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149 results on '"Todea, Ana Maria"'

6. The imperfect-preterite opposition in romance languages

Author

Todea, Ana Maria, Watson, Ian, and Maiden, Martin

Subjects
440, Linguistics, Romance languages, French, Romanian, Spanish, tense, aspect, imperfect, preterite, perfective, imperfective, perfect, Romance
Abstract

An aspect of the Romance languages that defies neat linguistic analysis is tense usage. In particular, students of Romance languages as well as grammarians have found it difficult to provide a consistent explanation for the imperfect - preterite opposition. Two main points of contention concern (i) the question of whether the two forms have an inherent aspectual content and (ii) the structure and role of lexical aspectual information in determining the overall meaning of a sentence. While the attempts at explaining French and Spanish usages of the imperfect and the preterite are numerous, hardly any work has been done in the interpretation of Romanian data. Furthermore, a general assumption that the same form - function opposition holds across Romance languages has led to cross-linguistic differences rarely being examined. I argue that the imperfect and the preterite do have an inherent aspectual content. However, in opposition to previous accounts, I maintain that the preterite does not provide a ‘closed’ viewpoint and that an atelic eventuality described by the verb phrase in the preterite can continue up to the present moment. I propose a description of the imperfect - preterite opposition that includes finer distinctions of lexical aspect based on its constituent stage structure. These finer lexical aspectual distinctions allow the identification of an area of divergence in the use of the two forms in French, Spanish, and Romanian: the preterite was found to be used more widely with states in Romanian than in French and Spanish.

Published
2014

7. Evaluation of a Partector Pro for atmospheric particle number size distribution and number concentration measurements at an urban background site.

Author

Asbach, Christof, Todea, Ana Maria, and Kaminski, Heinz

Subjects
PARTICLE size distribution, SPECTROMETRY, GEOMETRIC measure theory, STANDARD deviations, REGRESSION analysis
Abstract

Particle number size distributions, total number concentrations and mean particle sizes have been measured for 70 d at an urban background site in Mülheim-Styrum, Germany, with a handheld Partector Pro of the first generation and a TSI mobility particle size spectrometer (MPSS). The aim of the study was to evaluate the performance of the Partector Pro against the MPSS. The results show that the size distributions, measured with the Partector Pro, agree with the MPSS mostly within ± 25% for particle sizes between 10 and 113.5 nm, whereas higher, systematic differences were observed for larger particles. The measurement accuracy was shown to be dependent on the geometric mean diameter and the geometric standard deviation of the aerosol. Best results were found for the most abundant size distributions with geometric mean particle diameters ≥30 nm and geometric standard deviations larger than 1.8. The total number concentration, measured by the Partector Pro, was found to be in excellent agreement with the MPSS with a slope of the linear fit of 0.9977 and a regression coefficient of R² D 0:9956. The agreement of the geometric mean particle diameter, determined with the Partector Pro and the MPSS was good but moderately dependent on the particle size distribution. For mean particle sizes between 20 and 50 nm, the bias was within ±15 %. Higher deviations of up to 30% were observed when the geometric mean particle sizes exceeded 70 nm and when the geometric standard deviations exceeded approximately 2.7. [ABSTRACT FROM AUTHOR]

Published
2024
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10. Multiple nearest-neighbor exchange model for the frustrated magnetic molecules Mo72Fe30 and Mo72Cr30

Author

Schröder, Christian, Prozorov, Ruslan, Kögerler, Paul, Vannette, Matthew D., Fang, Xikui, Luban, Marshall, Matsuo, Akira, Kindo, Koichi, Müller, Achim, and Todea, Ana Maria

Subjects
Physics - Atomic and Molecular Clusters
Abstract

Our measurements of the differential susceptibility dM/dH of the frustrated magnetic molecules Mo72Fe30 and Mo72Cr30 reveal a pronounced dependence on magnetic field (H) and temperature (T) in the low H - low T regime, contrary to the predictions of existing models. Excellent agreement with experiment is achieved upon formulating a nearest-neighbor classical Heisenberg model where the 60 nearest-neighbor exchange interactions in each molecule, rather than being identical as has been assumed heretofore, are described by a two-parameter probability distribution of values of the exchange constant. We suggest that the probability distribution provides a convenient phenomenological platform for summarizing the combined effects of multiple microscopic mechanisms that disrupt the idealized picture of a Heisenberg model based on a single value of the nearest-neighbor exchange constant., Comment: 8 pages, 5 figures

Published
2008
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12. Particulate matter during Ultrashort-Pulse Laser (USPL) processing

Author

Walter, Jürgen, Düsing, Jan, Hansen, Tanja, Schumacher, Stefan, Schwarz, Katharina, Todea, Ana Maria, Ritter, Detlef, Asbach, Christof, Jäschke, Peter, and Kaierle, Stefan

