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Determination of high-time resolution mineral dust concentration in real-time by optical absorption measurements
Matic Ivančič, Irena Ježek, Martin Rigler, Asta Gregorič, Bálint Alföldy, Rok Podlipec, Luka Drinovec, Griša Močnik, 2021, published scientific conference contribution abstract

Found in: osebi
Keywords: mineral dust, concentration, aerosols, air quality
Published: 17.11.2021; Views: 882; Downloads: 3
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The impact of temperature inversions on black carbon and particle mass concentrations in a mountainous area
Miha Markelj, Maja Remškar, Martin Rigler, Irena Ježek, Kay Weinhold, Matej Ogrin, Asta Gregorič, Luka Drinovec, Andrea Cuesta-Mosquera, Honey Dawn C. Alas, Kristina Glojek, Griša Močnik, 2022, original scientific article

Abstract: Residential wood combustion is a widespread practice in Europe with a serious impact on air quality, especially in mountainous areas. While there is a significant number of studies conducted in deep urbanized valleys and basins, little is known about the air pollution processes in rural shallow hollows, where around 30 % of the people in mountainous areas across Europe live. We aim to determine the influence of ground temperature inversions on wood combustion aerosol pollution in hilly, rural areas. The study uses Retje karst hollow (Loški Potok, Slovenia) as a representative site for mountainous and hilly rural areas in central and south-eastern Europe with residential wood combustion. Sampling with a mobile monitoring platform along the hollow was performed in December 2017 and January 2018. The backpack mobile monitoring platform was used for the determination of equivalent black carbon (eBC) and particulate matter (PM) mass concentrations along the hollow. To ensure high quality of mobile measurement data, intercomparisons of mobile instruments with reference instruments were performed at two air quality stations during every run. Our study showed that aerosol pollution events in the relief depression were associated with high local emission intensities originating almost entirely from residential wood burning and shallow temperature inversions (58 m on average). The eBC and PM mass concentrations showed stronger associations with the potential temperature gradient (R2=0.8) than with any other meteorological parameters taken into account (ambient temperature, relative humidity, wind speed, wind direction, and precipitation). The strong association between the potential temperature gradient and pollutant concentrations suggests that even a small number of emission sources (total 243 households in the studied hollow) in similar hilly and mountainous rural areas with frequent temperature inversions can significantly increase the levels of eBC and PM and deteriorate local air quality. During temperature inversions the measured mean eBC and PM2.5 mass concentrations in the whole hollow were as high as 4.5±2.6 and 48.0 ± 27.7 µg m−3, respectively, which is comparable to larger European urban centres.
Found in: osebi
Keywords: air pollution, black carbon, sources, temperature inversion, mountainous area
Published: 03.05.2022; Views: 526; Downloads: 0
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Composition and diversity analysis of the lung microbiome in patients with suspected ventilator-associated pneumonia
Stephen Fowler, Paul Dark, Marcus Schultz, Ignacio Martin-Loeches, Pedro Póvoa, Antonio Artigas, Timothy Felton, Waqar Ahmed, Pouline van Oort, Paul Brinkman, Mahmoud Abdel-Aziz, Dominic Fenn, Iain R. White, 2022, original scientific article

