11. Spectroscopic insights into the electrochemical mechanism of rechargeable calcium/sulfur batteriesAntonio Scafuri, Romain Berthelot, Klemen Pirnat, Alen Vižintin, Jan Bitenc, Giuliana Aquilanti, Dominique Foix, Rémi Dedryvère, Iztok Arčon, Robert Dominko, Lorenzo Stievano, 13, izvirni znanstveni članek Opis: Calcium batteries represent a promising alternative to lithium metal systems. The combination of the low redox potential and low cost and the energy-dense calcium anode (2073 mAh/cm3, similar to 2044 mAh/cm3 for Li) with appropriate low-cost cathode materials such as sulfur could produce a game-changing technology in several fields of applications. In this work, we present the reversible activity of a proof-of-concept Ca/S battery at room temperature, characterized by a surprising medium-term cycling stability with low polarization, promoted by the use of a simple positive electrode made of sulfur supported on an activated carbon cloth scaffold, and a state-of-the-art fluorinated alkoxyborate-based electrolyte. Insights into the electrochemical mechanism governing the chemistry of the Ca/S system were obtained for the first time by combining X-ray photoelectron spectroscopy and X-ray absorption spectroscopy. The mechanism implies the formation of different types of soluble polysulfide species during both charge and discharge at room temperature, and the formation of solid CaS at the end of discharge. The reversible electrochemical activity is proven by the reformation of elemental sulfur at the end of the following charge. These promising results open the way to the comprehension of emerging Ca/S systems, which may represent a valid alternative to Mg/S and Li/S batteries.
Ključne besede: Calcium/Sulfur Batteries
EXAFS, XANES
Objavljeno v RUNG: 17.10.2020; Ogledov: 2923; Prenosov: 0
Gradivo ima več datotek! Več... |
12. Lidar Observations of Mountain Waves During Bora EpisodesLonglong Wang, Marija Bervida, Samo Stanič, Klemen Bergant, William Eichinger, Benedikt Strajnar, 2020, objavljeni znanstveni prispevek na konferenci Opis: Airflows over mountain barriers in the Alpine region may give rise to strong, gusty downslope winds, called Bora. Oscillations, caused by the flow over an orographic barrier, lead to formation of mountain waves. These waves can only rarely be observed visually and can, in general, not be reliably reproduced by numerical models. Using aerosols as tracers for airmass motion, mountain waves were experimentally observed during Bora outbreak in the Vipava valley, Slovenia, on 24-25 January 2019 by two lidar systems: a vertical scanning lidar positioned just below the peak of the lee side of the mountain range and a fixed direction lidar at valley floor, which were set up to retrieve two-dimensional structure of the airflow over the orographic barrier into the valley. Based on the lidar data, we determined the thickness of airmass layer exhibiting downslope motion, observed hydraulic jump phenomena that gave rise to mountain waves and characterized their properties.
Ključne besede: Bora, mountain waves, lidar observations
Objavljeno v RUNG: 08.07.2020; Ogledov: 2746; Prenosov: 0
Gradivo ima več datotek! Več... |
13. Coupling of autoionizing states by a chirped laser pulseMatjaž Žitnik, Andrej Mihelič, Klemen Bučar, Mateja Hrast, Žiga Barba, Špela Krušič, Primož Rebernik Ribič, Jurij Urbančič, Barbara Ressel, Matija Stupar, David Gauthier, Giovanni De Ninno, 2020, objavljeni povzetek znanstvenega prispevka na konferenci Opis: We have observed the autoionization of the laser-coupled 2s2p 1Po and 2p2 1Se resonances in helium. The ions were collected while varying the frequency and delay of the extreme-ultraviolet (EUV) excitation pulse with respect to the linearly chirped visible (VIS) laser pulse. From the measured frequency-delay map the Autler- Townes splitting, the EUV-VIS cross-correlation and the linear chirp parameter were extracted.
