Synthesis and luminescence characteristics of DHLA-capped PbSe quantum dots with biocompatibility

In this work, we report a facile aqueous route to prepare PbSe QDs with strong photoluminescent and near-infrared (NIR) emission using dihydrolipoic acid (DHLA) as the capping ligands. It was found that the synthesis parameters including the molar ratio of DHLA/Pb, the pH value and the reaction time have considerable influence on photoluminescent intensity (PL) of the PbSe QDs. The as-synthesized DHLA-capped PbSe QDs were characterized by high-resolution transmission electron microscopy (HRTEM), energy-dispersive analysis of X-ray (EDX) and X-ray diffraction (XRD), the results indicated that the QDs were about 8.0 ± 0.2 nm in size and had good monodisperse and a rock salt crystalline structure. Also, there was DHLA on the surface of QDs, which was confirmed by Fourier transform infrared (FT-IR) spectrometry. The PbSe QDs exhibited optimal PL intensity when Pb:Se:DHLA = 1:0.6:1 in weak alkaline aqueous. The as-synthesized QDs kept highly PL intensities when stored in the dark in normal air environment during the period of 60 days. In addition, the biocompatibility of these QDs was measured by hemolytic test, which indicated that DHLA-stabilized QDs are biocompatible. It is important for QDs as biomarkers in biological detection and diagnosis.     

氰酸酯/环氧树脂的固化反应历程

采用傅里叶红外光谱仪研究了4种不同比例的氰酸酯(CE)/环氧树脂(EP)混合体系在一系列固化温度下固化后的产物组成,结果证实了6步反应的存在。当EP含量高时,体系生成物主要是口恶唑烷酮和部分异氰酸脲,而三嗪环很不显著;EP含量低时,首先形成三嗪环,然后三嗪环与环氧生成口恶唑烷酮或异氰酸脲。反应温度较低时(≤160℃),CE首先生成三聚体,再同环氧反应生成口恶唑啉、口恶唑烷酮以及异氰酸脲;在较高温度下固化时(160℃～180℃),主要进行的是三聚氰酸酯重排生成异氰酸脲的反应以及异氰酸脲同环氧官能团生成口恶唑烷酮的反应。生成物组成的差异是影响固化物宏观性能,如耐热性的根本原因。     

基于寻址信息的城市公共空间静态导向标识系统

经济全球化、城市化进程的加快,使城市空间规模日益庞大、结构日趋复杂,城市外来流动人口也越来越多."寻路难"、标识系统的"不和谐"已成为各城市普遍存在的问题,且与城市规模有着较强的"正相关"联系,严重影响了人们的工作和生活.目前,关于城市的门牌、路名牌、公交站牌等导向标识的研究甚少,因理论上缺乏系统指导,导致设计上理念陈旧、滞后,在建设中则突出表现为各自为政、固步自封,导向功能效用已大大落后于实际需要.在大量调查分析的基础上,依据符号学、传播学理论,从传达寻址信息基本功能的视角,对我国城市环境中各类基础导向标识进行整合,提出基于传播寻址信息的新型城市公共空间静态导向标识系统的设计框架,促进其系统化、信息化、人性化,提升其易读性,从而提高城市空间环境寻路效率,改善空间环境品质.这对改进现有基础导向设施,充分发挥其使用效率都有着重要的理论意义和实用价值.     

Tensor-Based User Trajectory Mining

The rapid expansion of GPS-embedded devices has showed the emerging new look of location-based services, enabling such offerings as travel guide services and location-based social networks. One consequence is the accumulation of a rich supply of GPS trajectories, indicating individuals’ historical position. Based on these data, we aim to mine the hot route by using a collaborative tensor calculation method. We present an efficient trajectory data processing model for mining the hot route. In this paper, we rst model the individual’s trajectory log, extract sources and destinations, use map matching to get the corresponding road segments, and nally apply the source-destination-road segments tensor in order to compute the recommended hot route. To prove the validity and efficiency of the method, we conduct a collaborative route recommendation system, and the experimental result indicated that the solution can recommend a route with considerable accuracy.     

