ANiN(A=Li,Na,Mg,Ca)的结构、热力学、弹性和电子性质的第一性原理研究

三元过渡金属氮化物ANiN(A=Li,Na,Mg,Ca)是潜在的可充放电池的电极材料.物理性质,比如热稳定性、电子能隙以及弹性稳定性等,对于这些材料的电池应用都是非常重要的.本文使用第一原理方法,对比研究了 ANiN这些材料的结构、动力学、弹性和电子结构性质.对状态方程和声子谱的计算被用来确定体系的稳定结构.对最稳定结...     

太阳能溴化锂吸收式制冷循环的改进

由于单效溴化锂吸收制冷循环受太阳能热源温度较低的限制,需要采用适当的辅助手段.本文对增压辅助型太阳能溴冷机循环流程提出了在冷凝器前加装隔离阀的改进方案,该方案可降低发生压力,以充分利用低温热源,并可有效回收压缩功.通过计算分析了改进循环的热力系数COP与热源温度和循环溶液质量分数差的关系.给出了在不同的热源温度下对应的最佳发生压力的调整范围.     

以四硝基铝酞菁为荧光探针测定葡萄糖的荧光分析新方法

建立以四硝基铝酞菁为荧光探针测定葡萄糖的荧光分析新方法。方法基于四硝基铝酞菁苯环上的硝基与葡萄糖发生还原反应,形成铝酞菁的氨基化产物;氨基化铝酞菁具有红区激发和发射的特性,在强酸性介质中可发射较强荧光;体系的荧光强度和葡萄糖的含量呈良好的线性关系,并具有较好的准确性和稳定性。方法用于测定发酵样品中的还原糖,结果满意。     

荧光猝灭法研究山豆根碱与人血清白蛋白间的相互作用

利用荧光光谱法研究了中药有效成分山豆根碱与人血清白蛋白(HSA)间的非共价结合特性。在37℃和47℃两个作用温度下,山豆根碱与HSA间的结合常数K分别为1.5671×103L.mol-1和2.4923×103L.mol-1,结合位点数n分别为0.8309和0.8630,表明温度升高有利于两者的结合。计算了热力学参数,表明该药物与蛋白的相互作用是一个熵增加和吉布斯自由能降低的自发过程,并由此推断山豆根碱与HSA之间的作用力是以疏水相互作用为主,为研究山豆根碱的药理作用和生物学效应,以及山豆根碱对蛋白质构像的影响等提供了重要信息。     

芯片毛细管电泳荧光检测器灵敏度的研究

本文采用倒置荧光显微镜,以汞灯为激发光源,自行设计组装了芯片毛细管电泳荧光检测系统。以荧光素异硫氰酸酯(FITC)为检测对象,对双通道门控光子计数器、CH151型光子计数探测器、电荷耦合器件(CCD)三种荧光检测器的灵敏度进行了比较研究。根据芯片毛细管电泳图谱分析,FITC在双通道门控光子计数器、CH151型光子计数探测器、CCD三种检测器中的检出限(S/N=3)分别为7.0×10-10mol/L,1.2×10-9mol/L,3.2×10-8mol/L。进一步采用CH151型光子计数探测器和CCD两种较常用检测器,对FITC和荧光素、曙红和荧光素两组荧光试剂的分离及检测进行了研究。结果表明,使用CH151型光子计数探测器作为检测器,灵敏度高,基线稳定,信噪比高。     

溴取代紫外光度法同时测定痕量磺胺嘧啶和磺胺二甲嘧啶

提出了同时测定痕量磺胺嘧啶(SD)和磺胺二甲嘧啶(SM2)的溴取代紫外光度分析法, 实验结果表明: 在6×10-5 mol/L Br2, 2.5×10-3 mol/L KI溶液和体积分数40%乙醇溶液中, 测定SD和SM2的线性范围分别为: 0～2.25 mg/L, 和0～1.125 mg/L, 摩尔吸光系数(L·moL-1·cm-1)分别为: 在水中9.66×104和8.16×104, 在乙醇水溶液中1.25×105, 1.99×105. 用此法对猪肉中SD和SM2进行测定, 猪肉中SD和SM2的质量分数分别为7.53、7.35 mg/kg, 回收率在91.4%～104.4%, SD和SM2的相对标准偏差分别为0.5%、1.5%.     