Ključne besede: High Harmonic Generation
Objavljeno v RUNG: 29.06.2020; Ogledov: 3139; Prenosov: 0
Gradivo ima več datotek! Več... |
14. |
15. |
16. Localization, ligand environment, bioavailability and toxicity of mercury in Boletus spp. and Scutiger pes-caprae mushroomsAnja Kavčič, Klemen Mikuš, Marta Debeljak, Johannes Teun van Elteren, Iztok Arčon, Alojz Kodre, Peter Kump, Andreas-Germanos Karydas, Alessandro Migliori, Mateusz Czyzycki, Katarina Vogel-Mikuš, 2019, izvirni znanstveni članek Opis: This study provides information on mercury (Hg) localization, speciation and ligand environment in edible mushrooms: Boletus edulis, B. aereus and Scutiger pes-caprae collected at non-polluted and Hg polluted sites, by LA-ICP-MS, SR-μ-XRF and Hg L3-edge XANES and EXAFS. Mushrooms (especially young ones) collected at Hg polluted sites can contain more than 100 μg Hg g−1 of dry mass. Imaging of the element distribution shows that Hg accumulates mainly in the spore-forming part (hymenium) of the cap. Removal of hymenium before consumption can eliminate more than 50% of accumulated Hg.
Mercury is mainly coordinated to di-thiols (43–82%), followed by di-selenols (13–35%) and tetra-thiols (12–20%). Mercury bioavailability, as determined by feeding the mushrooms to Spanish slugs (known metal bioindicators owing to accumulation of metals in their digestive gland), ranged from 4% (S. pes-caprae) to 30% (B. aereus), and decreased with increasing selenium (Se) levels in the mushrooms. Elevated Hg levels in mushrooms fed to the slugs induced toxic effects, but these effects were counteracted with increasing Se concentrations in the mushrooms, pointing to a protective role of Se against Hg toxicity through HgSe complexation. Nevertheless, consumption of the studied mushroom species from Hg polluted sites should be avoided.
Ključne besede: edible mushrooms, HgSe complex, imaging of elemental distribution, LA-ICP-MS, alpha-XRF, XAS
Objavljeno v RUNG: 24.10.2019; Ogledov: 3343; Prenosov: 0
Gradivo ima več datotek! Več... |
17. Prihodnji scenariji rabe tal na celotnem območju Parka Škocjanske jame z uporabo prostorskega modela DynaCLUEKlemen Cotič, 2019, diplomsko delo Opis: Spremembe rabe tal, kot posledica naših dejavnosti, imajo pomemben vpliv na različne okoljske prvine, kot npr. raven biotske raznovrstnosti in erozijo tal. V tem delu se ukvarjamo s spremembo rabe tal v prihodnosti na širšem območju Regijskega parka Škocjanske jame, z uporabo geografskih informacijskih sistemov, statistike in prostorskega modeliranja. Najprej smo z uporabo zbirke različnih lokacijskih dejavnikov (nadmorska višina, naklon reliefa, ekspozicija tal, oddaljenost od cest, naselij, pedološke profile tal itd.) statistično analizirali prostorsko razporeditev rabe tal s pomočjo logistične regresije. Njivske površine se pojavljajo predvsem na območjih psevdoglenih distričnih tal, trajni nasadi pa niso odvisni od tipa tal. Zaraščene površine in gozd se pojavljajo na celotnem območju, brez močnega vpliva posameznih spremenljivk. Na podlagi različnih dokumentov in uradnih statistik smo zatem razvili tri različne scenarije rabe tal do leta 2035. V prvem se travniške in kmetijske površine obnovijo na raven iz leta 1985, drugi se osredotoča na širitev poselitvenih in industrijskih površin, tretji pa upošteva smernice trajnostnega razvoja. Po simulaciji z modelom DynaCLUE lahko ugotovimo, da se posamezne rabe tal, neodvisno od velikosti scenarija pojavljajo na podobnih mestih. Ne glede na to dejstvo razviti scenariji pomagajo določiti območja, kjer je večja verjetnost za širjenje naselij ali pa kjer je večja verjetnost opuščanja kmetijskih površin.
