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  • Polymer and Materials Science  (102)
  • Analytical Chemistry and Spectroscopy  (44)
  • Electronic structure and strongly correlated systems  (32)
  • 1
    Electronic Resource
    Electronic Resource
    Photodegradation of polyethylene films formulated with a titanium-based photosensitizer and titanium dioxide pigment (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 53 (1994), S. 847-856 
    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: This work reports on the photodegradation of low-density polyethylene films formulated with titanium (IV) oxide actylacetonate (TAc) and titanium dioxide pigment in different proportions; no previous reports on the photoactivity of this acetylacotonate have been found. Samples of blow-extruded films were submitted to accelerated UV aging with fluorescent lamps and the polymer degradation measured. The changes in carbonyl groups, molecular weight, and film elongation at break are discussed. The results show that TAc can promote photooxidation and accelerate the film degradation. The retention percent of elongation at break (EB) is apparently proportional to the carbonyl index irrespective of the formulation but has different relations with molecular weight (Mn), time, or the number of chain scissions (n), probably as a result of microstructural differences. © 1994 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1994.070530702
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  • 2
    Electronic Resource
    Electronic Resource
    CVD of Covalent Compounds and high-Tc superconductors (1995)
    Weinheim : Wiley-Blackwell
    Advanced Materials 7 (1995), S. 111-119 
    Details
    ISSN: 0935-9648
    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
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/adma.19950070203
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  • 3
    Electronic Resource
    Electronic Resource
    Tensorial calibration: I. First-order calibration (1988)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 2 (1988), S. 247-263 
    Details
    ISSN: 0886-9383
    Keywords: Calibration ; Tensor ; Multivariate ; PCR ; MLR ; PLS ; Regression ; Multidimensional arrays ; Order ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Many analytical instruments now produce one-, two- or n-dimensional arrays of data that must be used for the analysis of samples. An integrated approach to linear calibration of such instruments is presented from a tensorial point of view. The data produced by these instruments are seen as the components of a first-, second- or nth-order tensor respectively. In this first paper, concepts of linear multivariate calibration are developed in the framework of first-order tensors, and it is shown that the problem of calibration is equivalent to finding the contravariant vector corresponding to the analyte being calibrated. A model of the subspace spanned by the variance in the calibration must be built to compute the contravarian vectors. It is shown that the only difference between methods such as least squares, principal components regression, latent root regression, ridge regression and partial least squres resides in the choice of the model.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180020404
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  • 4
    Electronic Resource
    Electronic Resource
    Tensorial calibration: II. Second-order calibration (1988)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 2 (1988), S. 265-280 
    Details
    ISSN: 0886-9383
    Keywords: Calibration ; Tensor ; Multivariate ; Order ; Regression ; Generalized rank annihilation ; GRAM ; Multi order ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tensorial calibration provides a useful approach to calibration in general. For calibration of instruments that produce two-dimensional (second-order) arrays of data per sample, tensoial concepts are as natural a way of solving the calibration problem as vectorial concepts are for the multivariate problem. Similarly, for third- and higher-order data, the tensorial description of calibration is also useful. This paper introduces second-order calibration from a tensorial point of view. Univariate, multivariate and bilinear approaches to calibration are presented. The generalized rank annihilation method (GRAM) is described from the tensorial perspective, and it is shown that GRAM is equivalent to finding a second-order tensorial base that spans both tensors (calibration and unknown) with respective diagonal component matrices. GRAM uses a single calibration sample for multicomponent analysis even in the presence of interference. Second-order bilinear calibration is extended to multiple calibration samples where the effect of collinearities is reduced.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180020405
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  • 5
    Electronic Resource
    Electronic Resource
    An improved algorithm for the generalized rank annihilation method (1989)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 3 (1989), S. 493-498 
    Details
    ISSN: 0886-9383
    Keywords: Rank annihilation ; Generalized rank annihilation method ; Generalized eigenproblem ; Calibration ; Spectral interferents ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An improved algorithm for the generalized rank annihilation method (GRAM) is presented. GRAM is a method for multicomponent calibration using two-dimensional instruments, such as GC-MS. In this paper an orthonormal base is first computed and used to project the calibration and unknown sample response matrices into a lower-dimensional subspace. The resulting generalized eigenproblem is then solved using the QZ algorithm. The result of these improvements is that GRAM is computationally more stable, particularly in the case where the calibration sample contains chemical constituents not present in the unknown sample and the unknown contains constituents not present in the calibration (the most general case).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180030306
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  • 6
    Electronic Resource
    Electronic Resource
    Tensorial resolution: A direct trilinear decomposition (1990)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 4 (1990), S. 29-45 
    Details
    ISSN: 0886-9383
