层状双金属氢氧化物及复合材料对放射性元素铀的吸附及机理研究

随着核工业的快速发展，大量放射性元素铀被排放到环境中，造成严重的环境污染并给人类健康带来重大危害.层状双金属氢氧化物（LDHs）因其具有比表面积大、离子交换能力强以及独特的纳米结构等优点，在铀酰离子的去除及环境水污染处理方面展现出巨大潜力.同时，将层状双金属氢氧化物进行改性可大大增加活性位点，进一步提高材料对放射性元素铀的吸附性能.详细介绍了层状双金属氢氧化物及复合材料的制备及改性方法，通过光谱分析技术阐述了层状双金属氢氧化物对环境中铀酰离子的吸附效果以及作用机理.最后，对层状双金属氢氧化物在治理水污染中的应用前景给出个人见解，以期为今后的环境治理工作的深入研究和实际应用提供参考依据.     

胶束增溶(增敏)络合体系的高效液相色谱研究 Ⅷ.七种重金属的离子色谱柱后衍生光度法

本文用单柱阳离子色谱法分离了铜、镍、锌、钻、锰、镉、铅等七种重金属离子,并首次提出用胶束增溶(增敏)络合物为柱后衍生手段。用5-Br-PADAP 为试剂,TritonX-100为增溶剂,建立了七种金属离子同时测定的离子色谱法。     

分散固相萃取-超高效液相色谱-串联质谱法测定奶粉中7种非选择性环氧化酶抑制药物

建立并优化了使用分散固相萃取-超高效液相色谱-串联质谱（dSPE-UPLC-MS/MS）检测奶粉中7种非选择性环氧化酶（COX）抑制药物残留的方法。样品用0.01 mol/L pH 2.5抗坏血酸溶液-乙腈-乙酸乙酯（2：5：5，v/v/v）溶液提取后，加入无水硫酸钠、十八烷基键合硅胶吸附剂（C₁₈-N）及NH₂-丙基乙二胺吸附剂（NH₂-PSA）组成的盐包进行净化。以Waters CORTECS UPLC C₁₈（100 mm×2.1 mm，1.6 μm）色谱柱分离，流动相为0.1%（体积分数）甲酸水溶液和0.1%（体积分数）甲酸乙腈，配合多反应监测（MRM）模式定性定量分析水杨酸、布洛芬、双氯芬酸钠、吲哚美辛、吡罗昔康、萘普生和保泰松7种成分。结果表明：7种化合物线性相关性良好，相关系数（r²）≥ 0.9957。高、中、低3个水平下，加标回收率为76.4%~89.8%。定量限为2~5 μg/kg。该方法前处理简单，回收率高，重现性好，可作为奶粉中7种非选择性COX抑制药物残留的有效检测方法。     

INVESTIGATION ON THE RELATIONSHIP BETWEEN INTRINSIC VISCOSITY AND MOLECULAR WEIGHT OF POLY (VINYL CHLORIDE-DIETHYL MALEATE)

A poly (vinyichloride-diethyl maleate) copolymer has been fractionated by repeated precipitation method. All fractions and the unfractionated sample have been characterized by viscometry, dynamic osmometry, Zimm static osmometry, light scattering and gel permeation chromatography. After correction for polydispersity, a [η]～M relationship for monodisperse polymer solutions has been obtained:[η]=1.99×10~(-3)M~(0.87) (ml/g, at 25℃, in cyclohcxanone)For the copolymer solution in THF, the second virial coefficient A_2 decreases as the molecular weight increases. The relationship isA_2=2 slope ((?)_n RT)~(-1/2).     

Experiment and Capillary Bundle Network Model of Micro Polymer Particles Propagation in Porous Media

In this paper, a microscopic visualization experiment is conducted to explore the heterogeneous flow pattern of micro polymer particles in micron pore. A capillary bundle network model for micro polymer particles in porous media is established. The migration and retention mechanism of polymer particles can be clearly observed in the experiment and simulated with this numerical model. The result demonstrates that the block of large particles is one of the main factors by which micro polymer particles increase the flow resistance. The simulation results are consistent with the experimental results.     

Metabolite differences between glutamate carboxypeptidase II gene knockout mice and their wild-type littermates after traumatic brain injury: a 7-tesla <Superscript>1</Superscript>H-MRS study

Background

Traumatic brain injury (TBI) is a complex condition and remains a prominent public and medical health issue in individuals of all ages. A rapid increase in extracellular glutamate occurs after TBI, leading to glutamate-induced excitotoxicity, which causes neuronal damage and further functional impairments. Although inhibition of glutamate carboxypeptidase II (GCP II) is considered a potential approach for reducing glutamate-induced excitotoxicity after TBI, further detailed evidence regarding its efficacy is required. Therefore, in this study, we examined the differences in the metabolite status between wild-type (WT) and GCP II gene-knockout (KO) mice after TBI using proton magnetic resonance spectroscopy (1H-MRS) and T2-weighted magnetic resonance (MR) imaging with a 7-tesla imaging system, and brain water-content analysis.

