Ali A. ENSAFI*
,
Hajar BAHRAMI
,
0Hassan KARIMI-MALEH
,
Shadpour MALLAKPOUR
催化学报
doi:10.1016/S1872-2067(11)60465-8
A carbon paste electrode with added multiwall carbon nanotubes chemically modified with N-(3,4-dihydroxyphenethyl)-3,5-dinitrobenzamide was used as the electrochemical sensor for the determination of trace amounts of isoprenaline. The modified electrode showed good electrocatalytic activity for the anodic oxidation of isoprenaline, which was due to a substantial decrease in the anodic overpo-tential. Under the optimum conditions, measurements using square wave voltammetry had a linear range in the range of 0.3 to 125.0μmol/L of isoprenaline and a detection limit of 0.1μmol/L. The diffusion coefficient and kinetic parameters were determined using electrochemical methods. The relative standard deviation for seven successive assays of 1.0 and 20.0μmol/L isoprenaline were 1.9% and 2.4%, respectively. This electrochemical sensor was successfully applied for the determination of isoprenaline in human urine and injection solution samples.
关键词:
isoprenaline
,
carbon nanotube
,
electrode
,
electrocatalytic effect
,
voltammetry
A Rajeshkannan
,
K S Pandey
,
S Shanmugam
,
R Narayanasamy
钢铁研究学报(英文版)
Cold upsetting experiments were carried out on sintered Fe08%C10%Si04%Cu steel preforms in order to evaluate their deformation characteristics. Powder preforms of 86% of theoretical density, with two different ratios of height to diameter, were prepared using a suitable die set assembly on a 10 MN capacity hydraulic testing machine. Sintering was carried out in an electric muffle furnace for 15 h at 1 150 ℃. Each sintered compact was subjected to incremental loading of 004 MN under dry friction condition till a crack appeared at the free surfaces. The experimental results were critically analysed, the stress as a function of strain and densification was obtained, then the work hardening behaviour was analyzed. It has been found that in the process of enhancing densification, strength and strain hardening is also induced during upsetting, but the work hardening behaviour is not homogenously enhanced against strain and densification.
关键词:
cold upsetting;stress;height strain;densification;work hardening behaviour
徐汝军
,
李恩
,
周杨
,
郭高凤
宇航材料工艺
doi:10.3969/j.issn.1007-2330.2010.05.021
讨论了TM0n0模圆柱腔法测量介质复介电常数的原理,提出了一种TM0n0模圆柱腔设计的改进方法,研制了测试夹具,通过与未改进腔体比较和对石英样品复介电常数的测量.结果证明,该腔体大量抑制了圆柱腔的干扰模式数量,减小了测试误差,提高了测试准确度.
关键词:
微波测量
,
复介电常数
,
圆柱腔
Shunsheng Chen Changping Yang Lingfang Xu Shaolong Tang
材料科学技术（英文）
Strontium doped perovskite-type Nd0:7Sr0:3MnO3 ceramics were synthesized completely by high-energy ball milling raw oxides of Nd2O3, SrCO3 and MnO2. The optimal ball milling time and mass ratio of milling balls to raw materials are 4 h and 10:1, respectively. The grain size of as-milled Nd0:7Sr0:3MnO3 ceramics ranges from 51 to 93 nm, and the fine particles contain two phases of crystalline phase and amorphous phase. For the Nd0:7Sr0:3MnO3 synthesized by ball milling and sequent heat treatment, a remarkable colossal electroresistance (CER) effect is observed and the CER ratio reaches 900% at Curie temperature TC when the load voltage increases from 0.1 to 0.8 V.
关键词:
High-energy ball milling
,
Perovskite structure
,
Colossal electroresistance (CER)
,
Microstructure defect
GUO Wenquan WANG Jingtang Laboratory of Rapidly Solidified Non-Equilibrium Alloys
,
Institute of Metal Research
,
Academia Sinica
,
Shenyang
,
China
金属学报(英文版)
Considering the availability and derivation of Roscoe's equation for absolute viscosity calcula- tion,the method to adopt λ_0 value,so-called λ_f,was proposed by experimentally deter- mining relational curve of the measured height,H,of metal melt vs logarithmic oscillation decrement,λ,extrapolating H into zero,if such corresponding λ value is taken.Experimental results show that the proposed method not only satisfies the availability of original equation but also eliminate the effects of:“end and slippage”,so as to improve the accuracy for liquid Cu and Sn examinations.
关键词:
liquid metal
,
null
,
null
,
null
张豫
,
谢聚军
,
陈旭荣
原子核物理评论
doi:10.11804/NuclPhysRev.33.04.409
轻标量介子性质研究是当今中高能核物理研究中的热点问题之一,特别是质量低于1 GeV的标量介子f0(980)的内部结构一直存在争议,至今未达成共识.基于前人的研究结果,运用有效拉氏量方法,对f0(980)粒子的光生过程γp÷pf0 (980)进行了更深入的理论研究.探讨了两种传播子形式下得矢量介子ρ和ω交换的贡献,第一种是选择雷吉传播子,第二种是选择普通费曼传播子.第二种形式的微分散射截面理论结果与现有实验数据符合比第一种形式的结果好.基于此,计算了两种形式的总截面,两种形式给出的理论结果相差很大.另外,给出了γp÷pf0(980)÷pπ+π-过程的π+π-不变质量分布的理论预言,发现π+π-不变质量分布对于f0(980)于K(K)的耦合常数(gf0K(K))有很强的依赖关系,不同的gf0KK给出明显不同的π+π-不变质量分布.将来相关实验数据可以验证这些理论预言,并对矢量介子传播子形式和耦合常数gf0K(K)做出限制,加深人们对f0(980)粒子的认识.
关键词:
光生过程
,
轻标量介子
,
费曼传播子
S.K.Sadrnezhaad
,
E.Ahmadi
,
M.Mozammel
材料科学技术（英文）
Kinetics of dissolution of silver present in precious metal scraps in HNO3 was studied in temperature range of 26~85℃. Dissolution rate of silver was much faster than that of copper at all temperatures. Effects of particle size, stirring speed, acid concentration and temperature on the rate of dissolving of silver were evaluated. Dissolution rate decreases with particle size and increases with temperature. Dissolving was accelerated with acid concentrations less than 10 mol/L. Concentrations greater than 10 mol/L resulted in slowing down of the dissolution rate. Shrinking core model with internal diffusion equation t/τ=1-3(1-x)2/3+2(1-x) could be used to explain the mechanism of the reaction. Silver extraction resulted in activation energies of 33.95 kJ/mol for Ag-Au0:04-Cu0:10 and 68.87 kJ/mol for Ag-Cu0:23 particles. Inter-diffusion of silver and nitrate ions through the porous region of the insoluble alloying layer was the main resistance to the dissolving process. Results were tangible for applications in recycling of the material from electronic silver-bearing scraps, dental alloys, jewelry, silverware and anodic slime precious metal recovery.
关键词:
Silver
,
null
,
null
,
null
,
null
,
null
郭文全
,
王景唐
金属学报
通过对Roscoe绝对粘度计算公式的适用条件和推导过程的研究,提出了由实验测量液态金属的深度H与振动对数衰减率λ的关系曲线,并将其外延到H→0时所对应的λ值,作为原λ_0的取值(记为λ_f)的方法,液态Cu和Sn的实验结果表明,所提出的方法不仅满足原公式的使用条件,而且消除了“端面和滑动”等影响,使计算准确。
关键词:
粘度
,
viscosity
,
Roscoe's equation
