电声子相互作用对半导体超晶格动力学局域化的影响

本文用单带模型分别研究了直流外场和交流外场作用下，电声子相互作用对半导体超晶格的动力学局域化性质的影响。结果表明：电声子相互作用会破坏电子的动力学局域化。对同一声子频率，电声子相互作用的强度越大，电子越快被散射；当声子频率等于直流场的布洛赫频率或交流场频率时，初始局域在某一格点的电子被迅速地散射到其他格点上去，亦即光声子共振场会严重破坏电子的动力学局域化性质。     

Soliton Interactions of the "Good" Boussinesq Equation on a Nonzero Background

In this paper, we obtain the soliton solutions for the "good" Boussinesq equation on a constant background. Based on the asymptotic analysis of the solutions, we find that this equation admits both the elastic and resonant soliton interactions, as well as various partially inelastic interactions comprised of such two fundamental interactions. Via picture drawing, we present some examples of soliton interactions on nonzero backgrounds. Our results enrich the knowledge of soliton interactions in the (1+1)-dimensional integrable equation with a single field.     

A non-singular equation for the three-body scattering problem

This paper derives a non-singular integral equation for the three-body problem. Starting from the three-body equations obtained by Karlsson and Zeiger we introduce a set of algebraic transformations that remove all the Green function pole singularities. For scattering energies on the real axis we find a singularity-free momentum-space integral equation. This equation requires only a finite range of momentum values for its solution. In the case of well-behaved two-body interactions, such as the superposition of Yukawa interactions, we prove that the kernels of this equation have a finite Hilbert-Schmidt norm. This same norm provides a general criteria for establishing when the impulse approximation is accurate.     

Controllable growth of low-dimensional nanostructures on well-defined surfaces

The controllable growth of nanostructures with desired geometric order and well-defined shapes has stimulated great interest due to its applicability in the development of microelectronic devices. Self-assembly is an efficient and versatile way to guide the atoms or molecules into low-dimensional nanostructures as a consequence of balancing complex interplay between adsorbate-adsorbate and adsorbate-substrate interfacial interactions. The tailoring of low-dimensional nanostruc- tures by control of inter-adsorbate and adsorbate-substrate interfacial interactions is reviewed. Such inherent interactions greatly influence not only the size and shape of the growing nanostructures, but also their chemical identity. The degree of interaction between adsorbates can be controlled via preparation procedures, opening up the study of the influence of this phenomenon with respect to reactivity and catalytic behavior. The formation of well-defined molecular layers can be controlled not only by repulsive molecule-molecule interaction but also by symmetry matching or charge transfer be- tween adsorbed molecules and the substrate. It has become obvious that inter-adsorbate and adsorbate-substrate interfacial interactions can be tuned to fabricate diverse surface nanostructures from semiconductor, metallic, and molecular materials.     

Nanoscale Tail Aggregation in Ionic Liquids: Roles of Electrostatic and van der Waals Interactions

Nanoscale spatial heterogeneity in ionic liquids is formed by the aggregation of cationic tail groups. The electrostatic interactions between polar groups and the collective van der Waals interactions between nonpolar tail groups both contribute to the formation of tail domains, but the degrees of their contributions
were unknown. In this work, by applying a strong external electric field to effectively overpower the electrostatic interactions between polar groups, we have determined that the tail aggregation is majorly attributed to the electrostatic interactions and the van der Waals interactions only have minor influence on the spatial heterogeneity phenomenon of ionic liquids.     

Coherent Destruction of Tunneling of Bosons with Effective Three-Body Interactions

The tunneling dynamics of dilute boson gases with three-body interactions in a periodically driven double wells are investigated both theoretically and numerically.In our findings,when the system is with only repulsive twobody interactions or only three-body interactions,the tunneling will be suppressed;while in the case of the coupling between two- and three-body interactions,the tunneling can be either suppressed or enhanced.Particularly,when attractive three-body interactions are twice large as repulsive two-body interactions,CDT occurs at isolated points of driving force,which is similar to the linear case.Considering different interaction,the system can experience different transformation from coherent tunneling to coherent destruction of tunneling(CDT).The quasi-energy of the system as the function of the periodically driving force shows a triangular structure,which provides a deep insight into the tunneling dynamics of the system.     

Vibrational Spectroscopy as a Promising Tool to Study Enzyme-Carrier Interactions: A Review

Abstract

The high selectivity and specificity together with the catalytic activity of enzymes lead them to be a key tool in biotechnology industries. The enzyme immobilization on a carrier material facilitates the reuse of the enzyme and improves its stability. This article is a comprehensive review that reports papers in which different enzymes have been immobilized on distinct carrier materials and enzyme-carrier interactions were evaluated by infrared and/or Raman spectroscopy. Vibrational spectroscopy was used to inspect the spectral bands of different classes of enzymes before and after their immobilization on carriers. In fact, the characteristic spectral bands that prove the interaction enzyme-carrier are related with the amide functional groups of enzymes. In addition, those interactions are characterized by the shift, broadening, or increment on intensity of specific bands in reference to the spectrum of their carrier material. In this review, 20 of these studies used infrared spectroscopy and only three used Raman spectroscopy. The use of both vibrational spectroscopy techniques is increasingly due to their proved capacity to characterize the enzyme-carrier interactions without damaging them.     

