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

In this work, an inorganic hexagonal boron nitride (h-BN) dispersed vinyl (PVDF) and acrylic (PMMA) polymer blends were synthesized and its structure–property relationships were investigated. The structural identification by X-ray diffraction pattern confirms the semi-crystalline property of the h-BN dispersed blends. The internal morphology and topography details of the blends were studied by transmission electron (TEM) and atomic force microscopy (AFM). The chemical functionality of the polymer blends are changing after the dispersion of h-BN as confirmed from the IR spectrum analysis. The molecular interaction between PVDF, PMMA and h-BN is highly enhanced for 2 wt% loadings of h-BN. The dielectric constant (ε) as a function of frequency and temperature showed that there is a consistent increase in the value of ε at low frequency and high temperature for increasing loadings of h-BN and also a relatively low dissipation factor (tan δ) was obtained. The thermal stability was analyzed by TGA which is showing the enhanced thermal stability of blends as the h-BN wt% increases. The major interest of this study is to improve the dielectric and thermal properties of polymer blends for efficient electronic device applications. © 2019, Springer Science+Business Media, LLC, part of Springer Nature.

VIT Unitversity

School of Advanced Sciences

Vellore Campus

Journal of Materials Science: Materials in Electronics

Investigation of structure, dielectric and thermal properties of hexagonal boron nitride dispersed polymer blends

This work investigates the diffusion of metal atoms into phase change chalcogenides, which is problematic because it can destroy resonances in photonic devices. Interfaces between Ge 2Sb 2Te 5 and metal layers were studied using X-ray reflectivity and reflectometry of metal–Ge 2Sb 2Te 5 layered stacks. The diffusion of metal atoms influences the crystallisation temperature and optical properties of phase change materials. When Au, Ag, Al, W structures are directly deposited on Ge 2Sb 2Te 5, inter-diffusion occurs. Indeed, Au reacts with Ge 2Sb 2Te 5 to form a AuTe 2 layer at the interface. Diffusion barrier layers, such as Si 3N 4 or stable plasmonic materials, such as TiN, can prevent the interfacial damage. This work shows that the interfacial diffusion must be considered when designing phase change material-tuned photonic devices, and that TiN is the most suitable plasmonic material to interface directly with Ge 2Sb 2Te 5. © 2018, Springer Science+Business Media, LLC, part of Springer Nature.

World University root node

Journal of materials science

Inter-diffusion of plasmonic metals and phase change materials

In the present study, new multi-components spinel ferrite Zinc doped metallic ferrites are investigated. The synthesized compounds consisting of Zinc copper ferrite nanostructures were developed using the Co-precipitation technique. Powder X-ray diffraction pattern (XRD) confirms the formation of the spinel phase for all the samples. The lattice constant was studied through powder X-ray diffraction data analysis. The lattice constant of all Zinc copper ferrite concentration was found to be less than that of bulk values. The chemical composition, surface morphology and crystallinity of the samples have been examined by scanning electron microscopy (SEM) and High-Resolution Transmission Electron Microscope (HRTEM). Besides, selected area electron diffraction (SAED) confirms the evolution of phases and Energy Dispersive X-ray (EDX) respectively. The effect of Zinc copper ferrite nanoparticles, the magnetic properties were investigated by using Vibration Sample Magnetometer (VSM). The obtained hysteresis (M-H) curves of all the samples were analysed under the applied magnetic field of range ± 10 K Oe at room temperature. The magnetic properties such as saturation magnetisation (Ms), remnant magnetization (Mr) and coercivity (Hc) values are calculated. The data obtained from magnetic studies, the variation among the magnetic properties have been investigated for annealed 600 °C sample. The prepared Zinc copper ferrite nanoparticles should be extended to various potential applications, such as photodegradation of methylene blue (MB) dye under visible-light irradiation and results showed that 65% of the dye was degraded. Catalysis, separation, and purification processes. © 2019 University of Kashan.

