Key Engineering Materials Vol. 1028

Abstract: This study investigated the potential of acid-pretreated rice husk ash (RHA) sourced alkaline earth metal silicates for lauric acid (LA) adsorption. The synthesized materials were characterized using BET, FTIR, XRD, EDS, and SEM analyses, demonstrating that metal cation size had a notable effect on surface area, pore structure, crystallinity, and particle aggregation. Magnesium silicate (MS-1.0), with its smaller atomic radius, exhibited the highest surface area and the most porous structure among the samples. Calcium silicate (CS-1.0) displayed a moderate surface area with a mesoporous structure, while strontium silicate (SS-1.0), having the largest atomic radius, exhibited the lowest surface area, a predominantly macroporous structure and the highest degree of particle aggregation. The synthesized alkaline earth metal silicates were tested for LA adsorption performance and compared using the analytical hierarchy process (AHP). CS-1.0 demonstrated the highest LA removal efficiency (59.94% ± 11.24%) and adsorption capacity (8.68 ± 1.60 mmol/g), while MS-1.0 had the lowest removal efficiency (17.64 ± 3.28%) and adsorption capacity (2.60 ± 0.50 mmol/g). Interestingly, the production yield increased from MS-1.0 to CS-1.0 and SS-1.0. Through the AHP method, CS-1.0 was identified as the best-performing adsorbent in this study, considering both adsorption efficiency and production yield with the highest priority value of 0.9603.

Abstract: The Philippines still relies heavily on oil and coal as energy fuel sources, contributing to approximately 63.21% of the energy mix. It is crucial to seek alternative feedstock that can comply with the increasing demand. This study thus investigated the energy potential of bolo (Gigantochloa levis (Blanco) Merrill) along the bottom, middle and top culm height portions, for bioenergy applications. The top culm was consistently observed to have the lowest moisture contents and the highest relative (0.4757 g/mL) and bulk (0.2003 g/mL) densities. Proximate analysis revealed a significant increase in average fixed carbon (FC) content from top (19.18%) to bottom (20.88%), while ash content showed the opposite trend, ranging from 3.59% to 5.92%. The average volatile matter (VM) content (74.90% - 75.53%) showed no significant variation along the culm. Lignin content was also analyzed and its correlation with FC and VM reveal a parabolic relationship with R² values of 0.84 and 0.63, respectively. Despite the top section having the lowest higher heating value, its higher density and lower moisture content resulted in the highest calculated energy density (8.13 GJ/m³ in chipped form), suggesting that the top portion has the best potential as a biomass energy source for direct combustion.

Abstract: The purpose of this study is to investigate the effect of PAMAM G4NH2-Ag and G4OH-Ag nanocomposits on algae (cyanobacterium) Arthrospira platensis (spirulina) as a model at various conditions using UV-visible spectroscopy. It is known that the efficiency of energy production in photosynthetic microorganisms is partly determined by light absorption. In our case, we observed an increase in absorption in the region corresponding to chlorophyll a under various conditions when PAMAM G4NH2-Ag and PAMAM G4OH-Ag nanocomposits were added to spirulina. From these data, we may conclude that the photoactivity of chlorophyll a in spirulina is enhanced through the action of PAMAM G4NH2-Ag and PAMAM G4OH-Ag nanocomposits in vivo. This effect persisted regardless of dendrimer type, spirulina fermentation, freezing at different temperatures, or high-dose irradiation followed by re-cultivation.

Abstract: The influence of G4 poly(amidoamine) dendrimers or PAMAM–gold nanocomposites (G4NH2–Au, G4NH2 PAMAM dendrimer ethilenediamine core, generation 4). (NH2)₆₄ on Arthrospira platensis was studied under various conditions. Our findings demonstrate that these gold nanocomposites interact with both chlorophyll a and proteins in the cyanobacterium. Notably, the interaction between chlorophyll a and PAMAM G4NH2–Au nanocomposites persisted despite exposure to various factors, including temperature changes and high doses of irradiation. PAMAM–Au nanocomposites were found to enhance the natural functionality of the photosynthetic microorganism Arthrospira platensis and remained effective under diverse conditions. This enhancement is likely due to the increased light absorption potential resulting from the incorporation of nanocomposites into the microorganism’s cellular constituents.

Abstract: The paper presents new data on the complex use of colloidal solutions of nanoparticles (NPs) and low-intensity laser radiation on the biosynthetic activity of the edible medicinal mushroom Lentinula edodes (L. edodes) in vitro. Traditional mycological methods, colloidal solutions of metals (Ag, Fe, and Mg NPs), and unique photobiological methods were used. An argon laser at wavelength of 488 nm was used as a source of coherent visible light. It was found that colloidal solutions of NPs of all used metals increased (26–39%) the growth characteristics of L. edodes, while irradiation of the fungus inoculum with laser light in a medium with NPs reduced the growth activity of the L. edodes mycelium. The addition of all NPs to the nutrient medium with the inoculum inhibited the synthesis of extracellular polysaccharides, the greatest effect was observed with Fe NPs. At the same time, laser light irradiation in the presence of NPs increased the amount of extracellular polysaccharides; the greatest effect was observed in photoinduced Mg NPs, which stimulated the synthesis of extracellular polysaccharides by 47%. The introduction of NPs into the inoculum reduced the amount of intracellular polysaccharides in the mycelial mass; the greatest inhibitory effect of 50% was observed for Ag NPs. At for the photoinduced NPs, they stimulated the synthesis of intracellular polysaccharides in the mycelial mass of L. edodes. Treatment of the inoculum in a medium with NPs and photoinduced NPs caused an intensification of the synthesis of phenolic compounds in the mycelial mass and an increase in radical scavenging activity (RSA). The highest RSA values were recorded for samples obtained from inoculum treatment with photoinduced Fe and Mg NPs, respectively, for methanol and ethanol extracts of mycelial mass. The obtained results suggest the possibility of complex use of colloidal solutions of Fe, Ag, and Mg NPs and low-intensity laser radiation as environmentally friendly factors regulating biosynthetic activity in biotechnology of cultivating the valuable medicinal fungus L. edodes.