Order parameter description of electrochemical-hydrodynamic interactions in nanochannels

A novel phase-field model is developed for the quantitative modeling of the complex electrochemical-hydrodynamic interactions in narrow fluidic confinements. Through an order parameter variation, this model captures the underlying excluded volume effects, solvation interactions, and preferential polarizabilities in a self-consistent fashion, without resorting to computationally prohibitive molecular dynamics simulations. Agreement with molecular dynamics predictions is found to be quantitative.     

Generalization of interfacial electrohydrodynamics in the presence of hydrophobic interactions in narrow fluidic confinements

We show that the interfacial electromechanics in narrow fluidic confinements exhibits a universal dependence with the intrinsic surface-wettability characteristics, independent of the details of the bulk flow actuating mechanisms. Towards this proposition, we develop a generalized mesoscale model, which is extensively tested for combined electro-osmotic and pressure-driven nanochannel flows. Agreement with the molecular dynamics simulations is found to be quantitative.     

Effect of confinement on the crystallization of a dusty plasma in narrow channels

Three-dimensional quasi-equilibrium configurations of a complex (dusty) plasma in narrow channels are investigated using the molecular dynamics simulations for various confining potentials (confinements). The dynamics of the microparticles is described within the framework of a Langevin thermostat with allowance for the pair interaction between charged particles, which is described by a screened Coulomb potential (Yukawa potential). Two confinements—the parabolic potential and hard elastic wall—are considered. It is shown that the confinement strongly affects the crystallization and the local order of the microparticles in the system under consideration; in particular, the appearance of a new quasicrystalline phase induced by the hard wall confinement is revealed.     

Diquark clustering and the neutron charge radius

We show that a quark-diquark model previously introduced to explainSU(6) violations in quasi-two-body reactions is also able to accomodate a (quantitative) interpretation of the negative charge radius of the neutron, provided one uses appropriate hypotheses for the confinements (c.q. sizes) of the quarks and diquarks involved. They effectively imply the existence of a nucleon core (i.e. a massive two-quark state of substantial spatial clustering) with zero spin and zero isospin.     

NMR studies on simple liquids in confinement

NMR studies on liquids in various types of confinements are reviewed. The discussion includes results for the size, the morphology, and the filling of pores. Moreover, it deals with the phase behaviors, the local structures, and in particular, the local dynamics of confined liquids. Findings for soft and hard confinements of various sizes are considered. The main focus is on the time scales of and the mechanisms for dynamics of simple liquids in simple confinements. From the methodical point of view, the review is restricted to NMR work in homogeneous magnetic fields, i.e, field-gradient approaches are not included.     

Polaronic correction to the first excited electronic energy level in an anisotropic semiconductor quantum dot

Within the framework of second-order Rayleigh-Schrödinger perturbation theory, the polaronic correction to the first excited state energy of an electron in an quantum dot with anisotropic parabolic confinements is presented. Compared with isotropic confinements, anisotropic confinements will make the degeneracy of the excited states to be totally or partly lifted. On the basis of a three-dimensional Fröhlichs Hamiltonian with anisotropic confinements, the first excited state properties in two-dimensional quantum dots as well as quantum wells and wires can also be easily obtained by taking special limits. Calculations show that the first excited polaronic effect can be considerable in small quantum dots.     

Complex dynamics induced by strong confinement – From tracer diffusion in strongly heterogeneous media to glassy relaxation of dense fluids in narrow slits

We provide an overview of recent advances of the complex dynamics of particles in strong confinements. The first paradigm is the Lorentz model where tracers explore a quenched disordered host structure. Such systems naturally occur as limiting cases of binary glass-forming systems if the dynamics of one component is much faster than the other. For a certain critical density of the host structure the tracers undergo a localization transition which constitutes a critical phenomenon. A series of predictions in the vicinity of the transition have been elaborated and tested versus computer simulations. Analytical progress is achieved for small obstacle densities. The second paradigm is a dense strongly interacting liquid confined to a narrow slab. Then the glass transition depends nonmonotonically on the separation of the plates due to an interplay of local packing and layering. Very small slab widths allow to address certain features of the statics and dynamics analytically.     

Perspectives on water science: transport and application of confined water

The confinements of water can be divided into two main categories,namely,the confinements on surface or interface and the confinements in bulk water.By adding ions or applying electric field,the intensity and distribution of the hydrogen bonds can be greatly affected.These are collectively known as confinement on water surface or interface,which has potential applications in life science and industries involving evaporation control.Confined bulk water could be found everywhere in nature,such as in granular and porous materials,macromolecules and gels,etc.The investigation of the physical properties and the transports of the confined bulk water will contribute to understanding certain types of life activities such as the water transport in plant and in new application of extracting the shale oil and water.     

Twisted clad microstructured optical fibers: revisited

The paper discusses confinements corresponding to low-order sustained hybrid modes in twisted clad microstructured optical fiber with twists in the form of conducting sheath helix structure introduced at the core–clad interface and inclined at certain angles. Dispersion relations for such fiber structures are deduced under strict electromagnetic boundary conditions. Varying the angle of pitch (of the introduced conducting sheath helix), investigations in respect of the dependence of power confinements due to the existing low-order hybrid modes have been carried out. The obtained results indicate the usefulness of such microstructured fibers for attenuation or amplification of power in the guide.     

