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  • American Geophysical Union  (80)
  • Wiley-Blackwell  (52)
  • American Association for the Advancement of Science  (43)
  • 2015-2019  (47)
  • 1985-1989  (63)
  • 1980-1984  (37)
  • 1965-1969  (28)
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  • 1
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: When blood comes into contact with an artificial surface, a number of events occur which include protein adsorption, platelet activation and the activation of the intrinsic pathway of blood coagulation. With the increased application of blood containing artificial devices, there is a great demand to develop new biomaterials which retard thrombus formation. Our new approach to solving this problem is to mimic the non-thrombogenic surface of natural biological membranes at least in a simple form. We have developed a polymerisable phospholipid and polyesters based on the major phospholipid polar head group present on the erythrocyte outer membrane surface. The coagulation of blood exposed to these polymers was examined by the technique of Material Thrombelastography, a relatively simple test for the in vitro screening of polymer thrombogenicity. We present results which indicate that the polymerised phospholipid and polyesters show reduced thrombogenicity, and may therefore have potential for future biomaterials.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 313-323 
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Ethylurea was used to weaken hydrophobic interactions during collagen fibrillogenesis in vitro. Intact and enzyme-digested type I collagen was studied. In all preparations, ethylurea decreased the extent and rate of fibril formation, inhibition being greatest in the enzyme-digested collagens. With intact collagen (and probably also with carboxypeptidasedigested collagen), there was no evidence the ethylurea altered the mechanism of fibril growth; in pepsin-digested collagen, however, the growth mechanism was altered by ethylurea, possibly reflecting a conformational change of the “hydrophobic cluster” in the C-terminal peptide. Such a structural change could occur in a hydrophobic environment once the distal portion of the C-terminal peptide (presumed to be essential for its structural stability) is removed by pepsin. The results further emphasize the importance of hydrophobic interactions in collagen fibril nucleation and growth in vitro.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The metabolism of deutrated cortisol (9,12,12,-2H)cortisol, (2H3-F) was compared to that of radioactive cortisol (3H2-F) and natural cortisol, when these three compounds were administered simultaneously to an adrenalectomized piglet. The relative isotope dilution of tritium was determined from the specific activities of the main urinary neutral cortisol metabolites, tetrahydrocortisone (THE) and tetrahydrocortisol (THF), normalized to that of the cortisol mixture administered. To obtain a comparison of the isotope dilution of deuterium in the metabolites THE and THF to that in the cortisol mixture, the three steroids were converted to the common oxidation product 11-oxo-aetiocholanolone, and deivatized to the methoxime-tert-butyl-dimethylsilyl ether. The relative 2H-isotope dilution then was measured by gas chromatography/mass spectrometry. It was found that the specific activity of THE in the cumulative urine collections was similar to that of the cortisol mixture administered; the two-day value was, however, less. The specific activity of THF was slightly but significantly smaller than 1 (∼0.9) at all times. The relative 2H-isotope dilution in THE was slightly but significantly larger than one (∼1.1) at all times, whereas that in the THF was larger than 1.0 at 9 and 32 h or equal to 1.0 at 20 and 47 h of urine collection. When comparing the metabolism of the two tracer cortisol species the quotient of the 3H- and the 2H-isotope dilutions in THE and THF was smaller than 1.0. It can be concluded that (2H3)cortisol may be used for the determination of the cortisol production rate.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 27 (1989), S. 1993-2005 
    ISSN: 0887-624X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The hydrolysis of model structures found in the hard blocks of polyurethanes has been studied under moderately acidic and neutral conditions. These include a series of N-alkyl and N-phenyl urethanes and ureas; for comparison purposes the corresponding amides and a carbonate ester based on bisphenol A were also studied. Of all functional groups the urethane was the most resistant to hydrolysis and the amide the most labile. Also, the N-phenyl compounds were hydrolyzed faster than the corresponding alkyl derivatives. The carbonate ester underwent relatively rapid hydrolysis. Polyether containing polyurethanes, known to be relatively stable to hydrolysis, are discussed as to which polymer segments provide the weakest links under hydrolytic conditions.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 357-357 
