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991.
Glassy carbon electrodes modified with (5-amino-1,10-phenanthroline)bis(bipyridine)ruthium(II) chloride hydrate, [(bpy)2Ru(5-phenNH2)]Cl2·H2O, are shown to oxidize hydrazine with excellent sensitivity. The presence of an amine group on the ruthenium complex facilitates electropolymerization onto the electrode surface. Using cyclic voltammetry, a large catalytic current is observed upon oxidation of hydrazine in phosphate buffer (pH 5.0), compared to the current obtained from the ruthenium-modified electrode with no hydrazine present. The sensitivity of cyclic voltammetry is sufficient for obtaining a linear calibration curve for hydrazine over the range of 10−5 to 10−2 M. Hydrodynamic amperometry was used to determine the working potential for flow injection analysis. The limit of detection for hydrazine was determined to be 8.5 μM using FIA. The thickness of these films was shown to increase linearly with the number of electropolymerization cycles, in the range of 1000-2500 nm for 5-20 cycles, respectively, using Rutherford backscattering spectrometry (RBS). RBS analysis also suggests that the film is multilayered with the outermost layers containing a high ruthenium concentration, followed by layers where the concentration of ruthenium decreases linearly and approaches zero at the electrode surface. 相似文献
992.
Hilary E. Kent Terence H. Lilley Peter J. Milburn Michael Bloemendal Gus Somsen 《Journal of solution chemistry》1985,14(2):101-115
Enthalpies of dilution of the N-acetyl amides of glycine, L-alanine, L-valine, L-leucine, and L-phenylalanine, dissolved in N,N-dimethylformamide (DMF) as a solvent have been measured at 25°C. The results obtained have been analyzed to give the enthalpic interaction (or virial) coefficients of the solutes and these are compared with information previously obtained in aqueous systems. There are marked differences in the interaction properties in the two solvents and, while the additivity approach of Savage and Wood is applicable to the solutes in water it is not suitable for representing the interactions in DMF. A correlation is presented between the enthalpic second virial coefficients in DMF and the propensity of side-chains to be in proximity in globular proteins. 相似文献
993.
The molecular structure of Ph3CSSC(S)SCPh3 · CS2 has been determined by X-ray structural analysis. The substance crystallizes in the triclinic crystal system [a = 884.9(2) pm, b = 1 039.5(2) pm, c = 2 064.6(3) pm, α = 75.86(1)°, β = 79.83(2)°, γ = 77.31(5)°, Z = 2, space group P1 ]. The CS3 group is planar; the S? S-bond (201.4 pm) forms an angle of 5.7° with the CS3 plane. The torsional angle CSSC equals 96.3°. (Ph3C)2CS4 was obtained by reaction of TosNSCl2 (Tos = p-MeC6H4SO2) with Ph3CSH in CS2 in the presence of triethylamine. The reaction mechanism is discussed. 相似文献
994.
Rh上乙醇的生成机理,目前主要有两类.一是Ichikawa等为代表提出的“CO解离—CH_x(x=2或3)—乙酰基—乙醇”机理;另一是蔡启瑞等的“CO缔合—甲酰基(金属氧卡宾)—卡宾—乙烯酮—乙酰基—乙醇”机理.本文用Shustorovich的键级守恒—Morse势(BOC-MP)法对其进行了研究 相似文献
995.
996.
In this work, low pressure glow discharge O2 plasma has been used to increase wettability in a LDPE film in order to improve adhesion properties and make it useful for technical applications. Surface energy values have been estimated using contact angle measurements for different exposure times and different test liquids. In addition, plasma-treated samples have been subjected to an aging process to determine the durability of the plasma treatment. Characterization of the surface changes due to the plasma treatment has been carried out by means of Fourier transformed infrared spectroscopy (FTIR) to determine the presence of polar species such as carbonyl, carboxyl and hydroxyl groups. In addition to this, atomic force microscopy (AFM) analysis has been used to evaluate changes in surface morphology and roughness. Furthermore, and considering the semicrystalline nature of the LDPE film, a calorimetric study using differential scanning calorimetry (DSC) has been carried out to determine changes in crystallinity and degradation temperatures induced by the plasma treatment. The results show that low pressure O2 plasma improves wettability in LDPE films and no significant changes can be observed at longer exposure times. Nevertheless, we can observe that short exposure times to low pressure O2 plasma promote the formation of some polar species on the exposed surface and longer exposure times cause slight abrasion on LDPE films as observed by the little increase in surface roughness. 相似文献
997.
Páez-Hernández ME Aguilar-Arteaga K Valiente M Ramírez-Silva MT Romero-Romo M Palomar-Pardavé M 《Analytical and bioanalytical chemistry》2004,380(4):690-697
The results presented in this work deal with the prime application of activated composite membranes (ACMs) for the transport of Hg(II) ions in a continuous extraction–re-extraction system using di-(2-ethylhexyl)dithiophosphoric acid (DTPA) as carrier. The effects of variables such as the pH, the nature of the acid and the concentration of the casting solutions on the transport of Hg(II) are also investigated. When the ACM was prepared with a 0.5 M DTPA solution and when the feed solution contained 2.5×10–4 M Hg(II) in 0.1 M HCl, the amount of mercury extracted was greater than 76%. The re-extracted mercury was subsequently recovered by means of a stripping phase comprising 0.3 M thiourea solution in 2 M H2SO4, yielding 54% of the initial amount of mercury after transport had taken place for 180 min. 相似文献
998.
999.
1000.