32 research outputs found
Structure et dynamique de spin d'un complexe métallique étudié par rayonnement synchrotron
No full textThe thesis “Structure and Spin Dynamics of a Metal Complex Studied by Synchrotron Radiation” describes an experimental study of the metal complex [FeII(phen)3]2+ in solution by time-resolved X-ray scattering and emission spectroscopy aimed at monitoring changes in structure and spin during its photocycle. In the photoexcited state, a 3d electron is transferred to the ligand for a fraction of a picosecond. From this so-called metal-to-ligand charge transfer state (MLCT), the electron returns to the metal in an excited high spin state (HS) that in turn decays to the low spin (LS) ground state in 725 ps. The structure and spin of the HS state were measured by X-ray scattering (WAXS) and X-ray emission spectroscopy (XES) respectively with 100 picosecond resolution using single X-ray pulses from the synchrotron.Chapter 1 describes the importance of visualising atoms in chemical reactions and transformations. The use of X-rays to gain structural sensitivity is now allowing to visualise photoinduced reactions with 100 picosecond resolution at synchrotrons and lately at 100 femtosecond resolution at XFELs.In chapter two “Probing Molecular Structure in Solution with X-rays”, the theory of X-ray scattering is presented stressing that when the structure is known, the molecular scattering pattern is readily calculated. Compton scattering dominates the scattering at high q and has to be included in the scaling. The intensity of the scattering from a 0.36 mm water sheet is calculated for a 1E+9 photon pulse at 18 keV.When a solute is dissolved in a solvent, the atomic positions are described by statistical atom-atom functions g_ab(r) that can be calculated by MD. The scattering function S(q) is then calculated from g_ab(r) for Fe(phen)3 in water using the TIP4P model with LS and HS structures from DFT.Liquid X-ray scattering probes all atom-atom pairs in the sample including that of the solvent. In the hydrodynamic scattering theory, the liquid is assumed to be in local thermal equilibrium. The theory for the cooling of hot points is presented and the calculation shows that a solution with 2 mM excited Fe(phen)3 attains local thermal equilibrium in 100 ps.The end of chapter 2 gives a summary of X-ray emission spectroscopy (XES). Ka, Kb and valence-to-core (VtC) emission is discussed including their intensity, spin and ligand sensitivity. Kb is the most sensitive probe of the spin state.In chapter 3 the ESRF and ID09 are shortly described. The details of the Johann (JS) and Von Hamos (VH) spectrometers for XES are described with emphasis on the VH since it was used for the first time in this project. The count rate from Kb is extremely low, 0.01 ph/pulse/analyser and the sample has to be exposed for about 1 hour per time delay to get a Kb spectrum with a good S/N ratio.The WAXS and XES experiments are described in Chapter 4. After photoexcitation to the MLCT state, the electron returns to a metal centred HS state in < 100 fs for then to return to the GS in 725 ps. dS(q,t) are 100 ps snapshots of the average structural change for all pairs of atoms at time t. On short time scales t < 10 ns, the solvent is heated adiabatically at constant volume. The thermal response of water was measured in a dye/water mixture. The solvent corrected WAXS data show that the Fe-N distance increases by 0.19 Å in the HS state and that the HS population returns to the LS in 725 ps. The change in the water cage radius is inferred from the low-q data. It is found to contract by 0.3 Å in the HS state in spite of the 0.19 Å expansion of the Fe-N distance.The XES line shapes of the Kb lines were measured with the VH spectrometer and compared with Crispy simulations. The simulations confirm that the 725 ps state is the HS S=2 quintet. Very weak VtC emission, 100 times weaker than Kb, was also observed.Cette thèse intitulé «structure et dynamique de spin d’un complexe métallique étudié par rayonnement synchrotron» décrit une étude expérimentale du complexe métallique [FeII(phen)3]]2+ en solution par la diffusion des rayons X résolue en temps et la spectroscopie d’émission, dont l’objectif est de surveiller les changements structurels et de spin au cours du photocycle du complexe. Dans l’état photo-excité du complexe, un électron de