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991.
Wittig reaction under Phase Transfer conditions was performed in a flow reaction system. Different bases, aldehydes, phosphonium salts, and flow reaction parameters were investigated, in absence of a phase transfert catalyst. An improvement of the reaction outcome (yield and reaction time) was achieved through the immersion of the reactor into an ultrasound bath. 相似文献
992.
An oxidative peak in the cathodic scan is observed in the cyclic voltammetry of glucose at gold electrodes, its peak current density being proportional to glucose concentration in a wide potential range. The application of this phenomenon in blood glucose sensing has been hindered by the presence of inhibitors: the most problematic are chlorides due to their high concentration and difficult separation from glucose. In the present paper we propose a solution to this problem involving a three electrode, four step pulsed electrochemical detection technique. 相似文献
993.
Pescim GF Marrach G Vannuci-Silva M Souza LA Menegário AA 《Analytical and bioanalytical chemistry》2012,404(5):1581-1588
Saccharomyces cerevisiae immobilized in agarose gel is proposed as a binding agent for the diffusive gradients in thin films (DGT) technique for determination of Pb in river water and seawater. DGT samplers were assembled with the proposed binding agent (25-mm disk containing 20%, m/v, S. cerevisiae and 3.0%, m/v, agarose) and a diffusive layer of cellulose (3MM Chr chromatography paper of 25-mm diameter). The effects of some DGT parameters (e.g., immersion time, ionic strength, and pH) were evaluated. Elution of Pb from the binding agent was effectively done with 1.75 mol L(-1) HNO(3). The deployment curve (between 2 and 24 h) was characterized by a significant uptake of Pb (346 ng Pb h(-1)) and good linear regression (R(2) = 0.9757). The experimental results are in excellent agreement with the predicted theoretical curve for mass uptake. Consistent results were found for solutions with ionic strengths of 0.005 mol L(-1) or greater and within a pH range of 4.5-8.5. Interferences from Cu (20:1), Mn (20:1), Fe (20:1), Zn (20:1), Ca (250:1), and Mg (250:1) in Pb retention were negligible. Determination of Pb in spiked river water samples (from the Corumbataí and Piracicaba rivers) performed using the proposed device was in agreement with total dissolved Pb, whereas measurements in seawater suggest that of the various species of Pb present in the samples, only cationic Pb species are adsorbed by the agarose-yeast gel disks. The in situ concentration of Pb obtained at two different sites of the Rio Claro stream (Corumbataí basin) were 1.13 ± 0.01 and 1.34 ± 0.04 μg L(-1). For 72-h deployments, a detection limit of 0.75 μg L(-1) was calculated. The combination of inductively coupled plasma optical emission spectroscopy and in situ deployments of DGT samplers during the 72-h period makes possible the determination of labile Pb in river water. 相似文献
994.
I. Krastev Ts. Dobrovolska U. La?njevac S. Nineva 《Journal of Solid State Electrochemistry》2012,16(11):3449-3456
The investigations on the effect of the electrolysis conditions, including high speed electroplating, on the content, structure, morphology and some properties of electrodeposited In-Co alloys from citrate electrolytes are presented. It was shown that indium and cobalt could be successfully deposited from acid citrate electrolytes and deposition of alloys with indium content between 20 and 80 wt. % is possible. At high cobalt content, heterogeneous multiphase coatings with spatio-temporal structures are obtained. Spatio-temporal structures could be observed also during electrodeposition under intensive hydrodynamic flow and improved mass transport conditions at high current densities. The structures are obtained for the first time from silver- and cyanide-free non-alkaline stable electrolytes of a relatively simple composition. 相似文献
995.
Bruce Fontaine 《Advances in Mathematics》2012,229(5):2792-2817
Given a simple algebraic group G, a web is a directed trivalent graph with edges labelled by dominant minuscule weights. There is a natural surjection of webs onto the invariant space of tensor products of minuscule representations. Following the work of Westbury, we produce a set of webs for which form a basis for the invariant space via the geometric Satake correspondence. In fact, there is an upper unitriangular change of basis to the Satake basis. This set of webs agrees with previous work in the cases and generalizes the work of Westbury in the case . 相似文献
996.
Viet Duc La 《Journal of sound and vibration》2012,331(15):3429-3436
A passive dynamic vibration absorber (DVA) moving along a pendulum can cause the nonlinear Coriolis damping to reduce the pendulum swing. This paper proposes a simple semi-active on–off damping controller to improve the passive Coriolis DVA. The aim of the on–off damping control is to amplify the DVA resonance motion to increase the energy dissipated. Moreover, the paper finds the analytical solution of the harmonic vibration of semi-active controlled system. The accuracy of the analytical formulas and the superior performance of the semi-active DVA are verified by numerical simulations. 相似文献
997.
