Wet Oxidation of AlxGa1-xAs/GaAs Distributed Bragg Reflectors

The wet oxidation of AlGaAs with high Al content in a distributed Bragg reflectors （DBR） is studied by scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. Some voids distribute along the oxide/GaAs interfaces due to the stress induced by the wet oxidation of the AlGaAs layers. These voids decrease the shrinkage of the Al2O3 layers to 8% instead of the theoretical 20% when compared to the unoxidized AlGaAs layers. With the extension of oxidation time, the reactants are more completely transported to the front interface and the products are more completely transported out along the porous interfaces. As a result,the oxide quality is better.

Changes in grain-size and sedimentation rate of the Neogene Red Clay deposits along the Chinese Loess Plateau and implications for the palaeowind system

IEECAS SKLLQG

根据地质记录恢复渐新世和中新世不同时期环境空间特征及其意义

IEECAS SKLLQG

Average energy loss measured in single and double electron capture collisions of He2 on Ar at low velocities

Employing the recoil ion momentum spectroscopy we investigate the collision between He2+ and argon atoms. By measuring the recoil longitudinal momentum the energy losses of projectile are deduced for capture reaction channels. It is found that in most cases for single- and double-electron capture, the inner electron in the target atom is removed, the recoil ion is in singly or multiply excited states (hollow ion is formed), which indicates that electron correlation plays an important role in the process. The captured electrons prefer the ground states of the projectile. It is experimentally demonstrated that the average energy losses are directly related to charge transfer and electronic configuration.

不同类型原油污染土壤生物修复技术研究

对不同类型原油污染土壤在实用规模的预制床上采用堆制技术进行生物修复 .通过投加肥料、菌剂、控制水分和pH ,可使微生物获得较好的生态环境 .当稀油、高凝油、特稠油和稠油污染的土壤中原油总量为 2 5 .8～ 77.2 g·kg-1土时 ,经过近 2个月的运行 ,石油总量的去除率可达 38.37%～ 5 6 .74 % .石油中芳烃、沥青和胶质混合物是制约石油快速降解的主要因素 .在处理过程中筛选出石油降解的优势菌株 ,其中有 6株真菌、6株细菌和 1株放线菌 .研究结果为石油污染土壤异位生物修复技术实用化提供了理论依据 .

长白山生物圈保护区旅游的环境影响研究

生态旅游可以简单地定义为发生在那些具有独特的风景、特殊的生态学价值和具有纯粹自然性的受保护区域的旅游活动，也可以被理解为广义旅游的一部分，即可为自然和文化资源保护提供经济支持的一种旅游。根据生态旅游协会的定义（１９９１），生态旅游是一种前往自然区域以...

内蒙古农牧交错带生态工程成效实证调查和分析

作为生态工程的参与者和受影响者,农牧民对生态工程成效的评价、对未来生态工程措施的选择倾向具有重要的决策参考价值。将结构化问卷调查与开放式访谈相结合,对内蒙古自治区武川县、四子王旗和太仆寺旗3个旗县生态工程建设情况进行了调查研究。结果表明:退耕还林还草、围封禁牧以及季节性休牧是本区主要的生态工程类型;基于个体体验,农牧民并不认为生态工程取得了良好的、显著的生态效益;生态工程对农牧民的影响表现为"减产、提效、增收";对于未来的工程措施,农牧民优先选择限制牲畜数量,其次是退耕以及保护退化草地;绝大多数农牧民支持有补偿条件下进一步退耕和生态移民。本文进而给出了一些研究和政策建议。

Sensitive and Selective Determination of Cu2+ by Electrochemiluminescence of CdTe Quantum Dots

For the first time, we report a sensitive and selective method to detect Cu2+ based on the electrochemiluminescence quenching of CdTe quantum dots (QDs) in aqueous solution. The mercaptosuccinic acid (MSA) protected CdTe QDs were prepared and characterized with UV, fluorescence and ECL. The anodic ECL quenching mechanism was attributed to the fact that MSA capping was removed from the surface of the CdTe QDs and preferentially bound with Cu2+. The displacement of MSA capping layer created imperfections on the CdTe QDs surface, and eventually led to the ECL quenching.