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  • Electronic Resource  (26)
  • Polymer and Materials Science  (18)
  • Biochemistry  (4)
  • Chemical Engineering  (2)
  • Circular Dichroism  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 278 (1973), S. 301-312 
    ISSN: 1432-1912
    Keywords: Circular Dichroism ; Benzodiazepines ; Albumin-Binding ; Partition Coefficients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The circular dichroism spectra of 12 benzodiazepine derivatives studied in presence of human serum albumin are presented. Nearly all substances give biphasic extrinsic Cotton effects. At the CD maxima the molar ellipticities and the anisotropy factors are calculated. The influence of the chemical structure of the benzodiazepines on the induced Cotton effect is discussed. There is a linear correlation between the anisotropy factors and the logarithms of the partition coefficients of the substances. It is suggested that the phenyl ring of the benzodiazepine molecule is one of the essential groups for the binding of these substances to human serum albumin.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 283 (1974), S. 67-82 
    ISSN: 1432-1912
    Keywords: Benzodiazepines ; Albumin Binding ; Circular Dichroism ; Gel Filtration ; pH Dependence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The influence of pH on the binding of benzodiazepine derivatives to HSA was studied by circular dichroism measurements and by gel filtration. The binding of nearly all benzodiazepines is increased by rising the pH from 6.60 to 8.20. For flurazepam, clonazepam, and nitrazepam this increase in binding is due to an increase of the affinities, while for the other substances the affinity remains constant and the number of binding sites is increased from one to two. The changes in binding of the benzodiazepines by rising the pH are explained by a cationic amino acid residue near or at the benzodiazepine binding site of the HSA molecule. This second binding site is not detectable by circular dichroism. For several of the substances rising the pH from 6.60 to 8.20, is accompanied by large alterations of the optical properties of the HSA-benzodiazepine complexes. These alterations are explained by changes of the asymmetric environment of the benzodiazepine binding site at the HSA molecule in the structural transition at slightly alkaline pH values. To explain the different reactions of the benzodiazepines within the N→B transition a theory is given.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 5 (1961), S. 375-383 
    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: The effects on viscose ripening of a variety of materials are reported. (1) Normal constituents (Na2CO3, Na2CS3, NaCl) appeared not to affect ripening; however, Na2S retarded ripening. By-product removal appeared to retard ripening. (2) Oxidizing agents (H2O2, Na2Sx) accelerated ripening; reducing agent (Na2SO3) retarded ripening; this is suggestive of possible addition product formation. (3) Na2SO4, (CH3)2SO, KClO3, Na2BH4 showed no effect on ripening. (4) Salts which precipitated as hydroxides or carbonates did not appear to affect ripening. (5) Salts which formed insoluble sulfides resulted in an initial increase in ripening rates. In later stages, ripening proceeded normally, probably after the salts were removed from solution as insoluble sulfides. (6) FeCl3, BiCl3 and Na3AsO3 appeared to retard ripening. (7) A comparison of the effect on ripening of the trivalent state of elements in group V of the periodic table showed that the rate of ripening decreased with the oxidation potential of the element. (8) The addition of sodium zincate retarded ripening and suggested possible cross-linking of xanthate and by-product sulfur, or of two xanthate groups. (9) Addition of tin and chromium salts at the 0.5% level resulted in gelation of the viscose within 30 min. after the addition.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 12 (1981), S. 11-13 
    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: Quality Control of HDPE Pipes.Trials are reported made with the aim of finding an correlation between creep rupture test results obtained with two different types of testing samples: Pipes under internal pressure and tensile rods cut out of these pipes in a longitudinal direction.
    Notes: Es wird über Versuche berichtet, eine Korrelation zwischen Ergebnissen aus Zeitstand-Innendruckversuchen an HDPE-Rohren und Zeitstandversuchen an Längszugstäben aus diesen Rohren zu finden.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 19 (1968), S. 22-25 
    ISSN: 0947-5117
    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: Creep strength and chemical resistance pipes made of hard polyethylene and polypropyleneThe creep strength of pipes made of thermoplastics is influenced by the surrounding medium. This influence may be of a chemical or physical kind. Often, both influences are simultaneously present. The present paper deals with these different types of influences of chemical substances on the creep strength of pipes made of hard polyethylene and polypropylene. First, the test method is described by which the creep strength is investigated in the presence of chemical stresses. This is followed by the communication of results obtained with different obcals. These include inorganic as well as organic media. According to these results the inorganic substances can, in respect of their effect on the creep strength, be divided into the following four categories: 1aqueous solutions of non-oxidant substances,2aqueous solutions of oxidant substances,3aqueous solutions of wetting agents,4aqueous solutions of substances which penetrate into polyethylene in small quantities, thus causing Some Sort swelling.The organic substances can be divided into those with strong and with weak swelling effects. The swelling effect, which depends on the chemical structure of the substances, is described in some detail.
