计算机模拟技术在SARS-CoV-2病毒分子机制研究中的应用

由新型冠状病毒（SARS-CoV-2）引发的严重急性呼吸系统综合症到目前为止仍然是影响人类健康的重要问题，病毒突变体的不断出现给药物治疗以及疫苗设计带来了严重的挑战。因此，对于新冠病毒生命周期的分子机制及其突变逃逸机制的研究十分重要。包括分子动力学模拟在内的计算机模拟方法在病毒机制研究方面得到了广泛的应用，故对近年来模拟技术在SARS-CoV-2病毒研究方面的发展状况进行调查，特别探究了分子动力学模拟在刺突蛋白（S蛋白）及其突变体和ACE2以及中和抗体的结合中的应用。     

震荡波杀手接踵而至

5月11日,瑞星公司全球反病毒监测网截获了一个可以干掉“震荡波”的恶性蠕虫病毒,并命名为“震荡波杀手”(worm.cycle.a)病毒。据瑞星透露,“震荡波杀手”还是利用微软的L S A S S漏洞进行传播,该病毒虽然会清除“震荡波”和“冲击波”,但同样会造成网络堵塞和系统异常重启,传播感染速度可能会非常快。病毒跟“震荡波”一样利用微软的LSASS漏洞传播,因此只会影响Windows2000/XP系统。随机生成IP地址,对这些地址的445端口进行扫描,如果成功,则将自己复制过去,试图清除“震荡波”和“冲击波”病毒在系统中的进程。病毒在5月18日,还会对w…     

检测B型葡萄球菌肠毒素的Love波免疫传感器研究

报道了一种可用于检测B型葡萄球菌肠毒素(SEB)的Love模式声表面波压电免疫传感器。传感器本身由压电石英基片、叉指换能器和S iO2声波导层构成。通过APTES和戊二醛层交联蛋白A,实现抗体分子的定向固定,在Love波传感器的表面构建出抗体分子探针的传感界面。建立了基于网络分析仪的传感器测试系统,对抗体分子固定化过程以及10-6g/mL SEB的响应过程进行了实时监测,相位的偏移随时间表现出明显而规律性的改变,与戊二醛共价交联法进行了对比,并用原子力显微镜(AFM)对蛋白A法固定抗体以及捕获了SEB后的表面进行了成像表征。     

信息离散性度量方法在SARS病毒研究中的应用

多序列比较是分子生物学中的一个基本问题，本文利用一种新型信息离散性度量方法——FDOD方法，将其应用于SARS病毒研究中，对SARS病毒与已知的三类冠状病毒的复制酶、M蛋白、N蛋白和S蛋白进行了进化分析，得出的系统发育树与现有的生物分析基本一致。同时进一步显示了FDOD方法的优点，数学基础好，不带有主观因素，能比较客观地度量生物序列间的差异，且计算过程简单快速，是分子进化研究的一种有效工具。     

封杀“中国一号“

“中国一号“计算机病毒是江民病毒快速反应小组捕获的一种新的网络蠕虫病毒,根据病毒体内特有的标记“R.P.China Version1.0“而得名,也称“尼姆达“(Nimda)病毒,是针对微软信件浏览器的弱点和WindowsNT/2000、IIS的漏洞编写出的一种传播性强、破坏力大的病毒.它在Windows9X/ME、WindowsNT、Windows2000等操作系统中传播,感染以nws、eml、doc、exe为扩展名的文件,并加以破坏或替换.清除该病毒的具体方法:……     

封杀"中国一号"

“中国一号“计算机病毒是江民病毒快速反应小组捕获的一种新的网络蠕虫病毒,根据病毒体内特有的标记“R.P.China Version1.0“而得名,也称“尼姆达“(Nimda)病毒,是针对微软信件浏览器的弱点和WindowsNT/2000、IIS的漏洞编写出的一种传播性强、破坏力大的病毒.它在Windows9X/ME、WindowsNT、Windows2000等操作系统中传播,感染以nws、eml、doc、exe为扩展名的文件,并加以破坏或替换.清除该病毒的具体方法:……     

基于FLUENT的新型跨介质航行器气动水动特性研究

针对目前水下航行器和空中航行器难以以单一外形同时满足水空两种航行环境的特点,提出一种通过改变机体外形实现水空介质跨越的新型航行器.应用FLUENT对航行器的气动水动特性进行数值仿真,得到了航行器水中、空中航行的阻力、升力曲线.对结果的分析发现,通过改变外形能够满足航行器水中、空中的航行和机动要求,新型航行器的流体受弹体扰动较大,升阻特性有一定减弱,水空跨介质航行器的外形还有较大的优化空间.     

