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  • Chemical Engineering  (31)
  • Gastric cancer  (2)
  • 61.16.Bg  (1)
  • 61.46.+w  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Langenbeck's archives of surgery 359 (1983), S. 65-73 
    ISSN: 1435-2451
    Keywords: Vitamin-A ; Gastric cancer ; Chemical carcinogenesis ; Tumor promotion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung In einer Untersuchung an 82 Wistar-Ratten wurden Carcinome des Drüsenmagens mit MNNG erzeugt. Ein Teil der Tiere erhielt zusätzlich hohe Dosen Vitamin A. Wir sahen eine statistisch signifikante Zunahme der Invasionstiefe und damit der Progression des Tumorstadiums unter Vitamin A-Einfluß. Die Häufigkeit des Auftretens von Tumoren war hingegen nicht signifikant verändert. Als Ursache des tumorfördernden Einflußes von Vitamin A in unserem Experiment ist vor allem sein labilisierender Effekt auf celluläre Membransysteme zu diskutieren: 1. Durch Zerstörung lysosomaler Membranen werden Enzyme, Cancerogene und Viren freigesetzt, die direkt oder indirekt zu einer Alteration der DNA führen. 2. Durch Schädigung der Zellmembranen geht die Kontaktinhibition verloren.
    Notes: Summary Carcinomas of the glandular stomach were induced in 82 Wistar rats by means of MNNG1. Part of the group also received high doses of Vitamin A. A consistently significant increase in depth of invasion, i. e. progression of the pathological tumor stage, was observed under the influence of Vitamin A. The frequency of tumor occurrence was not significantly altered. The labilizing effect of Vitamin A on cellular membrane systems is the probable mechanism of Vitamin A's tumor-promoting influence in our experiment: 1. By way of destruction of lysosomal membranes, enzymes, cancerogens, and viruses would be released, leading directly or indirectly to an alteration of the DNA. 2. Damage of cell membranes would lead to loss of the contact inhibition.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Langenbeck's archives of surgery 358 (1982), S. 53-55 
    ISSN: 1435-2451
    Keywords: Gastric cancer ; Evaluation ; Technique ; Magenkrebs ; Bilanz nach 100 Jahren ; Taktik ; Technik
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Theodor Billroth konzipierte vor 100 Jahren die Technik der Magencarcinom-Resektion und zeitlos gültig die taktischen Prinzipien der radikalen kurativen Krebsoperation am Magen.
    Notes: Summary A hundred years ago Theodor Billroth devised the technique of gastric cancer resection and the perpetually valid tactical principles of radical curative gastric cancer surgery.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1434-6036
    Keywords: 79.20.Kz ; 61.46.+w ; 61.16.Bg
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The crystal and electronic structure of solidC 76 has been studied using transmission electron microscopy and electron energy-loss spectroscopy in transmission. C76 forms a close packed structure with an average facecentred cubic symmetry. From valence band and core electron excitations information on the dielectric function and the unoccupied density of states has been obtained.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 1 (1961), S. 86-92 
    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: For broad ranges of operating conditions and a wide variety of high pressure polyethylenes, the flow data obtained from a high shear viscometer and a commercial extruder are identical. Discrepancies between flow data can result from non steady state viscosities in the high shear viscometer, or from cooled screw extruder operation. In the broad regions in which the flow data concur, the readily obtained viscometer data are suitable for predictions of extruder performance. The principle is illustrated by the good correlation of a viscometer flow curve parameter and the screw power consumption in the extruder. Principles outlined for flow data identity and extruder performance prediction are believed to be general, but the quantitative limits defined are specific to the extrusion devices involved.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 433-433 
    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
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  • 6
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 456-461 
    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 shear strength of bonds between isotactic polypropylene and cellophane, formed under standard conditions, has beer studied as a function of cooling rates, following bond formation, and after ageing at temperatures up to 90°C. Rapid cooling produced cohesively failing bonds with shear strengths above 20 kg/em2. Weak, adhesively failing joints were produced under slow-cooling conditions. Strong bonds deteriorated when joints were aged at temperatures above 50°C, but further improvement in bond strength was observed upon ageing at lower temperatures. Experimental observations were consistent with the development of smectic structure in the polypropylene upon rapid cooling; a tendency for transcrystallization in slow-cooled joints was offset by the presence of weak boundary layers in the interface. Ageing produced further development of weak boundary layers and a transition from smectic to monoclinic crystallization in polypropylene. At higher ageing temperatures, the former effect seemed dominant; at lower temperatures, the structural change was assumed responsible for the observed improvement in bond strength.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 21 (1981), S. 433-438 
