Solidification of LiCl–Li2O oxide reduction salt into sodalite by a spark plasma sintering

Journal of Radioanalytical and Nuclear Chemistry - The waste LiCl–Li2O oxide reduction salt was solidified and transformed into sodalite by the spark plasma sintering method. Compared with...     

Production of Ultrafine Iron Powder by Combining Electrolysis and High-Voltage Discharge

High Energy Chemistry - Optimal conditions for producing ultrafine iron powder by combining the processes of electrolysis and high-voltage discharge have been determined. It has been established...     

Continuous Porous Aromatic Framework Membranes with Modifiable Sites for Optimized Gas Separation

Continuous microporous membranes are widely studied for gas separation, due to their low energy premium and strong molecular specificity. Porous aromatic frameworks (PAFs) with their exceptional stability and structural flexibility are suited to a wide range of separations. Main-stream PAF-based membranes are usually prepared with polymeric matrices, but their discrete entities and boundary defects weaken their selectivity and permeability. The synthesis of continuous PAF membranes is still a major challenge because PAFs are insoluble. Herein, we successfully synthesized a continuous PAF membrane for gas separation. Both pore size and chemistry of the PAF membrane were modified by ion-exchange, resulting in good selectivity and permeance for the gas mixtures H₂/N₂ and CO₂/N₂. The membrane with Br^? as a counter ion in the framework exhibited a H₂/N₂ selectivity of 72.7 with a H₂ permeance of 51844 gas permeation units (GPU). When the counter ions were replaced by BF₄^?, the membrane showed a CO₂ permeance of 23058 GPU, and an optimized CO₂/N₂ selectivity of 60.0. Our results show that continuous PAF membranes with modifiable pores are promising for various gas separation situations.     

A preliminary study on soil radon anomaly and its formation mechanism in karst area of southwest China

Journal of Radioanalytical and Nuclear Chemistry - Soil radon anomaly is a common phenomenon in karst areas. In this paper, the geochemical behavior of radium (Ra) in the process of carbonate rock...     

纳米白藜芦醇脂质体的物理化学稳定性研究

纳米载药脂质体的物理化学稳定性,是其实际应用中的关键问题。文章采用薄膜旋转蒸发法-超声法制备了白藜芦醇纳米脂质体（RES-Lip）,采用透射电子显微镜观察其微观形貌,并考察RES-Lip的物理化学稳定性。通过电导法测定了RES-Lip的相变温度（Tm）,及其在凝聚过程的凝聚速率常数（Kco）和表观活化能（Eco）;采用动态透析-紫外分光光度法,研究了温度和pH对RES-Lip降解的影响。结果表明,RES-Lip为球形囊泡结构,粒径小于100 nm;RES-Lip的相变温度为64℃;凝聚速率常数Kco随体系温度升高而升高;表观活化能Eco为86.056 kJ/mol;RES-Lip的降解符合一级动力学模型,降解的表观活化能Ea为59.3157 kJ/mol,降解过程是吸热、自发、熵增过程。本实验制备得到的RES-Lip在4℃、pH=7.40的条件下储存,稳定性较好。     

On-surface synthesis of porous graphene nanoribbons containing nonplanar [14]annulene pores

The precise introduction of nonplanar pores in the backbone of graphene nanoribbon represents a great challenge. Here, we explore a synthetic strategy toward the preparation of nonplanar porous graphene nanoribbon from a predesigned dibromohexabenzotetracene monomer bearing four cove-edges. Successive thermal annealing steps of the monomers indicate that the dehalogenative aryl-aryl homocoupling yields a twisted polymer precursor on a gold surface and the subsequent cyclodehydrogenation leads to a defective porous graphene nanoribbon containing nonplanar [14]annulene pores and five-membered rings as characterized by scanning tunneling microscopy and noncontact atomic force microscopy. Although the C–C bonds producing [14]annulene pores are not achieved with high yield, our results provide new synthetic perspectives for the on-surface growth of nonplanar porous graphene nanoribbons.     

