venkatramanan kannan
@kanchiuniv.ac.in
Professor / Physics
sri chandrasekharendra saraswathi viswa mahavidyalaya
Venkatramanan K, PhD, LM-USI, LM-ASI has been working as full time Professor of Physics and as Head of the department of Physics at SCSVMV Deemed University, Kanchipuram, India with 21 years of experience.. He is currently the Director of Student Cultural Affairs and Programmes of SCSVMV Deemed University, India. He was a Research fellow at the department of Materials Science & Engineering, City University of Hongkong. He is a life member of Ultrasonic Society of India and Acoustical Society of India and Senior member of SCIEI. He is also the executive council member of Thermophysical Society of India [TPSI]. He has acted as reviewer for few international journals and has organised many national and international conferences. He is the editor of few international conference proceedings and has authored three text books in Physics for engineering students. He is the Chairman of Board of studies in Physics of SCSVMV Deemed University and a member of Academic council and Planning and Moni
RESEARCH, TEACHING, or OTHER INTERESTS
Materials Science, Multidisciplinary
Scopus Publications
Scholar Citations
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Scopus Publications
Vaskuri C. S. Theja, Vaithinathan Karthikeyan, Dani S. Assi, Hongli Huang, Venkatramanan Kannan, Yue Chen, Chan‐Hung Shek, and Vellaisamy A. L. Roy
Wiley
AbstractGraphene analog MXenes are the best options for interface engineering traditional thermoelectric materials. For the first time, a composite‐engineered TEG device composed of heavily doped bismuth and antimony telluride with incorporated Ti3C2Tx (MXene) nanoflakes is developed. Incorporated MXenes improved the electrical conductivity by carrier injection and reduces thermal conductivity by interfacial phonon scattering in both composites. The fabricated composite TEG device resulted in a maximum power of 1.14 mW and a power density of 6.1 mWcm−2. The fabricated composite TEG also demonstrates strong power generation stability and durability. Added MXenes improve the mechanical stability by employing a dispersion‐strengthening mechanism. Conclusively, the developed composite‐engineered TEG device is a facile and efficiency‐improving option for next‐generation bismuth telluride‐based commercial TEG devices.
Chandravadhana Arumugam, Nandakumar Velu, Padmanaban Radhakrishnan, Vellaisamy A. L. Roy, Gopalan Anantha-Iyengar, Dong-Eun Lee, and Venkatramanan Kannan
MDPI AG
In the present work, a new kind of nanocomposite (NC)-based solid component was prepared for formulating nanofluids (NFs). The NC comprised metal oxide (titanium dioxide, TiO2) dispersed in a conducting polymer with polyaniline (PANI) and chemically linked silyl–alkyl units in it (PSA) that were designated as T-PSA NC. The NFs with ethylene glycol (EG) as a base fluid were prepared with T-PSA NCs with various compositions of TiO2 and PSA as well for various concentrations of T-PSA NCs. The scanning electron microscopic evaluation of the NC revealed that PSA deposition on TiO2 nanoparticles (NPs) decreased particle agglomeration. The PSA coating on the TiO2 NPs did not influence the crystalline structure of the TiO2 NPs, according to the X-ray diffraction patterns. The thermophysical characterization and molecular interaction features of the NFs at 303 K including a novel inorganic–organic T-PSA NC, were detailed. Furthermore, the stability of the T-PSA NC-based NFs was investigated experimentally using the zeta potential, and the particle size distribution change was analyzed using the dynamic light scattering (DLS) method. The T-PSA NCs had particle sizes that were significantly bigger than pristine PSA and pure TiO2. Most of the preparation conditions used to produce the T-PSA NCs resulted in moderately stable suspensions in EG. The results revealed that the ultrasonic velocity increased with the increase in the concentration of T-PSA NC mass % in the NFs, the refractive index and thermal conductivity increased with the increase in the concentration, and the surface tension exhibited a linear change when the ratio of mass % concentration of the T-PSA NCs increased. The combined presence of components that synergistically contribute to the electro, thermal, optical, and rheological properties is expected to attract advanced applications for NFs.
