Monolithic octadecylsilyl-silica gel column for the high-speed ion chromatographic determination of acidity

A monolithic ODS-silica gel column modified by saturating it with lithium dodecylsulfate (Li-DS) was used to demonstrate the high-speed separation of H+ from other mono- and divalent cations, such as Na+, NH4+, K+, Mg2+ and Ca2+ using ion chromatography (IC). Using a 5 mM EDTA-2K solution containing 0.10 mM Li-DS (pH 4.80) as eluent, H+ was eluted with a sharp and symmetrical peak within 1.0 min before other cations at a flow-rate of 1.5 ml min(-1). The rapid elution of H+ and its conductimetric detection could be attributed to the presence of EDTA (HY2-), which can convert H+ ions as anions. i.e. H(+) + H2Y(2-) --> H3Y(-). The acidity of rainwater and deionized water samples was determined using this IC system with satisfactory results.     

On using the NMR chemical shift to assess polar–nonpolar cross-intermolecular interactions

The possibility of using the NMR chemical shift to evaluate and develop intermolecular potentials for cross-interactions between polar and nonpolar molecules has been examined using the method of molecular dynamics. Such interaction potential models are known to be notoriously difficult to develop. Our work has shown that chemical shift can be obtained quite efficiently in simulations and converges much faster than other properties traditionally used for such evaluations (for example, the infinite dilution activity coefficients, Henry’s constants or the solubility of solutes in solvents). We have also found chemical shift to be quite sensitive to the intermolecular potentials which makes it a rather promising property to investigate polar–nonpolar interactions in fluids.     

Metamaterial absorber based on circular ring structure with and without copper lines

This paper presents the analysis of circular ring metamaterial absorber with the existing of copper lines. The structure is designed using lossy FR4 substrate with thin copper layers. The circular ring shape with copper lines is printed on the top surface of FR4 substrate, while at the bottom surface is printed with full copper ground plane. Parametric study is done to investigate the effect of copper lines on the resonance frequency. From the simulation, the circular ring metamaterial absorber with vertical copper lines can resonates at lower frequency, but this structure is polarized sensitive. This drawback can be improved by adding horizontal copper lines together with the vertical copper lines. The circular ring structure with vertical and horizontal copper lines is not only polarization insensitive, but it can works at wide operating angle of incident waves.     

A Class of Super Dense Stars Models Using Charged Analogues of Hajj-Boutros Type Relativistic Fluid Solutions

We present a spherically symmetric solution of the general relativistic field equations in isotropic coordinates for perfect charged fluid, compatible with a super dense star modeling. The solution is well behaved for all the values of Schwarzschild parameter u lying in the range 0 < u < 0.1727 for the maximum value of charge parameter K = 0.08163. The maximum mass of the fluid distribution is calculated by using stellar surface density as ρ _b = 4.6888×10¹⁴g cm^?3. Corresponding to K = 0.08 and u _max = 0.1732, the resulting well behaved solution has a maximum mass M = 0.9324M _⊙ and radius R = 8.00 and by assuming ρ _b = 2×10¹⁴g cm^?3 the solution results a stellar configuration with maximum mass M = 1.43M _⊙ and radius R _b = 12.25 km. The maximum mass is found increasing with increasing K up to 0.08. The well behaved class of relativistic stellar models obtained in this work might has astrophysical significance in the study of internal structure of compact star such as neutron star or self-bound strange quark star like Her X-1.     

Direct asymmetric Michael addition of ketones to chalcones catalyzed by a hydroxyphthalimide derived triazole–pyrrolidine

An efficient protocol for the enantioselective Michael additions of ketones to chalcones catalyzed by a hydroxyphthalimide linked triazole–pyrrolidine derivative has been developed. The corresponding products, 1,5-dicarbonyl compounds, were obtained in good yields with high levels of stereoselectivities under mild reaction conditions employing benzoic acid as an additive.     

The catalytic effect of Ag/CNTs nanocomposite on the ignition reaction of Mg/KNO3 pyrotechnic by determination of the kinetic triplet

Journal of Thermal Analysis and Calorimetry - The ignition reaction of Mg/KNO3 was improved with addition of Ag/CNTs nanocomposite as catalyst. The nanoparticles of Ag(0) was deposited on the...     

One-pot synthesis of 1, 3-thiazolidin-4-one using Bi(SCH2COOH)3 as catalyst

A catalytic multi-component reaction involving aromatic amine,aromatic aldehydes,mercapto acid as substrates and Bi（SCH₂COOH）₃ as catalyst under solvent free conditions,afforded thiazolidin-4-one in good yields.The efficiency of the catalyst was proved with a variety of substrates,ranging from electrondeficient to electron-rich aldehydes.     

Mutation scanning analysis of genetic variation within and among Echinococcus species: Implications and future prospects

Adult tapeworms of the genus Echinococcus (family Taeniidae) occur in the small intestines of carnivorous definitive hosts and are transmitted to particular intermediate mammalian hosts, in which they develop as fluid‐filled larvae (cysts) in internal organs (usually lung and liver), causing the disease echinococcosis. Echinococcus species are of major medical importance and also cause losses to the meat and livestock industries, mainly due to the condemnation of infected offal. Decisions regarding the treatment and control of echinococcosis rely on the accurate identification of species and population variants (strains). Conventional, phenetic methods for specific identification have some significant limitations. Despite advances in the development of molecular tools, there has been limited application of mutation scanning methods to species of Echinococcus. Here, we briefly review key genetic markers used for the identification of Echinococcus species and techniques for the analysis of genetic variation within and among populations, and the diagnosis of echinococcosis. We also discuss the benefits of utilizing mutation scanning approaches to elucidate the population genetics and epidemiology of Echinococcus species. These benefits are likely to become more evident following the complete characterization of the genomes of E. granulosus and E. multilocularis.