14 research outputs found
Study of the mechanical properties of single- layer and multi-layer metallic coatings with protective-decorative applications
Get PDFSingle thin coating of matt nickel (Nimat), a mirror bright copper (Cubright), a mirror bright nickel (Nibright) and their combinations were electrochemically deposited on brass substrate with thickness 500 μm. The basic aim was electrodeposition of two-layer Cubright/Nimat and Nibright/Cubright systems, and three-layer Nibright Cubrigh/Nimat system, which are among the most widely applied protective and decorative systems in light and medium operating conditions of corrosion. The thicknesses of the obtained films varied from 1 μm to 3.25 μm. They were investigated via nanoindentation experiments, in order to characterize their basic physical and mechanical characteristics, related with their good adhesion and corrosion protective ability, as well as ensuring the integrity of the system “protective coating/substrate” to possible mechanical, dynamic and/or thermal stresses. As a result, load-displacement curves were obtained and indentation hardness and indentation modulus were calculated using the Oliver & Pharr approximation method. The dependence of the indentation modulus and the indentation hardness on the depth of the indentation, surface morphology and structure of the obtained coatings, their texture and surface roughness were investigated too. The obtained results showed that the three-layer Nibright/Cubright /Niimat/CuZn37 system has highest indentation modulus and indentation hardness, following by two-layer Nibright/Cubright system and single layer coatings.</jats:p
Study of the mechanical properties of single- layer and multi-layer metallic coatings with protective-decorative applications
No full textSingle thin coating of matt nickel (Nimat), a mirror bright copper (Cubright), a mirror bright nickel (Nibright) and their combinations were electrochemically deposited on brass substrate with thickness 500 μm. The basic aim was electrodeposition of two-layer Cubright/Nimat and Nibright/Cubright systems, and three-layer Nibright Cubrigh/Nimat system, which are among the most widely applied protective and decorative systems in light and medium operating conditions of corrosion. The thicknesses of the obtained films varied from 1 μm to 3.25 μm. They were investigated via nanoindentation experiments, in order to characterize their basic physical and mechanical characteristics, related with their good adhesion and corrosion protective ability, as well as ensuring the integrity of the system “protective coating/substrate” to possible mechanical, dynamic and/or thermal stresses. As a result, load-displacement curves were obtained and indentation hardness and indentation modulus were calculated using the Oliver & Pharr approximation method. The dependence of the indentation modulus and the indentation hardness on the depth of the indentation, surface morphology and structure of the obtained coatings, their texture and surface roughness were investigated too. The obtained results showed that the three-layer Nibright/Cubright /Niimat/CuZn37 system has highest indentation modulus and indentation hardness, following by two-layer Nibright/Cubright system and single layer coatings
MANAGEMENT OF GRADUATE STUDENT’S THESIS WRITING THROUGH A SPECIALIZED SOFTWARE SYSTEM
Get PDFThe inclusion of Learning Management Systems (LMSs) in the Bulgarian academic institutions has augmented students’ learning experience. The paper presents a software system for managing and supporting the interaction between graduate students and their supervisors in the course of theses writing. The system allows to plan, manage and track the progress of students’ theses/graduation projects. The author makes a comprehensive critical examination of the specialized software systems’ impact on the process of teaching and learning. Further studies and practical implications are also discussed
Verbal and musical choral actions in theatrical productions. Methodological and music staging aspects
Get PDFThe text is based on two realized theatre events. „Medea†by Euripidies (producer Desislava Shpatova, Plovdiv, 2020) and „Oedipus The Tiran – choruses) acting studio „Sound, Text, Melos†based on fragments from Sophocles’ tragedy (NBU, The Red House, Sofia, 2017). In the text, the author presents new approaches to the interpretation of traditional choruses in ancient Greek theater. He examines not only his own compositional techniques for creating choral episodes, but also various aspects of the preparatory rehearsal process, as well as describing some of the difficulties that theatre actors and students face in meeting such choral practices. He shares his preparatory and musicalstaging methods for the achievement of theatrical-musical unity and integrity in the choral episodes in the considered productions
Tyrosine kinase inhibitors in modern oncotherapy
Get PDFThe widespread prevalence and increasing incidence of cancer has imposed the introduction of new therapeutic approaches and medications. The elucidation of the key role of receptor tyrosine kinases (RTKs) in intercellular signaling and their involvement in fundamental processes, replication, growth, differentiation, and apoptosis, has provided substantial evidence linking their altered functionality to tumorigenesis.This review aims to briefly discuss the role of RTKs in tumorigenesis and characterize tyrosine kinase inhibitors (TKIs), focusing on their mechanisms of action, pharmacodynamics, and pharmacokinetics as essential drugs in modern targeted cancer therapy.Two primary mechanisms inhibit mutated or overexpressed RTKs. The first involves monoclonal antibodies targeting the extracellular domains of RTKs or their ligands, inhibiting RTK dimerization and activation, thus forming the group of extracellular TKIs. The second mechanism involves small-molecule TKIs targeting the intracellular tyrosine kinase domain of the receptors or other intracellular tyrosine kinases mediating their signaling pathways. Numerous mono- and multi-targeted TKIs have been developed, addressing one or more signaling pathways. Identifying specific mutations in individual patients and applying specific TKIs have introduced the principles of personalized cancer therapy. Most TKIs are well-tolerated and significantly improve patient survival. The selectivity of TKIs toward their targets determines their efficacy and safety profile.Despite their advantages, TKI therapy is associated with significant toxic effects and high variability due to their pharmacokinetic features. Literature discusses the potential of therapeutic drug monitoring to optimize dosing, thereby enhancing efficacy and minimizing adverse side effects.In summary, TKIs are pivotal medications in modern oncology that have revolutionized the treatment paradigm for numerous cancers
