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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 1871-1874 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Spectral properties of blue upconversion luminescences in Tm3+ doped tellurite (PWT, PbF2-WO3-TeO2) glasses and germanate (PWG, PbF2-WO3-GeO2) glasses pumped by a tunable dye laser were studied at room temperature. Two emission bands centered at 453 and 477 nm, corresponding to the 1D2→3H4 and 1G4→3H6 transitions of Tm3+ ions respectively, were observed. The two-photon absorption mechanism responsible for the 477 nm luminescence was confirmed by a quadratic dependence of luminescent intensities on the excitation power. Tellurite glasses showed a weaker upconversion luminescence than germanate glasses. This observation was inconsistent with the prediction from the phonon sideband measurement. In this article, Raman spectroscopy and transmittance measurement were employed to investigate the origin of the difference in upconversion luminescences in the two glasses. Compared with phonon sideband spectroscopy, Raman spectroscopy extracts more information, including both phonon energy and phonon density, and therefore, is a more effective analytical tool for understanding upconversion luminescence. Our results showed that the phonon energy as well as phonon density of the host glass is important in determining the upconversion efficiency. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on a study of interfacial structure of GaN films grown on GaAs(001) substrates by plasma-assisted molecular beam epitaxy using x-ray grazing-angle specular reflection. We show that interfacial layers with electron densities differing from those of GaN and GaAs were formed upon deposition of GaN. It is also found that the interfacial structure of our systems depends strongly on the course of the initial layer deposition. The phase purity of the GaN films was examined by x-ray reciprocal space mapping. A simple kinetic growth model suggested by our results has been presented. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 70 (1997), S. 1965-1967 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Textured (100) diamond films are successfully grown on single-crystalline (100) silicon substrate by electron assisted hot filament chemical vapor deposition from a gas mixture of methane and hydrogen. The effects of various parameters have been studied. The optimal growth conditions are obtained and the oriental growth character is discussed. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 5003-5005 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Changes in electrical resistance of germanium were investigated during melting and cooling under high pressure. It was found that the electrical resistances of the samples dropped abruptly at an early stage of the solidification above ∼4 GPa. This result shows a metallic liquid to metallic solid transition of germanium when cooling above ∼4 GPa as compared to a metallic liquid to nonmetallic solid transition at pressures below ∼4 GPa. The mechanism of the phase evolution in the solidification process of germanium at high pressures is briefly discussed. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 2412-2414 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on the intentional n-type doping of the diluted magnetic semiconductor Zn1−xMnxSe using ZnCl2 as the dopant source. Samples with varying Mn concentrations and carrier densities were grown by molecular beam epitaxy and characterized using Hall effect, x-ray diffraction, and photoluminescence measurements. Net carrier concentrations in excess of 1018 cm−3 are readily obtained for x≤0.08. Useful carrier densities can be achieved for Mn concentrations x≤0.15, above which the samples are highly insulating. The controlled doping of this alloy provides another material for use in the fabrication of wide gap semiconductor device structures. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 68 (1996), S. 2270-2272 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The epitaxial growth of the diluted magnetic semiconductor (DMS) Zn1−xFexSe (0〈x≤0.22) by metalorganic vapor phase epitaxy (MOVPE) is reported. The films were grown on (100) GaAs substrates in a vertical stagnation flow reactor with a specially designed inlet to minimize prereactions between the groups II and VI precursors. The precursors used in this study were (CH3)2Zn:N(CH2H5)3, Fe(CO)5, and H2Se diluted in H2 carrier gas. The epilayers were characterized by x-ray diffraction (XRD), Raman, absorption, and x-ray photoelectron spectroscopies (XPS). Typical growth rates were from 3–4 μm/h, which are significantly higher than those obtained by molecular beam epitaxy. Thus, in addition to the growth of DMS multilayer structures, MOVPE appears to be very promising for efficient growth of thick DMS films for Faraday magneto-optical applications. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 75 (1999), S. 4112-4114 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Porous silicon is excited using near-infrared femtosecond pulsed and continuous wave radiation at an average intensity of ∼106 W/cm2 (8×1010 W/cm2 peak intensity in pulsed mode). Our results demonstrate the presence of micron-size regions for which the intensity of the photoluminescence has a highly nonlinear threshold, rising by several orders of magnitude near this incident intensity for both the pulsed and continuous wave cases. These results are discussed in terms of stimulated emission from quantum confinement engineered intrinsic Si–Si radiative traps in ultrasmall nanocrystallites, populated following two-photon absorption. © 1999 American Institute of Physics.
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Alimentary pharmacology & therapeutics 19 (2004), S. 0 
    ISSN: 1365-2036
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background : Patients undergoing transarterial chemoembolization for hepatocellular carcinoma have advanced tumour or severe cirrhosis and frequently have associated protein-calorie malnutrition. The role of nutritional supplements for such patients is unclear.Aim : To investigate, in a randomized controlled trial, any benefit of the long-term administration of branched chain amino acids in patients undergoing chemoembolization for hepatocellular carcinoma.Methods : Forty-one patients received oral branched chain amino acids for up to four courses of chemoembolization and 43 patients did not receive any nutritional supplement. Morbidity, liver function, nutritional status, quality of life and long-term survival were compared between the two groups.Results : The administration of branched chain amino acids resulted in a lower morbidity rate compared with the control group (17.1% vs. 37.2%, P = 0.039). In particular, the group given branched chain amino acids showed a significantly lower rate of ascites (7.3% vs. 23.2%, P = 0.043) and peripheral oedema (9.8% vs. 27.9%, P = 0.034). Significantly higher serum albumin, lower bilirubin and a better quality of life were observed after chemoembolization in the group given branched chain amino acids. However, there was no significant difference in survival between the two groups.Conclusions : Nutritional supplementation with oral branched chain amino acids is beneficial in increasing the serum albumin level, reducing the morbidity and improving the quality of life in patients undergoing chemoembolization for inoperable hepatocellular carcinoma.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 52 (1996), S. 2274-2277 
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 54 (1998), S. 11-12 
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
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