Effect of γ-irradiation on optical and chemical properties of CR-39 polymer

CR-39 polymer samples were irradiated with γ-irradiation up to dose ranging from 500 to 2000 kGy. The virgin and γ-irradiated polymer samples were investigated using UV–visible spectroscopy and Fourier transform infrared (FTIR) spectroscopy. In the present work, the Urbach energy was calculated using the Urbach edge method. Also, the direct and indirect energy band gaps in virgin and γ-irradiated CR-39 polymer samples were calculated. The values of indirect energy band gap were found to be lower than the corresponding values of direct energy band gap. The decrease in the optical energy band gap with increasing γ-irradiation dose was discussed on the basis of γ-irradiation-induced modifications in CR-39 polymer. The correlation between optical energy band gap and the number of carbon atoms in a cluster with modified Tauc's equation was also discussed. The FTIR spectra show considerable changes due to γ-irradiation, indicating that the detector is not chemically stable.     

Bridged amine-functionalized mesoporous organosilica materials from 1,2-bis(triethoxysilyl)ethane and bis[(3-trimethoxysilyl)propyl]amine

Amine-functionalized, organic/inorganic hybrid mesostructured organosilica (BAFMO) materials have been synthesized and characterized from two bridged silsesquioxane precursors, 1,2-bis(triethoxysilyl)ethane (BTESE) and bis[(3-trimethoxysilyl)propyl]amine (BTMSPA). Mole ratios of BTESE ranged from 0.05, 0.10, 0.125, to 0.175. The synthetic pathway involves employing cetyltrimethylammonium bromide as a template under basic conditions at room temperature. X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies revealed that the resultant BAFMO materials possess mesocopically ordered, hexagonal symmetries and well-defined morphologies. However, the order was decreased as the amount of BTMSPA increased, in terms of the d₁₀₀ spacings and the unit cell parameters on XRD as well as the TEM images. N₂ gas sorption experiments showed a gradual decrease in both the surface area, from 1075 to 688 m²/g, and the pore volume, from 2.08 to 0.55 cm³/g, on increasing the amount of BTMSPA. The organic functionalization was successfully determined by Fourier-transform infrared and ¹³C CP MAS NMR spectroscopy. X-ray photoelectron spectroscopy and elemental analysis results also confirmed the presence of Si-C bond as well as amine functionalities in the solvent-extracted mesoporous organosilica materials.     

A Conductive polylactic acid/polyaniline porous scaffold via freeze extraction for potential biomedical applications

This paper reports for the first time a simple yet effective method for fabricating a conductive and highly porous scaffold material made up of polylactic acid (PLA) and conducting polyaniline (PANI). The electrical percolation state was successfully obtained at 3 wt% of PANI inclusions and reached a conductivity level of useable tissue engineering applications at 4 wt%. In addition, preliminary bioactivity test results indicated that the protonating agent could form a chelate at the scaffold surface leading to good in-vitro apatite forming ability during biomimetic immersion. This new conductive scaffold has potential as a suitable biomedical material that requires electrical conductivity.     

Synthesis of substituted indoles using continuous flow micro reactors

Continuous flow micro fluidic devices for organic synthesis (‘micro reactors’) are becoming established in a number of facets of modern applied chemistry. As part of a concurrent research project with a pharmaceutical company for generation of materials of pharmaceutical interest within continuous flow environments, we present here, for the first time a series of indoles that have been produced within micro reactor systems. We have developed three different approaches to the synthesis, which are compared with traditional batch synthesis as well as each other in terms of ease of optimization, chemical suitability and versatility, and implications as to throughput. Typical throughputs of approach 1 (simulated classical synthesis) were in the region of 2 mgh⁻¹ of indoles such as tetrahydrocarbazole and cyclopentaindole. The second approach (based on Elk's modification of Fischer indole synthesis) gave throughputs of 5.7-8.9 mgh⁻¹ and the final approach (using heterocatalytic flow reactors) gave the highest throughputs of 12.7-20.1 mgh⁻¹. All throughputs are per single channel reactor system (i.e., one single reactor set up), and the latter two approaches produce viable output quantities for the syntheses of radiolabelled materials (where typically minute amounts of high purity materials are required from a rapid and safe production environment).     

Nitrate, ascorbic acid, mineral and antioxidant activities of Cosmos caudatus in response to organic and mineral-based fertilizer rates

The source and quantity of nutrients available to plants can affect the quality of leafy herbs. A study was conducted to compare quality of Cosmos caudatus in response to rates of organic and mineral-based fertilizers. Organic based fertilizer GOBI (8% N:8% P?O?:8% K?O) and inorganic fertilizer (15% N, 15% P?O?, 15% K?O) were evaluated based on N element rates at 0, 30, 60, 90, 120 kg h?1. Application of organic based fertilizer reduced nitrate, improved vitamin C, antioxidant activity as well as nitrogen and calcium nutrients content. Antioxidant activity and chlorophyll content were significantly higher with increased fertilizer application. Fertilization appeared to enhance vitamin C content, however for the maximum ascorbic acid content, regardless of fertilizer sources, plants did not require high amounts of fertilizer.     

