一株产羧酸酯酶菌的鉴定及酯酶特征的研究

目的:鉴定中国白酒发酵过程中的微生物种类，研究关键酶的特征与作用机制有利于提高白酒的优质品率。方法:本研究用形态学和生理学、16S rRNA、gyr B基因和antiSMASH分析的方法对酒曲中的一株微生物进行了验证；对该菌株的特性进行了研究，采用分子建模的方法获得了羧酸酯酶的3D模型，用分子对接的方法探讨了该菌株的羧酸酯酶的机理。结果:该菌株为产羧酸酯酶的革兰氏阴性菌Pb1（MW580690）；该菌株呈现典型的S型生长曲线，产物曲线为S型，羧酸酯酶活化最优pH范围为5.0~9.0。分子对接结果显示Phe21A为该酶具有催化活性的主要氨基酸，水解三丁酸甘油酯为丁酸和甘油。分子对接结果显示三丁酸甘油酯经过构象变化被转移到催化中心后，进一步被加工；酶的亲水性和疏水性的相互作用表面有利于配体向下转移，进而从疏水性通道释放产物到的酶表面。结论:产羧酸酯酶的菌株为贝莱斯芽胞杆菌，并为羧酸酯酶水解三丁酸甘油酯类物质的底物识别、转移和催化机理提供了新的见解。     

SIL验证与安全仪表系统的优化设计

安全仪表功能(SIF)回路是为了降低特定场景的安全风险而设置的,定级报告中SIF回路的功能描述是工艺设计的完整逻辑要求,包含关键动作及附件动作。安全完整性等级(SIL)验证属于概率学领域研究范畴,影响失效率的因素多且复杂。如果SIL验证无法通过,将造成大量的设计变更,浪费工程投资,影响工期。设计人员应关注SIL定级报告中关键动作的识别、要求平均失效概率以及SIF回路架构的约束。按照文中方法优化测量元件、逻辑控制器、执行元件及辅助元件的设计,可增加通过验证的概率。在没有预验证及安全要求规格书时,可以参考文中典型可通过SIL验证的SIF回路的经验架构进行优化设计,以减少工程变更。     

Multiple clusterings of heterogeneous information networks

Machine Learning - Traditional clustering algorithms focus on a single clustering result; as such, they cannot explore potential diverse patterns of complex real world data. To deal with this...     

An index structure supporting rule activation in pervasive applications

World Wide Web - Rule mechanism has been widely used in many areas, such as databases, artificial intelligent and pervasive computing. In a rule mechanism, rule activation decides which rules are...     

轻量级电驱水下机械臂设计与运动学分析

设计了一款四功能水下机械臂，并对驱动关节进行了模块化设计和密封测试。为了保证水下机械臂的可靠性，在水下机械臂水下测试前，进行了强度校核和模态分析。为了验证水下机械臂的性能，通过 Ｄ- Ｈ法建立了其运动学模型，在此基础上分别进行了正、逆运动学分析。此外还采用蒙特卡洛法，在正运动学分析的基础上研究了工作空间特点。研究结果将为进一步的运动控制提供有益的帮助。     

A mini review on two-dimensional nanomaterial assembly

Two-dimensional (2D) nanomaterials have attracted a great deal of attention since the discovery of graphene in 2004, due to their intriguing physicochemical properties and wide-ranging applications in catalysis, energy-related devices, electronics and optoelectronics. To maximize the potential of 2D nanomaterials for their technological applications, controlled assembly of 2D nanobulding blocks into integrated systems is critically needed. This mini review summarizes the reported strategies of 2D materials-based assembly into integrated functional nanostructures, from in-situ assembly method to post-synthesis assembly. The applications of 2D assembled integrated structures are also covered, especially in the areas of energy, electronics and sensing, and we conclude with discussion on the remaining challenges and potential directions in this emerging field.

     

Influence of Sodium Microalloying on Rolling Contact Endurance and Mechanical Properties of Hot-Deformed Powder Steels

Russian Journal of Non-Ferrous Metals - Rolling bearing rings comprise a large reserve for expanding powder metallurgy production. This reserve is being incompletely implemented. The hot forging of...     

MPE: a mobility pattern embedding model for predicting next locations

World Wide Web - The wide spread use of positioning and photographing devices gives rise to a deluge of traffic trajectory data (e.g., vehicle passage records and taxi trajectory data), with each...