Mass transfer kinetics using two-site interface model for removal of Cr(VI) from aqueous solution with cassava peel and rubber tree bark as adsorbents

M. Vasudevan,P. S. Ajithkumar,R. P. Singh,N. Natarajan 대한환경공학회 2016 Environmental Engineering Research Vol.21 No.2

Present study investigates the potential of cassava peel and rubber tree bark for the removal of Cr (VI) from aqueous solution. Removal efficiency of more than 99% was obtained during the kinetic adsorption experiments with dosage of 3.5 g/L for cassava peel and 8 g/L for rubber tree bark. By comparing popular isotherm models and kinetic models for evaluating the kinetics of mass transfer, it was observed that Redlich-Peterson model and Langmuir model fitted well (R2 > 0.99) resulting in maximum adsorption capacity as 79.37 mg/g and 43.86 mg/g for cassava peel and rubber tree bark respectively. Validation of pseudo-second order model and Elovich model indicated the possibility of chemisorption being the rate limiting step. The multi-linearity in the diffusion model was further addressed using multi-sites models (two-site series interface (TSSI) and two-site parallel interface (TSPI) models). Considering the influence of interface properties on the kinetic nature of sorption, TSSI model resulted in low mass transfer rate (5% for cassava peel and 10% for rubber tree bark) compared to TSPI model. The study highlights the employability of two-site sorption model for simultaneous representation of different stages of kinetic sorption for finding the rate-limiting process, compared to the separate equilibrium and kinetic modeling attempts.

Experimental and finite element analysis of residual stress and distortion in GTA welding of modified 9Cr-1Mo steel

M. Zubairuddin,S. K. Albert,S. Mahadevan,M. Vasudevan,V. Chaudhari,V. K. Suri 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.12

In this paper, investigation of residual stress and distortion induced in 3 mm thick Modified 9Cr-1Mo steel plates during GTA weldingis carried out. SYSWELD software is used for the thermo-mechanical analysis. A 3D meshed model is created for the simulation anddouble ellipsoidal heat source distribution is used for the thermal analysis. Thermal cycles predicted near the fusion zone are comparedwith experimentally measured thermal cycles using thermocouples. Predicted residual stress profile across the fusion zone is comparedwith the measured profile using X-ray diffraction method. There is a good agreement between measured and predicted thermal cyclesand residual stress profile. Distortion of the weld joint is measured using vertical electronic height gauge. Finite element analysis of distortionof the weld joint is carried out by applying both large and small distortion theories. Comparison of experimental and numericalresults showed better accuracy if large distortion theory is applied.

Friction stir welding of F/M ODS steel plug and F/M steel tube

Kang, S.H.,Vasudevan, M.,Noh, S.,Jin, H.J.,Jang, J.,Kim, T.K. North-Holland ; Elsevier Science Ltd 2016 Fusion engineering and design Vol.109 No.1

Friction stir welding (FSW) was used for joining of oxide dispersion strengthened (ODS) steel plug and F/M steel tube. The dimensions of the tube included outer diameter of 7mm, wall thickness of 0.5mm. The objective was to find suitable process variables for gaining enough frictional heat from those thin and curved pieces. A specially designed jig was used for stabilization and slow rotation of tube during FSW. Additionally, the plug was designed to overlap the tube. Inconel 718 was used as FSW tool, the diameter was 3.5mm. The adequate rotation speed of the tool and jig were 1200rpm and 1.5rpm, respectively. The joining was successfully accomplished using above combination, showing a good possibility. The hoop stress tests of joint were conducted by blowing Ar gas into the tube, the flow rate of gas was 10MPa/min. The measured hoop stress was 70-90MPa, the value was at around 70% of the tube.

Growth and characterization of pure and doped bis thiourea zinc acetate: Semiorganic nonlinear optical single crystals

