This diploma thesis deals with the development and validation of an analytical method using high performance liquid chromatography method with fluorescence detection for the simultaneous determination of aflatoxins and ochratoxin A in herbal and fruit tea. The theoretical part describes the most common groups of mycotoxins and the most important methods for their determination in food. The great attention is devoted to HPLC method and the overview of the derivatization techniques for aflatoxins B1 and G1 fluorescence response enhancement. The practical part of this study focuses on the optimization of sample extraction and purification, the settings of the instrumental analysis and the photochemical reactor assembly. The thesis also involves the determination of the basic performance characteristics for the successful method validation.

This diploma thesis deals with sorption properties of biochar produced from wood biomass treated with concentrated hydrochloric acid and activated carbon with respect to the triazine pesticide propazine. Although pesticides are widely used in both agriculture and the private sector worldwide, they pose a significant risk to ecosystems and human health. Propazine belongs to the group of chlorinated triazine herbicides, which pose a risk mainly as endocrine disruptors. The sorption of organic pollutants using pyrogenic carbonaceous materials promises an efficient and economically affordable solution, which has recently received increasing attention from the scientific community. In this work, we used isotherms to describe the equilibria of propazine sorption to given sorbents during vial experiments. Analysis of the propazine content in the model water solutions after reaching equilibrium was performed using high-performance liquid chromatography with mass detection.

OBJECTIVES: To assess the viability of using high-strength polymers as framework materials for full arch implant-supported fixed prostheses, veneered with full-coverage restorations of different materials. The machinability, mechanical performance, and damping capacity of the polymer-based materials was of interest. METHODS: The two framework polymers – a polyetheretherketone (JUVORA™ Dental Disk, Juvora) (PEEK) and a fiber-reinforced composite (TRINIA™ CAD/CAM Disk, Trinia) (TR) – were characterized with Fourier-Transform Infrared (FTIR) Spectroscopy and energy-dispersive X-ray spectroscopy (EDS). Phase 1 consisted of a machinability study involving the merlon fracture test, which tested the milling success of PEEK and TR at 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, and 0.5 mm. 10 four-walled merlons of each thickness and material were milled out of CAD/CAM Disks (n = 100 merlons, n = 400 walls) using a 5-axis milling machine, inLab MC X5 (Dentsply Sirona, Germany). Milling success rate, fracture height, fracture length, fracture position, fracture direction, and chipping factor were assessed. In phase 2, 20 bars of dimensions 3.3 mm x 10 mm x 40 mm were milled from each of the two framework materials, PEEK and TR, and two veneer materials – a composite resin material (Shofu Disk HC, Shofu, Inc., Kyoto, Japan) (COM), and a high-translucency 3 mol% yttria-stabilized tetragonal zirconia polycrystal material (Cercon® ht, Dentsply Sirona, Bensheim, Germany) (ZR). Framework and veneer bars were bonded to each other in 4 framework/veneer combinations of 10 bilayers each: PEEK/COM (PCB), PEEK/ZR (PZB), TR/COM (TCB), and TR/ZR (TZB). Bilayer bars were loaded to failure in a 3-point bending test. Failure load, biaxial flexural strength, failure pattern and failure mode were documented. In Phase 3, 10 full arch fixed implant-supported frameworks were designed and fabricated in TR material over an epoxy resin model containing 4 implants in the second premolar and lateral incisor positions. 5 frameworks were veneered by COM in the canine to first molar region, while the other 5 were veneered by ZR. Four loading sites were designated per prosthesis in the occlusal surface of the first molars and the first premolars. Prostheses were loaded at the four occlusal sites in 5 cycles of loading and unloading. The damping capacity of the prostheses was calculated based on energy absorbed during loading and unloading. Displacement and permanent deformation values of the prosthesis structures were obtained from the load-displacement data. Prostheses were loaded to failure at the same sites, and failure load and failure mode were observed. RESULTS: The minimum machined thickness of PEEK and TR was 0.5 mm. There was no significant difference between milling success of PEEK and TR, but cumulative success rate was slightly superior in PEEK. PEEK exhibited a ductile response to machining damage, while TR showed a more brittle response. Chipping factor of PEEK was higher than TR eightfold, meaning TR showed an improved marginal integrity at 0.5 mm. Both materials showed concerning signs of machining damage with the milling parameters and tools used in this study. Bilayer bars with a TR framework withstood significantly higher loads at failure compared to bilayers with a PEEK framework. Bilayer bars with a ZR veneer withstood significantly higher loads at failure compared to bilayers with a COM veneer. The biaxial flexural strength of the four framework/veneer combinations could not be compared due to the occurrence of delamination in 3 of the 4 groups. The PZB group was the only group with fracture of both the veneer and framework without any delamination and exhibited a mean biaxial flexural strength of 46.15 ± 5.76 MPa. None of the bilayer bars with a TR framework exhibited framework fracture. In delaminated specimens, bilayer bars with a TR framework exhibited mixed adhesive-cohesive failure on both layers, while bilayer bars with a PEEK framework exhibited purely adhesive failure on the PEEK-cement interface. Full arch implant prostheses with a TR framework demonstrated elastic hysteresis in continuous cycles of cyclic loading, which is evidence of viscoelastic damping. Significantly higher energy absorption was observed in prostheses veneered with COM compared to ZR. Energy absorption decreased with increasing cycles of loading-unloading. Significantly higher maximum displacement was observed in prostheses veneered with COM compared to ZR, and in cantilever support compared to bounded support. Maximum displacement was inversely related to the thickness of the veneer and framework materials. Permanent deformation of the prosthesis was negligible after 10 cycles. The failure pattern of all prostheses presented as fracture in the veneer only and partial delamination of the veneer with mixed adhesive-cohesive failure mode. The mean failure load at ZR-veneered bounded sites was significantly higher than that of COM-veneered bounded sites. The mean failure load at bounded loading sites was significantly higher than that of cantilever loading sites. ZR-veneered prostheses demonstrated failure load values above 1000 N at all sites. CONCLUSION: The merlon fracture test is well-complemented by several quantitative and qualitative measures to assess the machinability of materials. Optimized tools and parameters for milling PEEK and TR should be investigated. Full arch implant prostheses with TR framework and ZR veneer are a viable option for fixed implant rehabilitation demonstrating damping capacity, adequate failure load values, and easy repairability.

