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  • 1
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In order to study the basic mechanism of polarization enhancement realized by the multitilted foil technique, nuclear polarization of short-lived beta-emitter8B(T1/2=769 ms,I π=2+) was induced. Utilizing up to ten tilted foils, the polarization enhancement was measured as a function of the foil numbers. The observed enhancement for8B was combined with the previous results for12B(I π=1+,T 1/2=20 ms) which has the same atomic configurations but different nuclear spin. Analyzing these results in the framework of the classical vector model, the essential features of the enhancement depending on the nuclear spin was disclosed.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 92 (1988), S. 2390-2394 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Ferromagnetic perpendicularly magnetized epitaxial thin films of τ (Mn,Ni)Al have been successfully grown on AlAs/GaAs heterostructures by molecular beam epitaxy. We have investigated the polar Kerr rotation and magnetization of τ MnAl and (Mn,Ni)Al as a function of Mn and Ni concentration. The largest polar Kerr rotation and remnant magnetization were obtained for Mn0.5Al0.5 thin films with values of 0.16° and 224 emu/cm3, respectively. We observed that the Kerr rotation and magnetization remained constant with Ni additions up to about 12 at. % and subsequently decreased with further Ni additions. We discuss these results and one possible method of enhancing the Kerr rotation.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 97 (1992), S. 3781-3793 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Alkali–metal (K and Cs) promotion for sticking of nitrogen oxide molecule (NO) on Si(100) has been studied using a molecular beam method combined with an Auger electron spectroscopy (AES) and a laser ionization spectroscopy [resonance enhanced multiphoton ionization (REMPI)]. The observed sticking probability S shows a good correlation with alkali coverage, indicating that the alkali promotion is local in nature. The decay of S as a function of NO dose as observed with AES shows an anticorrelation with the evolution of the direct-inelastic scattering intensity as obtained with REMPI. This fact is understood as follows: since the direct-inelastic scattering occurs mostly in a single collision process with the surface, local alkali promotion is realized in a single collision of the incident NO molecule with the alkali–metal adsorbates. The decay of S as a function of NO dose is then analyzed with a reaction cross section. The evaluated reaction cross sections are close to the area of the 2×1 unit cell, and thus the estimated reaction radii are almost equal to but somewhat larger than the covalent radius of a K atom, with a increasing trend with alkali coverage. The alkali promotion is explained in terms of local electron charge transfer from the nonionized alkali adatoms to the affinity level of NO molecules based on the adatom density of state around EF.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A large semicylindrical negative ion source, whose dimensions are 34 cm in diameter and 104 cm in length, has been developed. By optimizing a chamber depth and a filter strength, a H− current of 650 mA (7.7 mA/cm2) was obtained at an arc condition of 1.3 Pa, 70 V, and 1200 A. In order to increase the H− current and to reduce an operating pressure, a small amount of Cs was injected. As a result, the H− current was increased from 550 mA (6.5 mA/cm2) to 850 mA (10 mA/cm2) under an arc power of 70 V×800 A. The most significant feature of the cesium effect was the reduction of the operating pressure. With maintaining the sufficient current of 670 mA (8 mA/cm2), the operating pressure could be lowered to 0.03 Pa. At this pressure, the highest gas efficiency of 20% was achieved.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: It is demonstrated that a cesium-seeded volume H− ion source can be operated very stably for long pulse durations of up to 24 h. The source consists of a 20 cm cylindrical multicusp plasma generator and a 9 cm × 10 cm multiaperture extractor. By seeding a small amount of cesium, the source has produced 50 keV, 0.5 A, 1000 s H− ion beams with a current density of 14 mA/cm2. The cesium effect lasted for more than 24 h once 100 mg cesium was seeded before operation. Power flow measurement revealed that the heat loading of the ion source was low enough to operate the source in the dc mode.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 5320-5325 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new interferometer has been developed for the accurate determination of the density of a silicon crystal, in which a single-crystal silicon sphere of nearly perfect geometry is placed in a Fabry–Perot etalon of accurately known plate distance, and the diameters are obtained by measuring the two gaps between the etalon and the adjacent surface of the sphere. A new method is used to measure the sum of the length of the two gaps by scanning the etalon against the sphere. Two wavelengths, 633 nm from a frequency-stabilized He–Ne laser and 441 nm from a free-running He–Cd laser, are used to determine the order of interference by applying the method of exact fractions. The diameter of about 94 mm has been measured with a resolution of 0.5 nm. Diameter measurements from uniformly distributed directions have shown that the mean diameter has been determined with a standard deviation of 8.6 nm, corresponding to 0.28 ppm in the volume determination. The total uncertainty of the volume is estimated to be 0.34 ppm. Effects of a thin oxide layer and impurities on the bulk density are discussed.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Superoxide production by cultured microglia derived from neonatal rat brains and the cytotoxicity of these cells were evaluated. The chemiluminescence (photon counts) detected in the presence of MCLA, a new chemiluminescence probe, was strongly correlated with the microglial cell count. Chemiluminescence observed in this system was confirmed to originate specifically from superoxide produced by activated microglia. Phorbol myristate acetate-stimulated microglia caused a pronounced reduction of PC12h cell numbers in coculture. The addition of superoxide dismutase with catalase or the addition of deferoxamine mesylate inhibited PC12h cell death, suggesting that active oxygen species derived from superoxide generated by the microglia or iron-oxygen complex formation were responsible for the cytotoxicity. These results imply that activated microglia may participate in the progression of the pathologic process in some neurodegenerative disorders.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 47 (1986), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract Using chicken brain mRNAs, α and γ enolase precursors were synthesized in the rabbit reticulocyte cell-free translation system. The product proteins showed molecular weights almost identical to those of the mature subunits. The levels of translatable mRNAs for α and γ subunits were determined by the cell-free translation system and immuno-precipitation with specific antisera, during development of chicken brain. The level of α mRNA was high at any developmental stage of the brain. On the other hand, the γ mRNA level was very low at the early embryonic stage, and increased rapidly during development of the brain. These changes were closely correlated with those of the corresponding enzyme activities, indicating that the levels of enolase activities in developing brain were controlled primarily by the level of the translatable α and γ mRNAs.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 885-896 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Molecular beam epitaxial (MBE) growth, structural, and electrical properties of novel epitaxial metal/semiconductor heterostructures (MSHs), consisting of monocrystalline CoAl, an intermetallic compound, and AlAs/GaAs III-V semiconductors have been studied. The CoAl with stoichiometric composition has a CsCl-type crystal structure whose lattice constant is very close to half the lattice constant of GaAs and AlAs, hence, it is a good candidate as a constituent metal in epitaxial monocrystalline metal/semiconductor heterostructures. MBE growth of CoAl thin films on AlAs/GaAs, and also semiconductor overgrowth on ultrathin CoAl films, together with structural characterizations by in situ reflection high energy electron diffractions, ex situ x-ray diffractions and cross sectional transmission electron microscopy have been explored. By optimizing the growth parameters and procedures, high quality monocrystalline CoAl/AlAs/GaAs heterostructures with atomically abrupt interfaces have been successfully grown. Furthermore, the electrical properties of such novel heterostructures as Schottky barrier heights of CoAl/AlAs/GaAs MSHs and transport properties in ultrathin buried CoAl films are described.
    Type of Medium: Electronic Resource
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