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  • 1
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Phenomena of colossal magnetoresistance (MR) or magnetic field induced insulator–metal (I–M) transitions have been investigated for single crystals of perovskite-type manganese oxides with controlled carrier density and one-electron bandwidth. In addition to the canonical MR behavior near the Curie temperature, the first-order phase transition accompanying several orders of magnitude change in resistivity has been observed under an external magnetic field for many of the composition-controlled crystals as an intrinsic bulk phenomenon. It was proved by the systematic experimental investigations that the field-induced destruction of the charge-ordered state accompanying the lattice structural as well as metamagnetic transition is a major origin of such a colossal MR. Versatile MR phenomena and I–M phase diagrams in the T–H plane are presented with their interpretation. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 4954-4956 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have investigated magnetoresistance (MR) phenomena relevant to the charge ordering (CO), namely, the real space ordering of both Mn3+ and Mn4+, in single crystals of (Nd1−ySmy)1/2Sr1/2MnO3, in which the one-electron bandwidth (W) is systematically controlled by varying the average ionic radius of the A site. The low-field colossal MR is observed for the small-W region of y≥0.5; e.g., ρ(0)/ρ(H)〉103 in a field of 0.4 T at 115 K for the y=0.94 crystal. This is viewed as a first-order insulator-to-metal phase transition induced by a magnetic field, which accompanies a lattice-structural change. In the small-W region, the CO instability accompanying the antiferromagnetic spin correlations subsists even above the ferromagnetic transition temperature Tc. The competition between the ferromagnetic double-exchange and antiferromagnetic CO interactions gives rise to such a lattice-coupled first-order phase transition induced by a relatively low magnetic field. © 1997 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. 3609-3611 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: To explore the optimized colossal magnetoresistance (MR), i.e., higher MR with lower field, magnetotransport properties of single-crystalline perovskite manganites have systematically been investigated. Near x=1/2 with intrinsic instability of charge ordering (a 1/1 ordering of Mn3+/Mn4+), the one-electron bandwidth (W) is varied by reducing the radius of R-site cation in R1−xSrxMnO3. For R=Nd, the MR behavior is rather canonical, while for R=Sm, the field-induced nonmetal-to-metal transition of the first order shows up accompanying a change in resistivity by several orders of magnitude as a result of an enhanced antiferromagnetic interaction. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 52 (1996), S. 2365-2367 
    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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  • 5
    Electronic Resource
    Electronic Resource
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 53 (1997), S. 610-612 
    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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  • 6
    Electronic Resource
    Electronic Resource
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 52 (1996), S. 1806-1808 
    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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  • 7
    ISSN: 1432-0584
    Keywords: Key words Bone marrow transplantation ; Cyclosporin A ; Granulocyte colony-stimulating factor ; Monosomy 7 ; Severe aplastic anemia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  A cytogenetically normal man with severe aplastic anemia was treated with granulocyte colony-stimulating factor (G-CSF), erythropoietin (EPO), cyclosporin A, anti-thymocyte globulin, and interleukin-6 (IL-6), which resulted in a gradual improvement in his neutrophil count and hemoglobin level. After 2 years of the therapy, monosomy 7 was detected during cytogenetic analysis of his bone marrow, which evolved during a period of 5 months into acute myeloblastic leukemia. An in vitro proliferation assay of cytokine responses showed that leukemic blasts were sensitive only to G-CSF, and not to EPO or IL-6. Although allogeneic bone marrow transplantation from an HLA-matched unrelated donor was carried out in the non-remission stage, the patient died of systemic fungal infection on day 25, without any evidence of hematological engraftment. As long-term use of cytokines and immunomosuppressants in patients with severe aplastic anemia may induce or hasten the onset of a malignant transformation, careful attention must be paid to clonal evolution. Due to the poor prognosis of secondary myelodysplasia and leukemia, allogeneic bone marrow transplantation for such patients must be carried out early in the course of the disease.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-0584
