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  • Electronic Resource  (584)
  • 1980-1984  (584)
  • 1970-1974
  • 1982  (584)
  • Chemical Engineering  (524)
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  • Nuclear reactions
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  • Electronic Resource  (584)
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  • 1980-1984  (584)
  • 1970-1974
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Keywords
  • 1
    Electronic Resource
    Electronic Resource
    Human osteogenic sarcoma (1982)
    Springer
    International orthopaedics 6 (1982), S. 171-179 
    Details
    ISSN: 1432-5195
    Keywords: Osteosarcoma ; Electron microscopy ; Acid phosphate ; Alkaline phosphate ; Bone tumour
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé La morphologie de 26 sarcomes ostéogéniques a été étudiée par microscopie électronique et la localisation des phosphatases acide et alcaline a pu être précisée au niveau ultrastructural. Quatre différents types de cellules ont été mis en évidence dans les tumeurs: cellules d'aspect ostéoblastique, fibroblastique et chondroblastique, ainsi que des cellules géantes multinuclées. Les cellules d'aspect ostéoblastique étaient présentes dans presque toutes les tumeurs étudiées. Une activité phosphatasique acide a été trouvée dans les lysosomes de toutes les cellules étudiées. Une activité phosphatasique alcaline a été observée dans — ou sur — la membrane plasmatique et dans les vésicules associées des cellules d'aspect ostéoblastique et fibroblastique ainsi que des cellules géantes. L'abondance des produits de réaction de la phosphatase alcaline contrastant avec une faible activité phosphatasique acide est en accord avec la nature de cette tumeur ostéogénique. Les résultats de l'étude histochimique ont aidé à comprendre la pathobiologie des différentes cellules qui constituent les sarcomes ostéogéniques.
    Notes: Summary The morphology of 26 cases of osteogenic sarcoma was studied using electron microscopic techniques, and the localization of acid and alkaline phosphatase activity at the ultrastructural level elucidated. Four different cells were present in the tumours: osteoblast-like, fibroblast-like, chondroblast-like, and multinucleated giant cells. The osteoblast-like cell was present in most of the tumours studied. Acid phosphatase activity was present in lysosome-like structures of almost all the cell-types studied. Alkaline phosphatase activity was noted in or on the plasma membranes and associated vesicles of osteoblast-like, fibroblast-like, and multinucleated giant cells. The abundant reaction product deposition of alkaline phosphatase as compared with the lower acid phosphatase activity is in agreement with the nature of this bone-forming tumour. The results of the histochemical studies have added to the understanding of the pathobiology of the different cells composing osteogenic sarcomas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00267727
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  • 2
    Electronic Resource
    Electronic Resource
    Adenoma of the human pituitary producing growth hormone and thyrotropin (1982)
    Springer
    Virchows Archiv 395 (1982), S. 59-68 
    Details
    ISSN: 1432-2307
    Keywords: Adenohypophysis ; Electron microscopy ; Growth hormone ; Immunocytology ; Pituitary adenoma ; Thyroid-stimulating hormone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A pituitary adenoma removed by surgery from a 22-year-old man was studied by histology, immunocytology, transmission electron microscopy and immunoelectron microscopy. Clinically, the patient had acromegaly and euthyroidism with elevated blood GH concentrations. Blood TSH and T4 levels were within the normal range. Histologically, the adenoma was chromophobic and exhibited no PAS, lead hematoxylin, aldehyde thionin or Grimelius silver positivity. By the immunoperoxidase technique GH, β-TSH and α-subunit but no PRL, ACTH, α-endorphin, β-FSH or β-LH were demonstrated in the adenoma cells. Electron microscopy revealed adenoma cells which were similar to TSH cells and showed no resemblance to GH cells of nontumorous pituitaries or GH-secreting tumors. Immunoelectron microscopy demonstrated GH and β-TSH in the secretory granules. It is concluded that pituitary adenomas composed of TSH-like cells may secrete GH, resulting in acromegaly. Production of GH by adenomatous TSH cells cannot be explained on the basis of the one cell- one hormone theory. The question is raised whether bihormonal or multihormonal clones, capable of synthesizing more than one hormone, exist in the human pituitary. These cells are apparently dormant under normal conditions, but in the course of neoplastic transformation may undergo functional dedifferentiation and acquire the ability to produce two or more different hormones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00443484
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  • 3
    Electronic Resource
    Electronic Resource
    Endothelium and “silver lines” (1982)
    Springer
    Virchows Archiv 395 (1982), S. 133-144 
    Details
    ISSN: 1432-2307
    Keywords: Endothelium ; Permeability ; Electron microscopy ; Electrolytes ; Silver
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The significance of endothelial “silver lines” was studied by TEM in rat aortas after perfusion with glutaraldehyde followed by silver nitrate. Standard TEM technique proved unsatisfactory (coarse silver granules, imprecise localization, artefacts). Exposure of the silver-treated aortas to photographic fixer markedly improved the image of the deposits leaving fine, stable, uniform “residual granules” about 100 Å in diameter. Most of these granules were localized along the intercellular junctions; they also tended to pool in the basement membrane beneath each junction. This image suggests that the Ag+ ions pass through the junction, and react with its contents as well as with the basement membrane beyond it. A scheme is proposed to explain the reaction of Ag+ ions with anions and negatively charged radicals within the junction. It is concluded that the “silver lines” represent not only a histochemical effect, but also the visualization of a transendothelial electrolyte pathway.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00429607
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  • 4
    Electronic Resource
    Electronic Resource
    The ultrastructure of human fibrosing alveolitis (1982)
    Springer
    Virchows Archiv 395 (1982), S. 181-199 
    Details
    ISSN: 1432-2307
    Keywords: Lung disease ; Electron microscopy ; Interstitial pneumonia ; Fibrosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This report describes the ultrastructural findings in 37 patients who underwent open lung biopsy which yielded diagnoses of fibrosing alveolitis. A spectrum of lesions are categorized for the capillary endothelium and its basement membrane, the interstitial space and its fibrocellular components, and the alveolar epithelium and its basement membrane. The findings typify the different pulmonary cellular reactions to injury. Evidence for cellular regeneration and death in both epithelial and endothelial cell populations include atypical epithelial cell proliferation, capillary basement membrane multilamination, decrease in capillary lumen size and prominent pericytic ensheathment of pulmonary capillaries. Within the interstitium of the lung, proliferation of collagen and elastic fibers are documented, but in addition, abundant myofibroblasts and smooth muscle cells are present. No ultrastructural evidence of immune complex deposition was found in this study. The morphologic findings of fibrosing alveolitis further support the widespread concept that the lung responds to various injuries in a similar manner and undergoes a common reparative response regardless of etiology.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00429611
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  • 5
    Electronic Resource
    Electronic Resource
    Primary sarcoma of the gallbladder (1982)
    Springer
    Virchows Archiv 396 (1982), S. 91-102 
    Details
    ISSN: 1432-2307
    Keywords: Primary gallblader sarcoma ; Electron microscopy ; Histopathology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Six Swedish cases of primary sarcoma of the gallbladder from the period 1958–1973 and 1 case from 1975 were studied by light and electron microscopy. The literature was reviewed for the period after 1970. Ultrastructural features of sarcoma were investigated in order to exclude poorly differentiated carcinoma. One case was considered to be an embryonal rhabdomyosarcoma, three cases leiomyosarcoma and two were diagnosed as fibrosarcoma. One case, diagnosed as sarcoma of the gallbladder by light microscopy, was omitted because electron microscopical examination revealed a squamous cell carcinoma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00428502
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  • 6
    Electronic Resource
    Electronic Resource
    Arrest and extravasation of neoplastic cells (1982)
    Springer
    Virchows Archiv 396 (1982), S. 73-89 
    Details
    ISSN: 1432-2307
    Keywords: Human malignant cells ; K-562 cell line ; Vascular arrest ; Endothelial attrition ; Extravasation ; Nude and lasat mice ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The morphological aspects of the arrest and extravasation of malignant cells of human origin (K-562 cell line) in the lungs of athymic (nude) and asplenic-athymic (lasat) mice were studied by electron microscopy examination of serial sections. The specimens were obtained at sequential stages after the sc inoculation into newborn mice of 107 malignant cells. K-562 cells (105) were also injected iv into control groups of nude and lasat mice to assess the influence of the route of inoculation on the in vivo behavior of K-562 cells. Our results demonstrated that K-562 cells were arrested and proliferated within the pulmonary capillaries without the participation of platelets or fibrin. The neoplastic cells extravasated by attrition and penetration of the endothelium (rather than by diapedesis) and continued to proliferate in the interstitial tissue of the lung, developing into neoplastic nodules. Following iv injection, K-562 cells induced the formation of platelet-tumor cell aggregates within the pulmonary capillaries. However, under these conditions, the neoplastic cells did not adhere to the endothelium nor did they proliferate or extravasate. These aggregates were flushed out by the circulation, restoring the permeability of the capillaries.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00428501
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  • 7
    Electronic Resource
    Electronic Resource
    An ultrastructural and morphometric study of bladder tumours (II) (1982)
    Springer
    Virchows Archiv 396 (1982), S. 291-301 
    Details
    ISSN: 1432-2307
    Keywords: Electron microscopy ; Bladder neoplasms ; Measurement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Bladder tissues from 3 groups of patients were examined, using the light and electron microscopes (LM and TEM). One group of patients had a history of well-differentiated papillary transitional cell carcinomas and specimens were taken from cystoscopically normal areas. In a second group frank papillary carcinoma was biopsied. Finally, patients with no history of urothelial tumours and a normal cystoscopic appearance were biopsied during investigations for various benign conditions and these served as controls. In tissues from the first two groups certain differences were seen when these were compared to the controls and the frequency of these was significant. Light microscopic examination of 0.5 μ toluidine blue stained sections revealed an increased number of immature, small dark cells in the superficial layer of the epithelium (P〈0.001). Electron microscopic examination showed that in place of the characteristic asymmetric unit membrane of mature superficial cells, the surface was frequently covered with microvilli and the junctional complexes were often atypical. There was an increased number of abnormalities in the basal lamina (P〈0.001). These features were seen in the absence of cystoscopic and light microscopic changes in three out of eight patients with a history of tumours. It is, therefore, suggested that these are the earliest detectable morphological abnormalities in the pre-neoplastic urothelium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00431388
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  • 8
    Electronic Resource
    Electronic Resource
    Ultrastructure of a virilizing ovarian Leydig-cell-tumor (1982)
    Springer
    Virchows Archiv 397 (1982), S. 17-27 
    Details
    ISSN: 1432-2307
    Keywords: Ovarian tumor ; Hilus cell tumor ; Leydig cell tumor ; Virilism ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A case of virilizing ovarian hilus cell tumor (Leydig-cell tumor) in a 37 year old female was studied by light and electron microscopy. The ultrastructural features of this rare and almost allways benign tumor are compared with those reported in the literature and with findings in normal and neoplastic interstitial cells of the testis. Tubulovesicular hyperplasia and formation of whorl structures of the endoplasmatic reticulum together with the presence of exocytosis vesicles on the cell surface may be the morphological manifestation of endocrine activity of the tumor. The identity of ultrastructural and optical diffraction characteristics of the crystal inclusions in both cells (hilar and testicular interstitial) favours the assumption of an homology of both cells and their neoplasms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00430890
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  • 9
    Electronic Resource
    Electronic Resource
    Synovial sarcoma arising in an anatomical bursa (1982)
    Springer
    Virchows Archiv 397 (1982), S. 93-101 
    Details
    ISSN: 1432-2307
    Keywords: Biphasic synovial sarcoma ; Semitendinosus bursa ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In previous studies, the origin of synovial sarcoma directly from synovium has not been satisfactorily established. This case report describes the light and electron microscopic features of a biphasic synovial sarcoma occurring within the popliteal fossa. At surgery, a cystic mass was identified in relationship to the semitendinosus tendon at the anatomical site of the semitendinosus bursa. The tumour originated from the inner surface of the bursa as multiple papillary projections with no evidence of extension beyond the capsule of the bursa. Portions of the synovial surface were hyperplastic but otherwise normal. The findings indicate that biphasic synovial sarcoma can arise directly from synovium and support the hypothesis of a mesenchymal histogenesis for this tumour.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00430896
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  • 10
    Electronic Resource
    Electronic Resource
    Tumor of mesonephric origin in a diverticulum of the urethra (1982)
    Springer
    Virchows Archiv 397 (1982), S. 335-345 
    Details
    ISSN: 1432-2307
    Keywords: Bladder neoplasm ; Mesonephric origin ; Urethral diverticulum ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A case of a rare tumor arising in a diverticulum of the urethra was studied. Light microscopy revealed the typical structures of mesonephric tumor with obvious infiltration of the muscularis. Electron microscopic appearance indicated that the tumor cells were immature and not totally characteristic of any tissue of origin. Apart from appearances suggesting rapid growth, cellular inclusions of various appearance were found.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00496574
