Low concentrations of NaHSO3 enhance NAD(P)H dehydrogenase-dependent cyclic photophosphorylation and alleviate the oxidative damage to improve photosynthesis in tobacco

Bisulfite at low concentrations(L-NaHSO3) increases cyclic electron transport around photosystem I(PSI) and photosynthesis.However,little is known regarding the detailed contribution of cyclic electron transport to the promoted photosynthesis by L-NaHSO3.In the present work,we used tobacco mutant defective in ndhC-ndhK-ndhJ(ndhCKJ) to investigate the role of NAD(P)H dehydrogenase(NDH)-dependent cyclic electron transport around PSI in an increase in photosynthesis by L-NaHSO3.After the treatment of tobacco leaves with L-NaHSO3(10 μmol L-1),the NDH-dependent cyclic electron transport,monitored by a transient post-illumination increase in Chl fluorescence and the amount of NDH,was notably up-regulated in wild type(WT).The NDH-dependent cyclic electron transport was severely impaired in ndhCKJ and was not significantly affected by treatment with L-NaHSO3.Accordingly,the NDH-dependent transthylakoid membrane proton gradient(pH),as reflected by the slow phase of millisecond-delayed light emission(ms-DLE),was increased by L-NaHSO3 in WT,but not in ndhCKJ;the enhancement of cyclic photophosphorylation(PSP) activity by L-NaHSO3 was more obvious in WT than ndhCKJ.The accumulation of both superoxide and hydrogen peroxide was reduced in WT when subjected to L-NaHSO3 treatment,but not in ndhCKJ.Furthermore,the increase of photosynthetic O 2 evolution rate by L-NaHSO3 was more significant in WT than in ndhCKJ.We therefore conclude that L-NaHSO3 alleviates the photo-oxidative damage by the enhancement of NDH-dependent cyclic PSP,thereby improving photosynthesis.     

一种带验证和撤销的组密钥分发方案

提出一种在无线传感器网络中具有正确性验证和头结点撤销功能的组密钥更新方案. 通过建立组密钥之间的冗余关联,实现了在不增加结点负担的情况下,合法结点利用当前广播消息和自身秘密恢复丢失的组密钥. 利用撤销多项式实现对结点和头结点的撤销,此外还能提供密钥的正确性验证. 分析表明,在没有增加计算开销和通信开销情况下本方案具有更好的安全性.     

大功率LED阵列散热结构热分析

在自然对流冷却状态下,不同的散热结构对大功率LED阵列散热性能有显著影响。采用有限元分析法,对不同散热模型进行了分析并得到工作稳定时的热分析图;对比直片形、弧形、弧钉形散热结构的散热效果,逐步得出弧钉形散热结构散热效果最好,使得空腔以及芯片处温度均在合适的范围内,灯具的使用寿命达到近40000h。另外,模拟得出在普通散热设计中,灯具适合的功率约为13．75w。通过有限元法仿真模拟得出较为合理的结果,有效地减少了实验损耗。     

级联型多电平变换器单元电路控制策略仿真

针对级联型多电平变换器需要四象限运行的工况,提出以双H桥的电压胞拓扑作为多电平变换器单元电路的方案。其前H桥为整流器,采用滞环电流控制策略实现直流电压稳定和近似单位功率因数的双向能量流动;后H桥为逆变器,采用载波相移SPWM技术。通过建立整流器的滞环电流控制模型和三单元级联多电平逆变器相移技术控制模型,对变换器进行双向能量传输运行的过渡过程分析和逆变器输出级联电压波形分析。仿真结果表明该拓扑及控制策略满足四象限运行要求。     

新型双羟乙氨基硝基型偶氮分子的合成、光学非线性和热稳定性

设计和合成了2种双羟乙氨基给体和硝基受体有效组合的新型偶氮分子,采用核磁共振、红外光谱、紫外光谱及熔点测定对化合物进行表征,研究化合物的热稳定性、线性和非线性光学性质.用熔致变色法测定这2种化合物的非线性极化率,分别为140×10-30esu 和351×10-30esu;热分解温度分别达到291.93 ℃和302.36 ℃,这2种非线性光学生色分子表现出较大的光学非线性和良好的热稳定性.     

