocal microvascular and spongy-cystic parenchymal alterations particularly in the gray matter. An essential feature of the lesions is the presence of edema with massive extravasation of plasma constituents as evidenced by specific gravity measurements, Evans blue technique and immunohistochemistry. The nerve cell injury occurring in the brain lesions in SHRSP is further characterized by light and electron microscopy in the present study. Two types of neuronal changes were seen within the blood-brain barrier (BBB) leakage sites. A small number of neurons with dark condensed nucleus and cytoplasm were found most often at the periphery of recent lesions. The majority of injured neurons were pale and showed intracellular edema confined to the dendrites and perikarya sparing axons and synapses. Their nuclei were weli preserved with finely dispersed chromatin. The swollen and watery cell processes of neurons and astrocytes gave a spongy appearance to the neuropil. The intracellular edema seemed to result in cytolysis. The results suggest that primary anoxiaischemia is not the major pathogenetic mechanism behind the nerve cell injury in severely hypertensive SHRSP, rather it is the massive BBB leakage and consequent brain edema that causes cytolytic destruction of neurons. Secondary focal ischemia as a consequence of occlusion in microvessels may, however, contribute to the nerve cell destruction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00687769
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  • 13
    Electronic Resource
    Electronic Resource
    The ultrastructural organization of the isthmic nucleus in Xenopus (1988)
    Springer
    Anatomy and embryology 177 (1988), S. 325-330 
    Details
    ISSN: 1432-0568
    Keywords: Isthmic nucleus ; Electron microscopy ; Tectal ablation ; Xenopus ; Morphometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The isthmic nucleus (IN) of the frog brain forms a linkage, relaying visual information from one tectum to the other. It receives afferent input from the tectum of the same side and projects bilaterally to both tecta. The ultrastructural features of the tecto-isthmic synaptic connections were studied in young postmetamorphic Xenopus frogs. Most synaptic profiles in the isthmic nucleus have spheroidal vesicles and an asymmetric zone of apposition. Frequently, synaptic glomeruli consisting of up to 8 terminal boutons surrounding a shaft dendrite were observed. The syanptic density in the rostral IN was slightly higher than in the middle or caudal portions. Partial deafferentation by transection of the tectoisthmic pathway or total deafferentation by removal of the tectum was followed by a widespread degeneration of terminals in the ipsilateral IN. In the former case, the density of synapses in the IN decreased initially by about 64%, and then increased by 30 days after operation to about 50% of the normal synaptic density. After tectal removal, all the terminal boutons in the isthmic neuropil degenerated by 3 days after operation. These studies, along with recent findings, indicate that most, if not all, of the afferent fibres to IN are of tectal origin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00315840
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  • 14
    Electronic Resource
    Electronic Resource
    Fine structural survey of Gudden's tegmental nuclei in the rat: cytology and axosomatic synapses (1988)
    Springer
    Anatomy and embryology 177 (1988), S. 485-493 
    Details
    ISSN: 1432-0568
    Keywords: Ventral tegmental nucleus of Gudden ; Dorsal tegmental nucleus of Gudden ; Quantitative morphometric study ; Synaptic organization ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The fine structure of neuronal somata and axosomatic synapses in each subnucleus of Gudden's tegmental nuclei was studied by use of electron microscopy. The pars principalis of the ventral tegmental nucleus of Gudden (TVP) is composed of oblong or triangular, medium sized neurons (11.8x22.6 μm, 211.4 μm2) containing many mitochondria, lysosomes, Golgi apparatus, and rough endoplasmic reticulum composing Nissl bodies. The light oval nucleus with a prominent nucleolus is centrally situated, and indentations of its nuclear envelope are recognized in all neurons. The neuron in the pars ventralis of the dorsal tegmental nucleus of Gudden (TDV) is similar to that in the TVP, but its average size is significantly smaller (10.0x18.8 μm, 151.4 μm2), and its organelles are also less well developed. The pars dorsalis of the dorsal tegmental nucleus of Gudden (TDD) is composed of spindle shaped, small neurons (6.9x16.2 μm, 85.1 μm2) characterized by their irregular shaped nucleus with its invaginated envelope. These neurons have a thin rim of cytoplasm, poorly developed organelles and no Nissl bodies. The average number of axosomatic terminals in a sectional plane is 9.9 in the TVP, 9.6 in the TDV and 2.6 in the TDD, and the bouton covering ratio is 24.3% in the TVP, 26.5% in the TDV and 7.4% in the TDD. The respective percentages of round, flat and pleomorphic type axosomatic terminals were estimated, and the flat type terminals were found to be dominant in the TVP, the pleomorphic type terminals in the TDV, and the round type terminals in the TDD.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00305136
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  • 15
    Electronic Resource
    Electronic Resource
    Quantitative electron microscopic observations on the non-neuronal cells and lipid droplets in the posterior funiculus of the kitten after dorsal rhizotomy (1988)
    Springer
    Anatomy and embryology 178 (1988), S. 95-105 
    Details
    ISSN: 1432-0568
    Keywords: Electron microscopy ; Glial cells ; Perivascular cells ; Lipid droplets ; Wallerian degeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Kittens were subjected to lumbosacral dorsal rhizotomies at the age of 6–8 days postnatally. After postoperative survival times of 1–25 days the number of non-neuronal cells and lipid droplets in each cell type in the posterior funiculus at L1 were counted at the ultrastructural level. Intact control animals were analyzed in the same way. The number of astrocytes and oligodendrocytes decreased with increasing postoperative survival time in the degenerating zone. This was also the case in the white matter of control animals with increasing age of sacrifice. However, in the degenerating zone of operated animals the decrease was more extensive for oligodendrocytes starting at 5 days after surgery, and possibly also for astrocytes at 25 days postoperatively. The number of microglial cells in the degenerating zone was markedly increased 2–10 days after surgery compared to the controls. The number of non-pericytic perivascular cells seemed to be somewhat increased from 9 days after surgery, while the number of pericytes remained unchanged during the experimental period. Lipid droplets in the degenerating white matter were mainly located in microglial cells and astrocytes and only to a small extent in nonpericytic perivascular cells. These findings suggest that lipid material produced during anterograde fiber degeneration in the immature white matter is mainly metabolized in glial cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02463643
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  • 16
    Electronic Resource
    Electronic Resource
    Ultrastructure of preimplantation rabbit embryos exposed to visible light and room temperature (1988)
    Springer
    Anatomy and embryology 178 (1988), S. 229-241 
    Details
    ISSN: 1432-0568
    Keywords: Room temperature ; Visible light ; Preimplantation embryos ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Early cleavage stage embryos (day 1 p.c.) and morulae (day 3 p.c.) of rabbits were exposed to visible (standard) lighting (1600 lx) and room (standard) temperature (23°C) during a 24 h in-vitro culture. Control embryos were cultured in darkness at 37°C. Development was assessed by light and electron microscopy as well as by the cytochemical demonstration of glycogen. In day 1 and day 3 embryos standard temperature induced swelling of the SER and Golgi complex vesicles. Major changes in day 1 embryos consisted of smallish microtubules-like crystalloids, and in day 3 embryos of unusually large SER vesicles. In both embryonic ages cleavage rate and development was more retarded by standard temperature than by standard lighting. Standard lighting, however, led to distinct signs of degeneration and cell death. The mode of cell damage seemed to be different in light exposed early cleavage stages and morulae: In day 1 embryos cytoplasmic degeneration was predominant while the majority of cells in day 3 embryos died by apoptosis. Despite clear indications of cell damage, cleavage rate was not notably impaired compared with non-exposed controls. Glycogen increased during development from cleavage stages to early blastocysts. The distribution was not changed either by exposure to standard temperature nor by standard lighting. The results demonstrate that day 1 embryos were clearly more susceptible to lighting whereas day 3 embryos were more affected by temperature. The mode of damage exerted by both the physical environmental factors was different. Reduction to standard temperature interfered mainly with the organization of the cytoskeleton and intracellular transport of organelles, while exposure to standard lighting led to cell degeneration and death.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00318226
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  • 17
    Electronic Resource
    Electronic Resource
    Heterogeneities of the islets in the rabbit pancreas and the problem of “paracrine” regulation of islet cells (1988)
    Springer
    Anatomy and embryology 178 (1988), S. 297-307 
    Details
    ISSN: 1432-0568
    Keywords: Rabbits ; Islands of Langerhans ; Electron microscopy ; Immunohistochemistry ; Regulation of islands
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In addition to “external” signals conveyed by the circulation or the nervous system, the pancreatic islets obviously are regulated also by “internal” (intra-islet) signals, e.g. by the islet hormones: insulin (B-), glucagon (A-), and somatostatin (D-) cells are able to affect the secretion of the heterologous cell types. It is, however, unclear whether this functional cooperation between islet cells occurs by an intercellular route (paracrinia sensu strictore), by intraislet “portal” vessels, or by the systemic circulation. These likely interactions are limited by islet anatomy. To identify the anatomical basis for the mutual functional relationships between the islet cells, islets of Langerhans in the rabbit pancreas were completely analyzed in immunostained serial semithin (0.5 μm) sections. The islets were found to be largely heterogenous. They were classified in three basic types: a) polycellular islets, composed of all established endocrine cells, and including two subtypes of islets, b) bicellular islets, containing only B- and A-cells or B- and D-cells, and c) monocellular islets, exclusively made up of B-cells. Concerning the modes of paracrine regulation of islet cells, the findings suggest primarely an endocrinous route of transport of the islet peptides to heterologous endocrine cells. The corresponding functional cooperation between islet cells probably is mediated rather by the systemic circulation than by intra-islet portal vessels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00698661
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  • 18
    Electronic Resource
    Electronic Resource
    Light and electron microscopic investigation of the rat placenta after cadmium administration during pregnancy (1988)
    Springer
    Anatomy and embryology 178 (1988), S. 345-351 
    Details
    ISSN: 1432-0568
    Keywords: Cadmium, Placenta (rat) ; Morphometry ; Light microscopy ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The morphology of the rat placenta was studied after exposure to cadmium chloride during pregnancy, using optimal fixation conditions. In contrast to previous observations, no differences were observed after cadmium administration in relative volume densities of trophoblastic tissue, maternal lacunae, fetal capillaries and connective tissue, nor in trophoblastic thickness or other morphometric features. At the ultrastructural level, the amount of glycogen in trophoblast layer II was elevated in cadmium exposed rats, but other electron microscopic features (amount and localization of lipid, degenerative vesicles, thickness and general appearance of the trophoblastic and endothelial layers and thickening or multiplication of the basal lamina) were not changed. Results obtained from the present experiments do not support the suggestion that cadmium is responsible for structural changes in the placentae of human smokers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00698665
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  • 19
    Electronic Resource
    Electronic Resource
    Quantitative assessment of taurine-like immunoreactivity in different cell types and processes in rat cerebellum: an electronmicroscopic study based on a postembedding immunogold labelling procedure (1988)
    Springer
    Anatomy and embryology 178 (1988), S. 407-421 
    Details
    ISSN: 1432-0568
    Keywords: Taurine ; Immunocytochemistry ; Quantification ; Electron microscopy ; Cerebellum ; Purkinje cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Ultrathin sections of plastic-embedded rat cerebella were incubated with an antiserum against conjugated taurine and subsequently treated with a secondary antibody coupled to colloidal gold. The density of gold particles in various cellular profiles was calculated with the assistance of a computer. In the cerebellar cortex the highest density was found in the somata, dendrites, and dendritic spines of the Purkinje cells, supporting parallel light-microscopical observations in postembedding stained semithin sections from the same tissue blocks. The remaining profiles could be divided into three groups according to their immunolabelling intensity, in descending order: 1) somata and processes of granule and Golgi cells; 2) somata and processes of stellate, basket, and glial cells, and 3) mossy fiber terminals. In a representative experiment, the structures in the first and second groups showed gold particle densities in the range of 19–25%, and 4–11%, respectively, of that in the Purkinje cell somata (values corrected for background) whereas the particle density in the mossy fiber terminals was not significantly above background level. In the cerebellar nuclei, taurine-like immunoreactivity was concentrated in terminals that typically established symmetric or intermediate type contacts with weakly labelled dendrites and cell bodies. These terminals, which shared the ultrastructural features of Purkinje cell terminals, showed an average gold particle density that was about 60% higher than that of the Purkinje somata. For specificity control, ultrathin sections containing a series of different amino acid conjugates were incubated in the same drops of sera as the tissue sections. The highly selective labelling of the taurine conjugate indicated that the distribution of gold particles in the tissue was not confounded by crossreactivity with GABA, glutamate or other common amino acids but adequately reflected the distribution of fixed taurine. For additional control of specificity, the taurine antiserum was applied to the soluble fraction of a rat brain extract separated by thin layer chromatography. In this system the taurine antiserum stained a single spot that comigrated with free taurine. The present results suggest that all cell types and processes in the rat cerebellum (with the exception of the mossy fiber terminals) contain taurine. However, the concentration of taurine appears to vary considerably among the different cell types and may also differ between different parts of the same neuron.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00306047
