Facile one-pot synthesis of novel dicyanoanilines fused to tetrahydro-4H-thiopyran-4-one ring via Et3N/H2O catalyzed pseudo four-component reaction

A facile procedure is developed for one-pot synthesis of a new group of dicyanoanilines. Tetrahydro-4H-thiopyran-4-one, 1, undergoes a pseudo four-component reaction with various aldehydes bearing different groups and two equivalents of malononitrile in aqueous media in the presence of triethylamine (Et₃N). As a result, novel thiopyran-fused dicyanoanilines 4 are formed efficiently in the reaction mixtures in 90–97% yield within 9–12?h mixing at 40°C. Due to the polarity of the medium, products precipitate in the mixture spontaneously allowing for easy purification by recrystallization avoiding cumbersome chromatographic separations. Characterization of the products was performed by spectroscopic methods and, in one case, was further supported by X-ray crystallographic experiments.     

A comparative study of CO<Subscript>2</Subscript> and CH<Subscript>4</Subscript> adsorption using activated carbon prepared from pine cone by phosphoric acid activation

Adsorption of pure carbon dioxide and methane was examined on activated carbon prepared from pine cone by chemical activation with H₃PO₄ to determine the potential for the separation of CO₂ from CH₄. The prepared adsorbent was characterized by N₂ adsorption-desorption, elemental analysis, FTIR, SEM and TEM. The equilibrium adsorption of CO₂ and CH₄ on AC was determined at 298, 308 and 318 K and pressure range of 1–16 bar. The experimental data of both gases were analyzed using Langmuir and Freundlich models. For CO₂, the Langmuir isotherm presented a perfect fit, whereas the isotherm of CH₄ was well described by Freundlich model. The selectivity of CO₂ over CH₄ by AC (CO₂: CH₄=50: 50, 298K, 5 bar), predicted by ideal adsorbed solution theory (IAST) model, was achieved at 1.68. These data demonstrated that pine cone-based AC prepared in this study can be successfully used in separation of CO₂ from CH₄.     

Synthesis of Chemically Cross-Linked Hydroxypropyl Methyl Cellulose Hydrogels and their Application in Controlled Release of 5-Amino Salicylic Acid

The objective of this study was to achieve the colon-specific delivery of an anti-ulcerative colitis drug using hydroxypropyl methyl cellulose (HPMC) hydrogels. HPMC hydrogels containing poly ethylene glycol (PEG) as cross-links have been prepared by reacting HPMC sodium salt with polyethylene glycol dichloride.

The effect of cross-linking agent on swelling behavior of HPMC-PEG hydrogels, were investigated. Swelling parameters such as equilibrium degree of swelling, swelling ratio and network parameter such as molecular mass between cross-links (M_c) were determined. The cross-linking concentrations were 0.5%, 1%, 1.5%, and 2% (based on weight of HPMC). The equilibrium swelling ratio (Q) of cross-linked HPMC hydrogels increases from 13.2 to 27.1 as the cross-linker percentage increases from 0.5% to 2%. 5-Aminosalicylic acid (5-ASA) was used as a model of an anti-inflammatory drug. Cross-linked HPMC hydrogels were found to be a promising drug delivery system for the drugs to be delivered to the colon.     

Thermosensitive nanoparticles prepared from poly(N‐isopropylacrylamide‐acrylamide‐vinilpyrrolidone) and its blend with poly(lactide‐co‐glycolide) for efficient drug delivery system

Temperature‐responsive polymers have become increasingly attractive as carrier for the injectable drug delivery systems. In the present work, we have studied the preparation of poly(N‐isopropylacrylamide‐acrylamide‐vinilpyrrolidone) (NIPAAm‐AAm‐VP terpolymer) nanoparticulated terpolymer and its blend with poly(lactide‐co‐glycolide, PLGA; molar ratio of lactide/glycolid 1/3). Thermosensitive terpolymer, poly(NIPAAm‐AAm‐VP) was prepared by free‐radical polymerization in aqueous solution. The nanoparticles of poly(NIPAAm‐AAm‐VP) and its blend with PLGA containing naltrexone were prepared using the evaporation and w/o emulsion‐solvent evaporation methods, respectively. Nanoparticles prepared from terpolymer‐PLGA blend at low polymer concentration (5%) shows larger particle size (>300 nm) and higher drug content%. Various types of nanoparticles showed a burst release of less than 10% after 24 h . The results suggest that by regulating different variables, desired release profiles of naltrexone can be achieved using a blend of PLGA‐poly(NIPAAm‐AAm‐VP) nanoparticulate system. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Fouling of WO3 nanoparticle-incorporated PSf membranes in ultrafiltration of landfill leachate and dairy a combined wastewaters: An investigation using model

