Laser-weldable Si_p-SiC_p/Al hybrid composites with bilayer structure for electronic packaging

Laser-weldable Sip-SiCp/Al hybrid composites with high volume fraction （60%-65%） of SiC reinforcement were fabricated by compression moulding and vacuum gas pressure infiltration technology. Microscopic observation displayed that the Sip-SiCp/Al hybrid composites with bilayer structure were compact without gas pores and the intergradation between Sip/Al layer and SiCp/Al layer was homogeneous and continuous. Further investigation revealed that the Sip-SiCp/Al hybrid composites possessed low density （2.96 g/cm^3）, high gas tightness （1.0 mPa·cm^3）/s）, excellent thermal management function as a result of high thermal conductivity （194 W/（m·K） and low coefficient of thermal expansion （7.0×10^-6 K-1）. Additionally, Sip-SiCp/Al hybrid composites had outstanding laser welding adaptability, which is significantly important for electronic packaging applications. The gas tightness of components after laser welding （48 mPa·cm^3）/s） can well match the requirement of advanced electronic packaging. Several kinds of these precision components passed tests and were put into production.

MicroRNA-502-3p regulates GABAergic synapse function in hippocampal neurons

Gamma-aminobutyric acid(GABA)ergic neurons,the most abundant inhibitory neurons in the human brain,have been found to be reduced in many neurological disorders,including Alzheimer's disease and Alzheimer's disease-related dementia.Our previous study identified the upregulation of microRNA-502-3p(miR-502-3p)and downregulation of GABA type A receptor subunitα-1 in Alzheimer's disease synapses.This study investigated a new molecular relationship between miR-502-3p and GABAergic synapse function.In vitro studies were perfo rmed using the mouse hippocampal neuronal cell line HT22 and miR-502-3p agomiRs and antagomiRs.In silico analysis identified multiple binding sites of miR-502-3p at GABA type A receptor subunitα-1 mRNA.Luciferase assay confirmed that miR-502-3p targets the GABA type A receptor subunitα-1 gene and suppresses the luciferase activity.Furthermore,quantitative reve rse transcription-polymerase chain reaction,miRNA in situ hybridization,immunoblotting,and immunostaining analysis confirmed that overexpression of miR-502-3p reduced the GABA type A receptor subunitα-1 level,while suppression of miR-502-3p increased the level of GABA type A receptor subunitα-1 protein.Notably,as a result of the overexpression of miR-502-3p,cell viability was found to be reduced,and the population of necrotic cells was found to be increased.The whole cell patch-clamp analysis of human-GABA receptor A-α1/β3/γ2L human embryonic kidney(HEK)recombinant cell line also showed that overexpression of miR-502-3p reduced the GABA current and overall GABA function,suggesting a negative correlation between miR-502-3p levels and GABAergic synapse function.Additionally,the levels of proteins associated with Alzheimer s disease were high with miR-502-3p overexpression and reduced with miR-502-3p suppression.The present study provides insight into the molecular mechanism of regulation of GABAergic synapses by miR-502-3p.We propose that micro-RNA,in particular miR-502-3p,could be a potential therapeutic to rget to modulate GABAergic synapse function in neurological disorders,including Alzheimer's disease and Alzheimer's diseaserelated dementia.

基于混合FE-SEA方法的汽车驾驶室声学包优化设计

以某车型为研究对象,基于混合有限元——统计能量方法建立了驾驶室的中频噪声预测模型,通过实车试验,获取待测工况下的激励信号,并验证构建的驾驶室混合FE-SEA模型的准确性;然后分析车内噪声贡献度,确定声学包优化的主要方向,采用拉丁超立方设计方法,以此构建克里金近似模型。基于遗传算法对声学包布置参数进行优化设计,并验证了优化方案效果。结果表明,合理优化关键板件的声学包布置参数能够有效降低驾驶室噪声水平。

