Journal of Analytical Chemistry - In this article, a new spectrofluorometric method was developed for the determination of methamphetamine based on a turn-on luminescence response of captopril... 相似文献
Journal of Thermal Analysis and Calorimetry - This paper reports the successful synthesis of NaX nanocrystals using an organic, additive-free hydrothermal approach. Then, solution casting was used... 相似文献
Journal of Thermal Analysis and Calorimetry - In this study, the efficacy of incorporating phase change material (PCM) into the building walls on the annual heat transfer reduction is examined.... 相似文献
Structural Chemistry - Carbon force fields are widely used for obtaining structural properties of carbon nanomaterials. We evaluate the performance of a wide range of carbon force fields for... 相似文献
Journal of Thermal Analysis and Calorimetry - The purpose of this study is to numerically investigate flow field and turbulent heat transfer of hybrid nanofluid, water–DWCNT–TiO2 in a... 相似文献
Quantum de Rham complexes on the quantum plane and the quantum group itself are constructed for the nonstandard deformation of Fun(SL(2)). It is shown that in contrast to the standardq-deformation of SL(2), the above complexes are unique for SLh(2). Also, as a byproduct, a new deformation of the two-dimensional Heisenberg algebra is obtained which can be used to construct models ofh-deformed quantum mechanics. 相似文献
A novel SBA-15-based fluorescent sensor, SBA-PI: mesoporous SBA-15 structure modified with iminostilbene groups, was designed, synthesized, and characterized by Fourier transform-infrared spectroscopy (FT-IR), ultraviolet–visible spectroscopy, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), thermogravimetric analysis (TGA), low-angle X-ray diffraction techniques (low-angle XRD), and N2 adsorption–desorption techniques. The SBA-PI as a sensor with a selective behavior for detection of Cu2+ comprises iminostilbene carbonyl as the fluorophore group. The SBA-PI sensor displays an excellent fluorescence response in aqueous solutions and the fluorescence intensity quenches remarkably upon addition of Cu2+. Other common interfering ions even at high concentration ratio showed either no or very small changes in the fluorescence intensity of SBA-PI in the absence of Cu2+. A limit of detection of 8.7 × 10−9 M for Cu2+ indicated that this fluorescence sensor has a high sensitivity and selectivity toward the target copper (II) ion. The fabricated Cu2+ sensor was successfully applied for the determination of the Cu2+ in human blood samples without any significant interference. With the selective analysis of Cu2+ ions down to 0.9 nM in blood, the sensor is a promising and a novel detection candidate for Cu2+ and can be applied in the clinical laboratory. A reversibility and accuracy in the fluorescence behavior of the sensor was found in the presence of I¯ that was described as a masking agent for Cu2+.
In this work a modified form of the Ghotbi–Vera Mean Spherical Approximation model (MGV-MSA) has been used to correlate the mean ionic activity coefficients (MIAC) for a number of symmetric and asymmetric aqueous electrolyte solutions at 25 °C. In the proposed model the hard sphere as well as the electrostatic contributions to the MIAC and the osmotic coefficient of the previously GV-MSA model has been modified. The results of the proposed model for the MIAC of the electrolyte solutions studied in this work are used to directly calculate the values of the osmotic coefficients without introducing any new adjustable parameter. In the MGV-MSA model the cation diameter as well as the relative permittivity of water depends on the electrolyte concentration. Having considered such dependency for both cation and relative permittivity for water in an electrolyte solution the modification of the GV-MSA has been made. It should be stated that in the MGV-MSA model the anion diameter in the solution similar to that in the GV-MSA model remains constant and independent of the electrolyte concentration. The results obtained from the proposed model have been favorably compared with those of the GV-MSA model. The results showed that the MGV-MSA model can more accurately correlate the MIAC of the single electrolyte solutions than those of the GV-MSA model. The same comparison has been observed in case of the osmotic coefficients for the electrolyte solutions studied in this work. It should be noted that in order to do an unequivocal comparison between the results obtained from the models used in this work the same minimization procedure and the same experimental data for the MIAC and the osmotic coefficients have been used. Also it should be mentioned that in the MGV-MSA model the conversion from the McMillan–Mayer (MM) framework to that of the Lewis–Randall (LR) has been performed. It has been concluded that such transformation can affect the results in particular at higher electrolyte concentrations. 相似文献
Pyrimethamine acts against malarial parasites by selectively inhibiting their dihydrofolate reductase-thymidylate synthase. Resistance to pyrimethamine in Plasmodium falciparum is due to point mutations in the DHFR domain, initially at residue 108 (S108N), with additional mutations imparting much greater resistance. Our previous work, the development of a simple rational drug design strategy to overcome such resistance, used suitable meta-substituents in the pyrimethamine framework to avoid the unfavorable steric clash with mutant side chains at position 108. Interestingly, the meta-chloro analog of pyrimethamine not only overcame the resistance due to S108N, but also that contributed by the more remote mutation, C59R. The present work improves on this by means of other meta-substituents. Against wild type DHFR, double mutant types A16V + S108T and C59R + S108T, and the highly pyrimethamine/cycloguanil-resistant quadruple-mutant form N51I + C59R + S108N + I164L, pyrimethamine itself gave Ki values of 1.5, 2.4, 72.3 and 859 nM, respectively. The meta-substituted analogs, especially the meta-bromo analog, were much more powerful inhibitors of these DHFRs, including the quadruple-mutant form (meta-bromo analog, Ki 5.1 nM). For comparison, the dihydropyrazine antifolate, WR99210, gave Ki values of 0.9, 3.2, 0.8 and 0.9 nM, respectively. Ki values were also measured against recombinant human DHFR, as were their activities against the growth of Plasmodium falciparum cultures bearing the double mutations (FCB and K1 strains) and quadruple mutation (V1/S) and the wild type (3D7). The meta-analogs were highly active against all of these, with the meta-bromo again being the strongest, having an IC50 of 37 nM against V1/S, compared to > 5000 nM for pyrimethamine itself and 1.1 nM for WR99210. 相似文献