As fouling has always been a major drawback of membrane technology, qualitative and quantitative understanding of membrane fouling mechanisms therefore becomes vital in order to help push membrane separation technologies forward. In this study, firstly, self-cleaning Polysulfone(PSf) membranes were synthesized by incorporation of WO_3nanoparticles(0–2 wt%) and subsequent UV irradiation for efficient ultrafiltration(UF)of landfill leachate and dairy wastewater. The membrane surface properties were characterized by scanning electron microscopy(SEM) and contact angle analysis. It was found that UV-irradiated membranes exhibited higher percent COD removals due to the hydrophilicity and photocatalytic properties of nano-WO_3. Subsequently, in order to analyze the fouling behavior of the membranes, a set of experimental data from cross-flow ultrafiltration of municipal landfill leachate and industrial dairy wastewater at 25 °C was obtained. A new model of membrane fouling was proposed based on a resistance in series concept and was fitted well with all experimental data sets.Almost all relative errors of prediction provided by the proposed model were less than 2.5%. In addition, it was revealed that this newly-developed model exhibited smooth transition between the common successive twostep pore blockage-cake filtration phenomena and thus eliminates the need to use separate equations for different mechanisms.     

Synthesis of chemically cross-linked hydroxypropyl methyl cellulose hydrogels and their application in controlled release of 5-amino salicylic acid

The objective of this study was to achieve the colon-specific delivery of an anti-ulcerative colitis drug using hydroxypropyl methyl cellulose (HPMC) hydrogels. HPMC hydrogels containing poly ethylene glycol (PEG) as cross-links have been prepared by reacting HPMC sodium salt with polyethylene glycol dichloride.

The effect of cross-linking agent on swelling behavior of HPMC-PEG hydrogels, were investigated. Swelling parameters such as equilibrium degree of swelling, swelling ratio and network parameter such as molecular mass between cross-links (M_c) were determined. The cross-linking concentrations were 0.5%, 1%, 1.5%, and 2% (based on weight of HPMC). The equilibrium swelling ratio (Q) of cross-linked HPMC hydrogels increases from 13.2 to 27.1 as the cross-linker percentage increases from 0.5% to 2%. 5-Aminosalicylic acid (5-ASA) was used as a model of an anti-inflammatory drug. Cross-linked HPMC hydrogels were found to be a promising drug delivery system for the drugs to be delivered to the colon.     

Quantum dots: synthesis, bioapplications, and toxicity

Ferrite nanoparticles of basic composition Ni_0.7-x Zn _x Cu_0.3Fe₂O₄ (0.0 ?? x ?? 0.2, x = 0.05) were synthesized through auto-combustion method and were characterized for structural properties using X-ray diffraction [XRD], scanning electron microscopy, transmission electron microscopy, and Fourier transform infrared spectroscopy [FT-IR]. XRD analysis of the powder samples sintered at 600°C for 4 h showed the cubic spinel structure for ferrites with a narrow size distribution from 28 to 32 nm. FT-IR showed two absorption bands (v ₁ and v ₂) that are attributed to the stretching vibration of tetrahedral and octahedral sites. The effect of Zn doping on the electrical properties was studied using dielectric and impedance spectroscopy at room temperature. The dielectric parameters (??', ????, tan??, and ?? _ac) show their maximum value for 10% Zn doping. The dielectric constant and loss tangent decrease with increasing frequency of the applied field. The results are explained in the light of dielectric polarization which is similar to the conduction phenomenon. The complex impedance shows that the conduction process in grown nanoparticles takes place predominantly through grain boundary volume. PACS: 75.50.Gg; 78.20; 77.22.Gm.     

DMSO Chemically Alters Cell Membranes to Slow Exocytosis and Increase the Fraction of Partial Transmitter Released

Dimethyl sulfoxide (DMSO) is frequently used as a solvent in biological studies and as a vehicle for drug therapy; but the side effects of DMSO, especially on the cell environment, are not well understood, and controls with DMSO are not neutral at higher concentrations. Herein, electrochemical measurement techniques are applied to show that DMSO increases exocytotic neurotransmitter release, while leaving vesicular contents unchanged. In addition, the kinetics of release from DMSO‐treated cells are faster than that of untreated ones. The results suggest that DMSO has a significant influence on the chemistry of the cell membrane, leading to alteration of exocytosis. A speculative chemical mechanism of the effect on the fusion pore during exocytosis is presented.