ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

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
  • 1985-1989  (10)
  • 1
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The influence of soft contact lenses (SCL) with low (37%, L) and high (65%, H) water content on rabbit corneas was investigated. The lenses were worn continuously for 1, 2, 4, 7, 10, 14, 21 or 28 days. The changes in corneal transparency, hydration and enzyme activities were studied. A slight change in corneal transparency due to higher hydration caused by a decreased activity of Na+−K+-dependent adenosine triphosphatase (Na+−K+-ATPase) in the corneal endothelium is followed by a decrease in the activity of γ-glutamyl transferase (GGT). Slight morphological disturbances appear within 4 days in animals wearing SCL (L). SCL (H) produce similar changes one week later. Subsequently, the corneal epithelium becomes thinner and changes in the size of corneal endothelial cells are obvious. Disturbances of enzyme activities in cells of all corneal layers are present. In the epithelium highly increased activities of acid glycosidases, acid phosphatase, and dipeptidyl peptidase I and II, in keratocytes decreased activities of alkaline phosphatase and GGT, and in the endothelium decreased activity of Na+−K+-ATPase and GGT were found. These changes are more severe after SCL (L). In this case, inflammatory cells displaying high activities of lysosomal hydrolases appear in the anterior part of the stroma during the 3rd and 4th weeks and local degradation of glycosaminoglycans and proteins takes place. In contrast, after SCL (H) a remarkable thinning of the corneas was observed during extended wear, accompanied by decreased stainability of stromal glycosaminoglycans and highly decreased enzyme activities in keratocytes. The histochemical methods proved very useful in the assessment of tesions caused by a continuous wear of SCL.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Czechoslovak journal of physics 39 (1989), S. 1263-1266 
    ISSN: 1572-9486
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The7Be(n, p)7Li nuclear reaction with thermal and 2 keV neutrons was studied. For thermal neutrons the total cross section of (46 800± 4 000) b was obtained and the proton branching ratio to the first excited and ground states of7Li was determined to beσ 1/σ0 = (2±1) %. For 2 keV neutrons the upper limit of the cross section of 540 b was estimated.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 141 (1986), S. 131-139 
    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: Durch eine mit Diisopropoxycarbonylperoxid initiierte radikalische Lösungspolymerisation wurden Copolymere von Methyl-2,3,3-trifluoracrylat mit Isobutylen, Propylen, Ethylen und n-Alkylvinylethern (wobei Alkyl Ethyl, Propyl oder Butyl bedeutete) hergestellt. Die Struktur der Copolymeren entspricht einer alternierenden Zusammensetzung der Methyltrifluoracrylat- und Comonomer-Einheiten. Die Polymerisationsgeschwindigkeit und die Molekulargewichte sind durch das Verhältnis der beiden Monomeren und durch die Art des Vinylmonomeren bedingt. Die alkalische Hydrolyse der Trifluoracrylateinheiten liefert Copolymere der Trifluoracrylsäure. Der Dissoziierungsgrad der Copolymeren wird durch den pK-Wert charakterisiert. Die Hydrolysegeschwindigkeit ist stark von der Struktur des Copolymeren abhängig. Die Polymeren sind gut beständig gegen höhere Temperaturen, und eine thermische Zersetzung erfolgt erst bei über 300°C.
    Notes: Copolymers of methyl-2,3,3-trifluoroacrylate with isobutylene, propylene, ethylene, and n-alkyl vinyl ethers, (the alkyl being ethyl, propyl, butyl) glycidyl vinyl ether, and 2-methoxyethylvinyl ether were prepared by radical solution polymerization using di(isopropoxycarbonyl) peroxide as the initiator. Their structure was that of the alternating order of methyltrifluoroacrylate and the respective vinyl monomer units. The rate of copolymerization and molecular weights of the copolymers were determined by the ratio of both monomers and by the character of the vinyl comonomer. By means of the alkaline hydrolysis of trifluoroacrylate units, the corresponding copolymers of trifluoroacrylic acid were prepared. Their degree of dissociation was characterized by pK values. The rate of alkaline hydrolysis was considerably affected by the copolymer structure. The polymeric materials prepared in this study possessed good thermal stability, and their thermal decomposition did not occur below 300°C.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 132 (1985), S. 187-195 
    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: Es wurden Dialysemembranen durch Gießen von Celluloseacetatlösung in ein Lösungsmittelgemisch von Aceton/Dimethylformamid (1 : 1) und durch teilweises Abdampfen des Lösungsmittels von der gegossenen Lösung bei Raumtemperatur und durch Koagulieren in Eiswasser hergestellt. Der Einfluß der Polymerkonzentration in der Lösung und der Abdampfdauer des Lösungsmittels auf die Zugfestigkeit, Morphologie und Permeabilität der Membranen wurde untersucht. Membranen mit den besten mechanischen Eigenschaften wurden aus Lösungen von 20-28 Gew.-% Celluloseacetat bei Abdampfzeiten über drei Minuten gebildet. Diese Membranen enthielten ein Minimum an Hohlräumen in ihren unteren Schichten. Die Permeabilität der Membranen für niedermolekulare Stoffe steigt mit sinkender Polymerkonzentration in den Lösungen und mit Verlängerung der Abdampfdauer des Lösungsmittels bis zu ungefähr 2 Minuten an.
