1. Effect of shell thickness on the exchange bias blocking temperature and coercivity in Co-CoO core-shell nanoparticlesSenoy Thomas, K. Reethu, Thanveer Thajudheen, M. T. Z. Myint, S. H. Al-Harthi, 2017, izvirni znanstveni članek Opis: The exchange bias blocking temperature distribution of naturally oxidized Co-CoO core-shell nanoparticles exhibits two distinct signatures. These are associated with the existence of two magnetic entities which are responsible for the temperature dependence of an exchange bias field. One is from the CoO grains which undergo thermally activated magnetization reversal. The other is from the disordered spins at the Co-CoO interface which exhibits spin-glass-like behavior. We investigated the oxide shell thickness dependence of the exchange bias effect. For particles with a 3 nm thick CoO shell, the predominant contribution to the temperature dependence of exchange bias is the interfacial spin-glass layer. On increasing the shell thickness to 4 nm, the contribution from the spin-glass layer decreases, while upholding the antiferromagnetic grain contribution. For samples with a 4 nm CoO shell, the exchange bias training was minimal. On the other hand, 3 nm samples exhibited both the training effect and a peak in coercivity at an intermediate set temperature Ta. This is explained using a magnetic core-shell model including disordered spins at the interface.
Ključne besede: exchange interactions, magnetic ordering, ferromagnetic materials, magnetic materials, polycrystalline material, thin films, nanoparticle, nuclear structure models, oxides, transition metals
Objavljeno v RUNG: 13.12.2024; Ogledov: 288; Prenosov: 2
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2. Modelling water for calorimetry of proteinsKnarik Yeritsyan, Artem Badasyan, 2023, objavljeni povzetek znanstvenega prispevka na konferenci Opis: Differential Scanning Calorimetry (DSC) is a powerful technique used to study the thermal stability and unfolding of proteins. DSC provides the excess heat capacity profile and is used to study the thermodynamics of a given protein. By fitting DSC data to the model, researchers can obtain valuable information about the thermodynamics of protein folding and unfolding, which can help them better understand protein structure, stability, and function.
Based on Hamiltonian representation of ZB model and using the solvent effects we derived an expression for heat capacity in proteins and successfuly fit it to experimental data. As we show, our model provides a better fit to experimental data, as compared to the 2-state model. The model we propose takes into account also water effects and we show that it fits better to experimental data giving inter- and intra-molecular H-bonding energies instead of reporting only one total enthalpy.
Ključne besede: Zimm-Bragg model, water model, helix-coil transition, protein folding, differential scanning calorimetry
Objavljeno v RUNG: 18.10.2023; Ogledov: 2063; Prenosov: 0
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3. DESIGN AND IMPLEMENTATION OF THE SUPERVISORY MODULE AS PART OF A SYSTEM FOR CONDITION MONITORING AND CONTROL OF SOLID OXIDE ELECTROLYSIS CELL SYSTEMSAmina Uglješa, 2023, magistrsko delo Opis: Hydrogen is playing an important role in many sectors of modern economy (green vehicles, energy conversion and storage in electrical grids, processing industry). Solid oxide electrolysis cell (SOEC) is an emerging technology for the production of hydrogen from steam and electrical energy as well as for renewable energies storage. Unfortunately, operating at high current and electrical transients cause degradation that leads to premature end of life. A remedy is to implement a hardware module capable to perform online condition monitoring and optimization of SOEC systems resulting in improved overall performance and extended lifetime. That is expected to significantly expand their deployment on the market.
However, very little has been done so far. The H2020 project REACTT seems to be one of the first attempts to build an embedded system for monitoring, diagnosis, prognostics, and control (MDPC) for SOEC system. The underlying master's thesis contributes to the REACTT project in the segment related to the supervision of different modules of the MDPC system. The supervisor module is aimed to orchestrate the operation of various functional modules (agents) such as data acquisition, system optimization, diagnosis, prognostics, and mitigation. The thesis focuses on the design of the supervisor module and its implementation on a control platform based on Raspberry Pi 4. The main contributions of the thesis are twofold. First, the dynamic operation of the supervisor modelled by using the state transition diagram (STD). Second, the code for implementation of the supervisor on the target platform done in Python in a way that complies with the requirements imposed in the project.
