Electrochemical Performance of M₂GeO₄ (M = Co, Fe and Ni) as Anode Materials with High Capacity for Lithium-Ion Batteries

Yuvaraj, Subramanian,Park, Myung-Soo,Kumar, Veerasubramani Ganesh,Lee, Yun Sung,Kim, Dong-Won The Korean Electrochemical Society 2017 Journal of electrochemical science and technology Vol.8 No.4

$M_2GeO_4$ (M = Co, Fe and Ni) was synthesized as an anode material for lithium-ion batteries and its electrochemical characteristics were investigated. The $Fe_2GeO_4$ electrode exhibited an initial discharge capacity of $1127.8mAh\;g^{-1}$ and better capacity retention than $Co_2GeO_4$ and $Ni_2GeO_4$. A diffusion coefficient of lithium ion in the $Fe_2GeO_4$ electrode was measured to be $12.7{\times}10^{-8}cm^2s^{-1}$, which was higher than those of the other two electrodes. The electrochemical performance of the $Fe_2GeO_4$ electrode was improved by coating carbon onto the surface of $Fe_2GeO_4$ particles. The carbon-coated $Fe_2GeO_4$ electrode delivered a high initial discharge capacity of $1144.9mAh\;g^{-1}$ with good capacity retention. The enhanced cycling performance was mainly attributed to the carbon-coated layer that accommodates the volume change of the active materials and improves the electronic conductivity. Our results demonstrate that the carbon-coated $Fe_2GeO_4$ can be a promising anode material for achieving high energy density lithium-ion batteries.

Nitrogen-doped Multi-walled Carbon Nanotubes-MnCo₂O₄ microsphere as electrocatalyst for efficient oxygen reduction reaction

Yuvaraj, S.,Vignesh, A.,Shanmugam, S.,Kalai Selvan, R. Elsevier 2016 International journal of hydrogen energy Vol.41 No.34

<P><B>Abstract</B></P> <P>Nitrogen-doped Multi-walled Carbon Nanotubes (N-doped MWCNT)/MnCo<SUB>2</SUB>O<SUB>4</SUB> hybrid is synthesized by a facile hydrothermal method. The X-ray diffraction studies revealed the single phase formation of cubic spinel structured MnCo<SUB>2</SUB>O<SUB>4</SUB> and their composites. The presence of D and G band of MWCNT is identified through Raman spectral analysis. The elemental oxidation state and nitrogen content is obtained using X-ray photoelectron spectroscopy, which elucidates that Co and Mn exists in multivalence state and the nitrogen functional groups are in pyrolytic and pyridinic-type. FE-SEM shows the microsphere formation of MnCo<SUB>2</SUB>O<SUB>4</SUB> and size exhibits in the range of 6–9 μm. The N-doped MWCNT/MnCo<SUB>2</SUB>O<SUB>4</SUB> hybrid catalyst exhibits an improved oxygen reduction electrocatalytic activity in an aqueous alkaline medium when compared with pristine MnCo<SUB>2</SUB>O<SUB>4</SUB>.</P> <P><B>Highlights</B></P> <P> <UL> <LI> N-doped MWCNT composite with MnCo<SUB>2</SUB>O<SUB>4</SUB> was prepared by single step hydrothermal method. </LI> <LI> The half-wave potentials of MWCNT-MnCo<SUB>2</SUB>O<SUB>4</SUB> is 30 mV higher than MWCNT and 150 mV higher than MnCo<SUB>2</SUB>O<SUB>4</SUB> catalyst. </LI> <LI> MWCNT-MnCo<SUB>2</SUB>O<SUB>4</SUB> hybrid exhibits an improved ORR activity in an aqueous alkaline medium compared to pristine samples. </LI> </UL> </P>

Organic–inorganic polypyrrole-surface modified SiO₂ hybrid nanocomposites: a facile and green synthetic approach

Yuvaraj, Haldorai,Shim, Jae-Jin,Lim, Kwon Taek John WileySons, Ltd. 2010 Polymers for advanced technologies Vol.21 No.6

<P>Organic-inorganic hybrid nanocomposites composed of conductive polypyrrole (PPy) and surface modified silica (SiO2) were successfully prepared through an in situ chemical oxidative polymerization in supercritical carbon dioxide (scCO(2)). SiO2 nanoparticles were surface modified using 3-methacryloxypropyltrimethoxysilane (MPTMS) in order to disperse well in the medium. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) showed that the SiO2 nanoparticles were encapsulated into the polymer. UV-visible spectra of the diluted colloidal dispersions of PPy/SiO2 hybrid nanocomposites were similar to those of PPy system. Fourier transform infrared spectroscopy (FT-IR) suggested the strong interaction between PPy and SiO2. Surface characterizations of nanocomposites were described by X-ray photoelectron spectroscopy (XPS). The nanocomposites synthesized in scCO2 have been shown to possess higher electrical conductivity and thermal stability. Copyright (C) 2009 John Wiley & Sons, Ltd.</P>

