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  • 11
    Electronic Resource
    Electronic Resource
    n-AlGaSb and GaSb/AlGaSb double-heterostructure lasers grown by organometallic vapor phase epitaxy (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 68 (1996), S. 400-402 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: n-type doping of AlxGa1−xSb epilayers (0≤x≤1) grown by organometallic vapor phase epitaxy has been achieved by using tritertiarybutylaluminum, triethylgallium, and trimethylantimony as the organometallic precursors and diethyltellurium as the doping source. Electron concentrations exceed 1017 cm−3 for layers with x〈0.3, and decrease to ∼1016 cm−3 for x=1 as a result of higher residual acceptor concentration. Lattice-mismatched double-heterostructure diode lasers with AlGaSb cladding layers and GaSb active layer are demonstrated, and indicate the potential of OMVPE for growth of GaSb-based materials for electronic and optoelectronic devices. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.116698
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  • 12
    Electronic Resource
    Electronic Resource
    Scanned-probe lateral-force determination of fluid-dynamic effects near a solid surface in air (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 130-132 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A calibrated method for the experimental determination of dynamic lateral force using a scanned probe in air has been applied to the measurement of force vs distance as the probe tip approaches a solid surface. The probe is a fused silica fiber vibrated with its axis perpendicular to the surface in a configuration commonly used for distance regulation in near-field scanned optical microscopes. Quantitative agreement of a fluid-dynamic model with the approach data demonstrates that the effects of fluids between the probe and the surface dominate the force on the probe in the optical far field. A two-layer fluid model indicates that fluid-dynamic effects must also be considered in lateral-force determination in the optical near field. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.118098
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  • 13
    Electronic Resource
    Electronic Resource
    Dicarbocyanine dyes in methanol solution probed by depolarized Rayleigh and hyper-Rayleigh light scattering (1996)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 104 (1996), S. 8230-8236 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The hyper-Rayleigh scattering (HRS) intensity of two symmetric carbocyanine dyes (1122 DEDC and 1144 DEDC, full names given in the text) in methanol is measured as a function of dye concentration. These dye molecules at equilibrium show a negligible permanent dipole moment. The low concentration data showing that the HRS intensity is proportional to the dye concentration are used to determine the first hyperpolarizability for each of these dyes. However, above a concentration ρb=0.1×10−3 M, the HRS intensity shows an anomalous concentration dependence. Above ρb, the HRS intensity shows a saturation behavior and it even decreases with increasing concentration at high dye concentration. The depolarization ratio of the HRS intensity is also measured as a function of dye concentration. At lowest concentration, the depolarization ratio is 0.18. As the dye concentration increases, the depolarization ratio also rapidly increases but the increase quickly saturates as the concentration exceeds ρb. The concentration dependence of the HRS intensity and depolarization ratio are interpreted as due to formation of molecular aggregates. The depolarized Rayleigh scattering (DRS) intensity is also measured as a function of dye concentration. The result of DRS corroborates well with that found in HRS. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.471576
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  • 14
    Electronic Resource
    Electronic Resource
    Determination of first hyperpolarizability of nonlinear optical chromophores by second harmonic scattering using an external reference (1996)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 104 (1996), S. 7821-7829 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: First hyperpolarizabilities (β) of two tricyanovinylthiophene nonlinear optical chromophores were determined using second harmonic, hyper-Rayleigh, scattering. The use of an external standard in the determinations is compared with the previous use of an internal standard. The first hyperpolarizability of the well-known chromophore 4 dimethylamino 4′ nitrostilbene (DANS) was also determined using the external standard method and its value is compared to those in the literature. A new method of analyzing the hyper-Rayleigh scattering signal by recording a histogram of the scattered energy is reported. This method is shown to give more reliable results in a shorter period of time than the usual static gate method. The histogram function provides additional information in the form of the histogram width which is shown to be an indication of the mean-square concentration fluctuations of the chromophores in solution. The effects of molecular interactions on the concentration dependence of the hyper-Rayleigh scattering signal is discussed. It is shown that depending on the concentration range, the β value of para-nitroaniline, used as the external standard, can agree with two different values reported in the literature. Results on the depolarization ratio of the hyper-Rayleigh scattered light from one of the tricyanovinylthiophene chromophores are presented. At low concentration the depolarization ratio agrees with the theoretically predicted value based on C2v symmetry. However, at higher concentration the measured depolarization ratio increases indicating molecular interactions. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.471669
