Cobalt promoted Ni/MgAl2O4 catalyst in lean methane catalytic oxidation

In the present research, magnesium aluminate spinel was prepared as catalyst support using a novel, facile, and efficient mechanochemical method. The Co-promoted catalysts with 20 wt.% of Ni were fabricated using an impregnation route and the samples were analyzed by the X-ray diffraction (XRD), N₂ adsorption/desorption (BET), temperature-programmed reduction and desorption (H₂-TPR and O₂-TPD), and field emission scanning electron microscopy (FESEM) tests. The results confirmed that all samples have a mesoporous structure with a high specific surface area and the presence of cobalt caused complete CH₄ oxidation at low temperatures, and no side reactions were observed. The results indicated that the 3%Co-20%Ni/MgAl₂O₄ catalyst was the optimal sample among the prepared catalysts, owing to the improvement of reduction features and oxygen mobility. The 50 and 90% of methane conversion was obtained at 530 and 600 °C, respectively. Also, the influence of calcination temperature, GHSV, and feed ratio was determined on the catalytic activity. The obtained outcomes revealed that the calcination temperature has a significant effect on the textural properties and catalytic efficiency. The sample calcined at 700 °C showed the weakest performance, which was related to the sintering of particles at high temperatures. The catalytic stability showed that the 3%Co-20%Ni/MgAl₂O₄ has acceptable stability during 600 min time of reaction.

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Non-isothermal crystallization of NaX nanocrystals/poly (vinyl alcohol) nanocomposite

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...     

Efficacy of incorporating PCMs into the commercial wall on the energy-saving annual thermal analysis

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....     

Superior performance of the machine-learning GAP force field for fullerene structures

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...     

An investigation on the influence of the shape of the vortex generator on fluid flow and turbulent heat transfer of hybrid nanofluid in a channel

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...     

Fully developed mixed convection in horizontal and inclined tubes with uniform heat flux using nanofluid

Fully developed laminar mixed convection of a nanofluid consists of water and Al₂O₃ in horizontal and inclined tubes has been studied numerically. Three-dimensional elliptic governing equations have been solved to investigate the flow behaviors over a wide range of the Grashof and Reynolds numbers. Comparisons with previously published experimental and numerical works on mixed convection in a horizontal and inclined tube are performed and good agreements between the results are observed. Effects of nanoparticles concentration and tube inclinations on the hydrodynamics and thermal parameters are presented and discussed. It is shown that the nanoparticles concentration does not have significant effects on the hydrodynamics parameters. Heat transfer coefficient increases by 15% at 4 Vol.% Al₂O₃. Skin friction coefficient continually increases with the tube inclination, but the heat transfer coefficient reaches a maximum at the inclination angle of 45°.     

An ultrasensitive fluorescence sensor for determination of trace levels of copper in blood samples

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⁺.

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Pyrimethamine analogs as strong inhibitors of double and quadruple mutants of dihydrofolate reductase in human malaria parasites

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.