Hybrid Ⅲ-50th-RS假人上腹部冲击试验探究

列车碰撞事故中,人体腹部是一个比较容易受到严重损伤的部位之一,为开发设计出适用于列车碰撞试验所用假人——Hybrid Ⅲ-50th-RS假人的腹部,开展针对假人上腹部的冲击试验探究。Hybrid Ⅲ-50th-RS假人上腹部的研究主要是参考THOR-NT假人上腹部冲击试验标准,结合国外Hybrid Ⅲ-50th-RS上腹部标定方法进行的试验探索。利用假人生产制作的常用材料,研究假人上腹部多层泡沫材料的组合方案、假人坐姿、压力分配板与腹袋是否连接、是否穿胸部皮肤以及假人上腹部的结构等对假人上腹部标定的影响及其响应特性。通过对试验数据进行分析,总结Hybrid Ⅲ-50th-RS假人上腹部冲击标定的影响因素及试验规律。根据所参考的THOR-NT假人上腹部冲击试验生物力学响应标准,确定符合试验要求的Hybrid Ⅲ-50th-RS假人上腹部的材料组合及其结构方案。研究结果表明:进行Hybrid Ⅲ-50th-RS假人上腹部冲击试验时,假人配有胸部皮肤,保持上腹部水平,压力分配板与腹袋保持连接更符合试验要求。采用后层2块丁晴橡胶板+中层三元乙丙泡沫+前层聚氨酯泡沫的“四层式”腹部结构和“前软中软”的材料搭配方案,具有较好的生物力学响应特性,适合用做列车碰撞试验假人上腹部。

Chromosome analysis of esophageal squamous cell carcinoma cell line KYSE 410-4 by repetitive multicolor fluorescence in situ hybridization

Chromosome aberrations are distinctive features of human malignant tumors. Analysis of chromosomal changes can illuminate the molecular mechanisms underlying the development and progression of cancer. To establish the technique of multicolor fluorescence in situ hybridization （M-FISH） for identifying chromosome aberrations in esophageal carcinoma cell line KYSE 410-4, four pools of 6-color whole-chromosome painting probes have been designed and hybridized on the same metaphase spread by four rounds of repetitive FISH. Repetitive 6-color M-FISH was successfully established and the cytogenetic abnormalities in KYSE 410-4 cells were characterized. Chromosome gains occurred at 2q, 3, 8, 17p, and X. An isochromosome 3q was visualized in the cell line, which might be one intermediate mechanism leading to 3p losses and/or 3q gains. Furthermore, 16 structural arrangements were detected, including four derivative chromosomes. The rearrangement of the centromeric regions accounted for approximately 44% of all rearrangements. The results added a more complete and accurate information of the genetic alterations to the classical cytogenetic description of KYSE 410-4 and provided a detailed cytogenetic background data for appropriate use of the cell line. The established 6-color M-FISH was useful for analyzing chromosomes in the whole genome of human tumors.

A hybrid Lagrangian-Eulerian numerical model for sea-ice dynamics

A hybrid Lagrangian - Eulerian （HLE） method is developed for sea ice dynamics, which combines the high computational efficiency of finite difference method （FDM） with the high numerical accuracy of smoothed particle hydrodynamics （SPH）. In this HLE model, the sea ice cover is represented by a group of Lagrangian ice particles with their own thicknesses and concentrations. These ice variables are interpolated to the Eularian gird nodes using the Gaussian interpolation function. The FDM is used to determine the ice velocities at Eulerian grid nodes, and the velocities of Lagrangian ice particles are interpolated from these grid velocities with the Gaussian function also. The thicknesses and concentrations of ice particles are determined based on their new locations. With the HLE numerical model, the ice ridging process in a rectangular basin is simulated, and the simulated results are validated with the analytical solution. This method is also applied to the simulation of sea ice dynamics in a vortex wind field. At last, this HLE model is applied to the Bohai Sea, and the simulated concentration, thickness and velocity match the satellite images and the field observed data well.

