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  • Chemistry  (20,474)
  • Polymer and Materials Science  (7,697)
  • General Chemistry  (1,936)
  • Wiley-Blackwell  (21,527)
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  • 1
    ISSN: 0884-3996
    Keywords: Luminometer ; evaluation ; rapid microbiology ; ATP assay ; firefly luciferase ; photometer ; radiometer ; comparison ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: An assessment has been carried out of the relative performance of ten instruments for quantification of adenosine triphosphate (ATP) by the firefly luciferase assay. The instruments evaluated were Amersham Amerlite Analyser, Dynatech Tube Luminometer, Dynatech Multiplate Luminometer, Dynatech Camera Luminometer, Hamilton Lumicon, LKB 1250 Luminometer, LKB 1251 Luminometer, Lumac Biocounter M2010A, Turner 20 TD Luminometer and a prototype version of the CLEAR Speed Tech 2000. An 800-fold difference in sensitivity was found between the most sensitive (Lumac, Turner) and the least sensitive (Dynatech Tube) of the conventional instruments. The Dynatech Camera Luminometer which worked on a completely different principle to the other instruments was about 5000 times less sensitive than the best of the photomultiplier tube instruments. The relative sensitivity of the instruments was maintained regardless of whether solutions of ATP in water or trichloroacetic acid extracts of bacteria were analysed. An analysis of 960 ATP bioluminescence assays showed that data obtained from such measurements are normally distributed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 9 (1971), S. 193-208 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The results of an x-ray and polarimetric study of a crystalline modification (form I) of isotactic poly-(S)-4-methyl-1-hexene are reported and discussed. The x-ray fiber spectra of this polymer are practically indistinguishable from those of isotactic poly-(R)-(S)-4-methyl-1-hexene. Although the crystal structure of the latter can be described on the basis of helices of different screw sense packed in a P4 space group, the crystal structure of poly-(S)-4-methyl-1-hexene is better described on the basis of a P1 space group. The conclusion of the x-ray investigation, that in the crystals of the optically active polymer an equal number of right-handed and left-handed helices must be present, is supported by the polarimetric measurements, which have shown that the polymer in the crystalline form I possesses a rather low rotatory power.
    Additional Material: 5 Ill.
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  • 3
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The data obtained with 252Cf plasma desorption (PD) and fast atom bombardment mass spectrometry of eight tri-, tetra- and pentapeptides were compared. Good spectra were obtained with 1-10 nmol of peptide. In both techniques molecular weight information was obtained. The PD mass spectra are often dominated by the cationized molecular ions in contrast to the fast atom bombardment (FAB) mass spectra, where cationization is rarely observed. Amino acid content is reflected in the immonium ions equally well in both techniques. The fragmentation patterns observed with the two techniques are almost identical. However, practical sequencing of peptides based on either FAB or PD mass spectrometry of underivatized peptides alone is difficult. This is due to the unpredictable and sometimes absent cleavage yield at certain peptide bonds. Another difficulty is the many simultaneous fragmentation pathways. However, for many peptides enough information is present to allow sequence determination for at least a major part of the molecule.
    Additional Material: 2 Ill.
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  • 4
    ISSN: 0021-9304
    Keywords: biomaterials ; polyurethanes ; infection ; infection resistance ; surface modification ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Tissue reactions to implantable pacemaker leads were investigated in an early infection model in rabbits. Both standard leads and surface-modified leads were used. The surface modification technique was applied to achieve controlled release of the antibiotic gentamicin. The insulating polyurethane tubing material of the leads was provided with an acrylic acid/acrylamide copolymer surface graft and then loaded with gentamicin. Implantation periods varied from day 4, to week 3½, to week 10. We investigated tissue reactions in the absence of an infectious challenge and also the efficacy of surface-modified leads in preventing infection after challenge with Staphylococcus aureus was evaluated. It was demonstrated that the applied surface modification did not induce adverse effects although during early postimplantation an increase in infiltration of granulocytes and macrophages and wound fluid and fibrin deposition were observed. After bacterial challenge, standard leads were heavily infected at each explantation period, denoted by abscesses, cellular debris, and bacterial colonies. In contrast, little or no infection was observed, either macroscopically or by bacterial cultures, with the surface-modified leads. Microscopy showed little evidence of the bacterial challenge, and that primarily at day 4. It was concluded that the applied surface modification demonstrated enhanced infection resistance and thus represents a sound approach to the battle against infectious complications with biomaterials. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 41, 142-153, 1998.
