Library

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • 1985-1989
  • 1975-1979  (546)
  • 1975  (546)
  • Chemical Engineering  (390)
  • Electron microscopy  (111)
  • Rat
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Virchows Archiv 368 (1975), S. 99-108 
    ISSN: 1432-2307
    Keywords: Electron microscopy ; Calcium ; Parathyroid glands ; Chief cells ; Oxyphil cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Using the potassium pyroantimonate technique for ultrastructural localization of cations and X-ray elemental analysis with both energy dispersive and wave-length dispersive systems, calcium-containing precipitates were found in normal, hyperplastic and adenomatous human parathyroid glands. Differences were observed between oxyphil cells, and suppressed, stimulated and active chief cells in the content and localization of intracellular precipitation. The oxyphil cells and suppressed chief cells possessed precipitates mainly in nuclei and medium-sized and large mitochondria, whereas the stimulated chief cells possessed precipitates in normal-appearing and morphologically altered mitochondria, and in smooth-surfaced vacuoles and cytosol. The active chief cells usually showed a rather sparse precipitation.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Virchows Archiv 369 (1975), S. 19-27 
    ISSN: 1432-2307
    Keywords: Alpha-1-antitrypsin deficiency ; Liver ; Electron microscopy ; Endoplasmic reticulum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Fourteen liver biopsies from twelve young patients with liver diseases associated with homozygous, PiZZ phenotype, alpha-1-antitrypsin deficiency in their sera were examined by electron microscopy. In all these biopsies characteristic homogeneous material was found in some hepatocytes and corresponded, when observed on adjacent semithin sections by light microscopy, to the deposit stained by periodic acid Schiff reaction. The accumulation in perinuclear spaces resulted in intranuclear invaginations, but the major deposit was located in lumens of the endoplasmic reticulum. The limiting membranes were rough and smooth but the extent of the latter was so large that only this type of reticulum seemed peculiarly involved in the accumulating process. On the contrary, Golgi complexes did not seen obligatorily involved by this process because, when observed, they appeared almost normal even in heavily overloaded liver cells. At least for the PiZZ phenotype, the abnormal substance would be an asialo form of normal alpha-1-antitrypsin. Thus the subject of this study is the morphologic translation of an impairment in the synthesis of a glycoprotein. In the light of data concerning the synthesis of such proteins our findings lead us to suggest: The ultrastructural patterns observed in alpha-1-antitrypsin deficiency cannot give the expected morphologic evidence of the biochemical data which locate the first binding steps of monosaccharide residues in the rough endoplasmic reticulum. The absence of sialic acid could not result from an enzymatic defect primarily located in Golgi complexes but could be secondary to an impairment in the binding of one monosaccharide residue which improves subsequent fixation of sialic acid, in the smooth endoplasmic reticulum. Finally it seems necessary to emphasize that the relationship between the abnormal substance and various important non specific lesions is largely unknown and that we don't know the significance of polymorphous dense bodies observed in ductular cells during the cholestatic period.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Pflügers Archiv 357 (1975), S. 201-207 
    ISSN: 1432-2013
    Keywords: Allantoin ; Uricase ; Kidney ; Clearance ; Micropuncture ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Renal excretion of allantoin was measured by tracer techniques. After injection of 2-C14 urate and H3 inulin, clearances of allantoin and inulin were measured and both proximal and distal tubules were micropunctured. In confirmation of earlier results 2-C14 urate injected into an intact animal is very rapidly converted to C14 allantoin: after 15 min more than 90% of urinary tracer is present as allantoin. It was further observed that 1) allantoin clearance is essentially identical with inulin clearance over a wide range of urine flows; 2) no net transport of allantoin occurs in either proximal or distal tubules. Clearly allantoin is handled by the rat kidney like inulin. The total excretion of filtered allantoin unlike that of filtered urate provides an easy and effective mechanism for animals possessing the enzyme uricase to dispose of their purine loads.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1432-2307
    Keywords: Tumors of the skin ; Histogenesis ; Classification ; Labyrinth nuclei ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Es wird über den Feinbau folgender Hauttumoren berichtet: Dermatofibrom (7 Fälle), Histiozytom (4 Fälle), Dermatofibrosarcoma protuberans (1 Fall) und Fibroxanthom (1 Fall). Aufgrund ihrer unterschiedlichen ultrastrukturellen Merkmale ist eine zweifache Unterteilung dieser Hauttumoren möglich: In eine Tumorgruppe, umfassend das Dermatofibrom, Dermatofibrosarcoma protuberans und Fibroxanthom, bei der die Faserbildung im Vordergrund steht und für deren Histogenese Fibroblasten angenommen werden können. Diese Tumortypen unterscheiden sich vom Histiozytom, dessen Zellcharakter vor allem durch die stark ausgeprägte Phagozytose- und Speichertätigkeit (Fett und Hämosiderin) bestimmt wird und für welches eine histogenetische Ableitung von Histiozyten wahrscheinlich ist. Die Zellkerne des Dermatofibromes und des Histiozytomes weisen einen einfachen Oberflächenverlauf auf, die des Dermatofibrosarcoma protuberans und Fibroxanthomes haben hingegen sehr stark gegliederte Formationen („Labyrinthkerne”). Diese Kernsegmentierung ist für das Dermatofibrosarcoma protuberans ein morphologisches Korrelat seiner Semimalignität. Eine Klassifizierung der faserbildenden Tumoren als „fibröse Histiozytome” erscheint aufgrund der ultrastrukturellen Analyse nicht gerechtfertigt.
    Notes: Summary A report on the ultrastructure of the following skin tumors: dermatofibroma (7 cases), histiocytoma (4 cases), dermatof ibrosarcoma protuberans (1 case), and fibroxanthoma (1 case). Because of their different ultrastructural characteristics a division into two groups is possible: one group of tumors would include dermatofibroma, dermatofibrosarcoma protuberans, and fibroxanthoma, where the formation of fibers is extensive and fibroblasts are suggested for its histogenesis. These types of tumor differ from histiocytoma, the cellular character of which is determined by a very pronounced phagocytosis and storage of lipid and hemosiderin; a histogenesis from histiocytes is probable. The nuclei of dermatofibroma and histiocytoma show a simple surfacedevelopment, whereas the nuclei of dermatofibrosarcoma protuberans and fibroxanthoma show multisegmented nuclei (“labyrinth nuclei”). In the case of dermatofibrosarcoma protuberans this kind of nuclear segmentation seems to be a morphologic correlate of its semimalignancy. Based on ultrastructural analysis a classification of these fiber-producing tumors into “fibrous histiocytomas” is not justified.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Virchows Archiv 367 (1975), S. 171-179 
    ISSN: 1432-2307
    Keywords: Kidney failure ; Pregnancy ; Electron microscopy ; Hemolytic-uremicsyndrome ; Basement membrane ; Endothelium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The clinico-pathological data from a patient with irreversible post-partum renal failure (IPRF) are presented. The electron microscopy of the late changes are described for the first time and consists of: 1. Thickening of the basement membrane. 2. Interposition of mesangial cells and matrix between the thickened basement membrane and the endothelial cell encircling the periphery of the tuft. 3. Multiplication of basal lamina material between mesangial cells and endothelial cells. 4. Proliferation of endothelial cells. All of the above changes tend to obliterate the glomerular tufts and transform the vascular lumina into slit-like spaces. They explain morphologically why most patients with IPRF terminate in chronic renal failure, if they survive the early changes. The late occurring hypertension is regarded as a secondary stimulation of the renin-angiotension system caused by partial or complete occlusion of arteries and arterioles.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Virchows Archiv 369 (1975), S. 111-121 
    ISSN: 1432-2307
    Keywords: Atherosclerosis ; apoB ; LDL ; VLDL ; Immunoperoxidase ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The fine-structural localization of apoB, the major protein constituent of both the low and very low density plasma lipoprotein fractions, was described in human middle cerebral and basilar arteries. Using an immunoperoxidase technique together with electron microscopy, apoB was localized only in arteries with atherosclerotic involvement and to the following regions in these arteries: 1. on the outer aspects of extracellular spherical structures with diameters of 250 to 700 Å found predominantly in lipid cores and between bands of collagen fibers of advanced atherosclerotic lesions; 2. on the surface of reduplicated elastica; 3. along collagen fibers and; 4. on aggregates of extracellular spherical lipid globules. These results suggest that the extracellular spheres may represent the fine-structural morphology of deposited low and very low density lipoproteius and that free apoB may be bound to lipid globules, elastica, and collagen fibers.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 287 (1975), S. 1-10 
    ISSN: 1432-1912
    Keywords: Dopamine ; Adrenomedullary Hormones ; Synthesis ; Rat ; Adrenals ; Subcellular Distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Rats received intravenous injections of3H-tyrosine and were killed at various time intervals thereafter.3H-dopamine (DA) in the adrenals reached a maximum within 1.5 min after the administration of3H-tyrosine. From the 15th min it disappeared with an apparent half life of 90 min.3H-Adrenaline (A) +3H-noradrenaline(NA) increased much more slowly and reached a plateau 120–240 min after the injection. The approximate synthesis rate of adrenal A+NA, calculated from the specific activity curves, ranged from 9.3 to 2.2 nmoles/h per kg b.w. The highest value was noted the first few minutes, the lowest 1–2 hrs after the administration of3H-tyrosine. In some experiments subcellular fractionation of the adrenals was performed. In untreated animals the amount of DA and A+NA recovered from the supernatant fraction was about 10 and 8 per cent, respectively, of the total amount recovered from the supernatant and particulate fractions. In the adrenals of animals receiving3H-tyrosine 3.75 or 60 min beforehand these figures were significantly elevated whereas the DA and A+NA of the particulate fraction did not deviate significantly from control values. The specific activities of3H-DA were the same in the supernatant and particulate fractions within 3.75 min after the injection of3H-tyrosine.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 288 (1975), S. 109-121 
    ISSN: 1432-1912
    Keywords: Halothane and Nitrous Oxide Anaesthesia ; 5-HT Turn-Over ; Brain ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of anaesthesia with halothane and nitrous oxide on the turn-over of 5-HT in the rat brain were analysed. The rate of 5-HT synthesis was estimated on the basis of 5-HTP accumulation following 5-HTP decarboxylase inhibition. Inhalation anaesthetics reduced the rate of 5-HT synthesis in the whole brain, this effect being particularly marked in the forebrain. In addition, the reduction of the rate of 5-HT synthesis was still detected after a large tryptophan loading indicating that halothane and nitrous oxide anaesthesia reduced the activity of tryptophan hydroxylase in vivo. The utilization of 5-HT was also delayed during anaesthesia since the rate of 5-HT disappearance following the inhibition of its synthesis at the decarboxylation step was decreased in the whole brain. In spite of this reduced turnover of 5-HT in the brain of rats exposed to inhalation anaesthetics, the 5-HIAA levels were permanently elevated. This was the result of a partial inhibition of the active elimination of the acidic metabolite from the brain during this kind of anaesthesia.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 288 (1975), S. 147-153 
    ISSN: 1432-1912
    Keywords: Adenylate Cyclase ; Phosphodiesterase ; cAMP ; Gastric Mucosa ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of starvation, feeding and pentagastrin on gastric mucosal adenylate cyclase (AC) and phosphodiesterase (PDE) activity were studied in the rat. 1. Starvation for 24 hrs and 48 hrs reduced both NaF stimulated and basal AC activities. 2. Feeding of starved rats slowly raised the AC activity up to 430% within 4 hrs after feeding. This effect was more pronounced under basal conditions than with NaF stimulation. 3. A single i.p. injection of pentagastrin (125 μg/kg) caused a stimulation of basal AC lasting 45 min, which was followed by a subsequent decrease in the basal and NaF stimulated enzyme activity. 4. PDE activity was not influenced by starvation and feeding but underwent a transient inhibition by pentagastrin. Accordingly gastric mucosal cAMP levels after starvation, feeding and pentagastrin are regulated by changes in AC and not in PDE activity. The rise in AC activity after feeding appears to be related to functions other than H+ and pepsin secretion.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    ISSN: 1432-1750
    Keywords: Lung fibrosis ; Rat ; Paraquat ; Lungenfibrose ; Ratte ; Paraquatlunge
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Es wird die Erzeugung einer Lungenfibrose bei Spraque-Dawley-Ratten mittels mehrfacher Injektion von Paraquat intraperitoneal beschrieben. Notwendige Dosierungen, Intervalle zwischen den Injektionen sowie der zeitliche Ablauf der histologischen Veränderungen werden dargelegt.
