Electrical Conduction in Single-Crystal Thallic Oxide: I, Crystals "As-Grown" from the Vapor in Air

Thallic oxide, "T1₂O₃," has been shown to be a degenerate n -type semiconductor with resistivity varying from 60 to 150 μΩ-cm over the range 4° to 900°K. The carrier concentration was 7 × 10²⁰ cm⁻³ and is temperature independent. Room-temperature Hall mobility was 105 cm² V⁻¹ s⁻¹, increasing to 130 cm² V⁻¹ s⁻¹ below 70°K. Donor states were shown to be native defects, probably oxygen vacancies.     

Electrode impedance parameters and internal resistance of a sealed LiC/Li1-xCoO2 lithium-ion rechargeable battery

The individual electrode impedance parameters and internal resistance of a sealed LiC/Li1-xCoO2 lithium-ion rechargeable battery were estimated by a galvanostatic nondestructive technique. Various resistive components of the battery were found to be minimum between state-of-charge values 0.5–0.9. It is expected that the operation of the battery within about 50% of its depth-of-discharge would prolong the charge/discharge cycle life of the battery.     

RHEOLOGICAL CHARACTERIZATION OF BUTTER USING LUBRICATED SQUEEZING FLOW

Rheological characteristics of butters made from anhydrous milk fat (AMF) and supercritically fractionated high melting triglyceride (HMT) fraction were compared. An Instron Universal Testing Machine was used to compress the samples between two lubricated plates at constant deformation rate (0.5 mm/min). Stress growth coefficients, computed from the ratios of stresses and biaxial strain rates, were plotted as function of time. HMT butter had higher stress growth coefficients than AMF butter, indicating its greater degree of firmness. Stress growth coefficients were negatively correlated to temperature due to lower crystallinity of fat at higher temperatures and increased on storage due to formation of weak van der Waal forces of attraction between crystalline fat chains.     

Analysis of electrical explosion of wire systems for the production of nanopowder

Nanoscience and nanotechnology continue to grow as fields of scientific research and commercial development as many fundamental properties are size dependent on the nano scale. There are so many techniques for the production and characterization of various ultra fine powders. To gain a fundamental understanding of size dependant properties of matter in the nanometer size regimes and to develop nanoscale materials into useful devices to benefit society requires detailed study of the experimental methods, better methods of sample preparation of mono dispersed material in large quantities, and development of nanoparticles characterization methods. Exploding wire method is one such method for the production of metal and metal oxide nanoparticles capable of producing bulk amount of metal nanoparticles at low cost. With the intention of developing better exploding wire system for the production of nanoparticle and to understand the nanoparticle formation process, we have developed two systems in the way of optimization of the experimental set-up for final production of nanoparticles. The detail analysis of the systems and its effect on the nanoparticles has been described in the paper.     

Pt–Ru decorated self-assembled TiO2–carbon hybrid nanostructure for enhanced methanol electrooxidation

Porous titanium oxide–carbon hybrid nanostructure (TiO₂–C) with a specific surface area of 350 m²/g and an average pore-radius of 21?·?8 Å is synthesized via supramolecular self-assembly with an in situ crystallization process. Subsequently, TiO₂–C supported Pt–Ru electro-catalyst (Pt–Ru/TiO₂–C) is obtained and investigated as an anode catalyst for direct methanol fuel cells (DMFCs). X-ray diffraction, Raman spectroscopy and transmission electron microscopy (TEM) have been employed to evaluate the crystalline nature and the structural properties of TiO₂–C. TEM images reveal uniform distribution of Pt–Ru nanoparticles (d _Pt???Ru ?=?1·5–3·5 nm) on TiO₂–C. Methanol oxidation and accelerated durability studies on Pt–Ru/TiO₂–C exhibit enhanced catalytic activity and durability compared to carbon-supported Pt–Ru. DMFC employing Pt–Ru/TiO₂–C as an anode catalyst delivers a peak-power density of 91 mW/cm² at 65 °C as compared to the peak-power density of 60 mW/cm² obtained for the DMFC with carbon-supported Pt–Ru anode catalyst operating under similar conditions.     