Abstract: Background: Ventilator-associated pneumonia (VAP) is associated with high morbidity and health care costs, yet diagnosis remains a challenge. Analysis of airway microbiota by amplicon sequencing provides a possible solution, as pneumonia is characterised by a disruption of the microbiome. However, studies evaluating the diagnostic capabilities of microbiome analysis are limited, with a lack of alignment on possible biomarkers. Using bronchoalveolar lavage fluid (BALF) from ventilated adult patients suspected of VAP, we aimed to explore how key characteristics of the microbiome differ between patients with positive and negative BALF cultures and whether any differences could have a clinically relevant role. Methods: BALF from patients suspected of VAP was analysed using 16s rRNA sequencing in order to: (1) differentiate between patients with and without a positive culture; (2) determine if there was any association between microbiome diversity and local inflammatory response; and (3) correctly identify pathogens detected by conventional culture. Results: Thirty-seven of 90 ICU patients with suspected VAP had positive cultures. Patients with a positive culture had significant microbiome dysbiosis with reduced alpha diversity. However, gross compositional variance was not strongly associated with culture positivity (AUROCC range 0.66–0.71). Patients with a positive culture had a significantly higher relative abundance of pathogenic bacteria compared to those without [0.45 (IQR 0.10–0.84), 0.02 (IQR 0.004–0.09), respectively], and an increased interleukin (IL)-1β was associated with reduced species evenness (rs = − 0.33, p < 0.01) and increased pathogenic bacteria presence (rs = 0.28, p = 0.013). Untargeted 16s rRNA pathogen detection was limited by false positives, while the use of pathogen-specific relative abundance thresholds showed better diagnostic accuracy (AUROCC range 0.89–0.998). Conclusion: Patients with positive BALF culture had increased dysbiosis and genus dominance. An increased caspase-1-dependent IL-1b expression was associated with a reduced species evenness and increased pathogenic bacterial presence, providing a possible causal link between microbiome dysbiosis and lung injury development in VAP. However, measures of diversity were an unreliable predictor of culture positivity and 16s sequencing used agnostically could not usefully identify pathogens; this could be overcome if pathogen-specific relative abundance thresholds are used.
Found in: osebi
Keywords: Microbiome, Next-generation sequencing, Ventilator-associated pneumonia
Published: 26.10.2022; Views: 341; Downloads: 0
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Richard Wagner
Martin Gregor-Dellin, 2017

Found in: osebi
Keywords: nemška glasba, nemški skladatelji, nemška opera, glasbena drama, glasbeno gledališče, odrska glasba,
Published: 02.03.2022; Views: 792; Downloads: 0
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Characterization of electrochemical processes in metal-organic batteries by X-ray Raman spectroscopy
Martin Sundermann, Hlynur Gretarsson, Robert Dominko, Urban Košir, Jan Bitenc, Alen Vižintin, Marko Petric, Matjaž Žitnik, Klemen Bučar, Iztok Arčon, Ava Rajh, Matjaž Kavčič, 2022, original scientific article

Abstract: X-ray Raman spectroscopy (XRS) is an emerging spectroscopic technique that utilizes inelastic scattering of hard Xrays to study X-ray absorption edges of low Z elements in bulk material. It was used to identify and quantify the amount of carbonyl bonds in a cathode sample, in order to track the redox reaction inside metal−organic batteries during the charge/ discharge cycle. XRS was used to record the oxygen K-edge absorption spectra of organic polymer cathodes from different multivalent metal−organic batteries. The amount of carbonyl bond in each sample was determined by modeling the oxygen K-edge XRS spectra with the linear combination of two reference compounds that mimicked the fully charged and the fully discharged phases of the battery. To interpret experimental XRS spectra, theoretical calculations of oxygen K-edge absorption spectra based on density functional theory were performed. Overall, a good agreement between the amount of carbonyl bond present during different stages of battery cycle, calculated from linear combination of standards, and the amount obtained from electrochemical characterization based on measured capacity was achieved. The electrochemical mechanism in all studied batteries was confirmed to be a reduction of double carbonyl bond and the intermediate anion was identified with the help of theoretical calculations. X-ray Raman spectroscopy of the oxygen K-edge was shown to be a viable characterization technique for accurate tracking of the redox reaction inside metal−organic batteries.
Found in: osebi
Keywords: X-ray Raman spectroscopy, meta-organic batteries, oxygen K-edge XANES, electrochemical processes
Published: 24.03.2022; Views: 836; Downloads: 14
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Proceedings of the 4th International Conference on Time and Matter, 4-8 March 2013, Venice, Italy
2013, proceedings of professional or unreviewed scientific conference contributions

Found in: osebi
Published: 15.04.2022; Views: 512; Downloads: 0

Proceedings of the 3rd International Conference on Time and Matter, 4-8 October 2010, Budva, Montenegro
2011, proceedings of professional or unreviewed scientific conference contributions

Found in: osebi
Published: 19.04.2022; Views: 530; Downloads: 0
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