Journal of Metastable and Nanocrystalline Materials Vol. 44

Abstract: Nanoscale structures have drawn significant attention due to their unique and interesting properties. At nano size, surface stress and crystal orientation are the key factors in defining the properties. In this context, mechanical properties of an aluminium nanowire, subjected to uniaxial tensile loading have been investigated by utilizing molecular dynamics (MD) simulations. Specifically, under uniaxial tensile loading, the effect of strain rate (0.0005 ps^-1-0.05 ps^-1), temperature (10K-800K) and diameter (4nm-6nm) of the NW on several mechanical properties have been examined in the current work. Mechanical properties, like- Young’s modulus, yield stress, yield strain, fracture strain, ductility are obtained from variation of stress with respect to strain analysis. Decrease in Young’s Modulus and increase in yield stress, yield strain, fracture strain, ductility with rise in strain rate are observed. Temperature is found to significantly influence the mechanical characteristics of the nanowire as it affects both the elastic and plastic characteristics. With increase in temperature, Young’s modulus, yield stress, yield strain and fracture strain are found to decrease whereas ductility remained unaffected. On increasing diameter of the NW, the Young’s modulus, yield stress, yield strain showed marginal decrease whereas, fracture strain and ductility increased noticeably. These results show that with rise in strain rate and decrease in temperature/diameter, the strength of aluminium nanowire increases.

Abstract: Lithium-Ion batteries, when subjected to high discharge rates (C rate), exhibit elevated temperatures. When the temperature crosses the 323 K threshold, thermal runaway occurs, leading to fire and sometimes an explosion. To prevent this, the Battery Thermal Management System (BTMS) is employed. The current study investigates the cooling performance of mass-produced paraffin and Graphene-based (in 1,3, and 5 wt% concentrations) experimentally synthesized Nano-enhanced Phase Change Material (NePCM). Characterization of NePCM indicated elevated thermal conductivity by 23.32, 53.22, and 66.95% and density by 3.75, 6.5, and 13.5% but decreased latent heat by 3.17, 4.20, and 11.37% and specific heat by 4.30%, 4.93%, and 7.16% for each NePCM sample, respectively. Paraffin and NePCM were numerically computed in Li-Ion cell BTMS discharged at 3C. The results indicated the successful cooling performance of PCM with temperature reduction of 11.69, 11.78, 12.23, and 12.38% concerning Bare Cell temperature, respectively. Cost analysis conducted with similar studies involving specialized Phase Change Material (PCMs) showed that the present BTMS was, at maximum, 63.23% less costly.

Abstract: This study reports the development of a PID-based rotational speed control system for a rotary forcespinning (RFS) device aimed at improving the stability of nanofiber fabrication. The system integrates an Arduino Nano as the main controller, an optocoupler-based RPM sensor as feedback, and a BTS7960 motor driver to regulate a high-speed DC motor. The PID controller was implemented in a closed-loop configuration to maintain stable rotational speeds across multiple setpoints. The accuracy of the RPM measurement system was validated using a commercial tachometer, yielding a high linear correlation with R² = 0.9997 and an average error of 0.23%. The dynamic response of the PID controller demonstrated rapid stabilization with minimal steady-state error at rotational speeds up to 11000 RPM. The performance of the developed RFS system was evaluated by fabricating nanofibers from a 10 wt% polyvinylpyrrolidone (PVP) solution at rotational speeds of 7000; 9000; and 11000 RPM. The results show that stable and precise RPM control significantly influences the resulting nanofiber diameter and its distribution. These findings confirm that PID-based RPM control plays a critical role in enhancing operational stability and ensuring consistent nanofiber quality in rotary forcespinning systems.

Abstract: Batik is a traditional textile dyeing technique that UNESCO has recognized. The batik industry produces wastewater from the dyeing process containing Remazol Red, a carcinogenic and persistent azo dye that poses significant risks to the environment and human health. This study reports the synthesis of Zinc Oxide-Xanthan Gum nanocomposites (ZnO-XG NCs) through the sol-gel method, utilizing Zn-acetate dihydrate (Zn(CH₃COO)₂ž2H₂O) and Xanthan Gum biopolymer. Characterization shows that the addition of Xanthan Gum polymer matrix causes quantum confinement and defects in the material, which reduces the crystal size from 73.82 nm (ZnO) to 45.62 nm (ZnO-XG NCs) and narrows the band gap value from 3.21 eV to 3.08 eV (by the Tauc plot method). This band gap spans the visible and ultraviolet spectrum ranges, enabling photocatalytic activity to utilize direct sunlight as a source of photon energy. The visible light intensity of sunlight at 10.00 to 14.00 West Indonesia Time (WIT) is 79-85 klux, and the UV intensity is 2.38-2.88 mW/cm². The ZnO-XG NCs can degrade remazol red by 99.9% in batik wastewater within 150 min with pseudo-first-order reaction kinetics (k=0.0388 cm^-1). These results highlight the potential of ZnO-XG as an efficient and sustainable photocatalyst for treating dye-containing wastewater from the batik industry, offering an environmentally friendly solution to mitigate pollution while supporting the preservation of cultural heritage.

Abstract: The textile industry produces large volumes of dye-rich wastewater, with synthetic dyes like methylene blue posing environmental risks due to their resistance to degradation. This study synthesizes mesoporous silica from oil palm biomass, like empty fruit bunches (EFB) and palm kernel shells (PKS) from oil palms as adsorbents for methylene blue. Silica was extracted using 10% w/v NaOH, while CTAB, dissolved in 1.6 M HCl, was added in varying amounts (10, 15, and 20 g) to promote mesopore formation, then removed by calcination at 550 °C for 5 hours. XRF showed silica contents of 34.65% in EFB and 32.46% in PKS, while FTIR confirmed Si–O–Si functional groups. SEM revealed mild agglomeration from CTAB micelles, and SAXS peaks at 2θ < 3° confirmed ordered mesoporous structures. BET analysis showed ~3 nm pore diameters and surface areas of 333.97 m²/g (PKS) and 314.79 m²/g (EFB) with 20 g of CTAB. UV–Vis results indicated 80.9% methylene blue removal by PKS-derived mesoporous silica. Kinetic analysis indicated that the adsorption behavior of most samples was better described by the pseudo-second order model, suggesting a dominant role of surface-related interactions. These results highlight EFB and PKS as cost-effective precursors for efficient mesoporous silica adsorbents for dye-contaminated wastewater treatment.