Luminescence and resonant energy transfer of two sizes of CdTe quantum dots embedded in gelatin films

We have used two sizes of highly monodisperse colloidal CdTe nanocrystals (or quantum dots) and gelatin to form quantum dots (QDs)-gelatin films. Photoluminescence (PL) results for the mixed systems show that the quenching of the emission of the small dots was accompanied by the enhancement of the emission of the large dots as their average separation decrease. The phenomena were attributed to the occurrence of the long-range resonance transfer (LRRT) between two different sizes of QDs when the concentration of the gelatin is low enough to ensure the close proximity of the dots. Determined by the overlap between the emission spectrum of the donor QDs (small dots) and the absorption spectrum of the acceptor QDs (large dots), FRET provides efficient coupling between two different sizes of QDs via long-range dipole-dipole interaction. The PL spectrum changes were also confirmed by true-color images of the mixed QDs system, which show that the colors change gradually from red to green at the gelatin concentrations varying from 0.01% to 0.25 wt% in their initial solution. The experimental results are expected to open new opportunities to modulate the luminescence of semiconductor QDs in a simple way.     

Effect of Grain Size of CaCO3 and SiO2 on the Formation of C3S Under Different Conditions

The effect of grain size of CaCO3 and SiO2 on the formation of C3S under various conditions, such as rapid heating rate（800 ℃/min）, normal heating rate（30 ℃/min） and in the presence or absence of ZnO, was studied. The results show that the decomposition temperature of CaCO3, the temperature of appearance of liquid phase and the f-CaO content descend when the grain size of CaCO3 and SiO2 becomes smaller, which attributes to the reactive activity enhancement of powders due to the decrease of the particle size. When the grain size of CaCO3 and SiO2 is below 1 μm, the rate of the formation of C3S is greatly raised. A rapid sintering rate and the presence of ZnO have an important effect on the formation of C3S and can lower the temperature of the formation of C3S by about 50 ℃.     

印制板行业水污染中铜的困扰

叙述印制板行业目前执行的水污染物排放的国家和地方标准,在污水处理中如何解决铜含量达到国家二级标准(1.0mg/L)和一级标准(0.5mg/L)的困扰,叙述铜对人体和动植物的毒害情况,世界各国污水排放铜的标准,提出了改变这种状况的建议。     

国际无线电、通讯和电磁协会EMC认证

国际无线电、通讯和电磁协会(iNARTE)EMC认证是国际公认的EMC专业人员认证项目,通过iNARTEEMC认证是个人专业能力的有效证明,拥有iNARTE EMC认证通过者是公司EMC技术实力的重要体现.介绍了iNARTEEMC认证的意义、考查范围、具体要求和认证流程,以促使国内EMc同行尽快了解和接受iNARTE认证.     

面向信息检索的近邻语言模型

面向信息检索的语言模型对单篇文档构建语言模型,存在较严重的数据稀疏问题。该文认为利用文档的近邻信息能够更合理地反映词在文档中的分布,有助于数据稀疏问题的解决,因此将文档的近邻信息加入语言模型的平滑算法中,提出近邻语言模型。该文在TREC评测的典型文档集美国能源署文件(DOE)和《华尔街日报》(WSJ)数据集上测试了在不同近邻选择来源上近邻语言模型的性能。实验结果表明,近邻语言模型对检索性能有一定的提升。     

浅谈气压机的飞动

介绍了催化裂化气压机飞动的原因和现象,并就生产中工艺调节上如何防止气压机的飞动提出了自己的观点.     

超高压聚乙烯管式反应器R401缺陷评定

参照英国R6评定方法及美国ASME规范第Ⅺ篇IWB-3640,IWB-3650等评定方法,结合断裂力学有关理论和材料的试验数据,对超高压自增强反应管进行了缺陷评定,得到了无残余应力后的裂纹扩展寿命和反应管满足破前漏结论.     

904L钢的性能及在精对苯二甲酸装置中的应用

主要论述了高镍不锈钢９０４Ｌ的一般性质、耐腐蚀性能等，介绍了其在精对苯二甲酸（ＰＴＡ）装置中的使用情况     

石脑油加氢装置冷却器的腐蚀与防护

大庆石化分公司炼油厂石脑油加氢装置冷却器（E-107），由于爆沸-活化腐蚀、垢下腐蚀和应力腐蚀，致使换热管外表面出现溃疡点，甚至穿孔，折流板也发生均匀腐蚀。后来，对管束采取镀Ni-P防腐蚀措施，经三年多运行考核，未发现泄漏，收到了较满意的效果。     

进口烟机轮盘的激光熔敷修复

烟机是催化裂化的关键设备，轮盘损伤后更换费用很高，采用激光熔敷的办法修复即不影响轮盘母材的机械性能，费用又低。