We numerically investigate the nonequilibrium behaviors of classic particles with competing interactions confined in a two-dimensional logarithmic trap. We reveal a quench-induced surprising dynamics exhibiting rich dynamic patterns depending upon confinement strength and trap size, which is attributed to the time-dependent competition between interparticle repulsions and attractions under a circular confinement. Moreover, in the collectively diffusive motions of the particles, we find that the emergence of dynamic structure transformation coincides with a diffusive mode transition from superdiffusion to subdiffusion. These findings are likely useful in understanding the pattern selection and evolution in various chemical and biological systems in addition to modulated systems, and add a new route to tailoring the morphology of pattern-forming systems.

We propose a confinement model and study numerically the structural properties of particles with competing interactions in logarithmic traps (i.e., the confinement potential is a logarithmic function). A rich variety of cluster structures are observed as a function of trap steepness, trap size, and particle density. In addition to the consistent results with previous studies for a harmonic confinement, we observe some new stable structures, including a hybrid cluster structure consisting of clumps surrounded by a circular stripe, parallel stripes, or homogeneous voids surrounded by a ringlike arrangement of clumps, and a gear-like cluster with fringed outer rims evenly arranged along the circumference. Our work reveals that such self-organized structures arise due to the radial density reconfiguration in a finite confined system corresponding to the unconstrained systems, which is controlled by the interplay between the long-range repulsions and the attractions to the minimum of the confinement potential. Such results are likely relevant in understanding the structural properties of confined mermaid systems.

Sodium sulfate decahydrate has been microencapsulated within a silica shell through a novel method of reverse micellization and emulsion polymerization. Tetraethoxysilane and 3-aminopropyl-triethoxysilane were used in conjunction as silicon precursors to form the silica shell, which encapsulated sodium sulfate decahydrate as a phase change material for thermal energy storage. The melting and solidifying temperatures of the microcapsules were measured as 33.6 degrees C and 6.0 degrees C, respectively, with associated latent heats of 125.6 kJ/kg and 74.0 kJ/kg. The phase segregation of various hydrate salts was inhibited by the confining effect of the silica mesopores. The size of the microcapsules could be regulated from 500 nm to 28 mu m simply by reducing the amount of surfactant (Triton X-100) deployed as a stabilizer. Confined by SiO2 matrix, heat storage properties of the hydrate salts were greatly improved. Sodium sulfate decahydrate microencapsulated within a silica shell is shown to be suitable for application in thermal energy storage.

在Halbach型永磁体阵列磁场和磁化强度分布研究中,涉及永磁材料内部磁化强度(M)、磁场强度(H)和磁感应强度(B)三者的相互关系函数M(H)、M(B)和B(H).本文介绍了这些函数的典型实验特征,说明为计算获得永磁体阵列磁体内部自洽的磁场和磁化强度矢量分布,必须使用M(B)函数.强场永磁体阵列材料内部的磁场和磁化强度矢量分布无法直接被进行实验测量,不恰当地使用M(H)和B(H)函数易导致不符合实际情况的磁场和磁化强度分布状态预测.

We numerically study the equilibrium vortex structures of type-II/1 superconducting films with a periodic quasi one-dimensional corrugated substrate. We show as a function of substrate period and pinning strength that, the vortex system displays a variety of vortex phases including arrays consisted of vortex clumps with different morphologies, ordered vortex stripes parallel and perpendicular to pinning troughs, and ordered one-dimensional vortex chains. Our simulations are helpful in understanding the structural modulations for extensive systems with both competing interactions and competing periodicities.

The Halbach type hollow spherical permanent magnet arrays (HSPMA) are volume compacted, energy efficient field sources, and capable of producing multi-Tesla field in the cavity of the array, which have attracted intense interests in many practical applications. Here, we present analytical solutions of magnetic induction to the ideal HSPMA in entire space, outside of array, within the cavity of array, and in the interior of the magnet. We obtain solutions using concept of magnetic charge to solve the Poisson's and Laplace's equations for the HSPMA. Using these analytical field expressions inside the material, a scalar demagnetization function is defined to approximately indicate the regions of magnetization reversal, partial demagnetization, and inverse magnetic saturation. The analytical field solution provides deeper insight into the nature of HSPMA and offer guidance in designing optimized one. (C) 2017 Elsevier B.V. All rights reserved.

