3,660 research outputs found

    Spin-splitting in an AlxGa1−xN/GaN nanowire for a quantum-ring interferometer

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    [[abstract]]The authors thank M. H. Gau, C. H. Hsieh, C. C Yang, R. Y. Su, and C. H. Chen for their assistance. The project was supported by National Science Council and Core Facilities Laboratory in Kaohsiung-Pingtung Area, Taiwan. The authors are also grateful to W. C. Mitchel and M. Mah for their help and AFOSR/AOARD, USAF for financial support under Grant No. FA4869-07-1-4022.[[abstract]]An Al0.18 Ga0.82 N/GaN heterostructure was used to fabricate a ballistic nanowire with a wire width of 200 nm by focused ion beam. We observed the beating Shubnikov-de Haas oscillations in the nanowire with a spin-splitting energy of (2.4±0.3) meV. Based on the results, we proposed a spin-Hall quantum-ring interferometer made of Alx Ga1-x N/GaN nanowires for spintronic applications. © 2008 American Institute of Physics.[[booktype]]紙

    Self-organizing magnetic beads for biomedical applications

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    In the field of biomedicine magnetic beads are used for drug delivery and to treat hyperthermia. Here we propose to use self-organized bead structures to isolate circulating tumor cells using lab-on-chip technologies. Typically blood flows past microposts functionalized with antibodies for circulating tumor cells. Creating these microposts with interacting magnetic beads makes it possible to tune the geometry in size, position and shape. We developed a simulation tool that combines micromagnetics and discrete particle dynamics, in order to design micropost arrays made of interacting beads. The simulation takes into account the viscous drag of the blood flow, magnetostatic interactions between the magnetic beads and gradient forces from external aligned magnets. We developed a particle-particle particle-mesh method for effective computation of the magnetic force and torque acting on the particles

    Neutrophil and lymphocyte responses to oral Streptococcus in Adamantiades-Behcet's disease

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    Immune reactions against microorganisms play an important pathogenic role in Adamantiades-Behçet’s disease (ABD). We had previously obtained Streptococcus sanguinis (strain BD113-20) isolated from the oral cavity of patients with ABD. To investigate the pathogenesis of this isolate, we examined neutrophil 5 reactions and level of cytokine production by lymphocytes after stimulation with the strain. The reactions of neutrophils were examined by chemiluminescence assay using whole blood. The amounts of interferon gamma (IFN-g) and interleukin (IL)-4, IL-8, IL-10, and IL-12 produced by peripheral blood mononuclear cells (PBMCs) were measured by ELISA. 10 Strain BD113-20 activated neutrophils from patients with ABD and healthy volunteers, and, in addition it increased IFN-g production by lymphocytes. Lymphocyte from the patients with ABD showed a dominant T helper 1 (Th-1) immune response. Results indicated that both bacterial stimulation and host hypersensitivity might be involved in the symptoms and pathogenesis of ABD

    Peripheral Electrical and Magnetic Stimulation to Augment Resistance Training

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    Electrical stimulation (ES) and magnetic stimulation (MS), applied peripherally, may be used to elicit muscle contractions to increase muscle hypertrophy, increase muscle strength and reduce knee laxity in rehabilitation following injury. We aimed to examine the effect of a three-week exercise programme designed to induce muscle hypertrophy augmented by peripheral ES and MS. We hypothesised that the use of peripheral stimulation to augment voluntary drive during a resistance-training protocol would induce more repetitions thus leading to increased thigh circumference, muscle layer thickness, and quadriceps strength whilst decreasing knee laxity. Thirty healthy participants were divided randomly into either ES, MS or Control groups. Five resistance training sessions were carried out, consisting of four sets of quadriceps extensions. During the first three sets the participants performed eight repetitions at 85% of their 1-repetition maximum (1-RM). On the last set, the participants were instructed to perform the exercise until failure. The augmentation of peripheral stimuli allowed the MS and ES groups to continue to exercise producing, on average, 4 ± 2 and 7 ± 6 additional repetitions with ES and MS, respectively. Following the training, significant increases were observed for both 1-RM (p = 0.005) and muscle layer thickness (p = 0.031) whilst no change was observed in thigh circumference (p = 0.365). Knee laxity decreased (p = 0.005). However, there were no significant differences in the stimulation groups compared with control for any of these measurements. The additional repetitions elicited by stimulation after the point of failure suggests that peripheral electrical and/or magnetic stimulation may be useful as an adjunct for resistance training. However, this effect of resistance training augmented by peripheral stimulation on hypertrophy, strength and knee laxity may be small

    mRNA analysis of single living cells

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    Analysis of specific gene expression in single living cells may become an important technique for cell biology. So far, no method has been available to detect mRNA in living cells without killing or destroying them. We have developed here a novel method to examine gene expression of living cells using an atomic force microscope (AFM). AFM tip was inserted into living cells to extract mRNAs. The obtained mRNAs were analyzed with RT-PCR, nested PCR, and quantitative PCR. This method enabled us to examine time-dependent gene expression of single living cells without serious damage to the cells

    Atomic Force Microscopy of Humic Acids

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    Atomic force microscopic (AFM) images of humic acids show discrete, globular particles, where particles of the order of magnitude 100 to 300 nm dominate the image fields; the humic acids had been grown to a steady state at pH 5.0. The AFM data are consistent with our previously reported small-angle neutron scattering (SANS) study done under similar conditions. In further agreement, the cluster-cluster interactions shown in our previous SANS study may have their counterparts in closely interacting particles appearing as twin particles in the AFM images
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