Influence of age after pruning on the levels of flavanols and other bioconstituents in tea (Camellia sinensis)

The influence of age after pruning on the biochemical constituents such as catechin fractions, the key enzyme phenylalanine ammonia lyase (PAL) and other compounds which contribute to black tea quality as well as root carbohydrates was investigated. Analyses were done consecutively for 4 years after pruning. The concentration of total catechins was found to be highest in the ‘Cambod’ cultivar UPASI‐17, followed by UPASI‐3 and UPASI‐9 representing ‘Assam’ and ‘China’ jats respectively, under prevailing conditions. A concomitant increase in total catechin content was found up to 3 years followed by a decrease in the fourth year of the pruning cycle, irrespective of the cultivar. PAL, the precursor of catechin biosynthesis, also increased up to 3 years and showed a sharp decrease thereafter. On the other hand, the root carbohydrate reserve and the caffeine content of tea leaves increased steadily up to the fourth year. All the genotypes studied showed the same trend. However, variability in catechin contents was prominent in different clones. Copyright © 2005 Society of Chemical Industry     

Optical, thermal and phase transition studies in Sn1-x Ge x Te

The optical and thermal properties of the mixed semiconducting alloy, Sn_1-xGe_xTe, is studied by photo acoustics, for various Ge concentrations and phase transition for a particular concentration is also studied by the same method. The results are compared with the available literature values and discussed.     

Serotonin synthesis inhibition in olivo-cerebellar system attenuates harmaline-induced tremor in Swiss albino mice

Recent experimental evidences point to the active role of central serotonin (5-HT) elicited mechanisms in the pathogenesis of tremor. The present study was undertaken to investigate the effects of p-chlorophenylalanine (pCPA), a specific tryptophan hydroxylase inhibitor and a central 5-HT depletor, on the neurochemical processes that occur synchronously in olivary nucleus (ON) and cerebellum during harmaline-induced tremor in mice. Tremor appeared by 3-4 min following harmaline administration, and reached its peak by 25 min for the doses (10-30 mg/kg) studied. Peak of harmaline-tremor coincided with increases in 5-HT in ON and cerebellum, as assayed employing HPLC-electrochemistry. Administration of pCPA caused significant depletion in 5-HT level in both the regions analyzed, and also significantly inhibited harmaline-induced tremor. Our present results support the earlier electrophysiological evidences that harmaline-induced tremor originates from ON, and confirm the role of 5-HT in the genesis of this motor neuronal dysfunction.     

Effects of annealing on the properties of SnSe films

Tin selenide thin films were deposited potentiostatically from an unstirred aqueous solution containing Sn-EDTA and Na₂SeO₃ onto indium-doped tin oxide glass substrates. The difference in the structural and compositional properties of the film before and after heat treatment in a nitrogen atmosphere were studied. The as-grown and treated films were characterised using various techniques such as X-ray diffractometry, scanning electron microscopy and energy-dispersive X-ray analysis. Photoactivity of the samples was studied using linear sweep voltammetry. An annealing temperature of 150°C was found to be the optimum temperature.     

Charge density in MoO<Subscript>4</Subscript> tetrahedron and PbO<Subscript>8</Subscript> octahedron in PbMoO<Subscript>4</Subscript>

The precise electronic structure of lead molybdate (PbMoO₄) has been studied using powder X-ray data. The acousto-optical, photoconductivity, luminescence, ad thermoluminescence properties in PbMoO₄ in general, depend on the electron density distribution in the MoO₄ tetrahedron and PbO₈ octahedron. Hence, a complete analysis of the bonding interaction between Mo and O atoms in MoO₄ and Pb and O atoms in PbO₈ has been studied. The bonding between the atoms using the maximum entropy method (MEM) and bond length distribution using pair distribution function (PDF) has been analyzed. The valence state of oxygen atom is found to be responsible for the sensible properties in PbMoO₄. The particle size of PbMoO₄ is also analyzed using XRD and SEM. The band gap energy has also been calculated using UV–visible spectra. A study in terms of the local structure and electron density using versatile tools like MEM and PDF is lacking in literature. Hence this work complements these aspects.     

