绵羊miR-200b对卵泡颗粒细胞周期和凋亡的影响

旨在揭示miR-200b在绵羊卵泡颗粒细胞的作用。本研究利用在线工具（TargetScan、miRTarBase及miRDB）预测miR-200b的靶基因,并利用KOBAS对其进行GO和KEGG通路富集分析。将分离培养的绵羊卵泡颗粒细胞分为4组,分别转染miR-200b mimic、mimic NC、miR-200b inhibitor和inhibitor NC,每组6个重复。采用CCK8法分别检测转染24、48和72 h颗粒细胞的存活率;采用荧光定量PCR检测miR-200b、CDK4、CDK6、CCND1、CCND2、Bax和Bcl-2基因的表达水平。利用3种在线工具预测到25个miR-200b的共同靶基因,GO和KEGG通路富集分析发现这些基因富集在细胞的增殖分化、细胞周期及生殖发育过程;转染miR-200b mimic、miR-200b inhibitor和NC后,颗粒细胞存活率随时间延长呈“V”型趋势降低,且48 h达最低（P<0.01）;miR-200b inhibitor与inhibitor NC组相比,miR-200b表达量无显著差异（P>0.05）;与mimic NC相比,miR-200b mimic组极显著促进miR-200b表达（P<0.001）,显著下调CDK4（P<0.01）、CDK6（P<0.001）和CCND1（P<0.001）、CCND2（P<0.05）和Bcl-2（P<0.01）基因表达水平,Bax表达并无显著变化（P>0.05）,且极显著下调Bcl-2与Bax比值（P<0.001）。综上所述,miR-200b抑制绵羊卵泡颗粒细胞细胞周期和增殖并促进其凋亡。     

Dichlorodiphenyltrichloroethane determination in air by thermal desorption gas chromatography-mass spectrometry

BACKGROUND: Current quantitative methods for airborne dichlorodiphenyltrichloroethane (DDT) require collection and extraction times of ≥ 12 h. The aim of this study was to develop a method for quantifying airborne DDT with a short (<4 h) collection and analysis time. RESULTS: Precision [relative standard deviation (RSD)] for each calibration point (0.8–9.0), linearity (R² = 0.99) and apparent recovery (R′ = 96.5%) were determined from thermal desorption (TD) gas chromatography–mass spectrometry (GC-MS) analyses of Tenax-TA-packed sampling tubes spiked with 1–250 ng of DDT. Recovery of ¹³C-labeled 4,4′-DDT from tubes spiked before and after air sampling was 97.3 and 90.3% respectively. DDT was detected and quantified in 1–3 L samples of air collected during 10–180 min sampling events. A significant difference was observed in DDT air concentration between 28 and 33 °C during microchamber studies. CONCLUSIONS: The results demonstrate that the TD GC-MS method developed in this study is precise, reproducible and linear over the span of 1–250 ng of DDT spiked onto TD tubes. By avoiding dilution of the sample, the method described allows the measurement of DDT vapor concentrations during short sampling periods (10–180 min) relevant to mosquito behavior studies. Published 2012 by John Wiley & Sons, Ltd.     

S7-300与S7-200通信问题探讨

本文主要探讨S7-300和S7-200通过MPI协议和通过Profibus DP协议进行通信的方法,并对两种通信方式进行比较。通过比较可以发现,MPI通信不需要额外添加硬件,但软件设置复杂,通信速率慢;Profibus DP通信需要添加EM277模块,但软件设置简单,通信速率快。     

饮水高氯诱发肉鸡胫骨软骨发育不良的试验研究

２４０羽健康ＡＡ肉鸡随机均分为对照组，试验１组，试验２组。从８日龄志分别饮用含Ｃｌ０．０％、０．０９％、０．１８％的饮水以观察肉鸡胫骨软骨发育情况，同时对其进行了Ｘ射线、骨密度、血清学和形态学的研究。结果表明：（１）饮水高氯可增加胫骨软骨发育不良的发病率。（２）３周后病鸡胫骨近端的Ｘ射线可透区与软骨增生区的形态一致，其承重侧的骨皮质增厚。（３）试验组鸡的胫骨骨密度较对照组稍高，但差异不显著。骨密度     

油菜200kg/667㎡轻简化栽培模式研究初报

运用L9(34)正交试验设计,研究皖中地区油菜667㎡产200kg以上的轻简化栽培模式.结果表明:最佳方案为巢油08品种在9月10日播种,移栽密度为3600株/667㎡,施氮量20kg/667㎡(A3B1C3D3)的处理产量可达260kg以上.     

