Al-2N高共掺p型ZnO电子结构和红移效应的第一性原理研究

基于密度泛函理论框架下的第一性原理平面波超软赝势方法,对纯的和Al-2N高共掺ZnO超胞的几何结构优化、能带分布、总态密度分布、分波态密度分布、Mulilken电荷分布和吸收光谱的计算。比较计算结果表明,Al-2N高共掺后ZnO电子结构发生了较大的改变,导电类型转化为p型;轨道杂化增强,电荷转移特征明显;间隙宽度减小,吸收光谱发生了红移效应,并且随着Al和N掺杂的相对原子浓度越大红移效应越显著,计算结果和实验的变化趋势相一致。

Ga/N高共掺浓度对ZnO导电性能和红移影响的第一性原理研究

采用密度泛函理论框架下的第一性原理平面波超软赝势方法,建立了未掺杂ZnO单胞和两种不同浓度的Ga/N高共掺ZnO超胞模型,分别进行了几何结构优化、总态密度分布和能带分布的计算.研究表明,ZnO高共掺Ga/N的条件下,Ga/N高共掺浓度越大,导电性能越弱,并且高掺杂后高能区红移效应显著,计算得到的结果与实验结果的变化趋势一致.

In—2N高共掺浓度和择优取向对ZnO最小光学带隙和吸收光谱的影响

目前,虽然In和2N共掺对ZnO最小光学带隙和吸收光谱影响的实验研究均有报道,但是,In和2N共掺在ZnO中均是随机掺杂,没有考虑利用ZnO的单极性结构进行择优取向共掺,第一性原理的出现能够解决该问题.本文采用密度泛函理论框架下的第一性原理平面波超软赝势(GGA+U)方法,计算了纯的ZnO单胞、择优位向高共掺In-2N原子的Zn_(1-x)In_xO_(1-y)N_y(x=0.0625—0.03125,y=0.0625—0.125)八种超胞模型的态密度分布和吸收光谱分布,计算结果表明,在相同掺杂方式、不同浓度共掺In-2N的条件下,掺杂量越增加,掺杂体系体积越增加、能量越增加,稳定性越下降、形成能越增加、掺杂越难、掺杂体系最小光学带隙越变窄、吸收光谱红移越显著.计算结果与实验结果相一致.在不同掺杂方式、相同浓度共掺In—2N的条件下,In—N沿c轴取向成键共掺与垂直于c轴取向成键共掺体系相比较,沿c轴取向成键共掺体系最小光学带隙越变窄、吸收光谱红移越显著.这对设计和制备新型光催化剂功能材料有一定的理论指导作用.

基于文献计量的中外人工智能政策研究现状及启示

[目的/意义]人工智能已成为推动新一轮科技革命和产业变革的重要技术力量,世界各国加紧出台了相关政策。通过对当前研究进行及时梳理,可为今后国内人工智能政策的理论推进及政策出台和完善等提供指导。[方法/过程]以国外SSCI和国内CSSCI期刊数据库收录的395篇研究论文为样本,采用文献计量分析和比较研究法对中外人工智能政策研究的高共被引文献、热点主题及演进趋势等进行深入探索。[结果/结论]与国外相比,国内研究起步较晚但势头迅猛;高共被引文献反映了人工智能领域存在的问题和风险、应用前景、技术革新及对社会的影响;国外研究热点涵盖了知识管理等十二类主题,而国内研究热点则包括国家治理背景下人工智能政策发展路径等三类主题;国外研究的演进特征体现在三个方面,而国内研究则体现在两个方面。最后,从加快形成和构建人工智能政策研究的理论框架体系等三个方面提出对国内研究的启示。

“不同情绪的共情以及不同情境中的共情”专题简介

共情（empathy）是个体理解和分享他人感受并对他人的处境做出适当反应的能力。作为人类情绪活动中的一个特殊方面,其对个体自身行为及社会生活都有重要影响。一方面,高共情个体表现出更好的社会适应性,在人际互动中有更多的亲社会行为,有更少的攻击行为和退缩行为。另一方面,共情损伤会对个体的社会交往产生消极影响。

