Library

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
  • Electronic Resource  (7)
  • Polymer and Materials Science  (4)
  • Cell & Developmental Biology  (3)
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 50 (1993), S. 1999-2006 
    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: Two types of aliphatic poly(ester-amides) (PEAs) were subjected to microbial degradation in basal mineral salt broth, under the attack of a yeast, Cryptococcus laurentii, at 20°C. PEA-I copolymers were made by the anionic ring-opening copolymerization of ∊-caprolactone and ∊-caprolactam, whereas PEA-II copolymers were synthesized by a two-step polycondensation reaction of hexanediol-1,6, hexanediamine-1,6, and adipolyl chloride. These copolymers were found to be readily degradable under biotic conditions, based on weight loss, GPC, NMR spectroscopy, and tensile property measurements. Compared to abiotic hydrolysis, biodegradation occurred much faster under milder conditions. Furthermore, NMR spectroscopic analysis proved that the biodegradation of poly(ester-amides) involves the enzymatic hydrolysis of ester groups on the backbones of polymers into acid and hydroxyl groups. No breakdown of amide bonds was observed under the given biotic conditions. © 1993 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 28 (1983), S. 327-334 
    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: Three high molecular weight polycaprolactones (M̄w = 35,000, 18,600, and 7,130) were utilized as the sole carbon source by five of six fungi tested by the American Standards for Testing and Materials (ASTM) agar plate method. The fungi were Aspergillus flavus, A. niger, A. fumigatus, Chaetomium globosum, Pencillium funiculosum, and a Fusarium sp. Quantitative analysis of degradation was performed using gel permeation chromatography (GPC). GPC analysis demonstrated differences between the activities of organisms which appeared similar by the ASTM method, and showed that, while all molecular weight species within each polymer were hydrolyzed, in several cases low molecular weight end products were not assimilated. Depending on the organism, the dominant factor determining degradability was either polymer molecular weight or degree of crystallinity.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 28 (1983), S. 335-342 
    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 degradability of three high molecular weight polycaprolactones (M̄w = 35,000, 18,600, and 7,130) and one low molecular weight polycaprolactone diol(M̄w = 2060) by mixed and pure cultures of microorganisms was assayed. A yeast, Cryptococcus laurentii, a gram-negative rod, Acinetobacter calcoaceticus var. lwoffi, and a gram-positive coryneform rod were used in the pure culture assays. The analysis of degradation by gel permation chromatography (GPC) allowed for quantitation independent of the growth of the organisms or the addition of supplementary growth factors. GPC analysis showed that the degradation effected by pure cultures was often enhanced when alternate carbon sources were present. This was not the case for mixed cultures. Mixed cultures. Mixed cultures completely metabolized polymer breakdown products while in some cases pure cultures did not.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Dehydroascorbate, an electron affinic metabolite of vitamin C, sensitized Ehrlich ascites tumor cells, in vivo, to radiation and was selectively toxic to V79 Chinese hamster lung cells under hypoxic conditions (without radiation). The radiosensitization may involve both the electron affinic nature of dehydroascorbate as well as its ability to oxidize the intracelluar NAD(P)H and non-protein sulfhydryl. Dehydroascorbate's oxidation of NAD(P)H required higher concentrations than other sulfhydryl oxidants such as N-ethylmaleimide and diamide. The oxidation of NAD(P)H by dehydroascorbate could be reversed by glucose. Hypoxic cell radiosensitization of V79 cells in tissue culture by dehydroascorbate could not be easily demonstrated because of the rapid breakdown and appreciable cytotoxicity of the drug at high concentration. The cytotoxicity was found to occur with both high and low densities of V79 cells. With low cell densities small amounts of oxygen did not reduce the cytotoxicity of dehydroascorbate, but virtually eliminated the cytotoxicity of nitroaromatic electron affinic compounds (metronidazole and Ro-07-0582). The cytotoxicity to dense cell suspensions was found to depend upon the type of buffer included in the reaction medium. The maximum cytotoxicity was obtained in buffer free saline. The reduced form of dehydroascorbate, vitamin C, was found to be toxic only under aerobic conditions. The aerobic cytotoxicity could be prevented by the addition of catalase to the growth medium or by an increase in cell density, suggesting it was caused entirely by the production of H2O2 from the oxidation of vitamin C.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The fine structure of the extracellular matrix during epithelio-mesenchymal interactions in the rabbit embryonic tooth germ is described using light and electron microscopy. Observations are restricted to the labial cervical loop region at the bell stage of development in maxillary and mandibular incisor tooth germs. Histochemical methods demonstrate a PAS-positive basement membrane between outer enamel epithelial cells and adjacent undifferentiated mesenchymal cells. The metachromatic region circumscribes the dental papilla region, becoming more intense and wider in association with cells illustrative of more advanced stages of differentiation. Ultrastructural observations of the basal lamina associated with outer enamel epithelial cells, cervical proliferating epithelial and mesenchymal cells, and with inner enamel epithelial cells and pre-odontoblasts are reported. The characteristic mesenchymal filopodia appeared in close proximity to the basal lamina. Microfibrils are seen as depositions on the basal lamina and in association with filopodia. The concentration of intercellular microfibrils is increased when in association with epithelia showing advanced differentiation. Collagen fibrils are frequently noted in peripheral association with mesenchymal cells but not adherent to the basal lamina. Numerous homotypic and heterotypic cell junctions are seen. An understanding of intercellular communication between heterotypic cells may be enhanced by postulating a dual developmental origin for the microfibrils associated with the basal lamina. The under surface of the basal lamina facing the extended mesenchymal filopodia appears to be a significant factor during epithelio-mesenchymal interactions, subsequent extracellular matrix formation, and morphogenesis.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Philadelphia : Wiley-Blackwell
    Journal of Cellular and Comparative Physiology 11 (1938), S. 433-454 
    ISSN: 0095-9898
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Letters Edition 19 (1981), S. 159-165 
    ISSN: 0360-6384
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...