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53. In poetry, if meter has to help memory, it takes its timeSara Andreetta, Oleksandra Soldatkina, Vezha Boboeva, Alessandro Treves, 2021, original scientific article Keywords: memory, poetry, meter, Italian poetry
Published in RUNG: 04.11.2021; Views: 1585; Downloads: 40
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56. Determination of the multiple-scattering correction factor and its cross-sensitivity to scattering and wavelength dependence for different AE33 Aethalometer filter tapes : a multi-instrumental approachJesús Yus-Díez, Vera Bernardoni, Griša Močnik, Andrés Alastuey, Davide Ciniglia, Matic Ivančič, Xavier Querol, Noemí Perez, Cristina Reche, Martin Rigler, Roberta Vecchi, Sara Valentini, Marco Pandolfi, 2021, original scientific article Abstract: Providing reliable observations of aerosol particles' absorption properties at spatial and temporal resolutions suited to climate models is of utter importance to better understand the effects that atmospheric particles have on climate. Nowadays, one of the instruments most widely used in international monitoring networks for in situ surface measurements of light absorption properties of atmospheric aerosol particles is the multi-wavelength dual-spot Aethalometer, AE33. The AE33 derives the absorption coefficients of aerosol particles at seven different wavelengths from the measurements of the optical attenuation of light through a filter where particles are continuously collected. An accurate determination of the absorption coefficients from the AE33 instrument relies on the quantification of the non-linear processes related to the sample collection on the filter. The multiple-scattering correction factor (C), which depends on the filter tape used and on the optical properties of the collected particles, is the parameter with both the greatest uncertainty and the greatest impact on the absorption coefficients derived from the AE33 measurements.
Here we present an in-depth analysis of the AE33 multiple-scattering correction factor C and its wavelength dependence for two different and widely used filter tapes, namely the old, and most referenced, TFE-coated glass, or M8020, filter tape and the currently, and most widely used, M8060 filter tape. For performing this analysis, we compared the attenuation measurements from AE33 with the absorption coefficients measured with different filter-based techniques. On-line co-located multi-angle absorption photometer (MAAP) measurements and off-line PP_UniMI polar photometer measurements were employed as reference absorption measurements for this work. To this aim, we used data from three different measurement stations located in the north-east of Spain, namely an urban background station (Barcelona, BCN), a regional background station (Montseny, MSY) and a mountaintop station (Montsec d'Ares, MSA). The median C values (at 637 nm) measured at the three stations ranged between 2.29 (at BCN and MSY, lowest 5th percentile of 1.97 and highest 95th percentile of 2.68) and 2.51 (at MSA, lowest 5th percentile of 2.06 and highest 95th percentile of 3.06). The analysis of the cross-sensitivity to scattering, for the two filter tapes considered here, revealed a large increase in the C factor when the single-scattering albedo (SSA) of the collected particles was above a given threshold, up to a 3-fold increase above the average C values. The SSA threshold appeared to be site dependent and ranged between 0.90 to 0.95 for the stations considered in the study. The results of the cross-sensitivity to scattering displayed a fitted constant multiple-scattering parameter, Cf, of 2.21 and 1.96, and a cross-sensitivity factor, ms, of 1.8 % and 3.4 % for the MSY and MSA stations, respectively, for the TFE-coated glass filter tape. For the M8060 filter tape, Cf values of 2.50, 1.96 and 1.82 and ms values of 1.6 %, 3.0 % and 4.9 % for the BCN, MSY and MSA stations, respectively, were obtained. SSA variations also influenced the spectral dependence of C, which showed an increase with wavelength when SSA was above the site-dependent threshold. Below the SSA threshold, no statistically significant dependence of C on the wavelength was observed. For the measurement stations considered here, the wavelength dependence of C was to some extent driven by the presence of dust particles during Saharan dust outbreaks that had the potential to increase the SSA above the average values. At the mountaintop station, an omission of the wavelength dependence of the C factor led to an underestimation of the absorption Ångström exponent (AAE) by up to 12 %. Differences in the absorption coefficient determined from AE33 measurements at BCN, MSY and MSA of around 35 %–40 % can be expected when using the site-dependent experimentally obtained C value instead of the nominal C value. Due to the fundamental role that the SSA of the particles collected on the filter tape has in the multiple-scattering parameter C, we present a methodology that allows the recognition of the conditions upon which the use of a constant and wavelength-independent C is feasible.