基于北斗定位的小麦播种机控制系统优化

以西门子S7-200 smart PLC为控制器,通过对基于步进电机的分种器的控制,实现了小麦小区播种机控制系统的设计。采用北斗定位辅助取代了以往误差较大的编码器测距,实现了对作业小区的精准控制,控制精度达到厘米级。目前,PLC内部浮点数存储格式为8位单精度浮点数,而接收到的北斗GPGGA数据有效数值为16位双精度浮点数,直接转化误差非常大。为确保计算精度,提出了一种基于三角恒等式的数值分段法来解决双精度浮点数转单精度浮点数的问题。经测试,精度到达微米级。     

联合收获机传动带稳态温度场预测与试验

传动带是联合收获机的关键传动部件,在联合收获机高强度作业过程中会出现因温度升高加剧橡胶老化、表面硬化及磨损开裂等现象。针对传动带稳态温度场分布计算问题,提出了一种基于动力学模型和有限元仿真计算的传动带稳态温度场预测方法。首先,在AVL Excite TD软件中通过设置带轮的物性参数、带的动态特性参数、张紧机构摩擦和扭转参数、驱动和负载参数,构建了传动带温升热源计算模型。其次,通过分析传动带热平衡方程、确定热流分配系数和对流换热条件,建立其二维稳态温度场有限元预测模型。再次,基于联合收获机CAN总线,开发了传动带工况采集系统。最后,以GM80型小麦收获机发动机动力输出轴与后中间轴之间的联组带为对象,开展了传动带稳态温度场预测田间试验。试验结果表明：当主动轮平均转速2244r/min、从动轮平均负载338N·m时,实测稳态温度为42.55℃,仿真稳态温度为41.7℃,稳态误差为1.97%;当驱动轮平均转速2244r/min、从动轮平均负载382N·m时,实测稳态温度为45.95℃,仿真稳态温度为45.2℃,稳态误差为1.63%。两次试验的稳态误差均小于2%,验证了联合收获机传动带稳态温度场预测方法的可行性与准确性。     

Computation of Scattering of Electromagnetic Waves from Absorbing Coating Using the Finite Difference Time Domain Method

In this paper,we derive the necessary extension to the FD TD(finite difference time domain) method for absorbing coating of composite material.The scattering of electromagnetic waves(EW) from absorbing coating is considered,and the comparision of obtained results with exact analytic ones shows that the method used in this paper is correct and available.     

Construction of substitution boxes based on tangent delay ellipse reflecting cavity mapping system

Based on the good chaotic properties of tangent delay ellipse reflecting cavity mapping system (TD ERCS), a kind of novel substitution boxes were constructed. The cryptographic properties, such as bijection, nonlinearity, strict avalanche, independence of output bits, the differential approximation probability and the nonlinear approximation probability of the S box are analyzed. The investigation method for the strength of the S box with the discrete chaotic system proposed by Kocarev is discussed. Theoretical analysis and backtesting results show that the method is efficient and easy to put into practice, while the constructed S boxes show better cryptographic properties than the S boxes based on other chaotic system, which can be used to improve the existing encryption scheme.     

双季水稻叶片温度变化规律及其与产量关系的研究

为了研究水稻叶片温度与产量关系,以双季早晚稻12个品种为材料,2008-2009年应用红外测温仪记录叶片温度,并分析大气温度、气叶温差与产量的关系。结果表明,水稻叶片温度的日变化呈单峰曲线,变化幅度小于气温;在不同生育阶段品种间气叶温差存在明显差异。各生育时期14:00点的气叶温差与产量呈正相关关系,抽穗期的相关程度最高;抽穗期和抽穗后的剑叶日平均温度与产量呈负相关,剑叶的日平均气叶温差与产量呈正相关;超级稻的气叶温差高于非超级稻。