顶吹搅拌液相流体的水模实验与数值模拟分析

采用水模型和VOF数学模型对浸没式气体顶吹搅拌液相流体分别进行实验与数值模拟,分析在不同喷吹条件下气泡在液相中的形变、运动及液相流体的流场特性。结果表明,随着气流量和喷管浸入液面深度的增加,气-液混合区域分布范围逐渐扩大,液面波动更剧烈;气流量越大、喷管浸入液面越深、液相温度越高,气泡运动对液相流体内部的搅拌作用越强,流体内部扰动越剧烈,液相流场域中的流场速度越大,其中,当气流量为2.0m3/h、喷管浸入液面深度为340mm时,其液相流场速度最大值达到1.18m/s。     

ATP-induced Ca<Superscript>2+</Superscript>-signalling mechanisms in the regulation of mesenchymal stem cell migration

The ability of cells to migrate to the destined tissues or lesions is crucial for physiological processes from tissue morphogenesis, homeostasis and immune responses, and also for stem cell-based regenerative medicines. Cytosolic Ca²⁺ is a primary second messenger in the control and regulation of a wide range of cell functions including cell migration. Extracellular ATP, together with the cognate receptors on the cell surface, ligand-gated ion channel P2X receptors and a subset of G-protein-coupled P2Y receptors, represents common autocrine and/or paracrine Ca²⁺ signalling mechanisms. The P2X receptor ion channels mediate extracellular Ca²⁺ influx, whereas stimulation of the P2Y receptors triggers intracellular Ca²⁺ release from the endoplasmic reticulum (ER), and activation of both type of receptors thus can elevate the cytosolic Ca²⁺ concentration ([Ca²⁺]_c), albeit with different kinetics and capacity. Reduction in the ER Ca²⁺ level following the P2Y receptor activation can further induce store-operated Ca²⁺ entry as a distinct Ca²⁺ influx pathway that contributes in ATP-induced increase in the [Ca²⁺]_c. Mesenchymal stem cells (MSC) are a group of multipotent stem cells that grow from adult tissues and hold promising applications in tissue engineering and cell-based therapies treating a great and diverse number of diseases. There is increasing evidence to show constitutive or evoked ATP release from stem cells themselves or mature cells in the close vicinity. In this review, we discuss the mechanisms for ATP release and clearance, the receptors and ion channels participating in ATP-induced Ca²⁺ signalling and the roles of such signalling mechanisms in mediating ATP-induced regulation of MSC migration.     

基于摄像头的直立行走智能车控制系统设计

针对以往靠中心线提取速度较慢导致车模方向控制不稳,容易跑出赛道等问题,设计以K60微控制器为核心控制单元,利用CMOS摄像头对路径信息进行采集,在提取赛道边界和控制车体方向时创新性的使用了"窗口检测法"和"双比例"PD控制方法。"窗口检测法"能够缩短赛道边界的提取时间,提高搜索效率。双比例PD控制能够对比例参数P进行实时调整,进而更及时、准确地控制车模的运行方向。     

Synthesis of the 3D porous carbon-manganese oxide (3D-C@MnO) nanocomposite and its supercapacitor behavior study

A 3D porous carbon-manganese oxide ([email protected]) nanocomposite is successfully synthesized via a thermal plasma deposition method. The chemical bonds and compositions, phase structures, surface morphologies, etc. of as-obtained [email protected] nanocomposite were characterized by the various equipment, such as X-ray diffractometer, X-ray photoelectron spectroscopy, and electron microscopes. The electrochemical performances of the [email protected] nanocomposite electrode showed a specific capacitance of 780 F g^?1 at a current density of 2 A g^?1 and a capacitance retention rate of 99% after 5000 charge-discharge cycles at a high current density of 10 A g^?1. These excellent capacitive performances may be attributed to the encapsulation of MnO nanoparticles by porous carbon sheets in the [email protected] MnO nanocomposite structure. It is believed that the carbon-encapsulated MnO nanoparticles can be protected from a volume deformation during the charge adsorption/desorption cycle and can be electrically improved by the encapsulated carbon sheets, resulting in better overall capacitive performance. In addition, this study also demonstrates the practical applicability by assembling a supercapacitor using the as-obtained [email protected] nanocomposite to glow a light emitting diode.     

国家电子政务外网入侵防御系统应用实践研究

电子政务外网是网络攻击的一个重点目标,根据国家电子政务外网的安全要求,需增强安全防护.IPS是一种主动响应入侵,并进行安全防护的安全产品,在电子政务行业得到了广泛应用.结合IPS在电子政务外网中的应用案例,阐述了IPS的选择依据、实现目标、保障措施.实践中采用了马尔可夫方法计算动态信息系统威胁发生概率,分析电子政务外网安全风险,为制定安全策略提供依据.     

沈阳市铁西区工人新村三期园区园林景观评价

从工人新村三期园区的园林景观整体入手,分析了硬质景观和软质景观,认为其充分体现了以人为本的设计理念.整体规划布局合理,园路顺畅,设施齐全、功能完备,植被丰富、四季青新,在绿化和美化了园区环境的同时,给人们的日常生活带来了极大的方便,具有明显的生态效益和社会效益,非常适宜市民居住和生活.但是,在水景景观和常绿树种配植方面略显不足,还有改进空间.     

Sonochemical synthesis of nanostructured nickel hydroxide as an electrode material for improved electrochemical energy storage application

A facile and fast approach for the synthesis of a nanostructured nickel hydroxide(Ni(OH)_2) via sonochemical technique is reported in the present study. The X-ray diffraction results confirmed that the synthesized Ni(OH)_2 was oriented in β-phase of hexagonal brucite structure. The nanostructured Ni(OH)_2 electrode exhibited the maximum specific capacitance of 1256 F/g at a current density of 200 mA/g in 1 M KOH_((aq)). Ni(OH)_2 electrodes exhibited the pseudocapacitive behavior due to the presence of redox reaction. It also exhibited long-term cyclic stability of 85% after 2000 cycles, suggesting that the nanostructured Ni(OH)_2 electrode will play a promising role for high performance supercapacitor application.     

Control of DNA integrity in skeletal muscle under physiological and pathological conditions

Skeletal muscle is a highly oxygen-consuming tissue that ensures body support and movement, as well as nutrient and temperature regulation. DNA damage induced by reactive oxygen species is present in muscles and tends to accumulate with age. Here, we present a summary of data obtained on DNA damage and its implication in muscle homeostasis, myogenic differentiation and neuromuscular disorders. Controlled and transient DNA damage appears to be essential for muscular homeostasis and differentiation while uncontrolled and chronic DNA damage negatively affects muscle health.