rss_2.0Chemistry FeedSciendo RSS Feed for Chemistry Feed review of the toxicity of triazole fungicides approved to be used in European Union to the soil and aqueous environment<abstract> <title style='display:none'>Abstract</title> <p>This review provides the summarized current knowledge on the degradation and effects on the non-target organisms from soil and aquatic environment of the triazole fungicides approved to be used in most of the European Union also taking into account stereospecific differences. Synthetized data reveal that triazole fungicides are usually persistent in aqueous environment and soil, and manifest moderately acute and chronic toxicity against the organisms living in these environments. Furthermore, the enantiomers of triazole fungicides proved to have distinct distribution and effects on these environments. These data are important for assuring a sustainable agriculture by production and use of single-stereoisomer and/or encouraging a management of agricultural crops with minimum effects on environment.</p> </abstract>ARTICLE2022-07-28T00:00:00.000+00:00Temperature dependence studies and microscopic protonation constants of L-alanine and β-alanine in acetonitrile – water mixtures<abstract> <title style='display:none'>Abstract</title> <p>L-alanine and β-alanine are important biological molecules and have zwitterion structure. In this study, L- alanine and β-alanine’s microscopic protonation constants and thermodynamic parameters (enthalpy, entropy, and free energy changes) for the proton–ligand systems of L-alanine methyl ester, β-alanine and β-alanine methyl ester have been determined at 5; 20; 35 °C, in ACN-water (25% ACN and 50% ACN (v/v)) mixtures at constant ionic strength of 0.1000 mol L<sup>–1</sup> NaClO<sub>4</sub> by potentiometric method. The results shown that, L-alanine and β-alanine’s microscopic protonation constants generally tend to decrease with temperature rise and their protonation reactions in ACN-water mixtures generally favor enthalpy-driven.</p> </abstract>ARTICLE2022-07-28T00:00:00.000+00:00Comparison of ultrasound and maceration methods on antioxidant and antimicrobial efficacy of phenolic compounds extracted from L. of Algeria<abstract> <title style='display:none'>Abstract</title> <p>An investigation was carried out to extract the polyphenols from <italic>Cynodon dactylon</italic> L. by ultrasound-assisted extraction (UAE) and maceration assisted extraction (MAE), and to assess the antioxidant and antimicrobial activities, as well as the evaluation of the cytotoxic effect of ethanolic extracts. The yields of crude extracts were 9.40 % for the MAE extract and 12.52 % for the UAE extract. The results showed that the extract obtained by MAE contains a high level of polyphenols and flavonoids estimated by 42.14 ± 0.75 mg EAG/gE and 23.57 ± 0.78 mg EQ/gE. In contrast, the content of condensed tannins in the extract of UAE (19.34 ± 0.48 mg EC/gE) is higher. The evaluation of the antioxidant activity revealed a considerable antioxidant response, the MAE extract represents the most active extract, with an IC<sub>50</sub> =7.52 ± 0.037 mg/mL for the DPPH test, and 15.83 ± 0.37 mg EAA/gE for the FRAP test. The results of antimicrobial activity showed that all the strains targeted have high susceptibility to the two ethanolic extracts of <italic>Cynodon dactylon</italic> L. The evaluation of cytotoxicity against RBCs was carried, the results shown the non-toxic effect of <italic>C. dactylon</italic> extracts and hence support its ethnomedicinal application.</p> </abstract>ARTICLE2022-07-28T00:00:00.000+00:00Dynamics of CTAB micelle mediated reaction of fuchsin degradation in alkaline medium<abstract> <title style='display:none'>Abstract</title> <p>Cetyltrimethylammonium bromide (CTAB) micelles catalyzed the degradation of fuchsin in the entire surfactant concentration range investigated. The pseudo first order rate constants increased with CTAB concentrations. However, there was a decrease in the rate constant at higher concentrations of CTAB. Increase in the rate constant was attributed to the incorporation of fuchsin and hydroxide ion in the stern layer of the CTAB micelles. The kinetics involved the removal of the π-conjugation in fuchsin due to its attack by hydroxide ion on the central C atom of the planar ring which led to the formation of carbinol. The reaction showed first order each to fuchsin and OH<sup>-</sup>. Menger-Portnoy and Piszkiewicz cooperative models were used to explain the micellar and kinetic effects.</p> </abstract>ARTICLE2022-07-28T00:00:00.000+00:00Study of corrosion inhibition of aluminum in acidic media by pineapple crown extract<abstract> <title style='display:none'>Abstract</title> <p>The efficiency of pineapple crown extract as corrosion inhibitor of aluminum in 1M H<sub>2</sub>SO<sub>4</sub> acidic medium was tested using weight loss and potentiodynamic methods, at varied inhibitor concentration. Through the data from the weight loss method there was calculated the corrosion rate and pineapple crown extract’s inhibition on aluminum corrosion in acidic medium, at varied inhibitor concentration. Also, with the data obtained from the potentiodynamic method, the polarization curves and Tafel tangents were constructed, while calculating the corrosion rate and inhibition efficiency of pineapple crown extract. Experimental measurements showed that pineapple crown extract acts as a mixed inhibitor and the inhibition efficiency increases with increasing the extract concentration.