基于分子指纹对黄酮类化合物及其抗DPPH自由基活性的QSAR分析

应用定量构效关系（Quantitative structure activity relationship, QSAR）研究阐明黄酮类化合物（Flavonoid compounds, FCs）的子结构指纹（Substructure fingerprint）与1,1-二苯基-2-三硝基苯肼（1,1-Diphenyl-2-picrylhydrazyl, DPPH）自由基清除能力之间的关系,从而指导高效抗氧化物质的设计和发现。在PubMed数据库中收集77个具有明确抗氧化活性的黄酮类化合物,而在ChEMBL数据库中收集86个无抗DPPH活性的黄酮类化合物。这163个黄酮类化合物的子结构指纹由PubChem系统生成,然后通过卡方检验筛选出与黄酮类化合物的抗氧化活性显著相关的分子指纹,最后通过判别分析建立预测QSAR模型,并采用回代法和交叉验证法对已建立的模型进行准确性和稳健性的验证。结果表明,黄酮类化合物抗DPPH自由基活性与ESSSR环的计数、简单相邻原子的类型和简单的SMARTS模式等因素有关。此外,所建立的QSAR模型能较好地预测黄酮类化合物的DPPH自由基清除活性,可用于评价候选抗氧化剂的潜力。     

有机膨润土结构对吡虫啉吸附热力学和动力学的影响机理

为深入了解有机膨润土结构对农药吸附性能的影响机理,论文制备十六烷基三甲基氯化铵(HTMA)载量系列变化的有机膨润土,通过吸附热力学和动力学研究了新烟碱杀虫剂吡虫啉与改性有机膨润土的相互作用和影响农药分子在有机膨润土层间扩散的结构因素。结果显示,季铵盐改性削弱了膨润土片层与吡虫啉的静电结合,但是增强与吡虫啉的疏水相互作用。吡虫啉吸附动力学与有机膨润土层间结构密切相关,低载量(<0.8′CEC)的HTMA对膨润土层间距的影响很小,但是层间堆积密度的增加导致吡虫啉吸附速率常数急剧下降。HTMA载量的进一步增加导致其层间排列方式由单层平铺向双层平铺的转变,层间距急剧增加使得吡虫啉吸附速率常数略有增大。     

碳纤维微电极负载金纳米粒子用于绿茶中儿茶素的检测

本文开发了基于纳米金修饰的碳纤维超微电极(CFME)用于儿茶素的定量检测。通过使用柠檬酸三钠还原氯金酸制得纳米金粒子(AuNPs),采用恒电位电沉积法将纳米金修饰在CFME表面。在pH 2.00的Tris-HCl缓冲溶液中,采用差分脉冲法和循环伏安法考察了修饰前后电极对儿茶素的电催化性能。结果表明,纳米金修饰电极对儿茶素具有明显的电催化效果。在优化实验条件下,纳米金修饰的碳纤维超微电极(AuNPs/CFME)与儿茶素浓度在1.00×10^-3~10.0μmol/L范围内呈良好的线性关系,且AuNPs/CFME的电化学性能非常稳定,具有良好的重现性。该方法操作简单,准确性高,可用于对儿茶素进行定量检测。     

基于BiOCl-Fe2O3@TiO2介孔复合材料的光电化学合成氨性能研究

传统合成氨工艺存在能耗高、污染严重的问题. 因此, 高效、低能耗绿色合成氨工艺的开发迫在眉睫. 光电化学以H₂O和N₂为原料, 可以在太阳光驱动下, 在常温常压条件下实现氨的合成, 因而受到广泛重视. 但总的来说, 效率和产率都达不到实际要求. 新型高效催化剂及工艺的开发是提高合成氨产率及效率的关键. 非贵金属催化剂具备成本低、来源广泛、可操作性强的优势, 有利于光电化学合成氨的产业化. 本实验采用溶胶凝胶结合原位热裂解的方法制备了分散性好、结构均匀的BiOCl-Fe₂O₃@TiO₂复合材料, 对其物相、微观结构、表面状态、光学性能、电学性能等方面进行了系统表征, 并探究了该材料在常温常压下光电化学合成氨的催化活性. 结果表明, 同纯介孔TiO₂相比_, BiOCl-Fe₂O₃@TiO₂的吸收带隙变窄, 可见光吸收能力增强, 光生载流子的利用率增加, 光电合成氨的产率提升了7倍, 且BiOCl-Fe₂O₃@TiO₂显示了优异的化学稳定性. 本研究工作为绿色合成氨催化材料及工艺设计提供了新思路.