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Enhanced Photocatalytic Performance of Sn6SiO8 Nanoparticles and Their Reduced Graphene Oxide (rGO) Nanocomposite

Gnanamoorthy G, Muthukumaran M, Varun Prasath P, Karthikeyan V, Narayanan V, Sagadevan S, et al.

J Nanosci Nanotechnol, 2020 09 01;20(9):5426-5432.
PMID: 32331114 DOI: 10.1166/jnn.2020.17814

Photocatalysts provide excellent potential for the full removal of organic chemical pollutants as an environmentally friendly technology. It has been noted that under UV-visible light irradiation, nanostructured semiconductor metal oxides photocatalysts can degrade different organic pollutants. The Sn6SiO8/rGO nanocomposite was synthesized by a hydrothermal method. The Sn6SiO8 nanoparticles hexagonal phase was confirmed by XRD and functional groups were analyzed by FT-IR spectroscopy. The bandgap of Sn6SiO8 nanoparticles (NPs) and Sn6SiO8/GO composites were found to be 2.7 eV and 2.5 eV, respectively. SEM images of samples showed that the flakes like morphology. This Sn6SiO8/rGO nanocomposite was testing for photocatalytic dye degradation of MG under visible light illumination and excellent response for the catalysts. The enhancement of photocatalytic performance was mainly attributed to the increased light absorption, charge separation efficiency and specific surface area, proved by UV-vis DRS. Further, the radical trapping experiments revealed that holes (h+) and superoxide radicals (·O-₂) were the main active species for the degradation of MG, and a possible photocatalytic mechanism was discussed.
Enhanced Photocatalytic Behavior of (GO/Cu₂O) Composite with Cu₂O Being Synthesized Through Green Route

Muthukumaran M, Dhinagaran G, Narayanan V, Raju T, Venkatachalam K, Karthika PC, et al.

J Nanosci Nanotechnol, 2019 Nov 01;19(11):7215-7220.
PMID: 31039878 DOI: 10.1166/jnn.2019.16671

Graphene oxide/Cuprous oxide (GO/Cu₂O) composite is a visible light photocatalyst for the degradation of dyes. A simple and efficient approach for preparing GO/Cu₂O composite adopted in this study involves reducing cuprous oxide precursors in the presence of graphene oxide using an aqueous solution of pulp derived from banana fruit. The GO/Cu₂O composite was characterized by Fourier transform infrared spectroscopy (FT-IR), Diffused reflectance Ultraviolet visible spectroscopy (DRS UV-Vis), Raman spectroscopy and Field Emission Scanning electron microscopy (FE-SEM). Cu₂O particles were distributed randomly on the graphene oxide sheets due to the template effect of GO. The results showed higher photocatalytic activity for the composite (band gap 2.13 eV), for the degradation of the organic dyes (Methylene blue and Rhodamine-B). The enhanced photocatalytic activity is due to effective charge transfer from GO to Cu₂O, and high specific surface area which improves the effective separation of the generated electron-hole pairs. Our present study is inspired by a facile, low cost, green production of (GO/Cu₂O) composite whose photocatalytic activity can be extended to degradation of all other water-born textile dyes.
Firefighter satisfaction and happiness at work: how big is the effect?

Muthukumaran M, Mohd Nadzrul Safiq AR, Rosnah I, Nor Hisham M, Ashrul Riezal A, Ismail AG

Med J Malaysia, 2023 May;78(3):287-295.
PMID: 37271837

INTRODUCTION: Firefighter satisfaction plays a crucial role in overall workplace happiness. We seek to quantify the effect size of firefighters' satisfaction with happiness at work after adjusting for socio-demographic attributes.
MATERIALS AND METHODS: This study used data from an online cross-sectional survey that was conducted from 24 June to 24 July 2021 in the Fire and Rescue Department of Malaysia. Firefighters were approached using the saturation sampling technique. They received online surveys via email through the Director of State and follow-up reminders through the Assistant Director of State Operations. A total of two filter questionnaires were employed i.e. type and duration of service. Firefighters stating that they were volunteer/auxiliary firefighters or had been in service for 2 years or less were excluded. In this study, data from 6041 out of 8581 firefighters were included for further analysis. The survey utilised the validated staff satisfaction index (SSI) and the happy career (HC) scale for in-service firefighters. SSI was a dual-dimension index consisting of welfare and protection against hazards at work, with 16 subdimensions. The HC is a five multi-dimensional items scale. Then, we used multiple linear regression to obtain the coefficient of determination while adjusting for age groups, gender, marital status, job grade, years of service and region of service.
RESULTS: A total of 6041 eligible data points were analysed in the study. The mean (±SD) age was 38.70 (8.97) years, of which 95.9% were male. The firefighters were in service for a median of 14 years (Q1, Q3: 8, 21). The firefighter reported higher life satisfaction (mean [SD] = 78.30 [9.15]) than happiness at work (mean [SD] = 77.22 [0.20]). The mean happiness scores differed significantly between years of service groups (p<0.001), region of service (p<0.001), marital status (p=0.029) and grade (p<0.001). Firefighters' satisfaction contributed 42.7% of workplace happiness (βadj=1.096 [95% CI: 1.064, 1.128]; p<0.001) after adjusting for frontline, married, the central region of service and male gender as control variables.
CONCLUSION: Firefighter satisfaction had a large effect size on happiness at work (42.7%). However, the interpretation of this effect size should be done with caution because happiness at work is inseparable from other life dimensions such as stability in matrimonial relationships and finances, involvement in leisure and religious activities and being mentally healthy.

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