Visible Light‐Initiated C(sp3)?Br/C(sp3)?H Functionalization of α‐Carbonyl Alkyl Bromides through Hydride Radical Shift

A new visible light‐initiated 1,5‐hydride radical shift strategy has been developed to enable the one‐step functionalization of both a C(sp³) Br bond and a C(sp³) H bond adjacent to the same carbon atom. This visible light photoredox catalysis offers a mild and straightforward access to diverse five‐membered carbocyclic ring‐fused polycyclic hydrocarbons with high turnover numbers (TONs; up to 4.93×10³) and broad substrate scope.

     

Synthesis of Polymer Nanospheres Conjugated Ce (IV) Complexes for Constructing Double Antibacterial Centers

Journal of Inorganic and Organometallic Polymers and Materials - The antimicrobial materials are rapidly emerging as a primary component in mitigation of bacterial pathogens, and functional...     

Numerical Modeling and Experimental Study of Laser Assisted Machining of Fused Silica

Silicon - Fused silica is a kind of high-strength optical material, which is widely used in industry. It is slow and inefficient to process hard and brittle materials by conventional machining (CM)...     

Numerical modeling of the 2008 Wenchuan earthquake-triggered Niumiangou landslide considering effects of pore-water pressure

Bulletin of Engineering Geology and the Environment - Ring-shear experiments are commonly conducted to analyze the kinematic mechanisms of landslides triggered by earthquakes, particularly for...     

数控铣削编程中的几种补偿

笔者介绍数控铣床在进行加工时,利用补偿的方法来解决生产中的实际问题。数控铣削加工中有三种补偿,基本解决了加工中因刀具尺寸、形状而产生的轨迹问题。     

球坐标系下中子输运方程泄漏项的简便推导

采用一种恰当的方法,简便地推导出中子输运方程泄漏项在球坐标系下的表达式,该方法避免直接寻求二面角与中子飞行距离之间的复杂微分关系,转而寻求二面角与其他平面角之间的几何关系,再利用其他平面角与中子飞行距离之间的微分关系(通常是已知的或比较容易推导得到),便可间接推导出中子输运方程泄漏项在球坐标系下的表达式。该方法与传统方法推导得到的表达式完全一致,且推导过程直观、物理图像清晰。     

酶解刺参内脏蛋白制备抗氧化肽的研究

对刺参内脏所含的内源蛋白酶的性质进行了初步研究,在此基础上分析和比较了利用内源蛋白酶和外源蛋白酶酶解内脏蛋白制备抗氧化肽的工艺。刺参内脏主要含有四种内源蛋白酶,最适pH分别为2.0、5.0、8.0和12.0。以羟自由基和超氧阴离子自由基清除率为指标,比较了内源蛋白酶和八种外源蛋白酶酶解内脏蛋白制备抗氧化肽的效果,结果表明菠萝蛋白酶为最佳用酶;用正交实验L9(34)对其水解条件进行优化,确定最佳酶解条件为:pH7.8、温度35℃、加酶量5.0g/100g、酶解时间1h,在此条件下所得酶解液对羟自由基和超氧阴离子自由基的清除率分别为79.15%和28.57%。      

不同鸡龄鸡血清中乙酰胆碱酯酶酶活力的比较研究

实验从发育的角度出发,探讨了血清中乙酰胆碱酯酶的含量、活力与家禽个体发育之间的关系。选取不同年龄阶段黄羽鸡,将其血清作为乙酰胆碱酯酶的酶源,分别对粗酶以及透析后的酶液进行蛋白质含量、酶活力和比活力的测定。实验结果表明,不同发育阶段鸡的鸡血中乙酰胆碱酯酶酶活力是有差异的,5个月大的黄羽鸡的血液中蛋白质含量(纯化后)、乙酰胆碱酯酶酶活力和比活力最高。这也为乙酰胆碱酯酶从低廉易得的鸡血原料中进行提取研究提供了参考。      

漂烫黄秋葵嫩果力学质地变化及评价方法的研究

为探讨漂烫黄秋葵嫩果的力学和色泽质地变化规律以及建立漂烫黄秋葵嫩果力学质地评价方法,用TA-XT2i质地分析仪对漂烫黄秋葵嫩果横切片进行了两种接触方式的硬度测定,并测定了不同漂烫温度、漂烫时间和冷却条件下黄秋葵嫩果的硬度,同时用DC-P3色差仪进行了色泽测定。实验表明,用棱接触压缩实验的压缩功评价漂烫黄秋葵硬度优于棱面接触压缩实验;黄秋葵嫩果经40、60℃漂烫后冷激能更好地保持原来硬度、色泽,且沿长度方向其硬度呈下降趋势;经80、100℃高温漂烫后,黄秋葵嫩果发生软化和褐变;综合力学和色泽质地的分析,黄秋葵嫩果最佳漂烫方法为60℃漂烫30⁶0s后冷激。本研究表明用棱接触压缩实验法评价漂烫黄秋葵力学质地变化是可行的,本实验为漂烫黄秋葵力学和色泽质地变化提供了参考。      

Stochastic linear quadratic optimal control problem with terminal state constraints

This paper addresses the stochastic linear quadratic (LQ) control problem with first- and second-order moment constraints on the terminal state. The problem is a modified version of the optimal covariance control problem, where the terminal state is steered to a given probability distribution. Studying a multiplicative-noise stochastic system rather than an additive-noise system is a salient feature. Unlike the existing ideas in the optimal steering, by using the Lagrange multipliers method and establishing the stochastic maximum principle, our problem is converted into solving forward–backward stochastic difference equations (FBSDEs), which is a special stochastic two-point boundary-value problem (TPBVP). We provide the optimal closed-loop controller and necessary and sufficient solvability conditions by developing a nonhomogeneous relationship between the optimal state and costate in FBSDEs. Finally, numerical examples are given to demonstrate our results.