This thesis includes NMR studies of free base meso-tetra(otolyl) porphyrin (TTP) and meso -tetraphenylporphyrin (TPP) and their dications protonated by trifluoroacetic acid (TFA). The chemical shift changes of the -NH resonance are very unusual and have never been reported. At the beginning of the titration, the N-H resonances broaden considerably but do not shift; when the ratio of [TFA]/[TTP] or [TFA]/[TPPf are over 2, the N-H resonances shift markedly to lower field by as much as 1.6 ppm. At acid levels well above the equivalence point, the NH resonances moves back to higher field. Moreover upon protonation the NH line of TTP becomes a complex multiplet which changes as a function of [TFA]/[TTP]. The NH line of TPP remains a singlet at all acid levels. We also report here a way of isolating atropisomers of mesotetra( o -tolyl)porphyrin through HPLC by using an analytical C-18 bond pack reverse phase column eluted by a 1 %THF + 99%Me0H solvent combination. A preliminary study by HPLC was also carried out on ZnTTP(II) with aliquots of 2,6-dimethylpyridine, and the retention time of the separation decreased markedly, but this study needs to be repeated and improved. TTP and TPP dications at two different acid levels were studied by VT-NMR, and the downfield shift of -NH resonance of TTP dications was more pronounced at higher temperatures than those of TPP dications.

This diploma thesis contains detailed design of high-performance cluster, primarely focused for parallel computing in Octave application. Each of component of this cluster is described along with instructions for installation and configuration. Cluster is based on GNU/Linux operating system and Message Parsing Interface. Design alllows implementation of this cluster in computers of schoolroom with active lessons.

Quantum-mechanical effects play a major role in the performance of modern electronic devices. In order to predict the behavior of novel devices, quantum effects are often included using Non-Equilibrium Green's Function (NEGF) methods in atomistic device representations. These quantum effects may include realistic inelastic scattering caused by device impurities and phonons. With the inclusion of realistic physical phenomena, the computational load of predictive simulations increases greatly, and a manageable basis through low-rank approximations is desired.<br><br>In this work, low-rank approximations are used to reduce the computational load of atomistic simulations. The benefits of basis reductions on simulation time and peak memory are assessed.<br>The low-rank approximation method is then extended to include more realistic physical effects than those modeled today, including exact calculations of scattering phenomena. The inclusion of these exact calculations are then contrasted to current methods and approximations.