l'orbitale 3d est transféré au ligand pour une fraction de picoseconde. Après ce “transfert de charge métal - ligand” (MLCT), l’électron revient au métal dans un état haut spin (HS) quasi-stable. Le photocycle se termine par un retour à l’état bas spin (BS), l’état fondamental, qui s’effectue en 725 ps. La structure et la rotation de l’état HS ont été mesurées avec une résolution temporelle de 100 ps.Le 1er chapitre commence par décrire l’importance de visualiser à l’aide de courtes impulsions de rayons X la façon dont les atomes se déplacent au cours de réactions chimiques et transformations. L’utilisation de rayons X pour des études structurelles a permis de visualiser les réactions induites par photons avec une résolution de 100 ps.Dans le chapitre 2 «Sonder la structure moléculaire en solution avec des rayons X», la théorie de la diffusion des rayons X est mentionnée. La diffusion de Debye à partir de molécules orientées au hasard est présentée. Lorsque la structure moléculaire est connue, le modèle de diffusion est facilement calculé. La diffusion inélastique domine la diffusion totale à grands q et doit également être prise en compte.La position des atomes dans une solution est décrite par des fonctions inter-atomiques g_ab(r) qui peuvent être simulées par la dynamique moléculaire. S(q) est calculé pour l’eau basées sur le modèle TIP4P. La diffusion d’un film d’eau de 0,36 mm d’épaisseur est calculée pour une impulsion de rayons X avec 1E+9 ph/pulse à 18 keV.Les modèles DFT des structures à bas et haut spins de Fe(phen)3 ont été générés et les fonctions S(q) ont ensuite été calculées par la fonction de Debye. La conclusion est que les liaisons Fe-N dans l’état HS s’allongent de 0,19 Å.La diffusion des rayons X par les liquides sonde toutes les distributions atome-atome dans l’échantillon, y compris celle du solvant ‘bulk’. Dans la théorie hydrodynamique, le liquide est supposé être en équilibre thermique local. L’expression pour le refroidissement des points chauds est examinée. Pour une concentration de 2 mM de Fe(phen)3 excité l’équilibre est atteint en 100 ps.La dernière section présente l’émission Ka, Kb; et valence-à-noyau (VtC, Valence-to-Core). Les spectromètres Johann (JS) et Von Hamos (VH) sont présentés. Le taux de comptage de Kb; est faible, 0,01 ph/pulse/analyseur, et l’échantillon a été exposé pendant 1 heure par délai pour obtenir un bon rapport signal-sur-bruit.Les expériences WAXS et XES sont décrites au chapitre 4. Après la photo-excitation en MLCT, l'électron transféré retourne à l'état HS centré sur le métal en environ 320 fs pour ensuite revenir à l'état BS par désintégration non radiative en 725 ps. Le changement de structure dans la transition BS-HS a été mesuré par diffusion de rayons X aux grands angles (WAXS) avec une résolution temporelle de 100 ps. L’échantillon était excité avec des impulsions de 1,2 ps à 400 nm et sondé par des impulsions de rayons X à 18 keV. Les courbes dS(q,t) sont des instantanés de 100 ps du changement structurel moyen pour toutes les paires d’atomes dans l’échantillon au moment t. Les données WAXS sont compatibles avec les structures BS et HS simulées par DFT avec une durée de vie HS de 725 ps. Le changement du rayon de la cage est déduit des données à petits q. La cage se contracte de 0,3 Å dans l’état HS.La ligne spectrale Kb a été mesurée avec le spectromètre von Hamos et comparée aux simulations Crispy. Les simulations confirment que l’état 725 ps est le quintet HS
Structure and spin dynamics of a metal complex studied by synchrotron radiation
No full textCette thèse intitulé «structure et dynamique de spin d’un complexe métallique étudié par rayonnement synchrotron» décrit une étude expérimentale du complexe métallique [FeII(phen)3]]2+ en solution par la diffusion des rayons X résolue en temps et la spectroscopie d’émission, dont l’objectif est de surveiller les changements structurels et de spin au cours du photocycle du complexe. Dans l’état photo-excité du complexe, un électron de l'orbitale 3d est transféré au ligand pour une fraction de picoseconde. Après ce “transfert de charge métal - ligand” (MLCT), l’électron revient au métal dans un état haut spin (HS) quasi-stable. Le photocycle se termine par un retour à l’état bas spin (BS), l’état fondamental, qui s’effectue en 725 ps. La structure et la rotation de l’état HS ont été mesurées avec une résolution