</p> </abstract>ARTICLE2022-07-28T00:00:00.000+00:00Editorial Note: Veleka Beach - the place where the mountain touches the sea model of the “Chemistry training process” system when applying semiotic approaches<abstract> <title style='display:none'>Abstract</title> <p>The present development uses the modeling method described in the literature and proposed a new didactic, functional model of the “chemistry training” system in the application of semiotic approaches: semantic, pragmatic, and syntactic. The main objective of creating such a model is to demonstrate the specific activities of the subjects “teacher” and “pupil” when familiarizing themselves with chemical symbols and their study by students. The added new components in the model “Technology of chemistry training”, “Semiotic information” and the clarified links between them, lead to a complete change in the way the described system works. The developed didactic model makes it easy to guess the relationship between a new learning situation and a result, that is, to predict an unknown process or phenomenon. This model makes it possible to formulate a reasoned hypothesis of the study.</p> </abstract>ARTICLE2022-07-28T00:00:00.000+00:00New data on the presence of the Blotched snake ( Pallas, 1814) in the region of Shumen town (Bulgaria), with emphasis on the negative human attitude toward the species<abstract> <title style='display:none'>Abstract</title> <p>In the present study, we report on new localities in Northeastern Bulgaria, where Elaphe sauromates (Pallas, 1814) was recently detected. We registered five Blotched snakes in the region of Shumen town in the period 2018 - 2022. All of the snakes were adults, three were killed by tools impacts and two of them were road kills. To date, the Blotched snake was registered extremely rare and in rather long intervals (of several decades) in the region of Shumen. Our findings indicate that the species currently inhabits the suburban and urban territories near the villages of Ivanski, Radko Dimitrievo and Konyovets. Two of the locations are new for the 10 km grid-system used for standard monitoring of the biodiversity in Bulgaria.</p> </abstract>ARTICLE2022-07-28T00:00:00.000+00:00Morphotectonic affilation of the Lilyak Plateau<abstract> <title style='display:none'>Abstract</title> <p>The morphostructural features of the Lilyak Plateau and it’s spatial and morphotectonic relationships with the adjacent parts of the Eastern Pre-Balkan Mountains are examined in the light of modern mobilist ideas. The Lilyak Plateau landform is part of the South Moesian morphostructural zone. This morphostructure borders distinctly to the south with the northern border of the corresponding part of the Fore Hemus morphostructural zone. There are significant morphostructural and morphotectonic differences between these two regional morphostructural units.</p> </abstract>ARTICLE2022-07-28T00:00:00.000+00:00Experimental study on the impact of semiotic approaches on students’ knowledge of chemical symbolism in seventh and eighth grade<abstract> <title style='display:none'>Abstract</title> <p>Experimental work in its milestones is carried out according to the following algorithm:</p> <p>1. Development of a methodological system, including additional training content in Chemistry and Environmental Protection for the seventh and eighth grades /purposefully selected urological fragments, exercises and summary lessons/, in which the subject of study is chemical symbolism, with the application of semiotic approaches - semantic, pragmatic and syntactic.</p> <p>2. Conducting a pedagogical experiment to establish the effectiveness of the developed methodological system.</p> <p>3. Analysis of the results of the pedagogical experiment.</p> <p>The pedagogical experiment is included in the work as the main method of researching the influence of semiotic approaches on the knowledge and skills of students for the proper use of chemical symbols. By conducting a pedagogical experiment, it has been shown that the use of the three semiotic approaches in Chemistry and environmental training facilitates and improves the understanding of the complex meaning of chemical symbols by students. The analysis of the results of the written control works in the seventh and eighth grades shows the existence of significant qualitative differences in students’ knowledge of how to identify chemical objects and the degree of skills formed to reveal the information embedded in chemical symbols.