Warum können Feuerwehrleute, Polizisten, Rettungsassistenten oder Formel-1-Teams auch in schwierigen Einsatzsituationen immer wieder beeindruckende Erfolge vorweisen und Spitzenleistungen erbringen? Der Artikel stellt wichtige leistungsbeeinflussende Faktoren dieser Organisationen vor und skizziert exemplarisch, wie Führungskräfte von den Erfahrungen dieser Teams profitieren können.

Most commercially available valves are able to produce a large flow rate or a fast response, but are incapable of producing both simultaneously. Commercially available valves that can achieve both are expensive as they require multiple stages of actuation and piloting pressures to deliver large flow rates quickly, preventing them from being broadly used in fluid power applications. This work investigates the design of an Energy Coupling Actuated Valve (ECAV) that is capable of solving this trade-off between large flow and fast switching times through the use of an innovative, high performance actuation system. The ECAV is a new development in valve technology in the area of hydraulic, high speed, proportional and digital on/off valves. High speed actuation is produced through the intermittent coupling of a kinetic energy source with a translational poppet or spool. This coupling process occurs through the use of magnetorheological fluid and a controlled magnetic flux through the fluid in the energy coupler. The ECAV has several design advantages including proportional force control and a large (7mm) stroke capability. Early results predict a nominal flow rate of 100 L/min at a 5 bar pressure drop can be achieved with a 3 ms on/off response time.

This diploma thesis deals with the determination of glucosinolates in plant material by capillary electrophoresis and high performance liquid chromatography. The chemical structure, biosynthesis, degradation, and also biological effects of glucosinolates are described. One part of this work also deals with the methods, which glucosinolates in plant materials were determined by. The experimental part describes the separation of intact glucosinolates by capillary electrophoresis and high performance liquid chromatography. Two plant materials were available for the determination of glucosinolates, namely lyophilized rapeseed leaves and broccoli juice. Micellar electrokinetic chromatography using a cationic surfactant was used to determine intact glucosinolates by capillary electrophoresis. After finding the optimal conditions for the separation of intact glucosinolates, it was found that it is impossible to determine these substances in plant samples. The reason was interference from the matrix, which interfered with this determination. While using high performance liquid chromatography under optimal conditions, some of the intact glucosinolates were identified in a rapeseed plant sample. Furthermore, the calibration dependencies of individual glucosinolates were obtained and the recovery and...

Neben der Umwandlung von Energie gehören deren Transport und Speicherung zu den wichtigsten ingenieurwissenschaftlichen Problemfeldern. Die optimale Ausnutzung beider Mechanismen könnte entscheidend zur Überwindung der häufig existierenden örtlichen und zeitlichen Diskrepanz zwischen Notwendigkeit und Verfügbarkeit energetischer Ressourcen beitragen. Dies steht im Mittelpunkt von Forschungsarbeiten am Graduiertenkolleg Hochleistungsbauteilkühlung und der gleichnamigen Juniorprofessur am Institut für Thermodynamik und Technische Gebäudeausrüstung der TU Dresden. Sie beschäftigen sich zum einen mit der Optimierung von Wärmetransportmechanismen vor allem zur Kühlung und zum anderen mit der Speicherung stoffgebundener Energie. Die notwendigen strömungs- und wärmetechnischen Untersuchungen sind sowohl auf experimentellem als auch auf numerischem Gebiet angesiedelt / Alongside energy conversion, the transfer and storage of energy represent two of the most important research areas in the field of engineering sciences. The optimal use of both mechanisms could make a significant contribution to overcoming the frequently encountered local and temporal discrepancy between demand and the availability of energy resources. The research within the graduate college on high-performance cooling at the Institut für Thermodynamik und Technische Gebäudeausrüstung of TU Dresden, together with that of a corresponding junior professorship, is focussed on the optimisation of heat transfer processes for cooling purposes and for the storage of thermal energy. The necessary investigations of flow and heat transfer are based on experimental as well as numerical methods.