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  • 11
    Electronic Resource
    Electronic Resource
    Photochemical decomposition of AsH3 on GaAs(100) (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 97 (1992), S. 605-615 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Molecular AsH3, adsorbed on Ga-rich GaAs(100) at 115 K, dissociates readily upon uv irradiation with 193, 248, and 351 nm excimer laser light. In the initial photodissociation step one As–H bond cleaves, leaving all the AsH2, and a large fraction of the H, adsorbed to As. The AsH2 further photodissociates to give As–H and Ga–H. The final steps, photochemical removal of hydrogen from Ga–H and As–H, lead to As deposition. The photodissociation cross section decreases sharply with the extent of photolysis. The wavelength dependence, compared to the gas-phase absorption cross section, extends to much lower photon energies and indicates that substrate-mediated excitation dominates the observed chemistry. There are strong isotope effects in all the cross sections; these are related to mass-dependent substrate-mediated quenching of the excited states. Implications for photon-assisted organometallic chemical vapor deposition are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.463556
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  • 12
    Electronic Resource
    Electronic Resource
    Surface photochemistry. II. Wavelength dependences of photoinduced dissociation, desorption, and rearrangement of O2 on Pt(111) (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 91 (1989), S. 5011-5020 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A Pt(111) surface saturated with molecular oxygen was irradiated by UV light from a mercury arc lamp with various cutoff filters. High-resolution electron energy-loss spectroscopy (HREELS) and temperature programmed desorption mass spectroscopy (TPD) were used to characterize the products retained on the surface. Upon UV irradiation at 95 K, chemisorbed O2 (peroxo) undergoes dissociation, desorption and rearrangement. Different wavelength dependences were observed for the three processes: dissociation was not observed at wavelengths longer than 295 nm, in agreement with gas phase photodissociation of the O–O bond in hydrogen peroxide; desorption and rearrangement became negligible at wavelengths longer than 420 nm, in agreement with the photolysis of an organometallic peroxoplatinum complex. For wavelengths between 230 and 315 nm, the average cross sections of dissociation and desorption were estimated to be 5.7×10−20 and 1.2×10−19 cm2 , respectively. The possible origins of the three processes are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.456741
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  • 13
    Electronic Resource
    Electronic Resource
    Direct and precursor dynamics in dissociative hydrogen chemisorption on Ni(100) (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 90 (1989), S. 7442-7447 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We report evidence for the coexistence of direct and precursor dynamics in the dissociative chemisorption of H2 on Ni(l00). Hydrogen and deuterium uptakes on Ni(l00) were measured at various surface temperatures by following the secondary ion ratios, Ni2 H+/Ni+ and Ni2 D+/Ni+ , which are proportional to surface hydrogen and deuterium coverage on both clean and carbon-covered Ni(100). Between 100 and 200 K on clean Ni(l00), the initial sticking coefficient of hydrogen decreases, but only slightly, as the surface temperature increases. The decrease is more pronounced both in the presence of predosed carbon and for deuterium adsorption on Ni(100). This is interpreted as due to the involvement at low temperatures of a molecular precursor which mediates dissociative adsorption at low temperatures. The precursor probably involves surface defects and sites formed in the presence of carbon. In addition to the precursor channel, a direct dissociation channel also operates, and dominates for T≥200 K.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.456224
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  • 14
    Electronic Resource
    Electronic Resource
    Hot carrier induced photodesorption dynamics of SO2 from Ag(111) (1993)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 99 (1993), S. 10021-10033 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The photon-driven (2.5 to 6.4 eV) desorption of SO2 (coverages up to 2.7 monolayers) on Ag(111) has been studied by time-of-flight mass spectrometry in combination with temperature programmed desorption and Auger electron spectroscopy. The photodesorption yields per incident photon increase with photon energy. Consistent with substrate-mediated excitation, the mean translational energy 〈Etrans/2k〉 is constant (650 K) for photon energies between 3.5 and 6.4 eV, but decreases at longer wavelengths (480 K at 2.5 eV). The decrease is attributed to changes in the energy distribution of the hot substrate carriers responsible for desorption. The photodesorption yields vary with the initial coverage, the method of preparing the initial coverage, and the extent of photolysis. These variations are attributed, in part, to changes in the SO2 orientation on the surface. Even at 6.4 eV, where unimolecular photodissociation occurs in the gas phase and multilayer, there is no photodissociation in monolayers. This effect is attributed to strong substrate quenching.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.465506
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  • 15
    Electronic Resource
    Electronic Resource
    017
Lower Expression of P-Selectin may Modulate the Fetal Inflammatory Response: (2004)
    Oxford, UK; Malden, USA : Blackwell Science Ltd/Inc.
