Accelerated weathering of unbleached and bleached Kraft wood fibre reinforced polypropylene composites

In this paper, combined moisture/ultraviolet (UV) weathering performance of unbleached and bleached Kraft wood fibre reinforced polypropylene (PP) composites was studied. Composites containing 40 wt% fibre with 3 wt% of a maleated polypropylene (MAPP) coupling agent were fabricated using extrusion followed by injection moulding. Composite mechanical properties were evaluated, before and after accelerated weathering for 1000 h, by tensile and impact testing. Differential scanning calorimetry (DSC), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) were also carried out to assess the changes occurring during accelerated weathering. Bleached fibre composites initially showed higher tensile and impact strengths, as well as higher thermal stability and greater crystallinity. During accelerated weathering, both unbleached and bleached fibre composites reduced tensile strength (TS) and Young's modulus (YM), with the extent of the reduction found to be similar for both unbleached and bleached fibre composites. Evidence supported that the reduction of TS and YM was due to PP chain scission, degradation of lignin and reduced fibre-matrix interfacial bonding.     

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.     

Application of chemometric approach for development and validation of high performance liquid chromatography method for estimation of ropinirole hydrochloride

A systematic Quality by Design approach was employed for developing an isocratic reversed‐phase liquid chromatographic technique for the estimation of ropinirole hydrochloride in bulk drug and pharmaceutical formulations. LiChrospher RP 18‐5 Endcapped column (25 cm × 4.6 mm id) at ambient temperature (25 ± 2°C) was used for the chromatographic separation of the drug. The screening of factors influencing chromatographic separation of the active pharmaceutical ingredient was performed employing fractional factorial design to identify the influential factors. Optimization of the selected factors was carried out using central composite design for selecting the optimum chomatographic conditions. The mobile phase employed was constituted of Solvent A/Solvent B (65:35 v/v) (Solvent A [methanol/0.05 M ammonium acetate buffer, pH 7, 80:20 v/v] and Solvent B [high performance liquid chromatography grade water]) and used at 0.6 mL/min flow rate, while UV detection was performed at 250 nm. Linearity was achieved in the drug concentration range 5–100 µg/mL (R² = 0.9998) with limits of detection and quantification of 1.02 and 3.09 µg/mL, respectively. Method validation was performed as per ICH guidelines followed by forced degradation studies, which indicated good specificity of the developed method for detecting ropinirole hydrochloride and its possible degradation products in the bulk drug and pharmaceutical formulations.     

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.     

Common fixed points of fuzzy maps

We prove common fixed point theorems for a pair of fuzzy mappings satisfying Edelstein, Alber and Guerr-Delabriere type contractive conditions in a metric linear space.     

Random solution of random multivalued operator inclusions

Sufficient conditions for a random solution of random operator inclusions involving random multivalued operators satisfying a general contractive condition are obtained. A simultaneous random solution of the system of two random operator inclusions is also derived.     

Study on phase stabilization and electrical performance of BICO0.20−xNIxVOX solid electrolyte

BICO_0.20?xNI_xVOX solid electrolyte in the composition range 0 ≤ x ≤ 0.20 was synthesized by standard solid-state reactions. The influence of Ni substitution for Co on the relationship between the phase stabilization and electrical performance was investigated by means of X-ray powder diffraction (XRPD), differential thermal analysis (DTA) and AC impedance spectroscopy. The highly conductive γ′-phase was effectively stabilized at room temperature for compositions with x ≥ 0.13 whose thermal stability increases with Ni content. On the other hand, complex plane plots of impedance suggested a major contribution of polycrystalline grain interiors to the overall electrical conductivity and the fastest oxygen-vacancy diffusion in the perovskite vanadate layers at x = 0.13. The dielectric permittivity measurements revealed the fact that suppression of the ferroelectric transition is compositionally dependent. However, a maximum ionic conductivity at lower temperatures (～2.56 × 10^?4 S cm^?1 at 300 °C) was observed for the composition with x = 0.13.     

Structural and electrical properties of hexavalent-substituted BIMEVOX synthesized by a microwave-assisted route

The microwave (MW)-assisted solid synthesis route was employed to prepare a new Aurivillius-type compound with the general formula Bi₂Cr _x V_1?x O_5.5+x?δ; 0≤x≤0.20 (BICRVOX). This novel synthesis method revealed that polycrystalline products of the BICRVOX system can effectively be obtained after being irradiated for 25 min rather than for the many hours of high-temperature heating needed in other conventional routes. The phase structure of MW-prepared samples was characterized by comparison with those obtained from the conventional solid-state reaction, using powder X-ray diffraction, FT-IR and differential thermal analysis techniques. Importantly, the substitution of Cr(VI) for V(V) in the parent compound resulted in stabilization of only the α - and β -phases. AC impedance spectroscopy confirmed that the MW-prepared samples possess slightly lower oxide-ion performance compared with the conventionally-prepared ones; it did, however, evidence the significant role of powerful dielectric heating of MWs in lowering the charge carrier accumulation.