Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Polymer and Materials Science  (8)
  • Aminophospholipid translocase  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Mathematical modelling of lipid transbilayer movement in the human erythrocyte plasma membrane (1993)
    Springer
    European biophysics journal 22 (1993), S. 213-223 
    Details
    ISSN: 1432-1017
    Keywords: Phospholipid asymmetry ; Aminophospholipid translocase ; Transbilayer diffusion ; Lipid flip-flop (erythrocyte membrane)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract A model is presented to simulate transverse lipid movement in the human erythrocyte membrane. The model is based on a system of differential equations describing the time-dependence of phospholipid redistribution and the steady state distribution between the inner and outer membrane monolayer. It takes into account several mechanisms of translocation: (i) ATP-dependent transport via the aminophospholipid translocase; (ii) protein-mediated facilitated and (iii) carrier independent transbilayer diffusion. A reasonable modelling of the known lipid asymmetry could only be achieved by introducing mechanism (iii). We have called this pathway the compensatory flux, which is proportional to the gradient of phospholipids between both membrane leaflets. Using realistic model parameters, the model allows the calculation of the transbilayer motion and distribution of endogenous phospholipids of the human erythrocyte membrane for several biologically relevant conditions. Moreover, the model can also be applied to experiments usually performed to assess phospholipid redistribution in biological membranes. Thus, it is possible to simulate transbilayer motion of exogenously added phospholipid analogues in erythrocyte membranes. Those experiments have been carried out here in parallel using spin labeled lipid analogues. The general application of this model to other membrane systems is outlined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00185783
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Transverse mobility of aminophospholipids in the plasma membrane of ram sperm cells (1996)
    Springer
    Pflügers Archiv 431 (1996), S. R255 
    Details
    ISSN: 1432-2013
    Keywords: Sperm cells ; Plasma membrane ; Lipid asymmetry ; Aminophospholipid translocase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The transbilayer movement of aminophospholipids in the plasma membrane of ram sperm cells was investigated using spin-labeled lipid analogues. After incorporation, spin-labeled phospliatidylserine (SL-PS) and phosphatidyl-ethanolamine (SL-PE) rapidly disappeared from the exoplasmic monolayer. Even at lower temperatures (10°C) the inward movement of SL-PE is fast. The initial velocities of the internalization of SL-PS and SL-PE were compared with those of ram and human erythrocytes
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02346365
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Polymerphysikalische Charakterisierung von Sol/Gel-ElastomerenHerrn Prof. Dr. H. Grünewald zum 60. Geburtstag gewidmet (1981)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 98 (1981), S. 97-112 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The stress-strain behaviour of sol/gel-polymers of 2-chloro-butadiene was investigated. The modulus of the raw polymers increases linearly while the gel component increases. Einstein's equation which deals with the viscosity of colloidal suspensions is applicable to the sol/gel-systems in investigation. There exist no strong interactions between the gel particles and the sol matrix which are characteristic for active fillers, so that the gel particles are able to move freely in the shear gradient of a processing machine without remarkable deformation. During vulcanization of the sol/gel-rubbers in investigation, the gel particles are only insufficiently covulcanized with the sol matrix. When the gel fraction of the rubber increases, and when the amount of vulcanizing agents in the sol phase increases, the homogenization of tension in the vulcanizate is increasingly disturbed. Tensile strength and ultimate elongation of the vulcanizate are impaired on account of the disadvantageous network structure which takes rise from the overcure and from the insufficient connexion between the gel particles and the sol phase.