Dai Z Kawde AN Xiang Y La Belle JT Gerlach J Bhavanandan VP Joshi L Wang J 《Journal of the American Chemical Society》2006,128(31):10018-10019
Here we present the first report on nanoparticle-based biosensing of glycan markers of diseases. The protocol relies on the competition between a nanocrystal (CdS)-tagged sugar and the target sugar for the binding sites of surface-confined lectin and monitoring the extent of competition through highly sensitive electrochemical detection of the captured nanocrystal. This development is expected to allow decentralized detection of carbohydrate moieties and lectin-carbohydrate interactions to be performed more rapidly, sensitively, inexpensively, and reliably. 相似文献
998.
De La Durantaye L McCormick T Liu XY Wang S 《Dalton transactions (Cambridge, England : 2003)》2006,(48):5675-5682
The coordination chemistry of the group 12 metal ions with two 2-(2'-pyridyl)benzimidazolyl derivative ligands 1,3,5-tris[2-(2'-pyridyl)benzimidazolyl]benzene (tmb) and 2-(2'-pyridyl)benzimidazolylbenzene (mb) has been investigated. The crystal structures of two coordination compounds (HgCl(2))(2)(tmb) and [Zn(mb)(2)(H(2)O)][ClO(4)](2) have been determined by single-crystal X-ray diffraction analysis which established the chelate bonding mode by the group 12 metal ions to the tmb or mb ligand. The luminescent response of tmb and mb toward group 12 metal ions, Zn(II), Cd(II) and Hg(II) has been examined by fluorescent titration experiments which established that the three group 12 metal ions have distinct luminescent response toward the tmb or mb ligand. The addition of the Hg(II) ion resulted in fluorescence quenching. In contrast, the addition of Zn(II) or Cd(II) led to a red shift and dramatic intensity increase of the emission spectrum of the ligand. 相似文献
999.
Interaction of lithium cyclopentadienide with a suitable partially protected alpha-D-allofuranose triflate, 4, epimer at C3 of glucose, gives as a major product, besides the expected glucose-cyclopentadiene, 5, a glucose-disubstituted cyclopentadiene, 6. This unprecedented behaviour, which does not occur with alpha-D-glucofuranose and other sugars, is tentatively explained by a complexation of LiCp and the oxygen atoms of the isopropylidene function of one molecule of 4 and one of 5, giving a termolecular structure as the result of a template effect. The results of other experiments, such as the use of MgCp2 in place of LiCp or the complexation of oxygen atoms by lithium triflate, which changed the selectivity of the reaction largely in favour of the monosubstitution product 5, support this hypothesis. When lithium indenide is reacted with 4, glucose-monosubstituted and glucose-disubstituted indenes, 8 and 9, respectively, are formed, and 9 is obtained with almost total diastereoselectivity. This result can also be rationalised by a stereoselective complexation of lithium, as shown by separate experiments and by molecular mechanics calculations. Methyltricarbonyl molybdenum(II) complexes have been synthesised and characterised from glucose-monosubstituted 5 and glucose-disubstituted 6 cyclopentadienes. 相似文献
1000.
L. Batist M. Górska H. Grawe Z. Janas M. Kavatsyuk M. Karny R. Kirchner M. La Commara I. Mukha A. Plochocki E. Roeckl 《The European Physical Journal A - Hadrons and Nuclei》2010,43(1):45-53
Excited states of the 49107In nucleus were populated through the 78Se ( 32S , p2n) fusion-evaporation reaction at beam energy, E
lab = 125 MeV. The de-excitations were studied using in-beam g \gamma -ray spectroscopic techniques involving the Compton-suppressed clover detector array. The level scheme of 107In consisting of about seven bands is established up to spin ∼ 45/2ℏ with the addition of 25 new transitions. Spins and parities
of various levels have been assigned through the DCO and polarization measurements. The level structures observed in 107In have been interpreted in the framework of a microscopic theory based on the deformed Hartree-Fock (HF) and angular-momentum
projection techniques. Various bands are reproduced in band mixing calculations with the configurations involving high-W \Omega
p \pi
g
9/2 and n \nu
d
5/2 orbits, and low-W \Omega
p \pi
g
7/2 , n \nu
g
7/2 and n \nu
h
11/2 orbits. 相似文献