Size and composition dependent electrochemical oxidation and deposition of metal nanostructures.

This dissertation describes (1) size-dependent electrochemical oxidation/stripping of gold and silver nanoparticles (NPs), (2) alloying of copper with gold nanoparticles at underpotential deposition potentials, (3) electrochemical characterization of Au/Ag core-shell structures, (4) characterization of metal nanoparticle alloys by stripping voltammetry, and (5) layer-by-layer assembly of metal nanoparticle/polymer structures. The motivation of this work is to better understand fundamental properties of metal nanostructures as a function of size, shape, and composition. We synthesized Au and Ag NPs with different size by electrochemical reduction of the metal salt directly on the electrode surface and by seed-mediated growth in solution followed by chemisorption on a silane functionalized electrode surface, respectively. Linear sweep voltammetry results demonstrated a negative shift in peak potential for oxidation with decrease in size. For Ag NPs, the oxidation potential is 275 mV and 382 mV for 8 and 50 nm particles, respectively. In the case of Au NPs, the peak potentials are 734 and 913 mV for 4 and 250 nm particles, respectively. This shift in oxidation potential with change in size of metal nanoparticles is consistent with Plieth theory. Underpotential deposition of copper on Au NPs of different size led to alloying of Au and Cu. Several peaks were observed on linear sweep voltammograms. We assigned these peaks to different copper locations in the alloy structure: (1) Cu UPD on the surface of Au NP, (2) outer-shell Cu-Au alloy, and (3) core of Cu-Au NP alloy. Au/Ag core-shell nanostructures were synthesized by seed-mediated growth directly on the electrode surface and characterized with electrochemical techniques. During electrochemical characterization, dealloying of Au from Au/Ag alloy structures occurred by cycling in bromide containing electrolyte solution. Composition analysis based on LSV showed that less than 3% of Au remained on the electrode surface. SEM images showed that the morphology of Au/Ag nanostructures changes after electrochemical oxidation. Particles become bigger and form hollow bulbs , porous structures, and networks. We also synthesized Au/Ag alloy nanoparticles through a high temperature seed-mediated growth procedure and characterized them by UV-Vis and LSV at different stages of synthesis. LSV results provided information about the composition and atomic arrangements of alloy nanoparticles synthesized using 1:1 Au:Ag ratio, but a different synthesis method. After a 24-hour heating time, the (Au 4nm )Ag NPs did not show the oxidation peak for Ag, indicating that it stabilized during the alloy formation. In the case of (Ag 8nm )Au NPs, Ag oxidation peak appeared on LSVs regardless the heating time. Electrochemical characterization and UV-vis spectroscopy results for metal nanoparticle-polymer multilayer films showed that, with increase in the number of metal-polymer layers, absorbance and coverage increases due to an increase of the amount of metal assembled on the surface. A red shift in peak wavelength indicates an increase in size and aggregation of NPs on the electrode surface. SEM analysis shows that the morphology of the film depends on the nature of the metal deposited and the size of NPs. Films of Ag NPs consisted of large aggregated structures on the electrode surface, while films of Au NPs were uniform and porous. Experiments on the electron transfer through the polymer film to the metal NPs, demonstrated that electron transport depends on the number of polymer bilayers and the nature of the NPs. After deposition of 5 polymer bilayers, Au oxidation peak disappeared, while Ag oxidation peak was lower compared to 1 layer, but still observable. This dissertation describes a few sets of experiments on fundamental electrochemical properties of metal nanostructures. The results of these experiments are crucial for the application areas such as catalysis and sensing. It is important to study the stability of these nanoparticles, and also their recycling potential, since it can be affected by changes in the shape and size of the nanoparticles during the course of a reaction. This will not only provide information about electrochemical stability but may also prove useful as a method for analyzing nanoparticles and using them as labels for analytical applications by electrochemical stripping voltammetry

Additive Manufacturing (AM) and Nanotechnology: Promises and Challenges

The narrow choice of materials used in Additive Manufacturing (AM) remains a key limitation to more advanced systems. Nanomaterials offer the potential to advance AM materials through modification of their fundamental material properties. In this paper, the authors provide a review of available published literature in which nanostructures are incorporated into AM printing media as an attempt to improve the properties of the final printed part. Specifically, we review the research in which metal, ceramic, and carbon nanomaterials have been incorporated into AM technologies such as stereolithography, laser sintering, fused filament fabrication, and three-dimensional printing. The purpose of this article is to summarize the research done to date, to highlight successes in the field, and to identify opportunities that the union of AM and nanotechnology could bring to science and technology.Mechanical Engineerin