当前中国消费金融公司的风险特征评估与监管趋势展望

消费金融在提振消费和促进国内大循环方面发挥着积极作用,而居民消费水平的提高和对借贷接受程度的增强亦为消费金融行业蓬勃发展奠定了基础。消费金融行业快速发展、线上渗透率大幅提升,但同时也引发了场景消费违约、高共债风险和不当催收等广受关注的问题。本文梳理了消费金融与传统银行信贷的主要差异,从监管机制建设和监管科技运用角度探究如何进一步规范消费金融公司发展,从而尝试为消费金融未来的监管方向提供思路借鉴。

High temperature oxidation behavior of directionally solidified NiAl-31Cr-2.9Mo-0.1Hf-0.05Ho eutectic alloy

The isothermal oxidation behavior of NiAl-31Cr-2.9Mo-0.1Hf-0.05Ho directional eutectic alloy was investigated with the help of scanning electron microscopy and X-ray diffraction.The results revealed that a continuous Al2O3 scale was formed and owned excellent oxidation resistance in the temperature range of 900-1100°C.When the temperature was up to 1150°C,the continuous Al2O3 oxide film ruptured.Trace rare earth element Ho distributed uniformly in the alloy and relatively high level of Al in Cr（Mo）phase are beneficial to the formation of continuous and compact Al2O3 scale.During the oxidation,a phase transformation fromθ-Al2O3 toα-Al2O3 existed on the surface of oxidation film.It resulted in the abnormal oxidation mass gain happening when the alloy was oxidized at 1000°C or 1050°C.

Low-Microwave Loss Coplanar Waveguides Fabricated on High-Resistivity Silicon Substrate

Three kinds of coplanar waveguides （CPWs） are designed and fabricated on different silicon substrates---common low-resistivity silicon substrate （LRS）, LRS with a 3μm-thick silicon oxide interlayer, and high-resistivity silicon （HRS） substrate. The results show that the microwave loss of a CPW on LRS is too high to be used, but it can be greatly reduced by adding a thick interlayer of silicon oxide between the CPW transmission lines and the LRS.A CPW directly on HRS shows a loss lower than 2dB/cm in the range of 0-26GHz and the process is simple,so HRS is a more suitable CPW substrate.

Dissipative Particle Dynamics Simulation of Microscopic Properties in Diblock Copolymer Films

Mean-square bond length, root-mean-square end-to-end distance and gyration radius in diblock copolymer films have been studied by dissipative particle dynamics simulations. Results show evident linear trends of any property separately with the thickness of film, the interaction between particles of different types, the repulsion between particle and boundary, except for the dependence of the variations of mean-square bond length on the thickness of film, which exhibits as a wave trend. What＇s more, the varying trends of mean-square bond length and root-mean-square end-to-end distance can correspond to each other. The density distribution of either component in diblock copolymer film can be controlled and adjusted effectively through its interaction with boundary.

Microphase Separation of Star-diblock Copolymer Films： a Dissipative Particle Dynamics Simulation

The microphase-separating behaviors of two types of star-diblock copolymers （Ax）4（By）4 and （A^Bg）4 in thin films are studied using the simulation technique of dissipative particle dynamics. A variety of ordered mesostructures have been observed and the simulated phase diagrams show obvious symmetries for the （Ax）4（By）a films and asymmetries for the （AxBy）4 films, besides, it is easier for the （Ax）4（By）4 than for the （A^By）4 to carry out microphase separation under the same conditions, which has been recognized in bulk and can be ascribed to the structural difference between the two types of star copolymers. There are some correspondences between the mesostructures formed in the film and those formed in bulk at the same composition fraction. Decreasing the thickness of film and strengthening the A-B repulsion both help the mesostructures enhance the degree of order. Composition fraction dependences of the mean-square radius of gyration in the two types of star copolymer films are almost contrary, which can be attributed to the differences in their respective structures. These findings can provide a guide to designing novel microstructures involving star-diblock copolymers via geometrical confinement.