新型冠状病毒肺炎的深度学习诊断方法综述

新型冠状病毒肺炎的高感染率导致其在全球范围内迅速传播,常用的逆转录-聚合酶反应（RT-PCR）检测方法存在耗时、假阴性率偏高和医学用具不足的缺陷,因此开发高效、准确、低成本的影像检测技术对新型冠状病毒肺炎的诊断和治疗至关重要。随着人工智能在医学领域的成功应用,深度学习技术成为辅助检验和识别新型冠状病毒肺炎的有效方法。对近年来涌现的新型冠状病毒肺炎的深度学习诊断方法进行了研究和总结：介绍了深度学习方法使用的两种新型冠状病毒肺炎数据集;介绍了基于VGGNet、Inception、ResNet、DenseNet、EfficientNet和CapsNet模型的六种深度学习诊断方法;介绍了三种深度学习与其他机器学习方法结合的诊断方法;对基于深度学习的新型冠状病毒肺炎诊断方法的研究趋势进行了展望。     

基于分布式控制系统的空间大型末端执行器抓捕策略

针对空间大型机械臂冈其关节和臂杆柔性带来的抓捕前定位问题,为一种具有柔性捕获接口的新型末端执行器设计了分布式控制系统,并建立了以捕获环收缩速度为主要控制对象的抓捕策略,可实现稳定且高效的抓捕.其中,该控制系统由传感器单元、上层控制单元和3个模块化的底层驱动单元组成.传感器单元和底层驱动单元集成在末端执行器内部,采集系统...     

基于Z曲线的SARS冠状病毒特征的研究

刺突（Spike）蛋白是SARS（Severe Acute Respiratory Syndmme）冠状病毒表面最重要的膜蛋白，它通过与被感染细胞的受体结合来作为感染的媒介。受此启发，该文利用Z曲线方法，对S蛋白及SARS受体序列进行探究，捕捉到一种SARS病毒的可视化特征。大量序列比对的结果证明该特征是SARS病毒所特有的。将这种特征图谱应用到SARS病毒的检测中，可以提供一种非标准的、简单、直观的检验方法，能够诊断一些利用标准方法难以判断的SARS病例。由此可见，Z曲线作为一种基因序列的几何学研究途径是一种有效的研究方法。     

微型四轮移动机器人控制系统的设计

介绍了美国ATMEL公司的高速嵌入式单片机AVR中的AT90S8535的性能特点,设计了以AT90S8535为核心的微型四轮移动机器人的控制系统的软、硬件。最后简要介绍了运用VisualC 6.0开发串行通信的方法。     

基于P2P网络的计算机病毒传播仿真设计

针对病毒文件的传播,充分考虑网络的诸多因素,如：用户到达率、在线（共享）时间、网络节点免疫力等对病毒文件传播的影响,并通过P2P网络仿真工具PeerSim进行分析。     

基于红外传感器的移动微机器人定位研究

综合概率论的思想,采用基于红外传感器的微机器人粒子滤波定位方法在已知环境中实现微机器人的自定位.因微机器人受尺寸效应影响无法安装位置传感器,故采用计步的方法存储机器人的运动信息.观测模型采用适合小尺寸微型机器人的红外测距地图匹配方式.因微机器人的存储能力有限,故采用分块存储地图的方法,便于微机器人快速加载地图而完成地图匹配,从而加速其定位过程.实验验证了微机器人的定位性能.     