    Keywords: Tensor ; Superdiagonalization ; GRAM ; Three-way ; Multilinear ; Trilinear ; PARAFAC ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Modern instrumentation in chemistry routinely generates two-dimensional (second-order) arrays of data. Considering that most analyses need to compare several samples, the analyst ends up with a three-dimensional (third-order) array which is difficult to visualize or interpret with the conventional statistical tools.Some of these data arrays follow the so-called trilinear model, \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm R}_{ijk} = \sum\limits_{r = 1}^N {{\rm X}_{ir} {\rm Y}_{jr} {\rm Z}_{kr} + {\rm Error}_{ijk} } $$\end{document} These trilinear arrays of data are known to have unique factor analysis decompositions which correspond to the true physical factors that form the data, i.e. given the array ∝, a unique solution can be found in many cases for each order X, Y and Z. This is in contrast to the well-known second-order bilinear data factor analysis, where the abstract solutions obtained are not unique and at best cannot be easily compared with the underlying physical factors owing to a rotational ambiguity.Trilinear decompositions have had the disadvantage, however, that a non-linear optimization with many parameters is necessary to reach a least-squares solution. This paper will introduce a method for reducing the problem to a rectangular generalized eigenvalue-eigenvector equation where the eigenvectors are the contravariant form (pseudo-inverse) of the actual factors. It is shown that the method works well when the factors are linearly independent in at least two orders (e.g. Xir and Yjr are full rank matrices).Finally, it is shown how trilinear decompositions relate to multicomponent calibration, curve resolution and chemical analysis.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180040105
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  • 7
    Electronic Resource
    Electronic Resource
    Dependence between fusion temperatures and chemical components of a certain type of coal using classical, non-parametric and bootstrap techniques (1990)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 4 (1990), S. 429-439 
    Details
    ISSN: 0886-9383
    Keywords: Principal components ; Multiple and stepwise regression ; Non-parametric density and regression estimation ; Bootstrap inference ; Canonical correlation ; PLS regression ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A statistical study of the dependence between various critical fusion temperatures of a certain kind of coal and its chemical components is carried out. As well as using classical dependence techniques (multiple, stepwise and PLS regression, principal components, canonical correlation, etc.) together with the corresponding inference on the parameters of interest, non-parametric regression and bootstrap inference are also performed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180040606
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  • 8
    Electronic Resource
    Electronic Resource
    The effect of the central linkage on the mass spectrometric behaviour of extended tetrathiafulvalenes (1995)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 9 (1995), S. 856-861 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The electron ionization-induced fragmentation pattern of extended tetrathiafulvalenes has been studied by exact mass measurements, metastable ion analysis and collision-induced dissociation mass spectrometry. The influence on the fragmentation of the central bridge linking the dithiole moieties is discussed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290090928
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  • 9
    Electronic Resource
    Electronic Resource
    Partial esterification of poly(vinyl alcohol) with acid chlorides (1980)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 92 (1980), S. 121-132 
    Details
    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: Die Reaktion von Carbonsäurechloriden mit Polyvinylalkohol wurde untersucht. Die Struktur der modifizierten Polymeren wurde durch IR-, UV-, NMR-Spektroskopie und chemische Analysen bestimmt. Durch die Reaktion des Polyvinylalkohols mit n-Buttersäurechloride entstehen Vinylalkohol-Vinylbutyrat-Copolymere. Wenn der Umsatz dieser Reaktion kleiner als 50% ist, findet man eine Kinetik zweiter Ordnung mit einer Aktivierungsenergie von 9.9 kcal/mol. Wenn Pyridin als Katalysator verwendet wird, nimmt die Reaktionsgeschwindigkeit bemerkenswert zu, unabhängig von dem verwendeten Säurechlorid. Wenn man Triäthylamin als Katalysator verwendet, dann erscheinen aufgepfropfte β-Ketoester-Gruppen in den Polymerketten. Wegen der sterischen Hinderung dieser Nebengruppen wird der Umsatz nicht höher als 30%. Je größber der Gehalt an Estergruppen ist, um so weniger hydrophil ist das Polymere, wie durch Quellungsmessungen der Vinylalkohol-Vinylbutyrat-Copolymeren in Wasser festgestellt wurde.
    Notes: This work deals with some features of the reaction of organic acid chlorides with poly(vinyl alcohol). The structure of the modified polymers was determined by means of IR, UV and NMR spectroscopy as well as by chemical analysis. Vinyl alcohol-vinyl butyrate copolymers were obtained by reaction of poly(vinyl alcohol) with n-butyryl chloride without any catalyst. The reaction appeared to satisfy a second order kinetics for conversions no higher than 50%. The activation energy found was of 9.9 kcal/mol. The use of pyridine as a catalyst involved a noticeable increase of the reaction rate, but this effect was found to be independent of the acid chloride used. When triethylamine was used as a catalyst, β-keto ester groups were found to be grafted onto the polymer chain. The steric hindrance of these groups were thought to be sufficiently important for the conversion to reach a limit of about 30%. The observed swelling in water of vinyl alcohol-vinyl butyrate copolymers made it reasonable to conclude that the hydrophilic character of the copolymers decreased progressively when the ester group content increased.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1980.050920110
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  • 10
    Electronic Resource
    Electronic Resource
    Chemical heterogeneity of a partially modified dextran with ethyl carbonate groups (1985)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 135 (1985), S. 139-149 
    Details
    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: Eine Probe von mit Ethylcarbonatgruppen teilweise modifiziertem Dextran wurde kreuz-fraktioniert. Auf der Basis von Trübungspunkt-Messungen wurden zwei Systeme gewählt: THF/Hexan und DMF/0,5 proz. wässerige NaCl-Lösungen. Die chemische Zusammensetzung (CCD) und die Molekulargewichtsverteilung (MWD) wurden den Fraktionierungsdaten entnommen. Die beobachtete chemische Heterogenität kann mit der Art des Reaktionsmechanismus von Dextran und Ethylchlorformiat korreliert werden. Die kumulativen Fraktionierungsdaten wurden nach den Zwei-Parameter-Funktionen von Tung und Wesslau angepasst.
    Notes: A sample of a partially modified dextran with ethyl carbonate groups was fractionated by cross-fractionation. Two systems THF/hexane and DMF/0.5% aqueous NaCl were selected on the basis of cloud-point determinations. The chemical composition distribution (CCD) and molecular weight distribution (MWD) curves were constructed from fractionation data. The chemical heterogeneity observed may be correlated with the pattern of reaction of dextran with ethyl chloroformate. The cumulative data were fitted by the two-parameter MWD functions of Tung and of Wesslau.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1985.051350112
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