    Notes: Dialysis membranes were prepared by casting a solution of cellulose acetate in a mixed solvent acetone/dimethylformamide (1:1) followed by partial evaporation of the solvent from the cast solution at room temperature and by coagulation in icewater. The effect of the polymer concentration in solution and evaporation time of the solvent on tensile strength, morphology, and permeability of the membranes was investigated. Membranes possessing the best mechanical properties are formed from solutions containing 20-28 wt.-% cellulose acetate and at evaporation times longer than three minutes. The membranes contain the minimal amount of cavities in their lower layer. The permeability of the membranes for low molar mass compounds increases with decreasing polymer concentration in the casting solution and with extension of the evaporation time of the solvent up to ca. 2 min.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Acta Polymerica 38 (1987), S. 196-199 
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Transporteigenschaften partiell hydrophiler Ionenaustauschermembranen für Wasser und hydroxylgruppenhaltige Nichtelektrolyte wurden bestimmt. Durch Einführung fraktioneller Diffusionskoeffizienten im „freien“ und „strukturierten“ Wasser in der Matrix können die Ergebnisse interpretiert werden. Mathematische Beziehungen zwischen dem Volumenanteil des Wassers und dem Diffusionskoeffizienten sowie eine Gleichung für den Anteil des „freien“ Wassers wurden abgeleitet.
    Notes: Transport properties of partial hydrophilic ion-exchange membranes have been determined for water and hydroxyl group containing non-electrolytes. Interpretation of the results is possible by introduction of fractional diffusion coefficients in “free” and “structural” water of the matrix. Mathematical relations between volume fraction of water and diffusion coefficients as well as an expression for the fraction of “free” water are derived.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 27 (1985), S. 1382-1384 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 751-762 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The present study deals with the application and possibilities of insoluble hydrophilic gels (poly(2-hydroxyethyl methacrylate)) as substitutes of bone tissue experimentally. Their biocompatibility is examined with regard to the porous qualities of the implant and to its chemical structure, and their behavior in the cancellous and compact bone is evaluated. It was found that the modifications of hydrogels used in the experiment are biocompatible, with the compatibility increasing in proportion to increasing porosity. The nonporous and microporous hydrogels are not compatible and are demarcated. The sintered macroporous gel is surrounded by a thin fibrin membrane. By adding methacrylic acid to the hydrogel surface, adhesion increases markedly. Marked destruction also appears in the polymer especially in the cancellous bone. By an active destruction of the polymer, no direct phagocytosis can be proved. Upon breakdown of the implant in the compact bone the activity of the macrophages is delayed. When the gel without methacrylic acid is used alone, destruction does not occur even after 193 days. When methacrylic acid is added to the polymer surface, destruction does occur and the implant is filled only by bone trabeculae.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    Publication Date: 1988-01-01
    Print ISSN: 0018-2222
    Electronic ISSN: 1432-119X
    Topics: Biology , Medicine
    Published by Springer
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    Publication Date: 1985-02-01
    Print ISSN: 0021-9673
    Electronic ISSN: 1873-3778
    Topics: Chemistry and Pharmacology
    Published by Elsevier
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    Publication Date: 1985-02-01
    Print ISSN: 0021-9673
    Electronic ISSN: 1873-3778
    Topics: Chemistry and Pharmacology
    Published by Elsevier
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...