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222. An in situ proton filter covalent organic framework catalyst for highly efficient aqueous electrochemical ammonia productionKayaramkodath C. Ranjeesh, Sukhjot Kaur, Abdul K. Mohammed, Safa Gaber, Divyani Gupta, Khaled Badawy, Mohamed Aslam, Nirpendra Singh, Tina Škorjanc, Matjaž Finšgar, 2023, izvirni znanstveni članek Opis: The electrocatalytic nitrogen reduction reaction (NRR) driven by renewable electricity provides a green synthesis route for ammonia (NH3) production under ambient conditions but suffers from a low conversion yield and poor Faradaic efficiency (F.E.) because of strong competition from hydrogen evolution reaction (HER) and the poor solubility of N2 in aqueous systems. Herein, an in situ proton filter covalent organic framework catalyst (Ru-Tta-Dfp) is reported with inherent Ruthenium (Ru) sites where the framework controls reactant diffusion by suppressing proton supply and enhancing N2 flux, causing highly selective and efficient catalysis. The smart catalyst design results in a remarkable ammonia production yield rate of 2.03 mg h−1 mgcat−1 with an excellent F.E. of ≈52.9%. The findings are further endorsed with the help of molecular dynamics simulations and control COF systems without in situ proton filter feasibility. The results point to a paradigm shift in engineering high-performance NRR electrocatalysts for more feasible green NH3 production. Ključne besede: covalent organic frameworks, ammonia, electrochemical synthesis, electrochemistry, nitrogen reduction reaction, ruthenium Objavljeno v RUNG: 11.12.2023; Ogledov: 454; Prenosov: 5 Celotno besedilo (2,77 MB) Gradivo ima več datotek! Več... |
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224. An improved low-input resistance folded-cascode transimpedance amplifier for giga-bit per second optical communication front-endsSoorena Zohoori, Ahmad Hosseini, Mehrdad Amirkhan Amirkhan Dehkordi, Seyed Mehdi Mirsanei, 2023, izvirni znanstveni članek Opis: The present study is devoted to articulating a modified folded‐cascode circuit, to make folded‐cascode structures an attractive configuration as a transimpedance amplifier (TIA) for being employed in Giga‐bit per second optical communication receiver systems. Giga‐bps communication receivers are highly necessitating circuits to isolate the input parasitic capacitance of the photodiode. The present modification makes folded cascodes comparable to the famous regulated cascode (RGC) structures by isolating this parasitic capacitor almost by the same quantity. The system is shown to be capable of operating at 2.5 Gbps up to 8 Gbps data rate with a fixed bandwidth. The paper analyzes and evaluates the designed circuit mathematically, and the obtained simulated results from Cadence using TSMC 65 nm CMOS validate the suitability of the modified circuit as a TIA. Ključne besede: improved folded-cascode, low input resistance, low noise, optical receiver, transimepdance amplifier Objavljeno v RUNG: 08.12.2023; Ogledov: 460; Prenosov: 2 Povezava na datoteko Gradivo ima več datotek! Več... |
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227. 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, objavljeni znanstveni prispevek na konferenci Opis: 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. Ključne besede: very-high-energy gamma-ray astronomy, Cherenkov Telescope Array, CTA sensitivity, gamma-ray bursts, POpulation Synthesis Theory Integrated project for very high-energy emission Objavljeno v RUNG: 04.12.2023; Ogledov: 435; Prenosov: 3 Celotno besedilo (27,92 MB) Gradivo ima več datotek! Več... |
228. 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, objavljeni znanstveni prispevek na konferenci Opis: 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. Ključne besede: very-high-energy gamma-ray astronomy, Cherenkov Telescope Array, CTA sensitivity, gamma-ray bursts, population Synthesis Theory, very high-energy emission Objavljeno v RUNG: 04.12.2023; Ogledov: 585; Prenosov: 1 Celotno besedilo (1,50 MB) Gradivo ima več datotek! Več... |
229. 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, objavljeni znanstveni prispevek na konferenci Opis: 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. Ključne besede: very-high-energy gamma-ray astronomy, Cherenkov Telescope Array, CTA performances, transient VHE sources, CTA science Objavljeno v RUNG: 04.12.2023; Ogledov: 523; Prenosov: 4 Celotno besedilo (1,16 MB) Gradivo ima več datotek! Več... |
230. Tuning the activity of iron phosphide electrocatalysts for sustainable energy conversionSaim Emin, Takwa Chouki, Manel Machreki, 2023, objavljeni povzetek znanstvenega prispevka na konferenci (vabljeno predavanje) Opis: 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. Ključne besede: Fe2P, FeP, electrocatalysis, NH3 reduction, counter electrode Objavljeno v RUNG: 04.12.2023; Ogledov: 418; Prenosov: 4 Povezava na datoteko Gradivo ima več datotek! Več... |