Conversion of monolithic gels to glasses in a multicomponent silicate glass system

Multicomponent silicate glasses of composition (wt%) 66SiO₂-18B₂O₃-7Al₂O₃-6Na₂O-3BaO were prepared by three sol-gel processes which differed primarily in the extent of hydrolysis of the metal alkoxide precursors. Gels which were prepared from solutions in which a stoichiometric excess of water was added, causing extensive replacement of OR groups (R (C _x H(_2x+1))^s–1 by hydroxyl groups, were converted to fully dense, organic-free, monolithic glasses at temperatures near the glass transition temperature. Gels containing large numbers of OR groups showed enhanced densification at lower temperatures due to condensation reactions, but these gels could not be converted to fully dense, organic-free glasses. This investigation has shown that at least three possible densification mechanisms might be operative during the gel to glass conversion: volume relaxation, condensation reactions and viscous sintering.A US Department of Energy Facility.     

Modeling mineral phase change chemistry of groundwater in a rural-urban fringe

This research paper aims to determine the genetic origin of the chemical elements in groundwater. It deals with the results of physicochemical parameters, to evaluate the hydro-geochemistry of groundwater in rural-urban fringe of district Bareilly, India. Pre- and post-monsoon sampling has been carried out, which reveals inter-seasonal variability effect on the hydro-geochemical processes. Geochemical modeling especially computation of saturation index was undertaken using the WATEQ4F model. Majority of samples fall in the category of undersaturation, which further suggests that groundwater still has potential to dissolve more minerals. Chemical categorizations of groundwater samples were performed with the help of the Aquachem model. Grouping of groundwater on the Piper diagram reveals a common composition and origin. In most of the area, water facies is of Ca(2+)-HCO(3)(-) type in both the seasons. It also indicates that in pre-monsoon, ion exchange is the dominant process, whereas in post-monsoon, both ion exchanges as well as reverse ion exchanges are reported in the groundwater of the study area.     

Delineation of Groundwater Potential Zones in Arid Region of India—A Remote Sensing and GIS Approach

The present research is an attempt to find out the groundwater potential zones within an arid region of India supported by the scientific investigation of lithology, geomorphology, geohydrological characterization of geological formations and their interrelationship. Thematic layers of drainage, lithology, geomorphology, lineaments, slope, soil, digital elevation model, rainfall, landuse/land cover and well inventory have been generated by using ancillary data, digital satellite image, water level data of 90 observation wells for last 11?years (2000?C2010), litholog data along with ground truthing. The groundwater potential zones have been classified into five categories like very poor, poor, moderate, good and excellent. The potential zones were obtained by weighted overlay combination using the spatial analyst tool in ArcGIS 9.2. During weighted overlay analysis, the ranking was given for each individual parameter of each thematic map and weights were assigned according to their influence such as lithology (20?%), geomorphology (15?%), lineament density (15?%), drainage density (15?%), soil (10?%), slope (10?%), rainfall (5?%), land use and land cover (5?%) and digital elevation model (DEM) (5?%) and it was found that the potential zones in terms of very poor, poor, moderate, good and excellent zones covered 13.7?%, 42.8?%, 27.3?%, 10.8% and 5.4% respectively of the total area. The result also has been validated by yield data collected from existing sources and it confirms that the higher yield categories are falling within excellent groundwater potential zones where yield ranges from 23 to 40.3?l/s and lower values ranging from 8.1 to 10.6?l/s are falling within poor groundwater potential zones.     

Porous Titania Thin Films Grown by Anodic Oxidation for Hydrogen Sensors

Porous titanium dioxide (Titania) thin films were grown by anodic oxidation using high purity (99.7%) titanium foil in a dilute sulphuric acid (1 M) medium. The anodization process was carried out for 30 minutes with 20 mA/cm² and 50 mA/cm² current densities. The samples were characterized by XRD, SEM, and AFM techniques. It was found that the grown porous titania films were less sensitive to 500 ppm hydrogen in air ambient below 300°C; however, the sensitivity and response behavior of the film at 300°C are very much dependent on the growth conditions. Particularly, the films grown at current density 50 mA/cm² and 1 M acid concentration exhibited the lowest response time of 151 sec at 300°C.     

Preparation of Adrenochrome Hydrogel Patch, Gel, Ointment, and the Comparison of Their Blood Coagulating and Wound Healing Capability

The aim of this study is to make an effective blood coagulant and wound healing agent, which on its topical application on ruptured skin would help in instant coagulation of blood and ongoing healing of wound. The hydrogel has been prepared by mixing 28% w/v gelatin and 21% w/v PVA in distilled water, and heated to 40°C followed by addition of a blood coagulant at a lower temperature. Beeswax, alcohol, liquid paraffin, and adrenochrome were mixed, triturated, and heated accordingly to prepare adrenochrome ointment. Polyvinyl alcohol and glycerin were mixed and heated and the drug was added at a lower temperature, and stored at 4-5°C to form adrenochrome gel. Gelatin alone has cell adhesion property. Adrenochrome is a blood coagulant. Therefore, gelatin with adrenochrome in hydrogel has a synergistic effect in wound healing. To evaluate the efficacy of these three different formulations, incisions were made on the backs of three mice and simultaneously adrenochrome containing hydrogel patch, gel, and ointment were applied on the wound and observed at regular intervals for half an hour to examine the rate of blood coagulation and kept under observation for 2 days to study the rate of wound healing. The efficacy of all these three formulations was compared to appraise the most effective blood coagulating and wound healing agent.     

