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Претрага радова објављених у периоду (2019-2020):
2020 |
Milenković, D A; Dimić, D S; Avdović, E H; Amić, A D; Marković, Dimitrić J M; Marković, Z S Advanced oxidation process of coumarins by hydroxyl radical: Towards the new mechanism leading to less toxic products Journal Article Chemical Engineering Journal, 395 , 2020. @article{Milenković2020, title = {Advanced oxidation process of coumarins by hydroxyl radical: Towards the new mechanism leading to less toxic products}, author = {D A Milenković and D S Dimić and E H Avdović and A D Amić and J M Dimitrić Marković and Z S Marković}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85083333113&doi=10.1016%2fj.cej.2020.124971&partnerID=40&md5=66e7cb80160ef8312eccd626299c8eb9}, doi = {10.1016/j.cej.2020.124971}, year = {2020}, date = {2020-01-01}, journal = {Chemical Engineering Journal}, volume = {395}, abstract = {The excessive use of coumarins and their derivatives is becoming an ecological concern due to their toxicity towards different organisms. One of the possible ways of their removal is the advanced oxidation processes. The oxidative breakdown of 4-hydroxycoumarin and its two derivatives, induced by a very powerful oxidizer hydroxyl radical (HO•), was investigated experimentally and theoretically. The new mechanism, namely radical adduct formation followed by hydrogen atom abstraction (RAF-HAA), was proposed. The thermodynamic parameters and rate constants, calculated by the Transition State Theory for several active positions indicated a possible reaction in which less toxic products were obtained, as confirmed by the ecotoxicity assessment. The mechanism included the reaction with two HO• and the introduction of an additional OH group to the structure. These results were compared to the more common mechanism that includes HAA between the OH group of 4-hydroxycoumarin and HO•. Based on the Quantum Theory of Atoms in Molecules and Natural Bond Orbital theory the exo-coupled electron transfer (PCET) mechanism was pointed out as a dominant pathway. Radical addiction with another HO•, followed by keto-enol tautomerism, led to the formation of the stable final product, identical to one obtained in the RAF-HAA mechanism. The reaction rates for RAF-HAA were higher then those for pure HAA and reactions were more spontaneous, therefore leading to the conclusion that the newly proposed mechanism could be a dominant pathway for the aromatic molecules’ breakdown in the advanced oxidation processes. © 2020}, keywords = {}, pubstate = {published}, tppubtype = {article} } The excessive use of coumarins and their derivatives is becoming an ecological concern due to their toxicity towards different organisms. One of the possible ways of their removal is the advanced oxidation processes. The oxidative breakdown of 4-hydroxycoumarin and its two derivatives, induced by a very powerful oxidizer hydroxyl radical (HO•), was investigated experimentally and theoretically. The new mechanism, namely radical adduct formation followed by hydrogen atom abstraction (RAF-HAA), was proposed. The thermodynamic parameters and rate constants, calculated by the Transition State Theory for several active positions indicated a possible reaction in which less toxic products were obtained, as confirmed by the ecotoxicity assessment. The mechanism included the reaction with two HO• and the introduction of an additional OH group to the structure. These results were compared to the more common mechanism that includes HAA between the OH group of 4-hydroxycoumarin and HO•. Based on the Quantum Theory of Atoms in Molecules and Natural Bond Orbital theory the exo-coupled electron transfer (PCET) mechanism was pointed out as a dominant pathway. Radical addiction with another HO•, followed by keto-enol tautomerism, led to the formation of the stable final product, identical to one obtained in the RAF-HAA mechanism. The reaction rates for RAF-HAA were higher then those for pure HAA and reactions were more spontaneous, therefore leading to the conclusion that the newly proposed mechanism could be a dominant pathway for the aromatic molecules’ breakdown in the advanced oxidation processes. © 2020 |
Milenković, D; Avdović, E; Dimić, D; Sudha, S; Ramarajan, D; Milanović, ; Trifunović, S; Marković, Z S Journal of Molecular Structure, 1209 , 2020. @article{Milenković2020b, title = {Vibrational and Hirshfeld surface analyses, quantum chemical calculations, and molecular docking studies of coumarin derivative 3-(1-m-toluidinoethylidene)-chromane-2,4-dione and its corresponding palladium(II) complex}, author = {D Milenković and E Avdović and D Dimić and S Sudha and D Ramarajan and Milanović and S Trifunović and Z S Marković}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85080037349&doi=10.1016%2fj.molstruc.2020.127935&partnerID=40&md5=b6333b566889ba33eb9c616fd994d2cc}, doi = {10.1016/j.molstruc.2020.127935}, year = {2020}, date = {2020-01-01}, journal = {Journal of Molecular Structure}, volume = {1209}, abstract = {In this study, the analysis of vibrational spectra and electronic structure of 3-(1-m-toluidinoethylidene)-chromane-2,4-dione (L1) and its corresponding palladium (II) complex (C1) was employed to characterize the spectroscopic behavior and molecular structure of the investigated compounds by applying B3LYP-D3BJ/6-311+G(d,p) level of theory. Hirshfeld surface analysis of the intermolecular interactions in crystal structure L1 was performed. The AIM and NBO analyses were used to understand the type, nature, and strength of intramolecular interactions and to examine the electronic structure of the studied molecules. The calculation of HOMO and LUMO energies was applied in order to present the charge transfer within the molecule. The computational molecular docking studies of title compounds was performed with special emphasis on differences in binding of ligand and complex. © 2020}, keywords = {}, pubstate = {published}, tppubtype = {article} } In this study, the analysis of vibrational spectra and electronic structure of 3-(1-m-toluidinoethylidene)-chromane-2,4-dione (L1) and its corresponding palladium (II) complex (C1) was employed to characterize the spectroscopic behavior and molecular structure of the investigated compounds by applying B3LYP-D3BJ/6-311+G(d,p) level of theory. Hirshfeld surface analysis of the intermolecular interactions in crystal structure L1 was performed. The AIM and NBO analyses were used to understand the type, nature, and strength of intramolecular interactions and to examine the electronic structure of the studied molecules. The calculation of HOMO and LUMO energies was applied in order to present the charge transfer within the molecule. The computational molecular docking studies of title compounds was performed with special emphasis on differences in binding of ligand and complex. © 2020 |
Ilić, Medić M; Bundaleski, N; Ivanović, N; Teodoro, O M N D; Rakočević, Z; Minić, D; Romčević, N; Radisavljević, I XPS measurements of air-exposed Cd(Zn)1–xFexTe1–ySey surfaces revisited Journal Article Vacuum, 176 , 2020. @article{MedićIlić2020, title = {XPS measurements of air-exposed Cd(Zn)1–xFexTe1–ySey surfaces revisited}, author = {M Medić Ilić and N Bundaleski and N Ivanović and O M N D Teodoro and Z Rakočević and D Minić and N Romčević and I Radisavljević}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85082390920&doi=10.1016%2fj.vacuum.2020.109340&partnerID=40&md5=61cbfffe3734322d74f90fc164992f5f}, doi = {10.1016/j.vacuum.2020.109340}, year = {2020}, date = {2020-01-01}, journal = {Vacuum}, volume = {176}, abstract = {Recently introduced model for quantitative analysis of in-depth non-uniform surfaces is applied to reexamine the X-ray Photoelectron Spectroscopy (XPS) data of Cd0.99Fe0.01Te0.97Se0.03 and Zn0.98Fe0.02Te0.91Se0.09 crystalline samples. Special attention is paid to the precise identification of phases which form the bulk-like near-surface region and the surface overlayers (the oxide layer and the layer of organic impurities), as well as the influence of surface morphology on the measurements. The obtained results fully support earlier qualitative estimations, but also provide new quantitative insight into the composition of the three investigated regions. The near-surface region of Cd0.99Fe0.01Te0.97Se0.03 and Zn0.98Fe0.02Te0.91Se0.09 samples is slightly electropositive, with cation/anion ratio 52:48 and 53:47, respectively. Model surface structures, which are fully compatible with the experimental results, comprise 0.76 nm thick CdTeO3 layer at the surface of Cd0.99Fe0.01Te0.97Se0.03 and 0.33 nm thick mixed ZnO/TeO2 oxide layer on Zn0.98Fe0.02Te0.91Se0.09. In both samples the oxide