Exact and model operators for magnon-phonon interactions in antiferromagnets

A theoretical study is given of magnon-phonon interactions in antiferromagnetic materials. The roles of magnons and phonons as heat carriers and as sources of thermal resistance have been taken into consideration. The exact collision operator which represents the magnon-phonon interactions involved in the transport Boltzmann equations has been replaced by a model operator which possesses the same important properties. The effect of other scattering processes that either phonons or magnons are involved has also been investigated. A new expression for the thermal conductivity has been derived. It includes terms which represent both Normal and Umklapp magnon-phonon processes. The results obtained by using the new expression agree quantitatively with the experimental measurements on Fe Cl₂     

Diffusion of colloidal particles in swimming suspensions

Previously, we have proposed to analyse the hydrodynamic interactions in a suspension of swimmers with respect to an effective hydrodynamic diffusion coefficient, which only considers the fluctuating motion caused by the stirring of the fluid. In this work, we study the diffusion of colloidal particles immersed in a bath of swimmers. To accurately resolve the many-body hydrodynamic interactions responsible for this diffusion, we use a direct numerical simulation scheme based on the smooth profile method. We consider a squirmer model for the self-propelled swimmers, as it accurately reproduces the flow field generated by real microorganisms, such as bacteria or spermatozoa. We show that the diffusion coefficients of the colloids are comparable with the effective diffusion coefficients of the swimmers, provided that the concentration of swimmers is high enough. At low concentrations, the difference in the way colloids and swimmers react to the flow leads to a reduction in the diffusion coefficient of the colloids. This is clearly seen in the appearance of a negative-correlation region for the velocity-correlation function of the colloids, which does not exist for the swimmers.     

Protein recognition using synthetic surface-targeted agents

The design of synthetic agents to disrupt protein-protein interactions has received relatively little attention in recent years. In this review we describe strategies for targeting different types of protein surfaces using mimetics of protein secondary or tertiary structure. In this way strong and selective binding to a protein surface has be achieved and disruption of clinically important protein-protein interactions has been demonstrated in models of human disease.     

Six-body van der Waals interactions

We report on the six-body van der Waals interactions within Rydberg atoms. Specifically, we focus on the octahedron case. The results are compared with previous calculations for two to five bodies' interactions. This research is useful for crystal structure in condensed matter physics, such as p-type doping in Silicon or other types of semiconductors. This research is also useful for studying big molecules in chemistry, chemical engineering, and other fields.     

Chiral plasmonics and enhanced chiral light-matter interactions

Chirality, which describes the broken mirror symmetry in geometric structures, exists macroscopically in our daily life as well as microscopically down to molecular levels. Correspondingly, chiral molecules interact differently with circularly polarized light exhibiting opposite handedness(left-handed and right-handed). However, the interaction between chiral molecules and chiral light is very weak. In contrast, artificial chiral plasmonic structures can generate "super-chiral" plasmonic near-field, leading to enhanced chiral light-matter(or chiroptical) interactions. The "super-chiral" near-field presents different amplitude and phase under opposite handedness incidence, which can be utilized to engineer linear and nonlinear chiroptical interactions. Specifically,in the interaction between quantum emitters and chiral plasmonic structures, the chiral hot spots can favour the emission with a specific handedness. This article reviews the state-of-the-art research on the design, fabrication and chiroptical response of different chiral plasmonic nanostructures or metasurfaces. This review also discusses enhanced chiral light-matter interactions that are essential for applications like chirality sensing, chiral selective light emitting and harvesting. In the final part, the review ends with a perspective on future directions of chiral plasmonics.     

Pairwise entanglement in the Heisenberg XX model with three-site interactions

We investigate the effects of three-site interactions on the pairwise entanglement in a three-qubit Heisenberg XX model. We find the three-site interactions only in favor of the thermal entanglement and benefit the teleportation between the next-to-nearest neighbor qubits. In addition, we also study the stationary entangled state in the model with intrinsic decoherence taken into account. The influence of different types of three-site interactions on the stationary entangled state is then examined.     