    Keywords: Key words Immunosuppressants ; Cyclosporin A ; FK506 ; KM2210 ; Hematopoiesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Immunosuppressants cyclosporin A (CsA), FK506, and KM2210 modulated colony formations of murine hematopoietic progenitor cells. In a 4-h treatment with CsA, 10 μg/ml increased the formation of colony-forming units of mixed lineages (CFU-Mix) but decreased the formation of highly proliferative potential colony-forming units (CFU-HPP); 1 μg/ml of CsA increased the formations of CFU-HPP, CFU-Mix, and colony-forming units of granulocytes/macrophages (CFU-GM); 0.1 μg of CsA increased the formation of CFU-Mix and burst-forming units of erythroid lineage (BFU-E). Lower doses of CsA appeared to induce an increase in various colony formations. FK506 increased CFU-HPP and CFU-Mix formations at lower doses. Another immunosuppressant, KM2210, increased CFU-HPP and CFU-GM formations but decreased CFU-Mix and BFU-E formations. In a 24-h treatment, 10 μg/ml and 1 μg/ml of CsA inhibited all the colony formations, but 0.1 μg/ml of CsA increased CFU-Mix, CFU-GM, and BFU-E formations. Similarly, 100 ng/ml and 10 ng/ml of FK506 decreased all the colony formations but 1 ng/ml of FK506 increased CFU-HPP and CFU-GM formations. KM2210 inhibited all the colony formations. These findings showed that lower doses of CsA and FK506 appeared to increase the colony formations, although higher doses of these drugs decreased the colony formations, similar to the findings in a 4-h treatment. On the other hand, KM2210 showed opposing effects on colony formation with 4-h and 24-h treatments.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Annals of hematology 71 (1995), S. 265-269 
    ISSN: 1432-0584
    Keywords: Allogeneic transplantation ; PBSCT ; G-CSF ; GVHD ; Cytokine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Recombinant human granulocyte colonystimulating factor (rhG-CSF)-mobilized peripheral blood stem cells (PBSC) are now widely used for autologous transplantation to provide hematopoietic stem cells after intensive chemoradiotherapy. However, PBSC which contain a large number of T cells represent a potential risk for graft-versus-host disease (GVHD) in allogeneic (allo) transplantation. There are about 50 case reports of clinical trials of rhG-CSF-mobilized allo PBSC transplantation (PBSCT) with relatively rapid hematological recovery, without severe acute GVHD except in a few cases. Therefore, the risk of inducing severe acute GVHD is not as high as was expected when allo PBSCT began. However, whether allo PBSCT will increase the risk of chronic GVHD is not clear, because the period of observation has been too short. Also, it will be of interest to determine the clinical effect of allo PBSCT on relapse of hematological malignancy post-transplant. Whether allo PBSCT will increase life-threatening acute and chronic GVHD, and whether PBSC allografting will result in permanent hematological and immunological reconstitution has to be determined by prospective randomized clinical trials.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Annals of hematology 71 (1995), S. 265-269 
    ISSN: 1432-0584
    Keywords: Key words Allogeneic transplantation ; PBSCT ; G-CSF ; GVHD ; Cytokine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Recombinant human granulocyte colony-stimulating factor (rhG-CSF)-mobilized peripheral blood stem cells (PBSC) are now widely used for autologous transplantation to provide hematopoietic stem cells after intensive chemoradiotherapy. However, PBSC which contain a large number of T cells represent a potential risk for graft-versus-host disease (GVHD) in allogeneic (allo) transplantation. There are about 50 case reports of clinical trials of rhG-CSF-mobilized allo PBSC transplantation (PBSCT) with relatively rapid hematological recovery, without severe acute GVHD except in a few cases. Therefore, the risk of inducing severe acute GVHD is not as high as was expected when allo PBSCT began. However, whether allo PBSCT will increase the risk of chronic GVHD is not clear, because the period of observation has been too short. Also, it will be of interest to determine the clinical effect of allo PBSCT on relapse of hematological malignancy post-transplant. Whether allo PBSCT will increase life-threatening acute and chronic GVHD, and whether PBSC allografting will result in permanent hematological and immunological reconstitution has to be determined by prospective randomized clinical trials.
    Type of Medium: Electronic Resource
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