阳极溶出伏安法同时测定高纯金属锌及试剂中的痕量杂质Cd、Pb、Cu、Bi

阳极溶出伏安法测定高纯金属及高纯试剂中的痕量杂质,正日益得到广泛的应用。我们研究了以酸溶试样后,不用分离主体锌,即可在普通笔录式极谱仪上,用玻碳汞膜电极同时测定其中四种痕量杂质元素Cd、Pb、Cu、Bi的极谱行为和测定条件。实验结果表明:在大量基体Zn存在下,最佳支持电解质体系为:1MHCl～0.2 MNH_4Ac～5×10~(-4)MHgCl_2,只预电解5分钟,Bi、Pb及Cd、Cu的灵敏度分别为4×10~(-10)g/ml、6×10~(-10)g/ml及     

梗阻型肥厚性心肌病冠状动脉造影特点及其对经皮室间隔心肌化学消融的临床意义

目的评价冠状动脉造影的形态学特征对经皮室间隔心肌化学消融(PTSMA)术治疗肥厚型梗阻性心肌病(HOCM)的指导意义.方法选择32例药物疗效欠佳并行PTSMA手术的HOCM患者,研究其冠状动脉造影特点,并与30例年龄、性别相匹配的冠状动脉造影正常的患者(对照组)进行比较.根据定量冠状动脉造影(QCA)测定目标消融间隔支的直径,分为≤1.5mm(小间隔支组)和>1.5mm组(大间隔支组),比较两组PTSMA术前、术后心导管测量左心室流出道压差(LVOTG)的变化.结果冠状动脉造影显示HOCM组的左主干、左前降支、左回旋支及左间隔支内径均显著大于对照组(均P<0.05),HOCM组左前降支肌桥的发生率较对照组亦明显增加(P<0.05);23例消融成功,PTSMA术前、术后导管测量LVOTG分别为(85.8±31.1)、(37.25±31.9)mmHg(P<0.01),其中大间隔支组PTSMA成功率明显高于小间隔支组(P<0.05),大间隔支组LVOTG的下降程度明显大于小间隔支组(P<0.05),两组间无水乙醇用量差异无统计学意义(P>0.05).结论 HOCM患者的左前降支肌桥发生率增加,且左冠状动脉内径较粗大,尤其是左间隔支粗大;间隔支>1.5mm的HOCM患者是PTSMA手术成功的重要预测因素,这对PTSMA目标消融间隔支的选择具有重要指导意义.     

Conductivity and applications of Li-biphenyl-1,2-dimethoxyethane solution for lithium ion batteries

The total conductivity of Li-biphenyl-1,2-dimethoxyethane solution(Li_xBp(DME)_(9.65), Bp = biphenyl, DME = 1,2-dimethoxyethane, x = 0.25, 0.50, 1.00, 1.50, 2.00) is measured by impedance spectroscopy at a temperature range from 0℃ to 40℃. The Li_(1.50)Bp(DME)_(9.65) has the highest total conductivity 10.7 m S/cm. The conductivity obeys Arrhenius law with the activation energy(E_(a(x=0.50))= 0.014 eV, E_(a(x=1.00))= 0.046 eV). The ionic conductivity and electronic conductivity of Li_xBp(DME)_(9.65) solutions are investigated at 20℃ using the isothermal transient ionic current(ITIC) technique with an ion-blocking stainless steal electrode. The ionic conductivity and electronic conductivity of Li_(1.00)Bp(DME)_(9.65) are measured as 4.5 mS/cm and 6.6 mS/cm, respectively. The Li_(1.00)Bp(DME)_(9.65) solution is tested as an anode material of half liquid lithium ion battery due to the coexistence of electronic conductivity and ionic conductivity. The lithium iron phosphate(LFP) and Li_(1.5)Al_(0.5)Ti_(1.5)(PO_4)_3(LATP) are chosen to be the counter electrode and electrolyte, respectively. The assembled cell is cycled in the voltage range of 2.2 V-3.75 V at a current density of 50 mA/g. The potential of Li_(1.00)Bp(DME)_(9.65) solution is about 0.3 V vs. Li~+/Li, which indicates the solution has a strong reducibility. The Li_(1.00)Bp(DME)_(9.65) solution is also used to prelithiate the anode material with low first efficiency, such as hard carbon, soft carbon and silicon.     

Size effect of Si particles on the electrochemical performances of Si/C composite anodes

A series of Si/C composites were fabricated based on pitch and Si powders with particle sizes of 30, 100, 500, and3000 nm. The size effects of the Si particles in the Si/C composites were investigated for lithium-ion battery anodes. The nanoscale Si and Si/C composites exhibited good capacity retentions. Scanning electron microscopy showed that exterior and interior cracks emerging owing to volume expansion as well as parasitic reactions with the electrolyte could well explain the performance failure.