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  • 101
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 119 (1978), S. 227-229 
    ISSN: 1432-072X
    Schlagwort(e): Cell wall ; Electron microscopy ; Methylomonas albus ; Goblet sub-units
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract In surface view, the cell wall complex ofMethylomonas albus possesses a hexagonal pattern of ridges. Thin sections reveal a continuous layer of goblet-shaped elements attached to the outermost surface of the lipopolysaccharide membrane. A possible interpretation of the cell wall complex ofM. albus, based on the fine-structural data is presented.
    Materialart: Digitale Medien
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  • 102
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 118 (1978), S. 305-308 
    ISSN: 1432-072X
    Schlagwort(e): Carotenoid mutant strain R-26-Rhodopseudomonas sphaeroides ; Electron microscopy ; Intracellular membranes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Stained thin-sections and freeze-fractured preparations of the carotenoid-less mutant strain R-26 of Rhodopseudomonas sphaeroides grown photosynthetically revealed 2 morphological kinds of intracellular membrane systems- spherical vesicles distributed throughout the cytoplasm and lamellae confined to the periphery of the cell. The lamellar membranes appeared to be large, flattened vesicles.
    Materialart: Digitale Medien
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  • 103
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 116 (1978), S. 133-139 
    ISSN: 1432-072X
    Schlagwort(e): Lagenisma ; Coscinodiscus ; Infection ; Endosymbiotic bacteria ; Tip growth ; Wall-less thallus ; Host-parasite interface ; Membranes ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Lagenisma coscinodisci is diplanetic and has two different cyst stages. The secondary cyst has a uniform cell wall of fibrillar material. It attaches to a Coscinodiscus frustule and germinates with an infection tube. The cyst becomes filled with an enlarging expulsion vacuole. The infection tube penetrates the diatom cell between the cingula. Inside the host cell the fungus grows as an irregularly branched wall-less thallus. In the hyphae apical vesicles are lacking. The infection tube is plugged by wall material. There are no microtubules which might participate in the morphogenesis of the thallus. The plasmalemma of the diatom is pushed inward but not pierced by the fungus. Along the host-parasite interface it lies closely paralled to the Lagenisma plasmalemma which is extremely straight here and measures about 10 nm instead of about 5–6 nm at the surfaces of other stages. The Coscinodiscus plasmalemma disintegrates at about the same time when the cytoplasm breaks down. The fungus allows bacteria to enter the diatom; there are also endosymbiontic bacteria in unattacked cells — The growth mechanisms are discussed and the host-parasite interface is compared with that of other fungi.
    Materialart: Digitale Medien
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  • 104
    Digitale Medien
    Digitale Medien
    Springer
    European archives of psychiatry and clinical neuroscience 225 (1978), S. 127-134 
    ISSN: 1433-8491
    Schlagwort(e): Toxoplasma gondii ; Toxoplasmosis, cerebral ; Encephalopathy, toxoplasmic necrotizing ; Hodgkin's disease ; Immunosuppression ; Electron microscopy ; Toxoplasma gondii ; Toxoplasmose, cerebrale ; Toxoplasma-Encephalopathie, nekrotisierende ; Morbus Hodgkin ; Immunsuppression ; Elektronenmikroskopie
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Ein 41jähriger Mann verstarb unter progredienter cerebraler Symptomatik, nachdem 11 Jahre ein Morbus Hodgkin bestanden hatte, der mit Röntgenbestrahlungen, Cytostatika und Corticoiden behandelt worden war. Autoptisch fanden sich nicht sehr ausgedehnte Manifestationen der Lymphogranulomatose im Thoraxbereich und multiple käsige Nekrosen im Gehirn. In diesen konnten licht- und elektronenmikroskopisch Toxoplasmen nachgewiesen werden. Die auffallend geringe Intensität der entzündlichen Reaktion im Bereich der Nekroseherde deutete darauf hin, daß sich der Patient in einem immunsuppressiven Zustand befunden hatte. Pathomorphologie und Klinik der cerebralen Erwachsenen-Toxoplasmose werden besprochen. Auf ihr vorzugsweises Auftreten bei konsumierenden Krankheiten, insbesondere bei Morbus Hodgkin, wird nachdrücklich hingewiesen.
    Notizen: Summary A male patient with a history of Hodgkin's disease of 11 years duration died at age 41 with signs of progressive cerebral involvement. The blastomatous process had been treated with X-rays, cytostatic agents, and corticosteroids. Autopsy revealed isolated lymphogranulomatous lesions in the chest walls and multiple foci of necrosis in the brain. In the latter, Toxoplasma could be detected by light and electron microscopy. The inflammatory response elicited by the protozoan parasite was strikingly slight. This indicated that the patient had had some immunologie impairment. Pathomorphologic and clinical aspects of cerebral toxoplasmosis in the adult are discussed. It is emphasized that patients suffering from chronic malignant disorders, particularly Hodgkin's disease, are preferentially affected by toxoplasmosis of the brain.
    Materialart: Digitale Medien
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  • 105
    Digitale Medien
    Digitale Medien
    Springer
    European archives of psychiatry and clinical neuroscience 225 (1978), S. 275-282 
    ISSN: 1433-8491
    Schlagwort(e): Metachromatic leucodystrophy, adult ; Sulfatidosis ; Intracellular storage ; Lamellar inclusions ; Electron microscopy ; Metachromatische Leukodystrophie, adulte ; Sulfatidose ; Intracelluläre Speicherung ; Lamelläre Einschlüsse ; Elektronenmikroskopie
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Primär formalinfixierte Gewebsproben aus der entmarkten weißen Substanz des Stirnhirns eines Autopsiefalles von adulter MLD wurden elektronenmikroskopisch untersucht. Das intracelluläre Speichermaterial ließ folgende Strukturmuster-Typen erkennen: (I) Gewöhnliche Myelinfiguren; (II) gefältelte Myelinfiguren; (III) schmale Stapel von scheibchenförmigen Lamellen, die sehr wahrscheinlich Bestandteile von ehemals kompakten „prismatischen“ Einschlüssen waren; (IV) gepaarte Lamellen, entweder in lockerer paralleler Anordnung oder in regelloser Verteilung und Ausrichtung; (V) Schichten von parallel verlaufenden Lamellen mit alternierend dichten und kontrastarmen Zwischenräumen; und (VI) Häufchen von Gebilden, die Bruchstücken von sog. pentalaminären Membranen glichen. Die Typen I bis IV sind sowohl bei Früh-als auch bei Spätformen der MLD schon beschrieben worden, die Typen V und VI dagegen noch nicht. Möglicherweise hatten postmortal-autolytische Vorgänge eine Änderung der strukturellen Organisation von einigen cytoplasmatischen Ablagerungen und die Ausbildung dieser bisher bei der MLD unbekannten Lamellenmuster bewirkt.
    Notizen: Summary Formalin-fixed samples from the demyelinated frontal white matter of an autopsy case of adult-onset MLD were studied by electron microscopy. The intracellular storage materials exhibited the following types of structural patterns: (I) ordinary myelin figures; (II) pleated myelin figures; (III) narrow stacks of lamellar discs which were most likely components of formerly compact ‘prismatic’ inclusions; (IV) paired lamellae, either arranged in loose parallel arrays or scattered about in random directions; (V) piles of parallel lamellae with alternating electron-dense and electron-lucent interspaces; and (VI) collections of structures resembling fragments of so-called pentalaminar membranes. Types I to IV have already been described in early-onset as well as in late-onset forms of MLD, but types V and VI have not. Postmortem autolysis had possibly altered the structural organization of some cytoplasmic deposits and given rise to the formation of those lamellar patterns which were hitherto not known to occur in MLD.
    Materialart: Digitale Medien
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  • 106
    Digitale Medien
    Digitale Medien
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 302 (1978), S. 239-254 
    ISSN: 1432-1912
    Schlagwort(e): Myocardial α-adrenoceptors ; Rat ; Guinea pig ; Cat ; Hypothyroidism ; Single adrenoceptor type
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The presence and distribution of myocardial α-adrenoceptors in different parts of the heart of various mammalian species was investigated. For this reason experiments were performed in isolated cardiac preparations of rats, guinea pigs and cats. In order to obtain more information about the nature of the cardiac α-adrenoceptors additional experiments were undertaken at different temperatures. These studies were aimed to show whether or not a conversion of β-to α-adrenoceptors or vice versa takes place. Moreover, we analyzed the influence of hypothyroidism on the sensitivity of α- and β-adrenoceptors of preparations from rats fed with propylthiouracil. Finally, we tried to find out whether stimulation of these α-adrenoceptors leads to the formation of the cyclic nucleotides cAMP and cGMP. The following results were obtained: 1. In right ventricular strips of rats, guinea pigs and cats phenylephrine stimulated α-adrenoceptors. After blockade of β-adrenoceptors the respective pD2-values of phenylephrine were 5.32, 5.99 and 5.33. The doseresponse curves obtained in the presence of α-adrenolytic drugs were shifted to the right without depression of the maximum. In the rat, in addition, the pA2-values for the α-adrenolytic drugs yohimbine (5.79) and phentolamine (7.85) were determined. They were at least 0.5 log units higher than those found in the rat for other α-adrenoceptors (Van Rossum, 1965) thus supporting the view that the population of cardiac α-adrenoceptors is different from that of other organs. In left ventricular strips of guinea pigs the pD2-value for the α-mimetic effect of phenylephrine was of the same order of magnitude as that obtained in the right ventricle. 2. In the papillary muscle of the right ventricle of guinea pigs and cats phenylephrine stimulated α-adrenoceptors. 3. In the left atrium of the rat, phenylephrine stimulated myocardial α-adrenoceptors (pD2: 5.58). Also in this preparation the pA2-values for yohimbine (6.36) and phentolamine (8.21) were different from those found for other α-adrenoceptors in the rat (Van Rossum, 1965). Likewise in strips from the left atrium of the cat myocardial α-adrenoceptors are present. 4. In spontaneously beating right atria of the rat a clear-cut positive chronotropic effect mediated by stimulation of α-adrenoceptors could not be demonstrated although in 6 out of 15 preparations a small positive chronotropic effect became evident. No positive chronotropic effect at all was obtained by stimulation of α-adrenoceptors in the cat right atrium. 5. In ventricular strips as well as in left atria from hypothyroid rats the pD2-value for the α-effect of phenylephrine was increased, in the atrium more than in the ventricle, while the pA2-values for yohimbine and phentolamine were not significantly different from the controls. Under these conditions a distinct positive chronotropic effect mediated by stimulation of α-receptors was found in the spontaneously beating rat atrium. 6. After stimulation of α-adrenoceptors in atria and ventricular strips of normal and propylthiouraciltreated rats, as well as in strips of guinea-pig ventricles or cat atria no elevation of cAMP and cGMP was observed. 7. The concept of a single adrenoceptor convertible from α- to β-type or vice versa was not supported by our experiments. These were carried out at different temperatures on left atria and on ventricular strips of rat hearts using the irreversible α-adrenoceptor blocking agent phenoxybenzamine. 8. The present experiments provide evidence for the existence of α-adrenoceptors in the myocardium of various mammalian species. Their stimulation produces positive inotropic effects without increases in heart rate.
