Kinetic analysis of gluconic acid production by Pseudomonas ovalis

A simple growth model is proposed on the basis of the reaction scheme for the conversion of glucose to gluconic acid. The model considers the combined effects of both glucose and oxygen substrates. Kinetic analysis of the system has been made. Computer solution of the equations proposed are obtained and the adequacy of the models confirmed.     

Effect of microstructure on mechanical properties of refractory Co-Cr-W-Ni alloy

A cobalt-base refractory alloy containing W, Ni, and Cr, which is widely used for making spacecraft components operating at high temperatures, is studied. Changes in the microstructure of the alloy are studied depending on the heat treatment, and the effect of these changes on mechanical properties at room and high temperatures is determined.     

Studies on jute–asphalt composites

The tensile properties of jute make it a suitable raw material for asphalt overlay (A/O) fabric. In this study, the thermal stability of jute under conditions of asphalt overlaying process was investigated and the compatibility of jute with asphalt was assessed through experimentation on jute–asphalt composites under mechanical and hygral loads. Fourier transform infra red (FTIR) spectroscopic study revealed probable chemical bonding between jute and asphalt. The test for ascertaining the capability of asphalt encasement for protecting jute against biodegradation under enzymatic attack was found positive. A 6‐month hygral treatment, of the jute–asphalt composite, showed significant increase in modulus of the material. The results indicate that although the strength of jute deteriorates by about 10% under asphalt overlaying condition, the overall tensile behavior of jute fabric–asphalt composite material is considerably superior to that of the pure jute fabric, even under biological and extended hygral loading conditions. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

A study on dynamic friction of different spun yarns

This article presents the results from a study of yarn-to-yarn (YY) and yarn-to-metal (YM) frictions conducted on ring, rotor, air-jet, and open-end friction (OE friction) spun yarns at different relative speeds and input tensions. The results indicate that the behavior of frictions for YY is different than that of YM. In case of YY friction, OE friction yarn shows maximum friction followed by rotor, air-jet, and ring spun yarns; however, a reverse order is noticed for YM friction. The relative speed and input tension have significant influence on the frictional behavior of spun yarns. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Large-scale electrochemical synthesis of SnO2 nanoparticles

Tin oxide nanoparticles were synthesized by electrochemical oxidation of a tin metal sheet in a non-aqueous electrolyte containing NH₄F. The as-prepared nanoparticles were then thermally annealed at 700 °C for 6 h. The resulting particles were characterized by a variety of experimental techniques, including X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), Raman, UV-visible, and photoluminescence (PL) spectroscopy. The XRD patterns clearly showed that the amorphous phase of the as-synthesized SnO₂ particles was transformed into a rutile-type crystalline structure after thermal treatment; and from the line broadening of the XRD peaks, the average size of the annealed particles was found to be 15.4, 12.5, 11.8 nm for the particles initially synthesized at 20, 30, and 40 V, respectively. Consistent results were also observed in HRTEM measurements which showed clear crystalline lattice fringes of the calcined nanoparticles, as compared to the featureless profiles of the as-produced counterparts. In Raman spectroscopic studies, three dominant peaks were observed at 480, 640, and 780 cm⁻¹ which were ascribed to the E_1g, A_1g, and B_2g Raman active vibration modes, respectively, and the wavenumbers of these peaks blue-shifted with decreasing particle size. Additionally, a broad strong emission band was observed in room-temperature photoluminescence measurements.     

