pH影响真鲷仔、幼鱼蛋白酶活性的研究

真鲷仔、幼鱼蛋白酶活性的最适PH随生长发育而变化。仔鱼期蛋白酶比活力峰值和次峰值出现在PH6.0和5.0；幼鱼期胃蛋白酶最适PH在2.2以下，肠和肝胰脏蛋白酶最适PH在10.0以上。真鲷仔幼鱼蛋白酶活性的变化与消化系统的发育和功能完善有关；育苗过程中使用单一铒料导致仔幼鱼的不适应，是育苗中仔稚鱼期死亡率高的原因之一。福建省自然科学基

Three-dimensional Porous Cu_6Sn_5 Alloy Anodes for Lithium-ion Batteries

以三维多孔泡沫铜为基底,通过直接电沉积的方法制备锂离子电池Cu6Sn5合金负极材料.发现合金表面大量的微孔和“小岛”不仅增大电极的表面积,而且显著缓解充放电过程中的体积变化.测得三维多孔Cu6Sn5合金的初始放电(嵌锂)容量为620mAh·g-1,充电(脱锂)容量为560mAh·g-1,库仑效率达到90.3%,具有较好的循环性能.扫描电子显微镜(SEM)结果显示,在泡沫铜基底上制备的Cu6Sn5合金电极具有比通常的铜片基底更好的结构稳定性,经过50周充放电循环后无明显的脱落现象.Three-dimensional porous Cu6Sn5 alloy electrodes were prepared by electroplating using copper foam as current collector.The micro-holes and small islands on surface of the Cu6Sn5 alloy increased largely the surface area of the electrode,and improved significantly the ability of the electrode in buffering the volume change in process of charge/discharge when the Cu6Sn5 alloy was employed as anode in a lithium-ion battery.Galvonostatic charging/discharging results demonstrated that the initial discharge(lithiation)and charge(delithiation)specific capacities of the Cu6Sn5 alloy electrode were 620 mAh·g-1 and 560 mAh·g-1,respectively.It demonstrated that the Cu6Sn5 alloy electrode exhibited a large initial coulomb efficiency(90.3%)and good capacity retention.SEM(scanning electron microscope)results illustrated that the Cu6Sn5 alloy deposited on copper foam substrate was more stable than that on a conventional copper substrate,and displayed no obvious exfoliation after 50 charge/discharge cycles.国家重点基础研究发展规划项目(973)(2002CB211804)资

Preparation and Capacity Fading Mechanism of Tin Thin Film as Anode of Lithium-ion Battery

以电镀的方法在铜基底上沉积薄膜锡作为锂离子电池负极材料.运用X射线衍射、扫描电镜、电化学循环伏安、电化学充放电和交流阻抗等多种方法对其结构和性能进行表征和研究.结果表明所制备的薄膜锡电极主要为四方晶系结构,其初始放电(嵌锂)容量为709mAh?g-1,充电(脱锂)容量为561mAh?g-1.电化学循环伏安研究发现在嵌/脱锂过程中薄膜锡经历了多种相变过程.电化学阻抗谱结果说明,首次嵌锂过程中当电极电位达到1.2V在电极表面形成SEI膜,而当电极电位低于0.4V表面SEI膜出现破裂,归因于体积膨胀所致.SEM研究表明30次充放电循环后薄膜锡负极出现龟裂现象.Tin thin film coated on Cu substrate as anode of lithium-ion battery was prepared by electroplating. Its structure and properties were characterized and studied by X-ray diffration, scanning electron microscopy, cyclic voltammetry, charging/discharging test and AC impedence method. XRD patterns indicate that the tin thin film exhibits a structure of tetragonal crystal. The first discharge and charge capacities of the tin thin film electrode were determined to be 709 and 561 mAh?g-1, respectively. Cyclic voltammetric results illustrated that multi-phase changes occurred during the lithiation and delithiation. Electrochemical impedance spectros- copy (EIS) results indicated that SEI film was begun to form on the surface of tin thin film electrode at 1.2 V, and then break down below 0.4 V because of large volume expansion. SEM investigations revealed that the tin thin film electrode appeared serious cracks after 30 charging and discharging cycles.国家重点基础研究和发展规划(973项目)(No.2002CB211804)资助项目

Progress of Organic Chemistry(2011～2012)

