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  • 1
    Electronic Resource
    Electronic Resource
    Fabrication of nanometer-sized magnetic structures using e-beam patterned deposition masks : The 41st annual conference on magnetism and magnetic materials (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 4717-4719 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on the development of a novel technique designed to study dimensional effects in sputter-deposited magnetic materials and multilayer nanostructures without the need for post-deposition patterning. Wires with widths ranging from 40 to 1000 nm have been deposited on Si wafer substrates through a deposition mask fabricated by e-beam lithography. A bilevel resist masking scheme allows smooth, near vertical sidewall profiles, and the resulting structures can be exposed using a simple lift-off process. This process was used to fabricate test structures of Fe, Cu, and Co which were characterized by scanning electron microscopy, atomic force microscopy, and ac resistivity measurements from 3 to 300 K. While the wire structures are geometrically well defined, transport measurements reveal high crystalline defect densities which must be eliminated to fabricate low-dimensional magnetoresistive structures. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.365538
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  • 2
    Electronic Resource
    Electronic Resource
    Deposition of high-quality NiMnSb magnetic thin films at moderate temperatures (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 2740-2744 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Thin films of the ferromagnetic Heusler alloy NiMnSb, of interest for magnetic multilayer devices because of their predicted half-metallic (i.e., 100% spin-polarized) transport properties, have been successfully deposited by rf magnetron sputtering from a single composite target. A novel combination of low argon gas pressure, low deposition rates, and moderate substrate temperatures (250–350 °C) are shown to result in high-quality, low-roughness polycrystalline films of the C1b-type crystal structure, with thicknesses as low as 100 Å, without the need for any post-deposition annealing. The structural properties of these films, determined by x-ray diffraction and atomic force microscopy are presented as a function of deposition conditions. The magnetic properties and resistivity are consistent with bulk MiMnSb, which suggests that they will be effective as spin-polarized conducting layers in multilayer thin-film structures. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.363977
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  • 3
    Electronic Resource
    Electronic Resource
    Quantifying electrical spin injection: Component-resolved electroluminescence from spin-polarized light-emitting diodes (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 3098-3100 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The spin-polarized light-emitting diode (spin-LED) is a very effective tool for accurately quantifying electrical spin injection in a model independent manner. We resolve and identify various components which occur in the electroluminescence (EL) spectra of GaAs quantum-well-based spin-LEDs, and examine the circular polarization of each. While a number of components exhibit significant circular polarization, the values do not necessarily reflect the electrical spin injection efficiency. We show that a reliable measure of spin injection efficiency can be obtained only if one takes care to spectroscopically resolve and accurately identify the free exciton or free carrier components of the EL spectrum, and exclude other components. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1416164
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  • 4
    Electronic Resource
    Electronic Resource
    Magnetoresistance of Mn:Ge ferromagnetic nanoclusters in a diluted magnetic semiconductor matrix (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 78 (2001), S. 2739-2741 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have fabricated a thin film magnetic system consisting of nanoscale Mn11Ge8 ferromagnetic clusters embedded in a MnxGe1−x dilute ferromagnetic semiconductor matrix. The clusters form for growth temperatures of ∼300 °C with an average diameter and spacing of 100 and 150 nm, respectively. While the clusters dominate the magnetic properties, the matrix plays a subtle but interesting role in determining the transport properties. Variable range hopping at low temperatures involves both nanoclusters and MnGe sites, and is accompanied by a negative magnetoresistance attributed in part to spin-dependent scattering analogous to metallic granular systems. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1369151
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  • 5
    Electronic Resource
    Electronic Resource
    Nonvolatile reprogrammable logic elements using hybrid resonant tunneling diode–giant magnetoresistance circuits (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 1190-1192 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have combined resonant interband tunneling diodes (RITDs) with giant magnetoresistance (GMR) elements so that the GMR element controls the switching current and stable operating voltage points of the hybrid circuit. Parallel and series combinations demonstrate continuous or two-state tunability of the subsequent RITD-like current–voltage characteristic via the magnetic field response of the GMR element. Monostable–bistable transition logic element operation is demonstrated with a GMR/RITD circuit in both the dc limit and clocked operation. The output of such hybrid circuits is nonvolatile, reprogrammable, and multivalued. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1395523
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  • 6
    Electronic Resource
    Electronic Resource
    Electrical spin injection across air-exposed epitaxially regrown semiconductor interfaces (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 3989-3991 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have fabricated spin-polarized light-emitting diode structures via epitaxial regrowth of Zn1−xMnxSe on air-exposed surfaces of AlyGa1−yAs/GaAs quantum wells. No passivation procedures were used to protect or prepare the III–V surface. The electroluminescence is strongly circularly polarized due to the electrical injection of spin-polarized electrons from the ZnMnSe contact into the GaAs quantum well. An analysis of the optical polarization yields a lower bound of 65% for the spin injection efficiency. These results demonstrate the robustness of the spin injection process in the diffusive transport regime, and attest to the practicality of manufacturing semiconductor-based spin injection devices. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1332826
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  • 7
    Electronic Resource
    Electronic Resource
    Differential in vivo cytokine mRNA expression in lesional skin of intrinsic vs. extrinsic atopic dermatitis patients using semiquantitative RT-PCR (2003)
    Oxford, UK : Blackwell Science Ltd
    Clinical & experimental allergy 33 (2003), S. 0 
