Individual Professional Practice in the Company

Táto bakalárska práca sa zaoberá popisom činností a informačných technológií, s ktorými som sa stretol v priebehu absolvovania individuálnej odbornej praxe vo firme XEVOS Solutions s.r.o. Práca obsahuje popis zamerania firmy, v ktorej som vykonával prax, moje pracovné zaradenie a zadané úlohy, o ktorých následne pojednávam v jednotlivých kapitolách bakalárskej práce. Jedná sa hlavne o mapovanie počítačovej siete, tvorbu PPC reklám, konfiguráciu IP telefónov a zabezpečenie počítačovej siete pomocou RADIUS. V závere je zhrnutý prínos absolvovania individuálnej odbornej praxe a vyhodnotenie využitia znalostí, ktoré som nadobudol počas štúdia a tých, ktoré mi naopak chýbali.This bachelor thesis represents the descriptions of actions and information technologies which I came across during my individual professional practice in the company XEVOS Solutions s.r.o. This thesis contains the description of the focus of the company, my work position and tasks which I have been given - I write about these in following chapters. The areas of focus are mainly the following: network scanning, the making of PPC advertisements, configuration of IP telephones and securing of the network via RADIUS. In the end I have summarized the assets of my individual professional practice in the company and evaluation of the use of knowledge which I do have from studies and also of such knowledge which I did not have.440 - Katedra telekomunikační technikyvýborn

Solution of Optical Fiber Ends for VLC Applications

Cieľom tejto práce je vytvoriť optický vláknový vysielač v softvérovej aplikácii LightTools a nájsť najvhodnejšie pozície a zakončenia vláken v počte 7 a 19 s ohľadom na rozloženie optickej intenzity na 1/8 gule s 3 dB kolísaním optického výkonu. Následný cieľ po simuláciách v danom softvéri je vytvoriť skutočný vláknový vysielač s konfiguráciou zhodnou s najlepšími výsledkami dosiahnutými pri simulácii. Po skonštruovaní a nameraní výsledkov vláknového vysielača sa porovnajú simulované a reálne namerané výsledky. V úvode práce je vysvetlená problematika optických sietí. Ide o zhrnutie histórie štúdie svetla, optických veličín, optických vláknových a bezvláknových sietí a komponentov, ktoré sú v nich používané a tiež bezpečnosť optického žiarenia. Nasleduje postup simulácie a merania.The objective of this diploma thesis is to create an optical fiber transmitter in the software aplication LightTools and to find the most suitable mesh positions and terminations in numbers 7 and 19 considering the distribution of optical intensity on 1/8 of the sphere with 3 dB fluctuation of optical power. The following goal after the simulation in this software is to create a real fiber transmitter with a configuration that matches the most efficient achieved results in the simulation. After constructing and measuring the fiber transmitter results, the simulated and real measured results are compared. At the beginning of the work the relations of optical networks are explained. It is a summary of the study of light, optical quantities, optical fiber and fiber-free networks and components used in them and also optical radiation safety. Following is the simulation and measurement procedure.440 - Katedra telekomunikační technikyvelmi dobř

Giant spin-orbit effects on H-1 and C-13 NMR shifts for uranium(VI) complexes revisited: role of the exchange-correlation response kernel, bonding analyses, and new predictions

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.Previous relativistic quantum-chemical predictions of unusually large H-1 and C-13 NMR chemical shifts for ligand atoms directly bonded to a diamagnetic uranium(VI) center (P. Hrobarik, V. Hrobarikova, A. H. Greif and M. Kaupp, Angew. Chem., Int. Ed., 2012, 51, 10884) have been revisited by two- and four-component relativistic density functional methods. In particular, the effect of the exchange-correlation response kernel, which had been missing in the previously used two-component version of the Amsterdam Density Functional program, has been examined. Kernel contributions are large for cases with large spin-orbit (SO) contributions to the NMR shifts and may amount to up to similar to 30% of the total shifts, which means more than a 50 ppm difference for the metal-bonded carbon shifts in some extreme cases. Previous calculations with a PBE-40HF functional had provided overall reasonable predictions, due to cancellation of errors between the missing kernel contributions and the enhanced exact-exchange (EXX) admixture of 40%. In the presence of an exchange-correlation kernel, functionals with lower EXX admixtures give already good agreement with experiments, and the PBE0 functional provides reasonable predictive quality. Most importantly, the revised approach still predicts unprecedented giant H-1 NMR shifts between +30 ppm and more than +200 ppm for uranium(VI) hydride species. We also predict uranium-bonded C-13 NMR shifts for some synthetically known organometallic U(VI) complexes, for which no corresponding signals have been detected to date. In several cases, the experimental lack of these signals may be attributed to unexpected spectral regions in which some of the C-13 NMR shifts can appear, sometimes beyond the usual measurement area. An extremely large uranium-bonded C-13 shift above 550 ppm, near the upper end of the diamagnetic C-13 shift range, is predicted for a known pincer carbene complex. Bonding analyses allow in particular the magnitude of the SO shifts, and of their dependence on the functional, on the ligand position in the complex, and on the overall electronic structure to be better appreciated, and improved confidence ranges for predicted shifts have been obtained

