Optical setup for torque detected electron spin resonance spectroscopy

Táto diplomová práca sa venuje vylepšeniu spektroskopu Torzne Detegovanej Elektrónovej Spinovej Rezonancie (TDESR) výmenou aktuálnej kapacitnej detekcie výchylky ohybného ramienka za optické metódy. Práca popisuje základy Elektrónovej Spinovej Rezonančnej (ESR) spektroskopie s dôrazom na TDESR a tému magnetizmu jednomolekulových magnetov. Následne je vysvetlená detekcia výchylky ramienka pomocou odrazu laserového zväzku a interferometrie. Všetky kroky nutné k skonštruovaniu spektrometra a jeho uvedenia do prevádzky sú podrobne popísané. Pomocou detekcie odrazu laserového zväzku sme úspešne získali vysoko kvalitné TDESR spektrá kryštálu jednomolekulového magnetu Fe4. Týmto meraním sme dokázali vhodnosť použitia tejto metódy a jej výraznú prevahu nad pôvodnou kapacitnou detekciou, najmä v oblasti kvality, rozlíšenia a rýchlosti. Zároveň sme na ďaľšie vylepšenie TDESR spektrometra navrhli a zostrojili zostavu využívajúcu na detekciu výchylky interferometer.This thesis has been devoted to the improvement of a Torque Detected Electron Spin Resonance (TDESR) spectrometer by replacing the current capacitive detection of cantilever bending with optical methods. The thesis covers the basics of Electron Spin Resonance (ESR) spectrometry with the focus on TDESR and the field of single molecule magnetism. Laser beam deflection and interferometric detection methods are explained. The design of the TDESR spectrometer and its performance is shown on successfully obtained high quality TDESR spectra of an Fe4 single molecule magnet single crystal. Obtained results prove the feasibility of implemented detection method and its superiority with respect to the previously used capacitive method in terms of quality, resolution and speed. To further improve the TDESR setup, we have designed and assembled a system which uses an interferometer for detection of cantilever bending.

Characteristics of the conjugative transfer system of the IncM plasmid pCTX-M3 and identification of its putative regulators

Plasmid conjugative transfer systems comprise type IV secretion systems (T4SS) coupled to DNA processing and replication. The T4SSs are divided into two phylogenetic subfamilies, namely, IVA and IVB or based on the phylogeny of the VirB4 ATPase into eight groups. The conjugation system of the IncM group plasmid pCTX-M3, from Citrobacter freundii, is classified in the IVB subfamily and in the MPFI group, as are the conjugation systems of IncI1 group plasmids. Although the majority of the conjugative genes of the IncM and IncI1 plasmids display conserved synteny, there are several differences. Here, we present a deletion analysis of 27 genes in the conjugative transfer regions of pCTX-M3. Notably, the deletion of either of two genes dispensable for conjugative transfer, namely, orf35 and orf36, resulted in an increased plasmid mobilization efficiency. Transcriptional analysis of the orf35 and orf36 deletion mutants suggested an involvement of these genes in regulating the expression of conjugative transfer genes. We also revised the host range of the pCTX-M3 replicon by finding that this replicon is unable to support replication in Agrobacterium tumefaciens, Ralstonia eutropha and Pseudomonas putida although its conjugation system is capable of introducing plasmids bearing oriTpCTX-M3 into these bacteria, which are representatives of Alpha-, Beta- and Gammaproteobacteria, respectively. Thus, the conjugative transfer system of pCTX-M3 has a much broader host range than does its replicon. Importance Horizontal gene transfer is responsible for rapid changes in bacterial genomes, and the conjugative transfer of plasmids has a great impact on the plasticity of bacteria. Here, we present a deletion analysis of the conjugative transfer system genes of the pCTX-M3 plasmid of the IncM group, which is responsible for the dissemination of antibiotic resistance genes in Enterobacteriaceae. We found that deletion of the orf35 or orf36 genes, which are dispensable for conjugative transfer, increased the plasmid mobilization efficiency. RT-qPCR analysis suggested the involvement of orf35 and orf36 in regulating the expression of transfer genes. We also revised the host range of pCTX-M3 by showing that its conjugative transfer system has a much broader host range than does its replicon

