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  • 1
    ISSN: 1432-2013
    Keywords: Cerebral Cortex ; Carbon Dioxide ; Oxygen ; Electrophysiology ; Großhirnrinde ; Kohlensäure ; Sauerstoff ; Elektrophysiologie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung An isolierten Hundeköpfen wurde die Gleichspannung zwischen der Konvexität des Gehirns (Gyrus lateralis) und der Nase (Knochenoberfläche des os frontale) bei Änderung des arteriellen pO2 oder pCO2 gemessen. Erniedrigung des pO2 oder pCO2 führt zu einer Negativierung, Erhöhung des pCO2 zu einer Positivierung. Erhöhung des pO2 ändert die Gleichspannung nicht.
    Notes: Summary In isolated dog head preparations the d.c. potential of the convexity of the brain (gyrus lateralis) with respect to the surface of os frontale was measured while the arterial pO2 or pCO2 were changed. Lowering of arterial pO2 or pCO2 resulted in a negative, increasing of pCO2 in a positive shift. No change of the cortical d.c. potential was found on increasing pO2.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2013
    Keywords: Cerebral Cortex ; Cerebral Ischemia, Transient ; Electrophysiology ; Großhirnrinde ; Gehirnischämie ; Elektrophysiologie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die corticale Gleichspannung wurde an isolierten Hundeköpfen von der Konvexität des Gehirns (Gyrus lateralis) gegen Nase (Knochenoberfläche des os frontale) bei kompletter und inkompletter Gehirnischämie gemessen. Während kompletter Gehirnischämie verschiebt sich die Gleichspannung nach einer initialen Positivierung, die 1,5–2,75 min nach Ischämiebeginn ein Maximum von 1,5–2 mV erreicht, in negativer Richtung. Diese Negativierung erreicht 3–8 min nach Ischämiebeginn einen steady state von im Mittel 6,5 mV. Nach Ende der kompletten Gehirnischämie kommt es nach einer kurzfristigen Positivierung zu einer länger dauernden Negativierung. Bei inkompletter Gehirnischämie kommt es zu einer Negativierung der Gleichspannung, wenn der Blutdruck auf 80–40 mm Hg abgefallen ist. Es wird vermutet, daß die Negativierung bei der für das Gehirn kritischen Blutdruckhöhe beginnt.
    Notes: Summary In isolated dog head preparations the d.c. potential of the convexity of the brain (gyrus lateralis) with respect to the surface of os frontale was measured in complete and incomplete ischemia of the brain. During complete ischemia an initial positivity, reaching a maximum of 1.5 to 2 mV after 1.5 to 2.75 min, is followed by a negative shift. The negativity reaches a steady state of 6.5 mV on an average 3 to 8 min after onset of the ischemia. After termination of a complete ischemia a transitory positivity is followed by a longer lasting negativity. In incomplete ischemia the d.c. potential turns negative, when the blood pressure has decreased to 80 to 40 mm Hg. It is assumed that the negative shift begins at the critical blood pressure of the brain.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-2013
    Keywords: Anoxie ; Cerebral Cortex ; Electrophysiologie ; Anoxie ; Großhirnrinde ; Elektrophysiologie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die Gleichspannung zwischen der Konvexität des Gehirns (gyrus lateralis) und der Nase (Knochenoberfläche des os frontale) wurde an isolierten Hundeköpfen gemessen. Nach Überschreiten der Wiederbelebungszeit der cerebralen Gesamtfunktion kann die Gleichspannung wider ihren Ausgangswert erreichen. Die Reaktionsweise der Gleichspannung auf einen weiteren O2-Mangel oder auf eine Änderung der arteriellen Gasdrucke ist auch nach Überschreiten der Wiederbelebungszeit noch erhalten. Aus der Gleichspannung können keine Schlüsse auf eine noch mögliche Wiederbelebung gezogen werden.
    Notes: Summary The d.c. potential of the convexity of the brain (gyrus lateralis) with respect to the surface of os frontale was measured in isolated dog head preparations. The d.c. potential always normalizes after ischemia of the head not exceeding the revival time of the brain as a whole, it also may return to the control level following ischemic periods exceeding the cerebral revival time. Also the reactions of the d.c. potential on another oxygen deficiency or on variations in the arterial pO2 and pCO2 are still present. Conclusions on the chances of cerebral revival can not be drawn from the d.c. potential.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-2013
    Keywords: Cerebral Cortex ; Cerebral Ischemia ; Electrocorticogram ; Großhirnrinde ; Gehirnischämie ; Elektrocorticogramm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Am isolierten, von einem Spendertier durchbluteten Hundekopf, dessen Gehirntemperatur konstant 37°C betrug, wurden 1 min lange komplette Ischämien gesetzt. Die Perfusionszeit zwischen den einzelnen Ischämien variierte zwischen 20 min und 1/2 min. Bei Reduzierung der Perfusionszeiten von 20 min auf 2 min fanden sich ein Anstieg der Überlebenszeit von 24,9±5,3 sec auf 33,1±5,4 sec und ein Abfall der Erholungslatenz des Elektrocorticogramms von 16,3±5,8 sec auf 11,7±5,3 sec. War der Abstand zwischen den Ischämien geringer als 2 min, wurde die Überlebenszeit kürzer, die Erholungslatenz stieg an; bei einer Perfusionszeit von 1/2 min betrug die Überlebenszeit 21,5±6,6 sec, die Erholungslatenz 22,5±9,7 sec.
