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Open access

G. Thilakavathi, R. Arun Kumar and V. Gunasekaran

Abstract

Single crystals of pure and L-threonine added tartaric acid (LT/TA), organic nonlinear optical (NLO) materials were grown from their respective aqueous solution by slow evaporation method. The crystalline nature of the grown crystals was confirmed by powder X-ray diffraction analysis (XRD). UV-Vis-NIR absorption and transmission spectra revealed that the lower cut-off wavelength was around 281 nm and the crystals exhibited high transmission over visible and near IR region. The presence of the functional groups such as O–H, C–H, C–O, C=O in the grown crystals was confirmed by FT-IR analysis. CHN analysis was carried out to confirm the presence of L-threonine in the grown crystals. Microhardness study on the crystals revealed that the hardness number Hv increased with the applied load. The growth pattern of the crystals were analyzed through etching analysis from which the etch patterns in the shape of ‘step-triangle’ were observed. The second harmonic generation (SHG) properties of pure and L-threonine doped tartaric acid crystals were confirmed by Kurtz-Perry powder technique.

Open access

P. Thamilarasu, G. Kumar, R. Tamilarasan, V. Sivakumar and K. Karunakaran

Kinetic, Equilibrium and Thermodynamic studies on the removal of Cr(VI) by activated carbon prepared from Cajanus Cajan(L) Milsp seed shell

This paper presents the feasibility of the removal of hexavalent chromium ions from aqueous solutions by using activated carbon prepared from Cajanus Cajan(L) Milsp. It was carbonized and activated by treating it with concentrated sulfuric acid followed by heating for 5 h at 500°C. Batch adsorption experiments were carried out as a function of pH, contact time, initial concentration of the adsorbate, adsorbent dosage and temperature. The experimental data fitted well to the Freundlich isotherm. The thermodynamic parameters such as ΔH°, ΔS°, and ΔG° were calculated, which indicated that the adsorption was spontaneous and endothermic in nature. The adsorbent used in this study was characterized by FT-IR and SEM before and after the adsorption of metal ions. The results indicate that Cajanus Cajan(L) Milsp can be employed as a low cost alternative and commercial adsorbents in the removal of chromium (VI) from water and waste water.

Open access

R. Singh and V. Kumar

Abstract

In this study an eigen value approach has been employed to examine the mechanical force applied along with a transverse magnetic field in a two dimensional generalized magneto micropolar thermoelastic infinite space. Results have been obtained by treating rotational velocity to be invariant. Integral transforms have been applied to solve the system of partial differential equations. Components of displacement, normal stress, tangential couple stress, temperature distribution, electric field and magnetic field have been obtained in the transformed domain. Finally numerical inversion technique has been used to invert the result in the physical domain. Graphical analysis has been done to described the study.

Open access

Vikrant Tyagi, Krishan Kumar and V.K. Jain

Abstract

Noise measurements have been carried out at eleven different sites located in three prominent cities of the Tarai region of India to evaluate the effectiveness of vegetation belts in reducing traffic noise along the roadsides. Attenuation per doubling of distance has been computed for each site and excess attenuation at different 1/3 octave frequencies has been estimated. The average excess attenuation is found to be approximately 15 dB over the low frequencies (200 Hz to 500 Hz) and between 15 dB to 20 dB over the high frequencies (8 kHz to 12.5 kHz). Over the critical middle frequencies (1-4 kHz), the average excess attenuation (between 10-15 dB) though not as high, is still significant, with a number of sites showing an excess attenuation of 15 dB or more at 1 kHz. The results indicate that sufficiently dense vegetation belts along the roadsides may prove as effective noise barriers and significant attenuation may be achieved over the critical middle frequencies (1-4 kHz).

Open access

B Kumar, K Lakshman, V Swamy, P Kumar, D Shekar, B Manoj and G Vishwantha

Hepatoprotective and Antioxidant Activities of Amaranthus viridis Linn

Aim: To study heaptoprotective activity of methanolic extract of whole plant of Amaranthus viridis Linn (MeAv) in paracetamol (PCM) induced hepatotoxicity.

