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252. The Cherenkov Telescope ArrayDaniel Mazin, Christopher Eckner, Gašper Kukec Mezek, Samo Stanič, Serguei Vorobiov, Lili Yang, Gabrijela Zaharijas, Danilo Zavrtanik, Marko Zavrtanik, Lukas Zehrer, 2019, published scientific conference contribution Abstract: The Cherenkov Telescope Array (CTA) is the next generation ground-based observatory
for gamma-ray astronomy at very-high energies. It will be capable of detecting gamma rays in the energy range from 20 GeV to more than 300 TeV with unprecedented precision in energy and directional reconstruction. With more than 100 telescopes of three different types it will be located in the northern hemisphere at La Palma, Spain, and in the southern
at Paranal, Chile. CTA will be one of the largest astronomical infrastructures in the world with open data access and it will address questions in astronomy, astrophysics and fundamental physics in the next decades. In this presentation we will focus on the status
of the CTA construction, the status of the telescope prototypes and highlight some of the physics perspectives.
Keywords: very-high-energy gamma-ray astronomy, Cherenkov Telescope Array, CTA sensitivity, gamma-ray bursts, POpulation Synthesis Theory Integrated project for very high-energy emission
Published in RUNG: 04.12.2023; Views: 547; Downloads: 3
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253. POSyTIVE : a GRB population study for the Cherenkov Telescope ArrayMaria Grazia Bernardini, Christopher Eckner, Gašper Kukec Mezek, Samo Stanič, Serguei Vorobiov, Lili Yang, Gabrijela Zaharijas, Danilo Zavrtanik, Marko Zavrtanik, Lukas Zehrer, 2019, published scientific conference contribution Abstract: One of the central scientific goals of the next-generation Cherenkov Telescope Array
(CTA) is the detection and characterization of gamma-ray bursts (GRBs). CTA will be sensitive to gamma rays with energies from about 20 GeV, up to a few hundred TeV.
The energy range below 1 TeV is particularly important for GRBs. CTA will allow exploration of this regime with a ground-based gamma-ray facility with unprecedented sensitivity.
As such, it will be able to probe radiation and particle acceleration mechanisms at work in GRBs. In this contribution, we describe POSyTIVE, the POpulation Synthesis Theory Integrated project for very high-energy emission. The purpose of the project is to make realistic predictions for the detection rates of GRBs with CTA, to enable studies
of individual simulated GRBs, and to perform preparatory studies for time-resolved
spectral analyses. The mock GRB population used by POSyTIVE is calibrated using the entire 40-year dataset of multi-wavelength GRB observations. As part of this project we explore theoretical models for prompt and afterglow emission of long and short GRBs,
and predict the expected radiative output. Subsequent analyses are performed
in order to simulate the observations with CTA, using the publicly available ctools and Gammapy frameworks. We present preliminary results of the design and implementation
of this project.
Keywords: very-high-energy gamma-ray astronomy, Cherenkov Telescope Array, CTA sensitivity, gamma-ray bursts, population Synthesis Theory, very high-energy emission
Published in RUNG: 04.12.2023; Views: 724; Downloads: 1
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254. Cherenkov Telescope Array Science : a multi-wavelength and multi-messenger perspectiveUlisses Barres de Almeida, Christopher Eckner, Gašper Kukec Mezek, Samo Stanič, Serguei Vorobiov, Lili Yang, Gabrijela Zaharijas, Danilo Zavrtanik, Marko Zavrtanik, Lukas Zehrer, 2019, published scientific conference contribution Abstract: The Cherenkov Telescope Array (CTA) will be the major global observatory for
VHE gamma-ray astronomy over the next decade and beyond. It will be an explorer
of the extreme universe, with a broad scientific potential: from understanding the role of relativistic cosmic particles, to the search for dark matter. Covering photon energies from 20 GeV to 300 TeV, and with an angular resolution unique in the field, of about 1 arc min, CTA will improve on all aspects of the performance with respect to current instruments, surveying the high energy sky hundreds of times faster than previous TeV telescopes,
and with a much deeper view. The very large collection area of CTA makes it an important probe of transient phenomena. The first CTA telescope has just been inaugurated in the Canary Islands, Spain, and as more telescopes are added in the coming years, scientific operation will start. It is evident that CTA will have important synergies with many of the
new generation astronomical and astroparticle observatories. In this talk we will review
the CTA science case from the point of view of its synergies with other instruments and
facilities, highlighting the CTA needs in terms of external data, as well as the opportunities and strategies for cooperation to achieve the basic CTA science goals.
