SOUTHERN JOURNAL OF SCIENCES

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: Recently, research has been carried out to improve the efficiency of electronic devices in general. With the commercial search for consolidated materials and the growth in demand with monitoring of costs, research has sought to minimize these effects with the replacement or functionalization of other substances, which may be applied at lower costs without compromising operating yields already achieved. Objective: This work aimed to obtain molecular modeling and reactivity parameters of -caprolactam and o-phenanthroline to evaluate the interaction capacity in the formation of molecular systems. Conductance measurements were taken to observe the electrolytic behavior. Infrared and UV-visible spectra were recorded to characterize vibrational transitions and evaluate spectrochemical properties. Methods: The WebLab program was used to obtain structural data and calculate reactivity parameters. Conductance was obtained in QUIMIS Q-405 equipment. IR spectra were recorded on PERKIN ELMER FRONTIER equipment. UV-vis spectra were recorded in a SHIMADZU equipment 200 – 1000 nm range to record the main transitions. Results and Discussions: Electron donor atoms are centered mainly on oxygen and nitrogen, respectively, which are sterically more favorable. The behavior was non-electrolyte. Groups with vibrational transitions sensitive to chemical interactions are comprised of C=N, C-N, and C=O bonds. The  parameter indicates transitions in the 190 – 300 nm region and the near-infrared, and the oscillator strength is typical of molecules used as dyes and sensitizers in optical light-emitting systems or light-to-electricity converters. Conclusions: We observed that these ligands have a donor capacity for the formation of complex systems that meet the need for electron transfer in optical pumping devices for the intensification of transitions or radiation converters, which can also be applied in radiation-to-electricity converter systems.

Background: Dr. Miguel Fornes is a researcher at CONICET and director of the Andrological Research Laboratory of Mendoza, Argentina. His research focuses on how dietary fat excess and hypercholesterolemia affect sperm physiology and male fertility. Objectives: The primary objective of Dr. Fornes' research is to investigate the effects of a high-fat diet on sperm function, capacitation, acrosomal reaction, and fertilization. He aims to develop translational animal models to study these effects without using human subjects. Methods: Dr. Fornes and his team use rabbit models to induce hypercholesterolemia through a high-fat diet. They then study the physiology and function of sperm cells from these hypercholesterolemic rabbits. Key parameters analyzed include cholesterol content in sperm membranes, ability to undergo capacitation and acrosomal reaction, and fertilization capability. Results: The studies revealed that hypercholesterolemia caused by a high-fat diet leads to increased cholesterol levels in sperm. This interferes with the normal physiology of sperm cells. In particular, many sperm from hypercholesterolemic rabbits were unable to properly undergo the acrosomal reaction, a crucial step for successful fertilization of the oocyte. This suggests high-fat diets could contribute to male infertility. Conclusions: The research highlights the importance of diet and lifestyle on male reproductive health. Dr. Fornes recommends a balanced diet like the Mediterranean diet, rich in fruits, vegetables, and olive oil, to maintain healthy sperm function and fertility. Replacing animal fats with olive oil may help prevent hypercholesterolemia-related infertility. The findings have implications for dietary guidelines and clinical interventions to support male fertility.