Vacancy engineered ceria nanostructures for protection from radiation-induced cellular damage

The ability of engineered cerium oxide nanoparticles to confer radioprotection was examined. Human normal and tumor cells were treated with nanoceria and irradiated, and cell survival was measured. Treatment of normal cells conferred almost 99% protection from radiation-induced cell death, whereas the same concentration showed almost no protection of tumor cells. For the first time, nanoceria is shown to confer radioprotection to a normal human breast line but not to a human breast tumor line, MCF-7.     

Effect of air-pressure on room temperature hydrogen sensing characteristics of nanocrystalline doped tin oxide MEMS-based sensor

Nanocrystalline indium oxide (In2O3)-doped tin oxide (SnO2) thin film sensor has been sol-gel dip-coated on a microelectrochemical system (MEMS) device using a sol-gel dip-coating technique. Hydrogen (H2) at ppm-level has been successfully detected at room temperature using the present MEMS-based sensor. The room temperature H2 sensing characteristics (sensitivity, response and recovery time, and recovery rate) of the present MEMS-based sensor has been investigated as a function of air-pressure (50-600 Torr) with and without the ultraviolet (UV) radiation exposure. It has been demonstrated that, the concentration of the surface-adsorbed oxygen-ions (which is related to the sensor-resistance in air), the ppm-level H2, and the oxygen (O2) partial pressure are the three major factors, which determine the variation in the room temperature H2 sensing characteristics of the present MEMS-based sensor as a function of air-pressure.     

Fenton-like reaction catalyzed by the rare earth inner transition metal cerium

Cerium (Ce) is a rare earth metal that is not known to have any biological role. Cerium oxide materials of several sizes and shapes have been developed in recent years as a scaffold for catalysts. Indeed even cerium oxide nanoparticles themselves have displayed catalytic activities and antioxidant properties in tissue culture and animal models. Because of ceria's ability to cycle between the +3 and +4 states at oxygen vacancy sites, we investigated whether cerium metal would catalyze a Fenton-like reaction with hydrogen peroxide. Indeed, cerium chloride did exhibit radical production in the presence of hydrogen peroxide, as assessed by relaxation of supercoiled plasmid DNA. Radical production in this reaction was also followed by production of radical cation of 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS). Radical scavengers and spin traps were capable of competing with ABTS for radicals produced in this cerium dependent Fenton-like reaction. Electron paramagnetic resonance experiments reveal both hydroxyl radical and superoxide anion in a reaction containing cerium and hydrogen peroxide. Based on these results we propose that cerium is capable of redox-cycling with peroxide to generate damaging oxygen radicals.     

Photoelectrochemical analysis of band gap modulated TiO2 for photocatalytic water splitting

In this study the photocatalysis efficiency of titania (TiO₂) is increased by conjugating it with folic acid (FA) molecules through a silane linker (APTMS) layer. Electrochemical testing demonstrated higher negative open circuit potential (OCP) in surface engineered TiO₂ as compared to TiO₂ indicating higher Schottky barrier leading to suppressed electron–hole pair recombination. The photocurrent density under no bias conditions demonstrated 55% increase in modified titania due to lower band gap and suppressed electron hole pair recombination. The mechanism behind higher photocatalytic properties of surface engineered TiO₂ was derived using density functional theory (DFT).     

Steady Mixed Convection in Power-Law Fluids from a Heated Triangular Cylinder

The steady mixed convective transport from a heated triangular cylinder immersed in power-law fluids in an unconfined vertical domain is investigated numerically. Two different configurations of the cylinder are chosen; one when the base of the cylinder is facing the flow and the other when the apex of the triangle is facing the flow. The simulation is performed for: Reynolds number (1 to 35), Richardson number (0 to 2), power law index (0.4 to 1.8) and Prandtl number, 50. The flow and thermal fields are visualized through the streamlines and isotherm contours at the close proximity of the heated object for various Reynolds numbers, Richardson numbers and power law indices. The distributions of the surface pressure coefficient and local Nusselt number provide further insight of the hydrodynamic and thermal characteristics. Finally, the total drag coefficient and average Nusselt numbers on the surface of the cylinder are computed to explore the overall macroscopic behavior of the involved thermo-hydrodynamics. The flow separation is observed to be more when the apex of the cylinder is facing the flow. The average heat transfer, measured in terms of the Nusselt number, and the total drag on the cylinder are also found higher for that configuration.     

A review of power electronics interfaces for distributed energy systems towards achieving low-cost modular design

Due to increased attention towards clean and sustainable energy, distributed energy (DE) systems are gaining popularity all over the world. Power electronics are an integral part of these energy systems being able to convert generated electricity into consumer usable and utility compatible forms. But the addition of power electronics adds costs to the DE capital investments along with some reliability issues. Therefore, widespread use of distributed energy requires power electronics topologies that are less expensive and more dependable. Use of modular power electronics is a way to address these issues. Adoption of functional building blocks that can be used for multiple applications results in high volume production and reduced engineering effort, design testing, onsite installation and maintenance work for specific customer applications. In this paper, different power electronics topologies are reviewed that are typically used with distributed energy systems. The integrated power electronics module (IPEM) based back-to-back converter topologies are found to be most suitable interface that can operate with different DE systems with small or no modifications. Also the requirements for a hierarchical control structure with standardized power and communication interfaces are addressed in the paper along with some discussion on future design possibilities for the IPEM-based power electronics topologies. It is expected that modular and flexible power electronics and standardized controls and interfaces, will provide commonality in hardware and software for the power electronics interfaces, thus will enable their volume production and decrease their cost share in distributed energy applications.     

Extended exploiting modification direction based steganography using hashed-weightage Array

Multimedia Tools and Applications - Steganography is the method of hiding secret message information in various cover media like text, image, audio, video and others without raising suspicion to...     

Multi-scale RoIs selection for classifying multi-spectral images

Multidimensional Systems and Signal Processing - The applications of object-based image analysis (OBIA) in remote sensing studies have received a considerable amount of attention over the recent...     

Room temperature hydrogen detection using 1-D nanostructured tin oxide sensor

Room temperature sensing of hydrogen using randomly oriented tin oxide nanowires has been demonstrated successfully. The role of surface functionalization of nanowires with platinum catalyst in rapid hydrogen detection is also studied. These nanowires were successfully incorporated into a micro-electro-mechanical (MEMS) device. The device can successfully detect hydrogen gas (as low as 500 ppm) with response time as low as 10 sec. Effect of aspect ratio of the nanowires on diffusion of hydrogen molecules in the tin oxide nanowires is elucidated in detail.     

Low temperature sintering of CCTO using P2O5 as a sintering aid

Recent work on CCTO is directed towards decreasing its dissipation factor and further raising its dielectric constant by using different dopants. Also attempts have been made to lower its sintering temperature by adding different sintering aids so as to save energy and use low-cost electrodes (Ag–Pd or base metal) for making multilayer capacitors. Normally, CCTO needs a processing temperature of 1100 °C and above for densification. We report the formation of dense CCTO ceramics at a temperature as low as 1000 °C by adding P₂O₅ as a sintering aid. The samples showed dielectric constant value as high as 40,000, though the dissipation factor values remained high like those reported for pure CCTO.