Influences of Y on the microstructures and mechanical properties of Mg-12Gd-1Zn-0.6Zr magnesium alloys

To develop Mg-Gd-Y based high-strength alloys and widen the application of magnesium alloys, the effects of Y addition on the microstructure and mechanical properties of Mg-12Gd-1Zn-0.6Zr alloy are investigated by using both optical and electron microscopy,X-ray diffraction (XRD),differential scanning calorimetric (DSC) analysis,and tensile test．The results indicate that adding 2%Y to the Mg-12Gd-1Zn-0.6Zr alloy does not cause an obvious change in the as-cast microstructure of the alloy. However,after adding 3%and 4%Y,the as-cast microstructure of the alloy is coarsened,and simultaneously the morphology of the secondary phases in the alloy is changed from the initial discontinuous fine network to thick skeleton-like frame. Furthermore,adding 2%-4%Y to the Mg-12Gd-1Zn-0.6Zr alloy can also refine the grains of the as-extruded alloy,and adding 2%and 3%Y can obtain higher refining efficiency than adding 4%Y. In addition,adding 2%-4%Y to the Mg-12Gd-1Zn-0.6Zr alloy can also effectively improve the ultimate tensile strength and yield strength of the as-extruded alloy,and the ultimate tensile strength,yield strength and elongation of the as-extruded alloy with the addition of 2%Y can reach 348.8 MPa,256.8 MPa and 14.7%,respectively.     

水稻白叶枯病抗性基因和相关因子研究利用进展

水稻白叶枯病严重制约水稻生产,抗病基因的发掘与利用是目前防治该病害最环保有效的手段。为高效发掘、研究和利用抗白叶枯病基因,本文概述了白叶枯病菌与水稻的互作机制,总结了抗白叶枯病基因的定位与克隆现状并对其功能类型加以分类,归纳了抗病相关因子的研究进展。针对目前抗白叶枯病基因的研究进展缓慢且概述性研究报道相对滞后的现状,提出研究展望,认为应更深入研究水稻抗白叶枯病基因的定位克隆与利用,并大力探究抗病基因与抗病相关因子的协同作用关系。     

结球甘蓝雌蕊调控因子SPT与HEC1的克隆及相互作用分析

为研究SPT和HECs及其相互作用对甘蓝雌蕊发育的影响, 以结球甘蓝自交不亲和系E1为材料, 提取雌蕊总RNA, 根据拟南芥中SPT和HEC1基因设计引物, 采用同源克隆的方法克隆SPT基因, 其序列1085 bp, 开放阅读框(ORF) 1062 bp; HEC1基因ORF 696 bp。通过cDNA推导得到的氨基酸序列表明, SPT编码353个氨基酸残基, 预测分子量为37.67 kD, pI为6.83; HEC1编码231个氨基酸残基, 预测分子量为25.26 kD, pI为10.2。分析表明, 两基因在各器官中均表达, 但SPT在果实和雌蕊中表达量最高, 而HEC1在根和花蕾中的表达量最高。为检测两者的相互作用, 构建原核表达质粒pCold I-SPT和pGEX-HEC1, Pull-down试验表明两蛋白能够在体外相互作用。同时构建pGBKT7-SPT、pGADT7-HEC1及互换载体pGBKT7-HEC1和pGADT7-SPT酵母表达载体, 分别转化酵母Y2HGold和Y187感受态细胞后均未出现自激活和毒性现象, 融合后的二倍体酵母均能在SD/–Trp–Leu–Ade–His/X-α-gal/AbA板上长出蓝色菌斑, 表明SPT和HEC1能够相互作用激活下游的HIS3、AUR1-C、MEL1和ADE2报告基因, 酵母双杂交试验结果与Pull-down检测一致, 说明SPT和HEC1能够相互作用以调控雌蕊的发育。     

