Cyclic transport of Fe3+ As H[FeCl4] and H[FeBr4] through a dibutyl ether-benzene membrane

Cyclic transport of Fe³⁺ as H[FeX₄], where X is Cl or Br, across solvent-type liquid membranes has been demonstrated. H[FeCl₄] was transported from HCl into HBr across a dibutyl ether—benzene mixture. In HBr the transported species reacted to H[FeBr₄], which moved out to the HCl side against the concentration gradient of Fe³⁺. On the HCl side it was reconverted into H[FeCl₄]. This continued till equilibrium was achieved. Likewise, Fe³⁺, present as H[FeBr₄] in HBr, migrated from HBr into HCl and then back to HBr across the same membrane.     

Studies with model membranes: Part IX. Evaluation of the thermodynamic effective fixed charge density and permselectivity of parchment supported cobalt tungstate and mercuric chromate membranes

Thermodynamic effective fixed charge densities of cobalt tungstate and mercuric chromate parchment supported membranes were evaluated by a number of methods particularly those of Teorell-Meyer-Sievers [19]. Altug and Hair [23] and the most recent one of Kobatake et al. [24, 27] based on the thermodynamics of irreversible processes. The value of the permselectivity was also obtained for the two membranes based on Kobatake et al.'s procedure. Kobatake et al.' equation was used under two limiting conditions of concentration of electrolyte solution, namely (1) in the concentrated range, and (2) in the dilute range. The charge densities obtained under these conditions namely θ_c and θ_d were found to differ (θ_c=1/2θ_d), but it was interesting to note that θ_c values were more closer to those of the TMS values. The theoretical predictions for membrane potential using Kobatake et al.'s equation are borne out quite satisfactorily by our experimental results for both membranes.     

Effect of core-corona plasma structure on seeding of instabilities in wire array Z pinches

We present the first measurements by x-ray radiography of the development of instabilities during the implosion phase of wire array Z pinches. The seeding of perturbations on the dense core of each wire is provided by nonuniform sweeping of the low-density coronal plasma from the cores by the global JxB force. The spatial scale of these perturbations ( approximately 0.5 mm for Al and approximately 0.25 mm for W) is determined by the size of the wire cores ( approximately 0.25 mm for Al and approximately 0.1 mm for W). A qualitative change in implosion dynamics, with transition to 0D-like trajectory, was observed in Al arrays when the ratio of interwire gap to wire core size was decreased to approximately 3.     

Effect of the plasma density scale length on the direction of fast electrons in relativistic laser-solid interactions

The angular distribution of bremsstrahlung gamma rays produced by fast electrons accelerated in relativistic laser-solid interaction has been studied by photoneutron activation in copper. We show that the gamma-ray beam moves from the target normal to the direction of the k(laser) vector as the scale length is increased. Similar behavior is found also in 2D particle-in-cell simulations.     

Encapsulation of N-heterocyclic carbene–gold (I) catalysts within magnetic core/shell silica gels: A reusable alkyne hydration catalyst

In this study, N-heterocyclic carbene–Au(I) complex, chloro[1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene]gold (I), was successfully encapsulated within mesopores of a magnetic core/shell (γ-Fe₂O₃@SiO₂) silica gel through post-pore-size reduction by silylation reactions The post-reduction of the pore size not only minimizes the catalyst leaching during the alkyne hydration reactions but also eliminates any need for covalent modification of the catalyst or support surface. The resulting catalyst exhibits high activity in hydration reactions of various alkynes even under low catalytic loadings. The catalyst can be easily recycled from the reaction mixture using a magnet and can be reused in alkyne hydration reactions up to six times with only 52. wt% Au leaching.     

Study on phase stability and oxide ion conductivity in the BIAGVOX system

A novel oxide ion conductor, BIAGVOX formulated as Bi₄Ag_xV_2?xO_11?(2x)?δ is obtained by substituting a fraction (x) of V⁵⁺ by Ag⁺ in Bi₄V₂O₁₁ samples of the BIAGVOX system in the composition range, 0.05≤x≤0.30 were synthesized using the standard solid-state reaction. XRPD, FT-IR, DTA and AC impedance spectroscopy were used for the investigation of the correlation between the structural phase stability and oxide ion performance of the BIAGVOX materials. It has been found that orthorhombic, β, and incommensurate tetragonal, γ′ were stabilized at room temperature for compositions with x≤0.15 and x≥0.20, respectively. The enthalpy of β→γ and γ→γ transition exhibited a general drop with increasing Ag content and a minimum transition temperature was observed for x=0.20. However, the oxide ion conductivity at lower temperatures remarkably increased in composition stability ranges of β- and γ-phase, while a maximum conductivity was reported for the high temperature γ-phase at x=0.15. However, the low temperature conductivity, σ₃₀₀°c measured for x=0.30 was found to be comparable with the maximum ionic conductivity of the BICUVOX system reported for x=0.20 at the same temperature.     

