Preparation of a functional nanofibrous polymer membrane incorporated with poly(2-aminothio phenol) stabilized gold nanoparticles

Functional nanofibrous polymer membranes were prepared by incorporating poly(2-aminothio phenol) (P2AT) stabilized Au NPs onto electrospun polyvinylidene fluoride (PVdF) nanofibers (designated as P2AT-Au NPs@PVdF-NFM). The preparation of P2AT-Au NPs@PVdF-NFM involves two steps: loading of 2AT (monomer) into electrospun PVdF nanofibrous membrane and polymerization of 2AT by gold chloride. P2AT and Au NPs were simultaneously formed into the electrospun PVdF-NFM. Transmission electron microscope image of P2AT-Au NPs@PVdF-NFM informs the presence of Au NPs (with sizes ~10 nm) onto PVdF-NFM.     

Phospholipid Cyclosporine Prodrugs Targeted at Inflammatory Bowel Disease (IBD) Treatment: Design,Synthesis, and in Vitro Validation

Novel phospholipid (PL)-cyclosporine conjugates were prepared and studied as potential prodrugs for inflammatory bowel disease (IBD). Our approach relies on phospholipase A₂ (PLA₂), which is overexpressed in the inflamed intestinal tissues, as the prodrug activator to potentially release cyclosporine at the site of inflammation. PL-cyclosporine prodrug conjugates with methylene linkers of various lengths between the sn-2 position of the PL and cyclosporine were synthesized and evaluated for in vitro activation. Surprisingly, despite previous work indicating that conjugates with six methylene linkers between the lipid and drug would suffer rapid enzymatic hydrolysis, with cyclosporine this was not observed. However, compounds with longer linkers (n=10, 12 methylene units) display complete release of the drug by PLA₂-catalyzed hydrolysis, thus demonstrating the importance and profound impact of structural fine-tuning. This study represents a proof-of-concept for our hypothesis and a first step towards a truly targeted IBD treatment with cyclosporine that could be administered throughout the GI tract.     

Heuristic techniques for accelerating hierarchical routing on road networks

The route computation module is one of the most important functional blocks in a dynamic route guidance system. Although various algorithms exist for finding the shortest path, their performance tends to deteriorate as the network size increases. We present an efficient hierarchical routing algorithm that finds a near-optimal route and evaluate it on a large city road network. Solutions provided by the hierarchical routing algorithm are compared with the optimal solutions to analyze and quantify the loss of accuracy. We propose a novel yet simple heuristic to substantially improve the performance of the hierarchical routing algorithm with acceptable loss of accuracy. A network pruning technique has been incorporated into the algorithm to reduce the search space and the correctness of the results is evaluated. The improved hierarchical routing algorithm that incorporates the heuristic techniques has been found to be over 50 times faster than a typical shortest path algorithm.     

Integrated electro-optic lens/scanner in a LiTaO3 single crystal

We report what we believe to be the first stand-alone integrated electro-optic lens and scanner fabricated on a single crystal of Z-cut LiTaO(3). The independently controlled lens and scanner components consist of lithographically defined domain-inverted regions extending through the thickness of the crystal. A lens power of 0.233 cm(-1) kV(-1) and a deflection angle of 12.68 mrad kV(-1) were observed at the output of the device.     

Analyses of Two Different 1-Server Systems

In this paper, the availability and the reliability of two 1-server systems with redundancy have been obtained. System 1 consists of n subsystems in series; each subsystem consists of two redundant i.i.d. components in `parallel' (cold standby) and one server. The times to failure of the components are exponentially distributed; their repair time distributions are arbitrary and different. System 2 consists of n dissimilar units and one server. The times to failure of the units are arbitrarily distributed; the repair rates are constant but all different. Explicit expressions for the Laplace transform of the mean down-time of the system in (0, t) and for the mean time to system failure have been obtained. A few particular cases are discussed.     

Changes in the glaciers of Chandra–Bhaga basin,Himachal Himalaya,India, between 1980 and 2010 measured using remote sensing

This study reports the glacier changes of Chandra–Bhaga basin, northwest Himalaya, India, from 1980 to 2010. Satellite remote-sensing data from the Landsat Multispectral Scanner (MSS) and Thematic Mapper (TM), the Linear Imaging Self Scanning Sensor (LISS) and Advanced Wide Field Sensor (AWiFS) of the Indian Remote Sensing (IRS) series, and the Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM) were used to study the changes in glacier parameters such as glacier area, length, snout elevation, and the impact of glacier topographical parameters (glacier slope, aspect, and altitude range) on the glacier changes. It was found that the total glaciated area had shrunk to 368.2 km² in 2010 from 377.6 km² in 1980, a loss of 2.5%. The average position of glacier terminuses retreated by 465.5 ± 169.1 m from 1980 to 2010 with an average rate of 15.5 ± 5.6 m year^?1. The decadal scale analysis showed that the average rate of retreat had increased the most in the recent decade. A moraine-dammed lake located in the study region was found to have expanded in area from (0.65 ± 0.01) km² in 1980 to (1.26 ± 0.03) km² in 2010. Glaciers with steep slope and less altitude range have lost more area than the glaciers having gentle slope and greater altitude range.     

