锂离子电池正极材料LiFePO4／C的研究进展

为提高LiFePO4电化学性能,综述了现有的碳表面包覆工艺,主要有高温固相合成法,低温液相合成法,液相共沉法,水热合成法及微波合成法.指出LiFePO4今后应在合成方法、掺杂机理、混合掺杂以及掺杂物质量的配比上加以研究,从而提高其电化学性能.     

锂离子电池液态GaSn自修复负极材料的制备及其电化学性能

为解决目前锂离子电池负极材料固有的体积膨胀问题,使用室温下呈液态的镓锡(GaSn)合金作为锂离子电池负极材料,通过静电纺丝法将液态GaSn合金束缚在纳米纤维内部以及纳米纤维的网络状结构中间,并组装成锂离子电池,对其结构和性能进行表征与分析.结果表明:液态GaSn合金可均匀地分散在碳纳米纤维中,同时GaSn合金由于超声空...     

锂离子电池层状氧化锂锰的合成及掺杂改性研究进展

介绍了LiMnO2的结构，综述了锂离子电池层状氧化锂锰以及掺杂LiMnO2的制备方法、电化学性能等方面的研究现状，并指出，寻找稳定又方便的合成层状氧化锰锂的方法和进行氧化锂锰的掺杂将是其未来的主要研究方向。     

碳纳米纤维负极材料制备及其电化学性能

为了获得性能优异的碳纳米纤维负极材料并对材料的碳化工艺进行探讨,利用静电纺丝技术和高温碳化制备一维碳纳米纤维负极材料。对获得的碳纳米纤维的形貌、化学成分结构及电化学性能进行测试分析,得到优化的预氧化和碳化条件。结果表明:在预氧化条件为250℃、120 min,碳化条件为800℃、120 min条件下制得的碳纳米纤维具有较好的形貌特征及化学性能,平均直径为190 nm,此时碳结构更加有序,碳含量达到73.7%。通过组装锂离子电池测试电池充放电性能,得到在100 mA/g的电流密度下,放电比容量达到568.4 mAh/g,经过100圈循环后容量保持率达77.3%。     

复合锂离子电池隔膜的制备及其电化学性能

为获得性能较好的锂离子电池隔膜,首先制备了单层静电纺聚偏氟乙烯六氟丙烯（P（VDF-HFP））纳米纤维,然后利用静电喷雾技术将Al2O3和ZrO2颗粒分散液均匀喷洒在其表面,再接收一层静电纺P（VDF-HFP）纳米纤维,制备出具有3层结构的有机/无机复合锂离子电池隔膜。同时制备了单层静电纺P（VDF-HFP）纳米纤维膜作为对比膜。考察了复合膜和对比膜的表面形貌、透气性、吸液率和热稳定性等物理性能,以及室温离子电导率、电化学稳定性和电池的循环充放电性能等电化学性能。结果表明：该复合膜的Gurley值为0.117S/(100mL?cm²),热收缩率为2.25%,吸液率为420%;室温下离子电导率为2.31mS/cm,电化学稳定窗口为5.4V,所制备电池首次放电比容量为138.6mA?h/g;在中间层添加纳米颗粒后,复合膜的透气性下降而其他指标均获得提升,综合性能优于相同条件下制备的单层静电纺隔膜     

LiV2.99Co0.01O8正极材料电化学能性的研究

以LiOH·H2O,NH4VO3和Co2O3为原料,采用微波与传统烧结相结合的方法合成了锂离子电池正极材料LiV2.99Co001O8。XRD分析表明该化合物仍为层状结构。充放电循环实验表明所得样品的首次放电容量高达328mAh·g-1,30次循环后仍能保持在223mAh·g-1。     

石墨烯/硅负极材料的制备及其电化学性能分析

为有效解决硅基材料的体积效应和导电性弱等问题,可利用石墨烯和亚微米硅进行还原复合与机械混合,制备石墨烯/硅复合电池负极材料。基于此,文章列举了石墨烯/硅负极材料的制备实验流程,并分析了不同还原方式对石墨烯/硅电化学性能的影响,以供参考。     