    Notes: Summary An experimental model of lung fibrosis by multiple i.p. injections of the herbicide Paraquat is described. The schedules, intervals between injections and histological changes are described.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 288 (1975), S. 185-193 
    ISSN: 1432-1912
    Keywords: Avoidance Acquisition ; Development ; Pimozide ; d-Amphetamine ; Catecholamines ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The acquisition of a conditioned avoidance response (CAR) was investigated in rats of nursing mothers given pimozide 0.5 mg/kg on days 1, 2, 3, 4, 5, 6, and 7 after delivery. Four weeks after birth, the male litter-mates were tested for CAR acquisition in a two-way avoidance situation or for correct CAR acquisition in a brightness discrimination situation. Offspring of mothers treated with pimozide were markedly inferior in the CAR acquisition in both behavioural situations as compared to those of mothers given glucose. The administration of d-amphetamine 15 min prior to the training session specifically counteracted the behavioural impairment obtained in the offspring of pimozide-treated mothers. The results obtained in the present investigation lend further support to the contention that the behavioural deficits in offspring of nursing mothers treated with neuroleptic agents are due to a developmental disturbance in central catecholamine neurones.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 12
    ISSN: 1432-0738
    Keywords: Acrylonitrile ; Phenobarbital ; SKF 525-A ; Dimercaprol (BAL) ; Thiosulfate ; Cyanide-Thiocyanate ; Route of Administration ; Drug Biotransformation ; Rat ; Mouse ; Chinese Hamster ; Acrylonitril ; Phenobarbital ; SKF 525-A ; Dimercaprol (BAL) ; Thiosulfat ; Cyanid ; Thiocyanat ; Applikationsart ; Biotransformation ; Ratte ; Maus ; Chinesischer Hamster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Wistar Ratten, Standard-Albinomäuse und chinesische Hamster (Weibchen) erhielten eine einmalige Dosis von Acrylonitril, 0,5 oder 0,75 mmol/kg Gewicht. Die Ausscheidung des Thiocyanats, Hauptmetaboliten des Acrylonitrils, wies bei Ratten nach einer oralen (20 %), intraperitonealen und subcutanen (2 bis 5%) und intravenösen (1 %) Applikation einen sinkenden Umwandlungsanteil auf. Auch bei Hamstern und Mäusen rief die orale Verabreichung eine höhere Umwandlung hervor als bei der intraperitonealen Zufuhr. Die Vorbehandlung von Ratten mit Phenobarbital, SKF 525-A, Cystein oder Dimercaptopropanol, hatte keinen signifikanten Einfluß auf die Ausscheidung von Thiocyanat im Harn. Hingegen erhöhte die gleichzeitige Applikation von Thiosulfat bedeutend den Anteil von Thiocyanat, und zwar bei Ratten fast zweifach, bei Mäusen mehr als dreifach. Die Studie bestätigt den ausgeprägten Einfluß der Verteilung (first pass metabolic phenomenon) auf das metabolische Schicksal von Acrylonitril. Anscheinend ist die starke Bindung von Acrylonitril und die Cyanoethylierung für den so markanten Einfluß der Applikationsart verantwortlich. Nach oraler, intraperitonealer und intravenöser Applikation von Acrylonitril wurde dieser bei Mäusen effektiver in Thiocyanat metabolisiert als bei Ratten. Die größere Umwandlung von Acrylonitril in Thiocyanat und die stärkere Senkung seiner akuten Toxicität nach Thiosulfat deuten auf eventuelle Unterschiede im Mechanismus der toxischen Wirkung von Acrylonitril bei Mäusen und Ratten hin. In der Toxicität des Acrylonitrils für Ratten spielt Cyanid anscheinend eine kleine Rolle, wohl aber für Mäuse.
    Notes: Abstract Female Wistar rats, conventional albino mice, and Chinese hamsters were given a single dose of acrylonitrile, 0.5 or 0.75 mM/kg body weight. The elimination in the urine of thiocyanate, which is the main metabolite of acrylonitrile, indicated a decreasing proportion of biotransformation after oral (over 20 %), intraperitoneal, or subcutaneous (2 to 5 %), and intravenous (1 %) administration in rats. Oral administration of acrylonitrile in hamsters and mice was also followed by higher biotransformation than intraperitoneal administration. Pretreatment of rats with phenobarbital, SKF 525 A, cysteine, or dimercaprol did not significantly influence elimination of thiocyanate in the urine after the administration of acrylonitrile, but simultaneous administration of thiosulfate significantly increased the metabolized portion of acrylonitrile given intraperitoneally in rats (almost twice) and mice (more than three times). Acrylonitrile was found to be strongly bound in blood. The study confirmed the marked effect of distribution (first-pass metabolic phenomenon) on the metabolic fate of foreign compounds. The strong acrylonitrile binding and cyanoethylation are apparently responsible for the unusually high influence of the different routes of administration on the metabolic fate of acrylonitrile. Acrylonitrile was more effectively metabolized to thiocyanate in mice than in rats after oral, intraperitoneal, and intravenous administration. A greater response of acrylonitrile to thiocyanate metabolism and a larger decrease in its acute toxicity after thiosulfate in mice than in rats indicate possible differences in the mechanism of acrylonitrile toxicity in these animals. Cyanide apparently plays a minor role in the acrylonitrile toxicity in rats, but may play quite an important one in mice.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 13
    ISSN: 1432-0568
    Keywords: Corticotropin releasing factor ; Neurosecretion ; Hypophysis ; X-irradiation ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In 195 female Wistar rats the influence of adrenalectomy, total body X-irradiation and dexamethasone treatment on the amount of CRF-granules in the external zone of the median eminence and “classical” neurosecretory material (NSM) in the internal zone of the median and in the posterior lobe of the hypophysis has been studied. In the normal rat only very few CRF-granules occur. 15 days after adrenalectomy increased amounts of CRF-granules but normal amounts of “classical” NSM are found. X-irradiation leads to a slight diminishment of “classical” NSM in normal rats. In adrenalectomized animals X-irradiation causes no changes in the amount of “classical” NSM but a marked decrease in the amount of CRF-granules. Application of dexamethasone from the 15th to 18th day after adrenalectomy enhances the augmentation of CRF-granules in irradiated and non-irradiated rats but does not influence the amount of “classical” NSM. The findings show that no correlation exists between the quantitative changes of CRF-granules and “classical” NSM under the experimental conditions used. Therefore it is to be assumed that the release of the two substances is regulated by different control mechanisms and that the substances have a different functional significance. The observations do not exclude the possibility that CRF-granules and “classical” NSM are biochemically identical.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 14
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 146 (1975), S. 225-243 
    ISSN: 1432-0568
    Keywords: Differentiation ; Sympathetic ganglion ; Culture ; Electron microscopy ; Histochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Immature sympathetic ganglia prepared from 51/2- or 6-day-old chick embryos were cultured up to one month. The in vitro development was followed by phase microscopy, electron microscopy and using histochemistry for catecholamines, monoamine oxidase and cholinesterases. During the first week of culture extensive plexuses of nerve fibres were formed between and around the clusters of nerve cells. Mature-looking neurons were observed in the cultures by phase microscopy after three weeks, at which age the mean diameter of the perikarya was more than doubled. Varying catecholamine fluorescence was observed in the perikarya during the entire culture period. The nerve fibres showed usually only weak fluorescence, but, in the older cultures, bright varicosities were regularly found in the fibres. Monoamine oxidase activity was demonstrated already at three days of culture and the reaction was maintained positive. Weak or moderate acetyl-cholinesterase activity was demonstrated in the sympathicoblasts and young sympathetic neurons and their processes. The axolemma showed acetylcholinesterase activity also around the nerve terminals containing small dense cored vesicles. Reactions for the non-specific cholinesterases were negative. Electron microscopy of the 30-day-old cultures revealed that the clusters of nerve cells consisted of mature sympathetic neurons, which contained large (60–200 nm) and small (35–60 nm) granular catecholamine-storing vesicles. Glial cells were almost totally lacking. Large numbers of nerve terminals containing both large and small granular vesicles were observed in the clusters, often in synaptic contact with the sympathetic neurons. It is concluded that the primitive sympathicoblasts are, in favourable conditions, capable of differentiation in culture up to mature sympathetic neurons.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 15
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 146 (1975), S. 279-300 
    ISSN: 1432-0568
    Keywords: Retinogenesis ; Synaptogenesis ; Guinea pig ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A light and electron microscopic examination of retinogenesis in the fetal guinea pig has revealed an early development of synapses and photoreceptor cells. Differentiation of the neural retina begins around day 23 of gestation. By 34 days the retina reaches its maximum thickness. It differentiates an inner plexiform layer in which vesicle-containing processes and primitive synapses are evident. Synaptic ribbons are found in processes of this layer by 43–45 days of gestation. An outer plexiform layer develops within the neuroblast layer at 40 days of gestation; from its first appearance the outer plexiform layer contains synapses complete with synaptic ribbons. Receptor terminals of the α, paranuclear and β type are present well before birth. Photoreceptor cells form inner segments by 40 days; the formation of outer segments is indicated by 45 days but not widespread until 49 days. The retina appears mature by day 51–57. It is clear that the primate is not unique in the early differentiation of its retinal synapses relative to the time of maturation of its photoreceptor cells. The potential functional capacities of precocious retinae, and the mechanisms of synapse development are discussed.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 16
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 147 (1975), S. 177-187 
    ISSN: 1432-0568
    Keywords: Iris ; Melanogenesis ; Chicken embryo ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The iris anlage of 2–10 and 15 days old chicken embryos were studied histochemically, and by both light and electron microscopy. Light microscopic serial sections showed that pigmentation began at the outer layer of the posterior eye pole and progressed from there forwards to the optic cup margin. The entire outer layer of the optic cup as well as the pupillary margin were completely pigmented by the 4th day of incubation. By the 10th day the posterior iris epithelium was totally pigmented. Electron microscopical studies showed that the first premelanosomes appeared at about the 3rd day of incubation in the anterior iris anlage with the exception of the pupillary margin. It could be shown that melanogenesis progressed through the following steps: premelanosomes, followed by tyrosinase activity in a Golgi-associated system of smooth endoplasmic reticulum (GERL) and small vesicles and finally differentiation of the melanosomes. The possible origin of the premelanosomes and the formation of melanin are discussed.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 17
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 147 (1975), S. 293-307 
    ISSN: 1432-0568
    Keywords: Implantation ; Golden hamster ; Senescent ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Implantation was compared in young (3–5 month) and senescent (14–17 month) golden hamsters at 3, 31/2, 4, 41/2, 5, and 51/2 days of pregnancy (post-ovulation). One hundred twenty-two embryos (89 from 22 young females and 33 from 18 senescent females) located in utero by cutting thick sections (1–3 μm), were re-embedded and thin-sectioned for electron microscopy. Ultrastructurally implantation and embryonic differentiation was delayed approximately 12 hours in the senescent hamster when compared with young hamsters at the same stage of pregnancy. Failure of the blastocyst to implant would not appear to be a major cause of the declining litter size in aged golden hamsters.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 18
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 148 (1975), S. 47-58 
    ISSN: 1432-0568
