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  • 1
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We have grown ZnCdSe/ZnSSe/ZnMgSSe separate confinement heterostructures by molecular-beam epitaxy. Strain on the ZnSSe layer is calculated from x-ray and photoluminescence data. The temperature dependence of band-gap energy and the photoluminescence intensity in the Cl-doped ZnCdSe active layers is compared with that of undoped ones. © 1996 American Institute of Physics.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 2036-2038 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Epitaxial [Co/Cu]10 grown on Si (001) has been irradiated by 1 MeV C+ with a dose of 1×1016/cm2. The intrinsic characteristics of epitaxy, such as crystal structure and fourfold magnetic anisotropy, are conserved after ion irradiation. However, the extrinsic magnetic properties are changed such that the coercivity decreases and the squareness of the hysteresis loop is noticeably improved. The intensity of the Cu (200) peak in the x-ray diffraction pattern increases about three times and its half-width decreases after irradiation. It is concluded that the changes of magnetic properties induced by ion irradiation result from the grain growth and the improved crystalline quality. © 2001 American Institute of Physics.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 84 (1998), S. 3125-3128 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Photoluminescence (PL) and Raman scattering measurements have been carried out to investigate the hydrogenation and annealing effects in p-type ZnSe epilayers grown on n-type GaAs (100) substrates by molecular beam epitaxy. After hydrogenation, the PL spectra showed that the deep acceptor-bound exciton peak disappeared and that the peak position of the donor–acceptor pair peak shifted to a higher energy. When the hydrogenated ZnSe/GaAs heterostructure was annealed at 300 °, a bound exciton due to neutral acceptors appeared. The Raman intensity of the plasma longitudinal optical-phonon-coupling mode increased after hydrogenation. These results indicate that the crystallinity of the p-type ZnSe epilayers grown on n-type GaAs substrates is improved by hydrogenation and that hydrogenated and annealed ZnSe films grown on GaAs substrates hold promise for potential application as buffer layers for the growth of Zn1−xMgxSySe1−y active layers. © 1998 American Institute of Physics.
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  • 4
    Digitale Medien
    Digitale Medien
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 80 (2002), S. 2296-2298 
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Three mechanisms for the formation of Cu diffusion channels in the Ta layer of a Cu/Ta/SiO2/Si structure are proposed. First, it is suggested that stacking faults formed during the recovery process induce localized regions of high internal energy in the Ta layer, from which Cu channels originate. Second, chemical reaction occurs at 800 °C and forms Ta4CuO11 across the Cu/Ta interface in Cu and Ta layers, which opens up channels for Cu diffusion. Third, triple junctions at the grain boundary of the Cu and Cu/Ta interface provide sites for the initiation of channel formation at 800 °C. At 950 °C, these channels in the diffusion barrier are absent, but Ta was oxidized into disordered Ta2O5 that may contain pathways for Cu diffusion. © 2002 American Institute of Physics.
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  • 5
    Digitale Medien
    Digitale Medien
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 71 (1997), S. 2851-2853 
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We fabricated a homeotropically aligned nematic liquid crystal display with positive dielectric anisotropy, whose on and off states are controlled by in-plane field. The rubbing-free device, dark in voltage-off state, reveals bright uniformity in all directions due to the dual domainlike director configuration in the voltage-on state. The electro-optic characteristics of one prototype with excellent viewing angles are reported herein. © 1997 American Institute of Physics.
    Materialart: Digitale Medien
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  • 6
    ISSN: 1398-9995
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Background:  Allergy is regarded as a multifactorial condition. Its onset and severity are influenced by both genetic and environmental factors. Identification of genetic factors involved in asthma development and related phenotypes is a major task in understanding the genetic background of asthma. The possible involvement of IL18 polymorphisms in asthma was examined in a Korean asthma cohort.Methods:  Direct sequencing was performed to discover single-nucleotide polymorphisms (SNPs) in the IL18 gene. Single-base extension (SBE) method was employed for genotyping. Genotypic influence of IL18 was analysed using logistic and multiple-regression models.Results:  Although no polymorphisms in the IL18 gene showed significant association with the risk of asthma development, analyses of the association with specific serum IgE levels to Dermatophagoides farinae (D.f.) and D. pteronyssinus (D.p.) among asthmatic patients revealed significant associations with two completely linked SNPs, i.e. −148G〉C and +13925A〉C(Ser35Ser) (P = 0.01–0.11 for D.f. and P = 0.005–0.11 for D.p.). Both C allele of −148G〉C and C allele of +13925A〉C showed gene dose-dependent effects on the levels of specific IgE. The lowest IgE levels in homozygotes of minor alleles (1.13 and 1.22 of D.f.; 1.38 and 1.33 of D.p., respectively), intermediate IgE levels in heterozygotes (1.60 and 1.70 of D.f.; 1.84 and 1.92 of D.p., respectively), and the highest levels in homozygotes for major allele (1.93 and 1.93 of D.f.; 2.24 and 2.24 of D.p., respectively), were found.Conclusion:  The genetic relevance of IL18 to specific IgE might offer an important step in understanding the genetic background of allergic diseases.