Abstract

The project “FUMe” shall fill significant knowledge-gaps about the release of particulate from the process zone during material processing with ultrashort-pulse lasers (USPL). Particle propagation in the working area and particle deposition on component and system surfaces will be examined for open and closed systems. To determine the emission rates and the space- and time-resolved inhalable exposure to total dust experimental measurements will be used. First results of the investigations in the exhaust-gas of USP laser processes on steel and ceramics are available. Particle-size-distributions have been determined and differences in the origin of the particles have been analysed. Toxicological analyses will be performed on nanoparticle-containing fumes by in-vitro exposure to human alveolar epithelial cells and subsequent determination of the cell viability. The measurement results can be used to develop laser process-specific measures for optimised health protection as well as to reduce component rework and system cleaning from dust deposits.

Published
2024
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22. Investigation of the effect of aerosolized tio₂ nanoparticles on the no₂ concentrations under uva exposure

Author

Nasrabadi, Ali Mohamadi, Todea, Ana Maria, Wolf, Carmen, Demirel, Tolga, Habryka, David, and Asbach, Christof

Subjects
Maschinenbau
Abstract

CA Asbach Engineered nanomaterials (ENM) are utilized and produced during many engineering processes. However, they may generate airborne nanoparticles during different phases of their life cycles. TiO2, which is known for its photocatalytic properties, especially in terms of degrading NO2, is one of the most widely produced ENM. Ambient NO2 stems mainly from vehicular and industrial combustion processes and potentially harms human health upon inhalation. This study investigated the photocatalytic reduction of NO2 due to varying concentrations of aerosolized TiO2 nanoparticlesduring varying levels of ultraviolet A (UVA) exposure. Additionally, we evaluated the effects of low (5%), moderate (35%), and high (70%) relative humidity. Our results demonstrated that the decrease in NO2 depended on both the TiO2 concentration and the UVA intensity. However, when the former was high (> 3.23E+06 cm–3), the contribution of the latter was negligible. On the other hand, when the latter was high, the influence of the former was minimal. Furthermore, as the UVA exposure increased in duration, its effect became dominant over that of the TiO2 concentration.Finally, we found the relative humidity to be an insignificant factor during conditions with strongUVA (6328 W s m–2).

Published
2021

26. Impact of emissions of airborne TiO2 ENM on atmospheric NO2 concentrations

Author

Asbach, Christof, Mohammadi-Nasrabadi, Ali, Nickel, Carmen, Todea, Ana Maria, Lacome, Jean-Marc, Aguerre-Chariol, Olivier, Kuenen, Jeroen, Manders-Groot, Astrid M.M., IUTA e.v., Air Quality & Sustainable Nanotechnology Unit, Institut National de l'Environnement Industriel et des Risques (INERIS), The Netherlands Organisation for Applied Scientific Research (TNO), and Civs, Gestionnaire

Subjects
[SDE] Environmental Sciences, [SDE.IE]Environmental Sciences/Environmental Engineering, [SDE]Environmental Sciences, [SDE.IE] Environmental Sciences/Environmental Engineering
Abstract

Titanium dioxide is one of the most produced engineered nanomaterials (ENMs) worldwide. Its high photocatalytic activity is key to many applications. Like any other ENM, TiO2 may be released into the atmosphere during nearly any phase of its lifecycle, where it may interact with atmospheric gases. It is well known and widely exploited that TiO2 photocatalytically reduces NO2 in the presence of UV light, however, the effect of accidentally released TiO2 ENMs on ambient NOx concentrations is widely unknown. We here present a comprehensive study on experimental laboratory investigations on the reaction rates of NO2 in the presence of TiO2 ENM (Evonik P25) under UV irradiation. The study is carried out in a dedicated test rig, where defined concentrations of TiO2 ENMs and NO2 are exposed to UV light. Both the UV light intensity and exposure time are adjustable. In a parallel study, the emission rates of engineered metal oxide nanomaterials from industrial facilities have been experimentally determined in field measurements and are used as surrogates for the TiO2 concentrations used in our lab-experiments. Experimental data on both the emission rates, as well as the chemical reaction rates, are used along with emission inventory data as input parameters for long range modeling of TiO2 and NOx concentrations across Europe using LOTOS-EUROS (see Figure 1) to better understand the dispersion of engineered nanomaterials and their impact on atmospheric chemistry. The poster will present results of the laboratory experiments and the field measurements and how these data are used in the model. First modeling results will be shown and it will be discussed how modeling can help improve the understanding of the presence and effects of engineered nanomaterials in the atmosphere.

