Transformerless Three-Level DC-DC Buck Converter with a High Step-Down Conversion Ratio

Zhang, Yun,Sun, Xing-Tao,Wang, Yi-Feng,Shao, Hong-Jun The Korean Institute of Power Electronics 2013 JOURNAL OF POWER ELECTRONICS Vol.13 No.1

For high power high step-down dc-dc conversion applications, conventional three-level dc-dc converters are subject to extreme duty cycles or increased volume and cost due to the use of transformers. In this paper, a transformerless three-level dc-dc buck converter with a high step-down conversion ratio is proposed. The converter comprises two asymmetrical half bridges, which are of the neutral point clamped structures. Therefore, the output pulse voltage of the converter can be obtained in terms of the voltage difference between the two half bridges. In order to realize harmonious switching of the converter, a modulation strategy with capacitor voltages self balance is presented. According to the deduced output dc voltage function, transformerless operation without extreme duty cycles can be implemented. Experimental results from a 1kW prototype verify the validity of the proposed converter. It is suitable for ship electric power distribution systems.

Association of the PSCA rs2294008 C>T Polymorphism with Gastric Cancer Risk: Evidence from a Meta-Analysis

Zhang, Qing-Hui,Yao, Yong-Liang,Gu, Tao,Gu, Jin-Hua,Chen, Ling,Liu, Yun Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.6

Background: Multiple studies have reported associations between the PSCA rs2294008 C > T polymorphism and GC, but susceptibility has proven inconsistent. Therefore, we estimates the relationship between the rs2294008 C > T polymorphism and GC by meta-analysis. Methods: PubMed, Embase and Web of Science databases were searched and nine independent case-control studies were included in this meta-analysis. Crude ORs with 95% CIs were extracted according to the Mantal-Haenszel method and pooled to assess the strength of the association. Results: We observed that the PSCA rs2294008 C > T polymorphism was significantly correlated with GC risk when all studies were pooled into the meta-analysis. Further subgroup analysis showed the polymorphism to be linked with diffuse and noncardia GC in the allele contrast model, homozygote codominant model, dominant model, and recessive model. However, no connection was apparent for intestinal and cardia GC. In the stratified analysis by ethnicity, significant associations were observed in Asians for the recessive model. Interestingly, the relationship was particularly significant in the Chinese population. Conclusions: Our findings suggest that the PSCA rs2294008 C > T polymorphism is a risk factor for GC, especially in diffuse and noncardia GC and in Chinese.

Effects of Combining Treatment of 5‐aza‐2’‐deoxyctidine and Trichostatin A into Fetal Fibroblasts on the Development of Porcine Cloned Embryos

Yun Fei Diao,Rong Xun Han,Jin Yu Zhang,Min Gu Lee,Tao Lin,Reza K. Oqani,Chang Sik Park,Dong Il Jin 한국동물생명공학회(구 한국동물번식학회) 2011 발생공학 국제심포지엄 및 학술대회 Vol.2011 No.1

5‐aza‐2’‐deoxyctidine (5‐aza‐dC) is DNA methylation inhibitor and Trichostatin A (TSA) is histone deacytlase inhibitor, both of them can alter the level of the epigenetic modification of cells. The objective of this study was to investigate the effects of treatment with 5‐aza‐dC and TSA into fetal fibroblasts on the development of porcine nuclear transfer (NT) embryos. In this study, experiments were performed in order to modify epigenetic status in donor cells and evaluate developmental potential of NT embryos. 5‐ aza‐dC or TSA or combining treatment of TSA and 5‐aza‐dC was treated into growing donor cells for 1 h exposure and development of NT embryos was evaluated. Experiment was performed with 3 groups: control group (donor cells without treatment); TSA group (donor cell treated with 50 nM TSA for 1 h); TSA + 5‐aza‐dC group (donor cells were treated with 50 nM TSA and 5 nM 5‐aza‐dC for 1 h); TSA+1/2(5‐aza‐dC) group (donor cells were treated with 50 nM TSA for 1h and subsequently treated with 2.5 nM 5‐aza‐dC for another 1h). When donor cells were individually treated with 5 nM 5‐aza‐dC or 50 nM TSA for 1h, the blastocyst rate of NT embryos increased significantly compared with control group [18.8% vs 13.4% (5 nM 5‐aza‐dC group vs control group), and 26.2% vs 11.8% (50 nM TSA group vs control group), p<0.05]. However, the blastocyst rate in combining treatment group (50 nM TSA + 5 nM 5‐aza‐dC) did not increase compare with control group (12.3% vs 11.8%, p>0.05). When the donor cell were individually treated with 50nM TSA for 1 h firstly and then treated with 2.5 nM 5‐aza‐dC for another 1h, the blastocyst rate was significantly improved compared with control and TSA group (28% vs 10.2% and 23.7%, p<0.05). The present study suggested that donor cells treated with TSA or low concentration of TSA+5‐azadC in short time exposure may enhance the development of porcine NT embryo.

