Gaussian Process Regression for Materials and Molecules.

We provide an introduction to Gaussian process regression (GPR) machine-learning methods in computational materials science and chemistry. The focus of the present review is on the regression of atomistic properties: in particular, on the construction of interatomic potentials, or force fields, in the Gaussian Approximation Potential (GAP) framework; beyond this, we also discuss the fitting of arbitrary scalar, vectorial, and tensorial quantities. Methodological aspects of reference data generation, representation, and regression, as well as the question of how a data-driven model may be validated, are reviewed and critically discussed. A survey of applications to a variety of research questions in chemistry and materials science illustrates the rapid growth in the field. A vision is outlined for the development of the methodology in the years to come

Multivariate Analysis in Management, Engineering and the Sciences

Recently statistical knowledge has become an important requirement and occupies a prominent position in the exercise of various professions. In the real world, the processes have a large volume of data and are naturally multivariate and as such, require a proper treatment. For these conditions it is difficult or practically impossible to use methods of univariate statistics. The wide application of multivariate techniques and the need to spread them more fully in the academic and the business justify the creation of this book. The objective is to demonstrate interdisciplinary applications to identify patterns, trends, association sand dependencies, in the areas of Management, Engineering and Sciences. The book is addressed to both practicing professionals and researchers in the field

Surface bonding of a functionalized aromatic molecule : Adsorption configurations of PTCDA on coinage metal surfaces