layer is only a few atomic layers thick, implying that it suppresses further rapid migration of oxygen into the bulk. © 2020 Elsevier Ltd}, keywords = {}, pubstate = {published}, tppubtype = {article} } Recently introduced model for quantitative analysis of in-depth non-uniform surfaces is applied to reexamine the X-ray Photoelectron Spectroscopy (XPS) data of Cd0.99Fe0.01Te0.97Se0.03 and Zn0.98Fe0.02Te0.91Se0.09 crystalline samples. Special attention is paid to the precise identification of phases which form the bulk-like near-surface region and the surface overlayers (the oxide layer and the layer of organic impurities), as well as the influence of surface morphology on the measurements. The obtained results fully support earlier qualitative estimations, but also provide new quantitative insight into the composition of the three investigated regions. The near-surface region of Cd0.99Fe0.01Te0.97Se0.03 and Zn0.98Fe0.02Te0.91Se0.09 samples is slightly electropositive, with cation/anion ratio 52:48 and 53:47, respectively. Model surface structures, which are fully compatible with the experimental results, comprise 0.76 nm thick CdTeO3 layer at the surface of Cd0.99Fe0.01Te0.97Se0.03 and 0.33 nm thick mixed ZnO/TeO2 oxide layer on Zn0.98Fe0.02Te0.91Se0.09. In both samples the oxide layer is only a few atomic layers thick, implying that it suppresses further rapid migration of oxygen into the bulk. © 2020 Elsevier Ltd |
Dobrota, A S; Pašti, I A; Mentus, S V; Johansson, B; Skorodumova, N V Altering the reactivity of pristine, N- and P-doped graphene by strain engineering: A DFT view on energy related aspects Journal Article Applied Surface Science, 514 , 2020. @article{Dobrota2020, title = {Altering the reactivity of pristine, N- and P-doped graphene by strain engineering: A DFT view on energy related aspects}, author = {A S Dobrota and I A Pašti and S V Mentus and B Johansson and N V Skorodumova}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85081026675&doi=10.1016%2fj.apsusc.2020.145937&partnerID=40&md5=144a6d323679a1f70b41dac3fc54ad91}, doi = {10.1016/j.apsusc.2020.145937}, year = {2020}, date = {2020-01-01}, journal = {Applied Surface Science}, volume = {514}, abstract = {For carbon-based materials, in contrast to metal surfaces, a general relationship between strain and reactivity is not yet established, even though there are literature reports on strained graphene. Knowledge of such relationships would be extremely beneficial for understanding the reactivity of graphene-based surfaces and finding optimisation strategies which would make these materials more suitable for targeted applications. Here we investigate the effects of compressive and tensile strain (up to ±5%) on the structure, electronic properties and reactivity of pure, N-doped and P-doped graphene, using DFT calculations. We demonstrate the possibility of tuning the topology of the graphene surface by strain, as well as by the choice of the dopant atom. The reactivity of (doped) strained graphene is probed using H and Na as simple adsorbates of great practical importance. Strain can both enhance and weaken H and Na adsorption on (doped) graphene. In case of Na adsorption, a linear relationship is observed between the Na adsorption energy on P-doped graphene and the phosphorus charge. A linear relationship between the Na adsorption energy on flat graphene surfaces and strain is found. Based on the adsorption energies and electrical conductivity, potentially good candidates for hydrogen storage and sodium-ion battery electrodes are discussed. © 2020}, keywords = {}, pubstate = {published}, tppubtype = {article} } For carbon-based materials, in contrast to metal surfaces, a general relationship between strain and reactivity is not yet established, even though there are literature reports on strained graphene. Knowledge of such relationships would be extremely beneficial for understanding the reactivity of graphene-based surfaces and finding optimisation strategies which would make these materials more suitable for targeted applications. Here we investigate the effects of compressive and tensile strain (up to ±5%) on the structure, electronic properties and reactivity of pure, N-doped and P-doped graphene, using DFT calculations. We demonstrate the possibility of tuning the topology of the graphene surface by strain, as well as by the choice of the dopant atom. The reactivity of (doped) strained graphene is probed using H and Na as simple adsorbates of great practical importance. Strain can both enhance and weaken H and Na adsorption on (doped) graphene. In case of Na adsorption, a linear relationship is observed between the Na adsorption energy on P-doped graphene and the phosphorus charge. A linear relationship between the Na adsorption energy on flat graphene surfaces and strain is found. Based on the adsorption energies and electrical conductivity, potentially good candidates for hydrogen storage and sodium-ion battery electrodes are discussed. © 2020 |
Brkovic, S M; Kaninski, Marceta M P; Lausevic, P Z; Saponjic, A B; Radulovic, A M; Rakic, A A; Pasti, I A; Nikolic, V М International Journal of Hydrogen Energy, 45 (27), pp. 13929-13938, 2020. @article{Brkovic202013929, title = {Non-stoichiometric tungsten-carbide-oxide-supported Pt–Ru anode catalysts for PEM fuel cells – From basic electrochemistry to fuel cell performance}, author = {S M Brkovic and M P Marceta Kaninski and P Z Lausevic and A B Saponjic and A M Radulovic and A A Rakic and I A Pasti and V М Nikolic}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85082747239&doi=10.1016%2fj.ijhydene.2020.03.086&partnerID=40&md5=6f42c2081cf1e926f3d3d807bf9b0fb1}, doi = {10.1016/j.ijhydene.2020.03.086}, year = {2020}, date = {2020-01-01}, journal = {International Journal of Hydrogen Energy}, volume = {45}, number = {27}, pages = {13929-13938}, abstract = {Durability and cost of Proton Exchange Membrane fuel cells (PEMFCs) are two major factors delaying their commercialization. Cost is associated with the price of the catalysts, while durability is associated with degradation and poisoning of the catalysts, primarily by CO. This motivated us to develop tungsten-carbide-oxide (WxCyOz) as a new non-carbon based catalyst support for Pt–Ru–based anode PEMFC catalyst. The aim was to improve performance and obtain higher CO tolerance compared to commercial catalysts. The performance of obtained PtRu/WxCyOz catalysts was investigated using cyclic voltammetry, linear scan voltammetry and rotating disk electrode voltammetry. Particular attention was given to the analysis of CO poisoning, to better understand how WxCyOz species can contribute to the CO tolerance of PtRu/WxCyOz. Improved oxidation of COads at low potentials (E < 0.5 V vs. RHE) was ascribed to OH provided by the oxide phase at the interfacial region between the support and the PtRu particles. On the other hand, at high potentials (E > 0.5 V vs. RHE) CO removal proceeds dominantly via OH provided from the oxidized metal sites. The obtained catalyst with the best performance (30% PtRu/WxCyOz) was tested as an anode catalyst in PEM fuel cell. When using synthetic reformate as a fuel in PEMFC, there is a significant power drop of 35.3 % for the commercial 30% PtRu/C catalyst, while for the PtRu/WxCyOz anode catalyst this drop is around 16 %. © 2020 Hydrogen Energy Publications LLC}, keywords = {}, pubstate = {published}, tppubtype = {article} } Durability and cost of Proton Exchange Membrane fuel cells (PEMFCs) are two major factors delaying their commercialization. Cost is associated with the price of the catalysts, while durability is associated with degradation and poisoning of the catalysts, primarily by CO. This motivated us to develop tungsten-carbide-oxide (WxCyOz) as a new non-carbon based catalyst support for Pt–Ru–based anode PEMFC catalyst. The aim was to improve performance and obtain higher CO tolerance compared to commercial catalysts. The performance of obtained PtRu/WxCyOz catalysts was investigated using cyclic voltammetry, linear scan voltammetry and rotating disk electrode voltammetry. Particular attention was given to the analysis of CO poisoning, to better understand how WxCyOz species can contribute to the CO tolerance of PtRu/WxCyOz. Improved oxidation of COads at low potentials (E < 0.5 V vs. RHE) was ascribed to OH provided by the oxide phase at the interfacial region between the support and the PtRu particles. On the other hand, at high potentials (E > 0.5 V vs. RHE) CO removal proceeds dominantly via OH provided from the oxidized metal sites. The obtained catalyst with the best performance (30% PtRu/WxCyOz) was tested as an anode catalyst in PEM fuel cell. When using synthetic reformate as a fuel in PEMFC, there is a significant power drop of 35.3 % for the commercial 30% PtRu/C catalyst, while for the PtRu/WxCyOz anode catalyst this drop is around 16 %. © 2020 Hydrogen Energy Publications LLC |
