Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

Department of Physics

(111)-oriented transition metal oxide thin films provide a route to developing oxide-based topological quantum materials, but the epitaxial growth is challenging. Here, we present the thickness-dependent electronic and magnetic phase diagrams of coherently strained, phase pure (111)-oriented SrRuO3 epitaxial films grown on (111) SrTiO3 substrates using pulsed laser deposition. With decreasing film thickness, it is found that both the metal-to-insulator and magnetic phase transitions occur at the same thickness of 4-5 nm for films grown along both the (111) and the (001) directions. The character of the transport near the metal-insulator transition is, however, distinct for the different directions, which is attributed to the increased electron-electron correlation for (111) SrRuO3. The findings presented here highlight both the broad challenges as well as the possibilities in modifying correlated materials using dimensional tuning of electronic and magnetic properties. © 2019 Author(s).

School of Advanced Sciences

Vellore Campus

World University root node

Fulltext

APL Materials

Metal-insulator transition in (111) SrRuO3 ultrathin films

The increasing demand for energy storage systems with high energy and power densities requires suitable electrode materials that are inexpensive, stable, and efficient. Using a facile synthesis technique that yields such materials in a short duration is the need of the hour. Herein, we demonstrate a microwave-assisted hydrothermal technique to synthesize cobalt hydroxy carbonate hydrate with diverse shapes. Upon annealing under air at 500 °C for 3 h, cobalt hydroxy carbonate is converted to phase pure Co3O4 without a significant change in the original morphology, i.e., urchin-like, flower-like, and nanocubes. The flower-like structure showed the highest specific capacitance and thus was used as the positive electrode for an all-solid-state flexible asymmetric supercapacitor (ASC) device. Among the three different carbon-based materials such as graphene hydrogel (GH), reduced graphene oxide, and activated carbon tested for use as negative electrodes, GH showed the best performance. The fabricated flexible Co3O4//GH ASC device affords an energy density of 29 W h kg-1 at a power density of 916 W kg-1 with a coulombic efficiency of ∼97%. The device retains 87% of its initial capacitance after 2000 cyclic runs. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2019.

New Journal of Chemistry

Morphology-dependent charge storage performance of Co3O4 nanostructures in an all-solid-state flexible supercapacitor

Cost-effective conducting polymer composite films were prepared from non-conducting polymer and black Tea. The films showed conducting and considerable magnetic properties. The measured coercive field, saturation magnetization and remnant magnetization values were found to be 80 Oe, 0.14 emu g-1 (at 8 kOe), and 9.0 ×10-3 emu g-1, respectively. In order to realize the high-frequency applications of these materials, dielectric properties were measured in the frequency range of 1 Hz-1 MHz. The measured dielectric permittivity (ϵ′) and loss tangent (tanδ) values of the composite polymer thin film were found to be 260 and 0.37 (at 1 kHz) respectively. The estimated dc conductivity (σ dc) value was around 1.60 ×10-8 S cm-1. © 2019 IOP Publishing Ltd.

Materials Research Express

Enhancement in the magnetic and electrical conductivity properties of PVA- black tea composite films

To understand the distribution of angular momenta between host stars and ( their ) planets, we estimate the ( spin ) angular momentum (J spin ) of host stars that follow a power law (forumala Presented). with stellar mass M ⊙ M* . Similarly, the orbital angular momenta (L p ) of exoplanets are estimated, and the best fit yields a power law, (forumala Presented). with the exoplanetary mass Mp MJ . Furthermore, the total (spin and orbital) angular momentum J tot of the stellar planetary system is computed, and a power law of the form J tot (forumala Presented).is obtained. In addition, an analysis between specific angular momenta (I p ) of planets and planetary masses J reveals that specific angular momentum is nonlinearly related with planetary mass in case of multiplanetary systems and is independent of planetary mass in case of single-planetary systems. We find that the probability of detecting Earth-like planets is more likely for host stars that have total angular momentum ≤10 41 kg m 2 s −1 . Finally, a power-law relationship is obtained between exoplanetary masses and their orbital distances in case of multiplanetary systems and, is independent in case of single-planetary systems. © 2018. The Astronomical Society of the Pacific. All rights reserved. Printed in the U.S.A.

Publications of the Astronomical Society of the Pacific

Angular momentum of stars and their planets

Solid state carbon based Electrochemical Double Layer capacitors (EDLC) was assembled and cyclic voltammetry (CV) was studied at high sweep rates. The carbons used were Vulcan XC carbon with typical surface area of 260 m 2/gm, templated mesoporous carbon, (CMK-3), typical surface area of 1260 m2/gm, and a blend of Vulcan XC carbon and mesoporous carbon (90:10% by weight). Solid ionic polymers of perfluorosulphonic acid were used as electrolyte. CV was performed for scan rates as high as 800V/s. Electrochemical impedance spectroscopy, EIS, was used to understand the interface characteristics. It was found that the polymer electrolyte membrane can support high scan rates. The resistance of the EDLC was more emphasized at high scan rates, which maybe due to surface effects rather than bulk characteristics of the carbon. It was found that the change in capacitance was less pronounced at scan rates above 10V/s. ©The Electrochemical Society.

