Understanding the molecular interaction and relaxation findings in amphiphilics on solution state using TDR

Senthilkumar P.,Vinoth K.,Maria Sylvester M.,Karunakaran D.J.S.Anand,Deshmukh Avadhut Ramrao,Hudge Pravin,Ganesh T.,Kumbharkhane A.C. 한국물리학회 2022 Current Applied Physics Vol.38 No.-

The dielectric behavior of stearic acid in 1,4-dioxane medium at various temperature 303 K–288 K and frequency regime (10 MHz–30 GHz) determined from the complex dielectric permittivity spectra obtained by Time Domain Reflectometry(TDR). In this frequency range, the dielectric study gives the electrostatic interaction as well as orientational polarizability of complex mixtures of long chain molecules significantly. Dielectric parameters were calculated from the complex spectra of the binary mixture by non linear least square fit method. The excess permittivity (εE), correlation factors were calculated for the binary system. Thermal parameters(ΔH-enthalpy, ΔS-entropy and ΔG-Gibbs free energy) were calculated and the direction of reaction is determined. The FTIR spectrum of the binary system recorded and the assignments are discussed. The FTIR spectral assignments confirm the molecular interactions.

Potentiostatic activation of as-made graphene electrodes for high-rate performance in supercapacitors

Senthilkumar, K.,Jeong, S.,Lah, M.S.,Sohn, K.S.,Pyo, M. Elsevier Sequoia 2016 Journal of Power Sources Vol. No.

A thermally expanded graphene oxide (EGO) electrode is electrochemically activated to simultaneously introduce electrolyte-accessible mesopores and oxygen functional groups. The former is produced via O<SUB>2</SUB> evolution and the latter is incorporated by the intermediate hydroxyl radicals generated during the potentiostatic oxidation of H<SUB>2</SUB>O in 1 M H<SUB>2</SUB>SO<SUB>4</SUB> at 1.2 V (vs. Ag/AgCl). When applied as a supercapacitor, the potentiostatically treated EGO (EGO-PS) shows significant enhancement in an electric-double layer (EDL) process with a noticeable Faradaic reaction and delivers high capacitance at fast charge/discharge (C/D) rates (334 F g<SUP>-1</SUP> at 0.1 A g<SUP>-1</SUP> and 230 F g<SUP>-1</SUP> at 50 A g<SUP>-1</SUP>). In contrast to EGO-PS, EGO that is oxidized potentiodynamically (EGO-PD) shows negligible enhancement in EDL currents. EGO that is subjected to successive potential pulses also shows behaviors similar to EGO-PD, which indicates the importance of hydroxyl radical accumulation via a potentiostatic method for simultaneous functionalization and microstructural control of graphenes. The potentiostatic post-treatment presented here is a convenient post-treatment strategy that could be used to readily increase capacitance and simultaneously improve the high-rate performance of carbon-based electrodes.

Experimental investigation and optimization of machining parameters during machining of glass fibre reinforced epoxy based composite using desirability function analysis

Senthilkumar K.M,Kathiravan N,Girisha L,Sivaperumal M 한양대학교 세라믹연구소 2022 Journal of Ceramic Processing Research Vol.23 No.4

In the recent years, mankind has established that the protection of the environment becomes a vital part in the discovery ofany engineering applications. Several engineering applications in the areas of agriculture, forestry, energy industries, havedeveloped several composite materials in place of other materials for its effectiveness. This work focuses on synthesis of acomposite material and the matrix material used in the research work was epoxy resin. Glass fibres were used as thereinforcement material for the preparation of the hybrid epoxy based composite. The epoxy used in this work is LB011 epoxyresin lapox B_11. The hardener used is Triethylenetetraamine (TETA). The composite laminates are prepared by varying theweight proportion of the glass fibres and tested for its mechanical properties. The composite laminate with high tensile strengthis selected for the investigation of machining properties of the composite laminate. Optimization of machining parameter arecarried out by a novel analysis called Desirability Function Analysis (DFA), which is an optimal tool considered for theproblems with multi objective optimization function.

