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This study reports light energy harvesting characteristics of bismuth ferrite (BiFeO 3 ) and BiFO 3 doped with rare-earth metals such as neodymium (Nd), praseodymium (Pr), and gadolinium (Gd) dye solutions that were prepared by using the co-precipitation method. The structural, morphological, and optical properties of synthesized materials were studied, confirming that 5–50 nm sized synthesized particles have a well-developed and non-uniform grain size due to their amorphous nature. Moreover, the peaks of photoelectron emission for bare and doped BiFeO 3 were observed in the visible region at around 490 nm, while the emission intensity of bare BiFeO 3 was noticed to be lower than that of doped materials. Photoanodes were prepared with the paste of the synthesized sample and then assembled to make a solar cell. The natural and synthetic dye solutions of Mentha, Actinidia deliciosa , and green malachite, respectively, were prepared in which the photoanodes were immersed to analyze the photoconversion efficiency of the assembled dye-synthesized solar cells. The power conversion efficiency of fabricated DSSCs, which was confirmed from the I–V curve, is in the range from 0.84 to 2.15%. This study confirms that mint ( Mentha ) dye and Nd-doped BiFeO 3 materials were found to be the most efficient sensitizer and photoanode materials among all the sensitizers and photoanodes tested.

The optoelectronic properties of the ternary Cd 0.25 Zn 0.75 Se alloy are reported under the influence of a high pressure ranging from 0 to 25 GPa, within a modified Becke–Jhonson potential using density functional theory. This alloy has a cubic symmetry, is mechanically stable, and its bulk modulus rises with pressure. It is observed to be a direct bandgap material with a bandgap energy that increases from 2.37 to 3.11 eV with rise in pressure. Pressure changes the optical and electronic properties, causing the absorption coefficient to rise and absorb visible green-to-violet light. The static dielectric constant, along with the static index of refraction, both increase under the influence of pressure. Optical constants, including dielectric constant, optical conductivity, refractive index, extinction coefficient, and reflection, are also investigated and discussed. This DFT forecast explores important research directions for the usage of the CdZnSe semiconductor alloys in the manufacturing of space photovoltaic and optoelectronic devices operating at different pressures.

The main objective of this research study is to optimize the printing parameters that can be used in the FDM (fusion deposition modeling) production method to obtain the lowest production time and best printing parameter of PLA (polylactic acid) filament with the tensile test. The printing parameter that can be used in FDM machines such as extruder temperature, bed temperature, layer height, printing speed, travel speed, infill, and shell count is taken into account for optimization. In addition, the tensile specimens from ASTM (American Society for Testing and Materials) D638 standard were manufactured by PLA filament with the above-modified printing parameters. The best printing parameters for PLA products were found by the time recorded during production and tensile test results after production. Thus, through this research, one can find the best PLA filament printing parameters and their timing.

Histamine, a prominent biogenic amine (BA), is commonly associated with allergic reactions and is a key culprit in foodborne illnesses stemming from spoiled food consumption. The detection of histamine is paramount for meeting food safety standards and ensuring quality control. In this study, an innovative method employing the direct integration of dopamine onto citrate-reduced gold nanoparticles (DCt-AuNPs) embedded within filter paper to create a paper-based colorimetric sensor for histamine detection was developed. Various sizes of DCt-AuNPs (13, 15, 27, and 39 nm) were synthesized, and their dimensions were controlled by adjusting the precursor molar ratio (MR). This adjustment led to size variations, influencing the localized surface plasmon resonance (LSPR) peaks (518, 520, 526, and 530 nm) and resulting in distinct optical properties. The interaction between these nanoparticles and histamine concentrations (ranging from 1 ppm to 100 ppm) was monitored by observing changes in the LSPR absorbance spectra and color. Histamine induced DCt-AuNP aggregation through interactions of its amino and imidazole groups via ligand exchange and interparticle crosslinking, thereby changing the solution color from red to blue. The size variance of DCt-AuNPs significantly impacted the colorimetric response to histamine. Among the sizes tested, the 15 nm DCt-AuNP paper sensor exhibited the lowest detection limit of 2.38 µM and a linear detection range of 20–70 ppm. Remarkably, this sensor boasted rapid detection, clocking in under 1 min, coupled with exceptional selectivity toward histamine analytes, highlighting its potential for real-world applications.