    Notes: Es wurde das Zug-Dehnungs-Verhalten von Sol/Gel-Polymeren aus 2-Chlorbutadien untersucht. Der E-Modul der Rohpolymeren steigt linear mit deren Gelanteil. Für die untersuchten Sol/Gel-Systeme gilt die Einsteinsche Beziehung über die Viskositätserhöhung kolloidaler Suspensionen. Zwischen Gelpartikeln und Solmatrix bestehen keine starken, aktive Füllstoffe kennzeichnende Wechselwirkungen, so daß die Gelpartikel im Schergradienten einer Verarbeitungsmaschine (z. B. Extruder) als quasistarre Kugeln abzugleiten vermögen und keine wesentliche Deformation erfahren. Bei der Vulkanisation der untersuchten Sol/Gel-Kautschuke werden die Gelpartikel nur unzureichend mit einer Solmatrix verknüpft. Die Spannungshomogenisierung im Vulkanisat wird zunehmend behindert, wenn der Gelanteil des Kautschuks zunimmt und wenn die Vernetzerkonzentration in der Solphase zunimmt. Durch die ungüstige Netwerkstruktur, die durch Übervernetzung und durch unzureichende Verknüpfung der Gelteilchen mit der Solphase entsteht, werden Zugfestigkeit und Bruchdehnung des Vulkanisats vermindert.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1981.050980105
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Polyuretdionpolyurethane und blockierte polyuretdioneneue rohstoffe für pulverlackeHerrn Prof. Dr. Dr. h. c. mult. Dr. E. h. mult. Otto Bayer zum 75. Geburtstag gewidmet (1977)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 65 (1977), S. 23-39 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: This paper is concerned with the ring opening of the uretdione group in presence of nucleophilic partners and of the technological significance of this reaction. It is shown that at temperatures from 100° to 120°C both polyesters containing hydroxyl groups and low-molecular weight compounds carrying Zerewitinow-active hydrogen atoms react in solution as well as in the molten state with free NCO groups of uretdione diisocyanates by the diisocyanate polyaddition process. Under these conditions no opening of the uretdione ring occurs.These results give rise to the use of uretdione diisocyanates for chain extensions yielding polyuretdione polyurethanes. Reactions with blocking agents (e.g. ε-caprolactam) result in new types of blocked uretdione and blocked polyuretdione polyurethanes. It is shown that the four-membered rings are split completely at temperatures from 140° to 180°C. Compounds containing hydroxyl groups which are available in the reaction mixture react with the latent NCO groups of the uretdiones to form urethanes. By selection and combination of suitable starting compounds crystalline, high-melting polyuretdione polyurethane powders of good milling properties can be obtained. The new syntheses of technical usefulness yield non-polluting polyurethane powder coatings for application by electrostatic spraying.
    Notes: Die Ringöffnung der Uretdiongruppe in Gegenwart von nukleophilen Reaktionspartner und die technische Bedeutung dieser Reaktionsind Gegenstand der vorliegenden Arbeit. Die Untersuchungen machen deutlich, daß hydroxylgruppenhaltige Polyester und niedermolekulare Zerewitinow-aktive Wasserstofftome tragende Verbindungen sich bei Temperaturen von 100-120°C in Lösung, aber auch in der Schmelze mit den freien NCO-Gruppen der Uretdiondiisocyanate nach dem Diisocyanat-Polyadditionsver-faren umsetzen lassen, ohne daß nennenswerte Uretdionringöffnung eintritt. Auf Grund dieser Erkenntnis können mit den Uretdiondiisocyanaten Kettenverlängerungen zu Poly-uretdionpolyurethanen durchgeführt werden. Durch Umsetzung mit Blockierungsmitteln (z.B.ε-Caprolactam) werden neuartige blockierte Uretdione und blockierte Polyuretdion-polyurethane erhalten. Es wird nachgewiesen, daß die Vierringe im Temperaturbereich von 140-180°C vollständig aufspalten. Gleichzeitig vorliegende hydroxylgruppenhaltige Verbindungen reagieren mit den latenten NCO-Gruppen der Uretdione unter Urethanbildung. Durch geeignete Wahl und Kombinatio der Asgangsverbindungen lassen sich kristalline, hochschmelzende, gut mahlbare Polyuretdionpolyurethanpulver gewinnen. Die neuen technisch verwertbaren Synthesen führen zu umweltfreundlichen, lösungsmittel-freien Verfahen der elektrostatischen Pulverbeschichtung.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1977.050650102
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Neue Bausteine für das Diisocyanat-Polyadditions-Verfahren, I. Polyole aus FormaldehydHerrn Prof. Dr. Otto Bayer in memoriam gewidmet (1982)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 108 (1982), S. 79-99 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Formaldehyde, one of the most important C1-building blocks in organic synthesis (starting from methanol), can be converted by polymerisation using basic catalysts into a mixture of synthetic sugars (formose), and, after the catalytic hydrogenation of these, into a mixture of polyhydroxyl compounds (formitol). Deductions are drawn from studies of the catalysis, co-catalysis and course of the formose reaction, which has been known for a long time, and these enable the commercial and economical use of the formose synthesis. Formose, and in particular formitol, are suitable for use as a new class of crosslinking agents in polyurethane foams, as starters for new polyether polyols and for the synthesis of polyester polyols.