Ključne besede: prihodnji scenariji, raba tal, Park Škocjanske jame, logistična regresija, DynaCLUE
Objavljeno v RUNG: 17.10.2019; Ogledov: 5031; Prenosov: 146
 Celotno besedilo (7,32 MB) |
18. Near-Ground Profile of Bora Wind Speed at Razdrto, SloveniaMarija Bervida, Samo Stanič, Klemen Bergant, Benedikt Strajnar, 2019, izvirni znanstveni članek Opis: Southwest Slovenia is a region well-known for frequent episodes of strong and gusty Bora wind, which may damage structures, affect traffic, and poses threats to human safety in general. With the increased availability of computational power, the interest in high resolution modeling of Bora on local scales is growing. To model it adequately, the flow characteristics of Bora should be experimentally investigated and parameterized. This study presents the analysis of wind speed vertical profiles at Razdrto, Slovenia, a location strongly exposed to Bora during six Bora episodes of different duration, appearing between April 2010 and May 2011. The empirical power law and the logarithmic law for Bora wind, commonly used for the description of neutrally stratified atmosphere, were evaluated for 10-min averaged wind speed data measured at four different heights. Power law and logarithmic law wind speed profiles, which are commonly used in high resolution computational models, were found to approximate well the measured data. The obtained power law coefficient and logarithmic law parameters, which are for modeling purposes commonly taken to be constant for a specific site, were found to vary significantly between different Bora episodes, most notably due to different wind direction over complex terrain. To increase modeling precision, the effects of local topography on wind profile parameters needs to be experimentally assessed and implemented.
Ključne besede: Bora wind, logarithmic law, power law, roughness length, wind profile
Objavljeno v RUNG: 04.10.2019; Ogledov: 3483; Prenosov: 109
Celotno besedilo (5,90 MB) |
19. THE ASSESSMENT OF THE VIPAVA RIVER IN THE PERIOD 2018/2019 WITH THE COMPARISON OF THE PERIOD 2009–2011 : Group project: FINAL REPORTNataša Cvetković, Milica Čvorović, Kaja Karner, Klemen Levičnik, Manuel Persoglia, Nika Simčič, Aleksandar Terzić, 2019, končno poročilo o rezultatih raziskav Ključne besede: reka Vipava, kakovost vode, onesnaževanje, namembnost zemljišča, invazivne vrste
Objavljeno v RUNG: 17.09.2019; Ogledov: 3278; Prenosov: 0
Gradivo ima več datotek! Več... |
20. Properties of tropospheric aerosols observed over southwest SloveniaTingyao He, Yingying Chen, Samo Stanič, Klemen Bergant, Fei Gao, Dengxin Hua, 2018, izvirni znanstveni članek Opis: From August to October 2010 lidar measurements of aerosols in the troposphere were performed at Otlica observatory, Slovenia, using a vertical scanning elastic lidar. The lidar data sample, which contains 38 nighttime vertical profiles of the mean aerosol extinction, was combined with continuous ozone concen- tration (O3), particulate matter concentrations (PM) and daily radiosonde data. The obtained radiosonde- and lidar-derived heights of the atmospheric boundary layer (ABL), which varied considerably from day to day, were found to be in good agreement. The mean values of the aerosol optical depth (AOD) at 355 nm, were calculated separately for the ABL and for the free troposphere (FT). A ten-fold increase of the FT AOD was observed during the days with predicted presence of Saharan dust above the lidar site. To correlate AOD values with the type and origin of aerosols, backward trajectories of air-masses above Otlica were modeled using the HYSPLIT model and clustered. High ABL AOD values were found to be correlated with local circulations and slowly approaching air masses from the Balkans and low values with northwestern flows. The highest values correlated with southwestern flows originating in northern Africa.
Ključne besede: Aerosol, Optical depth, Lidar, Atmospheric boundary layer
Objavljeno v RUNG: 22.02.2019; Ogledov: 3831; Prenosov: 0
Gradivo ima več datotek! Več... |