Milovanović, B; Stanojević, A; Etinski, M; Petković, M Intriguing Intermolecular Interplay in Guanine Quartet Complexes with Alkali and Alkaline Earth Cations Journal Article The journal of physical chemistry. B, 124 (15), pp. 3002-3014, 2020. @article{Milovanović20203002, title = {Intriguing Intermolecular Interplay in Guanine Quartet Complexes with Alkali and Alkaline Earth Cations}, author = {B Milovanović and A Stanojević and M Etinski and M Petković}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85083545675&doi=10.1021%2facs.jpcb.0c01165&partnerID=40&md5=586aadb3b4c40663d93672180ff09f1b}, doi = {10.1021/acs.jpcb.0c01165}, year = {2020}, date = {2020-01-01}, journal = {The journal of physical chemistry. B}, volume = {124}, number = {15}, pages = {3002-3014}, abstract = {The possibility to target noncanonical guanine structures with specific ligands for therapeutic purposes inspired numerous theoretical and experimental investigations of a guanine quartet and its stacked composites. In this work, we employed the interacting quantum atoms methodology to study interactions among different fragments in complexes composed of a guanine quartet and alkali (Li+, Na+, K+) or alkaline earth (Be2+, Mg2+, Ca2+) cations in vacuo: metal-quartet interaction, influence of the cation on guanine-guanine interaction, as well as hydrogen bond cooperativity in the guanine quartet and its complexes with metal ions. Interestingly, although the presence of a cation intensifies interaction among guanine molecules, it lowers their binding energy because of notable quartet's distortion which is responsible for guanines' substantial deformation energy. This phenomenon is particularly pronounced with Be2+ which, out of the six analyzed cations, enhances hydrogen bond cooperativity to the greatest extent.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The possibility to target noncanonical guanine structures with specific ligands for therapeutic purposes inspired numerous theoretical and experimental investigations of a guanine quartet and its stacked composites. In this work, we employed the interacting quantum atoms methodology to study interactions among different fragments in complexes composed of a guanine quartet and alkali (Li+, Na+, K+) or alkaline earth (Be2+, Mg2+, Ca2+) cations in vacuo: metal-quartet interaction, influence of the cation on guanine-guanine interaction, as well as hydrogen bond cooperativity in the guanine quartet and its complexes with metal ions. Interestingly, although the presence of a cation intensifies interaction among guanine molecules, it lowers their binding energy because of notable quartet's distortion which is responsible for guanines' substantial deformation energy. This phenomenon is particularly pronounced with Be2+ which, out of the six analyzed cations, enhances hydrogen bond cooperativity to the greatest extent. |
Barudžija, T; Perović, M; Bošković, M; Cvjetićanin, N; Gyergyek, S; Mitrić, M Magnetic memory effect in hollandite-type α-KxMnO2 monocrystalline nanorods Journal Article Journal of Alloys and Compounds, 820 , 2020. @article{Barudžija2020, title = {Magnetic memory effect in hollandite-type α-KxMnO2 monocrystalline nanorods}, author = {T Barudžija and M Perović and M Bošković and N Cvjetićanin and S Gyergyek and M Mitrić}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076581587&doi=10.1016%2fj.jallcom.2019.153406&partnerID=40&md5=cd13f34b01eba89fc8dbdc49ee38f795}, doi = {10.1016/j.jallcom.2019.153406}, year = {2020}, date = {2020-01-01}, journal = {Journal of Alloys and Compounds}, volume = {820}, abstract = {Memory effect due to spin-glass state below about 20 K has been illustrated in the hollandite-type α-KxMnO2 monocrystalline nanorods by systematic magnetization measurements including temperature- and time-dependent magnetization curves in low fields. In this work, we succeeded in writing, reading, and deleting 8-bits digital information in the investigated system. These results show that α-KxMnO2 is a good candidate material for a thermal memory cell. The phenomenological droplet model was used in the description of the observed memory effect, whose origin in α-KxMnO2 is associated with bulk properties, doping and frustration. © 2019 Elsevier B.V.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Memory effect due to spin-glass state below about 20 K has been illustrated in the hollandite-type α-KxMnO2 monocrystalline nanorods by systematic magnetization measurements including temperature- and time-dependent magnetization curves in low fields. In this work, we succeeded in writing, reading, and deleting 8-bits digital information in the investigated system. These results show that α-KxMnO2 is a good candidate material for a thermal memory cell. The phenomenological droplet model was used in the description of the observed memory effect, whose origin in α-KxMnO2 is associated with bulk properties, doping and frustration. © 2019 Elsevier B.V. |
Carević, M V; Savić, T D; Abazović, N D; Mojović, M D; Novaković, T B; Čomor, M I Effect of Fe3+ ion doping on photocatalytic ability of nanozirconia ceramic to degrade 2, 4, 6- trichlorophenol Journal Article Ceramics International, 46 (5), pp. 6820-6827, 2020. @article{Carević20206820, title = {Effect of Fe3+ ion doping on photocatalytic ability of nanozirconia ceramic to degrade 2, 4, 6- trichlorophenol}, author = {M V Carević and T D Savić and N D Abazović and M D Mojović and T B Novaković and M I Čomor}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85078751596&doi=10.1016%2fj.ceramint.2019.11.175&partnerID=40&md5=1d7e4c1e95c26cae0304d07dcdf02f98}, doi = {10.1016/j.ceramint.2019.11.175}, year = {2020}, date = {2020-01-01}, journal = {Ceramics International}, volume = {46}, number = {5}, pages = {6820-6827}, abstract = {Pure and a series of Fe3+ doped zirconia nanopowders were synthesized combining colloidal chemistry and solvothermal method from organometallic precursors in order to correlate doping and properties of zirconia matrix. After annealing of washed nanopowders at 600 °C, detailed characterization was performed using X-ray diffraction, UV/Vis absorption and luminescence, infrared and electron paramagnetic spectroscopy, transmission electron microscopy and BET measurements. Zirconia samples had mixed monoclinic and tetragonal crystalline phase; increasing Fe3+ ions concentration was followed by increasing of tetragonal phase share. In the sample with highest Fe3+ concentration, hematite can be detected. Also, UV/Vis spectrophotometry showed that Fe3+ doping lowers effective band gap of zirconia matrix from 4.5 eV (bulk value) to 2.1 eV for doped/nanocomposite samples. EPR measurements proved presence of dopant and showed that isolated Fe3+ ions in zirconia matrix exist in both crystalline phases; monoclinic and tetragonal (g ~ 4.8 and g ~ 4.27–4.2, respectively) surroundings. Zirconia samples were also successfully used as photocatalysts for photocatalytic degradation of 2, 4, 6, trichlorophenol. © 2019 Elsevier Ltd and Techna Group S.r.l.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Pure and a series of Fe3+ doped zirconia nanopowders were synthesized combining colloidal chemistry and solvothermal method from organometallic precursors in order to correlate doping and properties of zirconia matrix. After annealing of washed nanopowders at 600 °C, detailed characterization was performed using X-ray diffraction, UV/Vis absorption and luminescence, infrared and electron paramagnetic spectroscopy, transmission electron microscopy and BET measurements. Zirconia samples had mixed monoclinic and tetragonal crystalline phase; increasing Fe3+ ions concentration was followed by increasing of tetragonal phase share. In the sample with highest Fe3+ concentration, hematite can be detected. Also, UV/Vis spectrophotometry showed that Fe3+ doping lowers effective band gap of zirconia matrix from 4.5 eV (bulk value) to 2.1 eV for doped/nanocomposite samples. EPR measurements proved presence of dopant and showed that isolated Fe3+ ions in zirconia matrix exist in both crystalline phases; monoclinic and tetragonal (g ~ 4.8 and g ~ 4.27–4.2, respectively) surroundings. Zirconia samples were also successfully used as photocatalysts for photocatalytic degradation of 2, 4, 6, trichlorophenol. © 2019 Elsevier Ltd and Techna Group S.r.l. |
