InSb(111)表面硫处理的研究

本文用俄歇电子能谱、X射线光电子能谱和紫外光电子能谱对用硫化铵溶液处理的InSb表面进行研究。结果表明,硫处理以后在样品表面生成。一层厚度约8?的硫化物钝化层,它对防止表面的氧化和碳沾污有明显的钝化作用。钝化层中,破原子既与锑原子成键,引起Sb3d芯能级发生1.9eV的化学位移;又与铟原子成键,引起In4d芯能级发生0.6—0.7eV的化学位移。350℃的真空退火使锑的硫化物发生分解。500℃退火没能使铟的硫化物完全分解,仍有一部分硫原子以铟的硫化物形式留在样品表面。 关键词：     

一个多项式时间可解的自由作业排序问题

一个多项式时间可解的自由作业排序问题俞国胜（上海大学理学院数学系，上海２０１８００）１引言和记号自由作业（ｏＰｅｒｌｓｈｏＰ）排序问题是：有ｎ个工件Ｊ一《ＪＩ，人，··，人｝和。台机器Ｍ一｛ＭＩ，ＭＺ，…；Ｍｔｎ｝，每个工件Ｊｊ需要在机器Ｍｉ上加工，...     

边界元法在地基强夯加固中的应用

本文借助Cruse和Rizzo所获得的经过拉氏变换后的弹性体运体微分方程的基本解,用加权余量法导出弹性振动问题的边界积分方程,并将其应用于边界元解强夯问题.土的弹模在逐次夯击下随着地基性质的改善逐渐变大;而每次夯击,加荷与卸荷模量也是不同的,因之得到土的残余变形.实质上,这是非线性的弹性分析. 文中最后还推导出水下强夯时夯锤在水中的下落速度与落距的关系,为水下强夯提供了理论依据.     

科学出版社物理类新书推荐

密度起伏、结构缺陷等空间不均匀性能导致介质中光的弹性散射.弹性散射也会发生在非线性晶体中,它会作为信号光参与光参量过程,并且在相位匹配的条件下有效地转换成新的频率,强度也获得增强.最近我们在χ(2)非线性光子晶体中发现的锥形二次谐波就与这一过程有关.实验采用的是一块“晶格参数”约为 9μm的六角极化的χ(2)钽酸锂光子晶体,当基波光沿着六角结构的对称方向传播时,出射的锥形二次谐波投影在接收屏上呈现出轴对称或者镜像对称两种衍射光环.随着基波频率的变化,环的半径和颜色会发生相应的改变.封面图展示了样品的显微结构和不同颜…     

高性能硅基负极聚合物粘结剂的研究进展

硅（Si）由于其具有超高理论比容量而成为最有前途的下一代锂离子电池的负极材料。但是,锂离子的嵌入和脱出会造成硅体积的巨大变化,进而导致Si的粉化,致使电极容量产生不可逆的衰减,严重限制了硅基材料的广泛应用。然而过去的大量报道表明,聚合物粘结剂可以有效克服由于硅微粒的体积膨胀而产生的“孤岛效应”,保持电极在充放电过程的完整性,进而提高电极的电化学性能。对聚合物粘结剂按结构分类,可以将其大致分为4类,即线型、支化型、交联网络型及共轭型。不同分子结构的粘结剂用作硅基负极粘结剂时,电极表现出不同的电化学性能。特别是设计出具有多种分子结构的聚合物粘结剂,极大地促进了硅基负极的实际应用。通过对比具有不同分子结构的聚合物粘结剂用于硅基负极取得的效果,可以清晰地得到最有效的分子结构,对未来硅基负极聚合物粘结剂的开发提供思路。最后,本文提出了下一代聚合物粘结剂的设计方向,以促进其向可大规模应用和工业化生产的方向发展。     

结合n模式表示势的含时密度矩阵重正化群求解激发态非辐射衰减速率：理论形式和在薁分子中的应用

本文提出一种来计算多原子分子包含Franck-Condon区势能面非谐效应的无辐射衰减速率的方法. 这种方法结合了n模式表示法,通过构造第一性势能面和近乎精确的含时密度矩阵重正化群法(TD-DMRG),来模拟量子动力学过程. 另外,在TD-DMRG 的框架下,进一步发展了计算末态分辨的速率常数的算法,它对于分析每个振动模式对于跃迁过程的贡献十分有用. 本文采用这种方法研究了考虑基态势能面非谐性后的薁分子的内转换过程. 结果表明,即使对这个半刚性的分子,模式内的非谐性也能够显著的提高内转换速率;在考虑双模式的耦合之后,速率会进一步增加. 其原因是由于C-H振动的黄昆因子接近于0,其在简谐势能面上无法对内转换做出贡献,而非谐性打开了C-H振动接受电子能量的能力.     

