Inertial microfluidics in contraction–expansion microchannels: A review

Inertial microfluidics has brought enormous changes in the conventional cell/particle detection process and now become the main trend of sample pretreatment with outstanding throughput, low cost, and simple control method. However, inertial microfluidics in a straight microchannel is not enough to provide high efficiency and satisfying performance for cell/particle separation. A contraction–expansion microchannel is a widely used and multifunctional channel pattern involving inertial microfluidics, secondary flow, and the vortex in the chamber. The strengthened inertial microfluidics can help us to focus particles with a shorter channel length and less processing time. Both the vortex in the chamber and the secondary flow in the main channel can trap the target particles or separate particles based on their sizes more precisely. The contraction–expansion microchannels are also capable of combining with a curved, spiral, or serpentine channel to further improve the separation performance. Some recent studies have focused on the viscoelastic fluid that utilizes both elastic forces and inertial forces to separate different size particles precisely with a relatively low flow rate for the vulnerable cells. This article comprehensively reviews various contraction–expansion microchannels with Newtonian and viscoelastic fluids for particle focusing, separation, and microfluid mixing and provides particle manipulation performance data analysis for the contraction–expansion microchannel design.     

Preparation and evaluation of microcapsule containing volatile oil of Herba Schizonepetae by emulsion solvent diffusion method

Microcapsules of volatile oil containing Herba Schizonepetae(VOHS) were prepared by emulsion solvent diffusion method to improve the drug loading and reduce the amount of pharmaceutical excipients.Orthogonal assay was applied to optimize the preparation condition of microcapsulation,and the results illustrated that the ratio of ethyl cellulose(EC) to VOHS influenced the property of VOHS microcapsule significantly.GC-MS analysis indicated that some volatile components with low concentration in VOHS were lost after microencapsulation.The microcapsules prepared with optimum condition had good fluidity,and the holes on the surface of the microcapsules contributed to the release of VOHS.The particles of the microcapsule conformed to a normal distribution with the diameter of 45—220 μm.In the simulated intestinal fluid containing 0.2% sodium dodecyl sulfate,pulegone in VOHS microcapsule showed a certain degree of slow release.Compared with β-cyclodextrin method,the microencapsulation used in the present work could reduce the amount of excipients and increase the drug loading.It was beneficial to reduce the dose of Chinese medicines containing volatile oils.     

基于PPP模式的政府在线信息归档模型构建研究

文章对澳、美、英三国的既有政府在线信息归档项目进行分析与借鉴,厘清其归档工作主要存在由记忆机构独自承担和记忆机构与社会组织进行合作共同承担两种模式.通过明确记忆机构与社会组织进行合作(PPP模式)的优点,分析其与我国实际情况的契合度,对政府在线信息归档工作主体、归档范围、归档信息利用等工作基本环节进行分别介绍.构建基于PPP模式的以国家综合档案馆为工作主体中心,以社会组织为合作伙伴,以政府在线平台为工作对象的我国政府在线信息归档模型.     

“月”境品读——刘天华《月夜》与德彪西《月光》音乐美学分析

《月夜》和《月光》的创作分别处在中西音乐变革期,有着丰富的创新精神。两者通过二胡和钢琴两种完全不同的乐器诠释作品,中西"月亮文化"的差异影响了两首乐曲的审美意境和曲式。从音乐美学的角度讲,两者蕴含着不同的音乐文化底蕴,以中西方对月亮不同的诗学追求,表达了不同的"月"境。     

响应面法优化胡麻粕总黄酮提取工艺

通过单因素试验考察了乙醇浓度、液料比、超声温度和超声功率对胡麻粕总黄酮提取量的影响,利用Box-Behnken中心组合试验和响应面法进行优化。结果表明胡麻粕总黄酮的最佳提取工艺为:乙醇浓度58.00%、液料比27.50:1(mL/g)、超声温度57.00℃、超声功率240.00 W。在此条件下,胡麻粕总黄酮提取量实测值为29.02 mg/g,与预测值相符。     

风光互补发电系统最大功率跟踪实现电路的研究

本文介绍了风光互补发电系统的构成,对发电系统最大功率跟踪问题进行了分析,研究了一种双输入DC/DC变换器的实现电路,研究结果表明该电路能很好的应用于风光互补发电系统,具有较高的实用价值。     

数字图书馆信息安全风险评估的方法与模型

对比分析各种类型的风险评估方法,提出数字图书馆信息安全风险评估宜采用定性与定量相结合的半定量分析法。介绍国际标准ISO 27000、中国国家标准GB/T 20984及实际工作中常用的几种不同的评估模型,分析它们的异同与优缺点,讨论它们对数字图书馆信息安全管理的适用性,并通过具体的测评实践及理论分析证明宜采用中国国家标准GB/T 20984中的相乘法作为数字图书馆信息安全风险评估的实践模型。     

Serrated lithium fluoride nanofibers-woven interlayer enables uniform lithium deposition for lithium-metal batteries

The uncontrollable formation of Li dendrites has become the biggest obstacle to the practical application of Li-metal anodes in high-energy rechargeable Li batteries. Herein, a unique LiF interlayer woven by millimeter-level, single-crystal and serrated LiF nanofibers (NFs) was designed to enable dendrite-free and highly efficient Li-metal deposition. This high-conductivity LiF interlayer can increase the Li⁺ transference number and induce the formation of ‘LiF–NFs-rich’ solid–electrolyte interface (SEI). In the ‘LiF–NFs-rich’ SEI, the ultra-long LiF nanofibers provide a continuously interfacial Li⁺ transport path. Moreover, the formed Li–LiF interface between Li-metal and SEI film renders low Li nucleation and high Li⁺ migration energy barriers, leading to uniform Li plating and stripping processes. As a result, steady charge–discharge in a Li//Li symmetrical cell for 1600 h under 4 mAh cm⁻² and 400 stable cycles under a high area capacity of 5.65 mAh cm⁻² in a high-loading Li//rGO–S cell at 17.9 mA cm⁻² could be achieved. The free-standing LiF–NFs interlayer exhibits superior advantages for commercial Li batteries and displays significant potential for expanding the applications in solid Li batteries.     

数字图书馆业务流程研究

以关键词统计的方式并结合前人已有研究成果确定了数字图书馆的功能框架,并以此为基础设计问卷,进行调查、分析、总结,最终得到一套通用的数字图书馆业务流程,可作为数字图书馆信息安全风险管理及其他工作的基础。     

用瞬态法调试放大器的频率特性

本文通过分析放大器瞬态特性和频率特性的关系,提出用瞬态测试法对放大器频率特性进行调试的方法。