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31.
Spectroscopic investigation of oxygen vacancies in CeO[sub]2 : dissertation
Thanveer Thajudheen, 2021, doctoral dissertation

Abstract: A unique material, ceria (CeO2), which is widely applied in automobile exhaust catalysts, is functional due to presence of defects in its crystal structure. Furthermore, the structural defects dictate electrical and chemical properties of ceria. The creation of intrinsic oxygen vacancies in ceria is responsible for oxygen-ion conductivity in solid oxide fuel cells. This unfolds the keen interest in ceria defects. Using the analytical technique cathodoluminescence spectroscopy (CLS) we can characterize ceria for its band gap and the defect states within the band gap. Since CLS has a high spatial resolution, high sensitivity to low concentration of defects and ability to obtain depth resolved information it is an obvious technique of choice. The first part of the thesis is an introduction to the topic and description of the experimental techniques. Importance of ceria as a multifaceted material finding applications in areas spanning from energy production and conversion to biomedical applications is detailed. CLS as a tool to understand defect-related optical properties and advancement in the CL detection systems are discussed. To study the relationship between local structure and its impact on CL emission spectra, an X-ray absorption spectroscopy techniques were used. The X-ray absorption near edge structure (XANES) and the Extended x-ray absorption fine structure (EXAFS) techniques are summarized. The second part discusses CL emission from ceria. Initially, CL emission from reduced ceria and its dependence on oxygen vacancy concentration are presented. The origin of emission was attributed to different configurations of the oxygen vacancies and polarons. The recent F center description in ceria was adopted here. The intriguing observation of CL emission quenching as a function of oxygen vacancy concentration was explained on the basis of a relative change in population of F centers in ceria. This demonstrated the relevance of local structure for the CL emission in ceria. In order to have a better understanding of the system, La-doped ceria was proposed as a model system. A precise control over the stoichiometry helped to achieve a desired oxygen vacancy concentration. The CL emission behavior, as observed in reduced ceria, was replicated in the case of La-doped ceria and the analysis revealed that F+ centers favor CL emission whereas F0 centers are disadvantageous. The local structure investigation using EXAFS analysis of both cations Ce and La (K-Edge) showed distortion from the fluorite symmetry and corroborated the F center description of oxygen vacancies in ceria. Our results provide an experimental evidence for F center description involving oxygen vacancies and polarons.
Keywords: ceria, cathodoluminescence spectroscopy, local structure distortion, EXAFS analysis, La doped ceria, luminescence quenching, F centers, dissertations
Published in RUNG: 25.11.2021; Views: 2391; Downloads: 103
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32.
Features of narrative language in fluent aphasia : tesi sottomessa per il titolo di Philosophiae Doctor
Sara Andreetta, 2014, doctoral dissertation

Keywords: aphasia, discourse analysis, language evaluation, dissertations
Published in RUNG: 18.11.2021; Views: 2098; Downloads: 0
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33.
Narrative assessment in patients with communicative disorders
Sara Andreetta, Andrea Marini, 2014, published scientific conference contribution

Keywords: neurolinguistics, discourse analysis, language disorders
Published in RUNG: 04.11.2021; Views: 1532; Downloads: 0
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34.
Application of machine learning techniques for cosmic ray event classification and implementation of a real-time ultra-high energy photon search with the surface detector of the Pierre Auger Observatory : dissertation
Lukas Zehrer, 2021, doctoral dissertation