大蒜茎粉和牛至草粉对镜鲤抗氧化、非特异免疫以及肌肉品质的影响

试验研究了大蒜茎粉和牛至草粉对镜鲤(Cyprinus specularis)抗氧化能力、非特异免疫性能及肌肉品质的影响。试验共设7个处理组:G1空白对照组,G2添加黄霉素10 mg/kg,G3、G4分别添加大蒜茎粉0.5%和2.5%,G5、G6组分别添加牛至草粉0.1%和0.5%,G7混合添加大蒜茎粉0.5%和牛至草粉0.5%。每个处理设3个重复,每个重复10尾鱼,初始体重为(201.45±16.25)g,试验共进行8周。结果表明:与G1空白组对比,G3、G4和G6显著提高了肝胰脏SOD活性(P0.05),G3、G4显著降低了血清MDA含量(P0.05),G5、G6显著降低了肝胰脏MDA含量(P0.05)。与G1空白组对比,G5、G6和G7显著提高了脾脏溶菌酶活性(P0.05),G3、G4和G5、G6显著提高了血清溶菌酶活性(P0.05),G3和G5显著提高了血清补体3、补体4活性(P0.05)。与G1空白组对比,G3、G4、G5和G6显著提高了鱼体肌肉粗蛋白质含量,G4和G7显著提高了肌肉持水能力(P0.05);各试验组肌肉粗水分、pH值和嫩度无显著差异(P0.05)。在饲料中添加大蒜茎粉和牛至草粉提高镜鲤非特异免疫性能,改善鱼体肌肉品质。     

Numerical simulation and experimental analysis for process parameters of cold straightener

This paper focuses on the design of eleven rollers straightener. An elastic plastic FEM model is introduced to cope with the difficulty of pre estimating the performance of straightening during the design process. To obtain straightening force, stress, strain, elastic plastic ratio, relations between reduction amount of roller and roughness of plate per square meter, a three dimensional element model is established and straightening process is simulated. In addition, an experiment is conducted to measure the reduction amount of roller and the roughness of plate per square meter. It is shown that the results of numerical simulation are consistent with the experimental results. The developed computing model can provide essential references for the optimization of straightener.     

Dynamic characteristics of CVT hydraulic system in speed ratio changing

Aiming at the hydraulic system of CVT (Continuously Variable Transmission), the transfer function of hydraulic system of CVT and the dynamic simulation model of this system based on AMESIM are built, and the characteristics of speed ratio response is simulated and calculated. The influences of spring constant, damping coefficient and mass of moving part on rising time, setting time and overshoot are analyzed. The result shows that the dynamic simulation model of this system is reasonable and will provide a basis and method for the optimization of CVT hydraulic system’s dynamic characteristics in the future.     

Numerical simulation on multi jet diffusion combustion of low concentration coal bed methane

It is important to utilize coal bed methane to achieve the safe, environmental and economic benefits. The authors simulate the processes of multi jet diffusion combustion of low concentration coal bed methane using k ε turbulence model,non premixed combustion model and P1 radiation model. The influences of different geometrical structures and operating parameters on the combustion process are compared with each other. The results show that the distance between the gas nozzles and central axis,the angle of gas deflected from air ,the velocity ratio of air to gas have important impacts on the combustion. When the distance, the deflection angle and the velocity ratio are 30 mm,45 °and 2, respectively. The best combustion result can be achieved.     

Novel strategy for subcarrier and power allocation in OFDM based cognitive radio networks

In order to limit the interference caused by cognitive user within the range that primary users can tolerate. The mathematical optimization problem is formulated maximizing cognitive user’s capacity under the interference constraint at the primary receiver．When the signal to noise ratio of primary user changes according to the communication environment, the cognitive user can adaptively adjust its transmission power according to the interference control factor η. The optimal so1ution to the problem is obtained by utilizing the Lagrange method．A subcarrier and power allocation scheme are proposedamong multiple cognitive users, which is the performance tradeoff between fairness and system capacity. Simulation results show that the proposed scheme can efficiently guarantee the fairness of cognitive users and the capacity performance is close to the optimum.     

Power supply and electromagnetic simulation of implantable medical devices

It is studied how to charge the battery of the implanted medical device through the skin according to its bio electrical characteristics.Energy delivery model of volume conduction is created by FEMlab 3.3 (Finite Element Model Lab),using AC voltage as the input.In simulation,the frequency characteristic of the model is tested,and then 4 different shapes of electrodes are designed.Taking cylindrical electrode for example,the shape and layout of electrode are optimized by changing the electrodes’ cross section areas and the distance between the electrodes.According to the simulation results,current transmitting efficiency can reach above 30% under the premise of ensuring human security.     

Application of improved FAHP in schemes optimization about landslide treatment

Based on the landslide control scheme optimized by considering technical index and other factors,a landslide comprehensive control thought of “treating scheme optimization combined monitoring information feedback” is put forward.The multi level hierarchical comprehensive evaluation index on landslide control scheme is set up on the basis of analyzing many engineering examples,and formula of weight,fuzzy complementary judgment matrix and the consistency check method of judgment matrix of fuzzy analytical hierarchy process are given,the solution of multi objective decision problems based on improved fuzzy analytical hierarchy process is developed,too.Validity and reliability of this method is proved through the scheme selection for Xiangjiapo landslide control.It provides an effective method for construction decision makers.