    Materialart: Digitale Medien
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  • 107
    Digitale Medien
    Digitale Medien
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 303 (1978), S. 251-256 
    ISSN: 1432-1912
    Schlagwort(e): Diurnal rhythm ; Motor activity ; Rat ; H 44/68 ; FLA 63 ; Animex
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The effects of the inhibitor of the tyrosine-hydroxylase H 44/68 and the inhibitor of the dopamine-β-hydroxylase FLA 63 on the diurnal variations of the motor activity was studied in male Wistar rats, which were kept under standardized conditions of light and darkness (L:D=12:12h). The motor activity was continuously registered in groups of 5 rats using a two-channel Animex motimeter. During light FLA 63 (40 mg/kg, s.c.) greatly increased motor activity on acute application and during darkness the physiological elevation in motor activity was further but slightly increased. H 44/68 (200 mg/kg, i.p.) also increased motor activity during light, but in contrast to FLA 63 greatly reduced motor activity during darkness. The results indicate that though dopamine and noradrenaline are involved in the regulation of behavioural components, one or the other catecholamine may play a predominant role at different times of the day. Thus, it seems worthwhile to study the effects of drugs separately during light and during darkness.
    Materialart: Digitale Medien
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  • 108
    Digitale Medien
    Digitale Medien
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 303 (1978), S. 257-261 
    ISSN: 1432-1912
    Schlagwort(e): Diurnal rhythm ; Central noradrenaline and dopamine turnover ; H 44/68 ; FLA 63 ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Under controlled conditions of environmental light and darkness of 12:12 h the turnover of dopamine and noradrenaline in brain of male Wistar rats was studied at different times of the day. The turnover was calculated from the decline of the amine concentrations either after inhibition of the tyrosine-hydroxylase with H 44/68 (200 mg/kg, i.p.) or after inhibition of the dopamine-β-hydroxylase with FLA 63 (40 mg/kg s.c.). Whereas the noradrenaline turnover showed only slight but not significant variations within 24 h, the turnover of the central dopamine exhibited significant variations with increased turnover rates in the second half of the light and first half of the dark period. Thus, diurnal variations have to be taken into account when studying the effects of drugs on the turnover of biogenic amines in the central nervous system.
    Materialart: Digitale Medien
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  • 109
    Digitale Medien
    Digitale Medien
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 304 (1978), S. 69-75 
    ISSN: 1432-1912
    Schlagwort(e): Gastric secretion ; Cyclic AMP ; Phosphodiesterase inhibitor ; Rat ; Guinea pig
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The effect of the phosphodiesterase inhibitor 4-(3-cyclopentyloxy-4-methoxyphenyl)-2-pyrrolidone (ZK 62711) on gastric secretion and the cyclic AMP system of the gastric mucosa was studied in rats and guinea pigs. In rats, 0.03–0.3 μmoles/kg ZK 62711 i.v. stimulated acid and pepsin secretion in a dose-dependent manner and 0.03 μmoles/kg i.v. enhanced the effect of histamine. In guinea pigs no reproducible stimulation was found after intravenous injections of ZK 62711. The stimulation of gastric secretion in the rat by 0.3 μmoles/kg ZK 62711 i.v. was not affected by vagotomy but was totally inhibited by 10 μmoles/kg cimetidine i.v. The structurally related phosphodiesterase inhibitor, 4-(3-butoxy-4-methoxybenzyl)-2-imidazolidine (Ro 20-1724), at the dose of 3.3 μmoles/kg i.v. stimulated gastric secretion in anaesthetised rats to a similar extent as 0.3 μmoles/kg ZK 62711 i.v. The content of cyclic AMP in the rat gastric mucosa in vivo was slightly increased by 10 μmoles/kg ZK 62711 i.v, whereas lower doses did not change it. Accumulation of cyclic AMP in the rat gastric mucosa by 50 μmoles/kg histamine i.v. was enhanced by simultaneous injections of 3.3 μmoles/kg ZK 62711 i.v. In rat gastric tissue slices in vitro 1–50 μM ZK 62711 increased the level of cyclic AMP but 100 μM histamine had no effect in the absence or presence of ZK 62711. In gastric mucosal slices of the guinea pig 10 and 50 μM ZK 62711 increased the cyclic AMP content which effect was inhibited by 100 μM cimetidine and enhanced the stimulatory effect of 100 μM histamine on cyclic AMP. The activity of soluble cyclic AMP phosphodiesterase was inhibited by ZK 62711 in the rat (IC50=18 μM) and guinea pig gastric mucosa (IC50=1.5 μM). Adenylate cyclase was not affected in the homogenate of the guinea pig gastric mucosa. The results indicate that the phosphodiesterase inhibitor ZK 62711 which increases cyclic AMP levels in the gastric mucosa in vivo and in vitro, is a potent stimulator of gastric acid secretion.
    Materialart: Digitale Medien
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  • 110
    Digitale Medien
    Digitale Medien
    Springer
    Virchows Archiv 378 (1978), S. 75-90 
    ISSN: 1432-2307
    Schlagwort(e): Morbus Fabry ; Electron microscopy ; Freeze-fracturing ; Heterozygotic women ; Homozygotic men
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Es werden elektronenmikroskopische Beobachtungen zur Lokalisation und zur Feinstruktur der Glykolipideinschlüsse in verschiedenen inneren Organen bei Morbus Fabry berichtet. Die intrazellulÄren und extrazellulÄren Einschlüsse bestehen aus vielschichtig lamellÄren Membransystemen in konzentrischer und exzentrischer sowie in stapeiförmiger paralleler Anordnung. Diese lamellÄre Anordnung ist charakteristisch für flüssigkristalline Phasen von Phospholipid-Wasser-Systemen. Erstmalig werden ultrastrukturelle Befunde an den inneren Organen einer erkrankten Frau mitgeteilt. Demzufolge lassen sich bei heterozygoten Frauen gleiche Glykolipidablagerungen wie bei homozygoten MÄnnern nachweisen. Die Beziehung der Glykolipideinschlüsse zu den Lysosomen wird erörtert.
    Notizen: Summary Electron microscopic findings are reported on the localization and fine structure of glycolipid inclusions in different organs (heart, kidney, lymph nodes, arterial blood vessels, pancreas) in Fabry's disease in a female. The intracellular and extracellular inclusions were made up of multilamellar membraneous systems in concentric, excentric, and parallel arrangement. This fine structure is characteristic of liquid-crystalline phases of phospholipid-water systems. The same type of inclusions are found in the internal organs of heterozygotic women as in homozygotic men. The relationship between the glycolipid inclusions and the lysosomes is discussed.
    Materialart: Digitale Medien
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  • 111
    Digitale Medien
    Digitale Medien
    Springer
    Virchows Archiv 378 (1978), S. 181-197 
    ISSN: 1432-2307
    Schlagwort(e): Axonal swelling ; Spheroid ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Axonal swellings and spheroids in various human diseases were studied by light and electron microscopy. 4 cases of infantile neuroaxonal dystrophy, 2 of degenerative diseases, 2 brain tumors and 3 of cerebrovascular disease were examined. Ultrastructurally most spheroids in infantile neuroaxonal dystrophy consisted of interconnected tubules, stacked membranotubular profiles, alternating layered membranes and accumulations of neurofilaments. Combinations of these four constituents were seen only in infantile neuroaxonal dystrophy. “Torpedos” (fusiform swelling of the axon of a Purkinje cell) consisted exclusively of neurofilaments. Spheroids in case 6 (mental retardation) and 7 (atypical teratoma) consisted of interwoven skeins of neurofilaments and grouped mitochondria. Spheroids in case 8 (demyelination) and 9 (cerebrovascular disease) consisted of packed complex bodies and mitochondria. Spheroids in cases 10 and 11 (cerebrovascular disease) consisted of degenerating organelles only. The morphological differences between cases 9, 10 and 11 probably depends on the severity and timing of the cerebral injury. Most spheroids show similar histological and histochemical properties, but ultrastructural study may give some clue to the origin of the bodies.
    Materialart: Digitale Medien
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  • 112
    ISSN: 1432-2307
    Schlagwort(e): Human parathyroid adenomas ; Electron microscopy ; Parathyroid hormone release ; PTH radioimmunoassay ; Pathophysiology of primary hyperparathyroidism
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Twelve parathyroid chief cell adenomas from patients with primary hyperparathyroidism were incubated in a tissue culture system in the presence of different calcium concentrations and for various time periods. The endocrine response of the tissue was examined electron microscopically and radioimmunologically. After incubation in a medium of low calcium concentration the parathyroid adenomas showed ultrastructural signs of stimulation with proliferation of the hormone-synthesizing organelles. The development of the ultrastructural response could first be observed after four hours and increased up to several days. Radioimmunologically, an increase of the hormone secretion could be demonstrated. Converse results were obtained after incubation of the tumor tissue under suppressive culture conditions. To check for de-novo synthesis of the hormone released the tissue was incubated in a 75Se-methionine-containing medium. This resulted in radioactivity of the secreted parathyroid hormone, indicating de novo synthesis in our culture system. The biological potency of the released hormone was demonstrated by comparison of the PTH out of the medium with the international human MRC standard using two different radioassays.