    Additional Material: 12 Ill.
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  • 5
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: It was demonstrated that a total reflection x-ray fluorescence spectrometer, using monoenergetic synchrotron radiation as the primary x-ray source, is suitable to measure the concentration of transmutational elements in Cu and Fe metal matrices. In a typical irradiation of copper with 590 MeV protons or with spallation neutrons, where the damage dose is 0.4 dpa (displacement per atom), the calculated concentration of transmutational elements is Ni 25, Co 8 and Fe 8 μg g-1. The results show that the minimum detectable concentrations were lower than these values. The energy of the sychrotron radiation was set just below the K-edge energy of the matrix element, eliminating the large peak due to the matrix. As an example, in the case of a Cu (Z = 29) matrix, the minimum detectable concentration for Ni (Z = 28) was as low as 3 μg g-1. In order to check systematically the possible geometric arrangements of beam direction-reflector position-detector position, a new vacuum chamber was designed and tested. It provides all technical components for remote control of the adjustment procedure to align the reflector in total reflection geometry. Two ways of positioning the reflector in the beam, vertical to the plane of polarization and parallel to that plane, were investigated, to find the best excitation conditions and lowest limits of detection. A few pg corresponding to a concentration of ng g-1 of samples where the matrix can be easily removed as in aqueous or acidic solutions and 50 ng g-1 concentration of metals in a light matrix as in oil were found as detection limits.
    Additional Material: 3 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 1285-1300 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Raman and ir spectra of the glycyl-L-proline (GP) dipeptide were recorded. A normal-coordinate treatment was performed on the basis of the experimental spectra, using a modified Urey-Bradley force field (MUBFF). Cyclic redundancies were eliminated, and those due to the ring methylene groups, particularly distorted in regard to the tetrahedral conformation, were treated. An assignment of the experimental frequencies is proposed on the basis of the normal treatment.
    Additional Material: 5 Ill.
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  • 7
    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Phase separation by semi-interpenetrating polymeric network formation based on the copolymer styrene-divinylbenzene (PS-DVB) and poly(butyl methacrylate) (PBMA) was investigated by light scattering. The time for phase separation was measured as a function of the rate of the copolymerization reaction and of the composition of the initial blend. The time until the outset of phase separation decreases with increasing content of PBMA in the blend. The change in concentration of DVB does not influence the process of phase separation.
    Additional Material: 4 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 36 (1988), S. 1433-1441 
    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: Telechelic prepolymers of butadiene with aliphatic isocyanate end-groups were prepared by the solution polymerization of butadiene under free radical initiation. 4,4′-Azobis (4-cyanopentanoyl azide) was used as the initiator. Liquid prepolymers were obtained with molecular weights of 1450 to 6000 and functionalities 1.9 to 2.2. The prepolymers were characterized by their number-average molecular weight, isocyanate content, functionality, infrared, and nuclear magnetic resonance spectra and microstructure. The storage stability of the prepolymers was checked and they were found to be quite stable under ambient conditions. Isocyanate-terminated polybutadienes were reacted with N,N-dimethylamino ethanol and t-butyl hydroperoxide to obtain useful dimethylamino-terminated and peroxycarbamate-terminated prepolymers, respectively.
    Additional Material: 4 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 36 (1988), S. 837-858 
    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 extensive study on the turbulent drag reduction caused by the various mixtures of polyacrylamide, purified guargum, xanthangum, and their graft copolymers has been conducted at low concentrations and Re = 14,000 using a turbulent flow rheometer. It has been found in most of the cases that the drag reduction caused by mixtures shows a positive deviation from the linearly additive straight line. This effect is more prominent when the drag reduction caused by both the constituents differ appreciably. In most of the cases, the drag reduction caused by the mixtures is higher than the DR caused by either of the constituent polymers; however, the drag reduction caused by the mixture is less than the sum of the drag reduction caused by both the constituents at their respective concentration in the mixture. It has also been noticed that there is no evidence of synergism in these mixtures at low concentrations.
    Additional Material: 13 Ill.
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