When a conventional Halbach type Hollow Cylindrical Permanent Magnet Array (HCPMA) is used to generate magnetic induction over the magnitude of coercivity mu H-0(c), some detrimental parasitic magnetic phenomena, such as the demagnetization, magnetization reversal, and vortexes of magnetization, can appear in the interior of the magnets. We present a self-consistent quantitative analysis of the magnetization and magnetic induction distributions inside the magnetic array by considering the anisotropic and nonlinear magnetization functions of the materials consisting of the array. These numeric simulations reveal novel magnetization structures resulted from the self-field of array. We demonstrate that both the field uniformity and magnetic flux in the pole gap can be modulated by partially substituting the magnets of high energy products with the soft irons and the superhard magnets. We also show how the optimized substitution parameters can be obtained for a HCPMA achieving the best field uniformity or the maximum magnetic flux. (C) 2017 Elsevier B.V. All rights reserved.

The Halbach type hollow cylindrical permanent magnet array (HCPMA) is a volume compact and energy conserved field source, which have attracted intense interests in many practical applications. Here, using the complex variable integration method based on the Biot-Savart Law (including current distributions inside the body and on the surfaces of magnet), we derive analytical field solutions to an ideal multipole HCPMA in entire space including the interior of magnet. The analytic field expression inside the array material is used to construct an analytic demagnetization function, with which we can explain the origin of demagnetization phenomena in HCPMA by taking into account an ideal magnetic hysteresis loop with finite coercivity. These analytical field expressions and demagnetization functions provide deeper insight into the nature of such permanent magnet array systems and offer guidance in designing optimized array system.

针对以往铁电制冷方式的不足提出了一种基于热开关的铁电制冷模型的新结构并进行了相关数值计算.此结构中片状铁电材料与片状热开关紧密平行排列,构成模型的基本结构.热开关分‘开’和‘关’两种可控状态,其开状态的热导率远高于关状态的热导率.系统工作时铁电材料片按奇偶位置分别加电场与去电场,每半周期交换.模拟计算涉及铁电材料单元数以及系统不同温跨下的制冷系统性能,模拟计算结果表明,在固定铁电材料单元数或系统温跨时,对于制冷效率以及制冷功率均存在最佳工作点,并且此工作点随系统温跨或铁电材料单元数变化呈规律性变化.

In the recent study given by Insinga et al. [J. Magn. Magn. Mater. 407, 369–376 (2016)], two kind of magnetic hysteresis loops, magnetization versus magnetic field strength (M-H), and magnetic induction versus magnetic field strength (B-H) of the permanent magnetic material with finite coercivity are involved. However, M-H and B-H functions are sensitive to the shape of magnetic element, moreover, M and B are possibly the multivalue functions at H=Hc, perhaps the third kind magnetic hysteresis loop of magnetization versus magnetic induction (M-B) is more appropriate for predicting the phenomena of demagnetization and reversal of original remanence in magnet array.

We have studied Ru-doping effect on the thermopower and electrical transport properties of Ca3Co4O9+δ samples. A thermopower in Ca3Co4−xRuxO9+δ was enhanced by Ru doping. A clear field-induced suppression of thermopower implies a large spin entropy contribution. Magnetic results indicate that the spin entropy enhancement originates from the decrease of Co4+ concentration induced by Ru-doping. The increase of resistivity results from the decreases of carrier concentration and mobility. The electrical transport properties reveal that Ru-doping induces a metal–insulator transition at x≈0.2 and the thermally activated mechanism dominates the transport behavior at low temperature.

Purpose: This study aimed to clarify whether ischemia-induced early growth response 1 (EGR1) influenced the outcomes of experimental stroke by regulating brain-derived neurotrophic factor (BDNF) expression.Methods and results: To mimic ischemia, mice were subjected to middle cerebral artery occlusion, and neurons challenged with oxygen-glucose deprivation. The expression of EGR1 was increased immediately and reached the peak 24 h after reperfusion. To increase and to decrease EGR1 expressions, two types of recombinant lentiviruses were constructed. EGR1 over-expression induced by recombinant lentiviruses expanded infarct volumes and increased the numbers of terminal deoxynucleoitidyl transferase-mediated dUTP nick end labeling (TUNEL) and Fluoro-Jade C-positive cells; while decreased EGR1 expression induced by recombinant lentiviruses diminished infarct volumes and decreased the numbers of TUNEL-and Fluoro-Jade C-positive cells. Both in vitro and in vivo, increasing EGR1 expression with recombinant lentiviruses lead to decreased BDNF expressions; while silencing EGR1 expression with recombinant lentiviruses lead to increased BDNF expressions.Results from electrophoretic mobility shift assay indicated that EGR1 influenced the BDNF expression by binding to its promoter.Conclusion: Ischemia-induced EGR1 expression may exaggerate brain injury by reducing BDNF expression. Inhibiting EGR1 may become a potential treatment for improving outcomes of ischemic stroke. (C) 2015 IBRO. Published by Elsevier Ltd. All rights reserved.