Multiple-stacked Hybrid Plays of lacustrine source rock intervals：Case studies from lacustrine basins in China

Hydrocarbon-producing lacustrine basins are widely developed in the world, and China has a large number of lacustrine basins that have developed since the early Permian. The organic-rich shale-dominated heterogeneous source rock intervals in Chinese lacustrine basins generally contain frequent thin interbeds of stratigraphically associated sandstone, siltstone, marl, dolomite, and limestone. The concept of ‘‘Hybrid Plays＇ ＇ as put forth in this article recognizes this pattern of alternating organicrich shale and organic-lean interbeds and existence of mixed unconventional and conventional plays. Hybrid Plays in lacustrine source rock intervals present a unique closed petroleum system hosting continuous hydrocarbons.The interbedded organic-lean siliciclastic and/or carbonateplays are efficiently charged with hydrocarbons via short migration pathways from the adjacent organic-rich shale that is often also a self-sourced play. We assert ‘‘Hybrid Plays＇ ＇ provide the most realistic exploration model for targeting multiple-stacked and genetically related very tight shale, tight and conventional plays together in the entire source rock interval rather than individual plays only. The Hybrid Play model has been proven and works for a wide variety of lacustrine rift, sag and foreland basins in China.

S波段HYBRID聚束-加速结构的样机研制

Hybrid聚束-加速结构是把驻波预聚束器、行波聚束器和标准加速管集成到一起的新型RF结构。简述了对S波段Hybrid聚束-加速结构样机的束流动力学优化和微波设计结果,解释了Hybrid结构导致发射度增长的原因,对此样机进行了射频低功率测试。样机的冷测结果与RF设计结果一致性很好。在冷测频率2855.21 MHz处,实测S11小于-45 dB,腔间相移偏差小于±2°,VSWR≤1.2对应的带宽大于5 MHz,轴向场分布完全满足动力学要求。

Synthesis and Characterization of Polystyrene/Nanosilica Organic-Inorganic Hybrid

A polystyrene（PS）/nanosilica organic-inorganic hybrid material was prepared from styrene monomer and commercial aqueous silica sol containing large amounts of Si-OH by means of emulsion polymerization. The nanosilica sol was modified by the addition of the reactive coupling agent methacrylexy propyltrimethoxysilane （ MPS）, and the resulting latex particles were protected by surfactants such as sodium dodecyl sulphonate（ SDS）, hydroxypropyl methyl cellulose （ HMPC）, and poly （vinylpyrrolidone） （PVP）. The effects of the type of surfactant, the amount of surfactant, and the coupling agent on the shape and stability of the resulting latex particles were investigated. The TEM observation indicates that among SDS, HMPC, and PVP, SDS is the best surfactant. When the content of SDS is 0. 5% and the amount of MPS is 7% in the system, the latex with obvious core-shell structure could be obtained. The average diameters of the monodispersed particles range from 182 to 278 nm, and the average number of silica beads for each composite are 1325 and 4409, respectively. The FrIR analysis shows that PS was chemically linked to silica through MPS. The thermal gravimetric analysis shows that when there is a higher silica content, the hybrid composites have a better heat resistance.

SYNTHESIS AND CHARACTERIZATION OF STRUCTURALLY WELL-DEFINED POLYMER-INORGANIC HYBRID NANOPARTICLES VIA ATRP

Atom transfer radical polymerization (ATRP) using cuprous chloride/2,2'-bipyridine (bipy) was applied to graft polymerization of styrene on the surface of silica nanoparticles to synthesize polymer-inorganic hybrid nanoparticles, 2-(4Chloromethylphenyl) ethyltriethoxysilane (CTES) was immobilized on the surface of silica nanoparticles through condensation reaction of the silanol groups on silica with triethoxysilane group of CTES. Then ATRP of St was initiated by this surface-modified silica nanoparticles bearing benzyl chloride groups, and formed PSt graft chains on the surface of silica nanoparticles. The thickness of the graft chains increased with reaction time. End group analysis confirmed the occurrence of ATRP. Thermal analysis indicated that thermal stabilization of these resulting hybrid nanoparticles also increases with polymerization conversion. The results above show that this 'grafting from' reaction could be used for the preparation of polymer-inorganic hybrid nanoparticles with controlled structure of the polymer's end groups.