The present work aims at establishing a comprehensive model for the bonding mechanism for the adsorption of the organic prototype molecule 3,4,9,10-perylenetetracarboxylic 3,4:9,10-dianhydride (PTCDA) on coinage metal surfaces. Due to its chemical constitution, the PTCDA molecule allowed studying the effects of both the ϖ-conjugated system and the presence of functional groups, including heteroatoms, on the interfacial bonding. As a basic principle, the surface bonding mechanism of large ϖ-conjugated molecules is of immense interest for understanding the structural and electronic properties of organic thin films. Insight into relevant interaction channels and their relative contribution to the bonding can be obtained from a detailed determination of the bonding configuration of the same molecule on different crystal faces of chemically related substrates (or one substrate), including the positions of all relevant atoms. Within the context of the present work, we have investigated the geometric adsorption configurations of PTCDA on the Cu3Au(111), the Ag(100), the Ag(110), and the K:Ag(110) surface [i.e., a potassium-modified, reconstructed Ag(110) surface] with the x-ray standing waves (XSW) technique under normal incidence. Thereby, we have amended the series of earlier XSW results on the adsorption configurations of PTCDA on coinage metal (111) surfaces, namely, on Au(111), Ag(111), and Cu(111). In addition, we have employed low-energy electron diffraction (LEED) and scanning tunneling microscopy (STM) in combination with x-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS) as well as theoretical calculations [at density functional theory (DFT) level] for clarifying both the lateral geometric structures and the electronic properties at the metal/organic interfaces, complementing earlier results. The adsorption height of the PTCDA molecules decreases in the series Au(111), Cu3Au(111) (in the initial, more Au-analogous and the final, more Cu-analogous adsorption state), Cu(111), Ag(111), Ag(100), and Ag(110), as was revealed by XSW. In addition, the intrinsically planar PTCDA molecules exhibit distortions in the adsorbed state which alter from one surface to the next. On the Au(111) surface, PTCDA is concluded to be essentially undistorted while on Cu3Au(111) and Cu(111) [4] PTCDA exhibits a boat-like distortion with the perylene core of the molecule being closer to the surface than the atoms within the functional groups. On the canonical Ag surfaces, however, the situation is reversed. The distortion of the PTCDA molecule is saddle-like on Ag(111) and arch-like on Ag(100) and Ag(110), respectively, with the carbon and the oxygen atoms within the functional groups being closer to the surface than the perylene core now. The distortion of the molecular C backbone increases with decreasing surface atom coordination number for PTCDA/Ag(hkl). On K:Ag(110), PTCDA adsorbs in a saddle-like configuration, too. On the basis of our structural and spectroscopic results, we propose a universal bonding mechanism for the adsorption of PTCDA on coinage metal surfaces. This bonding mechanism is composed of several constituents (bonding channels). Besides the inevitable van der Waals (vdW) interactions, the main bonding channels are (a) a metal-to-molecule charge transfer and (b) local O-M bonds (M = Ag, K) on the anhydride groups; (c) in some cases - especially in the case of strong surface bonding -, local C-M bonds (M = Ag, Cu) may evolve, too. Note that these bonding channels (a)-(c) are of chemical nature, that is, actual chemical bonds are formed between the surface (atoms) and the adsorbate molecules.Ziel der vorliegenden Arbeit