Radhakrishnan Padmanaban, Ahobilam Gayathri, Aanantha Iyengar Gopalan, Dong-Eun Lee, and Kannan Venkatramanan
MDPI AG
This study reports the comparative deviations in experimental viscosity, density and ultrasonic velocity of two new ethanol-based binary liquid mixtures (ethanol + 1-hexanol and ethanol + 1-octanol) at 303.15 K by applying various theoretical models (Hind relation (ηH), Kendall and Monroe relation (ηK-M), Bingham relation (ηB), Arrhenius–Eyring relation (ηAE), Croenauer-Rothfus Kermore relation (ηCRK) and Gambrill relation (ηG)). Typically, the experimental densities are compared with theoretical methods like the Mchaweh–Nasrifar–Mashfeghian model (ρMNM), Hankinson and Thomson model (ρHT), Yamada and Gunn model (ρYG) and Reid et al. (ρR) model. Additionally, the experimental ultrasonic velocities are compared with various theoretical models like the Nomoto relation (UN), Van Dael and Vangeel relation (UIMR), Impedance relation (UIR), Rao’s specific velocity relation (UR) and Junjie relation (UJ). The average percentage of deviation (APD) is determined to identify the most suited model that can closely agree to the experimental values of the specified property (viscosity, density and ultrasonic velocity). From the APD values, it may be concluded that the ηK-M model is the most suitable theoretical method for estimating the viscosity for the ethanol + 1-hexanol system, and the Gambrill model is the suitable method for estimating viscosity for ethanol + 1-octanol liquid systems. Similarly, the model of Reid et al. and Jungie’s relation are the most suited theoretical models to predict the density and ultrasonic velocity of the binary liquid systems, respectively. Form the experimental data, various molecular interaction properties like adiabatic compressibility, intermolecular free length, free volume, internal pressure, and viscous relaxation time are analysed. The results of this study are expected to be useful in predicting the suitable molecular proportions that can be suited for industrial application (flavouring additive, insecticide, in the manufacture of antiseptics, perfumes for 1-hexanol based mixtures and flavouring, and as an antifoaming agent for 1-octanol based liquid mixtures).
Vaskuri C.S. Theja, Vaithinathan Karthikeyan, Sanjib Nayak, Kadir Ufuk Kandira, Dani S. Assi, Venkataramanan Kannan, and Vellaisamy A.L. Roy
Elsevier BV
Gopalan Saianand, Anantha-Iyengar Gopalan, Liang Wang, K. Venkatramanan, Vellaisamy A.L. Roy, Prashant Sonar, Dong-Eun Lee, and Ravi Naidu
Elsevier BV
Karthikeyan Velmurugan, Vaithinathan Karthikeyan, Krati Sharma, Tulja Bhavani Korukonda, Venkatramanan Kannan, Dhinesh Balasubramanian, and Tanakorn Wongwuttanasatian
Elsevier BV
Gopalan Saianand, Anantha-Iyengar Gopalan, K. Venkatramanan, Dong-Eun Lee, and Prashant Sonar
Elsevier
Vaithinathan Karthikeyan, Saw Lin Oo, James Utama Surjadi, Xiaocui Li, Vaskuri C. S. Theja, Venkataramanan Kannan, Siu Chuen Lau, Yang Lu, Kwok-Ho Lam, and Vellaisamy A. L. Roy
American Chemical Society (ACS)
Two-dimensional (2D)-layered atomic arrangement with ultralow lattice thermal conductivity and ultrahigh figure of merit in single-crystalline SnSe drew significant attention among all thermoelectric materials. However, the processing of polycrystalline SnSe with equivalent thermoelectric performance as single-crystal SnSe will have great technological significance. Herein, we demonstrate a high zT of 2.4 at 800 K through the optimization of intrinsic defects in polycrystalline SnSe via controlled alpha irradiation. Through a detailed theoretical calculation of defect formation energies and lattice dynamic phonon dispersion studies, we demonstrate that the presence of intrinsically charged Sn vacancies can enhance the power factor and distort the lattice thermal conductivity by phonon-defect scattering. Supporting our theoretical calculations, the experimental enhancement in the electrical conductivity leads to a massive power factor of 0.9 mW/mK2 and an ultralow lattice thermal conductivity of 0.22 W/mK through the vacancy-phonon scattering effect on polycrystalline SnSe. The strategy of intrinsic defect engineering of polycrystalline thermoelectric materials can increase the practical implementation of low-cost and high-performance thermoelectric generators.