Biserčić, M S; Marjanović, B; Zasońska, B A; Stojadinović, S; Ćirić-Marjanović, G Novel microporous composites of MOF-5 and polyaniline with high specific surface area Journal Article Synthetic Metals, 262 , 2020. @article{Biserčić2020, title = {Novel microporous composites of MOF-5 and polyaniline with high specific surface area}, author = {M S Biserčić and B Marjanović and B A Zasońska and S Stojadinović and G Ćirić-Marjanović}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85080987780&doi=10.1016%2fj.synthmet.2020.116348&partnerID=40&md5=ce7041b8dbdf75b1f25a95285285ac5c}, doi = {10.1016/j.synthmet.2020.116348}, year = {2020}, date = {2020-01-01}, journal = {Synthetic Metals}, volume = {262}, abstract = {Composites of metal organic framework MOF-5 and conjugated polymer polyaniline (PANI) were synthesized for the first time. Two procedures, which avoid humidity during the synthesis in order to preserve the structure of MOF-5, were applied. In the first one, dissolved part of nonconducting emeraldine base form of PANI (PANI-EB) in N,N΄-dimethylformamide was mixed with MOF-5 in different mass ratios. In the second one, the composites were prepared mechano-chemically, by using powdered conducting emeraldine salt form of PANI (PANI-ES) and solid MOF-5, mixed in chloroform in different mass ratios. The composites were characterized by various techniques: scanning electron microscopy (SEM), FTIR spectroscopy, nitrogen sorption and electrical conductivity measurements, XRD, and flame atomic absorption spectroscopy (FAAS). The procedure which used PANI-EB led to microporous PANI/MOF-5 composites with very high BET specific surface area, SBET (the highest value SBET of c.a. 2700 m2 g−1, even higher than SBET of starting pure MOF-5, showed the composite which contains 89 wt.% of MOF-5) and low conductivity (∼10-7 S cm−1). The second procedure which used PANI-ES gave microporous PANI/MOF-5 composites which showed moderate conductivities (the highest conductivity of 1.0 ⋅ 10−3 S cm-1 exhibited the composite which contains 25 wt.% of MOF-5) and also high SBET values, but lower than those measured for the composites with PANI-EB (the highest SBET of c.a. 850 m2 g-1 showed the composite of PANI doped with HCl which contains c.a. 77 wt.% of MOF-5). XRD measurements confirmed that predominately cubic crystalline structure of MOF-5 was present in almost all composites. © 2020 Elsevier B.V.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Composites of metal organic framework MOF-5 and conjugated polymer polyaniline (PANI) were synthesized for the first time. Two procedures, which avoid humidity during the synthesis in order to preserve the structure of MOF-5, were applied. In the first one, dissolved part of nonconducting emeraldine base form of PANI (PANI-EB) in N,N΄-dimethylformamide was mixed with MOF-5 in different mass ratios. In the second one, the composites were prepared mechano-chemically, by using powdered conducting emeraldine salt form of PANI (PANI-ES) and solid MOF-5, mixed in chloroform in different mass ratios. The composites were characterized by various techniques: scanning electron microscopy (SEM), FTIR spectroscopy, nitrogen sorption and electrical conductivity measurements, XRD, and flame atomic absorption spectroscopy (FAAS). The procedure which used PANI-EB led to microporous PANI/MOF-5 composites with very high BET specific surface area, SBET (the highest value SBET of c.a. 2700 m2 g−1, even higher than SBET of starting pure MOF-5, showed the composite which contains 89 wt.% of MOF-5) and low conductivity (∼10-7 S cm−1). The second procedure which used PANI-ES gave microporous PANI/MOF-5 composites which showed moderate conductivities (the highest conductivity of 1.0 ⋅ 10−3 S cm-1 exhibited the composite which contains 25 wt.% of MOF-5) and also high SBET values, but lower than those measured for the composites with PANI-EB (the highest SBET of c.a. 850 m2 g-1 showed the composite of PANI doped with HCl which contains c.a. 77 wt.% of MOF-5). XRD measurements confirmed that predominately cubic crystalline structure of MOF-5 was present in almost all composites. © 2020 Elsevier B.V. |
Gledovic, A; Lezaic, A J; Krstonosic, V; Djokovic, J; Nikolic, I; Bajuk-Bogdanovic, D; Stankovic, J A; Randjelovic, D; Savic, S M; Filipovic, M; Tamburic, S; Savic, S D PLoS ONE, 15 (4), 2020. @article{Gledovic2020, title = {Low-energy nanoemulsions as carriers for red raspberry seed oil: Formulation approach based on Raman spectroscopy and textural analysis, physicochemical properties, stability and in vitro antioxidant/ biological activity}, author = {A Gledovic and A J Lezaic and V Krstonosic and J Djokovic and I Nikolic and D Bajuk-Bogdanovic and J A Stankovic and D Randjelovic and S M Savic and M Filipovic and S Tamburic and S D Savic}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85083478878&doi=10.1371%2fjournal.pone.0230993&partnerID=40&md5=682ff0154174587b10f5581eb48a5b15}, doi = {10.1371/journal.pone.0230993}, year = {2020}, date = {2020-01-01}, journal = {PLoS ONE}, volume = {15}, number = {4}, abstract = {Considering a growing demand for medicinal/cosmetic products with natural actives, this study focuses on the low-energy nanoemulsions (LE-NEs) prepared via the Phase inversion composition (PIC) method at room temperature as potential carriers for natural oil. Four different red raspberry seed oils (ROs) were tested, as follows: cold-pressed vs. CO2- extracted, organic vs. non-organic, refined vs. unrefined. The oil phase was optimized with Tocopheryl acetate and Isostearyl isostearate, while water phase was adjusted with either glycerol or an antioxidant hydro-glycolic extract. This study has used a combined approach to formulation development, employing both conventional methods (pseudo-ternary phase diagram - PTPD, electrical conductivity, particle size measurements, microscopical analysis, and rheological measurements) and the methods novel to this area, such as textural analysis and Raman spectroscopy. Raman spectroscopy has detected fine differences in chemical composition among ROs, and it detected the interactions within nanoemulsions. It was shown that the cold-pressed, unrefined, organic grade oil (RO2) with 6.62% saturated fatty acids and 92.25% unsaturated fatty acids, was optimal for the LE-NEs. Textural analysis confirmed the existence of cubic gel-like phase as a crucial step in the formation of stable RO2-loaded LE-NEs, with droplets in the narrow nano-range (125 to 135 nm; PDI ≤ 0.1). The DPPH test in methanol and ABTS in aqueous medium have revealed a synergistic free radical scavenging effect between lipophilic and hydrophilic antioxidants in LE-NEs. The nanoemulsion carrier has improved the biological effect of raw materials on HeLa cervical adenocarcinoma cells, while exhibiting good safety profile, as confirmed on MRC-5 normal human lung fibroblasts. Overall, this study has shown that low-energy nanoemulsions present very promising carriers for topical delivery of natural bioactives. Raman spectroscopy and textural analysis have proven to be a useful addition to the arsenal of methods used in the formulation and characterization of nanoemulsion systems. © 2020 Gledovic et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Considering a growing demand for medicinal/cosmetic products with natural actives, this study focuses on the low-energy nanoemulsions (LE-NEs) prepared via the Phase inversion composition (PIC) method at room temperature as potential carriers for natural oil. Four different red raspberry seed oils (ROs) were tested, as follows: cold-pressed vs. CO2- extracted, organic vs. non-organic, refined vs. unrefined. The oil phase was optimized with Tocopheryl acetate and Isostearyl isostearate, while water phase was adjusted with either glycerol or an antioxidant hydro-glycolic extract. This study has used a combined approach to formulation development, employing both conventional methods (pseudo-ternary phase diagram - PTPD, electrical conductivity, particle size measurements, microscopical analysis, and rheological measurements) and the methods novel to this area, such as textural analysis and Raman spectroscopy. Raman spectroscopy has detected fine differences in chemical composition among ROs, and it detected the interactions within nanoemulsions. It was shown that the cold-pressed, unrefined, organic grade oil (RO2) with 6.62% saturated fatty acids and 92.25% unsaturated fatty acids, was optimal for the LE-NEs. Textural analysis confirmed the existence of cubic gel-like phase as a crucial step in the formation of stable RO2-loaded LE-NEs, with droplets in the narrow nano-range (125 to 135 nm; PDI ≤ 0.1). The DPPH test in methanol and ABTS in aqueous medium have revealed a synergistic free radical scavenging effect between lipophilic and hydrophilic antioxidants in LE-NEs. The nanoemulsion carrier has improved the biological effect of raw materials on HeLa cervical adenocarcinoma cells, while exhibiting good safety profile, as confirmed on MRC-5 normal human lung fibroblasts. Overall, this study has shown that low-energy nanoemulsions present very promising carriers for topical delivery of natural bioactives. Raman spectroscopy and textural analysis have proven to be a useful addition to the arsenal of methods used in the formulation and characterization of nanoemulsion systems. © 2020 Gledovic et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. |