Design and Analysis of a Gain-Enhanced,Fully Differential Telescopic Operational Transconductance Amplifier

This paper describes the design and analysis of a fully differential,gain-enhanced CMOS telescopic operational transconductance amplifier （OTA） used in a pipeline analog-to-digital converter （ADC）. Specifications of the OTA are derived from the requirements of ADC. Simulation shows that for a lpF load capacitance, this OTA achieves a high DC gain （approximately 145dB） and a wide unity-gain bandwidth （above 750MHz） at a phase margin 58°. In a configuration where the closed loop-gain is 4,the design spends about 18ns for settling with 0.05% accuracy. Simulations of this design are performed in SMIC CMOS 0.18μm technology.

Pyrolysis of CL20-BTF Co-crystal via ReaxFF-lg Reactive Force Field Molecular Dynamics Simulations

To obtain detailed information on the potential energy, the evolution of species, the initial reaction paths, and thermal decomposition products, we conducted simulations on pyrolysis process of CL20/BTF co-crystal using the ReaxFF/lg reaction force field, with temperature set at 2000 K to 3000 K. With the analysis of evolution curves of potential energy based on exponential function, we obtain the overall characteristic time. Via a description of the total package reaction with classical Arrhenius law, we obtain the activation energy of CL20/BTF co-crystal： Ea=60.8 kcal/mol. Based on the initial path of CL20/BTF co-crystal thermal decomposition we studied, we conclude that N-NO2 bond of CL20 molecules breaks first, working as a dominant role in the initial stage of thermal decomposition under the condition of different temperatures, and that all CL20 molecules completely decompose before BTF molecular regardless of different temperatures. We also find that the main products of CL20/BTF co-crystal are NO2, NO, NO3, HNO, O2, N2, H2O, CO2, N2O, and HONO, etc., on which the temperature forms certain influence.

世界最高夫妻孙明明与徐艳:相互扶持是婚姻的真谛

《吉尼斯世界纪录大全2016》揭晓篮球健将孙明明和手球运动员徐艳,两人身高共达4.26米,超过姚明与叶莉成世界最高夫妻。两人携手所到之处,无不吸引着世人好奇和羡慕的目光。因祸得福,邂逅暖心女孩孙明明1983年出生在黑龙江省巴彦县一个普通农民家庭。小时候个头与同龄人并无太大差别,但当他上小学时,个子却开始蹿了,15岁时竟超过2米。

策略悦读,教研联播——记第三届全国中小学英语阅读教学研讨会

7月15日一18日,来自全国各地中小学及教研单位共计320余名教师和教研员汇聚青岛,参加了全国教育科学"十二五"細撤育部重点课题"阅读策略在提升中小学生英语阅读能力中的价值研究"第三届课题会议暨中小学英语阅读教学研讨会。会议针对课题研究需求和中小学英语阅读教学的问题,共设置了5场专家讲座、3场课题实验区/校经验交流和课题支持相关讲座’及小初高共9堂典型阅读课例点评分析’具有很高的学术含量。

Microstructure and high temperature oxidation resistance of Si-Y co-deposition coatings prepared on TiAl alloy by pack cementation process

In order to improve the high temperature oxidation resistance of TiAl alloy, Y modified silicide coatings were prepared by pack cementation process at 1030, 1080 and 1130 °C, respectively, for 5 h. The microstructures, phase constitutions and oxidation behavior of these coatings were studied. The results show that the coating prepared by co-depositing Si?Y at 1080 °C for 5 h has a multiple layer structure: a superficial zone consisting of Al-rich (Ti,Nb)5Si4 and (Ti,Nb)5Si3, an out layer consisting of (Ti,Nb)Si2, a middle layer consisting of (Ti,Nb)5Si4 and (Ti,Nb)5Si3, and aγ-TiAl inner layer. Co-deposition temperature imposes strong influences on the coating structure. The coating prepared by Si?Y co-depositing at 1080 °C for 5 h shows relatively good oxidation resistance at 1000 °C in air, and the oxidation rate constant of the coating is about two orders of magnitude lower than that of the bare TiAl alloy.

The advertisement call of the giant spiny frog Paa spinosa

We analyzed the advertisement call of Paa spinosa at Yuliang Mountain,Lanxi,Zhejiang Province,in eastern China.Temporal and spectral call parameters were analyzed,along with call intensity.Calls comprised of three to seven notes,the last of which had the longest duration.Three formants(harmonics)were clearly distinguishable from the audio spectrogram.The dominant frequency ranged from 411-1534 Hz,and was either the first or the second formant.The number of notes within a call was positively correlated to air temperature,so that calls contained more notes during the day.Also,the dominant frequency appeared to be lower at the highest temperature.