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  • 20
    Electronic Resource
    Electronic Resource
    Proliferation of rat intraspinal Schwann cells following tellurium intoxication (1988)
    Springer
    Acta neuropathologica 76 (1988), S. 624-627 
    Details
    ISSN: 1432-0533
    Keywords: X-Irradiation ; Intraspinal Schwann cell ; Myelin ; Autoradiography ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A stable population of intraspinal Schwann cells, which developed follwing early postnatal irradiation of the spinal cord, was challenged by the addition of tellurium (Te) to the diet beginning at 30 days of age. Schwann cells incorporating [3H]thymidine were identified by 1 μm autoradiographs and by conventional electron microscopy of adjacent thin sections. Autoradiographs of areas with Schwann cell myclination showed extensive labelling of cells in the Te-fed animals. In contrast, control animals which were not fed Te showed little evidence of labelled Schwann cells. These data indicate that Schwann cells in the intraspinal environment show a proliferative response to the presence of Te in the rat's diet, as do Schwann cells in their normal extraspinal milieu.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00689602
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  • 21
    Electronic Resource
    Electronic Resource
    Abnormal amianthoid collagen fibers in meningioma (1988)
    Springer
    Acta neuropathologica 76 (1988), S. 638-639 
    Details
    ISSN: 1432-0533
    Keywords: Meningioma ; Electron microscopy ; Collagen ; Amianthoid fibers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Electron microscopic examination of a spinal meningioma demonstrated broad zones with large amianthoid collagen fibers in the tumor. Normal native collagen fibrils were found in small scattered clumps particularly around the blood vessels in the tumor. Such abnormal large collagen fibrils have not been seen previously in meningiomas. The significance of the amianthoid fibers is unknown. The only other unusual feature of the tumor was that it had many pale-staining cells by light microscopy and was classified as a clear cell variant of meningioma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00689605
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  • 22
    Electronic Resource
    Electronic Resource
    Morphological study of peripheral nerve changes induced by chloroquine treatment (1988)
    Springer
    Acta neuropathologica 75 (1988), S. 253-260 
    Details
    ISSN: 1432-0533
    Keywords: Chloroquine ; Peripheral neuropathy ; Nerve biopsy ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Nerve biopsies were performed in four patients with suspected chloroquine induced neuromyopathy. Three of the patients were treated with high doses of chloroquine for connective tissue disease, while one patient was taking this drug as malaria prophylaxis. Morphological studies demonstrated the presence of segmental demyelination and remyelination in all cases. Cytoplasmic inclusions were observed in Schwann cells, in perineurial and endothelial cells, and in some interstitial cells. They were never observed within axons. Occasional curvilinear profiles were seen in perineurial and Schwann cells. Perineurial calcifications were observed in two cases. The results of this morphological study suggest that chloroquine neuropathy is essentially due primary involvement of Schwann cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00690533
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  • 23
    Electronic Resource
    Electronic Resource
    Human immunodeficiency virus (HIV)-related chronic relapsing inflammatory demyelinating polyneuropathy with multifocal unusual onion bulbs in sural nerve biopsy (1988)
    Springer
    Acta neuropathologica 75 (1988), S. 529-534 
    Details
    ISSN: 1432-0533
    Keywords: HIV-related relapsing polyneuropathy ; Intrathecal HIV antibodies ; Nerve biopsy ; Electron microscopy ; Schwann cell morphology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This is obviously the first report on a case with a spontaneous sensu strictu relapsing variant of human immunodeficiency virus (HIV)-related polyneuropathy. Its manifestation preceded LAS. Intrathecal HIV-antibodies developed between the most severe third and fourth episode. Analysis of sural nerve biopsy was consistent with a multifocally accentuated chronic inflammatory demyelination, characterized by unusual onion bulb-like Schwann cell formations with irregular voluminous layers, electron density, aggregation of filaments, multiple indented nuclei, and numerous enclosed collagen pockets. A direct or immune-mediated indirect specific influence on Schwann cell morphology by HIV might be discussed. Virus-like particles and ultrastructural markers of HIV were not detectable.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00687143
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  • 24
    Electronic Resource
    Electronic Resource
    A novel intradural extramedullary spinal cord tumor in young dogs (1988)
    Springer
    Acta neuropathologica 75 (1988), S. 402-410 
    Details
    ISSN: 1432-0533
    Keywords: Spinal cord tumor ; Dog ; Electron microscopy ; Immunocytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We have studied an unusual, spontaneous, intradural extramedullary spinal cord tumor in 12 dogs. Animals presented with paraparesis and ataxia early in life (11/12 ranged from 6 to 38 months of age) suggesting that these tumors may be congenital. Various breeds of dogs were represented with four cases in German Shepherds and three in retrievers; there was no sex predisposition. Post-mortem examinations revealed a single intradural mass consistently located between T10 and L2, which produced extensive compression of the spinal cord. Metastasis was never observed and significant pathological changes in other organs were lacking. Microscopic examination revealed solid sheets of ovoid to fusiform cells interspersed with areas of acinar and tubular differentiation. Some areas were rarified and focal squamous metaplasia was observed. Ultrastructural features included the presence of a continuous basal lamina, junctional complexes, microvilli and occasional cilia at the apices of acinar complexes. Immunocytochemical studies did not support a neurectodermal origin. At least 13 case reports of this entity have been previously published and have been designated ependymomas, medulloepitheliomas and neuroepitheliomas. A recent case was diagnosed as a nephroblastoma and we feel that this is an interesting and provocative diagnosis. These tumors could result from remnants of renal primordium which becomes trapped between the dura and the developing spinal cord. However, firm evidence of such a histogenesis is not yet at hand.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00687794
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  • 25
    Electronic Resource
    Electronic Resource
    Ultrastructural analysis of neurofibrillary tangles of Alzheimer's disease using computerized digital processing (1988)
    Springer
    Acta neuropathologica 75 (1988), S. 519-522 
    Details
    ISSN: 1432-0533
    Keywords: Alzheimer's disease ; Neurofibrillary tangle ; Paired helical filament (PHF) ; Electron microscopy ; Computerized digital processing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The ultrastructure of neurofibrillary tangles of Zlzheimer's disease was analyzed by computerized digital processing of electron micrographs. Processing of the electron micrographs consists of four steps: digitizing the electron micrograph, Fourier transformation, noise filtering and inverse Fourier transformation and Laplacian operation. In the present study, we have confirmed that neurofibrillary tangles are composed of a pair of helical filaments (PHF), which appear characteristically as an unbranched rigid structure. The periodicity of PHF is 78nm on the diffractogram. The dimensions of PHF obtained by our analysis, although basically similar to those described earlier by other investigators using conventional techniques, more precisely defines its structural conformation. We have also demonstrated that the spatial relationship of two filaments appears symmetrical after two-way tilting of the specimen about the axis of rotation. Our observations emphasize the importance of digital image processing as an effective tool for structural analytical research in biology and medicine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00687141
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  • 26
    Electronic Resource
    Electronic Resource
    Ultrastructural pathology of dermal axons and Schwann cells in lysosomal diseases (1988)
    Springer
    Acta neuropathologica 76 (1988), S. 489-495 
    Details
    ISSN: 1432-0533
    Keywords: Dermal nerves ; Electron microscopy ; Lysosomal diseases ; Terminal axons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Skin tissue specimens, obtained from 60 patients afflicted with a diverse range of lysosomal disorders revealed two groups of lesions within dermal axons, largely unmyelinated ones, particularly within axonal terminals: (1) non-specific mitochondria and dense bodies often enlarging the axonal terminal; and (2) disease-specific lysosomal residual bodies, the latter less frequent depending on the incidence and type of lysosomal disorders, i.e., largely only seen in GM2-gangliosidosis due to hexosaminidase A deficiency and mucolipidosis IV, while the spectrum of lysosomal residual bodies in Schwann cells appeared more variegated, especially due to the occurrence of vacuolar lysosomal residual bodies which were never seen within axons. The most frequent location of abnormal intraaxonal constituents in terminal axons indicates a functionally and morphologically impaired retrograde axonal transport but provides no further evidence as to whether the respective parent nerve cell body has also accumulated lysosomal residual bodies. When studying biopsied skin specimens for diagnosis, axonal terminals beneath the epidermis, about sweat glands, and among smooth muscle cells, ought to be incorporated into a comprehensive electron microscopic examination.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00686388
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  • 27
    Electronic Resource
    Electronic Resource
    The postsynaptic targets of substance P-immunoreactive terminals in the rat neostriatum with particular reference to identified spiny striatonigral neurons (1988)
    Springer
    Experimental brain research 70 (1988), S. 361-377 
    Details
    ISSN: 1432-1106
    Keywords: Neostriatum ; Substance P ; Immunocytochemistry ; Golgi-impregnation ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Substance P-immunoreactive boutons were examined in the electron microscope in sections of the rat neostriatum that contained retrogradely labelled striatonigral neurons and/or Golgi-impregnated medium-size densely spiny neurons. The postsynaptic targets of the immunoreactive boutons were characterized on the basis of ultrastructural features, their projection to the substantia nigra and/or their somato-dendritic morphology. Substance P-immunoreactive axonal boutons formed symmetrical synaptic specializations. Of a total of 233 randomly identified synaptic boutons 72.5% made contact with dendritic shafts, 15% with dendritic spines and 10.7% with perikarya. The ultrastructural characteristics of some of the postsynaptic neuronal perikarya were consistent with their identification as striatal interneurons. Similarly, the observation of some of the substance P-containing terminals in contact with spines, spine-bearing dendritic shafts and perikarya with the ultrastructural characteristics of medium-size densely spiny neurons suggested that one of the targets of substance P-positive terminals are striatal projection neurons. Direct evidence for this was obtained in sections from rats that had received injections of horseradish peroxidase conjugated with wheatgerm agglutinin in the substantia nigra. The perikarya of retrogradely labeled striatonigral neurons were found to receive symmetrical synaptic input from substance P-positive boutons. Ultrastructural analysis of Golgi-impregnated medium-size densely spiny neurons, some of which were also retrogradely labeled from the substantia nigra, demonstrated directly that this class of neuron was postsynaptic to the substance P-immunoreactive boutons. The combination of Golgi-impregnation with substance P-immunocytochemistry made it possible to study the pattern or topography of the substance P-positive input to medium size densely spiny neurons. The substance P-containing boutons made contact predominantly with perikarya and dendritic shafts. This pattern of input is markedly different from that of other identified inputs to medium-size densely spiny neurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00248361
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  • 28
    Electronic Resource
    Electronic Resource
    The cholinergic innervation of the rat substantia nigra: a light and electron microscopic immunohistochemical study (1988)
    Springer
    Experimental brain research 72 (1988), S. 178-184 
    Details
    ISSN: 1432-1106
    Keywords: Choline acetyltransferase ; Immunocytochemistry ; Substantia nigra ; Pedunculopontine tegmental nucleus ; Acetylcholine ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Putative cholinergic axons and synaptic endings were demonstrated in the substantia nigra (SN) of the rat by light and electron microscopy on the basis of the localization of choline acetyltransferase (ChAT) immunoreactivity. The distribution of ChAT immunoreactivity in the SN as demonstrated by light microscopy revealed a modest network of ChAT-immunoreactive beaded axons in the SNc, in comparison to a relatively sparse distribution in the SNr. These axonal profiles were most dense in the middle of the rostral-caudal extent of the SNc and appeared to be concentrated in the middle third of the medial-lateral extent. By electron microscopy, unmyelinated, small diameter (0.25 μm) ChAT-immuno-reactive axons were observed interspersed among numerous other non-immunoreactive axons in the SNc. ChAT-immunoreactive synaptic endings were observed in juxtaposition to small caliber (0.5 μm) non-immunoreactive dendrites, and contained numerous spheroidal synaptic vesicles and occasional mitochondria. Synaptic contact zones were characterized by an accumulation of synaptic vesicles along the presynaptic membrane, and a prominent postsynaptic densification producing an asymmetrical pre-/postsynaptic membrane profile typical of excitatory synapses. These findings provide direct evidence for a cholinergic innervation of the SN, and suggest that this input may have an excitatory effect on neuronal elements in the SNc.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00248513
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  • 29
    Electronic Resource
    Electronic Resource
    Changes in microglial cell numbers in the spinal cord dorsal horn following brachial plexus transection in the adult rat (1988)
    Springer
    Experimental brain research 73 (1988), S. 61-68 
    Details
    ISSN: 1432-1106
    Keywords: Microglia ; Dorsal horn ; Nerve lesion ; Light microscopy ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effect of peripheral nerve transection on the size of the microglial cell population in cytoarchitecturally distinct regions of the spinal cord dorsal horn of rats was evaluated at selected intervals 2 through 35 days after unilateral brachial plexotomy. The identification of cells was verified by electron microscopic examination of a representative random sample of cells included in the counts. Microglial cell numbers were increased in laminae I, II as well as the arbitrarily defined deeper laminae 3.5 days after surgery. Although microglial cell numbers in laminae I were within normal range 35 days after axotomy, those of the more ventrally located laminae remained significantly greater than control values for the duration of the experimental period. These findings demonstrate that: 1) microglial cell proliferation in the dorsal horn is an early event in the central changes that are attendant to peripheral nerve injury 2) the time course of the response varies in cytoarchitecturally different regions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00279661