</p> </abstract>ARTICLE2022-07-28T00:00:00.000+00:00Global Ecological Problems of Modern Society<abstract> <title style='display:none'>Abstract</title> <p>At the modern stage of society’s development, ecology is seen as a complex, interdisciplinary science of the relationships of organisms, society and the environment. Ecology is a science that studies the regularities of the life of organisms in their natural living environment and taking into account the changes made in this environment as a result of human activity. In recent years, the mass media has been constantly talking and writing about ecology, environmental problems related to anthropogenic activity. The person with his activity is heavily polluted and continues to negatively affect the environment at increasing rates. This reckless behavior of humans and the whole of society threatens planet Earth with imminent doom, no less than the use of nuclear weapons. Only from the positions of modern science ecology is it possible to develop issues related to the prudent use of the natural resources of the biosphere and the fight against changes brought about in nature by human activity in the age of the scientific and technical revolution. For this reason, it is necessary to seek information and a solution to the key current problems: What are the main pollutants of the atmosphere, hydrosphere and lithosphere? What is the origin of these substances? How does their impact affect life on Earth? What approaches and methods are needed to prevent environmental pollution?</p> </abstract>ARTICLE2022-07-28T00:00:00.000+00:00Involvement of young people in the citizen science of invasive alien species in Bulgaria<abstract> <title style='display:none'>Abstract</title> <p>Citizen science plays an important role in the early detection of invasive alien species (IAS). The involvement of young people in initiatives related to citizen science in Bulgaria could contribute to better monitoring of IAS because of mobility and digital skills of those people. Based on a questionnaire survey, key aspects of involvement of young people in citizen science initiatives were analysed. Two groups of respondents, including professionals (with an educational background in biology or with professional activities related to the bioresources) and non-professionals (not connected with bioresources) were asked to make judgments about their own level of knowledge about: (1) IAS issues, (2) the level of awareness of citizen science; (3) the motivation and preferable ways to participate in citizen science; and (4) the most appropriate approaches for IAS awareness raising. A total of 337 young people in the age range of 15-30 years were questioned during the period 2019-2021. The results show that there is no significant difference between the responses of the two groups of respondents to the questionnaire - professionals and non-professionals. In both groups, less than 50% of respondents are aware of issues related to IAS. Less than 40% of respondents indicated the correct definition of citizen science. The leading motivation factor to participate in citizen science initiatives is “caring for nature” followed by “to contribute to nature conservation” and “to learn more about nature”. Most of the respondents are interested in additional information related to IAS and prefer online sources for information.</p> </abstract>ARTICLE2022-07-28T00:00:00.000+00:00The Effect of Nitrogen on the Structural and Electronic Properties of Graphene Sheet using Density Functional Theory<abstract> <title style='display:none'>Abstract</title> <p>The present research focuses on a theoretical study of structural and electronic properties of pure graphene sheet and then adding different number of N<sub>2</sub> atoms. The calculations are carried out using the density functional theory (DFT) with hybrid functional B3LYP/6-31G level to investigate the proposed structures. Gauss View 5.0.8 program is used to design the structures of pure and doped graphene sheets. These structures are relaxed by employing the PM6 semi-empirical method with the hybrid functional B3LYPDFT at Gaussian 09 package. The results of the structural properties of the studied graphene sheets showed that good relaxation of the structures, the constant bonds values in the pure graphene sheets in the same ranges of the carbon rings structures. We calculate the total energy, High Occupied Molecular Orbital (HOMO) and Low Unoccupied Molecular Orbital (LUMO) energies and forbidden energy gap. The result of the total energy of that doping graphene sheets is result of the binding energy of each structure and indicates that these structures have relaxation, and the effect of adding N<sub>2</sub> atoms in pure graphene sheet on the total energy of the molecule is effective. All doping graphene sheets have small forbidden energy gap, but it vibrates depending on the length and number of each sheet and the position of N<sub>2</sub> atoms in the sheets.</p> </abstract>ARTICLE2022-07-28T00:00:00.000+00:00Antioxidant potentials and anti-inflammatory properties of methanol extracts of ripe and unripe peels of (L.) Merr.