SOUTHERN JOURNAL OF SCIENCES

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.

Background: MQ-series gas sensors belong to the metal oxide semiconductor (MOS) family of sensors that can sense the presence of many gases. These sensors find their application in gas alarm systems as key components. While necessary sensor circuit output voltage value for alarm point in a stand-alone gas alarm system is desirable, but what exact combination of the sensor circuit parameters is required? Hitherto, the determination of these circuit parameters has not been given much attention in the research community. Aim: the purpose of this work is to explore a structured graphical approach of determination of MQ series gas sensor circuit parameters for a stand-alone gas alarm system that yields desired sensor circuit output voltage value for the alarm point; the main objective of the study was to develop mathematical model equations that relate the: (i) sensor resistance (RS) with the gas concentration (x) and the sensor resistance at standard calibration concentration of the sensor base gas in the clean air (Ro) and (ii) sensor circuit output voltage (VRL), load resistance (RL) and sensor resistance (RS). It is expected from the model equations developed that graphical correlations of the sensor circuits parameters will be generated. Using these graphs for a particular case of an MQ-4 gas sensor under the influence of LPG, the parameters that yield desired sensor circuit output voltage of 2V for 1000 ppm of LPG alarm point will be determined. Methods: Model equations were developed for the sensor dynamics, and based on these model equations, graphs for the determination of required sensor parameters were plotted for a case of MQ-4 gas sensor response to LPG. Results and Discussion: The results yielded optimal values for R_O,R_S and R_L of 20 kΩ, 30 kΩ and 20 kΩ respectively, for alarm settings of 1000 ppm and a desired sensor circuit output voltage of 2 V. Based on determined parameters, the calibration equation for determination of best concentration value for a given value of emulated LPG concentration was developed. Using the method proposed in this study makes the process of determining the MQ-series gas sensor circuit parameters less cumbersome as their value can easily be obtained from the resulting graphs. Conclusions: a structured graphical approach for determination of MQ-series gas sensor circuit parameters for alarm points in a stand-alone gas alarm system showed that using MQ-4 gas sensor and LPG as the target gas, and for a sensor circuit output voltage of 2 V for alarm point at 1000 ppm of LPG, the corresponding value of R_O, R_S and R_L obtained were 20 kΩ, 30 kΩ, and 20 kΩ respectively. Hence, a structured graphical approach is suitable for determining MQ series gas sensor circuit parameters for a stand-alone gas alarm system under the influence of its associated gases.

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.