Environmental Microbiology / Microbial Diversity : FMN-Based Fluorescent Proteins as Heavy Metal Sensors Against Mercury Ions

( Yuvaraj Ravikumar ),( Saravanan Prabhu Nadarajan ),( Chong Soon Lee ),( Seunho Jung ),( Dong Ho Bae ),( Hyungdon Yun ) 한국미생물 · 생명공학회 2016 Journal of microbiology and biotechnology Vol.26 No.3

Bacterial light-oxygen-voltage-sensing photoreceptor-derived flavin mononucleotide (FMN)- based fluorescent proteins act as a promising distinct class of fluorescent proteins utilized for various biomedical and biotechnological applications. The key property of its independency towards oxygen for its chromophore maturation has greatly helped this protein to outperform the other fluorescent proteins such as GFP and DsRed for anaerobic applications. Here, we describe the feasibility of FMN-containing fluorescent protein FbFP as a metal-sensing probe by measuring the fluorescence emission changes of a protein with respect to the concentration of metal ions. In the present study, we demonstrated the mercury-sensing ability of FbFP protein and the possible amino acids responsible for metal binding. A ratiometric approach was employed here in order to exploit the fluorescence changes observed at two different emission maxima with respect to Hg(2+) at micromolar concentration. The engineered variant FbFPC56I showed high sensitivity towards Hg(2+) and followed a good linear relationship from 0.1 to 3 μM of Hg(2+). Thus, further engineering with a rational approach would enable the FbFP to be developed as a novel and highly selective and sensitive biosensor for other toxic heavy metal ions as well.

A New-Generation Fluorescent-Based Metal Sensor-iLOV Protein

( Yuvaraj Ravikumar ),( Saravanan Prabhu Nadarajan ),( Chong Soon Lee ),( Jin Kyu Rhee ),( Hyung Don Yun ) 한국미생물 · 생명공학회 2015 Journal of microbiology and biotechnology Vol.25 No.4

The iLOV protein belongs to a family of blue-light photoreceptor proteins containing a lightoxygen- voltage sensing domain with a noncovalently bound flavin mononucleotide (FMN) as its chromophore. Owing to advantages such as its small size, oxygen-independent nature, and pH stability, iLOV is an ideal candidate over other reporter fluorescent proteins such as GFP and DsRed. Here, for the first time, we describe the feasibility of applying LOV domain-based fluorescent iLOV as a metal sensor by measuring the fluorescence quenching of a protein with respect to the concentration of metal ions. In the present study, we demonstrated the inherent copper sensing property of the iLOV protein and identified the possible amino acids responsible for metal binding. The fluorescence quenching upon exposure to Cu2+ was highly sensitive and exhibited reversibility upon the addition of the metal chelator EDTA. The copper binding constant was found to be 4.72 ± 0.84 μM. In addition, Cu2+-bound iLOV showed high fluorescence quenching at near physiological pH. Further computational analysis yielded a better insight into understanding the possible amino acids responsible for Cu2+ binding with the iLOV protein.

EXPERIMENTAL INVESTIGATION ON CRYOGENIC ASSISTED ABRASIVE WATER JET MACHINING OF ALUMINIUM ALLOY

Yuvaraj Natarajan,Pradeep Kumar Murugasen,Lenin Raj Sundarajan,Rajadurai Arunachalam 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.6 No.3

The purpose of the present investigation was to evaluate the abrasive water jet cutting performance by the application of a cryogenic liquid nitrogen jet in the cutting process. This technique was developed for improving the process capability of conventional abrasive water jet machining and enable a higher depth of cut and material removal rate, and better kerf profile and surface integrity. The experiments were conducted on AA5083-H32 aluminium alloy, using two different cutting methods, namely, abrasive water jet cutting and cryogenic assisted abrasive water jet cutting. Both cutting conditions were investigated by varying the water jet pressure, the abrasive mesh size and the abrasive water jet impact angle. Optical microscopy and Scanning Electron Microscope with Energy Dispersive X-ray Spectroscopy was used for studying the micro structure and morphology of the cut surfaces under both cutting conditions. There was an improvement in cutting performance features such as depth of penetration, material removal rate and kerf profile with the use of cryogenic assistance cutting approach. These results were produced due to the beneficial modification of erosion mechanism in the cutting zone as well as a reduction in particle embedment with the cut surface by about 56%.

