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51.
A new apparatus for large scale preparative isoelectric focusing in free solution is described. Its main characteristic is rapid fluid recirculation with but short residues times in the electric field. For the first time the recycling principle was also applied to preparative isotachophoresis, by incorporating into the system a computer controlled leader counterflow. The rapid recirculation permits application of unusually high electrical power for rapid resolution, as it suppresses fluid flow instabilities arising from electrohydrodynamic effects. 相似文献
52.
Monodisperse thermosensitive particles prepared by emulsifier-free emulsion polymerization with microwave irradiation 总被引:2,自引:0,他引:2
The emulsifier-free emulsion polymerization of styrene (St) and N-isopropylacrylamide (NIPAAm) was successfully carried out with microwave irradiation, and the monodisperse thermoresponsive
poly(styrene-co-N-isopropylacrylamide) (poly(St-co-NIPAAm)) particles with diameters in the range 100–130 nm were prepared. The morphology, size and size distribution of the
poly(St-co-NIPAAm) particles were characterized by transmission electron microscopy, scanning electron microscopy (SEM) and photon correlation
spectroscopy (PCS), respectively. The results showed that poly(St-co-NIPAAm) particles had spherical morphology, and the poly(St-co-NIPAAm) particles prepared by emulsifier-free emulsion polymerization with microwave irradiation were smaller, more uniform
than those obtained with conventional heating. The hydrodynamic diameters of poly(St-co-NIPAAm) particles were decreased as the temperature increased from 25 °C to 40 °C, and poly(St-co-NIPAAm) particles collapsed remarkably at 32 °C, which is the lower critical solution temperature of the poly(N-isopropylacrylamide). The morphology of the assembled poly(St-co–NIPAAm) particles was observed by SEM, it was found that monodisperse poly(St-co-NIPAAm) particles could assemble to form the two-dimensional order structures. 相似文献
53.
Kabir-ud-DinEmail author S.?M.?Shakeel?Iqubal Zaheer?Khan 《Colloid and polymer science》2005,284(3):276-283
Kinetics of the redox reaction between colloidal MnO2 and glycolic acid have been studied spectrophotometrically by monitoring the decay in the absorbance of colloidal MnO2 in absence and presence of surfactants. Anionic sodium dodecyl sulfate has no effect, non-ionic Triton X-100 catalyzed the reaction and experiments were not possible in presence of cationic cetyltrimethylammonium bromide due to the precipitation of MnO2.The reaction followed the same type of kinetic behavior, i.e., fractional-, first- and fractional-order dependencies, respectively, in [glycolic acid], [MnO2] and [H+ ] in both the media. Effects of gum arabic and manganese(II) have also been studied and discussed. Mechanisms in accordance with the experimental data are proposed for the reaction. 相似文献
54.
Jun?ZhangEmail author Pei-Hong?Deng Yong-Lan?Feng Yun-Fei?Kuang Jin-Jun?Yang 《Mikrochimica acta》2004,147(4):279-282
A carbon black microelectrode modified by -MnO2 has been prepared. The electrocatalytical oxidation of ascorbic acid (AA) at this microelectrode was investigated. The 2nd-order linear scan voltammograms of AA are recorded from –0.5 to 0.5V (vs. SCE). The relationship between the oxidation peak current of AA and its concentration in the range of 1.0×10–64.0×10–3molL–1 is linear. The detection limit (3) was found to be 6.0×10–7molL–1. Also, the determination of AA in samples is evaluated, and the results are satisfactory. 相似文献
55.
Shariff?E.?KabirEmail author M.?Arzu?Miah M.?Abdur?Rahim Sonia?Sultana G.?M.?Golzar?Hossain Ebbe?Nordlander Edward?Rosenberg 《Journal of Cluster Science》2005,16(1):93-110
Treatment of Ru3(CO)12 with dpphSe2 (dpph = 1,6-bis(diphenylphosphino)hexane) in refluxing toluene in the presence of Me3NO afforded two new compounds, Ru3(CO)7(-CO)(3-Se)(-dpph) (1) and Ru3(CO)7(3-Se)2(-dpph) (2). A similar reaction of Ru3(CO)12 with dpppeSe2 (dpppe = 1,5-bis(diphenylphosphino)pentane) gave exclusively Ru3(CO)7(3-Se)2(-dpppe) (3). Treatment of Ru3(CO)12 with dpphS2 and dpppeS2 at 110°C in the presence of Me3NO afforded Ru3(CO)7(3-S)2(-dpph) (4) and Ru3(CO)7(3-S)2(-dpppe) (5), respectively. Reactions of Fe3(CO)12 with dpphSe2 and dpppeSe2, under identical conditions, afforded Fe3(CO)7(3-Se)2(-dpph) (6) and Fe3(CO)7(3-Se)2(-dpppe) (7), respectively. Compounds 1–7 were characterized spectroscopically and the molecular structures of compounds 1–4 were determined by single crystal X-ray crystallography. The core of 1 contains an equilateral triangle of ruthenium atoms with one capping selenium, one bridging dpph, one doubly bridging carbonyl and seven terminal carbonyl ligands. Complexes 2–4 have a square-pyramidal structure with two metal and two chalcogenide atoms alternating in the basal plane and the third metal atom at the apex of the pyramid, and belong to the family of well-known nido clusters with seven skeletal electron pairs. 相似文献
56.