Predicting quantitative structure-activity relationship of substituted 17α-acetoxyprogesterones by molecular hybridization electronegativity-distance vector

A set of novel structural descriptors (molecular hybridization electronegativity-distance vector, VMEDh) was put forward, and the quantitative structure–activity relationship (QSAR) of a series of 17α-Acetoxyprogesterones (APs) was investigated. Taking into account the effect of various hybridized orbits on atomic electronegativities, we developed the structure descriptors with amended electronegativities to build a QSAR model. The 10-parameter model based on VMEDh yields a correlation coefficient R=0.972 and standard deviation SD=0.262, which are more desirable than those of the previous molecular electonegativity-distance vector (MEDV-4) (R=0.969, SD=0.275). By stepwise multiple linear regression, several parameters are selected to construct optimal models. The 7-parameter model based on VMEDh has R=0.960 and SD=0.276; its correlation coefficient (RCV) and standard deviation (SDCV) for leave-one-out procedure crossvalidation are respectively RCV=0.890 and SDCV=0.445. The 6-parameter MEDV-4 model has R=0.946, SD=0.304, RCV=0.903 and SDCV=0.406. It is demonstrated that VMEDh has desirable estimation performance and good predictive capability for this series of chemical compounds.

HybridⅢ-50th假人颈部标定试验的影响因素研究

假人标定试验的目的是检验其是否满足性能要求,直接决定了汽车碰撞试验结果的准确性。为提高假人颈部标定试验的效率,文章从摆锤的撞击速度、蜂窝铝的数量2个方面入手,采用控制变量法设计了7组HybridⅢ-50th假人颈部标定试验,分析其对颈部标定结果的影响。结果表明:摆锤的撞击速度对D平面的最大转角和枕骨处最大力矩影响显著;蜂窝铝的数量对枕骨处的最大力矩影响显著;二者皆对摆锤的减速度有一定影响。

Si-SiC混合功率模块的低感及低热阻封装研究

功率集成模块相比于传统的离散系统,具有体积小、功率大、集成度高、寄生参数小以及频率特性好等优点,广泛用于工业传动、家用及车用空调、辅助逆变器等场合。论文以包含有整流、制动、逆变多单元结构组成的功率集成模块为例,分析Si-SiC混合模块相比于全硅模块的性能优势,提出在低损耗的基础上进一步减小封装寄生电感和封装结构热阻的优化方案,提升功率集成混合模块的封装性能。通过对母线连接端子的位置和功率芯片的衬板图形进行优化,可将混合模块逆变电路各相之间的封装寄生电感差异降低5.2%。进一步应用局部双层衬板结构以及高导热石墨烯复合材料等,当热流密度达到100 W/cm^(2)以上时,模块最高温度降幅可达10℃。论文对Si-SiC混合功率模块的低感及低热阻封装进行研究,为充分发挥SiC材料的优势提供了有益的参考。

Formation of Hybrid Ring Structure of Cyanurate/Isocyanurate in the Reaction be-tween 2,4,6-Tris(4-Phenyl-Phenoxy)-1, 3,5-Triazine and Phenyl Glycidyl Ether

Reaction products of 2,4,6-tris(4-phenyl-phenoxy)-1,3,5-triazine derived from 4-phenylphenol cyanate ester and phenyl glycidyl ether were analyzed. In addition to an isocyanurate compound and an oxazolidone compound which were well known as reaction products of cyanate esters and epoxy resins, compounds with hybrid ring structure of cyanurate/isocyanurate were determined. Gibbs free energies of the compound having hybrid ring structure of cyanurate/isocyanurate with two isocyanurate moiety were found to be lower than that of the compound with cyanurate ring structure through calculations. Calculation data supported the existence of hybrid ring structure of cy-anurate/isocyanurate. It was revealed that isomerization from cyanurate to isocyanurate occurs via hybrid ring structure of cyanurate/isocyanurate in the reaction of aryl cyanurate and epoxy.