    Keywords: Rat ; Endometrium ; Ultrastructure ; Progesterone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of various dosages and of various time periods of treatment with progesterone have been studied in the spayed, mature rat. Test objects were the cells of the luminal epithelium and of the endometrial stroma which were examined by qualitative and quantitative electron microscopy. No significant response was observed in epithelial or stromal cells until after 12 hrs of progesterone treatment. The nuclei of both cell types were then more circular than earlier with reduced long diameters. The functional significance of this change in configuration is unclear since only in the stromal cells was it followed by nuclear growth. Further, after 12 hrs of treatment the relative amounts of mitochondria and granular endoplasmic reticulum of stromal cells were reduced while the volume of the stromal cell cytoplasm appeared enlarged. This is taken as evidence that progesterone causes an intracellular oedema probably by decreasing cell membrane permeability. This response is probably not specific for the stroma but also includes the luminal epithelium, although the volume of the epithelial cell cytoplasm could not be determined here. Nucleolar enlargement did occur in stromal cells and was observed after 12 hrs of treatment but was not significant until after 24 hrs. At this point of time the net amount of granular endoplasmic reticulum in stromal and epithelial cells was increased indicating an increased protein synthesis in both cell types. However, only in the stromal cells was this associated with nucleolar enlargement, which supports the idea that progesterone stimulates protein synthesis through different mechanisms in the two cell types. Testing various dosages of progesterone showed that 0.5 mg had an effect similar to 5 mg of progesterone. When 0.05 mg progesterone was injected the only effect observed was an increase in the amount of apical vesicles of the luminal epithelium, showing that the epithelium is more sensitive to progesterone than the stroma.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 19
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 148 (1975), S. 89-97 
    ISSN: 1432-0568
    Keywords: Superior cervical ganglion ; Paraganglionic cells ; Rat ; Guanethidine ; Catecholamines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Paraganglionic cells in the rat superior cervical ganglion were investigated by fluorescence and electron microscopy following treatment with guanethidine for 5–30 days. Control animals received saline and guanidine. Fluorescence cytophotometric measurements revealed a general decrease in the catecholamine content of paraganglionic cells in guanethidine-treated animals. However a few cell clusters showed focal increases. Similarly by electron microscopy there was a general decrease in the number of dense core vesicles in the majority of paraganglionic cells with a minority of cell clusters showing increases.—guanethidine—as well as guanidine—treated animals showed non-specific cytological alterations such as mitochondrial swelling and increase of cytoplasmic glycogen. However no changes of catecholamine contents and of dense core vesicles were noted in control animals. These results confirm the conception that in rat paraganglionic cells the dense core vesicles are the main storage site of catecholamines. The marked difference in the response of some cell clusters to the experimental treatment can be considered as evidence of functional heterogeneity of this cell population in the rat superior cervical ganglion.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 20
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 148 (1975), S. 73-87 
    ISSN: 1432-0568
    Keywords: Rat ; Temporal cortex ; Synaptogenesis ; Retzius-Cajal cells ; Poly morphous cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The onset of synaptogenesis was studied in the temporal cortex of rat fetuses whose age ranged between 15 and 19 days of gestation. First synapses were found at a surprisingly early stage of cortical development: on day 16. These contacts showed relatively few vesicles and very inconspicuous membrane-thickenings. They were located in the marginal layer, above as well as below the narrow band formed by the newly arrived first neuroblasts of the prospective cortical plate. The postsynaptic structures were probably dendrites of the horizontally or obliquely orientated neurons scattered throughout the marginal layer (such neurons were seen even within the cell-dense band). On day 17, the cortical plate separated the differentiated cells definitely into a superficial and a deep population. As on the following days, synapses were found above and below the cortical plate but not within it. In addition to contacts showing the same features as those described on day 16, there were already synapses with numerous vesicles and clearly asymmetric membrane thickenings. On days 18 and 19 the borders of the cortical plate became more clear-cut. The well-differentiated neurons situated above and below this plate could now be identified as Retzius-Cajal cells of the prospective molecular layer and as polymorphous cells of the layer VI b respectively. The presence of axo-somatic contacts on these neurons provided direct evidence that both cell types are targets for synapses. Desmosome-like junctions were found even in the youngest fetuses studied. Their roughly symmetric membrane thickenings were clearly more conspicuous than those of earliest synapses. Desmosome-like junctions occurred very frequently between structures which subsequently were never seen to become synaptically linked. During the entire period studied, numerous coated vesicles fused with cell membranes were noted. Such “open” vesicles were seen on neurons (sometimes in the immediate vicinity of synapses) but also on non-nervous, extracortical as well as intracortical structures. Thus there does not seem to be a specific relationship between desmosome-like junctions and coated vesicles on the one hand and synapse formation on the other.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 21
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 33 (1975), S. 257-270 
    ISSN: 1432-0533
    Keywords: Perineurium ; Pathology ; Electron microscopy ; Homeostasis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The response of the perineurium to the following experimental systems was investigated by light and electron microscopy: nerve crush, cold lesion and microinjection of (a) histamine liberator, (b) potassium cyanide, (c) lysophosphatidyl choline (LPC). Where myelin breakdown occurred, lipid globules were seen within Schwann cells, macrophages and also perineurial cells. Where increased vascular permeability occurred, proteinaceous material leaked from endoneurial vessels into the endoneurial space and later appeared between perineurial laminae. It is suggested that the normal homeostatic function of the perineurium is extended in pathology to the removal of protein and lipid debris. In this way the perineurium contributes to the restoration of the normal microenvironment of peripheral nerve fibres.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 22
    Electronic Resource
    Electronic Resource
    Springer
    Diabetologia 11 (1975), S. 49-55 
    ISSN: 1432-0428
    Keywords: Rat ; blood glucose ; plasma insulin ; pancreas perfusion ; insulin secretion ; thyroxine ; glucose ; tolbutamide ; pyruvate ; isoprenaline
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Thyroxine treatment increases blood glucose and plasma insulin levels in the rat. The hypoglycemic effect of tolbutamide is more pronounced in treated animals. The immediate insulin secretory response of the isolated perfused pancreas to maximal, but not to submaximal, glucose stimuli was increased after thyroxine treatment, especially in the lower dose range. However, as thyroxine treatment reduces insulin release during the prolonged late phase, the total amount of insulin released from the pancreas is reduced. Both the early response to tolbutamide and the subsequent basal secretion were increased after thyroxine treatment. When the pancreas of treated rats was exposed to glucose plus pyruvate the inhibition of the late phase was reversed. Isoprenaline did not overcome the inhibitory effect of thyroxine treatment on the late phase of glucose-induced insulin release. Thyroxine induces a selective inhibition of glucose induced insulin release which is reversed by pyruvate; this indicates that thyroxine interferes with the glycolysis in the beta cell.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 23
    Electronic Resource
    Electronic Resource
    Springer
    Inflammation research 5 (1975), S. 57-61 
    ISSN: 1420-908X
    Keywords: Rat ; Lymphostatic encephalopathy ; Harmine ; Tremor ; Antiphlogistics ; Blood-brain barrier ; Permeability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Injection of the tremorigenic alkaloid harmine into lymphostatic encephalopathic rats leads to a longer duration of tremor and higher brain concentrations than in shamoperated controls. In lymphostatic encephalopathic as well as in normal rats different antiphlogistics shorten the tremor duration and decrease harmine concentraion in brain. The antiphlogistics do not influence the plasma concentration of harmine, its protein binding and its tremorend concentration in brain. The effect of antiphlogistics in lymphostatic encephalopathic rats is considered as a consequence of the reduced blood-brain barrier permeability. Obviously in sick animals the blood-brain barrier permeability for harmine is not increased; the prolonged harmine tremor and the increased alkaloid concentration in the brain are consequences of the impaired cerebral lymphatic drainage only.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 24
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 106 (1975), S. 195-200 
    ISSN: 1432-072X
    Keywords: Trichophyton terrestre ; Trichophyton rubrum ; Hyphal fusions ; Origin of intra-hyphal hyphae ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cell observation chamber was designed to perform continuous photomicroscopic observations of hyphal anastomosis and the origin of intra-hyphal hyphae in Trichophyton terrestre and T. rubrum. These data were correlated with ultrastructural features of intra-hyphal hyphae. Hyphal fusions occurred commonly in either species of Trichophyton when incubated alone. In T. terrestre, empty hyphal segments adjoined by live units were invaded at the septa from both directions by new hyphal ingrowth. Continuous observations revealed that the intra-hyphal hyphae subsequently anastomosed via a lateral fusion peg. Similar intra-hyphal hyphae were shown in T. rubrum. Electron microscopic studies revealed ascomycetous septa in both conventional hyphae and intra-hyphal hyphae. For the latter, the cytoplasm and wall of the inner hypha were bounded by cytoplasmic organelles and another cell wall of the outer hypha.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 25
    Electronic Resource
    Electronic Resource
    Springer
    Archives of toxicology 34 (1975), S. 309-314 
    ISSN: 1432-0738
    Keywords: Glafenine ; Chloroquine ; 4-Amino-7-chloroquinoline ; Rat ; Glafenin ; Chloroquin ; 4-Amino-7-chlorchinolin ; Ratte
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Bei oraler Zufuhr in einer Dosierung von 150 bis 450 mg/kg 2 Tage hintereinander an etwa 100 g schweren Ratten bewirkt Glafenin eine vorübergehende Nephritis mit Steigerung von Blutharnstoff, Hypertrophie der Nebennieren und Veränderungen des Serumproteinogramms. An die 4-Amino-7-chlorochinolin-Struktur scheinen diese toxischen Wirkungen nicht gebunden zu sein, denn die ähnlichen Derivate, Chloroquin und Amodiaquin, rufen sie in äquimolekulären Dosen nicht hervor. Glycerol, ein im Organismus entstehendes Hydrolysisprodukt des Glafenins, zeigte sich auch wirkungslos. Die Toxicität ist wahrscheinlich auf das Glafenin selbst oder sein saures Abbauprodukt 4-(0-carboxyphenylammo-7-chlorochinolin, zurückzuführen.
    Notes: Abstract When given orally in elevated but nonlethal doses (150 to 450 mg/kg, on 2 consecutive days), glafenine induces in rats (body weight 100 g) a transient nephritis with an increase in blood urea, hypertrophy of adrenals, and some changes in the serum proteinogram. These effects do not appear to be due to the 4-amino-7-chloroquinoline structure from which glafenine is derived, as they are not observed with the structural analogue chloroquine given at equimolar doses under the same conditions. Further, they do not appear to be due to glycerol, the by-product of metabolic glafenine hydrolysis. The responsible molecule appears to be either glafenine itself or its acid metabolite 4-(0-carboxyphenylamino) 7-chloroquinoline.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 26
    Electronic Resource
    Electronic Resource
    Springer
    Archives of toxicology 34 (1975), S. 213-225 
    ISSN: 1432-0738
    Keywords: Lead ; Chelating agents ; Toxicity ; Rat ; Blei ; Chelatbildner ; Toxicität ; Ratte
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die intraperitoneale Verabfolgung von Pb-Acetat führt zu einer mäßigen und vorübergehenden hypochromen Anämie, zu einer lang dauernden erhöhten Ausscheidung der δ-Aminolävulinsäure mit dem Urin, während die Ausscheidung der alkalischen Phosphatase überhaupt nicht und die von Lactatdehydrogenase nur geringfügig beeinflußtwird. Es wird gefolgert, daß weder die hamatologische Reaktion noch die angedeutete Nephrotoxicität für die letale Wirkung von Pb verantwortlich sind. Die Chelattherapie begann 3 Tage nach der letzten Pb-Dosis und erstreckte sich auf 7 Wochen, wobei die intraperitoneale Tages-dosis 25, 50 bzw. 100 μmol/kg betrug. Die Wirksamkeit in bezug auf die Erhöhung der Pb-Ausscheidung mit dem Urin nahm in der Reihenfolge ab: Ca-Diäthylentriaminpentaacetat 〉 2,3-Dimercaptopropan-1-sulfonat 〉 Zn-Diäthylentriaminpentaacetat 〉 D-Penicillamin. Das vermehrt ausgeschiedene Pb stammt im wesentlichen aus dem Skelett. Die Chelatbildner erniedrigten ebenfalls die Ausscheidung der δ-Aminolävulinsäure, erwiesen sich aber als unwirksam, die hämatologische Reaktion und die letale Wirkung von Pb günstig zu beeinflussen. Durch diese negativen Ergebnisse wird der Wert der Chelatbehandlung von Fällen akuter Pb-Vergiftung in Frage gestellt.