temporelle de 100 ps.Le 1er chapitre commence par décrire l’importance de visualiser à l’aide de courtes impulsions de rayons X la façon dont les atomes se déplacent au cours de réactions chimiques et transformations. L’utilisation de rayons X pour des études structurelles a permis de visualiser les réactions induites par photons avec une résolution de 100 ps.Dans le chapitre 2 «Sonder la structure moléculaire en solution avec des rayons X», la théorie de la diffusion des rayons X est mentionnée. La diffusion de Debye à partir de molécules orientées au hasard est présentée. Lorsque la structure moléculaire est connue, le modèle de diffusion est facilement calculé. La diffusion inélastique domine la diffusion totale à grands q et doit également être prise en compte.La position des atomes dans une solution est décrite par des fonctions inter-atomiques g_ab(r) qui peuvent être simulées par la dynamique moléculaire. S(q) est calculé pour l’eau basées sur le modèle TIP4P. La diffusion d’un film d’eau de 0,36 mm d’épaisseur est calculée pour une impulsion de rayons X avec 1E+9 ph/pulse à 18 keV.Les modèles DFT des structures à bas et haut spins de Fe(phen)3 ont été générés et les fonctions S(q) ont ensuite été calculées par la fonction de Debye. La conclusion est que les liaisons Fe-N dans l’état HS s’allongent de 0,19 Å.La diffusion des rayons X par les liquides sonde toutes les distributions atome-atome dans l’échantillon, y compris celle du solvant ‘bulk’. Dans la théorie hydrodynamique, le liquide est supposé être en équilibre thermique local. L’expression pour le refroidissement des points chauds est examinée. Pour une concentration de 2 mM de Fe(phen)3 excité l’équilibre est atteint en 100 ps.La dernière section présente l’émission Ka, Kb; et valence-à-noyau (VtC, Valence-to-Core). Les spectromètres Johann (JS) et Von Hamos (VH) sont présentés. Le taux de comptage de Kb; est faible, 0,01 ph/pulse/analyseur, et l’échantillon a été exposé pendant 1 heure par délai pour obtenir un bon rapport signal-sur-bruit.Les expériences WAXS et XES sont décrites au chapitre 4. Après la photo-excitation en MLCT, l'électron transféré retourne à l'état HS centré sur le métal en environ 320 fs pour ensuite revenir à l'état BS par désintégration non radiative en 725 ps. Le changement de structure dans la transition BS-HS a été mesuré par diffusion de rayons X aux grands angles (WAXS) avec une résolution temporelle de 100 ps. L’échantillon était excité avec des impulsions de 1,2 ps à 400 nm et sondé par des impulsions de rayons X à 18 keV. Les courbes dS(q,t) sont des instantanés de 100 ps du changement structurel moyen pour toutes les paires d’atomes dans l’échantillon au moment t. Les données WAXS sont compatibles avec les structures BS et HS simulées par DFT avec une durée de vie HS de 725 ps. Le changement du rayon de la cage est déduit des données à petits q. La cage se contracte de 0,3 Å dans l’état HS.La ligne spectrale Kb a été mesurée avec le spectromètre von Hamos et comparée aux simulations Crispy. Les simulations confirment que l’état 725 ps est le quintet HS.The thesis “Structure and Spin Dynamics of a Metal Complex Studied by Synchrotron Radiation” describes an experimental study of the metal complex [FeII(phen)3]2+ in solution by time-resolved X-ray scattering and emission spectroscopy aimed at monitoring changes in structure and spin during its photocycle. In the photoexcited state, a 3d electron is transferred to the ligand for a fraction of a picosecond. From this so-called metal-to-ligand charge transfer state (MLCT), the electron returns to the metal in an excited high spin state (HS) that in turn decays to the low spin (LS) ground state in 725 ps. The structure and spin of the HS state were measured by X-ray scattering (WAXS) and X-ray emission spectroscopy (XES) respectively with 100 picosecond resolution using single X-ray pulses from the synchrotron.Chapter 1 describes the importance of visualising atoms in chemical reactions and transformations. The use of X-rays to gain structural sensitivity is now allowing to visualise photoinduced reactions with 100 picosecond resolution at synchrotrons and lately at 100 femtosecond resolution at XFELs.In chapter two “Probing Molecular Structure in Solution with X-rays”, the theory of X-ray scattering is presented stressing that when the structure is known, the molecular