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  • 1
    ISSN: 0887-3585
    Keywords: cellulases ; active sites ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Cellulomonas fimi produces an endoglucanase and an exoglucanase which bind strongly to cellulose. Each enzyme contains three distinct regions: a short sequence of about 20 amino acids containing only proline and threonine (the ProThr box); an irregular region, rich in hydroxyamino acids, of low charge density, and which is predicted to have little secondary structure; and an ordered region of higher charge density which contains a potential active site, and which is predicted to have secondary structure; and an ordered region of higher charge density which contains a potential active site, and which is predicted to have secondary structure. The Pro-Thr box is conserved almost perfectly in the two enzymes. The irregular regions are 50% conserved, and the conserved sequences include four Asn-Xaa-Ser/Thr sites. The ordered regions appear not to be conserved, but the potential active sites both have the sequence Glu-Xaa7-Asn-Xaa6-Thr; they occur at widely separated sites in the two regions. The order of the regions is reversed in the two enzymes: irregular-Pro-Thr box-ordered in the endoglucanase; ordered-Pro-Thr box irregular in the exoglucanase. The genes for the two enzymes appear to have arisen by shuffling of two conserved sequences and either one or two other sequences.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 111-125 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have prepared a number of high molecular weight, soluble, symmetrical dialkyl substituted germanium homopolymers and germanium-silicon copolymers. In solution, the absorption of the homopolymers was ∼ 20 nm red shifted from the crossponding silicon derivatives. This was somewhat unexpected based on theoretical predictions and has been rationalized on the basis of conformational arguments. In the solid state, samples of poly(di-n-hexylgermane) and poly(di-n-octylgermane) are strongly thermochromic. The effect is attributed to the conformational locking of the backbone which is caused by the crystallization of the side groups. In this regard, the germanium derivatives behave similarly to the corresponding silicon polymers, and the convergence of the long wavelength absorptions for both types of polymers is consistent with theoretical predictions. The germanium-silicon copolymers are also strongly thermochromic, but the long wavelength absorption is somewhat blue shifted (8 nm) from the respective homopolymers. As expected, the new germanium homo and copolymers are quite sensitive to light and readily undergo chain scission to produce lower molecular weight materials.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Letters Edition 25 (1987), S. 321-326 
    ISSN: 0887-6258
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 10 (1987), S. 497-503 
    ISSN: 0935-6304
    Keywords: Recycle gas chromatography ; Capillary columns ; Off-line flame Ionization detector ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preliminary results of a recycle system employing fused silica capillary columns are discussed. The unit, which can be operated with a pre-column for multidimensional GC, utilizes continuous stream splitting for off-line flame ionization detection. Commercially available rotary valves were used for recirculation of the chromatographic zone between column loops. Adsorptive activity, which is shown to be additive, is a serious limitation in the analysis of polar compounds. The successful application of recycle chromatography to increase resolution on non-polar mixtures is demonstrated.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 29 (1989), S. 882-886 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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 photochemistry of poly(cyclohexylmethylsilane) (PCHMS) has been studied, and PCHMS homopolymer has been shown to be useful for high resolution, deep UV pattern generation either by using a commercial 1:1 projection printer operating in the deep UV or by an excimer laser stepper at 248 nm. In the case of the excimer laser stepper, images 0.5 μm and smaller have been printed, which represents an improvement over the 0.8 μm limit previously reported for polysilane copolymers.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new method based on selected ion monitoring chemical ionization mass spectrometry was developed to measure the quaternary ammonium neuromuscular blocking agents, pancuronium and vecuronium, in serum. An ion-pair extraction procedure is utilized to separate the compounds of interest from biological fluids. The intensities of the ion currents produced by the bisamines formed from the drugs and the corresponding deuterated internal standards through thermolytic dequaternization are monitored. The assay shows good linearity over the range of 1-500 ng/ml. This assay has been utilized in a variety of clinical pharmacokinetic studies involving surgical pediatric, geriatric and obstetric patients requiring anesthesia.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 26 (1986), S. 1129-1134 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: All high molecular weight polysilane derivatives are characterized by a very strong electronic absorption in the-UV spectral region. The position of this absorption and the molar extinction coefficients are functions of both the nature of the substituent and the molecular weight. In this regard, both the λmax and the ∊si-si increase rapidly at first with increased catenation and approach limiting values al around 100 to 150 monomer units. Irradiation of these polysilane derivatives leads predominantly to chain scission and molecular weight reduction although the scission ing/crosslinking ratio is dependent on the nature of the substituents. The mechanism of the photodegradation involves both the extrusion of substituted silylene fragments and the formation of silyl radicals. Lithographically, we have exercised the polysilanes in two configurations: (1) O2-RlE etch resistant barriers in multilayer structures and, (2) thin imaginable layers for O2-RIE image transfer. In each case, the stability of the silicon polymers to O2-RIE conditions is due to the formation of a thin skin of oxide. In the case of the bilayer configurations, the images have been developed both by conventional wet development and by excimer laser ablation at either 308 or 248 nm prior to image transfer. Using either mode, we have been able to generate and transfer submicron images without difficulty. Finally, the strong optical absorption of the polysilanes, coupled with the observed bleaching upon irradiation, suggests potential as contrast enhancing materials. The contrast enhancement gained by the use of a polysilane layer has been modeled by computer simulation and demonstrated experimentally.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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