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181.
J. Ghazouani 《Thermochimica Acta》2005,432(1):10-19
Volumetric properties of several low acentric factor fluids (Ar, CH4, C2H6, Kr, N2, Ne, O2, Xe) as well as CO2 are modeled using the Bender equation of state. This equation is a linear function of 19 adjustable parameters, which are evaluated from properties data, using a linear numerical procedure. The validity of the EOS is tested by calculating the Joule-Thomson inversion curve. A simple model is in particular used to correlate the inversion properties predicted by the Bender equation, expressed in term of reduced pressure as a function of reduced temperatures ranging from 0.8 to 6. The simple correlation reproduces accurately the used data. We employ data on state behaviour ρ(P,T) of homogeneous fluid phases, vapour-liquid equilibrium, second virial coefficient and the coordinates of the critical point. 相似文献
182.
A range of new small bite-angle diphosphine complexes, [M(CO)4{X2PC(R1R2)PX2}] (M = Mo, W; X = Ph, Cy; R1 = H, Me, Et, Pr, allyl, R2 = Me, allyl), have been prepared via elaboration of the methylene backbones in [M(CO)4(X2PCH2PX2)] as a result of successive deprotonation and alkyl halide addition. When X = Ph it proved possible to replace both methylene protons but for X = Cy only one substitution proved possible. This is likely due to the electron-releasing nature of the cyclohexyl groups but may also be due to steric constraints. Attempts to prepare the bis(allyl) substituted complex [Mo(CO)4{Ph2PC(allyl)2PPh2}] were only moderately successful. The crystal structures of nine of these complexes are presented. 相似文献
183.
The synthesis and characterization of poly(4-vinyl,2′-carboxybenzophenone) ion exchange resin is described. This resin displays a remarkably high capacity for Cu2+. Control of pH permits selective adsorption and estimation of Fe3+. This ion-exchanger is quite stable to loading acid washing cycles. © 1995 John Wiley & Sons, Inc. 相似文献
184.
A very sensitive electroanalytical method was employed to determine bergenin in phosphate buffer with a pH of 6.0, bergenin was accumulated at a 4-(2-pyridylazo)-resorcinol (PAR) polymer film modified glassy carbon electrode (GCE) surface under the condition of open-circuit. In the following anodic sweep from −0.4 to 0.8 V, bergenin adsorbed at the PAR polymer film modified electrode surface, was oxidized and yielded a sensitive oxidation peak at 0.595 V. Due to its unique structure and extraordinary properties, the PAR polymer film shows higher accumulation efficiency toward bergenin compared with a bare GCE. Hence, the amount of bergenin at the PAR polymer film modified GCE surface increases significantly, and finally the oxidation peak current improves greatly. The experimental conditions, such as supporting electrolyte, pH value, accumulation time and scan rate, were optimized for the measurement of bergenin, and a sensitive electroanalytical method was proposed for bergenin determination. The oxidation peak current varies linearly with the concentration of bergenin over the range of 2.0 × 10−7 to 1.2 × 10−5 mol/L, and the detection limit is 2.0 × 10−8 mol/L after 3 min open-circuit accumulation. The relative standard deviation of the same electrode in 10 successive scans is 1.8% for 1.0 × 10−6 mol/L bergenin and 2.1% for interelectrodes, indicating excellent reproducibility. This new method was successfully demonstrated with bergenin tablets and diluted urine. 相似文献
185.
Ur?a?Opara?Kra?ovecEmail author Marko?Topi? Anneke?Georg Andreas?Georg Goran?Dra?i? 《Journal of Sol-Gel Science and Technology》2005,36(1):45-52
Nano-structured WO3-TiO2 layers were prepared by the sol-gel route. To obtain transparent, porous and crack free layers up to 0.8 μ m with a single dipping cycle a templating strategy was used. As a template three-dimensionally network based on organically modified silane was introduced to the WO3 and TiO2 sols. The WO3 layers were dip-coated onto the conductive glass substrate (TCO) and the TiO2 layers on the top of the WO3 layer. The morphology and the structure of the layers were determined by Scanning Electron Microscopy (SEM), High Resolution Transmission Electron Microscopy (HR-TEM), Energy Dispersive X-Ray Spectroscopy (EDXS), Auger and Infrared spectroscopy. SEM image of the WO3-TiO2 layer confirmed the nano-porosity of the layers and give the size of the particles of about 10 nm for TiO2 and 30 nm for WO3 layer. Further analysis indicated that the titanium sol penetrates the WO3 layer. Particles in the WO3 layer consist of a crystalline monoclinic WO3 core surrounded by a 5–10 nm amorphous phase consisting of WO3, TiO2 and SiO2. The WO3-TiO2 layers were used to assemble all solid state photoelectrochromic (PE) devices. Under 1 sun irradiation (1000 W/m2) the visible transmittance of the PE device changes from 62% to 1.6%. The colouring and bleaching processes last about 10 minutes. 相似文献
186.
《Electroanalysis》2004,16(11):949-954
The preparation and the electrochemical study of Disperse Blue 1‐chemically modified electrodes (DB1‐CME), as well as their efficiency for the electrocatalytic oxidation of NADH is described. The proposed mediator was immobilized by physical adsorption onto graphite electrodes. The electrochemical behavior of DB1‐CME was studied with cyclic voltammetry. The electrochemical redox reaction of DB1 was found to be reversible, revealing two well‐shaped pair of peaks with formal potentials 152 and ?42 mV, respectively, (vs. Ag/AgCl/3M KCl) at pH 6.5. The current Ip has a linear relationship with the scan rate up to 800 mV s?1, which is indicative for a fast electron transfer kinetics. The dissociation constants of the immobilized DB1 redox couple were calculated pK1=4 and pK2=5. The electrochemical rate constants of the immobilized DB1 were calculated k1°=18 s?1 and k2°=23 s?1 (Γ=2.36 nmol cm?2). The modified electrodes were mounted in a flow injection manifold, poised at +150 mV (vs. Ag/AgCl/3M KCl) and a catalytic current due to the oxidation of NADH was measured. The reproducibility was 1.4% RSD (n=11 for 30 μM NADH) The behavior of the sensor towards different reducing compounds was investigated. The sensor exhibited good operational and storage stability. 相似文献
187.
一般增长曲线模型参数阵的BLU估计 总被引:4,自引:0,他引:4
考虑一般增长曲线模型:Y=X1BX2+εE(Vec(ε))=0V(Vec(ε))=σ2VIn(V0)本文对任一可估函数KBL给出了它的BLU估计(最佳线性无偏估计),并得到了方差σ2的一个无偏估计. 相似文献
188.
189.
无约束修正Timoshenko梁的冲击问题 总被引:3,自引:0,他引:3
介绍了修正后的Timoshenko梁运动方程,并比较了修正Timoshenko梁与经
典Timoshenko梁的运动方程. 推导了考虑剪切变形引起的转动惯量的修正Timoshenko
梁的正交条件,推导了集中质量对无约束修正Timoshenko梁的正碰撞对梁所引起的瞬态冲
击响应公式,并用算例进行了分析,且与集中质量对经典的无约束Timoshenko梁的正碰撞
对梁所引起的冲击响应进行了比较,另外还用算例分析了梁的刚度的变化和冲击质量比对其
冲击响应产生的影响. 相似文献
190.