    Notes: Abstract The intraperitoneal administration of Pb acetate (5 × 20 mg Pb/kg per day) evokes a moderate and transient hypochromic anemia, a long-lasting enhanced urinary excretion of δ-aminolevulinic acid whereas the urinary excretion of alkaline phosphatase is not affected and that of lactic debyhrogenase only marginally. It is concluded that neither the hematologic response nor the slight nephrotoxicity are responsible for the lethal action of Pb. Chelate treatment started 3 days after the last Pb dose and was continued over 7 weeks. The daily intraperitoneal dose was 25, 50, and 100 μmol/kg, respectively. The efficacy in promoting the urinary excretion of Pb decreased in the following order: Ca diethylenetriaminepentaacetate 〉 2,3-dimercaptopropane-1-sulfonate 〉 Zn diethylenetriaminepentaacetate 〉 D-penicillamine. This effect was mainly due to the mobilization of skeletal Pb. The chelating agents also lowered the excretion of δ-aminolevulinic acid but failed to exert a beneficial influence on the anemia and the lethal action of Pb. These negative results raise questions about the usefulness of chelation therapy in cases of acute Pb poisoning.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 27
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 105 (1975), S. 193-199 
    ISSN: 1432-072X
    Keywords: Bean ; Rust ; Haustorium ; Sheath ; Autoradiography ; Infection ; Electron microscopy ; Phaseolus vulgaris ; Uromyces phaseoli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Tritium labeled uredospores of Uromyces phaseoli were produced be feeding the host, Phaseolus vulgaris, with 3H-orotic acid. These spores were allowed to germinate on and to penetrate into a bean leaf. 24 hrs after inoculation, the bean rust had formed the first haustorium. All fungal structures, including the fungus walls, were heavily labeled. No label could be detected in the cells that had come into contact with the hyphae. In the infected host cell, the haustorium was labeled heavily, but the sheath around the haustorium and the host cell remained free of label. These results indicate that no detectable amounts of label leach from the bean rust into the host at this stage of infection although it is known that the rust takes up many metabolites. Since the sheath remains free of label and all fungal structures are evenly labeled, it is concluded that the sheath is formed by the host.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 28
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 23 (1975), S. 157-166 
    ISSN: 1432-1106
    Keywords: Ventrobasal thalamus complex ; Thermosensitivity ; Burstactivity ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Recordings were made of spike-trains from 163 neurons of the rostral part of the ventrobasal thalamus complex of the rat while the temperature of the scrotal skin was altered. The following results were obtained: 55 neurons were nonthermosensitive, 7 neurons cold-sensitive and 101 neurons warm-sensitive. In the case of the warm-sensitive cells a definite discrimination was possible: 61.4% of the neurons altered their firing behavior during peripheral cooling, changing from relatively even spike frequency to burst firing. This change could be induced repeatedly by altering the temperature. 38.6% of the neurons, on the other hand, reacted to cooling by slowing down their frequency. By way of statistical methods the firing patterns of the two response-types were analyzed more precisely and the differences in response to temperature stimuli more exactly defined. Likewise, the spatial distribution of the two response-types of warm-sensitive cells exhibited differences; whereas the cells devoid of burst activity occured rather uniformly in the region of the thalamus studied, the cells with bursting activity were confined more to the mediocaudal region. These findings are discussed with regard to the phenomenon of peripheral bursts and to the projection of thermoafferent pathways onto the ventrobasal thalamus complex. The functional interpretation of the various cell reactions and their role in the central processing of thermoafferent signals still remains unexplained and requires comparative studies of peripheral and central parts of the thermoafferent system.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 29
    Electronic Resource
    Electronic Resource
    Springer
    International archives of occupational and environmental health 34 (1975), S. 167-175 
    ISSN: 1432-1246
    Keywords: N,N-Dimethylformamide ; Embryotoxicity ; Rat ; Inhalation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The purpose of this study, which was conducted for industrial toxicological reasons, was to investigate the possible embryotoxic and teratogenic effects after inhalation of dimethylformamide in rats. In a dynamic inhalation apparatus groups of 22–23 rats were subjected to approx. 18 ppm (maximum allowable concentration in the working area, MAC=20 ppm) and 172 ppm in the air for 6 hrs/day on 10 consecutive days, i.e. from the 6th to 15th day of gestation. The dimethylformamide inhalation did not cause any visible impairment to female rats as regards general behaviour, appearance or weight development during the treatment or the entire gestation period. The gestation rate was unchanged. The development of the fetuses was not influenced in any way by the exposure of the pregnant animals to approx. 18 ppm. In contrast the fetuses taken by caesarean section from the dams exposed to 172 ppm weighed significantly less than the fetuses of the control animals. Skeletal development of these fetuses, however, was normal. All other reproduction parameters were within the normal range for this strain. The study showed that the inhalation of dimethylformamide in concentration up to approx. 10 times the MAC had no teratogenic effect on rats.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 30
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 23 (1975), S. 463-470 
    ISSN: 1432-1106
    Keywords: Rat ; Hypoglossal nucleus ; Axotomy ; Horseradish peroxidase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The left hypoglossal nuclei of normal rats, and rats which had received left hypoglossal nerve axotomies 7–21 days previously, were studied by electron microscopy after injection of horseradish peroxidase as a marker of extracellular space and pinocytosis. Quantitative analysis showed that the number of pinocytotically-derived structures in presynaptic boutons was significantly increased in rats at 7, 14, and 21 days after axotomy when compared with normal rats. It was suggested that presynaptic boutons which became detached from injured neurones retracted by a membrane cycling mechanism involving pinocytotic uptake of bouton plasmalemma, without compensatory membrane production elsewhere. It was confirmed that the channels in the microglial cells communicated with the extracellular space.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 31
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 33 (1975), S. 1-8 
    ISSN: 1432-0533
    Keywords: Thalamus ; Cytoplasmic calcospherules ; Non-dystrophic ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Infantile thalamic degeneration is a rare clinico-pathological entity. Restricted location of the lesion and peculiar cytopathological changes serve to distinguish this disorder from other common encephalopathies. Optical and ultrastructural studies demonstrate cytoplasmic calcopherules in previously viable cells. According to current concepts of acute cellular reactions to injury and mechanism of intracellular calcification, the cytological changes cannot be attributed to either hypoxic ischemic cell change or dystrophic calcification. By analogy to other human and pathological material, the most likely basis for nondystrophic calcopherule formation is toxic or infectious injury with local synthesis, or autophagic or phagolysosomal degradation of cellular debris of specific chemical composition favoring calcium deposition.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 32
    ISSN: 1432-0428
    Keywords: Rat ; ammonium infusion ; blood ammonia ; glucose metabolism ; plasma immunoreactive insulin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In order to explain the abnormalities of glucose metabolism previously observed in patients with blood ammonia elevation, the effect of a transitory hyperammonemia on I. V. glucose tolerance was investigated in rats. An I. V. glucose tolerance test was performed in 3 groups of 15 rats 60 min after the beginning of a 95 min infusion of either a 2 ml isotonic NaCl solution (control group) or ammonium acetate solutions at low (0.50 μmol/kg/min. NH4+) or high doses (1.70 μmol/kg/min NH4+). The “high” NH4+infusion produced an increase of blood ammonia to levels near 1000 μg/100 ml, a significant decrease in the K coefficient for glucose disappearance (2.53 × 10−2±0.20 compared to 4.92 × 10−2±0.13 in control group) and a suppression of the radioimmunological plasma insulin (I.R.I.) response to glucose. With the “low” NH4 + infusion the hyperammonemia was less pronounced (200–300 μg/100 ml), but the decrease in K(3.02 × 10−2±0.15) and in the first phase of I.R.I, release remained significant. The decrease in glucose disappearance rate could be accounted for by the proportional decrease in insulin secretion. Thus glucose intolerance induced by ammonium acetate infusions may be due to a direct effect of NH4 + on the pancreas. These abnormalities in glucose metabolism depend on the quantity of infused ammonium.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 33
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 33 (1975), S. 143-152 
    ISSN: 1432-0533
    Keywords: Electron microscopy ; Experimental epilepsy ; Oedema
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Three different types of lesions have been studied in the cortex of the cat, by means of electroencephalography and electron microscopy. These three types of lesions can be listed in order of increasing magnitude according to their capacity to induce abnormal electrical activity: 1. incision of the cortex gives paroxymal activity, 2. intracortical insertion of a resin pellet generates weak epileptic activity, 3. intracortical insertion of a cobalt resin pellet produces epileptic activity. A parallel can be drawn between electrophysiological and anatomical data: there seems to be a quantitative relationship between the degree of epileptic activity and the extent of perilesional tissue. Furthermore, in this perilesional tissue, oedema is observed, the intensity of which varies according to the type of lesion. Thus, the epileptic activity of a lesion seems to be proportional not only to the volume of the perilesional tissue but also to the development of the oedema.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 34
    ISSN: 1432-0533
    Keywords: Adult metachromatic leukodystrophy ; Brain ; Peripheral nerve ; Kidney ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The fine structural characteristics of storage products in peripheral nerve, kidney and cerebral white matter, from a case of adult metachromatic leukodystrophy are described. There were pronounced differences from the fine structural aspects in late infantile cases. A large proportion of the inclusions did not exhibit a unit membrane. An hypothesis is proposed to clarify the delayed manifestation of this type of metachromatic leukodystrophy until adulthood.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 35
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 33 (1975), S. 191-200 
    ISSN: 1432-0533
    Keywords: Niemann-Pick disease ; Storage distribution ; Cerebral vascular glycolipid ; Histochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A histochemical study is reported of regional differences of the lipid storage in a case of Niemann-Pick disease (NPD) type C. Besides tissues known to be affected (reticuloendothelium, hepatocytes, nervous system), storage was demonstrated in adrenal cortical spongiocytes, sweat glands, renal glomerular and tubular cells, smooth muscle, excretory tubules of some salivary glands, ependyma and in choroid plexus. In most tissues were stored sphingomyelin, cholesterol and a small amount of a glycosphingolipid. In the endothelium of cerebral and spinal vessels the main stored lipid was a glycosphingolipid. The significance of these regional differences are discussed and their study is recommended as a useful counterpart to the biochemical investigation.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 36
    ISSN: 1432-0533
    Keywords: Experimental CNS tumours ; Methylnitrosourea ; Ethylnitrosourea ; Clonal growth ; Serum-free culture ; db cAMP treatment ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Six clones from methylnitrosourea (MNU) or ethylnitrosourea (ENU) induced tumours obtained in the nervous system of the rat were cultured in serum-free medium or treated with dibutyryl cyclic AMP (db cAMP) in vitro. All clones originated from longterm cultures. Three clones forming sarcomas after syngeneic transplantation showed only very slight changes following treatment, whereas the three glioma clones showed striking alterations. They formed long processes or showed rounding of their perikarya. In serum-free medium the cellular shape is intermediate between that seen in normal conditions and that seen in db cAMP treated cultures. The altered cultures resemble the primary cultures of the respective tumours. The relationship of these alterations to tumour types are discussed.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 37
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 33 (1975), S. 343-349 
    ISSN: 1432-0533
    Keywords: Lafora disease ; Myocardium ; Deposits ; Enzame histochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Histological, histochemical and electron microscopic studies on the myocardium of 3 Japanese patients with Lafora disease were carried out. Deposits in the myocardium stained positively with PAS, Best's carmine and Lugol's indine. After digestion of the sections with α-amylase, the deposits disappeared or were less intense, in particular with PAS staining. Phosphorylase activity was deficient in the myocardium of Case 3, when compared with controls, both of which were kept frozen at −20°C following autopsy. Electron microscopy revealed that the deposits were not membrane-bound and consisted of fine particles and fibrillae. The nature of the deposits is diseussed.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 38
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 33 (1975), S. 245-256 
    ISSN: 1432-0533
    Keywords: Herpes simplex encephalitis ; Blood-vessels ; Reactive microglia ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Generalized vascular changes and diffused proliferation of reactive microglia were observed in an experimental model of HSV encephalitis of mice. The wide spread of these changes contrasted with the localized character of virus replication and the confined areas of damaged nervous tissue. The vascular and microglial changes were precocious in animals inoculated with concentrated virus suspension (105.5LD50) while they appeared late in mice inoculated with diluted virus suspension (100 LD50). After inoculation with U.V. inactivated virus no changes were seen. The results obtained in this study suggest that the vascular and microglial modifications are not related to a direct cytopathic effect of the virus but dependent on the amount of virus present in the central nervous system and linked to the virus DNA.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 39
