Disposable potentiometric sensory system for skin antioxidant activity evaluation

The skin is a natural barrier between the external and internal environment. Its protective functions and the relationship of its state with the state of health of the organism as a whole are very important. It is known that oxidant stress (OS) is a common indicator of health status. This paper describes a new sensory system for monitoring OS of the skin using antioxidant activity (AOA) as its criteria. The contact hybrid potentiometric method (CHPM) and new electrochemical measuring scheme were used. A new sensory system, including disposable modified screen-printed carbon and silver electrodes covered by membrane impregnated by mediator, was developed. Its informative ability was demonstrated in the evaluation of the impact of fasting, consumption of food and food enriched by vitamins (antioxidants) on skin AOA. This device consisting of a sensory system and potentiometric analyzer can be used in on-site and in situ formats. © 2019 by the authors. Licensee MDPI, Basel, Switzerland

Electrochemical sensor based on a carbon veil modified by phytosynthesized gold nanoparticles for determination of ascorbic acid

An original voltammetric sensor (Au-gr/CVE) based on a carbon veil (CV) and phytosynthesized gold nanoparticles (Au-gr) was developed for ascorbic acid (AA) determination. Extract from strawberry leaves was used as source of antioxidants (reducers) for Au-gr phytosynthesis. The sensor was characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy and electrochemical methods. Optimal parameters of AA determination were chosen. The sensor exhibits a linear response to AA in a wide concentration range (1 µM–5.75 mM) and a limit of detection of 0.05 µM. The developed sensor demonstrated a high intra-day repeatability of 1 µM AA response (RSD = 1.4%) and its stability during six weeks, selectivity of AA determination toward glucose, sucrose, fructose, citric, tartaric and malic acids. The proposed sensor based on Au-gr provides a higher sensitivity and a lower limit of AA detection in comparison with the sensor based on gold nanoparticles synthesized by the Turkevich method. The sensor was successfully applied for the determination of AA content in fruit juices without samples preparation. The recovery of 99%–111% and RSD no more than 6.8% confirm the good reproducibility of the juice analysis results. A good agreement with the potentiometric titration data was obtained. A correlation (r = 0.9867) between the results of AA determination obtained on the developed sensor and integral antioxidant activity of fruit juices was observed. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.Russian Foundation for Basic Research, RFBR: 17-03-00679This research was partially funded by RFBR grant number 17-03-00679

Air Pollution Problems

В статье рассматриваются проблемы антропогенного загрязнения воздуха. Приводятся результаты исследований состояния атмосферы в промышленно развитых странах и её влияния на здоровье человека.The article deals with the issues of air pollution in a large industrial city. The results of studies of the state of air pollution and the impact of these problems on human health are presented

The effect of the antioxidant activity of plant extracts on the properties of gold nanoparticles

Synthesis of gold nanoparticles (phyto-AuNPs) with the use of leaf extracts (phytosynthesis) is based on the concept of Green Chemistry. The present study is conducted to discuss how antioxidant activity (AOA) of extracts from plant leaves impacts on the kinetics of phytosynthesis, the size of the formed nanoparticles, and the stability of their nanosuspensions. Results show that the formation rate of phyto-AuNPs suspensions accelerate due to the increase in the AOA of the extracts. Accompanying the use of transmission electron microscopy (TEM), UV-Vis-spectrophotometry and dynamic light scattering (DLS), it also has been found that higher AOA of the extracts leads to a decrease in the size of phyto-AuNPs, an increase in the fraction of small (d ≤ 5 nm), and a decrease in the fraction of large (d ≥ 31–50 nm) phyto-AuNPs, as well as an increase in the zeta potential in absolute value. Phyto-AuNPs suspensions synthesized with the use of extracts are more resistant to destabilizing electrolytes and ultrasound, as compared to suspensions synthesized using sodium citrate. Thus, the AOA of the extract is an important parameter for controlling phytosynthesis and predicting the properties of phyto-AuNPs. The proposed approach can be applied to the targeted selection of plant extract that will be used for synthesizing nanoparticles with desired properties. © 2019 by the authors. Licensee MDPI, Basel, Switzerland.Russian Foundation for Basic Research, RFBR: 17-03-00679_АFunding: This research was funded by the Russian Foundation for Basic Research, grant number 17-03-00679_А

Carbon Paper Modified with Functionalized Poly(diallyldimethylammonium chloride) Graphene and Gold Phytonanoparticles as a Promising Sensing Material: Characterization and Electroanalysis of Ponceau 4R in Food Samples