Impact of Tobacco on Glutathione S Transferase Gene Loci of Indian Ethnics

Senthilkumar, K.P.,Thirumurugan, Ramasamy Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.10

Background: Tobacco contains agents which generate various potent DNA adducts that can cause gene mutations. Production of DNA adducts may be neutralized by glutathione S transferase (GST) along with other phase I and phase II enzyme systems. The existence of null type of GST among the population increases the susceptibility to various disorders and diseases. The present study focuses on the impact of high tobacco usage and possible null type mutation in GST loci. Methods: Genotypes of GST were detected by multiplex polymerase chain reaction in unrelated 504 volunteers of high tobacco using natives of Gujarat. Allelic frequencies were calculated using Statistical Package for Social Studies-16 software. Hardy Weinberg Equilibrium (HWE) was calculated using Chi square test. Two sided Fisher's significance test was used to compare allelic frequencies of different populations. Results: The frequency of homozygous null genotype of GSTM1 and GSTT1 were 20% (95% CI 16.7-23.9) and 35.5% (95% CI 31.4-39.9) respectively. The GSTM1 and GSTT1 null allele frequency distribution in the Gujarat population was significantly deviating from HWE. GSTT1 null frequency of Gujaratians was significantly higher and different to all reported low tobacco using Indian ethnics, while GSTM1 was not differing significantly. Conclusion: Tobacco usage significantly influences the rate of mutation and frequency of GSTT1 and M1 null types among the habituates. The rate of mutation in GSTT1 loci was an undeviating response to the dose of tobacco usage among the population. This mutational impact of tobacco on GSTT1 postulates the possible gene - environment interaction and selection of null genotype among the subjects to prone them under susceptible status for various cancers and even worst to cure the population with GSTT1 dependent drugs.

Nano metal oxide (CuO/Co3O4) based feed stock filament for FDM

K. Uma,G. Senthilkumar,K. Balamurugan 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.9

The applications of fused deposition modelling (FDM) are stretched widely by making functional parts. Metal oxides-based polymer nano composites have great potential to develop those functional parts. The intention of this work is to recognize the appropriate metal oxide filler and level of its loading in composite filament which is compatible for FDM by analyzing their tensile and metal flow properties. Filaments were synthesized by taking acrylonitrile butadiene styrene (ABS) as common matrix material and two metal oxides such as copper oxide (CuO) and cobalt oxide (Co 3 O 4 ) were taken as fillers with 0.5, 1.0, 1.5 and 2.0 wt.% of loading. The composite filaments were fabricated using a single screw extruder after compounding in a twin screw extruder. Totally, nine filaments of diameter 1.75±0.1 mm were extruded and all the samples were characterized by tensile strength and metal flow index measures. An increased pattern of tensile strength and decreased trend of % elongation (%EL) and metal flow index (MFI) values were noticed for increased filler loading for both fillers. When considering ABS as a reference material, CuO shows better results compared to Co 3 O 4 . Even though Co 3 O 4 shows high tensile strength, its %EL and MFI values were not good. At 1 wt% loading of CuO, tensile strength increased up to 46 %, MFI and % elongation values were reduced slightly as 19 % and 20 % from ABS. Further addition of nanoparticles improved tensile strength, but %EL and MFI values decreased drastically. Hence, the promising filler and filler loading were concluded as CuO with 1 wt% loading, which may be considered as suitable material for making blades and impellers in hydro dynamic machinery to improve their performance.

GSTM1 and GSTT1 Allele Frequencies among Various Indian and non-Indian Ethnic Groups

Senthilkumar, K.P.,Thirumurugan, R. Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.12

Background: Glutathione-S-transferase (GST) is an important phase II xenobiotic compound metabolizing enzyme family, involved in tolerance to a particular drug or susceptibility to a diseasec. This study focused the GSTM1 and T1 null allele frequency in the Gujarat population with a comparison across other Inter- and Intra-Indian ethnic groups to predict variation in the possible susceptible status. Methods: DNA was isolated by a salting out method and GSTM1 and T1 homozygous null genotypes were detected by multiplex polymerase chain reaction in 504 unrelated individuals. The genotype distribution of null alleles was compared with Indian and non Indian ethnics reported earlier in the literature using Fisher's test. Results: The frequencies of the homozygous null genotypes of GSTM1 and GSTT1 were 20% (95%CI 16.7-23.9) and 35.5% (95%CI 31.4-39.9) respectively. GSTM1 null frequency did not deviate from most other Indian ethnic groups but differed from the majority of those of non Indian ethnicity studied. The frequency of homozygous null type of GSTT1 was significantly higher and deviated from all Indian groups and a few of non Indian ethnicity. Conclusions: Gujarat ethnicity, possibly the most susceptible for GSTT1 dependent drug disposition and diseases regarding effects of pollution. Further, the results have implications for GSTT1 dependent drugs used for treatment, a serious problem which needs to be solved by physicians and clinical researchers.