Acetylation of Smc3 by Eco1 Is Required for S Phase Sister Chromatid Cohesion in Both Human and Yeast

Zhang, Jinglan,Shi, Xiaomin,Li, Yehua,Kim, Beom-Jun,Jia, Junling,Huang, Zhiwei,Yang, Tao,Fu, Xiaoyong,Jung, Sung Yun,Wang, Yi,Zhang, Pumin,Kim, Seong-Tae,Pan, Xuewen,Qin, Jun Elsevier 2008 Molecular cell Vol.31 No.1

<P><B>Summary</B></P><P>Sister chromatid cohesion is normally established in S phase in a process that depends on the cohesion establishment factor Eco1, a conserved acetyltransferase. However, due to the lack of known in vivo substrates, how Eco1 regulates cohesion is not understood. Here we report that yeast Eco1 and its human ortholog, ESCO1, both acetylate Smc3, a component of the cohesin complex that physically holds the sister chromatid together, at two conserved lysine residues. Mutating these lysine residues to a nonacetylatable form leads to increased loss of sister chromatid cohesion and genome instability in both yeast and human. In addition, we clarified that the acetyltransferase activity of Eco1 is essential for its function. Our study thus identified a molecular target for the acetyltransferase Eco1 and revealed that Smc3 acetylation is a conserved mechanism in regulating sister chromatid cohesion.</P>

Transformerless Three-Level DC-DC Buck Converter with a High Step-Down Conversion Ratio

Yun Zhang,Xing-tao Sun,Yi-feng Wang,Hong-jun Shao 전력전자학회 2013 JOURNAL OF POWER ELECTRONICS Vol.13 No.1

For high power high step-down dc-dc conversion applications, conventional three-level dc-dc converters are subject to extreme duty cycles or increased volume and cost due to the use of transformers. In this paper, a transformerless three-level dc-dc buck converter with a high step-down conversion ratio is proposed. The converter comprises two asymmetrical half bridges, which are of the neutral point clamped structures. Therefore, the output pulse voltage of the converter can be obtained in terms of the voltage difference between the two half bridges. In order to realize harmonious switching of the converter, a modulation strategy with capacitor voltages self balance is presented. According to the deduced output dc voltage function, transformerless operation without extreme duty cycles can be implemented. Experimental results from a 1kW prototype verify the validity of the proposed converter. It is suitable for ship electric power distribution systems.

Effect of Sorbitol on In Vitro Porcine Oocyte Maturation and Subsequent Developmental after Parthenogenetic Activation

Tao Lin,Jin-Yu Zhang,Yun-Fei Diao,Min-Gu Lee,Rong-Xun Han,Reze K. Oqani,Dong-Il Jin 한국동물번식학회 2012 Reproductive & Developmental Biology(Supplement) Vol.36 No.2s

The objective of the present study was to investigate the effects of different concentrations of sorbitol supplementation for in vitro maturation medium and in vitro culture medium, on porcine cumulus oocyte complexe(COC) maturation and subsequent developmental capacity after parthenogenetic activation. Porcine COC were cultured for 44 h(0~ 22 h termed MI stage and 22~44 h termed MII stage) in TCM199 without(- ) or with(+) sorbitol (20 μM, 100 μM, 200 μM), and the resultant metaphase II oocytes cultured in PZM-3 for 7 days following activation. Our results showed that supplementation with appropriate concentrations of sorbitol (20 μM) during full term maturation culture(MI+/MII+) significantly(p<0.05) improved blastocyst formation rates and total cell number. When the concentration of sorbitol were increased to 100 μM and 200 μM during maturation culture, the maturation rate of COC were significantly reduced compared with 20 μΜ or control groups. Also blastocyst formation rates significantly(p<0.05) reduced with increasing concentration of sorbitol(200 μM). Supplementation with sorbitol(20 μM, 50 μM, 100 μM) into PZM-3 for in vitro culture significantly(p<0.05) inhibited blastocyst formation compared with control group. However, the blastocyst formation rates start to rise again when 50 μ M sorbitol was used for the first 48 hours and then cultured in PZM-3 without sorbitol. There was no significant difference in cell number between control and sorbitol treated groups. When the activated oocytes were cultured in PZM-3 for 48h and then cultured in PZM-3 with sorbitol, interestingly, the blastocyst formation rate was similar to that of PZM-3 with sorbitol for in vitro culture and significantly lower than control group. These results suggest that addition of low concentrations of sorbitol(20 μM) during oocyte maturation is beneficial for subsequent blastocyst development and improved embryo quality. However, treatment with sorbitol supplementation during in vitro culture medium is negative effect to blastocyst formation.

