ELECTROCHEMICAL BEHAVIOR OF A COMPOSITE MATERIAL OF SOLID BIOPOLYMER ELECTROLYTE FROM CASSAVA STARCH / GRAPHENE OXIDE PREPARED AT DIFFERENT pH

Background: Composite materials make it possible to modulate the properties of the source materials and expand their technological potential. In this sense, composite materials made from solid biopolymeric electrolytes and graphene oxide can be an attractive alternative for applications in organic electronics due to their electrochemical properties. Aim: The present work aims to evaluate the electrochemical behavior of a composite material made of solid biopolymeric electrolyte of cassava starch and graphene oxide at different concentrations to determine the effect of this concentration and the pH used in the production process. Methods: The composite material was made from the use of cassava starch plasticized with glycerol, glutaraldehyde, polyethylene glycol and with lithium perchlorate as electrolytes. During the synthesis process, graphene oxide was added in different concentrations (0, 0.25, 0.50, 1.00, 1.25, 1.50, and 1.75 %w/w) to evaluate the effect of the concentration of this component. The synthesis was carried out by thermochemical method with constant heating in an oven at 75 ° C for 48 hours. Films were prepared using synthesis solutions at different pH (5.0 and 9.0). The pH was regulated by adding HCl or NaOH to the synthesis solution as appropriate. Results and Discussion: The results showed that the cassava starch biopolymeric solid electrolyte films without plasticizers were stiff and brittle, so they broke easily. The films with plasticizers and the films of the composite material were stable to the manual traction, allowing their easy manipulation without breaking. The films presented a similar electrochemical behavior in terms of oxide reduction processes; however, the films with graphene oxide presented signals with higher peak currents. Films made at pH 9.0 showed 50 % more intensity in peak currents. The addition of graphene oxide affected the current parameters and peak potentials, being more marked in the films prepared at pH 9.0; at this pH the films with concentrations of graphene oxide lower than 1.00 %w/w presented variable Ep and Ip, while at concentrations of graphene oxide greater than 1%w/w, the behavior did not show significant variations. Conclusions: The addition of graphene oxide modulates or modifies the electrochemical behavior of cassava starch biopolymeric solid electrolyte films, and the processing pH can vary the effect of the graphene oxide addition.

SYNTHESIS OF NEW SUBSTITUTED PROCAINE HYDROCHLORIDE COMPOUNDS AND THEIR USE IN SPECTROPHOTOMETRIC DETERMINATION OF TETRACYCLINE HYDROCHLORIDE THROUGH DIAZOTIZATION-COUPLING REACTIONS

Background: Tetracycline is one of the most important antibiotics. It is used to treat many different bacterial infections. It is often used in treating severe acne, or sexually transmitted diseases such as syphilis, gonorrhea, or chlamydia. In some cases, tetracycline is used when penicillin or another antibiotic cannot be used to treat serious infections such as the ones caused by Bacillus anthracis, Listeria, Clostridium, Actinomyces. Aim: synthesized a new novel reagent used to determine TCH spectrophotometrically by using diazonium and coupling reaction. Methods: Four new substituted procaine derivatives were prepared by simple organic methods using aniline derivatives. A spectrophotometric approach was established for the micro-determination of TCH. The stoichiometry was investigated using mole ratio and continuous variation methods, and the stability constant was also estimated. The ΔG, ΔH, and ΔS were determined as thermodynamic parameters for evaluating the effect of temperature on the reaction. Results: Substituted procaine derivatives were prepared, and o-hydroxy procaine seems to be the best reagent used to determine TCH by diazotization and coupling reaction. The result was a yellow water-soluble dye with a maximum absorbance of 380 nm. The reaction conditions were studied and optimized. Beers law was obeyed over a concentration range (2.5–50) μg.mL-1 for TCH. The molar absorptivity was (14.4669.103) L.mol-1.cm-1, and the detection limit was (0.5052) μg.mL-1. The stoichiometry of the formed product was found 1:1 (o-hydroxyprocaine: TCH). The stability constant indicated that the product formed was stable, and the thermodynamic parameters showed that the diazonium salt reaction was preferred to occur at a low temperature. Conclusions: a simple, accurate, and fast method was developed to determine TCH in pure form and pharmaceuticals by coupling the TCH with a newly synthesized procaine derivative reagent (o-hydroxy procaine) in a basic medium.