Abstract: Despite their discovery already more than a century ago, Cosmic Rays (CRs) still did not divulge all their properties yet. Theories about the origin of ultra-high energy (UHE, > 10^18 eV) CRs predict accompanying primary photons. The existence of UHE photons can be investigated with the world’s largest ground-based experiment for detection of CR-induced extensive air showers (EAS), the Pierre Auger Observatory, which offers an unprecedented exposure to rare UHE cosmic particles. The discovery of photons in the UHE regime would open a new observational window to the Universe, improve our understanding of the origin of CRs, and potentially uncloak new physics beyond the standard model. The novelty of the presented work is the development of a "real-time" photon candidate event stream to a global network of observatories, the Astrophysical Multimessenger Observatory Network (AMON). The stream classifies CR events observed by the Auger surface detector (SD) array as regards their probability to be photon nominees, by feeding to advanced machine learning (ML) methods observational air shower parameters of individual CR events combined in a multivariate analysis (MVA). The described straightforward classification procedure further increases the Pierre Auger Observatory’s endeavour to contribute to the global effort of multi-messenger (MM) studies of the highest energy astrophysical phenomena, by supplying AMON partner observatories the possibility to follow-up detected UHE events, live or in their archival data.
Keywords: astroparticle physics, ultra-high energy cosmic rays, ultra-high energy photons, extensive air showers, Pierre Auger Observatory, multi-messenger, AMON, machine learning, multivariate analysis, dissertations
Published in RUNG: 27.10.2021; Views: 2731; Downloads: 147
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35.
L'uso dell'inglese L2 e la correzione degli errori in due lezioni alla scuola media : laurea in lingue e letterature straniere
Greta Mazzaggio, 2012, undergraduate thesis

Abstract: In our globalized and multi-cultural society, communicating between different nationalities becomes more and more important. Language remains a paramount aspect of cultural dialogue and English as lingua franca is the undisputed medium of communication, taught everywhere at an early age. In Italy English is taught since elementary school, sometimes even in kindergarten, when children’s linguistic abilities are stronger; however, teachers usually fail to make the most out of such abilities, as their lessons are primarily in Italian and the use of English is limited to some words or expressions targeted by exercises. With such an input, the children’s progress is likely to be limited. My experiment attempts to assess the interaction student-teacher in terms of use of L2 in class by means of a comparative analysis of two middle-school lessons taught by the same teacher to different age groups. Moreover, teacher’s correction techniques will be assessed in the light of frameworks established by scholars in this field, where the positive value of errors in the development of children interlanguage emerges with clarity. Since feedback is an essential part of education, special attention was paid to the teacher’s behavior in dealing with student’s mistakes. Two entire lessons were recorded and transcribed, counting the numbers of words and turns uttered respectively by students and the teacher. When collected and analyzed, such data exhibited both similarities and differences between classes. On the teacher’s side, both lessons revealed that she adopts a rather conservative style of teaching, with limited interaction. As a result, the lessons are to be considered teacher-oriented, for the distribution of turns and the amount of words exchanged; conducted along the textbook’s lines, they offer very limited room for creative language production. Moreover, the teacher’s tendency to steadily correct the students, with the only exception of pronunciation errors, impairs student’s communicative fluency at large. However, a certain progress may be observed between the 1st and 3rd class in both the increased command of English and the number of errors, decreased by almost 50%. In both cases, though, the production of English sentences is creative only for a minimal part, as English is often read and lessons are mostly based on the correction of homework and written exercises. In conclusion, the experiment offers data that confirm several assumptions of contemporary linguistics, particularly in the field of Second Language Acquisition and Error Analysis.
Keywords: Second Language Acquisition, Error Analysis, Italian, English as L2
Published in RUNG: 22.09.2021; Views: 1825; Downloads: 0
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36.
Untargeted molecular analysis of exhaled breath as a diagnostic test for ventilator-associated lower respiratory tract infections (BreathDx)
Pouline M. van Oort, Tamara M. E. Nijsen, Iain R. White, Hugo Knobel, Timothy Felton, Nicholas J. W. Rattray, Oluwasola Lawal, Murtaza Bulut, Waqar Ahmed, Antonio Artigas, 2021, short scientific article

Abstract: Patients suspected of ventilator-associated lower respiratory tract infections (VA-LRTIs) commonly receive broad-spectrum antimicrobial therapy unnecessarily. We tested whether exhaled breath analysis can discriminate between patients suspected of VA-LRTI with confirmed infection, from patients with negative cultures. Breath from 108 patients suspected of VA-LRTI was analysed by gas chromatography-mass spectrometry. The breath test had a sensitivity of 98% at a specificity of 49%, confirmed with a second analytical method. The breath test had a negative predictive value of 96% and excluded pneumonia in half of the patients with negative cultures. Trial registration number: UKCRN ID number 19086, registered May 2015.
Keywords: ventilator-associated pneumonia, breath analysis, volatile organic compounds, metabolomics, intensive care, hospital acquired infections
Published in RUNG: 07.09.2021; Views: 4042; Downloads: 0
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37.
An economic analysis of biomass potential as an opportunity to increase the share of biogas production for energy purposes in Slovenia : master's thesis
Stefan Dabižljević, 2021, master's thesis

