On-chip collection of particles and cells by AC electroosmotic pumping and dielectrophoresis using asymmetric microelectrodes

The recent development of microfluidic lab on a chip devices requiring sample sizes <100 μL has given rise to the need to concentrate dilute samples and trap analytes, especially for surface-based detection techniques. We demonstrate a particle collection device capable of concentrating micron-sized particles in a predetermined area by combining AC electroosmosis (ACEO) and dielectrophoresis (DEP). The planar asymmetric electrode pattern uses ACEO pumping to induce equal, quadrilateral flow directed towards a stagnant region in the center of the device. A number of system parameters affecting particle collection efficiency were investigated including electrode and gap width, chamber height, applied potential and frequency, and number of repeating electrode pairs and electrode geometry. The robustness of the on-chip collection design was evaluated against varying electrolyte concentrations, particle types, and particle sizes. These devices are amenable to integration with a variety of detection techniques such as optical evanescent waveguide sensing.     

Focusing and trapping of DNA molecules by head-on ac electrokinetic streaming through join asymmetric polarization

In this work, invoking join asymmetric ac polarization using double half-quadrupole electrodes in a symmetric arrangement, we demonstrate a head-on ac electro-osmotic streaming capable of focusing and trapping DNA molecules efficiently. This is manifested by the observation that picomolar DNA molecules can be trapped into a large crosslike spot with at least an order of magnitude concentration enhancement within just half a minute. We identify that the phenomenon is a combined result of the formation of two prefocused DNA jets flowing toward each other, dipole-induced attraction between focused DNA molecules, and dielectrophoretic trap on the spot. With an additional horizontal pumping, we observe that the trap can transform into a peculiar pitchfork streaming capable of continuous collection and long-distance transport of concentrated DNA molecules. We also show that the same electrode design can be used to direct assembly of submicrometer particles. This newly designed microfluidic platform not only has potentials in enhancing detection sensitivity and facilitating functional assembly for on-chip analysis but also provides an added advantage of transporting target molecules in a focused and continuous manner.     

Shape controllable microgel particles prepared by microfluidic combining external ionic crosslinking

Alginate microgels with varied shapes, such as mushroom-like, hemi-spherical, red blood cell-like, and others, were generated by combining microfluidic and external ionic crosslinking methods. This novel method allows a continuous fine tuning of the microgel particles shape by simply varying the gelation conditions, e.g., viscosity of the gelation bath, collecting height, interfacial tension. The release behavior of iopamidol-loaded alginate microgel particles with varied morphologies shows significant differences. Our technique can also be extended to microgels formation from different anionic biopolymers, providing new opportunities to produce microgels with various anisotropic dimensions for the applications in drug delivery, optical devices, and in advanced materials formation.     

Studying emotion induced by music through a crowdsourcing game

One of the major reasons why people find music so enjoyable is its emotional impact. Creating emotion-based playlists is a natural way of organizing music. The usability of online music streaming services could be greatly improved by developing emotion-based access methods, and automatic music emotion recognition (MER) is the most quick and feasible way of achieving it. When resorting to music for emotional regulation purposes, users are interested in the MER method to predict their induced, or felt emotion. The progress of MER in this area is impeded by the absence of publicly accessible ground-truth data on musically induced emotion. Also, there is no consensus on the question which emotional model best fits the demands of the users and can provide an unambiguous linguistic framework to describe musical emotions. In this paper we address these problems by creating a sizeable publicly available dataset of 400 musical excerpts from four genres annotated with induced emotion. We collected the data using an online “game with a purpose” Emotify, which attracted a big and varied sample of participants. We employed a nine item domain-specific emotional model GEMS (Geneva Emotional Music Scale). In this paper we analyze the collected data and report agreement of participants on different categories of GEMS. We also analyze influence of extra-musical factors on induced emotion (gender, mood, music preferences). We suggest that modifications in GEMS model are necessary.     

The control of current across a spark gap by means of an external magnetic field

An experimental study was made of the electrical discharge between parallel plates when the pressure between the plates had been reduced to a value slightly less than the critical pressure—i.e. to the condition when a tube begins to harden. Under these conditions the application of a transverse magnetic field will produce a discharge between the electrodes for potentials less than the normal potential required. It is believed that this is due to the lengthening of the path traversed by the ions in crossing the gap. The results obtained may be harmonized by means of the values found by Carr (Proc. Roy. Soc. 1903) who made a study of Paschen's Law in the region of critical pressure. In general it is found possible, under the conditions studied, to start a discharge and control the value of the current through a circuit of which the gap is a part by means of varying the magnetic field superposed on the gap and without altering either the impressed E.M.F. or the ohmic resistance of the circuit.This control is effected by altering the effective length of the spark gap in the circuit by means of the external magnetic field.     