    Details
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background A small subgroup of atopic dermatitis (AD) patients with normal serum IgE levels and without specific IgE sensitization has been termed ‘intrinsic type of AD’ (ADi) as a counterpart to the term ‘extrinsic type of AD’ (ADe). However, there are neither molecular markers nor clinically diagnostic tools for distinguishing between ADi and ADe.Objective The present studies were undertaken to clarify the pathogenesis and in vivo cytokine micromilieu of ADi patients in comparison with ADe patients.Methods We used semiquantitative RT-PCR to investigate the expression of various cytokines and assessed the tissue eosinophil counts in skin biopsies from both types of AD patients.Results Although there was no significant difference of cellular infiltrates in the lesional skin between ADe and ADi patients, ADe had significantly increased tissue eosinophilia than ADi. Based on our RT-PCR, the expression patterns of cytokines could be categorized into four groups. The first group includes IL-5, IL-13, and IL-1β, whose levels of mRNA expression were higher in both types of AD patients than non-atopic (NA) subjects, while ADe patients had even higher levels than ADi patients. The second group includes interferon-gamma (IFN-γ), IL-12, granulocyte-macrophage colony-stimulating factor (GM-CSF), IL-4, and IL-10, whose levels of mRNA expression were elevated in both types of AD patients without differences between ADe and ADi patients. The third group includes tumour necrosis factor-alpha (TNF-α), whose mRNA expression was more decreased in both types of AD patients than NA, and the fourth group includes IL-6 and transforming growth factor-beta (TGF-β), which did not show any differences among the three groups.Conclusion These current data demonstrate that the expressions of cytokines IL-5, IL-13, and IL-1β mRNA and the number of dermal infiltrating eosinophils are increased in ADe patients compared with ADi patients.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2222.2003.01782.x
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  • 8
    Electronic Resource
    Electronic Resource
    Cutaneous mastocytosis associated with a mixed germ cell tumour of the ovary: report of a case and review of the literature (2001)
    Oxford, UK : Blackwell Science Ltd
    British journal of dermatology 145 (2001), S. 0 
    Details
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: A 10-year-old girl with a mixed germ cell tumour of the ovary, treated by surgery and chemotherapy, developed cutaneous mastocytosis approximately 8 months after starting chemotherapy. This is the sixth report of a germ cell tumour associated with mastocytosis. c-kit receptor point mutations, including Asp816Val and Val560Gly were absent in a biopsy specimen obtained from lesional skin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2133.2001.04322.x
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  • 9
    Electronic Resource
    Electronic Resource
    Hydrogen Isotope Exchange Reactions in an Electrical Discharge (2000)
    Springer
    Plasma chemistry and plasma processing 20 (2000), S. 259-275 
    Details
    ISSN: 1572-8986
    Keywords: plasmolysis ; DC electrical discharge ; FTIR ; emission spectra ; hydrogen isotope exchange reaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Hydrogen isotope exchange reactions occurring in (H2O, D2)or (D2O, H2) reacting system under a DC electricaldischarge were investigated using spectroscopic methods such asFourier-transform infrared (FTIR) and plasma emission spectroscopy(PES). The progress of the reactions was determined by real-time measurementof the IR absorbance of HDO molecule, a major product of the reaction. Theprogress of the reaction was studied as a function of the temperature, thecurrent density, and the composition of the reactants, while the pressure ofthe system was maintained at approximately 67 mbar. The results revealedthat the discharge method was far more effective in facilating the exchangereaction than was the conventional catalytic method. The (H2O, D2)system also generated a significant amount of D2O besides HDO andHD as the ratio of D2 to H2O was increased. Thetransient species of the system, such as H or D atoms, were monitored duringthe discharge using emission spectroscopy. The analysis of the final products by mass spectroscopy confirmed that neither H2 nor O2was among the major products of the system in the discharge.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007073224543
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  • 10
    Electronic Resource
    Electronic Resource
    Inheritance and expression of a transgene insert in an aneuploid tobacco line (1994)
    Springer
    Molecular genetics and genomics 245 (1994), S. 471-485 
    Details
    ISSN: 1617-4623
    Keywords: Aneuploidy ; DNA methylation ; Homology-dependent gene silencing ; Non-Mendelian inheritance ; T-DNA ; Trisomy/tetrasomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A T-DNA locus comprising nptII, uidA and nos genes — all under the control of the nos promoter (this locus was designated K because it encodes resistance to Kanamycin) - was found to be inherited erratically in a transgenic tobacco line. This anomalous behavior was partially explained following a karyotype analysis of plants representing several generations: these plants were aneuploids, presumably for the K-containing chromosome. During four generations of sexual propagation, transgenic plants that were either trisomic or tetrasomic for the K-containing chromosome (i.e. 2n=49 or 2n=50, respectively) were obtained. The trisomic plants (2n=48+1) were virtually indistinguishable phenotypically from normal euploids (2n=4x=48), whereas the tetrasomic plants (2n=48+2) were smaller, had somewhat misshapen leaves and exhibited reduced fertility. Although the amount of NPTH protein in different trisomic (K--, KK-, KKK) and tetrasomic (KK--, KKK-) plants was generally consistent with a K dosage effect, the genetic behavior of each trisomic — with respect to segregation of KanR and marker gene activity in progeny — was unique and not completely explicable by invoking aneuploidy. Specifically, unexpected gains or losses of K could occur, suggesting the formation of double reductional gametes and/or frequent gene conversion at this locus. The susceptibility of K locus marker genes to trans-inactivation in the trisomic and tetrasomic lines was tested by crossing in partially homologous silencing loci. In all transgenotypes tested, the three K marker genes were sensitive to trans-silencing, which was accompanied by methylation in all copies of the nos promoter. In addition to this directed inactivation/methylation, the K locus could also undergo infrequent, spontaneous partial methylation, which produced stable epialleles. In most plants, however, the multiple copies of the nos promoter at this locus remained unmethylated and active through four generations in all transgenotypes examined. The significance of these results for irregular inheritance patterns, aneuploid syndromes and homology-dependent gene silencing is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00302260
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