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  • Polymer and Materials Science  (10)
  • 1
    Electronic Resource
    Electronic Resource
    Photopolymerization of cyclohexene oxide by use of o-nitrobenzyl triphenylsilyl ether/aluminum compound catalyst. Dependence of catalyst activity on the structure of the silyl ether (1987)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 753-763 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: o-Nitrobenzyl triphenylsilyl ehther/aluminum compound has been previously shown by the authors to act as catalyst in the photopolymerization of epoxides. The dependence of the structure of the silyl ether on the catalyst activity was examined. There were two steps in the photopolymerization. The first step (“Step 1”) is photodecomposition of the silyl ether to silanol. The second step (“Step 2”) is the initiation of polymerization by silanol and the aluminum compound. The introduction of an electron withdrawing group, Cl, CF3, on the benzene ring bonded to Si made the quantum yield of Step 1 low, however, the rate of Step 2 was increased. The low quantum yield of Step 1 was explained in terms of the rate of electron transfer that is controlled by the relative electron density between the CH2 and NO2 in the o-nitrobenzyl group. The acceleration of Step 2 was explained in terms of an increase in silanol acidity that was promoted by the introduction of an electron withdrawing group. The overall rate of the photopolymerizatiol depends to a greater degree on the rate of Step 2 than on that of Step 1.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1987.080250302
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  • 2
    Electronic Resource
    Electronic Resource
    Biocoulometry of cholesterol using porous carbon felt electrodes (1991)
    Weinheim : Wiley-Blackwell
    Electroanalysis 3 (1991), S. 59-62 
    Details
    ISSN: 1040-0397
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Free and total cholesterols in human serum have been determined by controlled-potential coulometry with porous carbon felt electrodes. In such a coulometric cell, a small amount of sample solution was dropped on the carbon felt dipped into electrolyte containing enzymes and a mediator. Hydrogen peroxide is produced by the enzymatic reaction of cholesterol catalyzed by cholesterol oxidase, and the complete electroreduction of hexacyanoferrate(III) ions [produced by the reaction of hexacynoferrate(II) ions and hydrogen peroxide catalyzed by peroxidase] was carried out under controlled-potential conditions. In the case of determining total cholesterol in human serum, cholesterol esters were converted to free cholesterol by cholesterol esterase reaction prior to the addition of the sample solution into electrolyte. The conversion ratios of free cholesterol to hydrogen peroxide were found to be 85-89% (RSD 〈 6%). The electrolysis time of one sample was less than 5 minutes. Immobilization of cholesterol oxidase to the carbon felt surface was attempted; the activity of cholesterol oxidase, Immobilized by the diazo-coupling method began to decrease 3 days after the immobilization.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140030111
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  • 3
    Electronic Resource
    Electronic Resource
    Rapid coulometry with a porous carbon felt electrode using iodide or ferrocyanide ion mediators (1989)
    Weinheim : Wiley-Blackwell
    Electroanalysis 1 (1989), S. 323-326 
    Details
    ISSN: 1040-0397
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The oxidizing agents of iodide and ferrocyanide ions, such as 1,4-benzoquinone and the iodate ion have been determined by rapid (9-25 seconds) coulometry. The electrolytic solution is confined to the pores of the carbon felt electrode and the sample is added to the carbon felt surface, which is maintained at a fixed potential. Current efficiencies approached 100% for sample concentrations ranging from 1 × 10-5 to 1 × 10-1 M with relative standard deviation of 0.6-2.2%. The determination of residual chlorine in drinking water has been carried out using the same coulometric cell, and the results obtained by the present method are in good agreement with those obtained by the orthotolidine method.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140010407
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  • 4
    Electronic Resource
    Electronic Resource
    Measurement of peroxide in oils by controlled-potential coulometry using a vapor-grown carbon fiber electrode (1990)
    Weinheim : Wiley-Blackwell
    Electroanalysis 2 (1990), S. 259-261 
    Details
    ISSN: 1040-0397
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A small amount of a linoleic acid sample solution was dropped on a carbon fiber paste containing a mixture of acetic acid and methanol (1:1) saturated with potassium iodide. The present method needs no titration, and the only pretreatment needed for the sample is the dissolution of linoleic acid with an acetic acid - chloroform mixture (3:2). The complete electrolysis time of iodine produced by the reaction of iodide ion and peroxides was found to be 2-3 minutes. The results obtained by coulometry were in fairly good agreement with those obtained by conventional iodometry.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140020315
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  • 5
    Electronic Resource
    Electronic Resource
    Electrocatalysis of nitrite reductase from Alcaligenes faecalis strain 6 mediated by native redox partner (1992)
    Weinheim : Wiley-Blackwell
    Electroanalysis 4 (1992), S. 771-776 
    Details
    ISSN: 1040-0397
    Keywords: Nitrite reductase ; blue protein ; electrocatalysis ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A protein-mediated electrocatalytic reaction is described. A blue protein from Alcaligenes faecalis strain 6 (AfBP) was used as a redox mediator for a nitrite reductase (NIR) from the same organism. Two steps of a homogeneous chemical reaction (AfBP-NIR and NIR-substrate), following the direct electron transfer reaction of AfBP (E C′C′), were analyzed, and the bimolecular rate constant of 1.8 × 106 M-1·S-1 for the AfBP-NIR reaction was calculated from electrocatalytic current in cyclic voltammetry. The kinetic relation of the first and the second homogeneous reaction was discussed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140040806