1-环丙基-5-取代-7-(4-甲基哌嗪基）-6,8-二氟-1,4-二氢 -4-氧-3-喹啉羧酸的定量构效关系

通过量子化学AM1和Monte Carlo模拟计算,对1-环丙基-5-取代-7-(4-甲基哌嗪基）-6,8-二氟-1,4-二氢-4-氧-3-喹啉羧酸的定量构效关系进行了研究,结果显示5-位取代基的体积V、表面积S、与母核紧连原子的净电荷、指示变量等对抗菌活性有很大影响,回归得到了相关性好的方程：((4)R=0.9,(5)R=0.94),(6)R=0.95)。5-位小的取代基、4-位和5-位形成氢键对抗菌活性有利。计算表明5-为被甲基取代后具有更好的抑制金葡萄菌和绿脓杆菌的抗菌活性。     

Motion control of a magnetically levitated microrobot using magnetic flux measurement

Recent advancements in micro/nano domain technologies have led to a renewed interest in ultra-high resolution magnetic-based actuation mechanisms. This paper deals with the development of a novel research-made magnetic microrobotic station (MMS) with promising potential in biological/biomedical applications. The MMS consists of two separate basic components: a magnetic drive unit and a microrobot. The magnetic drive unit produces and regulates the magnetic field for non-contact propelling of the microrobot in an enclosed environment. Our previous research findings have reported that the MMS should be equipped with high accuracy laser sensors for the position determination of the microrobot in the workspace. However, the laser positioning techniques can be used only in highly transparent environments. This paper seeks to address microrobot position estimation in non-transparent environments. A novel technique based on real-time magnetic flux measurement has been proposed for position estimation of the microrobot in the case of the laser beam blockage. A combination of Hall-effect sensors is employed in the structure of the magnetic drive unit to find the microrobot’s position using the produced magnetic flux. The most effective installation position for the Hall-effect sensors has been determined based on the accuracy sensitivity of experimental measurements. We derived a mathematical function which relates Hall-effect sensors’ voltage output and the position of the microrobot. The motion control capability of the Hall-effect-based positioning method is experimentally verified in the horizontal axis, and it was demonstrated that the microrobot can be operated in most of the workspace range with an accuracy of 0.3?mm as the root-mean-square of the position error.     

Discovering genomic patterns in SARS-CoV-2 variants

SARS-CoV-2 is a novel severe acute respiratory syndrome-like coronavirus (SARS-CoV), which is responsible of the ongoing world pandemic of COVID-19 disease. Although many approaches are being investigated to address this issue, nowaday there are no vaccines available and there is little evidence supporting the efficiency of potential therapeutic agents. Moreover, the high mutation rate of this virus heavily affects the understanding of its evolution and diffusion mechanisms, and, in turn, the development of effective solutions. In this study, two novel algorithms are provided for finding out recurrent patterns of nucleotide subsequences of different SARS-CoV-2 genomes as a unique signature capable of identifying the most peculiar features of the pathogen. In particular, we provide several subsequence patterns related to the Spike glycoprotein, which is believed to be the main target for developing effective drugs and vaccines against the COVID-19 disease because of its role in the entrance of coronaviruses into host cells. The experimental results, obtained by analyzing 5000 genomes of SARS-CoV-2, have shown that the extracted patterns are able to recognize the Spyke protein in the 99.35% of the considered genomes. In addition, such patterns have proven to be highly discriminating with respect to other pathogenic genomes, such as SARS, Middle East respiratory syndrome, Nipah, and the streptococcus bacteria. We hope that the findings presented in this study can help specialists in speeding up the design of more accurate drugs or vaccines against SARS-CoV-2.     

A new type of hybrid fish-like microrobot

In order to develop a new type of fish-like microrobot with swimming, walking, and floating motions, in our past research, we developed a hybrid microrobot actuated by ionic conducting polymer film (ICPF) actuators. But the microrobot had some problems in walking and floating motions. In this paper, we propose a concept of hybrid microrobot (see Fig. 1). The microrobot is actuated by a pair of caudal fins, a base with legs and an array of artificial swim bladders. We have developed a prototype of the base with legs and one artificial swim bladder, respectively, and carried out experiments for evaluating their characteristics. Experimental results show the base with legs can realize walking speed of 6 mm/s and rotating speed of 7.1 degrees/s respectively, and the prototype of the artificial swim bladder has a maximum floatage of 2.6 mN. The experimental results also indicate that the microrobot has some advantages, such as walking motion with 2 degrees of freedom, the walking ability on rough surface (sand paper), the controllable floatage, etc. This kind of fish-like microrobot is expected for industrial and medical applications.     

