衰老自由基学说和运动对抗自由基损伤的作用

从自由基的产生、清除以及对机体的损害作用几方面概述了衰老的自由基学说.并说明运动对机体自由基的产生和清除随运动方式、运动强度、运动时间的不同而产生相反的效应,指出长期的有氧运动可以抑制自由基的产生并提高机体的抗氧化能力,对延缓衰老有着不可忽视的作用.     

中国成人教育之“根”：社区成人教育？——与南海先生“社区说”商榷

针对南海先生提出的“中国成人教育之‘根’：社区成人教育”，本文提出质疑。笔者认为原文在概念厘定、宏观把握、未来预测等方面都存在不同程度的遗憾，特与作者商榷，以推动学术进步。     

基于城市竞争力理论的西部体育市场开发研究——以成都、西安、重庆与昆明四城市为例

基于城市竞争力的测评系统分析发现,成都、西安、重庆与昆明市是西部仅有的4个进入全国城市综合竞争力排名前50强的城市。通过对4个城市竞争力模式中12个分支系统的分析,西部体育市场的开发与利用需要进行正确的市场定位,并提出“西部体育城市发展圈”的模式、注重城市竞争力给体育市场开发带来的潜在市场、突出城市文化特色发展点等整体建议,并探讨西部4大城市的具体体育特色市场发展点。     

创新社会及其政策导向

创新不仅是一种"技术-经济"过程,同时也是一种"社会-文化"过程。对知识劳动者或创新创意阶层社会属性的高度关注,是"创新社会论"兴起的一个基本前提。文章分析了"创新社会论"兴起的4个认识基础,总结了全球一些代表性创新中心城市的社会共性特征,提出将人而不是技术置于创新政策制定的中心以及未来政策的导向。     

Centrifugal multiplexing fixed-volume dispenser on a plastic lab-on-a-disk for parallel biochemical single-end-point assays

In this study, a multiple sample dispenser for precisely metered fixed volumes was successfully designed, fabricated, and fully characterized on a plastic centrifugal lab-on-a-disk (LOD) for parallel biochemical single-end-point assays. The dispenser, namely, a centrifugal multiplexing fixed-volume dispenser (C-MUFID) was designed with microfluidic structures based on the theoretical modeling about a centrifugal circumferential filling flow. The designed LODs were fabricated with a polystyrene substrate through micromachining and they were thermally bonded with a flat substrate. Furthermore, six parallel metering and dispensing assays were conducted at the same fixed-volume (1.27 μl) with a relative variation of ±0.02 μl. Moreover, the samples were metered and dispensed at different sub-volumes. To visualize the metering and dispensing performances, the C-MUFID was integrated with a serpentine micromixer during parallel centrifugal mixing tests. Parallel biochemical single-end-point assays were successfully conducted on the developed LOD using a standard serum with albumin, glucose, and total protein reagents. The developed LOD could be widely applied to various biochemical single-end-point assays which require different volume ratios of the sample and reagent by controlling the design of the C-MUFID. The proposed LOD is feasible for point-of-care diagnostics because of its mass-producible structures, reliable metering/dispensing performance, and parallel biochemical single-end-point assays, which can identify numerous biochemical.     

Structural design of a double-layered porous hydrogel for effective mass transport

Mass transport in porous materials is universal in nature, and its worth attracts great attention in many engineering applications. Plant leaves, which work as natural hydraulic pumps for water uptake, have evolved to have the morphological structure for fast water transport to compensate large water loss by leaf transpiration. In this study, we tried to deduce the advantageous structural features of plant leaves for practical applications. Inspired by the tissue organization of the hydraulic pathways in plant leaves, analogous double-layered porous models were fabricated using agarose hydrogel. Solute transport through the hydrogel models with different thickness ratios of the two layers was experimentally observed. In addition, numerical simulation and theoretical analysis were carried out with varying porosity and thickness ratio to investigate the effect of structural factors on mass transport ability. A simple parametric study was also conducted to examine unveiled relations between structural factors. As a result, the porosity and thickness ratio of the two layers are found to govern the mass transport ability in double-layered porous materials. The hydrogel models with widely dispersed pores at a fixed porosity, i.e., close to a homogeneously porous structure, are mostly turned out to exhibit fast mass transport. The present results would provide a new framework for fundamental design of various porous structures for effective mass transport.     

Sensitivity of School-Performance Ratings to Scaling Decisions

Policymakers usually leave decisions about scaling the scores used for accountability to their appointed technical advisory committees and the testing contractors. However, scaling decisions can have an appreciable impact on school ratings. Using middle-school data from New York State, we examined the consistency of school ratings based on two scaling approaches that differed in scaling decisions that are important in high-stakes testing contexts. We found that, depending on subject, grade, and year, a switch in scaling approach led to (1) average absolute shifts in ranks of between 50 and 132 positions (median = 69), which are appreciable shifts for a listing of 1,243 schools; and (2) between 7% and 45% (average = 20%) of schools experiencing shifts in assigned performance bands, depending on the classification scheme. Further, the effect of scaling approach was larger when the raw-score distribution has more severe ceiling effect, and in these cases, it was driven primarily by the difference in the location of the highest obtainable scale score from the two scaling approaches.     

An unexpected particle oscillation for electrophoresis in viscoelastic fluids through a microchannel constriction

Electrophoresis plays an important role in many applications, which, however, has so far been extensively studied in Newtonian fluids only. This work presents the first experimental investigation of particle electrophoresis in viscoelastic polyethylene oxide (PEO) solutions through a microchannel constriction under pure DC electric fields. An oscillatory particle motion is observed in the constriction region, which is distinctly different from the particle behavior in a polymer-free Newtonian fluid. This stream-wise particle oscillation continues until a sufficient number of particles form a chain to pass through the constriction completely. It is speculated that such an unexpected particle oscillating phenomenon is a consequence of the competition between electrokinetic force and viscoelastic force induced in the constriction. The electric field magnitude, particle size, and PEO concentration are all found to positively affect this viscoelasticity-related particle oscillation due to their respective influences on the two forces.     

Study for optical manipulation of a surfactant-covered droplet using lattice Boltzmann method

In this study, we simulated deformation and surfactant distribution on the interface of a surfactant-covered droplet using optical tweezers as an external source. Two optical forces attracted a single droplet from the center to both sides. This resulted in an elliptical shape deformation. The droplet deformation was characterized as the change of the magnitudes of surface tension and optical force. In this process, a non-linear relationship among deformation, surface tension, and optical forces was observed. The change in the local surfactant concentration resulting from the application of optical forces was also analyzed and compared with the concentration of surfactants subjected to an extensional flow. Under the optical force influence, the surfactant molecules were concentrated at the droplet equator, which is totally opposite to the surfactants behavior under extensional flow, where the molecules were concentrated at the poles. Lastly, the quasi-equilibrium surfactant distribution was obtained by combining the effects of the optical forces with the extensional flow. All simulations were executed by the lattice Boltzmann method which is a powerful tool for solving micro-scale problems.