High-performance all-solid-state electrolyte for sodium batteries enabled by the interaction between the anion in salt and Na3SbS4

All-solid-state sodium batteries with poly(ethylene oxide) (PEO)-based electrolytes have shown great promise for large-scale energy storage applications. However, the reported PEO-based electrolytes still suffer from a low Na⁺ transference number and poor ionic conductivity, which mainly result from the simultaneous migration of Na⁺ and anions, the high crystallinity of PEO, and the low concentration of free Na⁺. Here, we report a high-performance PEO-based all-solid-state electrolyte for sodium batteries by introducing Na₃SbS₄ to interact with the TFSI⁻ anion in the salt and decrease the crystallinity of PEO. The optimal PEO/NaTFSI/Na₃SbS₄ electrolyte exhibits a remarkably enhanced Na⁺ transference number (0.49) and a high ionic conductivity of 1.33 × 10⁻⁴ S cm⁻¹ at 45 °C. Moreover, we found that the electrolyte can largely alleviate Na⁺ depletion near the electrode surface in symmetric cells and, thus, contributes to stable and dendrite-free Na plating/stripping for 500 h. Furthermore, all-solid-state Na batteries with a 3,4,9,10-perylenetetracarboxylic dianhydride cathode exhibit a high capacity retention of 84% after 200 cycles and superior rate performance (up to 10C). Our work develops an effective way to realize a high-performance all-solid-state electrolyte for sodium batteries.

A high-performance all-solid-state PEO/NaTFSI/Na₃SbS₄ electrolyte for sodium batteries is realized owing to the electrostatic interaction between TFSI⁻ in the salt and Na₃SbS₄, which immobilizes TFSI⁻ anions and promotes the dissociation of NaTFSI.     

低浓度含铅细颗粒物暴露大鼠体内生物转运研究

食品接触性塑料制品、可再生资源、汽车尾气中含有低浓度铅.铅等重金属体内蓄积严重影响机体健康,但机体长期暴露于铅环境的代谢依然未知.以低剂量含铅细颗粒物暴露为场景,探讨其在大鼠体内的生物转运及体内分布.通过比较每日吸入染毒(7.05±0.83)μg/m3及经口染毒0.42μg/d,连续染毒28 d.结果显示含铅细颗粒物入...     

An Edge Server Placement Method Based on Reinforcement Learning

In mobile edge computing systems, the edge server placement problem is mainly tackled as a multi-objective optimization problem and solved with mixed integer programming, heuristic or meta-heuristic algorithms, etc. These methods, however, have profound defect implications such as poor scalability, local optimal solutions, and parameter tuning difficulties. To overcome these defects, we propose a novel edge server placement algorithm based on deep q-network and reinforcement learning, dubbed DQN-ESPA, which can achieve optimal placements without relying on previous placement experience. In DQN-ESPA, the edge server placement problem is modeled as a Markov decision process, which is formalized with the state space, action space and reward function, and it is subsequently solved using a reinforcement learning algorithm. Experimental results using real datasets from Shanghai Telecom show that DQN-ESPA outperforms state-of-the-art algorithms such as simulated annealing placement algorithm (SAPA), Top-K placement algorithm (TKPA), K-Means placement algorithm (KMPA), and random placement algorithm (RPA). In particular, with a comprehensive consideration of access delay and workload balance, DQN-ESPA achieves up to 13.40% and 15.54% better placement performance for 100 and 300 edge servers respectively.     

掺杂铕和铽的卤硼酸盐荧光体的制备及光谱特征

采用高温固相法在空气中合成了一系列掺杂稀土离子的卤硼酸盐荧光体, 研究了其发光性质和基质组成对稀土离子共掺杂的荧光体发光性质的影响. 研究结果表明, 在Eu3+和Tb3+共掺杂的体系中存在电子转移, 因此出现了Eu3+, Eu2+和 Tb3+共存于同一基质共同发射的现象. Ce3+对Eu2+和Tb3+具有敏化作用, 可增强其发射强度. 基质的组成对稀土离子的发射峰位和发射强度有明显影响.