STRATEGIC PLAN TO STRENGTHEN RESEARCH AS A MECHANISM TO INCREASE MEANINGFUL TRAINING BASED ON FORMATIVE RESEARCH

Background: The academic activity of students and professors constitutes the basis of professional training in engineering. Training in electrical engineering has always been of less interest to university students compared to other professional training programs. However, in recent years, this interest has decreased beyond previous trends, an effect detected in all engineering programs, which has been accelerated by the distance learning mechanisms adopted in the face of the spread of COVID-19. Therefore, among the incentive mechanisms for young people, the promotion of research activity has been included. This study describes the model proposed within the Electrical Technology and Engineering programs of the Universidad Distrital Francisco José de Caldas as a distinctive element of its research training strategy. Aims: To offer alternatives tending to promote the current research activities of the research groups of the electrical engineering area of the Universidad Distrital (Colombia) to increase the performance of the formative research processes, in particular with motivational aspects, development of critical awareness, and strengthening of resilience. Methods: A strategic plan was developed to increase the activity related to research processes within the academic program. It was based on the dynamics shown in the last seven years, and a set of strategies aimed at strengthening and encouraging this trend was projected for the next seven years. Results and Discussion: This strategic plan is expected to increase academic activity, particularly related to scientific production indicators. Projections for the next seven years indicate an increase in student participation related to scientific publications, the population in research groups, and project development. Conclusions: The proposed scheme corresponds to a model adjusted to higher education institutions with student populations of low academic strata and under national standards that prioritize quality in education from the point of view of both physical and human resources, particularly those that promote critical awareness of local and national reality. In this sense, the proposed plan is highly relevant and promotes one of the strengths identified in the academic program.

USE OF ENHANCED FEEDBACK IN AN ELECTRONIC LEARNING COURSE “FUNDAMENTALS OF MOLECULAR PHYSICS AND THERMODYNAMICS”

Background: Being an essential part of the educational process, blended learning still faces some problems concerning the interaction between teachers and students. They include a decrease in the level of knowledge and in the number of graduates as students experience a lack of live communication with the teacher, lack of sufficient experience of independent work, lack of interactive assessment. Aim: This study aimed to elaborate the model of enhanced feedback in an e-learning course, “Fundamentals of Molecular Physics and Thermodynamics,” to increase student educational achievements. Methods: The effectiveness of the model of enhanced feedback in the learning process was measured with the methodology for calculating statistical indicators of the quality of education: knowledge quality, level of student proficiency, progress, and average grade. To measure the emotional and evaluative attitude of students to educational activities and interaction with the teacher in an electronic course, a test-questionnaire satisfaction with learning activity was employed. Results and Discussion: the results of the initial and final control of the statistical indicators of the quality of education including knowledge quality, level of student proficiency, progress, and average grade in students showed a significant difference between the control and the experimental groups. At the end of the semester, the difference in knowledge quality was 23%, student proficiency level – 13%, progress – 3.5%, average grade – 0.6 scores. The analysis of student satisfaction with the learning process also confirms an increase in satisfaction with the learning process and with the interaction with the lecturer. Thus, the experimental methodology contributes to a significant improvement in the learning process results. Conclusions: The experiment demonstrated that replacing formative assessment with the model of enhanced feedback raises student educational achievements and compensates for lack of live communication with the teacher.

LEARNING INNOVATION OF INSTRUMENTAL ANALYSIS LAB WORK FOR IMPROVING STUDENTS NEW LITERACIES AND LEARNING MOTIVATION IN THE COVID-19 PANDEMIC

Background: The COVID-19 outbreak has changed education dramatically. Teaching and learning are undertaken remotely and on digital platforms. Therefore, learning innovation needs to be carried out to keep and maintain the learning objectives. Unfortunately, some courses are challenging to carry out remotely, such as Instrumental analysis labwork. This chemistry labwork involves using modern analytical instrumentation, such as HPLC, AAS, and GC. Aim: In this study, an innovation of an online learning model of instrumental analysis labwork for chemistry students was carried out. The innovation aims to provide authentic and motivational experiences for students while learning remotely. Methods: The first innovation was carried out by verification experiments using an interactive virtual pH meter and visible spectrophotometer. The second was carried out by designing a creative project-based experiment. The experiment determined the concentration of colored solutions by utilizing digital cameras or smartphones and color image analysis software as a substitute for a visible spectrophotometer. The implementation of experiments with interactive virtual media was intended to introduce various analytical instrumentations. In addition, this also trained the students in processing and interpreting experimental data. Meanwhile, the project-based experiments were intended to prepare students to design and apply an experiment, then analyze and report the results creatively. Results and Discussion: The authentic assessment resulted in data literacy, technological literacy, and human literacy having high and very high criteria, namely 89%, 95%, and 95%, respectively. Meanwhile, students abilities in designing projects and processing data need to be improved. Conclusions: In general, the learning innovation developed is proven to increase the learning motivation of all students.