An electrochemical technique to deposit thin films of PbTe

PbTe thin films were deposited electrochemically on transparent conducting oxide coated (TCO) glass substrates from a solution of lead acetate and TeO₂ at low pH. A lead (Pb) strip was used as a sacrificing anode and the TCO glass acted as the cathode, which were short-circuited externally. Depositions were carried out at different temperatures of the bath to study the growth kinetics and grain growth. X-ray diffraction technique, scanning electron microscopy, infrared spectroscopy and resistivity measurements were carried out to characterize the deposited films. The films were polycrystalline in nature with a cubic phase.     

Towards the Development of a New Iron Age

Steel in its various forms is the most widely utilized metallic alloy and comprises over 80 % by weight of all metallic alloys in industrial use.^[1] The development of steel microstructures is based on manipulation of a very specific solid/solid state transformation called an eutectoid transformation (i.e. γ_austenite → α_ferrite+ Fe₃C_cementite). The control of this transformation is the primary factor resulting in wide variety of microstructures and resulting properties found in commercial steel alloys. However, the full benefit of its main constituent, iron has never been realized. Based on the metallic bonding in iron, the theoretical tensile strength has been calculated to be 13.2 GPa but ultra high strength steels, even today, only achieve maximum tensile strength levels from 1 to 1.5 GPa. Thus, our modern technological society has been established utilizing approximately only ～ 10 % strength level of iron. Here we demonstrate that a high level of strength (6.2 GPa) and strength to weight ratio of 8.3 × 10⁴/m³ may be obtained in iron‐based alloys by their solidification into metallic glasses, as well as, by employing another solid state transformation called glass devitrification.     

Catalytic oxidation of carbon monoxide over radiolytically prepared Pt nanoparticles supported on glass

Platinum nanoparticles have been prepared by radiolytic and chemical methods in the presence of stabilizer gelatin and SiO₂ nanoparticles. The formation of Pt nanoparticles was confirmed using UV-vis absorption spectroscopy and transmission electron microscopy (TEM). The prepared particles were coated on the inner walls of the tubular pyrex reactor and tested for their catalytic activity for oxidation of CO. It was observed that Pt nanoparticles prepared in the presence of a stabilizer (gelatin) showed a higher tendency to adhere to the inner walls of the pyrex reactor as compared to that prepared in the presence of silica nanoparticles. The catalyst was found to be active at ≥150 °C giving CO₂. Chemically reduced Pt nanoparticles stabilized on silica nanoparticles gave ∼7% CO conversion per hour. However, radiolytically prepared Pt nanoparticles stabilized by gelatin gave ∼10% conversion per hour. Catalytic activity of radiolytically prepared platinum catalyst, coated on the inner walls of the reactor, was evaluated as a function of CO concentration and reaction temperature. The rate of reaction increased with increase in reaction temperature and the activation energy for the reaction was found to be ∼108.8 kJ mol⁻¹. The rate of CO₂ formation was almost constant (∼1.5 × 10⁻⁴ mol dm⁻³ h⁻¹) at constant O₂ concentration (6.5 × 10⁻³ mol dm⁻³) with increase in CO concentration from 2 × 10⁻⁴ mol dm⁻³ to 3.25 × 10⁻³ mol dm⁻³. The data indicate that catalytic oxidation of CO takes place by Eley-Rideal mechanism.     

Pervasive computing: a paradigm for the 21st century

Pervasive computing promises to make life simpler via digital environments that sense, adapt, and respond to human needs. Yet we still view computers as machines that run programs in a virtual environment. Pervasive computing presumes a different vision. A device can be a portal into an application-data space, not just a repository of custom software a user must manage. An application is a means by which a user performs a task, not software written to exploit a device's capabilities. And a computing environment is an information-enhanced physical space, not a virtual environment that exists to store and run software. Pervasive computing is close to technical and economic viability.     

A software platform for testing intrusion detection systems

Intrusion detection systems monitor system activities to identify unauthorized use, misuse, or abuse. IDSs offer a defense when your system's vulnerabilities are exploited and do so without requiring you to replace expensive equipment. The steady growth in research on intrusion detection systems has created a demand for tools and methods to test their effectiveness. The authors have developed a software platform that both simulates intrusions and supports their systematic methodology for IDS testing