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  • 1
    Electronic Resource
    Electronic Resource
    A novel hollow-fiber reactor with reversible immobilization of lactase (1988)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 34 (1988), S. 293-304 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Experimental and theoretical studies on a backflush hollow-fiber enzymatic reactor (HFER) were conducted in this work for a lactose/lactase system. An A. niger lactase was chosen, from the four lactases tested, for reversible immobilization in the sponge layers of the fibers. An enzyme loading procedure was developed that allowed reliable and reproducible operation of the hollow-fiber reactor and produced industrially significant conversions without apparent change in the activity or stability of the lactase used. This reversible immobilization scheme also permitted easy replacement of the enzyme used. The performance of the backflush HFER was investigated and a large number of data concerning its operation were obtained and interpreted. Momentum and mass transports in such a HFER were analyzed, and mathematical models that took the experimental findings into consideration were also developed and solved analytically and/or numerically. Predictions from the computer model developed in this work were found to be in excellent agreement with the experimental data collected, suggesting the possibility of a priori design of a process-scale backflush HFER. With minor modifications, the models developed are expected to be applicable to hollow-fiber reactors with a wide selection of immobilized cells, organelles, and other enzymes.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690340213
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  • 2
    Electronic Resource
    Electronic Resource
    Recombinant human secretory phospholipase A2: Purification and characterization of the enzyme for active site studies (1992)
    Chicester [u.a.] : Wiley-Blackwell
    Journal of Molecular Recognition 5 (1992), S. 145-153 
    Details
    ISSN: 0952-3499
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A secreted form of phospholipase A2 (PLA2) is thought to play an important role in inflammatory diseases. To characterize this enzyme the cDNA encoding a low molecular weight PLA2 was cloned from a human placental cDNA library. The cDNA encoding the human PLA2 was subcloned into an expression vector and subsequently transfected into Chinese hamster ovary (CHO) cells. A stable CHO cell clone, secreting ca I mg/L of recombinant PLA2 into the medium, was scaled up in culture to 180L. The recombinant enzyme was purified from the cell supernatant to apparent homogeneity by a novel procedure combining adsorption to poly(vinylidene difluoride) membranes, ion exchange chromatography and size exclusion chromatography. The final recovery of PLA2 activity was 58%. A direct comparison between the purified recombinant human PLA2 and PLA2 purified from human synovial fluid, including molecular weight, antigenicity, ionic dependence, substrate specificity and sensitivity to know PLA2 inhibitors, indicated that the two enzymes exhibit identical biochemical properties. These results show that the recombinant PLA2 can be efficiently expressed and purified in sufficient quantities to characterize the enzyme active site, to aid in the rational development of PLA2 inhibitors as potential anti-inflammatory drugs, and to investigate further the role of PLA2 in inflammatory disease.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmr.300050405
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  • 3
    Electronic Resource
    Electronic Resource
    Effect of low-power air plasma treatment on the mechanical properties of carbon fibres and the interfacial shear strength of carbon fibre - epoxy composites (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 23 (1995), S. 313-318 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A low-power plasma treatment has been adapted to work on a pilot plant scale to continuously treat a tow of carbon fibres. This treatment successfully increases fibre-resin adhesion to levels comparable if not higher than those obtained by commercial electrochemical treatments. One advantage is that the plasma treatment does not appear to affect the tensile properties of the fibre, unlike the electrochemical oxidation.We have also shown that the chemical groups introduced during air plasma treatment play a significant role in fibre-resin adhesion whereas those introduced by electrochemical oxidation do not. A possible explanation for this is that plasma treatments introduce chemical groups onto the immediate surface of the fibres that have the potential to react with the resin, whereas electrochemical oxidation occurs predominantly at the edge sites and proceeds into the sublayers of the fibre. The vast majority of the functional groups are therefore inaccessible to the resin. This type of plasma treatment, however, is unlikely to remove all of the weakly bound layers as in the case of electrochemical treatment because the sputtering capability of the plasma is very low.The fact that these conclusions can be drawn from both the single-fibre fragmentation test and the short-beam shear test is encouraging and goes to prove that both these tests are suitable for looking at trends in fibre-resin adhesion.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740230507