Gutić, S J; Dobrota, A S; Fako, E; Skorodumova, N V; López, N; Pašti, I A Hydrogen evolution reaction-from single crystal to single atom catalysts Journal Article Catalysts, 10 (3), 2020. @article{Gutić2020, title = {Hydrogen evolution reaction-from single crystal to single atom catalysts}, author = {S J Gutić and A S Dobrota and E Fako and N V Skorodumova and N López and I A Pašti}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85080984156&doi=10.3390%2fcatal10030290&partnerID=40&md5=815f920476b20c05559a8508d08f0ecb}, doi = {10.3390/catal10030290}, year = {2020}, date = {2020-01-01}, journal = {Catalysts}, volume = {10}, number = {3}, abstract = {Hydrogen evolution reaction (HER) is one of the most important reactions in electrochemistry. This is not only because it is the simplest way to produce high purity hydrogen and the fact that it is the side reaction in many other technologies. HER actually shaped current electrochemistry because it was in focus of active research for so many years (and it still is). The number of catalysts investigated for HER is immense, and it is not possible to overview them all. In fact, it seems that the complexity of the field overcomes the complexity of HER. The aim of this review is to point out some of the latest developments in HER catalysis, current directions and some of the missing links between a single crystal, nanosized supported catalysts and recently emerging, single-atom catalysts for HER. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Hydrogen evolution reaction (HER) is one of the most important reactions in electrochemistry. This is not only because it is the simplest way to produce high purity hydrogen and the fact that it is the side reaction in many other technologies. HER actually shaped current electrochemistry because it was in focus of active research for so many years (and it still is). The number of catalysts investigated for HER is immense, and it is not possible to overview them all. In fact, it seems that the complexity of the field overcomes the complexity of HER. The aim of this review is to point out some of the latest developments in HER catalysis, current directions and some of the missing links between a single crystal, nanosized supported catalysts and recently emerging, single-atom catalysts for HER. © 2020 by the authors. Licensee MDPI, Basel, Switzerland. |
Jakovljević, K; Mišljenović, T; Savović, J; Ranković, D; Ranđelović, D; Mihailović, N; Jovanović, S Accumulation of trace elements in Tussilago farfara colonizing post-flotation tailing sites in Serbia Journal Article Environmental Science and Pollution Research, 27 (4), pp. 4089-4103, 2020. @article{Jakovljević20204089, title = {Accumulation of trace elements in Tussilago farfara colonizing post-flotation tailing sites in Serbia}, author = {K Jakovljević and T Mišljenović and J Savović and D Ranković and D Ranđelović and N Mihailović and S Jovanović}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076593326&doi=10.1007%2fs11356-019-07010-z&partnerID=40&md5=3414f7254cbfcb0735e6ba2c973d88c8}, doi = {10.1007/s11356-019-07010-z}, year = {2020}, date = {2020-01-01}, journal = {Environmental Science and Pollution Research}, volume = {27}, number = {4}, pages = {4089-4103}, abstract = {The purpose of this study was to examine the accumulation potential of spontaneously developed Tussilago farfara populations colonizing sites with different levels of anthropogenic pollution. Physical characteristics of the soil are presented, together with the concentrations of macroelements and microelements (Ca, Mg, Fe, S, Al, Pb, Zn, Cu, Cd, Mn, As, Sb, Ag, Ti, and Sr) in both soil and plants. The biological concentration, accumulation, and translocation factors were used to assess the potential for heavy metal accumulation. Considerable differences were found among assessions from unevenly contaminated habitats, particularly in comparison with an unpolluted site. In line with the ore’s characteristics, substrate samples from polluted sites were heavily contaminated with Pb, Zn, As, and Sb. Increased levels of microelements were also detected in plant samples from flotation tailings. Despite active absorption of Zn, Cu, Cd, Mn, and Sr by the plants from mining sites, the detected quantities of these elements in all samples were below the hyperaccumulation threshold. However, the obtained results indicate that the use of T. farfara from such sites in traditional medicine could pose a risk to human health due to accumulation of several toxic elements in the plant’s aboveground tissues. Additionally, as a successful primary colonizer and stabilizer of technogenic substrates, T. farfara has an important role in the initial phases of revegetation of highly contaminated sites. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The purpose of this study was to examine the accumulation potential of spontaneously developed Tussilago farfara populations colonizing sites with different levels of anthropogenic pollution. Physical characteristics of the soil are presented, together with the concentrations of macroelements and microelements (Ca, Mg, Fe, S, Al, Pb, Zn, Cu, Cd, Mn, As, Sb, Ag, Ti, and Sr) in both soil and plants. The biological concentration, accumulation, and translocation factors were used to assess the potential for heavy metal accumulation. Considerable differences were found among assessions from unevenly contaminated habitats, particularly in comparison with an unpolluted site. In line with the ore’s characteristics, substrate samples from polluted sites were heavily contaminated with Pb, Zn, As, and Sb. Increased levels of microelements were also detected in plant samples from flotation tailings. Despite active absorption of Zn, Cu, Cd, Mn, and Sr by the plants from mining sites, the detected quantities of these elements in all samples were below the hyperaccumulation threshold. However, the obtained results indicate that the use of T. farfara from such sites in traditional medicine could pose a risk to human health due to accumulation of several toxic elements in the plant’s aboveground tissues. Additionally, as a successful primary colonizer and stabilizer of technogenic substrates, T. farfara has an important role in the initial phases of revegetation of highly contaminated sites. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature. |
Dimić, D; Milanović, Ž; Jovanović, G; Sretenović, D; Milenković, D; Marković, Z; Marković, Dimitrić J Comparative antiradical activity and molecular Docking/Dynamics analysis of octopamine and norepinephrine: the role of OH groups Journal Article Computational Biology and Chemistry, 84 , 2020. @article{Dimić2020, title = {Comparative antiradical activity and molecular Docking/Dynamics analysis of octopamine and norepinephrine: the role of OH groups}, author = {D Dimić and Ž Milanović and G Jovanović and D Sretenović and D Milenković and Z Marković and J Dimitrić Marković}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076515589&doi=10.1016%2fj.compbiolchem.2019.107170&partnerID=40&md5=f368da14eb6e0a988625777d7f81651a}, doi = {10.1016/j.compbiolchem.2019.107170}, year = {2020}, date = {2020-01-01}, journal = {Computational Biology and Chemistry}, volume = {84}, abstract = {Octopamine is a neurotransmitter in invertebrates and a phenol analog of norepinephrine. The crystallographic and spectral (UV–visUV, and NMR) characteristics of octopamine were investigated experimentally and theoretically by applying appropriate level of theory, B3LYP-D3BJ/6-311++G(d,p), which reproduced well the experimental bond lengths and angles. The intramolecular interactions governing the stability of conformers were described by NBO and QTAIM analyses. The antiradical potencies of octopamine and norepinephrine towards DPPH[rad] and ABTS[rad] + were examined with special emphasis on the preferred mechanism and effect of catechol moiety. Several techniques were used to distinguish Hydrogen Atom Transfer (HAT) and Proton Coupled Electron Transfer (PCET) mechanisms for reaction with DPPH[rad]. The calculated rate constants of the reactions with both radicals showed that Sequential Proton Loss Electron