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  • 11
    Electronic Resource
    Electronic Resource
    Chordoid sarcoma (extraskeletal myxoid chondrosarcoma) (1982)
    Springer
    Virchows Archiv 399 (1982), S. 61-78 
    Details
    ISSN: 1432-2307
    Keywords: Chordoid sarcoma ; Chondrosarcoma ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Evaluation of a series of 12 chordoid sarcomas suggests that there is a wider range of histological features in this entity then previously appreciated. Six of the lesions had a typical tumor cell organization and a mixture of cellular and myxoid stromal components, while the remaining cases were atypical because of a more solid growth pattern. Four of the 12 cases, that included both typically myxoid and more cellular examples, had small foci with hyalinized stroma segragating individual or small groups of tumor cells with and without lacunar spaces. Two atypical cases revealed more extensive and obvious chondrocytic differentiation in recurrent or metastatic lesions and in one of these, the histological pattern was that of mesenchymal chondrosarcoma. Ultrastructural examination of three cases revealed fine structural features of both the tumor cell population and extracellular matrix compatible with chondrocytic differentiation. Results of light and electron microscopy of this series of chordoid sarcoma add further support for categorizing this tumor with other malignant chondrocytic neoplasms. It is probable that chordoid sarcoma and extraskeletal myxoid chondrosarcoma represent the same entity and that this lesion has a close histogenetic relationship to mesenchymal chondrosarcoma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00666219
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  • 12
    Electronic Resource
    Electronic Resource
    The permeability alteration of brain and spinal cord vasculature to horseradish peroxidase during experimental decompression sickness as compared to the alteration in permeability induced by hyperosmolar solution (1982)
    Springer
    Acta neuropathologica 57 (1982), S. 179-187 
    Details
    ISSN: 1432-0533
    Keywords: Decompression sickness ; Hypertonic solutions ; Blood-brain barrier ; Blood-spinal cord barrier ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The permeability of microvasculature in the cerebral cortex, neostriatum, and spinal cord to i. v. injected horseradish peroxidase (HRP) has been investigated in rats following experimental compression to 6.1 bars (abs.) air for 90 min, and subsequent decompression to the ambient pressure in 1 min. For comparison, 1 ml of 2.0 M urea was injected into the right common carotid artery of rats during 15 s. After exposure to compression-decompression, under the light microscope focal leaky areas were found in all the regions examined. The leakage was most prominent in the grey matter of the spinal cord, and the cerebral cortex. In decompressed rats, arterioles were most often the site of peroxidase extravasation, whereas extravasation of HRP was less frequently displayed by capillaries and venules. In urea-treated rats, capillaries and venules frequently displayed extravasation of HRP as well. Parenchymal cells accumulated the trace adjacent to the leaky areas. Under the electron microscope, the extravasation of HRP was associated with peroxidase-containing pleomorphic vesicular structures in the endothelium, both in decompressed and urea-injected rats. Moreover, in contrast to decompressed rats, the junctions between endothelial cells were penetrated by the trace in urea-treated rats. Accordingly, the results indicate that during decompression sickness the pathway for the extravasation of proteins is through vesicular transfer, whereas the injection of hyperosmolar urea induces extravasation, both through vesicular transfer and junctions between the endothelial cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00685387
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  • 13
    Electronic Resource
    Electronic Resource
    Fine structure of merkel cells after PUVA treatment (1982)
    Springer
    Archives of dermatological research 274 (1982), S. 373-375 
    Details
    ISSN: 1432-069X
    Keywords: Merkel cell ; PUVA ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00403744
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  • 14
    Electronic Resource
    Electronic Resource
    Intra-astrocytic glycogen granules and corpora amylacea stain positively for polyglucosans: A cytochemical contribution on the fine structural polymorphism of particulate polysaccharides (1982)
    Springer
    Acta neuropathologica 57 (1982), S. 99-102 
    Details
    ISSN: 1432-0533
    Keywords: Cytochemistry ; Electron microscopy ; Polyglucosan bodies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A cytochemical procedure for polysaccharides was carried out on a brain biopsy specimen, the thin-section study of which had shown excess glucogen granules and the corpora amylacea variety of polyglucosan bodies. Both granules and amyloid bodies were stained positively in contrast to the remaining structures of the brain tissue which remained unstained. This demonstrates that β-granules as well as filamentous and amorphous components of amyloid bodies are just different aspects of the polysaccharide molecule. Up to now the same kind of cytochemical evidence has been supplied for Lafora bodies of human material and Lafora-like bodies of rat material. The present study on corpora amylacea of human material shows that amyloid. Lafora, and Lafora-like bodies all behave the same way when stained for polysaccharides.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00685376
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  • 15
    Electronic Resource
    Electronic Resource
    Muscle fiber type morphology and distribution in paraplegic patients with traumatic cord lesion (1982)
    Springer
    Acta neuropathologica 57 (1982), S. 243-248 
    Details
    ISSN: 1432-0533
    Keywords: Skeletal muscle ; Paraplegia ; Complete spinal cord lesion ; Histopatology ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Biopsies of the rectus femoris muscle of 22 paraplegic patients with complete acute spinal cord transection due to trauma were taken for enzyme-histochemical and electron-microscopic studies in successive stages starting from the occurrence of the accident (1–17 months). Ingravescent muscular atrophy was demonstrated with a progressive decrease in the fiber diameter and changes in the fiber type distribution with predominant type II atrophy in the first stage and type I atrophy in the later stage of the cord transection. Muscular “neurogenic” changes, such as angular dark atrophic fibers, targetoid fibers, and type predominance are frequently observed. Myopathic alterations are observed in a low percentage in the later stages of the lesion. The ultrastructural findings are characterized by myofibrillar alterations and by dilatation and proliferative phenomena of the sarcoplasmic reticulum and T-system. There are ingravescent accumulation of lipid, interstitial fibrosis and microcirculatory alterations. The possible mechanism of “central” muscle atrophy is reviewed and discussed with reference to the morphological findings.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00692178
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  • 16
    Electronic Resource
    Electronic Resource
    The ultrastructural development of distal nephron segments in the human fetal kidney (1982)
    Springer
    Anatomy and embryology 164 (1982), S. 19-41 
    Details
    ISSN: 1432-0568
    Keywords: Human kidney ; Nephron development ; Distal segments ; Electron microscopy ; Morphometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The ultrastructural development of the human distal nephron was studied in fetuses 14–18 weeks of gestational age. The three-dimensional course of the nephrons was traced in serial semi-thin sections. Single semi-thin sections containing defined distal nephron segments were then reembedded, thin-sectioned and analyzed by electron microscopy. In stage I (renal vesicle) and stage II (S-shaped body) epithelial cells were essentially similar in ultrastructure. In stage III there were only minor variations in cell ultrastructure between distal nephron segments, but distinct differences were observed between proximal and distal tubule cells, the former being the most differentiated. The segments which are present in nephrons of adult kidneys could be identified in stage IV and some ultrastructural differences recognized between the cells. However, the amplification of the baso-lateral membrane, which is prominent in iontransporting mature distal segments, was almost absent and the baso-lateral membrane area per unit tubule length was similar in all distal segments. Intercalated cells were present towards the end of the distal convoluted and in the connecting tubule in stage IV but the ampulla of the collecting tubule was composed of cells with a uniform ultrastructure. Cell ultrastructure varied again to some extent in the collecting tubule. The present observations demonstrate that distal nephron segments in the human kidney are structurally undifferentiated in the early fetal development and suggest that they only to a limited extent are capable of modifying the composition of the tubular fluid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00301876
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  • 17
    Electronic Resource
    Electronic Resource
    Ultrastructural evidence for inhibition of chitin synthesis by nikkomycin (1982)
    Springer
    Development genes and evolution 191 (1982), S. 205-207 
    Details
    ISSN: 1432-041X
    Keywords: Chitin inhibition ; Nikkomycin ; Cuticle ; Electron microscopy ; Epilachna varivestis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The nucleoside antibiotic nikkomycin has proved to be an effective inhibitor of chitin synthesis in the Mexican bean beetleEpilachna varivestis. Ultrastructural investigations show defects in the procuticular area after nikkomycin application which suggest the complete absence of chitin. A cuticle like this is inflexible and too brittle to satisfy its normal function as an exoskeleton. The individuals are not able to free themselves from the exuvia and finally die. Therefore nikkomycin seems to be a potential insecticide with high specifity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00848337
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  • 18
    Electronic Resource
    Electronic Resource
    Spongiform-like changes in Alzheimer's disease (1982)
    Springer
    Acta neuropathologica 56 (1982), S. 146-150 
    Details
    ISSN: 1432-0533
    Keywords: Alzheimer's disease ; Creutzfeldt-Jakob disease ; Spongiform changes ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The ultrastructural study of the cortex of four patients with sporadic or familial AD, of two agematched controls without dementia, and of one normal pressure hydrocephalus, revealed in all the cases in the neuropil only occasional vacuoles which had a morphology similar to those observed in CJD. The degree of spongiform-like changes was, however, far less prominent than in CJD and considered mild in all the cases examined. Moreover, curled fragments of membranes within the vacuoles were not observed. It is suggested that the mild vacuolization of the neuropil occasionally observed in cortical biopsies of AD is a non-specific finding and cannot be considered a neuropathologic link between AD and CJD.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00690586
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  • 19
    Electronic Resource
    Electronic Resource
    Central neurocytoma (1982)
    Springer
    Acta neuropathologica 56 (1982), S. 151-156 
    Details
    ISSN: 1432-0533
    Keywords: Central neuronal tumor ; Third ventricle tumor ; Synapses ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The authors report two cases of a rare tumor in adults which were inserted on the fornix and caused a frontal syndrome. By light microscopy, the tumors, highly calcified, were composed of small clear cells forming dense areas in a patchy fibrillary stroma. Electron microscopy revealed a striking neuronal differentiation with numerous synapses. These tumors, for which the term neurocytomas was proposed, were compared with the other CNS neuronal tumors described in the literature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00690587
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  • 20
    Electronic Resource
    Electronic Resource
    The effect of tetraphenylporphinesulfonate (TPPS) on muscle end-plates in mice (1982)
    Springer
    Acta neuropathologica 56 (1982), S. 201-206 
    Details
    ISSN: 1432-0533
    Keywords: Muscle end-plates ; Porphyric neuropathy ; Electron microscopy ; Morphometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Motor end-plates were studied in mice at various intervals after a single injection of a synthetic porphyrin, tetraphenylporphinesulfonate (TPPS). Ultrastructurally, excess accumulation of neurofilaments constituted the earliest abnormality. These were followed by atrophy of many nerve terminals and their separation from the postsynaptic area by interposed separation from the postsynaptic area by interposed Schwann cells. Five to 8 months after the injection some postsynaptic areas showed denervation and atrophy. These progressive changes in the nerve terminals were accompanied by secondary changes in the subneural apparatus. Morphometric analysis revealed marked atrophy of the end-plates and significant swelling of preterminal axons. The present findings are suggestive of partial denervation of muscle, occurring after the injection of a synthetic porphyrin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00690636
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  • 21
    Electronic Resource
    Electronic Resource
    Thylakoid centers: Structures associated with the cyanobacterial photosynthetic membrane system (1982)
    Springer
    Archives of microbiology 133 (1982), S. 97-99 
    Details
    ISSN: 1432-072X
    Keywords: Cyanobacteria ; Thylakoid centers ; Photosynthetic membranes/thylakoids ; Membranes ; Membrane biogenesis ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An ultrastructural study of four cyanobacteria (Anabaena cylindrica, Dermocarpa violaceae, Gleocapsa alpicola, Pleurocapsa minor) indicates the presence of previously undescribed thylakoid centers from which photosynthetic membranes (thylakoids) radiate. These peripherally located thylakoid centers are cylinders 30 nm wide by 320 nm long, consisting of globular subunits oriented in nonparallel stacked arrays. Thylakoids are attached to the outer surface of the cylinder along its longitudinal axis. Thylakoid centers appear to be functionally significant due to their structure, location and thylakoid association.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00413518
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  • 22
    Electronic Resource
    Electronic Resource
    Ultrastructural pathology of human lymphocytes in lysosomal disorders: a contribution to their morphological diagnosis (1982)
    Springer
    European journal of pediatrics 138 (1982), S. 179-185 
    Details
    ISSN: 1432-1076