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of low-power plasma treatment on polyethylene surfaces (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 23 (1995), S. 319-327 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: This paper describes the effects that a low-power plasma (〈1 W) has on the chemistry, topography and surface energy of polyethylene (PE) film. The gases used for treating the film were air and nitrogen. The plasma cell was attached directly to the preparation chamber of an x-ray photoelectron spectrometer, enabling the immediate effects of the plasma on the chemical nature of the films to be monitored. Significant amounts of chemical functionality were introduced onto the surface using both plasmas even after a few seconds of treatment. Carbon/oxygen functionality dominates surfaces treated with an air plasma. Nitrogen plasma treatment, as expected, introduced amines, imines and amides. Exposing the treated surfaces to air results in oxygen adsorption, the amount of oxygen pick-up being time dependent. This ageing of the treated polymer films is thought to occur via two processes: short-term hydrolysis of the amines and gradual oxidation of the polymer chain itself.The topographical changes were studied using atomic force microscopy, which was performed after the films had been exposed to air. Both plasmas caused the polymer surface to roughen, with nitrogen plasma treatment having a more pronounced effect. The surface energy of the film was increased from 37 dyn cm-1 (untreated) to 47 and 46 dyn cm-1 after 20 s of exposure to air and nitrogen plasmas, respectively. After 1 min of treatment, the polar surface energy component of the film treated with a nitrogen plasma (12 dyn cm-1) was much higher than that treated with an air plasma (7 dyn cm-1). This is supported by the XPS results in that the concentration of chemical groups introduced onto the surface after nitrogen plasma treatment was greater than that for air.The greater changes in polymer surface properties observed for nitrogen plasma treatment were not reflected in the values obtained for the level of polymer/metal adhesion. Only air plasma-treated samples showed significant improvement in the adhesion between polyethylene and aluminium and we conclude that the presence of oxygen-containing functional groups plays a major role in this improvement.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740230508
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  • 5
    Electronic Resource
    Electronic Resource
    Ammonia Plasma Treatment of PTFE Under Known Plasma Conditions (1996)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 24 (1996), S. 821-829 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Ammonia plasmas produced in a helical resonator have been investigated using an energy-selective mass spectrometer and an r.f.-compensated Langmuir probe. The effect of processing parameters on the plasma composition and ion energy distributions have been examined. The dominant ion present in the plasma was found to be NH4+, which varied in concentration between 95% and 65%, dependent upon operating conditions. Similarly, by relatively small variations in processing parameters it was possible to vary the NH3+ ion concentration between 1.7 and 31%. In addition, no radicals (NH2•, NH• or N•) were detected using threshold ionization mass spectroscopy. Polytetrafluoroethylene (PTFE) samples were treated under a variety of different plasma conditions, and the chemical changes induced were studied by in situ XPS.Defluorination was observed to be greater under conditions that yield low ion energies or high concentrations of NH3+ ions. Conditions giving rise to significant concentrations of NH3+ ions result in the production of NH3+F- groups. Evidence is provided suggesting that NH3+ ions are much more reactive with PTFE surfaces than NH4+ ions.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Glycoconjugates: composition, structure, and function. Edited by Howard J. Allen & Edward C. Kisailus, Marcel Dekker, New York, 1992, vii + 685 pp., price: $195. ISBN 0 8247 8431 6 (1994)
    Chichester : Wiley-Blackwell
    Journal of Chemical Technology AND Biotechnology 59 (1994), S. 115-115 
    Details
    ISSN: 0268-2575
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jctb.280590131
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  • 7
    Electronic Resource
    Electronic Resource
    Novel poly(n-butyl methacrylate)/titanium oxide alloys produced by te sol-gel process for titanium alkoxides (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 40 (1990), S. 1401-1420 
    Details
    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: A method has been developed to cast novel organic/inorganic hybrid films from multicomponent solutions containing titanium alkoxides, poly(n-butyl methacrylate), water, and isopropanol of prescribed compositions. The sol-gel reactions and controlled drying procedure yielded materials of mechanical integrity for which the multistep thermal degradation profile of the organic polymer has been significantly modified. A crystallization exotherm, presumably due to anatase formation, is seen for tetraethyl titanate-derived films beyond the organic degradation temperature. The trend of mechanical tensile parameters with increasing Ti oxide content depicts progressive material strengthening. FT-IR as well as the thermal and mechanical studies of these films suggest a highly unconnected and heterogeneous Ti oxide phase.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1990.070400726