ist die Entwicklung eines schlüssigen Modells für den Bindungsmechanismus der Adsorption des prototypischen organischen Moleküls 3,4,9,10-Perylentetracarbonsäure-3,4:9,10-dianhydrid (PTCDA) auf Münzmetalloberflächen. Aufgrund seines chemischen Aufbaus ermöglicht es das PTCDA-Molekül, die Auswirkungen sowohl des ausgedehnten ϖ-Systems als auch der Gegenwart funktioneller Gruppen mitsamt deren Heteroatomen auf die Grenzflächenbindung zu untersuchen. Grundsätzlich ist der Oberflächenbindungsmechanismus für große ϖ-konjugierte Moleküls von immensem Interesse für das Verständnis sowohl struktureller als auch elektronischer Eigenschaften von dünnen organischen Filmen. Einblicke in die relevanten Wechselwirkungskanäle und deren relativen Beitrag zur Gesamtbindung können gewonnen werden durch die Bestimmung der Bindungskonfiguration, inklusive der Positionen aller relevanten Atome, ein und desselben Moleküls auf verschiedenen Flächen chemisch verwandter (oder identischer) Substrate. Im Rahmen der vorliegenden Arbeit wurden die geometrischen Adsorptionskonfigurationen von PTCDA auf der Cu3Au(111)-, der Ag(100)-, der Ag(110)- sowie der K:Ag(110)-Oberfläche [d.h. einer Kalium-modifizierten, rekonstruierten Ag(110)-Oberfläche] mit Hilfe der Absorption im stehenden Röntgenwellenfeld (x-ray standing waves, XSW) unter senkrechtem Einfall untersucht. Im Zuge dessen wurde die Serie früherer XSW-Ergebnisse über die Adsorptionskonfigurationen von PTCDA auf Münzmetall-(111)-Oberflächen, nämlich auf Au(111), Ag(111) und Cu(111), ergänzt. Zusätzlich wurden die Beugung niederenergetischer Elektronen (LEED) und Rastertunnelmikroskopie (STM) in Verbindung mit Röntgenphotoelektronenspektroskopie (XPS) und Ultraviolettphotoelektronenspektroskopie (UPS) sowie theoretischen Rechnungen [auf Dichtefunktionaltheorie-Niveau (density functional theory, DFT)] zur Aufklärung der lateralen geometrischen Strukturen sowie der elektronischen Eigenschaften an den Metall-/Organik-Grenzflächen eingesetzt, um frühere Ergebnisse zu ergänzen. Die Adsorptionshöhe des PTCDA-Moleküls verringert sich in der Serie Au(111), Cu3Au(111) (im initialen, eher Au-analogen und im finalen, eher Cu-analogen Adsorptionszustand), Cu(111), Ag(111), Ag(100) und Ag(110). Zusätzlich weisen die intrinsisch planaren PTCDA-Moleküle im adsorbierten Zustand Verzerrungen auf, die sich je nach Oberfläche unterscheiden. Auf der Au(111)-Oberfläche wird PTCDA als im Wesentlichen planar angenommen, während auf Cu3Au(111) und Cu(111) PTCDA eine bootartige Verzerrung aufweist. Dabei ist der Perylenrumpf des Moleküls näher an der Oberfläche als die Atome innerhalb der funktionellen Gruppen. Auf Ag(111) ist die Verzerrung sattelartig bzw. auf Ag(100) sowie Ag(110) gewölbeartig, wobei hier die Kohlenstoff- und Sauerstoff-Atome in den funktionellen Gruppen näher an der Oberfläche sind als der Perylenrumpf. Die Verzerrung des Perylenrückgrates nimmt für PTCDA/Ag(hkl) mit abnehmender Koordinationszahl der Oberflächenatome zu. Auf K:Ag(110) adsorbiert PTCDA ebenfalls in einer sattelartigen Konfiguration. Ausgehend von unseren strukturellen und spektroskopischen Ergebnissen wird ein allgemeingültiger Bindungsmechanismus für die Adsorption von PTCDA auf Münzmetalloberflächen vorgeschlagen. Dieser Bindungsmechanismus besteht aus mehreren Komponenten (Bindungskanälen). Abgesehen von van der Waals-Wechselwirkungen (vdW), die immer vorliegen, sind die Hauptbindungskanäle (a) ein Metall-zu-Molekül Ladungstransfer sowie (b) lokale O-M Bindungen (M = Ag, K) an den Anhydridgruppen; (c) in einigen Fällen - insbesondere im Falle starker chemischer Bindung - können auch lokale C-M Bindungen (M = Ag, Cu) ausgebildet werden