Keywords: very-high-energy gamma-ray astronomy, Cherenkov Telescope Array, CTA performances, transient VHE sources, CTA science
Published in RUNG: 04.12.2023; Views: 670; Downloads: 4
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255. Tuning the activity of iron phosphide electrocatalysts for sustainable energy conversionSaim Emin, Takwa Chouki, Manel Machreki, 2023, published scientific conference contribution abstract (invited lecture) Abstract: Electrocatalysis is a promising approach for the sustainable conversion of renewable energy sources, such as solar and wind power, into chemical energy that can be stored and used on demand. By harnessing renewable electricity to drive electrochemical reactions, we can produce fuels and chemicals in a way that is both clean and cost-effective. As we continue to develop new electrocatalytic materials and improve the efficiency of existing processes, the potential for electrocatalysis to transform our energy system will only continue to grow.
We report the use of iron phosphide (Fe2P, FeP) in several electrocatalytic applications, such as reduction of nitrate ions (NO3), hydrogen and oxygen evolution studies. The electrochemical reduction of the nitrate ion (NO3), a widespread water pollutant, to valuable ammonia (NH3) is a promising approach to achieving green energy conservation. Particularly, FeP and Fe2P phases were successfully demonstrated as efficient catalysts for NH3 generation. Detection of the in-situ formed product using a bi-potentiostat was achieved by electrooxidation of NH3 to nitrogen (N2) on a Pt electrode. The Fe2P catalyst exhibits the highest Faradaic efficiency (96%) for NH3 generation with a yield (0.25 mmol h−1 cm-−2 or 2.10 mg h−1 cm−2) at −0.55 V vs. reversible hydrogen electrode (RHE). To get relevant information about the reaction mechanisms and the fundamental origins behind the better performance of Fe2P, density functional theory (DFT) calculations were performed.
Keywords: Fe2P, FeP, electrocatalysis, NH3 reduction, counter electrode
Published in RUNG: 04.12.2023; Views: 490; Downloads: 4
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256. A novel multi-functional thiophene-based organic cation as passivation, crystalline orientation, and organic spacer agent for low-dimensional 3D/1D perovskite solar cellsAli Semerci, Ali Buyruk, Saim Emin, Rik Hooijer, Daniela Kovacheva, Peter Mayer, Manuel A. Reus, Dominic Blätte, Marcella Günther, Nicolai F. Hartmann, 2023, original scientific article Abstract: Recently, the mixed-dimensional (3D/2D or 3D/1D) perovskite solar cellsusing small organic spacers have attracted interest due to their outstandinglong-term stability. Here, a new type of thiophene-based organic cation2-(thiophene-2yl-)pyridine-1-ium iodide (ThPyI), which is used to fabricatemixed-dimensional 3D/1D perovskite solar cells, is presented. TheThPyI-based 1D perovskitoid is applied as a passivator on top of a 3D methylammonium lead iodide (MAPI) to fabricate surface-passivated 3D/1Dperovskite films or added alone into the 3D perovskite precursor to generatebulk-passivated 3D MAPI. The 1D perovskitoid acts as a passivating agent atthe grain boundaries of surface-passivated 3D/1D, which improves the powerconversion efficiency (PCE) of the solar cells. Grazing incidence wide-angleX-ray scattering (GIWAXS) studies confirm that ThPyI triggers the preferentialorientation of the bulk MAPI slabs, which is essential to enhance chargetransport. Champion bulk-passivated 3D and surface-passivated 3D/1Ddevices yield 14.10% and 19.60% PCE, respectively. The bulk-passivated 3Doffers favorable stability, with 84% PCE retained after 2000 h withoutencapsulation. This study brings a new perspective to the design of organicspacers having a different binding motif and a passivation strategy to mitigatethe impact of defects in hybrid 3D/1D perovskite solar cells.A. Semerci, A. Buyruk, R. Hooijer, P. Mayer, D. Blätte, M. Günther, T. Bein,T. AmeriDepartment of Chemistry and Center for NanoScience (CeNS)Ludwig-Maximilians-Universität MünchenButenandtstrasse 5–13 (E), 81377 Munich, GermanyE-mail:tayebeh.ameri@ed.ac.ukS.EminMaterialsResearchLaboratoryUniversityofNovaGoricaVipavska13c,Ajdovšˇcina5270,SloveniaThe ORCID identification number(s) for the author(s) of this articlecan be found under https://doi.org/10.1002/adom.202300267© 2023 The Authors. Advanced Optical Materials published byWiley-VCH GmbH. This is an open access article under the terms of theCreative Commons Attribution-NonCommercial License, which permitsuse, distribution and reproduction in any medium, provided the originalwork is properly cited and is not used for commercial purposes.DOI: 10.1002/adom.2023002671. IntroductionDuring the last decade, 3D organic–inorganic halide perovskites (OIHPs) haveemerged as promising absorber materialsfor photovoltaic applications due to theirsuperior properties such as high absorp-tion coefficient, long diffusion length ofthe charge carriers, fast charge transport,and tunable bandgap. The 3D OIHPs havedemonstrated rapid increase in powerconversion efficiency (PCE) from 3.8% to25.2%.