本文综述了中国大陆地区有机化学研究人员2011至2012年两年内在合成方法学、有机合成化学、元素有机化学以及天然产物化学等领域获得的重要成果。文章中共引用参考文献355篇,其中110多篇手性金属配合物和有机小分子催化的不对称反应、金属催化的碳氢键活化等合成方法学论文和30余篇氟有机化学论文基本来源于德国《应用化学》(国际版)和《美国化学杂志》。本文汇集了中国有机化学家两年中合成的150多个具有生物活性和化学结构多样性的天然产物,其中不乏具有高度挑战性的复杂天然分子。在近两年中中国有机化学家从陆地和海洋的生物体内发现各种不同类型新天然产物90多个。This biennale report reviewed the major achievements of organic chemistry involved to synthetic methodologies,synthetic chemistry,element-organic chemistry,and natural product chemistry in Mainland of China.There were 355 references cited in this report.Among them,about 110 papers related to the synthetic methodologies as well as about 30 papers of organofluorine chemistry reported herein were collected solely from ACIE and JACS.The report presented the synthesis of more than 150 natural products with diverse chemical structures and bioactivities,including some complex molecules with high synthetic challenge as well as the isolation of more than 90 new natural products with various structural types from continental or /and marine creatures,which were reported by Chinese chemists in 2011 ~ 2012

Fabrication and Performance of Cu_6Sn_5 Alloy Anode Using Porous Cu as Current Collector

以氢气泡为动力学模板电沉积获得多孔铜,并通过热处理增强其结构稳定性.进一步将多孔铜作为基底通过电沉积制备Cu-Sn合金负极.Xrd结果给出其组成为Cu6Sn5合金,扫描电子显微镜(SEM)观察到Cu6Sn5合金电极为三维(3d)多孔结构.充放电结果指出,Cu6Sn5合金电极具有较好的充放电性能,其首次放电(嵌锂)和充电(脱锂)容量分别为735和571MAH·g-1,并且具有较好的容量保持率.运用电化学阻抗谱研究了Cu6Sn5合金电极在商业电解液中的界面特性.Porous Cu was fabricated by electrodeposition through a kinetic template of hydrogen bubbles.The product was subsequently annealed to increase its structural stability.The Cu-Sn alloy was then electrodeposited onto porous Cu which served as a current collector.X-ray diffraction (XRD) studies ascertained that the composition of the Cu-Sn alloy was Cu6Sn5 and scanning electron microscopy (SEM) investigations showed a three-dimensional (3D) porous structure of the electrode.The first charge/discharge capacities of the Cu6Sn5 alloy electrode were measured respectively at 735 and 571 mAh·g-1,and a good retention of the capacities has been determined.Interfacial properties of the Cu6Sn5 alloy electrode in a commercial electrolyte were also studied by electrochemical impedance spectroscopy (EIS).国家重点基础研究发展规划(973)项目(2009CB220102)资

Electrochemical Impedance Spectroscopy Study on Phase Transformation of Cu_6Sn_5 Alloy Anode

以粗糙铜箔为基底,采用一步电沉积法获得Cu-Sn合金,X射线衍射(Xrd)测试结果显示其主要为Cu6Sn5合金相.扫描电子显微镜(SEM)测试结果表明该合金表面由大量“小岛“组成,且每个“小岛“上存在大量纳米合金粒子.充放电测试结果表明,以该合金为锂离子电池负极,其初始放电(嵌锂)和充电(脱锂)容量分别为461和405MAH·g-1.电化学阻抗谱测试结果显示,Cu6Sn5合金电极在阴极极化过程中分别出现了代表固体电解质界面膜(SEI膜)阻抗、电荷传递阻抗和相变阻抗的圆弧,并详细分析了它们的变化规律.The Cu-Sn alloy electrode was prepared by a one-step electrodepositing method using rough Cu foil as the substrate,and was determined as the intermetallic composite of Cu6Sn5 using an X-ray diffraction(XRD) method.The electrode surface morphology was analyzed by scanning electron microscopy(SEM) which displayed "small islands" structure with many nano-particles on it.The first discharge and charge capacities were determined as 461 and 405 mAh·g-1,respectively.Electrochemical impedance spectra(EIS) indicated that there appeared three arcs in the Nyquist plots respectively representing the impedance of solid electrolyte interphase film,charge transfer and phase transformation in the first lithiation,and their evolutive principles were also investigated.国家重点基础研究和发展规划(973)(No.2009CB220102);国家自然科学基金(No.20773102)资助项

LiCoO_2正极材料电子和离子传输特性的电化学阻抗谱研究

运用电化学阻抗谱(EIS)研究了LiCoO2正极的电子和离子传输特性,及其在电解液中贮存和充放电过程中的变化规律.发现当LiCoO2正极在电解液中贮存达到9h时,在EIS的中频区域出现一个新的半圆,随着贮存时间进一步延长,该半圆不断增大.在充放电过程中,这一中频区域半圆随电极电位的变化发生可逆的增大和减小,其变化规律与LixCoO2电子电导率随电极电位的变化规律相一致.因此,这一新的EIS特征应归属于LiCoO2正极在贮存或锂离子嵌脱过程中LixCoO2电子电导率的变化.研究结果还发现,LiCoO2正极表面SEI膜阻抗在充放电过程中可逆地增大和减小,也可归因于充放电过程中LiCoO2正极活性材料电子电导率的变化.国家重点基础研究发展计划(批准号:2002CB211804)资助项

