Point‐to‐Plane Nonhomogeneous Electric‐Field‐Induced Simultaneous Formation of Giant Unilamellar Vesicles (GUVs) and Lipid Tubes

It is well‐known that homogeneous electric fields can be used to generate giant unilamellar vesicles (GUVs). Herein we report an interesting phenomenon of formation of GUVs and lipid tubes simultaneously using a nonhomogeneous electric field generated by point‐to‐plane electrodes. The underlying mechanism was analyzed using finite element analysis. The two forces play main roles, that is, the pulling force (F) to drag GUVs into lipid tubes induced by fluid flow, and the critical force (Fc) to prevent GUVs from deforming into lipid tubes induced by electric fields. In the center area underneath the needle electrode, the GUVs were found because F is less than Fc in that region, whereas in the edge area the lipid tubes were obtained because F is larger than Fc. The diffusion coefficient of lipid in the tubes was found to be 4.45 μm² s^?1 using a fluorescence recovery after photobleaching (FRAP) technique. The method demonstrated here is superior to conventional GUV or lipid tube fabrication methods, and has great potential in cell mimic or hollow material fabrication using GUVs and tubes as templates.     

Nonsmooth analysis of vector-valued mappings with contributions to nondifferentiable programming

We define order Lipschitz mappings from a Banach space to an order complete vector lattice and present a nonsmooth analysis for such functions. In particular, we establish properties of a generalized directional derivative and gradient and derive results concerning a calculus of generalized gradients (i.e., calculation of the generalized gradient of f when f = f₁ + f₂, f = f · ₂, etc.). We show the relevance of the above analysis to nondifferentiaile programming by deriving optimality conditions for problems of the form min f(x) subject to x [euro] S. For S arbitrary we state the results in terms of cones of displacement of the feasible region at the optimal point; when S ={x ? A|g(x) ? B}, we obtain Kuhn-Tucker type results.     

Solid structures in a highly agitated bed of granular materials

A series of experiments are described in which bubbles and solid structures are produced in a highly agitated bed of vertically shaken granular materials. To identify the physical mechanisms behind bubbling, three-dimensional simulations of the aforementioned systems are performed on a graphics processing unit (GPU). The gas dynamics above and within shaken granular materials is solved using large-eddy simulations (LES) while the dynamics of grains is described through molecular dynamics. Here, the interaction between the grain surfaces is modeled using the generalized form of contact theory developed by Hertz. In addition, the coefficient of kinetic friction is assumed to depend on the relative velocity of slipping. The results show both a qualitative and a quantitative agreement between simulations and experiments. They imply that the instantaneous formation and failure of granular aggregates could play an important role in the nucleation, growth, departure and collapse of bubbles in shaken granular materials. This promising effort in GPU computing may position the GPU as a compelling future alternative to traditional simulation techniques.     

Effect of Temperature on Henry's Constant in Simple Mixtures

Abstract

The molecular theory of dense fluids is progressing rapidly and its extension to mixtures is well underway. The purpose of this note is to call attention to a possibly serious difficulty in comparing experimental Henry's constants with those calculated from theory. The difficulty arises because whereas theorists choose temperature and density as independent variables, experimental equilibrium measurements on mixtures are often made along the saturation line where (at fixed composition) temperature and density are not both independent variables. Unless Henry's constants are defined with care, the effect of temperature on Henry's constants calculated from molecular theory may be qualitatively different from that observed.     

Simulation of viscoelastic fluids in a 2D abrupt contraction by spectral element method

This study presents the vortex structure and numerical instability increase occurring when the level of elasticity is enhanced in inertial flows in planar contraction configuration for finitely extensible nonlinear elastic model by Peterlin (FENE‐P) fluid 1 . The re‐entrant corner effect on corner vortices is also considered. The calculations are performed using extended matrix logarithm formulation described in a previous paper: A. Jafari et al. A new extended matrix logarithm formulation for the simulation of viscoelastic fluids by spectral elements. Computer & Fluids 2010; 39 (9):1425–1438. In that reference, the proposed algorithm has been tested for simple geometry such as Poiseuille flow. In this study, we are interested in the capability of this algorithm for more complex geometry. This formulation helps to reach higher values of the Weissenberg number when compared with the classical one. Copyright © 2015 John Wiley & Sons, Ltd.     

