Polymer-controlled synthesis of Fe3O4 single-crystal nanorods

In this study, we describe a simple approach to preparing single-crystal Fe3O4 nanorods in the presence of poly(vinylpyrrolidone) (PVP). The morphologies of the nanorods are characterized by transmission electron microscopy (TEM), which indicates that these nanorods are formed by nucleation and growth process in situ in aqueous solution. A superconducting quantum interference device (SQUID) magnetometer characteristic of the as-synthesized Fe3O4 nanorods shows superparamagnetic properties.     

微生物燃料电池非生物阴极催化剂的研究进展

在微生物燃料电池（MFC）中,以氧为电子受体具有很多优点,但氧阴极还原的反应动力学慢,会造成阴极电势的损失。 因此,提高阴极对氧还原的电催化活性和降低催化剂的价格是MFC非生物阴极催化剂的研究重点之一。 本文综述了近年来MFC中非生物阴极氧还原催化剂的研究进展。 重点讨论了贵金属Pt、过渡金属大环化合物以及金属氧化物催化剂对氧还原的电催化活性。 其中,非贵金属氧化物及过渡金属大环化合物催化剂具有良好的性能,而且价格低廉,有望成为MFC非生物阴极Pt基催化剂的替代催化剂。     

氧化多孔硅/聚合物复合膜的折射率

用Bruggeman模型理论,分析了氧化多孔硅/聚合物复合膜的等效折射率与多孔硅孔隙率、氧化度和嵌入率的关系.实验研究了嵌入PMMA材料的氧化多孔硅/聚合物膜的等效折射率.证实了在多孔硅中嵌入聚合物可使薄膜的光学参量保持稳定.     

一种引入实体的地理语义相似度混合计算模型

针对现有地理语义相似度计算模型欠考虑实体层次影响因素问题,提出了一种引入实体的地理语义相似度混合计算模型.该模型在已有研究基础上,综合分析了语义相似度概念间的关系、本体结构、属性和实体的几何特征等影响因素,并用各影响因素的综合相似度结果度量地理概念间的语义相似度.最后,通过计算土地利用类型概念语义相似度验证了模型的有效性.     

基于时空老化模型的服务端瓦片缓存置换算法

随着网络地理信息服务（network geographic information service,NGIS）向云服务演进,客户端瓦片缓存架构的应用局限性逐渐体现。为提升瓦片服务的性能,在老化算法的基础上,综合分析了瓦片访问长短期流行度和瓦片大小特征,设计了基于时空老化模型的服务端瓦片缓存置换算法（server-side cache replacement algorithm based on spatiotemporal aging model for tiles,SSAT）,并利用谷歌全球底图瓦片和瓦片访问日志进行了仿真实验。结果表明,在不同缓存空间下,SSAT的缓存命中率均高于传统算法,缓存空间每增加1 MB,最多可以提高0.24%的请求命中率和0.23%的字节命中率;当缓存空间为500 MB时,SSAT能达到73%的请求命中率和76%的字节命中率,平均访问时长可缩短35%以上。SSAT能兼顾性能与资源消耗,具备高效性和扩展性。     

Structural and optical properties of the S-doped ZnO particles synthesized by hydrothermal method

Sulfur-doped ZnO particles have been synthesized by hydrothermal method. The structural and optical properties were studied systematically by XRD, scanning electron microscopy (SEM), and photoluminescence. SEM results show that the particle is hexagonal and the average size decreases with increasing sulfur doping, which means a retardant effect of sulfur on the growth of S-doped ZnO. XRD results show that the lattice parameters increase with more sulfur, which means an effective sulfur doping and increasing strain. Optical characterization also shows that the effective sulfur doping will enhance the green emission and suppress the near bandgap emissions.     

Evolution of surface morphology and photoluminescence characteristics of 1.3-μm In0.5Gao.5As/GaAs quantum dots grown by molecular beam epitaxy

Evolution of surface morphology and optical characteristics of 1.3-μm In0.5Gao.5As/GaAs quantum dots (QDs) grown by molecular beam epitaxy (MBE) are investigated by atomic force microscopy (AFM) and photoluminescence (PL). After deposition of 16 monolayers (ML) of In0.5Ga0.5As, QDs are formed and elongated along the [110] direction when using sub-ML depositions, while large size InGaAs QDs with better uniformity are formed when using ML or super-ML depositions. It is also found that the larger size QDs show enhanced PL efficiency without optical nonlinearity, which is in contrast to the elongated QDs.     

A direct suppression of green band emission of ZnO particles by adjusting the volume fraction of ethanol in reaction solutions

ZnO particles were successfully prepared by one step CTAB‐assisted hydrothermal method with different volume fraction of ethanol‐water mixture solution. The formed thorn‐ball like ZnO particles have an average size of 1 ∼ 2 μm in diameter. XRD result shows a hexagonal wurtzite structure and higher crystallinity. Room‐temperature photoluminescence shows a strong and dominated peak at ∼383 nm with a green emission at ∼510 nm. The intensity ratio between the UV and green emission increased from 1.31 to 7.53 when the volume fraction of ethanol was changed from 0% to 50%, which shows a direct suppression of structural defects just by adjusting the ethanol fraction in reaction solutions. The possible growth and luminescence mechanisms for thorn‐ball like ZnO particles are discussed.     

Antifreeze protein detection using Rhodamine B as photoluminescence label in porous silicon

A novel method is demonstrated to detect Antifreeze proteins (AFPs) based on photoluminescence (PL) using porous silicon (PS) coated with silver as a substrate. Ag/PS substrate is obtained through immersion of PS in silver nitrate (AgNO₃) solutions and is incubated with Rhodamine B (RB) as PL label. This substrate is easy to be fabricated and the pore size of PS is large enough for biological molecules to infiltrate, which is an ideal platform for biological molecule detection. Through functionalization used glutaraldehyde (GTA) and 4-(N-Maleimidomethyl) cyclohexane-1-carboxylicacid (Sulfo-SMCC) as cross-linkers separately, we test the role of the AFPs antibodies in selective capturing the AFPs antigen and explain the reason of the enhancement of PL intensity. The result shows a significant enhancement of the PL intensity of RB at around 590 nm due to the interaction of antibody–antigen competitive binding with AFPs. Therefore, the PL corresponding to RB was selected to detect the target AFPs and the PL intensity of RB proportional to the AFPs concentration. The detection limit was found to be 1.65 μg/ml for AFPs when GTA was used as cross-linker, and the detection limit was 16.5 ng/ml with Sulfo-SMCC as cross-linker.