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  • 30
    Electronic Resource
    Electronic Resource
    Hypertension and nephrotoxic lesions in rats 1 year after prenatal exposure to gentamicin (1988)
    Springer
    Archives of toxicology 62 (1988), S. 274-284 
    Details
    ISSN: 1432-0738
    Keywords: Gentamicin ; Postnatal development ; Blood pressure ; Embryotoxicity ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Using the aminoglycoside antibiotic gentamicin persistant functional and morphological changes were induced prenatally in the rat kidney. After 6 days of s.c. treatment (110 mg gentamicin/kg body wt) from day 10 to 15 of pregnancy complete resorption was noticed in 8 of the 14 treated animals. Fifty-three newborn were obtained from six dams. One year later only 26 rats (16 male, 10 female) were still alive. The systolic arterial pressure of the female offspring was significantly increased (139±15 mm Hg versus 112±9 mmHg) compared with controls. No statistically significant effect could be noticed in the male offspring (128±5 mm Hg versus 118±21 mm Hg). Corresponding results were obtained from analysis of urea plasma concentrations. Another cohort of pregnant rats received daily injections of gentamicin from day 15 to 20 of pregnancy (110 mg/kg body wt s.c.). In this group 59 newborn from a total of 109 died within the first 5 days after birth. Six litters were observed postnatally. One year after birth the following blood pressure values were determined: 122±4 mm Hg (male) and 132±17 mm Hg (female). Urea plasma concentrations were significantly higher in female, but not in male, offspring. Light and electron microscopic inspection revealed pathological changes in the kidneys of the female offspring only. The degree of maternal kidney damage — which shows considerable variations — was monitored during the treatment period. For this purpose the plasma gentamicin and urea concentrations were measured on 3 days of treatment in all of the pregnant animals. The postnatal data (mortality, blood pressure, and urea plasma concentrations) show a correlation to the degree of maternal kidney impairment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00332487
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  • 31
    Electronic Resource
    Electronic Resource
    Adult-onset rod disease with abundant intranuclear rods (1988)
    Springer
    Journal of neurology 235 (1988), S. 343-347 
    Details
    ISSN: 1432-1459
    Keywords: Adult-onset rod disease ; Nemaline myopathy ; α-Actinin ; Immunohistochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The third case of adult-onset rod disease (nemaline myopathy) with abundant myofibrillar as well as intranuclear rods is described. The 61-year-old woman suffered from progressive weakness of proximal extremities and of the neck, mimicking polymyositis. Muscle biopsy revealed a striking myopathic pattern, with intranuclear rods occurring in 31% of the fibres. On light and electron microscopy and by immunohistochemical study, the rods differed from myofibrillar rods. The absence of α-actinin in intranuclear rods suggests an enhanced readiness of actin filaments to bind to diverse proteins, instead of overproduction of α-actinin as the pathogenetic basis of the rod formation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00314229
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  • 32
    Electronic Resource
    Electronic Resource
    Immunocytochemical localization of two key enzymes of the 2-hydroxyglutarate pathway of glutamate fermentation in Acidaminococcus fermentans (1988)
    Springer
    Archives of microbiology 150 (1988), S. 504-508 
    Details
    ISSN: 1432-072X
    Keywords: Acidaminococcus fermentans ; Glutamate fermentation ; Electron microscopy ; Immunocytochemistry ; Post-embedding labelling ; Antibody-gold complexes ; Protein A-gold complexes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have investigated the in situ location of glutaconyl-CoA decarboxylase and 2-htdroxyglutaryl-CoA dehydratase in Acidaminococcus fermentans using the antibody-gold and protein A-gold techniques carried out as a post-embedding immunoelectron microscopic procedure. Polyclonal antisera were raised in rabbits against homogeneous fractions of the enzymes. Anaerobically grown cells of A. fermentans of the late exponential growth phase were fixed with 0.2% glutaraldehyde and 0.3% formaldehyde (final concentrations) in the growth medium. Dehydration of the cells was achieved with methanol. The cells were embedded in the low temperature embedding resin Lowicryl K4M. The markers indicative for antigenic sites of the two enzymes unequivocally demonstrate that the sodium pump glutaconyl-CoA decarboxylase is located at the cell periphery being a membrane-bound enzyme as expected whereas 2-hydroxyglutaryl-CoA dehydratase is a soluble cytoplasmic enzyme.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00422295
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  • 33
    Electronic Resource
    Electronic Resource
    The production and utilization of intermediary elemental sulfur during the oxidation of reduced sulfur compounds by Thiobacillus ferrooxidans (1988)
    Springer
    Archives of microbiology 150 (1988), S. 574-579 
    Details
    ISSN: 1432-072X
    Keywords: Thiobacillus ferrooxidans ; Sulfur production ; Sulfur oxidation ; Inhibitors ; Uncouplers ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The intermediary production of elemental sulfur during the microbial oxidation of reduced sulfur compounds has frequently been reported. Thiobacillus ferrooxidans, an acidophilic chemolithoautotroph, was found to produce an insoluble sulfur compound, primarily elemental sulfur, during the oxidation of thiosulfate, trithionate, tetrathionate and sulfide. This was confirmed by light and electron microscopy. Sulfur was produced from sulfide by an oxidative step, while the production from tetrathionate was initiated by a hydrolytic step, probably followed by a series of chemical reactions. The oxidation of intermediary sulfur was severely inhibited by sulfhydryl-binding reagents such as N-ethylmaleimide, by the addition of uncouplers or after freezing and thawing of the cells, which probably damaged the cell membrane. The mechanisms behind these inhibitions have not yet been clarified. Finally, it was observed that elemental sulfur oxidation by whole cells depended on the medium composition. The absence of sulfate or selenate reduced the sulfur oxidation rate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00408252
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  • 34
    Electronic Resource
    Electronic Resource
    Structure of the mitochondrial genome of Beta vulgaris L. (1988)
    Springer
    Theoretical and applied genetics 76 (1988), S. 753-759 
    Details
    ISSN: 1432-2242
    Keywords: Plant mitochondrial genome ; Minicircle DNA ; Electron microscopy ; Beta vulgaris L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The structure of mitochondrial DNA (mt-DNA) from sugarbeet (Beta vulgaris L.) has been studied by biochemical methods and electron microscopy. It was found to be complex multipartite consisting of two main classes of molecules: high molecules weight (HMW) mtDNA and low molecular weight (LMW) mtDNA. The HMW mtDNA consists of rosette-like structures and globules resembling chromomeres (150–200nm). A typical rosette has a protein core and radially stemming closed DNA loops (from 0.6-1.5 μm). The number of loops in a rosette varies from 16–30. The bulk of HMW mtDNAs are represented by interconnected rosettes (total contour length about 130–160 μm, 403–496 kbp). Such large circular DNAs may be evidence of the master chromosome arrangement of the sugarbeet genome. Globules and rosettes are interconnected by thick and thin DNA fibrils, along which nucleosome- and nucleomere-like structures are distributed. The LWM mtDNA is composed of two groups of supercoiled circular molecules, 0,2–1.5 μm and 0.02–0.05 μm in size. Electrophoretic analysis demonstrated that LWM mtDNA is represented by minicircle plasmid-like DNA molecules of 1.3, 1.4 and 1.6 kbp.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00303522
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  • 35
    Electronic Resource
    Electronic Resource
    Distribution of mitochondrial plasmid-like DNA in cultivated rice (Oryza sativa L.) and its relationship with varietal groups (1988)
    Springer
    Theoretical and applied genetics 76 (1988), S. 809-814 
    Details
    ISSN: 1432-2242
    Keywords: Electron microscopy ; Genetic variation ; Mitochondrial DNA ; Oryza sativa L. ; Plasmid-like DNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Mitochondrial (mt) plasmid-like DNA was found in most of more than 100 rice cultivars (Oryza sativa L.) by the use of 0.7% agarose gel electrophoresis (AGE). The DNA varied in molecular weight and number. By electron microscopy, small circular DNAs of different sizes could be detected in addition to the DNAs of high molecular weight, even in cultivars in which mt plasmid-like DNA was not detected by AGE. The detection of the mt plasmid-like DNAs by AGE did not depend on their presence or absence, but on their high stoichiometry. The relationship between cytoplasms with mt plasmid-like DNAs and varietal (for example, Indica rice) groups was close. The geographical distribution of cytoplasms is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00273665
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  • 36
    Electronic Resource
    Electronic Resource
    Localization of 28 kDa calbindin in human odontoblasts (1988)
    Springer
    Cell & tissue research 254 (1988), S. 341-346 
    Details
    ISSN: 1432-0878
    Keywords: Odontoblast ; Calbindin ; Immunohistochemistry ; Electron microscopy ; Teeth ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The presence of 28 kDa calbindin in human odontoblasts was studied by use of specific antibodies raised against chick duodenal 28 kDa calbindin, in immunofluorescence, immuno-peroxidase, and electron-microscopic labelling experiments. The calbindin-like protein was detected mainly in the cytoplasm of odontoblast cell bodies, in their processes and occasionally in their nuclei. Correspondingly, at the ultrastructural level, immunoreactive material was associated with the cytosol, microfilaments and cilia. These findings suggest that human odontoblasts express a 28 kDa vitamin D-dependent calcium-binding protein, unlike those of rats and mice in which ameloblasts are the only cells immunoreactive for the protein.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00225806
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  • 37
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    Electronic Resource
    Development of follicular dendritic cells in lymph nodes of B-cell-depleted mice (1988)
    Springer
    Cell & tissue research 254 (1988), S. 449-454 
    Details
    ISSN: 1432-0878
    Keywords: Follicular dendritic cells ; Lymph nodes ; Electron microscopy ; Nude mice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary We have studied follicular dendritic cells (FDC) in lymph nodes of normal and thymus dysgeneic nude mice depleted of B-cells by chronic treatment with anti-IgM antibodies. We found that B cell depletion was accompanied by the absence of mature FDC as defined morphologically at the ultrastructural level. Only precursor FDC (p-FDC) could be demonstrated. Upon release of B-cell suppression, the repopulation of lymph nodes with B-cells was associated with the reappearance of fully differentiated FDC in primary follicles of nude mice and in secondary follicles of T-cell competent mice. We conclude that mature B-cells and/or B-cell products are required for the development of mature follicular dendritic cells in the mouse lymph node.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00225818
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  • 38
    Electronic Resource
    Electronic Resource
    Orthogonal arrays of particles in non-pigmented cells of rat ciliary epithelium: Relation to distribution of filipin- and digitonin-induced alterations of the basolateral membrane (1988)
    Springer
    Cell & tissue research 252 (1988), S. 165-173 
    Details
    ISSN: 1432-0878
    Keywords: Ciliary epithelium ; Orthogonal arrays of particles ; Filipin ; Freeze-fracture ; Electron microscopy ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary It has been suggested that orthogonal arrays of particles may increase the rigidity of plasma membrane, as does cholesterol. Therefore, using freeze-fractured non- pigmented ciliary epithelium, the distribution of such arrays was compared to the distribution of membrane deformations induced by the sterol-probes filipin and digitonin in different domains of the basolateral plasma membrane. The distribution of orthogonal arrays of particles was homogeneous between different regions of the basolateral membrane of the non-pigmented ciliary epithelium, while the number of filipin-induced alterations was nearly 4 times higher in the membrane domains not in contact with the basal lamina than in domains in contact with it. Contrary to the homogeneous distribution of arrays, digitonin-induced deformations also differed markedly in these two basolateral membrane domains. Considering that a marked positive response to sterol probes implies a high sterol content, we conclude that orthogonal arrays of particles can occur in plasma membrane regions well-provided with cholesterol and not in direct contact with the basal lamina. Other possible roles of these arrays are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00213838
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  • 39
    Electronic Resource
    Electronic Resource
    Ultrastructural localization of immunolabeled substance P and methionine-enkephalin-octapeptide in the surface layer of the dorsal horn of rat spinal cord (1988)
    Springer
    Cell & tissue research 253 (1988), S. 55-60 
    Details
    ISSN: 1432-0878
    Keywords: Substance P ; Enkephalin ; Spinal dorsal horn ; Immunocytochemistry ; Electron microscopy ; Rat (Sprague-Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A preembedding dual immunolabeling technique and electron microscopy were utilized to demonstrate the localization of immunoreactive substance P and methionine-enkephalin-octapeptide (Enk-8) in ultrathin sections of the surface layer (laminae I and II) of rat spinal dorsal horn. The immunoreaction of Enk-8 was visualized as goldtoned silver particles and that of substance P as diaminobenzidine reaction products. Axonal terminals with immunoreactive substance P, and also unlabeled axonal terminals, formed synaptic junctions with the perikarya and dendritic processes of Enk-8-containing neurons. Dendritic profiles immunolabeled for substance P were synaptically linked with unlabeled axons but not with Enk-8-positive ones. Furthermore, it was found that Enk-8 axons and substance P axons terminated synaptically in juxtaposition to one another on the same immunonegative dendrites. Among the Enk-8-containing neurons axonal profiles also appeared to be synaptically associated with immunoreactive Enk-8 dendritic processes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00221739
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  • 40
    Electronic Resource
    Electronic Resource
    Light- and electron-microscopic immunocytochemistry of peptidergic neurons innervating thoracico-abdominal neurohaemal areas in the blowfly (1988)
    Springer
    Cell & tissue research 253 (1988), S. 583-595 
    Details
    ISSN: 1432-0878
