Input Voltage Range Extension Method for Half-Bridge LLC Converters by Using Magamp Auxiliary Post-Regulator

Xiaoguang Jin,Huipin Lin,Jun Xu,Zhengyu Lu 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.1

An improved half-bridge LLC converter with a magamp auxiliary post-regulator is proposed in this paper. The function of themagamp is bypassed when the converter works within the low input-voltage range. Meanwhile, it operates as an auxiliarypost-regulator when the input voltage is high. By changing the blocking time of the magamp, the dc gain of the converter can beextended. Hence, the input voltage range of the converter is extended. The realization of proposed topology does not require acomplicated circuit. The controller of the magamp can be easily implemented using only passive components, transistors and anOP amp. The generalized operational principle is analyzed and the design criterion for the magamp is presented. Finally, a 25Voutput, 400W experimental prototype was built and tested for a 160–300V input-voltage range to verify the feasibility of theproposed method.

Analysis of Gene Expression Profiles of Liver Stellate Cells During Liver Regeneration in Rats

Xu Cunshuan,Chen Xiaoguang,Chang Cuifang,Wang Gaiping,Wang Wenbo,Zhang Lianxing,Zhu Qiushi,Wang Lei,Zhang Fuchun 한국분자세포생물학회 2011 Molecules and cells Vol.31 No.1

This study performed a large-scale, high-throughput analy-sis of transcriptional profiling of liver stellate cells (LSCs) at the cellular level to investigate changes in the biological activity of LSCs during rat liver regeneration (LR) and the relation of these changes to LR. First, a rat liver regeneration model was established by partial hepatectomy (PH). Stellate cells were isolated in high purity and yield from the regenerating rat liver by Percoll density gradient centrifugation and immunomagnetic bead sorting. The changes in gene expression of LSCs after PH were examined using a rat genome 230 2.0 array composed of 24622 genes. The results indicated that 10241 of the 24622 genes investigated on the array were differentially expressed in LSCs. Of the 10241 genes, 1563 known genes were related to LR, which were grouped into three major gene expression clusters according to three-fold cut-off threshold: the up-regulated gene cluster, the down-regulated gene cluster, and the cluster composed of genes showing complex changes in expression. Additionally, the genes were grouped into those involved in transcription regulation, signal transduction, transport, cellular metabolism, in-flammation and immunity by functional analysis. When gene expression profiles were combined with the results of gene functional analysis, most of the genes involved in cytokine secretion and retinol metabolism in LSCs were significantly enriched in the cluster characterized by decreased expression, whereas genes involved in lipid metabolism were mostly enriched in the cluster showing increased expression. Based on further analysis of genes expressed in a phase-dependent manner during LR, it was suggested that lipid metabolism in LSCs was enhanced in the whole regeneration process, and that immune response and cytokine secretion were impaired during all three regenerative phases.

Transcriptional profiles of biliary epithelial cells from rat regenerating liver after partial hepatectomy

Cunshuan Xu,Xiaoguang Chen,Cuifang Chang,Gaiping Wang,Wenbo Wang,Lianxing Zhang,Qiushi Zhu,Lei Wang,Fuchun Zhang 한국유전학회 2012 Genes & Genomics Vol.34 No.3

It has been widely accepted that hepatocytes are critical for liver regeneration (LR), but very little is known about the role of biliary epithelial cells (BECs) in this event, so this study aims to manifest the relevance of BECs with LR. High purity population of BECs was obtained using Percoll gradient centrifugation combined with immunomagnetic-bead separation technique. Transcriptional profiles of BECs from rat regenerating liver after 2/3 hepatectomy were monitored with rat genome 230 2.0 array. Microarray analysis results were evaluated by RT-PCR assays. Of all the genes on the array, 1262 known genes and 1026 unknown genes were related to LR. 79 of 1262 known genes showed a ≥ 20-fold change in expression level, mainly participating in primary metabolism and inflammatory response. In contrast to the regenerating liver,BEC division did not occur at proliferative phase of LR; alterations in nucleic acid, lipid and protein metabolism were significantly different from each other or within the same substance metabolism at different phases; the active signaling pathways in priming phase were mediated mainly by G protein-coupled receptor, small GTPase and Wnt receptor. Transport-related genes showed up-regulated expression mainly in priming and proliferative phases, possibly linked to cell membrane formation and transport function recovery of BECs in the late phase. In brief, comparative analysis of biological activities of BECs and the regenerating liver reveals that bio-logical activities at the cellular level are not always consistent with those at tissue level, suggesting the necessity of cell level investigation on liver regeneration. Finally, expression of BEC markers in hepatocytes may suggest the potential of hepatocytes to transdifferentiate into BEC.

