表面活性剂-纳米粒子协同稳定Pickering乳液的双相反转实验设计

本实验以表面活性剂原位改性纳米粒子协同稳定Pickering乳液为研究对象,通过对乳液的双相反转行为研究,探究表面活性剂分子在纳米粒子表面的吸附模式,加深学生对胶体与界面化学领域相关原理的理解,培养学生综合实验能力和分析推理能力。     

IVB族过渡金属氮化物弹性与光学性质研究

基于密度泛函理论平面波方法研究了IVB族过渡金属氮化物TiN, ZrN, HfN的电子结构、 弹性性质和光学性质. 研究表明, IVB族过渡金属氮化物晶格的电子结构分别体现了共价性、 离子性和金属性, 且基态下体系呈金属性. 各晶格在坐标基矢方向上的杨氏模量的数值与体对角线方向上的差距明显, 体现出典型的弹性性质各向异性, 这导致了实验研究在制备其薄膜时不可避免地产生晶格畸变与微裂纹. 伴随着态密度中赝隙的红移, TiN, ZrN, HfN的金属性依次增强, 使得材料在力学性能方面脆性减弱, 单晶的各向异性程度提升, 以及光学性质方面电子跃迁机理由带内跃迁到带间跃迁转变所需入射光子能量的蓝移和光谱选择性能的下降. 因此, 通过降低IVB族过渡金属氮化物中自由电子的组分以加强材料的共价性, 有利于提高材料弹性性质的各向同性, 改善材料的光谱选择性能. 关键词： 第一性原理 弹性性质 光学性质     

双靶反应共溅射制备WC薄膜及其电催化性能

以金属钨靶和石墨靶反应共溅射的方法,在硅片上制备碳化钨薄膜.实验探究了功率和衬底温度对薄膜成分、质量的影响.研究表明,衬底温度为400℃时,薄膜生长致密、均匀,无裂痕;当钨靶功率为55 W,逐渐增大石墨靶功率时,薄膜成分分别为W、W2C、WC1-x.经电化学研究发现W2C、WC1-x两种薄膜均对甲醇有电催化作用,且有很高的比表面积,面积为1 cm2的W2C、WC1-x薄膜电极对应的比表面积分别为33.32 cm2和64.68 cm2.     

浅谈应用多媒体技术进行物理课堂的有效教学

<基础教育课程改革纲要>(试行)中明确指出:要大力推进信息技术在教学过程中的普遍应用,促进信息技术与学科课程的整合,逐步实现教学内容的呈现方式、学生的学习方式、教师的教学方式和师生互动方式的变革,充分发挥信息技术的优势,为学生的学习和发展提供丰富多彩的教育环境和有力的学习工具.     

回归基础——例析2011年高考题中的数列问题对高考备考复习的启示

数列问题在近几年的江苏高考中均有体现,而且大多为高考数学压轴题,对学生解决数列问题的技巧和方法有着非常高的要求,教师在复习备考过程中进行了大量的数列的习题训练,但是效果不佳.其实高考题具有很强的代表性和示范性,对高考题进行深入地探索,挖掘其潜在的价值,能有效地避免陷入"题海"战术,减负增效.譬如,2011年江苏高考数学试题最后一道压轴题是一道数列问题,只要学生平时认真落实了课本上关于等差数列概念及相关知识,掌握一些分析问题与解决问题     

Anisotropy of elasticity and minimum thermal conductivity of monocrystal M4AlC3 （M = Ti,Zr, Hf）

The elastic constants, elastic anisotropy index, and anisotropic fractional ratios of Ti4AlC3, Zr4AlC3, and Hf4AlC3 are studied by using a plane wave method based on density functional theory. All compounds are characterized by the elastic anisotropy index. The bond length, population, and hardness of the three compounds are calculated. The degrees of hardness are then compared. The minimum thermal conductivity at high temperature limitation in the propagation direction of [0001](0001) is calculated by the acoustic wave velocity, which indicates that the thermal conductivity is also anisotropic. Finally, the electronic structures of the compounds are analyzed numerically. We show that the bonding of the M4AlC3 lattice exhibits mixed properties of covalent bonding, ionic bonding, and metallic bonding. Moreover, no energy gap is observed at the Fermi level, indicating that various compounds exhibit metallic conductivity at the ground state.     

分光光度法测定饮料中六偏磷酸钠添加剂

在pH 8.6的Tris-HCl缓冲溶液中,六偏磷酸钠使天青B在溶液中发生聚集,溶液由天蓝色逐渐变为紫色,体系的吸光度降低,光散射增强.在优化条件下,在6.0 ×10-7～1.0×10-5 mol/L范围内,天青B在602 nm处的吸光度降低与六偏磷酸钠浓度呈良好的线性关系,检出限(3σ)为 5.3 ×10-7 mol/L.对浓度为5.0×10-6 mol/L的六偏磷酸钠溶液平行测定11次,其相对标准偏差为 2.5%.本方法用于饮料中添加剂六偏磷酸钠含量的分析,平均标准加入回收率为99.5%～112.3%,可实现六偏磷酸钠的可视化半定量检测.     

硫酸溶液中聚天冬氨酸对碳钢的吸附缓蚀性能

应用电化学极化曲线和交流阻抗研究聚天冬氨酸(PASP)对碳钢的缓蚀性能,讨论了PASP浓度和温度对缓蚀效果的影响.结果表明:PASP是一种以抑制阳极为主的缓蚀剂.在实验温度范围内,PASP在0.5mol/L硫酸溶液中对碳钢的缓蚀效率随着温度升高而降低,并以10℃时的缓蚀效果最好.在给定温度下,缓蚀率均随PASP浓度的增加而迅速增加,但当PASP质量浓度达到2.5g/L时,缓蚀率的增加趋于平缓,10℃下,缓蚀率的最高值可达80.33%(PASP 6.0g/L),PASP在碳钢表面的吸附基本服从Freund lich吸附等温式,PASP的加入增大了碳钢的腐蚀反应表观活化能.     

Effect of pressure on the elastic properties and optoelectronic behavior of Zn_4B_6O_(13): First-principles investigation

The hydrostatic-pressure-dependent mechanical stability and optoelectronic behavior of Zn_4B_6O_(13)(ZBO) are calculated using the exchange-correlation functional Perdew–Burke–Ernzerhof generalized gradient approximation and the hybrid functional PBE0 based on density functional theory. The calculated and experimental unit cell volumes and Vickers hardness of ZBO at zero pressure agree well. ZBO is mechanically stable under the critical pressure of 52.98 GPa according to the generalized stability criteria. Furthermore, Young's modulus and Vickers hardness decrease with increasing hydrostatic pressure. The strength and type of ZBO bonds are investigated by population and electron density difference. The electronic structure at zero pressure reveals that ZBO is an indirect band gap semiconductor, and the calculated 5.62-e V bandgap coincides well with the 5.73-e V experimental value, highlighting the success of the hybrid functional PBE0 calculations of electronic properties. The band gap almost increases as a second-order polynomial of pressure, and the indirect nature does not change with the applied external pressure. The optical reflectivity and absorption coefficient show that ZBO is an excellent ultraviolet photodetector. Our calculation results suggest that the elastic and optical properties of ZBO are highly stable over a wide pressure range.