    Keywords: Bioactive peptides ; Coexistence of peptides ; Immunocytochemistry ; Electron microscopy ; Insect nervous system ; Calliphora erythrocephala, C. vomitoria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Ventral thoracic neurosecretory cells (VTNCs) of the blowflies, Calliphora erythrocephala and C. vomitoria, innervating thoracic neuropil and the dorsal neural sheath of the thoracico-abdominal ganglion have been shown to be immunoreactive to a variety of mammalian peptide antisera. In the neural sheath the VTNC terminals form an extensive neurohaemal network that is especially dense over the abdominal ganglia. The same areas are invaded by separate, ut overlapping serotonin-immunoreactive (5-HT-IR) projections derived from neuronal cell bodies in the suboesophageal ganglion. Immunocytochemical studies with different antisera, applied to adjacent sections at the lightmicroscopic level, combined with extensive cross-absorption tests, suggest that the perikarya of the VTNCs contain co-localized peptides related to gastrin/cholecystokinin (CCK), bovine pancreatic polypeptide (PP), Met- and Leuenkephalin and Met-enk-Arg6-Phe7 (Met-enk-RF). Electron-microscopic immunogold-labeling shows that some of the terminals in the dorsal sheath react with several of the individual peptide antisera, whilst others with similar cytology are non-immunoreactive. In the same region, separate terminals with different cytological characteristics contain 5-HT-IR. Both 5-HT-IR and peptidergic terminals are localized outside the cellular perineurium beneath the acellular permeable sheath adjacent to the haemocoel. Hence, we propose that various bioactive substances may be released from thoracic neurosecretory neurons into the circulating haemolymph to act on peripheral targets. The same neurons may also interact by synaptic or modulatory action in the CNS in different neuropil regions of the thoracic ganglion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00219749
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  • 41
    Electronic Resource
    Electronic Resource
    The efferent innervation of the genital chamber by an identified serotonergic neuron in the female cricket Acheta domestica (1988)
    Springer
    Cell & tissue research 252 (1988), S. 449-457 
    Details
    ISSN: 1432-0878
    Keywords: Serotonin (5-HT) ; Genital chamber ; Immuno-cytochemistry ; Electron microscopy ; Cricket, Acheta domestica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The serotonergic innervation of the genital chamber of the female cricket, Acheta domestica, has been investigated applying anti-serotonin (5-HT) immunocyto-chemistry at both light- and electron-microscopic levels as well as using conventional electron microscopy. Whole mount and pre-embedding chopper techniques of immuno-cytochemistry reveal a dense 5-HT-immunoreactive network of varicose fibers in the musculature of the genital chamber. All of these immunoreactive fibers originate from the efferent serotonergic neuron projecting through the nerve 8v to the genital chamber (Hustert and Topel 1986; Elekes et al. 1987). At the electron-microscopic level, 5-HT-immunoreactive nerve terminals, which contain small (50–60 nm) and large (∼ 100 nm) agranular vesicles as well as granular vesicles (∼100nm), contact the muscle fibers or the sarcoplasmic processes without establishing specialized neuromuscular connections. In addition to the 5-HT-immunoreactive axons, two types of immunonegative axons can also be found in the musculature. By use of conventional electron microscopy, three ultrastructurally distinct types of axon processes can be observed, one of which resembles 5-HT-immunoreactive axons. While the majority of the varicosities do not synapse on the muscle fibers, terminals containing small (50–60 nm) agranular vesicles occasionally form specialized neuromuscular contacts. It is suggested that the 5-HTergic innervation plays a non-synaptic modulatory role in the regulation circular musculature in the genital chamber of the cricket, while the musculature as a whole may be influenced by both synaptic and modulatory mechanisms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00214388
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  • 42
    Electronic Resource
    Electronic Resource
    Atrial-specific granules in the hearts of normal and water-deprived rats (1988)
    Springer
    Cell & tissue research 253 (1988), S. 547-552 
    Details
    ISSN: 1432-0878
    Keywords: Atrial-specific granule ; Atrial natriuretic polypeptide ; Water deprivation ; Immunohistochemistry ; Electron microscopy ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The morphology of atrial-specific granules, which contain atrial natriuretic polypeptide (ANP), was studied in the cardiac tissue of untreated controls and water-deprived rats by means of conventional and immunoelectron microscopy. Immature secretory vesicles or granules appeared to become buded off from the Golgi cisternae and then fused to form specific A-granules. An electron-dense plate with a fuzzy coat was frequently found on the limiting membrane at the end of such fusion. Pale specific B-granules, which were less electron-dense, larger, and more granular than A-granules, were found in small numbers in the left atrial cardiocytes, but rarely in the right ones. Very pale granules with a less granular matrix, considered to be B-type granules which had lost their electron-density, and which had less immunoreactivity for ANP, were numerous in the cardiac tissue after water deprivation. This morphological change, which is interpreted as an indication of granule degradation, was in agreement with the noted increase of natriuretic activity in the atrial tissue of water-deprived specimens.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00219745
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  • 43
    Electronic Resource
    Electronic Resource
    Epidermal growth factor (EGF)-induced morphological changes in the basement membrane of chick embryonic skin (1988)
    Springer
    Cell & tissue research 254 (1988), S. 481-485 
    Details
    ISSN: 1432-0878
    Keywords: Embryonic skin ; Epidermal growth factor ; Basement membrane ; Electron microscopy ; Chick
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effect of epidermal growth factor (EGF) on the basement membrane structure of chick embryonic skin cultured in a chemically defined medium (BGJb) containing 20 mM hydrocortisone, and EGF at 10, 50, or 100 ng/ml supplemented with 5% delipidized fetal calf serum, was examined by electron microscopy. During development of the epidermis in vitro, EGF (100 ng/ml) caused striking changes to occur in the basement membrane structure and in the keratinization process. The basement membrane frequently became discontinuous with many gaps apparent in section, and occasionally became folded following detachment from the basal surface of the epidermis and protruded into the underlying dermis. In the basal and intermediate cells of EGF-treated epidermis, tonofilament bundles were decreased in number, while desmosomes and hemidesmosomes revealed no significant changes in morphology.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00226497
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  • 44
    Electronic Resource
    Electronic Resource
    Unifying principles in intermediate filament (IF) structure and assembly (1988)
    Springer
    Protoplasma 145 (1988), S. 73-81 
    Details
    ISSN: 1615-6102
    Keywords: Intermediate filament structure ; Intermediate filament assembly ; Desmin ; Keratins ; Neurofilaments ; Nuclear lamins ; Cytoskeleton ; Electron microscopy ; Polymerization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01349341
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  • 45
    Electronic Resource
    Electronic Resource
    Evaluation of 111In labelled white blood cells by in vitro functional tests and electron microscopy (1988)
    Springer
    European journal of nuclear medicine 14 (1988), S. 159-164 
    Details
    ISSN: 1619-7089
    Keywords: 111In-white blood cells ; Chemotaxis ; Phagocytosis ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We have studied the influence of granulocyte labelling with commercially available 111In-oxine, tropolone (trop) or home made 111In-Mercapto pyridine (Merc) prepared by the method of Thakur (1985) on the cell structure by electron microscopy and on the cell function by enzymatic tests, random migration, chemotaxis, phagocytosis and bactericidal activity. The granulocytes were labelled with 400 μCi 111In-oxine in saline or 111In-trop or Merc in plasma. The effect of the chelating agents with and without addition of the tracer was studied (n=4) with varying concentrations: 5–10 μg/ml oxine, 10–160 μg/ml trop and 1–4 μg/ml Merc. Chemotaxis and random migration were not affected by 111In-trop and clearly supressed by 111In-oxine and Merc; the other tests were normal. The cell structure was disturbed by Merc. The labelling efficiency was excellent with oxine (90%), acceptable with trop (30%–80%) and poor with Merc (10%–25%). Without 111In, chemotaxis and random migration were normal up to a concentration of 80 μg/ml trop, 8.5 μg/ml oxine and 1 μg/ml Merc. With addition of 111In, chemotaxis and random migration were unaffected up to 80 gmg/ml by trop and markedly supressed by Merc and oxine. It is concluded that labelling with 111In-trop assures intact cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00293542
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  • 46
    Electronic Resource
    Electronic Resource
    The barrier-like role of activated connective tissue against the spread of supraglottic laryngeal carcinoma (1988)
    Springer
    European archives of oto-rhino-laryngology and head & neck 245 (1988), S. 151-154 
    Details
    ISSN: 1434-4726
    Keywords: Supraglottic carcinoma ; Light microscopy ; Electron microscopy ; Activated connective tissue barrier
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Light microscopic investigations of whole organ serial sections of 15 laryngectomy specimens with supraglottic carcinomas and comparative electron microscopic studies of the upper and lower poles of the tumors were carried out. The ultrastructure of different poles of the same supraglottic tumors was investigated and showed a more progressive fibrillogenesis with an activation of the connective tissue elements of the border on the lower pole of the malignancy. A significant role is attributed to the barrierforming feature of activated connective tissue with respect to the inhibition of the extension of tumor into the glottic region.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00464017
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  • 47
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    Electronic Resource
    Ultrastructural localization of Ca2+-binding sites in the spiral limbus, the stria vascularis and Reissner's membrane of the guinea pig (1988)
    Springer
    European archives of oto-rhino-laryngology and head & neck 245 (1988), S. 279-283 
    Details
    ISSN: 1434-4726
    Keywords: Calcium ; Reissner's membrane ; Stria vascularis ; Limbus ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Cations were precipitated with potassium antimonate in the cochlea of the guinea pig and electron microscopy was used to analyze the distribution of the formed reaction products. Differences in precipitate density between neighboring cells in Reissner's membrane, in the stria vascularis and in the limbus are described. Electron spectroscopic imaging was performed to obtain information about the spatial distribution of the precipitates and their elemental composition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00464630
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  • 48
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    Electronic Resource
    Experimental results from a plate-column wet scrubber with gas-atomized sprayPaper presented at the “Jahrestreffen der Verfahrens-Ingenieure”, Freiburg, September 30 to October 2, 1987. (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 73-79 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A pilot wet scrubber was examined experimentally. It is constructed like a plate column. Its plates are designed to set the gas into a whirling motion with tangential velocities of up to 25 m/s and to ensure a uniform distribution of the liquid throughout the gas flow. Particles suspended in the waste gas are collected by gas-atomized droplets to yield cut diameters between one and two microns. Energy consumption is lower than in the case of other scrubbers. The scrubbing mechanisms are analyzed by examining the measured pressure drops. Finally, methods of determining the collection efficiency are discussed and an empirical approach to its calculation is presented.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110111
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    Electronic Resource
    Relationship between residence time, fluid dynamics and efficiency in countercurrent flow equipmentPaper presented at AIChE Annual Meeting 1986, Miami Beach, Florida, USA (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 139-148 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The suitability of any item of equipment for a given thermal separation process cannot always be judged solely in the light of efficient and loading range data. In vacuum rectification, involving a large number of theoretical stages, the vapour pressure drop per transfer unit exerts a considerable effect on the energy consumption and thus largely governs the choice of column fittings. Furthermore, the pressure drop per transfer unit determines the temperature at the bottom of a rectification column and, hence, the suitability of the equipment for the separation of heat-sensitive products. It is also an important criterion for compressor requirements in absorption processes. Another factor of considerable importance in separating heat-sensitive mixtures by distillation is the time during which the product, particularly the liquid phase, is exposed to a given temperature in the column. Therefore, a standardized liquid residence time has been adopted to evaluate the systems in their entirely. This residence time depends on the hydrodynamic conditions in the column and is thus closely related to pressure drop and efficiency. Further important factors, which may decide the selection of column internals, are the specific volume and mass of the column. Based on theoretical considerations, a flow model is derived for describing the main loading range of countercurrent packed columns; the relationships between the above mentioned parameters are presented.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110119
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  • 50
    Electronic Resource
    Electronic Resource
    Absorption of SO2 by aqueous NaOH solutions in the presence of a surfactant (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 156-162 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A report is presented on the influence of liquid flow rate, NaOH concentration, column length and presence of 5 × 10-3 wt-% of the surfactant SLS on the rate of absorption of pure SO2 by aqueous NaOH solution in a sphere-and-cylinder column. The presence of sodium lauryl sulphate (SLS) prevented axial turbulence which increased mass transfer in longer columns and was almost independent of the flow rate. The enhancement factor due to the reaction between SO2 and NaOH with respect to the process of physical absorption was analyzed for the systems with excess OH- in the outflow. The results obtained in the presence of a surfactant are satisfactorily explained by film theory with a single reaction plane model. Those obtained in the absence of surfactant are best described by a two-plane model using renewal theory.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110121
