SOUTHERN JOURNAL OF SCIENCES

Background: In line with the current global energy crisis, there is an urgent need to seek cheap energy sources. This study has utilized waste materials for synthesizing biodiesel, an environmentally friendly alternative energy. Aim: This study aimed to prepare low-cost carbon-based zirconium impregnated heterogeneous catalysts using wood dust to produce biodiesel from waste vegetable oil (WVO). Methods: Response Surface Methodology via Central Composite Design (RSM-CCD) optimized the biodiesel production process. The physico-chemical properties of waste vegetable methyl ester were determined following the American Standard Testing of Materials (ASTM). In addition, the catalyst morphology and elemental composition were determined using Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray (EDX), respectively. Results and Discussion: The optimum conditions were observed to be 8:1 methanol/oil ratio, 5 wt% catalyst loading, 55 °C temperature, and 3 hours of reaction time. The corresponding response was observed to be 98.39%. Conclusions: The experimental analysis confirmed that the synthesized catalyst from wood dust under optimized conditions transesterified the waste vegetable oil into biodiesel with properties that comply with American Standard Testing of Materials.

Dentistry is a part of medicine, where various polymer materials were used for the first time. Many factors forced researchers to find more stable, versatile, and hygienic materials for the manufacture of dental products. It is important to note that the search for the ideal polymer dental material is still ongoing. This is because modern polymers, in some cases, do not meet the specified requirements for chemical, physical, strength, and elasticproperties. Based on the data on the method of creating and using silicone material for the base of the removable prosthesis "Gossil", an improved silicone material for two-layer dentures "Silep" was developed, as well as a special primer for better connection of the lining with the rigid acrylic base of the prosthesis. To evaluate the most suitable compound, materials were tested for several parameters, such as tensile strength, elongation, and shore hardness. In addition to selecting a suitable material for modification, the selection and testing of an adhesive that allows the chemical bonding of the acrylate surface to the siloxane surface were carried out. 

Background: The interview with Professor José de Ribamar, conducted by Luís de Boni, addresses various aspects of his career and contributions to chemistry in Brazil. The conversation includes his experiences in teaching, research, and university administration, as well as his role as President of the Federal Council of Chemistry (CFQ). Aims: The primary aim of the interview is to highlight Professor Ribamar's achievements and challenges throughout his career, and to explore his views on chemistry and its impact on scientific and educational development in Brazil. Methods: The interview was conducted in a question-and-answer format, allowing Professor Ribamar to share his experiences and insights in a detailed and personal manner. The interview was recorded, transcribed, and is available in both text and video formats. Results: Professor Ribamar detailed his academic and professional journey, including his undergraduate and graduate studies in chemistry, his contributions as a professor at the Federal University of Maranhão (UFMA), and his initiatives as a course coordinator and department head. He also discussed the impact of his research and his vision for the future of chemistry, emphasizing the importance of artificial intelligence and algorithms in predicting chemical models. Discussion: The interview provided a comprehensive overview of Professor Ribamar's contributions to chemistry in Brazil. He emphasized the importance of education and ongoing research for scientific advancement, as well as the need to adapt to new technologies. The discussion also addressed the challenges the scientific community faces and the importance of interdisciplinary collaboration. Conclusion: Professor José Ribamar has significantly promoted and developed chemistry in Brazil in academia and public administration. His career illustrates the importance of dedication to education and research, and his reflections offer valuable lessons for future generations of scientists and educators. The interview serves as a testament to his lasting impact on the scientific community.

This study was designed to examine the DPPH free radical-scavenging activity, in different concentrations (0.025, 0.05, 0.07, 0.1, 0.2, 0.04 and 0.6) of methanolic extracts of Salvia nemorosa L. collected from the northwest of Iran (Zonouz and Ardabil regions) at two-stage of growth (vegetative stage leaves, flowering stage leaves, and flowers). The result showed that the mean of inhibition percentage in the Zonouz region increased in various concentrations and between flowers, vegetative stage leaves, and flowering stage leaves, compared with the plants of the Ardabil region. In each of the regions of Zonouz and Ardabil, the highest amount of DPPH inhibition was observed in the vegetative stage leaves in comparison with flowering stage leaves and flowers. In addition, in the effect of DPPH radical trapping in different concentrations of methanolic extracts of Salvia nemorosa L. was observed that from each of the collected region, methanolic extracts from sage plants were dose-dependent and acted very effective and useful and the best antioxidant activity was in the high concentration of extracts, So in Zonouz and Ardabil regions, the content of inhibition of DPPH increased significantly, by increasing the concentration of 0.025 mg/ml to 0.6 mg/ml and in Zonouz region the content of inhibition of DPPH similarly increased in 0.2, 0.4 and 0.6 mg/ml concentrations. In the Ardabil region, the most content of inhibition of DPPH was seen in 0.4 mg/ml and 0.6 mg/ml concentrations, but in this region, the content of inhibition of DPPH in 0.2 mg/ml concentration there was only in vegetative stage leaves and flowering stage leaves.

Biomass is the term attributed to any renewable resource derived from organic matter that can be used in energy production. Agricultural production generates residues that are of great importance for their energy use, of which sugar cane, eucalyptus, and rice. Various residues are generated from rice cultivation, among which the rice husk and rice straw are the most important. Several thermal conversion technologies have been developed for the use of biomass in industry. Pyrolysis has been notable for its ability to produce biofuels at different stages of aggregation. The slow pyrolysis of biomass has been proposed as a pretreatment method to improve the physical-chemical characteristics of rice straw. In this process is produced, mainly, a solid called biochar, which has a higher energy content when compared to the biomass of origin. This study investigated the slow pyrolysis of rice straw at 300 - 700°C for the purpose of obtaining biochar, bio-oil, and gases for energy purposes. The experimental results show that pyrolysis temperature has important roles in yield product. The highest biochar yield was observed at a temperature of 300°C with 49.91 wt%. This represents 47% more when compared to yield at 700°C (33.87 wt.%). This behavior is linked to the proximate analysis results for fixed carbon 26.01 wt.% at 300°C. The high pH of the biochar was attributed to the presence of alkali metals, according to XRF. Thermal decomposition of the biomass resulting in a gradual increase of bio-oil (16.81 - 34.70 wt.%) and gas (6.53 - 18.05 wt.%) on a wet basis. Thus, in the dry base parameter, the bio-oil increases from 19.22 - 30.6 wt.% and the gases at 9.42-20.19 wt.%. Drying of the raw material showed, by the results, a significant increase in the co-products.

Cast iron alloys combine many elements such as carbon, iron, silicon, magnesium and can be usually classified according to their microstructure in ductile, gray, compacted, white, and malleable. Each one has particularities in terms of properties and applications. Hence, this study aims to evaluate the degree of nodularity (%) in a ductile cast iron alloy GGG 40. In this context, a methodology to investigate the degree of nodularity wasproposed. The ultrasonic method was used to determine the amount of ductile graphite as well as for parts release and thus facilitated the industrial operational execution. The effect of ultrasonic sound was investigated in sixtyseven ductile cast irons, and these analyses were further compared to the level of nodularity observed by metallography. Finally, based on the findings, the cast iron quality was guaranteed, leading to time savings, avoiding the microstructural examination, and thus promoting cost reductions.