摘要：Topology optimization is an effective method to obtain a lightweight structure that meets the requirements of structural *** the optimization results meet the actual needs mainly depends on the accuracy of the material properties and the boundary conditions,especially for a tiny Flapping-wing Micro Aerial Vehicle(FMAV)transmission system manufactured by 3D *** this paper,experimental and numerical computation efforts were undertaken to gain a reliable topology optimization method for the bottom of the transmission ***,the constitutive behavior of the ultraviolet(UV)curable resin used in fabrication was ***,a numerical computation model describing further verified via *** optimization modeling considering nonlinear factors,***,friction and collision,was presented,and the optimization results were verified by both dynamic simulation and ***,detailed discussions on different load cases and constraints were presented to clarify their effect on the *** methods and results presented in this paper may shed light on the lightweight design of a FMAV.

摘要：为构建喀斯特山区土壤质量评价体系,通过对喀斯特山区植被退化过程中的小生境土壤进行调查,选用土面和石沟2种代表性小生境的土壤作为评价单元,用典范对应分析从29个指标中选出16个,通过因子分析法对土壤质量进行定量综合评价。结果表明:在喀斯特森林植被退化过程中,用土面和石沟2种小生境面积加权计算土壤质量综合分值,能更准确地反映植被退化过程中土壤质量的阶段性变化,具体可分为3个阶段,不同阶段之间土壤活性有机碳、碱解氮、速效磷、速效钾、有效锰、有效硫和脲酶活性出现显著降低,有效铁、蔗糖酶活性和粘粒含量出现显著增加。第Ⅰ阶段内(原生林-次生林)各土壤指标在样地间没有明显的差异;第Ⅱ阶段(灌木林)土壤活性有机碳、碱解氮、速效磷、速效钾、有效硫、脲酶活性和有效锰含量相对第Ⅰ阶段平均分别下降了33.73%、22.41%、57.66%、37.72%、44.59%、46.57%和12.52%;蔗糖酶活性及土壤粘粒含量平均分别增加了81.38%和47.69%;第Ⅲ阶段(灌草丛)土壤速效磷、脲酶活性、碱性磷酸酶活性和有效锰含量相对第Ⅱ阶段平均分别下降了42.82%、44.42%、28.45%和20.55%,土壤有效铁、粘粒含量平均分别增加了56.40%、57.49%,该阶段的土壤速效磷、速效钾含量已处于缺乏的水平,土壤质量明显下降。

摘要：Engineered sequence-specific zinc finger nucleases (ZFNs) make the highly efficient modification of eukaryotic genomes ***,most current strategies for developing zinc finger nucleases with customized sequence specificities require the construction of numerous tandem arrays of zinc finger proteins (ZFPs),and subsequent largescale in vitro validation of their DNA binding affinities and specificities via bacterial *** labor and expertise required in this complex process limits the broad adoption of ZFN *** effective computational assisted design strategy will lower the complexity of the production of a pair of functional *** we used the FoldX force field to build 3D models of 420 ZFP-DNA complexes based on zinc finger arrays developed by the Zinc Finger Consortium using OPEN (oligomerized pool engineering).Using nonlinear and linear regression analysis,we found that the calculated protein-DNA binding energy in a modeled ZFP-DNA complex strongly correlates to the failure rate of the zinc finger array to show significant ZFN activity in human *** our models,less than 5% of the three-finger arrays with calculated protein-DNA binding energies lower than 13.132 kcal mol 1 fail to form active ZFNs in human *** contrast,for arrays with calculated protein-DNA binding energies higher than 5 kcal mol 1,as many as 40% lacked ZFN activity in human ***,we suggest that the FoldX force field can be useful in reducing the failure rate and increasing efficiency in the design of ZFNs.

摘要：A recent study of significant research value carried out at the State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou,

摘要：应用锌指核酸酶(Zinc Finger Nuclease,ZFN)和序列同源的供体(Donor)作为模板,借助DNA的同源重组修复机制能够对动物基因组实现精确的遗传修饰。目前关于供体长度与ZFN介导的同源重组修复效率相关性的报道相对较少。本研究构建了一对靶向EGFP的ZFN并鉴定了活性,同时设计了一系列不同长度的供体,应用流式细胞分析术,在稳定整合了带有移码突变的EGFP基因的CHO细胞中系统分析了供体长度对ZFN介导的同源重组修复效率的影响。结果发现当同源臂单臂仅有50 bp时,即可有效支持ZFN介导的同源同组,随着同源臂长度的延伸,同源重组的效率有所提高,但要实现高效率的同源重组(较传统方法提高104倍),同源臂单臂长度需要延长至1 000 bp以上。这为今后如何设计合适的Donor,以提高ZFN等基因组编辑工具介导的同源重组效率提供了借鉴。

摘要：利用Hyper Xtrude挤压仿真软件对挤压铝型材模具进行模拟试模,并与挤压成型产品在产品变形和强度方面进行比对,发现问题及时纠错和补正后,达到尽量减少试模次数,从而降低成本的目的。

摘要：哺乳动物黑色素的合成依赖于酪氨酸的氧化作用,而酪氨酸酶(Tyr)是催化酪氨酸氧化反应的关键酶,当外源Tyr基因整合进白毛色小鼠基因组中,会使它获得黑色素合成的能力,表现出与原来不同的毛色表型。为方便、快捷地获得Tyr基因整合的小鼠,构建了一个无启动子的pTyr-2A-DsRed同源重组质粒供体,选择Rosa26的第一个内含子作为外源基因整合的靶位点,设计了切割位点几乎一致的ZFN、TALEN和CRISPR/Cas9系统。通过流式对比分析C 2C 12细胞中红色荧光蛋白DsRed的表达水平,比较了3种基因组编辑工具介导的外源基因定点整合效率,结果发现CRISPR/Cas9的效率最高,在此基础上,利用CRISPR/Cas9将供体整合到小鼠胚胎干细胞中,筛选单细胞克隆进行囊胚腔注射和胚胎移植,获得一只存活的嵌合体小鼠,表现出白毛中夹杂黑毛的表型,表明整合到小鼠Rosa26的Tyr基因可以正常表达。

摘要：针对130 t/h燃气锅炉送风系统振动大的问题,通过对送风机及风道系统的振动机理进行探讨,找出振动的主要原因是风道内气流不均匀导致局部涡流,改造后风机出现旋转脱流及形成二次流。采取送风系统加固及改变送风机出口扩散弯管等措施,其振动有所下降。建议从送风机选型与规范风道设计方面进行治理,达到根本消除风道振动的目的。

摘要：随着风能发电规模的不断扩大,风机变桨电机温升故障频发。传统风机变桨电机温升故障预警方法由于故障预警限值计算能力较差,导致在故障预警时及时性较差且无法确定故障位置。针对上述问题,设计基于TF-IDF模型的风机变桨电机温升故障预警方法。使用历史数据库以及小数缩放技术,完成风机变桨电机温度趋势监测。对数据进行预处理,使用TF-IDF模型捕捉故障数据并提取特征值。采用风速-温度曲线结合区间温度划分结果设定风机变桨电机温升故障预警限值。至此,基于TF-IDF模型的风机变桨电机温升故障预警方法设计完成。构建实验环节,选定电机退化情况以及故障位置确定能力作为对比指标。通过与传统方法对比可知,此方法在电机退化情况以及故障位置确定能力实验中所得结果优于传统方法。综上可知,此方法的故障预警能力优于传统方法。

摘要：深入研究两套直流电源环网的接线形式与特点,根据环网接线的规律,开发一套在线环网监测设备,一旦出现环网故障,装置能即时发出告警提示。