Materials and Methods: MeAv was screened for hepatoprotective activity in PCM (3 g/kg) induced hepatotoxicity in Wistar rats for 15 days at dose of 200 and 400 mg/kg by measuring liver marker enzymes (serum glutamate pyruvate transaminase and serum glutamate oxaloacetate transaminase), bilirubin (total bilirubin and direct bilirubin) and albumin (ALB), total protein (TP) levels and histopathological studies. Antioxidant activities were studies by measuring malondialdehyde (MDA), reduced glutathione (GSH), catalase (CAT) and total thiols (TT) in liver homegenate of treated animals.

Results: MeAv significantly (p<0.001) decreases the elevated liver marker enzymes (serum glutamate pyruvate transaminase and serum glutamate oxaloacetate transaminase), bilirubin (total bilirubin and direct bilirubin) and restores albumin (ALB), total protein (TP) levels. A histopathological study also showed liver protective activity of MeAv. In in vivo antioxidant studies, the MeAv has significantly restored the malondialdehyde (MDA), reduced glutathione (GSH), catalase (CAT) and total thiols.

Conclusion: In conclusion, administration of MeAv for 15 days showed liver protective activity against paracetamol induced liver damage and the potential antioxidant property of MeAv thought to be the mechanism behind its hepatoprotective activity.

Open access

V. Kumar and R. Singh

Abstract

A two dimensional Cartesian model of a generalized thermo-microstretch elastic solid subjected to impulsive force has been studied. The eigen value approach is employed after applying the Laplace and Fourier transforms on the field equations for L-S and G-L model of the plain strain problem. The integral transforms have been inverted into physical domain numerically and components of normal displacement, normal force stress, couple stress and microstress have been illustrated graphically.

Open access

Vinayak Hemant Kumar, N.A.K Sivaa Senthil and T V Pradeep Kumar

Abstract

A simple and direct Strut-and-Tie Model (STM) is proposed here to predict the ultimate shear strength of the reinforced concrete bridge pier cap for shear span to depth ratio of 0.4 to 2.4. The model is based on the Kupfer-Gerstle Biaxial Compression-Tension failure criterion which includes the concrete softening effect produced by the presence of transverse tensile stress. The earlier models consider the stress distribution factor for the varied stress distribution across the section by assuming it as linear function which is derived by satisfying equilibrium conditions. In this study the principal stresses have been evaluated by satisfying the compatibility condition at the time of impending failure which has been accounted for the effective area of concrete resisting tension. Also the softening effect has been included by using the formula for tensile strength of cracked concrete proposed by Belarbi and Hsu. The proposed model has been validated with 43 experimental results by author and from literature which confirm the coherency and conservativeness of the predicted results. The parametric study on ultimate shear strength is done so as to infer the relation between various abstract quantities such as compressive strain, shear capacity, span depth ratio and other material properties and get a deeper insight into the behavior of the Pier cap. Thus this paper tries to extend the practical application of Strut-and-Tie Model for reinforced concrete bridge pier cap in understanding the actual behavior of the structure on various dimensional and material parameters.

Open access

R. Singh and V. Kumar

Abstract

The eigen value approach, following the Laplace and Hankel transformation has been employed to find a general solution of the field equations in a generalized thermo microstretch elastic medium for an axisymmetric problem. An infinite space with the mechanical source has been applied to illustrate the utility of the approach. The integral transformations have been inverted by using a numerical inversion technique to obtain normal displacement, normal force stress, couple stress and microstress in the physical domain. Numerical results are shown graphically

Open access

V.A. Kiran Kumar, Vissa Shanti, Yaswanth Sandeep, Jatinder Kumar Mittal and Amit Agrawal

Open access

R.V.M.S.S. Kiran Kumar and S.V.K. Varma

Abstract

The hydromagnetic nanofluid flow over a stretching sheet in a porous medium with variable wall thickness in the presence of Brownian motion and thermophoresis is investigated. The heat transfer characteristics with variable conductivity are explored by using Cattaneo-Christov heat flux model. The governing non-linear ordinary differential equations are solved by using boundary value problem default solver in MATLAB bvp4c package. The impact of various important flow parameters on velocity, temperature and nanoparticle concentration as well as the friction factor coefficient and the rate of heat and mass transfer coefficients are presented and discussed through graphs and tables. It is found that the fluid velocity is accelerated with an increase in wall thickness parameter for n > 1, while the reverse trend is observed for n < 1.