Khrongkhwan Yotkuna, Rungsima Chollakup, Tanawat Imboon, Venkatramanan Kannan, and Sirikanjana Thongmee
Springer Science and Business Media LLC
S.M. Santhi Rekha, Vaithinathan Karthikeyan, Le Thi Thu Thuy, Quach An Binh, Kuaanan Techato, Venkatramanan Kannan, Vellaisamy A.L. Roy, Sukruedee Sukchai, and Karthikeyan Velmurugan
Elsevier BV
Rashmi Mannu, Vaithinathan Karthikeyan, Murugendrappa Malalkere Veerappa, Vellaisamy A. L. Roy, Anantha-Iyengar Gopalan, Gopalan Saianand, Prashant Sonar, Binrui Xu, Kwang-Pill Lee, Wha-Jung Kim,et al.
MDPI AG
The introduction of toxic chemicals into the environment can result in water pollution leading to the degradation of biodiversity as well as human health. This study presents a new approach of using metal oxides (Al2O3 and SiO2) modified with a plasmonic metal (silver, Ag) nanoparticles (NPs)-based nanofluid (NF) formulation for environmental remediation purposes. Firstly, we prepared the Al2O3 and SiO2 NFs of different concentrations (0.2 to 2.0 weight %) by ultrasonic-assisted dispersion of Al2O3 and SiO2 NPs with water as the base fluid. The thermo-physical (viscosity, activation energy, and thermal conductivity), electrical (AC conductivity and dielectric constant) and physical (ultrasonic velocity, density, refractive index) and stability characteristics were comparatively evaluated. The Al2O3 and SiO2 NPs were then catalytically activated by loading silver NPs to obtain Al2O3/SiO2@Ag composite NPs. The catalytic reduction of 4-nitrophenol (4-NP) with Al2O3/SiO2@Ag based NFs was followed. The catalytic efficiency of Al2O3@Ag NF and SiO2@Ag NF, for the 4-NP catalysis, is compared. Based on the catalytic rate constant evaluation, the catalytic reduction efficiency for 4-NP is found to be superior for 2% weight Al2O3@Ag NF (92.9 × 10−3 s−1) as compared to the SiO2@Ag NF (29.3 × 10−3 s−1). Importantly, the enhanced catalytic efficiency of 2% weight Al2O3@Ag NF for 4-NP removal is much higher than other metal NPs based catalysts reported in the literature, signifying the importance of NF formulation-based catalysis.
Gopalan Saianand, Prashant Sonar, Gregory J. Wilson, Anantha-Iyengar Gopalan, Vellaisamy A.L. Roy, Gautam E. Unni, Khan Mamun Reza, Behzad Bahrami, K. Venkatramanan, and Qiquan Qiao
Elsevier BV
Rashmi Mannu, Vaithinathan Karthikeyan, Nandakumar Velu, Chandravadhana Arumugam, Vellaisamy A. L. Roy, Anantha-Iyengar Gopalan, Gopalan Saianand, Prashant Sonar, Kwang-Pill Lee, Wha-Jung Kim,et al.
MDPI AG
Magnetic nanoparticles (MNPs) are widely used materials for biomedical applications owing to their intriguing chemical, biological and magnetic properties. The evolution of MNP based biomedical applications (such as hyperthermia treatment and drug delivery) could be advanced using magnetic nanofluids (MNFs) designed with a biocompatible surface coating strategy. This study presents the first report on the drug loading/release capability of MNF formulated with methoxy polyethylene glycol (referred to as PEG) coated MNP in aqueous (phosphate buffer) fluid. We have selected MNPs (NiFe2O4, CoFe2O4 and Fe3O4) coated with PEG for MNF formulation and evaluated the loading/release efficacy of doxorubicin (DOX), an anticancer drug. We have presented in detail the drug loading capacity and the time-dependent cumulative drug release of DOX from PEG-coated MNPs based MNFs. Specifically, we have selected three different MNPs (NiFe2O4, CoFe2O4 and Fe3O4) coated with PEG for the MNFs and compared their variance in the loading/release efficacy of DOX, through experimental results fitting into mathematical models. DOX loading takes the order in the MNFs as CoFe2O4 > NiFe2O4 > Fe3O4. Various drug release models were suggested and evaluated for the individual MNP based NFs. While the non-Fickian diffusion (anomalous) model fits for DOX release from PEG coated CoFe2O4, PEG coated NiFe2O4 NF follows zero-order kinetics with a slow drug release rate of 1.33% of DOX per minute. On the other hand, PEG coated NiFe2O4 follows zero-order DOX release. Besides, several thermophysical properties and magnetic susceptibility of the MNFs of different concentrations have been studied by dispersing the MNPs (NiFe2O4, CoFe2O4 and Fe3O4) in the base fluid at 300 K under ultrasonication. This report on the DOX loading/release capability of MNF will set a new paradigm in view that MNF can resolve problems related to the self-heating of drug carriers during mild laser treatment with its thermal conducting properties.
