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  • 1
    Electronic Resource
    Electronic Resource
    Ultrasonic beam propagation through a bimetallic weld—A comparison of predictions of the Gauss-Hermite beam model and finite element method (1993)
    Springer
    Journal of nondestructive evaluation 12 (1993), S. 151-158 
    Details
    ISSN: 1573-4862
    Keywords: Beam propagation ; bimetallic weld ; Gauss-Hermite beam model ; finite element method ; ultrasonics ; anisotropic medium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract In this paper, predictions of two models for the propagation of ultrasonic beams through a two-dimensional, bimetallic weld geometry are compared. The finite element method can predict beam propagation through quite general geometry with high accuracy. This model, however, requires significant computational time. On the other hand, the approximate Gauss-Hermite model offers considerably greater computational speed, but has lower accuracy in certain regions and cannot treat the most general geometries and inhomogeneities in material properties. This paper compares the performances of the two models for the case of the two-dimensional, bimetallic weld consisting of multiple layers, some of which have anisotropic properties. It is found that the results of the two models are in good agreement in the vicinity of the central ray, and that the deviation increases as one moves away from the axis. Also, as the beam propagates through multiple interfaces, the accuracy of the Gauss-Hermite solution decreases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00567571
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  • 2
    Electronic Resource
    Electronic Resource
    The effects of focusing and refraction on Gaussian ultrasonic beams (1984)
    Springer
    Journal of nondestructive evaluation 4 (1984), S. 107-123 
    Details
    ISSN: 1573-4862
    Keywords: ultrasonics ; transducers ; focusing ; refractior ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract A scalar theory of the propagation of Gaussian ultrasonic beams through lenses and interfaces is presented. For radiation into a fluid, the Fresnel approximation is employed to derive the laws of propagation of Guassian beams (previously employed in the analysis of coherent optical systems). These are then generalized to situations commonly found in nondestructive evaluation by treating the effects of propagation through lenses and through curved interfaces at oblique incidence. A numerical example illustrates the ease with which insight into diffraction phenomena for complex geometries can be gained by this approach. The limitations imposed on the theory by aberrations and the scalar assumption are discussed, and the relationship of the Gaussian theory to the radiation of piston transducers is explored.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566401
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  • 3
    Electronic Resource
    Electronic Resource
    Ultrasonic scattering from imperfect interfaces: A quasi-static model (1984)
    Springer
    Journal of nondestructive evaluation 4 (1984), S. 177-196 
    Details
    ISSN: 1573-4862
    Keywords: Interfaces ; ultrasonics ; partial contact ; quasi-static
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract A quasi-static model for the ultrasonic transmission and reflection at imperfect interfaces is developed. The interface is represented by a distributed spring, determined by the change in static compliance of the medium with respect to one with a perfect interface, and a distributed mass, representing excess mass at the interface. Comparison of the model predictions to exact solutions for two simple cases illustrates its accuracy at low frequencies. The spring stiffnesses can be derived from existing solutions for the elastic displacement of materials containing cracks and inclusions under static load. Results for a variety of cases are reviewed. Applications of the model to study the characteristics of partially contacting surfaces in several problem areas of current interest are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566223
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  • 4
    Electronic Resource
    Electronic Resource
    Use of subcritical fluid chromatography for the separation of enantiomers using packed cellulose based stationary phase (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 8 (1996), S. 157-162 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Investigations into the parameters affecting the enantiomeric separation of an intermediate in the synthesis of a drug targeted for cardiac arrhythmia is presented. The separation was achieved under subcritical fluid chromatography using CO2 modified with methanol and co-modifiers isopropyl amine and methylene chloride. The stationary phase was a cellulose based stationary phase manufactured under the trade name Chiracel OB. The results showed the addition of methylene chloride had a noticeable effect on resolution while the separation factor, α, remained constant. The co-modifier, isopropyl amine, did not considerably influence the resolution, or separation factor. Temperature studies were performed in order to establish the thermodynamic parameters of the interaction between the enantiomers and the stationary phase. Plots of In k′ vs. 1/T proved to be curved, while plots of In α vs. 1/T were linear. © 1996 Wiley-Liss, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 5
    Electronic Resource
    Electronic Resource
    Basic dyeability and acid content of high-conversion polyacrylonitrile (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 16 (1972), S. 3341-3351 
    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: Previous data have shown that the basic dyeability of acrylic polymers increases at a given specific viscosity as the peroxydisulfate-to-bisulfite ratio, that is, the catalyst-toactivator (C/A) ratio, is increased. This study represents an effort to understand better the role of the initiator system on the basic dyeability, the acid group composition, and the chain composition of acrylic polymers by preparing model polymers with radioactive initiators. As the C/A ratio is increased, the molecular weight distribution broadens as measured by the M̄v/M̄n ratio, the latter obtained by osmometry. There is also a significant effect of both C/A ratio and molecular weight on the sulfate group content per molecule, but there is no effect of C/A ratio on the number of basic dye sites per molecule, the number of sulfonate groups per molecule, or the weak acid groups per molecule. These effects can be explained by invoking a chain transfer to activator reaction in addition to the usual method of chain termination by recombination. The basic dyeability is found to correlate with the number-average molecular weight and with the number of strong acid groups plus the nonchromophoric weak acid groups.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1972.070161223