    Keywords: Lymphocytes ; Metabolic disorders ; Inclusions ; Lysosomes ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Ultrastructural examination of peripheral lymphocytes was performed in 28 cases of various lysosomal diseases, including infantile, late infantile and juvenile neuronal ceroid-lipofuscinoses (NCL), mucopolysaccharidoses (MPS), juvenile and adult metachromatic leukodystrophies (MLD), GM1-gangliosidosis, one patient with presumed mucolipidosis type IV, mucolipidosis type III, and glycogenosis type II. Based on our own observations on the ultrastructure of lymphocytes in lysosomal disorders, our results may be divided into the following 3 groups: 1. pathological findings with specific inclusions: each type of NCL, presumed mucolipidosis type IV, glycogenosis type II; 2. pathological findings with vacuoles: types I-H, II, III-A and III-B, IV, VI-A and VI-B of MPS, GM1-gangliosidosis; 3. apparently no pathological findings: juvenile and adult MLD, mucolipidosis type III, GM2-gangliosidosis, Gaucher disease. These results led us to conclude that morphological investigations utilizing lymphocytes do not always offer sufficient diagnostic information although easy accessibility favors diagnostic ultrastructural studies of lymphocytes. Such morphological studies should be supplemented by diagnostic biochemical methods.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00441150
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  • 23
    Electronic Resource
    Electronic Resource
    Comparative studies onChlorella cell walls: Induction of protoplast formation (1982)
    Springer
    Archives of microbiology 132 (1982), S. 10-13 
    Details
    ISSN: 1432-072X
    Keywords: Calcofluor White ; Cell wall structure ; Chlorella ; Electron microscopy ; Protoplast ; Ruthenium Red
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Among 12 strains ofChlorella ellipsoidea, C. vulgaris, andC. saccharophila tested, 4 strains (1,C. ellpsoidea; 2,C. vulgaris; 1,C. saccharophila) formed osmotically labile protoplasts after treatment with mixtures of polysaccharide degrading enzymes. The relationship between enzymatical digestibility and structure or composition ofChlorella cell walls were studied by electron microscopy and staining techniques with some specific dyes. The cell wall structures of the 12Chlorella strains were grouped into three types: (1) with a trilaminar outer layer, (2) with a thin outer monolayer, and (3) without an outer layer. Protoplasts were formed only from the strains with a cell wall of Type 2. In the strains with a cell wall of Type 1, the outer layer protected the inner major microfibrillar layer against enzymatic digestion. The cell wall of Type 3 was totally resistant to the enzymes; the chemical composition of the cell wall would be somewhat different from that of other types.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00690809
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  • 24
    Electronic Resource
    Electronic Resource
    Cell wall degradation ofStaphylococcus aureus by lysozyme (1982)
    Springer
    Archives of microbiology 131 (1982), S. 116-123 
    Details
    ISSN: 1432-072X
    Keywords: Cell wall ; Wall degradation ; Lysozyme ; Autolysines ; Electron microscopy ; Staphylococcus aureus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In contrast to former findings lysozyme was able to attack the cell walls ofStaphylococcus aureus under acid conditions. However, experiments with14C-labelled cell walls and ribonuclease indicated that, under these conditions, lysozyme acted less as an muralytic enzyme but more as an activator of pre-existing autolytic wall enzymes. Electron microscopic studies showed that under these acid conditions the cell walls were degraded by a new mechanism (i.e. “attack from the inside”). This attack on the cell wall started asymmetrically within the region of the cross wall and induced the formation of periodically arranged lytic sites between the cytoplasmic membrane and the cell wall proper. Subsequently, a gap between the cell wall and the cytoplasmic membrane resulted and large cell wall segments became detached and suspended in the medium. The sequence of lytic events corresponded to processes known to take place during wall regeneration and wall formation. In the final stage of lysozyme action at pH 5 no cell debris but “stabilized protoplasts” were to be seen without detectable alterations of the primary shape of the cells. At the same time long extended ribbon-like structures appeared outside the bacteria. The origin as well as the chemical nature of this material is discussed. Furthermore, immunological implications are considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01053992
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  • 25
    Electronic Resource
    Electronic Resource
    Immunoglobulin production and secretion in bence jones protein myeloma and “nonsecretory” myeloma (1982)
    Springer
    Annals of hematology 45 (1982), S. 121-129 
    Details
    ISSN: 1432-0584
    Keywords: Multiple myeloma ; Immunoglobulin ; Electron microscopy ; Fluorescent antibody technique
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Using our electron microscopic method for polysome analysis and an immunofluorescent technique we studied Ig production and secretion by tumor cells in seven BJP myeloma patients and seven “nonsecretory” myeloma patients. In BJP myeloma Ig production and secretion is of three types: Type 1, only L-chains are synthesized and secreted; Type 2, the myeloma cells show fluorescence for H-chains, but upon polysome analysis there is no peak at polysomes corresponding to H-chain production; Type 3, the myeloma cells show fluorescence for H-chains, and polysome analysis shows two peaks corresponding to L- and H-chain production. Polysome analysis of “nonsecretory” myelomas show the presence of only very few membrane-bound polysomes and their distribution curves are entirely different from those of “ordinary” myeloma. Furthermore, the distribution patterns vary among seven cases. Results obtained by polysome analysis and immunofluorescent technique suggest that the “nonsecretory” myeloma could be divided into several subtypes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00319940
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  • 26
    Electronic Resource
    Electronic Resource
    Heat of fusion and lamellar structure of polyethylene single crystal mats (1982)
    Springer
    Colloid & polymer science 260 (1982), S. 564-569 
    Details
    ISSN: 1435-1536
    Keywords: lin. Polyethylene ; Single crystals ; Heat of Fusion ; DSC ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Recently published results for solution crystallized PE single crystals have shown, that the experimental heat of fusionΔH * is higher, if the solvent is exchanged to silicon oil (oil suspension samples) as compared with dried mats. This has been interpreted by the collapse of the original hollow pyramids during drying, inducing lateral defects within the lamellae. The present investigation does not confirm this unexpected result.ΔH * of dried mats (T c 66 to 91 °C) and of the corresponding oil suspension samples agree within the rather small limits of experimental error. The crystallinities as derived fromΔH *, density or WAXS are in excellent agreement. SEM micrographs of cold fractured dried mats show their spongy macromorphology, but TEM micrographs of stained ultra-thin sections reveal the lamellar morphology of the walls, consisting of curved lamellae and stacked hollow pyramides. If a dried mat is sintered at room temperature, a dense transparent film is obtained with a rather regular stacked morphology of large flat lamellae.ΔH * of these films agrees with that of the original mat.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01422587
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  • 27
    Electronic Resource
    Electronic Resource
    Biologic characterization of human bone tumors I. Ewing's sarcoma (1982)
    Springer
    Journal of cancer research and clinical oncology 104 (1982), S. 171-180 
    Details
    ISSN: 1432-1335
    Keywords: Ewing's sarcoma ; Type IV collagen ; Factor-VIII-associated protein ; Endothelial differentiation ; Electron microscopy ; Immunofluorescence microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Six cases of Ewing's sarcoma were investigated by electron and immunofluorescence microscopy. A layer of basement membrane-like deposits was found between typical principal and secondary tumor cells. To clarify the nature of these ultrastructural deposits, antibodies against collagen type IV were applied to frozen sections of corresponding tumor tissue. This reaction revealed type IV collagen as a regular component of basement membranes in nonneoplastic tumor capillaries, but it was equally able to localize collagen type IV between single tumor cells in capillary-free areas. With the same method, factor-VIII-associated protein, predominantly found in endothelial cells, could be demonstrated in some tumor cells. These results demonstrate that, in addition to anaplastic cells, some tumor cells are found in Ewing's sarcoma that share certain differentiating features with the endothelial cell.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00402065
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  • 28
    Electronic Resource
    Electronic Resource
    Morphologische Untersuchungen zur Toxizität der Ethacrynsäure an der Prominentia spiralis (1982)
    Springer
    European archives of oto-rhino-laryngology and head & neck 236 (1982), S. 217-228 
    Details
    ISSN: 1434-4726
    Keywords: Ethacrynic acid ; Spiral prominence ; Electron microscopy ; Ethacrynsäure ; Prominentia spiralis cochleae ; Elek tronenmikroskopie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Nach einmaliger intravenöser Ethacrynsäure-Applikation (40 mg/kg Körpergewicht) wurden die ultastrukturellen Veränderungen in der Prominentia spiralis der Meerschweinchenschnecke nach Einwirkungszeiten zwischen 5 und 90 min untersucht. Nach einer initialen Schwellung der den Endolymphraum begrenzenden Epithelzellen entwickelte sich ein interzelluläres Ödem und eine ausgeprägte Schrumpfung der das Vas prominens umgebenden Stromazellen mit nachfolgender Erweiterung des Perivascularraumes. Während die Veränderungen in der Stria vascularis und der Prominentia spiralis im zeitlichen Verlauf sich weitgehend identisch entwickelten, setzte die Rückbildung zur normalen Ultrastruktur in der Prominentia spiralis früher ein.
    Notes: Summary Ultrastructural changes in the guinea pig spiral prominence were studied at various times after a single intravenous injection of ethacrynic acid (40 mg/kg body-weight). Initial swelling of endolymph-facing epithelial cells was followed by dilatation of the intercellular spaces and marked shrinkage of the stroma cells surrounding the spiral prominence vessel. While the changes in the stria vascularis and the spiral prominence progressed at about the same pace, the regression to normal ultrastructure set in earlier in the spiral prominence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00454213
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  • 29
    Electronic Resource
    Electronic Resource
    Macromolecular transport in the spiral prominence (1982)
    Springer
    European archives of oto-rhino-laryngology and head & neck 236 (1982), S. 41-51 
    Details
    ISSN: 1434-4726
    Keywords: Prominentia spiralis cochleae ; Meerrettichperoxidase ; Elektronenmikroskopie ; Inner ear spiral prominence ; Horseradish peroxidase ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Transport of macromolecules in the spiral prominence of the guinea pig was studied after perilymphatic and intravenous horseradish peroxidase (HRP) injection. HRP was taken up by the spiral prominence epithelium from the perilymphatic space and in a much higher degree from the endolymphatic space. A highly endocytic ativity was shown by the stroma cells surrounding the spiral prominence vessel. HRP particles were stored in the cytoplasm within vesicles and vacuoles of different sizes and different contrasts. The mode of tracer storage in the spiral prominence epithelium and in the stroma cells from the morphological point of view suggests lysosomal digestion. HRP was transported from the perilymphatic space into the spiral prominence vessel lumen by means of vesicular transport through the vessel wall, while transport of the tracer from the vessel lumen into the perilymphatic space after intravenous injection was not observed.
    Notes: Zusammenfassung Nach perilymphatischer und intravenöser Applikation von Meerrettichperoxidase wurde der Transport des Makromoleküls in der Prominentia spiralis des Meerschweinchens verfolgt. Die Tracer-Partikelchen wurden aus dem perilymphatischen Raum und vornehmlich jedoch aus dem Ductus cochlearis in das Oberflächenepithel der Prominentia spiralis aufgenommen. Die das Vas prominens umgebenden Stromazellen nahmen relativ viel Meerrettichperoxidase auf, die im Zytoplasma in unterschiedlich großen und unterschiedlich kontrastreichen Vesikeln und Vakuolen abgelagert wurde. Die Art der zytoplasmatischen Ablagerung des Tracers in den Epithelzellen und den Stromazellen spricht vom morphologischen Aspekt her für einen lysosomalen Abbau. Meerrettichperoxidase wurde von der Perilymphe in das Lumen des Vas prominens transportiert. Dieser Transport erfolgte vesikulär durch das Gefäßendothel. Ein Transport des Tracers in umgekehrter Richtung wurde nach intravenöser Applikation nicht beobachtet.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00464056
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  • 30
    Electronic Resource
    Electronic Resource
    Elektronenmikroskopische Befunde am Bindegewebe von Nervus und Ganglion vestibuli bei Morbus Menière (1982)
    Springer
    European archives of oto-rhino-laryngology and head & neck 236 (1982), S. 67-79 
    Details
    ISSN: 1434-4726
    Keywords: Menière's disease ; Vestibular nerve ; Vestibular ganglion ; Pathologic alterations ; Electron microscopy ; Morbus Menière ; Nervus vestibularis ; Ganglion vestibuli ; Pathologische Veränderungen ; Elektronenmikroskopie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Vestibularisganglien von 17 Patienten mit einem Morbus Menière wurden nach transtemporaler oder translabyrinthärer Neurektomie elektronenmikroskopisch untersucht. Als Vergleichsmaterial dienten drei Ganglien, die bei anderer Indikation entnommen wurden und vier postmortale Entnahmen von Ohrgesunden. Bei allen Menière-Präparaten zeigten sich am Bindegewebe gleichartige pathologische Veränderungen von unterschiedlich starkem Ausmaß. Sie bestanden in einer Zunahme des Kollagens, wobei sowohl unterschiedliche Kaliber des Faserquerschnittes als auch Veränderungen der Periodizität der Querstreifung beobachtet wurden. Aktive Fibroblasten und reaktive Schwannsche Zellen, die isoliert lagen, keinem Axon zugeordnet waren und deren z. T. hirschgeweihförmig verzweigte, dünne Zellausläufer Kollagenbündel umhüllten, wurden als Zeichen einer noch ablaufenden Kollagenbildung gedeutet. Die Blutgefäße wiesen häufig eine Vervielfachung der Basalmembran auf, die von einem mehrfach breiteren Saum einer homogenen Matrix umgeben war. Die Perizyten waren oft entweder nekrotisch oder teilweise nicht mehr zu beobachten. Die Endothelzellen wiesen in der Regel kein aktives Zytoplasma auf. Sie erschienen teilweise autolytisch. Die pinozytotische Aktivität erwies sich als auffallend verringert. Diese qualitativen Veränderungen im interstitiellen Gewebe könnten auf ein primär lokales pathologisches Geschehen im Bereich des Nerven und des Ganglions hinweisen.
