Influence of growth temperature on structural and magnetic characterization of (In, Cr)As quantum dots

(In, Cr)As ferromagnetic semiconductor quantum dots (QDs) were grown by molecular beam epitaxy on GaAs (001) substrates. The growth temperature effects on structure and magnetism of the QDs were investigated systematically. The Cr(2+)3d(4) states and quantum confined effect are assumed to play an important role in the room-temperature ferromagnetism of (In, Cr)As QDs. (C) 2009 Elsevier B.V. All rights reserved.

Site controlling of InAs quantum wires on cleaved edges of AlGaAs/GaAs superlattices

Site-controlled InAs quantum wires were fabricated on cleaved edges of AlGaAs/GaAs superlattices (SLs) by solid source molecular beam epitaxy. The cleaved edge of AlGaAs/GaAs SLs acted as a nanopattern for selective overgrowth after selective etching. By just growing 2.0 ML InAs without high temperature degassing, site-controlled InAs quantum wires were fabricated on the cleaved edge. Furthermore, atomic force microscopy demonstrates the diffusion of In atoms is strong toward the [00 (1) over bar] direction on the (110) surface.

Organic light emitting diodes with an organic acceptor/donor interface involved in hole injection

Organic light emitting diodes with an interface of organic acceptor 3-, 4-, 9-, 10-perylenetetracarboxylic dianhydride (PTCDA) and donor copper phthalocyanine (CuPc) involved in hole injection are fabricated. As compared to the conventional device using a 5 nm CuPc hole injection layer, the device using an interface of 10 nm PTCDA and 5 rim CuPc layers shows much lower operating voltage with an increase of about 46% in the maximum power efficiency. The enhanced device performance is attributed to the efficient hole generation at the PTCDA/CuPc interface. This study provides a new way of designing hole injection.

蓝宝石衬底上单晶InAlGaN外延膜的RF-MBE生长

利用射频等离子体辅助分子束外延技术在蓝宝石衬底上外延了晶体质量较好的单晶InAlGaN薄膜．在生长InAlGaN外延层时，获得了外延膜的二维生长，卢瑟福背散射测量结果表明，InAlGaN外延层中In，Al和Ga的组分分别为2％，22％和76％，并且元素的深度分布比较均匀，InAlGaN（0002）三晶X射线衍射摇摆曲线的半高宽为4．8′，通过原子力显微镜观察外延膜表面存在小山丘状的突起和一些小坑，测量得到外延膜表面的均方根粗糙度为2．2nm．利用光电导谱测量InAlGaN的带隙为3．76eV．

一种镍基单晶合金的凝固行为

采用等温凝固方法研究了单晶镍基合金的凝固区间,利用DSC测试了合金的凝固曲线.结果表明:实验合金的液相线温度约为1380℃,固相线温度约为1310℃.合金的凝固顺序为: Lγ,L MC;γγ′;Lγ+MC.单晶合金的铸态组织中,W偏析于枝晶干, Ti,Cr,Mo和Ta偏析于枝晶间,偏析程度为: Mo>Ti>Cr>Ta, Al和Co几乎不发生偏析.1314℃1382℃1361℃1325℃

秦安中新世黄土-古土壤序列石英颗粒形态特征、粒度分布及其对成因的指示意义

IEECAS SKLLQG

长白山暗针叶林苔藓植物对三种针叶树种子萌发及幼苗生长的影响

研究了长白山暗针叶林两种主要地面苔藓植物——塔藓和拟垂枝藓对红松、红皮云杉和落叶松种子萌发及幼苗生长的影响.结果表明,在一定浓度下,塔藓浸提液抑制红松发芽,拟垂枝藓浸提液促进红松发芽;苔藓浸提液对红皮云杉和落叶松的发芽率没有显著影响,但不同程度地加快了种子日萌发高峰的出现.用苔藓植物体直接培养红皮云杉和落叶松种子,发现活植物体量大时对发芽率没有显著影响,但延迟了红皮云杉种子萌发高峰的出现,加速了落叶松种子萌发高峰的出现;杀青后的苔藓植物体则明显地抑制种子发芽.通过幼苗培养实验,发现苔藓植物浸提液抑制红皮云杉和红松幼苗生长,但促进了落叶松幼苗的生长;不同处理的苔藓植物体对幼苗生长的影响差异较大,活植物体量大时,两种苔藓均促进了红皮云杉和落叶松幼苗生长,而杀青后植物体则明显地抑制幼苗生长.

Cytotoxicity of liver targeted drug-loaded alginate nanoparticles

In this study, novel liver targeted doxorubicin (DOX) loaded alginate (ALG) nanoparticles were prepared by CaCl2 crosslinking method. Glycyrrhetinic acid (GA, a liver targeted molecule) modified alginate (GA-ALG) was synthesized in a heterogeneous system, and the structure of GA-ALG and the substitution degree of GA were analyzed by H-1 NMR, FT-IR and elemental analysis. The drug release profile under the simulated physiological condition and cytotoxicity experiments of drug-loaded GA-ALG nanoparticles were carried out in vitro. Transmission electron micrographs (TEM) and dynamic light scattering (DLS) analysis showed that drug-loaded GA-ALG nanoparticles have spherical shape structure with the mean hydrodynamic diameter around 214 +/- 11 nm.

The effect of nocodazole on the transfection efficiency of lipid-bilayer coated gold nanoparticles

Nonviral vectors are safer than viral systems for gene therapy applications. However, the limited efficacy always prevents their being widely used in clinical practice. Aside from searching new gene nonviral vectors, many researchers focus on finding out new substances to improve the transfection efficiency of existent vectors. In this work, we found a transfection enhancer, nocodazole (NCZ), for dimethyldioctadecylammonium (DODAB, a cationic lipid) bilayer coated gold nanoparticles (AuNPs) mediated gene delivery. It was found that NCZ produces 3-fold transfection enhancement to HEK 293T cells assessed by flow cytometry (FCM). The result was further confirmed by luciferase assay, in which NCZ induced more than 5 times improvement in transfection efficiency after 48 h of transfection. The results from the inductively coupled plasma mass spectrometry (ICP-MS) and FCM showed that NCZ did not affect the internalization of DODAB-AuNPs/DNA complexes. The trafficking of the complexes by transmission electron microscopy (TEM) indicated that the interrupted transportation of the complexes to the lysosomes contributed greatly to the transfection enhancement.

Determination of three beta-blockers by capillary electrophoresis with end-column electrochemical detection

Three beta -blockers (propranolol, timolol, acebutolol) were separated by capillary electrophoresis (CE) and detected by end-column electrochemical detection (EC). In the present work, a carbon fiber (33 mum) electrode was used as the working electrode. The effect of the buffer concentration, buffer pH, detection potential and separation voltage on the separation of analytes and behavior of electrochemical detection was systematically investigated. The optimum conditions determined were as following: 40 cm length, 25 mum i.d. capillary; 17.5 kV separation voltage; 2 s injection at 15 kV; 70mM phosphate buffer, pH 3.5; detection potential + 1.2V (vs. Ag/AgCl). Under these conditions, the linear ranges of beta -blockers were over three orders of magnititude and the low detection limit of 10(-8)M was obtained. This method was also applied to detect the simulated urine sample.