Keywords: black carbon, aerosol absorption, filter photometer, artifact
Published in RUNG: 01.10.2021; Views: 1989; Downloads: 0
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57. Identification of environmental stress conditions by comparative analysis of peroxidase activity in betulla pendula and pinus sp. : Group project reportPatrik Cingerli, Katarina Erker, Nina Žvab-Pernat, Darian Rampih, Miroslav Štrbac, Hena Zukić, Kenan Kapetanović, 2021, treatise, preliminary study, study Abstract: The study investigated the possibility of developing a biomarker to evaluate the stress level in trees. The analyses have been performed on tree samples appertaining to two different tree species and collected at two locations in Slovenia. The presence and the activity of the proteins – peroxidases was measured by the qualitative method of the agarose gel electrophoresis and the quantitative method of spectrometry. It was found out that by measuring the presence of the biomarkers and pigments in the tree samples we can determine the stress levels and thus the health status of trees.
Keywords: biomarkers, environmental stress, pigments, peroxidase
Published in RUNG: 29.09.2021; Views: 2195; Downloads: 0
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58. Silica coated Bi[sub]2Se[sub]3 topological insulator nanoplatelets : the way of making them colloidally stable but preserving their optical propertiesBlaž Belec, Nina Kostevšek, Sebastjan Nemec, Slavko Kralj, Sandra Gardonio, Mattia Fanetti, Matjaž Valant, 2021, published scientific conference contribution abstract Keywords: topological insulator, optical properties, topological surface states, silica-coated
Published in RUNG: 27.09.2021; Views: 2390; Downloads: 0
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59. CDR1 composition can affect nanobody recombinant expression yieldsMarco Orlando, Sara Fortuna, Sandra Oloketuyi, Gregor Bajc, Adi Goldenzweig, Ario De Marco, 2021, original scientific article Keywords: nanobodies, in silico engineering, mutagenesis
Published in RUNG: 15.09.2021; Views: 1767; Downloads: 42
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60. Chemical (in)stability of an interface between metals and Bi[sub]2Se[sub]3 topological insulatorKatja Ferfolja, Mattia Fanetti, Sandra Gardonio, Matjaž Valant, 2019, published scientific conference contribution abstract Abstract: Our research is dedicated to a study of an interface between a Bi2Se3 topological insulator (TI) and various metals due to the essential need for providing a metal contact for devices. The main objective is to characterize structural and chemical properties at the interface, where the electronic properties of the TI can be affected. The structure of the interface and processes happening at it are investigated by microscopy (SEM, TEM, STM) and spectroscopy techniques (EDX, XPS).
The research started with the noble metals: Ag, Au and Pt. A good stability was observed for Au and Pt, whereas Ag reacted with Bi2Se3 already at room temperature, producing Ag2Se and AgBiSe2 phase. Interface stability was also checked at high temperature and results showed that the Au coating undergoes a coalescence process starting from 100 °C whereas the interface with Pt does not show any change at least up to 350 °C.
At present we are focused on the interface with Ti, a metal which is regularly used as an adhesive layer in electrical contacts. At low coverage (<30 nm) Ti forms an extremely flat film, smoother than Au, Ag or Pt. At higher coverage the film undergoes buckle delamination, likely induced by stress release. The observed morphology indicates that a chemical interaction leads to the growth of the initial smooth Ti epitaxial film. Se interdiffusion and formation of interfacial TixSey phase is envisaged, as suggested from preliminary TEM observations of the interface structure.
The presented results show the importance of the processes happening at the interface, especially solid-state chemical reactions, which are often neglected in the study of systems with metal/TI interfaces. Such instability has to be taken into account since the produced phases can affect transport properties of the material, increase a contact resistance or affect functionality of devices.
Keywords: Bi2Se3, interface, topological insulator, chemical instability
Published in RUNG: 20.08.2021; Views: 1948; Downloads: 12
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