基于主导设计演进的创新集群效应研究

主导设计的演进,给产业中的企业能带来持续创新机会。企业沿着产业技术轨道创新,企业自己抓住技术轨道,形成产品族创新,从而形成创新集群。一方面因为主导设计要求的技术复杂性及市场需求的复杂性也促进了技术集群的发展,以及环境的不确定性,使得技术创新日益成为一种复杂性活动,单个企业不可能独自完成越来越复杂的创新活动,因而必然寻求技术集成。另一方面,一个成熟的技术创新群总是以突破型技术创新为核心,开辟一个全新的产品设计,围绕这个设计展开的是若干个平台型创新。最后,通过实证来证明理论推演的有效性。     

Double stochastic resonance induced by varying potential-well depth and width

The role of potential-well depth and width on stochastic resonance (SR) driven by colored noise with different noise correlation times is explored and evaluated by deriving the analytic expression of output signal-to-noise ratio (SNR) as a most widely used indicator for quantifying SR phenomenon. Double resonance peaks are observed and shifted between single peak and double peaks when SNR is expressed as the function of varying potential-well depth, varying potential-well width, additive noise intensity, multiplicative noise intensity and the intensity ratio between two noise, respectively. Moreover, the SR behavior induced by varying potential-well depth is different from that induced by varying potential-well width. Even the shapes of SNR curves under different correlation times and coupling strength for potential-well depth are opposite to those for potential-well width and furthermore they are also of dependence on initial conditions. Above clues may be helpful to the precise control of SR by varying potential-well depth and width separately for weak signal enhancement.     

Hyperlipidemia in guinea pigs induced by chronic vitamin C deficiency

Sixteen weeks of chronic vitamin C deficiency, induced in guinea pigs by restricted vitamin C intake, resulted in a marked increase in the serum total LDL- and VLDL- cholesterol, triglycerides and total lipids. HDL-cholesterol decreased resulting in a highly significant increase in LDL/HDL ratio. The results reconfirm that vitamin C deficiency causes changes in blood lipid profile which could promote atherogenesis.     

苁蓉总苷对乙醇诱导小鼠学习记忆再现缺失的影响

目的:观察苁蓉总苷对乙醇所致小鼠学习记忆再现缺失的影响。方法:使用水迷宫法观察小鼠的学习记忆功能。对经过训练优选的小鼠连续灌胃给予苁蓉总苷7天,给药的同时进行训练,给药第6天的成绩作为给乙醇前成绩,第7天进行测试,测试前30分钟灌胃给予乙醇,记录反应时间、错误次数和每组错误只数。结果1)各组动物给予乙醇前水迷宫的反应时间基本一致,各组间没有显著性差异,错误次数及只数均为0。2)给予乙醇后,模型组反应时间明显延长、错误次数及只数明显增加。3)给予乙醇后,苁蓉总苷各剂量组及阳性组反应时间及错误次数和只数均少于模型组,但仅有中剂量组有显著性差异;且中剂量组的作用亦明显优于低剂量组,而阳性组与高剂量组的作用强度相当。结论苁蓉总苷对乙醇诱导的小鼠学习记忆再现缺失有明显的保护作用,并呈现剂量依赖性。     

Treatment of streptozotocin induced diabetes in male rats by immunoisolated transplantation of islet cells

Insulin injection is the main way to combat against insulin-dependent diabetes mellitus effects. Today in some laboratories in the world, the investigators are trying to find some treatments for this disease with insulin-secreting pancreatic islet cells transplantation. Donor tissue in each step of work was prepared from 36 adult male wistar Rats weighted 250–300 grams (75–90 days). Transplantation was done in rats after 2–4 weeks induction of diabetes with 60mg/kg of streptozotocin injection by intravenous method. Encapsulation of pancreatic islet cells allows for transplantation in the absence of immunosuppression. This technique that is called “immunoisolation” is based on the principle that transplanted tissue is protected for the host immune system by an artificial or natural membrane. In this study, the levels of insulin, C-peptide and glucose in diabetic rats have been reached to normal range as compared to un-diabetic rats in 20 days after transplantation of islet cells, so that testis is immunoisolated place for islet cells transplantation. Inside the testis subcutaneously and intrapretoneally implantation of pure islet cells graft, that is a natural immunoisolation method, rapidly and permanently normalized the diabetic state of streptozocin-administered animals.     