Increasing the budget costs’ efficiency as a factor of state finance stabilization

The article stands for comprehensive system approach in increasing the effect and performance of budget costs, providing the stability and long-term sustainability of state finance. In recent times Russia has gone to considerable lengths in introduction of result-oriented budgeting both on federal and regional level. In a similar vein, we could highlight the fact that insufficient conditions are created to increase the efficiency of budget costs management. The research paid much attention to the issues connected with evaluation of budget costs’ performance in conditions of implementing the concept of budget consolidation and budget constraints. Authors set number of objectives: studying economic essence of “efficiency” and “performance” of budget expenditures; studying the framework of budget stabilization financial support measures; revealing the methodological approaches in budget cost effect evaluation in the framework of program-target budgeting including the regional level. The article concludes with the necessity of improving the evaluation system of criterion-based budget costs’ management as well as highlighting the condition when the positive effect of program-target budgeting is reached: firstly, solving of methodological problem of measuring the planned (target) and actual results of budget funding; secondly, taking measures of strengthening the real responsibility of state authorities for accomplishment of target indicatorspeer-reviewe

Organizing Public Procurement in Ukraine and the European Union Countries

The article is concerned with the topical issues of improving the competitiveness of the national economy by improving the procedure of public procurement. The article is aimed at identifying the features of organization of public procurement in Ukraine and comparing it with the organization of these procedures in the countries of the European Union, which would reveal shortcomings of the Ukrainian model of public procurement, and developing recommendations as to overcoming them and approximation to the standards of the European Union. The mechanism of organization of procurement procedures in accordance with the EU directives has been determined, the analysis of both centralized and decentralized models of public procurement in the EU countries has been carried out. A comparative characterization of organizing the domestic electronic system of public procurement and the Georgian and European ones was carried out. The stages of procurement in the EU organizational model, which are absent in the Ukrainian model and require implementation to improve the efficiency of public procurement procedures, are defined

The Eurasian economic union customs’ administration mechanism in the digital era

Purpose: The aim of the article is to identify the prospects for the Eurasian Economic Union (EEU) customs regulation mechanism in digital transformation following the global trend. Design/Methodology/Approach: For the purpose of determining priorities for the EEU customs mechanism digitization, it is necessary to define the regulatory framework on which the digitalization process is based, to analyze the customs’ regulation sphere digitization direction in the member states of the EEU and to formulate the priorities for improving the EEU customs’ regulation mechanism on the information and communication technologies. Findings: EEU customs’ regulation mechanism digitization key areas have been identified, based on the provisions of the EEU’s Digital Agenda and the Declaration on further development of integration processes within the Union. Practical implications: The results can be implemented in the Eurasian Economic Commission management practice, the EEU member states customs’ authorities in order to improve the customs regulation mechanism. Originality/Value: The main contribution of this study is to identify the differences in the customs regulation sphere digitization processes in the EEU member states and to identify the areas for implementing a unified strategy.peer-reviewe

Tendências atuais no estado e regulação legal do componente religioso na educação

The article presents the results of modern model comparative legal analysis concerning state and legal regulation of the religious component in education within the context of state and municipal educational organization profile activity. The conceptual features of such regulation optimal model are determined, claiming the status of universal ones; their uniform consolidation in the special educational legislation of modern secular states is justified.El artículo presenta los resultados del análisis jurídico comparativo del modelo moderno sobre la regulación estatal y legal del componente religioso en la educación dentro del contexto de la actividad de perfil de la organización educativa estatal y municipal. Se determinan las características conceptuales de dicho modelo de regulación óptima, reclamando el estado de los universales; su consolidación uniforme en la legislación educativa especial de los estados seculares modernos está justificada.O artigo apresenta os resultados do modelo moderno de análise comparativa da legislação estadual e jurídica sobre o componente religioso na educação no contexto da atividade de perfil das organizações educacionais estaduais e municipais. As características conceituais desse modelo ótimo de regulação são determinadas, reivindicando o status das universais; sua consolidação uniforme na legislação educacional especial dos estados seculares modernos é justificada