Optimization of the radiofrequency atomic source for deposition of GaN

Táto bakalárska práca sa zaoberá sprevádzkovaním a optimalizáciou vysokofrekvenčného atomárneho disociačného zdroja dusíka pre depozíciu GaN. Teoretická časť sa zaoberá atomárnymi zdrojmi, rastom ultratenkých vrstiev a problematikou vysokofrekvenčných obvodov, s dôrazom na ich návrh pomocou Smithových diagramov. Taktiež pojednáva o metódach prípravy GaN ultratenkých vrstiev a nanostĺpcov. V experimentálnej časti je popísaný návrh a samotná realizácia rôznych kongurácii vyrovnávacej jednotky impedancie pre atomárny zdroj dusíku. Pomocou tejto vyrovnávacej jednotky bolo dosiahnuté zapálenie dusíkovej plazmy a bolo analyzované jej spektrum. Následne je popísaný návrh a realizácia ovládania vyrovnávacej jednotky pomocou krokových motorov.This thesis is focused on construction and optimization of radiofrequency atomic dissociation source of atomic nitrogen for depostion of GaN. The theoretical part deals with atomic sources, growth of ultrathin layers and the issue of radiofrequency circuits, with emphasis on their design using Smith chart. Methods for synthesis of GaN ultrathin layers and deposition are also discussed. In the experimental part, design and realization of various congurations of the impedance matching network is described. Using the impedance matching network a nitrogen plasma discharge was successfuly created and its spectrum was analysed. Afterwards, design and realization of a stepper motor control for the impedance matching network is described.

A 14-channel 7 GHz VCO-based EPR-on-a-chip sensor with rapid scan capabilities

This paper presents a VCO-based EPR-on-a-chip (EPRoC) sensor for portable, battery-operated electron paramagnetic resonance (EPR) spectrometers. The proposed chip contains an array of 14 injection-locked VCOs as the sensing element for an improved sensitive volume and phase noise performance. By cointegrating a high-bandwidth PLL, the presented design allows for continuous-wave and rapid-scan EPR experiments with a minimum number of external components. The active loop filter introduces an assisted replica charge pump that mitigates the slewing requirements on the loop-filter amplifier. The measured spin sensitivity of 2×10 9 spins/Hz−−−√ together with the large active volume of 210 nl lead to an 8-fold improvement in concentration sensitivity compared to the state-of-the-art in EPRoC detectors

On the modeling of amplitude-sensitive electron spin resonance (ESR) detection using voltage-controlled oscillator (VCO)-based ESR-on-a-chip detectors

In this paper, we present an in-depth analysis of a voltage-controlled oscillator (VCO)-based sensing method for electron spin resonance (ESR) spectroscopy, which greatly simplifies the experimental setup compared to conventional detection schemes. In contrast to our previous oscillator-based ESR detectors, where the ESR signal was encoded in the oscillation frequency, in the amplitude-sensitive method, the ESR signal is sensed as a change of the oscillation amplitude of the VCO. Therefore, using VCO architecture with a built-in amplitude demodulation scheme, the experimental setup reduces to a single permanent magnet in combination with a few inexpensive electronic components. We present a theoretical analysis of the achievable limit of detection, which uses perturbation-theory-based VCO modeling for the signal and applies a stochastic averaging approach to obtain a closed-form expression for the noise floor. Additionally, the paper also introduces a numerical model suitable for simulating oscillator-based ESR experiments in a conventional circuit simulator environment. This model can be used to optimize sensor performance early on in the design phase. Finally, all presented models are verified against measured results from a prototype VCO operating at 14 GHz inside a 0.5 T magnetic field

Low-dose radiotherapy for greater trochanteric pain syndrome-a single-centre analysis.

