Properties of tetra-N-glycidyl-4,4′-diamino diphenyl methane (TGDDM) cured thick films

Thick films of tetra-N-glycidyl epoxy resin of p,p′-diaminodiphenyl methane (TGDDM) were prepared using p,p′-diaminodiphenyl methane (DDM), p,p′-diaminodiphenyl sulfone (DDS) and diethylene triamine (DETA) as curing agent with or without the epoxy fortifiers PGEHA and VCDRC (at 20 phr level). These thick films were used to evaluate various physical, mechanical, chemical resistant and dielectric properties.     

Isotopic effects on non-linearity, molecular radius and intermolecular free length

Computation of non-linearity parameter (B/A), molecular radius (r _m) and intermolecular free length (L _f) for H₂O, C₆H₆, C₆H₁₂, CH₃OH, C₂H₅OH and their deuterium-substituted compounds have been carried out at four different temperatures, viz., 293.15, 303.15, 313.15 and 323.15 K. The aim of the investigation is an attempt to study the isotopic effects on the non-linearity parameter and the physicochemical properties of the liquids, which in turn has been used to study their effect on the intermolecular interactions produced thereof.     

Hypochlorite‐Mediated Modulation of Photoinduced Electron Transfer in a Phenothiazine–Boron dipyrromethene Electron Donor–Acceptor Dyad: A Highly Water Soluble “Turn‐On” Fluorescent Probe for Hypochlorite

A highly water‐soluble phenothiazine (PTZ)–boron dipyrromethene (BODIPY)‐based electron donor–acceptor dyad ( WS‐Probe ), which contains BODIPY as the signaling antennae and PTZ as the OCl^? reactive group, was designed and used as a fluorescent chemosensor for the detection of OCl^?. Upon addition of incremental amounts of NaOCl, the quenched fluorescence of WS‐Probe was enhanced drastically, which indicated the inhibition of reductive photoinduced electron transfer (PET) from PTZ to ¹BODIPY*; the detection limit was calculated to be 26.7 nm . Selectivity studies with various reactive oxygen species, cations, and anions revealed that WS‐Probe was able to detect OCl^? selectively. Steady‐state fluorescence studies performed at varied pH suggested that WS‐Probe can detect NaOCl and exhibits maximum fluorescence in the pH range of 7 to 8, similar to physiological conditions. ESI‐MS analysis and ¹H NMR spectroscopy titrations showed the formation of sulfoxide as the major oxidized product upon addition of hypochlorite. More interestingly, when WS‐Probe was treated with real water samples, the fluorescence response was clearly visible with tap water and disinfectant, which indicated the presence of OCl^? in these samples. The in vitro cell viability assay performed with human embryonic kidney 293 (HEK 293) cells suggested that WS‐probe is non‐toxic up to 10 μm and implicates the use of the probe for biological applications.     

Performance evaluation of the phase encoded optical CDMA system

Recently, there has been increasing interest in field of Optical CDMA due to its potential for offering unmatched features at ultra high data rates in field of local and metro area networks. In this paper, a very simple method of Optical CDMA encoding known as the Temporal Phase Encoding is discussed and the performance of the system with this encoding technique is evaluated on the basis of number of users, length of the spreading code for 4-phase and 8-phases. Simulation results for the system are presented for upto seven users. Bit error rate curves are plotted with data rate of 1 Gbps. This has been found that performance improves if normalized threshold higher than 0.5 is used.     