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    Measurement of temperature fields in mixing vessels using optical topographyPaper presented by W. Ostendorf at the “Jahrsterffen der Verfahrens- Ingenieure”, Freiburg, September 30 to October 2, 1987. (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 148-155 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Experimental investigation of stirring processes require the measurement of temperature changes and concentration profiles in all the zones of the mixing volume. The conversion of simultaneous chemical reactions during the mixing process depends on the local temperature and concentration. The time-dependent temperature and concentration fields can be recorded for the entire mixing volume with the use of optical tomography and correlated with time. This technique offers the possibility of continuous measurement of temperature and concentration changes during the mixing process throughout the measurement volume. In the described investigations, optical tomography is used to examine the transport and equalization processes during mixing in stirred vessels.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110120
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    Heat transfer between particle beds and submerged surfacesPaper presented by O. Molerus at the “Jahrestreffen der Verfahrens-Ingenierue”, Freiburg, September 30 to October 2, 1987. (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 126-138 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Theoretical modelling of heat transfer to particle beds comprises two sequential steps: transfer from the heating surface to contacting particles followed by transfer to the interior of the bed. Two different limiting case can be formulated for the second step: unmixed and homogeneously mixed bed. In the case, heat is transferred gradually via a repeated sequence of heat transfer in the gap between adjacent particles and conduction in the particulate material. In the second case, heat is transferred to the interior of the bed by mixing of particles which have previously attained the temperature of the heating surface. On the other hand, the mixing motion maintains a homogeneous lower temperature throughout the bed. Theory predicts a significant and easily measurable difference in the behaviour of heat transfer coefficients for the two regimes at long contact times t: unmixed beds ∝ \documentclass{article}\pagestyle{empty}\begin{document}$$ \sqrt t $$\end{document} and homogeneously mixed beds ∝ 1/t. For short times t, both regimes show the same behaviour, namely of t.From a theoretical standpoint, it makes sense to differentiate further between the behaviour patterns of unmixed beds: at long times t, instantaneous heat transfer coefficients are independent of heat transfer form the heating surface to adjacent particles. Comparison with experimental result from literature shows that the derived models, which are consistent, are suitable for describing the heat transfer from submerged surfaces to unmixed and mixed beds of particles.
    Additional Material: 24 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110118
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    The role of energy dissipation in contacting and mixing devicesPresented in memory of Professor Otto Nagel, at the “Jahrestreffen der Verfahrens-Ingenieure”, Freiburg, September 30 to October 2, 1987. (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 276-287 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The aim of the present paper is the discussion of the relevance of power dissipation as a criterion for the understanding and prediction of transfer and mixing efficiencies in contactors and chemical reactors. After reviewing the approach of Le Goff to the energetic efficiency of exchangers, based on the deviations from Chilton-Colburn analogy, the following processes are studied: mass transfer between a flowing fluid and a reactive solid surface, transfer to a fixed object in a stirred vessel, macro- and micromixing of miscible fluids, and mass transfer in fluid-fluid contractors (especially gas-liquid reactors). It is concluded from the various examples that a direct relationship between the dissipated power and intensity of transfer or mixing can be established only under the two following conditions: local values must be considered at the point where the actual transfer and mixing occur, and not average values over the whole device, and power dissipation must be coupled to transfer or mixing and appear physically as the driving force of the process.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110137
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    A new regenerable process for the recovery of SO2Dedicated to Professor Hanns Hofmann on the occasion of his 65th birthday (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 402-407 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Increasing demand for regenerable processes with SO2 recovery is to be expected. Advantages and limitations of the earlier developed citrate and adipate absorption/ steam stripping process are compared with those of the Wellman-Lord (sulphite) process. On the basis of comprehensive laboratory studies, a new process is proposed which supplements the citrate and adipate process. In this new process, the absorbent is a concentrated sodium phosphate buffer and the loaded buffer is regenerated by evaporation. The main buffer component is Na2HPO4, but NaH2PO4 is added in order to obtain a more complete stripping of SO2 during regeneration. The new process promises excellent absorption properties for SO2 with extremely low oxidation losses, regeneration with few incrustation problems and appreciable energy savings.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110152
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  • 55
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    Masthead (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988) 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110101
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  • 56
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    Axial pressure profile in circulating fluidized beds (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 11-17 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Design and operation of a circulating fluidized bed requires the knowledge of fluid mechanics. According to heat and mass transfer as well as chemical reactions, the effect of the set superficial gas velocity on the axial pressure profile is of particular interest. The axial pressure profile was measured for a variety of solids, as a function of the superficial gas velocity, in a cylindrical circulating fluidized bed with an inner diameter of 0.19 m and an overall height of 11.5 m. Depending on the solids content and superficial gas velocity, two or one sections can be observed in the plant where the pressure gradient is constant. A pressure profile with one pressure gradient exists only at high gas velocities, so long as the acceleration pressure drop immediately above the gas distributor is negligible. Comparison of measured pressure drops in circulating fluidized beds with those measured in vertical pneumatic conveying led to a state diagram for vertical gas-solid flows. The operation behaviour of different types of circulating fluidized bed plants can be explained with the aid of this diagram.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110103
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    Engineering aspects and applications of crossflow microfiltration (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 17-25 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Crossflow microfiltration (CMF) is a pressure driven membrane process for the separation of suspended microparticles, bacteria and emulsion droplets. The fluid to be filtered flows in parallel to the membrane surface and restricts the formation of a filter cake. This contribution explains the basic process characteristics and the combination of the crossflow technique with other membrane cleaning methods (periodic backflushing, chemical cleaning). Special attention is paid to the influence of different process parameters on the flux through the membrane. The principle of plant design and different operation modes are described. Engineering aspects such as hydrodynamics, energy requirement and selection of construction materials are discussed in some detail.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110104
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    Mass transfer contributions of solid particles to gas permeation in viscous laminar tube flow (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 25-31 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: While two- and multiphase flows find more and more application in chemical engineering practice, and the demand for theoretical information about mass and heat transfer processes in such systems is increasing, such data or at least experimental results which could be generalized are still lacking. The following pages are concerned with mass transfer in laminar suspension tube flows normal to the main direction of flow due to the individual motions of small, inert spherical particles. On the basis of a large number of experimental data, an interpretation is attempted of the role of nearly neutrally-buoyant particles in mass transfer enhancement, and a model for a semi-empirical description is suggested. The experimental arrangement uses the mass transfer of carbon dioxide in laminar flow of salt water during the process of gas permeation through a permeable membrane tube wall.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110105
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  • 59
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    Interfacial areas and gas hold-ups at elevated pressures in a mechanically agitated gas-liquid reactor (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 1-10 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Interfacial areas and gas hold-ups were determined at pressures of up to 1.7 MPa in a glass vessel, 88 mm in diameter and of standard geometry. Superficial gas velocities between 0.25 and 2.0 cm/s were used and the stirring speed varied between 4 and 30 rps. The interfacial areas were determined by the chemical method, using the model reaction between CO2 and aqueous diethanolamine (DEA). Hold-ups were determined by observation of differences in height. In contrast to literature indications, the gas hold-up was found to be independent of reactor pressure. This is also true for the interfacial area.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110102
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  • 60
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    Effect of ethane addition on propane pyrolysis (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 243-248 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Pyrolysis of propane/argon mixture in the presence of trace quantities (0.1% and 0.9%) of ethane was investigated at reflected shock wave temperatures between 1200 and 2000K. Traces of ethane accelerated propane decomposition at high temperature. However, increase in the quantity of ethane added to propane/argon mixture did not result in the same increase of its accelerating influence. Ethylene, methane and acetylene were the main hydrocarbon reaction products, with small quantities of propylene and ethane detected only at lower temperatures. Below 1500K, addition of ethane slightly enhanced the yields of ethylene and methane at the expense of propylene and ethane respectively. The selectivity for acetylene increased with increasing temperature and with the decline of those for the other products. For none of the products, did the presence of ethane alter the relationship between product formation rates and temperature. The influence of ethane addition on propane pyrolysis at high temperatures was explained in terms of increased radical concentrations, especially hydrogen atoms and vinyl radicals, formed at high conversions. These accounted for the rapid acceleration of propane decomposition and the high yield of acetylene at high temperatures.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110132
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    Mass transfer in centrifugal extractorsPaper presented by F. Otillinger at the “Jahrestreffen der Verfahrens-Ingenieure”, Freiburg, September 30 to October 2, 1987. (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 312-320 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This contribution presents the methods of measuring the mass transfer in centrifugal extractors and of determining it during the individual life stages of a fluid element of the dispersed liquid, i.e. drop formation, motion, coalescence and stay in the stationary layer of the dispersed phase. The experimental mass transfer coefficients of the dispersed and continuous phases are compared with well-known theoretical models developed for extraction columns in gravitational field. Due to the fast motion and coalescence of the fluid particles at high centrifugal field intensities, mass transfer in centrifugal extractors takes place during short contact times. Nevertheless, this contribution shows that mass transfer in a centrifugal field can be calculated with selected theoretical models of the gravitational field. The investigations on mass transfer are completed by a classification of the strongly deformed fluid particles in centrifugal field into regimes of circulating and oscillating drops. In addition, data on the performance of centrifugal extractors, undergoing several exchange steps, are given.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110141
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    Kinetic investigation of methacrylic acid synthesis on hetropoly-compoundsDedicated to Professor Dr. Hanns Hofmann on the ocassion of his 65th bithday (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 392-402 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The kinetics of heterogeneously catalyzed methacrylic acid synthesis from isobutyric acid has been investigated. Initial catalyst screening pointed to 10-molybdo-2-vanado-phosphoric acid and its Cs-salts as the most promising catalysts. A model describing the reaction behaviour of all the different hetropoly-compounds used in this work was developed. A relationship was found between model parameters and composition of different catalysts. First insight was gained into the catalyst deactivation phenomena. Deactivation appears to be caused mainly by loss of molybdenum with simultaneous collapse of the Keggin structure.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110151
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    A new appraisal of mass transfer processes in zeolites by transient methodsDedicated to Professor Dr. Hanns Hofmann on the occasion of his 65th birthday (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 432-438 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Transient diffusion of inert gases into Zeolon 900 H, a zeolite of the mordenite type, was studied by the chromatographic method. Experiments were performed with argon and helium either as tracer or as carrier gas. The diffusion of argon was also studied in a carrier gas containing methanol at a low temperature (75°C, no reaction) and at higher temperatures (up to 130°C) when some dehydration of methanol to dimethyl ether takes place. The adsorption isotherm of argon is linear. In the absence of methanol, its penetration into microcrystals of zeolite is equally well represented either by an effective diffusion coefficient D′μ = 7.4 × 10-8exp(-2873/T)m2s-1 or by a mass transfer coefficient at the crystallite surface keμ = 1.9 × 10-4 exp(-1324/T) ms-1. A small amount of methanol in the carrier gas considerably slows down the transfer of argon (by a factor of 40 for D′μ and 550 for keμ) showing the “blocking” effect of adsorbed methanol. In addition, transient adsorption can no longer be accounted for by a single transfer time. The size distribution of microcrystals, determined from Scanning Electron Microscope photographs leads to a Transfer Time Distribution which account well for experimental breakthrough curves without any parameter fitting. This interpretation is supported by experiments under reaction conditions where transport of argon within crystallites increases faster with temperature than in the absence of reaction due to the transformation of methanol into dimethyl ether, which is less adsorbed and thus provides lesser hindrance to argon diffusion.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110155