M. Lydia Caroline,S. Vasudevan 한국물리학회 2009 Current Applied Physics Vol.9 No.5

Metal–organic coordination complex single crystals bis thiourea zinc acetate (BTZA) and Cd2+ doped BTZA have been synthesized and grown successfully by slow-cooling technique from their aqueous solutions. Single crystals of pure and Cd2+ doped BTZA with dimensions of 35 × 4 × 2㎣ and 10 × 5 ×6㎣, respectively were obtained with well defined morphology. The as grown single crystals are characterized by single crystal XRD studies and melting point measurements which reveal the incorporation of metallic dopants has not changed the structure of the parent crystal. The powder X-ray diffractogram of the grown crystals has been recorded and the various planes of reflection identified shows shift in the peak positions. The metal coordination with thiourea through sulphur in pure and Cd2+ doped BTZA were ascertained by FTIR studies and optical absorption study to identify the UV cut-off range. The presence of metals in pure and Cd2+ doped BTZA crystal lattice were confirmed by atomic absorption spectroscopy (AAS). The thermal decomposition of pure and Cd2+ doped BTZA crystals were investigated by thermo gravimetric analyses (TGA) and differential thermal analysis (DTA) indicate that doped crystals are more stable than pure crystals. The dielectric response of the crystals were studied in the frequency range 100 Hz–5 MHz at different temperatures and the results are discussed. Second harmonic generation (SHG) measurement confirms that the pure and Cd2+ doped BTZA have nonlinear optical (NLO) property. Laser damage threshold value of 12.44 MW/㎠ has been determined using Q-switched Nd:YAG laser operating at 1064 nm and with 8 ns pulses in single shot mode for pure BTZA single crystal is reported for the first time. Metal–organic coordination complex single crystals bis thiourea zinc acetate (BTZA) and Cd2+ doped BTZA have been synthesized and grown successfully by slow-cooling technique from their aqueous solutions. Single crystals of pure and Cd2+ doped BTZA with dimensions of 35 × 4 × 2㎣ and 10 × 5 ×6㎣, respectively were obtained with well defined morphology. The as grown single crystals are characterized by single crystal XRD studies and melting point measurements which reveal the incorporation of metallic dopants has not changed the structure of the parent crystal. The powder X-ray diffractogram of the grown crystals has been recorded and the various planes of reflection identified shows shift in the peak positions. The metal coordination with thiourea through sulphur in pure and Cd2+ doped BTZA were ascertained by FTIR studies and optical absorption study to identify the UV cut-off range. The presence of metals in pure and Cd2+ doped BTZA crystal lattice were confirmed by atomic absorption spectroscopy (AAS). The thermal decomposition of pure and Cd2+ doped BTZA crystals were investigated by thermo gravimetric analyses (TGA) and differential thermal analysis (DTA) indicate that doped crystals are more stable than pure crystals. The dielectric response of the crystals were studied in the frequency range 100 Hz–5 MHz at different temperatures and the results are discussed. Second harmonic generation (SHG) measurement confirms that the pure and Cd2+ doped BTZA have nonlinear optical (NLO) property. Laser damage threshold value of 12.44 MW/㎠ has been determined using Q-switched Nd:YAG laser operating at 1064 nm and with 8 ns pulses in single shot mode for pure BTZA single crystal is reported for the first time.

Anti-Cell Proliferative Efficacy of Ferulic Acid Against 7, 12-dimethylbenz(a) Anthracene Induced Hamster Buccal Pouch Carcinogenesis

Prabhakar, M. Manoj,Vasudevan, K.,Karthikeyan, S.,Baskaran, N.,Silvan, S.,Manoharan, S. Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.10

The present study was designed to explore the anti-cell proliferative efficacy of ferulic acid by analysing the expression pattern of cell proliferative markers, proliferating cellular nuclear antigen (PCNA) and cyclin D1, in the buccal mucosa of golden Syrian hamsters treated with 7,12-dimethylbenz(a)anthracene (DMBA). Oral squamous cell carcinomas developed in the buccal pouch of hamsters using topical application of 0.5% DMBA three times a week for 14 weeks. Immunohistochemical (PCNA) and RT-PCR (Cyclin D1) analysis revealed over expression of PCNA and cyclin D1 in the buccal mucosa of hamsters treated with DMBA alone (tumor bearing hamsters). Oral administration of ferulic acid at a dose of 40 mg/kg bw to hamsters treated with DMBA not only completely prevented the tumor formation but also down regulated the expression of PCNA and cyclin D1. The results of the present study thus suggests that ferulic acid might have inhibited tumor formation in the buccal mucosa of hamsters treated with DMBA through its anti-cell proliferative potential as evidenced by decreased expression of PCNA and cyclin D1.

Influence of Low Nickel (0.09 wt%) Content on Microstructure and Toughness of P91 Steel Welds

B. Arivazhagan,M. Vasudevan,M. Kamaraj 대한금속·재료학회 2015 METALS AND MATERIALS International Vol.21 No.3

Modified 9Cr-1Mo (P91) steel is widely used as a high temperature structural material in the fabrication of power plant components. Alloying elements significantly influences the microstructure and mechanical properties of P91 steel weldments. The alloying elements manganese and nickel significantly influence the lower critical phase transformation temperature (AC1) as well as tempering response of welds. In the existing published information there was wide spread use of high Mn+Ni filler wire. In the present study, weldment preparation was completed using GTA filler wire having low Nickel content (Mn+Ni of 0.58 wt% including nickel content of 0.09 wt%). Microstructure and mechanical properties characterization was done. There is a requirement on minimum toughness of 47 Joules for P91 steel tempered welds at room temperature. Microstructural observation revealed that the GTA welds have low δ-ferrite content (< 0.5%) in the martensite matrix. In the as-weld condition, the toughness was 28 Joules whereas after PWHT at 760 °C-2 h it was 115 Joules. In the present study, toughness of low nickel weld was higher due to low δ-ferrite content (<0.5%), multipass grain refinement and weld metal deposition of single pass per layer of weldment.