    Notes: Summary Vestibular ganglia of 17 patients with Menière's disease, obtained by transtemporal or translabyrinthine neurectomy, were studied by electron microscopy. Three ganglia removed because of other disease and four ganglia of normal ears taken post mortem served as controls. The neuronal fibrous tissue of Menière cases showed without exception pathologic changes of various extent. The amount of collagen was increased, whereby different fiber diameters were observed as well as changes in the periodicity of cross banding. Signs of continuing collagen formation were found: active fibroblasts and an increased number of isolated Schwann cells without axons, showing deerhorn-like ramifications which enveloped collagen bundles. The blood vessels were frequently surrounded by multiple basal membranes and broad bands of homogenous matrix. The pericytes were either necrotic or nonexistent. The endothelial cell cytoplasma was usually not in an active state. Sometimes it seemed to be autolytic. The pinocytotic activity was strikingly diminished. These qualitative changes of the interstitial tissue might point to a local pathologic event in the region of the vestibular nerve and ganglion.
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    URL: http://dx.doi.org/10.1007/BF00464059
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  • 31
    Electronic Resource
    Electronic Resource
    Tubular aggregates in skeletal muscle of chronic alcoholic patients (1982)
    Springer
    Acta neuropathologica 56 (1982), S. 250-254 
    Details
    ISSN: 1432-0533
    Keywords: Skeletal muscle ; Chronic alcoholism ; Tubular aggregates ; Histochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The presence of tubular aggregates (TA) in type II muscle fibers in two of 20 alcoholic patients with chronic liver disease, and with no apparent neuromuscular disorder, is reported. The localization, histochemical reactions, and ultrastructural features of the TA are similar to those previously described in other conditions. In one of the two cases TA were demonstrated by E/M observations only and not by histochemistry. No correlations were found between the biochemical changes and the presence of tubular aggregates. We believe that TA are long-standing structures since the muscle biopsies were performed 12 and 13 days after the ingestion of alcohol had been discontinued. They may represent a non-specific response of the sarcoplasmic reticulum to compensate for the deficient calcium uptake reported in alcoholic patients.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00691255
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  • 32
    Electronic Resource
    Electronic Resource
    Oculopharyngeal dystrophy: Ultrastructure of muscles distant from the primary myopathy (1982)
    Springer
    Acta neuropathologica 57 (1982), S. 7-12 
    Details
    ISSN: 1432-0533
    Keywords: Oculopharyngeal muscular dystrophy ; Electron microscopy ; Pectoral and psoas muscles ; Myofibrillar degeneration ; A band fragmentation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The pectoral and psoas muscles from a 72-year-old man afflicted with oculopharyngeal muscular dystrophy were processed at autopsy for electron microscopy. The ultrastructural analyses of the pectoral muscle showed myofibrils which exhibited Z line streaming and a general breakdown in the organization of the sarcomere. In addition, some of the myofibrils displayed sites of degeneration at the center of the A band. The changes in the psoas muscles which are distant from the primary myopathic loci of oculopharyngeal muscular dystrophy were more extensive than that seen in the pectoral muscle. Control tissues showed intact myofibrils and little postmortem alteration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00688872
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  • 33
    Electronic Resource
    Electronic Resource
    Zur Feinstruktur der Nervenendigungen in den Muskelspindeln des M. lumbricalis der Ratte nach Durchschneidung des Nerven (1982)
    Springer
    Acta neuropathologica 57 (1982), S. 23-36 
    Details
    ISSN: 1432-0533
    Keywords: Muscle spindle ; Electron microscopy ; Nerve endings ; Denervation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The nerve endings in muscle spindles from lumbricalis muscles of the hindpaw of the rat were studied by electron microscopy from 10 h to 7 days after section of the sciatic nerve. No sensory endings were found after 5 days and no motor endings after 3 days. Early changes in sensory endings included accumulation of lamellar bodies, mitochondrial swelling or shrinkage, an edematous appearance of the cytoplasm and disruption of membranes. The predominant way of removal was phagocytosis by activated mesenchymal cells; other endings were incorporated into the sarcoplasm as electrondense bodies. Early changes in motor endings included aggregation or swelling of synaptic vesicles, swelling or shrinkage of mitochondria, edematous change of the cytoplasm and disruption of membranes. The predominant way of removal was incorporation into the cytoplasm of adjacent Schwann cells and degradation to phagolysosomes. Sites of removed sensory endings could be identified by basement membrane reduplication, while the intact subsynaptic apparatus of removed motor endings was either loosely covered by Schwann cell processes, or by fibrillar material, or appeared empty. The differences in the removal of motor and sensory endings are explained by the differences in their anatomic structure.
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    URL: http://dx.doi.org/10.1007/BF00688874
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  • 34
    Electronic Resource
    Electronic Resource
    An electron-microscopic study of the brain of the fruit fly,Drosophila melanogaster, exposed to high-LET krypton (84Kr) particle radiation (1982)
    Springer
    Acta neuropathologica 57 (1982), S. 37-44 
    Details
    ISSN: 1432-0533
    Keywords: Radiation effects ; Nervous system ; Drosophila melanogaster ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Fruit flies (Drosophila melanogaster) were exposed to high-LET krypton (84Kr) ions at low (4.2 rad) and high (1,584 rad) doses and killed to assess acute (36 h post-exposure) and late (35 days post-exposure) effects in the brain by means of electron microscopy. The main findings were: (a) glycogen granules appeared in the neuroglial compartment 36 h after exposure to either dose and were no longer present in flies killed 35 days later, (b) neuronal alterations (swelling and membrane disruption) were observed 35 days after exposure to both doses, (c) changes in the neuroglia (electron-dense masses of concentrically arranged membranous structures) were seen 35 days after exposure. The data are discussed in relation to previous research in the fruit fly using argon (40Ar) charged particles and to other radiation studies performed in the mammalian brain with the view of using the insect brain as a model for detailed study of radiation effects on neurons, neuroglia, and the neuron-neuroglia unit.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00688875
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  • 35
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    Electronic Resource
    Cerebrovascular pathogenesis in the telencephalon of the loop-tail mouse: A transmission electron-microscopic study (1982)
    Springer
    Acta neuropathologica 58 (1982), S. 177-182 
    Details
    ISSN: 1432-0533
    Keywords: Cerebral vessels ; Telencephalon ; Looptail mutant mouse ; Pathogenesis ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Cerebral capillaries in the telencephalon of normal (+/+;Lp/+)_and abnormal (Lp/Lp) loop-tail mutant mice were studied chronologically by means of electron microscopy at stages ranging from 15 through 18 days of gestation. In the abnormal tissue, neural rosettes were common, and cellular material and red blood cells were often contained within the lumen of the rosettes. The endothelial cells of telencephalic blood vessels in the abnormal brains showed a persistence of cellular projections, subluminal vacuoles, and swollen mitochondria beyond the stage when these features ordinarily disappear in normal embryonic cerebral vessels. The endothelial cells in the abnormal brains also failed to become fully invested with pericytes, and red blood cells gradually infiltrated the neural tissue, particularly in subependymal regions, at 16–18 days of gestation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00690798
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  • 36
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    Electronic Resource
    Hirano bodies in myelinated fibers of hepatic encephalopathy (1982)
    Springer
    Acta neuropathologica 58 (1982), S. 307-310 
    Details
    ISSN: 1432-0533
    Keywords: Hirano body ; Hepatic encephalopathy ; Oligodendroglia ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Inclusions, essentially identical to Hirano bodies, were observed in the substantia nigra, dentate nuclei, and frontal lobes in three autopsy cases of hepatic encephalopathy. Similar inclusions were not observed in these areas in nine controls. The inclusions were mainly seen in the inner loops of the myelinated fibers, between the myelin lamellae, and among degenerated myelin sheaths. The same inclusions were rarely observed in postsynaptic terminals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00688615
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  • 37
    Electronic Resource
    Electronic Resource
    Long-term study of liver damage following subcutaneous injection of airborne particle extracts and polycyclic aromatic hydrocarbon fractions (1982)
    Springer
    International archives of occupational and environmental health 49 (1982), S. 305-314 
    Details
    ISSN: 1432-1246
    Keywords: Polycyclic aromatic hydrocarbon ; Liver ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Female NMRI mice aged 9–12 weeks were each given a single subcutaneous injection of 0.5 ml of a suspension containing either the total extracts or the polycyclic aromatic hydrocarbon (PAH) fraction of airborne particles. Both the total extracts and PAH fractions contain 3 Vg benzopyrene. After about 15 months the livers were removed from the animals, which had by that time developed tumors at the injection site, and were subjected to ectronmicroscopical study. The essential alterations were observed in the nucleoli and the cell nuclei, which had greatly proliferated and exhibited irregular nuclear membranes. Advanced fibrosis was observed in central liver specimens of all groups. Marked alterations were also observed in the mitochondria and the mitochondria) cristae as well as in the bile canaliculi. Intracytoplasmic glycogen usually occurred densely clustered along the periphery of the cell. It may be concluded from the observations that both the total extract of atmospheric suspended particulate matter and the PAH fraction cause hematogenic damage to the liver following subcutaneous injection, a finding which cannot be interpreted as metastatic carcinoma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00377939
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  • 38
    Electronic Resource
    Electronic Resource
    Observations on the ultrastructure of human urothelium: The response of normal bladder of elderly subjects to hyperthermia (1982)
    Springer
    Urological research 10 (1982), S. 227-237 
    Details
    ISSN: 1434-0879
    Keywords: Human ; Bladder urothelium ; Electron microscopy ; Hyperthermia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An electron microscopic study of normal bladder urothelium of elderly subjects treated by hyperthermic perfusions has shown that the tissue responds, sooner or later, in every instance by desquamation. There is no evidence of cell death prior to desquamation although various organelles undergo structural alterations. Mitochondria are especially prone to suffer varying degrees of damage. A short heat shock has revealed differences in the initial response of the thick and thin regions of bladder urothelium known to occur in elderly subjects. After a long, fractionated treatment, regeneration is evident within 3 daysof the end of treatment, and follow-up biopsies have revealed a hyperplastic urothelium within 10 to 12 weeks. The constituent cells show signs of cytodifferentiation at this time but it remains unknown when an ultrastructurally normal urothelium with characteristic cell layers will be restored. The various treatments in this study suggest that the stem cells in the epithelium are unaffected by the levels of hyperthermia employed and that their unimpaired proliferative capacity ensures regeneration of the urothelium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00255928
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  • 39
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    Electronic Resource
    Sensory organs inIps typographus (Insecta: Coleoptera) — Fine structure of antennal sensilla (1982)
    Springer
    Protoplasma 111 (1982), S. 206-214 
    Details
    ISSN: 1615-6102
    Keywords: Bark beetle ; Sensilla ; Chemoreceptors ; Mechanoreceptors ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The antennal sensilla inI. typographus are almost exclusively confined to the flattened terminal flagellar segment. The sensillar types have distinct distribution patterns in the three areas where they are found. Judging from the ultrastructural characteristics the following functions can be assigned to the sensillar types: chemoreception, single-walled and double-walled sensilla; chemoreception/mechanoreception, terminal-pore sensillum. Moreover there are two types of mechanoreceptors, one of which is connected to a bristle, whereas the other terminates within the cuticle of the flagellar segment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01281968
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    Ultrastructure of endocrine cells in the stomach of two teleost fish Perca fluviatilis L. and Ameiurus nebulosus L. (1982)
    Springer
    Cell & tissue research 221 (1982), S. 657-678 
    Details
    ISSN: 1432-0878
    Keywords: Stomach (Teleost) ; Endocrine cells ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the gastric mucosa of two teleost species, the perch (Perca fluviatilis) and the catfish (Ameiurus nebulosus) three endocrine cell types were found, located predominantly between the mucoid cells of the gastric mucosa. A fourth cell type is present in the gastric glands of catfish. Each cell type was defined by its characteristic secretory granules. Type-I cells were predominant in both fish. These cells contained round or oval granules with a pleomorphic core. The average diameter of granules was 400 nm for the perch and 270 nm for the catfish. Type-II cells of both species displayed small, highly osmiophilic granules about 100 nm in diameter. The secretory granules of type-III cells (260 nm in the perch and 190 nm in the catfish) were round or slightly oval in shape and were filled with a finely particulate electron-dense material. Type-IV cells of the catfish were found in the gastric glands only. Their cytoplasm was filled with homogeneous, moderately electron-dense granules averaging 340 nm in diameter. The physiological significance of these different morphological types of gastric endocrine cells requires further investigation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00215709
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  • 41
    Electronic Resource
    Electronic Resource
    Paddle cilia (discocilia) in chemosensitive structures of the gastropod mollusk Pleurobranchaea californica (1982)
    Springer
    Cell & tissue research 222 (1982), S. 25-40 
    Details
    ISSN: 1432-0878