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    Effect of chlorine on the selectivity of a fischer-tropsch catalyst composed of iron/vanadium oxidesDedicated to Professor Dr. Karl Schügerl on the occasion of his sixtieth birthday (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 32-39 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Fischer-Tropsch catalysts (Fe/V oxides with ZnO and K2CO3 as promoters) were exposed to CHCl3, thereby producing surface and bulk chlorides. The effect of this exposure on activity and selectivity was studied in a continuous recycle reactor at a total pressure of 10 bar (CO/H2 in most experiments: ca 1:1) in a temperature range between 200 and 343°C. CHCl3 was introduced in amounts of up to 1 × 10-2 mol chlorine per g catalyst. The catalyst samples were characterized by internal surface area, pore-size distribution and adsorption capacities for CO, H2 and C2H4. Prior to synthesis, the catalysts were reduced by H2. Catalyst exposure to CHCl3 resulted in a decrease of activity and considerable changes in product distribution. Hydrogenation and isomerization of 1-olefins were partly suppressed; the chain length of the products was slightly increased. Deactivation of the catalysts due to chlorine addition was partly reversible during operation, while olefin formation was not significantly altered with time-on-stream. The effect of chlorine on activity and selectivity is explained by dissociation of CO as the chain initiating step and CO insertion into a carbon/metal bond as a possible chain propagation step. Since adsorption capacity for H2 decreases on the addition of chlorine, this may also contribute to lower activity and change in selectivity, compared to the unexposed catalyst.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/ceat.270110106
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    Effect of enzyme inhibition on the performance of packed-bed biological reactor - a theoretical study (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 50-56 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The performance characteristic of a packed bed reactor has been analyzed by considering diffusional resistance of the biofilm. Model equations were solved by the method of orthogonal collocation for various classical enzyme inhibition kinetics, including partially non-competitive, partially competitive, partially uncompetitive, partially mixed and fully mixed. For all considered modes of inhibition, an increase in the inlet substrate concentration decreases the steady state conversion in the reactor. However, an increase in the Peclet number has been found to improve the conversion. The effects of various other process variables of physical importance were also investigated parametrically.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110108
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  • 66
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    Derivation, selection, evaluation and use of asymptotes (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 63-72 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Asymptotes are known to be useful, but their potential in interpreting and correlating chemical and physical behaviour is seldom exploited fully. The derivation and selection of asymptotes for particular as well as limiting cases is described. The evaluation of the range of validity and applicability, if any, of asymptotes is also considered. Asymptotes are shown to be uniquely useful in the identification of groupings of variables which minimize parameteric variations, as upper and lower bounds, as trial functions in the method of weighted residuals, and most especially as components of correlating equations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110110
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  • 67
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    A robust pole-placement self-tuning controller for chemical process control: Theoretical studies and simulation (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 57-62 
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    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A single variable pole-placement self-tuning controller (PPSTC) is used to simulate examples typical of chemical processes; i.e., open-loop stable, unstable, and unstable non-minimum phase systems with unknown varying process dead time. The PPSTC is shown to be effective in each case. Set-point tracking and rejection of randomly occurring deterministic disturbances for all three types of processes are achieved. Simultaneous estimation of process parameters and process time delay is realized by using a recursive extended least squares method.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110109
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    The influence of stress and attrition on crystal size distributionPaper presented at the Annual Meeting of German Chemical Engineers 1986, September 17 to 19, in Strasbourg.Dedicated to Prof. Dr.-Ing. Rolf Lacmann on the occasion of his 60th birthday (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 40-49 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An important parameter influencing the crystal size distribution in mass crystallization from solution is the mechanical stress exerted on crystals in the crystallizer. This contribution presents the study of the influence of mechanical stress and attrition of the system potassium nitrate-water in an FC-crystallizer and in various draft-tube crystallizers, fitted with different types of impellers. The intensity of stress is a newly defined variable which is used to describe the level of stress in crystallizers. The reduction of crystal size by attrition is described by the linear attrition rate. The influence of impeller design and crystal hold-up on crystal size distribution and scale-up rules is discussed.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110107
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    Attrition and secondary nucleation in crystallizers (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 80-88 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The mean crystal size of coarse crystalline products is determined by secondary nucleation and crystal growth. Secondary unclei are mainly produced by contacts of crystals with parts of the crystallizer or with other crystals. As a consequence, attrition effects are very important. In this paper, a model is proposed in order to calculate the attrition rate of crystals, depending on the physical properties of the crystalline product, the geometry of the crystallizer and on the operating conditions such as the stirrer speed or the suspension density. The effective rate of secondary nucleation can be expressed in terms of the attrition rate by introducing effective values for number and size of attrition particles. Finally, a scale-up criterion based on this model is derived. This criterion allows to predict effective rates of secondary nucleation and mean crystal sizes if data obtained in a laboratory crystallizer are available.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110112
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  • 70
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    Theoretical and experimental study of sedimentation in vertical flow tanks (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 95-104 
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    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Settling characteristics of four different suspensions were measured by batch settling tests (glass spheres in glycerol-water mixtures and CaCO3) and by continuous settling test in a bench-scale vertical flow tank (activated sludge and kaolin in water), including the measurement of solids concentrations inside the tank. The characteristics could be described by different correlation functions which now include all the information about the settling behaviour of ideal suspensions. Continuous settling experiments in a bench-scale vertical flow tank were carried out with the same four material systems. These results correspond with sufficient accuracy to those from the theory of limiting flux if the settling characteristics determined earlier are considered.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110114
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    Thermal deactivation of heterogeneous catalyst, part 1. The theta-rule - a critical review (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 113-119 
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    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Thermal deactivation can be described either by deactivation kinetics or by the isokinetic effect. The latter expression is used synonymously with the “compensation effect” and the “Theta-Rule”. An examination of the original literature shows that only the compensation effect is applicable to thermal deactivation but not the Theta-Rule. The introduction of the preparation temperature as a parameter of the compensation effect results in a “modified Theta-Rule”, which describes the experimental data and is proposed for the non-separable kinetics. The consequence of the observed deviations from the validity range of the Theta-Rule is that the activation energy cannot be used as a universal activity criterion.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/ceat.270110116
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  • 72
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    The stability of crude oil residues and factors affecting their decomposition during mild thermal treatment (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 89-94 
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    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A number of topped crude oil residues were subjected to mild thermal cracking in the temperature range between 613 and 673K at N2 pressure of one atmosphere. It was found that the thermal stability of the six topped crude oils decreased in the order Brent 〈 Piper 〈 Auk 〈 Saudi Arabian 〈 Romashkinskaya 〈 Tia Juana Pesado. This was measured in terms of light end production (C1-C5 hydrocarbons). The asphaltene, sulphur and metal (nickel and vanadium) contents were also determined. The production of light ends, exemplified by methane, was found to be related to the metal asphaltene content of the crude oils, but the sulphur content exerted a moderating influence upon the extent of cracking. Hence, metal asphaltenes, probably as metal porphyrins, catalyse cracking but the presence of sulphur reduces that catalytic activity and can inhibit cracking. If cracking of long chain hydrocarbons is to be minimized, metal asphaltenes should be removed (preferably) or reduced in concentration or poisoned, in order to decrease their catalytic activity.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110113
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    Kinetic analysis of the oxidation of isobutyraldehyde in liquid phase (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 120-126 
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    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The kinetics of non-catalytic as well as catalytic oxidation of Isobutyraldehyde has been investigated. Reaction rate equations for the formation of the main product isobutyric acid and of the side products acetone, CO and CO2 were derived. Kinetic parameters, namely the order of reaction, preexponential factor and activation energy were estimated by non-linear regression. The influence of selectivity and activity of the different type of catalysts employed was investigated quantitatively.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110117
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  • 74
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    Thermal deactivation of heterogeneous catalysts. Part 2: The compensation effect and the Catalytic Paradox (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 228-236 
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    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The interpretation of the term “compensation” obscures a logical contradiction, the catalytic paradox, which is caused by inconsistent validity ranges of the Arrhenius parameters, the pre-exponential factor and the activation energy. For this reason, a theory which contains the Arrhenius parameters cannot be established for the entire system (whole temperature range) on the basis of classical logic. Only the subsystems can be consistent and complete. One subsystem is the range of the topocatalytic concept which is relevant for thermal deactivation, thermal bistability and for all reactions with surface dependence of activity. The other is the range of the energetic concept which is preferred in fundamental research. In order to complete the subsystems, new consistent symbols are introduced. The change of particle size caused by thermal deactivation can result in four possible particle size effects, two of which have been discussed in the literature.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110130
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    Thermal radiation of gas/solid mixturesPaper presented by Th. Elsner at the “Jahrestreffen der Verfahrens-Ingenieure”, Freiburg, September 30 to October 2, 1987. (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 237-243 
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    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Thermal radiation of gas/solid mixtures in high-temperature heat exchangers is of considerable importance for the design of heat exchange surfaces. Therefore, an experimental plant was constructed to measure solid particle emissivities, since there is a lack of relevant data in the existing literature. A theoretical equation was derived to describe the solid particle emissivity as a function of layer thickness, specific solid surface area, solid loading and absorption and scatter coefficients. Measurements were carried out for fluidized bed ash and quartz sand. The emissivities of these particle fractions increase with increasing layer thickness, slid loading, specific solid surface area and temperature. The description of these data by the derived model equation is very satisfactory. No dependence on wavelength was observed. The ash components do exert some influence which, for the present, cannot be described exactly.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110131
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    Application of modern packings in thermal separation processesPaper presented by R. Villet at ACHEMA ′85. (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 213-227 
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    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A report is presented on the performance of modern dumped and structured packings for application in the field of thermal separation processes. The evaluation of the results is based on extensive experimental investigations of rectification, absorption, and desorption systems. The following are indicated: the efficiency in terms of the number of theoretical stages per unit height or in terms of the height of transfer unit or volumetric mass transfer coefficient, the pressure drop per unit height as well as per theoretical stage or per gas phase transfer unit, and the liquid hold-up, whereby either the gas capacity factor or the liquid load was adopted as influencing parameter, and finally the maximum gas capacity factor as a function of the flow parameter. The results are presented in diagrams and tables.
