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1

Digitale Medien

Adaptive, global, extended Kalman filters for training feedforward neural networks (1994)

Blank, Thomas B. ; Brown, Steven D.

New York, NY : Wiley-Blackwell

Journal of Chemometrics 8 (1994), S. 391-407

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ISSN: 0886-9383

Schlagwort(e): Neural networks ; Non-linear multivariate regression ; Pattern classification ; Kalman filter ; Chemistry ; Analytical Chemistry and Spectroscopy

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: Finding methods for the optimization of weights in feedforward neural networks has become an ongoing developmental process in connectionist research. The current focus on finding new methods for the optimization of weights is mostly the result of the slow and unreliable convergence properties of the gradient descent optimization used in the original back-propagation algorithm. More accurate and computationally expensive second-order gradient methods have displaced earlier first-order gradient optimization of the network connection weights. The global, extended Kalman filter is among the most accurate and computationally expensive of these second-order weight optimization methods. The iterative, second-order nature of the filter results in a large number of calculations for each sweep of the training set. This can increase the training time dramatically when training is conducted with data sets that contain large numbers of training patterns. In this paper an adaptive variant of the global, extended Kalman filter that exhibits substantially improved convergence properties is presented and discussed. The adaptive mechanism permits more rapid convergence of network training by identifying data that contain redundant information and avoiding calculations based on this redundant information.

Zusätzliches Material: 9 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/cem.1180080605

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2

Digitale Medien

Steroid analysis by gas chromatography with SCOT and wide-bore WCOT columns (1980)

Thomas, B. S.

Weinheim : Wiley-Blackwell

Journal of High Resolution Chromatography 3 (1980), S. 241-247

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ISSN: 0935-6304

Schlagwort(e): Gas chromatography ; Capillary, glass ; Quantitative analysis at 10-10g level ; Steroids in urine ; Amino acid fluorobutyrates (19 in 35 min) ; Installation of glass capillaries ; Connection to FM-ECD ; Chemistry ; Analytical Chemistry and Spectroscopy

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: Glass capillary columns are ideal for analysis of urinary steroid profiles (i.e. the total steroid neutral fraction without prior separation into sub-groups).In this paper performance of both SCOT and wide-bore WCOT columns has been compared, resulting in no significant quantitative difference on urine extracts run as trimethylsilyl ether derivatives. However, because of increased efficiency the WB-WCOT column exhibited more sensitivity in measurement of small amounts of 11-ox-aetiocholanolone. Sensitivity of other steroids was greatly enhanced by use of either SCOT or WB-WCOT, leading to an almost tenfold increase over conventional packed columns (e.g. androsterone and aetiocholanolone 〈 40 μg per 24 h urine sample). A simple splitless injection system (based on a design of Dr. W. Greenaway, Oxford University) is presented.Experiments were also carried out using a SCOT column in conjunction with an FM-electron capture detector. Whilst efficiency was impaired due to the design of the detector, use of He (carrier) and N2 (make up gas) showed that several steroid derivatives could be easily measured at well below the 10-10 g level with much more rapid retention times than with a 1½m packed column. Highly successful separation of 19 amino acids (as fluoro-acyl derivatives) was achieved in 35 minutes using a SCOT (30 m) SP2100 column.

Zusätzliches Material: 12 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/jhrc.1240030504

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3

Digitale Medien

Simultaneous assay of serum vitamin A and vitamin E by high performance liquid chromatography using time-switched UV and fluorimetric detectors (1986)

Russell, M. J. ; Thomas, B. S. ; Wellock, E.

Weinheim : Wiley-Blackwell

Journal of High Resolution Chromatography 9 (1986), S. 281-284

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ISSN: 0935-6304

Schlagwort(e): Liquid chromatography, HPLC ; Time-switched detectors ; UV detection ; Fluorimetric detection ; Vitamin A ; Vitamin E ; Chemistry ; Analytical Chemistry and Spectroscopy

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: An HPLC method utilizing a UV and a fluorimetric detector linked in series is described. By use of a simple integrator-controlled time-switched relay, analysis of serum vitamin A and E is accomplished on the same chromatogram and at optimum sensitivity for each detector. A single internal standard (retinyl acetate) monitored only by the UV detector permits measurement of both vitamins over a wide linear range. Precision of the assays is satisfactory, both on a within-day and on a day-to-day basis. Recoveries of both vitamins are virtually 100% whilst sensitivity is 2 μg/L (retinol) and 0.05 mg/L (α-tocopherol).

