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  • 1
    Electronic Resource
    Electronic Resource
    A simple apparatus for determining column density and absolute photoabsorption cross sections (2000)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 71 (2000), S. 1564-1568 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: This article presents a simple measuring apparatus that is capable of measuring column density and absolute photoabsorption cross sections. The apparatus includes a simple high-temperature heatpipe furnace, an MKS Instruments Baratron, a hydrogen discharge lamp, and an optical detecting system. The heatpipe furnace provides an absorbing medium with a steady total pressure in a closed system so that the column density can be obtained using the ideal gas relation. The apparatus is designed for a working temperature range below 1000 K and a pressure range up to 10 Torr. Encountered experimental difficulties and their found solutions will be discussed in detail. In this work, the absolute photoabsorption cross section of Mg is measured near the 3s threshold using this apparatus. The absolute photoabsorption cross section result at the 3s threshold, which is 2.1±0.3 Mb, is in good agreement with hook method data (2.36 Mb). © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1150494
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  • 2
    Electronic Resource
    Electronic Resource
    Midinfrared photoluminescence from IV–VI semiconductors grown on silicon (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 3514-3516 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Above room temperature continuous wave midinfrared photoluminescence has been observed from PbSe/Pb1−xSrxSe multiple quantum well structures grown by molecular beam epitaxy on (111) silicon. Emission energy from a sample with 10-nm-thick quantum wells varied from 336.1 to 343.7 meV as sample temperature was increased from 15 to 35 °C. At a heat sink temperature of 25 °C the emission energy varied from 336.8 to 339.9 meV as the current in the near-infrared diode pump laser was increased from 300 to 800 mA indicating an additional 8.2 °C of epilayer heating due to increased photon flux from the pump laser. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1347950
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  • 3
    Electronic Resource
    Electronic Resource
    Onset of Asian desertification by 22 Myr ago inferred from loess deposits in China (2002)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 416 (2002), S. 159-163 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The initial desertification in the Asian interior is thought to be one of the most prominent climate changes in the Northern Hemisphere during the Cenozoic era. But the dating of this transition is uncertain, partly because desert sediments are usually scattered, discontinuous and difficult to ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/416159a
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  • 4
    Electronic Resource
    Electronic Resource
    Microwave dielectric properties of strained (Ba0.4Sr0.6)TiO3 thin films (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 5448-5451 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Ferroelectric Ba0.4Sr0.6TiO3 (BST) thin films grown on (001) MgO by pulsed laser deposition show a strong correlation between their structure and their microwave dielectric properties. Epitaxially grown BST films are observed by x-ray diffraction to be tetragonally distorted. The oxygen deposition pressure affects the magnitude of the tetragonal distortion (the ratio of in-plane and surface normal lattice parameters, D=a/c) of the deposited BST films. D varied from 0.996 to 1.004 at oxygen deposition pressure of 10–800 mTorr. The dielectric properties of BST films measured at microwave frequencies (1–20 GHz) exhibit an oxygen deposition pressure dependent dielectric constant (ε=100–600), and quality factor Q (1/tan δ=10–60). The BST film grown at the oxygen deposition pressure of 200 mTorr exhibits the highest figure of merit [% tuning in ε×Q0V, where % tuning is 100×(ε0−εb)/ε0, and ε0 and εb are dielectric constant at 0 and 80 kV/cm]. This corresponds to the film with the lowest distortion (D=1.001). The observed microwave properties of the films are explained by a phenomenological thermodynamic theory based on the strain along in-plane direction of the films. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1314619
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  • 5
    Electronic Resource
    Electronic Resource
    Unambiguous observation of subband transitions from longitudinal valley and oblique valleys in IV–VI multiple quantum wells (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 78 (2001), S. 2199-2201 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: PbSe/PbSrSe multiple-quantum-well (MQW) structures were grown on BaF2(111) substrates by molecular-beam epitaxy and characterized by Fourier transform infrared transmission spectroscopy. To reduce unwanted Fabry–Pérot interference fringes, the top surface of the MQW samples was coated with an anti-interference film, enabling clear observation of subband transitions without superposed interference fringes. Transition energies involving longitudinal and oblique valleys were unambiguously resolved and are in good agreement with calculations made using the envelope wave function approximation. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1361104
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  • 6
    Electronic Resource
    Electronic Resource
    Above-room-temperature optically pumped 4.12 μm midinfrared vertical-cavity surface-emitting lasers (2002)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 80 (2002), S. 1129-1131 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Optically pumped lead salt vertical-cavity surface-emitting lasers (VCSELs) with a nine period PbSe/PbSrSe quantum well active region operating above room temperature in pulsed mode are reported. The gain peak and cavity mode of the VCSEL structure are in resonance at 300 K. A power output of 40 mW is obtained at room temperature and it does not show saturation. The room-temperature threshold pump density is 200 kW/cm2. The lasing wavelength of λ=4.12 μm remains nearly constant over a temperature range of 280–310 K. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1449540
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  • 7
    Electronic Resource
