Magnetic Properties of Dilute Alloys: Equations for Magnetization and its Structural Fluctuations

The dilute Heisenberg ferromagnet is studied taking into account fluctuations of magnetization caused by disorder. A self-consistent system of equations for magnetization and its mean quadratic fluctuations is derived within the configurationally averaged two-time temperature Green's function method. This system of equations is analised at low concentration of non-magnetic impurities. Mean relative quadratic fluctuations of magnetization are revealed to be proportional to the square of concentration of impurities.Comment: 16 pages, LaTe

Room temperature spin Kondo effect and intermixing in Co/Cu non-local spin valves

The anomalous low temperature suppression of the spin accumulation signalDRNLin non-localspin valves (NLSVs) based on common ferromagnet (FM)/normal metal (N) pairings has recentlybeen shown to result from a manifestation of the Kondo effect. Local magnetic moments in the Ndue to even minor levels of FM/N interdiffusion depolarize the injected spin current, suppressingthe effective spin polarization around and below the Kondo temperatureTK. Previous studies havefocused on FM/N combinations that happen to have lowTKso that Kondo effects occur only wellbelow 300 K. Here, we study NLSVs based on Co/Cu, a materials combination that is not onlytechnologically relevant but also has a highTK, up to 500 K. Despite the negligibleequilibriumsol-ubility of Co in Cu, we find clear Kondo effects in bothDRNLand Cu resistivity, due to Co/Cuintermixing that we probeviaquantitative transmission electron microscopy. Most significantly,under certain conditions the spin Kondo effect suppresses the injected spin polarizationeven atroom temperature, with important technological implications. Studies as a function of the Cu thick-ness and annealing temperature reveal complex trends in interdiffusion lengths and Kondo effects,which we interpret in terms of the interplay between diffusion kinetics and thermodynamics, aswell as the thickness dependence of the Kondo effect

Sensitivity of Arctic warming to sea ice concentration

We examine the sensitivity of Arctic amplification (AA) to background sea ice concentration (SIC) under greenhouse warming by analyzing the data sets of the historical and Representative Concentration Pathway 8.5 runs of the Coupled Model Intercomparison Project Phase 5. To determine whether the sensitivity of AA for a given radiative forcing depends on background SIC state, we examine the relationship between the AA trend and mean SIC on moving 30 year windows from 1960 to 2100. It is found that the annual mean AA trend varies depending on the mean SIC condition. In particular, some models show a highly variable AA trend in relation to the mean SIC clearly. In these models, the AA trend tends to increase until the mean SIC reaches a critical level (i.e., 20-30%), and the maximum AA trend is almost 3 to 5 times larger than the trend in the early stage of global warming (i.e., 50-60%, 60-70%). However, the AA trend tends to decrease after that. Further analysis shows that the sensitivity of AA trend to mean SIC condition is closely related to the feedback processes associated with summer surface albedo and winter turbulent heat flux in the Arctic Ocean.1111Ysciescopu

Antioxidant, antibacterial and α-glucosidase inhibitory activities of different extracts of Cortex Moutan

Different extracts of Cortex Moutan (CM) were investigated for their antioxidant, antibacterial and α- glucosidase inhibitory activities. The content of paeonol was quantified by high performance liquid chromatography (HPLC). The results show that the yield of acetone extract (57.14%) was significantly higher than those of other solvents. The ethyl-acetate extract exhibited maximum paeonol concentration (60.69 μg/ml), good antibacterial activities (MIC = 100 μg/ml) against Escherichia coli and possessed significant α-glucosidase inhibitory activity. In addition, among all of the extracts, ethylacetate extract demonstrated a high total phenolic value of 127.12 ± 1.42 mg GAE/g, high DPPH radical scavenging activity with an IC50 of 19.88 ± 0.26 μg/ml, and significant reducing power, suggesting that CM is a potential source of natural antioxidants.Key words: Cortex Moutan, antioxidant, 11-diphenyl-2-picrylhydrazyl hydrate (DPPH), reducing power, antibacterial, α-glucosidas

Statistical variability study of random dopant fluctuation on gate-all-around inversion-mode silicon nanowire field-effect transistors

Random dopant fluctuation effects of gate-all-around inversion-mode silicon nanowire field-effect transistors (FETs) with different diameters and extension lengths are investigated. The nanowire FETs with smaller diameter and longer extension length reduce average values and variations of subthreshold swing and drain-induced barrier lowering, thus improving short channel immunity. Relative variations of the drain currents increase as the diameter decreases because of decreased current drivability from narrower channel cross-sections. Absolute variations of the drain currents decrease critically as the extension length increases due to decreasing the number of arsenic dopants penetrating into the channel region. To understand variability origins of the drain currents, variations of source/drain series resistance and low-field mobility are investigated. All these two parameters affect the variations of the drain currents concurrently. The nanowire FETs having extension lengths sufficient to prevent dopant penetration into the channel regions and maintaining relatively large cross-sections are suggested to achieve suitable short channel immunity and small variations of the drain currents. (C) 2015 AIP Publishing LLC.open111415sciescopu

Global organization of metabolic fluxes in the bacterium, Escherichia coli

Cellular metabolism, the integrated interconversion of thousands of metabolic substrates through enzyme-catalyzed biochemical reactions, is the most investigated complex intercellular web of molecular interactions. While the topological organization of individual reactions into metabolic networks is increasingly well understood, the principles governing their global functional utilization under different growth conditions pose many open questions. We implement a flux balance analysis of the E. coli MG1655 metabolism, finding that the network utilization is highly uneven: while most metabolic reactions have small fluxes, the metabolism's activity is dominated by several reactions with very high fluxes. E. coli responds to changes in growth conditions by reorganizing the rates of selected fluxes predominantly within this high flux backbone. The identified behavior likely represents a universal feature of metabolic activity in all cells, with potential implications to metabolic engineering.Comment: 15 pages 4 figure

PGC-Enriched miRNAs Control Germ Cell Development

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Direct Observation of Localized Spin Antiferromagnetic Transition in PdCrO2 by Angle-Resolved Photoemission Spectroscopy

We report the first case of the successful measurements of a localized spin antiferromagnetic transition in delafossite-type PdCrO2 by angle-resolved photoemission spectroscopy (ARPES). This demonstrates how to circumvent the shortcomings of ARPES for investigation of magnetism involved with localized spins in limited size of two-dimensional crystals or multi-layer thin films that neutron scattering can hardly study due to lack of bulk compared to surface. Also, our observations give direct evidence for the spin ordering pattern of Cr3+ ions in PdCrO2 suggested by neutron diffraction and quantum oscillation measurements, and provide a strong constraint that has to be satisfied by a microscopic mechanism for the unconventional anomalous Hall effect recently reported in this system.X1118sciescopu