Transfer (SPLET) mechanism was dominant both thermodynamically and kinetically, with values of thermodynamic functions and rate constants clearly proving the importance of the second hydroxyl group in structure. The Molecular Docking and afterward Molecular Dynamics calculations of formed complexes between octopamine/norepinephrine with β1- and β2- adrenergic receptors examined in details the interactions that lead to the formation of stable complexes. The number of strong interactions of amino acids with norepinephrine was higher, but the absence of hydroxyl group in octopamine did not lead to a significant change in the type of interactions and stability. The formed complexes showed higher flexibility of amino acids, similar compactness of structure as proteins and increased interatomic distances of the backbone when compared to pure proteins. © 2019 Elsevier Ltd}, keywords = {}, pubstate = {published}, tppubtype = {article} } Octopamine is a neurotransmitter in invertebrates and a phenol analog of norepinephrine. The crystallographic and spectral (UV–visUV, and NMR) characteristics of octopamine were investigated experimentally and theoretically by applying appropriate level of theory, B3LYP-D3BJ/6-311++G(d,p), which reproduced well the experimental bond lengths and angles. The intramolecular interactions governing the stability of conformers were described by NBO and QTAIM analyses. The antiradical potencies of octopamine and norepinephrine towards DPPH[rad] and ABTS[rad] + were examined with special emphasis on the preferred mechanism and effect of catechol moiety. Several techniques were used to distinguish Hydrogen Atom Transfer (HAT) and Proton Coupled Electron Transfer (PCET) mechanisms for reaction with DPPH[rad]. The calculated rate constants of the reactions with both radicals showed that Sequential Proton Loss Electron Transfer (SPLET) mechanism was dominant both thermodynamically and kinetically, with values of thermodynamic functions and rate constants clearly proving the importance of the second hydroxyl group in structure. The Molecular Docking and afterward Molecular Dynamics calculations of formed complexes between octopamine/norepinephrine with β1- and β2- adrenergic receptors examined in details the interactions that lead to the formation of stable complexes. The number of strong interactions of amino acids with norepinephrine was higher, but the absence of hydroxyl group in octopamine did not lead to a significant change in the type of interactions and stability. The formed complexes showed higher flexibility of amino acids, similar compactness of structure as proteins and increased interatomic distances of the backbone when compared to pure proteins. © 2019 Elsevier Ltd |
Amić, A; Marković, Z; Marković, Dimitrić J M; Milenković, D; Stepanić, V Antioxidative potential of ferulic acid phenoxyl radical Journal Article Phytochemistry, 170 , 2020. @article{Amić2020, title = {Antioxidative potential of ferulic acid phenoxyl radical}, author = {A Amić and Z Marković and J M Dimitrić Marković and D Milenković and V Stepanić}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075868348&doi=10.1016%2fj.phytochem.2019.112218&partnerID=40&md5=6076887d9f28971d3996f4d34577aa26}, doi = {10.1016/j.phytochem.2019.112218}, year = {2020}, date = {2020-01-01}, journal = {Phytochemistry}, volume = {170}, abstract = {The vast majority of previous studies dealing with antioxidant potency of (poly)phenols does not investigate the fate of phenoxyl radical obtained after single free radical scavenging. We investigated possible pathways of inactivation of ferulic acid phenoxyl radical (FAPR) using DFT method. Direct coupling with a set of 10 physiologically important free radicals, H-atom donation and dimerization were analysed by estimation of Gibbs free energy changes related to these processes. The former two processes are thermodynamically feasible to inactivate more dangerous free radicals such as hydroxyl, alkoxyl and carbon-centered radicals. Among dimerization reactions, the least energy demanding is formation of C-5−C-5 dimer of ferulic acid (FA), which has higher antiradical potency than FA itself. Obtained results reveal that FAPR, a priori considered as stable and unreactive, may contribute to the overall antioxidant activity of FA. This is a beneficial behavior, which makes FA a particularly valuable protector against oxidative stress. Hence, the contribution of phenoxyl radicals to the antioxidant activity of (poly)phenolic compounds should be taken into account, what has been scarcely considered until now. © 2019 Elsevier Ltd}, keywords = {}, pubstate = {published}, tppubtype = {article} } The vast majority of previous studies dealing with antioxidant potency of (poly)phenols does not investigate the fate of phenoxyl radical obtained after single free radical scavenging. We investigated possible pathways of inactivation of ferulic acid phenoxyl radical (FAPR) using DFT method. Direct coupling with a set of 10 physiologically important free radicals, H-atom donation and dimerization were analysed by estimation of Gibbs free energy changes related to these processes. The former two processes are thermodynamically feasible to inactivate more dangerous free radicals such as hydroxyl, alkoxyl and carbon-centered radicals. Among dimerization reactions, the least energy demanding is formation of C-5−C-5 dimer of ferulic acid (FA), which has higher antiradical potency than FA itself. Obtained results reveal that FAPR, a priori considered as stable and unreactive, may contribute to the overall antioxidant activity of FA. This is a beneficial behavior, which makes FA a particularly valuable protector against oxidative stress. Hence, the contribution of phenoxyl radicals to the antioxidant activity of (poly)phenolic compounds should be taken into account, what has been scarcely considered until now. © 2019 Elsevier Ltd |
Petrusic, I; Viana, M; Zecca, C; Zidverc-Trajkovic, J Dysphasia and Other Higher Cortical Dysfunctions During the Migraine Aura—a Systematic Review of Literature Journal Article Current Pain and Headache Reports, 24 (2), 2020. @article{Petrusic2020, title = {Dysphasia and Other Higher Cortical Dysfunctions During the Migraine Aura—a Systematic Review of Literature}, author = {I Petrusic and M Viana and C Zecca and J Zidverc-Trajkovic}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85078214474&doi=10.1007%2fs11916-020-0836-3&partnerID=40&md5=a59ae94050746ce59ab54b5cfee7542b}, doi = {10.1007/s11916-020-0836-3}, year = {2020}, date = {2020-01-01}, journal = {Current Pain and Headache Reports}, volume = {24}, number = {2}, abstract = {Purpose of the Review: Although visual and somatosensory disturbances are the most common migraine aura (MA) symptoms, patients can also experience other symptoms during their MA. The aim of this review is to provide an overview of studies that report symptoms of dysphasia and other higher cortical dysfunctions (HCDs) during MA, as well as to determine the frequency of HCDs. Recent Findings: Five studies met the inclusion criteria, corresponding to 697 patients overall. The most frequently reported HCDs were those of the language group (range 10–53%). The occurrence of visual HCDs was noted in 12–40 patients, somatosensory HCDs in 12–20%, and memory disturbances in 10–22% of the patients during MAs. Summary: MA is associated with a wide range of neurological symptoms, including symptoms of HCD. A better strategy for investigation of the HCD symptoms is needed to correctly stratify patients thus allowing meaningful studies of aura pathophysiology. © 2020, Springer Science+Business Media, LLC, part of Springer Nature.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Purpose of the Review: Although visual and somatosensory disturbances are the most common migraine aura (MA) symptoms, patients can also experience other symptoms during their MA. The aim of this review is to provide an overview of studies that report symptoms of dysphasia and other higher cortical dysfunctions (HCDs) during MA, as well as to determine the frequency of HCDs. Recent Findings: Five studies met the inclusion criteria, corresponding to 697 patients overall. The most frequently reported HCDs were those of the language group (range 10–53%). The occurrence of visual HCDs was noted in 12–40 patients, somatosensory HCDs in 12–20%, and memory disturbances in 10–22% of the patients during MAs. Summary: MA is associated with a wide range of neurological symptoms, including symptoms of HCD. A better strategy for investigation of the HCD symptoms is needed to correctly stratify patients thus allowing meaningful studies of aura pathophysiology. © 2020, Springer Science+Business Media, LLC, part of Springer Nature. |