The green synthesis of gold nanoparticles (AuNPs) using Mangifera indica (mango) fruit peel and its subsequent application to imbue color and antibacterial properties to cotton thread is explored in this study. Mango peels were dried, ground, and extracted with methanol and was added to gold ion solutions at 55 °C to synthesize AuNP. AuNPs were synthesized at different concentrations, producing various colors, and were successfully used to dye cotton threads via a heating method. The structural and optical properties of AuNPs were investigated by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscope (SEM), transmission electron microscope (TEM), ultraviolet–visible spectrophotometer (UV–Vis) and dynamic light scattering (DLS). The bioactive compounds of mango peel extract were determined using Nuclear magnetic resonance spectroscopy (NMR). The antibacterial potential of AuNP-dyed cotton threads was examined by disc diffusion method against E. coli and S. aureus based on the zone of inhibition. Change in color of the reaction mixture to red indicated the formation of AuNPs. The presence of UV characteristic peak around 530 nm confirmed the presence of spherical AuNPs. NMR spectrum further confirmed the presence of bioactive functional groups involved in the reduction of HAuCl 4 to AuNPs. TEM analysis displayed the shape of AuNPs with mean size of 16.90 nm whereas the hydrodynamic diameters range from 41 to 78 nm. The AuNP-dyed cotton threads showed antimicrobial activity against E. coli and S. aureus suggesting that this can be an excellent strategy to develop versatile and eco-friendly fabric-based biomedical products. The AuNP-dyed cotton threads demonstrated excellent color fastness and resistance to fading when subjected to various harsh conditions.

The microstructure and mechanical properties of an MMC based on AA 7075 and strengthened through silicon carbide (SiC) as well as boron carbide (B4C) elements were studied. The (SiC + B4C) combination was used in various weight percentages of 4, 8, 12, and 16% to create the hybrid composites utilizing the traditional stir casting procedure. XRD and SEM measurements were used to investigate the dispersion of the reinforced particles. For example, microhardness, impact strength, and ultimate tensile strength were measured on hybrid composites at room temperature. The density and porosity of the materials were also studied. The researchers found that increasing the weight percentage of the (SiC + B4C) mixture resulted in a small drop in % elongation. However, hybrid composites comprising 16% (SiC + B4C) weight reduction showed some decrease in hardness and tensile strength. Equated to unreinforced alloys, the hardness and tensile strength of hybrid composites rise by 8% and 21%, respectively. Reinforcement also resulted in a decrease in impact strength and density, as well as an increase in porosity.

A straightforward approach to recycle waste expanded polystyrene (EPS) foam to produce polystyrene (PS) microfibers using the improvised centrifugal spinning technique is demonstrated in this work. A typical benchtop centrifuge was improvised and used as a centrifugal spinning device. The obtained PS microfibers were characterized for their potential application for oil adsorption. Fourier transform infrared spectroscopy results revealed similarity on the transmission bands of EPS foam and PS microfibers suggesting the preservation of the EPS foam’s chemical composition after the centrifugal spinning process. Scanning electron microscopy displayed well-defined fibers with an average diameter of 3.14 ± 0.59 μm. At the same time, energy dispersive X-ray spectroscopy revealed the presence of carbon and oxygen as the primary components of the fibers. Contact angle (θ CA ) measurements showed the more enhanced hydrophobicity of the PS microfiber (θ CA = 100.2 ± 1.3°) compared to the untreated EPS foam (θ CA = 92.9 ± 3.5°). The PS microfiber also displayed better oleophilicity compared to EPS foam. Finally, the fabricated PS microfibers demonstrated promising potential for oil removal in water with a calculated sorption capacity value of about 15.5 g/g even at a very short contact time. The fabricated PS fiber from the waste EPS foam may provide valuable insights into the valorization of polymeric waste materials for environmental and other related applications.

