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  • 1
    Electronic Resource
    Electronic Resource
    Collision induced dissociative chemisorption of CH4 on Ni(111) by inert gas atoms: The mechanism for chemistry with a hammer (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 91 (1989), S. 5756-5777 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The dissociation of CH4 physisorbed on Ni(111) at 46 K is observed to be induced by the impact of incident inert gas atoms. The dynamics and mechanism of this new process, collision induced dissociative chemisorption, are studied by molecular beam techniques coupled with ultrahigh vacuum electron spectroscopies. The absolute cross section for collision induced dissociation is measured over a wide range of kinetic energies (28–109 kcal/mol) and incident angles of Ne, Ar, and Kr atom beams. The cross section displays a complex dependence on the energy of the impinging inert gas atom characteristic of neither total nor normal energy scaling. Quantitative reproduction of the complex dependence of the cross section on the Ar and Ne incident energy by a two-step, dynamical model establishes the mechanism for collision induced dissociation. Collision induced dissociation occurs by the impulsive transfer of kinetic energy upon collision of Ar or Ne with CH4, followed by the translationally activated dissociative chemisorption of the CH4 upon its subsequent collision with the Ni surface. The dependence of the probability of activated dissociation on the resultant CH4 normal energy derived from the fit of the model to the experimental cross section is in excellent agreement with the results of a previous study of the translationally activated dissociative chemisorption of CH4 on Ni(111). Collision induced activation and translational activation are shown to be consistent mechanisms for providing energy to CH4 to surmount the barrier to dissociative chemisorption.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.457529
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  • 2
    Electronic Resource
    Electronic Resource
    Uncooled high-speed InSb field-effect transistors (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 481-483 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: InSb enhancement-mode, metal-insulator-semiconductor, field-effect transistors with 1 μm gate lengths have been fabricated. When operated at room temperature with less than 0.5 V applied between the source and drain, the transistors have a static dynamic range in excess of 20 dB, a cut-off frequency (fT) of 14 GHz and a transconductance, at 1 GHz, of 230 mS mm−1. Analysis of the parasitic capacitances indicates an intrinsic fT of about 90 GHz. The static electron mobility in the channel is 2×104 cm2 V−1 s−1, so a carrier velocity of about 3.7×107 cm s−1 should be attained. This leads to a predicted frequency response of 84 GHz, in reasonable agreement with the intrinsic microwave data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.114063
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  • 3
    Electronic Resource
    Electronic Resource
    SPROUT: 3D Structure Generation Using Templates (1995)
    s.l. : American Chemical Society
    Journal of chemical information and modeling 35 (1995), S. 479-493 
    Details
    ISSN: 1520-5142
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ci00025a016
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  • 4
    Electronic Resource
    Electronic Resource
    LACK OF COMMON HAPLOTYPE AMONG FOUR FAMILY MEMBERS WITH LATE-ONSET KAPOSI'S SARCOMA (1989)
    Oxford, UK : Blackwell Publishing Ltd
    International journal of immunogenetics 16 (1989), S. 0 
    Details
    ISSN: 1744-313X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Kaposi's sarcoma is associated with an increased frequency of HLA-DR5. The hypothesized model of a susceptibility gene in linkage disequilibrium with DR5 may be tested by haplotype analysis in familial Kaposi's sarcoma. Our finding of no common haplotype among afflicted members of a family provides evidence against the hypothesized linkage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1744-313X.1989.tb00467.x
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  • 5
    Electronic Resource
    Electronic Resource
    The structure and chemistry of CH3 and CH radicals adsorbed on Ni(111) (1995)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 102 (1995), S. 7734-7749 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A detailed analysis of the vibrational spectra of CH3, CH2D, and CD3 adsorbed on Ni(111) and the products of their reactions is presented. The synthesis of adsorbed methyl radicals from CH4, CH3D, or CD4 is effected by molecular beam techniques. The ability to measure these spectra by high-resolution electron energy loss spectroscopy (HREELS) at higher resolution (35 cm−1) and higher sensitivity (5×106 counts/s) has allowed new features to be observed and a symmetry analysis to be carried out. It is concluded that the CH3 radical is adsorbed with C3v symmetry on a threefold hollow site. The symmetric C–H stretch mode of CH3 and the overtone of the antisymmetric deformation mode are observed to be in Fermi resonance. At temperatures above 150 K, CH3 dissociates to form adsorbed CH. Confirmation for the assignment to a CH species is found in the observation that the spectrum measured after thermal decomposition of CH2D is a superposition of those from the decomposition of CH3 and CD3. The adsorption site of the CH species is concluded to be a threefold hollow site and the geometry of the Ni3–C–H is concluded to be pyramidal. At temperatures above 250 K, carbon–carbon bond formation between the CH species is observed to yield C2H2. Low coverages of C2H2 are shown to dehydrogenate at 400 K. High coverages of C2H2 are shown conclusively to trimerize to form adsorbed benzene in contrast to a literature report of C2H2 dissociation to adsorbed CH at these temperatures. The relative stabilities of the hydrocarbon species on Ni(111) are determined to be CH3〈CH+2H 〈1/2C2H2+2H〈1/6C6H6+H2(g). © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.469026