[1–9]On the other hand, their mod-erate intrinsic stability against moistureand heat still has been a concern with aview on possible commercialization.[10–14]Instability of the 3D methyl ammoniumlead iodide (MAPI) perovskite is assumedto be due to its crystalline structure. Ionicmigration is now well recognized to affectthe photovoltaic properties of perovskitesolar cells. Especially, the ionic migrationcauses the generation and displacement ofvacancies in perovskite materials. OIHPsare mixed ionic–electronic conductors withiodide ions as the majority of ionic carriers.D. KovachevaInstitute of General and Inorganic ChemistryBulgarian Academy of SciencesSofia 1113, BulgariaM. A. Reus, P. Müller-BuschbaumTUM School of Natural SciencesDepartment of PhysicsChair for Functional MaterialsTechnical University of MunichJames-Franck-Str. 1, 85748 Garching, GermanyN. F. HartmannAttocube systems AGNanoscale AnalyticsneaspecEglfinger Weg 2, 85540 Haar, GermanyS. Lotfi, J. P. HofmannSurface Science LaboratoryDepartment of Materials and Earth SciencesTechnical University of DarmstadtOtto-Berndt-Str. 3, 64287 Darmstadt, GermanyAdv. Optical Mater.2023,11, 23002672300267 (1 of 13)© 2023 The Authors. Advanced Optical Materials published by Wiley-VCH GmbH
Keywords: perovskites, solar cells, passivation
Published in RUNG: 04.12.2023; Views: 469; Downloads: 2
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257. Efficient electrochemical nitrogen fixation at iron phosphide (Fe_2P) catalyst in alkaline mediumBeata Rytelewska, Anna Chmielnicka, Takwa Chouki, Magdalena Skunik-Nuckowka, Shaghayegh Naghdi, Dominik Eder, Aleksandra Michalowska, Tomasz Ratajczyk, Egon Pavlica, Saim Emin, 2023, original scientific article Abstract: A catalytic system based on iron phosphide (Fe2P) has exhibited electrocatalytic activity toward N2-reduction reaction in alkaline medium (0.5 mol dm−3 NaOH). Based on voltammetric stripping-type electroanalytical measurements, Raman spectroscopic and spectrophotometric data, it can be stated that the Fe2P catalyst facilitates conversion of N2 to NH3, and the process is fairly selective with respect to the competing hydrogen evolution. A series of diagnostic electrocatalytic experiments (utilizing platinum nanoparticles and HKUST-1) have been proposed and performed to control purity of nitrogen gas and to probe presence of potential contaminants such as ammonia, nitrogen oxo-species and oxygen. On the whole, the results are consistent with the view that the interfacial reduced-iron (Fe0) centers, while existing within the network of P sites, induce activation and reduction of nitrogen, parallel to the water splitting (reduction) to hydrogen. It is apparent from Tafel plots and impedance measurements that mechanism and dynamics of nitrogen reduction depends on the applied electroreduction potential. The catalytic system exhibits certain tolerance with respect to the competitive hydrogen evolution and gives (during electrolysis at -0.4 V vs. RHE) the Faradaic efficiency, namely, the selectivity (molar) efficiency, toward production of NH3 on the level of 60%. Under such conditions, the NH3-yield rate has been found to be equal to 7.5 µmol cm−2 h−1 (21 µmol m−2 s−1). By referring to classic concepts of electrochemical kinetic analysis, the rate constant in heterogeneous units has been found to be on the moderate level of 1-2*10−4 cm s−1 (at -0.4 V). The above mentioned iron-phosphorous active sites, which are generated on surfaces of Fe2P particles, have also been demonstrated to exhibit strong catalytic properties during reductions of other electrochemically inert reactants, such as oxygen, nitrites and nitrates.
Keywords: nitrogen reduction, alkaline medium, iron phosphide catalyst, ammonia, electrochemical determinations
Published in RUNG: 30.11.2023; Views: 603; Downloads: 4
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260. Analysis of circular economy implementation in local communityHenrik Gjerkeš, Marjana Šijanec-Zavrl, 2023, published scientific conference contribution Abstract: An analysis of the implementation of the comprehensive circular economy concept in Slovenia is presented. The concept used takes advantage of the endogenous potential of the area in which it is implemented and is aimed at the development of the forest-wood chain in the municipality of Kočevje. The results of the current 7-year implementation of the circular economy have shown a balanced fulfilment of all three dimensions of sustainable development: sustainable management of forests and products (FSC, PEFC), financial viability of operations and increased contributions to all public treasuries - even in time of crisis, more than 50 new green workplaces, increased interest of private investors, promotion of tourism, and last but not least - positive multiplicative effects on the quality of life of the citizens of Kočevje. Cyclicality is ensured in this way and the circular economy successfully fulfils its purpose.
Keywords: circular economy, sustainable development, implementation
Published in RUNG: 27.11.2023; Views: 536; Downloads: 5
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