The subgroup identification problem for finitely presented groups

We introduce the subgroup identification problem, and show that there is a finitely presented group G for which it is unsolvable, and that it is uniformly solvable in the class of finitely presented locally Hopfian groups. This is done as an investigation into the difference between strong and weak effective coherence for finitely presented groups.Comment: 11 pages. This is the version submitted for publicatio

Non-Enzymatic Co3O4 Nanostructure-Based Electrochemical Sensor for H2O2 Detection

This article describes the synthesis of nanostructured cobalt oxide on iron wires and its application for the detection of hydrogen peroxide as working electrode for non-enzymatic electrochemical sensor. Cobalt oxide was obtained by the hydrothermal synthesis method using chloride and acetate anions. The resulting nanostructured coating obtained from the chloride precursor is a uniform homogeneous porous network of long nanofibers assembled into regular honeyсomb-like formations. In the case of an acetate precursor, instead of nanofibers, petal-like nanostructures assembled into honeycomb agglomerates are observed. The structure, surface, and composition of the obtained samples were studied using field-emission scanning electron microscopy along with energy-dispersive spectroscopy and X-ray diffractometry. The resultant nanostructured specimens were utilized to detect H2O2 electrochemically through cyclic voltammetry, differential pulse voltammetry, and i-t measurements. A comparative research has demonstrated that the nanostructures produced from the chloride precursor exhibit greater sensitivity to H2O2 and have a more appropriate morphology for designing a nanostructured sensor. A substantial linear correlation between the peak current and H2O2 concentration within the 20 to 1300 μM range was established. The Co3O4 electrode obtained exhibits a sensitivity of 505.11 μA·mM−1, and the electroactive surface area is calculated to be 4.684 cm2. Assuming a signal-to-noise ratio of 3, the calculated limit of detection is 1.05 μM. According to the interference study, the prevalent interfering agents, such as ascorbic acid, uric acid, NaCl, and glucose, do not influence the electrochemical reaction. The obtained results confirm that this sensor is suitable for working with complex analytes.The actual sample assessment demonstrated a recovery rate exceeding 95 %. --//-- This is an open access article Mizers, V., Gerbreders, V., Krasovska, M., Sledevskis, E., Mihailova, I., Ogurcovs, A., Bulanovs, A. and Gerbreders, A.. "Non-Enzymatic Co3O4 Nanostructure-Based Electrochemical Sensor for H2O2 Detection" Latvian Journal of Physics and Technical Sciences, vol.60, no.6, 2023, pp.63-84. https://doi.org/10.2478/lpts-2023-0037 published under the CC BY-NC-ND 4.0 licence.The research has been supported by ESF Project No. 8.2.2.0/20/I/003 “Strengthening of Professional Competence of Daugavpils University Academic Personnel of Strategic Specialization Branches 3rd Call”. The Institute of Solid State Physics, University of Latvia at the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART2

Morphology Influence on Wettability and Wetting Dynamics of ZnO Nanostructure Arrays

This study has been supported by internal research grant No. 14-95/2021/10 of Daugavpils University “Development of the Nanostructured Metal Oxide Coatings and Their Application in Optical Sensing for Heavy Metal Detection”.Changes in nanostructure morphology and size may result in very different surface wettability. In this research, the impact of different morphological parameters on the wetting dynamics of ZnO nanostructured layers is studied. Six different morphologies are chosen to determine the specific wetting processes of ZnO nanostructures: nanoneedles, small diameter rods, large diameter rods, nanotubes, nanoplates, and plain thin films. Wetting dynamics is investigated using conventional sessile drop technique and a novel approach based on electrochemical impedance spectroscopy. The results show that the surface of nanostructured ZnO thin films exhibits both hydrophilic and hydrophobic wetting behaviour, depending on nanostructure form, size, and orientation. ZnO nanostructure arrays are a promising platform for electrochemical and optical sensing in aqueous solutions. The full and effective use of the sensor working surface can be ensured only under the condition of complete wetting of the nanostructured layer. Therefore, it is important to take into account the peculiarities of the wetting process of a specific morphology of nanostructures. © 2022 V. Gerbreders et al., published by Sciendo.Institute of Solid State Physics, University of Latvia has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART2