Mechanics of stretchable electronics on balloon catheter under extreme deformation

Stretchable electronics has been applied to balloon catheters for high-efficacy ablation, with tactile sensing integrated on the surface, to establish full and conformal contact with the endocardial surface for elimination of the heart sink caused by blood flow around their surfaces. The balloon of the catheter folds into uniform ‘clover’ patterns driven by the pressure mismatch inside (∼vacuum) and outside of the balloon (pressure ∼1 atm). The balloon catheter, on which microelectrodes and interconnects are printed, undergoes extreme mechanical deformation during its inflation and deflation. An analytic solution is obtained for balloon catheter inflation and deflation, which gives analytically the distribution of curvatures and the maximum strain in the microelectrodes and interconnects. The analytic solution is validated by the finite element analysis. It also accounts for the effect of inflated radius, and is very useful to the optimal design of balloon catheter.     

Position calculation of the frequency band gap in the finite photonic crystal with multiple alternations using boundary element method

In this paper, the wave transmission from finite photonic crystals with multiple alternations is investigated using boundary element method (BEM). Since that, in these structures the alternation is not in all directions of space; the investigations of the frequency band gap with desired accuracy are not practical by analytical methods. Also, the frequency dispersion of dielectric rods is an effective parameter in photonic crystals, which this effect in our calculations has been considered. Due to the high capabilities of the BEM, the transmitted wave spectrum in the photonic crystal is calculated by changing the geometrical and optical parameters of the photonic crystal and applying more alternation in its structure and the position and width of the frequency band gap is investigated. Then, it is assumed that the photonic crystal with an arbitrary angle is rotated around the axis which is perpendicular on the crystal cross section and then, it is irradiated with a plan wave. The band gap of the photonic crystals with the desired structure, desired rotation angle and multiple alternations have been solved. Very low information volume, high speed and accuracy during the calculation and useable for any desired structures are the characteristics of this method.     

Revealing sol-gel type main effects by exploring a molecular cluster behavior in model in-plane amphiphilic aggregations

In-plane (bio)matter aggregations of amphiphilic nature are modeled extensively by Monte Carlo simulation in their natural entropic contexts. The modeling starts by designing the aggregations at a molecular level, pointing to its well-known configuration vs conformation character. Then, the conformational behavior is distributed over the aggregations obtained, with the aim of revealing their main sol-gel type (viscoelastic) effects. The passage between the resulting sol and gel phases is not controlled by a scan in the temperature domain, on the contrary, the control parameter is selected to be the hydrophobic-interaction strength while the temperature remains unchanged. The distribution of ordered fringed micelles, and the overall crystalline inclusions of the gel phase, suggested a first-order phase change, reasonably conceivable in terms of Avrami-Kolmogorov formalism for such hydrophobic-force driven and percolation-in-nature systems. A phase transition diagram has been presented as a novel proposition to discern between sol vs gel phases. As specific results, also of high experimental value, a damped-oscillating cluster-involving effect on the resulting hydrophobic-polar matrices has been detected and analysed. Other additional intermolecular-sharing entropy-influenced effects on clustering, as seen in terms of chain-to-chain connectivities, have been addressed as being of sufficient relevance to the gelation mechanism described. The microcrystalline inclusions downgrade to some extent the overall picture of entropy-affected gelation, being all together suitable for experimental check-out.     

火焰原子吸收光谱法测定赣南脐橙中6种微量元素含量

将赣南脐橙经硝酸和高氯酸消化后，在样品中加入氯化镧作为释放剂以消除共存离子的干扰，采用火焰原子吸收光谱法测定了Ca、Mn、Zn、Fe、Cu和Pb元素的含量。结果表明，标准加入法的回收率为．96．58％～104．31％，10次平行测定结果的相对标准偏差RSD均小于2％。该法灵敏度高、操作简便快速，结果准确，重现性好。可见赣南脐橙中各元素含量差异显著，其中ca的含量比较丰富，Mn、Fe和zn的含量中等，含有人体必需的微量元素，而对身体有害的元素如P11含量却相当低，这说明赣南脐橙具有一定的药用和经济价值，为进一步探讨赣南脐橙开发利用提供实际依据。