    Notes: Formaldehyd, einer der wichtigsten C,-Bausteine in der organischen Synthese (Methanol-Stammbaum), 1mt sich durch Polyaddition mit Hilfe basischer Katalysa-toren in ein Gemisch synthetischer Zucker (Formose) bzw. nach deren katalytischer Hydrierung, in ein Gemisch von Polyhydroxylverbindungen (Formit) iiberfiihren. Aus Untersuchungen der Katalyse, Co-Katalyse und des Reaktionsablaufs der lange bekannten Formose-Reaktion werden Folgerungen gezogen, welche eine groatechni-sche und wirtschaftliche Verwertbarkeit der Formose-Synthese ermbglichen. Formose und insbesondere Formit kbnnen als neuartige Vernetzer in Polyurethanschaum-stoffen, als Starter fur neuartige Polyether-polyole sowie zur Synthese von Polyester-polyolen herangezogen werden.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1982.051080105
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Neue Bausteine für das Diisocyanat-Polyadditions-Verfahren, II. Aminoplastdispersionen in Polyolen - ein Weg zu schwer entflammbaren PUR-WeichschaumstoffenHerrn Prof. Dr. Otto Bayer in memoriam gewidmet (1982)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 108 (1982), S. 101-112 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Stable aminoplast dispersions can be obtained by new, commercially interesting syntheses. Nature and quantity of the catalysts used - the concentration of hydrogen ions and salts  - , the presence and quantity of water, and the temperature profile have an effect on the storage stability, setting, particle size, and particle size distribution of the condensation products dispersed in the polyether polyols and, in correlation, on the ultimate viscosity of the aminoplast dispersions. The aminoplast dispersion can be manufactured on conventional foaming equipment according to cold curing PUR-foam formulations with toluylene diisocyanate (® Desmodur T 80).Besides acceptable values for the physical properties such as rigidity, elasticity, and tensile strength, the resultant cold cured foams give a striking result in the flammabil-ity test acc. to DIN 4102 inasmuch as they reach Flammability Classification B 1. Yet there are no definitive results about a thinkable emanation of formaldehyde out of such dispersions under the conditions of use.
    Notes: Stabile Aminoplastdispersionen lassen sich nach neuen, technisch interessanten Synthesewegen herstellen. Die Lagerstabilität, Aushörtung, Teilchengrößie und Teilchengrößeverteilung der in den Polyetherpolyolen dispergierten Kondensationsprodukte und damit korrelierend die Endviskosität der Aminoplastdispersionen werden durch die Art und Menge der venvendeten Katalysatoren - die Wasserstoffionen und Salzkonzentration  - , die Anwesenheit und Menge von Wasser und durch die Temperaturführung beeinflußt. Die Aminoplastdispersion ist auf herkömmlichen Verschäumungsanlagen nach PUR-Kaltschaumrezepturen mit Toluylendiisocyanat (®Desmodur T 80) verarbeitbar. Die resultierenden Kaltschaumstoffe erreichen  -  neben guten Werten fur die mechanischen Eigenschaften wie Härte, Elastizität und Reififestigkeit - im Brandtest nach DIN 4102 iiberraschenderweise die Brandklasse B 1 . Uber die denkbare Abspaltung von Formaldehyd unter den Bedingungen der Anwendung solcher Dispersionen liegen noch keine abschliefienden Ergebnisse vor.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1982.051080106
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Die Chromatographie, eine zentrale Methode in der biotechnischen AufarbeitungVortrag von P. Müller auf dem Jahrestreffen der Verfahrens-Ingenieure, 27. bis 29. Sept. 1989 in Berlin. (1990)
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 62 (1990), S. 380-390 
    Details
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Chromatography, an essential method for downstream processing in biotechnology. More than ten years ago, largescale chromatography was established for isolation and purification of high molecular weight natural products, such as proteins and nucleic acids, from fermentation broths and extracts of animal and plant tissues. This was a result of the development of rigid, hydrophilic, and biocompatible polymers with large pore sizes. Compared to the precipitation methods previously used on a large scale, chromatography offers in particular the possibility of producing blood proteins and enzymes of higher purity on a technical scale and without pollution. The various chromatographic methods involve many separation possibilities with excellent selectivities. Progress in improving the chromatographic materials together with advanced equipment were the basis for present-day importance of chromatography in biotechnology downstream processing.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cite.330620506
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Neue Bausteine für das Diisocyanat-Polyadditionsverfahren, III NCO-Trimerisate durch PhasentransferkatalyseHerrn Prof. Dr. Otto Bayer in memoriam gewidmet (1983)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 113 (1983), S. 1-9 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The know-how on solid/liquid phase transfer catalysis, which has, over the past decade, become a firm part of preparative organic chemistry, is applied to the long-known utilization of basic alkali metal salts as trimerisation catalysts for isocyanates. By complexing with the aid of open-chain polyethylene glycols, which contain on average 5-8 oxyethylene units, it has become possible for the first time to use potassium acetate as a soluble and highly active (“activated anion”) trimerisation catalyst for the production of paint isocyanates with an isocyanurate structure.
