Plasmon coupling using eigenmode expansion and its sensing applications (2023)

Materials Today: Proceedings, Volume 78, Part 4, 2023, pp. 907-910

Two-dimensional (2D) metal dichalcogenides, like molybdenum disulfide (MoS₂), have been demonstrated as extremely efficient supercapacitive electrode material due to their high electrical conductivity and surface area. Herein, two different methodologies are adopted to synthesize MoS₂ samples: lithium (Li) intercalated chemical exfoliation and chemical vapour deposition (CVD) techniques. The structural and morphological characterizations of the as-prepared Li intercalated and CVD grown MoS₂ were done by high resolution transmission electron microscopy (HRTEM) and Scanning electron microscopy (SEM). The Raman spectra show that the Li intercalated MoS₂ samples are mostly comprised of 3–4 layers whereas a monolayer signature is observed in CVD grown samples. In this study, we report a comparative study of the supercapacitive properties of chemically exfoliated and CVD grown MoS₂ using an electrochemical cell arrangement. Interestingly, the cyclic voltammetry (CV) result shows higher current density in CVD grown MoS₂ as compared to that of Li intercalated MoS₂ samples. The observed high specific capacitance can be ascribed to a larger surface area in CVD grown MoS₂ owing to a higher charge transfer facilitating the diffusion of electrolyte ions. This result shows that the CVD grown MoS₂ can be used for high performance supercapacitor applications.

Materials Today: Proceedings, Volume 78, Part 4, 2023, pp. 911-918

This work targets to enhance the antioxidant properties of biopolymer Xanthan gum (XG) by derivatization of underlying functional groups with ethylenediamine, diethyl triamine, 4-aminobenzoic acid and thioglycolic acid led to chemically modified products designated as XEDA, XDET, XABA and XTGL respectively. The XG derivatives were manifested by FTIR, FESEM and EDS analysis. Antioxidant potential was evaluated by scavenging of OH radical, DPPH radical and determination of reducing power which demonstrated XDET possessed the better antioxidant activity followed by XEDA, XABA, XTGL and XG in a concentration-dependent manner. Thus, the derivatization of XG extended the research towards biological properties of polysaccharide.

Materials Today: Proceedings, Volume 78, Part 4, 2023, pp. 786-791

Oxidation of α-hydroxy acid, racemic tartaric acid and its kinetic studies have been carried out to establish the mechanism of oxidation. The electron transfer reaction was performed in presence of surface active agents, surfactants, a clean and green catalytic material, using Ce(IV) as the oxidant. The progress of the reaction was monitored using a spectrophotometer by recording the fall in absorbance of Ce(IV) at its λ_max (wave length of maximum absorbance) of 380nm. Disappearance of Ce(IV) is observed to be first order at constant [H⁺]. Plot of log(Absorbance) against time is found to be linear in the initial stages of the reaction. The results of oxidation rates show a complex dependence of rate on [H⁺]. The pseudo first order rate constants (k) obtained with varying substrate concentration and the plot of k_obs/[substrate] vs [substrate] are observed to be excellently linear with positive slope. Plots of pseudo first order rate constants in presence of surfactant (sodium dodecyl sulphate, SDS) against the [SDS] abruptly rises in the concentration range below cmc (critical micelle concentration) after which the rate exponentially falls. Based on all the findings, Berezin model has been advanced to explain the observed kinetic phenomenon in the surfactant medium.

Materials Today: Proceedings, Volume 78, Part 4, 2023, pp. 900-906

Mosquito-repellent textiles offer protection from mosquito bites, thereby keeping the user safe. Using an herbal mosquito repellent extract on textile material could prompt protection from mosquitoes along with safety for both users and the environment. So, this study was under taken to develop an herbal mosquito repellent finish for cotton fabric using optimized process variables. The active component was extracted from different parts of the Anacyclus pyrethrum (Akarkara) plant, applied on cotton fabric samples and assessed for mosquito repellency. The highest mosquito repellency was observed in cotton fabric samples finished with Akarkara flower extract. The process parameters (conc. of the extract, material to liquor ratio and treatment time) were optimized using Box and Behnken Design of RSM to apply Akarkara flower extract on cotton fabric directly. To select the optimized variables, the finished fabrics were assessed for mosquito repellency (laboratory cage test method). Experimental work revealed that the mosquito repellency of finished cotton fabric samples was noted in a range of 57.87 percent to 79.63 percent in the 17 cotton fabric samples prepared as per the BBD matrix. The optimized concentration of the extract (15 %), MLR (1:20) and treatment time (30min) were used for finishing the cotton fabric samples. It was observed that mosquito repellency increased with increasing concentration of the extract. The mosquito repellency of the finished cotton fabric sample was reduced to 24.2 percent from 79.5 percent upon one wash cycle and decreased further on every wash. Additionally, eight months old extract's from Akarkara flower, when applied on a cotton fabric surface, displayed a reduced mosquito repellency as compared to fresh extract application. Henceforth, through this kind of finish, an individual can receive protection from mosquito bites and further reduce cases of deadly diseases.

Materials Today: Proceedings, Volume 78, Part 4, 2023, pp. 825-829

An artificially roughened evacuated tube collector with periodic circular ribs was studied for heat transfer and flow characteristics. The current study was conducted in ANSYS Fluent 16.2 to analyze influence of fixed pitch to wire diameter ratio of 12 and wire diameter to hydraulic diameter ratio of 0.0643 on frictional factor and Nusselt number. RNG k-ε with enhanced wall treatment turbulence model was used for Reynolds number range of 2500–8000. For identical flow conditions, performance comparison of evacuated tube collectors having roughened and smooth absorber was undertaken. Reynolds number increase resulted in enhancement of Nusselt number and reduction in frictional factor. In comparison to smooth evacuated tube collector, augmentation of order 2.51 and 1.66 times was achieved in frictional factor and Nusselt number respectively. Across the entire Reynolds number range studied, thermohydraluic performance factor value ranged between 1.16 and 1.23.

Materials Today: Proceedings, Volume 78, Part 4, 2023, pp. 891-894

Nowadays there is increasing concern about water pollution. Heterogeneous photo catalysis in combination with self-cleaning effect is a promising technology that can be used for water treatment. Self-cleaning composite surfaces are proven to be best material for this problem; these coatings are based on the surface wettability behavior. These surfaces are categorized in to hydrophilic and hydrophobic surfaces based on the wettability behavior of the surface if the contact angle (WCA) of surface and liquid is<90°, then surface is considered as hydrophobic and if it is less than>90° surface could be considered as hydrophilic. In this study hydrophilic photo catalytic composite of SiO₂ @TiO₂ has been developed on glass substrate. The work focused on the wettability of developed coating under UV–vis light exposure which is responsible for the acceleration of the photo catalytic activity. The coating has been prepared by layer by layer deposition method (L-b-L). The detailed information about the crystallographic structure, chemical properties and physical properties of the composite material has been studied by XRD technique. XRD confirms the anatase phase of the TiO₂ in the composite coating. SEM technique has been used for the morphological information further XRD and SEM results could better substantiate with the help of EDAX analysis. EDAX confirms the elemental composition and mapping in the prepared composite coating. Further wettability behaviour of the coating was measured by water contact angle technique. WCA<24.8° results confirms the hydrophilic characteristics of the coatings which further helps to improve the photo catalytic activity of the coating. Photo catalytic degradation study has been also performed with Methylene blue dye solution (5ppm) under the UV–vis light irradiation. The catalytic activity results reveal that the photo catalytic activity of composite coating recorded about 82.79% after 90min of illumination.