基于LabVIEW平台的高准确度光声成像系统设计

利用虚拟仪器开发软件LabVIEW设计了一套高准确度光声成像系统,整个系统在GPIB总线技术基础上,构架了由超声传感器、数字示波器、可调谐激光器、个人计算机等组成的硬件平台,并开发了配套的控制软件和高抗噪音图像重建算法.在活体脑结构成像中,实验鼠的左右脑、小脑、脑横裂和脑主动脉等脑结构成像清晰,大脑皮层的血管分布特征得到了完整的再现,系统成像分辨率可达200 μm.该系统和方法可望发展为一种无损伤的生物组织结构与功能成像.     

In silico identification of potential inhibitors against human 2’-5’- oligoadenylate synthetase (OAS) proteins

As part of the type I IFN signaling, the 2′-5′- oligoadenylate synthetase (OAS) proteins have been involved in the progression of several non-viral diseases. Notably, OAS has been correlated with immune-modulatory functions that promote chronic inflammatory conditions, autoimmune disorders, cancer, and infectious diseases. In spite of this, OAS enzymes have been ignored as drug targets, and to date, there are no reports of compounds that can inhibit their activity. In this study, we have used homology modeling and virtual high-throughput screening to identify potential inhibitors of the human proteins OAS1, OAS2, and OAS3. Altogether, we have found 37 molecules that could exert a competitive inhibition in the ATP binding sites of OAS proteins, independently of the activation state of the enzyme. This latter characteristic, which might be crucial for a versatile inhibitor, was observed in compounds interacting with the residues Asp75, Asp77, Gln229, and Tyr230 in OAS1, and their equivalents in OAS2 and OAS3. Although there was little correlation between specific chemical fragments and their interactions, intermolecular contacts with OAS catalytic triad and other critical amino acids were mainly promoted by heterocycles with π electrons and hydrogen bond acceptors. In conclusion, this study provides a potential set of OAS inhibitors as well as valuable information for their design, development, and optimization.     

Identification of novel nt-MGAM inhibitors for potential treatment of type 2 diabetes: Virtual screening,atom based 3D-QSAR model,docking analysis and ADME study

In this study, a virtual screening procedure was applied to identify new potential nt-MGAM inhibitors as a possible medication for type 2 diabetes. To this aim, a series of salacinol analogues were first investigated by docking analysis for their binding to the X-ray structure of the biological target nt-MGAM. Key interactions for ligand binding into the receptor active site were identified which shared common features to those found for other known inhibitors, which strengthen the results of this study. 3D QSAR model was then built and showed to be statistically significant and with a good predictive power for the training (R² = 0.99, SD = 0.17, F = 555.3 and N = 27) and test set (Q² = 0.81, Pearson(r) = 0.92, RMSE = 0.52, N = 08). The model was then used to virtually screen the ZINC database with the aim of identifying novel chemical scaffolds as potential nt-MGAM inhibitors. Further, in silico predicted ADME properties were investigated for the most promising molecules. The outcome of this investigation sheds light on the molecular characteristics of the binding of salacinol analogues to nt-MGAM enzyme and identifies new possible inhibitors which have the potential to be developed into drugs, thus significantly contributing to the design and optimization of therapeutic strategies against type 2 diabetes.     

原位变温X射线衍射虚拟仿真实验建设与实践

原位变温X射线衍射实验是物理、化学等相关专业综合和创新性实验项目,基于“以虚代实,虚实结合”的思想开发原位变温X射线衍射虚拟仿真实验系统非常必要。本系统完整地模拟了仪器认知、样品测试、数据计算及应用等实验实景,教学中采用线上线下虚实结合的教学方法,培养学生利用大型仪器解决复杂问题的综合能力和高级思维。     

Posting-related attributes driving differential engagement behaviors in online travel communities

Users’ engagement behaviors such as likings, sharing and social interactions in online communities are critically important to the viability and the ultimate success of these communities. However, empirical research investigating which posting-related attributes driving these participation behaviors still lags. The purpose of this study is to understand what and how posting-related attributes drive the engagement behaviors. Using travelogue data from a large traveling knowledge-sharing community, we used econometric models to investigate and compare the antecedents leading to three different kinds of engagement behavior that users exhibit in online communities (i.e., consuming, contributing, and creating). The results reveal that five attributes are associated with these engagement behaviors. These attributes demonstrate the differential effectiveness on the engagement behaviors with different intensities. Our empirical findings provide both theoretical and practical implications for online community operators to build a vibrant and successful online community.     