    Additional Material: 25 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110129
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  • 77
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    Volumetric mass transfer coefficient in stirred reactors (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 249-251 
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    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: It is shown that the volumetric mass transfer coefficients, presented recently by Schmitz et al. [1] for viscous solutions of carboxymethyl cellulose (CMC) in aqueous sodium sulphite, are considerably underestimated as a result of unjustified neglect of the oxygen back pressure during oxygen absorption. Schmitz et. al. [1] found a decrease in the exponent n in the relationship between the oxygen mass transfer coefficient, kla, and the power dissipated per unit volume of the liquid phase, e (kla ∝ en), and ascribed it to viscosity effects. However, no such decrease is observed, provided that the actual oxygen back pressure is taken into account.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/ceat.270110133
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    Effect of combustion air preheating on NOx emissions from gas burners in high-temperature industrial applicationsPresented by M. Flamme at the “Jahrestreffen der verfahrens-ingenieure”, strasbourg, september 17 to 19, 1986. (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 104-112 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: NOx emissions from different commercial gas burners for metal heat treatment applications were measured for a research project of the Gaswärme-Institut. The burners, rated at up to 50 kW, were installed for the tests in a laboratory combustion chamber operated at temperatures of up to 1400°C. The air for combustion was preheated to maximum temperature of 600°C. Following the tests, the potentials of different NOx control techniques were investigated. Methods explored included staged combustion air injection, staged fuel injection and fuel gas injection into the flue for NOx reduction. The results showed that it is feasible to reduce the NOx content of flue gases by as much as 90%.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110115
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    A new fluid dynamic model for mixing of newtonian and power-law liquids in the transient regimeModified version of a paper presented at the “GVC Working Party on Mixing”, Trier, 4./5. May 1987. (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 162-170 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In the description of mixing processes influenced by viscosity in pseudoplastic (power-law) fluids, a definition of representative viscosity is normally used which takes into account the variable flow behaviour of the stirred material as a result of different shear stresses. In this context, the Metzner and Otto concept, which postulates that a representative shear rate is proportional to stirring speed, has become widely know, although the power calculation is inaccurate, particularly in the transient regime between the laminar and turbulent flow. A new model of fluid dynamics in the mixing vessel is presented, based on the increase of the mean flow velocity standardized with the stirrer's tip velocity in the transition regime. It provides a physical explanation for the above deviations. A suitable definition of representative viscosity substantially improves the accuracy of calculations of the stirring power in power-law fluids.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110122
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  • 80
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    Scale-up of bioreactors for fermentation of mammalian cell cultures with special reference to oxygen supply and microcarrier mixingPaper presentet by J. Vorlop at the “Jahrestreffen der Verfahrensingenieure”, September 17 to 19, 1986 in Strasbourg (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 171-178 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The increasing demand for products from mammalian cells has prompted the authors to develop a new type of bioreactor. Its significant features include the supply of oxygen, homogeneous distribution of microcarrier suspensions and process control. Media with high protein contents, required for mammalian cell cultures tend to generate foam. This causes the flotation of solid particles. The reactor was equipped with a system of porous hydrophobic Accurel hollow fibre membranes in order to prevent the formation of bubbles. The membrane is coiled in the form of a basket, or fixed on several carriers. If the liquid pressure is higher than that of the gas phase inside the membrane, a bubble - free oxygen supply to the culture broth can be achieved. The problem of axial mixing of microcarier suspensions was solved by the use of a spiral agitator, attached underneath the aeration system at the bottom of the reactor. The combined aeration and mixing system, which is driven by an eccentric motor, undergoes a tumbling motion. Sufficiently homogeneous suspensions are produced in this system at low membrane velocities, i.e. in presence of low shear forces.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110123
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  • 81
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    Organosolv delignification of southern pine - an alternative pulping process (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 195-199 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Aqueous ethylenediamine-ethanol-anthraquinone (EDA-EtOH-AQ) pulping of Southern Yellow Pine was studied for lignin removal and pulp yield. Temperature, time and ethylenediamine concentration in the solvent solution were studied and equations for lignin content and lignin-free yield were developed. Lignin content is decreased by an increase of temperature, time or EDA concentration. Lignin-free yield of pulp decreased with an increase in temperature or time, but increased with increasing EDA concentration. Overall, the solvent is selective, that is, large quantities of lignin are removed while the retention of cellulose remains high.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110126
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  • 82
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    Influence of mechanical stress on the growth of Rhizopus nigricans in stirred bioreactorsPaper presented at the “Jahrestreffen der Verfahrensigenieure”, Freiburg, September 30 to October 2, 1987. (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 178-187 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This investigation was undertaken in order to examine the factors affecting mechanical damage to micro-organisms in stirred bioreactors. Growth of the mould Rhizopus nigricans was studied in stirred bioreactors at different geometrical and operating parameters. Since experimental results cannot be described by conventional key parameters, a new concept has been suggested. It is based on the analogy to processes of mechanical disintegration. It is shown that the same key parameter, i.e. the ratio of power input to flow rate, can be used for a satisfactory correlation of experimental data on mechanical damage to micro-organisms, which is an important step in the recovery of intracellular products in biotechnology.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110124
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  • 83
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    Consistent scale-up procedure for the power consumption in agitated non-newtonian fluids (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 199-205 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: It is shown how a consistent scale-up rule for the power consumption in agitated non-Newtonian liquids can be obtained. The new approach is based on the concept of including the real liquid in a set of liquids with similar rheological properties and of using, in a small scale laboratory system, a suitable member of that set instead of the original liquid. Considerations of similarity lead to simple unique selection rules for the actual test liquid and for the stirrer speed in the laboratory experiment as well as to a prediction of the power requirement in the real system. The theory is tested experimentally by means of different aqueous polyacrylamide solutions. The results are compared with predictions, according to Metzner and Otto as well as Rieger and Novák.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110127
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  • 84
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    Bubble column research in Japan (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 205-212 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Many experimental studies on the bubble column have been reported by Japanese researchers since around 1960. They include studies of bubble behaviour, bubble size distribution, transition from the homogeneous bubbly flow regime to the heterogeneous liquid circulation regime, liquid velocity distribution, longitudinal liquid mixing, hydrodynamic modelling, the gas holdup, and the volumetric coefficient of gas-liquid mass tranfer kLa. Studies covered various modified bubble columns, such as the airlift reactor with an external or internal loop, the packed bubble column, and others. Performance of three-phase bubble columns, which deal with suspensions or emulsions, and their use as bioreactors or chemical reactors were also studied.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110128
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  • 85
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    A model-based control system for a distillation columnPaper presented by F. F. Rhiel at the “Jahrestreffen der Verfahrens-Ingenieure”, Freiburg, September 30 to October 2, 1987. (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 188-194 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A control concept which includes an adaptive multivariable control algorithm and an observer model has been put into practice in the operation of a distillation column which separates water from a solvent. The model yields predictions of solvent concentration in the waste water which forms the top product. Early detection of disturbances permits an adjustment of the process in time. This has resulted in an exceptionally smooth operation of the column, with a drastic reduction in solvent concentration fluctuations, observed with conventional control technology. Since the only measurements required are pressure, temperature and the rate of flow, this control system is largely free from disturbances. In addition to considerably reducing the burden on operating personnel, use of this control system has lowered the costs of waste water treatment, solvent losses, analysis expenditure and energy consumption.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110125
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  • 86
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    Parametric sensitivity of the ignition process to mass transfer in adiabatic tubular reactors with exothermic heterogeneous reactions (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 251-258 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The alternative effects of reaction kinetics, mass, heat and momentum transport on mass conversion by chemical reactions are examined theoretically for a reacot tube with laminar flow. The reaction enthalpy is considered. A heterogeneous reaction between several gaseous components takes place at the inner surface of this reactor tube. Strongly exothermic reactions lead to self-acceleration of the reaction, unless reaction enthalpy is removed through the tube wall. Under certain conditions, there will be a sudden change from mass transfer controlled by the reaction to that controlled by diffusion. This phenomenon is known as ignition of the reaction. The effect of ignition and its sensitivity to reaction enthalpy, thermal conductivity and diffusivity of the fluid as well as activation energy of the first order heterogeneous wall reaction are investigated by a numerical solution of the transport equations. Axial conduction of heat and mass is neglected both in the fluid and in the tube wall. Non-stoichiometric wall reactions of first order, with temperature dependent reaction rates and equilibrium constants, are considered. The results are presented in graphical form, as plots of the local mass flux at the reacting wall as functions of the dimensionless tube length.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110134
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  • 87
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    Chemical engineering aspects of precipitation from solutionPaper presented by A. Mersmann at the “Jahrestreffen der Verfahrens-Ingenieure”, Freiburg, Spetember 30 to october 2, 1987. (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 264-276 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Precipitation is a rapid solidification. As a rule, it applies to substances which are sparingly soluble and is coupled with a chemical reaction or with a salting out process. The chemical engineer has to ensure that the product obtained has a constant and preferably coarse size distribution. This contribution compares the literature data on crystallization of soluble and sparingly soluble substances; it can be shown that, during precipitation processes, nuclei are formed, most probably by a primary mechanism. Analysis of the processes occurring during precipitation, such as chemical reaction, mixing and crystallization, leads to recommendations for the operation of precipitation processes.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110136
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  • 88
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    Scale-up of mechanically agitated extraction columnsPaper presented at the “Jahrestreffen der Verfahrens-Ingenieure”, Freiburg, September 30 to October 2, 1987 (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 259-263 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The deterioration of mass transfer efficiency of an extraction column with increasing column diameter is the result of developing residence time distributions. These effects can be described by one-dimensional dispersion model. However, it must be verified whether the requirements for its application are fulfilled in the different types of agitated extraction columns. For the columns for which the dispersion model can be applied, a relationship will be derived between the necessary increase of column height with column diameter. This is based on the equations for calculation of the dispersion coefficient of the continuous phase. If the dispersion model cannot be applied to given a type of column, an investigation will be made on the possible modifications of operation or changes in construction, in order to permit a scale-up procedures as proposed here.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110135
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  • 89