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 33 (1975), S. 275-278 
    ISSN: 1432-0533
    Keywords: Whipple's disease ; Macrophage ; Electron microscopy ; Brain involvement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A man of 22 with Whipple's disease suffered from an acute febrile state and unconsciousness. Focal inflammatory lesions accompanied by large numbers of peculiar macrophages occurred in thalamus and basal ganglia. The electron microscopic findings conform to previous reports on brain involvement in Whipple's disease.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 40
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 33 (1975), S. 207-226 
    ISSN: 1432-0533
    Keywords: GM2-Gangliosidosis, AB Variant ; Hexosaminidase A and B ; Electron microscopy ; Membranous cytoplasmic inclusions ; Zebra bodies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Clinical and neuropathological studies of a case of AB variant GM2-gangliosidosis have been presented. The patient was a 14 months old black female infant who had “black cherry spot” in the retinas. The total activities of β-galactosidase and N-acetyl-β-hexosaminidase, as well as the proportion of hexosaminidase A and B components in her serum and leukocytes were normal when the assays were carried out with artificial fluorogenic substrate. Diagnosis of GM2-gangliosidosis AB variant was established by an abnormal increase of GM2-ganglioside in the biopsied brain tissue, similar to classical Tay-Sachs disease. Her clinical manifestation appeared to be similar but somewhat milder than those of classical Tay-Sachs disease. Light microscopic features of the cerebral biopsy were also closely similar to Tay-Sachs disease and Sandhoff disease but gliosis and neuronal loss were less pronounced. Electron microscopic study revealed numerous membranous cytoplasmic bodies (MCB) and zebra bodies in neurons. In addition, varieties of large intracytoplasmic inclusions in astrocytes, a feature distinctly different from classical Tay-Sachs disease, were observed. Numerous cytoplasmic inclusions were also present in oligodendroglia, pericytes and microglial cells.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 41
    Electronic Resource
    Electronic Resource
    Springer
    Pflügers Archiv 353 (1975), S. 171-189 
    ISSN: 1432-2013
    Keywords: Enzyme Secretion ; Hormonal Stimulation ; Narcosis ; Pancreas ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. A method for collecting duodenal juice and gastric content separately, in conscious rats, is described. Metal cannulas were implanted into the stomach fundus. For the main experiment a double lumen tube was inserted through the cannula via the pylorus into the duodenum. 2. The following secretion patterns were observed: a) In the resting state there was a constant flow rate of duodenal volume, bicarbonate, trypsin and amylase. b) Cholinergic stimuli were capable of increasing enzyme secretion as much as fourfold for a period of 30 to 40 min when administered as a single subcutaneous injection. This effect was annulled by atropine. c) Secretin and cholecystokinin-pancreozymin given together in a single injection s. c. or i. v., elicited a similarly strong response. d) Identical ranges of the secretion maxima were found with a tendency to decrease after the first hour, when the hormones were infused either s. c. or i. v. e) Doses from 0.5 to 25 U/100 g b. w./hr showed identical responses. Doses below 0.2 U/100 g/hr were without effect. 3. Narcosis (pentobarbital) inhibited markedly the resting and stimulated enzyme secretion. 4. The method is suitable for examination of physiological and pharmacological effects on resting and stimulated enzyme secretion of the rat pancreas.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 42
    ISSN: 1432-2072
    Keywords: p-CPA ; Ethanol ; Pentobarbital ; Tolerance ; Brain 5-HT ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Rats were rendered tolerant to ethanol or pentobarbital by daily oral administration. Motor impairments after test doses of ethanol or pentobarbital were measured prior to and at various times during chronic treatment in order to assess the degree of tolerance development. Chronic administration of p-chlorophenylalanine (p-CPA) in a dosage regimen which produced and maintained approximately 95% depletion of brain serotonin (5-HT) did not alter motor impairment after initial acute administration of ethanol or pentobarbital. However, the rate of tolerance development to the motor-impairing effects of both drugs was slowed down in p-CPA-treated rats. p-CPA did not appear to exert this effect by altering the disposition of ethanol or pentobarbital, since blood levels determined 20 min after administration of the test doses were similar in animals treated with p-CPA and in controls. These findings suggest that brain 5-HT may have a role in tolerance development to ethanol and pentobarbital.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 43
    ISSN: 1432-2072
    Keywords: LSD-25 ; UML ; Acute ; Chronic ; Behaviour ; 5-HT ; Brain ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Successive daily injections of LSD-25 and UML (1-methyl-d-lysergic acid butanolamide) caused progressive depression of brain 5-HT levels in the rat. On the fourth day, the decrease was significant with respect to the highly significant fall observed after a single administration, whereas it had been shown earlier that conditioned behaviour is no longer affected by LSD-25 after 3 days and that simultaneous administration of a single dose of LSD-25 and UML is equally ineffective in this respect. Its depression of 5-HT levels, however, has now been shown to be equal to that of LSD-25 alone at doses that influence conditioned behaviour. The findings indicate that changes in such behaviour are not dependent on brain 5-HT levels and that no link exists between such levels and the psychotomimetic effect of LSD-25 in man.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 44
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 41 (1975), S. 301-304 
    ISSN: 1432-2072
    Keywords: Mescaline ; Anti-Drug Antibody ; Hapten ; Immunopharmacology ; Rabbit ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Antibodies with mescaline binding specificity were raised in rabbits by immunization with conjugates of bovine serum albumin with mescaline or its analogue 3,4,5-trimethoxyphenylacetic acid. Immunized rats were given mescaline and their behavior was compared to that of non-immunized controls.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 45
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 42 (1975), S. 147-152 
    ISSN: 1432-2072
    Keywords: Nicotine ; Selection ; Avoidance Conditioning ; Rat ; Latency ; Freezing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Rats of both sexes from the genetically selected Roman High Avoidance (RHA), the Roman Low Avoidance (RLA) and the Roman Control (RCA) strains were given one 30-min session of two-way escape-avoidance conditioning (30 trials) in a shuttle box with a buzzer as the conditioned stimulus and shock as the unconditioned stimulus in a factorial design involving three time intervals (0,15 and 30 min) following one subcutaneous injection of saline or of nicotine in five doses (0.05, 0.1, 0.2, 0.4, or 0.8 mg/kg of body weight). Six measures relating to performance were analysed in whole or part. While the number of avoidance responses showed the expected strain differences, no effect of dose or delay interval could be detected. Avoidance and escape latencies and intertriai activity showed some effects of these variables, especially in interaction with sex and strain. Dose determined pre-sessional activity, but its effect was strain dependent. The failure to confirm previous findings is discussed in the context of other instances in the literature, and the results of an operant experiment confirming the continuing sensitivity of the Roman strains to the effects of nicotine are reported.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 46
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 44 (1975), S. 287-289 
    ISSN: 1432-2072
    Keywords: Delta-9-tetrahydrocannabinol ; Social behaviour ; Mouse ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The behavioural effects of delta-9-tetrahydrocannabinol in mice and rats have been studied by an ethological analysis of encounters between animals injected with the drug and partners injected with the solvent (Tween-saline). In both species, Immobility was increased and Non-Social Activity reduced after injections of 5 mg/kg of delta-9-tetrahydrocannabinol. Flight was increased in treated mice but not in treated rats. Aggression was not significantly altered in either species. Thus, in the mouse, the qualitative behavioural effects of delta-9-tetrahydrocannabinol were similar to those previously reported for crude cannabis resin. Comparison of the dose-response data indicated that some other constituents of cannabis may reduce the Flight reaction from delta-9-tetrahydrocannabinol although not interfering with Immobility.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 47
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 42 (1975), S. 231-234 
    ISSN: 1432-2072
    Keywords: Heroin ; Self-Stimulation ; Water Intake ; Food Intake ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Male rats maintained with continuous access to levers for intracranial self-stimulation (ICSS), water, and food were subjected to five consecutive daily injections of heroin (5 mg/kg). Rates of lever pressing for ICSS were increased in 8 rats, 2–6 hrs after administration of heroin. Rates of lever pressing for water and food were not significantly changed during this period. Naloxone (5 mg/kg) pretreatment attenuated by 82% the facilitative effect of heroin on ICSS. A second group of 8 rats maintained at reduced ICSS rates failed to show an increase in lever pressing for ICSS with heroin. The facilitative effect of heroin described in this study is consistent with previously reported studies describing the effects of morphine on ICSS.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 48
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 42 (1975), S. 255-261 
    ISSN: 1432-2072
    Keywords: Methadone ; Mode of Withdrawal ; Body Weight ; Relapse ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Physical dependence on methadone was induced in rats by an initial “forced drinking” procedure and subsequently by i.p. administration of the drug. In a subsequent Experimental Phase of the study the physical dependence of one group was sustained by a “methadone maintenance” treatment, while two other groups were withdrawn from the drug, one gradually and one abruptly. When relapse trials were carried out during a Readdiction Phase it was found that the maintained group voluntarily consumed significantly greater amounts of methadone than did the two withdrawal groups. These groups did not differ between themselves but did in turn ingest significantly more methadone than a control group with no prior exposure to the drug. The characteristic loss of body weight reliably found during withdrawal from morphine was not demonstrated. This may have been due to the unexpected weight loss which occurred during the last stage of the initial Addiction Phase. The dependent variables of amount of methadone solution and the percentage of fluid consumed as methadone solution correlated highly. However the amount of methadone solution ingested was a better indicator of addiction liability as it was not influenced by fluctuations in the amount of water consumed by the animals.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 49
    Electronic Resource
    Electronic Resource
    Springer
    Pflügers Archiv 353 (1975), S. 215-225 
    ISSN: 1432-2013
    Keywords: Muscle Regeneration ; Muscle Transplantation ; Contractile Properties of Muscle Transplants ; Denervation of Muscle ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The soleus or extensor digitorum longus muscles of young rats were freely grafted into the bed of the corresponding contralateral muscle. The grafts were of normal muscle or muscles which had been denervated for 14 days. Grafts of normal muscle were characterized by little or no contractile activity for the first 2–4 days after transplantation. In contrast, denervated grafts contracted weakly, but consistently, throughout this early period. The patterns of contraction were complex. In early transplants, the contractions were due entirely to surviving muscle fibers in the graft, and the contractile characteristics were those of denervated muscle fibers. After the first week, contractions of newly regenerating muscle fibers within the grafts were superimposed upon and later took over those from the fibers that survived the original transplantation. The contraction time approached those of the normal soleus or extensor muscles during the second month after grafting, and the grafts contracted like fast or slow muscles.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 50
    ISSN: 1432-2013
    Keywords: High Altitude ; Coronary Blood Flow ; Cardiac Output ; Cardiac Hypertrophy ; Rat ; TissueP O 2
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In rats exposed to a simulated high altitude of 3500 m for their whole prenatal and postnatal life a severe cardiac hypertrophy develops. In rats born and first staying 5 weeks at sea level and then being exposed to simulated high altitude, only a unilateral right cardiac hypertrophy occurs. In both groups nutritional coronary blood flow was estimated in left ventricle, right ventricle, and septum and was compared with control animals of similar age. Coronary blood flow was measured at hypoxia in all groups. At first cardiac output was determined by the Fick principle, then86Rb was applied and the animals were killed after 55 sec. Activity of86Rb was measured in both cardiac ventricles and septum and the fractional uptake was calculated. According to Sapirstein (1956, 1958) the distribution of86Rb follows the distribution of cardiac output and from both these data the nutritional blood flow to the parts of the heart may be estimated. Cardiac output was similar in rats exposed to simulated high altitude later in life (“newcomers”) and in control animals, but it was significantly lower in rats born in the low pressure chamber (“natives”). Fractions of cardiac output supplying cardiac ventricles and septum in rats from both hypoxic groups were significantly higher than in control animals. In the “natives” they were significantly higher than in the “newcomers”. The fractions of cardiac output in both “newcomers” and “natives” remained significantly higher than those of the control animals, also when calculated per gram of heart tissue. Nutritional coronary blood flow (in ml/min) was higher in both ventricles and septum of the “newcomers” and in the right ventricle of the “natives”, and lower in the septum of the “natives”, when compared with control animals. Coronary blood flow per gram of heart tissue (in ml/min·g) was significantly higher in all cardiac parts of the “newcomers”, but it was about the same in all cardiac parts of the “natives” when compared with controls. The importance of observed changes concerning myocardial tissue oxygenation is analyzed by using Krogh's cylindrical tissue model.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 51
    Electronic Resource
    Electronic Resource