Electron-ion plasma modification of Al-based alloys

The paper reports on the study where we analyzed the surface structure and strength properties of coated Al alloys modified by electron-ion plasma treatment. The Al alloys were deposited with a thin (≈0.5 μm) TiCu film coating (TiCu-Al system) and with a hard TiCuN coating (TiCuN–AlSi system) on a TRIO vacuum setup in the plasma of low-pressure arc discharges. The temperature fields and phase transformations in the film–substrate system were estimated by numerical simulation in a wide range of electron energy densities (5–30 J/cm2) and pulse durations (50–200 μs). The calculations allowed us to determine the threshold energy density and pulse duration at which the surface structure of the irradiated Al-based systems is transformed in a single-phase state (solid or liquid) and in a two-phase state (solid plus liquid). The elemental composition, defect structure, phase state, and lattice state in the modified surface layers were examined by optical, scanning, and transmission electron microscopy, and by X-ray diffraction analysis. The mechanical characteristics of the modified layers were studied by measuring the hardness and Young’s modulus. The tribological properties of the modified layers were analyzed by measuring the wear resistance and friction coefficient. It is shown that melting and subsequent high-rate crystallization of the TiCu–Al system makes possible a multiphase Al-based surface structure with the following characteristics: crystallite size ranging within micrometer, microhardness of more than 3 times that in the specimen bulk, and wear resistance ≈1.8 times higher compared to the initial material. Electron beam irradiation of the TiCuN–AlSi system allows fusion of the coating into the substrate, thus increasing the wear resistance of the material ≈2.2 times at a surface hardness of ∼14 GPa

Double-stranded RNAs are promising adjuvants for enhancing immunogenicity of vaccines

Background. The most effective way to prevent infectious diseases is vaccination. Adjuvants contribute to the optimization of the immune response of vaccines. Double-stranded ribonucleic acids (dsRNAs) from natural sources are promising, but insufficiently studied adjuvants. The aim of the work was to study the adjuvant activity of dsRNA obtained from the killer strain of Saccharomyces cerevisiae using two models of induction of a specific immune response. Materials and methods. In the experiments, the substance of the drug Ridostin containing dsRNA, 21.72% (produced by Institute of Medical Biotechnology of the State Research Center of Virology and Biotechnology Vector), was used. A specific immune response was modeled using ovalbumin (OVA) or the substance of the EpiVacCorona vaccine (EVC). The experiments were carried out in 200 female BALB/c mice. Mice of the experimental groups were injected twice with antigen and adjuvant together with a 28-day interval, mice of the comparison group with antigen only. On the 10th day after the second immunization, blood samples were collected to determine the level of specific antibodies using enzyme immunoassay. The results were evaluated by calculation of the average geometric titers of specific antibodies against OVA or EVC. Results. OVA or EVC administered twice induced the specific antibodies in mice in dose-dependent titers. The combined administration of antigen and dsRNA increased the strength of the immune response. The highest stimulating effect of dsRNA was observed in the dose of 100 g/mouse administered into mice immunized with OVA (1 g/mouse) or in the dose of 50 g/mouse in mice immunized with EVC substance (0.25 of a human dose per mouse). Conclusion. The data obtained indicate that the substance of dsRNA exerts adjuvant properties, which gives reason to consider dsRNA as a promising adjuvant for peptide vaccines

Frequency of EGFR mutations in non-small cell lung cancer patients: screening data from West Siberia

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Glutamate Concentration in the Serum of Patients with Schizophrenia

Glutamate is the major neurotransmitter with multiple functions in the central nervous system. Glutamate-mediated excitotoxicity is involved in the pathophysiological processes in schizophrenia. The purpose of this study was to determine the concentration of glutamate in the serum of patients with paranoid schizophrenia compared with healthy individuals, and depending on the duration of the schizophrenic process and leading clinical symptoms. We investigated the level of glutamate in the serum of 158 patients with paranoid schizophrenia and 94 healthy persons. Higher concentrations of glutamate in schizophrenic patients compared with healthy persons have been found. The maximum concentrations of glutamate were detected in patients with disease duration of more than ten years. Glutamate level in the serum does not depend on the prevailing negative or positive clinical symptoms. The increased concentration of glutamate can hypothetically contribute to dopaminergic and glutamatergic imbalance, leading to the development of psychotic symptoms and cognitive dysfunction