Protective effect of ascorbic acid against oxidative damage induced by hydrogen peroxide in cultured human peripheral blood lymphocytes

Hydrogen peroxide is one of the reactive oxygen species for cellular injury. It is overproduced during oxidative stress and is known to damage proteins, nucleic acids and cell membranes. The present study was aimed to study the protective effect of ascorbic acid against the toxic doses of hydrogen peroxide using lipid peroxidation and cytokinesis blocked micronucleus assay. Hydrogen peroxide was studied at 50, 100 and 200μM and was found to increase a dose dependent increase in lipid peroxidation and micronuclei frequency. The treatment of 100 and 200μM of hydrogen peroxide separately along with 20, 40 and 80μM of ascorbic acid showed a dose dependent decrease in the lipid peroxidation and micronuclei frequency. The results suggest a protective effect of ascorbic acid against the hydrogen peroxide induced oxidative damage in cultured human peripheral blood lymphocytes.     

Three-dimensional two-component velocity measurement of the flow field induced by the Vorticella picta microorganism using a confocal microparticle image velocimetry technique

Understanding the biological feeding strategy and characteristics of a microorganism as an actuator requires the detailed and quantitative measurement of flow velocity and flow rate induced by the microorganism. Although some velocimetry methods have been applied to examine the flow, the measured dimensions were limited to at most two-dimensional two-component measurements. Here we have developed a method to measure three-dimensional two-component flow velocity fields generated by the microorganism Vorticella picta using a piezoscanner and a confocal microscope. We obtained the two-component velocities of the flow field in a two-dimensional plane denoted as the XY plane, with an observation area of 455×341 μm² and the resolution of 9.09 μm per each velocity vector by a confocal microparticle image velocimetry technique. The measurement of the flow field at each height took 37.5 ms, and it was repeated in 16 planes with a 2.50 μm separation in the Z direction. We reconstructed the three-dimensional two-component flow velocity field. From the reconstructed data, the flow velocity field [u_(x,y,z),v_(x,y,z)] in an arbitrary plane can be visualized. The flow rates through YZ and ZX planes were also calculated. During feeding, we examined a suction flow to the mouth of the Vorticella picta and measured it to be to 300 pl∕s.     

班氏促卵助孕汤对雷公藤多苷致大鼠卵巢功能低下模型卵巢指数和动情周期的影响

目的:通过动物实验观察广西中医药大学国医大师班秀文经典补肾方剂班氏促卵助孕汤对雷公藤多苷致卵巢功能低下大鼠的干预作用,探讨其治疗卵巢功能低下的机制。方法:选择有正常动情周期的7~8周的育龄期SD大鼠,连续雷公藤多苷片以40mg/kg.d灌胃10周后,应用随机数字法将45只大鼠按随机数字表法随机分为模型对照组、西药对照组、中药高剂量组、中药中剂量组、中药低剂量组5组,加上正常对照组,共6组。中药治疗组分别给予给班氏促卵助孕汤中药原液1.02g/100g.d、0.507g/100g.d、0.254g/100g.d,每次0.5m L/100g,连续2周进行治疗,西药对照组先给予戌酸雌二醇0.028mg/m L浓度,每次以0.5m L/100g灌胃,连续4天,然后给予醋酸甲羟孕酮片0.172mg/m L浓度,每次以0.5m L/100g灌胃,在第4天灌胃一次,停1天后,继续按以上序贯方法用药,连续2周。阴性对照组和模型组造模后按每天0.5m L/100g纯净水灌胃,共2周,观察大鼠一般情况、体重、动情周期、卵巢指数的变化。结果:模型组和正常对照组相比,造模停止后一般情况有所改善,但恢复速度比中药治疗组和西药治疗组慢。模型组的动情周期和卵巢指数均低于正常对照组(P0.01)。给药治疗后,与模型组相比,中药高剂量治疗组和西药组的动情周期恢复至正常水平,卵巢指数提高(P0.05),但中药中剂量组和中药低剂量组在动情周期和卵巢指数上差异不明显(P0.05)。结论:雷公藤多苷可致雌性大鼠卵巢功能低下,表现为动情周期紊乱以及卵巢指数下降,班氏促卵助孕汤用药可恢复卵巢功能低下的动情周期紊乱和卵巢重量。