Journal of Nanostructures

Photocatalytic dye degradation properties of zinc copper ferrites nanoparticles

We design a multi-resonance metasurface at terahertz frequency, which can act as a polarization manipulator in the reflective mode. The proposed polarization converter consists of periodic unit cells and each unit cell has a resonator on the top surface. While a dielectric material forms the middle layer, a gold foil constitutes the bottom layer. The proposed polarization converter converts a linearly polarized terahertz wave into an orthogonal one for a wide range of operating frequencies. It provides a maximum conversion efficiency in the frequency range of 0.64–1.47 THz where the magnitudes of the cross reflection coefficients exceed 90%. The calculated relative bandwidth of the proposed converter is 78.67%. The phase difference of the reflected wave is between − 180 ∘ and 180 ∘ depending upon the operating frequency. Further, based on the detailed numerical results, we corroborate that the proposed device is robust against the variations in the structural parameters. The proposed converter maintains the conversion efficiency for various incident angles from 0 ∘ to 30 ∘ . Besides, we also demonstrate the possibility of tuning the polarization conversion ratio by integrating silicon in the metasurface. The proposed metasurface may find potential applications in communications, antenna, and radar cross-section reduction technology. © 2019, Springer Science+Business Media, LLC, part of Springer Nature.

Journal of Infrared, Millimeter, and Terahertz Waves

Designing a Broadband Terahertz Half-Wave Plate Using an Anisotropic Metasurface

We investigate the propagation characteristics of the chirped self-similar solitary waves in non-Kerr nonlinear media within the framework of the generalized nonlinear Schrödinger equation with distributed dispersion, two-power-law nonlinearities, and gain or loss. This model contains many special types of nonlinear equations that appear in various branches of contemporary physics. We extend the self-similar analysis presented for searching chirped self-similar structures of the cubic model to a more general problem involving two nonlinear terms of arbitrary power. A variety of exact linearly chirped localized solutions with interesting properties are derived in the presence of all physical effects. The solutions comprise bright, kink and antikink, and algebraic solitary wave solutions, illustrating the potentially rich set of self-similar pulses of the model. It is shown that these optical pulses possess a linear chirp that leads to efficient compression or amplification, and thus are particularly useful in the design of optical fiber amplifiers, optical pulse compressors, and solitary wave based communication links. Finally, the stability of the self-similar solutions is discussed numerically under finite initial perturbations. © 2019 American Physical Society.

Physical Review E

Chirped self-similar solitary waves for the generalized nonlinear Schrödinger equation with distributed two-power-law nonlinearities

Purpose: RayStation treatment planning system employs pencil beam (PB) and Monte Carlo (MC) algorithms for proton dose calculations. The purpose of this study is to evaluate the radiobiological and dosimetric impact of RayStation PB and MC algorithms&nbsp;on the intensity-modulated proton therapy (IMPT) breast plans. Methods: The current study included ten breast cancer patients, and each patient was treated with 1–2 proton beams to the whole breast/chestwall (CW) and regional lymph nodes in 28 fractions for a total dose of 50.4&nbsp;Gy relative biological effectiveness (RBE). A total clinical target volume (CTV_Total) was generated by combining individual CTVs: AxI, AxII, AxIII, CW, IMN, and SCVN. All beams in the study were treated with a range shifter (7.5&nbsp;cm water equivalent thickness). For each patient, three sets of plans were generated: (a) PB optimization followed by PB dose calculation (PB-PB), (b) PB optimization followed by MC dose calculation (PB-MC), and (c) MC optimization followed by MC dose calculation (MC-MC). For a given patient, each plan was robustly optimized on the CTVs with same parameters and objectives. Treatment plans were evaluated using dosimetric and radiobiological indices (equivalent uniform dose (EUD), tumor control probability (TCP), and normal tissue complication probability (NTCP)). Results: The results are averaged over ten breast cancer patients. In comparison to PB-PB plans, PB-MC plans showed a reduction in CTV target dose by 5.3% for D99% and 4.1% for D95%, as well as a reduction in TCP by 1.5–2.1%. Similarly, PB overestimated the EUD of target volumes by 1.8─3.2&nbsp;Gy(RBE). In contrast, MC-MC plans achieved similar dosimetric and radiobiological (EUD and TCP) results as the ones in PB-PB plans. A selection of one dose calculation algorithm over another did not produce any noticeable differences in the NTCP of the heart, lung, and skin. Conclusion: If MC is more accurate than PB as reported in the literature, dosimetric and radiobiological results from the current study suggest that PB overestimates the target dose, EUD, and TCP for IMPT breast cancer treatment. The overestimation of dosimetric and radiobiological results of the target volume by PB needs to be further interpreted in terms of clinical outcome. © 2019 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

Fulltext

Journal of Applied Clinical Medical Physics

Radiobiological and dosimetric impact of RayStation pencil beam and Monte Carlo algorithms on intensity‐modulated proton therapy breast cancer plans