Identifying conformational changes of the β2 adrenoceptor that enable accurate prediction of ligand/receptor interactions and screening for GPCR modulators

The new β₂ Adrenoceptor (β₂AR) crystal structures provide a high-resolution snapshot of receptor interactions with two particular partial inverse agonists, (−)-carazolol and timolol. However, both experimental and computational studies of GPCR structure are significantly complicated by the existence of multiple conformational states coupled to ligand type and receptor activity. Agonists and antagonists induce or stabilize distinct changes in receptor structure that mediate a range of pharmacological activities. In this work, we (1) established that the existing β₂AR crystallographic conformers can be extended to describe ligand/receptor interactions for additional antagonist types, (2) generated agonist-bound receptor conformations, and (3) validated these models for agonist and antagonist virtual ligand screening (VLS). Using a ligand directed refinement protocol, we derived a single agonist-bound receptor conformation that selectively retrieved a diverse set of full and partial β₂AR agonists in VLS trials. Additionally, the impact of extracellular loop two conformation on VLS was assessed by docking studies with rhodopsin-based β₂AR homology models, and loop-deleted receptor models. A general strategy for constructing and selecting agonist-bound receptor pocket conformations is presented, which may prove broadly useful in creating agonist and antagonist bound models for other GPCRs. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

示波器探头的使用及测量结果的误差分析

示波器探头在电路测试中起着至关重要的作用.探头的使用应不以任何方式影响到信号本身.介绍了示波器探头的定义,并详细论述了实际工作中最常用的无源电压探头的原理、在实际测试中对电路的影响以及使用时的注意事项.对示波器/探头系统的上升时间对测量结果引入的误差进行了分析,并对实际测试中探头的选择给出了很好的建议.只有与示波器和被测电路都匹配良好的探头才能把信号无失真地送入示波器.最大限度满足信号的完整性和测量的精度的要求.     

Identities in the Future Internet of Things

There are two problem areas of the current Internet to be solved in Future Internet scenarios—security and putting the user back in control despite the move to the Internet of things. With this in mind, we address problems associated with the diversifying of the Internet towards an Internet of things, and with increased ways to be reachable, whether the user wants it or not, in the digital world. The paper presents two approaches to cope with the problem: The Identinet and a concept designated by the digital shadow. The paper presents an architecture based on these concepts.     

用PC直接获取数字示波器波形和联机波形参数测量

数字存储示波器,顾名思义除了能实现一般的显示波形功能之外,更重要的是能将屏幕上显示的波形保存下来,以便作再次观察和其它用途,这是数字存储示波器和普通示波器的根本区别。据了解,一般的数字存储示波器用户,都会使用它进行测量和观察波形,对如何存储波形的方法并没有去研究或不太了解。本文提供了利用电脑与安捷伦数字存储示波器实现联机,并利用电脑直接将示波器的波形存储下来,和对存储下来的波形进行参数测量分析等方法,对数字存储示波器用户有一定的参考价值。     

主动网络技术在MPLS-VPN中的应用研究

利用主动网络的可编程性,文中提出一种将主动网络技术运用于MPLS-VPN网络中的方案,通过将网络管理程序动态部署到各主动节点上,实现了网络的智能化、分布式管理。同时,可根据用户的需求,调用主动节点中相关的主动代码,动态配置业务执行环境,满足用户对QoS的要求。