Effect of wall compliance on compressible fluid transport induced by a surface acoustic wave in a microchannel

Effects of complaint wall properties on the flow of a Newtonian viscous compressible fluid has been studied when the wave propagating (surface acoustic wave, SAW) along the walls in a confined parallel‐plane microchannel is conducted by considering the slip velocity. A perturbation technique has been employed to analyze the problem where the amplitude ratio (wave amplitude/half width of channel) is chosen as a parameter. In the second order approximation, the net axial velocity is calculated for various values of the fluid parameters and wall parameters. The phenomenon of the “mean flow reversal” is found to exist both at the center and at the boundaries of the channel. The effect of damping force, wall tension, and compressibility parameter on the mean axial velocity and reversal flow has been investigated, also the critical values of the tension are calculated for the pertinent flow parameters. © 2009 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 27: 621–636, 2011 Keywords:     

Radiation synthesis of acrylic acid/polyethyleneimine interpenetrating polymer networks (IPNs) hydrogels and its application as a carrier of atorvastatin drug for controlling cholesterol

Gamma irradiation was used to form interpenetrating polymer networks structure (IPNs) hydrogels based on different ratios of acrylic acid monomer (AAc) and polyethyleneimine (PEI). The property-behavior was characterized by IR spectroscopy, gel content, thermogravimetric analysis (TGA) and swelling in water at room temperature and different pH values. The AAc/PEI hydrogels were used as a carrier for atorvastatin drug, in which the uptake-release character was studied. The results showed that the gel content of AAc/PEI hydrogels decreased greatly with increasing the ratio of PEI in the initial feeding solution. The AAc/PEI hydrogels displayed pH-sensitive character. The drug uptake-release study indicated that AAc/PEI hydrogels possessed controlled release behavior and that the release process depends on pH. In this respect, the release of atorvastatin drug was significant in acidic medium.     

Synthesis and Characterization of Novel Amorphous Hybrid Silica Materials

Novel amorphous organic-inorganic hybrid silica materials have been prepared by the conventional sol-gel reaction of bis(gamma-trimethoxysilyl)propylamine (TMSPA) and tetraethyl orthosilicate (TEOS) in the presence of cetyltrimethylammonium bromide (CTABr) as a structure directing agent. The gelation of the hybrid silica gels took place faster as the TMSPA composition was higher. Infrared Spectroscopy (IR), Thermogravimetric Analysis (TGA), X-Ray Diffraction (XRD), and Scanning electron microscope (SEM) were used to characterize various hybrid materials. Nitrogen adsorption desorption isotherms at 77 K were used to determine the surface area, and average pore size. The hybrids were composed of macropores and a small amount of micropores. According to SEM photographs, the hybrids were composed of quite uniform aggregate of spherical particles with ca. 60 nm in diameter.     

Effect of anions on the dissolution of Al in acid solutions

The effect of Cl^?, Br^?, I^?, ClO₄^?, NO₃^?, HSO₄^?, HCrO₄^? and H₂PO₄^? on the of Al in 2 M HCl is studied by the thermometric method. Three sets of experiments are carried out, which allow the variation of the concentration of the various species in a programmed manner. Dissolution promotion is noted in solutions to which HCl, HBr and H₂CrO₄ are added. The way of action of each of these anions is discussed. Additions of HI, HClO₄, H₂SO₄ and H₃PO₄, on the other hand, first retard and later enhance the dissolution of Al in 2 M HCl, as their concentration in solution is increased. This is related to anion adsorption, which is counterbalanced by increase in acidity. HNO₃ differs from the other tested acids in causing only dissolution retardation. Experiments in which LaCl₃ is added to the test solution indicate that the NO₃^? is adsorbed as such on Al₂O₃. The ability of the various anions to retard the dissolution of Al in 2 M HCl decreases in the succession: NO₃^? (strong)>I^?>HSO₄^?>H₂PO₄^?>Br^?, ClO₄^? (weak)     

Palladium mediated synthesis of isoindolinones and isoquinolinones

The palladium-catalyzed reactions of 2-iodo-N-substituted benzamides 5-10 with acrylic esters 11-14 led to N-substituted-3-alkylisoindolinone esters 15-22 in good yields. The esters of isoindolinones 15-22 underwent hydrolysis reactions yielding the N-aryl-1,2,3,4-tetrahydro-1-oxoisoquinoline-3-carboxylic acid 26-31 in good yields.