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  • 15
    Electronic Resource
    Electronic Resource
    Surface laser light scattering studies of the air/poly(N-vinyl-2-pyrrolidone)-water solution interface (1996)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 105 (1996), S. 6546-6552 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: An experimental study of poly(N-vinyl-2-pyrrolidone) (PVP) in water solution has been carried out by using the surface laser light scattering (SLLS) technique. The concentration dependence data of the peak frequency and linewidth are obtained from the SLLS spectra of the PVP/water solutions with two PVP molecular weights over a wide concentration range varying from the dilute to semidilute regime. The equilibrium surface tension of the solution is also measured as a function of polymer concentration and molecular weight. In the dilute solution, the peak frequency and surface tension show only a small decrease with increasing concentration. However, in the semidilute concentration regime, the surface tension and the frequency shift decrease rapidly with increasing concentration, accompanied by the dramatic increase in the spectral linewidth. The surface tension, SLLS spectral peak frequency and linewidth show an important molecular weight dependence. Over the entire concentration range investigated, the SLLS data of the PVP/water solutions do not show evidence of the capillary to Rayleigh wave evolution. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.472463
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  • 16
    Electronic Resource
    Electronic Resource
    Macular amyloidosis with widespread diffuse pigmentation (1996)
    Oxford, UK : Blackwell Publishing Ltd
    British journal of dermatology 135 (1996), S. 0 
    Details
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Summary We report two patients with an unusu al variant of macular amyloidosis who had diffuse homogeneous hyperpigmentation without papules, a rippled pattern or poikiloderma. The hyperpigmentation was extensive, involving the face, neck, mucosa, axillae, groin and peripheries in one patient and only the face and arms in the other. Skin biopsies in both cases revealed subepidermal band-like amyloid deposits. Neither patient had systemic involvement. The skin lesions in these patients could be easily confused with hyperpigmentation caused by endocrine disorders, drugs, heavy metals, polychlorinated biphenyl or cutaneous inflammation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2133.1996.d01-951.x
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  • 17
    Electronic Resource
    Electronic Resource
    LIMITS OF PARALLEL PROCESSING: EXCITATORY CONVERGENCE OF DIFFERENT INFORMATION CHANNELS ON SINGLE NEURONS IN STRIATE AND EXTRASTRIATE VISUAL CORTICES (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Clinical and experimental pharmacology and physiology 23 (1996), S. 0 
    Details
    ISSN: 1440-1681
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: 1. It has been postulated that the distinct parallel retinogeniculo-cortical information channels characterizing visual pathways of virtually all mammals are selectively linked to parallel motion, colour and/or form information processing ‘streams’ distinguishable within the primary visual cortices, extrastriate cortical areas of occipital lobes and the temporal and parietal visual cortices.2. Using selective pressure-blocking of the large-fibre channel (the so-called Y-channel) in the optic nerve of the cat, we have experimentally examined the ‘selective excitatory parallel links’ hypothesis. We conclude that the majority of neurons in the primary visual cortices (areas 17, 18) as well as in the two ‘higher order’ visual areas, area 21a and posteromedial lateral suprasylvian (PMLS) area, constituting, respectively, part of the ‘form’ and part of the ‘motion’ processing streams, receive their excitatory inputs from both Y- and non-Y-information channels. In areas 17, 18 and 21a (but not in PMLS area), there are, however, subpopulations of cells that apparently receive excitatory inputs from only one information channel.3. Review of the relevant work on the macaque monkey suggests that the situation is similar in the primate: that is, there is a substantial degree of excitatory convergence of different retino-geniculo-cortical information channels on single neurons in the primary visual cortices and the extrastriate cortices constituting parts of the form/colour or the motion processing streams.4. Despite this high degree of excitatory convergence of different information channels, the large-fibre channels (the Y-channel in the cat and the magnocellular or Y-like channel in macaque), are in both carnivores and primates the principal contributors to the motion processing cortical streams.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1440-1681.1996.tb01143.x
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  • 18
    Electronic Resource
    Electronic Resource