COMPARATIVE ANALYSIS OF THE EFFECT OF HORMONE-INDUCED STRESS ON HEMOSTASIS IN THE CYPRINUS CARPIO AND THE OREOCHROMIS NILOTICUS

Background: The mortality of freshwater fish due to stress during various production manipulations is a severe problem, which requires a thorough understanding of the basic mechanisms involved, including the hemostasis system. Therefore, on the application level, the study of blood clotting can perform fish coagulopathies diagnostics and develop practical preventive and therapeutic anticoagulation methods for fish farming. Aim: The goal of this research was a comparative assessment of the reaction of some hemostasis parameters of two commercial fish species, carp Cyprinus carpio and tilapia Oreochromis niloticus, to the stress of different duration induced by corticosteroids. Methods: The fishes were divided into three groups: chronically stressed (induction by betamethasone), acutely stressed (induction by dexamethasone), and control animals with blood taken from the caudal hemal canal before hormone treatment(by dexamethasone and betamethasone), then 7 and 21 days after. Results and Discussion: Changes in the following parameters were studied: thrombin time, prothrombin time, activated partial thromboplastin time, the concentration of fibrinogen, soluble fibrin monomer complexes, antithrombin. It was found that both hormone-induced stress and handling stress associated with blood sampling strongly increased blood clotting ability in carps (prothrombin time decrease by 78,5-86,1%, fibrinogen increase by 12,7-100%, thrombin time decrease by 83,4-85%, and antithrombin III decreases by 15,3-21,7%), while in tilapias, acceleration of blood clotting by intrinsic and extrinsic pathways were recorded by the end of the experiment only in fishes with imitation of chronic stress (prothrombin time decrease by 76,8%, activated partial thromboplastin time decrease by 20,0%, and 2,3 multiplying soluble fibrin monomer complexes). Conclusions: It was concluded that the adaptive mechanisms of the tilapia (Oreochromis niloticus) organism allowed the clotting function to recover in most cases by the end of the experiment in all groups of fish, in contrast to carps (Cyprinus carpio).

THE IMPACT OF INTENSIVE RAISING OF AUSTRALIAN HOLSTEIN HEIFERS ON THE PHYSICOCHEMICAL PROPERTIES OF COW MILK

Background: The study of growth, development and productivity features of imported cattle from Australia to the Krasnodar Territory is of great scientific and practical interest, which is topical. Since the productive features of the imported genotypes have not been studied sufficiently, not only in the farms of the Krasnodar Territory but also in other regions of Russia, they require further, more in-depth study and improvement under the new conditions of feeding and housing. Aim: The research aimed to study the influence of intensive rearing of replacement heifers of the Holstein breed of Australian selection on cow milk quality indicators. Methods: The studies were conducted at Artex-Agro LLC, Kushchevsky District of the Krasnodar Territory, concerning the descendants of the imported Australian Holstein cattle. Sixty-four heifers were selected for the study. The experimental replacement heifers were raised using the enhanced milk feeding rates and the Cellobacterin probiotic product. They were raised intensively and inseminated when they were 14 months old. The milk productivity of cows and the physicochemical properties of milk were studied during three lactations after calving. Results and Discussion: The milk productivity of the cows from the experimental groups has exceeded one of their herd mates from the control group by 450 – 1,360 kg. The best indicators of the physicochemical properties of milk have been determined in the milk of the cows raised from the heifers fed with 450 kg of the whole milk during the first 50 days until they were six months old. Conclusions: The authors believe that intensive rearing of replacement heifers positively affected the degree of development of their gastrointestinal tract and improved the level of milk yield and its physicochemical parameters.

INVESTIGATING THE KNOWLEDGE, ATTITUDE, AND PRACTICE OF PREGNANT WOMEN ABOUT PERIODONTAL HEALTH AND ORAL HEALTH, AND THEIR EFFECT ON THE FETUS DURING PREGNANCY