Persuasion in Public Discourse

This book approaches persuasion in public discourse as a rhetorical phenomenon that enables the persuader to appeal to the addressee’s intellectual and emotional capacities in a competing public environment. The aim is to investigate persuasive strategies from the overlapping perspectives of cognitive and functional linguistics. Both qualitative and quantitative analyses of authentic data (including English, Czech, Spanish, Slovene, Russian, and Hungarian) are grounded in the frameworks of functional grammar, facework and rapport management, classical rhetoric studies and multimodal discourse analysis and are linked to the constructs of (re)framing, conceptual metaphor and blending, mental space and viewpoint. In addition to traditional genres such as political speeches, news reporting, and advertising, the book also studies texts that examine book reviews, medieval medical recipes, public complaints or anonymous viral videos. Apart from discourse analysts, pragmaticians and cognitive linguists, this book will appeal to cognitive musicologists, semioticians, historical linguists and scholars of related disciplines

Detailed temperature and angular investigation on magnetic properties of model transition-metal oxides: from flms grown on vicinal surfaces to bilayers exploiting interfacial exchange bias phenomena

Tesis Doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Física de la Materia Condensada. Fecha de Lectura: 22-03-2023La era de la información en la que nos encontramos reclama cada día más capacidad para procesar los datos, y una mayor velocidad y precisión a la hora de almacenar la información, a la vez que el tamaño y consumo energético se reducen. Estas exigencias han derivado en la búsqueda de tecnologías alternativas como la espintrónica, la cual se basa en estructuras magnéticas con las propiedades de transporte adecuadas en función de cada aplicación. Dentro de las estructuras magnéticas, aquellas que presentan transiciones metal-aislante, ofrecen la posibilidad de obtener diferentes comportamientos dentro de un mismo dispositivo en base a estímulos externos. Tener un completo conocimiento de las propiedades y efectos magnéticos de estos sistemas complejos es necesario para el desarrollo de los dispositivos espintrónicos del futuro. En este trabajo se presenta un estudio sistemático de las propiedades magnéticas de dos óxidos complejos con transiciones metal-aislante controladas mediante la temperatura. Se utilizará un sistema MOKE con resolución vectorial y control de temperatura para analizar las propiedades magnéticas de ambos sistemas. Aunque en ambos casos la transición de fase se activa con temperatura, su naturaleza magnética y efectos son completamente diferentes; por ello los resultados experimentales se han dividido en dos capítulos. En primer lugar, se han estudiado láminas delgadas de LaSrMnO con distinta composición de Sr con el objetivo de encontrar las mejores condiciones para desarrollar un sensor magnético para aplicaciones biomédicas; este estudio se engloba dentro del proyecto Europeo ByAxon, en el cual nuestro grupo participa. El detallado estudio muestra como las propiedades magnéticas, principalmente la anisotropía y la temperatura de Curie, se ven afectadas por la composición y las terrazas del sustrato; de forma que se pueda maximizar el desempeño del sensor en función de las condiciones en las que va a ser utilizado. Además, se estudia el comportamiento del LSMO durante la transición de fase, remarcando la influencia en los mecanismo de inversión de imanación. Los datos experimentales se discuten dentro de los modelos de Stoner-Wohlfarth y pinning. En segundo lugar, se analiza el acoplamiento entre una lámina de V2O3 y otra capa ferromagnética de cobalto (Co). El creciente interés en los óxidos de vanadio se debe a la utilidad de la transición metal-aislante/aislante-metal en memristores, y como punto de partida para el desarrollo de la computación neuromórfica. Además, añadir a la estructura una capa de material ferromagnético permite estudiar los efectos del acoplamiento de canje entre las dos láminas sin que haya influencia de la rugosidad de la interfaz. Este acoplamiento de canje se usa en la mayoría de dispositivos espintrónicos, aunque aun hay contradicciones sobre su origen y efectos. Nuestros resultados resaltan la importancia que tiene en el fenómeno del acoplamiento de canje la estructura de dominios y los procesos de reversión de la imanación de la capa ferromagnética. El comportamiento del campo de acoplamiento (HE ) y la temperatura de bloqueo (TB ) se explican dentro del modelo de Malozemof y de los procesos de inversión de imanación. Por tanto, estos resultados aportan información fundamental dentro del nano magnetismo que permitirá mejorar los próximos dispositivos espintrónico

Biomedical Engineering

Biomedical engineering is currently relatively wide scientific area which has been constantly bringing innovations with an objective to support and improve all areas of medicine such as therapy, diagnostics and rehabilitation. It holds a strong position also in natural and biological sciences. In the terms of application, biomedical engineering is present at almost all technical universities where some of them are targeted for the research and development in this area. The presented book brings chosen outputs and results of research and development tasks, often supported by important world or European framework programs or grant agencies. The knowledge and findings from the area of biomaterials, bioelectronics, bioinformatics, biomedical devices and tools or computer support in the processes of diagnostics and therapy are defined in a way that they bring both basic information to a reader and also specific outputs with a possible further use in research and development

Selected problems of materials science

The stamp was provided by the Methodical Council Igor Sikorsky KPI (protocol № 8 from 24.06.2021) at the request of the Academic Council of the Institute of Physics and Technology (protocol № 12 of 14.06.2021)The textbook discusses the physical foundations and practical application of functional dielectrics and simiconductors. Theories, experimental data and also specifications of basic materials, necessary for practical application, are considered. The results of modern research in the field of microelectronics and nanophysics are taken into account, with a special attention paid to the influence of the internal structure on the physical properties of materials and prospects for their use. The textbook is based on the authors' many years of experience in teaching physical materials science, intended for the students of higher educational institutions with specializations in the fields of "Applied Physics" and "Microelectronics". The book can also be used by the graduate students, engineers and researchers specializing in materials science.У навчальному посібнику розглядаються фізичні основи та практичне застосування функціональних діелектриків та напівпровідників. Розглянуто теорії, наведені експериментальні дані, а також специфікації основних матеріалів, що необхідні для практичного застосування. Беруться до уваги результати сучасних досліджень у галузі мікроелектроніки та нанофізики, при цьому особлива увага приділяється впливу внутрішньої структури на фізичні властивості матеріалів і перспективи їх використання. Навчальний посібник заснований на багаторічному досвіді авторів у викладанні курсу фізичного матеріалознавства, призначеного для студентів вищих навчальних закладів із спеціалізаціями в галузях «Прикладна фізика» та «Мікроелектроніка». Книга також може бути використана аспірантами, інженерами та дослідниками, що спеціалізуються в галузі матеріалознавства