排序方式: 共有73条查询结果,搜索用时 421 毫秒
1.
Zamudio-Rivera LS George-Tellez R López-Mendoza G Morales-Pacheco A Flores E Höpfl H Barba V Fernández FJ Cabirol N Beltrán HI 《Inorganic chemistry》2005,44(15):5370-5378
The one pot reaction of salicylaldehyde 1, beta-amino alcohols 2a-2c, and di-n-butyltin(IV) oxide 3a or diphenyltin(IV) oxide 3b produced five diorganotin(IV) compounds, 4a-4c, 5a, and 5c, in good yields. All compounds were characterized by IR, (1)H, (13)C, and (119)Sn NMR spectroscopy, and elemental analysis; furthermore, compounds 4b, 4c, 5a, and 5c were characterized by X-ray diffraction analysis. After the structural characterization, all of the compounds were tested in vitro against Bacillus subtilis (Gram-positive, strain ATCC 6633), Escherichia coli (Gram-negative, strain DH5alpha), Pseudomonas aeruginosa (Gram-negative, strain BH3), Desulfovibrio longus (strain DSM 6739), and Desulfomicrobium aspheronum (strain DSM 5918) to assess their antimicrobial activity. Compounds 4 and 5 demonstrated a wide range of bactericidal activities against the tested aerobic (one Gram-positive and two Gram-negative subtypes) and anaerobic bacteria (two sulfate-reducing bacteria, SRB). Compound 5 had better bactericidal performances than compound 4. For all of the compounds, the acute toxicity was measured using luminescent bacteria toxicity (LBT-Microtox) tests to track their further environmental impact. According to these results and in order to fulfill environmental regulations, the toxicity of the compounds studied herein can be modulated through the proper selection of the disubstituted tin(IV) moiety. 相似文献
2.
Dabek-Zlotorzynska E Aranda-Rodriguez R Graham L 《Journal of separation science》2005,28(13):1520-1528
Urban fine airborne particulate matter (PM2.5) and vehicle emission samples were studied for water-soluble low-molecular-weight carboxylic acids using CE with indirect UV detection. Further identification of these acids was achieved using GC-MS as their butyl esters (after derivatization with BF3/butanol). Several dicarboxylic acids in the range C2-C10 including straight-chain, branched-chain, cis- and trans-unsaturated, and aromatic acids were confirmed by GC-MS. In addition, aromatic acids such as benzoate, phthalate, terephthalate, isophthalate, and 4-methylphtalate were present in such samples, but some of these were not well resolved by the used CE method. Oxocarboxylic acids (Cn(w) with n > 4) were also identified by GC-MS but not determined by CE due to lack of standards. The rapidity and simplicity of the CE method were clearly demonstrated, and the method was observed to be advantageous for routine monitoring of water-soluble organic acids in airborne PM2.5 and vehicle emission at low microg/L levels. 相似文献
3.
Rocio Marilyn Caja Rivera 《Mathematical Methods in the Applied Sciences》2019,42(18):6810-6828
Vector‐borne diseases, such as leishmaniasis, dengue, malaria, and yellow fever, transmitted by microparasites show periodic fluctuations in their prevalence. The novelty of this research is to assess the relationship between the vector feeding preference for an infectious host and the annual seasonal transmission through a vector‐host mathematical model. For the first time, numerical simulations illustrate that by increasing the vector feeding preference value in the transmission dynamics, periodic fluctuations accentuate and the endemic equilibrium average increases in vector and host populations. Moreover, increasing the vector feeding preference value, the amplitude strengthens for the infectious host and vector populations. This periodic behavior shows a similar pattern with the Peruvian incidence data from 2000 to 2016 for Andean cutaneous leishmaniasis provided by the Ministry of Health of Peru (MINSA). In addition, using the Floquet theory, the time average method and the linear operator method provides for the first time that the basic reproduction number for a nonautonomous system depends explicitly on the vector feeding preference for the infectious host. The nonautonomous model system shows that is a threshold parameter for the local stability of the disease‐free periodic solution. Therefore, the vector feeding preference is an important factor that should be considered and attended to for future research. Public and veterinary health in Peru and other countries should consider the vector feeding preference for specific host to vector control. 相似文献
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Reyes Malavé Osuna Rocio Ponce Ortiz Mari Carmen Ruiz Delgado Valentin G Nenajdenko Viktor V Sumerin Elizabeth S Balenkova Víctor Hernández Juan Teodomiro López Navarrete 《Chemphyschem》2007,8(5):745-750
Herein, we study the conjugation properties of three different thienoacenes, each of which has three or four fused thiophene rings, by means of Fourier transform Raman spectroscopy. The B3LYP/6-31G** vibrational analysis of all of the collected spectroscopic data evidences that the selective enhancement of a limited number of Raman scatterings is related to the occurrence in the three thienoacenes of a vibronic coupling between the lowest unoccupied frontier molecular orbital (LUMO) and some Raman-active skeletal nu(C==C) stretching modes of 1600-1300 cm(-1). 相似文献
6.
