Machinable mica-based glass-ceramic

A glass-ceramic in the K₂O-MgO-Al₂O₃-MgF₂-SiO₂ system was prepared through the sol-gel and alkaline precipitation routes. The powders were hot pressed into workable discs. The glass-ceramic was found to be machinable with conventional tools. Its physical and mechanical properties compare favourably with commercial macor. A dependence of flexure strength on microstructure is also indicated.     

FAIRIO: A Throughput-oriented Algorithm for Differentiated I/O Performance

Providing differentiated service in a consolidated storage environment is a challenging task. To address this problem, we introduce FAIRIO, a cycle-based I/O scheduling algorithm that provides differentiated service to workloads concurrently accessing a consolidated RAID storage system. FAIRIO enforces proportional sharing of I/O service through fair scheduling of disk time. During each cycle of the algorithm, I/O requests are scheduled according to workload weights and disk-time utilization history. Experiments, which were driven by the I/O request streams of real and synthetic I/O benchmarks and run on a modified version of DiskSim, provide evidence of FAIRIO’s effectiveness and demonstrate that fair scheduling of disk time is key to achieving differentiated service in a RAID storage system. In particular, the experimental results show that, for a broad range of workload request types, sizes, and access characteristics, the algorithm provides differentiated storage throughput that is within 10% of being perfectly proportional to workload weights; and, it achieves this with little or no degradation of aggregate throughput. The core design concepts of FAIRIO, including service-time allocation and history-driven compensation, potentially can be used to design I/O scheduling algorithms that provide workloads with differentiated service in storage systems comprised of RAIDs, multiple RAIDs, SANs, and hypervisors for Clouds.     

Metol as Corrosion Inhibitor for zinc

The inhibition behavior of metol (N-methyl-p-aminophenol sulphate) on zinc in different corrosive solutions at room temperature was investigated by various techniques such as weight loss, polarization and linear polarization methods. The percentage inhibition efficiencies were evaluated at different concentrations of the inhibitors. The corrosion rate, inhibition efficiency and surface coverage were dependent on metol concentration. The electrochemical data indicated a basic modification of zinc surface resulting in a decrease in the corrosion rate. Corrosion inhibition was explained by considering an interaction between metal surface and the inhibitor. SEM images and FT-IR profiles confirmed the formation of passive film on the metal surface.     

Interfacial area and mass transfer coefficients in liquid-gas ejectors

Measurements and correlations are reported for the interfacial area and mass transfer coefficients as a function of energy dissipation in a liquid-gas ejector. The correlations for interfacial area and mass transfer coefficients have been developed using Kolmogorov’s theory and Levich’s hydrodynamic derivations. The present developed correlations are validated using experimental results.     

Correlation between structural properties and gas sensing characteristics of SnO2 based gas sensors

Undoped polycrystalline tin oxide sintered in the temperature range 500–1000 °C has been comprehensively characterized with respect to its response to CO, methane and H₂. Results obtained at an operating temperature of 300 °C show that increasing the sintering temperature leads to a gradual increase in CO sensitivity which reaches a maximum after sintering at 800 °C.     

Chemical and nutritional evaluation of chili (Capsicum annum) seed oil

Alkali-refined red chili (Capsicum annum) seed oil was analyzed for free fatty acids, iodine value, saponification value, peroxide value and fatty acid composition, and the values were found to be close to those of edible oils. The alkali-refined chili oil (5% of diet), alcohol-treated chili oil (5%) and a mixture of alcohol-treated chili oil and peanut oil (5%+5%) were fed to adult male albino rats in natural diets for eight weeks. Digestibility was normal in all experimental animals and was on par with the peanut oil control. Serum lipid levels in the group fed alcohol-treated chili oil were slightly high compared to those in groups fed alkali-refined chili oil and peanut oil. Liver structure revealed no abnormalities.     

Development and in vitro evaluation of a nanoemulsion for transcutaneous delivery

Objective: The purpose of this study is to develop a nanoemulsion formulation for its use as a transcutaneous vaccine delivery system.

Materials and methods: With bovine albumin-fluorescein isothiocyanate conjugate (FITC-BSA) as a vaccine model, formulations were selected with the construction of pseudo-ternary phase diagrams and a short-term stability study. The size of the emulsion droplets was furthered optimized with high-pressure homogenization. The optimized formulation was evaluated for its skin permeation efficiency. In vitro skin permeation studies were conducted with shaved BALB/c mice skin samples with a Franz diffusion cell system. Different drug concentrations were compared, and the effect of the nanoemulsion excipients on the permeation of the FITC-BSA was also studied.

