311. Characterizing the sources of ambient ▫$PM_10$▫ organic aerosol in urban and rural Catalonia, SpainMarten in ʼt Veld, Peeyush Khare, Yufang Hao, Cristina Reche, Noemí Perez, Andrés Alastuey, Jesús Yus-Díez, Nicolas Marchand, Andre S. H. Prevot, Xavier Querol, Kaspar Rudolf Daellenbach, 2023, izvirni znanstveni članek Ključne besede: PM10, chemical composition, organic aerosols, SOA, source apportionment
Objavljeno v RUNG: 23.10.2023; Ogledov: 847; Prenosov: 6
 Celotno besedilo (7,72 MB)
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312. Effects of Photodegradation in TLS Measurements: Troubleshooting and Applications in Photochemistry and PhotocatalysisMladen Franko, 2023, objavljeni povzetek znanstvenega prispevka na konferenci (vabljeno predavanje) Opis: Most analytical applications of thermal lens spectrometry (TLS) and related theoretical models consider absorbance of the sample constant during a single excitation by the pump laser beam. For photolabile analytes intensive excitation light can cause photodegradation, which significantly affects the results of TLS measurements.
Theoretical models have been developed to account for changes in concentration and consequent changes in absorbance, caused by chemical reactions of different orders. Furthermore, abnormal TLS signal transients were observed for fast photochemical reactions on millisecond time scale, and the contributions of photodegradation as well as molecular diffusion were analyzed in detail. It has also been demonstrated that such effects can be reduced by performing TLS measurements in flowing systems such as in the case of flow injection analysis (FIA) or microfluidics.
These findings were utilized to study the kinetics of chemical reactions, processes such as photostability of the soybean oil and thermal stability of biodiesel, or to improve the sensitivity of TLS detection in case of photolabile analytes. Furthermore, in combination with the concept of biomolecular recognition, FIA-TLS was exploited to study the efficiency of photocatalytic degradation of some neurotoxic substances such as organophosphate insecticides and revealed the formation of even more toxic degradation products. High sensitivity of TLS has enabled discrimination between photocatalytic and photosensitization mechanisms in photocatalytic degradation of textile dyes as well as between photodegradation and photocatalysis as will be demonstrated by the results of latest research in this field.
Ključne besede: Spektrometrija TLS, fotolabilnost, CrIVI), fotokataliza, fotorazgradnja
Objavljeno v RUNG: 23.10.2023; Ogledov: 1341; Prenosov: 0
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313. Recent Progress and Applications of Thermal Lens Spectrometry and Photothermal Beam Deflection Techniques in Chemical Analysis and Materials' CharacterizationMladen Franko, 2023, predavanje na tuji univerzi Opis: Initially the theoretical background relevant to recent developments of thermal lens spectrometry (TLS) which include TLS detection in liquid chromatography and in microfluidic flow injection analysis (μFIA) and to non-contact and non-destructive characterization of composite materials by beam deflection spectrometry (BDS) is presented. The advantages and basic characteristics of the TLS and BDS techniques are illustrated by presenting applications such as the determination of free bilirubin in endothelial cells by HPLC-TLS, studies of diffusion in Taylor-type microfluidic flows by thermal lens microscopy (TLM), μFIA-TLM detection of microcystin-LR and Cr(VI) in waters, and by the dept profiling of multi-layered coatings of orthopaedic implants.
In the main part of the presentation the results of joint MU-UNG research are presented with emphasis on BDS and TLS characterisation of biocomposite materials from cellulose and chitosan or keratin with added Ag nanoparticles, sporopollenin capsules or antibiotics. The focus is on BDS determination of thermal parameters including thermal diffusivity and related properties relevant for medical applications, such as porosity and surface roughness, as well as on the TLS detection of Ag and other nanoparticles applied in studies of nanoparticle leaching from biocomposites.
Ključne besede: Optotermična spektrometrija, TLS, BDS, kemijska analiza, karakterizacija materialov, biokompoziti
Objavljeno v RUNG: 23.10.2023; Ogledov: 635; Prenosov: 1
Celotno besedilo (25,02 MB) |
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318. Silica-coated ▫$Bi2_Se_3$▫ topological insulator nanoparticles: preserving their optical properties and make them biocompatible : preserving their optical properties and make them biocompatibleBlaž Belec, Nina Kostevšek, Giulia Della Pelle, Sebastjan Nemec, Slavko Kralj, Martina Bergant Marušič, Sandra Gardonio, Mattia Fanetti, Matjaž Valant, 2023, objavljeni povzetek znanstvenega prispevka na konferenci Ključne besede: topological insulator, bismuth selenide, photo-thermal material, biocompatibility, nanoparticles
Objavljeno v RUNG: 19.10.2023; Ogledov: 792; Prenosov: 3
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319. Ferrite-based magnets by high pressure consolidationCesár De Julián Fernández, Blaž Belec, Aleksander Učakar, Petra Jenuš, 2023, objavljeni povzetek znanstvenega prispevka na konferenci Opis: M-type hexaferrite magnets constitute together the rare-earth magnets the most employed magnets in the
world. Even if ferrite magnets have smaller energy product and lower magnetization saturation than rare-earth
permanent magnets (PMs), currently ferrite magnets represent the most widely used PMs, covering 80% of the
PM market production [1,2]. Recently, a strong effort is being performed to improve the magnetic properties
of ferrites with the scope of substituting partially rare-earth magnets. Most of the strategies involve the
nanostructuration of the ferrites and/or the development of hybrid compounds [3]. A bottleneck for the
production of these magnets is that standard sintering process requires high temperatures and oxidizing
atmosphere that produces the destruction of the nanostructure and several chemical changes. Different novel
strategies as out-of-equilibrium or cold sintering processes are mainly considered[2,4].
In our presentation we will show the production of dense ferrite-based magnets by high pressure multi-Anvil
press at low temperatures. This press applies quasi-isotropic pressures in the range up to 20 GPa and
temperatures up to 1200°C. We demonstrate that the consolidation of micrometric hexaferrite (SrFe12O19)
powders is possible at temperatures below 1000°C, below the standard sintering temperatures. In addition,
dense hybrid magnets were obtained composed of micrometric hexaferrites and soft high magnetization metal
Fe or FeCo NPs applying pressures up to 6 GPa and low temperatures (250°C). A deep study, including
structural, morphological and magnetic characterizations, has been performed to determine the influence of the
temperature and pressure consolidation conditions in the properties of these novel magnets. Magnetic
characterizations show that hybrid magnets exhibit larger magnetization than ferrites and single step hysteresis
loops. Single Point Detection characterizations indicate that the anisotropy field of the hybrid magnets is similar
to that of the ferrite magnets. These results suggest that the two moieties componing the high pressure
consolidated magnets have similar properties than the original micro and nano powders, but they are magnetic
coupled during the reversal process. High pressure consolidation appears as a promising technique to obtain
nano-based metal-oxide hybrid magnets with promising hard properties.
Ključne besede: ferrite magnets, high pressure consolidation, low temperatures
Objavljeno v RUNG: 19.10.2023; Ogledov: 795; Prenosov: 5
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320. 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: 747; Prenosov: 0
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