燃煤电厂烟气污染物超低排放技术路线的选择

在深入研究燃煤电厂烟尘、SO₂、NO_x等控制技术特点与适用条件的基础上,综合国内大量煤电机组超低排放的成功案例,提出了燃煤电厂超低排放技术路线选择应遵循“因煤制宜,因炉制宜,因地制宜,统筹协同,兼顾发展”的基本原则,辨识出不同煤质、不同炉型、不同机组规模、不同污染控制要求等条件下的最佳可行技术,给出目前应用较多的超低排放典型技术路线,可指导燃煤电厂对超低排放技术路线的选择。     

约束钢梁在不同温度路径下的性能及各参数的影响

为了探索约束钢梁的高温性能及不同温度路径和参数的影响,本文采用大型有限元程序ANSYS对四种不同温度路径和四个不同参数下约束钢梁的性能反应进行分析研究.计算时充分考虑了高温引起的材料非线性和几何非线性,其中钢材的力学和物理性能指标随温度升高的变化系数按照欧洲规范(EUROCODE3)取用.本文首先对两端固定约束钢梁在温度连续升高时的性能反应进行了分析,并将分析结果与已有研究成果进行对比,验证了本文分析方法的正确性.在此基础上,又对升温-降温、升温-恒温-降温、升温-降温-升温等不同温度路径下约束钢梁的性能进行分析,研究了不同温度路径对钢梁高温性能的影响.最后探索了降温速率、历史最高温度、降温最低温度以及升降温循环次数等参数对约束钢梁性能反应的影响.     

半精纺工艺及其应用现状

为更好地应用半精纺工艺开发出适应市场需求的纺织产品,详细介绍了半精纺工艺的特点和发展现状,以及常用的半精纺工艺流程和设备.归纳出半精纺生产中在原料选用和工艺设计上的技术要点及产品开发现状.总结了目前半精纺产品开发中存在的掉毛起球、色差和色粒等质量和设备方面的问题及解决方法.针对半精纺工艺的应用情况,指出要多采用现代化的加工技术,打破传统专业限制,树立大纺织的观念,生产符合轻量化、休闲化、功能化的半精纺产品.     

河南油田配电网接地选线装置应用述评

回顾了河南油田配电网小电流接地选线装置多年来的应用情况,在总结应用经验的基础上,研制了分别具有消弧或TV消谐功能的两种小电流接地选线、定位装置,最后介绍了两种装置的应用效果和三点应用建议。     

Oxidative desulfurization of model and real oil samples using Mo supported on hierarchical alumina-silica: Process optimization by Box-Behnken experimental design

The catalytic performance of Mo supported on hierarchical alumina-silica (Si/Al=15) with Mo loadings of 3, 6 and 15 wt% was investigated for the oxidative desulfurization (ODS) of model and real oil samples. Hierarchical alumina-silica (hAl-Si) was synthesized by economical and ecofriendly silicate-1 seed-induced route using cetyltrimethylammonium bromide (CTAB) as mesoporogen. The effect of CTAB on the structure of catalyst was studied by characterization techniques. The results revealed that 6%Mo/hAl-Si had the highest sulfur removal compared to the other catalyst loadings. The effect of operating parameters was evaluated using Box-Behnken experimental design. The optimal desulfurization conditions with the 6%Mo/hAl-Si catalyst were determined at oxidation temperature of 67℃, oxidation time of 42 min, H₂O₂/S molar ratio of 8 and catalyst dosage of 0.008 g·ml^-1 for achieving a conversion of 95%. Under optimal conditions, different sulfur-containing compounds with initial concentration of 1000 ppm, Dibenzothiophene (DBT), Benzothiophene (BT) and Thiophen (Th), showed the catalytic oxidation reactivity in the order of DBT > BT > Th. According to the regeneration experiments, the 6%Mo/hAl-Si catalyst was reused 4 times with a little reduction in the performance. Also, the total sulfur content of gasoline and diesel after ODS process reached 156.6 and 4592.2 ppm, respectively.     

东通道工程二十里广联线路走向方案研究

在综合考虑铁路技术要求、经济因素等基础上,结合大连市保税区规划,研究了改刘大线方案和钻大窑湾高速公路方案两个方案,采用统计、类比和优缺点评价等方法进行经济技术比较,提出了改刘大线方案为推荐方案。