Carriers recombination processes in charge trapping memory cell by simulation

We have evaluated the effects of recombination processes in a charge storage layer, either between trapped electrons and trapped holes or between trapped carriers and free carriers, on charge trapping memory cell＇s performances by numerical simulation. Recombination is an indispensable mechanism in charge trapping memory. It helps charge convert process between negative and positive charges in the charge storage layer during charge trapping memory programming/erasing operation. It can affect the speed of programming and erasing operations.     

Size-dependent optical properties and carriers dynamics in CdSe/ZnS quantum dots

Size-dependence of optical properties and energy relaxation in CdSe/ZnS quantum dots （QDs） were investigated by two-colour femtosecond （fs） pump-probe （400/800 nm） and picosecond time-resolved photoluminescence （ps TRPL） experiments. Pump-probe measurement results show that there are two components for the excited carriers relaxation, the fast one with a time constant of several ps arises from the Auger-type recombination, which shows almost particle sizeindependence. The slow relaxation component with a time constant of several decades of ns can be clearly determined with ps TRPL spectroscopy in which the slow relaxation process shows strong particle size-dependence. The decay time constants increase from 21 to 34 ns with the decrease of particle size from 3.2 to 2.1 nm. The room-temperature decay lifetime is due to the thermal mixing of bright and dark excitons, and the size-dependence of slow relaxation process can be explained very well in terms of simple three-level model.     

科研生产单位职工继续教育的再认识

本文根据目前职业教育的性质，并依据科研生产单位中职工继续教育的情况和特点，较为详细的阐述了在科研生产单位中职工继续教育（再培训）的模式、实施原则、运作方式以及继续教育（再培训）成果的推广等一系列问题。     

高血压性脑出血再发生因素的Logistic分析

根据问题的特点 ,选择 Logistic判别模型 ,并借鉴普通线性回归的逐步向前法 ,用似然比统计量 ( Deviance)来筛选自变量 (因素 ) .结果显示 :在 1 1个因素中 ,有 3个是作用显著的 ,而其中舒张压值极为重要 .为降低再出血率 ,将其控制在 85 mm Hg以下是有效而可行的     

一道调研试题的探究

2010年南通市高三第二次调研测试第14题是:设函数f(x)=x2-ax+a+3,g(x)=ax-2a.若存在x0∈R,使得f(x0)<0与g(x0)<0     

蒸汽失活裂化催化剂沸石活性组元的再活化研究

研究了蒸汽失活的裂化催化剂的再活化过程.高温水蒸汽下失活的含Y型沸石的裂化催化剂在碱性水热条件下进行原位晶化处理并经过含铵离子的水溶液交换以恢复其裂化活性,在整个处理过程中保持催化剂的粒度不变.对含ZSM-5类沸石的失活裂化催化剂则采用含VA族元素的铵盐溶液处理,并在350℃～600℃的温度范围内进行焙烧来恢复其择形裂解活性.     

2010年《色谱》主要计量引证指标再创新高

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合成后再处理法制备含Ti介孔分子筛Ti-KIT-1

Mesoporous molecular series Ti-KIT-1 samples were prepared by three different post-handling methods using Ti(OEt)4 as the Ti source and KIT-1 as the support .The three post-synthetic methods were impregnated method,grafting method and colloidal method.The Ti-KIT-1 samples were characterized by FT-IR,DRS,XRD,TG-DSC and physical adsorption-desorption of nitrogen.Experimental results showed that the Ti-KIT-1 samples remained the original mesoporous structure with a smaller specific BET surface area compared to the parent KIT-1 sieve.DRS and FT-IR indicate the existence of tetrahedral titanium (Ⅳ),TG-DSC and chemical analyse method proved that TiO_2 weight percentage of grafting sample is much more than impregnated and colloidal samples.The grafting method is a good post-handling method that can effectively make use of a titanium source and promise the original mesoporous structure.     

重视典型事例的理论内涵 优化高中物理课堂教学——关于平抛运动在力学教学中应有地位的几点思考

科学理论的建立过程往往是人们对典型事例进行科学的观察、分析和归纳,再创造性地提出解释并对解释加以验证的过程.万有引力定律的建立过程就是其中一例,我们可以将该定律的建立过程大致划分成三个阶段: