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  • Polymer and Materials Science  (18)
  • Benzodiazepines  (4)
  • Circular Dichroism  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Interactions of benzodiazepines with human serum albumin (1973)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 278 (1973), S. 301-312 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF00500291
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  • 2
    Electronic Resource
    Electronic Resource
    Characterization of the binding of benzodiazepines to human serum albumin (1973)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 280 (1973), S. 229-237 
    Details
    ISSN: 1432-1912
    Keywords: Benzodiazepines ; Albumin Binding ; Gel Filtration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The binding of eleven benzodiazepine derivatives to human serum albumin (HSA) was determined by means of sephadex gel filtration. The albumin binding of the substances was characterized by the percentage of bound drug, the binding constants k +, K 1 and m, the number of binding sites per albumin molecule, and the free binding energy. Under the conditions chosen in these experiments there seems to exist only one binding site of the same type for all investigated benzodiazepines at the HSA molecule. The affinities of the benzodiazepines to this binding site are very different. It is discussed which part of the benzodiazepine molecule represents the main binding group.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00501348
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  • 3
    Electronic Resource
    Electronic Resource
    Influence of pH on the benzodiazepine-human serum albumin complex (1974)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 283 (1974), S. 67-82 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF00500146
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  • 4
    Electronic Resource
    Electronic Resource
    Benzodiazepines: Specific competitors for the binding of l-tryptophan to human serum albumin (1975)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 288 (1975), S. 17-27 
    Details
    ISSN: 1432-1912
    Keywords: Human Serum Albumin Binding ; l-Tryptophan ; Displacing Agents ; Benzodiazepines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary By means of the gel filtration technique, the effect of nine benzo-diazepine derivates on the binding of l-tryptophan to human serum albumin was investigated. Using equimolar tryptophan and benzodiazepine concentrations, all benzodiazepines with binding constants higher than 104 (M−1), displace l-tryptophan from its binding site to a high degree. The mechanism of the displacement was characterized as a competition for a common binding site. Some of the benzodiazepines displace l-tryptophan to a greater extent than salicylic acid. The benzodiazepines and tryptophan are the only substances known with a high degree of stereospecific binding to human serum albumin. This study shows that there is only one binding site on the human serum albumin molecule, which binds tryptophan and the benzodiazepines in a highly stereospecific manner. Therefore it is concluded that the benzodiazepines and l-tryptophan must have similarities in their molecular structure, so that both can bind to the common binding site in such specific manner. These considerations are discussed in regard to the known influence of benzodiazepine derivatives on the l-tryptophan metabolism in brain. A direct involvement of the reported displacement in the pharmacological actions of the drugs seems not to be relevant because of their small therapeutical plasma levels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00501811
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  • 5
    Electronic Resource
    Electronic Resource
    Qualitätskontrolle von Rohren aus HDPEHerrn Dr.-Ing. Kurt Richard zum 70. Geburtstag gewidmet (1981)
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 12 (1981), S. 11-13 
    Details
    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
    URL: http://dx.doi.org/10.1002/mawe.19810120105
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  • 6
    Electronic Resource
    Electronic Resource
    Einfluß von Verfahrensparametern beim Fließpressen auf das Ermüdungsverhalten (1994)
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 25 (1994), S. 329-340 
    Details
    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
    URL: http://dx.doi.org/10.1002/mawe.19940250807
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  • 7
    Electronic Resource
    Electronic Resource
    Beitrag zur quantitativen Bewertung thermisch aktivierter Werkstoffreaktionen (1994)
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 25 (1994), S. 341-348 
    Details
    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
    URL: http://dx.doi.org/10.1002/mawe.19940250809
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  • 8
    Electronic Resource
    Electronic Resource
    Eigenschaften von Polypropylen unter besonderer Berücksichtigung des chemischen ApparatebausVortrag anläßlich des DECHEMA-Kolloquiums am 5. 4. 63. (1963)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 14 (1963), S. 925-930 
    Details
    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: Properties of polypropylene, particularly from the point of view of chemical equipmentApart from polyethylene, isotactic polypropylene is gaining increasing importance. The special properties of this material have soon been found particularly advantageous in the technical sector. A number of properties such as density, softening point, permeability to gases, hardness, stuffness and the excellent resistance to chemicals are due to the structure of the polymer. Another valuable property is the good suitability of the material for welding. It has already been possible to gather experience in this sphere, on a large scale, from the processing of semi-finished products from low-pressure polyethylene. Apart from wire welding, much use is also being made of heat element welding (without auxiliary wire).From the point of view of chemical equipment, an important property is the so-called long-term strength or long-term behaviour. This is illustrated by a number of diagrams in regard to contact with water, air and chemicals, e.g. sulphuric acid of different degrees of concentration.
    Notes: Neben dem Polyäthylen gewinnt das isotaktische Polypropylen mehr und mehr an Bedeutung. Die speziellen Eigenschaften dieses Materials haben sich sehr schnell als für den technischen Sektor besonders günstig erwiesen. Aus der Struktur des Polymeren erklärt sich eine ganze Reihe von Eigenschaften, z. B. Dichte, Erweichungspunkt, Permeabilität von Gasen, Härte, Steifigkeit und die ausgezeichnete Chemikalienbeständigkeit. Eine weitere wertvolle Eigenschaft stellt die gute Verschweißbarkeit dar. Erfahrungen auf diesem Gebiet konnten schon in großem Umfang bei der Verarbeitung von Halbzeug aus Niederdruckpolyäthylen gewonnen werden. Neben der Drahtschweißung wird auch sehr oft die Heizelementschweißung (ohne Zusatzdraht) angewandt.Wichtig für den chemischen Apparatebau ist die sogenannte Zeitstandfestigkeit bzw. das Zeitstandverhalten. In verschiedenen Diagramme wird dies in Kontakt mit Wasser, Luft und Chemikalien, z. B. Schwefelsäure verschiedener Konzentration, dargestellt.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19630141102
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  • 9
    Electronic Resource
    Electronic Resource
    Anwendung von Rohren großen Durchmessers aus HartpolyäthylenHerrn Prof. Dr. E. Rabald zum 65. Geburtstag gewidmet (1964)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 15 (1964), S. 51-58 
    Details
    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
    URL: http://dx.doi.org/10.1002/maco.19640150109
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  • 10
    Electronic Resource
    Electronic Resource
    Effects of by-products, trace components, and similar compounds in viscose on ripening (1961)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 5 (1961), S. 375-383 
    Details
    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
    URL: http://dx.doi.org/10.1002/app.1961.070051601
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