Phase transition and quasinormal modes for charged black holes in 4D Einstein-Gauss-Bonnet gravity

In four-dimensional Einstein-Gauss-Bonnet(EGB)gravity,we consider the thermodynamic and phase transitions of(charged)AdS black holes.For the negative GB coefficientα<0.the system allows two physical critical points,corresponding to the reentrant phase transition.when the charge Q>2√-α.For arbitraryα>0,the system always leads to a van der Waals phase transition.We then study the quasinormal modes(QNMs)of massless scalar perturbations to probe the van der Waals-like phase transition between small and large black holes(SBH/LBH)for(charged)AdS black holes.We find that the signature of this SBH/LBH phase transition in the isobaric process can be detected since the slopes of the QNM frequencies change dramatically in small and large black holes near the critical point.The obtained results further support that QNMs can be a dynamic probe of ther-modynamic properties in black holes.     

Analysis of Electromagnetic Information Leakage Based on Cryptographic Integrated Circuits

Cryptographic algorithm is the most commonly used method of information security protection for many devices. The secret key of cryptographic algorithm is usually stored in these devices’ registers. In this paper, we propose an electromagnetic information leakage model to investigate the relationship between the electromagnetic leakage signal and the secret key. The registers are considered as electric dipole models to illustrate the source of the electromagnetic leakage. The equivalent circuit of the magnetic field probe is developed to bridge the output voltage and the electromagnetic leakage signal. Combining them, the electromagnetic information leakage model’s function relationship can be established. Besides, an electromagnetic leakage model based on multiple linear regression is proposed to recover the secret key and the model’s effectiveness is evaluated by guess entropy. Near field tests are conducted in an unshielded ordinary indoor environment to investigate the electromagnetic side-channel information leakage. The experiment result shows the correctness of the proposed electromagnetic leakage model and it can be used to recover the secret key of the cryptographic algorithm.     

黄土高原中部秋季干湿的年际和年代际环流异常特征及与海温的多尺度相关性研究

黄土高原地区作为气候敏感区和生态脆弱区地表干 湿状况的年际和年代际变化特征十分明显. 但以往主要是针对夏季进行分析, 而对黄土高原秋季干湿变化规律及大气环流机理的认识非常有限. 本文基于中国589站最近50 a (1961–2010年)月降水和气温月平均资料、NCEP/NCAR提供的再分析资料以及NOAA提供的海表温度(Sea Surface Temperature, SST) 资料, 运用带通/低通滤波、小波分析、EOF/REOF和回归分析等方法, 在对中国秋季干湿时空演化分类的基础上, 通过研究秋季黄土高原中部干湿演变周期、大气环流特征及与海温的多尺度相关关系, 以揭示影响黄土高原中部秋季干湿变化的物理机理, 并确定影响该区域干湿状况的前兆信号. 小波功率谱分析表明, 黄土高原中部秋季干湿指数存在准4 a和准8 a的周期, 1970–1990年准8 a尺度周期振荡尤为明显. 年际(周期≤ 8 a) 尺度上偏湿年的大气环流特征是, 欧亚大陆中高纬呈“双阻型”, 200 hPa西风急流显著北移, 日本海-鄂霍茨克海受反气旋控制, 其底部的偏东水汽输送带将水汽输入研究区. 年代际(周期 > 8 a)尺度上偏湿年的大气环流特征是, 东亚大陆为一致的低值系统; 200 hPa东亚副热带西风急流减弱北移, 研究区主要水汽来源由经孟加拉湾在中南半岛转向的南风水汽输送及中纬度的西风水汽输送组成. 整个序列上, Nino3区SST指数(Nino3I)超前5个月与秋季干湿指数已呈显著的负相关关系, 而孟加拉湾–中国南海SST指数(BayI)则超前3个月与干湿指数呈现显著的负相关关系. 年际尺度上, 秋季Nino3I, BayI均与秋季干湿指数存在显著相关(准4 a, 4–6 a), 而年代际尺度上, 只有BayI与秋季干湿指数存在显著相关性(准10 a). 黄土高原中部秋季干湿的年际和年代际周期的确定、大气环流异常特征的认识及与海温的多尺度相关关系的建立, 不仅揭示了影响该区域干湿变化的物理机理, 也为干旱气候预测提供了重要的前兆信号. 关键词： 黄土高原中部 干湿特征 海表温度 小波分析     

Electrostatic potential in cylindrical dielectric media using the image charge method

We derive a simple analytical expression for the electric potential produced by a point charge in a cylindrical pore with relative permittivity different from that of the surrounding medium. The interface between the pore and the surrounding media may contain electric charge or be electrically neutral. The expression reduces to the known solutions when the surrounding dielectric medium is identical to the pore or an electric conductor. We discuss the convergence of the series expansion and numerically evaluate the electrostatic potential inside the cylindrical pore. The calculated potential shows the effect of the dielectric permittivity difference of the media. The results demonstrate that the expression can be implemented in a numerical dynamic simulation of charged systems in cylindrical geometry. We also give an expression for the case when the source charge is in the medium outside the cylinder.     