scattering pattern is readily calculated. Compton scattering dominates the scattering at high q and has to be included in the scaling. The intensity of the scattering from a 0.36 mm water sheet is calculated for a 1E+9 photon pulse at 18 keV.When a solute is dissolved in a solvent, the atomic positions are described by statistical atom-atom functions g_ab(r) that can be calculated by MD. The scattering function S(q) is then calculated from g_ab(r) for Fe(phen)3 in water using the TIP4P model with LS and HS structures from DFT.Liquid X-ray scattering probes all atom-atom pairs in the sample including that of the solvent. In the hydrodynamic scattering theory, the liquid is assumed to be in local thermal equilibrium. The theory for the cooling of hot points is presented and the calculation shows that a solution with 2 mM excited Fe(phen)3 attains local thermal equilibrium in 100 ps.The end of chapter 2 gives a summary of X-ray emission spectroscopy (XES). Ka, Kb and valence-to-core (VtC) emission is discussed including their intensity, spin and ligand sensitivity. Kb is the most sensitive probe of the spin state.In chapter 3 the ESRF and ID09 are shortly described. The details of the Johann (JS) and Von Hamos (VH) spectrometers for XES are described with emphasis on the VH since it was used for the first time in this project. The count rate from Kb is extremely low, 0.01 ph/pulse/analyser and the sample has to be exposed for about 1 hour per time delay to get a Kb spectrum with a good S/N ratio.The WAXS and XES experiments are described in Chapter 4. After photoexcitation to the MLCT state, the electron returns to a metal centred HS state in < 100 fs for then to return to the GS in 725 ps. dS(q,t) are 100 ps snapshots of the average structural change for all pairs of atoms at time t. On short time scales t < 10 ns, the solvent is heated adiabatically at constant volume. The thermal response of water was measured in a dye/water mixture. The solvent corrected WAXS data show that the Fe-N distance increases by 0.19 Å in the HS state and that the HS population returns to the LS in 725 ps. The change in the water cage radius is inferred from the low-q data. It is found to contract by 0.3 Å in the HS state in spite of the 0.19 Å expansion of the Fe-N distance.The XES line shapes of the Kb lines were measured with the VH spectrometer and compared with Crispy simulations. The simulations confirm that the 725 ps state is the HS S=2 quintet. Very weak VtC emission, 100 times weaker than Kb, was also observed
Специфика рекламы на современном суданском рынке товаров и услуг
No full textПредставленная выпускная квалификационная работа посвящена теме рекламной традиции в Республике Судан и вопросу о текущем уровне рекламы при формировании рыночных предпочтений. Данное исследование демонстрирует как экономически отсталая страна, находящаяся под санкциями, пытается развивать собственное предпринимательство, а также конкурировать с транснациональными гигантами на рынке. В работе представлена выборка из элементов наружной рекламы и рекламных объявлений, размещенных в средствах массовой информации, а также в интернете. Исследуется, какие компании заявляют о себе регулярно и качественно, а какие только пытаются соответствовать западным канонам рекламы. Также в работе рассматривается культурный и лингвистический аспект, в котором выражается уникальность суданской рекламы товаров и услуг.The thesis is devoted to the theme of the advertising tradition in the Republic of Sudan and the case of the current level of advertising in the formation of market preferences. The study shows how an economically backward country, being under sanctions, is trying to develop its own business, and also in its attempts to compete with transnational giants in the market. The paper consists of variation of advertisements posted on the Internet, the media, as well as outdoor advertising. It is investigated which companies declare themselves regularly and qualitatively, and which only try to comply with the Western canons of advertising. Also, the work considers the cultural and linguistic aspect, which expresses the uniqueness of Sudanese advertising of goods and services
RUSSIAN GOVERNMENT POLICY TOWARDS MONGOLIAN AND KAZAKH NATIONS IN LATE XVII-XVIII TH CENTURIES
