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  • 1
    Digitale Medien
    Digitale Medien
    Magnetic properties of ultrafine nickel particles : The 5th Joint MMM−Intermag Conference (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 5903-5905 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Ultrafine nickel particles have intriguing physical and chemical properties, which are interesting both in fundamental and applied research. The size of the particle was controlled by gas pressure. X-ray diffraction studies showed that fine Ni particles have fcc crystal structure and are coated with thin Ni oxide on the surface. Electron micrographs showed a spherical particle shape, forming a long chain. Size dependence of magnetic properties were studied. The specific magnetic moment drastically decreases when reducing the diameter d of particles 〈15 nm. The coercivity Hc also approaches zero when d is about 15 nm. Therefore, we can suppose that the critical size for superparamagnetism at room temperature is about 15 nm. According to the superparamagnetic formula KV=25 kT, the value of the magnetic anisotropy constant can be determined, K = −5.8 × 105 (erg/cc). It is found to be larger than bulk Ni [K=−3.4–5.1 × 104 (erg/cc)], the same as Fe particles. The maximum of coercivity at room temperature is about 250 Oe, that is less than the theory value for the coherent rotation model, Hc = 4 K/3Ms=1600 Oe. The mechanism of reversal magnetization can be understood by the sphere chain model. The critical diameter of the single domain is about 65 nm. Curie temperature Tc obviously decreases for 9-nm average diameter particles rather than bulk. It may be in connection with the lattice contraction.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.350101
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  • 2
    Digitale Medien
    Digitale Medien
    Effects of oxygen on the melting and freezing of Bi2Sr2Ca1Cu2O8+δ (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 7397-7401 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Crystallization of Bi2Sr2Ca1Cu2O8+δ has been studied as a function of the partial pressure of oxygen, using in situ high temperature x-ray measurements, in order to determine the phases that form and the kinetics of growth. As the partial pressure of oxygen is systematically reduced, the dominant second phase changes from (Sr,Ca)2Cu1O3 at 150 Torr of oxygen, to (Sr,Ca)1Cu1O2 at 15 Torr of oxygen, to CaO in a pure nitrogen atmosphere. Normally, in 150 Torr of oxygen, Bi2Sr2Cu1O6+δ is the first Bi cuprate to form from the melt but if the oxygen partial pressure is reduced to 75 Torr, then Bi2Sr2Ca1Cu2O8+δ is favored due to the decreased amount of 2:1 phase in the melt.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.355009
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  • 3
    Digitale Medien
    Digitale Medien
    Transport critical current density and microstructure in extruded YBa2Cu3O7−x wires processed by zone melting (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 228-232 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: YBa2Cu3O7−x compounds were extruded into long wires with the diameter of 1 mm after sintering. The sintered wires were subsequently zone melted to develop a highly textured microstructure. Magnetization experiments at 77 K indicated a Jc value of 1×105 A/cm2 at 1 T. Transport measurements at 77 K showed a greatly enhanced field dependence of the critical current density. Transmission electron microscopy revealed an important grain-boundary feature which eliminated the weak-link behavior. Large amounts of dislocations have also been found in the zone-melted sample which may contribute to flux pinning in the system.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.347122
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  • 4
    Digitale Medien
    Digitale Medien
    Relation between microstructures and magnetic properties upon annealing in Fe50Mn50/Ni80Fe20 films (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 92 (2002), S. 2052-2057 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The annealing-temperature-dependent change in the exchange bias and coercivity is investigated in Fe50Mn50/Ni80Fe20 films. It is interesting to note that, as the annealing temperature increases, the exchange bias first decreases, and then increases, and finally decreases for the case of annealing at the higher temperature. The coercivity will increase upon annealing at moderate temperature, but decrease upon higher-temperature annealing. We can qualitatively interpret the change of the magnetic properties with annealing temperature in connection to the microstructures by x-ray scattering technologies. The results show that both the large exchange bias field and low coercivity of Fe50Mn50/Ni80Fe20 films are dependent of not only the interfacial roughness but also the antiferromagnetic structure. © 2002 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1493653
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  • 5
    Digitale Medien
    Digitale Medien
    The dopamine D1 receptor is a critical mediator for cocaine-induced gene expression (2002)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 82 (2002), S. 0 
    Details