    Wound repair and regeneration 12 (2004), S. 0 
    Details
    ISSN: 1524-475X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Fetal dermal wound healing is characterized by a minimal inflammatory response and absence of scar. In order to determine the factors contributing to the minimal inflammatory response in the fetus, the role of P-selectin in the interaction and transmigration of leukocytes through vascular endothelium was investigated.
Methods: Primary endothelial monolayers were established from adult porcine central veins and from umbilical veins of mid-gestation porcine fetuses. The ability of the endothelial cells to capture and enable transmigration of adult leukocytes was studied under flow conditions of 4 dynes/sec, with and without prior stimulation of the endothelial cells with TNF-α or IL-1β. In addition, P-selectin mRNA expression was determined by quantitative real time PCR. All data were analyzed by ANOVA. 
Results: In response to IL-1β 10 ng/ml stimulation, adult endothelial cells manifested a 10 fold increase in P-selectin mRNA expression while fetal endothelial cells mounted only a 3.5 fold increase. 100 ng/ml was required to mount a 10 fold increase in fetal P-selectin expression while no further increase in adult P-selectin expression was noted at this dose. Leukocyte capture, demonstrated by rolling of neutrophils over the endothelial surface, was more efficient on adult monolayers compared to the fetus. This is inversely related to the rolling velocity which was significantly slower in the adult (5.3 ± 0.6 vs 12.4 ± 1.0 μm/mm2). Ultimately, the number of neutrophils transmigrating across adult endothelial monolayers under flow conditions was significantly higher compared to the fetal monolayer (199 ± 18 vs 72 ± 9 cells/mm2).
Conclusion: Lower P-selectin expression on fetal endothelial cells may account, in part, for the minimal inflammatory response noted following fetal dermal injury.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1067-1927.2004.0abstractxr.x
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  • 16
    Electronic Resource
    Electronic Resource
    Characterization of Two [3H]Ketanserin Recognition Sites in Rat Striatum (1987)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 49 (1987), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Two [3H]ketanserin recognition sites are present in the rat striatum. The high-affinity site (Kd, 0.39 nM) is similar to the 5-hydroxytryptamine2 (5-HT2) site previously characterized by various investigators. The low-affinity site (Kd, 21.8 nM) has a unique pharmacologic specificity and is preferentially localized to rat striatum and septum. Conventional 5-HT2 antagonists as well as 5-HT and 5-HT uptake inhibitors are ineffective at inhibiting [3H]ketanserin binding to this low-affinity site. Also, chronic treatment with p-chlorophenylalanine, which depletes brain 5-HT, upregulates only the high-affinity site. Thus, in the striatum and septum, [3H]ketanserin labels a unique recognition site. This site has recently been shown to be associated with dopaminergic nerve endings and may regulate biogenic amine release.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1987.tb02444.x
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  • 17
    Electronic Resource
    Electronic Resource
    HLA-DR and DQ polymorphisms in bullous pemphigoid from northern China (2002)
    Oxford, UK : Blackwell Science Ltd
    Clinical and experimental dermatology 27 (2002), S. 0 
    Details
    ISSN: 1365-2230
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Summary Bullous pemphigoid (BP) is an autoimmune disease mediated by autoantibodies against hemidesmosome components. This study used PCR–sequence-specific primers to genotype polymorphisms in HLA-DR and DQ in 25 BP patients and 57 normal controls from northern China. We found lower frequencies of DRB1*08 (DR8) and DRB1*08/DQB1*06 (DR8/DQ6) haplotypes in BP patients than in controls (4.08% vs. 15.19% and 1.54% vs. 13.82%, respectively; P 〈 0.05), suggesting a protective role for DR8 and DR8/DQ6 haplotypes in BP patients from northern China; there were no statistical differences among other alleles tested. This result is strikingly different from previous reports that DQB1*0301 is associated with BP in Caucasian patients and DRB1*1101, DQB1*0302, DRB1*04/DQA1*0301/DQB1*0302 and DRB1*1101/ DQA1*0505/DQB1*0302 with Japanese BP patients. Ethnic differences in the polymorphic composition of the HLA-DR and DQ genes may influence genetic susceptibility to BP.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2230.2002.01037.x