Spectroscopic analysis of thin films fabricated from benzanthrone luminescent dye

Thin films samples of organic luminophore - 3-N,N-diacetylaminobenzanthrone deposited on glass substrate were prepared by thermal evaporation obtaining thin films of 2.5 to 3 μm thickness. The structural and spectroscopic properties of obtained films were investigated by confocal microscope with input of femtosecond laser radiation, Xray diffractometer and scanning electron microscope. It was found that prepared films are highly ordered materials with molecular layers; X-ray diffraction analysis indicate that the distance between these layers is ~6.5 Å. In addition, quantum chemical calculations were performed, indicating electron properties of studied dye molecule in ground and excited state. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2061

Диагностирование когнитивного развития детей через оценку разделенной интенциональности в биотехнической системе

Introduction. Recent research shows that up to 17 % of children are diagnosed with cognitive developmental disorders. Early identification of developmental delay in children allows an earlier onset of treatment with greater efficiency. However, the modern diagnostic approach has limitations associated with the problem of correctly assessing behavioral markers of children. This classical assessing approach depends on specialists’ professionalism of and parents' competence in reporting the issue timely and informatively.Aim. Developing a computerized methodology and algorithm for estimating shared intentionality in mother-child dyads; designing a biotechnical system for the early diagnosis of a lag in children's cognitive development.Materials and methods. We analyze our own previous research, in which: 1) the goal was to measure the intellectual activity of a group while stimulating their shared intentionality; 2) the independent variable was the intellectual task; 3) the stimuli of shared intentionality were described. The method employs the mathematical apparatus of measurement theory, systems theory, and statistical methods of analysis.Results. The developed biotechnical system uses specific software for diagnosing cognitive delay in children during a 15-minute test. Two factors of the biotechnical system impact the object of assessment: an electromagnetic field for stimulating shared intentionality and an intellectual test. The system's software instantly provides the assessment results to the user (specialist or parents) in the form of recommendations understandable even to a non-specialist – it saves this database in a convenient form for further storage and processing.Conclusion. The advantage of the method is its unbiased computerized assessment, which can also diagnose subjects online, conversely to the classical approach based on behavioral markers. Another advantage of the assessment method is the possibility of diagnosing a lag in children's cognitive development at an earlier age, which does not yet imply verbal communication.Введение. До 17 % детей диагностированы с нарушениями когнитивного развития. Выявление задержки развития детей на раннем этапе позволяет осуществлять раннее лечение с большей эффективностью. Современная диагностика имеет ряд ограничений, связанных с проблемой корректной оценки маркеров поведения детей. Классический метод зависит от квалификации специалистов и способности родителей своевременно выявить и информативно сообщить о проблеме.Цель работы. Разработка компьютеризированной методики и алгоритма оценки разделенной интенциональности в парах мать–ребенок, создание биотехнической системы ранней диагностики отставания когнитивного развития детей.Материалы и методы. Анализируются собственные исследования, в которых целью являлось измерение интеллектуальной деятельности группы при стимулировании их разделенной интенциональности; независимой переменной было интеллектуальное задание; описаны стимулы разделенной интенциональности. Применен математический аппарат теории измерений, теории систем и статистического исследования зависимостей.Результаты. Создана биотехническая система, использующая программное обеспечение для диагностики когнитивного отставания детей в течение 15-минутного квиц-теста. Два фактора воздействия биотехнической системы на объект оценки: электромагнитное поле для стимуляции разделенной интенциональности и интеллектуальный тест. Результаты оценки предоставляются пользователю (специалисту или родителям) моментально в форме рекомендаций, понятных неспециалисту, и в форме базы данных, удобной для дальнейшего хранения и обработки.Заключение. Преимущество метода – в объективности компьютеризированной оценки, диагностирующей объект также онлайн, в отличие от классического подхода, основанного на маркерах поведения детей. Еще одно преимущество метода оценки заключается в возможности диагностирования отставания когнитивного развития детей в более раннем возрасте, который еще не предполагает вербальной коммуникации

