27Al and 31P NMR Investigations of Soluble Aluminophosphate Species in Alcohol–Water Mixtures

In this work, phosphorus-31 and aluminum-27 nuclear magnetic resonance techniques were used to characterize the distribution of soluble aluminophosphate species in methanol + water and ethanol + water mixtures. The assignment of the peaks to aluminate species was attempted, clarifying earlier work and producing information on the different aluminophosphate complexes. Nine peaks were observed at ?0.41, ?6.4, ?7.5, ?7.9, ?13.1, ?13.9, ?16.6, ?18.1 and ?20.6 ppm. Four new peaks appeared in the ³¹P NMR spectra of the alcoholic aluminophosphate solutions and their intensities changed with changes of the alcohol:water volume ratio. These new peaks were observed in the presence of methanol or ethanol but not in aqueous solutions.     

Synthesis of new substituted cylopentenone derivatives via a one-pot three-component reaction between arylglyoxals,acetylacetone, and amines in aqueous media

An efficient one-pot method for the synthesis of new substituted cylopentenone derivatives is described via reaction of arylglyoxals and acetylacetone with aliphatic amines. This reaction was carried out in aqueous media in the absence of any catalyst or promoter to produce substituted cylopentenone in high yield.     

State‐of‐the‐Art and Trends in Synthesis,Properties, and Application of Quantum Dots‐Based Nanomaterials

Quantum dots (QDs) with a nanoscale size range have attracted significant attention in various areas of nanotechnology due to their unique properties. Different strategies for the synthesis of QD nanoparticles are reported in which various factors, such as size, impurities, shape, and crystallinity, affect the QDs fundamental properties. Consequently, to obtain QDs with appropriate physical properties, it is required to select a synthesis method which allows enough control over the surface chemistry of QDs through fine‐tuning of the synthesis parameters. Moreover, QDs nanocrystals are recently used in multidisciplinary research integrated with biological interfaces. The state‐of‐the‐art methods for synthesizing QDs and bioconjugation strategies to provide insight into various applications of these nanomaterials are discussed herein.     

Nano‐sized silver crystals and their dispersion over α‐alumina for ethylene epoxidation

Ethylene oxide catalyst is a high metal loading catalyst, in which silver crystals is impregnated on α‐Al₂O₃ support. In this type of catalyst, metal dispersion plays an important role on catalyst selectivity for desired products. In this work, silver nitrate and silver oxide together with oxalic and lactic acid as the raw materials were used with different impregnation techniques to make catalysts with high silver content and dispersion. It is also known that the use of promoters affect the metal dispersion on the catalyst support and for that cesium was used as the promoter to improve the silver crystal dispersion. Physical and chemical characteristics of the prepared catalysts, i.e., surface area, pore volume, silver content, nano‐sized silver crystals and their dispersion were measured using BET method, Atomic Absorption Spectroscopy, X‐ray diffraction and TEM. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

On an inequality of Ramanujan concerning the prime counting function

We discuss on the sign of $\mathcal{R}_{\alpha }(x):=\pi(x)^{2}-\frac{\alpha x}{\log x}\pi(\frac{x}{\alpha })$ for x sufficiently large, and for various values of ??>0. The case ??=e refers to a result due to Ramanujan asserting that $\mathcal{R}_{e}(x)<0$ . Related by this inequality, we obtain a conditional result that gives the number N>530.2 such that $\mathcal{R}_{e}(x)<0$ is valid for x>e ^N . Moreover, we show that under assumption of validity of the Riemann hypothesis, the inequality $\mathcal{R}_{e}(x)<0$ holds for x>138,766,146,692,471,228. Then, in various cases for ??, we find numerical values of x _?? in which $\mathcal{R}_{\alpha }(x)$ is strictly positive or negative for x??x _?? .     

Ion population fraction calculations using improved screened hydrogenic model with l-splitting

Ion population fraction(IPF) calculations are very important to understand the radiative spectrum emitted from the hot dense matter. IPF calculations require detailed knowledge of all the ions and correlation interactions between the electrons of an ion which are present in a plasma environment. The average atom models, e.g., screened hydrogenic model with l-splitting(SHML), now have the capabilities for such calculations and are becoming more popular for in line plasma calculations. In our previous work [Ali A, Shabbir Naz G, Shahzad M S, Kouser R, Rehman A and Nasim M H 2018 High Energy Density Phys. 26 48], we have improved the continuum lowering model and included the exchange and correlation effects in SHML. This study presents the calculation of IPF using classical theory of fluctuation for our improved screened hydrogenic model with l-splitting(I-SHML) under local thermodynamic equilibrium conditions for iron and aluminum plasma over a wide range of densities and temperatures. We have compared our results with other models and have found a very good agreement among them.     

Investigating the effects of nanoparticles mean diameter on laminar mixed convection of a nanofluid through an inclined tube with circumferentially nonuniform heat flux

In this study, laminar mixed convection of a water-based nanofluid containing Al₂O₃ nanoparticles in an inclined copper tube, which is heated at the top half surface, is investigated numerically. A heat conduction mechanism through the tube wall was implemented. Three-dimensional equations using a two-phase mixture model were solved to investigate the hydrodynamic and thermal behaviors of the nanofluid over a wide range of nanoparticle volume fractions. To verify the model, the results were compared with previous works and a good agreement between the results was observed. The effect of nanoparticles diameter on the hydrodynamic and thermal parameters over a wide range of Grashof numbers is presented and discussed for a particle volume fraction and Reynolds number. It is shown that the diameter of nanoparticles affects the particle distribution in the cross section perpendicular to the tube axis, heat transfer coefficient, and shear stress.     

Synthesis and Antimicrobial Studies of Some Quinolinylpyrimidine Derivatives

The quinolinylpyrimidine derivatives were prepared by the condensation of quinolinyl chalcones with urea (or thiourea) under basic conditions by using both conventional and microwave heating. Their IR, ¹H NMR, ¹³C NMR, mass spectra and CHN analyses confirmed the prepared compounds. The newly prepared quinolinylpyrimidine derivatives were screened for antimicrobial activities against the bacterial strains viz. S. aureus, Shigella, Salmonela, P. aeroginosa, B. Subtilus and E. coli and found considerably active against S. aureus, P. aeroginosa and E. coli.