Preparation and Properties of Nanocrystalline Nickel by Pulse Electrodeposition on Glassy Carbon

由于纳米晶体镍具有电催化甲醇的活性,本文采用双脉冲法在玻碳表面上电沉积制备了纳米晶体镍，并分析了脉冲条件对其晶粒尺寸的影响。电沉积的溶液组成为300 g·L-1 NiSO4·6H2O，45 g·L-1 NiCl2·6H2O，40 g·L-1 H3BO3，5 g·L-1 C7H5NO3S，0.05 g·L-1 C12H25NaO4S，最优的脉冲工艺参数是脉冲平均电流密度为100 mA·cm-2、脉冲占空比为30%,脉冲频率为100 Hz, pH为1.5、温度为55 oC。利用XRD、TEM、循环伏安以及电化学阻抗分析了纳米晶体镍的晶粒尺寸、结构及性能。制备的电沉积层致密均匀，为典型的面心立方结构，晶体镍的平均粒径在18 nm左右，玻碳材料表面上通过电沉积得到的纳米晶体镍在碱性环境下对甲醇具有良好的电催化活性。Nanocrystalline nickel exhibits electrocatalytic activity for methanol. In this work, nanocrystalline nickel coating has been obtained by using the double pulse method on glassy carbon materials surface. The influence of pulse conditions on the grain size of nanocrystalline nicke was studied. The concentrations and compositions of the plating bath were  300 g·L-1 NiSO4·6H2O，45 g·L-1 NiCl2·6H2O，40 g·L-1 H3BO3，5 g·L-1 C7H5NO3S，and 0.05 g·L-1 C12H25NaO4S. The optimal pulse process parameters including the average pulse current density of 100 mA·cm-2, pulse duty ratio of 30%, pulse frequency of 1000 Hz, pH of 1.5, and treatment temperature of 55 ℃ were determined. The grain size, surface morphology, structure and electrochemical properties of the prepared nanocrystalline nickel were investigated by XRD, TEM, cyclic voltammetry and electrochemical impedance spectroscop. Accordingly, the dense, smooth, and continuous uniform electrodeposition layer with the typical face-centered cubic structure was developed. The average size of the nanocrystalline nickel was about 18 nm. Cyclic voltammetric and electrochemical impedance spectroscopic results showed that the nanocrystalline nickel electrodeposited on the glassy carbon surface had good electrocatalytic activity for methanol in an alkaline environment.作者联系地址：燕山大学环境与化学工程学院，秦皇岛 066004Author's Address: College of Environmental and Chemical Engineering, Yanshan University, Qinhuangdao 066004, China通讯作者E-mail：[email protected]

Expert consensus on multimodal MRI sequence parameters and scanning protocols for studies of brain and cognitive development in school‑aged children

当代多模态MRI技术的迅速发展，为精准刻画儿童青少年脑发育规律与个体差异、揭示 脑发育异常疾病的神经机制，提供了重要影像研究工具，带来了儿童脑发育影像学这一脑科学前沿方 向。然而，面向学龄儿童（6~18 岁）的高质量多模态 MRI 脑影像序列参数设置与扫描采集极具挑战 性，严重阻碍了国内脑发育相关影像研究的开展与推广。为此，国内相关领域的多家权威机构和专家 团队，依托科技部科技创新2030&ldquo; 脑科学与类脑研究&rdquo;重大项目&ldquo;中国学龄儿童脑智队列&rdquo;计划，通过 调研全国 30余家机构 MRI设备现况，以及国际大型儿童脑发育队列研究序列参数的优缺点，共同制 订了《面向学龄儿童脑智发育研究的多模态MRI脑影像序列参数与扫描规范专家共识》，以期规范国 内不同规模、不同类型队列相关脑发育影像研究中的序列参数设计与扫描操作，提升儿童脑影像扫描成功率与影像质量，以及结果可比性与稳定性，推动我国儿童脑智发育基础与临床研究的整体进步。</p

Prediction of Energy Resolution in the JUNO Experiment

International audienceThis paper presents the energy resolution study in the JUNO experiment, incorporating the latest knowledge acquired during the detector construction phase. The determination of neutrino mass ordering in JUNO requires an exceptional energy resolution better than 3% at 1 MeV. To achieve this ambitious goal, significant efforts have been undertaken in the design and production of the key components of the JUNO detector. Various factors affecting the detection of inverse beta decay signals have an impact on the energy resolution, extending beyond the statistical fluctuations of the detected number of photons, such as the properties of liquid scintillator, performance of photomultiplier tubes, and the energy reconstruction algorithm. To account for these effects, a full JUNO simulation and reconstruction approach is employed. This enables the modeling of all relevant effects and the evaluation of associated inputs to accurately estimate the energy resolution. The study reveals an energy resolution of 2.95% at 1 MeV. Furthermore, the study assesses the contribution of major effects to the overall energy resolution budget. This analysis serves as a reference for interpreting future measurements of energy resolution during JUNO data taking. Moreover, it provides a guideline in comprehending the energy resolution characteristics of liquid scintillator-based detectors