Experimental analysis and optimization on machining of coated carbon fiber and nanoclay reinforced aluminum hybrid composites

Gajalakshmi K.,Senthilkumar N.,Palanikumar K. 한국탄소학회 2022 Carbon Letters Vol.32 No.3

In this present investigation, machinability studies on novel aluminum composite with hybrid reinforcements of copper-coated 4% carbon fibers (CFs) and 3% nanoclay in AA6026 matrix fabricated by compocasting method is performed. Step drill bit and multifaceted drill bit are used by adopting central composite design (CCD) in response surface methodology (RSM). The outcomes show that, with a rise in rotational speed surface irregularities, resultant force and material removal rate (MRR) intensifies, and with the additional rise in rotational speed, all the outputs decrease considerably. High MRR, resultant cutting force, and surface roughness are obtained with multifaceted carbide drills, compared with a step drill. Desirability function is used to maximize the MRR and minimize the resultant cutting forces considering the constant surface roughness of 3 µm. The optimal values are rotational speed of 1285 rpm, feed rate of 60 mm/min with the step drill bit, producing an MRR of 0.0439 kg/sec and a resultant cutting force of 185.818 N. The second-order empirical models are developed for outputs, which are fed into the non-traditional metaheuristic Evaporation Rate-based Water Cycle Algorithm (ER-WCA) therefore the lower objective value is achieved with step drill of 51.7421. It is found that using a step drill the machinability performance of this hybrid nanocomposite is well improved than the machining with other drill bits. This composite fulfills the norms of 2000/53/CE-ELV European environmental directives.

Electric discharge machining of AA7075/SiCp/B4Cp hybrid composites under Cu mixed used engine oil dielectric medium

Udhaya Chandran R.M.,Senthilkumar K.,Shabarinathan K.T.,Mylsamy K. 한양대학교 청정에너지연구소 2024 Journal of Ceramic Processing Research Vol.25 No.4

Electrical Discharge with an effort to create wealth out of waste, Used Engine Oil (UEO) was employed as the dielectricmedium to machine AA7075 hybrid composites. The research was conducted utilizing a variety of tools (Copper, Brass),current, pulse, weight percentage of composites, and powder concentration. The experimentation was designed using aTaguchi L18 orthogonal array. Because of its superior heat conductivity, copper electrodes remove more material than brasselectrodes. As the particle absorbs the most amount of heat generated, MRR falls as Cu particle integration increases to 6g/l. Cu powders added to the dielectric medium increase TWR, and research indicates that the heat created was transferredto the electrode rather than the work piece. Particles used as reinforcement had no impact on TWR. Brass electrode hada lower thermal conductivity than the copper electrode, less material was removed, resulting in the best surface quality. The formation of remelted layers is halted by through flushing, which is brought on by widening the spark gap. Due to theheat-absorbing qualities of copper particles, the surface is exposed to lower temperatures, increasing the surface's qualityby preventing the formation of cracks and craters. In the case of tools made of copper, 3 g/l of conductive copper powderwas added to the dielectric fluid, and the current, pulse on time, and pulse width were all set at 3A and 15 μs, maximumproductivity was achieved.

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.

Optimization of stir casting process parameter using response surface meth odology

Senthilkumar KM,Sivakumar A,Rohokale Milind Shivaji,S.K. Tamang,Giriraj M 한양대학교 세라믹연구소 2022 Journal of Ceramic Processing Research Vol.23 No.2

Response surface methodology is used to optimize the stir casting process parameters for the aluminium metal matrixcomposite reinforced with boron carbide with several weight percentages. The stir casting process parameters used in thiswork are the weight percentage of the reinforcing element, stir casting mixing time and particle size of the reinforcing elementused in the fabrication of the metal matrix composite. The levels are chosen and central composite design is implemented tooptimize the tensile strength of the metal matrix composite. The analysis of variance is calculated and the estimated regressioncoefficients for the tensile strength are obtained. Also the residual plots and the contour plots are plotted and discussed here.