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  • 1
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 186 (1985), S. 1227-1237 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The exchange reaction between a polycarbonate and a polyarylcarboxylate, both based on bisphenol A, was simulated by studying the reaction between the polycarbonate and diphenyl terephthalate or isophthalate used as model compounds of a polyarylcarboxylate. The kinetic results indicate the presence of a transesterification reaction occurring without any catalyst. Some results from reactions in the melt between both polymers also point to an exchange reaction.
    Additional Material: 6 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1944-1954 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Thin-layer electrochemical reactors are analytical reactors where mass transfers are generally assumed not to affect the overall reaction rate. The validity of this hypothesis was tested for systems involving a second-order or an enzymatic homogeneous reaction that consumed the product generated by the electrochemical heterogeneous reaction. The experiments were performed with the oxidation of hexacyanoferrate II into hexacyanoferrate III, coupled with the consumption of hexacyanoferrate III by the reduced form of nicotinamide adenine dinucleotide, catalyzed or not by a diaphorase. The tools commonly used for gas - liquid interfaces were adapted to the description of mass transfer in a closed thin film. The theoretical model agreed well with the experimental data and served as the basis for testing the thin-layer hypothesis. The validity of the hypothesis was plotted as a function of the Hatta and Damköhler numbers. The influence of concentration and diffusion parameters are discussed with focus on the validity criterion.
    Additional Material: 8 Ill.
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  • 3
    ISSN: 0886-9383
    Keywords: NIR ; Fast Fourier transform ; Principal component analysis ; Discrimination ; Baking quality ; Wheat ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Digitalized continuous near infra-red reflectance (NIR) spectra are composed of a great number of data which must be reduced for microcomputer mathematical treatment. The sequence ‘fast Fourier transform preceding principal component analysis’ was tested to perform data size reduction without a large loss of information. The method was applied on a collection of wheat spectra composed of 351 data. Ten resulting data, which described 99.5% of the total variance, were kept. The relevance of the method was estimated by the ability of the resulting data (i) to regenerate the original signal, and (ii) to discriminate the baking quality of the wheat by stepwise multiple discriminant analysis. The average difference between initial and regenerated spectra was -2.4 × 10-3 log (1/R) units and the standard deviation was 1.16 × 10-3 log (1/R) units. The discrimination treatments gave 89.9% of well classified samples for the calibration test and 90.5% for the prediction test. The application of these mathematical treatments to other continuous signals is discussed.
    Additional Material: 2 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 163-175 
    ISSN: 0886-9383
    Keywords: Multiple-correspondence analysis ; Starch granule description ; Image analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Raw starch is composed botanically of characteristic granules of various sizes and shapes, so that each kind of starch may be characterized by the population of its granules. In the present study ten commercial starch species were studied: wheat, rice, manioc, potato, arrowroot, amylomaize, normal maize, waxy maize and two different banana species. Six variables measuring the size and shape of granules were obtained by image analysis. The objective was to find a method to describe and compare the granule populations of the ten species. For such a study, multiple-correspondence analysis (MCA) was applied. MCA makes it possible to draw similarity maps of categories and objects. For each starch species the frequency distributions (histograms) of the six variables were assessed and each granule was characterized by its species and the classes of histograms to which it belonged. MCA was applied to the granule table and a description of the histogram classes and the granules was obtained. From the variables description a general typology of the granules was deduced. The similarity maps showed considerable scatter of the granules for all species except rice. A particular species could therefore not be identified by a single granule, but the granule distribution seemed to be characteristic. MCA was an appropriate method to analyse these data because it points out non-linear relationships between quantitative and qualitative variables.
    Additional Material: 7 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 9 (1995), S. 125-135 
    ISSN: 0886-9383
    Keywords: Procrustean analysis ; FT-IR spectroscopy ; NIR spectroscopy ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Procrustean methods allow the fitting of a given matrix to another given matrix observed on the same objects. In the traditional approach orthogonal constraints are imposed upon the transformation matrix, whereas in the alternative approach Procrustean analysis may be performed without such constraints. The two methods (with and without constraints) were compared on data dealing with mid- and near-infrared spectra of oil. The aim was to reconstruct the mid-infrared spectral information using data from the near-infrared spectra. Unconstrained Procrustean analysis proved to be the more efficient for both the calibration and verification sets. Furthermore, the analysis of the transformation matrix between the two infrared ranges made it possible to indicate wavelengths and wave numbers corresponding to the same chemical groups.