Radiation resistance of a cylindrical antenna immersed in a weakly ionized magnetoplasma. II†

The field components for electromagnetic and eletromagnetic waves from a cylindrical antenna radiating in a weakly ionized magnetoplasma and expressions for radiation resistances assuming sinusoidal current distribution in the antenna have been obtained. The effect of a steady magnetic field on the radiation resistances has been discussed. it has been concluded that the magnetic field changes considerably the radiation characteristics of an antenna.     

Effects of Mechanical Processing on Semiconducting Properties of Barium Titanate

Semiconducting barium titanate elements with positive temperature coefficient of resistance (PTCR) are usually subjected to different degrees of stress levels during processing operations like grinding, ultrasonic drilling, and slicing, etc. In this work we have examined the influence of these operations on the semiconducting properties of PTCR barium titanate using X-ray diffraction and electrical resistivity measurements.     

Computational study on effects of rib height and thickness on heat transfer enhancement in a rib roughened square channel

A computational study was carried out for the heat transfer augmentation in a three-dimensional square channel fitted with different types of ribs. The standard k–ε model and its two variants (RNG and realizable) were used for turbulence modeling. The predictions were compared with available experimental and computational results. Three rib configurations were used in the present study: 90° continuous attached ribs, 60° V-shaped broken attached thick and thin ribs. It was observed that the maximum heat transfer occurs at the normalized rib spacing (p/e) = 10 in the case of 90° attached ribs. The effects of the blockage ratio and rib thickness were investigated for 60° V-shaped broken ribs with Re = 10,000–30,000 and p/e = 10. It was observed that the average Nusselt number decreases with an increase in the Reynolds number for almost all configurations studied in the present study. For the 60° V-shaped broken ribs, increasing the blockage ratio had an adverse effect on the heat transfer. It was also observed that thin ribs perform better than thick ribs.     

Electrical Conduction in Single-Crystal Thallic Oxide: II, Effects of Annealing at 923°K in Oxygen Pressures from 0.01 to 1 Atmosphere

The low-temperature conductivity of thallic oxide (Tl₂O₃) is relatively insensitive to the equilibrium partial pressure of oxygen during annealing at 923°K, i.e. the maximum variation is ∼15% over the range of 0.01 to 1 atm O₂, with a relative maximum occurring at ∼0.2 atm. The insensitivity in conductivity results from the compensating effects of increasing mobility and decreasing carrier concentration with increasing oxygen pressure during annealing. At low oxygen pressures, defect interactions complicate the interpretation of the measurements, but a calculated Fermi energy on the order of 0.8 eV is sufficiently close to other reported values to confirm the model of a highly degenerate semiconductor with a simple S-like conduction band described by a parabolic density-of-states function.     

Studies on the use of chhana and paneer whey in the preparation of puras (pancakes)

Puras (pancakes) are widely accepted traditional Indian foods. Studies were conducted on the use of chhana and paneer whey in the preparation of sweet and salty puras . Six samples of chhana and paneer whey were substituted in sweet and salty puras at different whey to water ratios (0 : 100, 20 : 80, 40 : 60, 60 : 40, 80 : 20, 100 : 0). The effects of chhana and paneer whey on sensory evaluation showed that sweet puras containing mixed milk chhana whey and salty puras containing cow's milk chhana whey scored highest with respect to appearance, body and texture, flavour and taste, and overall acceptability. In general, commercial samples scored less, which may be due to poor handling and maintenance of whey by commercial manufacturers. Whey substitutions also improved fat, total solids, protein and ash of both sweet and salty puras . It is interesting to note that none of sweet and salty pura samples was below the limits acceptable to the panellists. It can be thus concluded that chhana and paneer whey can be used successfully in the preparation of puras for value addition.