    Notes: Die Erkenntnisse der Fest-Flüssig-Phasentransfer-Katalyse, die im letzten Jahrzehnt zu einem festen Bestandteil der präparativen organischen Chemie geworden ist, werden auf die seit langem bekannte Nutzung der basischen Alkalimetallsalze als Trimerisationskatalysatoren für Isocyanate übertragen. Durch Komplexierung mit Hilfe von offenkettigen Polyethylenglykolen, die im Mittel 5 bis 8 Ethylenoxideinheiten enthalten, gelingt es erstmals, Kaliumacetat als löslichen und hochaktiven („Anionenaktivierung“) Trimerisationskatalysator bei der Herstellung von Lackisocyanaten mit Isocyanurat-Struktur einzusetzen.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1983.051130101
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Langevin dynamics simulations of macromolecules on parallel computersThis work is supported by the DFG-Schwerpunktprogramm “Effiziente Algorithmen für diskrete Probleme und ihre Anwendungen”, grant LE 952/1-1. (1997)
    Weinheim : Wiley-Blackwell
    Macromolecular Theory and Simulations 6 (1997), S. 507-521 
    Details
    ISSN: 1022-1344
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A parallel algorithm is developed that allows efficient Langevin-dynamics simulations of macromolecular coils, which is the usual structure of synthetic polymers in solution and in bulk. Contrary to usual so-called spatial decomposition algorithms, we map the one-dimensional topology of the chain molecule on the parallel computer. The speedup of the algorithm is measured on different multi-processor systems. The reliability of the parallel calculations is shown by comparison with sequential simulations.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mats.1997.040060213
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Sind polyurethanwerkstoffe ein reifes gebiet? (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 244 (1997), S. 121-133 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The world-wide production of polyurethanes has exceeded 6 mio. metric tons in 1994. Compared with the produced amounts of large-scale thermoplastics such as PE, PVC, PP and PS, polyurethanes keep the 5th place.Polyurethanes (PUR) are segmented polymers, which can be synthesized from preformed building blocks in a modular unit construction system. The chemical modules and the various possibilities of combination will be discussed here.Tailor-made polyurethane materials can be divided into two main-fields of application: foams and compact PUR.The main constituents of polyurethane materials are diisocyanates and polyols. These key- chemicals are well characterised with respect to their technological, economical and ecological properties. Taking into account the availability, the masses of production and the experiences that have been collected with the PUR main constituents, these PUR precursors seem to be very mature already.In contrast to this, the PUR-materials made from these building blocks still offer numerous novel problem-solutions, resulting from the variability of the diisocyanate-poly-addition reaction: PUR materials are most commonly segmented into several phases. The formation of hard- and softsegments can be easily demonstrated by looking at thermoplastic polyurethanes (TPU). A deeper understanding of this phase separation and the molecular organisation within these materials promises to realize prospectic polymeric architectures with new and improved properties. PUR materials will still be able to offer new answers to future requirements in balancing economical and ecological needs. By looking at the life-cycles of soft and hard-foams, polyurethane-coatings and thermoplastic PUR-elastomers, this contribution will adress the question: “Is PUR-chemsitry still a challenging field?”
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1997.052440106
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...