Association of Serum Vitamin D Levels with Bacterial Load in Pulmonary Tuberculosis Patients

Yuvaraj, B.,Sridhar, M.G.,Kumar, S. Vinod,Kadhiravan, T. The Korean Academy of Tuberculosis and Respiratory 2016 Tuberculosis and Respiratory Diseases Vol.79 No.3

Background: Vitamin D is known to have diverse effects on various systems in the body. There is evidence to suggest that a link exists between the serum vitamin D status and tuberculosis. The present study was designed to assess the alterations in serum 25-hydroxyvitamin D levels in newly diagnosed sputum acid fast bacilli (AFB) positive pulmonary tuberculosis patients and to study the association, if any, between serum vitamin D levels and different levels of sputum smear positivity. Methods: Serum 25-hydroxyvitamin D levels were estimated in 65 sputum AFB positive pulmonary tuberculosis patients and 65 age and gender-matched healthy controls. Results: The levels of serum 25 hydroxy-vitamin D in tuberculosis patients were not statistically different from the levels of serum 25 hydroxy-vitamin D in healthy controls. However, among patients with pulmonary tuberculosis, there was a significant negative correlation between the levels of serum 25 hydroxy-vitamin D and levels of sputum positivity. Conclusion: Serum vitamin D levels negatively correlates with bacterial load in patients with active pulmonary tuberculosis.

Transfer Learning Based Real-Time Crack Detection Using Unmanned Aerial System

Yuvaraj, N.,Kim, Bubryur,Preethaa, K. R. Sri Council on Tall Building and Urban Habitat Korea 2020 International journal of high-rise buildings Vol.9 No.4

Monitoring civil structures periodically is necessary for ensuring the fitness of the structures. Cracks on inner and outer surfaces of the building plays a vital role in indicating the health of the building. Conventionally, human visual inspection techniques were carried up to human reachable altitudes. Monitoring of high rise infrastructures cannot be done using this primitive method. Also, there is a necessity for more accurate prediction of cracks on building surfaces for ensuring the health and safety of the building. The proposed research focused on developing an efficient crack classification model using Transfer Learning enabled EfficientNet (TL-EN) architecture. Though many other pre-trained models were available for crack classification, they rely on more number of training parameters for better accuracy. The TL-EN model attained an accuracy of 0.99 with less number of parameters on large dataset. A bench marked METU dataset with 40000 images were used to test and validate the proposed model. The surfaces of high rise buildings were investigated using vision enabled Unmanned Arial Vehicles (UAV). These UAV is fabricated with TL-EN model schema for capturing and analyzing the real time streaming video of building surfaces.

Recent Progress on Sodium Vanadium Fluorophosphates for High Voltage Sodium-Ion Battery Application

Yuvaraj, Subramanian,Oh, Woong,Yoon, Won-Sub The Korean Electrochemical Society 2019 Journal of electrochemical science and technology Vol.10 No.1

Na-ion batteries are being considered as promising cost-effective energy storage devices for the future compared to Li-ion batteries owing to the crustal abundance of Na-ion. However, the large radius of the Na ion result in sluggish electrode kinetics that leads to poor electrochemical performance, which prohibits the use of these batteries in real time application. Therefore, identification and optimization of the anode, cathode, and electrolyte are essential for achieving high-performance Na-ion batteries. In this context, the current review discusses the suitable high-voltage cathode materials for Na-ion batteries. According to a recent research survey, sodium vanadium fluorophosphate (NVPF) compounds have been emphasized for use as a high-voltage Na-ion cathode material. Among the fluorophosphate groups, $Na_3V_2(PO_4)_2F_3$ exhibited the high theoretical capacity ($128mAh\;g^{-1}$) and working voltage (~3.9 V vs. $Na/Na^+$) compared to the other fluorophosphates and $Na_3V_2(PO_4)_3$. Here, we have also highlighted the classification of Fluorophosphates, NVPF composite with carbonaceous materials, the appropriate synthesis methods and how these methods can enhance the electrochemical performance. Finally, the recent developments in NVPF for the application in energy storage devices and its outlook are summarized.

Synthesis of MWNT/PEDOT Composites for the Application of Organic Light Emitting Diodes

Yuvaraj, Haldorai,Jeong, Yeon Tae,Lee, Won-Ki,Lim, Kwon Taek Informa UK (TaylorFrancis) 2009 Molecular Crystals and Liquid Crystals Vol.514 No.1