酸掺杂聚苯胺电极材料的制备及其电化学性能研究

本研究以苯胺为单体,过硫酸铵为氧化剂,植酸为掺杂酸,与木质素磺酸盐进行化学聚合,通过原位化学氧化法合成了电子传导能力良好和电容性能优异的木质素磺酸盐/聚苯胺（LS/PANI）电极材料,采用场发射扫描电子显微镜（FESEM）、傅里叶变换红外光谱仪（FT-IR）和比表面积及孔径分析仪（BET）对LS/PANI电极材料进行分析表征;运用循环伏安、充放电、电化学阻抗等测试LS/PANI电极材料电化学性能。结果表明,LS/PANI电极材料具有良好的电容性能和较好的循环稳定性;在充放电0.5 A/g的电流密度下比电容可以达到509.3 F/g,在充放电电流密度为10 A/g时,循环5 000次后仍能保留63.23%的电容。     

溶胶-凝胶法制备ZnWO4负极材料及其电化学性能研究

采用柠檬酸溶胶-凝胶法制备了Zn WO4材料,考察了焙烧温度对制备过程的影响.利用TG/DSC分析了Zn WO4前驱体的分解过程;通过XRD和SEM研究了Zn WO4材料的晶体结构组成和形貌;选择恒电流充放电、循环伏安及交流阻抗测试了该材料的电化学性能.结果表明:Zn WO4材料在550℃下晶体结构完整,综合电化学性能较好,首次放电比容量为446.29 m Ah/g,循环20次可逆比容量为200.7 m Ah/g,比容量衰减相对较慢,充放电效率也较高,循环性能较好.     

Y2O3:Eu3+纳米纤维与纳米带的制备及其发光性能

以聚乙烯吡咯烷酮（PVP）、稀土硝酸盐为原料,分别以水和N,N二甲基甲酰胺（DMF）溶剂,通过静电纺丝与高温煅烧制备出两种不同形貌的一维结构纳米材料。通过热重分析（TG）、场发射扫描电镜（FE-SEM）、傅立叶红外光谱（FTIR）、X射线衍射仪（XRD）对材料的结构、形貌进行了表征,利用荧光光谱仪对样品的光致发光性能进行了评价。结果表明：以水为溶剂制备的Y2O3:Eu3+样品煅烧前后均为带状,并推测了纳米带的形成机理,而用DMF溶剂制备的样品煅烧前后则均为纤维状;800 °C煅烧后样品结晶良好且为立方相结构。此外,纳米纤维和纳米都显示出来良好的发光效果,而Y2O3:Eu3+纳米纤维的光致发光强度约为Y2O3:Eu3+纳米带的2倍。     

丹蒽醌对氧化脱胶苎麻纤维理化性能的调控

为解决苎麻氧化脱胶中纤维容易被过度氧化而性能受损的问题,在氧化脱胶液中添加了具有纤维素和半纤维素保护效果的试剂 1,8-二羟基蒽醌（丹蒽醌）,并通过调节1,8-二羟基蒽醌的用量实现了对苎麻纤维理化性能（强伸性能、聚合度、半纤维素含量、制成率等）的调控。结果表明,1,8-二羟基蒽醌用量越高,纤维中半纤维素含量、制成率越高;但纤维强伸性能随1,8-二羟基蒽醌含量先升高后降低;当1,8-二羟基蒽醌的用量为2 %时,脱胶的综合效果最佳,此时纤维的断裂功、聚合度、半纤维素含量、制成率比不使用1,8-二羟基蒽醌时分别提高了41.0%、2.0%、17.3%、7.0%;此外,使用1,8-二羟基蒽醌后,脱胶废水的COD值降低了40%,大幅度提高了氧化脱胶工艺的环保性。     

Biosynthesis of 1-Octen-3-ol and 10-Oxo-trans -8-decenoic Acid Using a Crude Homogenate of Agaricus bisporus: Reaction Scale Up