Requirement of the isocitrate lyase gene ICL1 for VPS41-mediated starvation response in Cryptococcus neoformans

Zhe Xu,Yafei Zhi,Jianzhang Dong,Benfeng Lin,Di Ye,Xiaoguang Liu 한국미생물학회 2016 The journal of microbiology Vol.54 No.7

Cryptococcus neoformans is a major cause of fungal meningitis in individuals with impaired immunity. Our previous studies have shown that the VPS41 gene plays a critical role in the survival of Cryptococcus neoformans under nitrogen starvation; however, the molecular mechanisms underlying VPS41-mediated starvation response remain to be elucidated. In the present study, we show that, under nitrogen starvation, VPS41 strongly enhanced ICL1 expression in C. neoformans and that overexpression of ICL1 in the vps41 mutant dramatically suppressed its defects in starvation response due to the loss of VPS41 function. Moreover, targeted deletion of ICL1 resulted in a dramatic decline in viability of C. neoformans cells under nitrogen deprivation. Taken together, our data suggest a model in which VPS41 up-regulates ICL1 expression, directly or indirectly, to promote survival of C. neoformans under nitrogen starvation.

Leakage Flux Adjustment and Flux Field Optimization for Coreless Axial Flux Permanent Magnet Synchronous Machine Based on U-shaped Iron

Wang Xiaoguang,Yin Hao,Liu Cheng,Li Xiaofeng,Zhang Guoguang,Liu Yi,Xu Wei 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.5

The rotor leakage flux will cause a lot of eddy current losses in the windings of coreless axial flux permanent magnet synchronous machine (CAFPMSM). This article presents a rotor leakage flux adjustment method for the CAFPMSM based on U-shaped iron, which can also achieve the optimization of the rotor flux field. The U-shaped iron can reduce the leakage flux crosses the winding and improve the spatial harmonic distribution of the air gap field at the same time. Firstly, the basic topology and its operating principle are investigated by using an equivalent magnetic circuit model. And then, the characteristics of the flux field distribution in the winding area are analyzed, and the parameters of the U-shaped iron on the leakage flux path regulation are elaborated and optimized by the three-dimensional finite-element method (3D FEM) analysis. Finally, the comprehensive experimental results show that the leakage flux path of the rotor passes through the U-shaped magnetically conductive block rather than through the windings, the total harmonic distortion (THD) of the air gap flux density waveform can be significantly decreased, and the THD of the back EMF and the eddy current losses are lower than before.

Input Voltage Range Extension Method for Half-Bridge LLC Converters by Using Magamp Auxiliary Post-Regulator

Jin, Xiaoguang,Lin, Huipin,Xu, Jun,Lu, Zhengyu The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.1

An improved half-bridge LLC converter with a magamp auxiliary post-regulator is proposed in this paper. The function of the magamp is bypassed when the converter works within the low input-voltage range. Meanwhile, it operates as an auxiliary post-regulator when the input voltage is high. By changing the blocking time of the magamp, the dc gain of the converter can be extended. Hence, the input voltage range of the converter is extended. The realization of proposed topology does not require a complicated circuit. The controller of the magamp can be easily implemented using only passive components, transistors and an OP amp. The generalized operational principle is analyzed and the design criterion for the magamp is presented. Finally, a 25V output, 400W experimental prototype was built and tested for a 160-300V input-voltage range to verify the feasibility of the proposed method.

Intracellular trafficking of TREM2 is regulated by presenilin 1

Yingjun Zhao,Xiaoguang Li,Timothy Huang,Lu-lin Jiang,Zhenqiu Tan,Muxian Zhang,Irene Han-Juo Cheng,Xin Wang,Guojun Bu,Yun-wu Zhang,Qi Wang,Huaxi Xu 생화학분자생물학회 2017 Experimental and molecular medicine Vol.49 No.-

Genetic mutations in triggering receptor expressed on myeloid cells 2 (TREM2) have been linked to a variety of neurodegenerative diseases including Alzheimer’s disease, amyotrophic lateral sclerosis, frontotemporal dementia and Parkinson’s disease. In the brain, TREM2 is highly expressed on the cell surface of microglia, where it can transduce signals to regulate microglial functions such as phagocytosis. To date, mechanisms underlying intracellular trafficking of TREM2 remain elusive. Mutations in the presenilin 1 (PS1) catalytic subunit of the γ-secretase complex have been associated with increased generation of the amyloidogenic Aβ (amyloid-β) 42 peptide through cleavage of the Aβ precursor amyloid precursor protein. Here we found that TREM2 interacts with PS1 in a manner independent of γ-secretase activity. Mutations in TREM2 alter its subcellular localization and affects its interaction with PS1. Upregulation of PS1 reduces, whereas downregulation of PS1 increases, steady-state levels of cell surface TREM2. Furthermore, PS1 overexpression results in attenuated phagocytic uptake of Aβ by microglia, which is reversed by TREM2 overexpression. Our data indicate a novel role for PS1 in regulating TREM2 intracellular trafficking and pathophysiological function.