    Materialart: Digitale Medien
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  • 113
    ISSN: 1432-2307
    Schlagwort(e): Limb bud cultures (mouse) ; Electron microscopy ; Effect of highly sulfated GAG (SP54® and Arteparon®) ; Collagen structure ; Cartilage pattern
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Addition of 1 mg/ml or higher doses of the highly sulfated pentosanpolysulfoester SP54® or the mucopolysaccharidepolysulfoester Arteparon® to limb bud cultures from 11-day-old mouse embryos caused a marked reduction in the growth of the distal parts of the cartilage anlagen. The most striking effect, however, was the change in the collagen structure of the cartilaginous intercellular substance. After more than 0.05 mg/ml SP54® or Arteparon® no collagen filaments were seen but collagen aggregates with an altered cross-striation occurred. They were produced by an antiparallel arrangement of collagen molecules caused by the highly sulfated substances. By immunofluorescence microscopy it was shown that SP54® and Arteparon® did not influence the distribution of the collagen types but only affected the aggregation of collagen type II. From the morphological point of view the production of endogenous PG seemed to be uneffected by SP54® and Arteparon®. The effect of SP54® and Arteparon® was reversible. After removal of these substances characteristic collagen filaments re-formed. The collagen aggregates were decomposed extracellularly or phagocytosed by chondroblasts and decomposed intracellularly.
    Materialart: Digitale Medien
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  • 114
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 186 (1978), S. 121-133 
    ISSN: 1432-0878
    Schlagwort(e): Proximal tubule ; Tight junctions ; Ultrastructure ; Electron microscopy ; Freeze fracturing
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The morphology of tight junctions of the renal proximal tubule was studied comparing the pars convoluta and pars recta of rat, golden hamster, rabbit, cat, dog and tupaia. Though some interspecies variations were observed, the convoluted portions of the proximal tubules revealed quite uniformly very leaky tight junctions with mainly 1–2 strands. Along the whole proximal tubule of the rabbit kidney including the pars recta only minor differences of the zonulae occludentes were found. By contrast, the tight junctions of the pars recta in other species were much more elaborate, especially in cat and tupaia, having up to 6 strands and an overall depth of more than 150 nm. The implications of these findings are discussed with special regard to the functional differences between the pars convoluta and pars recta of the proximal tubule.
    Materialart: Digitale Medien
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  • 115
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 187 (1978), S. 457-472 
    ISSN: 1432-0878
    Schlagwort(e): Ovarian follicles (sheep) ; Theca interna ; Oestrogen ; Androgen ; Capillaries ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The theca interna of non-atretic ovarian follicles from 2.0 mm in diameter up to the stage shortly following ovulation was studied by light and electron microscopy. In follicles 〈3.0mm in diameter, the theca interna consisted of about 8–12 layers of flattened cells, together with many capillaries and small bundles of collagen. Two main forms of cellular differentiation were seen. These were towards either fibroblast-like cells or presumed steroidogenic cells whose cytoplasm contained large amounts of predominantly smooth tubular endoplasmic reticulum, to which some ribosomes were attached. The majority of cells were of relatively undifferentiated or intermediate structure. In larger follicles up to the early stages of oestrus the theca interna cells became larger and less flattened, and cells rich in tubular endoplasmic reticulum became proportionately more numerous. By 18 h after the onset of oestrus the theca interna was oedematous, and many cells possessed pseudopodia. Many cells also contained numerous lipid droplets, but there were no signs of thecal cell degeneration or death. Shortly after ovulation the basal lamina of the membrana granulosa was incomplete, and it became more difficult to distinguish between theca and granulosa layers. Structural heterogeneity, with two major cell types and cells of intermediate structure, was present at all stages. It was concluded that: (1) the theca interna of 2.0–2.9 mm follicles contained many cells whose structure was compatible with a steroidogenic capacity; (2) changes in the differentiated thecal cells up to the early stages of oestrus were quantitative rather than qualitative, and suggestive of an increased steroidogenic capacity; (3) the accumulation of lipid in many cells of the theca interna by 18 h after the onset of oestrus probably reflected a reduction in steroidogenic activity; and (4) there was no evidence of any structural specialization to facilitate the transport of steroids from the theca interna to the membrana granulosa.
    Materialart: Digitale Medien
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  • 116
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 188 (1978), S. 75-82 
    ISSN: 1432-0878
    Schlagwort(e): Drum muscles ; Piranha ; Degenerative changes ; Fine structure ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary In the posterior drum muscle of the piranha structural alterations are frequently observed. Electron microscopic studies revealed a disordering of the myofibrils in these regions, accompanied by conspicuous changes in the mitochondria. As the degree of disorder increases, the mitochondrial cristae initially swell to form vesicles. Eventually the mitochondria become filled with myelin-like lamellar structures, which in many cases coalesce to form a dense outer wall. A striking concentration of lysosomes into localized masses was also characteristic of these regions.
    Materialart: Digitale Medien
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  • 117
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 189 (1978), S. 155-166 
    ISSN: 1432-0878
    Schlagwort(e): Levator ani muscle ; Rat ; Neuromuscular junction ; Castration ; Testosterone effect
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The ultrastructure of the neuromuscular junction (n.m.j.) of the androgen-sensitive levator ani muscle was studied in normal adult male rats, in 8-month-old rats castrated at the age of one month and in castrated rats treated with testosterone propionate (TP). Castration does not result in significant changes of the n.m.j. The density of synaptic vesicles and the postsynaptic junctional folds remain practically normal in spite of marked atrophy of the muscle. TP administration for 7 days results in marked changes in preand postsynaptic structures. There is slow progressive depletion of synaptic vesicles, appearance of cisternae and coated vesicles in axon terminals, and coalescence of coated vesicles with the plasma membrane. Coated vesicles are also found inside Schwann cells and among junctional folds. Dense core vesicles appear both in the axon terminals and in the postsynaptic area. Collateral sprouting of terminal axons with the formation of new immature junctions is observed. After 35 days of TP administration depletion of synaptic vesicles continues. Glycogen β-particles, mostly freely dispersed, occasionally seen in axon terminals 7 days after TP administration, subsequently increase in number. In the endplate zone of the muscle fibre increased protein synthesis is indicated by a rapid increase in ribosomes and irregularly located myofilaments and myofibrils. The appearance of n.m.j. after testosterone administration resembles that described after nerve stimulation; the degree of change is however less pronounced.
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  • 118
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 189 (1978), S. 167-177 
    ISSN: 1432-0878
    Schlagwort(e): Hypodermis ; Rotifer ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The integument of the rotifer Habrotrocha rosa Donner is provided with pores and formed by an extrasyncytial cuticle and a syncytial hypodermis. The hypodermis peripherally contains 3 layers of dense cytoplasm and borders the cuticle by an asymmetric cell membrane. The wall of the pores is stiffened proximally like an annulus. The pores lead into cytoplasmic invaginations which are surrounded by vesicles. Close to and also beneath the condensed cytoplasmic layers microbodies are found, which are interpreted as microperoxisomes. Subhypodermal layers of muscles are connected with the cytoplasm of the hypodermis by desmosome-like structures.
    Materialart: Digitale Medien
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  • 119
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 189 (1978), S. 257-266 
    ISSN: 1432-0878
    Schlagwort(e): Neuromuscular junction ; Hindgut ; Crustacea ; Catecholamine ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The crustacean species Pacifastacus leniusculus and Gammarus pulex were investigated by electron microscopy in a search for possible neuromuscular junctions in the hindgut, which has a rich supply of catecholaminergic fibres. True neuromuscular synapses were found in both species between nerve terminals containing dense-core vesicles (80–110 nm in diam.) and muscle fibres. We suggest that the dense-core vesicle terminals contain a catecholamine, and this is supported by ultrahistochemical tests for monoamines. Two types of junctions are found: one in which the nerve terminal is embedded in the muscle cell (both species) and one in which protrusions from the muscle cell meet nerve terminals (Pacifastacus). Gammarus pulex, which has only circular muscles in the hindgut, has only catecholaminergic innervation, whereas Pacifastacus leniusculus has circular and longitudinal muscles both with at least two types of innervation.
    Materialart: Digitale Medien
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  • 120
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 189 (1978), S. 277-286 
    ISSN: 1432-0878
    Schlagwort(e): Maternal adrenalectomy ; Rat ; Influence on the adrenals of newborn animals ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Maternal adrenalectomy at 7 or 14 days of gestation produced increased cell necrosis within zona reticularis cells on the day of birth and at 24 or 48 h after birth. Small remnants or large portions of adrenocortical cells were present within macrophages. In otherwise normal adrenocortical cells, lipid droplets were incorporated within some mitochondria. Autophagocytosis of single mitochondria was observed within adrenocortical cells. Undoubtedly ultrastructural changes represent stimulation of adrenocortical cells in neonatal rats in response to maternal adrenalectomy.
    Materialart: Digitale Medien
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  • 121
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 191 (1978), S. 449-462 
    ISSN: 1432-0878
    Schlagwort(e): Ileum (Rat) ; Occluding junctions ; Freeze-fracture ; Ultrastructure ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Two kinds of occluding junctions are found between ileal epithelial cells of suckling rats: apical zonulae occludentes (ZO) and fasciae occludentes (FO) which are associated with the lateral plasma membranes of many epithelial cells. In unfixed preparations, glycerol treatment induces the further proliferation of extensive fasciae occludentes. Both kinds of junction have identical structural elements when visualized in freeze fracture replicas, although the arrangement of these elements differs. Zonulae occludentes consist of networks of branching and anastomosing linear ridges or rows of ∼10 nm particles with 20–30 nm spaces between the rows which form narrow belt-like structures around the apical region of adjacent cells. Fasciae occludentes, on the other hand, consist of similar linear ridges or rows of particles but the junction strands are often discontinuous, open ended and only occasionally intersect with each other. Several different fracture planes through the plasma membrane in the region of the occluding junctions have been observed and these provide further evidence that two components, one from each membrane, fused at the level of the extracellular space, form the junction sealing element. Furthermore, we present evidence which indicates a staggered rather than an in-register arrangement of these two components.