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: The dopamine D1 receptor plays a major role in mediating behavioral responses to cocaine administration. The time course for the acquisition and the relative stability for the expression of behavioral responses suggest the involvement of enduring neuroadaptations in response to repeated cocaine exposure. Changes in gene expression through the D1 receptors may accompany and mediate the development of such neuroadaptations to repeated cocaine stimulation. To test this possibility, we systematically compared the expression of the fos and Jun family immediate early genes in the nucleus accumbens and caudoputamen in D1 receptor mutant and wild-type control mice after acute and repeated cocaine exposure. Moreover, we compared the expression of three molecules that have been implicated in mediating the actions of cocaine, Gαolf, β-catenin and brain-derived neurotrophic factor, in the two groups of mice before and after cocaine administration. We found that there is a lack of induction of c-Fos, FosB, Fra-2 and JunB by acute cocaine exposure, and of ΔFosB by repeated cocaine administration in both the NAc and CPu of D1 receptor mutant mice compared with wild-type control mice. Moreover, the D1 receptor is differentially required for mediating Gαolf, β-catenin and BDNF expression in the NAc and CPu upon cocaine exposure. These results suggest that the D1 receptor is a critical mediator for cocaine-induced expression of these genes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1471-4159.2002.01089.x
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  • 6
    Digitale Medien
    Digitale Medien
    Decomposition products of superconducting (Bi,Pb)2Sr2Ca2Cu3O10+δ (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 1111-1115 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: High-temperature in situ x-ray studies of Pb-doped Bi2Sr2Ca2Cu3O10+δ have been carried out in a variety of different environments in order to determine the range of stability and the decomposition products that appear as this material transforms into other phases. In air at 840 °C, a combination of Bi2Sr2Ca0Cu1O6+δ, Ca2PbO4, (Sr,Ca)2Cu1O3, and some liquid phase coexists with Bi2Sr2Ca2Cu3O10+δ as it gradually decomposes. When the Bi2Sr2Ca2Cu3O10+δ is completely gone, the Bi2Sr2Ca0Cu1O6+δ, Ca2PbO4, and (Sr,Ca)2Cu1O3 transform to a liquid with CaO and other phases floating on the liquid. If Ag is micromilled with the Bi2Sr2Ca2Cu3O10+δ, the decomposition process is similar, but all of the temperatures are lowered substantially. If the partial pressure of O2 is reduced to 10 kPa over the Bi2Sr2Ca2Cu3O10+δ/Ag sample, the decomposition temperatures and products are similar to the 20 kPa case.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.357831
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  • 7
    Digitale Medien
    Digitale Medien
    Intermediate phases produced in growth of Bi2Sr2Ca2Cu3O10+δ (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 360-363 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: High-temperature in situ x-ray measurements have been undertaken during the growth of Bi2Sr2Ca2Cu3O10+δ in order to determine the sequence of phases that form and the kinetics of growth. With a Ag-coated thin pellet of the starting mixture of Pb-doped Bi2Sr2Ca1Cu2O8+δ, Ca-cuprates, and CuO in an air atmosphere, major changes occur in the x-ray spectrum at temperatures as low as 790 °C. A triplet of lines associated with Ca2PbO4 forms as soon as the pellet reaches 790 °C and then disappears after 20 or 30 minutes. The Bi2Sr2Ca2Cu3O10+δ phase begins to grow at about 810 °C. For these rather porous pellets, about 20% of the sample transforms to Bi2Sr2Ca2Cu3O10+δ, as indicated by both x-ray intensities and superconducting magnetization studies. © 1995 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.360610
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  • 8
    Digitale Medien
    Digitale Medien
    High critical current density in grain-oriented bulk YBa2Cu3Ox processed by partial melt growth (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 57 (1990), S. 2606-2608 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: A uniform grain-oriented microstructure was developed in 50-mm-long bar samples of bulk YBa2Cu3Ox prepared by a partial melt growth process. In sharp contrast to previous reports, the textured products contained only small amounts of second phases. The samples were dense and nearly free of porosity. Transport measurements showed that the textured samples could carry a critical current density greater than 4.4×104 A/cm2 at 77 K and 1.8 T. The possible effects of processing parameters on the superconducting properties of the tested materials are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.104188
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  • 9
    Digitale Medien
    Digitale Medien
    Protein Splicing: Characterization of the Aminosuccinimide Residue at the Carboxyl Terminus of the Excised Intervening Sequence (1995)
    s.l. : American Chemical Society
    Biochemistry 34 (1995), S. 10844-10850 
    Details
    ISSN: 1520-4995
    Quelle: ACS Legacy Archives
    Thema: Biologie , Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1021/bi00034a017
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  • 10
    Digitale Medien
    Digitale Medien
    Highly textured thick films by a melt-annealing technique in the Bi-Sr-Ca-Cu-O system (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 2236-2238 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: A melt-annealing method has been developed to deposit highly textured superconducting thick films on different substrates in the Bi-Sr-Ca-Cu-O system. As opposed to previous techniques, this method uses powder made from an extremely dense glass sample to yield very uniform and dense thick films. The x-ray diffraction and scanning electron microscopy results indicate that the superconducting phase is strongly oriented along the c axis perpendicular to the substrate and the films are chemically uniform. Electrical transport measurements consistently show a Tc near 80 K for all samples.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.102356
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