Results

Evaluation of glutamate and N-acetylaspartate concentrations revealed a decrease in both levels in the ipsilateral hippocampus at 24 h post-TBI; however, the reduction in glutamate and N-acetylaspartate levels was less marked in GCP II-KO mice than in WT mice (p?<?0.05). T2 MR data and brain water-content analysis demonstrated that the extent of cortical edema and brain swelling was less in KO than in WT mice after TBI (p?<?0.05).

Conclusion

Using two non-invasive methods, 1H-MRS and T2 MR imaging, as well as in vitro brain-water content measurements, we demonstrated that the mechanism underlying the neuroprotective effects of GCP II-KO against brain swelling in TBI involves changes in glutamate and N-acetylaspartate levels. This knowledge may contribute towards the development of therapeutic strategies for TBI.

     

Equilibrium, kinetic and thermodynamic studies on the adsorption of the toxins of Bacillus thuringiensis subsp. kurstaki by clay minerals

The persistence of Bacillus thuringiensis (Bt) toxins in soil is further enhanced through association with soil particles. Such persistence may improve the effectiveness of controlling target pests, but impose a hazard to non-target organisms in soil ecosystems. In this study, the equilibrium adsorption of the Bt toxin by four clay minerals (montmorillonite, kaolinite, goethite, and silicon dioxide) was investigated, and the kinetic and thermodynamic parameters were calculated. The results showed that Bt toxin could be adsorbed easily by minerals, and the adsorption was much easier at low temperature than at high temperature at the initial concentration varying from 0 to 1000 mg L⁻¹. The adsorption fitted well to both Langmuir and Freundlich isotherm models, but the Freundlich equation was more suitable. The pseudo-second-order (PSO) was the best application model to describe the adsorption kinetic. The adsorption process appeared to be controlled by chemical process, and the intra-particle diffusion was not the only rate-controlling step. The negative standard free energy () values of the adsorption indicated that the adsorption of the Bt toxin by the minerals was spontaneous, and the changes of the standard enthalpy () showed that the adsorption of the Bt toxin by montmorillonite was endothermic while the adsorption by the other three minerals was exothermic.     

钌镧氧化物涂层在NaCl 溶液中的电化学阻抗谱(EIS)研究

测量了钌镧氧化物涂层的电化学阻抗谱(EIS), 结合循环伏安(CV)及扫描电子显微镜形貌分析, 研究了钌镧氧化物涂层阳极在3.5% NaCl 溶液中电化学表面结构及电化学行为. 在非析氯反应区间, 该涂层EIS 数据的最佳拟合等效电路是R_s(R_ctQ_dl), 在析氯反应区间, 其等效电路为R_s(R_fQ_f)(R_ctWQ_dl). 高频段阻抗行为对应涂层的物理阻抗, 低频段对应涂层与溶液界面的电化学反应阻抗. 实验结果表明, 随着La 浓度增加, 氧化膜及双电层的伪电容增大, 且在La 含量30mol%时达到最大值, 与CV实验结果一致, 证明了加入La 能提高RuO₂涂层的电催化活性. 但在析氯反应区间, 涂层氧化膜的导电性在含La 大于30 mol%之后迅速下降, 在低频段产生Warburg 阻抗, 与其表面钝化和特性吸附现象有关,这是导致含La 70 mol%时电催化活性急剧下降的原因.     

钠分子高位2~1Ⅱ_g与C~1Ⅱ_u态之间的碰撞能量转移

通过双光子激发和探测后向受激辐射光谱的方法观察了钠分子高位单态2~1Π_g与C~1Π-x间的碰撞能量转移过程。理论上计算的C~1Π_x态的布居分布和由C~1Π_x→X~1∑_g~+跃迁产生的紫外受激辐射光谱,均与实验结果相符。还同时采用二台不同波长的染料激光器分别激发钠分子和钠原子,研究了不同激发态钠原子对钠分子高位激发态能量转移过程的影响。     

声频下驻波管中微粒的悬浮现象及其相位多普勒测量

本文在声频信号下发现驻波管底部的微小颗粒群在一定声场强度下会腾空而起，在管中形成稳定的悬浮层。通过相位多谱勒（PDA）测量发现，只有粒径在一定范围内的颗粒才能稳定悬浮在管中，且颗粒悬浮层中颗粒的粒径按一定的高度规律分布，这一结果在粉尘颗粒分离，分级中有广阔的应用前景。