流动激光腔中饱和增益的基本变化规律

本文给出在流动激光腔(GDL)中饱和增益系数随场分布沿流动方向变化的基本规律。联系到各振型振动能和振动温度的变化,用激活介质弛豫过程的物理机制对这些规律作了诠释,因而指出例如 Gerry 的单模输出30千瓦的器件还有相当多的可被利用的振动能

废橡胶和废纸热解过程NOx前驱体的生成

在固定床反应器中热解废橡胶和废纸,考察在不同热解终温和加热方式下NOx前驱体（HCN和NH3）的生成特性.研究结果表明,随着热解终温的升高,原料中的N转化为HCN和NH3的比例不断增加.以废橡胶为例,HCN和NH3的产率从400℃的0.5%分别增加到1 000℃的7%和9%;加热方式对HCN和NH3的产率有明显的影响.实验条件下,非等温热解时,废橡胶在所有热解温度下HCN和NH3的产率均高于等温热解时的产率

银纳米立方体的合成及其SERS活性研究

用乙二醇还原硝酸银,以聚乙烯吡咯烷酮作表面活性剂合成了银纳米立方体晶粒,并以吡啶和SCN-作为探针分子初步研究了银纳米立方体晶粒组装体系的SERS活性。当探针分子吸附于银纳米立方体晶粒上时,吡啶和SCN-的谱峰强度明显增强,表明银纳米立方体晶粒可望作为SERS活性基底。通过研究探针分子的SERS强度与粒子尺度关系,也有望用于表征银纳米立方体晶粒的光学性质

多酶级联反应催化的环氧醇立体互补性差向异构化

动态动力学拆分是制备光学纯手性中间体的重要手段之一。本研究以光学纯的多手性中心的缩水甘油醇为目标产物,将苯乙烯单加氧酶(SMO)与两个醇脱氢酶/羰基还原酶(ADH)共表达于大肠杆菌BL21中,构建了整细胞催化的多酶级联反应体系。其中苯乙烯单加氧酶负责选择性地向底物中引入手性环氧基团,而一对羰基还原酶进一步完成对羟基的差向异构化(Fig.1)。该多酶级联反应体系高效运转的重点是还原型辅酶对反应体系的调控作用。还原型辅酶I(NADH)参与的环氧化作用(Step1)与氧化型辅酶I(NAD~+)参与的脱氢反应(Step2),不仅实现了辅酶I的自循环,控制了反应顺序,还将还原型辅酶II(NADPH)参与的还原反应(Step3)与前两步反应"隔离"开,实现了对仲醇的动态动力学拆分。三步串联反应有序进行,互不干扰,使目标产物的理论产率可以达到100%。以三个酶共表达的休止细胞为催化剂,检测了该级联反应体系对12种底物的转化情况,1-2小时内产率36%至>99%,大多数情况下具备优异的对映体及非对映体选择性。运用两对选择性和辅酶适应性互补的羰基还原酶分别与苯乙烯单加氧酶组合得到两个立体互补性的催化系统,可以分别获得S-和R-手性醇,最终实现了环氧醇立体互补性差向异构化,为多手性基团有机砌块的合成提供了新思路

连续可调纳秒级窄脉冲半导体激光器模块

本发明公开了一种连续可调纳秒级窄脉冲半导体激光器模块，该激光器模块由驱动电路、半导体激光器和管壳构成，该驱动电路驱动该半导体激光器发光，且该驱动电路和该半导体激光器被封装在侧面至少具有一光窗的管壳内。利用本发明，减小了寄生效应带来的影响，得到了高峰值功率和良好波形的激光输出，提高了半导体激光器整体的可靠性