    AN ANALYSIS OF MEAN STRESS IN MULTIAXIAL RANDOM FATIGUE (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Fatigue & fracture of engineering materials & structures 19 (1996), S. 0 
    Details
    ISSN: 1460-2695
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract— Generally engineering components are subjected to multiaxial variable amplitude loading, which may be non-proportional. One of the best known low cycle fatigue design codes that addresses non-proportional loading problems is the ASME Boiler and Pressure Vessel Code, but this does not include a cycle counting method and it does not allow for the presence of a mean stress. Traditional rainflow methods, incorporating a strain range and a mean stress, are applicable only where there is a single load varying with respect to time, or possibly where multiaxial loads are proportional. So a multiaxial non-proportional cycle counting method and a fatigue damage calculation procedure are proposed here, based on plastic deformation response and a critical plane hypothesis that incorporates the effect of mean stress. A cyclic deformation model, based on the Ramberg-Osgood equation and a multiaxial memory rule, is used to calculate the mean stress response under variable amplitude loading.The proposed procedure is assessed with combined tension/torsion tests on En15R steel under variable amplitude loading. Fatigue life predictions are compared for analysis with and without mean stress corrections, to assess the sensitivity to mean stresses of non-proportional fatigue endurance in the low cycle regime.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-2695.1996.tb00970.x
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  • 19
    Electronic Resource
    Electronic Resource
    Structural relationship of various squarates (1996)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 52 (1996), S. 966-975 
    Details
    ISSN: 1600-5740
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: This work illustrates the structural relationship between three types of metal squarates as well as the ligand in its acid form and in its monoanion salt. Squaric acid, H2C4O4, is known to have a polymeric layer structure with planar molecules connected through intermolecular hydrogen bonds. The interlayer distance is only 2.649 Å. The crystal of H2NMe2[H3(C4O4)2] is found to contain columns of [H3(C4O4)2−] repeating units, again connected by intermolecular hydrogen bonds. Within the repeated unit, there is a symmetric hydrogen bond connected to two HC4O4 moieties. A new type of metal squarate with M(HC4O4)2(H2O)4 M = MnII, FeII both belong to space group P\bar 1, Z = 1, a = 5.194 (3), b = 7.454 (2), c = 8.901 (2) Å, α = 67.07 (2), β = 77.26 (3), γ = 74.46 (4)°, for MnII is shown to have a layer-type structure, where all [HC4O4] units are bonded into infinite chains via symmetric hydrogen bonds, each (HC4O4)22− ligand bridging two metal ions (μ-2) in a trans fashion. The structurally most well understood metal squarate M(C4O4)(H2O)4 (M = MnII, FeII, CoII, NiII and ZnII, space group C2/c, Z = 4) is again a polymeric chain with C4O42− serving as a bridging ligand between two metal ions (μ-2) in trans positions. A three-dimensional polymeric structure is found to have the formula M(C404)(H2O)2, where C4O42− is a bridging ligand between four metal ions (μ-4). Due to the slight difference in packing, there are two structure types in this category: one is in space group R{\bar 3} [M = FeII, a = 11.440 (2), c = 14.504 (3) Å, Z = 9], the other is in Pn{\bar 3}n [M = CoII, a = 16.255 (3) Å, Z = 24]. The structural relationship between all these structures relies heavily on the understanding of intra- and intermolecular hydrogen bonds. The interesting building blocks of each compound will be illustrated. There are tunnels of various sizes in all these structures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108768196009639
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  • 20
    Electronic Resource
    Electronic Resource
    Structural stability of heat-treated Co/C soft X-ray multilayers fabricated by dual-facing-target sputtering (1996)
    Springer
    Applied physics 63 (1996), S. 57-65 
    Details
    ISSN: 1432-0630
    Keywords: PACS: 68.65.+g; 68.60.Dv; 68.55.Jk
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract.  Thermal stability of Co/C multilayers prepared by a dual-facing-target sputtering system was studied. A picture of the thermally induced changes in the microstructure was obtained using complementary measurement techniques including low-angle and high-angle X-ray diffraction, transmission electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. It was found that the period expansion, reflectivity change and compound formation, that were observed after annealing are caused by structural changes both in the sublayers and at the interfaces. Below 400 °C, the period expansion is mainly caused by the graphitization of the amorphous carbon layers, and a significant increase in the reflectivity at grazing incidence was observed. By 500 °C, the crystallization and agglomeration of Co layers induce an enormous period expansion and a serious decrease in reflectivity. A small amount of carbide is found to form at this temperature. Our results imply that new multilayer structures, e.g., compound multilayers will have to be developed for use at high temperatures or under high X-ray incident flux.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003390050352
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