Antioxidant activity of two traditional Indian vegetables: Solanum nigrum L. and Solanum torvum L.

In the present study, chloroform, acetone, and methanol extracts of Solanum torvum and Solanum nigrum leaves and fruit were evaluated for their in vitro antioxidant activity using ferric reducing antioxidant power, 2,2-diphenyl-1-picryl-hydrazyl (DPPH), ABTS^·+, iron chelation, and antihemolytic activity. Among the various solvents used, the maximum yield was obtained in chloroform followed by acetone and methanol. The total phenolics were also significantly higher in the chloroform extracts and the in vitro antioxidant activity was shown to be highly dependant on the total phenolic content (p<0.01). The DPPH^· and 2,2′azinobis(3-ethylbenzothiozoline-6-sulfonic acid) diammonium salt (ABTS) cation radical scavenging activities were well proved with the ferric reducing antioxidant capacity of the extracts. The potential of multiple antioxidant activity of samples can be further evidenced by inhibition of reactive oxygen mediated erythrocyte cell lysis and metal ion chelating activity. In conclusion, the results presented here implied leaves and fruits of S. torvum and S. nigrum could be considered as health supplements and nutraceuticals/functional foods.     

Effect of various indigenous processing methods on the α‐galactoside and mono‐ and disaccharide content of an Indian tribal pulse,Mucuna pruriens var utilis

The effect of various treatments, such as soaking in different solutions, cooking of raw and soaked seeds, autoclaving of raw and soaked seeds, dehusking of water‐soaked seeds, fermentation of water‐soaked/dehusked seeds, autoclaving of fermented seeds, dry heating of raw seeds and germination, on the levels of mono‐ and disaccharides and α‐galactosides in two varieties of an Indian tribal legume, mucuna bean (Mucuna pruriens var utilis), was investigated. The levels of raffinose, stachyose and verbascose decreased under various treatments. Among the different soaking and cooking/autoclaving treatments, tamarind pulp extract soaking and sodium bicarbonate solution soaking followed by autoclaving procedures were the most effective for removing α‐galactosides (68.4–70.9 and 68.5–68.9% respectively). The lowest reduction of α‐galactosides (8.4–17.2%) was observed in dry‐heated samples. Germination for more than 72 h resulted in the highest reduction of total α‐galactosides (93.6 and 89.6% in white and black varieties respectively). During the germination process, glucose, fructose and sucrose concentrations increased significantly. © 2001 Society of Chemical Industry     

Application of discrete wavelet transform and Zhao-Atlas-Marks transforms in non stationary gear fault diagnosis

Gears are one of the most common mechanisms for transmitting power and motion.Studies on gear teeth contacts have been considered as one of the most complicated applications. Depending on the application, the speed and load conditions of teeth may cause several types of failures on teeth surface which leads to non stationary operating conditions. This paper is attempt to analyze the effectiveness of the new time-frequency distributions called the Zhao-Atlas-Marks (ZAM) distribution to enhance non stationary signal analysis for fault diagnosis in spur gears. Also the performance of ZAM with other methods like short term fourier transform (STFT) and discrete wavelet transform (DWT) is discussed in this paper.     

Synthesis of Mn doped ZnO nanocrystals by solvothermal route and its characterization

Undoped and Manganese doped Zinc Oxide were prepared by solvothermal technique. The structural analysis was carried out using X-ray diffraction. It showed that the undoped Zinc Oxide and Manganese doped Zinc Oxide nanocrystals to exhibit hexagonal wurtzite structure. Grain sizes were estimated from Atomic Force Microscopy and Transmission Electron Microscopy images. The surface morphological studies from Scanning Electron Microscope, Transmission Electron Microscope and Atomic Force Microscope depicted spherical particles with formation of clusters. The magnetic behavior studied by Vibrating Sample Magnetometer indicated paramagnetic behaviour. Hyperfine splitting is observed using Electron Spin Resonance studies.     

Effect of co-substitution of Mn and Al on thermoelectric properties of chromium disilicide

CrSi₂ was earlier reported to be an interesting thermoelectric material for high temperature applications because of its high oxidation resistance and good mechanical properties. In order to enhance its figure of merit, Mn at Cr site and Al at Si site were substituted into CrSi₂. Our results indicate that Cr_1?x Mn _x Si_2?x Al _x solid solutions exhibit significantly lower thermal conductivity and a higher figure of merit than CrSi₂.     