Zusätzliches Material: 4 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/jhrc.1240090506

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4

Digitale Medien

A new approach to chemical characterization of polymer surfaces (1995)

Lloyd, Thomas B. ; Ferretti, Kathleen E. ; Lagow, Joyce

New York, NY [u.a.] : Wiley-Blackwell

Journal of Applied Polymer Science 58 (1995), S. 291-296

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ISSN: 0021-8995

Schlagwort(e): Chemistry ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Maschinenbau , Physik

Notizen: The “three-liquid” contact angle procedure of Good et al. was applied to polymer films of varying Lewis acidic and basic nature to test the procedure. Surface energy parameters with the units of mJ/m2 are determined for the surfaces. These are γLWs (Lifshitz-van der Waals or apolar), γ+s (acidic), and γ-s (basic). Very little has yet been published on this new method, and this study found it to be promising. More research on the procedure is warranted. The study included films of basic polymethylmethacrylate (PMMA), and predominately acidic chlorinated polyvinylchloride (CPVC) and polyvinylfluoride (PVF) as well as the series: polyethylene (PE) and PE copolymerized with 1.8% and 7.0% acrylic acid. In some of the experiments receding contact angles were measured, and the surface energy parameters determined in order to cast more light on the mechanism of contact angle hysteresis. © 1995 John Wiley & Sons, Inc.

Zusätzliches Material: 6 Tab.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/app.1995.070580208

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5

Digitale Medien

A new technique for preparing monodisperse polymer particles (1992)

Hou, Wei-Hsin ; Lloyd, Thomas B.

New York, NY [u.a.] : Wiley-Blackwell

Journal of Applied Polymer Science 45 (1992), S. 1783-1788

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ISSN: 0021-8995

Schlagwort(e): Chemistry ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Maschinenbau , Physik

Notizen: A procedure is described for preparing fairly uniform spheres of three different nylon polymers by phase separation. The mean diameter and polydisperse index were 5 μm and 1.056 for Griltex nylon, 5.7 μm and 1.046 for nylon 6/6, and 12.9 μm and 1.016 for nylon 6. The phase separation is done by taking a 1 wt % solution in a theta solvent above the theta temperature and cooling it rapidly. The spheres of the three nylons have various degrees of roughness. Formation of highly uniform particles during phase separation is discussed in a preliminary way. © 1992 John Wiley & Sons, Inc.

Zusätzliches Material: 4 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/app.1992.070451012

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6

Digitale Medien

Temperature dependence of relative modulus in filled polymer systems (1969)

Nielsen, Lawrence E. ; Lewis, Thomas B.

New York : Wiley-Blackwell

Journal of Polymer Science Part A-2: Polymer Physics 7 (1969), S. 1705-1719

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ISSN: 0449-2978

Schlagwort(e): Physics ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Physik

Notizen: The temperature dependence of relative modulus observed in filled thermoset, thermoplastic, and polyelectrolyte salt matrices is explained on the basis of induced stresses produced by the differences in the thermal expansion coefficients of the constituent materials. The analysis is based on the assumption that the modulus of the matrix in a filled polymer is less than that of the unfilled polymer. The temperature dependence of relative modulus is expressed as a function of the difference in thermal expansion coefficients, the volume fraction, the relative modulus in the unstressed state, and mechanical properties of the phases. Agreement is good between the analysis and experimental results for three systems: epoxy and glass, polyethylene and wollastonite, and a polyelectrolyte salt with mica and asbestos.

Zusätzliches Material: 7 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/pol.1969.160071007

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7

Digitale Medien

Bacteriorhodopsin α-helices in lipid settings: Insights for structure prediction (1998)

Woolf, Thomas B.