ABSTRACT: The enzymatic reaction that produces 1 -octen-3-ol and 10-oxo-trans-8-decenoic acid was successfully scaled up from a 1 -L to a 10-L bioreactor using a crude mushroom homogenate of Agaricus bisporus . For this non-Newtonian reaction broth, the agitation rate was considered the most important controlling factor for the scale up. An agitation rate of 600 rpm, for an aeration rate of 0.44 m³/m³/h, was found to be the minimum to maintain the yield constant for the 1-L reactor. Subsequently, the agitation rate for the 10-L reactor was determined using 2 different approaches: a constant power per volume of liquid and a constant volumetric mass transfer coefficient (k_La). The constant power per volume of liquid approach predicted an agitation rate of 364 rpm that resulted in being too low to maintain the same yield obtained with the 1-Lreactor. Measurement of the kLa for the 10-Lreactor, at 364 rpm and an aeration of 0.44 m³/m³/h, produced a value of 11.7/h, thus confirming that the reaction in the larger reactor was oxygen-deprived. Therefore, the use of constant volumetric mass transfer coefficient (kLa) strategy was used instead. k_La was experimentally determined at different agitation rates for the 10-L reactor. It was found that 750 rpm produced a k_La of 40.2/h. Confirmatory reactions were run in both reactors with the same batch of mushrooms, and the results were equivalent, thus indicating that was a good criterion for scaling up this process.     

Sequencing analysis of a 15·4 kb fragment of yeast chromosome XIV identifies the RPD3, PAS8 and KRE1 loci,and five new open reading frames

The DNA sequence of a 15·4 kb region covering the left arm of chromosome XIV from Saccharomyces cerevisiae was determined. This region contains eight open reading frames (ORFs) which code for proteins of more than 100 amino acids. Three ORFs correspond to the RPD3, PAS8 and KRE1 loci, described previously. Three ORFs show limited homology with known proteins: NO330 with the recessive suppressor of secretory defect SAC1, NO325 with YCR094W identified during chromosome III sequencing; whereas NO315 presents a motif conserved in the dnaJ family. Two ORFs (NO320 and NO325) show no homology to known proteins within the databases screened, but NO320 corresponds to a serine-threonine-rich protein. The sequence has been entered in the EMBL data library under Accession Number Z46259.     

Analysis of a 32·8 kb segment of yeast chromosome IV reveals 21 open reading frames,including TPS2, PPH3, RAD55, SED1, PDC2, AFR1, SSS1, SLU7 and a tRNA for arginine

We report the nucleotide sequence of a 32·8 kb DNA segment from the right arm of Saccharomyces cerevisiae chromosome IV. The sequence contains 20 open reading frames (ORFs) longer than 300 bp as well as the 240 bp gene coding for the essential SSS1 secretory protein. Nine ORFs previously totally or partially sequenced (TPS2, PPH3, RAD55, SED1, PDC2, AFR1, SSS1, SLU7 and D4478) are presented, as well as the transmembrane protein D4405, the leucine zipper containing D4495 and a new tRNA for arginine. D4456 and D4461 are separated by a single in-frame stop codon only. The other five ORFs show no particular features or significant homology. The sequence is recorded in EMBL database under Accession Number X82086.     

Pyridine‐2,6‐diamine‐functionalized Fe3O4 nanoparticles as a novel sorbent for determination of lead and cadmium ions in cosmetic samples

A novel sorbent based on pyridine‐2,6‐diamine‐functionalized Fe₃O₄ nanoparticles was developed and characterized by X‐ray powder diffraction (XRD), elemental analysis, IR spectroscopy and scanning electron microscopy (SEM). The application of the sorbent was investigated for pre‐concentration and determination of lead and cadmium ions in aqueous samples. Effects of various factors such as the sample pH, eluent parameters (type, concentration and volume) and time (adsorption and desorption) were appraised. The effects of several interfering ions on method recovery were also investigated. The limit of detection (LOD) was found to be 1.3 and 0.089 μg L^?1 for lead and cadmium ions, respectively. Recovery and precision (RSD%) of the method were above 97.9% and below 0.6%, respectively. Validation of the outlined method was performed by analysing several certified reference materials. This method was successfully used for determination of lead and cadmium ions in several cosmetic samples, which are usually contaminated by lead and cadmium ions.