Abstract: One of the biggest global problems, the solution of being put in front of the scientists around the world, is endangering the environment. To preserve it, the transition from non-renewable to renewable energy sources is a rational and necessary solution. One of the energy sources with great potential in the future is biomass. In the master’s thesis, we have studied the economic analysis of the possibility of obtaining energy from biogas in Slovenia for the production of which biomass is used. For the study to be successful, it was necessary to analyse the situation in the field of renewable energy sources and biogas in the European Union and Slovenia to obtain a general picture for further analysis. By analysing the available data from previous years, we gained insight into the situation in the given area. The master’s thesis aims to show that although Slovenia has been facing the problem of a decreasing number of biogas power plants for years, the implementation of a system for obtaining energy from biogas is an economically and environmentally viable investment. The economic analysis was done for a 1 MW plant. The choice of plant size and power was made based on the Kepner-Tregoe method and the method of comparing alternatives. For the project duration of 30 years, through cash flows, as well as through various economic indicators, such as the presentation of loan calculations with a certain interest rate, internal rate of return, repayment period method, present project value, etc., the economic side of the investment is presented, which aims to show the profitability of the project.
Keywords: Renewable energy sources, biomass, biogas, economic analysis, investment, project
Published in RUNG: 07.09.2021; Views: 2193; Downloads: 95
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38.
Improved photocatalytic activity of SnO[sub]2-TiO[sub]2 nanocomposite thin films prepared by low-temperature sol-gel method
Ksenija Maver, Iztok Arčon, Mattia Fanetti, Samar Al Jitan, Giovanni Palmisano, Matjaž Valant, Urška Lavrenčič Štangar, 2021, original scientific article

Abstract: The objective of this research was to investigate how the photocatalytic activity of pure TiO2 can be improved by SnO2 modification. Different molar ratios of tin to titanium were prepared. The correlation between tin concentration and structural properties was investigated to explain the mechanism of photocatalytic efficiency and to optimize the synthesis conditions to obtain enhanced activity of the SnO2-modified TiO2 photocatalysts under UV-irradiation. The SnO2-modified TiO2 photocatalysts were prepared by a low-temperature sol-gel method based on organic tin and titanium precursors. The precursors underwent sol-gel reactions separately to form SnO2-TiO2 sol. The sol-gels were deposited on a glass substrate by a dip-coating technique and dried at 150 ◦C to obtain the photocatalysts in the form of a thin film. To test the thermal stability of the material, an additional set of photocatalysts was prepared by calcining the dried samples in air at 500 ◦C. The photocatalytic activity of the samples was determined by measuring the degradation rate of an azo dye. An increase of up to 30% in the photocatalytic activity of the air-dried samples was obtained when the TiO2 was modified with the SnO2 in a concentration range of 0.1–1 mol.%. At higher SnO2 loadings, the photocatalytic activity of the photocatalyst was reduced compared to the unmodified TiO2. The calcined samples showed an overall reduced photocatalytic activity compared to the air-dried samples. Various characterization techniques (UV-Vis, XRD, N2-physisorption, TEM, EDX, SEM, XAS and photoelectrochemical characterization) were used to explain the mechanism for the enhanced and hindered photocatalytic performances of the SnO2-modified TiO2 photocatalysts. The results showed that the nanocrystalline cassiterite SnO2 is attached to the TiO2 nanocrystallites through the Sn-O-Ti bonds. In this way, the coupling of two semiconductors, SnO2 and TiO2, was demonstrated. Compared to single-phase photocatalysts, the coupling of semiconductors has a beneficial effect on the separation of charge carriers, which prolongs their lifetime for accessibility to participate in the redox reactions. The maximum increase in activity of the thin films was achieved in the low concentration range (0.1–1 mol.%), which means that an optimal ratio and contact of the two phases is achieved for the given physical parameters such as particle size, shape and specific surface area of the catalyst.
Keywords: photocatalytic activity, Sn-modified TiO2, low-temperature, thin films, XAS analysis
Published in RUNG: 05.07.2021; Views: 2331; Downloads: 0
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