Petković, M; Leopold, J; Popović, I; Dimić, D; Ilić, J; Nenadović, M; Rakočević, Z; Schiller, J Journal of Carbohydrate Chemistry, 39 (1), pp. 1-23, 2020. @article{Petković20201, title = {Performances of ionic liquid matrices with butyl ammonium counterion for matrix-assisted laser desorption/ionization mass spectrometric detection and analysis of sucralfate}, author = {M Petković and J Leopold and I Popović and D Dimić and J Ilić and M Nenadović and Z Rakočević and J Schiller}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074481788&doi=10.1080%2f07328303.2019.1669633&partnerID=40&md5=1252a26a34997acf6eb6088c4a2a2bd6}, doi = {10.1080/07328303.2019.1669633}, year = {2020}, date = {2020-01-01}, journal = {Journal of Carbohydrate Chemistry}, volume = {39}, number = {1}, pages = {1-23}, abstract = {In this work, the performances of two ionic liquid matrices (ILMs) with the same ammonium counterpart for mass spectrometric analysis of the insoluble and soluble sucralfate were compared. Matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) was performed assisted by the butylammonium salts of α-cyano-hydroxycinnamic acid (CHCAB) and 2,5-dihydroxybenzoic acid (DHBB). CHCAB has a higher IE than DHBB, but better optical properties. CHCAB is more suitable for the analysis of sucralfate, although molecular ions of both compounds were detectable only with low intensities. Thus, optical properties of ILMs are crucial to enhance the sensitivity of MALDI MS detection of polysulfated oligosaccharides. © 2019, © 2019 Taylor & Francis Group, LLC.}, keywords = {}, pubstate = {published}, tppubtype = {article} } In this work, the performances of two ionic liquid matrices (ILMs) with the same ammonium counterpart for mass spectrometric analysis of the insoluble and soluble sucralfate were compared. Matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) was performed assisted by the butylammonium salts of α-cyano-hydroxycinnamic acid (CHCAB) and 2,5-dihydroxybenzoic acid (DHBB). CHCAB has a higher IE than DHBB, but better optical properties. CHCAB is more suitable for the analysis of sucralfate, although molecular ions of both compounds were detectable only with low intensities. Thus, optical properties of ILMs are crucial to enhance the sensitivity of MALDI MS detection of polysulfated oligosaccharides. © 2019, © 2019 Taylor & Francis Group, LLC. |
Kalijadis, A; Gavrilov, N; Jokić, B; Gilić, M; Krstić, A; Pašti, I; Babić, B Composition, structure and potential energy application of nitrogen doped carbon cryogels Journal Article Materials Chemistry and Physics, 239 , 2020. @article{Kalijadis2020, title = {Composition, structure and potential energy application of nitrogen doped carbon cryogels}, author = {A Kalijadis and N Gavrilov and B Jokić and M Gilić and A Krstić and I Pašti and B Babić}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072025175&doi=10.1016%2fj.matchemphys.2019.122120&partnerID=40&md5=596fb20373556913e06eff7d52dffe6c}, doi = {10.1016/j.matchemphys.2019.122120}, year = {2020}, date = {2020-01-01}, journal = {Materials Chemistry and Physics}, volume = {239}, abstract = {Resorcinol–formaldehyde (RF) cryogels were synthesized by sol–gel polycondensation of resorcinol with formaldehyde and freeze-drying was carried out with t-butanol. Carbon cryogel (CC) was obtained by pyrolyzing RF cryogels in an inert atmosphere to 950 °C. Nitrogen doped CCs (CCN) were synthesized by introducing melamine into RF precursor mixture solution to obtain nitrogen concentration 2, 6 and 10 wt.%. Material was characterized by elemental analysis, nitrogen adsorption– desorption measurements, scanning electron microscopy (SEM), Raman spectroscopy, FT-IR Spectroscopy. Cyclic voltammetry (CV) was used to investigate capacitive and electrocatalytic properties. Conductivity measurement was also performed. Elemental analysis results confirmed presence of nitrogen in CCN samples in the range from 0.45 to 1.15 wt.%. Raman spectroscopy of the samples showed increase of D and G peak integrated intensity ratio (ID/IG) with nitrogen doping suggesting that the structural disorder as well as edge plane density increase, but according to similar ID/IG values for CCN samples, their share is not directly related to the amount of incorporated N. Characterization by nitrogen adsorption showed that overall specific surface and maximum mesopores are achieved in CCN sample with medium nitrogen concentration. Results of cyclic voltammetry experiments demonstrated maximum capacitance for CCN sample with smallest N wt.% indicating that narrow pore size distribution and high specific surface area are dominant factors to achieve good capacitive behavior. The relatively low doping level of nitrogen reached in CCN samples may be the reason for the incomplete reduction of oxygen to hydroxide and furthermore it turned out that presence of N in the structure of CC had a negligible effect on the otherwise relatively high conductivity of CC. © 2019 Elsevier B.V.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Resorcinol–formaldehyde (RF) cryogels were synthesized by sol–gel polycondensation of resorcinol with formaldehyde and freeze-drying was carried out with t-butanol. Carbon cryogel (CC) was obtained by pyrolyzing RF cryogels in an inert atmosphere to 950 °C. Nitrogen doped CCs (CCN) were synthesized by introducing melamine into RF precursor mixture solution to obtain nitrogen concentration 2, 6 and 10 wt.%. Material was characterized by elemental analysis, nitrogen adsorption– desorption measurements, scanning electron microscopy (SEM), Raman spectroscopy, FT-IR Spectroscopy. Cyclic voltammetry (CV) was used to investigate capacitive and electrocatalytic properties. Conductivity measurement was also performed. Elemental analysis results confirmed presence of nitrogen in CCN samples in the range from 0.45 to 1.15 wt.%. Raman spectroscopy of the samples showed increase of D and G peak integrated intensity ratio (ID/IG) with nitrogen doping suggesting that the structural disorder as well as edge plane density increase, but according to similar ID/IG values for CCN samples, their share is not directly related to the amount of incorporated N. Characterization by nitrogen adsorption showed that overall specific surface and maximum mesopores are achieved in CCN sample with medium nitrogen concentration. Results of cyclic voltammetry experiments demonstrated maximum capacitance for CCN sample with smallest N wt.% indicating that narrow pore size distribution and high specific surface area are dominant factors to achieve good capacitive behavior. The relatively low doping level of nitrogen reached in CCN samples may be the reason for the incomplete reduction of oxygen to hydroxide and furthermore it turned out that presence of N in the structure of CC had a negligible effect on the otherwise relatively high conductivity of CC. © 2019 Elsevier B.V. |
Etinski, M; Stanković, I M; Puthenkalathil, R C; Ensing, B A DFT study of structure and electrochemical properties of diiron-hydrogenase models with benzenedithiolato and benzenediselenato ligands Journal Article New Journal of Chemistry, 44 (3), pp. 932-941, 2020. @article{Etinski2020932, title = {A DFT study of structure and electrochemical properties of diiron-hydrogenase models with benzenedithiolato and benzenediselenato ligands}, author = {M Etinski and I M Stanković and R C Puthenkalathil and B Ensing}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85078439931&doi=10.1039%2fc9nj04887a&partnerID=40&md5=8c473dac752adddfa88fce96aaad8ec5}, doi = {10.1039/c9nj04887a}, year = {2020}, date = {2020-01-01}, journal = {New Journal of Chemistry}, volume = {44}, number = {3}, pages = {932-941}, abstract = {The diiron benzenedithiolato carbonyl complex is a biomimetic catalyst for proton reduction whose catalytic pathways depend on the solvent properties and the proton donor acidity. Previous studies showed that the initial steps in electrocatalytic generation of dihydrogen in acetonitrile involve a two-electron reduction followed by protonation, but the structures and physical properties of other intermediates are not known. We have performed a systematic quantum chemical analysis of the reduced and protonated complexes with benzenedithiolato and benzenediselenato ligands that can be formed by addition of up to three electrons and/or protons. The exchange of the sulfur atoms by selenium increases the basicity of the iron atoms but is not favorable for the protonation of the chalcogen atoms. Our results show that the most stable singly protonated complexes possess the proton in a bridging position between both irons, irrespective of the total complex charge. The