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  • 6
    Electronic Resource
    Electronic Resource
    Mediated micro-glucose sensors using 2 μm platinum electrodes (1992)
    Weinheim : Wiley-Blackwell
    Electroanalysis 4 (1992), S. 859-864 
    Details
    ISSN: 1040-0397
    Keywords: Bisensors ; Microelectrodes ; Mediate Glucose ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Glucose-oxidase (GOD) and glucose-dehydrogenase (GDH) immobilized cylindrical microelectrodes were fabricated, and their characteristics were evaluated by using 1,4-benzoquinone and ferricyanide as electron mediators, respectively. Each enzyme was immobilized in a photocrosslinkable polymer on a cylindrical microelectrode of 2 μm diameter. A linear range in the calibration plot of the GOD-based micro-glucose sensor was observed to be wider than that obtained using a disk electrode of 1 mm diameter. The mediated response of the 2 μm glucose sensor was compared with the response resulting from hydrogen peroxide detection. This result showed that a higher response and a wider linear range were observed at a highly concentrated mediator. For the GDH-immobilized 2 μm microelectrode, a much higher response was obtained when not only ferricyanide but also diaphorase were employed to reoxidize NADH produced by the enzyme reaction of GDH. The GDH-based micro-glucose sensor was found to be unaffected by dissolved oxygen concentration.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140040906
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  • 7
    Electronic Resource
    Electronic Resource
    Amplified vitamin C sensor based on the cyclic reaction between L - ascorbic acid and dehydroascorbic acid (1993)
    Weinheim : Wiley-Blackwell
    Electroanalysis 5 (1993), S. 653-655 
    Details
    ISSN: 1040-0397
    Keywords: Ascorbic Acid ; Amplification ; Biosensor ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The current response of L-ascorbic acid at an ascorbate-oxidase membrane electrode (detecting the decrease of oxygen) has been amplified by adding dithiothreithol into the sample solution. The signal amplification is based on the cyclic reaction between L-ascorbic acid and dehydroascorbic acid, which leads to the regeneration of L-ascorbic acid. The amplification factor was increased up to 22.5 (at pH 7.5) when 5 × 10-3 M dithiothreithol solution was used. This amplification system enables the determination of not only L-ascorbic acid but dehydroascorbic acid, and the detection limit for vitamin C was found to be 2 × 10-7 M.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140050805
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  • 8
    Electronic Resource
    Electronic Resource
    Rapid coulometry of tocopherols in ethanol and chloroform using ferricyanide ion mediator (1994)
    Weinheim : Wiley-Blackwell
    Electroanalysis 6 (1994), S. 63-66 
    Details
    ISSN: 1040-0397
    Keywords: Coulometry ; Tocopherols ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In order to estimate the absolute determination method of tocopherols, rapid coulometry has been carried out by using a vapor grown carbon fiber electrode impregnated with ethanol-water solution containing ferricyanide ion as a mediator. The electrolysis time of 1 × l0-3 M α-tocopherol in ethanol was below 30 seconds, and its current efficiency was attained to be 100.1% when an ethanol content in pH 4.0 electrolyte is 20%. Four isomers of vitamin E in chloroform were also determined by indirect coulometry in which ferricyanide solution was mixed with sample solution for 10 minutes prior to electrolysis and the current efficiencies of α-, β-, γ-, and δ-tocopherols were obtained to be 97.6, 100.5, 89.7, and 83.7%, respectively, and the relative standard deviations were below 1%.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140060112
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  • 9
    Electronic Resource
    Electronic Resource
    Concentration-step amperometric sensor for uric acid using uricase (1990)
    Weinheim : Wiley-Blackwell
    Electroanalysis 2 (1990), S. 559-562 
    Details
    ISSN: 1040-0397
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A novel amperometric method for biochemical substrates consuming oxygen in their enzyme reactions is proposed. This method is based on the measurement of the current peak observed when the sample solution is dropped on the thin membrane dipped in the enzyme solution, which is placed on the oxygen gas-selective permeable membrane. In order to illustrate the present concept, uric acid was chosen as a measurable species and the response characteristics of the sensor were investigated. The peak current obtained by sample addition was proportional to the concentration of uric acid in the dropped solution, and the method was applied to measure uric acid in human urine. The results obtained were in fairly good agreement with those obtained using a conventional spectrophotometric method.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140020710
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  • 10
    Electronic Resource
    Electronic Resource
    Polymerization of cyclohexene oxide with aluminum complex/silanol catalyst. VI. Oligomer and polymer effects (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 21 (1983), S. 467-477 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The activity of an aluminum complex/polysilanol polymerization catalyst was examined in order to confirm the dependence of catalytic activation on silanol chain length. Tris (acetylacetonato)-aluminum/silanol increased when silanols with an intramolecular hydrogen bond such as the trimer of diphenylsilanediol, polydiphenyl(4-vinylphenyl)silanol, and polymeric silanol of silicone were used. However, when tris(ethylacetoacetato)aluminum or tris(salicylaldehydato)aluminum was used, the product obtained from the reaction of a part of the aluminum complex with the polysilanols had to be considered in any explanation of the catalytic activation. The active catalyst with such aluminum complexes was obtained when the silanols that had intramolecular hydrogen bonds and gave the appropriate ratio of the reaction between the aluminum complex and silanol were used.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1983.170210216
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