    Additional Material: 7 Ill.
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  • 6
    ISSN: 0886-9383
    Keywords: NIR reflectance ; Multivariate analysis ; Principal component analysis ; Stepwise multiple linear regression ; Silage quality ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Calibrations to predict crude protein (CP) and in vitro dry matter digestibility (IVDMD) in dried grass silage from reflectance data collected at 19 wavelengths on an InfraAlyzer 400R have been developed using stepwise multiple linear (SML) and principal component (PC) regression techniques. A direct comparison of the efficacy of each multivariate technique in this applications has been possible by using identical calibration development and evaluation sample sets. The effect of two data transformation steps prior to PC regression was also investigated. PC regression of raw reflectance data yielded no significant improvement in the standard errors of prediction (SEP) for CP and IVDMD over those obtained by SMLR, viz. 0·61 vs 0·63 and 2·9 vs 3·0 respectively. Computation time for development and evaluation of the PC regression equation was less than for selection of the best SMLR equation, and PCR equations may be more robust. Data transformation to reduce granularity effects prior to PCR did not produce any improvement in predictive accuracy for either IVDMD or CP.
    Additional Material: 5 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 19 (1991), S. 269-274 
    ISSN: 0886-1544
    Keywords: minor and major waves ; beat frequeney ; wave propagation velocity ; coiling diameter ; storage effect ; differential behaviour ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: All species of the Drosophila obscura group exhibit within-ejaculate sperm length dimorphism. The present work is a contribution to the understanding of sperm competition through a comparative study of sperm kinetic parameters in four of these species. Videomicrographic observations at 200 frames per second of sperm from males and females, out of the storage organ, prior or after storage were made. Drosophila sperm display both major and minor waves. The former is analysed by measuring coiling diameter (μm) and the latter by recording both beat frequency (s-1) and wave propagation velocity (μm·s-1). Results show that the ‘behaviour’ of short and long spermatozoa noticeably differ: short sperm kinetics remains unaltered after storage while both major and minor waves of long spermatozoa are markedly modified. Thus, evidence is provided here of a sort of “differential activation” which is assumed to result in different survival abilities of short and long sperm within the storage organ of females.
    Additional Material: 2 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 5 (1991), S. 299-302 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The molecular weights of the recombinant proteins interleukin 2 and interferon gamma were determined by electrospray ionization (ESI) mass spectroscopy on the whole molecules. For interleukin 2 an average experimental mass of 15 549.4 u, was observed in excellent agreement with the theoretical average mass of 15 547.2 u. The mass observed for interferon gamma (16 908.4 u) agreed with the theoretical molecular weight of the monomeric species (16 907.3 u). By ESI mass spectrometry it was possible to determine the presence of proteins lacking one or two amino acids.
    Additional Material: 4 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 2563-2571 
    ISSN: 0887-6266
    Keywords: thermodynamic melting temperature ; thermodynamic melting temperature extrapolation ; n-alkanes thermodynamic melting temperature ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The determination of the thermodynamic equilibrium melting point of a polymer (T0m) by the extrapolation of the melting temperature of its oligomers has been extensively studied in the case of n-alkanes. Nevertheless, a recent publication1 underlines the difficulty to realize this extrapolation. A new method is presented here, leading to an acceptable extrapolation of PE. The equation proposed may give a better value of Tm because the premelting phenomena is being considered in its development. Moreover, this method can be easily extended to a larger number of polymers, such as PEO, PEEK, PPS, etc.© 1998 John Wiley & Sons, Inc. J. Polym. Sci. B Polym. Phys. 36: 2563-2571, 1998
    Additional Material: 14 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1895-1900 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Exchange reactions in molten bisphenol-A polycarbonate-poly(butylene terephthalate) mixtures are investigated by means of model reactions. Transesterification can result either from direct ester-ester interchange or via alcoholysis or acidolysis. Among the various reactions investigated, only the PBTP alcoholysis by phenol is not found to occur. Taking into account that bisphenol-A terephthalate units (A2B1) and butylene carbonate units (A1B2) are formed in equimolecular amounts, it is concluded that direct ester-ester interchange is the most likely mechanism for PC-PBTP transesterification.
    Additional Material: 1 Ill.
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