SERS Mechanism for Rhodium Electrode in the Ultraviolet Region

【中文文摘】采用波长为 32 5nm的He Cd激光为激发光源 ,首次在粗糙铑电极上获得了高质量的表面增强拉曼信号。基于在紫外区获得SERS信号这一进展 ,以电磁场理论为基础 ,分别从定性和定量的角度对此新的实验结果做了理论分析。分析表明 ,在紫外区获得的铑的SERS信号主要源自于有着特定形貌的铑纳米粒子所引起的避雷针效应及微弱的表面等离子体共振效应的共同作用。对铑纳米粒子的表面平均SERS增强因子的计算结果与实验值较为一致 ,约为两个数量级。我们同时比较分析了在可见光及近红外区有着极佳SERS增强效应的银基底在采用 32 5nm激发光时却得不到任何SERS信号这一实验结果 ,这是因为银在此紫外区间已完全不能满足表面等离子激元共振的条件所致 【英文文摘】Stable and good quality of Surface Enhanced Raman Scattering (SERS) signal from net rhodium electrode in the ultraviolet region was observed for the first time by our group recently. In this paper, both qualitative and quantitative analyses are given to interpret the new experimental results mainly based on the electromagnetic field theory. The mechanisms of SERS for rhodium electrode in the ultraviolet region are mainly attributed to the lightning rod effect together with the weak surface plas...国家自然科学基金 (2 0 0 2 1 0 0 2 ;;2 0 2 2 80 2 0 )资

Securely redundant scheduling policy for MapReduce based on dynamic domains partition

MapReduce现有调度策略无法实现云环境中多租户作业的安全隔离。提出一种基于动态域划分的安全冗余调度策略：通过引入冲突关系、信任度、安全标签等概念，建立一种动态域划分模型，以将待调度节点划分为与不同租户作业关联的冲突域、可信域或调度域；结合冗余方式，将租户作业同时调度到其可信域节点和调度域节点(但不允许为其冲突域节点)，通过二者执行环境和部分计算结果的一致性验证决定是否重新调度。实验分析了其有效性和安全性。 MapReduce’s current scheduling policies could not ensure the isolation between multi-tenant Tasks in the cloud. A securely redundant scheduling policy based on dynamic domains partition was proposed. First, a kind of dy-namic domain partition model was introduced in this policy. Based on the node’s current belief, security labels with the conflict relationship between tenants, a computing node was partitioned into the conflict domain, trusted domain or schedulable domain in this model. Second, through redundantly computing, two copies of each Task were assigned re-spectively to its trusted domain node and its schedulable domain node (but not allow for its conflict domain node) in this policy. And the integrity of the two nodes’execution environments and the consistence of their results on a small part of original input data were verified. Accordingly, it decided whether the schedulable domain node was trusted. Finally, the performance and security analysis in the prototype show its effectiveness.MapReduce's current scheduling policies could not ensure the isolation between multi-tenant Tasks in the cloud. A securely redundant scheduling policy based on dynamic domains partition was proposed. First, a kind of dynamic domain partition model was introduced in this policy. Based on the node's current belief, security labels with the conflict relationship between tenants, a computing node was partitioned into the conflict domain, trusted domain or schedulable domain in this model. Second, through redundantly computing, two copies of each Task were assigned respectively to its trusted domain node and its schedulable domain node (but not allow for its conflict domain node) in this policy. And the integrity of the two nodes' execution environments and the consistence of their results on a small part of original input data were verified. Accordingly, it decided whether the schedulable domain node was trusted. Finally, the performance and security analysis in the prototype show its effectiveness

银和去合金银-金纳米粒子的SERS活性研究

用乙二醇还原硝酸银,聚乙烯吡咯烷酮作表面活性剂合成了大量的银纳米颗粒。银纳米颗粒和HAuCl4发生置换反应后形成去合金银-金纳米粒子。以吡啶和SCN-作为探针分子研究了它们的SERS活性。结果表明,当探针分子吸附于银纳米颗粒和去合金银-金纳米粒子上时,探针分子的特征振动峰强度增强、频率发生位移。SERS可表征纳米粒子物理和化学性质的变化