Leakage current analysis of hydrothermal BaTiO3 thin films

Hydrothermal processing can deposit crystalline ferroelectric films at low temperatures of less than 150°C to achieve permittivities above 100. Such a process, hence, can be attractive in integrating thin film capacitors in organic, silicon or flex substrates. However, their poor insulation strength leading to high leakage current can prevent their wide acceptance. Lattice defects such as hydroxyl groups are attributed to their high leakage currents and lower Breakdown Voltages (BDVs). With appropriate thermal treatments, majority of the OH groups can be removed, leading to improved insulation characteristics. The leakage current behavior of as-synthesized and post-baked hydrothermal thin films are analyzed with various conduction models. The room temperature I-V characteristics are attributed to a combination of ionic and Space-Charge-Limited (SCLC) conduction models for films baked at 160°C while higher baking temperatures of 350°C agree well with Poole-Frenkel type conduction, with an activation energy of 0.57 eV for the defects. The defects, which are presumably OH groups or oxygen vacancies embedded in the barium titanate lattice, act as shallow traps and the trapping and detrapping results in easier conduction. A brief perspective is provided on the suitability of such a hydrothermal thin film capacitor approach for power supply applications.     

Ammoxidation of 3-picoline over V2O5/TiO2 (anatase) system I. Relationship between ammoxidation activity and oxidation state of vanadium

A series of titania (anatase)-supported vanadia catalysts ranging in V₂O₅ content from 0.4 to 9.9 mol% was prepared by wet impregnation technique, characterized by BET surface area measurement and X-ray diffraction, and evaluated for ammoxidation of 3-picoline. The average oxidation number of vanadium in the fresh and used catalysts was determined by titrimetric methods. The ammoxidation activity and the average oxidation number were observed to increase with vanadia loading up to 3.4 mol% in the catalyst which corresponds to a monolayer coverage. The phase transformation of anatase to rutile after the reaction was observed at a V₂O₅ loading of 5.9 mol%. The slow decrease of ammoxidation activity beyond 3.4 mol% V₂O₅ was attributed to the coverage of active monomeric VO_x species on the support by bulk vanadia and by other oxides, and also to compound formation with ammonia.     

Limb salvage using free tissue transfer following meningococcal septicemia

Over the past 10 years, I have been privileged to conduct educational forums for audiences containing many recovering alcoholics or otherwise chemically dependent persons. In these forums about the addictive diseases and their treatment and research possibilities, significant interaction with the audience members occurs. During these interactions, certain anecdotal phenomena seem to predominate. The repetitive nature of these reports suggests the need for systematic investigation. As with editorial comments in major medical journals, observed phenomena and unanswered questions from those afflicted can be valuable in the generation of testable hypotheses. Perhaps the ideas presented herein will be useful in the development of future research on alcohol abuse and alcohol dependence.     

Oral Nanoparticulate Atorvastatin Calcium is More Efficient and Safe in Comparison to Lipicure<Superscript>®</Superscript> in Treating Hyperlipidemia

Atorvastatin calcium (AC) is a second-generation 3-hydroxy-3-methylglutaryl-CoA reductase inhibitor approved for clinical use as a lipid lowering agent. AC, the world's best selling drug is associated with poor oral bioavailability and serious adverse effects like rhabdomyolysis on chronic administration. A biodegradable nanoparticulate approach was introduced here with a view to improving the efficacy and safety of AC. Poly lactide-co-glycolic acid (PLGA) nanoparticles containing atorvastatin calcium were prepared using two stabilizers i.e. didodecyl dimethyl ammonium bromide (DMAB) and Vitamin E tocopheryl polyethylene glycol 1000 succinate (Vit E-TPGS) using a co-solvent approach by emulsion-diffusion-evaporation method. AC loaded PLGA nanoparticles prepared using DMAB and Vit E-TPGS were found to be 120.0 +/- 4.2 nm and 140.0 +/- 1.5 nm (z-average) in size respectively. In vitro release studies at pH 7.4 revealed a zero order release profile for nanoparticles. Efficacy and safety parameters of the prepared nanoparticles against marketed formulation were evaluated in high fat diet fed (hyperlipidemic) rats. It was found that atorvastatin calcium nanoparticles were equally effective in comparison to Lipicure, at a 66%-reduced dose in treating the hyperlipidemia characterized by alterations in PTC, LDL-C, VLDL-C, HDL-C, PTG and PGL in the high fat diet fed rats. On the other hand, when evaluated for safety, nanoparticulate formulation showed no/negligible myotoxicity characterized by lower PC, BUN, CK, LDH and AST levels in comparison to the marketed formulation.     