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 6
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: An isotope dilution mass spectrometric method to determine the urinary cortisol production rate (CPR) in babies and children is described. The method uses stable isotopically labelled (1,2,3,4-13C)cortisol. The tracer is intravenously administered to the patient and urine is collected for the following three days. Following extraction, enzymic hydrolysis, purification and isolation by high-performance liquid chromatography (HPLC) the urinary cortisol metabolites tetrahydrocortisone, tetrahydrocortisol, α- and β-cortolone are separately oxidized to the common product, 11-oxo-aetiocholanolone. The methyl oxime tert-butyldimethylsilyl ether derivative (MO TBDMS) was analysed by gas chromatography mass spectrometry. Quantification of the isotope enrichment was carried out by selected ion monitoring of the base fragment ion at m/z 344[M-103]+ for unlabelled, and at m/z 348 for labelled 11-oxo-aetiocholanolone. HPLC isolation of the metabolites together with the oxidation step allowed very small isotope enrichments, sometimes down to 0.1% (1:1000), to be reliably measured against a linear calibration graph containing 0 to 1% (13C4) enrichments. The standards for the calibration graph were synthesized from mixtures of labelled (13C4) cortisol and natural cortisol, and the calibration graph was prepared each time samples were measured. The long term instrumental precision of the isotope dilution analyses was 0.91% for a derivatized sample containing a (13C4) enrichment of 0.5% (measured on six different days over seven months). The coefficient of variation of the complete procedure for the four cortisol metabolites was between 1.17 and 2.14%. The clinical applicability of the method is demonstrated by presenting the results of a CPR determination in a patient.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 22 (1980), S. 981-993 
    ISSN: 0006-3592
    Schlagwort(e): Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: In a recent publication, a technique was outlined for measuring surface aeration rates in an agitated vessels while sparging, and it was shown that surface aeration rates fall rapidly with increasing sparge rates. That work was conducted in a 0.61 m diam vessels. The work reported here was done in a small vessel (0.22 m diam) where surface aeration has been reported to be of particular significance. In general, the results obtained in the small vessel confirmed those in the large one and in addition were generally in good agreement with those recently published elsewhere for an almost identical geometry. For typical practical power inputs and sparge rates, the rate of surface aeration was never more than 20% of the sparge rate and generally less than 5%. These results indicate that surface aeration is of considerably less importance than has generally been believed following the findings of workers who estimated its effect by comparing KLa values under unsparged conditions with those when sparging.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 8
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 27 (1985), S. 355-361 
    ISSN: 0006-3592
    Schlagwort(e): Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Batch hydrolysis kinetics of paper birch (Betula papyrifera) xylan and its associated acetyl groups in dilute sulfuric acid have been measured for acid concentrations of between 0.04 and 0.18M and temperatures of between 100 and 170°C. Only 5% of the cellulose was hydrolyzed for up to 85% xylan removal. Rate data were correlated well by a parallel reaction model based on the existence of reactive and resistant xylan portions. The resulting rate equation predicts the experimental xylan concentrations in the residue to within 10%. Hydrolysis of xylan-associated acetyl groups was found to occur at the same rate as that of xylan, except at 100°C, where acetyl is released preferentially. No effect of acid concentration on the rate of acetyl removal relative to that of xylan was evident.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 9
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 30 (1987), S. 685-691 
    ISSN: 0006-3592
    Schlagwort(e): Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 10
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 9 (1967), S. 33-44 
    ISSN: 0006-3592
    Schlagwort(e): Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The bacterial degradation of catechol, 3-methylcatechol, 2,3-dihydroxy-β-phenylpropionic acid, and protocatechuic acid has been studied in detail. From the results obtained a general sequence has been proposed for the microbial oxidation of dihydroxy aromatic compounds.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
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