Effects of La on microstructure and mechanical properties of NbMoTiVSi0.2 refractory high entropy alloys

To study the effects of La on the microstructure and mechanical properties of refractory high entropy alloys,NbMoTiVSi0.2 alloys with different La contents were prepared.Phase constitution,microstructure evolution,compressive properties and related mechanisms were systematically studied.Results show that the alloys with La addition are composed of BCC solid solution,eutectic structure,MSi2 disilicide phase and La-containing precipitates.Eutectic structure and most of La precipitates are formed at the grain boundaries.Disilicide phase is formed in the grains.La can change the grain morphologies from dendritic structure to near-equiaxed structure,and the average grain size decreases from 180 to 20μm with the increase of La content from 0 to 0.5 at.%.Compressive testing shows that the ultimate strength and the yield strength increase with the increase of La content,which is resulted from the grain boundary strengthening.However,they cannot be greatly improved because of the formation of MSi2 disilicide phase with low strength.The ductility decreases with the increase of La content,which is due to the La precipitates and brittle MSi2 disilicide phase.

Miscibility, Crystallization, and Rheological Behavior of Solution Casting Poly（3-hydroxybutyrate）/poly（ethylene succinate） Blends Probed by Differential Scanning Calorimetry, Rheology, and Optical Microscope Techniques

The miscibility and crystallization of solution casting biodegradable poly（3-hydroxybuty- rate）/poly（ethylene succinate） （PHB/PES） blends was investigated by differential scanning calorimetry, rheology, and optical microscopy. The blends showed two glass transition temperatures and a depression of melting temperature of PHB with compositions in phase diagram, which indicated that the blend was partially miscible. The morphology observation supported this result. It was found that the PHB and PES can crystallize simultaneously or upon stepwise depending on the crystallization temperatures and compositions. The spherulite growth rate of PHB increased with increasing of PES content. The influence of compositions on the spherulitic growth rate for the partially miscible polymer blends was discussed.

Inverse Gaussian-beam common-reflection-point-stack imaging in crosswell seismic tomography

To solve problems in small-scale and complex structural traps,the inverse Gaussian-beam stack-imaging method is commonly used to process crosswell seismic wave reflection data.Owing to limited coverage,the imaging quality of conventional ray-based crosswell seismic stack imaging is poor in complex areas;moreover,the imaging range is small and with sever interference because of the arc phenomenon in seismic migration.Thus,we propose the inverse Gaussian-beam stack imaging,in which Gaussian weight functions of rays contributing to the geophones energy are calculated and used to decompose the seismic wavefield.This effectively enlarges the coverage of the reflection points and improves the transverse resolution.Compared with the traditional VSP–CDP stack imaging,the proposed methods extends the imaging range,yields higher horizontal resolution,and is more adaptable to complex geological structures.The method is applied to model a complex structure in the K-area.The results suggest that the wave group of the target layer is clearer,the resolution is higher,and the main frequency of the crosswell seismic section is higher than that in surface seismic exploration The effectiveness and robustness of the method are verified by theoretical model and practical data.

Simulation of Morphologies and Mechanical Properties of A/B Polymer Blend Film

The effects of blend composition and micro-phase structure on the mechanical behavior of A/B polymer blend film are studied by coupling the Monte Carlo(MC) simulation of morphology with the lattice spring model(LSM) of micro mechanics of materials.The MC method with bond length fluctuation and cavity diffusion algorithm on cubic lattice is adopted to simulate the micro-phase structure of A/B polymer blend.The information of morphology and structure is then inputted to the LSM composed of a three-dimensional network of springs to obtain the mechanical properties of polymer blend film.Simulated results show that the mechanical response is mainly affected by the density and the composition of polymer blend film through the morphology transition.When a force is applied on the outer boundary of polymer blend film,the vicinity of the inner cavities experiences higher stresses and strains responsible for the onset of crack propagation and the premature failure of the entire system.