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121.
J. Rubín J. Bartolomé F. Cruellas I. Flotats I. Belmonte 《Hyperfine Interactions》2009,192(1-3):69-75
The failure of a servo motor with Nd–Fe–B magnets under harsh atmospheric conditions is analysed. The magnets presented corrosion both on the side glued to the rotor (magnet-bottom) and on the opposite side (magnet-top), and eventually came off the rotor shaft. The corrosion products were studied by X-ray diffraction and Mössbauer spectroscopy and compared to the uncorroded magnet material. The observed products, Nd(OH)3 and iron oxyhydroxides, evolve from the magnet-bottom to the top, and show that the atmospheric environment was wet with a high concentration of salts. Finally, some paramagnetic powder was found away from the magnet set, as a consequence of rotor rotation, and it represents a further oxidation process of the magnet products. The surface protection of the magnets has shown to be insufficient for the atmospheric working conditions. 相似文献
122.
Cheryl Aharon Fernando G. Guijarro Samara Medina Rivero Prof. Francisco J. Ramírez Dr. Rubén Caballero Prof. Juan Casado Prof. Fernando Langa Prof. Shlomo Rozen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(2):464-468
Oligo-S,S-dioxothienylenevinylenes have been prepared by transferring oxygen atoms to the sulfur atoms using the HOF ⋅ CH3CN complex. Their photophysical properties are presented in comparison with their thiophenevinylene congeners. Together with their vibrational properties and molecular force fields, this study allows for the interpretation of the alteration of aromaticity and inter-ring exocyclic π-conjugation in this series. 相似文献
123.
Eva Mª Barea Dr. Rubén Caballero Francisco Fabregat‐Santiago Dr. Pilar De La Cruz Dr. Fernando Langa Prof. Juan Bisquert Prof. 《Chemphyschem》2010,11(1):245-250
Five new sensitizers for dye sensitized solar cells have been designed consisting of conjugated thienylenevinylene units threaded with alkyl chains to improve solubility and cyanoacetic acid as anchoring group. The conjugation length was increased from 2 to 6 thienylenevinylene units, which resulted in a red‐shift of the optical absorption of the dyes from 550 to 750 nm, improving the spectral overlap with the solar spectrum. The photovoltaic performance of these dyes as sensitizers in mesoporous TiO2 solar cells shows a clear correlation of increasing photocurrent with the extension of the conjugation up to an optimal length. Further extension of the conjugation increases the absorption but additional effects like self‐quenching or recombination processes reduce the photocurrent and photovoltages and consequently the overall efficiency of the DSC. 相似文献
124.
125.
Rubí Zamudio-Vázquez Sa?ka Ivanova Miguel Moreno Maria Isabel Hernandez-Alvarez Ernest Giralt Axel Bidon-Chanal Antonio Zorzano Fernando Albericio Judit Tulla-Puche 《Chemical science》2015,6(8):4537-4549
The synthesis of a new small library of quinoxaline-containing peptides is described. After cytotoxic evaluation in four human cancer cell lines, as well as detailed biological studies, it was found that the most active compound, RZ2, promotes the formation of acidic compartments, where it accumulates, blocking the progression of autophagy. Further disruption of the mitochondrial membrane potential and an increase in mitochondrial ROS was observed, causing cells to undergo apoptosis. Given its cytotoxic activity and protease-resistant features, RZ2 could be a potential drug candidate for cancer treatment and provide a basis for future research into the crosstalk between autophagy and apoptosis and its relevance in cancer therapy. 相似文献
126.
127.
