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  • 1
    Electronic Resource
    Electronic Resource
    On the fundamentals of the gradient theory of van der Waals (1997)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 106 (1997), S. 9820-9834 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In this study a simple relation has been derived for the influence parameter in the gradient theory of van der Waals in terms of simple accessible quantities like temperature, the equilibrium densities, and the equilibrium isothermal compressibilities. Application of this relation leads to a substantially better agreement between interfacial tensions computed from the gradient theory and tensions obtained from experiment and simulation. The basis for this novel relation is an expression that connects the influence parameter to the second moment of the direct correlation function of pure fluids at states within the binodal region. The direct correlation functions for this study have been obtained from solving of the Ornstein–Zernike equation and the Percus–Yevick (PY) or hypernetted chain (HNC) closure relations for a Lennard–Jones (LJ) fluid. Special attention was paid to the behavior of solutions in the vicinity of the nonsolution region. It was shown for the PY closure that at the low density side the isothermal compressibility remains finite at the boundary of the nonsolution region. Along the isotherms and isochors the isothermal compressibility terminates at this boundary in so-called square root branch points. The isothermal compressibility diverges on the high density side although the correct location of the spinodal locus could not be found because of numerical inaccuracies. Diverging compressibilities are never encountered as the solution boundary is reached using the HNC closure. In all cases the isothermal compressibility terminates in square root branch points along the isotherms and isochors. In addition, computations show that at this boundary, the second moment of the direct correlation function seems to diverge for both the PY and the HNC closure. Comparison of the tensions obtained from the gradient theory with those obtained from a partial summation of the gradient expansion shows that at low temperatures the former results are ∼50% higher. Comparison of the results obtained from the latter model with experiments and simulations shows good agreement. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.473872
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of residual ion damage on the minority carrier lifetime in molecular beam epitaxy grown silicon doped by low-energy ion implantation (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 67 (1995), S. 977-979 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The residual ion damage due to low-energy ion implantation during molecular beam epitaxy growth was investigated by measuring the minority carrier lifetime in the base of a silicon bipolar transistor. The base was doped with As+ ions at 200 eV to a concentration of 1019 cm−3. Three samples were grown at temperatures of 500, 650, and 800 °C. The 500 °C sample had a minority carrier lifetime in the base ∼1/6 that of the samples grown at the higher temperatures. On annealing at 650 °C the lifetimes of all samples were essentially equal. The results indicate that at this dopant concentration the collision cascades caused by ion bombardment do not overlap. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.114964
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  • 3
    Electronic Resource
    Electronic Resource
    Global phase behavior based on the simplified-perturbed hard-chain equation of state (1995)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 102 (1995), S. 3361-3375 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The equation of state that results from the simplified-perturbed hard-chain theory (SPHCT) has been used to calculate phase diagrams for binary fluid mixtures and to classify these phase diagrams in accordance with the system of van Konynenburg and Scott. For molecules with equal or similar sizes, the global phase diagrams are similar to the ones obtained with the van der Waals, Redlich–Kwong, and Carnahan–Starling–Redlich–Kwong equation of state. In addition to the types I–V, one can calculate also types VI, VII, and VIII with the SPHCT equation. For molecules with large size differences two new, main types of phase behavior have been discovered. We propose to call them type IX and X. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.469210
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  • 4
    Electronic Resource
    Electronic Resource
    On the retrograde condensation behavior of lean natural gas (1995)
    Springer
    International journal of thermophysics 16 (1995), S. 629-642 
    Details
    ISSN: 1572-9567
    Keywords: characterization ; equations of state ; liquid dropout ; natural gas ; phase behavior ; potential hydrocarbon liquid content ; retrograde condensation ; supercritical solubility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The occurrence of liquid dropout in natural gas pipelines may cause operational problems during storage, transport, and processing. Therefore, the availability of a model that accurately predicts the amount of liquid formed is of great importance for the natural gas industry. The objective of this study is to develop a thermodynamic model for the accurate prediction of the amount of liquid formed in natural gas pipelines at transportation conditions. As input, the model requires an accurate gas analysis. A modified Peng-Robinson equation of state was selected for the phase equilibrium calculations. Interaction parameters were optimized from experimental data at conditions of practical interest, i.e., at pressures 10 〈 p 〈 70 bar and at temperatures 250 〈 T 〈 290 K. For a number of “keysystems,” the interaction parameters were calculated from new accurate solubility data of heavy hydrocarbons in some of the main constituents of natural gas like methane and nitrogen. Also, an extensive experimental program was carried out to study the influence of minute amounts of nitrogen, ethane and carbon dioxide in methane on the solubility behavior of decane in these gas mixtures. From a sensitivity analysis, it could be concluded that the liquid dropout is influenced mainly by the concentration and characterization of C7-C13 fractions. In this work, two characterization procedures to represent these fractions are compared. For two types of lean natural gas, the model predictions are compared with field measurement data, recently supplied by the Dutch natural gas industry.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01438848
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  • 5
    Electronic Resource
    Electronic Resource
    Ultrastructural characteristics of Sin Nombre virus, causative agent of hantavirus pulmonary syndrome (1995)
    Springer
    Archives of virology 140 (1995), S. 2107-2122 
    Details
    ISSN: 1432-8798
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A previously unrecognized disease, hantavirus pulmonary syndrome, was described following an outbreak of severe, often lethal, pulmonary illness in the southwestern United States in May–June, 1993. We have now studied the morphologic features of the causative agent, Sin Nombre virus (SNV), by thin section electron microscopy and immunoelectron microscopy of infected Vero E6 cells. SNV virions were roughly spherical and had a mean diameter of 112 nm. They had a rather dense envelope and closely apposed fine surface projections, 7 nm in length. Filamentous nucleocapsids were present within virions. Viral inclusion bodies were present in the cytoplasm of infected cells; these appeared granular or filamentous, depending on the plane of section. All of these characteristics were similar to published descriptions of other hantaviruses; however, unlike all other hantaviruses and virtually all other member viruses of the familyBunyaviridae which bud upon smooth intracytoplasmic membranes, SNV budding occurred almost entirely upon the plasma membrane of infected cells. Virus budding was associated with the formation of long 28 nm diameter tubular projections. Occasional elongated 47 nm diameter virus-like particles were seen to bud upon intracytoplasmic membranes. As shown by immunoelectron microscopy, viral antigens were localized over virions, inclusions, and tubular projections associated with virion morphogenesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01323234
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