    Notes: Die Zeitstandfestigkeit von Rohren aus thermoplastischen Kunststoffen wird durch das umgebende Medium beeinflußt. Dieser Einfluß kann chemischer oder physikalischer Art sein. Oft sind beide Einflüsse gleichzeitig wirksam. Die vorliegende Arbeit behandelt diese verschiedenen Arten des Einflusses chemischer Substanzen auf die Zeitstandfestigkeit von Rohren aus Hartpolyäthylen und Polypropylen. Es wird zunächst die Prüfmethode beschrieben, nach der die Zeitstandfestigkeit bei gleichzeitiger chemischer Beanspruchung untersucht wird. Anschließend werden Ergebnisse mitgeteilte, die mit verschiedenen Chemikalien gewonnen wurden. Es wird dabei sowohl auf anorganische als auch auf organische Medien eingegangen. Nach diesen Ergebnissen können die anorganischen Substanzen hinsichtlich ihrer Wirkung auf die Zeitstandfestigkeit in folgende vier Gruppen eingeteilt werden: 1wäßrige Lösungen von nicht oxydierend wirkenden Substanzen;2wäßrige Lösungen von oxydierend wirkenden Substanzen;3wäßrige Lösungen von Netzmitteln;4wäßrige Lösungen von Substanzen, die in geringer Menge in Polyäthylen eindringen und dadurch eine Art Quellung bewirken.Die organischen Substanzen körnert in stark und schwach quellend wirkende eingeteilt werden. Auf die Quellung, die von der chemischen Struktur der Substanzen abhängig ist, wird näher eingegangen.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 25 (1994), S. 329-340 
    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: Effect of Process Parameters in Extrusion on Fatigue BehaviourFatigue test specimens were produced by forward extrusion and subsequent heading from conventional steels, P/M steels and AlMg4.5Mn. The strain, die-opening angle, temperature and in some cases the lubricant were varied. For purpose of comparation in some cases also specimens were prepared by machining. S/N curves or cyclic deformation curves were determined mainly by stress-controlled tests.For all materials the time strength was increased by cold forming whereby the effect of strain was stronger than that of the die-opening angle. The time strength of steel is less increased by warm (semihot) forming than by cold forming. The fatigue strength, however, is not necessarily increased by cold or warm forming. After cold forming the P/M steels contrary to conventional steels revealed mainly quasielastic deformation until fracture. After warm forming, however, P/M steels, due to the decrease of porosity, behaved almost like conventional steels. For AlMg4.5Mn specimens prepared by forming - probably due to worse surface quality - revealed a lower fatigue strength than those prepared by machining. Here also a feasible effect of the choice of the lubricant was stated.
    Notes: Aus schemelzmetallurgischen und Sinterstählen sowie AlMg4,5Mn wurden durch Fließpressen und Anstauchen von Köpfen bauteilähnliche Schwingproben hergestellt. Dabei wurden Umformgrad, Schulteröffnungswinkel, Temperatur und z.T. der Schmierstoff variiert. Zu Vergleichszwecken wurden in Einzelfällen Schwingproben spannend hergestellt. Wöhlerkurven oder Wechselverformungskurven wurden zumeist in spannungskontrollierten Versuchen ermittelt. Für alle Werkstoffe wurde eine Erhöhung der Zeitfestigkeit durch eine Kaltumformung beobachtet. Der Einfluß des Schulteröffnungswinkels war schwächer als der des Umformgrades. Eine Halbwarmumformung von Stahl steigert die Zeitfestigkeit weniger als eine Kaltumformung. Die Dauerfestigkeit wird durch Kalt- oder Halbwarmumformung nicht notwendig gesteigert. Die Sinterstähle zeigten kaltfließgepreßt anders als konventionelle Stähle vornehmlich quasielastische Verformung bis zum Bruch. Halbwarmumgeformt verhalten sich Sinterstähle jedoch aufgrund der verringerten Porosität nahezu wie konventionelle. Für AlMg4,5Mn zeigten umgeformte Schwingproben im Vergleich zu spanend gefertigten - vermutlich aufgrund der schlechteren Oberfläche - eine niedrigere Dauerfestigkeit; hier wurde auch ein deutlicher Einfluß des Schmierstoffes beobachtet.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 25 (1994), S. 341-348 
    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: On the quantitative valuation of thermally activated material reactionsThis paper gives an insight into the fundamentals and application of the quantitative valuation of thermally activated material reactions, especially of static softening processes. Possibilities of calculating based on diffusion and chemical kinetics are reported not only for isothermal, but also generally for thermally nonstationary conditions. The special cases of constant heating or cooling rates and of constant temperatures which nearly exclusively have been described in the literature follow automatically from these more universal equations given here. For a more precise description of softening processes it is proposed that the ARRHENIUS formula is modified and generalized by introducing a temperature threshold value, i.e., a minimum or reference temperature. This allows the material softening process that independently of time always can be observed only above a minimum temperature to be represented in this way also by the physical-mathematical model. Integrals are calculated and explizit solutions are given for characteristic temperature-time dependences. Finally, the fundamental method of determining the model parameters is described.