Rocio Díez Azofra Luis A. Sarabia Maria Cruz Ortiz 《Analytical and bioanalytical chemistry》2010,396(2):923-935
The objective of this work is to optimize a solid-phase extraction procedure for the simultaneous determination of sulfadiazine,
sulfamerazine, and sulfamethazine in milk by fluorimetric detection. For this task, an alternative strategy is employed, which
allows one to reduce noticeably the number of experiments without losing the quality of the estimations. It consists of the
use of a D-optimal design together with PARAFAC decomposition for the calculation of the response in the experimental design.
Effects of amount of cartridge sorbent, kind of milk, volume of conditioning solutions, kind of wash and elution, and kind
of mixture of sulfonamides have been evaluated, for maximizing sulfonamide mean recovery and minimizing its standard deviation.
Since milk without sulfonamides may give some matrix effect over the fluorescence signal, its behavior has also been studied.
Optimal conditions have been selected where the ratio between sulfonamide recovery and milk without sulfonamides was the highest,
which are 500 mg of cartridge sorbent, acid wash, and elution and 3 mL of conditioning solutions. The type of milk and mixture
of sulfonamides not significant. This makes the procedure suitable for the combined determination of sulfadiazine, sulfamerazine,
and sulfamethazine in any kind of milk. Finally, an experimental procedure is proposed, obtaining a sulfonamide mean recovery
equal to 68.5% with values of standard deviation between 7 and 8 μg kg−1. 相似文献
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Rocio Bueno‐Perez Dr. Juan J. Gutiérrez‐Sevillano Dr. David Dubbeldam Prof. Patrick J. Merkling Prof. Sofia Calero 《Chemphyschem》2015,16(13):2735-2738
The separation of pentanol isomer mixtures is shown to be very efficient using the nanoporous adsorbent zeolitic imidazolate framework ZIF‐77. Through molecular simulations, we demonstrate that this material achieves a complete separation of linear from monobranched—and these from dibranched—isomers. Remarkably, the adsorption and diffusion behaviors follow the same decreasing trend, produced by the channel size of ZIF‐77 and the guest shape. This separation based on molecular branching applies to alkanes and alcohols and promises to encompass numerous other functional groups. 相似文献
9.
A reverse-phase high-performance liquid chromatographic method has been developed for the separation and simultaneous determination
of two COX-2 inhibitors, celecoxib and rofecoxib, in addition to two well-known non-steroidal anti-inflammatory drugs (NSAIDs),
sodium diclofenac and niflumic acid in human serum samples. Good chromatographic separation was achieved using a C18 bonded
silica column applying a gradient with acetronitrile and water, from 15 to 60% acetonitrile. The mobile phase contained 0.1%
trifluoroacetic acid as an organic modifier. Detection was made using a diode array detector (DAD) and the analytical parameters
were established at the wavelength maximum in the UV spectrum of each drug. Linearity was studied up to 100.0 mg L−1. Calibration functions, quantification and detection limits, intra- and inter-day reproducibility and accuracy were estimated
for each drug. Solid phase extraction was needed to separate and concentrate the drugs from human serum samples. The method
was successfully applied to determine the drugs in human serum samples at levels of 1.0 mg L−1. 相似文献
10.
Yahia Didane Rocio Ponce Ortiz Jian Zhang Keijyu Aosawa Toshinori Tanisawa Hecham Aboubakr Frédéric Fages Jörg Ackermann Noriyuki Yoshimoto Hugues Brisset Christine Videlot-Ackermann 《Tetrahedron》2012,68(24):4664-4671
Solution and solid-state properties of two new perfluoroalkyl end-substituted analogues of distyryl-bithiophene (CF3-DS2T and diCF3-DS2T) are presented. Vacuum deposited thin films were investigated by atomic force microscopy, X-ray diffraction, and implemented as active layers into organic thin film transistors. While physicochemical measurements in solution suggest a preferential hole injection and transport inside CF3-DS2T and diCF3-DS2T films, electrical measurements performed under high vacuum show that CF3-DS2T behaves as n-type semiconductor while no charge transport was measured in diCF3-DS2T. The results highlighted the importance of substituents on conjugated backbone and on the resulting fine ordering in solid state to control the charge transport. 相似文献