    Materialart: Digitale Medien
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  • 122
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 191 (1978), S. 501-506 
    ISSN: 1432-0878
    Schlagwort(e): Neurohypophysis ; Ultrastructure ; Perivascular space ; Hormonerelease ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Neural lobes from rats subjected to neurohypophysial hormone-releasing stimuli were examined electron microscopically following fixation in 4 % tannic acid in 2.5 % glutaraldehyde. This fixation allowed the delineation of the perivascular space in the neural lobe tissue. Measurement of the area of the perivascular space showed that it was significantly increased in the rats subjected to vagal stimulation and intraarterial calcium ions compared to the control rats. The rats which had been subjected to haemorrhage as a hormonereleasing stimulus did not show any significant change in the area of the perivascular space. The significance of these findings in relation to hormone release is discussed.
    Materialart: Digitale Medien
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  • 123
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 191 (1978), S. 507-512 
    ISSN: 1432-0878
    Schlagwort(e): Odontoblasts ; Osteoblasts ; Cementoblasts ; Intercellular attachments ; Electron microscopy (SEM/TEM) ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Osteoblasts of the young rat cranium, and cementoblasts and odontoblasts of young rat molars were prepared by ethanol freeze-fracture prior to critical point drying for scanning electron microscopy (SEM) as well as conventional transmission electron microscopy (TEM) techniques. Critical point drying causes shrinkage which separates the lateral intercellular contacts between neighbours in the same sheet in the case of cementoblasts and osteoblasts, but not those between odontoblasts. These differences are considered to be of functional significance and need to be taken into consideration when formulating theories of calcium influx into the mineralizable matrix of the respective tissues.
    Materialart: Digitale Medien
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  • 124
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 191 (1978), S. 513-523 
    ISSN: 1432-0878
    Schlagwort(e): Median eminence ; Rat ; Freeze-fracture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Nerve terminals in the palisade zone of the rat median eminence were investigated with freeze-fracture electron microscopy. Fracture face P of the specific terminals showed two populations of intramembranous particles (IMP): a large and a small variety. The large IMP-s often formed small irregular clusters. In nerve terminals the total number of both populations of IMP-s was considerably less than that found on P membrane faces of ependymal feet. On fracture face E of the nerve terminals, the number of IMP-s was about a quarter of that seen on fracture face P. On both fracture faces of most terminals a few small round impressions (or elevations respectively) were found which may be interpreted as broken necks of either exo- or endocytotic vesicles. Neither gap nor tight junctions occurred at lateral membranes of the specific axon terminals. Similarly, no membrane specializations were observed with freeze-fracturing on membrane areas adjacent to the basement membrane. The findings are discussed in relation to a possible exocytosis mechanism of the hypothalamic releasing and inhibiting hormones.
    Materialart: Digitale Medien
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  • 125
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 192 (1978), S. 39-51 
    ISSN: 1432-0878
    Schlagwort(e): Prostate ; Rat-Anti-Androgens ; Nuclear alterations ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The fine structure of the nuclei of epithelial cells of the dorsal lobe of the rat prostate were studied after administration of three different antiandrogenic compounds. The nucleolus appears to undergo a progressive disorganisation with partial fragmentation and dispersion of its normal components. Different types of intranuclear inclusions were found. The various alterations observed were often encountered within the same section. This may indicate that the nuclear alterations occur in the same compartment of the cell, and represent a dysfunction of integrated biochemical events occurring within this compartment. The findings support a view that the stimulatory secretory effect of androgens is mediated via a ‘secretory center’, located within the nucleolusassociated chromatin. Within this ‘secretory center’, the initial steps of the secretory process, the binding of the DHT receptor complex to DNA is assumed to occur.
    Materialart: Digitale Medien
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  • 126
    ISSN: 1432-0878
    Schlagwort(e): Taste buds ; Circumvallate papillae ; Colchicine ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary It is believed that differentiation and maintenance of taste buds in vertebrates is dependent on the trophic function of their sensory nerve supply. In the present work colchicine was injected into the circumvallate papilla of the rat. This produced a reversible blockade of neuroplasmic transport and disappearance of taste buds. Colchicine inhibited the further differentiation of bud cells, but apparently did not change the life cycle of the cells present already at the time of injection. It is speculated that the neurotrophic factors in this particular cell system are effective to induce cell differentiation only.
    Materialart: Digitale Medien
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  • 127
    ISSN: 1432-0878
    Schlagwort(e): T-lymphocytes ; Stereological model system ; Free cells ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Menschliche, in Nylonwolle gereinigte T-Lymphozyten aus dem peripheren Blut dienten als repräsentatives Untersuchungsobjekt zur Schaffung eines neuen stereologischen Modellsystems für freie, sphärische Zellen. Dieses System erlaubt, die Zelle und die darin enthaltenen Strukturkomponenten auf ultrastruktureller Ebene quantitativ zu charakterisieren.
    Notizen: Summary T-lymphocytes derived from human peripheral blood and passed through a nylon-wool column, were employed to develop and test a new Stereological model system for free spherical cells, allowing a quantitative characterization of the cell and its components at the ultrastructural level. Electron micrographs were recorded in a hierarchical manner at three different levels of magnification and subjected to point counting procedures. The resulting parameters were expressed in relation to various reference compartments, both absolute and relative. Results indicated that the average volume of a small, non-activated T-lymphocyte was 103.8 μm3, the nuclear volume 47.5 μm3 and the cytoplasmic volume 55.9 μm3. On the average, the cytoplasm contained 30 mitochondria, 0.7 μm3 RER-cisternae, 0.2 μm3 cisternae and vesicles of the Golgi apparatus and about 231,000 free ribosomes (most of them single). The ratio of eu- to heterochromatin volume was 0.5. The design and application of the Stereological model system are discussed with regard to dynamic studies of a variety of free cells, such as macrophages, neutrophilic granulocytes and various lymphocytes.
    Materialart: Digitale Medien
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  • 128
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 186 (1978), S. 535-540 
    ISSN: 1432-0878
    Schlagwort(e): Skeletal muscle ; Satellite cells ; Regeneration ; Electron microscopy ; Autoradiography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Satellite cells were traced autoradiographically during the regeneration of skeletal muscle in young Sprague-Dawley rats. Approximately 31% of the satellite cells in uninjured muscles appeared labelled after three injections of tritiated thymidine; none of the myonuclei were labelled in the same muscles. Four to six days after transplanting the radioactive muscles to non-radioactive littermates, regenerating myotube nuclei in the host appeared labelled. Thus, this study confirms that satellite cells in young rats can differentiate into multinucleated myotubes following muscle injury.
    Materialart: Digitale Medien
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  • 129
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 187 (1978), S. 159-165 
    ISSN: 1432-0878
    Schlagwort(e): Endocrine cells ; Ascidian (Styela clava) ; Gut epithelium ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Ultrastructural studies have shown the presence of two types of granulated endocrine cell in the gut of Styela clava. Type I, which occurs in the stomach and intestine contains small irregular granules, each with a distinct halo. Type II, found only in the oesophagus contains larger rounded granules, often with little or no halo. The characteristics of these two cell types are compared with those of endocrine cells found in the digestive tracts of other protochordates and discussed with special reference to the evolution of gastrointestinal endocrine cells in vertebrates.
    Materialart: Digitale Medien
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  • 130
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 187 (1978), S. 439-448 
    ISSN: 1432-0878
    Schlagwort(e): Urinary bladder epithelium (Rat) ; Gap junctions ; Tight junctions ; Electron microscopy ; Freeze-fracturing
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The junctional connections between the cells of the urinary bladder epithelium in rat have been studied by freeze-fracturing. Tight junctions and desmosomes are known as structural features of the epithelium. In addition, gap junctions (nexus) have been found to connect the epithelial cells in an irregular distribution pattern. The junction size ranges from few assembled particles up to plaques with irregular forms. This may indicate that the gap junctions are mobile structures. The functional significance of the junctions in comparison with electrophysiological data is discussed.
    Materialart: Digitale Medien
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  • 131
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 188 (1978), S. 345-359 
    ISSN: 1432-0878
    Schlagwort(e): Hippocampal subfields ; Rat ; Volumes ; Timm stain
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The absolute volumes of the hippocampal and subicular cortical layers in the rat were determined. The boundaries of the various layers were defined on series of sections made through the entire hippocampal region of five rats and stained according to the Timm sulfide silver technique. Coordinates representing the boundaries of the layers on selected sections were fed into a mini-computer programmed to calculate the volume of the layers from the areas of the profiles and the distances between the sections. The distribution of the layers indicates that they constitute the same proportion of the volume of the dorsal and ventral divisions of the hippocampal region, with the exception of the structures lying in regio inferior and regio superior. Although the combined regio superior and regio inferior components of the layers of Ammon's horn occupy the same percentage of the volume of the dorsal and ventral hippocampal regions, the regio superior components occupy a larger percentage of Ammon's horn in the dorsal region than they do in the ventral region. The inter-animal variations in the volumes of the various layers indicate that it is possible to describe quantitatively the subdivisions of the hippocampal region with a precision that is compatible with comparative studies.