Equity Ownership Strategy in Greenfield Investments : Influences of Host Country Infrastructure and MNE Resources in Emerging Markets
Get PDFThis chapter addresses equity ownership strategy in greenfield investments by multinational enterprises (MNEs) in the emerging markets (EMs). It is one of the few studies to hypothesize and analyze influences of host EM physical infrastructure in relation to investment decisions of MNEs. We use resource dependence theory (RDT) as a theoretical basis and test the moderating effects of firm resources like size and host country investment experience. Moreover, the current study assumes a more nuanced approach to studying equity ownership by analyzing wholly owned subsidiaries versus joint ventures (JVs) and including majority versus minority JVs in the analysis as well. The empirical results based on greenfield investments undertaken by Nordic (Danish, Finnish, Norwegian, and Swedish) MNEs in EMs during 1990–2015 reveals the importance of host country physical infrastructure for high equity ownership strategy. Moreover, host country investment experience moderates the effect of physical infrastructure on equity ownership strategy. Finally, the analysis of a sub-sample of greenfield JVs reveals that determinants of equity ownership strategy differ somewhat between greenfield JV or greenfield wholly owned subsidiaries (WOS).© The Author(s) 2019.fi=vertaisarvioitu|en=peerReviewed
Factor Productivity of Chosen Bulgarian Agricultural Productions
No full textТhe study focus on the Total Factor Productivity (TFP) for selected agricultural sectors (fruit growing, viticulture and dairy cattle breeding). The methodology used to determine TFP is according to Regulation (EU) 834/2014 laying down monitoring and evaluation framework for CAP 2014-2020. The Laspeyers index was applied to analyze the development of agricultural production and to explore the influence of different factors on the production output during the CAP implementation. The change was reviewed in comparison to a basis period and TFP was estimated as an index coefficient represented as industry output and the driving inputs (including labour, capital, land, variable production costs and subsidies). The study reveals a significant change in TFP indexes over the period after Bulgaria’s accession to the EU. The results show the TFP indexes decrease for fruits and cow’s milk and increase for grapes (due to improved efficiency). There is a drop in production for grapes and cow’s milk but a significant increase in production quantities for fruits. Meanwhile, the TFP index for fruit growing is slumping down, which is explicated by tangible enhancement in investment and capital costs during the covered period, which deems to improve the productivity and efficiency in the coming years. There is a need to increase and target the financial support for viticulture and dairy farming in order to hoist up the productivity and production outputs.This article is published as Toteva, D., Dimitrova, D., Stoychev, V., Factor Productiviy of Chosen Bulgarian Agricultural Prouctions. Agriculture and Foresty, 2022, 68(3);147-159. doi: 10.17707/AgricultForest.68.3.12. Posted with permission. Open Access-policy: This is an open access journal with all the content freely available without charge to the users. Users are allowed to read, download, copy, distribute, print, search, or link to the full texts of the articles in this journal without asking prior permission from the publisher or the author. This is in accordance with the Budapest Open Access Initiative (BOAI) definition of open access. The only constraint on reproduction and distribution, and the only role for copyright in this domain, should be to give authors control over the integrity of their work and the right to be properly acknowledged and cited.
We accepted Open Access-policy becouse of Higher Citation Impact of open access articles due to their high publicity and availability. It has been demonstrated that open access publications are more frequently cited! <br/
Asset prices and exchange rates: a time dependent approach
Get PDFThis paper studies the relationship between exchange rates and asset prices. It takes the novel approach of modeling both the markets in a framework of heterogeneous agents. Investors maximize their profits from the international equity markets by solving a Mean-Variance problem. As a result, agents choose between different combinations of rules in the home and foreign equity market as well as in the foreign exchange market. Given the incomplete information setting, agents check the past profitability of their rules and switch behavior in the effort to maximize their profits. Due to the heuristics embedded within the model, this simple frame-work alone is able to create a complex, time-varying dynamics. This dynamics is analyzed for different parameters and conditions. Finally the model is brought to the data, to check the fitness of the predictions on the real world markets.Behavioral finance, exchange rates, asset prices
Foreign exchange and stock market: tow related markets?
Get PDFThis paper studies the relationship between the stock market and the exchange rate in several countries. The approach taken in the first part of this study is a linear VAR, to be compared in the following part to a MSVAR. The data is also analyzed by Granger causality tests in both contexts and a thorough description of the empirical results obtained is shown. The research uncovers a spread (but not constant over time) causality from the exchange rate and American stock market to the local markets of the different nations studied. The non-linear, time varying approach allows several considerations on the dynamics of the relationship. The markets analyzed are the Japanese, the British and the German (pre-Euro) market against the US Dollar and the US stock market. The frequency of the data used is daily.
