Phthalimide and tetraethylammonium hydroxide react via an unusual pathway to afford tetraethylammonium 2-(carbamoyl)benzoate (TEACB) which is of interest as a bifunctional organocatalyst. TEACB (0.5 mol %) was found to catalyze the addition of trimethylsilyl cyanide (TMSCN) to carbonyl compounds under solvent-free conditions at room temperature with very short reaction times. A wide variety of aldehydes and ketones were transformed into the corresponding cyanohydrin trimethylsilyl ethers in high to quantitative yields. 相似文献
Super-paramagnetic iron oxide (SPIO) nanoparticles are actively investigated to enhance disease detection through molecular imaging using magnetic resonance imaging (MRI). Detection of the cells labeled by SPIO depends on the MRI protocols and pulse sequence parameters that can be optimized. To evaluate the sensitivity and specificity of the image acquisition methods and to obtain optimal imaging parameters for single-cell detection, we further developed an MRI simulator. The simulator models an object (tissue) at a microscopic level to evaluate effects of spatial distribution and concentration of nanoparticles on the resulting image. In this study, the simulator was used to evaluate and compare imaging of the labeled cells by the gradient-echo (GE), true-FISP [fast imaging employing steady-state acquisition (FIESTA)] and echo-planar imaging (EPI) pulse sequences. Effects of the imaging and object parameters, such as field strength, imaging protocol and pulse sequence parameters, imaging resolution, cell iron load, position of SPIO within the voxel and cell division within the voxel, were investigated in the work. The results suggest that true-FISP has the highest sensitivity for single-cell detection by MRI. 相似文献
The purpose of the present work is to develop a simple, rapid, sensitive and accurate method for the derivatization and subsequently preconcentration of Hg(II) and the determination of its derivative, diphenylmercury, in natural water samples using gas chromatography-flame ionization detection. The method is based on the diphenylation using phenyl boronic acid, subsequent extraction of phenylmercury into a single drop of an organic solvent (toluene), followed by gas chromatography-flame ionization detection GC-FID analysis of the extract. The pH of the feed solution was kept in pH 5 with acetate buffer solution. Thus, the optimized conditions are: organic solvent, toluene; derivatization time, 10 min; extraction time, 15 min; microdrop volume, 1.6 μL; stirring rate, 600 rpm; sample volume, 5 mL. The limit of detection (LOD), calculated on the basis of five replicates was 0.02 μg mL−1. The relative standard deviation of the method (RSD%, n = 5) was 3.0. Linear range was between 0.05 and 5 μg mL−1 and preconcentration factor obtained for phenyl-mercury was 105.
The aim of the present study was to develop controlled drug delivery systems based on nanotechnology. Two different nanocarriers were selected, chitosan-alginate nanoparticles as hydrophilic and solid lipid nanoparticles as lipophilic carriers. Nanoparticles were prepared and characterized by evaluating particle size, zeta potential, SEM pictures, DSC thermograms, percentage of drug loading efficiency, and drug release profile. The particle size of SLNs and Chi/Alg nanoparticles was 291 ± 5 and 520 ± 16. Drug loading efficiency of Chi/Alg and SLN particles were 68.98 ± 5.5% and 88 ± 4.5%. The drug release was sustained with chitosan-alginate system for about 45 hours whereas for SLNs >98% of the drug was released in 2 hours. Release profile did not change significantly after freeze drying of particles using cryoprotector. Results suggest that under in vitro condition chitosan/alginate systems can act as promising carriers for ciprofloxacin and may be used as an alternative system in sustained delivery of ciprofloxacin. 相似文献
In this study, a platinum electrode was coated with NiZn layer (Pt/NiZn) in a nickel-zinc bath by electrodeposition for use
as anode material for methanol electrooxidation in alkaline solution. The electrode prepared was etched in a concentrated
alkaline solution (30% NaOH) to produce a porous and electrocatalytic surface suitable for use in the methanol electrooxidation
(Pt/NiZn). The surface morphologies and compositions of coating before and after alkaline leaching were determined by energy
dispersive X-ray (EDX) and scanning electron microscopy (SEM) techniques. The effect of NiZn coated platinum electrode for
methanol electrooxidation was investigated in 1 M NaOH solution by cyclic voltammetry (CV) and electrochemical impedance spectroscopy
(EIS) techniques. Methanol electrooxidation on Pt/NiZn electrode was studied at various temperatures and potential scan rates.
The results showed that Pt/NiZn electrode behaved as an efficient catalyst for the electrooxidation of methanol in alkaline
medium. 相似文献
In this study, N-heterocyclic carbene–Au(I) complex, chloro[1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene]gold (I), was successfully encapsulated within mesopores of a magnetic core/shell (γ-Fe2O3@SiO2) silica gel through post-pore-size reduction by silylation reactions The post-reduction of the pore size not only minimizes the catalyst leaching during the alkyne hydration reactions but also eliminates any need for covalent modification of the catalyst or support surface. The resulting catalyst exhibits high activity in hydration reactions of various alkynes even under low catalytic loadings. The catalyst can be easily recycled from the reaction mixture using a magnet and can be reused in alkyne hydration reactions up to six times with only 52. wt% Au leaching. 相似文献
Journal of Structural Chemistry - A new complex of Pt(II) bearing N-(bis(2,4-dimethoxybenzyl)carbamothioyl)-4-methylbenzamide ligand is prepared and characterized by 1H, 13C, HMQC, COSY NMR and... 相似文献
Digoxin is widely used as a cardiac glycoside drug in the treatment of various heart conditions. Because it is a toxic drug, it should be regularly monitored in the serum of patients under treatment. In this study, colloidal nanogold is synthesized and the preparation of nanogold-labeled monoclonal antibody probe to digoxin is described under optimal conditions. In addition, an immunochromatographic (IC) method for digoxin analysis employing nanogold-labeled probe is developed. With this technique, it requires only 5 min to complete the quantitative detection of digoxin. The detection time is decreased 20–30 times in comparison to radioimmunoassay (RIA). The sensitivity to digoxin was about 2 ng/ml by naked eye, which is within the therapeutic and toxic ranges of digoxin. The results of serum samples obtained by IC strip were in agreement with those obtained by RIA. The IC strip was sufficiently sensitive and accurate to be used for the rapid detection of digoxin in serum samples. 相似文献