Ključne besede: supervisor, module, agent, method, solid oxide electrolysis cell system, diagnosis, prognostics, real-time optimization, Python programming, state transition diagram
Objavljeno v RUNG: 20.06.2023; Ogledov: 1998; Prenosov: 30
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4. A comparative study of nanolaminate CrN/Mo2N and CrN/W2N as hard and corrosion resistant coatingsMarco Beltrami, Andraž Mavrič, Simone Dal Zilio, Mattia Fanetti, Gregor Kapun, Marco Lazzarino, Orfeo Sbaizero, Miha Čekada, 2013, izvirni znanstveni članek Opis: Nanolaminate coatings (NLC) consisting of alternated CrN coupled with either cubic tungsten nitride (β-W2N) or molybdenum nitride (γ-Mo2N) were deposited on cold worked tool steel substrates using reactive DC reactive magnetron sputtering for improved mechanical and corrosion resistance. The CrN/γ-Mo2N and CrN/β-W2N nanolaminate systems were found to perform better than the corresponding single-layer systems, with both mechanical and electrochemical properties improving by decreasing the individual layer thickness from 100 to 5 nm. The CrN/β-W2N NLC combined the high hardness value of W2N with the low corrosion current of CrN. The CrN/γ-Mo2N NLC showed synergistic improvements consisting of both higher hardness and lower corrosion currents with respect to the constituent materials alone. The dependence of mechanical and corrosion properties on the bilayer period is discussed in terms of the grain size, residual stresses and texture of the constituent materials and the nanostructured character of the multilayer architecture.
Ključne besede: Nanolayered coatings, Transition metal nitrides, Sputtering, Nanoindentation, Corrosion resistance, Mechanical properties
Objavljeno v RUNG: 12.01.2023; Ogledov: 2188; Prenosov: 0
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8. System size dependence in the Zimm-Bragg model : partition function limits, transition temperature and intervalArtem Badasyan, 2021, izvirni znanstveni članek Opis: Within the recently developed Hamiltonian formulation of the Zimm and Bragg model
we re-evaluate several size dependent approximations of model partition function. Our size analysis
is based on the comparison of chain length N with the maximal correlation (persistence) length ξ of
helical conformation. For the first time we re-derive the partition function of zipper model by taking
the limits of the Zimm–Bragg eigenvalues. The critical consideration of applicability boundaries for
the single-sequence (zipper) and the long chain approximations has shown a gap in description for
the range of experimentally relevant chain lengths of 5–10 persistence lengths ξ. Correction to the
helicity degree expression is reported. For the exact partition function we have additionally found,
that: at N/ξ ≈ 10 the transition temperature T m reaches its asymptotic behavior of infinite N; the
transition interval ∆T needs about a thousand persistence lengths to saturate at its asymptotic, infinite
length value. Obtained results not only contribute to the development of the Zimm–Bragg model,
but are also relevant for a wide range of Biotechnologies, including the Biosensing applications.
Ključne besede: Zimm-Bragg model, helix-coil transition, zipper model
Objavljeno v RUNG: 17.06.2021; Ogledov: 3319; Prenosov: 87
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9. Dissecting Mott and charge-density wave dynamics in the photoinduced phase of 1T-TaS[sub]2Alberto Simoncig, Matija Stupar, Barbara Ressel, Tanusree Saha, Primož Rebernik Ribič, Giovanni De Ninno, 2021, izvirni znanstveni članek Opis: The two-dimensional transition-metal dichalcogenide 1T−TaS2 is a complex material standing out for its puzzling low temperature phase marked by signatures amenable to both Mott-insulating and charge-density wave states. Electronic Mott states, coupled to a lattice, respond to coherent optical excitations via a modulation of the lower (valence) Hubbard band. Such dynamics is driven by strong electron-phonon coupling and typically lasts for tens of picoseconds, mimicking coherent structural distortions. Instead, the response occurring at the much faster timescale, mainly dominated by electronic many-body effects, is still a matter of intense research. By performing time- and angle-resolved photoemission spectroscopy, we investigated the photoinduced phase of 1T−TaS2 and found out that its lower Hubbard band promptly reacts to coherent optical excitations by shifting its binding energy towards a slightly larger value. This process lasts for a time comparable to the optical pump pulse length, mirroring a transient change of the onsite Coulomb repulsion energy (U). Such an observation suggests that the correction to the bare value of U, ascribed to the phonon-mediated screening which slightly opposes the Hubbard repulsion, is lost within an interval of a few tens of femtoseconds and can be understood as a fingerprint of electronic states largely decoupled from the lattice. Additionally, these results enforce the hypothesis, envisaged in the current literature, that the transient photoinduced states belong to a sort of crossover phase instead of an equilibrium metallic one.
Ključne besede: ultrafast phenomena, time resolved photoemission, strongly correlated systems, transition metal dichalcogenide
Objavljeno v RUNG: 13.04.2021; Ogledov: 3546; Prenosov: 0
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