Supervised locally tangent space alignment for machine fault diagnosis

Yun Zhang,Benwei Li,Wen Wang,Tao Sun,Xinyi Yang,Lin Wang 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.8

How to deal with the high-dimensional and nonlinear data is a challenging problem for fault diagnosis. An unsupervised locally tangentspace alignment (LTSA) has recently proven to be an effective unsupervised manifold learning algorithm for high-dimensional dataanalysis. In this paper, a supervised expansion of LTSA (named S-LTSA) is proposed, which takes full advantage of class label informationto improve classification performance. Based on S-LTSA, a novel machine fault diagnosis approach is proposed to deal with thehigh-dimensional fault data that contain multiple manifolds corresponding to fault classes. The experiment results with bearing fault datashow that the proposed approach outperforms the other fault pattern recognition approaches such PCA, ICA, LDA and LTSA.

Demethylation of CpG islands in the 5` upstream regions mediates the expression of the human testis-specific gene MAGEB16 and its mouse homolog Mageb16

( Yun Qiang Liu ),( Mei Ling Wang ),( Si Yuan Jiang ),( Yong Jie Lu ),( Da Chang Tao ),( Yuan Yang ),( Yong Xin Ma ),( Si Zhong Zhang ) 생화학분자생물학회 2014 BMB Reports Vol.47 No.2

Tissue-specific gene expression is regulated by epigenetic modification involving trans-acting factors. Here, we identified that the human MAGEB16 gene and its mouse homolog, Mageb16, are only expressed in the testis. To investigate the mechanism governing their expression, the promoter methy-lation status of these genes was examined in different samples. Two CpG islands (CGIs) in the 5` upstream region of MAGEB16 were highly demethylated in human testes, whereas they were methylated in cells without MAGEB16 expression. Similarly, the CGI in Mageb16 was hypomethylated in mouse testes but hypermethylated in other tissues and cells without Mageb16 expression. Additionally, the expression of these genes could be activated by treatment with the demethylation agent 5`-aza-2`- deoxycytidine (5`-aza-CdR). Luciferase assays revealed that both gene promoter activities were inhibited by methylation of the CGI regions. Therefore, we propose that the testis-specific expression of MAGEB16 and Mageb16 is regulated by the methylation status of their promoter regions. [BMB Reports 2014; 47(2): 86-91]

Thermal Shock Behaviors of AlN/BN Laminated Ceramic Composites

Tao Zhang,Ji-feng Zhao,Zhi-hao Jin,Hai-yun Jin 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.2

AlN/BN laminated ceramic composites were fabricated by a flow casting method. The thermal shock behavior of both block AlN ceramics and AlN/BN laminated ceramic composites were carried out for comparison. To understanding the different of thermal shock resistance for the two materials, the microstructures were observed and the mechanical properties were tested. The results showed that, the thermal shock resistance of AlN/BN laminated ceramic composites was larger than that of block AlN ceramics. During the tests of residual strength after quenching from different temperatures, for the block AlN ceramics, the residual strength would decrease rapidly when the critical temperature difference ΔTc was larger than 450℃, on the other hand, for the AlN/BN laminated ceramic composites, the residual strength would decrease slowly and there was no obvious ΔTc. AlN/BN laminated ceramic composites were fabricated by a flow casting method. The thermal shock behavior of both block AlN ceramics and AlN/BN laminated ceramic composites were carried out for comparison. To understanding the different of thermal shock resistance for the two materials, the microstructures were observed and the mechanical properties were tested. The results showed that, the thermal shock resistance of AlN/BN laminated ceramic composites was larger than that of block AlN ceramics. During the tests of residual strength after quenching from different temperatures, for the block AlN ceramics, the residual strength would decrease rapidly when the critical temperature difference ΔTc was larger than 450℃, on the other hand, for the AlN/BN laminated ceramic composites, the residual strength would decrease slowly and there was no obvious ΔTc.

Effect of Sorbitol on In Vitro Porcine Oocyte Maturation and Subsequent Developmental after Parthenogenetic Activation

Tao Lin,Jin-Yu Zhang,Yun-Fei Diao,Min-Gu Lee,Rong-Xun Han,Reze K. Oqani,Dong-Il Jin 한국동물번식학회 2012 Reproductive & developmental biology Vol.36 No.2