Background: Periodontal infection leads to adverse pregnancy outcomes such as preterm delivery, low birth weight, preeclampsia, miscarriage, or early pregnancy loss. Aim: The aim of this study was to investigate the knowledge, attitude, and practice of pregnant women about periodontal health and oral health and their effect on the fetus. Methods: The present study is a descriptive-analytical study on 210 pregnant women in the first and second trimesters referring to health centers in Birjand in 2019. The tool used in this study was a researchermade questionnaire with four parts: women's demographic information, and women's knowledge, attitude, and practice, the validity, and reliability of which were confirmed. After data collection, it was entered into SPSS software version 22 and then analyzed using descriptive statistics, independent t-test, and one-way analysis of variance. The significance level was considered 0.05 in all tests. Results and Discussion: In this study, the mean scores of knowledge, attitude, and practice of pregnant women were 5.6 ±1.92, 55.9 ± 5.1, and 25.9± 3.7, respectively. There was a significant difference between the mean attitude score and mothers' age. There was also a significant difference between the mean scores of knowledge, attitude, and practice of women and significant difference in knowledge, attitude, and practice of employee and housewife pregnant women; In terms practice, there were significant differences between pregnant housewives and self-employed women. There was a significant relationship between the mean of these scores and mothers' jobs so that the mean scores were higher in employed women than others. Conclusions: The results of our study showed that the average score of knowledge, attitude, and practice of pregnant women in Birjand regarding oral hygiene during pregnancy is not satisfactory and appropriate.

THERMAL AND ELECTROCHEMICAL PROPERTIES OF SOLID BIOPOLYMER ELECTROLYTES FROM STARCH OF DIFFERENT BOTANICAL ORIGIN

Background: Solid biopolymer electrolytes are a type of material with high technological potential used in the development of solar cells, batteries, fuel cells, among others, due to their biodegradable nature and low environmental impact. Aim: This study aimed to evaluate the effect of the botanical origin of the starch used to prepare solid biopolymeric electrolyte films on its electrochemical and thermal properties and to establish the variations in thermal decomposition temperatures and redox potentials depending on the botanical origin of the starch used. Methods: Films of solid biopolymer electrolyte were made by thermochemical synthesis processes using corn starch, cassava starch, potato starch, glycerol, polyethylene glycol, and glutaraldehyde as plasticizers and lithium perchlorate salt. The synthesis solutions were taken to an oven at 70 °C for 48 hours. The films were characterized electrochemically by cyclic voltammetry using a dry electrochemical cell and thermally by differential scanning calorimetry and thermogravimetric analysis. Results and Discussion: The results showed that the electrochemical behavior of the films was similar in terms of registered redox processes. However, the potential values of the oxidation and reduction were different, as are the stability and intensity of the processes. On the other hand, the thermal analysis allowed establishing two decomposition processes in each of the films studied; the first process was due to dehydration and depolymerization phenomena in the films. The temperatures recorded were 59.0 °C, 58.9 °C, and 89.9 °C for potato starch, cassava starch, and corn starch films. The second process evidenced the thermal decomposition at different temperatures, 267.7 °C in potato starch films, 280.6 °C in corn starch films, and 287.1 °C in cassava starch films. Conclusions: It could be concluded that the botanical origin of the starch used in the synthesis of solid biopolymer electrolyte films affects its behavior and electrochemical and thermal stability.

SEASONAL VARIATION OF PHENOLS AND FLAVONOIDS IN NON-GALLED AND GALLED LEAVES OF CARYOCAR BRASILIENSE (CARYOCARACEAE)

Introduction: Galling insects manipulate the development of their host plants. Galls are rich in secondary metabolites, such as phenolic compounds and terpenes. Caryocar brasiliense acts as a host of galling insects. Few studies report the impacts of this plant-insect interaction on the species' morphology, physiology, and secondary metabolism. Objective: The purpose of this study was to verify if there is a correlation between the levels of total phenols and flavonoids in C. brasiliense leaf extracts and environmental variables, such as temperature and precipitation, throughout the year, and to evaluate how galling insects can interfere in this seasonality. Methods: Ethanol extracts from leaves were obtained by soxhlet extraction. The main classes of secondary metabolites were detected by phytochemical prospecting. The levels of total phenols and flavonoids were quantified by the Folin-Dennis tests and complexation reaction with aluminum chloride, respectively. Pearson 's correlation coefficient shows that the levels of phenols and flavonoids were correlated with the average monthly maximum temperatures and precipitation accumulation, respectively, recorded in Gurupi - Tocantins. Results and Discussion: Phytochemical prospecting indicated flavonoids, saponins, tannins, triterpenes, steroids, and alkaloids in both extracts. In C. brasiliense, the samples of healthy leaves suffered a greater variation in the levels of phenols (68.39±2.3 to 279.34±3.1 mg GAE g-1 extract) and flavonoids (164.06± 3.0 at 269.03±3.6 mg QE g-1 extract) compared to leaf samples with galls. A strong positive correlation was found between the contents of total phenols and maximum temperatures and a strong negative correlation with precipitation through Pearson's correlation. Conclusions: The variations observed in the levels of phenols and flavonoids in the extracts of C. brasiliense seem to be related to abiotic factors and the herbivory promoted by the galling insect.