    Electronic Resource
    Quantum-confined magneto-Stark effect in diluted magnetic semiconductor coupled quantum wells (2002)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 80 (2002), S. 1788-1790 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The magneto-Stark effect in a diluted magnetic semiconductor (DMS) coupled quantum well (CQW) induced by an in-plane magnetic field is investigate theoretically. Unlike the usual electro-Stark effects, in a DMS CQW the Lorenz force leads to a spatially separated exciton. The in-plane magnetic field can shift the ground state of the magnetoexciton from a zero in-plane center of mass (CM)/momentum to a finite CM momentum, and render the ground state of magnetoexciton stable against radiative recombination due to momentum conservation. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1459491
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  • 8
    Electronic Resource
    Electronic Resource
    Lower-dose 13C-urea breath test to detect Helicobacter pylori infection—comparison between infrared spectrometer and mass spectrometry analysis (2000)
    Oxford UK : Blackwell Science Ltd
    Alimentary pharmacology & therapeutics 14 (2000), S. 0 
    Details
    ISSN: 1365-2036
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The expense of the 13C-urea breath test (UBT) to detect Helicobacter pylori infection is mainly due to the cost of 13C-urea and the analysis using isotope ratio mass spectrometry (IRMS).〈section xml:id="abs1-2"〉〈title type="main"〉Aim:To test whether a UBT, using a lower dose of urea and lower-priced isotope-selective nondispersive infrared spectrometry (INIS), can preserve diagnostic efficacy in clinical practice.〈section xml:id="abs1-3"〉〈title type="main"〉Methods:A total of 177 dyspeptic patients received endoscopy for H. pylori culture and histology. All of them received a UBT in which the duplicate baseline, 10 min, and 15 min breath samples after ingestion of 50 mg 13C-urea were collected to analyse the excess 13CO2/12CO2 ratio (ECR) by IRMS (ABCA, Europa Scientific, UK) and INIS (UBiT-IR200, Photal Otsuka Electronics, Japan), respectively.〈section xml:id="abs1-4"〉〈title type="main"〉Results:Of the 177 patients, 84 were infected and 93 were uninfected with H. pylori. A close correlation of ECR was found between IRMS and INIS (r=0.9829 at 10 min; r=0.9918 at 15 min, P 〈 0.0001). Analysing the 15-min samples, UBT by both IRMS and INIS achieved the same sensitivity (96.4%) and specificity (98.9%).〈section xml:id="abs1-5"〉〈title type="main"〉Conclusions:INIS is as effective as IRMS for UBT, and can use a lower dose of 13C-urea. This can provide an economic UBT, using the lower-priced INIS and a low dose of 13C-urea.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2036.2000.00848.x
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  • 9
    Electronic Resource
    Electronic Resource
    Impact of supplement with Lactobacillus- and Bifidobacterium-containing yogurt on triple therapy for Helicobacter pylori eradication (2002)
    Oxford, UK : Blackwell Science Ltd
    Alimentary pharmacology & therapeutics 16 (2002), S. 0 
    Details
    ISSN: 1365-2036
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Aim : To test whether supplements of Lactobacillus- and Bifidobacterium-containing yogurt (AB-Yogurt) affect the success of Helicobacter pylori eradication.Methods : One hundred and sixty H. pylori-infected patients were randomized into a triple-plus-yogurt group or a triple-only group, receiving 1 week of triple therapy with and without supplements of AB-Yogurt, respectively. In the triple-plus-yogurt group, AB-Yogurt was continued for 4 weeks after triple therapy. Eight weeks later, patients were assessed for the success of H. pylori eradication. The stool samples of 22 randomly selected patients, 11 from each group, were provided on enrolment, at the first week and at the fifth week for evaluation of the percentage of Bifidobacterium in anaerobes.Results : By intention-to-treat analysis, the triple-plus-yogurt group had a higher H. pylori eradication rate than the triple-only group (91% vs. 78%, P 〈 0.05). The per protocol H. pylori eradication rates were similar for both groups (93.5% vs. 89%, P = N.S.). Only patients supplemented with AB-Yogurt showed restoration of the percentage of Bifidobacterium in the anaerobes of stools at the fifth week to the level in the stools on enrolment.Conclusions : Supplement with AB-Yogurt can improve the intention-to-treat eradication rates of H. pylori, and can restore the depletion of Bifidobacterium in stools after triple therapy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2036.2002.01335.x
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  • 10
    Electronic Resource
    Electronic Resource
    Effects of antioxidants on pyridinoline cross-link formation in culture supernatants of fibroblasts from normal skin and hypertrophic scars (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 Free radicals are normally generated in many metabolic pathways. They are closely associated with inflammatory diseases. The aim of this study was to investigate the effects of free radicals and their antioxidants on the formation of pyridinoline using human fibroblasts from normal skin and hypertrophic scars. The significance of the increase in pyridinoline cross-links is that large quantities have been found in hypertrophic scars formed post-burn than in normal skin, and that catalase was effective in reducing the pyridinoline cross-link formation in hypertrophic scars. The pyridinoline cross-link concentration expressed in nM/µg hydroxyl proline was found to be higher in the culture supernatants of the fibroblasts from hypertrophic scars (9.04 ± 2.74) than that of normal skin (7.55 ± 2.1). When the human fibroblasts from normal skin and hypertrophic scar were subject to hydroxyl radicals generated by the Fenton reaction, there was no significant increase in pyridinoline cross-link concentration (nm/µg hydroxyl proline) in the supernatants compared with the control. When the controls plus various treatments with free radicals were subject to different antioxidants, including superoxide dismutase, catalase, glutathione peroxidase, and desferrioxamine, it was found that catalase alone was most effective in scavenging hydroxyl radicals as determined by the decrease in pyridinoline cross-links.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2230.2002.01096.x
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