    Materialart: Digitale Medien
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  • 132
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 188 (1978), S. 491-496 
    ISSN: 1432-0878
    Schlagwort(e): Castration ; LH-cells ; Rat ; Development ; Sex-steroids
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The effects of sex-steroids on the LH-cell development in neonatal rats were studied. The cells were stained immunohistochemically by applying anti-HCG serum. On the second day after birth some of the animals of both sexes were gonadectomized and simultaneously injected with testosterone or estradiol (50 or 200 μg). The remaining animals were either gonadectomized or injected with either one of the sex-steroids. The LH-cell numbers in each group were determined on the 12th day of age from serially cut histological sections of the pituitary. In castrated males the number of LH-cells was about twice that of the intact animals. In the so-called sex-zone, LH-cells tended to be hypertrophied in castrates. These alterations in the appearance of LH-cells did not occur after ovariectomy. In gonadectomized animals injected with sexsteroids (200 μg), the cells were markedly reduced in number and size, both in males and females. Testosterone injection (50 μg) into intact newborn animals also suppressed the numerical development of LH-cells, especially in females. These alterations were particularly evident in the sex-zone in both sexes. Thus the present findings show that sex-steroids may be involved in sexual differences in morphological development of LH-cells in newborn rats.
    Materialart: Digitale Medien
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  • 133
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 188 (1978), S. 497-508 
    ISSN: 1432-0878
    Schlagwort(e): Fertilization ; Domestic fowl ; Acrosome reaction ; Vitelline membrane ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The developing outer layer of the vitelline membrane of the ovum in the posterior part of the infundibulum of the domestic fowl contains many spermatozoa in nearly parallel orientation with its inner layer. When the acrosomal region of a spermatozoon approaches or contacts the inner layer, promptly undergoes the acrosome reaction. The outer acrosomal membrane and overlying plasma membrane fuse together and the apical region of the acrosome opens, so that the acrosomal contents are released. Meanwhile the spermatozoon remains a time in contact with the surface of the inner layer, and the network of the inner layer just under the tip of the sperm head begins to be dissolved. This dissolution extends downward forming a tunnel, approximately 9 μm in diameter. The spermatozoon then passes through the inner layer obliquely via the central region of the tunnel and arrives at the perivitelline space.
    Materialart: Digitale Medien
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  • 134
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 189 (1978), S. 375-388 
    ISSN: 1432-0878
    Schlagwort(e): Lateral line organ ; Pit organ ; Sea eel (Conger myriaster) ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The fine structure of the pit organ of the sea eel has been studied by means of electron microscopy. The sensory epithelium of the pit organ consists of sensory cells and supporting cells. The apical surface of the sensory cell is studded with sensory hairs consisting of a kinocilium and stereocilia. The sensory cells are divided into two groups. In one, the kinocilium points dorsally and in the other the kinocilium points ventrally. The total number of sensory cells in one pit organ is about 100, and the ratio of cells with opposite polarity is about 1∶1. On the basis of these structural features, the pit organ is considered to be a mechano-receptor sensitive to the movement of liquid in a dorso-ventral direction. It may also serve as an ion receptor, sensitive to environmental ion concentration. Efferent nerve terminals make rare synaptic contacts on the afferent nerve fiber.
    Materialart: Digitale Medien
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  • 135
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 189 (1978), S. 403-407 
    ISSN: 1432-0878
    Schlagwort(e): Adrenal gland ; Rat ; Vinblastine ; Corticosterone ; Exocytosis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Vinblastine treatment blocks corticosterone release from rat adrenal zona fasciculata without impairing hormone synthesis, and induces the formation of acid phosphatase-positive granular clumps at the juxta-sinusoidal pole of the cells. Autoradiography shows that ACTH administration to vinblastine-treated animals mobilizes the 3H-cholesterol stored in the lipid droplets and leads to a noticeable labelling of the granular clumps. The possible significance of these granules is discussed.
    Materialart: Digitale Medien
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  • 136
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 189 (1978), S. 515-523 
    ISSN: 1432-0878
    Schlagwort(e): Protonephridium ; Rotifer ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The excretory system of Habrotrocha rosa consists of two protonephridia. From each of them seven tubules lead to a terminal organ, also called cyrtocyte. Its weir basket contains structures which resemble ciliary rootlets. The lumen of the excretory system is bordered by a syncytial layer of cytoplasm. Cells are only found in the upper region of the trunk, where the channel is twisted several times.
    Materialart: Digitale Medien
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  • 137
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 189 (1978), S. 525-535 
    ISSN: 1432-0878
    Schlagwort(e): Alimentary system ; Rotifer ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The alimentary system of Habrotrocha rosa is composed of the alimentary channel, five digestive glands and another gland which is in close relation to the intestinal syncytium. After the present investigation, the alimentary channel can be divided into sections which clearly differ from each other, these are: oral cavity, pharynx, oesophagus, mastax, stomach-hose, syncytium of intestine, and terminal intestine.
    Materialart: Digitale Medien
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  • 138
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 188 (1978), S. 11-18 
    ISSN: 1432-0878
    Schlagwort(e): Purkinje fibers (Ox, goat) ; Axons ; Nerve endings ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The moderator band in the heart of the ox and goat contains bundles of Purkinje fibers and nerve fibers separated by connective tissue. The axons are mostly unmyelinated and embedded in the cytoplasm of Schwann cells. Small bundles of axons run close to the Purkinje fibers. The axons dilate into varicosities 0.5 to 1.6 μ in diameter (mean 0.95 μ), containing three types of vesicles: 1) agranular vesicles with a diameter of 400–500 Å, 2) large dense-cored vesicles with a diameter of 800–1200 Å, 3) small dense-cored vesicles with a diameter of 500 Å. Most varicosities contain agranular vesicles together with a few large dense-cored vesicles. The gap between the varicosities and the nearest Purkinje fiber is unusually wide and normally varies between 0.3 μ and 0.8 μ. No intimate nerve-Purkinje fiber contacts, with a cleft of 200 Å, were observed.
    Materialart: Digitale Medien
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  • 139
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 188 (1978), S. 265-272 
    ISSN: 1432-0878
    Schlagwort(e): Muscles ; T-system ; Fish ; Frog ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary In “white” muscle fibres of a teleost fish T-tubule openings may occur regularly at all Z-disc levels between adjacent peripheral myofibrils, the T-tubule openings thus occurring at a density of ca. 0.9 μm-2. In frog “white” fibres, T-tubule openings are infrequently seen in material fixed like the fish material. In material prepared according to the albumin method of Gray (1975, 1976 a, b) which renders the muscle fibres swollen, straight tubules or sometimes chains of vesicles instead are seen opening at the sarcolemmal surface. Such tubules occur at a higher density than expected from experiments with local activation of contraction. Lability and dynamics within the T-system normally and during fixation are discussed.
    Materialart: Digitale Medien
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  • 140
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 188 (1978), S. 285-297 
    ISSN: 1432-0878
    Schlagwort(e): Pineal gland ; Rat ; Organ culture ; Indole metabolism ; Ultrastructural morphology
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary In vitro indole metabolism and ultrastructural morphology of the pineal gland of male rats were examined. A comparison of the effect of norepinephrine stimulation on indole synthesis in whole cultured glands and preparations of dispersed pineal cells is discussed. Our studies on the performance of dispersed cells during the first 24 h after preparation indicate a strong dependence of pineal cells upon physical attachment to the culture dish and probably also on cell-to-cell contact.
    Materialart: Digitale Medien
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  • 141
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 191 (1978), S. 405-419 
    ISSN: 1432-0878
    Schlagwort(e): Subfornical organ ; Japanese quail, Coturnix coturnix japonica ; Monoaminergic innervation ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The parenchyma of the subfornical organ (SFO) of the Japanese quail was studied by light and electron microscopy. The SFO consists of ependymal, intermediate, and basal (perimeningeal) layers. In the intermediate layer, neurons, glial cells, and their processes are found. Axons containing dense core granules approximately 80 nm in diameter are numerous, some of which make synaptic contact with the neuronal perikarya or dendrites. Synaptic vesicles in some axons contain a dense dot in the interior after treatment with 5-hydroxydopamine. The activity of the SFO, which is probably concerned with elicitation of drinking by angiotensin II, may be regulated at least partly by afferent monoaminergic axons. Capillaries with a non-fenestrated endothelium are occasionally found in the parenchyma. The basal layer is occupied by glial processes abutting on the digitating layer of perivascular connective tissue of meningeal vessels. The endothelium of these vessels is occasionally fenestrated. Trypan blue injected systemically accumulated in the SFO, but not in the deeper areas of the brain. The absence of a blood-brain barrier is suggested in the SFO.
    Materialart: Digitale Medien
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  • 142
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 192 (1978), S. 267-276 
    ISSN: 1432-0878
    Schlagwort(e): Endocrine glands ; Mouse small intestine ; Mouse embryo ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The duodenum and ileum of 15 to 18-day old Swiss ICR mouse embryos were studied with the electron microscope to follow the differentiation of endocrine cells. Endocrine cells were classified on purely morphological characteristics. EC cells appeared at 16 days of gestation in both segments. At the same stage G cells were seen in the duodenum and K cells in the ileum. ECL, and S cells were identified in the duodenum at 17 days. Finally, D cells were seen at 18 days of gestation in the duodenum and ileum. With the electron microscope, endocrine cells were not identified in the small intestine of the mouse before the formation of villi.
    Materialart: Digitale Medien
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  • 143
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 192 (1978), S. 285-297 
    ISSN: 1432-0878
    Schlagwort(e): Intestinal epithelium ; Rat ; Kinetics ; Autonomic denervation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The effect of autonomic denervation upon the kinetics of the ileal epithelium of rats was studied by tracing 3H-thymidine labelled nuclei and counting mitotic figures and goblet cells. Counts of labelled nuclei and goblet cells provided information about cell migration along the intestinal epithelium. The mitotic index and turnover time of this population were calculated from the mitotic figures counts. Comparing denervated animals with sham operated controls, it was possible to conclude that autonomic denervation, either sympathectomy or parasympathectomy results in a decrease in mitotic activity. As a result of lower mitotic activity in the crypts, the turnover time increases and there is a delay in the migration of cells from the crypts towards the villi. Sympathectomy causes an early short-lived effect upon the kinetics of the crypt cell population, since after 27 h there is a tendency to normality. Parasympathectomy produces a slower but continuous decline in mitotic activity.
