Synthesis, structure stability and magnetic properties of nanocrystalline Ag-Ni alloy

Santhi, Kalavathy,Thirumal, E.,Karthick, S. N.,Kim, Hee-Je,Nidhin, Marimuthu,Narayanan, V.,Stephen, A. Springer-Verlag 2012 Journal of nanoparticle research Vol.14 No.5

Moringa Oleifera, A Biosorbent for Resorcinol Adsorption-Isotherm and Kinetic Studies

M. Helen Kalavathy,G. Swaroop,E. Padmini,Miranda Lima Rose 한국탄소학회 2009 Carbon Letters Vol.10 No.1

The adsorption of phenolic compound resorcinol on activated carbons prepared from Moringa oleifera (Drumstick bark) has been investigated. Activated carbon was prepared by impregnating Moringa oleifera with 50% phosphoric acid in the ratio of 1:1 and 1:2(w/w), designated as MOAC1 and MOAC2. Equilibrium and isotherm studies were carried out. The influences of variables such as contact time, initial concentration of resorcinol, carbon dosage in the solution on percentage adsorption and adsorption capacity of the bark have been analysed. The equilibration time was found to be 4 h. Kinetics of resorcinol onto activated carbons was checked for pseudo first order and pseudo second order model. It was found that the adsorption of resorcinol follows pseudo second order kinetics for both MOAC1 and MOAC2. The isotherm data were correlated with isotherm models, namely Langmuir and Freundlich. Adsorption isotherms were satisfactorily fitted by both the Langmuir and Freundlich model for MOAC1 and MOAC2.

Surface Modified Agave sisalana as an Adsorbent for the Removal of Nickel from Aqueous Solutions : Kinetics and Equilibrium Studies

E. Padmini.,M. Helen Kalavathy,Miranda Lima Rose 한국탄소학회 2008 Carbon Letters Vol.9 No.2

In the present study Sisal fiber obtained from the leaves of Agave sisalana has been chosen to validate its viability as an adsorbent for the removal of Nickel from aqueous solutions. The material was also surface modified and its effect on adsorption of Nickel was also studied. Agave sisalana fiber was found to be a cheap and effective adsorbent doing away with the need to activate the material therby reducing processing cost. The equilibrium studies indicated that the adsorption capacity of raw fiber and the surface modified fiber was 8.66 and 9.77 mg/g respectively with the Langmuir isotherm describing the adsorption phenomena better than the Freundlich and Temkin isotherm. The adsorption was found to be exothermic from the thermodynamic studies and the kinetics showed that the adsorption phenomena were second order.

Surface Modified Agave sisalana as an Adsorbent for the Removal ofNickel from Aqueous Solutions - Kinetics and Equilibrium Studies

Padmini. E,Helen Kalavathy M,Lima Rose Miranda 한국탄소학회 2008 Carbon Letters Vol.9 No.2

In the present study Sisal fiber obtained from the leaves of Agave sisalana has been chosen to validate its viability as anadsorption of Nickel was also studied. Agave sisalana fiber was found to be a cheap and effective adsorbent doing away withthe need to activate the material therby reducing processing cost. The equilibrium studies indicated that the adsorptioncapacity of raw fiber and the surface modified fiber was 8.66 and 9.77 mg/g respectively with the Langmuir isothermdescribing the adsorption phenomena better than the Freundlich and Temkin isotherm. The adsorption was found to beexothermic from the thermodynamic studies and the kinetics showed that the adsorption phenomena were second order.

Antifouling properties of poly(vinylidene fluoride)-incorporated cellulose acetate composite ultrafiltration membranes

Manikandan Gomathy Nainar,Kalidass Jayaraman,Helen Kalavathy Meyyappan,Lima Rose Miranda 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.12