Multi response optimization of NOx emission of a stationary diesel engine

In the present work the combined effect of fuel injection timing, percentage of EGR and fuel injection pressure in controlling the NO_x emission of a stationary diesel engine fuelled with diesel was investigated. Three levels were chosen in each factor and NO_x emission, smoke concentration and brake fuel conversion efficiency are taken as the response variables. Experiments were designed as per Taguchi’s L₉ orthogonal array and tests were conducted with different injection timings, percentage EGR (by volume) and injection pressures. Multi response signal to noise ratio (MRSN) was calculated for the response variables and the optimum combination level of factors was obtained simultaneously using Taguchi’s parametric design. Obtained combination was confirmed experimentally and significant improvement was observed in the response variables.     

Influence of triethylamine on the anodic dissolution characteristics of Ni,Cu and their alloys in non-aqueous solvents containing fluoride media: voltammetric and surface morphologic study

Multisweep cyclic voltammetric (CV) responses of nickel, copper, Monel and nickel–copper alloy had been extensively studied and compared in different non-aqueous solvents, such as acetonitrile (AN), propylene carbonate (PC) and sulpholane-containing anhydrous hydrogen fluoride (AHF) medium in the absence and the presence of triethylamine (Et₃N). The quantity of dissolution and surface morphological transformation on the electrodes as a result of anodic polarisation were investigated by means of atomic absorption spectroscopy and scanning electron microscopy (SEM), respectively. The CV study indicates that Ni, Cu and their alloys are highly unstable in AN/AHF medium. Surface morphology of Ni after polarisation in this medium reveals the generation of number of pits, whereas the evolution of small crystallites of CuF₂ is noted on the polarised alloy material, as evidenced by SEM pictures. The dissolution characteristics decrease significantly in PC/AHF medium and become low in sulpholane-containing fluoride medium on the four electrodes. The relative solubility of metal fluoride film in the three solvents increases in the order: sulpholane < PC < AN. The voltammograms suggest that addition of Et₃N (0.5 M) to AN- and PC-containing AHF medium helps both in maintaining uniform dissolution and generating compact fluoride film on the electrode surface. The addition of Et₃N to AHF/sulpholane medium shows only little influence in improving the electrocatalytic oxidation process.     

Shear flexible field‐consistent curved spline beam element for vibration analysis

In this paper, an efficient curved cubic B‐spline beam element is developed based on the field consistency principle, for vibration analysis. The formulation is general in the sense that it includes anisotropy, transverse shear deformation, in‐plane and rotary inertia effects. The element is based on laminated refined beam theory, which satisfies the interface transverse shear stress and displacement continuity, and has a vanishing shear stress on the top and bottom surfaces of the beam. The lack of consistency in the shear and membrane strain field interpolations in their constrained physical limits causes poor convergence and unacceptable results due to locking. Hence, numerical experimentation is conducted to check these deficiencies with a series of assumed shear/membrane strain functions, redistributed in a field‐consistent manner. The performance of the element is assessed by studying the free vibration behaviour of a variety of problems ranging from a straight beam to a circular ring. Copyright © 1999 John Wiley & Sons, Ltd.     

Study of plasma- and detonation gun-sprayed alumina coatings using taguchi experimental design

Atmospheric plasma spraying (APS) is a most versatile thermal spray method for depositing alumina (Al₂O₃) coatings, and detonation gun (D-gun) spraying is an alternative thermal spray technology for depositing such coatings with extremely good wear characteristics. The present study is aimed at comparing the characteristics of Al₂O₃ coatings deposited using the above techniques by using Taguchi experimental design. Alumina coating experiments were conducted using a Taguchi fractional-factorial (L₈) design parametric study to optimize the spray process parameters for both APS and D-gun. The Taguchi design evaluated the effect of four APS and D-gun spray variables on the measured coating attributes. The coating qualities evaluated were surface roughness, porosity, microhardness, abrasion, and sliding wear. The results show that the coating quality is directly related to the corresponding coating microstructure, which is significantly influenced by the spray parameters employed. Though it is evident that the D-gun-sprayed coatings consistently exhibit dense and uniform microstructure, higher hardness, and superior tribological performance, the attainment of suitable plasma-sprayed coatings can be improved by employing the Taguchi analysis.