QbD‐oriented development and validation of a bioanalytical method for nevirapine with enhanced liquid–liquid extraction and chromatographic separation

The present studies describe the systematic quality by design (QbD)‐oriented development and validation of a simple, rapid, sensitive and cost‐effective reversed‐phase HPLC bioanalytical method for nevirapine in rat plasma. Chromatographic separation was carried out on a C₁₈ column using isocratic 68:9:23% v/v elution of methanol, acetonitrile and water (pH 3, adjusted by orthophosphoric acid) at a flow rate of 1.0 mL/min using UV detection at 230 nm. A Box–Behnken design was applied for chromatographic method optimization taking mobile phase ratio, pH and flow rate as the critical method parameters (CMPs) from screening studies. Peak area, retention time, theoretical plates and peak tailing were measured as the critical analytical attributes (CAAs). Further, the bioanalytical liquid–liquid extraction process was optimized using an optimal design by selecting extraction time, centrifugation speed and temperature as the CMPs for percentage recovery of nevirapine as the CAA. The search for an optimum chromatographic solution was conducted through numerical desirability function. Validation studies performed as per the US Food and Drug Administration requirements revealed results within the acceptance limit. In a nutshell, the studies successfully demonstrate the utility of analytical QbD approach for the rational development of a bioanalytical method with enhanced chromatographic separation and recovery of nevirapine in rat plasma. Copyright © 2015 John Wiley & Sons, Ltd.     

A New Metal-Chelated Cryogel for Reversible Immobilization of Urease

Poly(2-hydroxyethyl methacrylate-co-glycidyl methacrylate) [poly(HEMA-GMA)] cryogel was synthesized by cryopolymerization technique at frozen temperature. Iminodiacetic acid (IDA) was then attached covalently to the cryogel as a chelating agent. Then, poly(HEMA-GMA)-IDA cryogel was chelated with Ni(II) ions and this novel metal affinity support was used for adsorption of urease from its aqueous solution. Urease adsorption experiments were carried out in a continuous system by using a peristaltic pump. Maximum urease adsorption onto poly(HEMA-GMA)-IDA-Ni(II) cryogel was found to be 11.30 mg/g cryogel at pH 5.0 acetate buffer and in 25 °C medium temperature. Urease adsorption capacity decreased with increasing ionic strength and increasing chromatographic flow rate. Adsorption kinetics of urease onto poly(HEMA-GMA)-IDA-Ni(II) cryogel was also investigated and it was found that Langmuir adsorption model is applicable for this adsorption study. This novel immobilized metal affinity chromatography support was used 10 times without any decrease at their adsorption capacity. It was also observed that urease enzyme was repeatedly adsorbed and desorbed without significant lost in enzymatic activity.     

Synthesis and antimicrobial activity of new 2-((1-furan-2-yl)ethylidene)hydrazono)-4-phenylthiazol-3(2H)-amine derivatives and their schiff bases with 4-nitrobenzaldehyde

Abstract

A new series of 2-((1-furan-2-yl)ethylidene)hydrazono)-4-substitutedphenylthiazol-3(2H)-amines (2a–2o) and their Schiff bases (3a–3o) from 4-nitrobenzaldehyde were synthesized. The chemical structures of all the synthesized compounds were confirmed by their IR, ¹H-NMR, ¹³C-NMR spectroscopy and mass spectrometry. They were screened for their antimicrobial and antifungal activities. Additionally, in vitro cytotoxic acivity of the most active antifungal compound (3o) and ketoconazole was determined in NIH/3T3 cells by MTT assay. Compound 2i (4-{3-Amino-2-[(1-(furan-2-yl)ethylidene)hydrazono]-2,3-dihydrothiazol-4-yl}phenol) showed the greatest antifungal activity among the newly synthesized derivatives. Schiff bases (3c-3n) displayed an undeniable fungicidal action against Candida parapsilosis ATCC 22019 as intense as the reference ketoconazole. In addition, the most active Schiff base 3o (2-[(1-(Furan-2-yl)ethylidene)hydrazono]-N-(4-nitrobenzylidene)-4-(2,3,4-trichloro phenyl)thiazol-3(2H)-amine) showed the highest antifungal activity against both Candida krusei ATCC 6258 and Candida parapsilosis ATCC 22019, and was as potent as ketoconazole. Moreover, compound 3o was found to be non-cytotoxic against NIH/3T3 cells.     

Study of phase transition in ZrO2 doped with Pb3O4

Electrical conductivity of ZrO₂ doped with Pb₃O₄ has been measured at different temperatures for different molar ratios (x=0, 0.01, 0.02, 0.03, 0.04, 0.05 and 0.06). The conductivity increases due to migration of vacancies, created by doping. The conductivity increases with increase in temperature till 180 °C and thereby decreases due to collapse of the fluorite framework. A second rise in conductivity at higher temperatures beyond 500-618 °C is due to phase transition of ZrO₂. DTA and X-ray powder diffraction were carried out for confirming doping effect and transition in ZrO₂.The addition of Pb₃O₄ to ZrO₂ shifted the phase transition of ZrO₂ due to the interaction between Pb₃O₄ and ZrO₂.