高岭石基复合材料在光催化领域应用的研究进展

环境污染和能源紧缺已成为当今社会亟须解决的重大问题。高岭石基复合材料光催化处理技术因绿色环保、经济安全、无二次污染而备受关注。鉴于高岭石在光催化领域的研究现状,本文介绍了高岭石的层状硅酸盐结构特征及其在光催化领域的应用优势,综述了高岭石基光催化材料的主要类型、基本特征、合成方法、改性过程、光催化特点及其应用进展与优势,最后,提出了高岭石基复合材料在光催化领域应用的重点研究方向。以期获得制备工艺简单、光催化性能优异、原料易获取且无环境污染的高岭石基光催化复合材料,从根本上解决环境污染问题,缓解能源紧缺危机。     

基于全国大学生物理实验竞赛命题导向的物理实验教学探索

综合分析了历届全国大学生物理实验竞赛命题的特点和导向,从学生培养、实验室建设和实验教师能力提升等方面探讨物理实验教学改革的方向.全国大学生物理实验竞赛的基础题命题立足于基本知识点的考核,其衍生内容为实验改进提供了思路和素材;综合题的命题体现了聚焦经典物理理论、国际前沿性、技术引领性和综合性的特点,对学生阅读文献能力、融会贯通的物理思维能力、团队合作能力进行了考核.物理实验教学应在一定程度上融入通识教育的内涵,培养学生科学的操作习惯、科学的思维方式.基础物理实验室的建设在注重高精尖测量设备的配套同时,应该保持传统的开放和自组的经典实验,保持一定的通用测量仪器的更新率.专题式实验教学对实验教师的知识体系有了更高的要求,教师既要熟悉基础测量,又要了解科研前沿,紧跟行业进步.     

光电探测器组件光纤耦合移位特性分析

光电探测器组件响应度下降会造成光纤陀螺输出异常,响应度下降的主要原因为光纤耦合移位,分析光纤耦合移位的原因并采取有效措施可提高探测器组件的使用可靠性。通过对探测器尾纤出射高斯光斑在探测器管芯端面数学积分,计算出光纤耦合效率系数与光纤耦合间距及光纤偏转角度的关系,计算结果与实际封装探测器组件指标一致。根据计算结果,从光纤移位、探测器管芯移位和管壳形变三个方面分析了耦合移位的影响因素,提出避免探测器使用中发生耦合移位的措施,并通过试验验证了耦合焊接缺陷会造成探测器试验后响应度下降,采取耦合对准控制措施后封装的探测器试验后响应度保持稳定。     

含左手材料光纤的表面模特性

在弱导条件下,利用Maxwell方程组,对纤芯是左手材料,包层是右手材料的光纤表面模进行了研究,得到了TE (TM)、 EH和 HE表面模的色散方程,.根据色散方程,画出了相应表面模和含左手材料光纤导模的色散曲线.比较这些色散曲线,发现了含左手材料光纤表面模一些新的特性.     

Trichloromethyl chloroformate ("diphosgene"), ClCOOCCl3: structure and conformational properties in the gaseous and condensed phases

The conformational properties of gaseous trichloromethyl chloroformate (or "diphosgene"), ClC(O)OCCl3, have been studied by vibrational spectroscopy [IR (gas), IR (matrix), and Raman (liquid)] and quantum chemical calculations (MP2 and B3LYP with 6-311G basis sets); in addition, the structure of a single crystal at low temperature has been determined by X-ray diffraction. ClC(O)OCCl3 exhibits only one conformational form having Cs symmetry with a synperiplanar orientation of the C-O single bond relative to the C=O double bond. The calculated energy difference between the syn and anti forms, 5.73 kcal mol(-1) (B3LYP) or 7.06 kcal mol(-1) (MP2), is consistent with the experimental findings for the gas and liquid phases. The crystalline solid at 150 K [monoclinic, P2(1)/n, a = 5.5578(5) angstroms, b = 14.2895(12) angstroms, c = 8.6246(7) angstroms, beta = 102.443(2) degrees, Z = 4] likewise consists only of molecules in the syn form.     

哌啶并噻吩并嘧啶酮衍生物结构和活性的密度泛函理论研究北大核心CSCD

采用密度泛函理论中的广义梯度近似(DFT/GGA)方法,在PW91/DNP水平上研究了七种哌啶并噻吩并嘧啶酮衍生物的结构,化学活性和前线轨道.结果表明:含有卤素化合物的前线轨道能隙(Eg)降低,7b,8b,9b的能隙比7a,8a,9a分别低0.053,0.063,0.010eV.含有卤素的化合物中,Eg越小,对水稻纹枯菌(Rhizoctonia solani bacteria)的抑制率越高,而不含卤素的化合物中,Eg越大,对苹果轮纹菌(Dothiorella gregaria bacteria)的抑制率越高.     

以RF/SiO2复合气凝胶为前驱体制备介孔α-SiC

以间苯二酚(R)和甲醛(F)为碳源,3-氨丙基三乙氧基硅烷为硅源,无水乙醇为溶剂,利用简捷的一步溶胶-凝胶法和超临界干燥工艺制备RF/SiO2复合气凝胶。RF/SiO2复合气凝胶经碳热还原、煅烧、酸洗等一系列工艺制备出介孔碳化硅(SiC),采用XRD、FTIR、NMR、SEM、TEM和氮气吸附-脱附等分析手段对制备的介孔SiC进行了表征。结果表明,介孔SiC材料为纯的α-SiC,平均晶粒大小为15 nm,BET比表面积为106 m2·g-1,孔径主要分布在21.7 nm和61 nm附近,SiC纳米颗粒大小和分布均匀。     

Phase diagram of trivalent and pentavalent patchy particles

We compute the equilibrium phase diagram of two simple models for patchy particles with three and five patches in a very broad range of pressure and temperature. The phase diagram presents low-density crystal structures which compete with the fluid phase. The phase diagram of the five-patch model shows re-entrant melting, in analogy with the previously studied four-patch case, a metastable gas-liquid critical point and a stable, high-density liquid. The three-patch model shows a stable gas-liquid critical point and, in the region of temperatures where equilibration is numerically feasible, a stable liquid phase, suggesting the possibility that in this small valence model the liquid retains its thermodynamic stability down to the vanishing range limit.     

Using evidence from nanocavities to assess the vibrational properties of external surfaces

Internal surfaces of nanocavities are an exceptionally useful laboratory wherein one can spotlight the factors ruling the intricate interplay between morphology and chemistry at silicon surfaces. At the same time, they offer unparalleled opportunities to validate the assignment of vibrational signals of silicon-terminating species under almost ideal experimental conditions. In the case of hydrogen, evidence will be provided of the detailed evolution of H-related species at surfaces depending on their orientation. Also, preliminary results concerning nitrogen at and around nanocavity surfaces will be reported.     

Dual-channel phase-shifting interferometry for microscopy with second wavelength assistance

Dual-channel phase-shifting interferometry for simultaneous phase microscopy is presented. Red and blue light beams are used for microscope illumination. A 45 tilted beamsplitter replicates the object and reference waves in red light together with the object wave in blue light into two parallel beams. The two resulting quadrature phase-shifting interferograms in red light and the object waves in blue light are generated in the two channels. The two interferograms are recorded simultaneously by a color charge-coupled device (CCD) camera, and can be separated via RGB components of the recorded color patterns without crosstalk. As a result, the phase of tested specimen can be retrieved. The feasibility of the proposed method is demonstrated by test performed on a microscopic specimen.