Effect of the TiO2 Nanoparticles on the Growth Behavior of Intermetallics in Sn/Cu Solder Joints

Shengyan Shang,Anil Kunwar,Jinye Yao,Yanfeng Wang,Haitao Ma,Yunpeng Wang 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.2

In order to investigate the effect of TiO2 nanoparticles on growth behavior of interfacial Cu6Sn5 intermetallics compounds(IMCs) in Pb-free Sn/Cu system, the solder joints are fabricated by using flux doped with different content (0.0–2.0 wt% offlux) and particle diameter (5 nm and 50 nm) of TiO2 . In context of isothermal reflow soldering at 250 °C and subsequentair cooling, the increase in reflow duration from 10 to 120 s was characterized with an increment in IMC layer thicknessand grain size, due to the enhancement of Cu flux contribution for Ostwald ripening during constant temperature reflow andprecipitation kinetics during cooling. The increased proportion of TiO2 nanoparticles in flux was found to reduce the growthof IMC layer and grain size. The suppression effect on IMC was more pronounced for 5 nm particles as compared to the 50nm TiO2 . The TiO2 nanoparticles, adsorbed on IMC plane can retard the growth of the latter. Presence of sufficient amountof a given sized TiO2 nanoparticles among IMCs, by increasing the effective stress at the localized interfaces, and causingthe breaking of brittle Cu6Sn5 during growth stage; can help in the inhibition of IMC whisker formation. Particle diameterand mass proportion of TiO2 nanoparticles are important for soldering materials design.

Proteasome subunit beta type 1 interacts directly with Rheb and regulates the cell cycle in Cashmere goat fetal fibroblasts

Yanfeng Wang,Xudong Guo,Zhigang Wang,Zhixin Guo,Mingtao Liu,Keyu Zhao,Xue Feng,Xu Zheng,Xiaojing Wang,Huifang Hao 한국통합생물학회 2017 Animal cells and systems Vol.21 No.5

PSMB1 (proteasome subunit beta type 1) is a core component of the 20S proteasome, and based on its structure, it might have a crucial function in the transcription of certain genes. Rheb (Ras homolog enriched in brain) is a Ras-like small GTPase that acts as an upstream positive regulator of the mechanistic target of rapamycin complex 1 (mTORC1) pathway. We cloned and characterized PSMB1 (KY310590.1) to determine its function in cell cycle progression and proliferation of goat fetal fibroblasts (GFbs). Further, by yeast two-hybrid screen and coimmunoprecipitation, we conformed that PSMB1 interacts directly with Rheb. An siRNA was designed and expressed targeting PSMB1 mRNA in GFbs and inducing cell cycle arrest. Rheb overexpression in GFbs significantly increased the number of S phase cells and growth efficiency compared with control cells. These data indicate that PSMB1 and Rheb have important functions in the cell cycle and proliferation of GFbs, indicating that their interaction governs many processes in GFbs.

Direct Interaction between Ras Homolog Enriched in Brain and FK506 Binding Protein 38 in Cashmere Goat Fetal Fibroblast Cells

Wang, Xiaojing,Wang, Yanfeng,Zheng, Xu,Hao, Xiyan,Liang, Yan,Wu, Manlin,Wang, Xiao,Wang, Zhigang Asian Australasian Association of Animal Productio 2014 Animal Bioscience Vol.27 No.12

Ras homolog enriched in brain (Rheb) and FK506 binding protein 38 (FKBP38) are two important regulatory proteins in the mammalian target of rapamycin (mTOR) pathway. There are contradictory data on the interaction between Rheb and FKBP38 in human cells, but this association has not been examined in cashmere goat cells. To investigate the interaction between Rheb and FKBP38, we overexpressed goat Rheb and FKBP38 in goat fetal fibroblasts, extracted whole proteins, and performed coimmunoprecipitation to detect them by western blot. We found Rheb binds directly to FKBP38. Then, we constructed bait vectors (pGBKT7-Rheb/FKBP38) and prey vectors (pGADT7-Rheb/FKBP38), and examined their interaction by yeast two-hybrid assay. Their direct interaction was observed, regardless of which plasmid served as the prey or bait vector. These results indicate that the 2 proteins interact directly in vivo. Novel evidence is presented on the mTOR signal pathway in Cashmere goat cells.

Experimental Study on Microstructure and Hydraulic Performance of Bentonite Modified Loess

Yanfeng Li,Jian Xu,Zefeng Wang,Bao Wang 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.7

The impact of natural sodium bentonite on the microstructure, permeability and strengthcharacteristics of bentonite-modified loess (BML) were evaluated by scanning electron microscope(SEM) test, triaxial flexible wall permeability test, uniaxial compression test and direct sheartests. The experimental results indicate that bentonite can be used for loess solidificationattributed to its effective particle filling, water absorption and expansion characteristics. Thequantitative parameters of SEM images such as the average pore area, width, length andsurface porosity of BML declined first and then increased with bentonite content, and thelowest was observed at a bentonite content of 15%. The hydraulic conductivity of BMLdeclined with increasing bentonite content and was lower than the maximum allowable limitof 1.0 × 10−9 m/s. The uniaxial compressive strength and shear strength parameters of BMLincreased initially and subsequently declined as bentonite content increased. A normalizedprediction model was established for modified loess based on the correlation betweenmechanical characteristics and the microscopic pore parameters, which was verified to berational in estimating the macro- and micro-scale properties of BML. Therefore, when theanti-seepage landfill layers are constructed in the Loess Plateau area, 15% of bentonite isrecommended in modified loess, which has optimal impermeability and mechanical properties.