Polarization measurements on single-step co-fired solid oxide fuel cells (SOFCs)

Anode-supported planar solid oxide fuel cells (SOFC) were successfully fabricated by a single step co-firing process. The cells comprised of a Ni + yttria-stabilized zirconia (YSZ) anode, a YSZ or scandia-stabilized zirconia (ScSZ) electrolyte, a (La_0.85Ca_0.15)_0.97MnO₃ (LCM) + YSZ cathode active layer, and an LCM cathode current collector layer. The fabrication process involved tape casting of the anode, screen printing of the electrolyte and the cathode, and single step co-firing of the green-state cells in the temperature range of 1300–1330 °C for 2 h. Cells were tested in the temperature range of 700–800 °C with humidified hydrogen as fuel and air as oxidant. Cell test results and polarization modeling showed that the polarization losses were dominated by the ohmic loss associated with the electrodes and the activation polarization of the cathode, and that the ohmic loss due to the ionic resistance of the electrolyte and the activation polarization of the anode were relatively insignificant. Ohmic resistance associated with the electrode was lowered by improving the electrical contact between the electrode and the current collector. Activation polarization of the cathode was reduced by the improvement of the microstructure of the cathode active layer and lowering the cell sintering temperature. The cell performance was further improved by increasing the porosity in the anode. As a result, the maximum power density of 1.5 W cm⁻² was achieved at 800 °C with humidified hydrogen and air.     

Hydrogen generation and separation using Gd0.2Ce0.8O1.9−δ–Gd0.08Sr0.88Ti0.95Al0.05O3±δ mixed ionic and electronic conducting membranes

Decomposition of steam under a chemical driving force at moderate temperatures offers a simple and economical way to generate hydrogen. A significant amount of hydrogen can be generated and separated by splitting steam and removing the oxygen using Gd_0.2Ce_0.8O_1.9−δ (GDC)–Gd_0.08Sr_0.88Ti_0.95Al_0.05O_3±δ (GSTA) mixed oxygen ionic and electronic conducting membranes. Hydrogen generation experiments for the self-supported thick membranes and porous supported thin membranes were conducted at different oxygen partial pressure gradients across the membrane established using H₂–H₂O mixture gas. Experimental results indicate that the hydrogen generation from steam using GDC–GSTA MIEC membranes at elevated temperatures is mainly controlled by the bulk diffusion of oxygen for the self-supported thick membranes, while the permeation process for the porous supported thin membranes is mixed controlled, i.e. the hydrogen generation/oxygen permeation process is controlled by the surface exchange reactions and bulk diffusion of oxygen through the MIEC membrane. A mathematical model for the calculation of the area specific hydrogen generation rate is proposed in this paper based on the measured oxygen partial pressures, gas compositions, and gas flow rates of the inlet and outlet gases on feed side of the membrane, as well as the permeation area of the membrane.     

Enhanced electrocatalytic performance of cyano groups containing conducting polymer supported catalyst for oxidation of formic acid

A new palladium (Pd) based catalyst was developed using poly(diphenylamine-co-3-aminobenzonitrile) (P(DPA-co-3ABN)) as the new catalyst support. The sizes, distribution and stability of Pd nanoparticles (Pd NPs) are strongly influenced by the cyano group (–CN) present in P(DPA-co-3ABN). Field emission scanning electron microscopy image and energy dispersive x-ray analysis revealed good dispersion of Pd NP onto P(DPA-co-3ABN) matrix. The electrocatalytic activity of P(DPA-co-3ABN)/Pd catalyst electrode (CE) was investigated in terms of formic acid (FA) electro oxidation. The onset potential and catalytic current for the electro oxidation of FA are higher at P(DPA-co-3ABN)/Pd-CE as compared to PdNPs loaded pristine PDPA catalyst electrode (PDPA/Pd-CE). P(DPA-co-3ABN)/Pd-CE exhibited 18 time higher electrocatalytic current than PDPA/Pd-CE for oxidation of FA.