Long-term trends of atmospheric pollutants, particularly ozone (O 3 ) and particulate matter (PM) provide a direct evaluation of the response of the atmosphere to the environmental policies and the variability of anthropogenic and biogenic emissions. Here, we report the assessment of the temporal evolution of the air quality in a tropical urban city (Butuan) in the southern Philippines by evaluating the trends of meteorological conditions (i.e., temperature, R.H., boundary layer height), air pollutants (i.e., PM 2.5 , NO 2 , O 3 ) and their precursors (Benzene, Toluene, and Xylene) from 2014 to 2020. During the seven-year measurement, the mean PM 2.5 and PM 10 mass concentrations were 8.7 ± 3.9 and 24.3 ± 12.0 µg m −3 , with no single day exceeded the daily PM limit. The max concentrations of aerosol occurred during the dry season when the loss of particles through wet deposition was limited. Speciation of PM 2.5 indicated that fine aerosol was dominated by sea salt and organic matter (OM). Analysis of the ratio of OM and sulfate indicated that the main source of pollution in the city was wildfire/biomass burning. The average O 3 and NO 2 mixing ratios during the same period were 22.3 ± 9.5 ppb and 8.1 ± 5.4 ppb while increasing at the rate of 0.409 ppb year −1 and 0.683 ppb year −1 . The highest O 3 concentration occurred during the summer months when photochemistry enhanced the formation of tropospheric O 3 . The increasing O 3 trend was attributed to the contribution of anthropogenic VOCs (AVOCs), based on their ozone-forming potentials (OFPs). The seven-year measurement also showcased the variability of the atmospheric pollutants during the COVID-19 pandemic of 2020, when O 3 substantially increased due to reduced vehicle transport activities. Overall, our results provide insights to better comprehend the sources of the variability of O 3 and PM on a long-term temporal scale, as well as implications on relevant environmental policies in controlling air pollutants in a tropical developing region.

In this research, the first work was carried out to manufacture MgO-based metal matrix composite containing 3 wt%. Sintering parameters, such as temperature, pressure, and time were subjected to Taguchi analysis to identify the most significant effect on magnesium oxide physical and mechanical characteristics. The impact of each sintering parameter explores using the analysis of variance-structure and microstructure analysis using XRD and EDS-equipped FE-SEM. The mechanical properties of the composite are evaluated by testing its Rockwell hardness (HR) and Vickers hardness (HV). The results showed that sintering temperature was the most influential of the sintering factors on microhardness. Densification at its peak was 100%, while it peaked at 62.19 Rockwell hardness and 58.7 Vickers hardness.

Carbon nanotubes (CNTs) and graphene, in particular, have been the subject of many recent studies since their discovery in the early 2000s. Because of their unusual properties, carbon nanotubes (CNTs) have piqued the interest of scientists across a wide range of disciplines. An Al matrix was reinforced with powder metallurgy-fabricated B4C and CNT composites. The nanocomposite aluminium matrix was examined for tribological behaviour, density, stiffness, and compressive strength before and after hot isostatic pressing (HIP). Scanning electron microscopy and TEM were used to analyze the carbon nanotubes and their hybrid counterparts (SEM). The density of nanocomposites was reduced by 38% without HIP but by 45% after it was added to the mixture. Hardness was also increased by 40%, but following HIP, the hardness rose to 67%. Before and after HIP, the compression strength increased by 39% and 60%, respectively. HIP improves the wear rate by 45%, and B4C and CNTs improve the coefficient of friction by 20% in all volume fractions but only by 48% in the case of nanocomposites.