Paramagnetic NMR of phenolic oxime copper complexes : a joint experimental and density functional study

This work was supported by EaStCHEM and the School of Chemistry. The authors would like to thank the EPSRC for computational support through the Collaborative Computational Project on NMR Crystallography (CCP-NC), via EP/M022501/1 and EP/J501542/1. SEA would like to thank the Royal Society and Wolfson Foundation for a merit award. Work at the TU Berlin has been carried out within the EU Marie-Curie Initial Training Network “pNMR”.1H and 13C pNMR properties of bis(salicylaldoximato)copper(II) were studied in the solid state using magic-angle-spinning NMR spectroscopy and, for the isolated complex and selected oligomers, using density-functional theory at the PBE0-1/3 // PBE0-D3 level. Large paramagnetic shifts are observed, up to δ(1H) = 272 ppm and δ(13C) = 1006 ppm (at 298 K), which are rationalised through spin delocalisation from the metal onto the organic ligand and the resulting contact shifts arising from hyperfine coupling. The observed shift ranges are best reproduced computationally using exchange-correlation functionals with a high fraction of exact exchange (such as PBE0-1/3). Through a combination of experimental techniques and first-principles computation, a near-complete assignment of the observed signals is possible. Intermolecular effects on the pNMR shifts, modelled computationally in the dimers and trimers through effective decoupling between the local spins via A-tensor and total spin rescaling in the pNMR expression, are indicated to be small. Addition of electron-donating substituents and benzannelation of the organic ligand is predicted computationally to induce notable changes in the NMR signal pattern, suggesting that pNMR spectroscopy can be a sensitive probe for the spin distribution in paramagnetic phenolic oxime copper complexes.PostprintPeer reviewe

Ein neutrales 1,4‐Diborabenzol als π‐Ligand in Actinoidkomplexen

Die π‐Koordination von Aren‐ und anionischen Heteroarenliganden ist ein allgegenwärtiges Strukturmotiv in der metallorganischen Chemie der d‐ und f‐Block‐Elemente. Im Gegensatz dazu sind vergleichbare π‐Wechselwirkungen neutraler Heteroarene, darunter auch solche neutraler, aromatischer Borheterocyclen, für den f‐Block weit weniger verbreitet, was z. T. mit einer geringeren Effektivität der Metall‐zu‐Ligand‐Rückbindung in Zusammenhang gebracht werden kann. Für die Actinoide sind π‐Komplexe mit neutralen Heteroarenliganden sogar gänzlich unbekannt. Durch Ausnutzung der außergewöhnlichen π‐Donorstärke eines 1,4‐Diborabenzols ist es uns nun gelungen, eine Reihe stabiler π‐Halbsandwichkomplexe des Thoriums(IV) und des Urans(IV) über einen erstaunlich einfachen Zugang zu generieren: Umsetzung eines 1,4‐Diborabenzols mit ThCl4(dme)2 bzw. UCl4 in Gegenwart einer Lewis‐Base. Hierdurch konnten die ersten Beispiele für Actinoidkomplexe mit einem neutralen Borheterocyclus als Sandwich‐artigem Liganden erhalten werden. Laut experimentellen und theoretischen Studien ist die starke Actinoid‐Heteroaren‐Wechselwirkung in diesen Molekülen im Wesentlichen von elektrostatischer Natur. Der kovalente Hauptbeitrag wird hingegen von der Ligand‐zu‐Metall‐π‐Wechselwirkung geleistet, während π/δ‐Rückbindungsanteile kaum eine Rolle spielen.EC/H2020/669054/EU/Boron-boron multiple bonding/multiBBDFG, 390540038, EXC 2008: Unifying Systems in Catalysis "UniSysCat