Shurbaji M Abu Al Rub MH Saket MM Qaisi AM Salim ML Abu-Nameh ES 《Journal of AOAC International》2010,93(6):1868-1873
A rapid, simple, and sensitive RP-HPLC analytical method was developed for the simultaneous determination of triclabendazole and ivermectin in combination using a C18 RP column. The mobile phase was acetonitrile-methanol-water-acetic acid (56 + 36 + 7.5 + 0.5, v/v/v/v) at a pH of 4.35 and flow rate of 1.0 mL/min. A 245 nm UV detection wavelength was used. Complete validation, including linearity, accuracy, recovery, LOD, LOQ, precision, robustness, stability, and peak purity, was performed. The calibration curve was linear over the range 50.09-150.26 microg/mL for triclabendazole with r = 0.9999 and 27.01-81.02 microg/mL for ivermectin with r = 0.9999. Calculated LOD and LOQ for triclabendazole were 0.03 and 0.08 microg/mL, respectively, and for ivermectin 0.07 and 0.20 microg/mL, respectively. The intraday precision obtained was 98.71% with RSD of 0.87% for triclabendazole and 100.79% with RSD 0.73% for ivermectin. The interday precision obtained was 99.51% with RSD of 0.35% for triclabendazole and 100.55% with RSD of 0.59% for ivermectin. Robustness was also studied, and there was no significant variation of the system suitability of the analytical method with small changes in experimental parameters. 相似文献
128.
An efficient Cu(I)-catalyzed asymmetric [3 + 2] cycloaddition of N-(2-pyridylmethyl) imines has been developed. In the presence of a Cu(CH(3)CN)(4)PF(6)/bisoxazoline catalyst system, high levels of enantioselectivity (up to 97% ee) and moderate to high exo selectivity were achieved with a wide variety of substituted dipolarophiles, including maleimides, fumarates, fumarodinitrile, enones, and nitroalkenes. The reaction with unsymmetrically substituted dipolarophiles is completely regioselective. 相似文献
129.
[reaction: see text] A new iron(III) halide-promoted aza-Prins cyclization between gamma,delta-unsaturated tosylamines and aldehydes provides six-membered azacycles in good to excellent yields. The process is based on the consecutive generation of gamma-unsaturated-iminium ion and further nucleophilic attack by the unsaturated carbon-carbon bond. Homoallyl tosylamine leads to trans-2-alkyl-4-halo-1-tosylpiperidine as the major isomer. In addition, the alkyne aza-Prins cyclization between homopropargyl tosylamine and aldehydes gives 2-alkyl-4-halo-1-tosyl-1,2,5,6-tetrahydropyridines as the only cyclic products. 相似文献
130.
Vignaduzzo SE Maggio RM Castellano PM Kaufman TS 《Analytical and bioanalytical chemistry》2006,386(7-8):2239-2244
Two new analytical methods have been developed as convenient and useful alternatives for simultaneous determination of hydrochlorothiazide
(HCT) and propranolol hydrochloride (PRO) in pharmaceutical formulations. The methods are based on the first derivative of
ratio spectra (DRS) and on partial least squares (PLS) analysis of the ultraviolet absorption spectra of the samples in the
250–350-nm region. The methods were calibrated between 8.7 and 16.0 mg L−1 for HCT and between 14.0 and 51.5 mg L−1 for PRO. An asymmetric full-factorial design and wavelength selection (277–294 nm for HCT and 297–319 for PRO) were used
for the PLS method and signal intensities at 276 and 322 nm were used in the DRS method for HCT and PRO, respectively. Performance
characteristics of the analytical methods were evaluated by use of validation samples and both methods showed to be accurate
and precise, furnishing near quantitative analyte recoveries (100.4 and 99.3% for HCT and PRO by use of PLS) and relative
standard deviations below 2%. For PLS the lower limits of quantification were 0.37 and 0.66 mg L−1 for HCT and PRO, respectively, whereas for DRS they were 1.15 and 3.05 mg L−1 for HCT and PRO, respectively. The methods were used for quantification of HCT and PRO in synthetic mixtures and in two commercial
tablet preparations containing different proportions of the analytes. The results of the drug content assay and the tablet
dissolution test were in statistical agreement (p < 0.05) with those furnished by the official procedures of the USP 29. Preparation of dissolution profiles of the combined
tablet formulations was also performed with the aid of the proposed methods. The methods are easy to apply, use relatively
simple equipment, require minimum sample pre-treatment, enable high sample throughput, and generate less solvent waste than
other procedures.
Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users. 相似文献