    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: Variously dispersed two-component blends of linear polyethylene and a thermoplastic rubber were subjected to different thermal histories after compression molding and their properties were evaluated. It has been shown that ultimate properties of the blends are not defined by the composition, but vary greatly with degree of dispersion and thermal history. Stronger materials failing in a ductile manner were produced under shock cool conditions and in, finely-dispersed blends. Brittle failures and weaker materials were favored by annealing procedures and in blends subjected to brief and/or lowshear dispersion procedures. Time and temperature dependent changes in properties of blends prepared under standard conditions have been observed and activation energies for the aging process calculated. Data interpretation was based on a hypothesis of domain morphology in the blends, and on the existence of “tie molecules” which help to determine the cohesive strength of domain boundaries.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 721-727 
    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: Pyrolysis of polymer wastes appears to be a suitable means of dealing with an increasingly important environmental problem. To provide background on the pyrolytic behavior of wastes, model mixtures of polyethylene and polystyrene have been pyrolyzed in various gas phases including nitrogen and carbon monoxide, at atmospheric and at reduced pressures and at temperatures from about 300-900°C. When the pyrolyzing temperature is attained by gradual heating, and when pyrolysis occurs at pressures in excess of about 200 torr, the process occurs as if each component were present alone - that is, no evidence for component interaction was noted. In these cases, the known mechanisms for pyrolysis of the pure polymers can be applied to the behavior of mixtures. Complicating effects due to interactions between the starting polymers, or among the pyrolysis products, were observed in low pressure pyrolysis (≲20 torr); further, it was shown that the balance of pyrolysis products depends on rates of attaining the pyrolyzing temperature, more rapid rates favoring the production of carbon-rich solid residues of possible use as carbon blacks. More detailed understanding of pyrolytic processes in polymer mixtures is needed to permit selection of conditions producing the optimum balance of useful products.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 900-906 
    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 linear polyethylene and ethylene-propylenediene elastomer, representing the entire composition range, were prepared under various conditions of shear intensity. It was found that both viscoelastic flow parameters and mechanical properties at large deformation respond strongly to variations in shear history of material preparation. Mechanical degradation of the polymers not being detected, it is postulated that property variations are due to morphological effects related to domain sizes of the two components and to the ease of molecular diffusion across domain boundaries. Thus, mechanical properties develop over finite times of mixing, consistent with the attainment of steady states in domain sizes. Maximum sensitivity of mechanical properties to mixing variables is found for 50/50 blends of the polymers, which have maximum interdomain contact areas. It appears feasible to develop desired balances of flow and mechanical properties in such polyblends through the close control of component dispersion processes.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 129-134 
    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: Polypropylene, polystyrene, EP (ethylene/propylene) rubber, and bromobutyl rubber were blended under standardized conditions and the sizes of minor phase domains determined by Quantimet analysis. Dispersion effectiveness was found to depend on the melt viscosities of components under mixing conditions and on their “compatibilty” as inferred here from surface-tension data. Dispersion was optimized when components wet readily at contact surfaces and when melt viscosities were similar. Shear heating during dispersion appeared to offer an empirical index of component compatibilty. Apparent melt viscosities of the blends further reflected the component compatibility factor.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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