    Materialart: Digitale Medien
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  • 144
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 188 (1978), S. 509-520 
    ISSN: 1432-0878
    Schlagwort(e): Cerebellar cortex (Cat) ; Postnatal development ; Myelination of efferent and afferent fiber systems ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The myelination of the cerebellar cortex of the cat was investigated in 61 cats aged from 3 hrs post partum to two and a half years. The first myelinated fibers appear at the time of birth in the central medullary ray. Before the onset of myelination, all fibers reach a critical diameter of about 1 μm. About the 14th day of life the number of oligodendrocytes in the prospective white matter increases markedly. Thereafter, the oligodendrocytes invade the inner granular layer. It therefore seems that the myelination of the cerebellar cortex proceeds from the central medullary ray towards the granular layer. At the 60th day of postnatal life, most of the afferent and efferent fiber systems are myelinated. These findings are discussed in relation to the development of function and the maturation of the electrical activity of the cerebellar circuit.
    Materialart: Digitale Medien
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  • 145
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 189 (1978), S. 1-18 
    ISSN: 1432-0878
    Schlagwort(e): Kidney medulla ; Rat, rabbit, gerbil ; Interstitial cells ; Lipid droplets ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The inner zone of the renal medulla of rats, gerbils, and rabbits was investigated to determine whether or not there are any characteristic ultrastructural differences between the interstitial cells of these species. The effects on the interstitial cells of water deprivation and water loading were also investigated. In all three species, the Type 1 interstitial cells, the lipid containing cells, were abundant and their distribution and topographical relations as well as their general ultrastructure were similar. The previously reported significantly higher frequency in desert rats could not be confirmed. Although the lipid droplets of the interstitial cells were smaller in gerbils and rabbits when compared to rats, their fine structure was similar. Their electron dense outer zone was sometimes associated with a granular material and/or a lamellar material with a periodicity of about 40 Å resembling phospholipid “myelin figures”. Water-loaded rats showed a considerable increase in the number of lipid droplets when compared to dehydrated or untreated animals. In contrast, the interstitial cells of waterloaded gerbils and rabbits were depleted of lipid droplets.
    Materialart: Digitale Medien
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  • 146
    ISSN: 1439-6327
    Schlagwort(e): Exercise ; Altitude ; Left ventricular work ; Myocardial blood flow ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Total hemodynamic values and left ventricular blood flow were studied using Sapirstein's method of 86Rb uptake in female rats 24 h after a last exposure to high altitude. A simulated altitude of 1350 m was used, initial exposure being for 30 min, gradually increased by 30 min daily up to 330 min daily for 5 days a week; the total number of exposures was 32. In another animal group the hypobaric exposure was combined with swimming in water at 37
    Materialart: Digitale Medien
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  • 147
    Digitale Medien
    Digitale Medien
    Springer
    Plant systematics and evolution 129 (1978), S. 135-142 
    ISSN: 1615-6110
    Schlagwort(e): Algae ; Chrysophyceae ; Chrysosphaerella solitaria ; Electron microscopy ; phytoplankton
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A new unicellular species of the genusChrysosphaerella (Chrysophyceae) was found in fresh-water ponds in Switzerland, Japan, and the U.S.A. It is described asC. solitaria. The genus is divided into two subgenera:Chrysosphaerella, comprising the colonial species, andPseudochrysosphaerella, the unicellular ones.
    Materialart: Digitale Medien
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  • 148
    Digitale Medien
    Digitale Medien
    Springer
    Environmental biology of fishes 3 (1978), S. 185-191 
    ISSN: 1573-5133
    Schlagwort(e): Euthynnus affinis ; Electron microscopy ; Kawakawa tuna ; Red fibres ; White fibres ; Muscle size ; Activity ; Thermogenesis ; Thermal inertia
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Synopsis An electron microscopic study of the red and white muscle fibres in the trunk musculature of the Kawakawa tuna (Euthynnus affinis) was carried out with a view to correlating their structure with metabolic adaptation. The red fibres which are considerably smaller in diameter (34.58 μm ± 6.16 S.D.) are characterized by their high content of myoglobin, mitochondria, lipid droplets and glycogen granules. The white fibres which are relatively larger in diameter (66.03 μm ± 11.59 S.D.) are characterized by their lack of myoglobin, low mitochondria) density, high content of glycogen granules and the conspicuous absence of lipid droplets. The characteristics in fine structure of the two fibre types are discussed in the light of their metabolic adaptation, the red fibres as being adapted for long term cruising movement utilizing lipid as the main source of energy and the white fibres for short bursts of activity metabolizing glycogen as the chief fuel. The tuna, with the acquisition of the counter-current heat exchange system which provides for the retention of the heat generated from high substrate oxidation in the red muscle and an efficient respiratory system, it is postulated, is well adapted for high speed sustained swimming.
    Materialart: Digitale Medien
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  • 149
    Digitale Medien
    Digitale Medien
    Springer
    European archives of oto-rhino-laryngology and head & neck 220 (1978), S. 201-212 
    ISSN: 1434-4726
    Schlagwort(e): Plica vocalis ; Epithelial surface ; Rat ; Extrapulmonary airway epithelium ; Scanning electron microscopy ; Stimmbänder ; Epitheliale Oberfläche ; Ratte ; Larynxepithel ; Rasterelektronenmikroskopie
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Das Stimmbandepithel ausgewachsener männlicher Albinoratten wird rasterelektronenmikroskopisch untersucht. Seine Oberflächenstruktur wird mit jener des Epithels auf der Plica ventricularis und im Recessus ventricularis verglichen. Charakteristischerweise zeigen die Zellen im Epithel über den Stimmbändern einen dichten, lückenlosen Besatz mit Mikrovilli. Die Übergänge des Stimmbandepithels in die benachbarten Larynxabschnitte wird dokumentiert. Besondere Aufmerksamkeit wird dem Auftreten von Mikroleisten auf den apikalen Zellpolen im Larynxepithel gewidmet, die bisher als charakteristische Struktur für das Stimmbandepithel gewertet wurden.
    Notizen: Summary The epithelial surface of the Plica vocalis in adult male rat is studied by scanning electron microscopy. It's structure is compared with that of the plica and of the recessus ventricularis. The transition of the epithelium in the plica vocalis to the epithelium of the joining parts of the larynx is documented. Special attention is paid to the occurrence of microridges at the apical poles of epithelial cells in the larynx. Up to now microridge cells have been said to be characteristic for the plica vocalis.
    Materialart: Digitale Medien
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  • 150
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 13 (1978), S. 391-410 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A model consisting of a harmonic oscillator well and a repulsive inverse square potential, coupled by a delta function, is solved. We find the S-function for this case and study its poles as a function of the coupling strength. These poles show how the harmonic levels shift and broaden as the two potential curves couple and predissociation occurs. A “new state” is found when the energy threshold is just below the first excited state of the harmonic oscillator.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
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  • 151
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 13 (1978), S. 455-456 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 152
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 13 (1978), S. 499-507 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The thermodynamics of the DNA helix-coil transition is studied, starting from the thermodynamical potential difference between the states helix and coil; this potential difference is understood as the difference in free energies. With only three parameters obtained from experimental data different quantities of the T2 phage DNA molecule are calculated. It is observed that the phase transition is of second order.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 153
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 154
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 13 (1978) 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 155
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 13 (1978), S. 605-617 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A very efficient and exact method for calculating the long-range effects in polymers is reported. The method is based on the multipole expansion within the Fock operator, and exact summation up to infinity is carried out. Only a small number of one-electron integrals have to be considered, while in the traditional approach one has to compute a large number of two-electron integrals. Results on LiH model polymer have been obtained with a remarkable accuracy within a negligible computing time.
    Zusätzliches Material: 3 Tab.
    Materialart: Digitale Medien
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  • 156
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 13 (1978), S. 641-677 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Let E(R) be a potential-energy function for a neutral or ionic diatom in the Born-Oppenheimer approximation. Then the approximation of E(R) for 0 〈 R 〈 ∞ starting from finite and typically small sets of given information is considered. The approach is based on the fact that the scaled potential curves F(R) = R2E(R) derive from an eigenvalue problem which depends linearly on R. The nature of the curves F(R) is examined in detail. The results include the discovery of various approximants, some of which display rigorous bounding properties and others, closely related, whose behavior with respect to the approximated function appears to be predictable.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 157
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 13 (1978), S. 679-692 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: In an attempt to rationalize and improve an approximate exchange perturbation scheme related to the model of Murrell et al., more accurate approximations are introduced eliminating the use of empirical parameters. The total interaction energy has been evaluated as the sum of additive electrostatic, exchange, charge transfer, and dispersion contributions. It is proven that the assumption of intramolecular ZDO approximation is equivalent to the use of the Mulliken formula for intermolecular intergrals in the region of small overlap. It is also shown that the use of exact two-center resonance integrals and atomic multipole expansion leads to a substantial improvement of results. The method has been applied to calculation of interaction energies of some model hydrogen-bonded complexes of water, hydrogen fluoride, adenine, thymine, guanine, and cytosine using approximate all-valence wave functions.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 158
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 13 (1978), S. 769-775 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The problem considered is that of selecting the finite orbital basis which will minimize the energy in a given size CI calculation. (1) A one-body operator is defined which has as eigenfunctions the desired optimal basis. The operator is defined in terms of the basis which leads to a self-consistency problem of Hartree-Fock type. (2) A method of successive orbital rotations is defined which is shown to have desirable convergence properties.
    Zusätzliches Material: 1 Ill.
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  • 159
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 13 (1978), S. 160-160 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 160
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 13 (1978), S. 199-206 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: It is shown that application of the orthonormality-constrained variation method to the absolute squares of three kinds of overlap integrals leads to eigenvalue equations and of which the eigenvectors belonging to maximum (minimum) eigenvalues are the maximum (minimum) overlap, localized, and hybrid orbitals. In the eigenvalue equations, coupling operators similar to those used in SCF theory are found to occur. Connection of the maximum orbitals to a many-shell model, a simple MO theory, and Löwdin's orthonormalization is also discussed.