    Springer
    Mycopathologia 55 (1975), S. 53-55 
    ISSN: 1573-0832
    Keywords: Rubratoxine B ; Mitochondria ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The in vitro effect of rubratoxin B on the electron transport system of rat liver mitochondria was investigated. This mycotoxin depressed oxygen consumption in ADP-lacking mitochondria and in ADP-coupled mitochondria, using succinate or β-hydroxybutyrate as substrats. Rubratoxin B is neither an oxidative-phosphorylation inhibitor nor uncoupling agent. Its effect is compared with aflatoxin B1.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 52
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 8 (1975), S. 319-331 
    ISSN: 1432-0630
    Keywords: Self-interstitials in silicon ; Swirls ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Point defect agglomerates in dislocation-free silicon crystals, usually called “swirls”, have been investigated by means of high-voltage electron microscopy. It was found that a single swirl defect consists of a dislocation loop or a cluster of dislocation loops. By contrast experiments it could be shown that these loops are formed by agglomeration of self-interstitial atoms. Generally the loops have a/2〈110〉 Burgers vectors, but in specimens with high concentrations of carbon (∼1017 cm−3) and oxygen (∼1016 cm−3) also dislocation loops including a stacking fault were observed. In crystals grown at growth rates higher thanv=4 mm/min no swirls are observed; lower growth rates do not markedly affect the size and shape of the dislocation loops. With decreasing impurity content (particulary of oxygen and carbon) the swirl density decreases, whereas the dislocation loop clusters become larger and more complex. A model is presented which describes the formation of swirls in terms of agglomeration of silicon self-interstitials and impurity atoms.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 53
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 22 (1975), S. 525-540 
    ISSN: 1432-1106
    Keywords: Supraoptic nucleus ; Quantitative electron microscopy ; Afferent fiber connections ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A quantitative electron microscopic study of synaptic terminal degeneration was performed in the supraoptic nucleus (NSO) after a variety of major transections or ablations, destroying or interrupting in different combinations the afferent pathways known from earlier and own light microscopic degeneration studies. Solutions of a set of equations, expressing the percentage degenerations in synaptic profiles after different combinations in which the several pathways are interrupted by the various interferences, enabled the authors to give the following percentage numbers for afferent synapses from different sources. 32.7% of supraoptic afferents originate from the brain stem probably representing the monoaminergic innervation of this nucleus. The medial basal hypothalamus (21.0%), amygdala (13.5%), septum (13.5%), hippocampus (8.5%) and olfactory tubercle and further rostral cortical region (17.0%) are the other main sites of origin of supraoptic nucleus afferents. There are no supraoptic afferents from the optic nerve, superior cervical ganglion or fimbria hippocampi.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 54
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 22 (1975), S. 175-183 
    ISSN: 1432-1106
    Keywords: Rat ; Hypoglossal nucleus ; Axotomy ; Subsurface cisterns
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A quantitative ultrastructural survey was made of subsurface cisterns and their association with overlying structures in the left hypoglossal nucleus of normal rats, and rats which had received left hypoglossal axotomies 7–84 days previously. Subsurface cisterns in normal rats occurred in some hypoglossal neurones, and, sporadically, in proximal dendrites. They were mostly subsynaptic, and often associated with Nissl substance. From 7–14 days postoperatively, when many somatic boutons temporarily lost contact with the perikaryal surface, and were replaced by a microglial sheath, the percentage of perikaryon with underlying cistern was significantly reduced. The Nissl substance was also dispersed at this stage, and not restored until 28 days postoperatively. At 21 days normal percentages of subsurface cistern were restored, but the cisterns were now mostly subastrocytic, an astrocytic sheath having replaced the microglial sheath. From 63 days onwards the cisterns were mostly subsynaptic again as boutons returned to the regenerating perikarya and the temporary astrocytic sheath disappeared. It is suggested that subsurface cisterns might alter the overlying perikaryal surface in some way during neuronal regeneration, causing certain boutons to adhere there.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 55
    Electronic Resource
    Electronic Resource
    Springer
    Research in experimental medicine 165 (1975), S. 213-217 
    ISSN: 1433-8580
    Keywords: Rat ; Lymph nodes ; lymphography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Most the lymphatic system in the rat was directly observed in our experiment by radiological means. The lymphatics of the limbs were firstly revealed by subcutaneous injection of Patent Blue V. Lipiodol was used as radio-opaque compound injected by a micro-technique fully described by the authors.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 56
    Electronic Resource
    Electronic Resource
    Springer
    Research in experimental medicine 165 (1975), S. 245-249 
    ISSN: 1433-8580
    Keywords: Vinblastine ; Liver ; Perisinusoidal cell ; Microtubules ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Vinblastine, given intravenously to rats, leads to disappearance of microtubules, formation of paracrystalline inclusions and accumulation of fat droplets in the cytoplasm of the perisinusoidal cells of the liver suggesting that microtubules of the perisinusoidal cells play a role in lipid metabolism.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 57
    ISSN: 1432-2307
    Keywords: Lathyrism ; Capillaries ; Rat ; Ultrastructure ; Flavonoids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The ultrastructure of rat myocardial capillaries was studied in the course of experimental lathyrism. Endothelial cells were hypertrophic, with a sinuous profile of the plasma membrane facing the lumen and with a consistent increase of pinocytotic vesicles; the nuclei were irregular in shape; ATPase activity was no more demonstrable. Therefore, various and well distinct structural endothelial mechanisms seem to be primarily involved, causing an alteration of the dynamics of transcellular exchanges and of the permeability of the vascular wall. Simultaneous treatment with certain flavonoids, (O-(β-hydroxyethyl)-rutosides and Na(+)-epicatechin-2-sulfonate), resulted in a less pronounced alteration and a more rapid recovery. The possibility of the existence of a common site of action of lathyrogens and flavonoids is raised in the discussion.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 58
    ISSN: 1432-0878
    Keywords: Avian follicles ; Oocytes ; Transosomes ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Production and fates of transosomes (sacs of ribosomes made in the follicular cells of an ovarian follicle and subsequently passed to the cytoplasms of the oocyte) have been studied by electron microscopy in ovaries of young chicks, a testosterone-treated hen, aged hens which had ceased laying eggs and a “non-layer” mutant. Study was also made of “primitive yolk” (vacuoles present in both follicular cells and ooplasms of small follicles of normally laying hens). It was found that both transosomes and vacuoles of primitive yolk were present in small oocytes of young chicks, and “non-layer” mutants. However, the transosomes deep within the ooplasms were present within lysosomal vesicles in both of these instances and the vacuoles containing primitive yolk were patently abnormal in the “non-layer” mutant. Very few transosomes or primitive yolk vacuoles were present within the ooplasms of follicles from a testosterone-treated hen or from those of aged hens which were no longer laying. In both of these latter cases such bodies were present in the follicular cells. However, many transosomes were seen to be in the process of being lysed within the cytoplasms of these follicular cells.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 59
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 163 (1975), S. 99-110 
    ISSN: 1432-0878
    Keywords: Central neuropile ; Planorbis corneus ; Synapses ; Spinule complexes ; Varicosities ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The neuropile in the central ganglia of Planorbis corneus was studied by electron microscopy, using different fixatives. Several types of specialization were observed in the membranes of adjacent axonal processes, varying from only slight membrane thickenings to structures resembling desmosomes. Specialized structures similar to the ‘spinule complexes’ in mammalian brain are widely distributed in certain areas of neuropile. They consist of a small projection which invaginates a neighbouring neurone; the membranes are closely apposed and there is associated electron-dense material. The problem of identifying chemical synapses in this tissue is discussed. Many axonal processes are varicose, and it is suggested that varicosities may also be sites of transmitter release.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 60
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 163 (1975), S. 175-184 
    ISSN: 1432-0878
    Keywords: Cardiac sarcomeres ; Circolana borealis (Isopod) ; T-tubules ; Sarcoplasmic reticulum ; Couplings ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The membrane systems of the cardiac muscle cell of the isopod Cirolana borealis Lilljeborg are described. The sarcolemma invaginates at the level of the Z band, forming transverse tubules. Narrow tubules branch off in a longitudinal direction from these transverse and radially arranged TZ-tubules forming a transverse collar at each A-I level, where dyadic and triadic junctions are formed with the sarcoplasmic reticulum. Two different orientations of the coupling discs have been detected in the supercontracted sarcomere, and this observation has been discussed. Adjacent myofibrils are separated by a double layer of sarcoplasmic reticulum.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 61
    ISSN: 1432-0878
    Keywords: Human spleen ; Sinus lining cells ; Pulp veins ; Histochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Sinus and venous walls of normal human spleens were studied with enzyme histochemical and electron microscopic methods. Particular attention was paid to the connections between sinuses and veins. Histochemically the sinus lining cells revealed a distinct naphthol-AS-acetate-esterase activity but no reaction for alkaline phosphatase. Venous endothelial cells were positive for the latter but negative for the former enzyme. In the sinusvenous junctional area there were no endothelial cells with reactivity for both enzymes. Electron microscopically both the sinus lining cells and the venous endothelial cells could be clearly characterized and therefore easily distinguished from one another on morphological grounds. There were no clear ultrastructural indications of transitional forms between sinus lining cells and venous endothelial cells in the sinus-venous area. According to these findings, sinus lining cells represent a specialized endothelium, but one with practically no morpholgical similarities to the venous endothelium.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 62
    ISSN: 1432-0878
    Keywords: Epidermis ; Salmonids ; Mucous cells ; Mucus ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fine structure of epidermal mucous cells of two species of salmonid fish has been described. Mucous cells are, next to filament-containing cells, the most commonly encountered cells in fish epidermis. The development of the cells as they progress to the periphery has been characterised. They are initially difficult to distinguish from filament-containing cells: later, they can be recognised by the presence of much smooth-surfaced E.R. The mucigenesis and the subsequent secretion of mucus has been observed and it is essentially comparable to that which occurs in the mucous cells of the mammalian intestine. The mucous layer of the epidermal surface seems to mainly comprise of the products of these mucous cells and the “cuticle” seen in other species has not yet been observed in the salmonid species investigated here.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 63
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 156 (1975), S. 201-216 
    ISSN: 1432-0878
    Keywords: Smooth muscle ; Myofilaments ; Vas deferens ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Smooth muscle cells of the mouse vas deferens fixed with 5% glutaraldehyde contained three types of filaments, namely, thin (50–80 Å) filaments, intermediate (100 Å) filaments and thick (120–180 Å) filaments. However, in 2 out of 16 experiments, under identical conditions, the cells did not contain thick filaments. With OsO4 fixation, thin filaments were not prominent, the most obvious being thick (120–250 Å) and intermediate (100 Å) filaments. After soaking in a modified Ringer solution under no applied tension for one hour, thick filaments (120–180 Å) appeared prominently in smooth muscle cells of the mouse vas deferens and thin filaments were in ordered bundles. By 4 hours, thick filaments had increased in size and density, with thin filaments distributed randomly around them. After 8 hours in Ringer, thin filaments were diffuse and difficult to discern, while thick filaments were large (up to 300 Å) and electron-dense. Intermediate (100 Å) filaments were present in association with dark bodies. Physiological experiments indicated that the intracellular components responsible for the development of a mechanical response were still functional at this time. The presence of “thick filaments” is also reported in degenerating smooth muscle cells of the guinea-pig vas deferens in tissue culture.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 64
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 156 (1975), S. 377-380 
    ISSN: 1432-0878
    Keywords: Vasopressin-neurophysin neurons ; Suprachiasmatic nuclei ; Immunoenzyme histochemistry ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Immuno-enzyme histochemical investigations on the hypothalamus of the normal rat showed (1) that the Suprachiasmatic nuclei produce vasopressin; (2) that it is highly probable that these nuclei do not produce oxytocin. From the present and previous investigations it may be concluded that the Suprachiasmatic neurons produce a vasopressin-neurophysin complex.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 65
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 156 (1975), S. 411-416 
    ISSN: 1432-0878
    Keywords: Acrosome ; Spermatid ; Budgerigar ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The development of the acrosome of the budgerigar spermatid was studied under the electronmicroscope. The acrosome arises from a granule derived from the Golgi apparatus which interacts with the nucleus to form a cone shaped acrosomal cap and a perforatorium. A quantity of cytoplasm and plasma membrane is captured from the cell periphery and incorporated into the substance of the acrosome. The possible significance of the developmental phases and comparative avian spermatology is discussed.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 66
