微/纳米流体控制用冰阀器件执行过程的数值模拟

冰阀是一种利用微/纳米流道内流体自身的冻结/融化相变过程来实现关断或开启作用的新型流体元件.由于无运动部件、无泄漏、不会引起流体污染且易于实现电控等优点,该器件在微/纳米流体系统的控制中具有重要的应用前景.针对冰阀的工作原理,基于相应的流体力学及传热学数学模型,从数值计算角度对微流道冰阀器件的执行过程进行了模拟,并开展了相应的参数化研究,在此基础上可对冰阀的工作状态及控制过程更好地加以理解和剖析.

冻结开关控制生物网络液体电路中的信号传输(英文)

通过引入一种新概念型电开关,首次提出研究生物网络液体电路或具有普遍意义的导电性微流体系统中的电学关断问题,通过有选择性地对通路中的水性电溶液实施冻结,则其内在特定方向上传输电流的离子可因溶液冻结后绝缘性的形成而被完全阻断,而一旦复温融化后,则此微流体电路中的电流又恢复其开启状态。为初步证实上述设想,设计了相应的概念性试验,通过检测溶液或生物系统在冻结及加热时的电阻瞬态响应规律,证实了方法的可行性。总结了冻结性电开关在控制导电性液体电路方面的工作性能及其在电泳分析、液相色谱分析以及在控制神经网络中信号传输方面的潜在应用。

冻融型光网络开关

文章提出了一种新概念型的借助于固-液相变对光信号实施调控的冻融型光开关,相比于汽泡光开关,它在提高时间响应特性及降低功耗方面具有优势。本文通过理论分析、热场模拟及原理性实验,对冻融型光开关的可行性进行了论证,结果表明基于该技术有望发展出光通讯领域内具有重要应用价值的器件。

Rotational nanofluids for oxytactic microorganisms with convective boundary conditions using bivariate spectral quasi-linearization method

In this study,we considered the three-dimensional flow of a rotating viscous,incompressible electrically conducting nanofluid with oxytactic microorganisms and an insulated plate floating in the fluid.Three scenarios were considered in this study.The first case is when the fluid drags the plate,the second is when the plate drags the fluid and the third is when the plate floats on the fluid at the same velocity.The denser microorganisms create the bioconvection as they swim to the top following an oxygen gradient within the fluid.The velocity ratio parameter plays a key role in the dynamics for this flow.Varying the parameter below and above a critical value alters the dynamics of the flow.The Hartmann number,buoyancy ratio and radiation parameter have a reverse effect on the secondary velocity for values of the velocity ratio above and below the critical value.The Hall parameter on the other hand has a reverse effect on the primary velocity for values of velocity ratio above and below the critical value.The bioconvection Rayleigh number decreases the primary velocity.The secondary velocity increases with increasing values of the bioconvection Rayleigh number and is positive for velocity ratio values below 0.5.For values of the velocity ratio parameter above 0.5,the secondary velocity is negative for small values of bioconvection Rayleigh number and as the values increase,the flow is reversed and becomes positive.

Recent progress in the application of microfluidic systems and gold nanoparticles in immunoassays

Immunoassays are useful for many bioassays. Many new techniques and materials are introduced into the immunoassay to improve the efficiency. This paper reviews recent progress in the application of microfluidic systems and gold nanoparticles in immunoassay. The micro/nano technologies and materials can offer good sensitivity, fast detection, cost-effectiveness and easy signal readout. In particular, the miniaturization of microfluidics and colorimetric assays based on gold nanoparticles have dramatically improved the efficiency of immunoassays.

Integration of microfluidic injection analysis with carbon nanomaterials/gold nanowire arrays-based biosensors for glucose detection

Carbon nanotubes(CNTs) and reduced graphene oxide(r GO) nanosheets were utilized to construct glucose biosensors in combination with gold nanowire arrays(Au NWAs), and microfluidic injection analysis driven by gravity force was used to investigate the performances of as-prepared glucose biosensors. The results demonstrated glucose biosensors based on carbon nanomaterials/Au NWAs presented excellent performance at low working potential of-0.2 V versus Ag/Ag Cl(3 mol/L KCl), such as high sensitivity, good anti-interference ability and high throughput(45 h^(-1)). The glucose biosensor based on glucose oxidase(GOx)–CNT–Au NWAs showed a wide linear range from 100 to 3,000 lmol/L with a sensitivity of 4.12 l A/cm^2 mmol/L. Furthermore, the linear range and sensitivity of GOx–r GO–Au NWAs-based glucose biosensor were 50–4,000 lmol/L and 8.59 l A/(cm^2 mmol/L), respectively, which were better than those of glucose biosensor based on GOx–CNT–Au NWAs,suggesting r GO nanosheets in combination with Au NWAs being a good platform for the construction of glucose biosensors.

Hypergeometric Series Solution to a Class of Second-Order Boundary Value Problems via Laplace Transform with Applications to Nanofluids

Very recently, it was observed that the temperature of nanofluids is finally governed by second-order ordinary differential equations with variable coefficients of exponential orders. Such coefficients were then transformed to polynomials type by using new independent variables. In this paper, a class of second-order ordinary differential equations with variable coefficients of polynomials type has been solved analytically. The analytical solution is expressed in terms of a hypergeometric function with generalized parameters. Moreover, applications of the present results have been applied on some selected nanofluids problems in the literature. The exact solutions in the literature were derived as special cases of our generalized analytical solution.

BIOCONVECTION IN A NON-DARCY POROUS MEDIUM SATURATED WITH A NANOFLUID AND OXYTACTIC MICRO-ORGANISMS

The aim of this paper is to present a continuum model for bioconvection of oxytactic micro-organisms in a non-Darcy porous medium and to investigate the effects of bio- convection and mixed convection on the steady boundary layer flow past a horizontal plate embedded in a porous medium filled with a water-based nanofluid. The governing partial differential equations for momentum, heat, oxygen and micro-organism conser- vation are reduced to a set of nonlinear ordinary differential equations using similarity transformations that are numerically solved using a built-in MATLAB ODE solver. The effects of the bioconvection parameters on the nanofluid fluid properties, nanoparticle concentration and the density of the micro-organism are analyzed. A comparative anal- ysis of our results with those previously reported in the literature is given. Among the significant findings in this study is that bioconvection parameters highly influence beat, mass and motile micro-organism transfer rates.