    Materialart: Digitale Medien
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  • 161
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 13 (1978), S. 235-238 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Electric polarizabilities are calculated by solving the first- and second-order perturbation equations through a variational procedure. Satisfactory numerical results are obtained for a number of molecules using the CNDO approximation with an extended basis set.
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
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  • 162
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 14 (1978), S. 209-212 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The mathematical basis for the Ruedenberg's and Mulliken's approximations is given in a general framework.
    Materialart: Digitale Medien
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  • 163
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 14 (1978), S. 239-243 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The ab initio Hartree-Fock crystal orbital method is used for the calculation of the energy band structure of a one-dimensional model of (SN)x. Two energy band structures are described corresponding to the self-consistent spin density wave (SDW) and the self-consistent charge density wave (CDW) solution, respectively.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 164
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 13 (1978), S. 367-374 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The multiple scattering molecular orbital method, with different choices of sphere radii and local exchange, is applied to the cluster CrF63-. The orbital energies are almost always in the same order but uniformly moved up or down the energy scale depending on which parameters are used. Charge densities are only slightly dependent on the parameters. A method to avoid interaction with Rydberg-like states is suggested.
    Zusätzliches Material: 1 Ill.
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  • 165
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 13 (1978), S. 411-428 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A general quantum-mechanical description of molecular transport across biological membranes has been developed. The one-dimensional Schrödinger equation for the motion of ions and molecules across the biological membrane has been solved using reasonable potential barriers. Two types of potential profiles for such transports have been considered: a flat barrier proposed by Hall et al. for lipids and an oscillatory potential proposed by Lauger for lipids and by us in this paper for intrinsic proteins. The general behavior of the transmission coefficient as a function of energy and the variation of the permeability as a function of structural changes in the membrane have been discussed. Finally, the importance and areas of applicability of such a theory have been pointed out.
    Zusätzliches Material: 11 Ill.
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  • 166
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 14 (1978), S. III 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 167
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 13 (1978), S. 483-497 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Le découpage de la densité électronique totale dans une molécule, en contributions provenant des diverses orbitales, permet de définir des régions orbitalaires de caractère conventionnel dont la charge totale est égale à la somme des populations de Mulliken des orbitales constituant les diverses régions. La fluctuation relative de la charge de ces régions s'exprime simplement en fonction des populations de Mulliken et des indices de liaisons. Cette analyse de la densité dans des molécules variées (saturées ou conjuguées) permet de retrouver les liaisons chimiques de la graphie classique comme correspondant à des régions orbitalaires de charge voisine de 2 et présentant une fluctuation relative fiable (≤0, 10). Compte tenu du caractère dynamique que contient la notion de liaison, les résultats obtenus trouveraient une interprétation simple dans l'espace des phases. L'impuissance de la Mécanique quantique de donner une description dans cet espace expliquerait l'impossibilité de déduire de calculs quantiques la notion měme de liaison chimique.
    Zusätzliches Material: 1 Tab.
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  • 168
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The dependence of the molecular electrostatic potential V on the method of calculating the wave function and on the basis set has been examined for three electronic states of H2CO. The calculations analyzed here refer to two different basis sets: a minimal set and a split-valence shell set, both supplemented with diffuse p orbitals. The methods of calculation include the SCF procedure (for the ground state), CI procedures of increasing complexity, which practically reach their asymptotic limits, and, for the excited states, simpler methods (rigid orbital excitation, complete CI of single excitations, electron-hole potential methods). It appears that in the ground state the two bases give equivalent descriptions of V when the CI process reaches the asymptotic limit and that the SCF descriptions approximate fairly well the more accurate ones. For the 3A1(π → π*) state the conclusions on the two basis sets are similar and, in addition, it is shown that a simple method (EHP) gives an approximation of V that reproduces the essential features of the complete CI calculations. The inadequacy of both basis sets for the representation of the 1A1(π → π*) state turns out to be evident. A discussion is presented concerning the possibility of adopting the calculation of V as an auxiliary tool to compare the accuracy of different descriptions of the same electronic state.
    Zusätzliches Material: 10 Ill.
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  • 169
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 13 (1978), S. 597-603 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A multiple scattering method is used for determining the total cross section of elastic electron scattering for the SF6 molecule in the energy range 10-60 eV.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 170
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    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 13 (1978), S. 627-634 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The approximate way of calculating the supermolecular density applied in the Gordon and Kim method is examined. If the supermolecular density is approximated by a sum of the subsystem densities, the results for the individual contributions to the interaction energy (kinetic, potential) appear to be incorrect as compared with those obtained in the SCF approach and in first-order perturbation theory. However, a considerable improvement of the statistical results is obtained if a more suitably calculated supermolecular density is used. All calculations have been carried out for the He2 system.
    Zusätzliches Material: 4 Tab.
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  • 171
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    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 13 (1978), S. 693-695 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 172
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    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 13 (1978), S. 719-730 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A survey of our recent work on algebraic structures and reduced-density-matrix theory is presented. Our approach leads to a method of classifying reduced density matrices and generalizes the notion of open and closed shells in many-body theory.
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  • 173
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    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 13 (1978), S. 777-790 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Optimal orbital exponents are approximated by minimization of the reduced Hamiltonian orbital ground state energy. They appear to be as good as and are obtained at much less expense than the values derived by the usual SCF exponent optimization scheme. Partitioning of energy into 0-energy, 1-energy, and 2-energy (Absar and Coleman, Int. J. Quant. Chem. 10, 319 (1976); Chem. Phys. Lett. 39, 60 (1976)) is used to study the variation in the electronic energy surface upon variation of orbital exponents. The 1-energy operator, the natural orbitals of which are the reduced Hamiltonian orbitals, is compared with the SCF operator.
    Zusätzliches Material: 3 Ill.
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  • 174
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    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 13 (1978), S. 791-799 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Representable reference density matrices are applied to the graphical description of the Coulomb hole in a CI wave function for the first excited 1S state of the four-electron boron ion B+. It is found that a satisfactory picture of the Coulomb hole emerges only when the symmetry of the correlated wave function is recognized in the construction of the reference full-density matrix.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 175
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Ab initio LCAO SCF MO calculations are carried out on planar Co-porphine with a basis set of roughly double zeta quality for Co and N and of single zeta quality for C and H. The net charge on Co and N and the overlap population between them are 1.78, -0.57, and 0.06, respectively, in the 2A1g, state, which is known to be the ground state by experiment. The bonding in this complex is thus largely ionic. The first and second calculated ionization potentials are 6.51 and 6.77 eV, respectively, and are in reasonable agreement with the observed ionization potentials of 6.44 and 6.62 eV for Ni-tetraphenylporphine. CI calculations within the framework of the ligand field theory are also performed. The calculated order of the five lowest states is 4B2g ≈ 4Eg, 4A2g, 2A1g, 4Eg from below and is not in agreement with the semiempirical order of 2A1g ≈ 4B2G, 4A2g, 2Eg, 4Eg determined by Lin.
    Zusätzliches Material: 4 Ill.
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  • 176
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    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 14 (1978), S. 191-207 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The properties of biorthonormal sets and their use in quantum chemistry are discussed. A theoretical description of the interaction between one-electron atoms is presented. The description is based on a single orbital per electron but is otherwise complete. Structurally simple relations are derived for the energy of interaction, and theoretical justifications for the London equation and the diatomics-in-molecules method are presented. Some comments on the stability of spin-coupling-optimized methods are made.
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  • 177
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    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 14 (1978), S. 181-190 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A SCF method using localized molecular orbitals which are built up on hybrid atomic orbitals is proposed to obtain the charges in infinite crystals. Hybrid orbitals are built up on a minimal STO basis set. The formalism has been adapted in order to take into account the periodicity of the system and its infinite size by introducing the Madelung constant. The total energy is given by an infinite sum of terms each corresponding to the energy of a bond in the crystal field. Minimizing this bond energy with respect to eigenvectors it is straightforward to obtain the electronic charges, whence the polarity, i.e., the ionicity, of bonds. In this first paper, we study and discuss the polarity of bonds in zincblende and wurtzite-type compounds built up on first and second row elements. Our values are coherent between themselves and in agreement with other authors' results. The connection with electronegativity and polarizability is discussed.
    Zusätzliches Material: 1 Tab.
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  • 178
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    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 14 (1978), S. 231-237 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A procedure to improve trial wave functions is given in terms of the off-diagonal hypervirial theorem. This procedure is closely related to the optimum scaling method which is valid for the diagonal hypervirial theorem. The second excited state of the one-dimensional oscillator model is employed as an example, and improved wave functions and expectation values are calculated. The results are compared with previous values based on the diagonal hypervirial theorem.
    Zusätzliches Material: 1 Ill.
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  • 179
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 14 (1978), S. 289-297 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: In this paper, MC-SCF and CI methods have been explored for the calculation of ground- and excited-state energies of some aromatic heterocycles in the PPP framework. A new algorithm for solving the orbital equations in MC-SCF theory has been suggested and its performance has been compared with the conventional gradient optimization technique. Energies of first few transitions have been calculated and compared with rather extensive CI results.
    Zusätzliches Material: 1 Ill.
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  • 180
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 14 (1978), S. 319-327 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: An analytical potential function for the pairwise interaction of methane and water is reported. The function is representative of 225 ab initio quantum-mechanical calculations of the intermolecular interaction using 6-31G self-consistent-field molecular-orbital theory. The statistical parameters of the curve fitting are given and isoenergy contour maps of the interaction energy are presented and discussed.
    Zusätzliches Material: 3 Ill.
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  • 181
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 14 (1978), S. 341-341 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 182
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 14 (1978), S. 353-359 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: We review the methods and some applications of complex scaling transformation as well as some goals that now seem accessible using this technique in atomic and molecular physics.
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  • 183
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 14 (1978), S. 393-418 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The theories of the dilatation, r → r eiθ, and translation, x → x + iq, transformations as related to the Stark problem are reviewed, and new results obtained. Results for the hydrogen atom n = 1 and n = 2 levels and the 1P0, 2s2p H- shape resonance in dc fields are presented, and the extension to the ac Stark effect made. Spectral estimates are made using the technique of the numerical range and via discussion of several model problems, using both coordinate rotation and coordinate translation.