    ISSN: 1432-0878
    Keywords: Adenohypophysis ; Rat ; L-dopa ; Fluorescence histochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The uptake of L-dopa into the cells of the adenohypophysis of the rat was studied during the postnatal development and at adult age using the formaldehyde-induced fluorescence method (FIF). The cells taking up L-dopa were classified by Alcian blue-PAS-Orange G staining. The correlation between the cells taking up L-dopa and those containing tryptophyl-peptide was estimated during the postnatal period and in adult rats. The cells containing tryptophyl-peptide were demonstrated using fluorescence induced by treatment with combined formaldehyde and acetyl chloride vapour. The following observations were made: 1) Great majority of the cells taking up L-dopa did not contain tryptophyl-peptide. Thus the accumulation of L-dopa into the cells of pars distalis is not due to accumulation of L-dopa into the cells by the same transport mechanism as the amino acids for tryptophyl-peptide. 2) Of the cells taking up L-dopa in the adult rats 96% were chromophobes, 2.0% acidophilic cells (somatotrophs and cells producing prolactin), 0.9% R-mucoid cells (corticotrophs), and 1.2% S1- and S2-mucoid cells (gonadotrophs and thyrotrophs). At 10 and 25 days' age the relative numbers of the cells taking up L-dopa were about the same. 3) Pretreatment with nialamide caused only a slight increase in the number of the cells taking up L-dopa. The decrease in the number of the cells uptaking L-dopa of the pars distalis, which takes place after 5 weeks' age is thus not caused by the increased MAO-activity. 4) Strongly chromophilic cells did not take up L-dopa. At the light of our results it seems evident that L-dopa is taken up by the chromophobic cells when these differentiate into chromophilic cells. The accumulation of L-dopa may be a sign of an active transport of amino acids into the cells. The accumulation of L-dopa into the chromophobic stellate and follicular cells may reflect their metabolic activity. These cells probably have an important role in the production of the hormones of the pars distalis.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 67
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 156 (1975), S. 475-482 
    ISSN: 1432-0878
    Keywords: Annulate lamellae ; Spermatocytes ; Grasshoppers ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Intranuclear and cytoplasmic annulate lamellae were studied in grasshopper spermatocytes (Melanoplus) with the electron microscope. Although cytoplasmic annulate lamellae were observed in all three species examined, intranuclear annulate lamellae were found in only one species. The intranuclear annulate lamellae encompass certain nuclear material adjacent to the nuclear envelope forming a vesicle that is extruded into the spermatocyte cytoplasm. In this same species, cytoplasmic annulate lamellae are seen contiguous with granular masses of varying size. These structures were noted as being morphologically indistinguishable from the “yolk nuclei” of dragonfly oocytes (Kessel and Beams, 1969; Kessel, 1973).
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 68
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 158 (1975), S. 111-120 
    ISSN: 1432-0878
    Keywords: Iris ; Rana pipiens ; M. dilatator, sphincter pupillae ; Electron microscopy ; Photosensitivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The iris of the grass frog Rana pipiens, can respond to light even when isolated from the remainder of the animal. The iris is a three-layered structure, comprising a stromal layer and two layers of pigment epithelium. The sphincter pupillae, which is composed of pigmented smooth muscle cells, is embedded between the two layers of pigment epithelium. There is no dilator pupillae in this species. We have been unable to find any cells or any organelles in the iris which are anatomically specialized for photoreception in any obvious way.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 69
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 158 (1975), S. 205-213 
    ISSN: 1432-0878
    Keywords: Sertoli cell ; Crystalloid ; Swine ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Spindle or needle-shaped crystalloids are observed in Sertoli cells of the intersex and experimental cryptorchid swine in the light and electron microscopes. Small crystalloids are also observed in Sertoli cells of the normal swine only by electron microscopy. These crystalloids consist of fine filaments. The filaments are about 5 nm in diameter and arranged parallel to the long axis of the crystalloid. In cross sections of the crystalloid, the close packing of the filaments shows hexagonal arrays. The interfilamentous distance is about 5 nm. In all animals examined, bundles of short filaments, which are 5 nm in diameter, are observed in the basal part of the Sertoli cells. Ultrastructural similarities among the crystalloids, the bundles of fine filaments, and the filamentous layer in the junctional specialization of the Sertoli cell are shown. These morphological similarities suggest that the crystalloids are formed by the aggregation of the bundles in the Sertoli cells of azoospermic testes.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 70
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 15 (1975), S. 11-15 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Liquid SO2 sealed into tubes made of a fluorocarbon copolymer permeates the walls of the tube at a temperature-dependent but accurately reproducible rate. Sulfur dioxide dispensers made in this way are called permeation tubes and are useful for calibrating instruments that measure SO2 concentrations in air. The National Bureau of Standards calibrates SO2 permeation tubes and makes them available as Standard Reference Materials. The permeation rate in a batch of nominally identical tubes varies enough that each Standard Reference Material tube must be individually calibrated. Changes in the length or radial dimensions of the tubes are much too small to explain most of this variation. An excellent (negative) correlation is found between the measured permeation rate and the density of the polymer (or weight per unit length). Since both the measured density and the permeation rate for this semi-crystalline polymer depend upon morphological factors, but in different ways, x-ray diffraction measurements of the thickness and orientation of the lamellar crystals were made and a mathematical model was set up to identify the morphological factors which can cause variations in the permeation rate.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 71
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 15 (1975), S. 1-10 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A theory for roll coating of a fluid onto a moving sheet is developed utilizing the usual “lubrication approximations.” The effects of fluid and operating parameters on coating thickness and pressure distribution are determined for a Newtonian fluid, and for a purely viscous non-Newtonian fluid obeying the Power Law. The results for these cases are obtained analytically, and are rather straightforward.A viscoelastic fluid is considered, of a type which shows typical non-Newtonian shear behavior observed in polymer melts and solutions and which also exhibits normal stress behavior. Analytical solutions are not possible, but a perturbation method, using a viscoelastic perturbation parameter related to a Deborah number, yields an approximate solution. Only terms to first order in the perturbation parameter are given. Subject to that degree of approximation, the following conclusions are drawn: 1Non-Newtonian shear behavior reduces the pressure distribution, and increases the coating thickness.1Elasticity of the type usually observed in polymer solutions makes only a minor contribution to the roll-separating (load-carrying) force. The contribution is positive, but smaller than the corresponding negative contribution due to the non-Newtonian shear effects.1An increase in load-carrying capacity would require a different viscoelastic fluid than the type considered here - one that is essentially Newtonian in shear but, independently, capable of developing significant normal stresses.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 72
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 15 (1975), S. 29-34 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: There are two distinct solid conveying theories that can be applied to plasticating screw extruders. One is Darnell and Mol's theory based on a solid-to-solid friction model and the other is Chung's theory based on a viscous shearing model. The two theories predict very different solid conveying performances for a same set of conditions. In this paper, the maximum pressures that can be developed inside plasticating screw extruders by the solid conveying force are calculated using each of the two theories. Comparison of the results may shed some light on the applicability of each theory for a particular extrusion operation.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 73
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 15 (1975) 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 74
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 15 (1975), S. 79-83 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The mechanical properties of a propylene-ethylene copolymer resin depend strongly on the mold temperature employed during injection molding. Average spherulite size correlates well with most physical properties; good impact properties are related to small average size, and high heat distortion temperatures to large average size. Tensile specimens have three distinct regions when viewed through crossed polars. The outer region (Region 1) does not contain spherulites, but Regions 2 and 3 do. The largest spherulites are found in Region 3, the center of the specimen. Region 1 has a molecular weight higher than that of the other two regions.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 75
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 15 (1975), S. 113-116 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: During the last several years there has been considerable interest in the occurrence of structure in certain bulk polymers normally thought to be structurally homogeneous. Specifically, it has been proposed that polymers produced by emulsion polymerization may retain a particle structure in the bulk state. This has been demonstrated by both rheological measurements and by electron microscopy. In this work we show conclusively that at least part of the particle structure observed by electron microscopy for polystyrene is an intrinsic feature of the fracture surface and is in no way related to the history of the sample.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 76
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A new type of extrusion rheometer has been designed which employs dual slit geometry with a double valve. The double valve concept allows a change in flow rates through the slits, while the total extruder flow rate remains constant thus leaving extruder operating conditions unchanged. Electronic pressure transducers are mounted along the slit to record axial pressure distribution. Flow rates are measured by weighing polymer output and wall shear stresses are calculated from the axial pressure profiles. Exit pressures are derived from extrapolating the pressure profile to the slit exit and from this information the normal stresses can be determined.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 77
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 15 (1975), S. 761-773 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The rheological behavior of aqueous solutions of Separan AP-30®, polymethylcellulose, and polyvinylpyrrolidone was studied experimentally. These solutions exhibit non-Newtonian flow behavior in simple shear, and are characterized by one of several 2, 3, or 4 parameter rheological equations. The equations used included the power law, the Ellis model, Spriggs equation, the Herschel-Bulkley equation, and Meter's model. The power law model fits the data for each of the solutions over a limited range of shear rates, whereas the other models, which include either a lower shear rate limiting Newtonian viscosity, and/or an upper shear rate limiting Newtonian viscosity, or a yield stress, fit the data well over a wide range of shear rates from 0.00675 to 1076 sec-1. The pressure drop-flow rate data for the same aqueous solutions flowing through packed beds were correlated well by the Ergun equation using the various rheological models applied in this work to evaluate a modified fluid viscosity. In each case it was found that the rheological model which best fit the viscometric data also gave the best packed bed friction factor correlation, and that no one model, such as the powerlaw, or the Ellis model, is the best one to use in all cases for all solutions. For polyvinylpyrrolidone solutions large deviations between experimental values of friction factor and those from the Ergun equation occurred for modified Reynolds numbers greater than one. A pseudo viscoelastic parameter was used to improve the friction factor correlation empirically at high Reynolds numbers.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 78
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 15 (1975), S. 219-224 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Recent work is presented on the plastic deformation of linear polyethylenes. This work demonstrates the importance of molecular weight and initial morphology in determining the drawing behavior, and shows that by appropriate choice of these two factors a substantial increase in draw ratio and hence stiffness can be achieved over conventionally-oriented polyethylenes. Under optimum conditions a modulus of approximately 700 Kbar was obtained at a draw ratio of ∼30. These very high modulus materials displayed an extensibility to break of at least 3 percent and a strength of about 4 Kbar. In some cases they also exhibited very high melting points (∼139°C) and exceptionally good thermal stability.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 79
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 15 (1975), S. 238-239 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 80
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 15 (1975), S. 569-582 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A practically-oriented computer model which computes the temperature, pressure, and velocity fields in a cavity during the mold filling portion of the injection molding process is described. The model is structured so that it can be used for cavities having non-simple shapes and for commonly used molding compounds with complicated viscosity, shear rate, temperature relationships. Predictions from the model are found to be in good agreement with results obtained from exact solutions to special cases. Model predictions in molding problems have been found to correctly describe trends such as an increase in the pressure required to fill molds as injection rate, shot temperature, and mold temperature decrease, and to be reasonably accurate when compared to data for plaque, disc, and telephone housing molds over a wide range of molding conditions. Some illustrative examples of the use of the model in solving real molding problems are provided.
