RESUMO
Point contacts between normal and ferromagnetic metals are investigated using magnetoresistance and transport spectroscopy measurements combined with micromagnetic simulations. Pronounced hysteresis in the point contact resistance versus both bias current and external magnetic field are observed. It is found that such hysteretic resistance can exhibit, in addition to bi-stable resistance states found in ordinary spin valves, tri-stable resistance states with a middle resistance level. We interpret these observations in terms of surface spin valve and spin vortex states, originating from a substantially modified spin structure at the ferromagnetic interface in the contact core. We argue that these surface spin states, subject to a weakened exchange interaction, dominate the effects of spin transfer torques on the nanometer scale.
RESUMO
We report an observation of spin-valve-like hysteresis within a few atomic layers at a ferromagnetic interface. We use phonon spectroscopy of nanometer-sized point contacts as an in situ probe to study the mechanism of the effect. Distinctive energy phonon peaks for contacts with dissimilar nonmagnetic outer electrodes allow localizing the observed spin switching to the top or bottom interfaces for nanometer thin ferromagnetic layers. The mechanism consistent with our data is energetically distinct atomically thin surface spin layers that can form current- or field-driven surface spin-valves within a single ferromagnetic film.
Assuntos
Cobalto/química , Magnetismo , Membranas Artificiais , Nanoestruturas/química , Nanoestruturas/ultraestrutura , Nanotecnologia/métodos , Substâncias Macromoleculares/química , Teste de Materiais , Conformação Molecular , Tamanho da Partícula , Marcadores de Spin , Propriedades de SuperfícieRESUMO
In this study, we have investigated correlation between enzymatic activity of NAD(P)-dependent dehydrogenases of lymphocytes and polymorphic variants of glutathione S-transferase M1 (GSTM1) and T1 (GSTT1) genes in the group of unrelated patients with acute pancreatitis in comparison with healthy Russians from Krasnoyarsk. Thus, genotype GSTM1 0/0 is the marker of predisposition to the acute pancreatitis, wheras polymorphism of the GSTT1 gene is not involved in the development of the pancreatitis, at least in our group. The bioluminescence analysis showed statistically significant decrease of the levels of G3PD, NAD(+)MDH and the increase of NADH(+)LDH, NAD(+)GDH, NADH(+)GDH in lymphocytes of pancreatic group. Development of pancreatitis in patients with different genotypes GSTM1 and GSTT1 genes showed the rearrangement of the basic intracellular processes: dominance of a plastic metabolism in the patients with GSTM1--deletions and predominance of energetic processes at GSTT1 0 - pancreatitis.
Assuntos
Predisposição Genética para Doença , Glutationa Transferase/genética , Linfócitos/metabolismo , Pancreatite/genética , Doença Aguda , Adulto , Feminino , Genótipo , Humanos , Linfócitos/enzimologia , Masculino , Pancreatite/etiologia , Pancreatite/metabolismo , Polimorfismo GenéticoRESUMO
Phonon spectroscopy is used to investigate the mechanism of current-induced spin torques in nonmagnetic/ferromagnetic (N/F) point contacts. Magnetization excitations observed in the magneto-conductance of the point contacts are pronounced for diffusive and thermal contacts, where the electrons experience significant scattering in the contact region. We find no magnetic excitations in highly ballistic contacts. Our results show that impurity scattering at the N/F interface is the origin of the new single-interface spin torque effect.
RESUMO
Original methods for identification and quantitative photometry of 5-nitrofurane derivatives based on the use of known rhodanine reagents were developed and used in clinical analysis.
Assuntos
Nitrofuranos/análise , Humanos , Nitrofuranos/urina , EspectrofotometriaRESUMO
We studied the possibility of using prooxidant effects of nitrofurantoin (furadonin) for stimulation of the natural antioxidant systems for preventing myocardial damage after coronary occlusion. A pronounced cardioprotective effect of the drug was observed.
Assuntos
Cardiotônicos/farmacologia , Peroxidação de Lipídeos/efeitos dos fármacos , Nitrofurantoína/farmacologia , Espécies Reativas de Oxigênio/farmacologia , Animais , Masculino , Ratos , Ratos WistarRESUMO
A method for isolating tyrosyl-tRNA synthetase from Thermus thermophilus is described, including ammonium sulfate fractionation, chromatography on DEAE-sepharose, hydroxyapatite, heparin-sepharose and hydrophobic chromatography on Toyopearl HW-65. The yield of the purified enzyme was 1.6 mg per 1 kg of T. thermophilus cells. The enzyme is a dimer protein of the alpha 2 type with molecular weight of 100 kDa.
Assuntos
Aminoacil-tRNA Sintetases/isolamento & purificação , Thermus/enzimologia , Tirosina-tRNA Ligase/isolamento & purificação , Catálise , Cromatografia por Troca Iônica , Eletroforese em Gel de Poliacrilamida , Peso Molecular , TemperaturaAssuntos
Hipertensão/epidemiologia , Programas de Rastreamento , Adulto , Humanos , Masculino , Pessoa de Meia-Idade , Ucrânia , População UrbanaRESUMO
It has recently been suggested1 that the absorption line v = 26.13 MHz that we had detected2 in the direction of Cassiopeia A might be a recombination line due either to carbon (C631α) present in H I clouds or to heavier elements of hot gas. Observations reported here taken in February 1981 suggest that the low-frequency attenuation in the spectrum of Cas A is due to the presence of a cold cloud of ionized carbon.