    Zusätzliches Material: 16 Ill.
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  • 184
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 14 (1978), S. 457-513 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The theory of this paper deals with certain aspects of the formal properties of atomic and molecular highly excited nonstationary states and the problem of calculating their wave functions, energies, and widths. The conceptual framework is a decay theory based on the consistent definition and calculation of the t = 0 localized state, |Ψ. Given this framework, the following topics are treated: (a) The variational calculation of Ψ0 and E0 using a previously published theory that generalized the projection operator approach to many-electron systems. (b) The exact definition of the resonance energy. (c) The possibility of bound states in the continuum. (d) The relation of Ψ0 to the resonance (Gamow) function Ψ and of the Hamiltonian to the rotated Hamiltonian H(θ) based on the notion of perturbation of boundary conditions in the asymptotic region. (e) The variational calculation of real and complex energies employing matrix elements of H and H2 with square-integrable and resonance functions. (f) The mathematical structure of the time evolution of |Ψ0〉 and the possibility of observing nonexponential decays in certain autoionizing states that are very close to the ionization threshold. (g) A many-body theory of atomic and molecular resonances that employs the coordinate rotation method.
    Zusätzliches Material: 7 Ill.
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  • 185
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 14 (1978), S. 623-634 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The theoretical justification of the model potential method is studied in some detail. The correct equations within the framework of Roothaan's open-shell scheme are derived and the approximations necessary to get a workable method are discussed. Analysis of the local part of the model potential suggests a new analytical form for it. The new expression is theoretically more consistent than the original one, and it can be determined in a more straightforward way. A basis set approximation, which is particularly suitable for approximate evaluation of two-electron integrals when only valence orbitals are involved, is discussed and tested with encouraging results. The ideas are tested on the Fe and I atoms.
    Zusätzliches Material: 7 Tab.
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  • 186
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 14 (1978), S. 649-657 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The polarization model, originally developed to describe deformable and ionizable water molecules, has been extended to hydrogen fluoride. Since electronic polarization is explicitly included, the interaction energy in aggregates of molecules (with or without ions) is nonadditive. The model properly describes the structure of (HF)2, including off-axis bending of the proton acceptor molecule. Calculations are presented to illustrate elementary gas-phase reactions involving proton transfer between HF and F-, and H2F+ and F-.
    Zusätzliches Material: 3 Ill.
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  • 187
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    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 14 (1978), S. 635-639 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The concept of a universal basis set for electronic structure calculation is illustrated by presenting results obtained when basis sets are transferred from one atom to another. A single Slater-orbital basis set, consisting of nine 1s and six 2p functions, produces Hartree-Fock total energies and orbital energies in good agreement with the most accurate calculations of these energies obtained using different basis sets individually optimized for each atom. Transferability of integrals is a natural consequence of the use of the same basis set for each atom in a molecule.
    Zusätzliches Material: 3 Tab.
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  • 188
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    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 14 (1978), S. 641-648 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The possible uses of the half-projected Hartree-Fock (HPHF) scheme for computing potential-energy surfaces for both singlet and triplet states are investigated. For that purpose, a new procedure based on the simultaneous solution of two eigenvalue equations is presented for calculating the HPHF function. Applications are given in the cases of the singlet ground state and lowest triplet state of the lithium molecule. In both cases, the HPHF scheme is found to yield the correct general shape of the curves. The features of these curves are discussed. Finally, it is concluded that the HPHF model seems to be useful as a tool for determining potential-energy surfaces, especially in the cases of large molecules where more sophisticated methods are unmanageable.
    Zusätzliches Material: 1 Ill.
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  • 189
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 14 (1978), S. 737-740 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The molecular spectra of formamide (HCONH2) are interpreted by the use of the new semiempirical method HAM/3. Very good agreement with experiments can be obtained for the calculation of all valence ionization energies as well as for the (negative) electron affinity. In addition, the calculated excitation energies allow an unambiguous interpretation of the UV spectrum, for which previously different ordering of the triplet 3ππ* and 3nπ* transitions have been suggested.
    Zusätzliches Material: 2 Ill.
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  • 190
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 13 (1978), S. 331-347 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The electronic structure of tetracyanoquinodimethane (TCNQ) is calculated using the new semiempirical method HAM/3. The calculated photoelectron spectrum is in reasonable agreement with the measured spectrum. The excitation energies are obtained directly in HAM as the differences of the energies of the unoccupied and the occupied orbitals. The calculated UV spectrum is in good agreement with the measurements. The weak band at 5.3 eV, which earlier had been assumed to correspond to a forbidden transition, is allowed according to HAM. The electron affinity is also in reasonable agreement with the measured value. An explanation has been given for the experimental observation of several resonance states (negative electron affinities). p-Quinodimethane has also been studied.
    Zusätzliches Material: 4 Ill.
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  • 191
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    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 14 (1978), S. 271-287 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The convergence properties of perturbation theories for molecular interaction energies are tested by performing high-accuracy high-order numerical calculations for a ground-state hydrogen atom interacting with a proton. It is shown that a strong symmetry forcing used in the Eisenschitz-London-Hirschfelder-van der Avoird (EL-HAV) theory leads to rapidly convergent perturbation expansion whereas a weak symmetry forcing, peculiar to the Murrell-Shaw-Musher-Amos (MSMA) theory, is not able to guarantee the convergence of the resulting perturbation series. The perturbation expansion introduced recently by Jeziorski and Kolos and corresponding to an intermediate symmetry forcing is shown to converge rapidly ensuring the correct asymptotic behavior of the interaction energy calculated through second order. Despite the divergence of the resulting perturbation series the MSMA theory is shown to give very useful results at the distances corresponding to the van der Waals minimum. In this region, however, virtually the same results can be obtained by using a simpler theory employing a properly symmetrized wave function of the usual Rayleigh-Schrödinger (RS) polarization theory.
    Zusätzliches Material: 6 Tab.
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  • 192
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    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 14 (1978), S. 333-336 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 1 Tab.
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  • 193
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 13 (1978) 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 194
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 14 (1978), S. 361-370 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 195
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 14 (1978), S. 371-382 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: We present a discussion of the functional dependences of the wave functions for bound, resonant, and scattering states on the radial coordinate ρ and the rotation angle α in the complex coordinate method. We conclude that for bound states and resonances, ρ and α are constrained to appear in the wave functions only in the for ρ exp(iα). On the other hand, this constraint is not obtained for the scattering states since the energy of the scattering states depends on α. In addition we suggest a partitioning of the resonant wave function into two parts - a boundlike or “Q-space” part and a scattering like or “P-space” part. With these concepts one can incorporate physical insight into the choice of configurations as one does in other methods and can apply the complex coordinate method to many electron systems with an expected rate of convergence similar to other techniques. Its advantages are that a single calculation yields the position and width of the resonance, only square integrable functions are used, only a solution of a straightforward eigenvalue problem is required unlike some methods, arbitrarily accurate target states are easily incorporated, and polarization terms can easily be explicitly included. Variational calculations for the position and width of the lowest 2S resonance in the negative helium ion are reported using trial wave functions containing 39, 43, 55, 24, and 32 “P-space” configurations, respectively. Values of 19.387 eV and 12.13 meV are obtained for the position and width, respectively, for the resonance over a range in the rotation angle of almost two orders of magnitude. One also finds that inclusion of free-particle-like basis functions improves the representation of the scattering states.
    Zusätzliches Material: 4 Ill.
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  • 196
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    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 14 (1978), S. 659-674 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: An explicit function has been derived for the potential-energy surface of the ground state of ClO3 with the six interatomic distances as variables. This surface is valid over all configurations of the atoms. The surface has been used to calculate classical trajectories for the reactions R1: O(3P2)+ClO(2Π3/2)→ O2(3∑g-)+Cl(2)P3/2 and R2: Cl(2P3/2)+O3(1A1)→ClO(2Π3/2)+O2(3∑g-). An appreciable fraction (∼1/3) of the reactive trajectories for R1 go through a long-lived complex ClOO(2A″). The cross section decreases with increasing rotational state of the ClO; and 37% of the energy release is vibrational. The calculated rate constant at 298°K is 2.6 × 10-11 cm3/molecule sec. For reaction R2 there is no evidence of long-lived complexes. The product ClO is predominantly found in the backward-scattering direction. Most of the internal energy is carries off by ClO but O2 carried off most translational energy. An Arrhenius expression has been deduced from calculations at 220 and 300°K to give an A factor of 2.488 × 10-11 cm3/molecule sec and an activation energy of 1.543 kJ/mol.
    Zusätzliches Material: 5 Ill.
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  • 197
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 14 (1978), S. 675-694 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Theoretical issues that must be considered for calculating rates of intramolecular electron transfer are discussed. The process itself is well defined only if the ground state is well approximated by a localized electronic function (Robin-Day class I or II). Under those conditions, the linear-response formalism yields the rate as the Fourier transform of the particle-hole propagator. We discuss the validity of electron propagators as approximations to particle-hole propagators, and find that they are valid, for simple models, within the stability range of the Hartree-Fock procedure. The vibronic nature of the transfer process is stressed, and formal schemes are given for calculating direct and through-bridge transfer rates. Outstanding difficulties, and applications to biological systems, are very briefly noted.
    Zusätzliches Material: 4 Ill.
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  • 198
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: In the local-mode description of vibrational structure, the nuclear coordinates - unlike the usual normal coordinates - do not reflect the molecular symmetry. Accordingly, the local-mode product wave functions must be symmetry adapted. We discuss this simple procedure in light of its implications for the localization of vibrational energy and the dissociation limits of molecular excited states. These properties are in turn related to the separability of the total nuclear Hamiltonian and to the different ways in which the vibrational anharmonicity is “absorbed” by the local and normal coordinates.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 199
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 14 (1978) 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 200
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 13 (1978), S. 801-810 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: It is shown how an idempotent density matrix provides a proper model for interpretation of the x-ray coherent diffraction experiment.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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