HT－6M托卡马克等离子体电子密度分布研究

根据等离子体电子密度诊断原理，建立了七道远红外ＨＣＮ激光干涉仪。用电子密度分布特征参数研究了ＨＴ－６Ｍ托卡马克上的边界欧姆加热（ＥＯＨ）、抽气限制器（ＰｕｍｐｉｎｇＬｉｍｉｔｅｒ）和离子回旋共振加热（ＩＣＲＨ）实验中的密度分布变化规律和约束特性。对于ＨＴ－６Ｍ托卡马克装置欧姆放电，密度分布特征参数ｕ约为１．１～１．３；约束改善的放电模式，ｕ上升到１．８～２．０，电子密度分布展宽；当密度分布特征多数ｕ≤０．９时，密度分布峰化，这是大破裂的先兆。     

Effect of Confinement Strength on the Conversion Efficiency of Strained Core–Shell Quantum Dot Solar Cell

Optics and Spectroscopy - The conversion efficiency (CE) of core–shell quantum dot (CSQD) solar cell is investigated within weak and strong confinements strength, using detailed balance...     

Speedup of self-propelled helical swimmers in a long cylindrical pipe

Pipe-like confinements are ubiquitously encountered by microswimmers.Here we systematically study the ratio of the speeds of a force-and torque-free microswimmer swimming in the center of a cylindrical pipe to its speed in an unbounded fluid(speed ratio).Inspired by E.coli,the model swimmer consists of a cylindrical head and a double-helical tail connected to the head by a rotating virtual motor.The numerical simulation shows that depending on swimmer geometry,confinements can enhance or hinder the swimming speed,which is verified by Reynolds number matched experiments.We further developed a reduced model.The model shows that the swimmer with a moderately long,slender head and a moderately long tail experiences the greatest speed enhancement,whereas the theoretical speed ratio has no upper limit.The properties of the virtual motor also affect the speed ratio,namely,the constant-frequency motor generates a greater speed ratio compared to the constant-torque motor.     

多组分金属聚合体的光学纳米复合体系(英文)

pacc:7865T Nanocompositethinfilmsformedbynoble metalnanoparticlesembeddedinadielectricma trixshowattractiveopticalpropertiesatthesur faceplasmonresonance(SPR)wavelengthdueto dielectricandquantumconfinementseffects.Whensuchametal-dielectricnanocompositeis …     

The burstein-moss shift in quantum-confined nonparabolic semiconductors

Summary An attempt is made to present a simple theoretical study of the Burstein-Moss shift in quantum wires and dots of nonparabolic semiconductors, takingn-GaAs andn-InSb as examples. It is found that the same shift increases with increasing electron concentration and decreasing film thickness in nonideal steps for both types of quantum confinements for both the materials, respectively.     

用光谱方法研究HL－1装置的不同约束模式

在Ｈ模式和高密度模式（ＨＤＭ）下，用光谱方法研究了ＨＬ－１等离子体的约束状况。实验表明，在这两种模式下粒子约束时间都有明显改善．     

Hyperpolarizability of hydrogen atom under spherically confined Debye plasma

Systematic analysis of the effect of Debye plasma on the hyperpolarizability of spherically confined hydrogen atom has been studied in detail for the first time to understand the behavior of non linear optical properties of atoms under such confinements. Variation perturbation theory is used for such studies. Hyperpolarizability values are enhanced considerably under increased plasma strength while it is found to diminish with decreasing radius of spatial confinement. The present results without plasma screening are in good agreement with existing theoretical data.     

Finite element modal solutions of planar photonic crystal fibers with rectangular air-holes

Modal solutions of planar photonic crystal waveguides with rectangular air-holes are presented by using a rigorous full-vectorial finite element-based approach. The effective indices, mode field profiles, spot-sizes, power confinements, modal hybridness, beat lengths and group velocity dispersions are shown for the fundamental and higher order modes of the quasi-TE and TM polarizations.     

Light propagation and oscillations in two-dimensional graded square photonic lattices

We have studied the optical oscillations and transitions in two-dimensional graded square photonic lattices (GSPL) formed by evanescently coupled optical waveguide arrays with parabolic confinements in all transverse directions. When we retain only the orthogonal couplings, decoupled one-dimensional models can be used to obtain the various normal modes, which correspond to a variety of optical oscillations. Six different combinations of Bloch oscillation (BO), dipole oscillation (DO), and reflections from the boundaries of finite lattice are classified on the phase diagram. If we include the diagonal couplings, transitions among various oscillations are obtained with the Hamiltonian optics approach and confirmed by the field-evolution analysis. We studied in detail a typical example in which a switching occurs from the constituent BO and DO to both DOs in the two orthogonal directions. The method to analyze the complex field evolution in GSPL can be extended to similar systems with different types of lattices and/or confinements.     

Substitutions of vertex configuration of Ammann-Beenker tiling in framework of Ammann lines

The Ammann-Beenker tiling is a typical model for two-dimensional octagonal quasicrystals. The geometric properties of local configurations are the key to understanding its formation mechanism. We study the configuration correlations in the framework of Ammann lines, giving an in-depth inspection of this eightfold symmetric structure. When both the vertex type and the orientation are taken into account, strict confinements of neighboring vertices are found. These correlations reveal the structural properties of the quasilattice and also provide substitution rules of vertex along an Ammann line.