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    Development of design charts for fixed-bed adsorptionPaper presented by W. Otten at the “Jahrestreffen der Verfahrens-Ingenieure”, Freiburg, Spetember 30 to October 2, 1987. (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 289-297 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A mathematical model of the dynamic behaviour of non-isothermal fixed-bed adsorbers has been developed which takes into account the various mass and heat transfer resistances. Comparison of experimental and simulated results confirms that the model can predict the adsorption and desorption breakthrough curves of an adiabatically operated column, using only equilibrium data and tortuosity factors obtained from single pellet experiments. A simplified model with a reduced number of parameters was derived by investigation of the dimensionless transfer parameters under industrial conditions. It becomes evident that the main transfer mechanisms are convective heat and mass transfer in the bulk flow and diffusion within the pores of the particle. Dimensionless effluent concentration is expresses in terms of dimensionless time, a transport parameter, a non-isothermal parameter, the adsorption equilibrium and the inlet and initial concentrations and temperatures in the simplified model. For a chosen system of adsorbate and adsorbent, design charts can be developed by computer simulation, to determine graphically the breakthrough time as a function of significant process parameters, i.e. the dimensionless transfer parameter and the feed concentration.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110138
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  • 90
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    The significance of fly ash in wet-dry scrubbing of SO2 (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 298-305 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A bench scale flue gas desulphurization spray dry scrubbing unit was employed to study the effect of fly ash on the removal of SO2. The equipment consisted of a spray dryer with and ultrasonic nozzle for atomization and a pulse jet baghouse. The flue gas rate was 1500 lN/h (dry gas). Four fly ashes, originating from different countries were investigated. The alkalinity and reactivity of the fly ashes were determined in a pH-stat equipment. Pure fly ash removed SO2 in both the spray dryer and in the baghouse. An increase of humidity divided the fly ashes into two groups. The high calcium fly ash gave a considerably higher SO2 removal than the medium and low calcium fly ashes which showed similar SO2 removals. Fly ash did not enhance the removal of SO2 when added to a lime slurry because lime suppresses the dissolution of the alkali in the fly ashes. The pressure drop build-up in the fabric filter showed a strong dependence on material properties.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110139
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  • 91
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    Subcooled boiling heat transfer to R 12 in an annular vertical channel (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 320-327 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Detailed knowledge of the physical phenomena involved in subcooled boiling is of great importance for the design of liquid-cooled heat generating systems with high heat fluxes. Experimental heat transfer data were obtained for forced convective boiling of dichloro-difluoroethane (R 12). The flow is circulated upwards through a concentric annular vertical channel. The inner and outer diameters of the annulus are 0.016 m and 0.03 m respectively. The reduced pressures studied were 0.24 ≤ p/pcrit ≤ 0.8, inlet subcooling varied from 10 to 75 K and mass fluxes from 500 to 3000 kg/m2s, which corresponds to Re numbers from 30000 to 300000. The experiments, described in this study, demonstrate that liquid fluorocarbons show certain unusual boiling characteristics in the subcooled flow, such as hysteresis of the boiling curve. These characteristics are attributed to the properties of the fluid, mainly the Pr number and the very low surface tension. The pronounced boiling curve hysteresis can be explained by the fact that large nucleation sites may have been flooded prior to incipient boiling. A dimensionless regression formula is presented which predicts the onset of subcooled boiling as a function of reduced pressure (p/pcrit), Boiling-(Bo), Reynolds-(Re), and a modified Jacob number (Ja), over the whole range of parameters studied, with a good accuracy, including water data from literature.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110142
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  • 92
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    Mass transfer behaviour of gas-liquid jet loop reactorsPaper presented by M. Geisendörfer at the “Jahrestreffen der Verfahrens-Ingenieure”, Freiburg, September 30 to October 2, 1987.Dedicated to Professor Dr. Horst Langemann on the occasion of his sixtieth birthday (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 306-311 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A special type of jet loop reactor (JLR), designed for continuous operation and short residence times was investigated with regard to its mass transfer behaviour, described by the volumetric mass transfer coefficient kLa. The jet stream and superficial gas velocities are varied in two JLRs of different sizes, equipped with different nozzles. Fully desalinated water, 0.08 molar NaCI solution and solutions of different concentration of carboxymethyl cellulose (CMC) are used as the liquid phase. A steady-state physical method is employed to determine kLa: air oxygen is purged from the liquid phase by gaseous nitrogen. The measurements show that the reactor is characterized by high power density and high mass transfer performance. No limit of mass transfer capacity was observed in the chosen ranges of volumetric gas and liquid flow rates, i.e. at a given jet stream velocity, the relationship between kLa and the superficial gas velocity is nearly linear. The investigations show that the mass transfer contributed by the jet stream largely depends on liquid phase composition.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110140
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  • 93
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    Characteristics of solid suspensions in a bubble column without and with draft tubePaper presented by J. Heck at the “Jahrestreffen der Verfahrensingenieure”, Freiburg, September 30 to October 2, 1987. (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 335-340 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In order to investigate the suspension behaviour of solid particles in bubble columns without and with draft tube, minimum gas velocities for generating and maintaining complete solid suspension were determined. Experiments were carried out in a bubble column with a diameter of 200 mm and a height of 2 500 mm. The bubble column could be equipped with a draft tube with a diameter of 120 mm and a length of 1 500 mm. The state of suspension was determined by measuring the hydrostatic pressure as a result of suspended solid particles with an inductive pressure gauge. Solid content εs, solid density ϱs, particle size dp, particle shape, particle size distribution, and solid wettability were varied. Furthermore measurements of integral gas holdup were carried out.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110144
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  • 94
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    Modelling of multiphase detonations with drop disintegration - description of thermal detonations (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 327-334 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A model is presented which consists of steady-state and transient codes for the description of reacting multiphase flow fields, including hydrodynamic fragmentation of liquid drops in relative flows. An application of this model for the description of large scale melt-coolant interactions (thermal detonations) is described. A simulation of two-phase chemical detonations, especially those with hydrodynamic disintegration of liquid fuel drops in the reaction zone, is possible, in principle, within the framework of the modeling.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110143
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  • 95
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    Modelling of a pressure swing adsorption process for oxygen enrichment with carbon molecular sievePaper presented by E. Richter at the “Jahrestreffen der Verfahrens Ingenieure”, Freiburg, September 30 to October 2, 1987. (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 341-351 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Adsorptive separation of oxygen from nitrogen and argon is carried out during the desorption steps of a pressure swing adsorption (PSA) process which uses carbon molecular sieves developed by Bergbau-Forschung GmbH. The adsorption isotherms of the three main components of air are very similar. On account of the pore size distribution of CMSN2, the diffusion coefficient of oxygen is more than eight times those of nitrogen and argon so that air separation occurs by adsorption kinetics. Experimental results for the individual steps and cyclic operation of the PSA process are presented and compared with the predictions of an isothermal plug-flow model. Adsorption rate is represented by a linear driving force equation. If the diffusion coefficients are adapted separately to every step, a good agreement is observed between the model calculations and experimental results.
    Additional Material: 22 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110145
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  • 96
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    The importance of corrosion prevention for the safety of chemical plants (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 359-365 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: One of the most important tasks to eliminate dangers in chemical plants is the prevention of corrosion. This implies the provision of safe enclosures and reaction spaces for the substances to be processed. The present contribution deals with the procedure in the selection of materials for equipment exposed to corrosion and stresses the difficulties connected with the elimination of local corrosion. The relevance of prevention of crack forming corrosion processes is emphasized. Problems to be solved in order to obtain results from investigations, suitable for a safe application of a materials under practical conditions, are indicated.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110147
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  • 97
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    Modelling of activated carbon desorption by a circulated inert gasPaper presented at the “Jahrestreffen der Verfahrens-Ingenieure”, Freiburg, September 30 to October 2, 1987 (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 352-358 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The adsorption solvent recovery process, known as Recursorb which involves desorption and cooling steps by a circulated inert gas, is analyzed in detail on the basis of equilibrium theory. Employing the method of characteristics, the model is solved for each step of the overall process. The estimations confirm that the process performance with respect to final gas purity, activated carbon useful capacity and operation times depends on condenser and heater temperatures. Simple expressions are derived for the calculation of adsorption, desorption and cooling times.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110146
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  • 98
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    Decoking of fixed-bed catalytic reactorsDedicated to Prof. Dr. Hanns Hofmann at the ocassion of his 65th birthday (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 367-375 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A mathematical model for the description of the non-steady state process of decoking of a fixed bed catalytic reactor is presented. The relevant dimensionless groups are identified and their influence on the process discussed. Appropriate relationships are given for the estimation of the maximum temperature in the bed. Methods of monitoring the process and of controlling it in the case of unknown or variable coke contents are explained.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110148
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  • 99
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    Model discrimination and parameter estimation in the kinetic study of methanol synthesisDedicated to Professor Dr. Hanns Hofmann on the occasion of his 65th birthday (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 375-383 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The new model discrimination method is based on the correlation coefficient test of experimental data sets for different reactions, without requiring a prior parameter estimation. The new parameter estimation method reduces by n the number of dimensions to be tested, compared to the classical method where n is the number of independent reactions in the system. This has reduced the computation time for most complex reactions to a level, comparable to that needed for single reactions. The example used is the kinetic study of methanol synthesis in which the formation rates of methanol, methane, ethanol and ethane are considered. Two adequately accurate models were obtained from an extensive range of plausible models by using the new model discrimination and parameter estimation method with a relatively small computation effort.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110149
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    Evaporation and pervaporation of a binary mixture from an inert carrier liquidDedicated to Professor Hanns Hofmann on the occasion of his 65th birthday (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 384-391 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Bench-Scale experiments were carried out with the ternary mixture 2-propanol/water/glycerol. In a cylindrical vessel, the stirred and thermostated liquid was exposed to a preheated and either dry or humidified air stream. The mixture was evaporated either from a free surface or from the surface of a porous plate. On evaporating the mixture from a porous plate into a dry air stream, the less volatile component water escapes preferentially; in the case of evaporation from a free surface, water is retained in the mixture. In the former case, selectivity is liquid diffusion controlled, in the latter, the gas-side mass transfer and the thermodynamic equilibrium are the controlling mechanisms. On reducing the gas flow rate, the more volatile alcohol evaporates preferentially in both cases; the selectivity is controlled only by thermodynamic equilibrium. Humidification of the air stream with water vapour causes preferential evaporation of the alcohol at an increased rate. Furthermore, instabilities in the liquid boundary layer due to density gradients and surface tension effects may affect the selectivity of evaporation. Experimental results show that the selectivity of evaporation can be manipulated by choosing appropriate evaporation conditions. The theory, which applies the generalized Stefan-Maxwell equations to diffusion in the liquid, can describe these effects.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110150
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