second proton can be attached to a chalcogen atom or to an iron atom in a terminal position, depending on the complex charge. The most stable isomers of the triply protonated complexes have protons in the bridging and terminal positions as well as one proton bound to a chalcogen atom. Standard reduction potentials and acidities of all examined complexes were computed. We also discussed possible intermediates and reaction pathways in the electrocatalytic proton reduction to molecular hydrogen formation. © 2020 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The diiron benzenedithiolato carbonyl complex is a biomimetic catalyst for proton reduction whose catalytic pathways depend on the solvent properties and the proton donor acidity. Previous studies showed that the initial steps in electrocatalytic generation of dihydrogen in acetonitrile involve a two-electron reduction followed by protonation, but the structures and physical properties of other intermediates are not known. We have performed a systematic quantum chemical analysis of the reduced and protonated complexes with benzenedithiolato and benzenediselenato ligands that can be formed by addition of up to three electrons and/or protons. The exchange of the sulfur atoms by selenium increases the basicity of the iron atoms but is not favorable for the protonation of the chalcogen atoms. Our results show that the most stable singly protonated complexes possess the proton in a bridging position between both irons, irrespective of the total complex charge. The second proton can be attached to a chalcogen atom or to an iron atom in a terminal position, depending on the complex charge. The most stable isomers of the triply protonated complexes have protons in the bridging and terminal positions as well as one proton bound to a chalcogen atom. Standard reduction potentials and acidities of all examined complexes were computed. We also discussed possible intermediates and reaction pathways in the electrocatalytic proton reduction to molecular hydrogen formation. © 2020 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique. |
Milakin, K A; Gavrilov, N; Pašti, I A; Trchová, M; Zasońska, B A; Stejskal, J; Bober, P Carbon materials derived from poly(aniline-co-p-phenylenediamine) cryogels Journal Article Polymers, 12 (1), 2020. @article{Milakin2020, title = {Carbon materials derived from poly(aniline-co-p-phenylenediamine) cryogels}, author = {K A Milakin and N Gavrilov and I A Pašti and M Trchová and B A Zasońska and J Stejskal and P Bober}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85078455370&doi=10.3390%2fpolym12010011&partnerID=40&md5=8fa429131a2ae440a59356f080bda1e6}, doi = {10.3390/polym12010011}, year = {2020}, date = {2020-01-01}, journal = {Polymers}, volume = {12}, number = {1}, abstract = {Nitrogen-containing carbon derivatives were prepared by the carbonization of poly(aniline-co-p-phenylenediamine) cryogels in inert atmosphere. Lower aniline fraction in the comonomer mixture used for preparation of the cryogels led to the decrease of their thermal stability, a consequent increase of carbonization degree, and less defective structure of carbonized materials. The resulting carbonaceous products had up to 4 orders of magnitude higher specific surface area than their respective cryogel precursors, the highest value 931 m2 g-1 being achieved for carbonized poly(p-phenylenediamine) cryogel. Electrochemical characterization of the carbon derivatives demonstrated that the decrease in aniline concentration during the synthesis of the precursor cryogels led to higher gravimetric capacitance for corresponding carbonized materials. These materials can potentially be used for energy storage applications. © 2019 by the authors.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Nitrogen-containing carbon derivatives were prepared by the carbonization of poly(aniline-co-p-phenylenediamine) cryogels in inert atmosphere. Lower aniline fraction in the comonomer mixture used for preparation of the cryogels led to the decrease of their thermal stability, a consequent increase of carbonization degree, and less defective structure of carbonized materials. The resulting carbonaceous products had up to 4 orders of magnitude higher specific surface area than their respective cryogel precursors, the highest value 931 m2 g-1 being achieved for carbonized poly(p-phenylenediamine) cryogel. Electrochemical characterization of the carbon derivatives demonstrated that the decrease in aniline concentration during the synthesis of the precursor cryogels led to higher gravimetric capacitance for corresponding carbonized materials. These materials can potentially be used for energy storage applications. © 2019 by the authors. |
Nešović, M; Gašić, U; Tosti, T; Trifković, J; Baošić, R; Blagojević, S; Ignjatović, L; Tešić, Ž Physicochemical analysis and phenolic profile of polyfloral and honeydew honey from Montenegro Journal Article RSC Advances, 10 (5), pp. 2462-2471, 2020. @article{Nešović20202462, title = {Physicochemical analysis and phenolic profile of polyfloral and honeydew honey from Montenegro}, author = {M Nešović and U Gašić and T Tosti and J Trifković and R Baošić and S Blagojević and L Ignjatović and Ž Tešić}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85078301815&doi=10.1039%2fc9ra08783d&partnerID=40&md5=062c3793431500531ed017d9d351ac6f}, doi = {10.1039/c9ra08783d}, year = {2020}, date = {2020-01-01}, journal = {RSC Advances}, volume = {10}, number = {5}, pages = {2462-2471}, abstract = {The research subject of this paper was a detail physicochemical analysis of 28 honey samples from the northern part of Montenegro. The honey from Montenegro has not been previously studied in such detail. Differentiation between samples, such as honeydew honey and polyfloral honey, was based on electrical conductivity, which was higher than 0.8 mS cm-1 for honeydew honey, as was expected. Other investigated physicochemical parameters (water content, free acids, diastase activity, hydroxymethylfurfural (HMF) content and sugar content) have shown great similarity for all honey samples. The main interest of this study was the identification and quantification of phenolic compounds using ultra-high performance liquid chromatography (UHPLC) with mass spectrometry detection. The results show that honey samples are very rich in phenolic compounds, especially quercetin. Among the 31 quantified phenolic compounds, the most dominant were phenolic acids. The highlight was based on p-hydroxybenzoic acid, p-coumaric acid, caffeic acid and ferulic acid. Considering polyphenolic compounds and sugar content, a high nutritional value can be observed in all samples, with an emphasis on polyfloral honeys, as was confirmed with principal component analysis (PCA). In addition, all honey samples were tested for total phenolic content (TPC) and radical scavenging activity (RSA). The results indicate the higher antioxidant ability of honeys from Montenegro in comparison to some honey samples from other countries in the region. This journal is © The Royal Society of Chemistry.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The research subject of this paper was a detail physicochemical analysis of 28 honey samples from the northern part of Montenegro. The honey from Montenegro has not been previously studied in such detail. Differentiation between samples, such as honeydew honey and polyfloral honey, was based on electrical conductivity, which was higher than 0.8 mS cm-1 for honeydew honey, as was expected. Other investigated physicochemical parameters (water content, free acids, diastase activity, hydroxymethylfurfural (HMF) content and sugar content) have shown great similarity for all honey samples. The main interest of this study was the identification and quantification of phenolic compounds using ultra-high performance liquid chromatography (UHPLC) with mass spectrometry detection. The results show that honey samples are very rich in phenolic compounds, especially quercetin. Among the 31 quantified phenolic compounds, the most dominant were phenolic acids. The highlight was based on p-hydroxybenzoic acid, p-coumaric acid, caffeic acid and ferulic acid. Considering polyphenolic compounds and sugar content, a high nutritional value can be observed in all samples, with an emphasis on polyfloral honeys, as was confirmed with principal component analysis (PCA). In addition, all honey samples were tested for total phenolic content (TPC) and radical scavenging activity (RSA). The results indicate the higher antioxidant ability of honeys from Montenegro in comparison to some honey samples from other countries in the region. This journal is © The Royal Society of Chemistry. |