Ground States of Lattice Gases with “Almost” Convex Repulsive Interactions

To the best of our knowledge there is only one example of a lattice system with long-range two-body interactions whose ground states have been determined exactly: the one-dimensional lattice gas with purely repulsive and strictly convex interactions. Its ground-state particle configurations do not depend on any other details of the interactions and are known as the generalized Wigner lattices or the most homogeneous particle configurations. The question of the stability of this beautiful and universal result against certain perturbations of the repulsive and convex interactions is interesting in itself. Additional motivations for studying such perturbations come from surface physics (adsorption on crystal surfaces) and theories of correlated fermion systems (recent results on ground-state particle configurations of the one-dimensional spinless Falicov–Kimball model). As a first step, we studied a one-dimensional lattice gas whose two-body interactions are repulsive and strictly convex only from distance 2 on, while its value at distance 1 can be positive or negative, but close to zero. We showed that such a modification makes the ground-state particle configurations sensitive to the tail of the interactions; if the sum of the strengths of the interactions from the distance 3 on is small with respect to the strength of the interaction at distance 2, then particles form two-particle lattice-connected aggregates that are distributed in the most homogeneous way. Consequently, despite breaking of the convexity property, the ground state exhibits the feature known as the complete devil's staircase.     

UV resonance Raman study of cation–π interactions in an indole crown ether

UV resonance Raman (UVRR) spectroscopy is used to probe changes in vibrational structure associated with cation–π interactions for the most prevalent amino acid π–donor, tryptophan. The model compound studied here is a diaza crown ether with two indole substituents. In the presence of sodium or potassium sequestered in the crown ether, or a protonated diaza group on the compound, the indole moieties participate in a cation–π interaction in which the pyrrolo group acts as the primary π‐donor. Systematic shifts in relative intensity in the 760–780 cm⁻¹ region are observed upon formation of this cation–π interaction; we propose that these modifications reflect shifts of the delocalized, ring‐breathing W18 and hydrogen‐out‐of‐plane (HOOP) vibrational modes in this spectral region. The observed changes are attributed to perturbations of the π‐electron density as well as of normal modes that involve large displacement of the hydrogen atom on the C2 position of the pyrrole ring. Modest variations in the UVRR spectra for the three complexes studied here are correlated to differences in cation–π strength. Specifically, the UVRR spectrum of the sodium‐bound complex differs from those of the potassium‐bound or protonated‐diaza complexes, and may reflect the observation that the C2 hydrogen atom in the sodium‐bound complex exhibits the greatest perturbation relative to the other species. Normal modes sensitive to hydrogen‐bonding, such as the tryptophan W10, W9, and W8 modes, also undergo shifts in the presence of the salts. These shifts reflect the strength of interaction of the indole N H group with the iodide or hexafluorophosphate counteranion. The current observation that the W18 and HOOP normal mode regions of the indole crown ether compound are sensitive to cation–pyrrolo π interactions suggests that this region may provide reliable spectroscopic evidence of these important interactions in proteins. Copyright © 2010 John Wiley & Sons, Ltd.     

Phase transitions driven by quasiparticle interactions

After a survey of the solid–liquid transition, driven by phonon–phonon interactions, attention is next focussed on two phase transitions caused by electron–phonon interactions. These are (i) the Barden–Cooper–Schrieffer pure metal superconducting transition and (ii) the original Peierls instability. These have closely similar forms for the respective transition temperatures, both being related to energy gaps. Spin–phonon interactions are then discussed in relation to spin-Peierls materials. Finally, magnon–magnon interactions are treated in the context of the ferromagnetic–paramagnetic transition in the itinerant electron systems Fe, Co and Ni. Heuristic and phenomenological arguments, plus of course experiment, provide the basis for the conclusions drawn here.     

Controlling Soliton Collisions of Condensates by Time-Dependence of Both Interactions and External Potential

Considering time-dependence of both interactions and external potential, we analytically study the collisional behaviors of two bright solitons in Bose-Einstein condensates by using Darboux transformation. It is found that for a closed external potential, the soliton-soliton distance is decreased with nonlinearly increased interactions, while the amplitude of each soliton increases and its width decreases. For linearly increased interactions but nonlinearly decreased external potential, especially, the atom transfer between two solitons is observed, different from previous theory of no atom transfer in solitons collision in a fixed external potential. In addition, it is shown that the collisional type, such as head-on,"chase", or collision period between two solitons, can be controlled by tuning both interactions and external potential. The predicted phenomena can be observed under the condition of the current experiments and open possibilities for future application in atoms transport.     

Violation of the feynman scaling hypothesis and the cosmic-muon charge ratio: a model-dependent analysis

Summary We have attempted here to study the nature of the sea-level cosmicmuon charge ratio at very high energies on the basis of one particular model of multiple production of hadrons in which the violation of the Feynman scaling is one of the very gross features. It is found that extreme emphasis on this feature alone would cause drastic departures from the experimental values of the charge ratio; but when this is combined with some other recently observed and/or proposed characteristics of high-energy interactions the model-based calculations agree quite well up to several TeV energy regime with the data. The model, in the final analysis, supports a very feebly rising nature of the muon charge ratio at ultrahigh energy.