No full textThe article analyzes the relationships between Russia (later the Russian Empire) and Central Asia countries, in particular with the Kazakh and Mongolian nations in the period of late XVII-XVIII th centuries. The research shows the features of mutual relationships, the purposes and tasks of the Russian policy in this region, and it also reveals the competition for supremacy there between Russia and China ruled by Qing dynasty. The author considers the advantages and drawbacks of the Russian political course developted by Peter I towards the Kazakh and Monogolians. Besides, the article considers the models of the relations between Russia and Central Asia nations, which enable to assess the results of the pursued foreign police of the country in this region
Effect of Current Efficiency on Electrochemical Micromachining by Moving Electrode
No full textAbstractIn this work, the effect of current efficiency on the electrochemical micromachining by moving electrode is studied theoretically. The Laplace equation for the electric potential and the equation of workpiece surface evolution are used as the mathematical model of the process. A new scheme of solution of free boundary problem for steady-state electrochemical micromachining is proposed. According to the scheme, the initial approximation of the workpiece surface is prescribed. In the course of modeling, the workpiece surface moves in the normal direction at a rate proportional to the discrepancy of the steady-state condition. The effect of various dependences of current efficiency on the local current density is analyzed. As a result of simulation, the dependences of the shape and sizes of machined surface on the current efficiency and the machining parameters are obtained
Comparison of drama The Storm and libretto to opera Katya Kabanova
No full text(in English): The topic of this thesis is The Comparison of Drama The Storm by Alexander Nikolayevich Ostrovsky and Libretto to Opera Katya Kabanová by composer Leoš Janáček. It summarises the creation, the premiere and the reception of both pieces of art, shortly describes the story, the main characters of the original work of art. Then, the thesis studies the circumstances of the creation of libretto, seeks the answer to the question why Leoš Janáček chose to write an opera based on drama The Storm. The main target of the thesis is the comparison of the story and the characters of both pieces of art with the focus on main character Katya Kabanová. In the end, the thesis tries to answer the questions why the libretto was changed as opposed to the original piece of art, what was the meaning of those changes and what influenced the author to make them
The future of virtual reality in marketing and advertising: benefits and challenges for business
No full textThe purpose of the study is to summarise the features of the application, advantages, disadvantages, as well as to develop an effective toolkit for the implementation of virtual reality as a means of marketing promotion for modern companies. Methodology: The study is based on the use of general scientific methods, including analysis, synthesis, induction, deduction, generalization, and systematization. As a result of the study and achievement of the set goal, the following results were obtained: the essence and features of the use of virtual reality in business and product promotion were determined; the advantages and disadvantages of using virtual reality in marketing were specified; the main tools for implementing virtual reality in the marketing activities of modern companies were systematized. The scientific novelty of the obtained results lies in the development of specific areas of application of virtual and augmented reality for marketing promotion of products on the market. At the same time, the author takes into account the experience of the world's leading companies and considers a significant list of advantages and disadvantages of marketing use of virtual and augmented reality. In conclusion, it is worth noting that virtual reality can be used as an effective marketing tool that reaches a large audience and significantly increases the likelihood of product purchase. In general, virtual and augmented reality open up new marketing opportunities by creating unique immersive experiences, which can significantly improve conversion rates and sales. In the future, these technologies will become even more popular and play a key role in marketing.
