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.

Introduction: Thermal insulating coatings are increasingly being introduced into construction practice for internal and external finishing enclosing structures and pipelines. Thermal insulation coatings are usually made based on polymer binder and mineral fillers. The durability and stability of the properties of heat-insulating materials depend on the type of binder. As a rule, polymers are used as a binder: epoxy resin; silicone rubber; urea-formaldehyde resins; aqueous dispersed polymers - styrene-butadiene, polyvinyl acetate, and acrylate (acrylic and styrene-acrylic). The quality indicator of binders can be assessed by the influence of the seasonality of climatic impact, and as a result, the best elastic strength characteristics of binders can be established after one month to a year of field tests. Aim: To determine the influence of climatic factors on the change in the elastic-strength indicators of epoxy polymers binders used in liquid thermal insulation coatings. Methods: A tensile testing machine of the AGS-X series with the TRAPEZIUM X software was used for mechanical tests. The tests were carried out in accordance with GOST 11262-2017 (ISO 527-2: 2012) "Plastics. Tensile test method". Results and Discussion: The paper discusses the results of experimental studies of the compositions of polymer binders and their resistance to various climatic factors, which will later be used as a polymer binder for thermal insulation coatings based on fine mineral granular systems. Conclusions: When analyzing the changes in the characteristics of polymer samples after exposure to climatic factors, it was found that compositions based on Etal-247 epoxy resin, cured with amine hardeners Etal-1440N, Etal-1460, Etal-1472, and Etal-45M, demonstrate the best elastic strength characteristics after one year of full-scale tests. The high stability of the indicators under consideration allows us to conclude that the use of Etal-247 resin as a base leads to creating of the most climate-resistant epoxy coatings.

Background: Candidiasis, caused mainly by Candida albicans yeast, is a pathology that affects a significant amount of people in the world, mainly women, thus being a public health issue. In addition, clinical practice has found it difficult to treat candidiasis for two reasons: the multidrug resistance associated with the exacerbated use of available drugs and the high number of side effects caused by current antifungal drugs. In this scenario, this work is a literature review on the antifungal activity of metal complexes against C. albicans since they are extensively studied for their varied applications in health sciences, as an object of study in the area of inorganic chemistry, in the subareas of bioinorganic chemistry and pharmaceutical chemistry. Aim: The present work consists of a literature review in electronic databases on the potential antifungal action against Candida albicans presented by metal complexes. Methods: Data was collected using the Capes, PubMed, Cochrane Reviews and Virtual Health Library (BVS) databases. Results: The results obtained through bibliographic surveys show the importance of studies of metal complexes against the strain of C. albicans, which have promising inhibitory activities and in some cases, with Minimum Inhibitory Concentration (MIC) values lower than 20µg/mL Discussion: The results obtained through bibliographic surveys show the importance of studies of metal complexes against the strain of C. albicans, which have promising inhibitory activities, and in some cases, with Minimum Inhibitory Concentration (MIC) values lower than 20µg/mL. Conclusion: Highlighting the activity performed by ruthenium complexes and Schiff bases when coordinated to metallic ions arouses great interest in a future study of a complex of this metal with a Schiff base in its coordination site.