Development of a stable and highly active metal oxide based electrochemical supercapacitor is a major challenge. Herein, we report a Au-Fe 2 O 3 nanocomposite having tiny amount of gold (3 atomic % Au) by employing a simple redox-mediated synthetic methodology using a modified hydrothermal system. Structural and morphological studies of the synthesized Au-Fe 2 O 3 nanocomposite have been performed both experimentally (XRD, IR, Raman, XPS, TEM, and FESEM analyses) and theoretically (WIEN2K). A probable dissolution-nucleation-recrystallization growth mechanism has been suggested to explain the morphological transformation from a Fe 3 O 4 nanoflake to a Au-Fe 2 O 3 nanorod. We have observed the superior chemical stability of the Au-Fe 2 O 3 nanocomposite in an acidic medium due to composite formation. The electrochemical measurement of the synthesized Au-Fe 2 O 3 nanocomposite exhibits specific capacitance of ∼570 F g -1 at the current density of 1 A g -1 in 0.5 M H 2 SO 4 electrolyte. The result is superior compared to the mother component, i.e., Fe 2 O 3 (138 F g -1 ), under identical conditions. It is credited to its higher specific surface area and composite effect. Theoretically, a decrease in band gap associated with increase in conductivity supports the superiority of the Au-Fe 2 O 3 nanocomposite compared to the mother compound, i.e., Fe 2 O 3 . In addition, electrochemical kinetic analysis showed that the charge-storage mechanism is mostly from a dominant capacitive process (78% at 1.5 mV s -1 ). A solid-state asymmetric supercapacitor device has been fabricated using a synthesized Au-Fe 2 O 3 composite nanorod as the positive and activated carbon as the negative electrodes. The asymmetric solid-state device exhibits a maximum energy density of 34.2 Wh kg -1 and power density of 2.73 kW kg -1 at current densities 1 A g -1 and 10 A g -1 , respectively. Thus, the synthesized nanocomposite shows excellent activity as a supercapacitor with long-term durability (91% capacitance retention) up to 5000 cycles even in an acidic medium. Copyright © 2018 American Chemical Society.

ACS Sustainable Chemistry and Engineering

Redox-Mediated Shape Transformation of Fe 3 O 4 Nanoflakes to Chemically Stable Au-Fe 2 O 3 Composite Nanorods for a High-Performance Asymmetric Solid-State Supercapacitor Device

Purpose: The aim of this work is to study the dosimetric parameters of newly introduced 2.5 MV imaging x-ray beam used as inline imaging to do setup verification of the patient undergoing radiation therapy. As this x-ray beam is in megavoltage range but comprises of a lower energy spectrum. It is essential to study the pros and cons of 2.5 MV imaging x-ray beam for clinical use.Methods: The mean energy was calculated using the NIST XCOM table through MAC. Profile analysis was done using RFA to understand the percentage depth dose, degree of unflatteness, symmetry, penumbra and out of field dose. Dose to skin for the 2.5 MV x-ray beam was analysed for field sizes 10x10 cm2, 20x20 cm2, 30x30 cm2. Leakage measurements for treatment head and at the patient plane were done using IEC 819/98 protocol. Finally, the spatial resolution and contrast were analyzed with and without patient scatter medium. Results: The MAC at 15 cm off-axis was found to be lower than that at the CAX. Similarly, there was a decrease in mean energy from 0.47 MV to 0.37 MV at 15 cm off-axis. The reduction of mean energy towards off-axis is lower than the other high energy MV x-ray beams. The tuned absolute dose of 1 cGy/MU is consistent and within &lt; ±1 %. The relative output factors were found to be in correlation with Co-60. The beam quality of 2.5 MV x-ray beam was found to be 0.4771. The profile parameters like the degree of unflatness of the 2.5 x-ray beam were studied at 85 %, 90 %, 95 % lateral distances, and the penumbra at different depth and field sizes are higher than the 6 MV treatment beam. In addition, out of field dose also drastically increases to a maximum of up to 30 % laterally at 5cm at deeper depths. The skin dose increases from 48.51 % to 88.15 % from 6 MV to 2.5 MV x-ray beam for the field size 10x10 cm2. Also, the skin dose increases from 88.15 % to 91.78 % from the field size 10x10 cm2 to 30x30 cm2. Although the measured leakage radiation for 2.5 MV x-ray beam at the patient plane and other than patient planes are with the tolerance limit, an increase in exposure towards gantry side compared to other areas around treatment head and the patient plane may lead to more skin dose to head and chest while imaging pelvis region. The MLC transmission of 2.5 MV x-ray beam such as inter, intra and edge effect are 0.40 %, 0.37 % and 11% respectively. The spatial resolution of 2.0, 1.25 and 0.9 LP/mm was observed for KV, 2.5MV, and 6 MV x-ray beams. The spatial resolution and contrast of 2.5 MV x-ray beam are superior to 6 MV x-ray beam and inferior to KV x-rays. Conclusions: The 2.5 MV x-ray imaging beam is analysed in view of beam characteristics and radiation safety to understand the above-studied concepts while using this imaging beam in a clinical situation. In future, if 2.5MV x-ray beam is used for treatment purpose with increased dose rate, the above-studied notions can be incorporated prior to implementation. © 2019 Asian Pacific Organization for Cancer Prevention.