Stable Actinide π Complexes of a Neutral 1,4-Diborabenzene

The π coordination of arene and anionic heteroarene ligands is a ubiquitous bonding motif in the organometallic chemistry of d-block and f-block elements. By contrast, related π interactions of neutral heteroarenes including neutral bora-π-aromatics are less prevalent particularly for the f-block, due to less effective metal-to-ligand backbonding. In fact, π complexes with neutral heteroarene ligands are essentially unknown for the actinides. We have now overcome these limitations by exploiting the exceptionally strong π donor capabilities of a neutral 1,4-diborabenzene. A series of remarkably robust, π-coordinated thorium(IV) and uranium(IV) half-sandwich complexes were synthesized by simply combining the bora-π-aromatic with ThCl4(dme)2 or UCl4, representing the first examples of actinide complexes with a neutral boracycle as sandwich-type ligand. Experimental and computational studies showed that the strong actinide–heteroarene interactions are predominately electrostatic in nature with distinct ligand-to-metal π donation and without significant π/δ backbonding contributions.DFG, 390540038, EXC 2008: Unifying Systems in Catalysis "UniSysCat"EC/H2020/669054/EU/Boron-boron multiple bonding/multiBBEC/H2020/752285/EU/Towards Highly-Efficient Two-Photon Absorbing Sensitizers within a Confined Chromophore Space:From Computer-Aided Design to New Concepts and Applications/TWOSEN

Ein neutrales 1,4‐Diborabenzol als π\pi‐Ligand in Actinoidkomplexen

Die $\pi$-Koordination von Aren- und anionischen Heteroarenliganden ist ein allgegenwärtiges Strukturmotiv in der metallorganischen Chemie der d- und f-Block-Elemente. Im Gegensatz dazu sind vergleichbare $\pi$-Wechselwirkungen neutraler Heteroarene, darunter auch solche neutraler, aromatischer Borheterocyclen, für den f-Block weit weniger verbreitet, was z. T. mit einer geringeren Effektivität der Metall-zu-Ligand-Rückbindung in Zusammenhang gebracht werden kann. Für die Actinoide sind π-Komplexe mit neutralen Heteroarenliganden sogar gänzlich unbekannt. Durch Ausnutzung der außergewöhnlichen $\pi$-Donorstärke eines 1,4-Diborabenzols ist es uns nun gelungen, eine Reihe stabiler π-Halbsandwichkomplexe des Thoriums(IV) und des Urans(IV) über einen erstaunlich einfachen Zugang zu generieren: Umsetzung eines 1,4-Diborabenzols mit ThCl$_{4}$(dme)$_{2}$ bzw. UCl$_{4}$ in Gegenwart einer Lewis-Base. Hierdurch konnten die ersten Beispiele für Actinoidkomplexe mit einem neutralen Borheterocyclus als Sandwich-artigem Liganden erhalten werden. Laut experimentellen und theoretischen Studien ist die starke Actinoid-Heteroaren-Wechselwirkung in diesen Molekülen im Wesentlichen von elektrostatischer Natur. Der kovalente Hauptbeitrag wird hingegen von der Ligand-zu-Metall-$\pi$-Wechselwirkung geleistet, während $\pi$/δ-Rückbindungsanteile kaum eine Rolle spielen

Mechanism of the cooperative Si-H bond activation at Ru-S bonds

The nature of the hydrosilane activation mediated by ruthenium(II) thiolate complexes of type [(R3P)-Ru(SDmp)](+)[BAr4F]- is elucidated by an in-depth experimental and theoretical study. The combination of various ruthenium(II) thiolate complexes and tertiary hydrosilanes under variation of the phosphine ligand and the substitution pattern at the silicon atom is investigated, providing detailed insight into the activation mode. The mechanism of action involves reversible heterolytic splitting of the Si-H bond across the polar Ru-S bond without changing the oxidation state of the metal, generating a ruthenium(II) hydride and sulfur-stabilized silicon cations, i.e. metallasilylsulfonium ions. These stable yet highly reactive adducts, which serve as potent silicon electrophiles in various catalytic transformations, are fully characterized by systematic multinuclear NMR spectroscopy. The structural assignment is further verified by successful isolation and crystallographic characterization of these key intermediates. Quantum-chemical analyses of diverse bonding scenarios are in excellent agreement with the experimental findings. Moreover, the calculations reveal that formation of the hydrosilane adducts proceeds via barrierless electrophilic activation of the hydrosilane by sterically controlled eta(1) (end-on) or eta(2) (side-on) coordination of the Si-H bond to the Lewis acidic metal center, followed by heterolytic cleavage of the Si-H bond through a concerted four-membered transition state. The Ru-S bond remains virtually intact during the Si-H bond activation event and also preserves appreciable bonding character in the hydrosilane adducts. The overall Si-H bond activation process is exergonic with Delta G(r)(0) ranging from -20 to -40 kJ mol(-1), proceeding instantly already at low temperatures.DFG, EXC 314, Unifying Concepts in CatalysisDFG, GRK 1143: Komplexe chemische Systeme, Design, Entwicklung und Anwendunge