Preparation and in vitro/in vivo evaluation of gliclazide loaded Eudragit nanoparticles as a sustained release carriers

The aim of this study was to formulate and optimize gliclazide-loaded Eudragit nanoparticles (Eudragit L100 and Eudragit RS) as a sustained release carrier with enhanced efficacy. Eudragit L 100 nanoparticles (ELNP) were prepared by controlled precipitation method whereas Eudragit RSPO nanoparticles (ERSNP) were prepared by solvent evaporation method. The influence of various formulation factors (stirring speed, drug:polymer ratio, homogenization, and addition of surfactants) on particle size, drug loading, and encapsulation efficiency were investigated. The developed Eudragit nanoparticles (L100 and RS) showed high drug loading and encapsulation efficiencies with nanosize. Mean particle size altered by changing the drug:polymer ratio and stirring speed. Addition of surfactants showed a promise to increase drug loading, encapsulation efficiency, and decreased particle size of ELNP as well as ERSNP. Dissolution study revealed sustained release of gliclazide from Eudragit L100 as well as Eudragit RSPO NP. SEM study revealed spherical morphology of the developed Eudragit (L100 and RS) NP. FT-IR and DSC studies showed no interaction of gliclazide with polymers. Stability studies revealed that the gliclazide-loaded nanoparticles were stable at the end of 6 months. Developed Eudragit NPs revealed a decreased t_min (ELNP), and enhanced bioavailability and sustained activity (ELNP and ERSNP) and hence superior activity as compared to plain gliclazide in streptozotocin induced diabetic rat model and glucose-loaded diabetic rat model. The developed Eudragit (L100 and RSPO) NP could reduce dose frequency, decrease side effects, and improve patient compliance.     

Electronic coupling between azurin and gold at different protein/substrate orientations

By means of constrained classical molecular dynamics simulations, we have computed the structure of azurin deposited on a Au(111) surface at different possible orientations and the azimuthal forces acting on the protein at each sampled conformation. We have then evaluated the effect of the angular variation on the speed of electron tunneling between the protein redox site and the metal surface. We find that the azurin/gold electronic coupling has a strong dependence on the molecular orientation and is greatly enhanced by inclining the protein to lie as flat as possible on the surface. We discuss the implications of our results for scanning probe microscopy experiments in which tunneling currents are measured while the protein is subjected to mechanical forces exerted by the tip of the instrument.     

Modular product family design: Agent-based Pareto-optimization and quality loss function-based post-optimal analysis

The advent of mass customization and increased manufacturing competition has necessitated that many companies offer platform-oriented multiple product variants. Various design strategies such as Design for Variety and product family design have become critical in this respect. This paper provides a two-step approach to tackle the modular product family design problem. The first step performs a multi-objective optimization using a multi-agent framework to determine the Pareto-design solutions for a given module set. The proposed multi-agent framework is new and has built in flexibility to handle various constraints such as module compatibility during the optimization process. The second step performs post-optimization analysis that includes a novel application of the quality loss function to determine the optimal platform level for a related set of product families and their variants. The proposed method is applied to a product family design example to demonstrate its validity and effectiveness.