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991.
In the present work dynamic moiré-like fringe patterns, produced by photorefraction with low spatial frequencies, applied for profile determination of small objects is proposed. Basically, a Fourier transform profilometry technique is developed for an automated profile determination. This means, as far as we know, a new experimental procedure that exploits the real time holographic two wave mixing in Bi12TiO20 crystal sample. Besides, the mainly advantages of this procedure are, comparatively to the classical fringe projection method using the Michelson interferometer, best fringe pattern contrast, less speckle noise, absence of noises produced by spurious reflections and, the most significant, a pure sinusoidal shape obtained by dynamic holographic moiré-like process using photorefraction. 相似文献
992.
The fourth virial coefficient of asymmetric nonadditive binary mixtures of hard disks is computed with a standard Monte Carlo method. Wide ranges of size ratio (0.05 ≤ q ≤ 0.95) and nonadditivity (-0.5 ≤ Δ ≤ 0.5) are covered. A comparison is made between the numerical results and those that follow from some theoretical developments. The possible use of these data in the derivation of new equations of state for these mixtures is illustrated by considering a rescaled virial expansion truncated to fourth order. The numerical results obtained using this equation of state are compared with Monte Carlo simulation data in the case of a size ratio q = 0.7 and two nonadditivities Δ = ±0.2. 相似文献
993.
Viacheslav I. Tsirelnikov Boris V. Lokshin Prof. Dr. Petr Melnikov Valter A. Nascimento 《无机化学与普通化学杂志》2012,638(14):2335-2339
The dependence of the gallium trichloride saturated and unsaturated vapor pressures on temperature was studied by the static method using a quartz membrane zero‐manometer and taking into account the volume of its working chamber and substance mass. Conclusions about the presence of a distinguishable amount of trimeric molecules along with dimeric and momomeric molecules in the vapor were drawn on the basis of the obtained data. The following rough thermodynamic characteristics of a gaseous trimer of gallium trichloride were calculated: ΔfH° (Ga3Cl9, gas, 298 K) = –1466 kJ · mol–1. S°(Ga3Cl9, gas, 298 K) = 654 J · mol–1 · K–1. These data were used to elucidate the composition of the gaseous phase at a total pressure of 1 atm in the temperature range of 400–750 K. The suggested existence of trimeric molecules was not contradicted by vibrational spectroscopic analysis of gallium trichloride saturated vapor. 相似文献
994.
Olga Bienemann Ann‐Kathrin Froin Ines dos Santos Vieira Ramona Wortmann Alexander Hoffmann Prof. Dr. Sonja Herres‐Pawlis 《无机化学与普通化学杂志》2012,638(11):1683-1690
This contribution reports the synthesis of the novel tetradentate bisguanidine ligand 2′,2′‐[ethane‐1, 2‐diylbis(methylazanediyl)]bis(ethane‐2, 1‐diyl)bis(1, 1, 3, 3‐tetramethylguanidine) ( L1 , TMG2dmtrien), which combines two weak amine and two strong guanidine donor functions. Two new copper(II) complexes were isolated and structurally characterized as complexes [Cu(TMG2dmtrien)][Br]2 · 3MeCN ( C1 [Br]2 · 3MeCN) and [Cu(TMG2dmtrien)][Cl]2 · 3MeCN ( C2 [Cl]2 · 3MeCN). The cations C1 and C2 [Cu(TMG2dmtrien)]2+ show a square‐planar coordination environment and are chiral with both enantiomers being observed in the unit cell. We investigated the application of L1 in copper‐mediated styrene ATRP. L1 shows with CuBr and PEBr as initiator a high polymerization activity according to the polymerization rate. First order kinetics confirm the living character of the polymerization. However, the deviation of molecular weights from theoretical molecular weights and the broad molecular weight distributions hint for a low controlled ATRP. The ATRP with further copper(I) salts {CuCl, [Cu(MeCN)4]BF4 and [Cu(MeCN)4]PF6} and PECl and PEBr as initiators were investigated as well. Herein the use of [Cu(MeCN)4]PF6 with PECl led to promising results. 相似文献
995.