Hepatoprotective Activity of Thespesia populnea Bark Extracts against Carbon Tetrachloride-Induced Liver Toxicity in Rats

R.Ilavarasan,M.Vasudevan,S.Anbazhagan,S.Venkataraman,S.K.Sridhar 한국생약학회 2003 Natural Product Sciences Vol.9 No.2

Factors Influencing Association of Intermediaries in the Supply Chain of Consumer Healthcare Brands

SURESH, A.S.,VASUDEVAN, M.,VINOD, Sharma Korea Distribution Science Association 2021 유통과학연구 Vol.19 No.1

Purpose: The rural market in India provides tremendous scope for FMCG consumer healthcare companies to market their products because of a significant increase of rural purchasing power. Many empirical studies in this area highlight the challenges and opportunities for marketers in the FMCG space. Research articles are not in abundance to understand intermediaries' expectations in the supply chain specific to consumer healthcare products. The existing literature did not significantly address the challenges of channel partners in the rural market. The present study aims to determine the retailer expectations from manufacturers and channel members' mutual expectations in the FMCG distribution channel. Research design and Methodology: The present study adopted a qualitative research methodology. Fifty respondents from each level of distribution channel such as super-stockist, distributors and retailers in central India were identified and an interview method was adopted to collect the data. Results: Nineteen factors were identified to influence the intermediaries for involvement in the business with any FMCG brand. Factors like Profit margin, reverse logistics, credit terms, return on investment, timely payments were crucial for managing the expectations of all intermediaries. This study provides academic as well as practical implications in terms of enabling the industry to align its channel management strategies accordingly.

THE INFLUENCE OF SUBSTRATE TEMPERATURE ON THE ELECTRICAL PROPERTIES OF ZnO FILMS PREPARED BY THE RF MAGNETRON SPUTTERING TECHNIQUE

K. SARAVANAKUMAR,V. SENTHILKUMAR,C. SANJEEVIRAJA,M. JAYACHANDRAN,V. GANESAN,RAUSHAN B. KOIZHAIGANOVA,T. VASUDEVAN,MU SANG LEE 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2008 NANO Vol.3 No.6

ZnO thin films were grown by the RF magnetron sputtering technique at different substrate temperatures, from RT to 300°C. The crystallite size was calculated from XRD and the grain size was measured from AFM for different substrate temperatures. The influence of the substrate temperature on the electrical properties of the films was investigated through the Hall effect, and conductivity studies were performed under UV light illumination. The conductivity and the carrier mobility of the films were found to increase with increasing substrate temperature, which can be due to the grain-boundary-dominated conduction mechanism. The thermal activation energy and photosensitivity of the films were calculated, and the results are presented in this paper.

Stress Corrosion Cracking Susceptibility of 316LN Grade Stainless Steel Weld Joint in Boiling Magnesium Chloride Hexahydrate Environment

R. Rajasekaran,A. K. Lakshminarayanan,M. Vasudevan,P. Vasantha Raja 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.11

The 316LN Stainless Steel (SS) weld joints were fabricated using Tungsten Inert Gas (TIG) Welding and Activated FluxTungsten Inert Gas (A-TIG) Welding techniques with suitable process parameters. Initially, basic mechanical properties wereevaluated across weld joints. Further microstructural study of the base metal, TIG, and A-TIG joints were accomplishedusing Optical Microscopy (OM), Transmission Electron Microscopy (TEM), and Scanning Electron Microscopy (SEM)techniques. The microstructural characterization revealed higher grain size variations at the fusion zone of the A-TIG jointdue to the slow cooling rate and reversed Marangoni convection effect. The Stress Corrosion Cracking (SCC) susceptibilityof the TIG and A-TIG welded joints was assessed using five different loading/Stress conditions. The constant load boiling45 wt% Magnesium Chloride Hexahydrate (MgCl2.6H2O) solution as per ASTM G36-94 standard was used to evaluate theSCC susceptibility of the welded joints. The SCC (crack initiation and propagation) of the base metal and welded jointsoccurred by the anodic dissolution and Hydrogen Induced Cracking mechanisms. For the welded joints additionally, thedissolution of the δ-ferrite increased the crack growth rate. The A-TIG joint exhibited lesser SCC resistance than the TIGjoint for the following major reasons: (i) Formation of the large dendrites (ii) Presence of the higher grain size variations atthe fusion zone. Moreover, both welded joints showed lesser SCC resistance than the base metal due to the dissolution ofthe δ-ferrite and the residual stress formation. The fractographic studies for the base metal, TIG, and A-TIG joints revealedthe brittle nature of transgranular SCC failure.