<abstract> <title style='display:none'>Abstract</title> <p>Studies suggest that extracts from plant materials could play protective roles against various disorders associated with the interplay between oxidative response and inflammatory disorders. The aim of this study was to investigate the potential antioxidant and anti-inflammatory properties, and phytochemical analyses of methanol extract of ripe and unripe peels of <italic>Ananas comosus</italic> (L.) Merr. The antioxidant properties were investigated through the analyses of ferric ion reducing antioxidant capacities, ascorbic acid equivalent antioxidant capacities, and nitric oxide scavenging capacities of the extracts. The anti-inflammatory potentials of the extracts were assessed through albumin denaturation inhibition and proteinase inhibition assays. Further investigation was carried out on the phytochemical composition of the extracts. There was no significant difference in the antioxidant potentials of the extracts assessed through the reduction of ferric ion. However, the ascorbic acid equivalent capacities and nitric oxide scavenging potential revealed that the antioxidant potentials of the extract of the unripe peel of <italic>A. comosus</italic> were significantly higher (p &lt; 0.05) than the antioxidant potentials of the extract of ripe peel. Albumin denaturation inhibitory potential was significantly higher (p &lt; 0.05), but there was no significant difference in the protease inhibitory potentials of both extracts. The estimated amounts of total flavonoids present in the extract of ripe peel of <italic>A. comosus</italic> were significantly higher (p &lt; 0.05) than the estimates in the extract of unripe peels. This study gave a comprehensive insight into the antioxidant properties, anti-inflammatory properties and phytochemical compositions of the methanol extracts of the peels of ripe and unripe <italic>A. comosus</italic> which could be exploited as an alternative and complementary medicine in the treatment of different ailments associated with inflammatory disorders.</p> </abstract>ARTICLE2022-07-13T00:00:00.000+00:00A Cross-Sectional Study of Sialic Acids Level in Breast Cancer Patients Attending Ahmadu Bello University Teaching Hospital Zaria, North-Western Nigeria: Preliminary investigations and Implications on Disease Subtypes, Grade and Chemotherapy Courses<abstract> <title style='display:none'>Abstract</title> <p>Due to the challenges associated with breast cancer prognosis, this study examined sialic acid levels based on subtypes, grades and therapeutic courses among breast cancer patients presenting at Ahmadu Bello University Teaching Hospital (ABUTH) in North-Western Nigeria between June 2019 and December 2020. This was a cross-sectional study. Sociodemographic characteristics, total sialic acid (TSA), free sialic acid (FSA), bound sialic acid (BSA) and haematological parameters were determined. The mean age of the respondents was 47.46 ± 10.71 years, and the modal age range was 41-50 years. About 40% of the patients had triple-negative breast cancer subtype, and 83.1% had invasive carcinoma. There was an association between breast cancer grade and body mass index (χ<sup>2</sup>= 26.306, P= 0.001). The TSA, FSA and BSA concentrations were significantly (P&lt;0.05) higher in luminal A and triple-negative breast cancer patients when compared to apparently healthy controls and were highest in stage IV patients. The TSA correlated with the third and sixth chemotherapy courses. Significant (P&lt;0.05) decrease was observed in PCV and Hb among the breast cancer patients irrespective of subtype compared to healthy control. The results suggest that TSA, FSA and BSA were higher in breast cancer patients, necessitating further research on their possible prognostic implications.</p> </abstract>ARTICLE2022-07-11T00:00:00.000+00:00Subsurface Investigation for Road Construction Using Electrical Resistivity Method along Oloko road, Apatapiti, Akure, Ondo State, Nigeria<abstract> <title style='display:none'>Abstract</title> <p>Evaluation of the shallow geologic materials in terms of types, nature, and bedrock structure as possible causes of pavement failure was carried out along Oloko road Apatatpiti, Akure, Nigeria, using Schlumberger vertical electrical sounding and 2-D imaging dipole-dipole techniques. Three lithological layers, namely thin top soil, weathered layer and weathered basement, were revealed by the 2-D resistivity structure. Vertical electrical soundings were made at locations with a very low resistive medium typical of linear features such as fractures/faults at some distances on the 2-D resistivity structure. Four geologic layers, namely the top soil, clay/sandy clay, fractured basement, weathered/fresh basement, were identified by the geoelectric section. The geoelectric section and the 2-D resistivity structure revealed that the upper 0-6m, which constitutes the subgrade, has a low resistivity (36 Ωm to 108 Ωm) characterised to be clayey materials and suggestive of weak zones that might impair the stability of the road. A relatively shallow depth, ranging from 3.7 m to 4.29 m, was the depth to the water table of the four wells close to the road. Therefore, the possible causes of pavement failure are the thick and low resistive layer, the near-surface linear features suspected to be fractures/faults, and the water table’s shallow depth.