Xe~(26+)入射Au靶离子L壳层空穴的产生与退激辐射

基于两体碰撞过程的能量与角动量守恒,推导出Xe26+离子与Au原子碰撞过程,单离子的L壳层空穴产额与离子动能的理论关系.实验测定了动能2.4-3.6Me V的Xe26+离子入射Au靶,产生的Xe的L-X射线谱,获得了射线产额与离子入射动能的实验关系.结果表明,碰撞过程产生Xe L壳层空穴的同时,产生了一定数目的 M壳层空穴,导致L壳层空穴平均荧光产额显著变大,在实验能量范围,空穴产额的理论值与射线产额的实验值存在较好的一致性.     

大数据时代下的化学经验2.0：基于键能的大规模反应途径预测

报道了一个基于键能数据预测反应途径的可编程算法．运用该算法,成功预测了F₂+CH₃Cl气相反应的最优产物(CF₄)和对应的反应途径．提供了一个启示性的化学经验2.0 的例子,并可能开启大数据时代下的大规模反应途径预测的大门．     

MODELING HARVEST SCHEDULING IN MULTIFUNCTIONAL PLANNING OF FORESTS FOR LONGTERM WATER YIELD OPTIMIZATION

In this study, wood production and hydrologic functions of forests were accommodated within a planning procedure for separate working circles (areas dedicated to certain forest functions) that were delineated according to an Ecosystem‐Based Functional Planning approach. Mixed integer goal programming was used as the optimization technique. The timing and scheduling of a maintenance cutting (partial harvest) was the decision variable in the modeling effort, and an original formulation was developed as a multiobjective planning procedure. Four sample planning strategies were developed and model outputs were evaluated according to these strategies. Spatial characteristics of stands were considered, and used to prohibit the regeneration of adjacent stands during the same time period. Because of the positive relationship between qualified water production and standing timber volume in the forest, the model attempts to maximize qualified water production levels by increasing standing volume stocks in the forest through the delay of regeneration activities.     

Influence of Gd doping on the absolute quantum efficiency and lifetime of EuxGd1-x（TTA）3phens

Absolute quantum yield （Ф） is one of the most important parameters to evaluate the potential of novel materials. Lanthanide complexes EuxGd1-x（TTA）3phens are synthesized with the ratio of Gd3＋ dopant concentration ranging from 10% to 90% to improve the absolute quantum yield. EuxGd1-x（TTA）3phens possess similar infrared and ultraviolet spectra, showing that they have similar molecular structures. The absolute emission quantum yields of EuxGd1-x（TTA）3phens are determined using a fluoromax-4 spectrofluorometer equipped with an integrating sphere. The fluorescence lifetimes of the EuxGd1-x（TTA）3phens are measured in the same experiment. It was found that both absolute quantum yields and fluorescence lifetimes of EuxGd1-x（TTA）3phens are of quasi-periodic variation with the change of the Gd3. dopant concentrations. The absolute quantum efficiency and fluorescence lifetime vary with respect to the Gd content in an opposite fashion, indicating that the rate of energy absorption by the EuxGd1-x（TTA）3phens and the conversion to light energy is critical for the absolute quantum efficiency. The radiative rate constant Kr and non-radiative rate constant Knr are calculated. The dependence of Kr and Knr on the Gd3＋ dopant concentrations is very similar to that of absolute quantum efficiency. The radiation rate constant Kr and absolute quantum efficiency have a linear relationship.     

Kinetics and efficiency displayed by supported and suspended TiO2 catalysts applied to the disinfection of Escherichia coli

TiO₂-mediated photocatalysis is widely used in a variety of applications and products in the environmental and energy fields, including photoelectrochemical conversion, self-cleaning surfaces, and especially water purification systems. The dimensionality of the structure of a TiO₂ material can affect its properties, functions, and more specifically, its photocatalytic performance. In this work, the photocatalytic inactivation of Gram-negative Escherichia coli using three photocatalysts, differing in their structure and other characteristics, was studied in a batch reactor under UVA light. The aim was to establish the disinfection efficiency of solid TiO₂ compared with that of suspended catalysts, widely considered as reference cases for photocatalytic water disinfection. The bacterial inactivation profiles obtained showed that: (1) the photoinactivation was exclusively related to the quantity of photons retained per unit of treated volume, irrespective of the characteristics of the photocatalyst and the emitted light flux densities; (2) across the whole UV light range studied, each of the photocatalytic solids was able to achieve more than 2 log bacterial inactivation with less than 2 h UV irradiation; (3) none of the used catalysts achieved a total bacterial disinfection during the treatment time. For each of the catalysts the quantum yield has been assessed in terms of disinfection efficiency, the 2D material showed almost the same performance as those of suspended catalysts. This catalyst is promising for supported photocatalysis applications.     

