Thermal decomposition as route for silver nanoparticles

Single crystalline silver nanoparticles have been synthesized by thermal decomposition of silver oxalate in water and in ethylene glycol. Polyvinyl alcohol (PVA) was employed as a capping agent. The particles were spherical in shape with size below 10 nm. The chemical reduction of silver oxalate by PVA was also observed. Increase of the polymer concentration led to a decrease in the size of Ag particles. Ag nanoparticle was not formed in the absence of PVA. Antibacterial activity of the Ag colloid was studied by disc diffusion method.     

Particulate matter air pollution disrupts endothelial cell barrier via calpain-mediated tight junction protein degradation

ABSTRACT: BACKGROUND: : Exposure to particulate matter (PM) is a significant risk factor for increased cardiopulmonary morbidity and mortality. The mechanism of PM-mediated pathophysiology remains unknown. However, PM is proinflammatory to the endothelium and increases vascular permeability in vitro and in vivo via ROS generation. OBJECTIVES: We explored the role of tight junction proteins as targets for PM-induced loss of lung endothelial cell (EC) barrier integrity and enhanced cardiopulmonary dysfunction. METHOD: S: Changes in human lung EC monolayer permeability were assessed by Transendothelial Electrical Resistance (TER) in response to PM challenge (collected from Ft. McHenry Tunnel, Baltimore, MD, particle size >0.1 um). Biochemical assessment of ROS generation and Ca2+ mobilization were also measured. RESULTS: : PM exposure induced tight junction protein ZO-1 relocation from the cell periphery, which was accompanied by significant reductions in ZO-1 protein levels but not in adherens junction proteins (VE-cadherin and beta-catenin). N-acetyl-cysteine (NAC, 5mM) reduced PM-induced ROS generation in ECs, which further prevented TER decreases and atteneuated ZO-1 degradation. PM also mediated intracellular calcium mobilization via the transient receptor potential cation channel M2 (TRPM2), in a ROS-dependent manner with subsequent activation of the Ca2+-dependent protease calpain. PM-activated calpain is responsible for ZO-1 degradation and EC barrier disruption. Overexpression of ZO-1 attenuated PM-induced endothelial barrier disruption and vascular hyperpermeability in vivo and in vitro. CONCLUSIONS: : These results demonstrate that PM induces marked increases in vascular permeability via ROS-mediated calcium leakage via activated TRPM2, and via ZO-1 degradation by activated calpain. These findings support a novel mechanism for PM-induced lung damage and adverse cardiovascular outcomes.     

Venturi Scrubber Modelling and Optimization

An improved algorithm that optimizes Pease‐Anthony type venturi scrubber performance is presented in this work. This approach predicts the minimum pressure drop needed to achieve the desired collection efficiency by optimizing key operating and design parameters such as liquid‐to‐gas ratio, throat gas velocity, number of nozzles, nozzle diameter, and throat aspect ratio. A detailed assessment of four established pressure drop models and an extension of two of the models by providing an empirical algorithm to give better prediction of pressure drop in the venturi throat have been conducted by validating them with experimental data. This optimization algorithm provides a stepwise, effective, and accurate approach to optimizing both existing and new scrubbers.     

Biofiltration of volatile organic compound using two packing materials: Kinetics and modelling

The performance of two laboratory scale biofilters, packed with pressmud (BF1) and sugarcane bagasse (BF2), was evaluated for gas phase ethylacetate removal under various operating conditions. Biofilters were inoculated with mixed culture obtained from pharmaceutical wastewater sludge. Experiments were carried out at different flow rates (0.03, 0.06, 0.09 and 0.12 m³ h^?1) and inlet ethylacetate concentrations (0.2, 0.4, 0.6 and 1.2 gm^?3). Maximum removal efficiency (RE) of 100% and 98% was achieved at an inlet concentration of 0.2 gm^?3 and gas flow rate of 0.03 m³ h^?1 in BF1 and BF2, respectively. A maximum elimination capacity (EC) of 66.6 gm^?3 h^?1 and 64.1 gm^?3 h^?1 was obtained in BF1 and BF2, respectively, at an inlet concentration of 0.8 gm^?3 and a gas flow rate of 0.12 m³ h^?1. The kinetics of biofiltration of ethylacetate was studied by using Ottengraf and van den Oever model. The kinetic modelling gives an insight into the mechanism of biofiltration. The modified Ottengraf model, which was also tested, demonstrated good agreement between calculated and experimental data.     

