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11.
Structure and population of complex ionic species in FeCl[sub]2 aqueous solution by X-ray absorption spectroscopy
Uroš Luin, Iztok Arčon, Matjaž Valant, 2022, original scientific article

Abstract: Technologies for mass production require cheap and abundant materials such as ferrous chloride (FeCl2). The literature survey shows the lack of experimental studies to validate theoretical conclusions related to the population of ionic Fe-species in the aqueous FeCl2 solution. Here, we present an in situ X-ray absorption study of the structure of the ionic species in the FeCl2 aqueous solution at different concentrations (1–4 molL−1) and temperatures (25–80 ◦C). We found that at low temperature and low FeCl2 concentration, the octahedral first coordination sphere around Fe is occupied by one Cl ion at a distance of 2.33 (±0.02) Å and five water molecules at a distance of 2.095 (±0.005) Å. The structure of the ionic complex gradually changes with an increase in temperature and/or concentration. The apical water molecule is substituted by a chlorine ion to yield a neutral Fe[Cl2(H2O)4]0. The observed substitutional mechanism is facilitated by the presence of the intramolecular hydrogen bonds as well as entropic reasons. The transition from the single charged Fe[Cl(H2O)5]+ to the neutral Fe[Cl2(H2O)4]0 causes a significant drop in the solution conductivity, which well correlates with the existing conductivity models.
Keywords: structure, population, ionic species, aqueous ferrous chloride, in situ X-ray absorption spectroscopy
Published in RUNG: 24.01.2022; Views: 1666; Downloads: 42  (1 vote)
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Experimental syntax and Slavic languages
Arthur Stepanov, 2021, independent scientific component part or a chapter in a monograph

Abstract: The chapter reviews a number of empirical domains that recently came into the focus of research in Slavic experimental syntax, including island phenomena, syntactic Superiority effects, various types of agreement, word order, and scope interaction, among others. This research mostly relies on sentence acceptability experiments applied across larger pools of participants, but the chapter also reviews selected studies using related experimental methods (e.g. elicited production and sentence–picture verification). The chapter concludes by identifying a number of conceptual issues in syntactic theory, for which we believe Slavic experimental syntax has a potential to make a particularly strong contribution.
Keywords: experimental syntax, Slavic language, syntactic island, unaccusativity, information structure, superiority effect, case matching, agreement, numeral phrase
Published in RUNG: 20.12.2021; Views: 1806; Downloads: 14
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15.
Prosody and information status in Italian and German L2 intonation
Cinzia Avesani, Giuliano Bocci, Mario Vayra, 2015, independent scientific component part or a chapter in a monograph

Abstract: In this work, we address the systemic difference in the prosodic strategies of accentuation at the utterance level of Italian and German, belonging respectively to Romance and Germanic languages. In particular, we address the Interlanguage properties of the speech produced by adult Second Language Learners of the two languages analyzing their production in semi-spontaneous elicitation contexts. We focus on the acquisition of the interplay of phonological and discourse structure occurring in German causing Given Information to be prosodically deaccented, because already cognitively activated in the mind of the interlocutor. The Deaccentuation contour is prosodically realized as a flat low pitch contour and is pragmatically assigned in Germanic languages to a non-focused element, even in positions that metrically would require the positioning of a Nuclear Pitch Accent. This strategy is not reported in Italian, causing referents that align to the position of the prosodic metrical head to be standardly pitch-accented. Deaccentuation, is hard to acquire and subject to prosodic transfer when produced by L2 learners native speakers of Italian, especially when aligning with the metrical head requiring accentuation. Italian L2 speakers of German show to accent Given referents because adopting the Italian accentuation strategy, while German L2 speakers of Italian seem to accommodate more easily the accentuation pattern in L2. We provide a possible explanation in light of the Differential Markedness Hypothesis that considers the number of parameters to be acquired by the L2 speakers.
Keywords: pitch accents, deaccentuation, German, Italian, discourse structure, L2 acquisition, prosody
Published in RUNG: 14.12.2021; Views: 1574; Downloads: 0
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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: 2390; Downloads: 103
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19.
N-subalgebras of BCK=BCI-algebras which are induced from hyperfuzzy structures
Hashem Bordbar, Mohammad Rahim Bordbar, Rajab Ali Borzooei, Young Bae Jun, 2021, original scientific article

Abstract: In the paper [J. Ghosh and T.K. Samanta, Hyperfuzzy sets and hyperfuzzy group, Int. J. Advanced Sci Tech. 41 (2012), 27–37], Ghosh and Samanta introduced the concept of hyperfuzzy sets as a generalization of fuzzy sets and interval-valued fuzzy sets and applied it to group theory. The aim of this manuscript is to study N-structures in BCK\BCI-algebras induced from hyperfuzzy structures.
Keywords: hyperfuzzy set, hyperfuzzy structure, hyperfuzzy subalgebra, N-subalgebra, induced N-function
Published in RUNG: 03.11.2021; Views: 1545; Downloads: 42
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20.
Orbital selective dynamics in Fe-pnictides triggered by polarized pump pulse excitations
Ganesh Adhikary, Tanusree Saha, Primož Rebernik Ribič, Matija Stupar, Barbara Ressel, Jurij Urbančič, Giovanni De Ninno, A. Thamizhavel, Kalobaran Maiti, 2021, original scientific article

Abstract: Quantum materials display exotic behaviours related to the interplay between temperature-driven phase transitions. Here, we study the electron dynamics in one such material, CaFe$_2$As$_2$, a parent Fe-based superconductor, employing time and angle-resolved photoemission spectroscopy. CaFe$_2$As$_2$ exhibits concomitant transition to spin density wave state and tetragonal to orthorhombic structure below 170 K. The Fermi surface of this material consists of three hole pockets ($\alpha$, $\beta$ and $\gamma$) around $\Gamma$-point and two electron pockets around $X$-point. The hole pockets have $d_{xy}$, $d_{yz}$ and $d_{zx}$ orbital symmetries. The $\beta$ band constituted by $d_{xz}$/$d_{yz}$ orbitals exhibit a gap across the magnetic phase transition. We discover that polarized pump pulses can induce excitations of electrons of a selected symmetry. More specifically, while $s$-polarized light (polarization vector perpendicular to the $xz$-plane) excites electrons corresponding to all the three hole bands, $p$-polarized light excites electrons essentially from ($\alpha$,$\beta$) bands which are responsible for magnetic order. Interestingly, within the magnetically ordered phase, the excitation due to the $p$-polarized pump pulses occur at a time scale of 50 fs, which is significantly faster than the excitation induced by $s$-polarized light ($\sim$ 200 fs). These results suggest that the relaxation of different ordered phases occurs at different time scales and this method can be used to achieve selective excitations to disentangle complexity in the study of quantum materials.
Keywords: Electronic structure, Pnictides and chalcogenides, Time-resolved spectroscopy
Published in RUNG: 13.10.2021; Views: 1783; Downloads: 6
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