Adaptive V1-MT model for motion perception

( Shuai Li ),( Xiaoguang Fan ),( Yuelei Xu ),( Jinke Huang ) 한국인터넷정보학회 2019 KSII Transactions on Internet and Information Syst Vol.13 No.1

Motion perception has been tremendously improved in neuroscience and computer vision. The baseline motion perception model is mediated by the dorsal visual pathway involving the cortex areas the primary visual cortex (V1) and the middle temporal (V5 or MT) visual area. However, few works have been done on the extension of neural models to improve the efficacy and robustness of motion perception of real sequences. To overcome shortcomings in situations, such as varying illumination and large displacement, an adaptive V1-MT motion perception (Ad-V1MTMP) algorithm enriched to deal with real sequences is proposed and analyzed. First, the total variation semi-norm model based on Gabor functions (TV-Gabor) for structure-texture decomposition is performed to manage the illumination and color changes. And then, we study the impact of image local context, which is processed in extra-striate visual areas II (V2), on spatial motion integration by MT neurons, and propose a V1-V2 method to extract the image contrast information at a given location. Furthermore, we take feedback inputs from V2 into account during the polling stage. To use the algorithm on natural scenes, finally, multi-scale approach has been used to handle the frequency range, and adaptive pyramidal decomposition and decomposed spatio-temporal filters have been used to diminish computational cost. Theoretical analysis and experimental results suggest the new Ad-V1MTMP algorithm which mimics human primary motion pathway has universal, effective and robust performance.

Image flickering-free polymer stabilized fringe field switching liquid crystal display

Jiang, Yingfei,Qin, Guangkui,Xu, Xiaoguang,Zhou, Li,Lee, SeungHee,Yang, Deng-Ke The Optical Society 2018 Optics express Vol.26 No.25

Eu³⁺→Eu²⁺ unusual reduction and bond energy in MAlSi₂O₆:Eu (M = Li, Na, K, Rb, Cs)

Pan, Yu,Wang, Wenjun,Zhu, Yuhan,Xu, Haibing,Noh, Hyeon Mi,Jeong, Jung Hyun,Liu, Xiaoguang,Li, Ling Elsevier 2018 CERAMICS INTERNATIONAL Vol.44 No.7

<P><B>Abstract</B></P> <P>Eu-doped MAlSi<SUB>2</SUB>O<SUB>6</SUB> (M = Li, Na, K, Rb, Cs) phosphors were synthesized by solid-state reaction in air. The crystal structure and optical properties of the phosphors were investigated by X-ray powder diffraction and photoluminescence. Their emission spectra are composed of some broad bands coming from the 5d-4f transition of Eu<SUP>2+</SUP> and some sharp emission peaks coming from the f-f transitions of Eu<SUP>3+</SUP>. The co-existence of Eu<SUP>3+</SUP> and Eu<SUP>2+</SUP> cations is detected in MAlSi<SUB>2</SUB>O<SUB>6</SUB>:2%Eu, which shows that the unusual Eu<SUP>3+</SUP>→Eu<SUP>2+</SUP> reduction process occurs in MAlSi<SUB>2</SUB>O<SUB>6</SUB>. The preferential occupancy of Eu<SUP>3+</SUP> or Eu<SUP>2+</SUP> in MAlSi<SUB>2</SUB>O<SUB>6</SUB> can be calculated to be M<SUP>+</SUP> sites by the bond-energy method. The deviation of the Eu<SUP>3+</SUP>–O<SUP>2-</SUP> bond energy is closed to that of the Eu<SUP>2+</SUP>–O<SUP>2-</SUP> bond energy, which means that Eu<SUP>3+</SUP> and Eu<SUP>2+</SUP> can coexist in air. The abnormal reduction of Eu<SUP>3+</SUP> to Eu<SUP>2+</SUP> can be explained by charge compensation model. The doped Eu<SUP>3+</SUP> was induced to M<SUP>+</SUP> and the vacancy (<I>V</I> <SUB> <I>M</I> </SUB>) may be formed. The vacancy(<I>V</I> <SUB> <I>M</I> </SUB>) acted as a donor of electrons, and the Eu M ∙ ∙ defect acted as an acceptor of electrons. The theoretical result is consistent with the experimental phenomenon.</P>