Accumulating evidence suggested that hyperglycemia played a critical role in hippocampus dysfunction in patients with diabetes mellitus. However, the multifactorial pathogenesis of hyperglycemia-induced impairments of hippocampal neurons has not been fully elucidated. Docosahexaenoic acid (DHA) has been shown to enhance learning and memory and affect neural function in various experimental conditions. The present study investigated the effects of DHA on the lipid peroxidation, the level of inflammatory cytokines and neuron apoptosis in the hippocampal neurons in high-glucose condition. High-glucose administration increased the level of tumor necrosis factor α (TNF-α) and IL-6, induced oxidative stress and apoptosis of hippocampal neurons in vitro. DHA treatment reduced oxidative stress and TNF-α expression, protected the hippocampal neurons by increasing AKT phosphorylation and decreasing caspase-3 and caspase-9 expression. These results suggested that high-glucose exposure induced injury of hippocampal neurons in vitro, and the principle mechanisms involved in the neuroprotective effect of DHA were its antioxidant and anti-apoptotic potential. DHA may thus be of use in preventing or treating neuron-degeneration resulting from hyperglycemia.

A simple method of analytical calculation of cooling power for the magnetic refrigerator(MR) was proposed with active magnetic regenerator(AMR),and the cooling power of the AMR was calcuated with an ideal linear temperature field.The cooling power depends on the parameters concerned was revealed.It is found that the refrigerating capacity per cycle is proportional to the square of the adiabatic temperature change induced by magnetocaloric effect(MCE) of magnetic refrigerant,or in other words,proportional to the product of adiabatic temperature change and isothermal entropy change of magnetic refrigerant.In addition,the cooling capacity is also inversely proportional to temperature span of the AMR bed.At last,heat exchange fluid with low specific heat per unit volume is preferred for the AMR.

The effects of Y-doping on spin entropy of Ca3Co4O9+δ have been investigated through measurements of magnetothermopower and magnetic properties. The temperature dependence of thermopower at 4 T is weaker than that at 0 T, showing a clear field-induced suppression of thermopower and a large contribution from spin entropy. The results from magnetic measurements demonstrate that Co4+ concentration decreases with increasing Y-doping level, which gives rise to enhanced spin entropy. A suitable model is adopted to explain commendably the spin entropy enhancement.

An unusual anisotropy of thermopower and magnetothermopower has been observed in the powerful thermoelectric Ca3Co4O9+δ single crystal. The in-plane thermopower is about twice as big as the out-of-plane thermopower. Combining ab initio band structure calculation with semiclassical model analysis, we understand this anisotropy with band structure effects and especially with anisotropic Fermi surface. We find that a strong anisotropy in the topology of Fermi surface leads to the anisotropy of (magneto)thermopower. This study may also shed light on anisotropic properties of other layered cobalt oxides.

[tang, guodong; xu, xiaonong; tang, chipui; qiu, li; lv, liya; wang, zhihe; du, youwei] nanjing univ, dept phys, natl lab solid state microstruct, nanjing 210093, peoples r china. [yang, teng; zhang, zhidong] chinese acad sci, shenyang natl lab mat sci, inst met res, shenyang 110016, peoples r china. [yang, teng; zhang, zhidong] chinese acad sci, int ctr mat phys, shenyang 110016, peoples r china.;tang, gd (reprint author), nanjing univ, dept phys, natl lab solid state microstruct, nanjing 210093, peoples r china;zhwang@nju.edu.cn

The effects of Gd substitution on the thermoelectric (TE) properties of Ca3Co4O9+delta have been systematically investigated from 25 K to 335 K. Partial substitution of Gd in Ca3Co4O9+delta results in an increase of thermopower and resistivity, and a decrease of thermal conductivity. A maximum dimensionless figure of merit (ZT) of 0.028 was achieved at 335 K for Ca2.4Gd0.6Co4O9+delta , which is about one order of magnitude larger than that for Ca3Co4O9+delta . The investigation demonstrates that the TE performance of the Ca3Co4O9+delta system can be improved through Gd doping.

We propose a model to construct the phase diagram for type-II superconductors through molecular-dynamics simulation. In this model, the Abrikosov vortices interact with long-range repulsion and short-range attraction. We are able to obtain the phase diagrams consisting of the vortex lattice, the intermediate-mixed phase (IMP), and the disordered vortex phase in the B-T, B-?, and B-q planes, where B is induction, ? is the Ginzburg-Landau parameter, and q is the relative strength of the attraction to repulsion interactions between vortices. The IMP is in the form of a superlattice of either vortex bubbles or parallel vortex stripes, agreeing excellently with experimental results that have not yet been explained by existing models.