Results: The optimum homogenization regime was determined to be five passes at 20?000?psi, with no evidence of protein degradation during processing. With these conditions, the particle diameter was 85.2?nm?±?15.5?nm with a polydispersity index of 0.186?±?0.026 and viscosity of 14.6 cP?±?1.2 cP. The optimized formulation proved stable for 1 year at 4?°C. In vitro skin diffusion studies show that the optimized formulation improves the permeation of FITC-BSA through skin with an enhancement ratio of 4.2 compared to a neat control solution. Finally, a comparison of the skin permeation of the nanoemulsion versus only the surfactant excipients resulted in a steady state flux of 23.44?μg/cm²/h for the nanoemulsion as opposed to 6.10?μg/cm²/h for the emulsifiers.

Conclusion: A novel nanoemulsion with optimized physical characteristics and superior skin permeation compared to control solution was manufactured. The formulation proposed in this study has the flexibility for the incorporation of a variety of active ingredients and warrants further development as a transcutaneous vaccine delivery vehicle.     

Development of SiC/TiAl composites: processing and interfacial phenomena

The needs of the aerospace industry for materials with low density and suitable mechanical properties at elevated temperature have oriented research to TiAl/SiC intermetallic matrix composites. A fabrication method specific for such composites was developed in this study. Two types of long fibers that have been used are the BP SM 1240 and Textron SCS-6 silicon carbide monofilaments. To fabricate these composites, firstly, the arc spraying conditions have been optimized by preparing sprayed Ti–48Al–2V material on a steel substrate and both types of Ti–48Al–2V/SCS-6 and Ti–48Al–2V/SM 1240 monotapes. Secondly, we have investigated the conditions under which a Ti–48Al–2V alloy powder could be consolidated and the kinetics of fiber damage by chemical reaction with the TiAl base matrix observed during consolidation. Then composite samples have been fabricated by uniaxial hot pressing of monotapes. In both composites, an interaction occurs between the fiber and the matrix and the reaction zone thickness follows approximately a parabolic growth law. It was determined that the plasma spray process is well adapted to produce titanium aluminide matrix composites. However, efforts are in progress to solve some of the problems inherent in the choice of the fiber, matrix and interfacial characteristics.     

Benzyloxybenzaldehydethiosemicarbazone: Extractive Spectrophotometric Reagent for the Determination of Cu(II) in Food and Water Samples

Benzyloxybenzaldehydethiosemicarbazone (BBTSC) was prepared and developed a new method for the simple, highly selective, and extractive spectrophotometric determination of copper(II) with BBTSC at wavelength 370 nm. The metal ion formed a bluish green colored complex with BBTSC in acetate buffer of pH 5.0, which was easily extractable into n-butanol with 1:1(metal/ligand) composition. The method obeys Beer’s law in the range of 0.5–5.2 ppm. The molar absorptivity and Sandell’s sensitivity were found to be 1.5 × 10⁴ l mol⁻¹ cm⁻¹ and 0.00412 g cm⁻², respectively. The correlation coefficient of the Cu(II)–BBTSC complex was 0.998, which indicated an excellent linearity between the two variables. The repeatability of the method was checked by finding the relative standard deviation (RSD; n = 10), which was 0.377% and its detection limit 0.0204 μg ml⁻¹. The interfering effect of various cations and anions were also studied. The proposed method was successfully applied to the determination of copper(II) in food and water samples. Comparing the results with those obtained using an atomic absorption spectrophotometer tested the validity of the method.     

Prediction of two‐phase pressure drop and liquid holdup in co‐current gas–liquid downflow of air–Newtonian systems through packed beds

The dependency of pressure drop and liquid holdup on phase velocities, geometry of the column and packing materials as well as on the physical properties have been analyzed. Our experimental data (825 data points obtained using four liquid systems and three different particles) along with those of the available literature (776 data point from five different sources) were used for the analysis. The applicability and the limitations of the literature correlations were evaluated using the available data. Based on the analysis, new correlations for the estimation of pressure drop and liquid holdup, valid for low and high interaction regimes have been developed using the available data, with a wide range of variables. Copyright © 2005 Society of Chemical Industry