ZHANG Xingwen HU Lijiang HUANG Yudong SUN Dezhi & SUN Yi . Department of Applied Chemistry Harbin Institute of Technology HUANG Yudong Harbin China . Department of Environmental Engineering Harbin Institute of Technology Harbin China . Department of Experimental Mechanics Harbin Institute of Technology Harbin China 《中国科学B辑(英文版)》2004,47(5):388-395
Silsesquioxanes (SSO) or polyhedral oligomericsilsesquioxanes (POSS) are generally prepared frommolecular precursors using the hydrolytic condensa-tion of trialkoxysilane, RSi(OR')3. They are organic/inorganic hybrid nanostructural blocks with theircomplete general formula Tn(T = RSiO1.5, n = 1,2, …), and the incomplete generic formula is Tn-(OH)x(OR')y[x, y = 0, 1, 2, …, T= RSiO1.5 ?(x+y)/2n][1,2].Each VSSO, possessing a certain structural formulaand molecular weight, may h… 相似文献
57.
M.?Prasad S.?P.?MoulikEmail author A. Al.?Wardian S.?Moore A.?van?Bommel R.?PalepuEmail author 《Colloid and polymer science》2005,283(8):887-897
The clouding points (CP) of the nonionic surfactants p-tert-octyl phenyl polyoxyethylene ether (Triton X 100), Brij-56 and Brij-97, and the water soluble polymer polyvinylmethylether (PVME) have been measured in the presence of the ionic surfactants alkyl (C10, C12, C14 and C16) triphenyl phosphonium bromides (ATPBs). The threshold additive concentrations required for efficient CP enhancement of the systems that were studied have been determined. Considering CP as the threshold state of phase separation, the energetics of the process at different additive concentrations has been evaluated. The spontaneity of free energy of the clouding process (G
c
0
) at the transition concentrations followed the order PVME > TX 100 Bj 56 > Bj 97. The clouding process has been found to be energetically endothermic with fairly large enthalpy and entropy changes that nicely compensate each other. The compensation temperature has been evaluated and compared with different types of the clouding agents.This revised version was published online in January 2005 with corrections to the names of the authors. 相似文献
58.
Determination of Dopamine in the Presence of Ascorbic Acid Using a Poly(Amidosulfonic Acid) Modified Glassy Carbon Electrode 总被引:3,自引:0,他引:3
Yuzhong?ZhangEmail author Guiying?Jin Zhousheng?Yang Hong?Zhao 《Mikrochimica acta》2004,147(4):225-230
A glassy carbon electrode (GCE) was modified with electropolymerized films of amidosulfonic acid in pH 7.0 phosphate buffer solution (PBS) by cyclic voltammetry (CV). The modified electrode showed an excellent electrocatalytical effect on the oxidation of dopamine (DA). In pH 7.0 PBS, the anodic peak current increased linearly with the concentration of DA in the range of 5.0×10–7 1.0×10–4moldm–3, with a correlation coefficient of 0.9932, and a detection limit (S/N=3) of 1.0× 10–7moldm–3. The relative standard deviation of 10 successive scans was 2.5% for 1.0×10–6moldm–3 DA. The interference of ascorbic acid (AA) with the determination of DA could be eliminated because of the very distinct attracting interaction between DA cations and the negatively poly(amidosulfonic acid) film in pH 7.0 PBS. The proposed method exhibited good recovery and reproducibility. 相似文献
59.
Protein microarrays: new tools for pharmaceutical development 总被引:2,自引:0,他引:2
Kumble KD 《Analytical and bioanalytical chemistry》2003,377(5):812-819
60.
Ashish Surya?Prakash?Singh Ashok?Kumar?Singh Bharat?SinghEmail author 《Transition Metal Chemistry》2005,30(5):610-615
Kinetics and mechanism of the Os(VIII) catalysed oxidation of crotonic acid (CA) by KBrO3 in alkaline medium have been investigated. Zero order dependence in [KBrO3] was observed, while first order with respect to CA in its lower concentration range tends to zero order at its higher concentration range. The order in [Os(VIII)] was found to be unity and a positive effect of [OH−] was observed. Variation of the ionic strength (μ) and dielectric constant of the medium and addition of Hg(OAc)2 (used as Br− scavenger) had an insignificant effect on the rate of reaction. Thermodynamic parameters have also been calculated and reported. A suitable mechanism consistent with the observed kinetic results has been suggested and the related rate law deduced. 相似文献