    Notes: Summary Complete 1 min ischemias were performed in isolated heads of dogs perfused from a donor dog. The brain temperature was maintained at 37°C. The perfusion time between complete 1 min ischemias varied from 20 min to 0.5 min. Reduction of the perfusion times from 20 min to 2 min resulted in an increase of survival time from 24.9±5.3 sec to 33.1±5.4 sec and a decrease of latency of recovery of the electrocorticogram from 16.3±5.8 sec to 11.7±5.3 sec. Survival time was reduced and latency of recovery increased when the intervals between ischemias were shorter than 2 min; survival time was 21.5±6.6 sec and latency of recovery 22.5±9.7 sec when the perfusion time was 0.5 min.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 27 (1989), S. 3937-3949 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metathesis ring opening polymerization has been used to copolymerize norbornene and 7,8-bis(trifluoromethyl)tricyclo[4,2,2,02,5]deca-3,7,9-triene. Subsequent thermal elimination of the precursor copolymers yielded acetylene-norbornene copolymers. The undoped copolymers were found to have electrical conductivity, spin concentration, and EPR linewidths which vary with composition. The location of the trans-C—H out-of-plane vibration, however, was invariant at 1010cm-1 indicating that conjugation length of n 〉 4 are present even at 40% acetylene content in the copolymer. The copolymers containing 79 mol % of acetylene units attained a doped conductivity of 0.02 S/cm with a dopant concentration of 6 mol % of I3- per sp2 carbon.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 12 (1981), S. 256-262 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Anisotropy Effects in Copper Alloy Strip MaterialsThe textures and effects of mechanical anisotropy have been measured in several copper alloy strip materials with commercial hardness levels. In most cases mixed textures have been found with a qualitative correlation to the mechanical effects.The optimum position for spring elements proved to be transverse to rolling direction, especially the relation of the elastic limit in bonding to yield strength has a maximum in this direction.
    Notes: Bei Bändern aus verschiedenen Kupferlegierungen in handelsüblichen Festigkeitszuständen wurden die Texturen und die mechanischen Anisotropieeffekte gemessen. In den meisten Fällen wurden Mischtexturen festgestellt, welche die mechanischen Anisotropieeffekte qualitativ erklären.Für Federelemente ist die Querlage die günstigste, insbesondere ist in dieser Richtung das Verhältnis Federbiegegrenze zu Streckgrenze am höchsten.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 25 (1994), S. 63-70 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Investigations on the lattice constants and the calculation of domain sizes and mean squared lattice strains have been presented for PVD-TiN coatings of various thickness on the substrates 52 100 and M2. Constant dependencies have been observed for the lattice constants, domain sizes and lattice strains as a function of the coating thickness. The two different substrate materials have no influence on the mentioned properties.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 11 (1967), S. 305-310 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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: Thermal stabilities of eighteen model compounds related structurally to thermostable polymer systems were determined accurately by pyrolysis-gas chromatography. This approach offers distinct advantages over previously used indirect methods which measure parameters other than actual starting material remaining undecomposed. Both the oxadiazole ring and the aromatic amide link were found to have poor thermal stabilities in comparison with other compounds studied. Since polymers based on these two features have been shown to be valuable for use in air at 200-400°C., the data suggest that oxidation resistance rather than the ultimate in pure thermal resistance should be sought in all-purpose thermostable materials.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 33 (1987), S. 1473-1477 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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: Reduced (4-O-methyl-D-glucurono)-D-xylan and nine methylglycosides related to this polysacharide were studied by dynamic and isothermal thermogravimetry. It could be stated from the results that the thermal stability of saccharides is increasing with increasing number of pyranose units. The models related to (4-O-methyl-D-glucurono)-D-xylan are more thermally stable than the corresponding hexoglycanic models. Rates of gasification of models containing uronic acid methylesters are higher than those of neutral methylglycosides. The rate of polysaccharide gasification was the highest one from all models studied. The supramolecular structure of polysaccharide is dramatically influencing the course of thermal degradation.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 0021-9304
    Keywords: bioprostheses ; type I collagen ; infrared spectroscopy ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Clinical usage of bioprosthetic heart valves (BPHVs) fabricated from glutaraldehyde-pretreated porcine aortic valves is restricted due to calcification-related failure. We previously reported a highly efficacious ethanol pretreatment of BPHVs for the prevention of cuspal calcification. The aim of the present study is to extend our understanding of the material changes brought about by ethanol and the relationship of these material effects to the ethanol pretreatment anticalcification mechanism. Glutaraldehyde-crosslinked porcine aortic valve cusps (control and ethanol-pretreated) were studied for the effects of ethanol on tissue water content and for spin-lattice relaxation times (T1) using solid state proton NMR. Cusp samples were studied for protein conformational changes due to ethanol by ATR-FTIR spectroscopy. The changes in cuspal tissue-cholesterol (in vitro) interactions also were studied. Cusp material stability was assessed in terms of residual glutaraldehyde content and collagenase degradation. Water content of the cusp samples was decreased significantly due to ethanol pretreatment. The cuspal collagen conformational changes (per infrared spectroscopy) brought about by ethanol pretreatment were persistent even after rat subdermal implantation of cusp samples for 7 days. In vitro cholesterol uptake by cusps was greatly reduced as a result of ethanol pretreatment. Ethanol pretreatment of cusps also resulted in increased resistance to collagenase digestion. Cuspal glutaraldehyde content was not changed by ethanol pretreatment. We conclude that ethanol pretreatment of bioprosthetic heart valve cusps causes multi-component effects on the tissue/material and macromolecular characteristics, which partly may explain the ethanol-pretreatment anticalcification mechanism. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 40, 577-585, 1998.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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