P. Dhivya, R. Padmanaban, A. Gayathri, and K. Venkatramanan
Springer Singapore
Anantha-Iyengar Gopalan, Jun-Cheol Lee, Gopalan Saianand, Kwang-Pill Lee, Woo-Young Chun, Yao-long Hou, Venkatramanan Kannan, Sung-Sik Park, and Wha-Jung Kim
MDPI AG
Titanium dioxide (TiO2), the golden standard among the photocatalysts, exhibits a varying level of photocatalytic activities (PCA) amongst the synthetically prepared and commercially available products. For commercial applications, superior photoactivity and cost-effectiveness are the two main factors to be reckoned with. This study presents the development of simple, cost-effective post-treatment processes for a less costly TiO2 to significantly enhance the PCA to the level of expensive commercial TiO2 having demonstrated superior photoactivities. We have utilized sequential calcination and ball milling (BM) post-treatment processes on a less-costlier KA100 TiO2 and demonstrated multi-fold (nearly 90 times) enhancement in PCA. The post-treated KA100 samples along with reference commercial samples (P25, NP400, and ST01) were well-characterized by appropriate instrumentation and evaluated for the PCA considering acetaldehyde photodegradation as the model reaction. Lattice parameters, phase composition, crystallite size, surface functionalities, titanium, and oxygen electronic environments were evaluated. Among post-treated KA100, the sample that is subjected to sequential 700 °C calcination and BM (KA7-BM) processes exhibited 90-fold PCA enhancement over pristine KA100 and the PCA-like commercial NP400 (pure anatase-based TiO2). Based on our results, we attribute the superior PCA for KA7-BM due to the smaller crystallite size, the co-existence of mixed anatase-srilankite-rutile phases, and the consequent multiphase heterojunction formation, higher surface area, lattice disorder/strain generation, and surface oxygen environment. The present work demonstrates a feasible potential for the developed post-treatment strategy towards commercial prospects.
A Chandravadhana, V NandaKumar, and K Venkatramanan
IOP Publishing
Abstract This paper presents a review of mono and hybrid nanofluid using heat sink technologies, which is the foremost task of new generation technology in cooling electronic devices. Heat generation in a tiny electronic device is the main factor to be prevented to enhance the heat transfer. One prominent remedy for this problem is to adopt mono and hybrid nanofluid based microchannel heat sinks are considered to be the recent trends.In this article, a state-of-the-art review of heat sinks, nanofluids preparation and characterization techniques have been carried out. The study begins with an overview of the heat sink, designing parameters, research work carried out in the last decade using mono nanofluids and hybrid nanofluids followed by the analysis of the research work carried out in the last decade in terms of different geometries of MCHS to examine the diverse factors like pressure drop, heat transfer coefficient, and critical heat flux. Current challenges and opportunities for future research are presented as well.
