Surface-enhanced Raman Spectroscopic Study of Gold Nanoparticles with Different Shapes

【中文文摘】使用514 5nm激光激发,第一次得到了不同形状金纳米粒子的表面增强拉曼光谱(SERS)。一般情况下,较短波长(600nm)的激发。然而,对特殊形状的自组装金纳米粒子,由于避雷针效应,即使使用绿光激发也可获得很高增强的SERS。 【英文文摘】In this communication, we obtained for the first time the SERS spectra of gold at the laser excitation of 514.5 nm by fabricating the ordered array of gold nanoparticles with special shapes, e.g., sphere, tadpole, and pearlchain. Selfassemble method of these gold nanoparticles is briefly introduced. In general, the enhancement of gold by the laser excitation of short wavelength (600 nm) becuase that the coupling between conduction electrons and interband electronic transitions by using 514. 5 nm depresses the quality of the surface plasmon resonance of gold metals considerably. Our observation reveals that the SERS of self2assembly gold nanoparticles with special shape can be rather high even using the green light excitation , which is mainly due to the lightning2rod effect.国家自然科学基金创新群体研究资助项目(20021002);; 国家自然科学基金九五重点项目(29833060

The Size and Shape Effects on the Optical Properties of Gold Nanoparticles

【中文文摘】纳米尺度的金属及半导体呈现出特殊的光学、电学及磁学性质,采用近年发展起来的离散偶极近似(DDA)的方法,我们分析了金纳米粒子的尺寸及形状对其光学性质的影响。粒子周围介质的影响在文中亦作了分析。计算结果显示,金纳米粒子的等离子体吸收带同时受到粒子尺寸和形状的影响,但来自形状的影响更为明显。与米氏理论及扩展的甘氏理论相比较,DDA方法在粒子尺寸不再远小于入射光波长的时候更准确,并能应用于任何形状的纳米粒子。理论计算与实验结果能较好的吻合。 【英文文摘】Metals and semiconductors exhibit unusual optical, electronic, and magnetic properties at the nanometer scale. Based on the newly developed method, discrete dipole approximation (DDA), the dependence of the optical properties of the gold nanoparticles on the size and shape was analyzed. The effects of the surrounding medium were also taken into consideration in the calculation. The calculated results show that the plasmon absorption band depends on both the size and shape of the gold noanoparticles. However , the influence of the shape is more significant . Compared to the Mieps theory and the extension , Gansp theory , the DDA method is more accurate when the dimensions of the particles are not much smaller than the wavelength of the incident light and can be applied to particles of any shape. The theoretical results are in good agreement with the experimental data.国家自然科学基金项目,批准号为 :20003008,2983306

不同氮水平下有机肥碳氮比对土壤硝态氮残留量的影响

采用盆栽试验的方法,研究N0(不施氮)、N1(施N 0.067 g/kg)、N2(施N 0.133 g/kg)、N3(施N 0.266g/kg)、N4(施N 0.400 g/kg)4个不同氮水平下施入M1(C/N:31.8)、M2(C/N:42.5)、M3(C/N:66.6)不同C/N的有机肥对土壤NO3-残留量的影响。结果表明:在N0,N1,N2水平下,3种不同C/N的有机肥对土壤NO3-残留量的影响不显著,在N3,N4水平下,M1能够增加土壤NO3-的残留量,M2和M3能够降低土壤NO3-的残留量。N3M1,N4M1处理的土壤NO3-含量分别比N3,N4处理增加了11.6%和14.4%;N3M2,N3M3处理分别比N3处理降低了15.9%和37.9%;N4M2,N4M3处理与N4处理相比差异不显著

The Research for the Employment of the Students with Financial Difficulties in Universities——Based on the Analysis for the Employment Status, the Job-seeking Process and the Results

文章使用方差分析、卡方分析以及logistic回归等方法,对某大学毕业生就业情况进行数据分析,发现经济困难学生升学比例、人力资本较高,但求职过程与非经济困难学生相比,并无统计学显著差异;访谈发现"双困"学生主要来自中西部偏远地区。基于上述结果,本文认为经济困难学生应树立求职信心;学校帮扶应有针对性,做到分类指导,"精准帮扶"。Using variance analysis, chi square analysis and logistic regression, analysed the employment situation of graduates, found the economic difficulties students had higher enrollment ratio and human capital, but compared non economic difficulties students, there was no statistically significant difference in job search process; the "double storm" students were mainly from remote areas of the Midwest. Based on the above results, the paper believed that economic difficulties students should establish job confidence; school aid should be targeted, do classification guidance, precision helping.教育部人文社科重点研究基地重大项目“大学生结构性失业的教育审视与治理”(编号:11JJD880026)成

气候变化影响及其适应的经济学评估

分析了英国尼古拉斯•斯特恩领导完成的“从经济学角度看气候变化”报告的主要内容，并从科学基础、气候变化中的经济学问题、减排行动的政策与经济因素、适应行动的效益分析以及全球合作应对气候的意义等5个方面对报告的主要内容、立场和结论进行了介绍。报告认为，气候变化是不争的事实，如果人类按照目前的模式继续发展下去，到21世纪末，全球温度可能会升高2～ 3℃ 以上。这将会造成全球经济的GDP比重下挫5％～10％ ，而贫穷国家则会超过10％ 。如果现在即采取措施，在2050年前把温室气体浓度控制在450～550ppm的水平上，减排的成本大约仅占GDP的1％ 。报告提出，要建立长期稳定的碳价格政策、低碳技术发展政策、消除阻碍减排行动的障碍因素，保证温室气体减排行动的有效实施。全球合作和以适应为目标的气候行动目前在经济上是可行的，并有利于气候目标的实现