Dual drug-loaded paclitaxel–thymoquinone nanoparticles for effective breast cancer therapy

The present study highlights the beneficial synergistic blend of anticancer drug paclitaxel (PTX) and thymoquinone (TQ) in MCF-7 breast cancer cells. We aimed to augment the therapeutic index of PTX using a polymeric nanoparticle system loaded with PTX and TQ. PLGA nanoparticles encapsulating the two drugs, individually or in combination, were prepared by single emulsion solvent evaporation method. The formulated nanoparticles were homogenous with an overall negative charge and their size ranging between 200 and 300 nm. Entrapment efficiency of PTX and TQ in the dual drug-loaded nanoparticles was found to be 82.4 ± 2.18 and 65.8 ± 0.45 %, respectively. The release kinetics of PTX and TQ from the nanoparticles exhibited a biphasic pattern characterised by an initial burst, followed by a gradual and continuous release. The anticancer activity of nanoparticles encapsulating both the drugs was higher as compared to the free drugs in MCF-7 breast cancer cells. The combination index for the dual drug-loaded NPs was found to be 0.688 which is indicative of synergistic interaction. Thus, here, we propose the synthesis and use of dual drug-loaded TQ and PTX NPs which exhibits enhanced anticancer activity and can additionally help to alleviate the toxic effects of PTX by lowering its effective dose.     

Protein PEGylation attenuates adsorption and aggregation on a negatively charged and moderately hydrophobic polymer surface

Covalent grafting of poly(ethylene glycol) chains to proteins ("PEGylation") is emerging as an effective technique to increase the in vivo circulation time and efficacy of protein drugs. PEGylated protein adsorption at a variety of solid/aqueous interfaces is a critical aspect of their manufacture, storage, and delivery. A special category of block copolymer, PEGylated proteins have one or more water-soluble linear polymer (PEG) blocks and a single globular protein block that each exert distinct intermolecular and surface interaction forces. We report the impact of PEGylation on protein adsorption at the interface between aqueous solutions and solid films of poly(lactide-co-glycolide) (PLG), a moderately hydrophobic and negatively charged polymer. Using the model protein lysozyme with controlled degrees of PEGylation, we employ total internal reflection fluorescence techniques to measure adsorption isotherms, adsorption reversibility, and the extent of surface-induced aggregation. Lysozyme PEGylation reduces the extent of protein adsorption and surface-induced aggregation and increases the reversibility of adsorption compared to the unconjugated protein. Results are interpreted in terms of steric forces among grafted PEG chains and their effects on protein-protein interactions and protein orientation on the surface.     

Increasing the stability of an enzyme toward hostile organic solvents by directed evolution based on iterative saturation mutagenesis using the B-FIT method

Mutants of the lipase from Bacillus subtilis, previously engineered for enhanced thermostability using directed evolution based on the B-FIT method, show significantly increased tolerance to hostile organic solvents.     

Properties of glass-fiber reinforced composites based on liquid diglycidyl ether of bisphenol-c-epoxy resin

Glass-fiber reinforced epoxy composites were fabricated from the matrix resin liquid diglycidyl ether of bisphenol-C (DGEBC) using various amines as curing agents with and without fortifier (20 phr). The epoxy laminates were evaluated for their mechanical properties, such as flexural strength, interlaminar shear strength (ILSS), tensile strength and shore-D hardness. Dielectric properties, such as the dielectric constant, tan δ, dielectric loss and the resistivity of the laminated samples, were measured. The effect of the chemical reagents on the mechanical properties (i.e. flexural strength, lLSS) was also studied.     

On unified fractional integral operators

The present paper is in continuation to our recent paper [6] in these proceedings. Therein, three composition formulae for a general class of fractional integral operators had been established. In this paper, we develop the Mellin transforms and their inversions, the Mellin convolutions, the associated Parseval-Goldstein theorem and the images of the multivariableH-function together with applications for these operators. In all, seven theorems and two corollaries (involving the Konhauser biorthogonal polynomials and the Jacobi polynomials) have been established in this paper. On account of the most general nature of the polynomials S _n ^m [x] and the multivariableH-function whose product form the kernels of our operators, a large number of (new and known) interesting results involving simpler polynomials and special functions (involving one or more variables) obtained by several authors and hitherto lying scattered in the literature follow as special cases of our findings. We give here exact references to the results (in essence) of seven research papers which follow as simple special cases of our theorems.