Fast response Full Bridge Power Factor Corrector

A fast response Full Bridge Power Factor Corrector (FBPFC) is presented in this paper. The converter is combined by two interleaved boost cells and a conventional full bridge converter. As the interleaving technique is applied, the input ripple current of FBPFC are reduced. Experimental result shows that the maximum power factor is 0.98 even without input filter.published_or_final_versio

Interleaved boost power factor corrector operating in discontinuous-inductor-current mode

This paper presents the basic operation of the Discontinuous-Inductor-Current-Mode (DICM) boost PFC and the improvement achieved by interleaving technique. The PFC is constructed by at least two boost cells, each cell is kept running in DICM. Input current of the PFC is analyzed by numerical method and the optimum power factor is calculated in different modes of operation. The calculated result is verified by experiment and presented in graphical form with detailed discussion. The result shows that interleaving technique can alleviate the ripple current and improve the power factor. The improvement is obvious for the number of boost cells equal to 2 or 3 and the ripple alleviation is better when the PFC is operated in fixed frequency mode. The optimum power factor is improved up to 0.99 even without an input filter.published_or_final_versio

DSP controlled power converter

A digital controller is designed and implemented by a Digital Signal Processor (DSP) to replace the Pulse Width Modulator (PWM) and error amplifier compensation network in a two wheeler forward converter. The DSP controller is designed in three approaches: a) Discretization of analog controller - the design is based on the transfer function of the error amplifier compensation network. b) Digital PID controller design - the design is based on the general form of the pulse transfer function of PID controller. c) Deadbeat controller design - the design is based on the open-loop pulse transfer function of the power converter. The controller design is optimised by running computer simulation with the MATLAB numerical calculation package and the experimental results agree with the simulated analysis.published_or_final_versio

HIV-1 Tat dysregulation of KSHV induced immune response through the production of IL-8

Poster PresentationHuman immunodeficiency virus (HIV) causes acquired immunodeficiency syndrome (AIDS) and is a major health issue around the world. HIV is known to induce a number of pathological problems in AIDS patients via the transactivator (Tat) protein that is expressed and released by infected cells. One of the most important function of Tat is the dysregulation of the immune response. IL-8 is a chemokine known to be highly expressed in AIDS patients and Tat plays a major role in its production. IL-8 increases the HIV transmission and replication rate; and plays a role in Kaposi's sarcoma associated herpesvirus (KSHV) infection, which is a major opportunistic pathogen that AIDS patients are at risk to. KSHV is also known to induce the expression of IL-8 in patients, and IL-8 is known to assist tumour development by increasing angiogenesis. In our study, we investigated the role that Tat may have in manipulating the expression of IL-8 induced by KSHV in primary blood monocyte derived macrophages (PBMac). The results showed that pretreatment of PBMac with Tat inhibited the expression of IL-8 induced by KSHV by approximately 40%. We also found that Tat was able to inhibit the phosphorylation of STAT-1 induced by KSHV, and the inhibition of STAT-1 phosporylation was related to the expression of IL-8 induced by KSHV. In conclusion, we found that Tat was able to manipulate the expression of IL-8 induced by KSHV in macrophages, and this inhibition of IL-8 expression was regulated through the STAT-1 related pathways.published_or_final_versio

Investigating the role of interleukin-17A on cytokines production by macrophages in response to bacterial infections

Poster PresentationInterleukin-17A (IL-17A) has been shown to associate with a variety of infection diseases. In this study, we investigate whether IL-17A affects cytokines production of human peripheral blood-derived macrophages during Mycobacteriun bovis BCG or Klebsiella pneumoniae infection. We observed that IL-17A-treated macrophages exhibited suppressed productions of TNF-α and IL-6 in response to BCG infection. The reduction of cytokines production was not associated with cell death. On the other hand, IL-17A promoted TNF-α and IL-6 production by macrophages during K. pneumoniae infection. Furthermore, IL-17A did not affect TNF-α production induced by LPS and Pam3 Cys, which are TLR4 and TLR2 agonists, respectively. The data suggest that the differential regulation of cytokines production by IL-17A requires whole bacterium infection.published_or_final_versio

Evolution of superconductivity in K2-xFe4+ySe5: Spectroscopic studies of X-ray absorption and emission.

This study investigates the evolution of superconductivity in K2-xFe4+ySe5 using temperature-dependent X-ray absorption and resonant inelastic X-ray scattering techniques. Magnetization measurements show that polycrystalline superconducting (SC) K1.9Fe4.2Se5 has a critical temperature (T c) of ∼31 K with a varying superconducting volume fraction, which strongly depends on its synthesis temperature. An increase in Fe-structural/vacancy disorder in SC samples with more Fe atoms occupying vacant 4d sites is found to be closely related to the decrease in the spin magnetic moment of Fe. Moreover, the nearest-neighbor Fe-Se bond length in SC samples exceeds that in the non-SC (NS) sample, K2Fe4Se5, which indicates a weaker hybridization between the Fe 3d and Se 4p states in SC samples. These results clearly demonstrate the correlations among the local electronic and atomic structures and the magnetic properties of K2-xFe4+ySe5 superconductors, providing deeper insight into the electron pairing mechanisms of superconductivity

Novel Hybrid Au/Fe3O4 Magnetic Octahedron-like Nanoparticles with Tunable Size

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Synthesis and Morphology Control of Gold/Iron oxide Magnetic Nanocomposites via a Simple Aqueous Method

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Liver cancer immunoassay with magnetic nanoparticles and MgO-based magnetic tunnel junction sensors

This journal issue is proceedings of the 56th 56th Conference on Magnetism and Magnetic MaterialsSession DV - Sensors 2 (Poster Session): no. DV-07We have demonstrated the detection of alpha-fetoprotein (AFP) labeled with magnetic nanoparticles (MNPs) using MgO-based magnetic tunnel junction (MTJ) sensors. AFP is an important hepatic tumor biomarker and the detection of AFP has significant applications for clinical diagnostics and immunoassay for early-stage liver cancer indications. In this work, MgO-based MTJ sensors and 20-nm iron-oxide magnetic nanoparticles (MNPs) were used for detecting AFP antigens by a sandwich-assay configuration. The MTJ sensors with a sensing area of 4 × 2 μm 2 possess tunneling magnetoresistance (TMR) of 122 and sensitivity of 0.95/Oe at room temperature. The target AFP antigens of three concentrations were successfully detected, and the experimental data indicate that the resistance variations of the MTJ sensor increased with the AFP concentration ratios proportionally. These results demonstrate that MgO-based MTJ sensors together with MNPs are a promising biosensing platform for liver cancer immunoassay. © 2012 American Institute of Physics.published_or_final_versionThe 56th Conference on Magnetism and Magnetic Materials, Scottsdale, AZ., 30 October-3 November 2011. In Journal of Applied Physics, 2012, v. 111 n. 7, article no. 07E50

Liver cancer immunoassay with magnetic nanoparticles and MgO-based magnetic tunnel junction sensors

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