Semipolar (11\bar 2\bar 2) ZnO thin films grown on LaAlO3‐buffered LSAT (112) single crystals by pulsed laser deposition

Semipolar (11\bar 2 \bar 2) ZnO was successfully grown on (112) LaAlO₃/(LaAlO₃)_0.29(Sr₂AlTaO₆)_0.35 substrate by pulsed laser deposition. The epitaxial relationship is [11\bar 23]_{\rm ZnO} // [11\bar 1]_{\rm LAO/LSAT} with the polar axis of [000\bar 1]_{\rm ZnO} pointing to the surface. For ZnO films with thickness of 1.6 μm, the threading dislocation density is ～1 × 10⁹ cm^–2, and the density of basal stacking faults is below 1 × 10⁴ cm^–1. The (11\bar 2 \bar 2) ZnO exhibits strong D⁰X emissions with a FWHM of 9 meV and very few green–yellow emissions in the low‐temperature (10 K) and room‐temperature photoluminescence spectra, respectively.

     

Interaction Between Neuroglobin and Caffeine by Multispectroscopic Methods

The interaction between neuroglobin (Ngb) and caffeine was studied by spectroscopy. UV-Vis spectra revealed that caffeine did not influence the native hexa-coordinated heme structure of neuroglobin. Fluorescence spectra indicated that caffeine could quench the intrinsic fluorescence of neuroglobin through static quenching mechanisms. The calculated thermodynamic parameters showed that the electrostatic force was the main intermolecular force in the reaction. Results also indicated that the microenvironmental changes of tryptophan and tyrosine residues within neuroglobin are inapparent. Furthermore, the circular dichroism (CD) spectra implied that caffeine could induce the formation of α-helix structure of neuroglobin.     

Optimisation of ultrasound assisted extraction of phenolic compounds from Sparganii rhizoma with response surface methodology

The present study reports on the extraction of phenolic compounds from sparganii rhizome. Box–Behnken Design (BBD), a widely used form of response surface methodology (RSM), was used to investigate the effect of process variables on the ultrasound-assisted extraction (UAE). Three independent variables including ethanol concentration (%), extraction time (min) and solvent-to-material ratio (mL/g) were studied. The results showed that the optimal UAE condition was obtained with an ethanol concentration of 75.3%, an extraction time of 40 min and a solvent-to-material ratio of 19.21 mL/g for total phenols, and an ethanol concentration of 80%, an extraction time of 33.54 min and solvent-to-material ratio of 22.72 mL/g for combination of ρ-hydroxybenzaldehyde, ρ-coumaric acid, vanillic acid, ferulic acid, rutin and kaempferol. The experimental values under optimal conditions were in good consistent with the predicted values, which suggested UAE is more efficient process as compared to solvent extraction.     

Why to synthesize vaterite polymorph of calcium carbonate on the cellulose matrix via sonochemistry process?

Vaterite is an important biomedical material due to its features such as high specific surface area, high solubility, high dispersion, and small specific gravity. The purposes of this article were to explore the growth mechanism of vaterite on the cellulose matrix via sonochmistry process. In the work reported herein, the influences of experimental parameters on the polymorph of calcium carbonate were investigated in detail. The calcium carbonate crystals on the cellulose matrix were characterized by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Experimental results revealed that all the reactants, solvent, and synthesis method played an important role in the polymorph of calcium carbonate. The pure phase of vaterite polymorph was obtained using Na₂CO₃ as reactant in ethylene glycol on the cellulose matrix via sonochmistry process. Based on the experimental results, one can conclude that the synthesis of vaterite polymorph is a system process.     

ZnO nanowire array ultraviolet photodetectors with self-powered properties

A ZnO nanowire (NW) array ultraviolet photodetector (PD) with Pt Schottky contacts has been fabricated on a glass substrate. Under UV light illumination, this PD showed a high photo-to-dark current ratio of 892 at 30 V bias. Interestingly, it was also found that this PD had a high sensitivity of 475 without external bias. This phenomenon could be explained by the asymmetric Schottky barrier height (SBH) at the two ends causing different separation efficiency of photogenerated electron–hole pairs, which resulted in the formation of photocurrent. It is anticipated to have potential applications in self-powered UV detection field.     

概率型算子在Lp空间的渐近性质

In 1985, Khan, R. A. established the asymptotic formulas of operators of probabilistic type inL1, space by introducing a newLp-norm. The purpose of this paper is to study the asymptotic rate of these operators, inLp (p>1) spaces. Project supported by the National Natural Science Foundation of China