Enhanced locomotive and drilling microrobot using precessional and gradient magnetic field

We propose a new electromagnetic actuation (EMA) system for an intravascular microrobot with steering, locomotion and drilling functions. The EMA system consists of 3 pairs of Helmholtz coil and 1 pair of Maxwell coil. Generally, Helmholtz coils can align a microrobot in a desired direction by generating a uniform magnetic flux. If the uniform magnetic field generated by Helmholtz coils can be rotated, a microrobot with Helmholtz coils can also be rotated. On the other hand, a Maxwell coil, which generates a constant gradient magnetic flux, can supply the propulsion force for the microrobot. A microrobot actuated by the proposed EMA system has a spiral shaped body containing two magnets with different magnetization directions. With the proposed EMA system, the microrobot can move to the target region and perform drilling there by the precessional magnetic field of the Helmholtz coil pairs. The propulsion force for the microrobot is produced by the gradient magnetic field generated by the Maxwell coil pair. The moving velocity and the drilling performance of the microrobot can be increased by the propulsion force of the Maxwell coil pair. Through various tests, the feasibility and enhancement of the microrobot actuated by the proposed EMA system were verified.     

Novel electromagnetic actuation (EMA) method for 3-dimensional locomotion of intravascular microrobot

A new electromagnetic actuation (EMA) method is proposed for 3-dimensional locomotion of a microrobot. Generally, the EMA system uses Helmholtz coils and Maxwell coils. The Helmholtz coil pair generates a uniform magnetic flux density and the Maxwell coil pair generates a uniform gradient magnetic flux. The microrobot can be aligned to the desired direction by the Helmholtz coils and then, be propelled in the aligned direction by the Maxwell coils. However, many previous EMA systems have been restricted to 2-dimensional planar actuation. The EMA system proposed in this paper consists of a pair of stationary Helmholtz–Maxwell coils and a pair of rotational Helmholtz–Maxwell coils. This new EMA system can manipulate a microrobot in 3-dimensional space. For accurate actuation of a microrobot, the gravitational force, which influences the motion of microrobot, has to be analyzed and compensated. Through various experiments, the performance of the proposed EMA system was evaluated. Finally, a microrobot was test-driven in a blood vessel phantom, and the result of the test drive verified the feasibility of 3-dimensional motion of a microrobot by the new EMA system.     

Design and implementation of LQG\LTR controller for a magnetic telemanipulation system-performance evaluation and energy saving

This paper deals with designing a telemanipulation system (TMS) for microrobotics applications. The TMS uses magnetic levitation technology for the three-dimensional (3-D) manipulation of a microrobot. The TMS is made up of two separate components: a magnetic drive unit and a microrobot. The magnetic drive unit is developed to generate the magnetic field for propelling the microrobot in an enclosed environment. The drive unit consists of electromagnets, a disc pole-piece for connecting the magnetic poles, and a yoke. To handle the 3-D high precision motion control of the microrobot, experimental magnetic field measurements coupled with numerical analysis were done to identify the dynamic model of levitation. This approach leads to the design of a linear quadratic gaussian (LQG) control system, based on the derived state-space model. Based on the PID controller performance, the LQG controller provides considerable improvement in transient response and cross coupling errors. The 3-D motion control capability of the LQG control method is verified experimentally, and it is demonstrated that the microrobot can be operated in the TMS workspace, vertical range of 30?mm and the horizontal range of $32\times 32\,{\text{mm}}^2$ , with RMS error on the order of $10\,\upmu {\text{m}}$ in the vertical and $2.2\,\upmu {\text{m}}$ in the horizontal direction. In the vertical motion, the cross coupling error of the LQG controller is nine times smaller than that of the PID controller. A pre-magnetized pole-piece is proposed to compensate for gravity effect and reduces the system??s energy consumption. This pole-piece provides 66% energy saving for the system??s workspace operations.