电子封装高温焊料研究新进展

随着先进封装和第三代半导体的快速发展,具有高熔化温度、耐持久温度考验的高温焊料逐渐成为学界追逐的热点,也成为推动电子产业无铅化和升级换代等“卡脖子”问题的瓶颈。本文综述了传统高温Sn-80Au和Pb-Sn焊料、IMC焊料、纳米及纳米-微米混合焊料,提出未来高温焊料在成分上必将以金、银、铜、铝等金属或石墨烯、碳纳米管等轻质、高导热、高熔化温度的碳基材料及其复合材料为主流;在微观尺度上,纳-微米混合焊料既具有纳米焊料的温度效应,又具有颗粒选择的灵活性,能在一定程度上解决纳米焊料的氧化、团聚及烧结时的相转变等问题;基于颗粒焊料的多尺度、颗粒种类选择的多维度,具有低温快速制备、高温长期服役的IMC高温焊料也具有极大的前途。加速高温焊料研发,突破低温封装、高温服役的技术瓶颈,必将极大推动先进封装和功率封装的快速发展。

Breeding and Cultivation Techniques of Edible Sunflower Variety AR9-9293

Edible sunflower variety AR9-9293 was approved by the Sunflower Variety Appraisal Committee with the country Identification number of sunflower 2015005. This paper introduced the breeding process, yield performance and characteristics, and the high-yield cultivation technology of new edible sunflower variety AR9-9293. The promotion of edible sunflower varieties and cultivation technology could achieve the effects of improving the level of the sunflower cultivation, promoting the development of rural and agricultural economy and increasing farmers＇ income, as well as positively promoting development of the society and adjusting agricultural industry structure.

基于FE-SEA混合法的汽车镁合金前围板隔声量数值计算

为研究中频域的结构噪声,采用有限元-统计能量分析(FE-SEA)混合法对汽车板件的隔声性能进行了研究,该方法具备适用于低频域的有限元或边界元法和适用于高频域的统计能量分析的优点.结合混合法理论,建立克莱斯勒Viper跑车镁合金压铸前围板的混合模型,验证该方法应用于汽车车身薄壁件中低频隔声量计算的可行性.对混合模型的入射侧施加混响声场(DAF)作为声激励,在透射侧施加半自由声场(SIF)作为功率接收器,由数值计算结果得到前围板中低频率范围内的隔声量曲线,与试验结果对比,表明两者结果基本吻合,从而很好地证明了有限元-统计能量混合法用于解决本模型的中频声学问题的可行性.介绍了区域声学包装法,即在隔声量曲线低谷频率范围(100～500Hz)内,将简易声学包装施加到结构表面振动速度较大处,可以有效地优化前围板的总体隔声性能.

非线性差分-微分方程的Jacobi椭圆函数解

基于椭圆函数展开法和tanh函数法,引入构造非线性离散系统行波解的方法,并给出了离散mKdVlattice方程和(2+1)-维Hybrid lattice方程的一些新的椭圆函数解.

高密度混合电路封装技术发展趋势及可靠性评价方法研究

电子产品向小型化、智能化方向演进已是必然的发展趋势,高密度集成电路封装技术是实现产品小型化的关键技术。本文对高密度混合集成电路封装技术进行了深入研究,从基板选择、结构设计和散热设计等方面对高密度混合集成电路的封装设计进行了论述。在此基础上,结合国外非气密性混合集成电路保证要求,文章进一步研究了高密度非气密混合集成电路的可靠性评价方法,并通过应用实例说明了评价方法的有效性,可作为国产化非气密性集成电路质量保证体系建设的参考。