Size-controllable carbon spheres doped Ni (II) for enhancing the catalytic oxidation of methanol

Ni(II)/CSs were prepared using a simple two-step hydrothermal method. The morphology and composition of the catalysts were studied with scanning electron microscope, transmission electron microscope, and X-ray diffraction. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy showed that the surface of the prepared carbon spheres was rich in hydroxyl groups, which was beneficial to remove CO intermediates, and therefore, improving the catalytic efficiency and the antipoisoning ability of the catalysts. The results of cyclic voltammetry and chronoamperometry showed that the electrocatalytic activity and stability of Ni(II)/CSs were higher than that of unloaded NiAc under alkaline environment. When the nickel content was 5 wt.%, the peak oxidation current density of methanol on Ni(II)/CSs electrocatalyst reached the maximum of 34.54 mA/cm², which was about 1.8 times that of unloaded NiAc. These results indicate that Ni(II)/CSs has potential applications in the electrocatalytic oxidation of methanol.     

AucorePtshell础纳米粒子对甲醇氧化的电催化性能研究

应用两步化学还原法制备不同厚度的AucorePtshell纳米粒子，经紫外可见光谱（UV-Vis）、透射电子显微镜（TEM）表征．该金纳米颗粒经化学还原包裹铂后平均粒径明显增大，调节金与铂的含量可获得不同包裹厚度的AucorePtshell纳米粒子．循环伏安法研究表明，粒径为70-80nm的AucorePtshell纳米粒子对甲醇的氧化具有较好的电催化活性，并且其电催化性能随着电位循环扫描次数的增加而增强．     

丁二烯阴离子聚合动力学及活性种的研究

本文对于n-BuLi/2G引发的丁二烯阴离子聚合动力学数据及产物微观结构进行了解析。建立了动力学模型,提出了聚合反应机理。求得了单量体、一络合体和二络合体的增长速度常数和诸活性种之间的平衡常数以及它们对形成乙烯基结构的贡献。     

血透患者微量元素营养状况初步探讨

对门诊维持性血透肾衰患者进行了膳食营养调查。结果表明：（1）在临床检查中发现,血透肾衰患者面黄肌瘦,面色苍白,浮肿,疲劳;体质虚弱,四肢无力;精神不振,具有明显的营养不良的临床表现。（2）在膳食调查中发现,每人每日营养素摄入量为蛋白质41．54mg,热量5288kJ,钙104mg、铁4．86mg和锌8．86mg、硒35μg、铜2．28mg、锰2．86mg、镁76．50mg、磷448mg、钾752mg和钠1385．4mg;视黄醇当量368μg、vitarmin B10.58mg、vitamin B20.39mg、vitarnin C51mg、vitaminPP12.60mg和vitaminE0.38mg。提示血透肾衰患者蛋白质－热量营养不良,K、Na过量,而Ca、Mg、P等宏量元素和Zn、Cu、Fe、Mn、Se等微量元素和RE、vitamin B1、vitamin B2、vitamin C均未达到RDA要求。原因是主食营养不平衡。因此,建议对血透肾衰患者进食主食营养平衡米（NBR）和制订平衡食谱,开展透析日营养治疗和病人家庭营养治疗。改善血透肾衰患者微量元素营养状况。     

微波消解-ICP-MS法测定药用明胶空心胶囊中微量重金属元素

采用微波消解技术,建立了一种电感耦合等离子体质谱法测定明胶空心胶囊中Cr,Co,Ni,Cu,Zn,As,Cd,Hg和Pb 9种微量重金属元素的方法。确定了微波消解仪和等离子体质谱仪的最佳操作参数,研究共存离子的干扰和消除方法,选择了各元素的测定同位素,以Ge,Rh和Tl为内标补偿基体效应,建立了样品测定方法。应用拟定的方法测定了不同生产厂家、不同批次的空心胶囊中微量重金属的含量。方法对试样中各元素测定的相对标准偏差为1.5%~14.1%,加标回收率在90.0%~102.0%。结果表明,方法简便、快速、灵敏,满足于空心胶囊中9种重金属元素的测定要求。     