IS Ibarra JA Rodriguez ME Páez-Hernández EM Santos JM Miranda 《Electrophoresis》2012,33(13):2041-2048
A magnetic solid-phase extraction (MSPE) method combined with capillary electrophoresis for the simultaneous determination of seven quinolones (QNs) (danofloxacin, ciprofloxacin, marbofloxacin, enrofloxacin, difloxacin, oxolinic acid, and flumequine), using (S)-(+)-6-methoxy-α-methyl-2-naphthaleneacetic acid as internal standard, in milk samples was developed. The variables involved in the preconcentration magnetic procedure were: the composition of the magnetic support composition, the sample pH, and the weight of magnetic adsorbent used. The variables were optimized using a simplex-lattice design. Different magnetite covered with octyl-phenyl silica adsorbents were synthesized by varying the molar ratio of phenyltrimethylsilane and octyltrimethoxysilane; the solids were evaluated for QN preconcentration. Under optimal conditions, a linear range was obtained from 27 to 1000 μg L(-1) with limits of detection ranging from 9 to 12 μg L(-1) for the seven QNs. The absolute recoveries of the seven QNs at three different spiked levels (40, 150, and 400 μg L(-1) ) ranged from 74% to 98% with a relative standard deviation less than 10% in all cases. The proposed method was applied to analyze 20 whole milk samples of different brands. All samples were positive for the presence of QN residues; in some cases, extract dilution was required. The concentrations found are in the range from 31.1 to 5047.3 μg L(-1) . Marbofloxacin was the most frequently found. The method proposed offers advantages in terms of simplicity, sensitivity, efficiency, cost, and analysis time making it an alternative for the analysis of QNs in whole milk samples. 相似文献
996.
ET da Costa CA Neves GM Hotta DT Vidal MF Barros AA Ayon CD Garcia CL do Lago 《Electrophoresis》2012,33(17):2650-2659
This paper describes a long-range remotely controlled CE system built on an all-terrain vehicle. A four-stroke engine and a set of 12-V batteries were used to provide power to a series of subsystems that include drivers, communication, computers, and a capillary electrophoresis module. This dedicated instrument allows air sampling using a polypropylene porous tube, coupled to a flow system that transports the sample to the inlet of a fused-silica capillary. A hybrid approach was used for the construction of the analytical subsystem combining a conventional fused-silica capillary (used for separation) and a laser machined microfluidic block, made of PMMA. A solid-state cooling approach was also integrated in the CE module to enable controlling the temperature and therefore increasing the useful range of the robot. Although ultimately intended for detection of chemical warfare agents, the proposed system was used to analyze a series of volatile organic acids. As such, the system allowed the separation and detection of formic, acetic, and propionic acids with signal-to-noise ratios of 414, 150, and 115, respectively, after sampling by only 30 s and performing an electrokinetic injection during 2.0 s at 1.0 kV. 相似文献
997.
The formation and properties of carbonate adducts of some organic hydroxy compounds in aqueous medium were investigated. Fatty alcohols and sugars were chosen as representative classes of biological interest, and the medium was carbonated aqueous solution with pH ranging from 3.0 to 8.3. Capillary electrophoresis with two capacitively coupled contactless conductivity detectors (C4Ds) was used for quantitation and to obtain the mobility of the monoalkyl carbonates (MACs), which were used to determine the equilibrium and kinetic constants of the reaction as well as the diffusion coefficients. For increasing chain length of the alcohols, the equilibrium constant tends to the unit, which suggests that fatty alcohols can form the corresponding MACs. The formation of MACs for cyclohexanol and cyclopentanol also suggest the existence of similar species for sterols. Carbonate adducts of fructose, glucose, and sucrose were also detected, which suggests that these counterparts of the well‐known phosphates can also occur in the cytosol. Our calculations suggest that one in 1000 to one in 10 000 molecules of these hydroxy compounds would be available as the corresponding MAC in such a medium. Experiments carried out at pH values less than 3.0 showed that there is a catalytic effect of hydronium on the interconversion of bicarbonate and a MAC. Taking into account the great number of hydroxy compounds similar to the ones investigated and that bicarbonate is ubiquitous in living cells, one can anticipate the existence of a whole new class of carbonate adducts of these metabolites. 相似文献
998.
