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  • Chemistry  (30,383)
  • General Chemistry  (3,323)
  • Life and Medical Sciences  (3,064)
  • Wiley-Blackwell  (33,447)
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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 214 (1994), S. 211-216 
    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: Über die Anwendung von Vinylesterharzen aus dem Diglycidylether von Bisphenol A sowie dessen Urethanderivat als Beschichtungsmaterial wird berichtet. Die mit den Harzen beschichteten Flußstahlplatten wurden auf Oberflächenglanz, Kratzfestigkeit und Chemikalienbeständigkeit untersucht. Harze mit Styrolanteil zeigen deutlich verbesserte Beschichtungseigenschaften.
    Notes: The present paper is concerned with the coating applications of a vinyl ester resin derived from diglycidyl ether of bisphenol-A and its urethane derivative. The mild steel panels coated with the synthesized resins were evaluated for their gloss on the surface, scratch hardness and chemical resistance. The incorporation of styrene in the resin systems improves the properties of coatings remarkably.
    Additional Material: 2 Tab.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 45 (1992), S. 1983-1994 
    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: Wholly aromatic polyamides, including poly(1,4-phenyleneisophthalamide) and poly(1,4-phenyleneterephthalamide) are N-methylated to render them soluble in N,N-dimethylformamide, a common size-exclusion chromatography eluent. The procedure N-methylates 50-55% of the total amide linkages in these two examples, permitting reproducible measurement of their absolute molecular weight distributions using differential viscometry detection. There is no observable degradation in molecular weight resulting from the N-methylation, provided the excess methylating reagent is destroyed shortly after completion of the derivatization by quenching with potassium acetate. The validity of the molecular weight data obtained by the method is confirmed by light-scattering measurements on derivatized polymer and by comparison to the molecular weight of underivatized polymer that can be approximated from the intrinsic viscosity in concentrated sulfuric acid. The method is applicable to a variety of wholly aromatic polyamide structures. Examples are given.
    Additional Material: 9 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 4 (1983), S. 371-381 
    ISSN: 0197-8462
    Keywords: 2,450 MHz ; microwaves ; natural killer cells ; macrophages ; mice ; lymphocytes ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: The effect of 2,450-MHz CW microwaves on natural killer (NK) cell activity and lymphocyte responsiveness to mitogen stimulation was studied in mice. Groups of mice were irradiated at power densities of 5, 15, or 30 mW/cm2 (SAR = 3.5, 10.5, and 21 W/kg respectively) for 1.5 h on 2 or 9 consecutive days. NK cell activity was determined using an in vitro 51Cr release cytotoxicity assay and an in vivo tumor-cell clearance assay. No consistent change was observed in the mitogen response of spleen cells from sham compared with irradiated mice. A significant suppression of NK cell activity measured in vitro was observed for mice irradiated at 30 mW/cm2, but not at 15 or 5 mW/cm2. A significant suppression of NK cell activity, as determined using the in vivo tumor clearance assay, was also observed at 30 mW/cm2. NK cell activity, as determined using the in vitro assay, returned to normal within 24 h following the last irradiation. Treatment of mice with hydrocortisone caused suppression of NK cell activity measured in vitro and in vivo. Paradoxically, peritoneal macrophage phagocytosis was enhanced following irradiation at 30 mW/cm2, the power density at which NK activity was suppressed. The possible role that microwave heating plays in producing these effects is discussed.
    Additional Material: 2 Ill.
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  • 4
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The establishment of reliable values for concentrations of 16 priority pollutant polycyclic aromatic hydrocarbons (PAH) in a suite of marine sediment reference materials included an examination of the methods used to determine such compounds. Results from the five techniques used indicate large method biases. The biases arise from chemical interferences in methods which use non-selective measuring systems with separation techniques which do not first completely resolve the analytes; e.g., single-parameter optical detectors with high performance liquid chromatographic (HPLC) techniques or a flame ionisation detector (FID) with capillary column gas chromatographic (GC) methods. Measurement by a mass spectrometer with HPLC and GC removes much of the method bias. Results for a representative sediment are discussed to illustrate these conclusions.
    Additional Material: 3 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 33 (1989), S. 578-583 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Methods of measuring oxygen solubility in culture media are scarce, and those available are tedious to apply. A simple colorimetric assay was developed and applied to the analysis of oxygen solubility during alcoholic fermentation. The method was based on the consumption of oxygen by glucose oxidase activity and the production of the pink quinone of syringaldazine by coupled peroxidase activity. Color formation at 526 nm progressed through an optimum that was a linear function of the oxygen added to the assay. Sensitivity was maximized by operating at pH 7 and limiting the medium sample volume added. Each assay took 10-15 min to prepare and react. Reaction time was minimized by using abundant glucose and enzyme concentrations. Data obtained by the assay developed showed good agreement with published oxygen solubilities in water and selected media at various temperatures. Subsequent analyses of fermentation broths indicated falling sugar concentration to be primarily responsible for increases in oxygen solubility during fermentation. For example, during fermentations started with 230 g/L xylose or glucose, oxygen solubility could increase by 41% due to sugar consumption alone. This procedure can provide the solubility data needed to accurately calibrate in-line electronic probes for monitoring dissolved oxygen concentration during fermentation processes.