Synthesis of titanium oxide and titanium nitride nano-particles with narrow size distribution by supersonic thermal plasma expansion

The paper reports the synthesis of nano-crystalline ceramics like titanium dioxide and titanium nitride using a plasma chemical experimental reactor powered by a multi-segment (cascaded) arc plasma torch. The precursor-laden plasma beam emerging from the torch anode section expands supersonically through a converging nozzle to a low-pressure collection chamber. This results in a uniform and controlled gas dynamic quenching ensuring rapid synthesis of pure, un-coagulated free-flowing particles with a narrow size distribution. Simple Langmuir probes and calorimetric energy balance methods are used for plasma and reactor characterization, while X-ray diffraction (XRD), transmission electron microscopy (TEM), dynamic light scattering (DLS), Raman and X-ray photoelectron spectroscopy (XPS) techniques have been used for product analysis. It is shown that size distribution of both the product particles is comparatively narrower than that found in most thermal plasma assisted laboratory synthesis studies. The expansion process was observed to produce a non-equilibrium electron population, which could charge up the particles after nucleation and hence could curb unwanted coagulation.     

Study of standard heat treatment on mechanical properties of Inconel 718 using ball indentation technique

The effect of standard heat treatment on the microstructure and mechanical properties of Ni–Fe base super-alloy, Inconel 718 was studied by optical microscopy and ball indentation technique (BIT) using small amount of specimen. In order to get good ductility, good formability, yield, tensile and creep rupture, as-received material was given the standard heat treatment, viz solution treatment at two temperatures 940 °C and 1040 °C for1 h and water quenched (WQ) followed by aging treatment at 720 °C for 8 h. and furnace cooling (FC). The BIT has revealed that the strengths for as-received material are maximum compared to other heat-treated materials. After solution treatment there has been a radical decline in strength. But the ageing causes a significant enhancement of strength. Optical microscopy studies supported the obtained BIT results. γ″-phase is the basic strengthening phase in 718 alloys.     

<Emphasis Type=Bold>Analysis of Spatio-temporal Characteristics and Regional Frequency of Droughts in the Southern Peninsula of India</Emphasis>

A detailed regional drought study is carried out in the southern peninsula of India to characterize the spatio-temporal nature of droughts and to predict the drought magnitudes for various probabilities in the homogeneous drought regions. The method of several random initializations of the cluster centres of the K-means algorithm is suggested for the identification of the initial regions in the context of drought regionalization, which is shown to perform better than the initialization from the Ward’s algorithm and the Ward’s algorithm itself. The peninsula is classified into seven spatially well-separated homogeneous drought regions. The robust L-moment framework is used for the regional frequency analysis of drought magnitudes computed using the standardized precipitation index. The Pearson type III is found to be appropriate for regional drought frequency analysis in six of the regions, while the robust Wakeby distribution is suggested for one region. Low magnitude droughts are frequent and dominant in the northern part of west coast, the north-eastern coast and its adjoining inland region, while high magnitude droughts are less in number and are experienced in semi-arid central part, southern part of western coast, south-eastern part and north-western inland region. The spatial maps of drought magnitudes indicate that at higher return periods (100 and 200 years) the south-eastern part of the peninsula is likely to encounter high magnitude droughts, while the central region is likely to experience the same at lower return periods (10 and 50 years). Hence these regions need to be given special importance in the drought mitigation planning activities.     

Turbulent natural convection heat transfer from a vertical plate to the power-law fluid at high prandtl numbers

A simple analytical technique for turbulent natural convection heat transfer from an isothermal vertical plate to a power-law fluid is developed. The model is based on the assumption that the turbulent heat transfer rate is controlled by the flow characteristic near the surface in the limit of large Prandtl numbers. The formulation proposed in this work agrees well with the correlations available in the literature.     

Synthesis and Characterization of Homo Polymer of Acrylate of Mixed Alcohols (Decyl,Dodecyl, and Myristyl Alcohol)—A Potential Pour Point Depressant for Lubricating Oils

Polymer of the acrylate of a mixture of three different alcohols, decyl alcohol, dodecyl alcohol, and myristyl alcohol, and the respective homopolymers, poly(decylacrylate), poly(dodecylacrylate), and poly(myristylacrylate), were synthesized, characterized, and evaluated for their performances (oil thickening and pour point depression property) as lube oil additive. The viscosity measurements of the synthesized polymers in the toluene solution at 313 K were performed and compared.