PURPOSE To determine predictive factors associated with a good response (GR) to and efficacy of low-dose radiotherapy (LDRT) in patients with greater trochanteric pain syndrome (GTPS). METHODS Patients with GTPS were irradiated on a linear accelerator with 0.5-1.0 Gy per fraction to a total dose of 3.0-4.0 Gy per series. The endpoint was subjective good response (GR) to treatment 2 months after completion of the last LDRT series, defined as complete pain relief or marked improvement assessed using the von Pannewitz score. A positive response to steroid injection (SI) was defined as pain relief of at least 7 days. Patient and treatment-related characteristics were evaluated with respect to LDRT outcomes. RESULTS Outcomes were assessed for 71 peritrochanteric spaces (PTSs; 65 patients, 48 females, with mean age of 63 [44-91] years). Prior SI had been given to 55 (77%) PTSs and 40 PTSs received two series of LDRT. Two months after completion of LDRT, GR was reported in 42 PTSs (59%). Two series of LDRT provided a significantly higher rate of GR than one series (72.5 vs. 42% PTSs, p = 0.015). Temporary pain relief after prior SI predicted GR to LDRT compared with PTSs which had not responded to SI (73 vs. 28% PTSs, p = 0.001). A regional structural abnormality, present in 34 PTSs (48%), was associated with a reduction of GR to LDRT (44 vs. 73% PTSs, p = 0.017). CONCLUSION LDRT is an effective treatment for GTPS. Administration of two LDRT series, prior response to SI, and absence of structural abnormalities may predict significantly better treatment outcomes

Latent human traits in the language of social media: An open-vocabulary approach

Over the past century, personality theory and research has successfully identified core sets of characteristics that consistently describe and explain fundamental differences in the way people think, feel and behave. Such characteristics were derived through theory, dictionary analyses, and survey research using explicit self-reports. The availability of social media data spanning millions of users now makes it possible to automatically derive characteristics from behavioral data-language use-at large scale. Taking advantage of linguistic information available through Facebook, we study the process of inferring a new set of potential human traits based on unprompted language use. We subject these new traits to a comprehensive set of evaluations and compare them with a popular five factor model of personality. We find that our language-based trait construct is often more generalizable in that it often predicts non-questionnaire-based outcomes better than questionnaire-based traits (e.g. entities someone likes, income and intelligence quotient), while the factors remain nearly as stable as traditional factors. Our approach suggests a value in new constructs of personality derived from everyday human language use

Photolytic and Reductive Activations of 2‐Arsaethynolate in a Uranium‐Triamidoamine Complex: Decarbonylative Arsenic Group‐Transfer Reactions and Trapping of a Highly Bent and Reduced Form

Little is known about the chemistry of the 2-arsaethynolate anion, but to date it has exclusively undergone fragmentation reactions when reduced. Herein, we report the synthesis of [U(Tren(TIPS))(OCAs)] (2, Tren(TIPS)=N(CH(2)CH(2)NSiiPr(3))(3)), which is the first isolable actinide-2-arsaethynolate linkage. UV-photolysis of 2 results in decarbonylation, but the putative [U(Tren(TIPS))(As)] product was not isolated and instead only [{U(Tren(TIPS))}(2)(mu-eta(2):eta(2)-As2H2)] (3) was formed. In contrast, reduction of 2 with [U(Tren(TIPS))] gave the mixed-valence arsenido [{U(Tren(TIPS))}(2)(mu-As)] (4) in very low yield. Complex 4 is unstable which precluded full characterisation, but these photolytic and reductive reactions testify to the tendency of 2-arsaethynolate to fragment with CO release and As transfer. However, addition of 2 to an electride mixture of potassium-graphite and 2,2,2-cryptand gives [{U(Tren(TIPS))}(2){mu-eta(2)(OAs):eta(2)(CAs)-OCAs}][K(2,2,2-cryptand)] (5). The coordination mode of the trapped 2-arsaethynolate in 5 is unique, and derives from a new highly reduced and bent form of this ligand with the most acute O-C-As angle in any complex to date (O-C-As angle approximate to 128 degrees). The trapping rather than fragmentation of this highly reduced O-C-As unit is unprecedented, and quantum chemical calculations reveal that reduction confers donor-acceptor character to the O-C-As unit