Published
2018

28. Review of measurement techniques and methods for assessing personal exposure to airborne nanomaterials in workplaces

Author

Asbach, Christof, primary, Alexander, Carla, additional, Clavaguera, Simon, additional, Dahmann, Dirk, additional, Dozol, Hélène, additional, Faure, Bertrand, additional, Fierz, Martin, additional, Fontana, Luca, additional, Iavicoli, Ivo, additional, Kaminski, Heinz, additional, MacCalman, Laura, additional, Meyer-Plath, Asmus, additional, Simonow, Barbara, additional, van Tongeren, Martie, additional, and Todea, Ana Maria, additional

Published
2017
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29. Inter-comparison of personal monitors for nanoparticles exposure at workplaces and in the environment

Author

Todea, Ana Maria, primary, Beckmann, Stefanie, additional, Kaminski, Heinz, additional, Bard, Delphine, additional, Bau, Sébastien, additional, Clavaguera, Simon, additional, Dahmann, Dirk, additional, Dozol, Hélène, additional, Dziurowitz, Nico, additional, Elihn, Karine, additional, Fierz, Martin, additional, Lidén, Göran, additional, Meyer-Plath, Asmus, additional, Monz, Christian, additional, Neumann, Volker, additional, Pelzer, Johannes, additional, Simonow, Barbara Katrin, additional, Thali, Patrick, additional, Tuinman, Ilse, additional, van der Vleuten, Arjan, additional, Vroomen, Huub, additional, and Asbach, Christof, additional

Published
2017
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30. Rate of ligand exchange between >[Fe.sup.III]-OH2 functional groups on a nanometer-sized aqueous cluster and bulk solution

Author

Balogh, Edina, Todea, Ana Maria, Muller, Achim, and Casey, William H.

Subjects
Molybdenum compounds -- Structure, Molybdenum compounds -- Chemical properties, Molybdenum compounds -- Spectra, Nuclear magnetic resonance spectroscopy -- Analysis, Iron compounds -- Structure, Iron compounds -- Chemical properties, Iron compounds -- Spectra, Dipole moments -- Analysis, Chemistry
Abstract

Study is presented to show that the rates of exchange of waters bound to the >[Fe.sup.III]-OH2 functional groups on 2.5 nm Mo72Fe30 cluster can be measured using standard [super 17]O NMR methods. Results establish a link between the nanoclusters and smaller aqueous molecules.

Published
2007

34. Chapter 7 - Examples and Case Studies

Author

Asbach, Christof, Aguerre, Olivier, Bressot, Christophe, Brouwer, Derk H., Gommel, Udo, Gorbunov, Boris, Le Bihan, Olivier, Jensen, Keld Alstrup, Kaminski, Heinz, Keller, Markus, Koponen, Ismo Kalevi, Kuhlbusch, Thomas A.J., Lecloux, Andre, Morgeneyer, Martin, Muir, Robert, Shandilya, Neeraj, Stahlmecke, Burkhard, and Todea, Ana María

Published
2014
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36. Formation of a 'less stable' polyanion directed and protected by electrophilic internal surface functionalities of a capsule in growth: [{Mo6O19}(2-)subset of{(Mo72Fe30O252)-Fe-VI-O-III(ac)(20)(H2O)(92)}](4-)

Author

Müller, Achim, Todea, Ana Maria, Bögge, Hartmut, van Slageren, Joris, Dressel, Martin, Stammler, Anja, and Rusu, Mariana

Abstract

The spherical capsule skeleton of the host - guest system [{Mo6O19}(2-)subset of{Mo-VI Fe-72(III) O-30(252)(CH3COO)(20)(H2O)(92)}](4-) 1a built up by 12 {( MoVI) MoVI 5} type pentagonal units linked by 30 Fe-III centers which span the unique icosahedral Archimedean solid, the icosidodecahedron - can now be constructed deliberately and with a simpler composition than before from an acidified aqueous molybdate solution containing the mentioned ( virtual) pentagonal units; the encapsulated hexamolybdate - normally not formed in water - is built up in an unprecedented way concomitant with capsule growth, while being directed by the corresponding internal electrophilic surface functionalities.

Published
2006

44. Porous Capsules {(M)M5}12FeIII30 (M=MoVI, WVI): Sphere Surface Supramolecular Chemistry with 20 Ammonium Ions, Related Solution Properties, and Tuning of Magnetic Exchange Interactions

Author

Todea, Ana Maria, primary, Merca, Alice, additional, Bögge, Hartmut, additional, Glaser, Thorsten, additional, Pigga, Joseph M., additional, Langston, Melissa L. K., additional, Liu, Tianbo, additional, Prozorov, Ruslan, additional, Luban, Marshall, additional, Schröder, Christian, additional, Casey, William H., additional, and Müller, Achim, additional

Published
2009
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