Ab initio studies on the mechanic and magnetic properties of PdHx

Based on ab initio total energy calculations,the structural,electronic,mechanic,and magnetic properties of PdH x are investigated.It is found that bulk modulus of PdH x is larger than the metal Pd with the hydrogen storage except Pd 4 H 2.The calculated results for the magnetic moments show that the hydrogen addition weakens the magnetic properties of the PdH x systems.A strong magneto-volume effect is found in PdH x structures as well as Pd.The transition from paramagnetism to ferromagnetism is discussed.The corresponding densities of states for both structures are also shown to understand the magnetic behaviour.     

氧化硅中纳米晶硅薄膜的低温沉积及其键合特性研究

以Ar和H2为溅射气体,采用Si和SiO2双靶活性溅射技术实现了镶嵌纳米晶硅(nc-Si)的富硅氧化硅(SiOx)薄膜的300℃低温生长,并分析了氢气掺入对薄膜微观结构及键合特性的影响.结果表明,氢气流量比的增加导致纳米硅粒子尺寸增加,而生长速率逐渐减小.薄膜中Si-O键合结构以Si(O4)键为主,随H2流量比的增加,Si-O4-nSin(n=0,1)键密度减小,Si-O4-nSin(n=2,3)和SiH2键密度持续增加,而所对应Si-H键密度呈现先减小后增加趋势,该结果可解释为等离子体内氢原子对反应前驱物中氧的去除效应增强和氢原子与表面氧的解吸附反应几率的增加.     

Magnetism of Zr atomic wires

By using the full-potential linearized augmented plane wave method to perform ab initio total energy calculations, we have explored magnetic ordering in one-dimensional Zr wires. The result shows that Zr can form linear, or dimerized, or zigzag wires, and the magnetic properties strongly depend on their geometric structures. The linear and zigzag wires exhibit ferromagnetic ground states at the equilibrium bonding distance, while the dimerized wire, despite its higher stability than that of the linear one, exhibits nonmagnetic ground states. The most stable geometry is shown to be the zigzag wire with a magnetic moment of 0.26μB per atom.     

ρ-VOF:一种可清晰模拟自由界面的两相流方法

文章通过对EFM(effective field modeling)模型进行简化, 消除了原模型的非守恒性项和非双曲性特性项, 发展了一种基于密度的气液两相流模拟方法: ρ-VOF方法.利用体积分数信息对控制单元内的自由界面进行重构, 得到了控制单元内流体的空间分布, 并采用AUSM+-up格式获得考虑气液流体接触间断信息的对流通量.新方法可统一处理激波间断和接触间断的相互作用, 保持自由界面的尖锐性, 并且其计算量与自由界面的空间复杂度无关.最后, 数值模拟了液体激波管气液激波管和气体激波跨二维液滴传播等问题, 并与文献结果进行对比, 验证了本方法在气液两相流模拟中的准确性.      

硝基苯类化合物对小鼠急性毒性LD50的QSAR研究

本文选取45个典型硝基苯类化合物的小鼠半致死浓度毒性数据,利用遗传算法和多元线性回归分析,构建了硝基苯类化合物结构与急性毒性LD50的定量构效关系。模型的相关系数R2和内部交叉验证系数Q2分别为0.819和0.732,均方根误差为0.243。结果表明,该模型具有较好的预测能力和稳健性。通过模型中筛选出的描述符可知,硝基苯类化合物的急性毒性与氢键的数量以及结构拓扑学参数有较强的相关性。     

芘分子共价修饰的硅纳米线制备及其发光性能表征

将功能分子共价链接于硅纳米线表面,是发展硅纳米线性能,获得新的硅纳米线器件材料的重要手段.但是对硅纳米线表面的修饰却存在产生不可控制的表面氧化层的缺点,因此有必要发展一种温和的新方法.本文通过羟基(—OH)与硅纳米线表面Si—H键反应生成Si—O—C键,从而在硅纳米线表面引入功能分子.并通过芘醇分子在硅纳米线表面的固定化,证明了这一方法能够温和地实现对硅纳米线表面的共价键修饰.     

Si-O-C骨架支撑型高循环性能锂离子电池硅基负极材料(英文)

通过经济有效的方法制备得到一种具有长循环寿命的高效稳定性硅/硅氧碳/无定形碳的复合负极材料结构.在这种结构中,以具有稳定化学性能的硅氧碳结构作为骨架,来支撑和隔离硅纳米颗粒结构.材料中包含的无定形碳组分可提高硅/硅氧碳结构的电导性能.这种复合负极结构在0.3C电流充放电情况下,不仅能发挥出637.3 mAh·g-1的比容量,而且在经过100周的充放电循环后,其容量保持率也达到86%.这种新型硅基负极材料的设计为其他功能材料的设计提供了一种潜在可能的方法.     

First-principles study of diffusion behaviour of point defects in the O-terminated (0001) surface in wurtzite ZnO

A detailed first-principles study of the diffusion behaviour of point defects in the O-terminated (0001) surface in wurtzite ZnO was performed. The O vacancy and interstitial are found to diffuse much more easily in surface than in bulk. The Zn vacancy has a similar migration barrier for both bulk and surface, but has much smaller barrier for the diffuse-in process. The Zn interstitial is difficult to diffuse in the surface directly, but it can diffuse into the bulk relatively easily. Specific values of corresponding migration barriers are obtained.     

Mechanical and Magnetic Properties of Rh and RhH： First-Principles Calculations

Mechanical and magnetic properties of Rh in bcc, fcc structures and RhH in cubic structure are investigated by using first-principles calculations. Theoretical strengths of these structures are given for the first time. The results show that the NaCl-type cubic RhH has a lower bulk modulus and a theoretical strength larger than those of Rh in bcc and fcc structures. A strong magneto-volume effect of a transition from low magnetic moment-low cell volume＇＇ to high magnetic moment-large cell volume＇＇ is also found for both the bcc and fcc Rh structures as well as RhH.     

四物汤及其单味药振荡反应的微量量热法研究

采用微量量热法对四物汤及其单味药振荡体系进行了研究, 测定了四物汤及其单味药在不同浓度、不同温度下的振荡体系的热功率-时间曲线, 得到了它们的诱导期、振荡周期, 根据非平衡态理论计算了它们的反应级数和表观活化能, 并建立了诱导期、振荡周期与浓度和表观活化能之间的非线性关系式.