    Additional Material: 25 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 81
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 15 (1975), S. 646-650 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The dynamic mechanical properties of a series of thermoplastic urethane elastomers have been studied as a function of molecular composition and temperature. Polymers based on polycaprolactone diol, an isomeric mixture of tolylene diisocyanate and hydrogenated Bisphenol-A as the chain extender were prepared at various relative concentrations of hard and soft segments. The glass transition temperatures of these polymers progressively shifted to higher temperatures as the relative hard segment content was increased. This variation was accurately described by the Fox relationship for amorphous copolymers. These results can be interpreted in terms of the relative degree of segregation between the segment of the block copolymers.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 82
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Elastomeric bearings which consist of cylindrical rubber layers bonded on their inner and outer curved surfaces to metal cylinders are investigated theoretically and experimentally. Emphasis is placed on two asymmetic loading modes, radial loading and bending or tilting moments. An approximate theoretical treatment based on linear elastic behavior is proposed. Experimental spring constants are compared to the theoretical predictions for thin elastomer layers of various lengths. It was found that for highly confined layers, the theoretical spring constants must be modified to obtain agreement with experimental results. The importance of elastomer bulk deformation, shrinkage stresses from elastomer cure, and tension-compression stress-strain behavior is also evaluated.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 83
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 15 (1975), S. 660-667 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Experimental studies of structure development in melt spinning of polyethylene and polypropylene fibers are described. Emphasis is given to the influence of applied stresses on the rates of crystallization and on the development of crystalline morphology. The relationship of fiber morphology to mechanical properties, especially “hard elastic fibers” is considered. The relevance of such studies to other polymer processing operations such as film extrusion is discussed.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 84
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 15 (1975), S. 673-678 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Previous studies have evaluated low molecular weight crystalline materials as latent heat sinks for passive thermal protection systems. This study evaluated crystalline polymers as heat storage materials. Differential scanning calorimetry and Instron thermomechanical analysis are applied in dynamic studies of cumulative histories of melting and recrystallization. Commercially available crystalline polymers with melting temperatures Tm ≥ 100°C can provide fully reversible heats of fusion ΔHm ≥ 35 cal/gm under programmed heating-cooling cycles. A linear polyethylene (Marlex 6050) is modified by radiation crosslinking to retain shape stability above Tm with-out loss of heat storage capability. The essentially zero vapor pressure and inherent shape stability of crosslinked crystalline polymers may provide unique advantages as uncontained, non-expendable, heat storage materials.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 85
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 15 (1975) 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 86
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 15 (1975), S. 690-695 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: One dimensional transient heat conduction analysis of reactive, unfilled polyesters and epoxies shows that care must be taken during curing to minimize large temperature excursions due to internal heat generation. Isothermal heat generation rates have been shown to underestimate the non-isothermal values by more than an order of magnitude.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 87
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 15 (1975), S. 684-689 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The mixing of polymers is an important subject which has received considerable and recent attention. This study shows that residence time distribution curves give information on the distribution of material along the primary flow direction, but do not quantify in polymer flow systems. Several polymer processing systems have been analyzed and the degree of mixing has been related to strain in each of these systems. Strain correlates directly with transverse mixing, which is the most important aspect of polymer mixing. Mixer design is shown to influence the amount of strain needed to achieve a specified degree of mixedness.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 88
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 15 (1975), S. 725-730 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Theoretical equations for power dissipation and torque for single and multi-section screw extruders for Newtonian or slightly non-Newtonian melts are derived from improved theoretical velocity distributions. Verification of the equations is indicated by experimental data for four single-section screws of constant channel depth. The power equations can be easily programmed on a digital computer for design or evaluation.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 89
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 15 (1975), S. 731-746 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A composite normally consists of a material forming a continuous matrix and a different material in the form of discrete particles. The composite structure is characterized by the proportions of each component, the shape of the particles and their arrangement in space. A generalized way to characterize a particle shape and its position relative to adjacent particles is shown to describe the various geometrical arrangements of two components in space. The components of a composite often have different transport or related properties, i.e., thermal or electrical conductivity, gas permeability, modulus of elasticity, etc. A given property of a composite is a function of the structure of the composite and the corresponding property of each component. Structure-property analytical relationships are presented and compared. A generalized relationship corresponding to a generalized particle is discussed and shown to be practical and realistic.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 90
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 15 (1975), S. 747-756 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Shortages of both energy and materials make it imperative that low cost substances, processed with low energy requirements, be developed as soon as possible. One promising type of materials are the structural thermoplastic foams since they further enhance the favorable strength to weight ratio of plastics while reducing overall material needs. In addition, foam processing also capitalizes on the generally lower energy consumption and manpower-hour requirements for plastics. Finally, the possibility of forming larger and more complex shapes opens up new application areas. The largest deterrent to the use of structural foams is the lack of appropriate basic engineering and scientific knowledge. This paper not only summarizes and extends such understanding, but also shows how appropriate design procedures can be developed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 91
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 15 (1975) 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 92
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 15 (1975), S. 757-760 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Numerical results are given of calculations of the radial, transverse, and shear stresses in the matrix surrounding a cylindrical inclusion in plane strain perpendicular to the cylinder axis, this being taken as a model of a fiber composite under transverse loading. It is shown that the presence of an interlayer on the fiber at a thickness which is a small fraction of the fiber diameter can significantly affect the stress concentrations in the matrix. The interlayer-fiber ‘composite’ can be ‘matched’ to the matrix by suitable choice of interlayer elastic moduli. In particular, if the shear modulus of the interlayer is smaller than that of the matrix and its Poisson's ratio is very small, the stress concentrations in the matrix are considerably reduced and the composite should be less subject to failure by delamination.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 93
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 15 (1975), S. 831-833 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: It is now possible to do molecular weight distribution of polymeric material almost as fast as you can put them in solution. μSYRAGEL® has opened a new era in the determination of molecular weight distribution of polymers. With operational efficiencies of 800 plates/min., one can obtain a molecular weight distribution in 15 mins. Combining three of the newest advances in liquid chromatography - solvent delivery, septumless injection, and μSYRAGEL - now makes it possible to use molecular weight distribution as a quality control tool in polymerization and fabrication. The reproducibility of the molecular weight distribution is now good enough that overlays can be done from the raw data. The chromatograms can be used right off the recorder. The reproducibility of the weight average and number average molecular weight is 2-3 percent.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 94
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Evidence is presented that singlet oxygen may have an important role in the photo-oxidation of polymers. Increased attention is being paid to singlet oxygen as a possible reactive intermediate in the initiation step of the photodegradation of polymers. Singlet oxygen may be produced by energy transfer either from impurities or internal groups after excitation, e.g. carbonyl groups, which are present in commercial polymers. As a consequence, reactions of singlet oxygen may also be important in the stabilization of polymers, e.g. leading to search for new and more effective antioxidants.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 95
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 15 (1975), S. 65-69 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Dynamic elastic modulus and internal friction of a Portland cement (Type I) mortar system impregnated with an epoxy resin system and with methyl methacrylate were measured in the temperature range of 100 to 450°K by use of a free-free resonance technique. Dynamic modulus values were found to increase greatly compared to controls, especially at lower (〈300°K) temperatures. Above 320°K the dynamic moduli of polymer-impregnated mortars exhibited a sharp decrease toward control values. Low temperature damping maxima of the composites differed significantly from those of the constituent phases.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 96
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 15 (1975), S. 84-89 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Viscous dissipation causes significant temperature increases in polymers while they are flowing through extruder dies. The development of the temperature field has been studied numerically using the dimensionless parameters Na and Gz. With the annular geometry (parameter: ratio of radii κ) the well known developing temperature fields in capillaries could be compared with the developing temperature fields in an annulus and in a plane slit. The shear dependence of the viscosity is described by a “power law” and the temperature dependence by an exponential function. A simple graphical method is suggested for estimating temperature fields in extruder dies, making use of the fully-developed temperature field for very long dies as a reference state. For the demonstration of results, a power law exponent n = 0.4 has been chosen.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 97
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 15 (1975) 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 98
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 15 (1975), S. 129-129 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 99
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 15 (1975), S. 150-159 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Graphite has a hexagonal close-packed crystal structure which is strong and stiff in the two directions of the basal plane and, in the third direction - perpendicular to the basal plane - is weak and compliant. High-performance carbon fibers must make use of the strong directions while suffering from the poor properties of the third. This paper describes, from fundamentals, the processes used to produce high-performance carbon fibers. The resulting fiber microstructures and the consequences of these structures on properties are presented.
    Additional Material: 20 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 100
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 15 (1975), S. 167-177 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This note illustrates how the development rate for the use of composites as engineering materials has recently increased. Reasons for the expected even larger number of applications of composites in industry is explored. The engineering potential of composites is outlined in terms of properties and design aspects and mainly by pointing out how the proper use of a composite requires a clear knowledge of its application as well as the appropriate design technology. Examples of applications in different fields are reported with the aim of showing the high versatility of composites for a variety of engineering applications. The final part is devoted to cost aspects, which are considered in connection with the effects of composite use upon the total structure. The purpose is to show that a large number of interesting applications are already cost effective.
    Additional Material: 26 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...