Double Line Voltage Synthesis Strategy for Three-to-Five Phase Direct Matrix Converters

Wang, Rutian,Zhao, Yanfeng,Mu, Xingjun,Wang, Weiquan The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.1

This paper proposes a double line voltage synthesis (DLVS) strategy for three-to-five phase direct matrix converters. In the proposed strategy, the input and expected output voltages are divided into 6 segments and 10 segments, respectively. In addition, in order to obtain the maximum voltage transfer ratio (VTR), the input line voltages and "source key" should be selected reasonably according to different combinations of input and output segments. Then, the corresponding duty ratios are calculated to determine the switch sequences in different segment combinations. The output voltages and currents are still sinusoidal and symmetrical with little lower order harmonics under unbalanced or distorted input voltages by using this strategy. In addition, the common mode voltage (CMV) can be suppressed by rearranging some of the switching states. This strategy is analyzed and studied by a simulation model established in MATLAB/Simulink and an experimental platform, which is controlled by a DSP and FPGA. Simulation and experimental results verify the feasibility and validity of the proposed DLVS strategy.

Incremental Optimization of Hub and Spoke Network under Changes of Spokes’ Number and Flow

Yanfeng Wang,Youfang Huang 보안공학연구지원센터 2016 International Journal of Hybrid Information Techno Vol.9 No.1

Hub and spoke network has been widely used in air transport, road freight, shipping network and urban distribution areas as part of the strategic decisions, which may have a profound effect on the future of enterprises. In view of the existing network structure, as time goes on, the number of spokes and the flow change because of different sources of uncertainty. Hence, the incremental optimization of the capacitated single-allocation hub and spoke network problem is considered in this paper, and the decisions to be made to cope with change comprise (i) whether new hubs need to be setup and their selection, (ii) whether the capacity levels of original hubs need to be adjusted, and their new capacity levels, (iii) whether the original hubs need to be closed, (iv) the new allocation of the spoke nodes to the hubs, (v) the flow distribution through the sub network defined by all the hubs. The objective is to minimize the total cost, which includes the setup costs for the new hubs, the closure costs and the adjustment costs for the original hubs as well as the flow routing costs. Two mixed-integer linear programming formulations are proposed and analyzed for this problem. A set of computational tests are performed, and we analyze the changes in the solutions driven by the number of spokes and the flow. The tests also allow an analysis to consider the effect of variation in parameters on the network.

Double Line Voltage Synthesis Strategy for Three-to-Five Phase Direct Matrix Converters

Rutian Wang,Yanfeng Zhao,Xingjun Mu,Weiquan Wang 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.1

This paper proposes a double line voltage synthesis (DLVS) strategy for three-to-five phase direct matrix converters. In the proposed strategy, the input and expected output voltages are divided into 6 segments and 10 segments, respectively. In addition, in order to obtain the maximum voltage transfer ratio (VTR), the input line voltages and “source key” should be selected reasonably according to different combinations of input and output segments. Then, the corresponding duty ratios are calculated to determine the switch sequences in different segment combinations. The output voltages and currents are still sinusoidal and symmetrical with little lower order harmonics under unbalanced or distorted input voltages by using this strategy. In addition, the common mode voltage (CMV) can be suppressed by rearranging some of the switching states. This strategy is analyzed and studied by a simulation model established in MATLAB/Simulink and an experimental platform, which is controlled by a DSP and FPGA. Simulation and experimental results verify the feasibility and validity of the proposed DLVS strategy.

Recombinant Goat VEGF164 Increases Hair Growth by Painting Process on the Skin of Shaved Mouse

Bao, Wenlei,Yin, Jianxin,Liang, Yan,Guo, Zhixin,Wang, Yanfeng,Liu, Dongjun,Wang, Xiao,Wang, Zhigang Asian Australasian Association of Animal Productio 2014 Animal Bioscience Vol.27 No.9

To detect goat vascular endothelial growth factor (VEGF)-mediated regrowth of hair, full-length VEGF164 cDNA was cloned from Inner Mongolia cashmere goat (Capra hircus) into the pET-his prokaryotic expression vector, and the recombinant plasmid was transferred into E. coli BL21 cells. The expression of recombinant $6{\times}his-gVEGF164$ protein was induced by 0.5 mM isopropyl thio-${\beta}$-D-galactoside at $32^{\circ}C$. Recombinant goat VEGF164 (rgVEGF164) was purified and identified by western blot using monoclonal anti-his and anti-VEGF antibodies. The rgVEGF164 was smeared onto the dorsal area of a shaved mouse, and we noted that hair regrowth in this area was faster than in the control group. Thus, rgVEGF164 increases hair growth in mice.

Effects of Crop Residues and Application Manners on Biological Properties of Continuous Cropping Cucumber Soil in Solar Greenhouses

Yanfeng Qi,Min Wei,Xiufeng Wang 한국원예학회 2008 한국원예학회 기타간행물 Vol.- No.-

Investigation on quasi-static and dynamic mechanical properties of disc springs considering asymmetric frictional boundary

Yanfeng Zhou,Dan Wang,Jianyuan He,Weifang Chen,Rupeng Zhu 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.11

Systematic experimental studies of disc springs are sparse. In this paper, quasistatic and dynamic compression experiments are performed on a single disc spring under both symmetric and asymmetric frictional conditions for different series of disc springs. On this basis, multiple disc springs stacked in parallel are also investigated. The full-range load-displacement curves of disc springs under quasi-static and dynamic compression are obtained and compared with the theoretical values, and the limitations of the existing analytical solutions are pointed out. The analysis revealed that frictional conditions of contact boundaries greatly affect the damping of disc springs. As the compression frequency increases, the damping of the disc spring gradually increases and finally remains stable. When the disc springs are stacked in parallel, the stiffness relationship can be approximated as conforming to the law of parallel connection, but the damping increases significantly due to the introduction of friction between internal contact surfaces.