    Keywords: Paddle cilia ; Discocilia ; Pleurobranchaea ; Chemoreceptors ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Scanning electron microscopy of various regions of the body of the marine gastropod Pleurobranchaea californica (McFarland) has revealed a characteristic cell type that bears cilia with dilated discoid-shaped tips. The tips of the cilia consist of an expansion of the ciliary membrane around a looped distal extension of the axoneme. These kinocilia have been observed in numerous other marine invertebrates and are generally referred to as paddle cilia (Tamarin et al. 1974) or discocilia (Heimler 1978). Although many functions have been proposed for paddle cilia, little empirical evidence supports any of the proposals. In Pleurobranchaea we have found that the distribution of this ciliated cell type corresponds exactly to areas of the body known from behavioral studies (Lee et al. 1974; Davis and Matera 1981) to mediate chemoreception. Transmission electron microscopy of the epithelium lining the rhinophores and tentacles of Pleurobranchaea revealed details of the ultrastructure of these ciliated cells and showed that they are primary receptors. These ciliated receptors lie in a yellow-brown pseudostratified columnar epithelium that superficially resembles the olfactory mucosa of vertebrates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00218286
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  • 42
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    Electronic Resource
    Pigment biogenesis in freshwater shrimp ventral nerve chord chromatophores (1982)
    Springer
    Cell & tissue research 222 (1982), S. 167-175 
    Details
    ISSN: 1432-0878
    Keywords: Pigment granules ; Chromatophores ; Granulogenesis ; Palaemonid shrimp ; Macrobrachium ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The possible biogenesis of two pigment granule types present in the monochromatic, brown chromatosomes enveloping the ventral nerve chord of the freshwater palaemonid shrimps Macrobrachium acanthurus, M. heterochirus and M. olfersii is examined by transmission electron microscopy in thin section and freeze fracture replicas. Prominent, membrane limited granules are suggested to have their origin in a complex, juxtanuclear, smooth endoplasmic reticulum labyrinth, continuous with the nuclear envelope. Amembranous, lipocarotenoid granules possibly derive from the external surface of the smooth endoplasmic reticulum. Nuclear envelope and SER membranes contain numerous 11 nm diameter intramembranous particles while pigment granule membranes exhibit fewer particles. A dictyosomal origin for the lipocarotenoid granules is discounted. Granulogenesis is suggested to be a continuous process in crustacean chromatophores.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00218297
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  • 43
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    Electronic Resource
    Apical region of the crayfish retinula (1982)
    Springer
    Cell & tissue research 222 (1982), S. 409-415 
    Details
    ISSN: 1432-0878
    Keywords: Crustacean compound eye ; Eighth retinular cell ; Crystalline tract ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The base of the crystalline tract, the distal part of the eighth retinular cell and its rhabdomer constitute a structural unit in the apical region of the retinula of Astacus fluviatilis and A. leptodactylus, shielded from the blood by a special covering cell.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00213221
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  • 44
    Electronic Resource
    Electronic Resource
    Cellular interconnections in the young mouse ovary (1982)
    Springer
    Cell & tissue research 224 (1982), S. 383-395 
    Details
    ISSN: 1432-0878
    Keywords: Mouse ovary ; Junctions ; Freeze-fracture ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Intercellular junctions in the young mouse ovary were examined by electron microscopy utilizing freeze-fracture and thin-sectioning techniques. Projections from the granulosa cells adjacent to the oocyte (GI) traverse the zona pellucida and form small gap junctions on the oocyte surface. On the P-face of these cells, the junctional aggregations are occasionally associated with linear strands of particles. In contrast, large gap junctional areas are frequently observed between the more peripherally located granulosa cells (GE) and are also present in the theca interna (TI) cell layer surrounding the follicles. Three types of tight junctional strands are discernible on the P-face of theca externa cells (TE): angularly zigzag strands consisting of intermittently distributed intramembranous particles on wide ridges, intermediate zigzag strands consisting of more continuously distributed particles, and wavy strands consisting of rather fused particles. Tight junctional strands are also present in the middle of grooves on the E-face of endothelial cells of blood vessels. In the germinal epithelial cell layer, tight junctional strands appear to be discrete and form a less anastomosing network.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00216881
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  • 45
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    Electronic Resource
    Ultrastructure of the pars intermedia of the developing sheep hypophysis (1982)
    Springer
    Cell & tissue research 224 (1982), S. 369-381 
    Details
    ISSN: 1432-0878
    Keywords: Pituitary gland ; Pars intermedia ; Electron microscopy ; Fetal sheep ; Lamb
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Using light and electron microscopy, the morphogenesis of the pars intermedia of the sheep pituitary gland was examined in developing lambs between 26 days of gestation and the newborn stage. Following the establishment of contact between the anterior and posterior lobe primordia seen at 26 days, the connection with the pharyngeal roof disappeared by 31 days. The lumen of Rathke's pouch, which was a prominent cavity at the earlier stages, became inconspicuous by 40 days but progressively increased in size during gestation and, in some newborn animals, contained colloid material. At 40 days, the pars intermedia consisted of a uniform population of undifferentiated cells. Cells with cytoplasmic granules were first identified at 50 days. The cytological appearance of granular cells at 70 days indicated increased synthetic activity and by 80 days they closely resembled adult glandular cells. At 100 days, membrane activity suggestive of exocytosis was first observed in granular cells; fenestrated capillaries were present, and early follicle formation between adjacent non-granular cells was seen. This apparent exocytotic release of granules was observed much more frequently between 100 days of gestation and the newborn stage than in adult pars intermedia cells. These findings indicate that glandular cells of the developing pars intermedia are actively engaged in synthesis, storage and secretion from an early stage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00216880
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  • 46
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    Electronic Resource
    Electron-microscopic localization of A2B5 cell surface antigen in monolayer cultures of murine cerebellum and retina (1982)
    Springer
    Cell & tissue research 224 (1982), S. 637-645 
    Details
    ISSN: 1432-0878
    Keywords: Cell surface antigen ; Neurons ; Glia ; Electron microscopy ; Immunoperoxidase ; Monoclonal antibody
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Immuno-electron microscopy was performed on live, cultured, early postnatal cerebellar and retinal cells of the mouse to identify A2B5 antigenbearing elements. In cerebellar cultures, granule cells, some immature oligodendroglia, and astroblasts express A2B5 antigen on their cell surfaces. The typical features of astroblasts include large cisternae of the endoplasmic reticulum and a mixed population of intermediate-sized filaments and microtubules. Immature oligodendroglia cells express the antigen on their cell bodies and on procecesses filled with cytoplasm. Cytoplasm-free membranous whorls, however, are devoid of A2B5 antigen, but not of 0 or NS-1 antigens. In retinal cultures, A2B5 antigen is observed on differentiating neurons with the exception of photoreceptor cells as identified by ribbon synapses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00213758
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  • 47
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    Electronic Resource
    Survival of Pacinian corpuscles after denervation in adult rats (1982)
    Springer
    Cell & tissue research 224 (1982), S. 673-683 
    Details
    ISSN: 1432-0878
    Keywords: Pacinian corpuscles, rat ; Denervation ; Sensory terminals ; Nerve degeneration ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of Pacinian corpuscles located on the crural interosseous membrane was studied in adult rats 6 h to 10 months after transection of the right sciatic nerve. Axon terminals degenerated one day after transection and were engulfed and resorbed by cells of the inner core within one week. The axial space left after removal of the axonal debris was closed by the lamellae of the inner core. The main structural features of the inner core and capsule remained preserved after denervation throughout the period of study. The denervated inner cores, however, became atrophic 10 months after neurotomy, their mean diameter being reduced by 17.5% compared with that of contralateral control corpuscles. The number of capsular lamellae was unaltered, and perineurial pathways of the peripheral nerve stump remained preserved. Schwann cells proliferated and formed Büngner bands during the first month after denervation, but retracted their processes and became atrophic at later stages after neurotomy. Survival of Pacinian corpuscles after long-term denervation in adult rats is in contrast to their rapid degeneration within several days after nerve section in neonates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00213762
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  • 48
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    Electronic Resource
    Endometrial ultrastructure in the early uterine response to blastocysts and artificial deciduogenic stimuli in rats (1982)
    Springer
    Cell & tissue research 225 (1982), S. 355-364 
    Details
    ISSN: 1432-0878
    Keywords: Implantation ; Blastocyst ; Pontamine ; blue reaction ; Decidualization ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The early uterine response to transplanted, delayed and estrogenactivated blastocysts was studied ultrastructurally and compared with that induced by intrauterine instillations of deciduogenic agents (arachis oil, air). The uterine responses to delayed and activated blastocysts showed no ultrastructural or temporal differences. Already within 4 h after transfer to a sensitized uterus, the delayed blastocysts exhibited signs of activation, and both types of blastocysts had started to attach onto an undamaged epithelial lining. Signs of stromal cell differentiation into decidual cells were also seen as early as 4 h after transfer, while the Pontamine-blue reaction did not appear until after 8 h. The results therefore indicate that the transplanted blastocysts induced decidualization atraumatically and that the delayed blastocysts were either deciduogenic already before transfer or rapidly acquired deciduogenic properties after transfer. Artificial decidual induction with oil and air led to damage or death of a large number of cells in the uterine luminal epithelium. Within only 15 min after instillation pronounced signs of cell damage were seen, and later numerous cells were extruded from the epithelial lining. In the stroma ultrastructural signs of decidual cell differentiation and a Pontamine-blue reaction were observed as early as 4 h after induction. It is therefore suggested that oil and air induce decidualization via the epithelium by means of trauma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00214688
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  • 49
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    Electronic Resource
    Cells and intercellular contacts in glomeruli and tubules of the frog kidney (1982)
    Springer
    Cell & tissue research 226 (1982), S. 589-608 
    Details
    ISSN: 1432-0878
    Keywords: Kidney (frog) ; Glomerulus ; Nephron ; Tight junctions ; Freeze-fracturing ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary By the use of thin sections and freeze-fracture replicas the glomerular and tubular structures of the kidney of the frog (Rana esculenta) were studied with special reference to intercellular junctions. In the glomerulus the filtration barrier is of very variable thickness, and frequent tight and gap junctional contacts occur between podocyte processes. Although structurally less elaborate, the proximal tubule resembles its mammalian counterpart. In the initial part the tight junctions are relatively shallow but become very broad in the mid and distal portions of the proximal tubule. The proximal tubular cells are extensively linked by gap junctions. In some animals the shapes of the cells in the proximal and distal portions of the proximal tubule were markedly different. The distal tubule consists of two segments which differ mainly in the pattern of interdigitations and the structure of the zonulae occludentes. Similarities with the tight junctional morphology of the mammalian distal tubule are striking. In the first part of the distal tubule (diluting segment) a narrow band of parallel tight junctions is found closely resembling that found in the mammalian straight distal tubule; in the more distal part of the distal tubule, however, a broad band of anastomosing tight junctional strands exists, like the zonula occludens of the mammalian convoluted distal tubule. The connecting tubule displays cellular dimorphism: its wall contains a mixture of light and dark (flask) cells. The luminal and basolateral membranes of the flask cells are covered with numerous rod-shaped particles. The tight junctions of the connecting tubule are broad and increase in depth and number of strands along its length; they are typical of a very tight epithelium. In spite of several dissimilarities with phylogenetically younger kidneys our findings suggest that many structural principles of the mammalian kidney are also represented in the kidneys of amphibians. The structural-functional relationships are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00214787
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  • 50
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    Electronic Resource
    Close apposition of muscle cells in the longitudinal bands of the body wall of a holothurian, Isostichopus badionotus (1982)
    Springer
    Cell & tissue research 227 (1982), S. 465-473 
    Details
    ISSN: 1432-0878
    Keywords: Electron microscopy ; Junctions ; Smooth muscle ; Echinodermata ; Holothuria, Aspidochirotida
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Electron microscopy reveals that sarcolemmata of adjacent muscle cells form pentalaminar junctions by fusion of apposed trilaminar double leaflet membranes. These junctions appear to be candidates for low resistance pathways between muscle fibers. The muscles depolarize slowly when bathed in solutions containing elevated concentrations of KCl, and the sucrose gap method can then be used to measure the potential difference between polarized and depolarized regions. Thus the junctions which we have observed may provide the structural basis for electrical transmission through the sucrose gap.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00204778
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  • 51
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    Electronic Resource
    Splenic white pulp as a thymus-independent area in the African clawed toad, Xenopus laevis (1982)
    Springer
    Cell & tissue research 226 (1982), S. 327-335 
    Details
    ISSN: 1432-0878
    Keywords: Xenopus ; Spleen ; B-lymphocyte ; Immunofluorescence ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary An indirect immunofluorescence study of the frozen sections of the spleen of an anuran amphibian, Xenopus laevis, showed that lymphocytes bearing a small amount of immunoglobulin (Ig) were localized mostly in the white pulp of non-immunized toads. There were fewer fluorescent cells in the red pulp. In the toads hyperimmunized with human gamma globulin (HGG), cells with strong cytoplasmic fluorescence increased significantly in the outer part of the white pulp. Electron microscopy of spleens from these toads showed that plasma cells at different stages of maturation were abundant in the white pulp, whereas in the red pulp, a smaller number of maturer plasma cells were observed. These results indicate that, in contrast with its mammalian counterpart, the splenic white pulp of this anuran is the site where thymusin-dependent lymphocytes commence blast formation and transformation into plasma cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00218363