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  • 6
    Electronic Resource
    Electronic Resource
    A circular dichroic investigation of the secondary structure of lectins (1978)
    New York : Wiley-Blackwell
    Biopolymers 17 (1978), S. 2107-2120 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The far-uv CD spectra of eight lectins are presented. These eight lectins, as well as others previously studied, are grouped into three classes according to their particular CD spectra. The eight lectins studied appeared to have secondary structure dominated by β-pleated sheet, which so far has been true of all lectins. An attempt was made to quantitate the three structural components (α-helix, β-pleated sheet, and aperiodic) in the lectins using the data for reference proteins given by Chen et al. [Biochemistry 13,3350 (1974)]. For lectins in two of the classes, this method proved excellent and values for the three components are given. However, for the third class of lectins, which includes most of the lectins as well as Concanavalin A, this method of analysis proved to be unsatisfactory. This inadequacy was due to two factors: (1) the reference proteins used by Chen and (2) the unusual CD spectra of these lectins manifested by considerable ellipticity above 225 nm in a region where there are no known peptide electronic transitions.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1978.360170906
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  • 7
    Electronic Resource
    Electronic Resource
    Permethylation of barbiturates. Separation and characterization of the reaction products by gas chromatography-mass spectrometry (1973)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 7 (1973), S. 989-1000 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A Series of barbiturates (I) has been permethylated with the methylsulfinylmethide carbanion and methyl iodide and the products (II to IV) separated, quantified and characterized by g.c.-m.s. The ratios and fragmentation patterns of II to IV are highly dependent upon the nature of the R-groups. All fragment ions have been confirmed by accurate mass measurements or perdeuteriomethylation.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210070809
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  • 8
    Electronic Resource
    Electronic Resource
    Kinetics of OH reactions with aliphatic thiols (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 16 (1984), S. 1623-1636 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of OH reactions with 1-4 carbon aliphatic thiols have been investigated over the temperature range 252-430 K. OH radicals were produced by flash photolysis of water vapor at λ 〉 165 nm and detected by time-resolved resonance fluorescence spectroscopy. All thiols investigated react with OH at nearly the same rate; k(298 K) = 3.2-4.6 × 10-11 cm3 molecule-1 s-1, -Eact = 0.6-1.0 kcal/mol, A = 0.6-1.2 × 10-11 cm3 molecule-1 s-1. CH3SH and CH3SD react with OH at identical rates over the entire temperature range investigated. We conclude that the dominant reaction pathway is addition to the sulfur atom.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550161215
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  • 9
    Electronic Resource
    Electronic Resource
    Kinetic study of the reaction of OH with HCl from 240-1055 K (1985)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 17 (1985), S. 1281-1297 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Absolute rate coefficients for the reaction of OH with HCl (k1) have been measured as a function of temperature over the range 240-1055 K. OH was produced by flash photolysis of H2O at λ 〉 165 nm, 266 nm laser photolysis of O3/H2O mixtures, or 266 nm laser photolysis of H2O2. OH was monitored by time-resolved resonance fluorescenceor pulsed laser-induced fluorescence. In many experiments the HCl concentration was measured in situ in the slow flow reactor by UV photometry. Over the temperature range 240-363 K the following Arrhenius expression is an adequate representation of the data: k1 = (2.4 ± 0.2) × 10-12 exp[-(327 ± 28)/T]cm3 molecule-1 s-1. Over the wider temperature range 240-1055 K, the temperature dependence of k1 deviates from the Arrhenius form, but is adequately described by the expression k1 = 4.5 × 10-17 T1.65 exp(112/T) cm3 molecule-1 s-1. The error in a calculated rate coefficient at any temperature is 20%.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550171206
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  • 10
    Electronic Resource
    Electronic Resource
    The immunodetection of brain proteins blotted onto nitrocellulose from fixed and stained two-dimensional polyacrylamide gels (1984)
    Weinheim : Wiley-Blackwell
    Electrophoresis 5 (1984), S. 35-42 
    Details
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Proteins visualised by Coomassie Blue staining of two-dimensional polyacrylamide gels of complex mixtures of brain proteins were blotted onto nitrocellulose sheets. The Coomassie Blue stain was transferred simultaneously and bound strongly to the nitrocellulose, giving a copy of the original gel pattern. Using specific antisera and a second antibody coupled to horseradish peroxidase, proteins in the original mixture could be detected on the nitrocellulose in quantities less than 25 ng. The Coomassie Blue and horseradish peroxidase stains were distinguishable by a suitable filter, allowing precise correlation of spots stained by Coomassie Blue with spots stained with the brown immunoperoxidase reaction product. The technique was used to identify related proteins in electrophoretograms of brain extracts from different animals.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150050107
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