Roseany V. V. Lopes Luis F. B. Osorio Maria L. Santos Maria J. A. Sales 《Macromolecular Symposia》2012,319(1):173-178
Summary: Given the demand for renewable resources by industries and the promising potential of vegetable oils for this purpose, the current study aims to evaluate the properties of polyurethanes (PUs) obtained from linseed (Linum usitatissimun L.) oil (PULO) and passion fruit (Passiflora edulis Sims f. flavicarpa Degener) oil (PUPFO), by thermogravimetry (TG), derivative thermogravimetry (DTG), dynamic mechanical analysis (DMA) and Fourier transform infrared (FT-IR). The results showed that PULO is more thermally stable than PUPFO, suggesting that the first presents more urethane linkages. The DMA analysis showed that both prepared PUs have uneven porosity, causing the loss of the elastic plateau. It was found as well that PUPFO exhibits a higher value of glass transition temperature (Tg), signifying that it seems to be more crosslinked than PULO. The analysis by FT-IR showed that the curing reaction of PUs was successful. 相似文献
999.
André L. Santos Regina M. Takeuchi Rodrigo A. A. Muñoz Lúcio Angnes Nelson R. Stradiotto 《Electroanalysis》2012,24(8):1681-1691
This article critically reviews the electroanalytical methods developed for the determination of inorganic contaminants in automotive fuels. Topics include the methods applied to the analysis of liquid biofuels and liquid fossil fuels for which different strategies were developed based on analytes and sample matrices. Special attention is given to electrodes, detection techniques, and sample preparation protocols (when required). Analytes include anions such as chloride, sulfate and phosphate, and mainly metallic species such as sodium, potassium, magnesium, calcium, cadmium, copper, iron, lead, manganese, mercury, nickel, platinum, tin, vanadium, and zinc. Suggestions for future research are also presented. 相似文献
1000.
Francisco J. Enríquez‐Medrano Martín Hernández‐Valdez Hortensia Maldonado‐Textle Patrick Lacroix‐Desmazes Ramiro Guerrero‐Santos 《先进技术聚合物》2012,23(3):375-381
S‐allyl‐4‐methyldithiobenzoate was synthesized and used as a chain transfer agent for the RAFT polymerization of butyl acrylate to produce a functionalized acrylic rubber. A solution of 8 wt% of this functionalized rubber was prepared in styrene and polymerized to generate a material called acrylic rubber‐modified polystyrene (AMP) constituted by well‐dispersed particles of poly(butyl acrylate)‐block‐poly(styrene) into a polystyrene matrix. Impact strength of injection‐molded samples of AMP was measured and compared with the general purpose polystyrene (GPPS) and the high impact polystyrene (HIPS). AMP itself showed an impact strength value similar to GPPS; however, when AMP was blended with conventional HIPS, the resulting material exhibited an improvement of 76–91% as compared to HIPS by itself, without affecting negatively tensile properties. Transmission electron microscopy analysis revealed both kinds of dispersed phases, i.e. the typical salami particles of polybutadiene coming from HIPS (size: 0.5–2 µ) and small particles from poly(butyl acrylate)‐block‐poly(styrene) (size: ~50 nm). We clearly showed that such a bimodality of the particle size distribution caused the positive synergistic effect on impact strength. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献