Simultaneous determination of nine nucleosides and nucleobases in different Fritillaria species by HPLC‐diode array detector

A sensitive and reliable HPLC‐diode‐array detector method was developed for the first time to simultaneously determine nine nucleosides and nucleobases including uracil, cytidine, guanine, uridine, thymine, inosine, guanosine, thymidine and adenosine in 13 different Fritillaria species. The analysis was performed on a BaseLine C18 column with a gradient of acetonitrile in water at a flow rate of 0.8 mL/min. The diode‐array detector wavelength was set at 260 nm for the UV detection of nucleosides and nucleobases. Satisfactory separation of these compounds was obtained in less than 40 min. The optimized method provided good linear relation (r² >0.9995 for all the investigated analytes), satisfactory precision (RSD <1.51%) and good recovery (from 97.64 to 101.16%). The established method was successfully applied to simultaneous determination of nine nucleosides and nucleobases in 61 batches of samples from 13 Fritillaria species collected from different habitats in China, which could be helpful to control the quality of Fritillaria bulbs.     

LixNi0.5Co0.5O2的态密度计算及电化学性能研究

>为获得综合性能更好的锂离子二次电池正极材料, 分析了Co掺杂对Li_xNiO₂电化学性能的影响. 采用密度泛函DFT理论对Li_xNiO₂和Li_xNi_0.5Co_0.5O₂的平均放电电压和态密度进行了计算. 同时, 用共沉淀法制备了Li_xNiO₂和Li_xNi_0.5Co_0.5O₂锂离子二次电池正极材料, 并对其进行了XRD结构分析和恒流充放电测试. 实验和计算结果表明: 随锂离子嵌入正极(电池放电), 电池的电压逐渐降低, 材料的态密度峰向低能量方向移动; 与Li_xNiO₂相比, Li_xNi_0.5Co_0.5O₂的电压平台相对较高(当0.25≤x≤0.5), 而且在Li^＋嵌/脱时, Li_xNi_0.5Co_0.5O₂的结构变化相对较小; Co离子的掺入, 减小了NiO₆八面体的畸变度, 使材料的电化学稳定性得以提高. 在钴掺杂镍酸锂体系中, NiO₆和CoO₆具有相互的稳定作用.     

LiNi0.5Co0.5O2体系的结构稳定化作用和独立充放电机理

为了解释锂离子二次电池正极材料LiNi_0.5Co_0.5O₂具有的优良充放电循环性能和高比容量特征，采用基于密度泛函理论(DFT)的第一性原理计算方法对LiNi_0.5Co_0.5O₂和LiNiO₂的相关特性进行了研究。结果表明LiNi_0.5Co_0.5O₂的结构稳定性优于LiNiO₂的原因在于充放电过程中体系中Ni、Co离子交替存在的价电子构型t_2g⁶e_g⁰。依据LiNi_0.5Co_0.5O₂体系中Ni离子和Co离子相互独立的电极反应提出了适用于LiNi_xCo_1-xO₂(0≤x≤1)体系的独立充放电机理(0.2C、3.0～4.2 V vs Li⁺/Li)，并得到实验的证实。     

多级溶剂萃取-气相色谱法测定啤酒中的游离脂肪酸

啤酒中含量极低、极不稳定的游离脂肪酸是影响啤酒风味重要因素之一。本文采用溶剂萃取和气相色谱联用技术,对啤酒不良风味物质游离脂肪酸进行了检测。啤酒样品经3次萃取(有机溶剂萃取、碱液反萃取、有机溶剂萃取)后,通过甲醇-硫酸甲酯化处理,最后用正己烷萃取浓缩进行气相色谱(GC)分析。该方法中以辛酸、癸酸和月桂酸为代表的平均回收率分别为86.26%、92.19%和83.57%。辛酸、癸酸、月桂酸、棕榈酸在2.326~2326 mg/L,0.362~362 mg/L,0.250~250 mg/L,0.330~330 mg/L范围内线性良好,相关系数在0.9996~0.9999之间。