Anantha-Iyengar Gopalan, Jun-Cheol Lee, Gopalan Saianand, Kwang-Pill Lee, Prashant Sonar, Rajarathnam Dharmarajan, Yao-long Hou, Ki-Yong Ann, Venkatramanan Kannan, and Wha-Jung Kim
MDPI AG
Titanium dioxide (TiO2) has been extensively investigated in interdisciplinary research (such as catalysis, energy, environment, health, etc.) owing to its attractive physico-chemical properties, abundant nature, chemical/environmental stability, low-cost manufacturing, low toxicity, etc. Over time, TiO2-incorporated building/construction materials have been utilized for mitigating potential problems related to the environment and human health issues. However, there are challenges with regards to photocatalytic efficiency improvements, lab to industrial scaling up, and commercial product production. Several innovative approaches/strategies have been evolved towards TiO2 modification with the focus of improving its photocatalytic efficiency. Taking these aspects into consideration, research has focused on the utilization of many of these advanced TiO2 materials towards the development of construction materials such as concrete, mortar, pavements, paints, etc. This topical review focuses explicitly on capturing and highlighting research advancements in the last five years (mainly) (2014–2019) on the utilization of various modified TiO2 materials for the development of practical photocatalytic building materials (PBM). We briefly summarize the prospective applications of TiO2-based building materials (cement, mortar, concretes, paints, coating, etc.) with relevance to the removal of outdoor/indoor NOx and volatile organic compounds, self-cleaning of the surfaces, etc. As a concluding remark, we outline the challenges and make recommendations for the future outlook of further investigations and developments in this prosperous area.
Nellore Manoj Kumar, Kannan Venkatramanan, Anish Kumar M. Nair, and Shekatam Satheesh Kumar
Informa UK Limited
ABSTRACT An interesting feature of the tropical cirrus clouds is its descending nature, which is not well characterized over the tropics due to the scarcity of continuous observations over a single location. In order to quantify the morphological characteristics of the descending cirrus, data from systematic ground-based Lidar observations of cirrus clouds over a tropical site Gadanki (13.5° N, 79.2° E) is analyzed during 2000–2015. Time series and altitude structures of different descending cirrus layers are discussed. A total of 105 cases of descending cirrus (about 9%) are observed against 10 (about 1%) cases of ascending cirrus. The mean displacements of the base and top of descending cirrus clouds are 1.26 ± 1.04 km and 1.21 ± 0.99 km, respectively. About 94% of the descending cirrus have their descent speeds of < 0.8 m s−1. As 75% of descending cirrus has Cloud Optical Depth (COD) between 0.1 and 0.9, it is obvious that most of the observed descending cirrus clouds are classified as either thick or thin clouds. Surprisingly, none of the cases showed that descending cirrus are of a sub-visible type. The present exploratory study on descending nature of cirrus clouds would be useful in understanding the process of cirrus sedimentation, which plays a major role in regulating the moisture content in Tropical Tropopause Layer (TTL) as well as on the Earth’s radiation budget.
Nellore Manoj Kumar and Kannan Venkatramanan
Frontiers Media SA
The presence of cirrus cloud has its impact on the earth’s radiation budget. In order to study the effect of cirrus clouds in the tropical regions, it is essential to understand, and characterize their optical properties. The optical properties of high altitude cirrus clouds are obtained using the polarization diversity ground based Mie lidar instrument at a tropical latitude station in the Indian subcontinent. Lidar measurements are taken for one year (2013) at National Atmospheric Research Laboratory (NARL), located at Gadanki (13.5°North, 79.2°East; 375 m AMSL), India and are used for the present investigation. Altitude variations of optical depth and depolarization ratio are discussed. In the altitude range of 10–17 km, the range of the optical depth and depolarization ratio of cirrus cloud was found to be 0.01–0.4 and 0.1–0.4, respectively. The interdependence of optical depth as a function of depolarization ratio is analyzed and a positive correlation is observed (0.3950). From the measured optical depth values, it is categorized that 8, 77, and 14% of the cirrus clouds are sub-visual, thin, and thick clouds. The monthly and seasonal variations of optical properties of cirrus clouds were analyzed. Summary of cirrus cloud layer statistics and the statistical variation (seasonal) of the optical properties of cirrus clouds is presented for the period of study.