Structure and Properties of Three-dimensional Reticular Sn-Co Alloy Electrodes as Anode Material for Lithium Batteries

应用电沉积技术制备了三维网状结构的Sn-Co合金负极材料,采用XRD、SEM和电化学方法考察了该负极材料的结构和性能.XRD分析表明,该三维网状结构的Sn-Co合金镀层为六方固溶体结构.其电化学性能测试表明:三维网状结构Sn-Co合金微晶电极的性能稳定,其首次放电容量高达493.4mAh·g-1,首次库仑效率达80.03%,而平面结构Sn-Co合金电极的首次库仑效率为63.47%.经50周充放电循环后,三维网状结构Sn-Co合金电极的放电容量为329.6mAh·g-1,放电容量保持率为66.8%;SEM分析表明:三维网状Sn-Co合金电极表面是由大小不一、高低不同的“岛”紧密排列在一起;“岛”和多孔结构的存在,缓冲了锂嵌入时体积的膨胀,部分抑制了材料结构的变化,减缓了电极容量的衰减,改善了电极的循环性能.The three-dimensional reticular Sn-Co alloy deposits were prepared by electroplating.The structure and electrochemical performance of the electroplated three-dimensional reticular Sn-Co alloys have been investigated in detail.Experimental results show that the Sn-Co alloy film is of hexagonal solid solution,with Sn as the solvent,Co as the solute.Electrochemical tests show that the three-dimensional reticular Sn-Co alloy coating electrodes can deliver a discharge capacity of 493.4 mAh·g-1 in the first cycle.At the 50th cycle the charge was 329.6 mAh·g-1.The three-dimensional reticular structure in Sn-Co alloy electrode was beneficial in reducing the irreversible capacity of Sn-Co alloy electrode at initial charge-discharge,and in relaxing the volume expansion during cycling,which improved the cyclability of Sn-Co alloy electrode.They are also beneficial to diffusion of Li into /out of macroporous materials,and improve coulomb efficiency in charge-discharge cycle.国家重点基础研究和发展规划(973项目,2002CB211804)资助项

Electrochemical Impedance Spectroscopic Study of the First Delithiation of Spinel Lithium Manganese Oxide

研究了尖晶石锂锰氧化物电极首次脱锂过程中的电化学阻抗特征.通过选取适当的等效电路拟合实验所得的电化学阻抗谱数据,获得了首次脱锂过程中固体电解质相界面膜(SEI膜)的电阻、电容以及电荷传递电阻、双电层电容等随电极极化电位的变化规律.The first delithiation of the spinel LiMn2O4 electrode was studied using electrochemical impedance spectroscopy (EIS). Appropriate equivalent circuits were proposed to fit the experimental EIS data. Based on the fitting results, the variation of the capacitance and the resistance of SEI(solid electrolyte interphase) film, the resistance of charge transfer, and the capacitance of double layer along with the increase of polarization potential were quantitatively analyzed. The results demonstrated that the resistance and the thickness of the SEI film formed on the spinel LiMn2O4 electrode were both increased with the increase of polarization potential in the first delithiation of the spinel LiMn2O4 electrode; The charge transfer resistance decreases below 4.15 V and increases above 4.15 V, corresponding to the two-step reversible (de)intercalation of lithium between LiMn2O4 and λ-MnO2; The double layer capacitance was influenced by both the state of the spinel LiMn2O4 electrode(different polarization potential) and the two-step reversible (de)intercalation of lithium.国家重点基础研究发展规划项目(2002CB211804)资

LiCoO_2电极/电解液界面特性的电化学阻抗谱研究

运用电化学阻抗谱研究了LiCoO2电极在电解液中的贮存和首次脱锂过程.发现LiCoO2电极在电解液中,随浸泡时间延长其表面SEI膜不断增厚,归结为LiCoO2电极与电解液之间的自发反应导致生成一些高介电常数的有机碳酸锂化合物.研究结果指出LiCoO2电极首次脱锂过程中,SEI膜在3.8~3.95V电位区间发生可逆坍塌,对应其可逆溶解;由于过充反应,当电位大于4.2VSEI膜迅速增厚.研究结果同时表明,Li/LiCoO2电池体系的感抗来源于充放电过程中LiCoO2电极中存在LiCoO2/Li1?xCoO2局域浓差电池.发现锂离子在LiCoO2电极中的嵌脱过程可较好地用Langmuir嵌入等温式和Frumkin嵌入等温式描述,测得LiCoO2电极中锂离子嵌脱过程中电荷传递反应的对称因子α=0.5.国家重点基础研究发展计划资助项目(批准号:2002CB211804