This paper presents a novel eco-friendly sensing material based on carbon paper (CP) volumetrically modified with a composite nanomodifier that includes functionalized poly(diallyldimethylammonium chloride) graphene (PDDA-G) and phytosynthesized gold nanoparticles (phyto-AuNPs). The functionalization of graphene was justified by Fourier-transform infrared spectroscopy. The phyto-AuNPs (d = 6 nm) were prepared by “green” synthesis with the use of strawberry leaf extract. The sensing material was characterized using scanning electron microscopy, electrochemical impedance spectroscopy, and voltammetry. The research results indicated a more than double increase in the electroactive surface area; a decrease in the resistance of electron transfer on nanocomposite-modified CP, compared to bare CP. The phyto-AuNPs/PDDA-G/CP was used for the electrosensing of the synthetic dye Ponceau 4R. The oxidation signal of colorant enhanced 4-fold on phyto-AuNPs/PDDA-G/CP in comparison to CP. The effect of the quantity of nanomodifier, solution pH, potential scan rate, accumulation parameters, and differential pulse parameters on the peak current of Ponceau 4R was studied. Under optimal conditions, excellent sensory characteristics were established: LOD 0.6 nM and LR 0.001–2 μM for Ponceau 4R. High selectivity and sensitivity enable the use of the sensor for analyzing the content of Ponceau 4R in food products (soft drinks, candies, and popsicles) without additional sample preparation. © 2022 by the authors

Interdisciplinary project-based learning: technology for improving student cognition

The article studies a way of enhancing student cognition by using interdisciplinary project-based learning (IPBL) in a higher education institution. IPBL is a creative pedagogic approach allowing students of one area of specialisation to develop projects for students with different academic profiles. The application of this approach in the Ural State University of Economics resulted in a computer-assisted learning system (CALS) designed by IT students. The CALS was used in an analytical chemistry course with students majoring in Commodities Management and Expertise (‘expert’ students). To test how effective the technology was, the control and experimental groups were formed. In the control group, learning was done with traditional methods. In the experimental group, it was reinforced by IPBL. A statistical analysis of the results, with an application of Pearson χ 2 test, showed that the cognitive levels in both IT and ‘expert’ experimental groups improved as compared with the control groups. The findings demonstrated that IPBL can significantly enhance learning. It can be implemented in any institution of higher or secondary education that promotes learning, including the CALS development and its use for solving problems in different subject areas

FORMATION OF PROFESSIONAL COMPETENCE IN THE COURSE OF PHYSICO-CHEMICAL LABORATORY WORKSHOP IN ECONOMIC UNIVERSITY

Abstract. Aim. The work is devoted to the study of the conditions of formation in the educational process on the subject «Analytical Chemistry and Physical Methods of Analysis», the most important competences necessary to the modern specialist in the food sector (production and examination of food quality technology) for food quality control and food safety of the population.Methods. The basis of the organization of educational process on the considered discipline laid professionally-oriented approach. Innovative instruments for use in laboratory practice are created based on the model of interdisciplinary design, providing for the development of electronic resources by students. Evaluation of formation of competences was carried out using a three-tier model based on the well-known in pedagogics measurement systems of achievements of pupils: B. Blum’s taxonomy, V. P. Bespalko’s classification, etc. Indirect quality standard of efficiency of educational process was based on the surveys of students, teachers of specialized (professional) departments, and on comparison of student portfolios.Results and scientific novelty. The complex of competences which development is promoted by a laboratory workshop on analytical chemistry and physicalchemical methods of the analysis is emphasized. The connections of these competences with content of the laboratory practical work providing the application of electronic resources optimizing labor-consuming routine transactions of an experiment and facilitating handling of its results are determined. The approbation of laboratory works and assessment of their efficiency in forming of various all-professional and professional competences is carried out. Practical significance. Described experience of a laboratory practical work, developing innovative resources on the basis of student partnership formation and evaluation elements of the professional competencies can be used by various educational institutions in the system HE, HVE and SVE.Цель работы: статья посвящена исследованию условий формирования в учебном процессе вуза важнейших компетенций, необходимых современному специалисту в продовольственной сфере для контроля качества продуктов питания и обеспечения продовольственной безопасности населения. Методика. Организация рассматриваемого учебного процесса осуществлялась согласно профессионально-ориентированному подходу. Инновационный инструментарий лабораторного практикума создавался на основе междисциплинарного проектирования. Оценка сформированных в ходе практикума элементов компетенций проводилась по адаптированной к специфике контингента учащихся трехуровневой модели, базирующейся на известных в педагогике системах измерений достижений учащихся: таксономии Б. Блума, классификации В. П. Беспалько и др. Косвенная качественная оценка эффективности учебного процесса базировалась на опросах студентов, преподавателей специализированных (профессиональных) кафедр и на сравнительном анализе портфолио студентов. Результаты и научная новизна. Выделен комплекс компетенций, развитию которых способствует лабораторный практикум по аналитической химии и физико-химическим методам анализа. Определены связи этих компетенций с содержанием лабораторного практикума, предусматривающего использование электронных ресурсов, оптимизирующих трудоемкие рутинные операции эксперимента и облегчающих обработку его результатов. Проведена апробация лабораторных работ и оценка их эффективности в формировании различных общепрофессиональных и профессиональных компетенций. Практическая значимость. Описанный опыт организации лабораторного практикума и разработки инновационных ресурсов учебного процесса могут быть использованы различными образовательными учреждениями системы высшего и среднего специального профессионального образования.Работа выполнена при поддержке Минобрнауки РФ (проект № 2940 «Разработка электронных образовательных ресурсов для изучения естественнонаучных дисциплин в экономическом вузе»