Мета дослідження полягає в тому, щоб узагальнити особливості застосування, переваги, недоліки, а також розробити ефективний інструментарій для впровадження віртуальної реальності як a засобу маркетингового просування сучасних компаній. Методологія: Дослідження базується на використанні загальнонаукових методів, включаючи аналіз, синтез, індукцію, дедукцію, узагальнення та ін систематизація. У результаті дослідження та досягнення поставленої мети були отримані наступні результати отримано: сутність та особливості використання віртуальної реальності в бізнесі та просуванні товару визначений; визначено переваги та недоліки використання віртуальної реальності в маркетингу. Систематизовані основні інструменти впровадження віртуальної реальності в маркетингову діяльність сучасних компаній. Наукова новизна отриманих результатів полягає в розробці окремих напрямків застосування віртуальної та доповненої реальності для маркетингового просування продукції на ринку. При цьому автори враховують досвід провідних світових компаній і розглядають значний перелік переваг і недоліків маркетингового використання віртуальної та доповненої реальності. Підсумовуючи вищевикладане, варто зазначити, що віртуальну реальність можна використовувати як ефективний маркетинговий інструмент, який досягає великої аудиторії і значно підвищує ймовірність покупки товару. Загалом, віртуальні і доповнена реальність відкриває нові маркетингові можливості, створюючи унікальний захоплюючий досвід, що може значно підвищити рівень конверсії та продажів. У майбутньому ці технології стануть ще більш популярні та відіграють ключову роль у маркетингу
Challenges of scientific knowledge visualization in publication productivity of the university academic staff
No full textIt has recently been shown that a person, an author particularly, faces the challenges of visualization in the cognitive process. The aim of this study is to consider the forms of thinking process and the changes happened in education process and in scientific activity. It was noted that the challenges connected with information perceiving during the work with the text occur in the process of creating academic papers as well. We conclude that the topical field of visualization covers not only the educative process assuming information transfer from person to person (model "teacher-student"), but the process of scientific activity. Applying the methods of visualization in publication activity is the factor for effective communication in social and cultural space that provides the opportunity for academic society to recognize results. We offer possible ways to promote scientific papers via online resources such as scientific social networks and tools of media corporations. The scientific social network ResearchGate and Thomson Reuters media corporation product as an online tool “Researcher ID” placed at the bibliographic database Web of Science TM Core Collection are used as the examples. We state that information technology allows authors to promote the results of their studies around the world
Challenges of scientific knowledge visualization in publication productivity of the university academic staff
No full textIt has recently been shown that a person, an author particularly, faces the challenges of visualization in the cognitive process. The aim of this study is to consider the forms of thinking process and the changes happened in education process and in scientific activity. It was noted that the challenges connected with information perceiving during the work with the text occur in the process of creating academic papers as well. We conclude that the topical field of visualization covers not only the educative process assuming information transfer from person to person (model “teacher-student”), but the process of scientific activity. Applying the methods of visualization in publication activity is the factor for effective communication in social and cultural space that provides the opportunity for academic society to recognize results. We offer possible ways to promote scientific papers via online resources such as scientific social networks and tools of media corporations. The scientific social network ResearchGate and Thomson Reuters media corporation product as an online tool “Researcher ID” placed at the bibliographic database Web of Science TM Core Collection are used as the examples. We state that information technology allows authors to promote the results of their studies around the world
High local disorder in pyrochlore oxide nanocrystals
No full textThe process of TbHfO nanocrystals formation upon annealing to 1600°C was investigated by means of X-ray absorption fine structure (XAFS) spectroscopy combined with X-ray diffraction (XRD) and pair distribution function (PDF) analysis. The structure ordering and the growth of nanocrystals upon annealing were estimated independently from XRD patterns and PDF. The probable content of Tb ions in TbHfO was estimated from XANES. All studies indicate a high disorder and a large number of local structure defects in TbHfO pyrochlore oxide