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  • 18
    Electronic Resource
    Electronic Resource
    A new keratin 5 mutation (K199T) in a family with Weber–Cockayne epidermolysis bullosa simplex (2004)
    Oxford, UK : Blackwell Science Ltd
    Clinical and experimental dermatology 29 (2004), S. 0 
    Details
    ISSN: 1365-2230
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: A new missense mutation in the keratin 5 gene (KRT5) in a Chinese family with Weber–Cockayne type epidermolysis bullosa simplex is reported. Direct sequencing identified a heterozygous A → C substitution at nucleotide 596 altering codon 199 of KRT5 from lysine to threonine in all affected family members, but not in the unaffected family members or in 50 unrelated control samples. The mutation is designated K199T. This mutated lysine residue is sited within the 1A domain of keratin 5 and is highly conserved among all type II keratins. The mutation may perturb the alignment of tonofilaments and, as a consequence, result in skin fragility and blistering.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2230.2004.01434.x
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  • 19
    Electronic Resource
    Electronic Resource
    Crystallization of sputtered amorphous oxide films (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 7075-7079 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Amorphous oxide films with a composition of Bi2DyFe5O12 have been prepared by rf sputtering technique. The crystallization process was investigated using x-ray diffraction, differential thermal analysis, magnetic properties, magnetic resonance spectra, magneto-optical Faraday spectra, Raman spectra, and infrared reflection spectra. Amorphous oxide films exhibit very small magnetization and Faraday rotation at room temperature. At about 600 °C amorphous films crystallize to a garnet phase. With crystallization the magnetization and Faraday rotation increase rapidly. Raman and infrared spectra studies show the presence of tetrahedral sites in the amorphous films. As the annealing temperature increases, the peaks corresponding to octahedral and dodecahedral sites occur successively. It is of interest to note that amorphous oxide films containing Fe3+ ions show no magnetic resonance spectra at 71 and 300 K. The films annealed above crystallization temperature show a normal resonance spectrum. With increasing annealing temperature the linewidth decreases rapidly and the effective magnetization and anisotropy constant increase. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.361474
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  • 20
    Electronic Resource
    Electronic Resource
    In situ monitoring of ion sputtering and thermal annealing of crystalline surfaces using an oblique-incidence optical reflectance difference method (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 2736-2738 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We demonstrate that the morphology of crystalline surfaces during ion sputtering and thermal annealing can be monitored in situ with an oblique-incidence polarization-modulated optical reflectance difference technique. Such a technique is effective under high ambient pressures as well as ultrahigh vacuum. We studied the Ne ion sputtering and thermal annealing of Ni(111) from 623 to 823 K. We found that the rate-limiting step (with an activation energy of 1.1 eV/atom) during annealing is most likely to be direct evaporation of Ni atoms from step edges. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.122574
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