Repository for digital copies of Journal articles authored by NIIST Staff http://localhost:8080/xmlui/handle/123456789/4 2026-05-01T19:52:31Z 2026-05-01T19:52:31Z Nithyaa, J Nishanth, K G http://localhost:8080/xmlui/handle/123456789/5143 2026-04-20T04:24:22Z 2025-01-01T00:00:00Z

Synergistic effect of a one-pot synthesised kaolinite–cerium melamine cyanurate hybrid for an improved metal protective coating Nithyaa, J; Nishanth, K G This paper presents the cerium–melamine cyanurate (CeMC) complex as an anticorrosive pigment prepared by one-pot synthesis. Further, kaolinite is integrated to prepare KCeMC to improve the barrier performance of the anticorrosive coating. The effectiveness of the synthesised pigment-loaded epoxy coatings was assessed using electrochemical impedance spectroscopy in a 3.5 wt% NaCl solution. X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX) confirmed the release of the cathodic inhibitor Ce3+, which forms a protective layer over defective areas of the coating. A five-fold increase in the initial coat resistance was observed compared to the pristine epoxy, as measured by electrochemical impedance spectroscopy (EIS). A 1 wt% KCeMC loaded epoxy coating reveals better durability among all the synthesised pigment loaded coatings. The impedance results exhibited remarkable long-term durability, maintaining a high coating resistance of 7.70 × 109 Ω cm2 after 2 months of immersion in a saline medium. The improved protective properties of the epoxy coating containing KCeMC are attributed to the synergistic effects of cerium inhibition along with the barrier performance provided by kaolinite and melamine cyanurate.

2025-01-01T00:00:00Z Shereema, R M Sruthi, T V Kumar, V B S Rao, T P Shankar, S S http://localhost:8080/xmlui/handle/123456789/5142 2026-04-20T04:21:15Z 2015-10-20T00:00:00Z

Angiogenic Profiling of Synthesized Carbon Quantum Dots Shereema, R M; Sruthi, T V; Kumar, V B S; Rao, T P; Shankar, S S A simple method was employed for the synthesis of green luminescent carbon quantum dots (CQDs) from styrene soot. The CQDs were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared, and Raman spectroscopy. The prepared carbon quantum dots did not show cellular toxicity and could successfully be used for labeling cells. We also evaluated the effects of carbon quantum dots on the process of angiogenesis. Results of a chorioallantoic membrane (CAM) assay revealed the significant decrease in the density of branched vessels after their treatment with CQDs. Further application of CQDs significantly downregulated the expression levels of pro-angiogenic growth factors like VEGF and FGF. Expression of VEGFR2 and levels of hemoglobin were also significantly lower in CAMs treated with CQDs, indicating that the CQDs inhibit angiogenesis. Data presented here also show that CQDs can selectively target cancer cells and therefore hold potential in the field of cancer therapy.

2015-10-20T00:00:00Z Ashitha, G Athira, B S Chandran, A Surendran, K P Gowd, E B http://localhost:8080/xmlui/handle/123456789/5138 2026-02-25T06:30:08Z 2025-07-03T00:00:00Z

Self-Poled PVDF Infiltrated Nylon 11 Aerogels with Oriented Crystals for High-Performance Piezoelectric Energy Harvesters and Self-Powered Acoustic Sensors Ashitha, G; Athira, B S; Chandran, A; Surendran, K P; Gowd, E B Efficient piezoelectric polymers with enhanced electromechanical conversion gain significant attention for energy harvesting and sensing applications. Among them, poly(vinylidene fluoride) (PVDF) and odd-nylons stand out due to their high piezoelectric coefficients and thermal stability. However, achieving a piezoelectric phase with a preferred crystal orientation for optimal performance remains challenging, particularly under mild processing conditions. In this study, a vacuum-assisted infiltration technique is introduced to fabricate PVDF-infiltrated nylon-11 (PVDFIPA11) aerogels with oriented polymer crystallites. Anisotropic nylon-11 aerogels, featuring aligned polymer crystals, serve as templates for PVDF infiltration under vacuum. This process facilitates the formation of highly oriented β phase PVDF crystals alongside γ phase nylon-11 crystals, yielding a fully self-poled system without the need for external poling. A piezoelectric nanogenerator (PENG) based on the PVDFIPA11 aerogel exhibits a high output voltage (peak-to-peak) of ≈45 Vpp and a peak power density of 2.2 Wm⁻3 significantly outperforming pristine PVDF and nylon-11 aerogels. Additionally, the PVDFIPA11 aerogel PENG is demonstrated as a self-powered acoustic sensor, effectively distinguishing sound signals at varying pressure levels. This work provides a scalable and practical strategy for developing self-poled piezoelectric polymer aerogels, paving the way for next-generation energy-harvesting devices and sensors.

2025-07-03T00:00:00Z Navin, J Ignatious, V Neethi, R Dheepika, R Riya, M Tanjore, P Y Biswapriya, D Vijayakumar, C http://localhost:8080/xmlui/handle/123456789/5137 2026-02-25T06:25:51Z 2025-07-08T00:00:00Z

Optimization of Benzodithiophene-Based Copolymer and SWCNT Composite Films for Flexible Thermoelectric Generators Navin, J; Ignatious, V; Neethi, R; Dheepika, R; Riya, M; Tanjore, P Y; Biswapriya, D; Vijayakumar, C This study investigates the thermoelectric (TE) properties of a benzodithiophene-based conjugated polymer (PBDTT-DPP) combined with single-walled carbon nanotubes (SWCNTs) for flexible, solution-processable thermoelectric generators (TEGs). Composite films are prepared with varying SWCNT content, achieving optimal performance at 50 wt.% SWCNT. Further optimization through FeCl₃ doping and thermal annealing at 200 °C significantly enhanced the electrical conductivity and overall TE performance. The doped and annealed composite film exhibited a power factor of 135 ± 8 µW mK−2 at 253 °C and a maximum ZT value of 0.17. Spectroscopic and electronic analyses revealed that doping and annealing realigned the energy bands and formed charge-transfer complexes, contributing to improved TE properties. Practical application is demonstrated through the fabrication of flexible, arc-shaped TEGs capable of harvesting energy from curved heat sources. The TEGs achieved a peak power output of 0.66 µW at ΔT = 100 K, showcasing its potential for low-grade waste heat recovery in industrial settings. This research advances the understanding of organic TE materials and offers promising solutions for sustainable energy harvesting from waste heat sources.

2025-07-08T00:00:00Z