Department of Chemistry

ECS Transactions

Study of Carbon Based Solid State EDLCs at High Sweep Rates

The present study has been carried out to analyse the effect of the laser shock peening (LSP) with the absence of a coating on titanium alloy (Grade 5—Ti6Al4V) and to establish the best set of LSP parameters for enhanced surface characteristics. Ti6Al4V which has excellent mechanical properties is penned using Nd:YAG pulsed laser with 2D XY translation with water as confinement medium. Power density (3, 6, 9 GW/cm 2 ), wavelength (532, 1064 nm) and overlap (60%, 70%) are the three process parameters considered to perform laser shock peening without coating (LSPwC). Surface roughness is increased with raise in wavelength and as well as other parameters too. Even though hardness is increased in both wavelengths, enhanced hardness is caused with 1064 nm wavelength. An adequate amount of compressive stress is induced with 3 GW/cm 2 at 50 μm depth. The rate of corrosion is dropped in samples LSPwC with 532 nm compared with 1064 nm wavelength due to its low surface roughness and surface oxide layer which holds the fluctuation of current density with respect to potential. SEM observation showed pits on the surface of samples peened with a 1064 nm wavelength. And this surface pitting is correlated with the fall of charge transfer resistance in such samples. © 2019, The Brazilian Society of Mechanical Sciences and Engineering.

Department of Manufacturing Engineering

School of Mechanical Engineering

Journal of the Brazilian Society of Mechanical Sciences and Engineering

Laser shock peening wavelength conditions for enhancing corrosion behaviour of titanium alloy in chloride environment

We numerically investigate the effects of a weak coherent femtosecond (fs) pulse seed on the continuous wave (CW) pumped supercontinuum (SC) generation. We analyze the evolution of CW pumped SC generation with various random noises and we observe the instabilities, which are initiated by modulation instability, in the spectrum of the SC. To actively control the instabilities, we introduce a weak coherent fs pulse seed to improve the properties of CW pumped SC in terms of spectral bandwidth and pulse-to-pulse stability. The detailed numerical results corroborate that the frequency shift and the peak power of the seed significantly decide the properties of the SC. The present investigation would be highly useful for realizing a broad CW pumped SC with enhanced coherence and SNR. © 2018 IOP Publishing Ltd.

Journal of Optics (United Kingdom)

Continuous wave pumped supercontinuum assisted by a weak femtosecond pulse seed

Purpose: The purpose of this study is to evaluate variation in the treatment hold pattern and quantify its dosimetric impact in breath-hold radiotherapy, using fraction-specific post-treatment quality assurance. Material and Methods: A patient with lung mets treated using intensity-modulated radiation therapy (IMRT) with active breath coordinator (ABC) was recruited for the study. Treatment beam hold conditions were recorded for all the 25 fractions. The linearity and reproducibility of the dosimetric system were measured. Variation in the dose output of unmodulated open beam with beam hold was studied. Patient-specific quality assurance (PSQA) was performed with and without beam hold, and the results were compared to quantify the dosimetric impact of beam hold. Results: There was a considerable amount of variation observed in the number of beam hold for the given field and the monitor unit at which the beam held. Linearity and reproducibility of the dosimetric system were found within the acceptable limits. The average difference over the 25 measurements was 0.044% (0.557 to -0.318%) with standard deviation of 0.248. Conclusion: Patient comfort with the ABC system and responsiveness to the therapist communication help to maintain consistent breathing pattern, in turn consistent treatment delivery pattern. However, the magnitude of dosimetric error is much less than the acceptable limits recommended by IROC. The dosimetric error induced by the beam hold is over and above the dose difference observed in conventional PSQA. © 2019 Cambridge University Press.

Journal of Radiotherapy in Practice

Fraction-specific post-treatment quality assurance for active breath-hold radiation therapy

Electric Vehicle is one of the most effective solution for reducing the Green House Effect and Global Warming. It is the alternative way of conventional vehicle. In Power Electronic circuit battery, charging unit is used to deliver high performance with less power consumption. LCC compensation network is used with the Converter circuit of the battery-charging unit of EV. It has high efficiency with reduced circulating current, output voltage and output current consists of wide range regulation. In Design consideration of Battery Charging unit, Bi- directional power flow is required Grid to Vehicle (G2V) power transformation or vice versa. The paper focuses on Bi-directional Converter LCC compensation with double sided for charging Topology of the EV. In this proposed method, depending on coupling coefficient resonant frequency is independent and is used between transmitting and receiving coil where zero voltage switching (ZVS) is achieved. This proposed method is used as a charging system which is wireless with maximum resistive load of 7.77 KW instead of battery load with an achieved efficiency of 86.2%. © 2019 IEEE.

Department of Energy and Power Electronics

School of Electrical Engineering

VIT Unitversity

2019 Innovations in Power and Advanced Computing Technologies (i-PACT)

A Solution To Fast Battery Charging Technology With Bi-Directional Series Parallel Resonant Converter LCC In Grid to Vehicle Ambient

A continuous global demand for energy resources poses serious threats to the human race in forms of pollution that stimulates many natural hazards. To overcome such problems, fuel cell technology seems to be a viable solution. However, it remains a challenge to develop highly efficient metal-free electrocatalysts for oxygen reduction reaction (ORR) to achieve optimal performance for the fuel cells. Herein, we demonstrate a facile room temperature synthesis of reduced graphene oxide (RGO) via chemical reduction of graphene oxide (GO) using sodium iodide (NaI) and hydrochloric acid (HCl). As-synthesized GO and RGO were employed as an efficient electrocatalyst for the ORR in 0.1 M KOH. The RGO shows higher ORR activity compared to GO due to its higher surface area and low charge transfer resistance. Thus as-synthesized RGO is found to be a viable metal-free electrocatalyst with higher current density, larger half-wave potential, and long-term operation stability for ORR via a four-electron pathway in alkaline media. The high performance of cost-effective RGO-based ORR electrodes is suitable to function as an alternative to platinum-based materials for energy conversion device applications. © 2019, Springer Nature Switzerland AG.