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  • 8
    Electronic Resource
    Electronic Resource
    Fast atom bombardment and collisional activation mass spectrometry of retinyl phosphate mannose synthesized by liver membranes (1985)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 12 (1985), S. 221-227 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Fast atom bombardment (FAB) and collisional activation dissociation (CAD) mass-analysed ion kinetic energy (MIKE) spectra have confirmed the structures of retinyl phosphate (Ret-P), retinyl phosphate mannose (Ret-P-Man) and guanosine 5′-diphospho-D-mannose (GDP-Man). Ret-P-Man was made in vitro while Ret-P and GDP-Man were chemically synthesized. Positive ion FAB mass spectrometry of Ret-P showed an observable short-lived spectrum with a mass ion at m/z 367 [M + H]+, and a major fragment ion at m/z 269 [M+H—H3PO4]+. Negative ion FAB mass spectrometry of Ret-P showed a strong stable spectrum with a parent ion at m/z 365 [M—H]-, a glycerol (G) adduct ion at m/z 457 [M—H+G]- and a dimer ion at m/z 731 [2M—H]-. GDP-Man showed an intense spectrum with parent ion at m/z 604 [M—H]- and cationized species at m/z 626 [M+Na-2H]- and 648 [M+2Na-3H]-. Negative ion FAB mass spectrometry of Ret-P-Man showed a parent ion at m/z 527 [M—H]- and a fragment ion at m/z 259 [C6H12PO9]-. The CAD-MIKE spectra showed structurally significant fragment ions at m/z 442 and 361 for the [M—H]- ion of GDP-Man, and at m/z 509, 406, 364 and 241 for the [M—H]- ion of Ret-P-Man. FAB and CAD-MIKE spectra have been applied successfully to confirm the structure of Ret-P-Man made in vitro from Ret-P and GDP-Man.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200120507
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  • 9
    Electronic Resource
    Electronic Resource
    Macro- and microsegregation of Zn in bridgman-grown CdZnTe (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 5 (1995), S. 101-108 
    Details
    ISSN: 1057-9257
    Keywords: CdZnTe ; Zn segregation ; Bridgman ; ACRT ; substrates ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: One of the remaining problems in the use of CdZnTe material as substrates in liquid phase epitaxy (LPE) of CdxHg1-xTe (CMT) layers is that of variation in lattice matching, i.e. Zn content, across substrates. This wil become increasingly important in the future as larger focal plane arrays of infrared detectors are required. The basic Bridgman growth process for CdTe/Cd0.96Zn0.04Te has been extended by applying the accelerated crucible rotation technique (ACRT). A marked reduction in axial Zn segregtion is seen in 50 mm diameter ACRT material, but this effect is smaller in the case of 75 mm diameter crystals. Radial variations in Zn content are small in both sizes of crystal, demonstrating the benefits obtained from ACRT stirring. Both macro- and microsegregation effects have been studied in these crystals in an attempt to understand the growth mechanism. Zinc distributions have been assessed by near-infrared transmission, X-ray lattice parameter measurements, atomic absorption spectrometry (AAS) and Auger electron spectrometry (AES). The last technique was used for the microsegregation studies, while AAS provides the absolute calibration for Zn content. Comparisons with segregation behaviour found in the literature will be given. It will be shown that the low temperature gradient and low growth rate lead to a degree of supercooling in the first-to-freeze region and this leads to significant Zn segregation in both radial and axial directions. As the crystals reach full diameter, the radial variation is decreased, presumably by the action of the ACRT, and axial segregation is also reduced.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/amo.860050206
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  • 10
    Electronic Resource
    Electronic Resource
    Photon correlation spectroscopy of hemoglobin: Diffusion of Oxy-HbA and Oxy-HbS (1978)
    New York : Wiley-Blackwell
    Biopolymers 17 (1978), S. 1581-1593 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Translation diffusion coefficients have been measured for oxyhemoglobin A and oxyhemoglobin S over the concentration range 0.1-37 g/dl by means of photon correlation spectroscopy. The solutions were 0.1 M in KCl and in each case the pH was adjusted to the isoelectric point of the hemoglobin species present. No significant differences were found between the HbA and HbS results; and after correction to water at 20°C, the diffusion coefficients could be described by the equation \documentclass{article}\pagestyle{empty}\begin{document}$$ D{\rm } = {\rm }D_0 \left[{1{\rm } - {\rm }\left({{\rm 0}{\rm .0067} \pm {\rm 0}{\rm .0007}} \right)c} \right] $$\end{document} where Do = (6.93 ± 0.06) × 10-7 cm2/sec and c ids the concentration in units of g/dl. No evidence was found for the aggregation of oxy-HbS at high concentrations which was reported by Lindstrom et. al. [(1976) Biophys. J. 16, 679-689].
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1978.360170615
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