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  • 1
    Electronic Resource
    Electronic Resource
    Quasielastic light scattering study of ternary polymer solutions of polystyrene and poly(methyl methacrylate) in dioxane (1997)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 106 (1997), S. 3775-3781 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The dynamic behavior of the mixture polystyrene (PS)–poly(methyl methacrylate) (PMMA)–dioxane in the semidilute concentration regime has been investigated by quasielastic light scattering. Two types of PS–PMMA–dioxane solution have been studied: One at a fixed composition but with different total polymer concentrations, and the other at a fixed total polymer concentration but with different compositions. For each solution, two distinct modes have been observed in the autocorrelation function of the scattered light; their relaxation times and relative amplitudes are studied as functions of composition and total polymer concentration. The present method differ from the previous one by not requiring one polymer to be isorefractive with solvent. By using the experimental results and with the help of theory, the self-diffusion coefficients of PS and PMMA and the Flory–Huggins interaction parameter χF have been deduced. The χF values obtained in this work are in good agreement with that obtained by other methods. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.473430
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  • 2
    Electronic Resource
    Electronic Resource
    Theory of quasielastic light scattering of a ternary solution consisting of two homopolymers with arbitrary optical, hydrodynamic, and thermodynamic properties (1997)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 107 (1997), S. 3675-3683 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The temporal dependence of the time correlation function detected by quasielastic light (QEL) scattering in solution consisting of two homopolymers with arbitrary hydrodynamic and thermodynamic properties is investigated. New results appropriate for the ternary polymer solution in various concentrations are obtained. These new results should facilitate the analysis of the QEL scattering data of a ternary solution in any concentrations. Information about tracer diffusion coefficients of the constitutive polymers and their excluded volume interaction parameter is shown to be obtainable from the QEL experiment of the ternary polymer solution. Applications to ternary polymer solutions with one polymer isorefractive with the solvent, solutions with two polymers differing only in molecular weight, and solutions with two polymers having arbitrary refractive index increments are discussed. Clarification in regard to the ternary solution under the zero average contrast (ZAC) condition is also made. It is shown that under the ZAC condition, the autocorrelation function of the composition fluctuation in general decays with two exponentials, even at 1:1 symmetric composition. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.474723
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  • 3
    Electronic Resource
    Electronic Resource
    Hydrodynamic surface waves in concentrated polymer solutions in the presence of surface adsorption (1997)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 107 (1997), S. 5898-5906 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A theory of light scattering from the polymer solution/air interface that includes the effect of surface adsorption is developed. The polymer solution is assumed to exhibit a linear viscoelastic response. The surface laser light scattering (SLLS) spectrum is calculated from surface hydrodynamic equations appropriate for linear viscoelastic fluids using the method of initial value problems. Numerical calculations are made to investigate the effects of surface tension and dilational modulus on the SLLS spectrum. The results show that the SLLS spectrum from polymer solutions having a high surface tension solvent displays a two-peak structure. The high-frequency peak exhibits more capillary wave character, and diminishes rapidly with decreasing surface tension or increasing dilational modulus as a result of surface adsorption. The two-peak structure is, however, found to be much less pronounced in a solution with a low surface tension solvent. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.474315
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of external electric field on semidilute polymer solutions probed by dynamic light scattering (1997)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 106 (1997), S. 2819-2823 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Dynamic light scattering studies of polystyrene (PS) in tetrahydrofuran (THF) in 1,4-dioxane (DO) and in THF/DO mixed solvent, subject to an external dc field, have been carried out. In THF the rate constant for the decay of the intensity autocorrelation function (IACF) is found to increase with increasing the external applied electric field; in DO, the electric field is found to have only a negligible effect on the IACF; in the mixed solvent it exhibits an intermediate effect, depending on the THF content. A hydrodynamic theory is proposed to account for the observed electric field induced effect in THF. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.473358
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  • 5
    Electronic Resource
    Electronic Resource
    Excitatory Convergence of Y and Non-Y Information Channels on Single Neurons in the PMLS Area, a Motion Area of the Cat Visual Cortex (1997)
    Oxford, UK : Blackwell Publishing Ltd
    European journal of neuroscience 9 (1997), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: We analysed the receptive field properties of neurons in the posteromedial lateral suprasylvian (PMLS) visual cortical area of anaesthetized cats in which there was selective conduction block of the largest (Y-type) fibres in one optic nerve. As in normal cats, in cats with selective block of one optic nerve the great majority of PMLS cells could be activated by photic stimulation through either eye. However, the responses evoked by stimulation via the eye with the selectively pressure-blocked optic nerve (‘Y-blocked eye’) were significantly weaker than those of the same cells evoked by the stimulation via the normal eye. Accordingly, eye dominance histograms were shifted markedly in favour of the normal eye. Furthermore, there was a significant shift towards lower preferred velocities when PMLS cells were photically stimulated via the Y-blocked eye. Finally, when stimulated via the Y-blocked eye, PMLS cells responded poorly or not at all to high stimulus velocities (≤100°/s). On the other hand, a number of receptive field properties, such as the spatial organization of receptive fields, the size of the discharge fields, orientation tuning and direction selectivity indices, were not significantly affected by the removal of the Y input. We conclude that virtually all neurons in the PMLS area of the cat receive excitatory input from both Y and non-Y information channels, although the Y channel provides the dominant input and makes the principal contribution to the detection of high-velocity motion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-9568.1997.tb01443.x