    Materialart: Digitale Medien
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  • 7
    ISSN: 1398-9995
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Background:  5-Lipooxygenase (ALOX5) and 5-lipoxygenase-activating protein (ALOX5AP) are known as key enzymes in cysteinyl-leukotriene (cys-LT) production, critical mediators in aspirin acetylsalicyclic acid (ASA)-intolerant asthma (AIA). To date, studies of the promoter region of ALOX5 gene has revealed the potential influence of a variable number of tandem repeats of a Sp1- and Egr1-binding motif, on the transcription rate.Methods:  To understand the pathological process that arises from cys-LT overproduction in AIA, we genotyped ALOX5 Sp1 and ALOX5AP poly(A) repeat promoter polymorphism by fluorescent-based capillary electrophoresis in the Korean population.Results:  No significant differences in allele and genotype frequencies of the ALOX5 and ALOX5AP promoter polymorphisms were observed between the three groups. However, there was a strong association of the ALOX5 Sp1 repeat polymorphism with airway hyperresponsiveness (AHR; PC20 methacholine); AIA patients carrying a mutant allele (n 〉 5 or n 〈 5 repeats) showed increased AHR compared to AIA patients with wild-type genotype (P = 0.003).Conclusion:  Although the alleles of the ALOX5 and ALOX5AP promoter cannot be considered as a prominent risk factor in the development of AIA, the genetic variant of tandem repeat (GGGCGG; Sp1-binding motif) in ALOX5 promoter is associated with the severity of airway hyperresponsiveness in AIA patients.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Clinical & experimental allergy 26 (1996), S. 0 
    ISSN: 1365-2222
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Background There have been very few reports of occupationai allergies caused by inhalation of buckwheat flour. In this paper, we present a case of occupational asthma and rhinitis caused by buckwheat flour inhalation.Methods and results The patient had strong positive responses to grass and ragweed poiiens as well. The bronchoprovocation test showed early asthmatic response to buckwheat flour extracts. Serum specific IgE antibody to buckwheat flour was detected by enzyme-linked immunosorbent assay (ELISA). In order to further identify the allergenic component of the extracts, sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and electroblotting studies were performed. Eight IgE binding components (9–55 kDa) were detected within the buckwheat flour extracts.Conclusion These results suggest that inhalation of buckwheat flour can caused IgE mediated bronchoconstriction.
    Materialart: Digitale Medien
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  • 9
    ISSN: 1365-2222
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Background Urticaria/angioedema is a common aspirin-induced allergy; however, its pathogenic mechanism is not understood.Objective In order to uncover the genetic mechanism, we studied the associations of the human leucocyte antigen (HLA) genotypes in patients with aspirin-induced urticaria compared with aspirin-intolerant asthma and normal control in a Korean population.Methods Ninety-four aspirin-induced urticaria patients presenting urticaria/angioedema-induced by both ASA and NSAID (50 had underlying chronic urticaria) and showing positive responses on oral aspirin challenge test, 76 aspirin-intolerant asthmatics with positive responses on lysine–aspirin bronchoprovocation test, and 185 normal healthy controls were enrolled. HLA-DRB1, DQB1, and DPB1 genotypings were performed by direct DNA sequencing analysis.Results The allele frequencies of HLA-DRB1*1302 (18.1%) and HLA-DQB1*0609 (10.1%) in aspirin-induced urticaria were significantly higher than in aspirin-intolerant asthma (5.3%, P=0.0004; 2.0%, P=0.0024) and in normal controls (8.1%, P=0.0005; 3.2%, P=0.0008), and they remained significant after correcting for multiple comparisons. The patients with these two HLA markers had a significantly younger age than patients without, while no associations were found in with respect to atopic status, a history of previous allergic diseases, total IgE level, or presence of underlying chronic urticaria (P〉0.05, respectively). In haplotype analysis, the HLA-DRB1*1302-DQB1*0609-DPB1*0201 was significantly higher in the aspirin-induced urticaria (8.0%) than in the aspirin-intolerant asthma (0.7%, P=0.0014) and normal controls (2.0%, P=0.0006).Conclusion These findings suggest that the HLA-DRB1*1302-DQB1*0609-DPB1*0201 may be a strong genetic marker to determine the aspirin-induced urticaria phenotype.
    Materialart: Digitale Medien
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  • 10
    ISSN: 1365-2222
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Background and objective Persistent asthma symptoms are associated with airway inflammation and remodeling, which may be mediated through metalloproteinase (MMP) and tissue inhibitor of metalloproteinase (TIMP). The aim of this study was to evaluate MMPs and TIMP involvement in toluene diisocyanate (TDI)-induced asthma.Materials and method Induced sputum was collected in eight newly diagnosed TDI-induced asthma subjects (group I) before and 7 h after the TDI and placebo challenges and in 12 subjects with TDI-induced occupational asthma diagnosed 5 years previously with persistent asthma symptoms (group II). Sera was collected in group I at diagnosis, and in group II, they were collected at the time of the study. 12 nonasthmatic healthy subjects were enrolled as controls. MMP-9, MMP-2 and TIMP-1 levels in both sputum and serum were measured by enzyme-linked immunosorbent assay (ELISA). Gelatinase activity in the sputum was confirmed by zymographic analysis.Results The serum TIMP-1 level was significantly higher in asthma patients than in healthy controls (P = 0.01), while MMP-9 level was significantly lower in asthmatic patients (P = 0.03). There was no significant difference in MMP-2 level (P = 0.27). MMP-9 level in the sputum was significantly increased after the TDI challenges (P = 0.01). TIMP-1 level in sputum tended to increase after TDI challenges, but no statistical significance was noted (P = 0.09). MMP-9 and MMP-9/TIMP-1 levels in the sputum were significantly higher in group II than in group I (P = 0.04, P = 0.02) with no significant difference in TIMP-1 level. Minimal amount of MMP-2 was found in sputum. Zymography demonstrated that MMP-9 level increased and active form of MMP-9 was generated after the TDI bronchoprovocation test.Conclusion TDI exposure leads to overproduction of MMP-9, which may induce airway inflammation and remodeling, and then contribute to persistent asthmatic symptoms in TDI-induced asthma.
    Materialart: Digitale Medien
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