Vaithinathan Karthikeyan, James Utama Surjadi, Joseph C.K. Wong, Venkataraman Kannan, Kwok-Ho Lam, Xianfeng Chen, Yang Lu, and Vellaisamy A.L. Roy
Elsevier BV
A. Jayanthi, K. Venkatramanan, and K. Suresh Kumar
Elsevier BV
Rashmi M., Padmanaban R., Vaithinathan Karthikeyan, Vellaisamy A. L. Roy, Anantha-Iyengar Gopalan, Gopalan Saianand, Wha-Jung Kim, and Venkatramanan Kannan
MDPI AG
Copper oxide (CuO) and cerium oxide (CeO2) of various concentrations have been prepared through an ultrasonically assisted dispersion of CuO and CeO2 nanoparticles (NPs) in which water and nanofluids (NFs) were formulated. The morphological properties of the CuO and CeO2 NPs are reported. Few of the physicochemical properties that can influence the photocatalytic activities of the NFs are evaluated, such as viscosity, activation energy, density, thermal conductivity, electrical conductivity, alternating current (AC) conductivity, pH, stability, refractive index and optical band gap of the CuO and CeO2 NFs. Viscosity studies have been made at four different temperatures (303 K, 308 K, 313 K and 318 K) and the activation energy is calculated and compared between the CuO and CeO2 NFs. The thermal conductivity of the two NFs is calculated and compared. Electrical conductivity is measured for CuO and CeO2 NFs using an impedance analyzer at different frequencies at 303 K. The dielectric constant and AC conductivity were studied. The electrical conductivity and pH of the prepared NFs are measured and the results are compared. The stability of the NFs is determined from Zeta potential values obtained from dynamic light scattering measurements. UV-Visible diffuse reflectance measurements were used to deduce the optical bandgap of the respective metal oxide NPs in the NFs. The photocatalytic efficiencies of the CuO NFs and CeO2 NFs were evaluated using methylene blue (MB) as the model dye. The rate constant for the photodegradation of MB was higher for CuO NF as compared CeO2 NF and also higher than simple NPs-based photocatalysts. A plausible explanation for the role of NFs over the simple NPs-based photocatalytic solution is presented.
A. Jayanthi, K. Venkatramanan, and K. Suresh Kumar
IOP Publishing
Abstract The physics of laser - AISI 316 stainless steel interactions discussed stage-by-stage including the formation of plasma plume around the keyhole during the laser welding. This work reveals that the pulsed laser heat input is a highly successful tool to join 2 mm thick 316L stainless steel welding by a single pass, that too autogenously! However, inadequacy in laser input power leads to the incomplete penetration at weld joint and poor bead formation and whereas excess heat input causes root concavity (loss of material) at the bottom. It has observed a vapour region near bottom of the keyhole while the joint fully penetrated and it slightly expanded due to excess heat input, known as downward expanded vapour region. Consequently, downward expanded vapour region results in excess melting; it leads to loss of material by spatter during welding that causes root concavity at the bottom, which will affect the joint integrity. Therefore, it is important to identify and control the expansion of vapour region by optimizing the input power of the laser. To ensure optimization of the operating parameters and the integrity of weld joints are qualified through Vickers micro hardness test and X-ray radiography test.
Manoj Kumar Nellore, Venkatramanan Kannan, and Arul Lenus Roy Vellaisamy
MDPI AG
Altitude occurrences of cirrus clouds, their base, mid, and top heights are identified by using a powerful statistical approach called the Variance Centroid Method (VCM). This method is effective in determining the geometrical properties of cirrus clouds at a height range of 8 km to 20 km. This statistical method provides in-depth information on Generation Circulation Models (GCM’s) because of its significant role in the radiative balance of the earth’s atmosphere. The output related to geometrical and optical properties of cirrus clouds obtained from this statistical method for the years 2014 and 2015 are studied. Altitude distributions of base, mid, top, and thickness of tropical cirrus clouds are analyzed in terms of percentage occurrences. For the year 2014, it was found that 14.8%, 75.2%, and 9.9% of cirrus clouds were sub-visual, thin, and thick clouds and for the year 2015, 71.2% and 28.7% of cirrus clouds were found to be thin and thick clouds, and sub-visual types of clouds were not observed. The interdependence of optical depth with the depolarization ratio is discussed and it is observed that the correlation is negative (−0.0303) for the year 2014 and positive (0.1311) for the year 2015. High optical depths with values from 0.502 to 0.849 are observed in the height regions from 9 km to 15 km (for 2014) and for the year 2015, the observed value ranges from 0.514 to 0.822 for the height regions from 9 km to 11 km. Statistical variation of characteristics of tropical cirrus clouds is presented for the period of study. The characterization of these cirrus clouds is highly useful for climate modeling studies, and their impact plays a vital role in the Earth’s radiation budget at the top of the atmosphere.
A. Gayathri, T. Venugopal, and K. Venkatramanan
Elsevier BV