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  • 6
    Electronic Resource
    Electronic Resource
    Light and electron microscopic evidence of white spot disease in the giant tiger shrimp, Penaeus monodon (Fabricius), and the kuruma shrimp, Penaeus japonicus (Bate), cultured in Taiwan (1997)
    Oxford, UK : Blackwell Science Ltd
    Journal of fish diseases 20 (1997), S. 0 
    Details
    ISSN: 1365-2761
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Since 1992, mass mortalities among cultured giant tiger shrimp, Penaeus monodon (Fabricius), and kuruma shrimp, Penaeus japonicus (Bate), have been observed in Taiwan. The condition is known as ‘white spot disease’ (WSD), based on the characteristic white spots on the cuticle of diseased shrimp. With the scanning electron microscope, two sizes of white spots were observed. Each spot represented a protrusion on the inside surface of the carapace. The composition of white spots was similar to that of the cuticule, most calcium, as determined with an energy dispersive spectrometer. Histological studies of moribund, infected specimens revealed degenerated cells, characterized by hypertrophied nuclei, in various meso- and ectodermal tissues. Infected tissues included cuticular epidermis, connective tissue, lymphoid organ, antennal gland, and haematopoietic, gill and nervous tissue. Nuclei were Feulgen-positive and no occlusion body was found in the necrotic tissue. Transmission electron microscopy revealed the presence of rod-shaped and enveloped virions in the hypertrophied nuclei. The virions measured 298 ± 21 × 107 ± 8 nm in the giant tiger shrimp and 248 ± 12 × 104 ± 8 nm in the kuruma shrimp. In an experimental infection trial, cumulative mortality was 40% within 14 days under stress conditions. No mortality was observed in controls or in non-stressed infected shrimp. Experimental infections show that environmental stressors such as ammonia may enhance the severity of WSD virus infections in cultured shrimp.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2761.1997.00301.x
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  • 7
    Electronic Resource
    Electronic Resource
    Monosymptomatic hypochondriacal psychosis complicated by self-inflicted skin ulceration, skull defect and brain abscess (1997)
    Oxford, UK : Blackwell Science Ltd
    British journal of dermatology 137 (1997), S. 0 
    Details
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Self-inflicted dermatoses are associated with personality disorders and psychoses, including monosymptomatic hypochondriacal psychosis (MHP), which is characterized by a delusion involving a particular hypochondriacal concern. We report an unusual case of MHP with severe mutilation of the skin complicated by a skull defect and brain abscess. The patient was a 66-year-old uneducated man who damaged his forehead repeatedly because he believed that a ‘toxic root’ in the forehead was the source of his general ailment. He admitted that the lesions were self-inflicted. There was no other evidence of psychosis or primary skin disease and MHP was diagnosed. Despite initial favourable response to pimozide, the patient was lost to follow-up for 4 years, during which he continued to damage his forehead and applied corrosive agents. He was then referred with a personality change and a 6 × 4 cm bony defect in the skull, complicated by herniation and abscess of the left frontal lobe. This case represents one of the most severe examples of self-mutilation ever reported. The differential diagnosis of dermatitis artefacta and the principles of treating MHP are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2133.1997.18261917.x
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  • 8
    Electronic Resource
    Electronic Resource
    Onset of natural convection in a sector-shaped box containing a fluid-saturated porous medium (1997)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 9 (1997), S. 3570-3571 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.869465
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  • 9
    Electronic Resource
    Electronic Resource
    Use of thin wall imaging in the diagnosis of laser heated hohlraums : Proceedings of the eleventh topical conference on high temperature plasma diagnostics (1997)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 68 (1997), S. 838-841 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: High-Z, laser heated hohlraums can be made thick enough to contain thermal radiation, yet thin enough to let out x rays 〉∼6 keV produced by hot, relatively dense blow-off plasma. We use such "thin wall hohlraums" to observe the physical location of hot, dense, laser produced hohlraum plasmas. This technique has allowed us to come to some understanding of laser transport/deposition, plasma stagnation, and bulk plasma filling. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1147703
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  • 10
    Electronic Resource
    Electronic Resource
    High-performance GaInAsSb thermophotovoltaic devices with an AlGaAsSb window (1997)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 71 (1997), S. 3758-3760 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A large increase in the quantum efficiency (QE) and open-circuit voltage Voc of GaInAsSb thermophotovoltaic (TPV) devices is obtained by the use of an AlGaAsSb window layer compared with devices without a window layer. The TPV structure, grown on GaSb substrates by organometallic vapor phase epitaxy or molecular beam epitaxy, consists of a 1-μm-thick n-GaInAsSb base layer, a 3-μm-thick p-GaInAsSb emitter layer, a 100-nm-thick AlGaAsSb window layer, and a 25-nm-thick GaSb contacting layer. The band-gap energy of the lattice-matched GaInAsSb is 0.53–0.55 eV. The peak internal QE of the TPV cells with the window is 〉90%, compared with less than 60% for those without the window. At a short-circuit current density of ∼1000 mA/cm2, Voc of ∼300 meV is obtained for cells with the window layer, compared with less than 220 meV without the window layer. These increases are attributed to a substantial decrease in the surface recombination velocity with the window layer. Based on a standard calculation, the electron diffusion length in the p-GaInAsSb layer is at least 5 μm. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.120497
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