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  • 6
    Electronic Resource
    Electronic Resource
    Myelin Basic Protein-Reactive Human T-Cell Clones: Stimulation by Diverse Microbial Antigens (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 756 (1995), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1995.tb44532.x
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  • 7
    Electronic Resource
    Electronic Resource
    Synthesis of benzene from methane over a nickel(111) catalyst (1989)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 111 (1989), S. 8748-8749 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja00205a043
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  • 8
    Electronic Resource
    Electronic Resource
    A hierarchical framework for the analysis of scale (1989)
    Springer
    Landscape ecology 3 (1989), S. 193-205 
    Details
    ISSN: 1572-9761
    Keywords: hierarchy theory ; nonequilibrium ; thermodynamics ; catastrophe theory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Landscapes are complex ecological systems that operate over broad spatiotemporal scales. Hierarchy theory conceptualizes such systems as composed of relatively isolated levels, each operating at a distinct time and space scale. This paper explores some basic properties of scaled systems with a view toward taking advantage of the scaled structure in predicting system dynamics. Three basic properties are explored: (1) hierarchical structuring, (2) disequilibrium, and (3) metastability. These three properties lead to three conclusions about complex ecological systems. First, predictions about landscape dynamics can often be based on constraints that directly result from scaled structure. Biotic potential and environmental limits form a constraint envelope, analogous to a niche hypervolume, within which the landscape system must operate. Second, within the constraint envelope, thermodynamic and other limiting factors may produce attractors toward which individual landscapes will tend to move. Third, because of changes in biotic potential and environmental conditions, both the constraint envelope and the local attractors change through time. Changes in the constraint structure may involve critical thresholds that result in radical changes in the state of the system. An attempt is made to define measurements to predict whether a specific landscape is approaching a critical threshold.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00131538
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  • 9
    Electronic Resource
    Electronic Resource
    Structure of 6-nitro-4-phenyl-1,2-dihydroquinazoline (1989)
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 45 (1989), S. 1114-1115 
    Details
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108270189001769
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  • 10
    Electronic Resource
    Electronic Resource
    Oxidation of low-density lipoprotein in NIDDM: its relationship to fatty acid composition (1995)
    Springer
    Diabetologia 38 (1995), S. 1300-1306 
    Details
    ISSN: 1432-0428
    Keywords: Non-insulin-dependent diabetes mellitus ; low-density lipoprotein oxidation ; dietary fatty acids ; low-density lipoprotein composition ; glycated low-density lipoprotein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The increased risk of atherosclerotic disease in diabetic subjects may be due to enhanced foam cell formation following an increased susceptibility of low density lipoprotein to oxidative modification. This study has compared fatty acid content and lipoprotein oxidisability in 10 non-insulin-dependent diabetic subjects with that in 10 control subjects. Both groups were normocholesterolaemic and the diabetic subjects had higher triglyceride levels (2.2±0.4 vs 1.2±0.2 mmol/l, p〈0.05). The fatty acid composition was compared in low density lipoprotein following Folch extraction, separation by thin layer chromatography (for the lipid classes) and analysis by gas liquid chromatography. Low density lipoprotein oxidisability was assessed by conjugated diene and thiobarbituric acid reacting substance formation in the presence of copper ions. The esterified/free cholesterol ratio was higher in the low density lipoprotein from patients compared to control subjects (2.9±0.1 vs 1.9±0.3, p〈0.05). Linoleic acid in the cholesteryl ester fraction of the lipoprotein was higher in the patients than in the control subjects (48.2±2.2% vs 42.4±3.4%, p〈0.05) as was the total quantity of linoleic acid in the cholesteryl ester fraction (317.8±68.0 vs 213.2±28.0 Μg/mg protein, p〈0.05) and in the low-density lipoprotein as a whole (443.2±70.0 vs 340.2±28.2 Μg/mg protein, p〈0.05). Lipoprotein oxidisability was also increased in the diabetic group with increased formation of thiobarbituric acid reacting substances (35.6±7.2 vs 22.3±3.5 nmol/mg protein, p〈0.05, increased total diene formation (502±60 vs 400±30 nmol/mg protein, p〈0.05) and increased rate of diene formation (7.2±0.6 vs 5.1±0.9 nmol diene · mg protein−1 · min−1, p〈0.05). This study indicates that low-density lipoprotein from diabetic subjects is more susceptible to oxidation. This could, in vivo, accelerate foam-cell formation thereby increasing atherosclerotic risk in diabetic subjects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00401762
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