齿轮齿面接触分析TCA技术及发展动态

通过对齿轮齿面接触分析TCA技术(利用电子计算机进行齿面接触区域的分析和修正)的研究,介绍了齿面接触分析TCA技术的基本原理、发展现状以及发展动态,阐明了TCA技术在现代工业生产中重要意义。     

Trichloroacetate affects the EPR SignalⅡslow and SignalⅠin the thylakoid of Chlamydomonas reinhardtii

One electron paramagnetic resonance (EPR) signal, named SignalⅡslow, originates from the oxidized Tyrosine 160 (YDo) of D2 polypeptide of photosystemⅡ reaction center. After adding high concentration trichloroacetate (TCA) to the Chlamydomonas reinhardtii thylakoid suspension, this signal was abolished in a minute. Treatment of TCA also removes a few of polypeptides, including three extrinsic polypeptides of oxygen-evolving complex, from the thylakoid membrane. Based upon the analysis of the microenvironment around YD with a three-dimensional model, it is indicated that relatively high hydrophobicity of this microenvironment may be the essential prerequisite for TCA to affect YD. It has been observed that TCA treatment also retards the decay of the SignalⅠ, produced by the oxidized reaction center chlorophyll dimer (P700+) of photosys- temⅠ.     

Regulation of mitochondrial aconitase by phosphorylation in diabetic rat heart

Mitochondrial dysfunction and protein kinase C (PKC) activation are consistently found in diabetic cardiomyopathy but their relationship remains unclear. This study identified mitochondrial aconitase as a downstream target of PKC activation using immunoblotting and mass spectrometry, and then characterized phosphorylation-induced changes in its activity in hearts from type 1 diabetic rats. PKCβ₂ co-immunoprecipitated with phosphorylated aconitase from mitochondria isolated from diabetic hearts. Augmented phosphorylation of mitochondrial aconitase in diabetic hearts was found to be associated with an increase in its reverse activity (isocitrate to aconitate), while the rate of the forward activity was unchanged. Similar results were obtained on phosphorylation of mitochondrial aconitase by PKCβ₂ in vitro. These results demonstrate the regulation of mitochondrial aconitase activity by PKC-dependent phosphorylation. This may influence the activity of the tricarboxylic acid cycle, and contribute to impaired mitochondrial function and energy metabolism in diabetic hearts. Received 31 October 2008; received after revision 17 December 2008; accepted 2 January 2009     

考虑齿向修形与安装误差的圆柱齿轮接触分析

提出一种齿向修形的等半径圆弧鼓形齿面新结构,根据齿向修形原理推导出等半径圆弧鼓形齿面方程,构建含安装误差的主动轮鼓形齿与未修形从动轮渐开线齿的接触分析(TCA)模型,给出TCA算法和算例.TCA计算结果表明:齿轮轴线的中心距误差对这种鼓形齿传动的接触轨迹影响很小,鼓形修形量、鼓形中心与齿宽中点的偏差及齿轮轴线的平行度误差都将对齿轮接触轨迹产生较大影响:通过调整修形参数和安装误差可以精确的预控接触轨迹的位置,这对高性能齿轮传动设计制造有较大参考价值.     

极大螺旋藻多糖提取方法研究

对TCA法和Sevag法两种螺旋藻多糖提取方法进行了比较研究,根据研究结果,指出TCA法在多糖提得率、蛋白去除率、色素去除率方面均优于Sevag法;同时对TCA法提取多糖进行了正交实验,从固液比、pH值、时间、温度4个方面进行优化组合得到了最佳提取条件：当pH值为10、固液比为1∶30、提取时间为6h、温度为90℃时达到TCA法提取多糖的最佳提取条件,多糖提得率为3.935%。     

腺苷发酵液中有机酸的代谢规律

选取了优化过程中典型的3种含有不同碳源的培养基配方(其中配方A中含有100g／L葡萄糖,配方B中含100g／L蔗糖,配方C中含100g／L蔗糖和10g／L谷氨酸),进行摇瓶发酵生产腺苷(AR),以测定发酵液的生化参数。通过研究发酵液中的有机酸与腺苷的积累在时序性上的代谢规律,在此基础上提出了通过增强TCA循环为手段以提高目的产物产量的观点,即TCA强化论假说。     

蒲公英多糖提取中脱蛋白方法的研究

研究了蒲公英多糖提取中三氯乙酸(TCA)法、酶法及TCA与木瓜蛋白酶结合脱蛋白的效果.结果表明,TCA与木瓜蛋白酶结合脱蛋白可以达到较高的脱蛋白率.蛋白脱除率可达83.18%,而糖的得率为97.59%.     

弧齿锥齿轮和准双曲面齿轮润滑加载接触分析

弧齿锥齿轮和准双曲面齿轮润滑加载接触分析将轮齿加载接触分析（ＬＴＣＡ）与热弹性流体动力润滑分析（Ｔｈｅｒｍａｌ－ＥＨＬ）有机地结合在一起。运用ＬＴＣＡ，可以得到齿轮副的接触状况，轮齿表面的几何特性，以及进行轮齿啮合表面热弹性流体动力润滑分析所需的法向载荷和运动参数等。从Ｔｈｅｒｍａｌ－ＥＨＬ的分析结果中，设计者能够得到包括油膜形成能力，油膜压力分布和温度增升等的润滑特性。在ＬＬＴＣＡ模型中，综合建立了轮齿接触和润滑特性与运转条件和齿轮加工所决定的几何特性之间的联系。     

Trichloroacetate affects the EPR Signal IIslow and Signal I in the thylakoid ofChlamydomonas reinhardtii

One electron paramagnetic resonance (EPR) signal, named Signal II_slow, originates from the oxidized Tyrosine 160 (Y_D) of D2 polypeptide of photosystem II reaction center. After adding high concentration trichloroacetate (TCA) to theChlamydomonas reinhardtii thylakoid suspension, this signal was abolished in a minute. Treatment of TCA also removes a few of polypeptides, including three extrinsic polypeptides of oxygen-evolving complex, from the thylakoid membrane. Based upon the analysis of the microenvironment around Y_D with a three-dimensional model, it is indicated that relatively high hydrophobicity of this microenvironment may be the essential prerequisite for TCA to affect Y_D. It has been observed that TCA treatment also retards the decay of the Signal 1, produced by the oxidized reaction center chlorophyll dimer (P700⁺) of photosystem I.     

斜齿轮滑动摩擦功率损失的计算

应用齿轮啮合理论,提出了斜齿轮啮合滑动摩擦功损的计算方法.首先,利用轮齿接触分析得到齿轮副的啮合路径和接触印痕:然后,利用承载接触分析求得齿面接触点法向载荷和承载传动误差,通过求解一个周期内所有啮合位置,可以得到一对轮齿从进入啮合到退出啮合所有接触点的法向载荷和承载传动误差,极大减少了计算工作量;最后,将承载传动误差转换成齿面接触点的相对滑动速度并与该接触点处的摩擦力相乘得到该点的滑动摩擦功损,将所有接触点的滑动摩擦功损一起带入功率近似计算公式从而得到斜齿轮啮合的滑动摩擦功率损失.