Characterization of proton exchange membranes based on SPSEBS/SPSU blends

Proton-conducting polymer membranes are used as an electrolytes in proton exchange membrane fuel cells (PEMFCs). The most widely used commercially available membrane electrolytes are perfluorosulfonic acid polymers, an expensive class of ionomers. In this study, the potential of polymer blends derived from sulfonated polystyrene ethylene butylene polystyrene (SPSEBS) and sulfonated polysulfone (SPSU) for use in electrolyte applications was examined. Although SPSEBS by itself exhibits good conductivity, flexibility, and chemical stability, it has poor mechanical stability. So, in an effort to improve the mechanical properties of SPSEBS while maintaining its good conductivity, it was blended with SPSU. SPSEBS/SPSU blends were therefore prepared by a solvent evaporation method, and the resulting blend membranes were characterized in terms of conductivity, ionic exchange capacity, and water uptake. Sulfonation was confirmed and the crystallinity of the blend membranes was studied by FTIR spectroscopy and X-ray diffraction. The morphologies of the membranes were studied by scanning electron microscope (SEM), and their thermal stabilities by TGA and DSC. Finally, the mechanical strength of SPSEBS was studied using a UTM (universal testing machine). This paper presents the results of recent investigations aimed at developing an optimized in-house membrane electrode assembly (MEA) preparation technique combining catalyst ink spraying and assembly hot pressing. Easy steps were chosen for this preparation technique in order to simplify the method, thus minimizing costs. The influence of MEA fabrication parameters like electrode pressing or annealing on the performance of the hydrogen fuel cell was studied by performing single cell measurements during H₂/O₂ operation. Carbon cloth was used as a gas diffusion layer (GDL), and the composition of the electrode ink was optimized to maximize fuel cell performance. A commercial E-TEK catalyst was used for the anode and cathode, with Pt loadings of 0.125 and 0.37 mg/cm², respectively. The MEA with the best performance delivered approximately 0.50 W/cm² at room temperature. The methanol permeability and the selectivity ratio strongly influenced DMFC performance. Both direct methanol fuel cells (DMFCs) and PEMFCs are discussed in this paper.     

Variable Parameter Muskingum Routing Considering Downstream Effects

Using a variable parameter Muskingum method, a procedure for discharge hydrograph routing in prismatic channels considering downstream effects is presented. The method involves a two step process: (1) a given routing reach is divided into a number of subreaches with each subreach having a representative unique stage–discharge relationship established by using a gradually varied flow profile estimation technique; and (2) the routing of a given inflow hydrograph through these subreaches successively using the variable parameter Muskingum method with parameter variation achieved using the established stage–discharge relationships pertinent to the subreaches and the assumptions of the routing method. The ability of this procedure to route floods accounting for downstream effects is demonstrated by routing a given hypothetical inflow hydrograph in three rectangular channels each with a reach length of 40?km, and for two different scenarios of downstream boundary conditions, one resulting in an M1 profile and another in an M2 profile with the control at the end of the 40?km reach. The M1 profile is formed due to the prescribed boundary condition at the outlet of the reach that the flow depth at that section is equal to twice the normal depth in the channel reach. The M2 profile is formed due to a free fall located at the outlet of the reach. The routing results obtained using this procedure are compared with the corresponding Saint-Venant solutions arrived at using the U.S. National Weather Service’s DAMBRK model, which is used as a benchmark. The performance of this discharge routing procedure compares well with the corresponding DAMBRK model solutions subject to the criterion ∣(1/S0)?y/?x∣<1 being satisfied.     

Spontaneous gradual accumulation of hexagonally-aligned nano-silica on gold nanoparticles embedded in stabilized zirconia: a pathway from catalytic to NH3-sensing performance

The present study highlights the influence of nano-impurities on the catalytic/sensing performance of nano-structured Au sensing-electrodes (SEs) housed in a quartz reactor and operated at high temperature over a long period of time. The planar sensor, made from a nano-structured Au-SE on a polished-polycrystalline (pp) yttria-stabilized zirconia (YSZ) substrate exhibited initially negligible electromotive force (emf) response to each of the examined gases (CO, CH(4), C(3)H(8), C(3)H(6), NO(x) and NH(3); 400 ppm each) at 700 °C in the presence of 5 vol.% oxygen and 5 vol.% water vapor. Such a poor emf response was attributed to the excellent gas-phase oxidation/reduction ability of Au nanoparticles embedded in the YSZ substrate at high temperature. The response of the planar sensor made up of nano-structured Au-SE was monitored for about 75 days at 700 °C. As a result of this long-term monitoring, we detected the appearance of highly sensitive and selective NH(3) gas-sensing properties after 45-75 days of sensor operation. Detailed observation of the morphology and composition of the as-fabricated nano-structured Au-SE after 75 days operation at 700 °C revealed the gradual accumulation of hexagonally-aligned SiO(2) nano-impurities on the surface of the Au nanoparticles. The NH(3) sensing mechanism of the YSZ-based sensor using the spontaneously-formed composite (nano-Au + nano-SiO(2))-SE is therefore proposed to be based on a strong acid-base interaction between gaseous NH(3) and SiO(2) nano-impurities, followed by spillover of adsorbed NH(3) towards the nano-Au/pp-YSZ interface.     

Rating Curve Development at Ungauged River Sites using Variable Parameter Muskingum Discharge Routing Method

A physically based simplified discharge routing method, namely, the variable parameter Muskingum discharge-hydrograph (VPMD) routing method, having the capability of estimating the stage hydrographs simultaneously in channels with floodplains is presented herein. The upstream discharge hydrograph is routed using this VPMD method in different two-stage symmetrical trapezoidal compound cross section channel reaches. The performance of the VPMD method is evaluated by numerical experiments using the benchmark MIKE11 hydrodynamic model and the field data of the Tiber River in central Italy. The proposed method is capable of accurately routing the discharge hydrographs, corresponding stage hydrographs and synthesizing the normal rating curves at any downstream ungauged river site which is not affected by any downstream effects. This study can be helpful for various planning and management of river water resources in both the diagnostic and prognostic modes.