</p> </abstract>ARTICLE2022-07-11T00:00:00.000+00:00Effects of anthropogenic activities on nutrient parameters in the North Eastern Mediterranean Sea (Bay of Sığacık/Aegean Sea)<abstract> <title style='display:none'>Abstract</title> <p>This study aims to examine the physicochemical parameters of seawater (temperature, pH, salinity, dissolved oxygen, suspended particulate matter, ammonium-nitrogen, nitrite-nitrogen, nitrate-nitrogen, and phosphate-phosphorus, burnable organic matter in the sediment), and possible effects of pollution in Sığacık Bay where different anthropogenic activities are carried out. Samples of surface seawater (0 m), bottom seawater (2 m), and sediment were collected monthly from four sampling sites between September 2013 and September 2014. Annual mean nutrient values were determined as 1.6 ± 0.14 μ<sub>4</sub><sup>+</sup>-N l<sup>-1</sup>, 0.1 ± 0.01 μ<sub>2</sub><sup>-</sup>-N l<sup>-1</sup>, 0.8 ± 0.08 μ<sub>3</sub><sup>-</sup>-N l<sup>-1</sup>, 0.7 ± 0.08 μ<sub>4</sub><sup>3-</sup>-P l<sup>-1</sup>, SPM 21.4 ± 0.33 mg l<sup>-1</sup>. The BOM content in the sediment was 5.6 ± 0.39%. As a result of the study, it was determined that Sığacık Bay was polluted by anthropogenic point and non-point source pollution. According to the water quality criteria, the bay was found to be in the group of polluted seawater in terms of phosphate phosphorus.</p> </abstract>ARTICLE2022-07-07T00:00:00.000+00:00Intercellular and extracellular amino acids of different bloom species in the Mediterranean Sea<abstract> <title style='display:none'>Abstract</title> <p>The presented laboratory experiment was designed to characterize the quantity and compositional variation of algal extracellular amino acids (AAs) that may represent an alternative nutrient source in a natural environment. To resemble algal bloom scenarios, analyses were conducted in mono- and/or co-cultures of the bloom-forming species <italic>Skeletonema costatum, Scrippsiella trochoidea, Ulva fasciata</italic>, and <italic>Corallina officinalis</italic> during their active growth phase. The study revealed that <italic>S. costatum</italic> exhibited higher production of the dominant AAs than <italic>S. trochoidea</italic>. Alanine, lysine, and threonine acids are the dominant amino acids in <italic>S. costatum</italic> and <italic>S. trochoidea</italic> filtrates, which may play a role in mucus formation during mucosal phytoplankton blooms with negative ecological effects. On the other hand, aspartic, glutamine, alanine, and leucine acids are the dominant amino acids in macroalgae. In co-culture experiments, <italic>U. fasciata</italic> shows strong and rapid allelopathic activity against these two potentially harmful species. The AA production offers an advantage to species with the capacity to absorb them to form blooms. Thus, anthropogenic inorganic nutrient inputs may be less important for the development of algal blooms in coastal waters. A major difference that distinguishes this work from others is the use of specific multi-taxa cultures of phytoplankton and macroalgae. The study represents a new research effort in Alexandria waters.</p> </abstract>ARTICLE2022-07-07T00:00:00.000+00:00Skeletal deformities in (Teleostei: Cyprinidae) collected from the Dalaman River in southwestern Turkey<abstract> <title style='display:none'>Abstract</title> <p>In this study, skeletal anomalies such as vertebral centra deformation, lordosis (ventral curvature), and consecutive repetition of lordosis and kyphosis were examined in specimens of <italic>Barbus xanthos</italic> (Güçlü, Kalaycı, Küçük &amp; Turan, 2020) collected from the Dalaman River, southwestern Turkey. Abnormalities of the vertebral column were observed in both thoracic and caudal vertebrae. Cases of lordosis and consecutive repetition of lordosis and kyphosis showed varying degrees of severity. Specimens with consecutive repetition of lordosis showed the most acute deformities among the cases studied, as they revealed complicated incidences of skeletal anomalies. None of the cases were fatal as they occurred in adult individuals. This study discusses the possible causes of such deformities and the usefulness of this type of study in environmental monitoring.</p> </abstract>ARTICLE2022-07-07T00:00:00.000+00:00First record of the common sun star (L., 1767) in the Baltic Sea in over 100 years<abstract> <title style='display:none'>Abstract</title> <p>The rare in the German North and Baltic Sea waters and strictly protected sea star <italic>Crossaster papposus</italic> was found in 2019 and 2021 during monitoring activities in a marine protected area. This unique observation was achieved by using towed camera platform imagery along a transect in the Fehmarn Belt, which allows monitoring of a much larger area of the seafloor compared to traditional invasive grab and dredge sampling. The last time <italic>C. papposus</italic> was documented in this area was in 1871, indicating the rarity of this species in the Baltic Sea. Possible explanations for such rare records of the occurrence of this presumably native species in the study region are briefly discussed, including uncommon survival due to salinity conditions caused by prior inflows of saline water from the North Sea.</p> </abstract>ARTICLE2022-07-07T00:00:00.000+00:00en-us-1