    Additional Material: 5 Ill.
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  • 6
    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: X-ray diffraction, CP/MAS C-13 NMR, DSC, FTIR and fluorescence microscopy have been used to study the structure, compatibility, and morphology of films made from starch, poly(ethylene-co-acrylic acid) (EAA), and polyethylene (PE) before and after exposure to a mixture of highly amylolytic bacteria. The components of starch, amylose and amylopectin, interact with EAA via the formation of V-type inclusion complexes and hydrogen bonds. PE appears to be immiscible with the starch-EAA complex, with each forming sheetlike domains. The amylopectin in the films is susceptible to digestion by the bacterial consortium while the crystalline EAA-amylose complex is resistant. Digestion begins at the film surface and then proceeds inwards with sheetlike areas of starch removed. The good compatibility between starch and EAA as well as migration of EAA to the film surface explains the resistance of such films to digestion by conventional amylases.
    Additional Material: 6 Ill.
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  • 7
    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: Schiff bases of hydroxy benzaldehydes with aliphatic and aromatic 1,2-diamines were re-sinified in HCHO in alkaline media. These resins were found to form complexes readily with Cu(II), Co(II), and Ni(II). The materials were characterized by infrared, 1H-NMR, UV-visible (UV-vis) spectral studies, and thermogravimetric analyses. The phenolic oxygen and the azomethene nitrogen were the ligating sites, one or more lattice positions in polychelates being occupied by water molecules. 1H-NMR provided evidence for bridging methylene and terminal methylol groups. The UV-vis spectra showed weak absorptions in the d - d transition range. Capacity studies of the resins indicated metal loading up to 70% at room temperature in an appropriate pH of the salt solutions. The effects of contact time, particle size of the sorbents, resin quantity, and pH on the adsorption characteristics were studied. In the pH range 3-8, the resins derived from the structurally rigid Schiff bases exhibited higher capacity for the metal ions than the resins derived from structurally flexible Schiff bases. Kinetic parameters computed from the thermogravimetric data indicated the resins to be more stable than the corresponding polychelates. © 1996 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
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  • 8
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A benzenesulphonic acid-type cation exchanger (pKa 〈 1) is used as trapping-column material in a phase-system switching for the on-line coupling of column liquid chromatography and thermospray mass spectrometry. Phase-system switching is used to remove non-volatile constituents from the mobile phase, so that eluents containing non-volatile buffers and ion-pairing agents can be used without contaminating the mass spectrometer. The total analytical system is optimized using four benzalkonium test compounds (quaternary ammonium compounds). The reversed-phase separation of the test compounds as well as the parameters involved in the sorption on and desorption from the trapping column are studied. Important parameters during sorption are the concentration of the phosphate buffer and the percentage of acetonitrile in the mobile phase. During desorption of the test compounds from the ion-exchanger the percentage of acetonitrile in the desorption eluent and the pH are the most important factors. As an example, the analysis of domiphen in nasal drops is shown.
    Additional Material: 10 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 25 (1980), S. 1391-1405 
    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: An atmospheric-pressure, vapor-phase polymerization technique was used to deposit thin(1-10 μm) poly(p-phenyleneterephthalamide) coatings onto polyester film and other sheet substrates. A minimum deposition temperature of 170°C, was found to be critical. When substrate temperatures were below 170°C, coatings were loosely adhered, powdery, and of low molecular weight; above 170°C, coherent, well-adhered, high molecular weight coatings were obtained. These vapor-deposited coatings exhibited exceptionally good oxygen barrier properties and were found to consist of fused 0.1-μm particulates. Scanning electron microscopy (SEM) of the top surfaces of these coatings clearly revealed their particulate origin. Similar evidence was also obtained from SEM examination of fracture surfaces and transmission electron microscopy of microtomed sections. The coalescence of these coatings was demonstrated by SEM of plasma-etched surfaces and oxygen permeability information. The uniplanar orientation of the polymer crystals in these multiparticulate coatings was strong evidence for the epitaxial growth of the crystals.
    Additional Material: 11 Ill.
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  • 10
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Complexes of the type [crown+M]+ were observed following laser desorption ionization of 18-crown-6 molecules ‘doped’ with K+, Cs+, and Ba+. Laser desorption ionization of 15-crown-5 and 12-crown-4 ‘doped’ with the same metals gave [(crown)]2+[M]+ type sandwich complexes. Binding energies of crown ethers with different metal ions in all such complexes have been estimated from appearance energies obtained in the collisionally-activated dissociation of the corresponding laster desorbed complexes.
    Additional Material: 1 Tab.
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