New York, NY : Wiley-Blackwell

International Journal of Quantum Chemistry 69 (1998), S. 105-116

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ISSN: 0020-7608

Schlagwort(e): bacteriorhodopsin ; protein: lipid interactions ; α-helices ; molecular dynamics ; membrane protein tertiary structure prediction ; Chemistry ; Theoretical, Physical and Computational Chemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: The two-stage model of membrane protein folding predicts that isolated transmembrane α-helices form stably in the bilayer before coming together to form the fully functional protein. Insight into the molecular implications of this model are possible with detailed molecular dynamics calculations. Thirty molecular dynamics simulations of both individual and pairs of α-helices from bacteriorhodopsin were calculated with the CHARMm program. This data base will continue to grow and expand. Already, differences between identical helices in different media and different helices in the same media have been found. The current results are summarized in this contribution. © 1998 John Wiley & Sons, Inc. Int J Quant Chem 69: 105-116, 1998

Zusätzliches Material: 9 Ill.

Materialart: Digitale Medien

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8

Digitale Medien

1H-NMR Untersuchungen der Komplexbildung von Strontium mit Amidopodanden (1990)

Beger, J. ; Thomas, B. ; Stephan, H.

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 332 (1990), S. 1088-1092

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ISSN: 0021-8383

Schlagwort(e): Chemistry ; Organic Chemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: 1H.-N.M.R. Spectroscopic Evidence for the Complex Formation of Strontium Ions by Amido Podands

Zusätzliches Material: 4 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/prac.19903320629

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9

Digitale Medien

Dreikomponentenreaktionen. XX. Methoxymercurierung von Cyclohexa-1,4-dienen (1991)

Beger, J. ; Thomas, B. ; Vogel, T. ; [weitere]

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 333 (1991), S. 447-453

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ISSN: 0021-8383

Schlagwort(e): Chemistry ; Organic Chemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: Three Component Reactions. XX. Methoxymercuration of Cyclohexa-1,4-dienes.The methoxymercuration of several cyclohexa-1,4-dienes leads to insoluble mixtures of mono- and bismercuricompounds 2-4 and 5-7. After reduction with NaBH4/NaOH mixtures of methoxycyclohexenes and bismethoxycyclohexanes result. The result of capillary gaschromatographic analyses and n.m.r. spectra allow a semiquantitative evaluation of the reaction pathways.

Zusätzliches Material: 1 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/prac.19913330310

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10

Digitale Medien

Produktzusammensetzung der Kohlenwasserstoffgemische nach der BIRCH-Reduktion substituierter Benzene und säurekatalysierte Addition von Alkoholen an alkylsubstituierte Cyclohexene und Cyclohexa-1,4-diene (1991)

Beger, J. ; Thomas, B. ; Vogel, T. ; [weitere]

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 333 (1991), S. 481-488

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ISSN: 0021-8383

Schlagwort(e): Chemistry ; Organic Chemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: Composition of Mixtures of Hydrocarbons after BIRCH-Reduction of Substituted Benzenes and Acid Catalyzed Addition of Alcohols to Alkylsubstituted Cyclohexenes and Cyclohexa-1,4-dienes.10 different benzene hydrocarbons 1, indane, tetraline, anisol and phenol are reduced by sodium in liquid ammonia in the presence of methanol to the BIRCH products 2. The product mixture compositions are determined through capillary GLC. On storage at + 6°C some rearomatization of the 1,4-cyclohexadienes 2 occurs. Data of the 1H- and 13C-n.m.r. spectra and also mass spectra of the BIRCH 1,4-dienes 2 are given. For comparison 4-alkoxycyclohexenes 4 and 1-alkoxy-1-methylcyclohexanes 8 are prepared and spectroscopically characterized. Acid-catalyzed addition of alcohols to the 1,4-cyclohexadiene systems is a slow process and gives the 4-alkoxy-4-alkylcyclohex-1-enes (4) only in moderate yields up to 30 %. Most of the products are dimers 5 and also oligomers 6 of the parent hydrocarbons 2.

Zusätzliches Material: 1 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/prac.19913330315

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