Novel merwinite/akermanite ceramics: in vitro bioactivity

The ceramics in the system CaO – MgO – SiO2 has recently received a great deal of attention because they exhibit good in vitro bioactivity and have potential use as bone implants. Biphasic calcium-magnesium-silicate ceramics was prepared by a sol-gel method. The dried gel with chemical composition 3CaO.MgO.2SiO2 was thermally treated at 1300°C for 2 h. The structural behavior of the synthesized ceramics was examined by means of X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). Merwinite, as the main crystalline phase, and akermanite, as the minor phase, were identified. The in vitro bioactivity of the synthesized ceramic samples was recorded in Simulated Body Fluid (SBF) for different times of soaking. The apatite formation on the surface of the immersed samples was detected by FTIR, SEM and Energy Dispersive Spectroscopy (EDS) techniques. The ion concentrations in the SBF solutions after the in vitro test were evaluated by Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). On the basis of the results obtained, the ability of the biphasic ceramics to deposit apatite layer was found. The peculiarities of the formation of apatite layer depending on the phase composition were analyzed and discussed

Postnatal cerebellar development in a mouse

The cerebellum is a part of the central nervous system, which plays an important role in cognitive functions, discriminative sensibility, and the coordination of voluntary movements. Its development takes place in two stages: prenatal and postnatal. The cerebellar germ originates from the rhombic lip. There are two major groups of cells: glutamatergic and GABAergic neurons, which are generated at different spatial-temporal intervals. In the postnatal period, Purkinje cells and their synaptic contacts undergo the most significant development. Another key point is the formation of anchoring centers and the foliation of the brain.The cerebellum is a part of the central nervous system, which plays an important role in cognitive functions, discriminative sensibility, and the coordination of voluntary movements. Its development takes place in two stages: prenatal and postnatal. The cerebellar germ originates from the rhombic lip. There are two major groups of cells: glutamatergic and GABAergic neurons, which are generated at different spatial-temporal intervals. In the postnatal period, Purkinje cells and their synaptic contacts undergo the most significant development. Another key point is the formation of anchoring centers and the foliation of the brain

Экспериментальная модель неинфекционного гранулематоза легких

Experimental model of noninfectional granulomatosis in lungs was elaborated by the authors. The lung granulomatosis was induced by Sefadex A-25 aerosol inspiration in Wistar rats. It was characterised by the mature macrophagal granulomas appearance in couple with acute bronchitis and alveolitis. Granulomatous reaction in lungs was accompanied by extreme hyperplasia of lymphoid bronchial folliculi. The bronchial alveolai lavage cell count, especially neutrophil, lymphocyte, and polynuclear macrophage counts, increased during the experiment. Maximally manifestated changes of the mentioned parameters were noted after 7 days since Sefadex A-25 aerosol inhalation. Using the elaboreted model of noninfectional pulmonary granulomatosis, it was demonstrated that the model can be used to estimate the efficiency of antiinflammatory and immunomodulating pharmacological products, as well Budesonide, which are used in pulmonology.Разработана экспериментальная модель неинфекционного гранулематоза легких. При аэрозольном в ведении сефадекса А-25 у крыс Вистар развивается гранулематоз легких, морфологически характеризующийся образованием зрелых макрофагальных гранулем в сочетании с острым бронхитом и альвеолитом. Гранулематозная реакция легких сопровождается выраженной гиперплазией лимфоидных фолликулов бронхов. В бронхоальвеолярном смыве увеличивается количество клеточных элементов, и среди них повышается процентное содержание нейтрофилов, лимфоцитов и многоядерных макрофагов. Максимально выраженные изменения указанных показателей отмечаются на 7-е сутки после аэрозольного введения сефадекса А-25. На разработанной модели неинфекционного гранулематоза легких продемонстрирована, на примере будесонида, возможность использования ее для оценки эффективности противовоспалительных и иммуномодулирующих фармакологических препаратов, используемых в пульмонологии