中温热解焦油重馏分悬浮床加氢裂化的研究

以中温热解煤焦油为原料,对其性质进行了分析,其中,350℃重质馏分中胶质含量30.88%,沥青质含量37.27%,四氢呋喃不溶物3.36%,属于常规固定床加氢裂化难以直接处理的馏分。合成了一种Mo系超分散催化剂,采用FT-IR、XPS、XRD、SEM和TEM等对催化剂进行了表征,催化剂中含有Mo=O和Mo-S特征结构,活性金属的硫化率为84.34%,在体系中具有优良的分散性,在反应体系内原位分解为超分散MoS_2颗粒;在0.25 t/d连续装置上进行了热解重油悬浮床加氢裂化实验研究,考察了反应条件对产物分布情况和结焦率的影响,得出适宜的反应条件为19 MPa,440℃,催化剂的添加量为300 mg/kg;此条件下石脑油收率24.47%,柴油馏分收率49.71%,结焦率1.32%。     

氮掺杂碳点的制备及其对阿莫西林高灵敏检测

以天然物质石斛为原料,一步水热法合成高荧光量子产率的氮掺杂碳点(NCDs),通过透射电子显微镜(TEM)、X射线光电子能谱(XPS)、傅里叶变换红外光谱(FT-IR)、紫外-可见光吸收图谱(UV-Vis)及荧光光谱(PL)对合成的NCDs进行表征。 实验结果显示合成的NCDs发强烈的蓝色荧光,呈现为球形或准球形,均匀分散,尺寸范围在1~5 nm;其表面含有丰富的COOH、OH和NH₂等水溶性基团,最佳激发和发射波长分别为350和435 nm,且具有良好的发光稳定性。 通过测定,合成的NCDs的荧光量子产率高达29.19%。在pH=7.4的缓冲溶液中测定不同物质对NCDs的荧光影响,相同条件下发现只有阿莫西林能够对NCDs荧光进行明显猝灭,表明合成的NCDs可选择性的识别阿莫西林,通过NCDs的荧光强度变化构建一种可灵敏检测阿莫西林的传感器,检测线性范围为2.6~30 μmol/L,检出限为0.15 μmol/L。     

Synthesis of carbon dots with a tunable photoluminescence and their applications for the detection of acetone and hydrogen peroxide

Carbon dots(CDs) with multi-color emissive properties and a high photoluminescent quantum yield(PLQY) have attracted great attention recently due to their potential applications in chemical,environmental,biological and photo-electronic fields.Solvent-dependent effect in photoluminescence provides a facial and effective approach to tune the emission of CDs.In this study,green emissive nitrogen-doped carbon dots(N-CDs) are synthesized from p-hydroquinone and ethylenediamine through a simple hydrothermal method.The as-prepared N-CDs possess a robust excitation-independent green luminescence and a high PLQY of up to 15.9%.Further spectroscopic characterization indicates that the high PLQY is achieved by the balance of nitrogen doping states and the surface passivation extent in CDs.The N-CDs also exhibit solvent-dependent multi-color emissive property and distinct PLQY in different solvents(the maximum can reach up to 25.3%).Furthermore,the as-prepared N-CDs are applied as fluorescence probes to detect acetone and H2O2 in water.This method has exhibited a low detection limit of acetone(less than 0.1 %) and a quick and linear response to the H_2O_2 with the concentration from 0 to 120 μmol/L.This work broadens the knowledge of applying CDs as probes in the bio and chemical sensing fields.     

[100]LiF单晶在60 GPa以内冲击加载下的高压屈服强度特性

获取光学窗口自身的高压强度特性是开展材料高压高应变率冲击响应行为精密测量和数据反演的重要基础。利用平板撞击和双屈服面法,通过冲击-卸载、冲击-再加载原位粒子速度剖面精细测量和数据反演,获得了约60 GPa范围内[100]LiF屈服强度特性随冲击压力的变化规律。结果表明:在实验压力范围内,[100]LiF的屈服强度随加载压力的提高而显著提高,压力硬化效应显著;同时,LiF在冲击加载下的屈服强度高于磁驱准等熵加载结果,应变率硬化效应强于热软化效应。采用Huang-Asay模型确定了可描述冲击加载[100]LiF强度特性的本构模型参数,为LiF在强度、相变、层断裂等加窗测量实验中的深入应用和数据准确解读提供了重要支撑。