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  • 52
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    Electronic Resource
    Modeling of polymeric film-blowing processesPresented at the 52nf Annual Meeting, Society of Rheology, February 1981. (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 172-181 
    Details
    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: Industrial film-blowing processes are characterized by large deformation rates, rapid changes of temperature and high stress levels. A pilot scale process was set up to simulate these variables. The pivotal element in modeling the process is a rheological constitutive equation which describes the fluid properties accurately over the entire range of conditions encountered; it was found that contributions to the stress in the material which arise out of the changing thermal history of a fluid element were a significant fraction of the total. When the deforming film is subjected to stretching but to little or no blowing, the axial stresses in the film are predicted excellently by the model under both isothermal and non-isothermal processing conditions. With rapid blowing and major deviations from uniaxial extension, the axial stresses are predicted less well, but still satisfactorily, under the conditions used. In no case are the circumferential stresses predicted accurately: i.e. unequal biaxial extensional deformations represent complications which have not been resolved.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760220307
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  • 53
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    Electronic Resource
    A dynamic mechanical study of the curing reaction of an unsaturated polyester (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 254-259 
    Details
    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 curing process of an unsaturated polyester was followed by employing the dynamic spring analysis (DSA) technique attached to the Rheovibron viscoelastometer. The storage and loss moduli and the gel times of the resin with various concentrations of initiator (methyl ethyl ketone peroxide) were determined at several temperatures. The activation energy for the curing process studied was about 40 kJ/mol. Temperature effects on films partially cured below the ultimate glassy transition temperature (Tg) were studied similarly using the tensile mode on the Rheovibron from room temperature to 120°C. Two modulus peaks were observed upon heating and these were independent of precure conditions. The lower temperature peak was the result of continued curing and the higher temperature peak was attributed to the glassy relaxation of the cured product. The DSA technique were found to be useful for characterization of the curing process and the results showed good qualitative agreement with those obtained by tensile measurements using cast films when the shapes of the curves were compared.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760220407
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  • 54
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    Property-morphology relationships of polymethylmethacrylate/polyvinylidenefluoride blends (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 234-240 
    Details
    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: An investigation was conducted to establish property-morphology relationships in polymethylmethacrylate/polyvinylidenefluoride (PMMA/PVDF) blends. All blends were compounded in a twin-screw extruder and then processed by injection molding Mechanical properties of blends of various compositions were studied by dynamic mechanical and impact strength measurements. The presence of crystalline regions in blends was determined by Differential Scanning Calorimetry (DSC). Morphology of fracture surfaces of blends was studied by Spinning Electron Microscopy (SEM). PMMA/PVDF blends were found to form compatible mixtures over a wide range of blend composition. Changes in dynamic mechanical properties upon annealing were found to be a direct function of blond morphology. Electron microscopic evidence showed no signs of phase separation. DSC measurements detected crystalline regions in all blends containing 40 percent or more (by weight) PVDF.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760220404
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  • 55
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    The limiting pressure-velocity (PV) of plastics under unlubricated sliding (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 248-253 
    Details
    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 limiting pressure-velocity (PV) of plastics materials under normal contacting pressure P and sliding velocity V when the sliding goes on continuously unlubricated has been discussed theoretically in this study. The sliding friction tests between the rotating edge of a hollow cylinder against a stationary metal surface were carried out in room air and when the metals were cooled with circulating water.The results obtained were as follows: The relation between PVmax and the critical temperature τbmax of the surface above which ordinary frictional conditions are not maintained may be represented by the following formula, \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} {{\rm PV}_{max} = C(\tau _{bmax } - \tau _a)} & {(1)} \\ \end{array} $$\end{document} Where C = Hn/μk, and H is the mean total heat conductivity between materials and environment in cal/cm2. °C · s, n the area ratio of heat radiation surface to frictional surface, μ the kinetic frictional coefficient, k the thermal equivalent of frictional work in cal/kg · cm · s, and τa the cooling or environment temperature.The value of C ranges from 1 to 10 in cal/kg · cm s · °C, and the value of PVmax from 45 to 750 in kg/cm2 · cm/s under prevailing room temperature air cooling in this experiment, however, the value of C has been increased about 2.3 times as much as those values by circulating water of 2°C around the lower side of the test piece.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760220406
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  • 56
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    Electronic Resource
    Solid-phase backward extrusion of thermoplastics (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 269-279 
    Details
    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 backward extrusion process was studied as a means of forming projections and ribs on flat sections of thermoplastic parts. The simplified, open-die axisymmetric and plane-strain extrusion cases were mainly considered. The results were applied to the development of a continuous solid-phase-forming process. Commercial-grade polycarbonate (PC), polypropylene (PP), and polystyrene (PS) were used in the investigation. The projection height and extrusion loads in the unconstrained extrusion were measured as a function of the initial temperature of the material, the load hold time, and geometric variables. Cold dies were used in the experiments, and the samples were kept below their melt temperatures. The dimensional recovery of the flange section of the formed samples was also measured as a function of the hold time for given initial temperature and geometric variables. The slab and the upper-bound methods-in plasticity analysis were used to theoretically derive the projection heights and forming loads. The degree of correlation between the predictions and the experimental results depended on the estimates used for the frictional factors at the interfaces between the deforming material and the dies.
    Additional Material: 21 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760220502
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  • 57
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    Electronic Resource
    Effect of compaction rate during the cold forming of polymeric powders (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 300-306 
    Details
    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 many plastics processing methods, both conventional and novel, plastic powders or granules are subjected to pressure. The pressure transmissibility through the powder has an important effect on the success and efficiency of the process, and so it is desirable to be able to predict the pressure at any point from a knowledge of the applied pressure and the geometry of the system. To examine this pressure transmissibility effect, poly(vinylidene chloride) powder has been compacted in a metal die under different rates using either load or displacement control. It has been found that rate effects are particularly important for loading rates greater than 8 MPa/s and displacement rates greater than 7.5 mm/s. The ratio of transmitted pressure (P2) to applied pressure (P1) has been measured for a range of compact geometries, and it has been found that the ratio is approximately constant during the latter stages of the compaction process. Various laws for predicting the transmitted pressure have been studied, but it has been found that the simplest equation that agrees with the data is of the form \documentclass{article}\pagestyle{empty}\begin{document}$$ \frac{{P_2 }}{{P_1 }} = e^{- \alpha \mu ch/D} $$\end{document}
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760220506
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  • 58
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    Molecular weight distribution of polyethylene terephthalate in homogeneous, continuous-flow-stirred tank reactors (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 314-323 
    Details
    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: Poly(ethylene terephthalate) (PET) formation in homogeneous, continuous-flow-stirred tank reactors (HCSTRs) operating at steady state has been simulated. The feed to the reactor is assumed to consist of the monomer bis-(hydroxyethyl) terephthalate and monofunctional compound (MF1) cetyl alcohol. The overall polymerization is assumed to consist of the polycondensation, reaction with monofunctional compounds, redistribution, and cyclization reactions. At a given time, the reaction mass consists of polyester molecules (Pn), polyester molecules with an ending of molecules of monofunctional compound (MFn), and cyclic polymers (Cn). A mass balance for each of these species in the reactor gives rise to a set of algebraic equations to be solved simultaneously. The MWD calculations show that the redistribution reaction plays a major role and cannot be ignored, This result is in contrast lo the observation for semi-batch reactors, for which redistribution becomes important when the cyclization reaction is included. For the same residence times of semi-batch and HCSTRs, the latter gives considerably lower-number average molecular weight, Nav, and polydispersity index, ρ. However, for the same conversions, the ρ for CSTR is higher. The concentration of the monofurctional compound, [MF1]0, in the feed and the reactor temperature both influence ρ, but the effect is small within the range studied.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760220508
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    An improved lattice-fluid equation of state for pure component polymeric fluids (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 345-348 
    Details
    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 Fluid-Lattice Theory (Ising Fluid), recently tested by Lacombe and Sanchez, has been modified by introducing the typical Flory's surface-to-volume ratio of the characteristic-segment of a polymeric liquid. This surface-to-volume ratio is not an adjustable parameter. It is obtained from Bondi's tabulations. The resulting new equation of state has three adjustable parameters per component and it represents a definite improvement for the fitting of P-V-T data for polymeric liquids. Extension to mixtures is not tested in this work but, in principle, it can be done by well-established methods.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760220603
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    Capillary and slit flow behavior of concentrated solutions of a rod-like polymer (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 521-527 
    Details
    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 paper is concerned with the flow behavior of isotropic solutions of the rod-like polymer, poly(p-phenyleneterephthalamide) (PPT), in 100 percent sulfuric acid. Studies include entry flow visualization in a slit die and solution fracture, and die swell in capillaries and a slit die. It was observed that solutions of PPT exhibit nearly negligible die swell, a slip-stick type of fracture that disappears at high shear rates, and radial entry flow patterns similar to Newtonian fluids. Fracture was associated with the plateau in the shear stress vs shear rate curve. Because values of the wall shear stress (τw.) obtained from capillary measurements were in good agreement with those obtained from a cone-and-plate rheometer and values of the loss modulus (G″) obtained from small-strain dynamic oscillatory measurements, it is believed that the rheological properties lead to the flow instability. These results are in agreement with the predictions of a recent theory by Doi and Edwards for concentrated solutions of rod-like molecules. Data are also presented for a flexible chain polyamide, nylon 6,6, in 100 percent H2SO4 for the purpose of comparing the flow characteristics of rigid and flexible chain polymers.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760220902
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    The elastic change of volume in pressurized bottles made from polymeric materials (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 472-477 
    Details
    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 relations describing the elastic change of volume of thermoplastic cylindrical pressurized containers are presented. Discussions have been made on various cases including isotropic (i.e., un-oriented), uniaxially, and biaxially oriented materials. These relations are expected to be helpful for selecting the optimum processing conditions (i.e., draw ratio) in order to achieve the desired properties of polymeric pressurized containers.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760220804
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    The hydrolytic stability of some commercially available polycarbonates (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 370-375 
    Details
    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 number of commercially available polycarbonates, including formulations made flame retardant by two different modifications, have been exposed to conditions producing moderately rapid hydrolysis. Hydrolysis rates were calculated from molecular weight data determined by gel permeation chromatography and, in some cases, from melt flow rate data. The rates calculated by the two methods are in good agreement. In general, the standard formulations containing minimal additive packages are the most hydrolytically stable. Although one relatively new flame retardant polycarbonate demonstrates generally good resistance to hydrolysis, most of the flame retardant formulations appear to be quite susceptible to hydrolytic degradation. For these materials, hydrolysis under conditions encountered in use could cause significant decreases in impact strength within a few years.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760220608
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    Low temperature thermal aging of ethylene vinyl alcohol copolymers (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 382-387 
    Details
