Efficient One-Pot Synthesis of Benzimidazoles Under Solvent-Free Conditions

A green, efficient method for the synthesis of various 2-aryl-benzimidazoles in the presence of hypervalent iodine as the oxidant at room temperature under solvent-free conditions is reported. The salient features of this method include mild conditions, short reaction times (3–5 min), excellent yields, and simple procedure.     

Synthesis and Mesogenic Properties of Novel Terthiophene Derivatives

To develop novel oligothiophene‐based liquid crystals involving hydrogen bonding, new terthiophene derivatives containing a stearylamide group, N,N′‐distearyl‐5,5″‐dicyano‐2,2′∶5′,2″‐terthiophene‐4,4″‐dicarboxamide (DNC₁₈DCN 3T) and N,N′‐distearyl‐5,5′‐dipropyl‐2,2′∶5′,2′‐terthiophene‐4,4″‐dicarboxamide (DNC₁₈ DP3T), were designed and synthesized, and their thermal behavior examined. Although DNC₁₈DP3T did not exhibit liquid crystallinity, DNC₁₈DCN3T was found to form smectic A phase.     

Facile One‐Pot Synthesis of Oxazolidin‐2‐ones from Phenyl 2‐Hydroxyalkyl Selenides

A novel, convenient, efficient, three‐step, one‐pot synthesis of 2‐oxazolidinones from phenyl 2‐hydroxyalkyl selenides was developed. Using this methodology, 2‐oxazolidinones are obtained in good yields (76–85%) by reaction of phenyl 2‐hydroxyalkyl selenides with benzoyl isocyanate and subsequent oxidation/cyclization, followed by hydrolysis with hydrochloric acid solution.     

Spectroscopic Investigation on Sonocatalytic Damage of BSA Molecules by FeIII Complexes with Binary Organic Acid Ligands Under Ultrasonic Irradiation

The interaction between bovine serum albumin (BSA) and Fe^III complexes with three binary organic acid (biorga) ligands, [Fe^III(oxa)(H₂O)₄]⁺ (oxa = oxalic acid), [Fe^III(pra)(H₂O)₄]⁺ (pra = propanedioic acid) and [Fe^III(sua)(H₂O)₄]⁺ (sua = succinic acid), as well as the sonocatalytic damage of BSA in the presence of these three Fe^III–biorga complexes under ultrasonic irradiation, were studied by UV–vis and fluorescence spectra. The experimental results show that the fluorescence quenching process of BSA caused by three Fe^III–biorga complexes are all static quenching and the corresponding quenching rate constants (K _q), equilibrium constants (K _A) and the binding site numbers (n) were calculated. The results reveal that, under ultrasonic irradiation, the BSA molecules were obviously damaged by these Fe^III–biorga complexes. In addition, the effects of several factors on the damage of BSA molecules were examined. The experimental results demonstrate that the damage degree of BSA increased with an increase of ultrasonic irradiation time, Fe^III–biorga complex concentration, and ionic strength. In comparison, [Fe^III(pra)(H₂O)₄]⁺ exhibited higher sonocatalytic activity than [Fe^III(oxa)(H₂O)₄]⁺ and [Fe^III(sua)(H₂O)₄]⁺. Finally, the extent of generation of $ \cdot {\text{O}}_{2}^{ - } $ · O 2 ? and ·OH during sonocatalytic processes was estimated. Perhaps, the results will be significant for promoting sonodynamic treatment (SDT) of tumors at the molecular level.     

Laboratory Studies of Depressurization with a High Concentration of Surfactant in Low-Permeability Reservoirs

To solve the problem of high pressure of water injection in low permeability reservoirs, a high concentration of surfactant system was developed in this article. With the solubilization of oil in aqueous surfactant solution as a criterion, a formula was screened from anionic and nonionic-anionic surfactants, and the optimal depressurized system was obtained as follows, 13.3% surfactant HEX +2.23% n-propanol +4.47% n-butanol, the solubilization capability being up to 0.66 g/g. This system had good salt tolerance, and it exhibited water external microemulsion in the range of of 1 to 200 g/L NaCl. Core flooding results show that this high concentration of surfactant system formed water external microemulsion with the residual oil in the core, reducing the displacement pressure over 35%. Meanwhile, the effects of concentration and injection volume on depressurization were also investigated. It is indicated that a good depressurization effect was achieved after injecting 1 pore volume of the system with the salt concentration of 100 g/L.     

Electrical Properties of a Highly Charged Cylindrical Particle in a Symmetric Electrolyte Solution

Based on the extended Langmuir's method, accurate analytic expressions for the electrical properties of cylindrical colloidal particle in a solution of symmetric electrolyte are derived from the nonlinear cylindrical Poisson-Boltzmann equation. Comparison is made with previous literature results. The present formulae have good agreement with literature values and are quite simple for practical use.     

Preparation and Characterization of Polymer‐Protected Pt@Pt/Au Core‐Shell Nanoparticles

Poly(N‐vinyl‐2‐pyrolidone) protected Pt‐core bimetallic Pt/Au‐shell (Pt@Pt/Au) nanoparticles were prepared by multi‐step reduction of HAuCl₄ and H₂PtCl₆ alternately by hydrogen adsorbed on platinum atom. Transmission electronic microscopy (TEM) and x‐ray diffraction (XRD) were used to characterize Pt@Pt/Au nanoparticles. The structure of the shell of the nanoparticles seems to be the Au‐Pt solid solution.     

An Approximate Expression for the Degree of Counterion Binding of Dressed Micelles

A simple formula for calculating the degree of counterion binding of dressed micelles is presented. This approximate expression for the spherical micelle is derived from the extending Langmuir's method in the case of high surface potentials. It works quite well for the estimation of the degree of counterion binding of micelles. The simple form is very convenient for practical use.     

Electrical Properties of Cylindrical Reverse Micelle

In this article, accurate analytic expressions of the surface charge density/surface potential and adsorption excesses for cylindrical reverse micelle in a solution of symmetric electrolyte are derived from the nonlinear cylindrical Poisson–Boltzmann equation. These expressions are in good agreement with numerical values and Van Aken's results for cylindrical reverse micelle with high surface potentials and large κa.     

Adsorption kinetics and equilibrium modeling of cesium on copper ferrocyanide

The copper ferrocyanide (CuFC) prepared in this study was characterized using X-ray diffraction and scanning election microscopy. The distribution of particle sizes of the CuFC suspension was determined. The adsorption kinetics data were evaluated for an intraparticle diffusion model, a pseudo-first order model and a pseudo-second order model at temperatures of 288, 298 and 308 K, respectively. It was found that the adsorption process of Cs⁺ on CuFC was best described by a pseudo-second order kinetic model, with a correlation coefficient (R ²) equal to 1.000, and the adsorption rate constant increased with increasing temperature. This result indicated that chemisorptions took place during the adsorption process. The adsorption equilibrium data fit well to the Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherm models. The mean adsorption energy (E) between 11 and 13 kJ/mol at different temperatures indicated that ion exchange was the main mechanism during the adsorption process. Thermodynamic parameters were also evaluated during the adsorption. The values of the standard Gibbs free energy change (ΔG ^o) and standard enthalpy change (ΔH ^o) suggested that the adsorption was a spontaneous and endothermic process. The distribution coefficient (K _d) was more than 2.94 × 10⁶ mL/g when the pH of solution was between 2.6 and 10.9, and the initial Cs⁺ concentration was 100 μg/L. The existence of K⁺ and Na⁺ did not affect the adsorption of Cs⁺ on CuFC when the concentration of K⁺ and Na⁺ in the solution was below 20 and 1,000 mg/L, respectively.