Asian Pacific Journal of Cancer Prevention

An assessment of dosimetric characteristics of inline 2.5 mega voltage unflattened imaging X-ray beam

Background: Herbal drugs are gaining exponential scientific recognition due to their distinct advantages. In the last 2-3 decades, a gradual increase in worldwide patents on herbal nano-formulations has been noted to address the solubility and bioavailability issues of phytoceuticals. Struvite or ammonium magnesium phosphate hexahydrate (NH 4 MgPO 4 .6H 2 O) is among the important urinary infection stones causing painful urological ailment. These smaller stones may bind together to form bigger staghorn calculus. Urinary tract infections caused by some gram positive and gram negative bacteria further enhance the chance of formation of such stones. Oxalis corniculata Linn. is an edible plant, traditionally used in the treatment of bacterial infections and kidney stones. However, there is no scientific evidence to relate the use of O. corniculata against struvite kidney stones. Hence, the antibacterial and struvite stones inhibition activity of the aqueous extract of Oxalis corniculata Linn. leaves and its biofabricated silver nanoparticles (AgNPs) was studied. Methods: The aqueous extract of O. corniculata was prepared by Soxhlet extraction. AgNPs were synthesized using green technique and were characterized using UV and IR spectroscopy, XRD, TEM, DLS and zeta potential studies. Antibacterial activity of the aqueous extract and the silver nanoparticles was tested against E. coli (gram negative) and S. aureus (gram positive) species. Struvite stones were grown in a gel medium by in vitro single diffusion gel growth technique and its inhibition study was carried out using the extract and its biofabricated nanoparticles. Results: The aqueous extract and its biofabricated AgNPs exhibited potent antibacterial activity against both gram positive and gram negative strains of bacteria. The aqueous extract also effectively repressed the growth of struvite stones and led to the dissolution of stones, but the inhibitory effect was further enhanced by its biofabricated AgNPs. Conclusion: The present work confirms the inhibitory activity of the aqueous extract of edible O. corniculata and its biofabricated silver nanoparticles against urinary tract infection (UTI) causing bacteria and urolithiasis. Therefore, the consumption of O. corniculata in our daily diet may reduce the risk of UTI and urolithiasis. © 2018 Bentham Science Publishers.

Recent Patents on Drug Delivery and Formulation

Antibacterial and in vitro growth inhibition study of struvite urinary stones using Oxalis corniculata linn. Leaf extract and its biofabricated silver nanoparticles

Galectins are β-galactoside binding proteins that act as potential cancer biomarkers. Agrocybe cylindracea galectin (ACG) is a fungal galectin which recognizes specifically α(2,3)-linked sialyllactose and play a pivotal role in biological recognition processes. This manuscript has presented the theoretical investigation on enhancing the binding specificity of ACG towards α(2,6)-linked sialyllactose. In silico single point and double point mutations were carried out at the binding site amino acid residues of ACG to enhance its binding to α(2,6)-linked sialyllactose, and the mutated protein-carbohydrate complexes were simulated for 30 ns durations. Analysis of the interaction patterns of the carbohydrate at the binding site of wild type and mutated lectins revealed that sialic acid contributed more to the binding when compared with other sugar units in the trisaccharide and enhanced the binding specificity of ACG towards α(2,6)-linked sialyllactose. © 2019, © 2019 Taylor & Francis Group, LLC.

Department Of Biotechnology

Journal of Carbohydrate Chemistry

Investigation on the binding specificity of Agrocybe cylindracea galectin towards α(2,6)-linked sialyllactose by molecular modeling and molecular dynamics simulations