    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 crystallites of semicrystalline polymers formed at low temperatures are subject to partial partial melting and recrystallization resulting in a systematic increase in the size and perfection of the nascent crystallites. Differential scanning calorimetry (DSC) and x-ray studies suggest that ethylene-vinyl alcohol copolymers (EVOH), in particular, may undergo these secondary crystallization processes upon storage at temperatures far below Tm. DSC scans have been run on “as received” and quenched samples; the mole percent of vinyl alcohol in the copolymers studied was 0, 62, 70, 72, 82 and 100 percent. Tests on secondary crystallization kinetics, performed at different temperatures, further confirm the hypothesis of an increased degree of perfection (lamellar thickening) of the bulk crystallites achieved upon long term storage at temperature between Tg and Tm.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760220610
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  • 64
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    Rheology of polymer blends: Simultaneous slippage and entrance pressure loss in the ethylene-propylene-diene (EPDM)/viton system (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 507-511 
    Details
    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: Because the exact nature of the mechanism governing the marked viscosity reduction in the highly incompatible EPDM/“Viton” fluoroelastomer system is not fully understood, a study was undertaken to shed more light on the phenomenon. Interracial. Slippage in the blend has been suggested as the mechanism by which a substantial reduction in the melt viscosities of either component takes place upon addition of a small amount of the other, In the present investigation, a Mooney slip analysis demonstrated wall slippage in the EPDM/Viton system over the shear stress range of 40 kPa to 160 kPa. The capillary surface was examined for evidence of coating by the minor component of the blend (Viton), and 9-fold enrichment was found by elemental analysis. However, on no occasion was pure Viton found. In other experiments, the dynamic linear viscoelastic properties and the transient squeezing flow response of the blend were found to be no different from those of the neat elastomer. In addition, the slip velocity in a capillary (and consequently, the viscosity-lowering effect) was reduced by a factor of 2 to 3 in capillaries with a 90° included entrance angle. It is postulated that the reduction in the flow resistance for the blend is unique to the sharp-entry capillary geometry and results from removal of Viton from the melt in the recirculating flow at the entrance. This material then feeds along the capillary wall, disrupting the already tenuous adhesion of the elastomer to the metal surface.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760220809
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    Unsaturated polyesters from 2,2-dimethyl-1,3-propanediol (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 556-559 
    Details
    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 series unsaturated polyesters were made from 2,2-di-methyl-l,3-propanediol, propylene glycol, fumaric acid, and isophthalic acid by a two-step fusion process. The effect of catalyst, conversion, composition, unsaturation, and styrene content were studied, and the relationship between composition and properties was established.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760220907
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    Effect of the addition of ethylene-propylene random copolymers on the properties of high-density polyethylene/isotactic polypropylene blends: Part 1 - morphology and impact behavior of molded samples (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 536-544 
    Details
    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: Two random commercial ethylene-propylene copolymers (EPM) with different ethylene content have been added to binary isotactic polypropylene (iPP)/high density polyethylene (HDPE) blends by melt mixing in a Brabender-like apparatus. Impact Izod tests and a morphological analysis on the fractured surfaces of broken specimens have been performed and discussed, in order to improve the deficiency in toughness of the binary HDPE/iPP mixtures. The results show that the impact performance of both homopolymers and HDPE/iPP binary blends is strongly improved by the addition of the EPM copolymers. Such an effect is related to the fact that the overall morphology, as well as the mechanism and mode of fracture, are greatly modified by the presence of such additives. The extent is dependent on factors such as the nature of the matrix (HDPE or iPP), the composition, and the chemical structure and/or the molecular mass of the added copolymer.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760220904
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    Masthead (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982) 
    Details
    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
    URL: http://dx.doi.org/10.1002/pen.760221001
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    Estimation of injection pressure during mold fillingPresented in part at the “Second World Congress of Chemical Engineering,” Montreal, Canada, Oct, 4-9, 1981.This paper is a corrected reprint of the paper that originally appeared in POLYMER ENGINEERING AND SCIENCE, Mid-April, 1982, Vol, 22, No. 5. (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 589-593 
    Details
    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: Dimensionless diagrams for estimating the bulk temperature of the flow front and injection pressure in the limit of small viscous generation are obtained. Also, a criterion for neglecting viscous generation is identified, The diagrams, based on the Lord and Williams model, refer to rectangular geometry and amorphous materials. A satisfactory comparison is obtained with literature data taken on polystyrene. A reasonable estimate of polyethylene injection pressure was obtained by roughly accounting for latent heat of crystallization through modified thermal diffusivity.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760221002
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    The relationship of carbon black dispersion to electrical resistivity and vulcanizate physical properties (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 601-609 
    Details
    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 degree of dispersion of carbon black in rubber is known to be a determining factor in the physical properties of the composite. It is important, therefore, to have a reliable, quantitative technique for assessing carbon black dispersion. It has been known for some time that the degree of dispersion of carbon black is reflected in its electrical resistivity. A resistivity instrument, developed by B. Boonstra, has been redesigned and constructed for use in this study. Factors that influence resistivity (i.e., black type, volume loading, and mixing time) are examined. Physical property and dynamic mechanical measurements are made, and their relationship to black dispersion is investigated. Light microscopy is also used to evaluate dispersion, and these data are compared to the resistivity results.
    Additional Material: 18 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760221004
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    On the dynamics and control of a plasticating extruder (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 1095-1106 
    Details
    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: In recent years, there have been many papers published on the application of process control to plasticating extruders. Much of the literature concentrates on the more classical control techniques. However, recent research has studied the application of stochastic identification techniques for building transfer function models for the extruder. In particular, the relationship of screw speed to die pressure and temperature has been studied. In the present work, both step tests and pseudorandom binary sequence tests were used to study the process dynamics of a 38 mm Killion extruder having a Iength-to-diameter ratio of 24:1. This study concentrates on the regulation of the extruder pressure in the face of its inherent surging characteristics. Variations in the quality of the feed plastic were studied through pulse and step changes in input polymer composition. Significant control problems resulted from measurement noise, which appeared at the same frequency as the screw rotation speed. Various mathematical filters to reduce the effect of this noise on the control variables were studied.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760221707
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    Siloxane-poly(Methylmethacrylate) amphoteric blends (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 1123-1126 
    Details
    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: Poly([4-(methacryloyloxy) butyl]pentamethyldisiloxane), PMBPD, has been prepared for the first time. At the weight average molecular weight of 55,900, it is a clear, viscous liquid with a glass transition temperature, Tg, of 236K. Copolymers with methylmethacrylate have also been prepared. The homo-and copolymers, all of which have methacrylate backbones with pendant siloxane groups, were blended with poly(methyl-methacrylate), PMMA. Using the existence of a single Tg as a definition of miscibility, it was found that blends of either PMMA or PMBPD with random copolymers are miscible. However, in spite of a clear appearance, the blend of the two horriopolymers were found to have two distinct Tgs.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760221712
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    Recent advances in interpenetrating polymer networks (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 1143-1152 
    Details
    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: We review the synthesis, morphology, and physical and mechanical properties of IFNs as well as the related pseudo-IPNs, in which only one of the polymers is crossliriked. Recent studies have shown that the degree of phase separation achieved in these materials is strongly dependent on the compatibility of blends of the linear polymer constituents of the IPN components as well as the kinetics of chain extension and the presence of grafting between component polymers. We illustrate this by a series of IPNs consisting of a polyurethane and an acrylic copolymer. The acrylic is a typical automotive enamel. An enhancement in properties results, which is dependent on the amount of grafting and the kinetics of polymerization. Also discussed are IPNs of a polyurethane and an epoxy, which exhibit a synergism in adhesive properties, and IPNs of a RIM polyurethane with several epoxies and unsaturated polyesters. In addition, also reported are the preliminary studies on the first successful preparation of a three-component IPN, consisting of a polyurethane, an epoxy, and an acrylic.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760221715
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    Development of industrial polyolefin blends using melt rheology data (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 1153-1165 
    Details
    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 review of current knowledge of the composition dependence of polymer-blend processability and morphology shows that development of industrial blends requires use of a semiempirical approach, based on the particular rheological composition (PRC) concept. Selecting blend composition in the close proximity to PRC and employing factorial experiments for the mixing process allows the development of successful industrial polyethylene/polypropylene blends designed for film and blow-molding applications.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760221716
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    Composition and processing effects on the properties of one-component polyurethanesPresented at Second World Congress of Chemical Engineering, Montral, Canada, October 4-9, 1981. (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 1177-1183 
    Details
    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 polyurethane consisting of a poly(propylene oxide) soft segment and a diphenylmethane diisocyanate - hydroquinone di-(b̃-hydroxyethyl) ether (HQEE) hard block has been characterized over the composition range of 30 to 60 percent hard block. The flexural modulus varied from 60 to 900 MPa over this composition range. The elongation was approximately 250 percent at the lower hard block contents but fell below 100 percent at 60 percent hard block. Differential scanning calorirnetric measurements showed that the crystallinity associated with the hard phase increased with increasing hard block content but decreased with increasing cure temperature. The heat sag was found to decrease with increasing hardblock and increase with increasing cure temperature. A material with properties comparable to current fascia materials had a significantly better heat sag resistance than a current RIM (reaction injection molding) polyurethane. The combination of the solid chain extender, HQEE, and a solid catalyst, zinc stearate, lowing it to be processed as a one-component resin having a pot life of greater than 8 h at 20°C al-injection molding machines. The one-component nature of the resin has made it possible to use a continuous in-line mexer and to reduce the amount of scrap by using cold runner molds. In addition, any scrap that is generated can be used as regrind in the system.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760221802
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    Fractography of polyethylene glycol dimethacrylate doped with polymethyl methacrylate (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 1199-1204 
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    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 presence of polymethyl methacrylate (PMMA) can greatly affect the properties of materials made by polymerization of ethylene glycol dimethacrylate (EGDM). Fracture surfaces, examined by scanning electron microscopy, show a much wider range of morphologies in mist regions than observed in previous work on PEGDM alone. These morphologies are attributed to the moderation of brittle fracture by localized plastic deformation. It is suggested that the effect of PMMA is due to its segregation around clusters of highly cross-linked particles of PEGDM that, as a result, become more discrete and, hence, more susceptible to interparticle displacements during fracture. In agreement With this suggestion, the mist regions usually exhibit a particulate microstructure.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760221805
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    Studies of epoxy resin systems: Part D: Fracture toughness of an epoxy resin: A study of the effect of crosslinking and sub-Tg aging (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 1228-1236 
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    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 fracture toughness of an epoxy resin system, diglycidyl ether of butanediol, DGEB, cured with 4-4′ diaminodiphenyl sulphone, DDS, has been studied by varying the crosslinking density and state of aging. A stable, but rough, crack propagation was observed with specimens that were 99 percent cured and quenched. When the extent of curing was less than 99 percent or the material was aged for more than 20 min at 62°C, crack propagation was of the unstable stick-slip nature. Aging was found to decrease the initiation fracture toughness dramatically, but the arrest fracture toughness was almost unchanged. This result was associated with a change of relaxation strength of the primary, a, transition with aging. An increase of crosslinking density was found initially to reduce the fracture toughness of this epoxy resin, but the fracture toughness increased after 87 percent of curing. The initial decrease of the fracture toughness was attributed to a decrease of relaxation strength of the primary transition (i.e., the area under the α-relaxation peak), while the increase of the fracture toughness after 87 percent curing was explained by the onset of the stablerough crack propagation, Micrographs taken by scanning electron microscopy-showed possible existence of blunting during crack propagation and a decrease of blunting with the extent of aging.