A feasible strategy for tailoring stable spray-coated electrolyte layer in micro-tubular solid oxide fuel cells

By this work, the viability of the spray coating as a cost-effective and reliable technique for the coating of Ce_0.9Gd_0.1O_1.95 (GDC) electrolyte layer on the mini-tubular NiO–GDC anodes based a solid oxide fuel cell (SOFC) fabrication was assessed. The compatibility of the anode and electrolyte was analyzed by using XRD. The variation in thickness and morphology of the electrolyte film as a function of the coating cycles was discussed with optical and scanning electron microscopes. By similar formulation, the coating of La_0.6Sr_0.4Fe_0.8Co_0.2O₃ –Ce_0.9Gd_0.1O_2–δ (LSCF–GDC) was performed to achieve porous cathode. An individual micro-tubular anode supported cell with configuration NiO–GDC/GDC/LSCF–GDC as anode/electrolyte/cathode was tested in the SOFC mode with humidified hydrogen as fuel and stationary air as oxidant. The fabricated mini-SOFC prototype that generated a maximum power density of 0.510 W/cm² at 600°C signifies the potential of this industrially scalable low-cost coating technique.     

Single molecular switch based on thiol tethered iron(II)clathrochelate on gold

Molecular electronics has been associated with high density nano-electronic devices. Developments of molecular electronic devices were based on reversible switching of molecules between the two conductive states. In this paper, self-assembled monolayers of dodecanethiol (DDT) and thiol tethered iron(II)clathrochelate (IC) have been prepared on gold film. The electrochemical and electronic properties of IC molecules inserted into the dodecanethiol monolayer (IC-DDT SAM) were investigated using voltammetric, electrochemical impedance spectrpscopy (EIS), scanning tunneling microscopy (STM) and cross-wire tunneling measurements. The voltage triggered switching behaviour of IC molecules on mixed SAM was demonstrated. Deposition of polyaniline on the redox sites of IC-DDT SAM using electrochemical polymerization of aniline was performed in order to confirm that this monolayer acts as nano-patterned semiconducting electrode surface.     

Interaction of aflatoxin B1 with some biologically important substances

The interaction of aflatoxin B₁ with a number of biologically important substances has been investigated by spectrophotometric and fluorimetric techniques. The ultra-violet absorption of tryptophan, adenosine, RNA and DNA were altered by the addition of aflatoxin B₁. Some amino-acids, purine and pyrimidine derivatives, bovine-serum albumin and DNA quenched the fluorescence of aflatoxin B₁. Fluorescence polarization data suggested that the interaction of aflatoxin B₁ with bovine-serum albumin was stronger than that with DNA.     

Role of Spray Drying of Nanoagglomerates in Morphology Evolution in Nanostructured APS Coatings

Nanostructured coatings undergo many processing challenges during atmospheric plasma spray if the feedstock is not well prepared. The effects of using spray drying on achieving a suitable feedstock for an even flow of nanoparticles through the gun, the selection of plasma gases for optimum heat transfer, and the velocity of the agglomerates during flight are highlighted in this communication. Analytical heat transfer calculations are used for coating property optimization. The physical characteristics of the nanoagglomerates are studied using diagnostics sensor and scanning electron microscopy. Transmission electron microscopy revealed the retention of nanostructures.     

Fluorescence changes of aflatoxins B1 and G1.

The effects of various factors, such as pH, buffer, sodiumchloride and ultra-violet radiation on the fluorescence of aflatoxins B1 and G1 have been studied. The fluorescence characteristics of aflatoxins B1 and G1 underwent a marked change at pH values above 7.2. Prolonged exposure to ultra-violet radiation lead to some degradation of aflatoxins and the extent of degradation was dependent upon the nature of the solvent. Sodium chloride partially protected the toxins from degradation by ultra-violet radiation or alkaline conditions.