Poly(vinylidene fluoride) (PVDF) was incorporated in Cellulose acetate (CA) to prepare polymeric blend membrane to enhance the antifouling properties and rejection. Blend membranes consist of different concentrations (0, 2.5 and 5.0 wt%) of polyvinylpyrrolidone (PVP), which was the hydrophilic polymer additive and pore forming agent. The existence of membrane functional groups was analyzed by ATR-FTIR spectroscopy. AFM and SEM were conducted to explain the surface morphology of the synthesized blend membranes. Membrane properties were examined by contact angle, porosity and equilibrium water content (EWC). The membrane’s thermal and mechanical properties were determined by performing TGA and tensile test. Membrane performance was assessed by pure water flux (PWF), rejection, antifouling properties using bovine serum albumin (BSA) and Sodium alginate (SA) solution. In this study, CPA-2 membrane showed high PWF of 269.82 L m2 h1, flux recovery ratio (FRR) against BSA and SA was 94% and 92%, respectively. Rejection of BSA and SA was found to be 83% and 86%, respectively. From the results, it was significant that the hydrophilic additive PVP blended membrane ameliorated and showed better results in surface roughness, hydrophilicity, thermal and mechanical stability. Hence, CPA-2 membrane would exhibit less susceptibility to fouling with enhanced PWF, permeability and selectivity.

Temporal Trends and Future Prediction of Breast Cancer Incidence Across Age Groups in Trivandrum, South India

Mathew, Aleyamma,George, Preethi Sara,Arjunan, Asha,Augustine, Paul,Kalavathy, MC,Padmakumari, G,Mathew, Beela Sarah Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.6

Background: Increasing breast cancer (BC) incidence rates have been reported from India; causal factors for this increased incidence are not understood and diagnosis is mostly in advanced stages. Trivandrum exhibits the highest BC incidence rates in India. This study aimed to estimate trends in incidence by age from 2005-2014, to predict rates through 2020 and to assess the stage at diagnosis of BC in Trivandrum. Materials and Methods: BC cases were obtained from the Population Based Cancer Registry, Trivandrum. Distribution of stage at diagnosis and incidence rates of BC [Age-specific (ASpR), crude (CR) and age-standardized (ASR)] are described and employed with a joinpoint regression model to estimate average annual percent changes (AAPC) and a Bayesian model to estimate predictive rates. Results: BC accounts for 31% (2681/8737) of all female cancers in Trivandrum. Thirty-five percent (944/2681) are <50 years of age and only 9% present with stage I disease. Average age increased from 53 to 56.4 years (p=0.0001), CR (per $10^5$ women) increased from 39 (ASR: 35.2) to 55.4 (ASR: 43.4), AAPC for CR was 5.0 (p=0.001) and ASR was 3.1 (p=0.001). Rates increased from 50 years. Predicted ASpR is 174 in 50-59 years, 231 in > 60 years and overall CR is 80 (ASR: 57) for 2019-20. Conclusions: BC, mostly diagnosed in advanced stages, is rising rapidly in South India with large increases likely in the future; particularly among post-menopausal women. This increase might be due to aging and/or changes in lifestyle factors. Reasons for the increased incidence and late stage diagnosis need to be studied.

A Novel Reference Current Extraction Technique with Multi‑Functional Capability for Shunt Active Filter

Kumar Reddy Cheepati,Nageswara Rao Maddala,Surya Kalavathi Munagala 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.2

The exponential growth of non-linear loads results the generation of harmonics in electrical distribution system. Major Harmonic generation efects due to non-linear loads are energy loss, nuisance tripping, equipment failure/mal-operation, and transformer saturation, overheating of neutral conductors and/or capacitors, interference with communication circuits, excess reactive power burden and lowering the true power factor. Improving the current quality is the prime responsibility of the consumers whereas utility is accountable for minimizing the supply voltage distortions. Shunt active flters (SAFs) were being used for many years to mitigate the current harmonics typically up to 25th order. Mainly, time and frequency domain reference current extraction control techniques were being used for SAF. Time-domain reference current extraction techniques were proved efcient than frequency-domain techniques due to their faster response. Time-domain reference current extraction techniques such as real and reactive (p-q) and synchronous reference frame (SRF) are having their own merits and demerits. The p-q control does not perform well under distorted and unbalanced supply voltage conditions whereas SRF control is limited to balanced loads. In this paper a novel reference current extraction control strategy is proposed i.e. inverse matrix averaging pq-SRF (IMApq-SRF) control. IMApq-SRF control extract the features of both conventional p-q and SRF control, based on inverse matrix average. The mathematical modeling of the proposed IMApq-SRF control is tested with MATLAB Simulink environment and it validates that the proposed IMApq-SRF control gives the superior performance as compared with conventional p-q and SRF techniques under balanced, unbalanced and distorted supply voltage and dynamic loading conditions.