    Additional Material: 11 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760221809
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    Mathematical modeling of the blow-molding process (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 1075-1083 
    Details
    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 mathematical simulation of the blow-molding cycle has been developed by combining general conservation principles along with appropriate constitutive relations for the material. A model of the parison formation stage has been devised by considering the competing effects due to swell and drawdown. A more rigorous numerical analysis of parison formation is also discussed. A theoretical treatment of parison inflation is described for both inelastic and viscoelastic materials by assuming uniform radial growth, Comparisons are made with experimental data for all phases of the molding cycle. The mathematical model is in reasonable quantitative agreement with experimental results and is capable of elucidating the influence of material properties and process conditions on the dynamics and performance of the blow-molding process.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760221705
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    Editor's note (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 1107-1107 
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    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
    URL: http://dx.doi.org/10.1002/pen.760221708
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    13C NMR characterization of intermolecular interactions for polymers. Part 3. Solvent effect on the blend compatibility of poly(vinyl methyl ether) and polystyrene (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 1109-1116 
    Details
    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 solvent has an influence on the homogeneity of the poly(vinyl methyl ether)-polystyrene, PVME-PS blends Prepared by drying cosolutions. This influence has been analyzed in terms of the competition among polymer-polymer and polymer-solvent interactions. Model solutions have been prepared in which intermoleeular interactions correspond to the interactions in this blend and in some of the cosolutions. These interactions in the model solutions have been detected and identified by applying Rummens' method. The 13C NMR spectra have been determined for PVME and for styrene oligomer dissolved in n-alkanes, cyclohexane, diethyl ether, isopropyl methyl ether, diisopropyl ether, and chloroform, and for PVME dissolved in benzene, toluene, and cumene. The chemical shifts have been plotted against the parameter g2 = [(n22 - 1)/(n22 + 1)]2, where n2 is the refractive index of the solvent. If the structural segment represented by certain carbon and some solvent has an interaction that is stronger than dispersive, the chemical shift for this carbon will deviate from the line formed by its shifts in n-alkane solutions, these deviations indicate characters and intensities of the intermoleeular interactions. Results indicate that cyclohexane exhibits weak interactions with both of the polymers and does not interfere with their mutual interaction, leading to a compatible blend. Results also suggest that benzene and toluene interact in the PVME in the same manner as PS. This leads to a gradual increase of the number of polymer-polymer interactions as the concentration of the polymers is increased by solvent removal, resulting in a compatible blend. Chloroform apparently interacts more strongly with PVME than with PS but interacts strongly enough with both to restrict interaction among the two polymers. As the concentration of polymers in the cosolution is increased, PS forms a separate phase. This leads to an inhomogeneous blend when the solvent is evaporated.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760221710
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    Fracture toughness (KQ) testing with a mini-compact tension (CT) specimen (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 1190-1198 
    Details
    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 testing method using the Rheometrics Mechanical Spectrometer as the loading instrument to measure the fracture toughness KQ, which is related to a specific sample geometry and dimensions (half-inch compact tension) is reported. The small sample size requirement makes it attractive to do fracture toughness testing on newly synthesized material for preliminary material study and comparison purposes. Commercially available epoxy resins were used to check the procedure at different temperatures (-150° to 250°C). An empirical crack length averaging method was used that appears to give constant KQ values independent of the a/W ratio values. The fracture surfaces were studied using scanning electron microscopy.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760221804
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    Studies of epoxy resin systems: Part A: A study of the origins of the secondary relaxations of epoxy resins by thermally stimulated depolarization (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 1205-1212 
    Details
    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 relaxation behavior of several epoxy resin systems, which have systematic structural differences, has been studied by the thermally stimulated discharge (TSD) technique. Two TSD peaks centered at about 115°K (β peak) and 185°K (β peak) were found for epoxy resins cured with a diamine. Structural change, either in the epoxy resin molecule or the amine molecule, did not seem to affect those two peaks. The TSD thermogram of the DGEBA (diglycidyl ether of disphenol A) epoxy resin part only showed a small new peak at 160°K instead of the ft peak at 185°K. This result, together with the fact that postcuring increased β peak height, leads to the conclusion that the ft peak is most likely due to the newly-created molecular segment during the curing reaction. The peak at 160°K was assigned to the epoxy group. This assignment was based on the fact that the 160°K peak of an epoxy homopolymer, which has fewer epoxy groups, was smaller than that of the parent DGEBA. The β and γ peaks were found to be of distributed characteristics, and the distribution of activation energy was studied by the partial heating method.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760221806
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    Batch polymerization of styrene-optimal temperature historiesThis paper was presented at the 1980 Annual Meeting, American Institute of Chemical Engineers, Chicago, III. (November 1980). (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 1-8 
    Details
    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: Optimal temperature histories for the batch thermal polymerization of styrene are determined using Pontryagin's maximum principle. The theoretical predictions are compared with experimental measurements of conversion and molecular weight distribution. The excellent agreement suggests policy improvements in batch radical chain growth polymerizations.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760220102
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  • 83
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    Masthead (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982) 
    Details
    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
    URL: http://dx.doi.org/10.1002/pen.760220201
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  • 84
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    Introduction (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 57-57 
    Details
    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
    URL: http://dx.doi.org/10.1002/pen.760220202
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  • 85
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    Polymer compatibility with and without a solvent (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 64-73 
    Details
    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 qualitative review of the thermodynamics of polymer systems will be given in terms of three contributions: positional (or combinatorial) entropy, an “international” term and a free volume term. From this one finds that a simple polymer-solvent system phase separates on lowering T to an Upper Critical Solution Temperature (UCST) or raising it to Lower Critical Solution Temperature (LCST), To achieve miscibility of two polymers of high molecular weight, one requires a “specific” interaction, usually a weak charge-transfer complex or a hydrogen bond. Phase separation takes place on raising the temperature to an LCST. These various UCST and LCST are predicted semi-quantitative by the Prigogine-Flory theory. When a solvent is added to two miscible polymers, a new type of phase separation appears since there is an effect of any difference in the strengths of the two polymer-solvent interactions. Phase separation may easily occur in the ternary system where there is none in the three binary systems, and examples will be given. In the case of two highly-attractive polymers in a solvent, a quite different phase separation occurs, sometimes called complex coacervation. A simple Flory-Huggins type theory predicts these phenomena in ternary systems.
    Additional Material: 13 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760220204
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  • 86
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    High modulus semi-crystalline polymers by solid state rolling (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 27-33 
    Details
    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: Solid state rolling of semi-crystalline polymers is shown to be an effective method of producing high strength, high modulus tape at acceptable production rates. High density polyethylene tape was produced having a tensile strength exceeding 300 MPa and a tensile modulus of 8.7 GPa at production rates exceeding 8 m/min. A significant factor in producing highly oriented tape by the rolling process is roll temperature. Increasing the roll temperature from 25°C to 125°C not only increases the maximum extent of orientation achievable, but increases the mechanical properties at a given degree of thickness reduction. Internal frictional heat development limited the maximum thickness reduction ratio of polypropylene to 6.6:1. This reduction was reached by rolling at 150°C. The resultant tape had a tensile modulus of 5.1 GPa and a tensile strength of 300 MPa.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760220105
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    Residual stresses in polymers I: The effect of thermal historyThe availability of appropriate illustrations has led to publication in this journal of Part II (Vol. 21, NO. 15, page 997) p or to this Part I. (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 40-47 
    Details
    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 distribution of residual stresses in quenched modified poly(phenylene oxide) (PPO) specimens was investigated. Quenching was carried out from temperature level above Tg to various temperatures below Tg. As expected, compressive stresses were measured at the surface layers while tensile stresses were in the inner layers. The ratio between the tensile and compressive stresses varied, depending on the thermal history. The level of residual surface stresses was found to depend on both the total temperature difference during cooling and the initial specimen temperature. At constant initial temperature the surface stresses are proportional to the total temperature difference, whereas, at constant final temperature the surface stresses are inversely proportional to the total temperature difference. An empirical correlation describing the surface stresses as a function of thermal history has been suggested. The differences between present theories and experimental data are discussed. emphasizing the apparent discrepancy regarding the influence of initial temperature above Tg on the level of residual stresses.
    Additional Material: 13 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760220107
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  • 88
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    Kinetics of a sterically hindered amine-cured epoxy resin system (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 166-171 
    Details
    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: Fourier transform infrared spectroscopy (FT-IR) and torsional braid analysis (TBA) were used to study the reaction of an epoxy resin system cured with a sterically hindered amine. Isothermal torsional braid analysis showed the apparent activation energy to be approximately 42 kJ/mol. The reaction kinetics were also considered from the unreacted freshly mixed condition and a partially reacted “B-staged” condition using infrared spectroscopy, The B-staged condition is unreactive and stable at room temperature due to the quenching of the primary amine reaction by the glassy structure and the steric hindrance of the secondary amine reaction. Apparent activation energies for these two conditions were found to be 49.4 kJ/mol and 49.0 kJ/mol respectively. The storage life at room temperature of the B-staged resin system is predicted to be at least three months based on extrapolation of the experimental kinetic data.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760220306
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    A Note on the prediction of polyethylene melt rheological properties from molecular weight distribution data obtained by gel permeation chromatography (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 53-55 
    Details
    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: In the present study, a modification of the method previously presented by the authors for predicting rheological properties of linear polyethylene melts from gel permeation chromatography (GPC) data is presented. The modification involves independent values of the zero shear viscosities for melts rather than generating these values internally. The comparison between the experimental zero shear viscosity values and those calculated from GPC data is shown to be very good.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760220109
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  • 90
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    Graft copolymerization of vinyl chloride onto ethylene propylene rubber (EPR) and ethylene propylenediene monomer (EPDM) by bulk processPresented at the 180th National Meeting, American Chemical Society, August 1980. (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 48-52 
    Details
    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: Vinyl chloride was graft copolymerized on ethylene propylene rubber (EPR) and ethylene propylene diene-monomer rubber (EPDM) by a bulk process to give a multi-component end product consisting of three components and two phases. The reaction system forms a pseudo-emulsion at an early stage of reaction where the phase morphology of graft poly(vinyl chloride) (PVC) is determined. The formation of pseudo-emulsion was confirmed visually, by the particle size of PVC prepared in the presence of rubber and by the phase morphology of rub be r-g-PVC which is similar to that from an aqueous emulsion system. The degree of graft depends on the unsaturation of the rubber used as backbone. The amount of grafted EPR does not exceed 60 percent of the initial rubber; however, the amount of grafted EPDM is always higher than 60 percent of the initial rubber and increases further as the unsaturation increases. The degree of graft was found to be independent of the type of radical initiator used indicating that the abstraction of hydrogen from the rubber is carried out by the PVC radical to generate the grafting point. The graft PVC shows considerably improved processability which is equivalent to that of commercial vinyl chloride copolymers containing small amounts of propylene. It also shows dramatically improved impact strength which ranges from ten to twenty times that of PVC homopolymers.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760220108
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    Temperature dependence of the viscoelastic shift factor in ionomersBased on presented at the 63rd Annual Conference of the Chemical Institute of Canada, Ottawa, Ontario, June 8-1, 1980. (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 81-87 
    Details
    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 temperature dependence of log a of poly(styrene -co- sodium methacrylate) was analyzed by means of the relation based on the free volume and the hole theories of liquids. For the near-Tg region the relation becomes a single parameter equation of T/Tg. The analysis revealed a transition in flow pattein at TT associated with disintegration of the ion multi plets. The Tt-transition was previously detected in other theological functions, viz, relaxation modulus, mechanical and dielectric tan δ plots.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760220206
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    Melt rheology of polymer blends (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 96-114 
    Details
    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 polymer blends is compared with that reported for emulsions, block polymers and homologous polymer blends. It has been shown that the properties of polymer alloys frequently differ from those of these “model” systems - the principal difference being the lowering of at least one rheological function below the value predicted In the log-additivity rule. Primarily, the most recent (post 1977) results are reviewed. The data obtained by the authors on the flow of poly(ethylene terephthalate)/Polyamide-6,6 are discussed in detail.
    Additional Material: 30 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760220211
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    Discussion on terminology (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 137-139 
    Details
    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
    URL: http://dx.doi.org/10.1002/pen.760220215
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  • 94
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    Masthead (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982) 
    Details
    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
    URL: http://dx.doi.org/10.1002/pen.760220301
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  • 95
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    The principles of pipe-line design for molten poly(ethylene terephthalate) (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 141-146 
    Details
    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 flow of molten poly(ethylene terephthalate) in pipes is discussed. The considerations made are based on the results of previous investigations by the authors, concerning the rheological behavior of the melt which exhibits thermal degradation. A procedure is proposed which enables the design of a pipe-line system for the distribution of molten, spinnable poly(ethylene terephthalate) in a fiber plant to be made.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760220302
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  • 96
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    Shear-induced anisotropy in thermal conductivity of a polyethylene melt (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 154-157 
    Details
    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 rotating concentric-cylinder thermal conductivity cell for polymer liquids is described. Thermal conductivity can be measured at temperatures approaching 200°C and at strain rates up to 400 s-1, The transient heat flux probe (with inner cylinder as heat source and temperature probe) method is used to permit the separation of the viscous heating effect from the probe heating effect.A polyethylene melt was studied and showed that at 50 s-1, a 2 percent increase in thermal conductivity occurs, followed by a gradual decrease until a value 10 percent less than the no-shear thermal conductivity was found at 400 s-1. This effect is due to molecular orientation.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760220304
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  • 97
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    Processing properties of high- and low-density polyethylenes and their blends (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 280-286 
    Details
    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: Blends of two characterized linear polyethylenes with a branched polyethylene have been prepared by melt extrusion. It has been found that the linear polyethylenes can be shear modified in a reversible manner similar to branched polymers and that this shear modification and its reversal by re-heating does not change the molecular weight distribution, thereby indicating that the shear modification is a physical rather than chemical change in structure. Because both the high- and low-density polyethylene components of the blends are capable of undergoing reversible shear modification, it is possible to produce blends with either greater or less melt elasticity than the individual components by adjusting the conditions of blending. This demonstrates that the correlation of the properties of blends with the properties of their components should not be attempted without consideration of the effect of the blending process on the properties of the individual components.
    Additional Material: 14 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760220503
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    Masthead (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982) 
    Details
    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
    URL: http://dx.doi.org/10.1002/pen.760221101
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    Correction (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 683-683 
    Details
    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
    URL: http://dx.doi.org/10.1002/pen.760221105
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  • 100
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    Relationship between rheological properties and impact strength in high impact polystyrene (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 684-691 
    Details
    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: Two batches of a commercially available high-impact polystyrene having different impact strengths were investigated. The steady-shear flow properties, dynamic shear properties, and elongational flow properties of the two were measured. Transmission electron microscopy (TEM) was used to study the microstructure. It is suggested that melt rheology can be a sensitive tool in the characterization of final product properties of rubber-modified polymers: the zero-shear-rate viscosity and the dynamic storage modulus G′, at low frequencies, were experimentally shown to correlate directly with the impact strength, despite the fact that TEM revealed no gross differences in the morphology of the two batches.
    Additional Material: 14 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760221106
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