Kinetics of discontinuous precipitation in Cu–20Ni–20Mn alloy

The morphology and growth kinetics of discontinuous precipitation (DP) in a Cu–20Ni–20Mn alloy were investigated in the temperature range of 523–673 K by optical microscopy, scanning electron microscopy, and transmission electron microscopy. A lamellar mixed structure consisting of alternating lamellae of a matrix and NiMn phase was observed in DP colonies. The volume fraction of regions formed by a DP reaction was determined by quantitative metallographic measurements. The kinetics of DP was evaluated on the basis of the Johnson–Mehl–Avrami–Kolmogorov equation, which resulted in a time exponent of approximately 1.5. We confirmed that the nucleation of the discontinuous precipitate was confined to grain edges or boundaries at an early stage of the reaction. The activation energy of DP process was determined to be approximately (72.7 ±7.2) kJ/mol based on the Arrhenius equation; this result suggests that DP is controlled by grain boundary diffusion. The hardness values exhibited good correlation with the volume fraction of DP; this correlation was attributed to the presence of the ordered NiMn phase.     

社会地位、财政政策和随机经济增长

在一个具有生产性政府花费的随机经济增长模型中,把体现社会地位的财富引入消费者效用函数．在政府发行债券的情况下,利用随机最优化方法,确定了均衡状态下的消费一财富比、期望经济增长率以及资本和债券份额．讨论了社会地位、财政政策和随机扰动对经济增长的影响．同时,考察了社会地位对财政政策的制定是否有影响的问题．     

基于GPP平台的LTE上行信道估计高效实现

处理的实时性是基于GPP(general purpose processor)平台的LTE基站系统的关键指标。在上行信道估计环节,往往需要维纳插值来获得良好性能;但其过高的计算复杂度使信道估计成为上行物理信道实时性处理的计算瓶颈,需要结合GPP特点进行算法实现的优化。通过引入部分线性插值和预存维纳插值系数的方式,显著降低维纳插值的运算复杂度。再使用SSE指令集和"流水线"处理的优化,在保持性能基本不变的情况下,在单核处理器上处理100个物理资源块的上行信道估计仅需6.36μs,为优化前的1.5%,使得高性能上行信道估计不再成为GPP软件无线电实时处理的瓶颈。     

基坑开挖扰动变形特征及控制效果模拟分析

坑中坑的开挖对于基坑的稳定性有诸多方面的影响,内坑的开挖会造成土体回弹,引起基坑土体抗力的损失,降低基坑的整体稳定性。运用FLAC^3D对合肥恒大中心C地块坑中坑式基坑进行了开挖与支护模拟,计算采用摩尔-库伦本构模型,通过模拟计算得出了基坑应力、桩基应力、桩锚应力,验证了基坑中外坑和内坑最易失稳破坏区域,并对利用负泊松比(negative Poisson’s ratio, NPR)锚索对该类基坑进行加密支护的控制效果进行了评价。通过施加位移监测得到了不同开挖阶段基坑地表位移、坑中坑底部位移、以及坑中坑周围土体位移,确定了基坑极易发生破坏的区域以及滑动面位置,建立了坑中坑物理模型,并验证了数值模拟的正确性,研究结论可为类似工程条件基坑的开挖及加固提供理论支撑和实践基础。     

基于有限元的非共线边裂纹相互影响研究

薄壁结构是飞机中常用的工程结构。薄板中裂纹将直接影响结构的剩余强度。当薄板结构含有多个裂纹时,其强度分析过程复杂。利用有限元分析方法对含有两等长非共线边裂纹的有限宽板进行了系统分析。通过与共线边裂纹情况对比,提出了合适的应力强度因子K_Ⅰ的修正系数F_1。同时,分析了裂纹相对位置对应力强度因子K_Ⅱ的影响,当两裂纹相对方位角为18.8°时,K_Ⅱ取最大值,而该最大值的大小仅仅与板宽w与裂纹长度a的比值w/a有关。结果为估算含有该类裂纹结构的剩余强度及裂纹扩展行为提供方便快捷的方法。