    Notes: Der Beitrag gibt einen Einblick in Grundlagen und Anwendung der quantitativen Bewertung thermisch aktivierter Werkstoffreaktionen, insbesondere bei statisch ablaufenden Entfestigungsvorgängen. Berechnungsmöglichkeiten werden auf der Grundlage von Diffusion und chemischer Kinetik nicht nur für isotherme, sondern allgemein für thermisch beliebig instationäre Bedingungen angegeben. Die im Fachschrifttum fast ausschließlich betrachteten Spezialfälle konstanter Erwärmungs- oder Abkühlraten und konstanter Temperaturen ergeben sich aus den hier angegebenen allgemeingültigeren Gleichungen zwanglos. Zur präziseren Beschreibung von Entfestigungsvorgängen wird vorgeschlagen, den Arrhenius-Ansatz dahingehend zu modifizieren bzw. zu verallgemeinern, daß ein Temperaturschwellenwert - eine Mindestbzw. Bezugstemperatur - in geeigneter Weise eingeführt wird. Dadurch wird erreicht, daß eine Werkstoffentfestigung, die - praktisch unabhängig von der Zeitdauer - immer erst oberhalb gewisser Mindesttemperaturen beobachtbar ist, in dieser Weise auch durch das physikalisch-mathematische Modell erfaßt und widergespiegelt wird. Für charakteristische Temperatur-Zeit-Abhängigkeiten werden die auftretenden Integrale berechnet und explizite Lösungen angegeben. Abschließend wird der prinzipielle Weg zur Bestimmung der Modellparameter skizziert.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 1499-1501 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 15 (1964), S. 51-58 
    ISSN: 0947-5117
    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: Application of large-diameter pipes made of hard polyethyleneWith the aid of numerous illustrations, the applications of polyethylene pipes of relatively large diameters are surveyed. A special account is given of the advantages which such pipes may offer under different installation conditions. Especially in the Scandinavian countries  -  Norway, Finland and Sweden  -  where pipes are laid in the open even during the winter months, the toughness of hard polyethylene, even at low temperatures, is found to be a particular advantage. A special problem is posed by the need for a reliable jointing of large-diameter pipes. It is shown that, if the necessary conditions are adhered to, and if suitable aids are used, it is possible to obtain reliable butt welds, both between one pipe and another, and between pipe and welding collar. Such welding collars can be made in different ways. For instance, a mould is filled with the aid of an extruder and a rough cast prepared which, after cooling, is machined on a lathe. Pipes made of hard polyethylene are used not only for drinking water pipes but also for special purposes, e. g. cable protection pipes. For this purpose, a special technique, known as jetting method, is sometimes used for laying pipes across water.
    Notes: Anhand einer großen Anzahl van Bildern wird über den Einsatz van Rohren relativ großen Durchmessers aus Hart-Polyäthylen berichtet. Dabei wird auch auf die Vorteile, die solche Rohre unter den verschiedensten Verlegebedingungen bieten, näher eingegangen. Gerade in skandinavischen Ländern wie Norwegen, Finnland und Schweden, wo auch während der Wintermonate Rohrverlegungen im Freien stattfinden, erweist sich die gute Zähigkeit von Hart-Polyäthylen auch in der Kälte von besonderem Vorteil. Ein besonderes Problem stellt die zuverlässige Verbindung von Rohren großen Durchmessers der. Es wird gezeigt, daß bei Einhaltung der erforderlichen Bedingungen und bei Verwendung geeigneter Hilfsgeräte einwandfreie Stumpfschweißungen sowohl der Rohre untereinander als auch von Rohr und Vorschweißbund erzielt werden können. Die Herstellung solcher Vorschweißbunde kann auf verschiedene Arten vorgenommen werden; z. B. wird mit Hilfe eines Extruders eine Form gefüllt und durch Pressen ein Rohling hergestellt, der nach dem Erkalten auf einer Drehbank bearbeitet wird. Neben der Verwendung van Rohren aus Hart-Polyäthylen für Trinkwasserleitungen werden sie auch für Spezialzwecke, wie z. B. Kabelschutzrohre, eingesetzt. Dabei wird in manchen Fällen eine besondere Verlegetechnik beim Durchqueren van Gewässern, das sog. Einspülverfahren, angewandt.
    Additional Material: 36 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 29 (1989), S. 954-959 
    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 this paper we describe the synthesis, characterization, and lithographic evaluations of novel positive photoresists based on hydroxy polyimides and polyamides containing 6-F linking groups. The polymers were synthesized using solution condensation techniques and characterized using solution viscosity, GPC, FTIR, NMR, UV, TGA, and DSC. Tg's of these polymers range from 250 to 300°C. Both polyimides and polyamides are soluble in a variety of solvents commonly utilized for photoresist applications. When formulated with diazonaphthoquinone sensitizers, these polymers provide an improved high-temperature resistant, aqueous base developable positive photoresist system with good photospeed, contrast, and resolution characteristics. High resolution relief images were obtained which are comparable to 1300 Series AZ type photoresists. No thermal deformation, loss in resolution or defects were noticed when relief patterns were annealed to 250°C. Additionally, the hydroxy polyamide based resists, when thermally annealed to 300°C, provide a photoresist system with even higher thermal stability (400 to 450°C) and excellent resistance to solvents. Also, the photoresist formulations have excellent storage stability at room temperature and can be processed like conventional positive photoresists using broad band UV radiation sources.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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