The modulation of brain functional connectivity with manual acupuncture in healthy subjects:An electroencephalograph case study

Manual acupuncture is widely used for pain relief and stress control.Previous studies on acupuncture have shown its modulatory effects on the functional connectivity associated with one or a few preselected brain regions.To investigate how manual acupuncture modulates the organization of functional networks at a whole-brain level,we acupuncture at ST36 of a right leg to obtain electroencephalograph(EEG) signals.By coherence estimation,we determine the synchronizations between all pairwise combinations of EEG channels in three acupuncture states.The resulting synchronization matrices are converted into functional networks by applying a threshold,and the clustering coefficients and path lengths are computed as a function of threshold.The results show that acupuncture can increase functional connections and synchronizations between different brain areas.For a wide range of thresholds,the clustering coefficient during acupuncture and postacupuncture period is higher than that during the pre-acupuncture control period,whereas the characteristic path length is shorter.We provide further support for the presence of "small-world" network characteristics in functional networks by using acupuncture.These preliminary results highlight the beneficial modulations of functional connectivity by manual acupuncture,which could contribute to the understanding of the effects of acupuncture on the entire brain,as well as the neurophysiological mechanisms underlying acupuncture.Moreover,the proposed method may be a useful approach to the further investigation of the complexity of patterns of interrelations between EEG channels.     

High-performance 4H-SiC junction barrier Schottky diodes with double resistive termination extensions

4H-SiC junction barrier Schottky (JBS) diodes with a high-temperature annealed resistive termination extension (HARTE) are designed, fabricated and characterized in this work. The differential specific on-state resistance of the device is as low as 3.64 m ·cm2 with a total active area of 2.46×10-3 cm2 . Ti is the Schottky contact metal with a Schottky barrier height of 1.08 V and a low onset voltage of 0.7V. The ideality factor is calculated to be 1.06. Al implantation annealing is performed at 1250℃ in Ar, while good reverse characteristics are achieved. The maximum breakdown voltage is 1000 V with a leakage current of 9×10-5 A on chip level. These experimental results show good consistence with the simulation results and demonstrate that high-performance 4H-SiC JBS diodes can be obtained based on the double HARTE structure.     

Modulation of electroencephalograph activities by manual acupuncture stimulation in healthy subjects: An autoregressive spectral analysis

To investigate whether and how manual acupuncture (MA) modulates brain activities, we design an experiment that acupuncture at acupoint ST36 of right leg to obtain electroencephalograph (EEG) signals in healthy subjects. We adopt autoregressive (AR) Burg method to estimate the power spectrum of EEG signals and analyze the relative powers in delta (0 Hz-4 Hz), theta (4 Hz-8 Hz), alpha (8 Hz-13 Hz), and beta (13 Hz-30 Hz) bands. Our results show that MA at ST36 can significantly increase the EEG slow wave relative power (delta band) and reduce the fast wave relative powers (alpha and beta bands), while there are no statistical differences in theta band relative power between different acupuncture states. In order to quantify the ratio of slow to fast wave EEG activity, we compute the power ratio index. It is found that the MA can significantly increase the power ratio index, especially in frontal and central lobes. All the results highlight the modulation of brain activities with MA and may provide potential helps in clinical treatment of acupuncture. The proposed quantitative method of acupuncture signals may be further used to make MA more standardized.     

熔盐法制备NbSe2纳米棒及其摩擦学性能表征

采用熔盐法(KCl∶ NaCl=1∶1)成功制备出了形貌新颖并且结晶性良好的NbSe2纳米棒,研究了时间和温度对于其形貌的影响.用XRD,SEN以及TEM分别对NbSe2样品进行了分析和表征,结果表明产物为纯2H-NbSe2,并且产物晶型为典型的六方点阵.用UMT-2多功能摩擦试验机测试其作为石蜡添加剂的摩擦磨损性能并对摩擦机理进行了分析,结果表明熔盐法制备的NbSe2纳米棒的摩擦性能要优于固相法制备合成的单一片状NbSe2,显示出更为优良的减磨性能.