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Nasl. z nasl. zaslona. Opis vira z dne 21. 6. 2023. Bibliografija: str. 11-12. Abstract.

Nasl. z nasl. zaslona. Opis vira z dne 16. 5. 2023. Bibliografija: str. 16-18. Abstract.

Nasl. z nasl. zaslona. Objavljeno na spletu: 20. 3. 2023. Opis vira z dne 17. 4. 2023. Bibliografija: str. 1236–1237.

Nasl. z nasl. zaslona. Opis vira z dne 9. 1. 2023. Št. članka: 120916. Bibliografija: str. 7. Abstract.

Finding a maximum clique is important in research areas such as computational chemistry, social network analysis, and bioinformatics. It is possible to compare the maximum clique size between protein graphs to determine their similarity and function. In this paper, improvements based on machine learning (ML) are added to a dynamic algorithm for finding the maximum clique in a protein graph, Maximum Clique Dynamic (MaxCliqueDyn; short: MCQD). This algorithm was published in 2007 and has been widely used in bioinformatics since then. It uses an empirically determined parameter, Tlimit, that determines the algorithm’s flow. We have extended the MCQD algorithm with an initial phase of a machine learning-based prediction of the Tlimit parameter that is best suited for each input graph. Such adaptability to graph types based on state-of-the-art machine learning is a novel approach that has not been used in most graph-theoretic algorithms. We show empirically that the resulting new algorithm MCQD-ML improves search speed on certain types of graphs, in particular molecular docking graphs used in drug design where they determine energetically favorable conformations of small molecules in a protein binding site. In such cases, the speed-up is twofold.

In this work, we developed and optimized a method for the analysis of PAHs and nitro-PAHs in atmospheric particulate matter (PM) samples by using thermal desorption gas chromatography coupled with electron ionization single quadrupole mass spectrometry (TD-GC-(EI)-MS). The method uses thermal desorption from a PM on a filter sample as means of sample introduction to a column and obviates the need for complex extraction procedures, which are time-consuming and require environmentally unfriendly solvents. Moreover, the possibility of systematic errors is minimized and a significantly smaller amount of sample is required compared to traditional techniques requiring a pre-extraction step (approx. 10-times). Thirteen PAHs and three nitro-PAHs were used during method development. Although Tenax cartridges are typically used to capture volatile pollutants from the air, we found that glass-wool liner is the most suitable trap for the examined analytes after desorption from a quartz filter. Among the various instrument parameters which were tested and optimized, TD desorption flow and hold time, and temperature of the cooled injection system (CIS) proved to be most critical. We also found out that the matrix effect is especially pronounced in the case of high PM loadings, which should be kept in mind when planning the analysis. After the optimization, standard reference materials (ERM-CZ100 and NIST 1648a) were used for partial method validation and finally, real PM10 and PM2.5 samples from two Slovenian cities were successfully analyzed.

"Available online 11 June 2022", The objective of this study was to assess the degradation rates of chrysene and benzo[a]pyrene, as well as the removal of aluminium and iron from contaminated soil collected in the upper layer (030 cm) in Lagos, Southwest Nigeria. Trametes versicolor was isolated from this soil and used in degradation experiments, with plantain peels as support. After 8 weeks, 82.0% of chrysene degradation was achieved by T. versicolor, and by adding support this increased to 91.0%. Benzo[a]pyrene was less degradable, with 38.0% and 49.1% of degradation, respectively. Trametes versicolor was also capable of accumulate 46.1% of aluminium and 57.2% of iron. By adding plantain peels, these amounts increased to 48.2% and 61.8%, respectively. At the same time, laccase was produced by Trametes versicolor on plantain peels, achieving 37.8 U/g of crude laccase during SSF at 30 °C for 3 weeks. Laccase degradation experiments were set up in packed-bed reactor (PBR), with a constant feed of 21.6 mL/day of laccase, with and without mediators. In 35 days, 75.9% degradation of chrysene was achieved by laccase. The highest degradation was observed with ABTS (2,2-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid diammonium salt) as mediator, 87.9%. Benzo[a]pyrene degradation with laccase reached 35.6%, raising to 38.8 % with ferulic acid as mediator. In addition, 99.2% of iron and 99.6% of aluminium was removed by laccase, being the treatment for this last mediated with ABTS., This study was supported by the Portuguese Foundation for Science and Technology (FCT), Portugal under the scope of the research project PTDC/AAG-TEC/5269/2014, the strategic funding of UID/BIO/04469/2013 unit and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte. Ziva Vipotnik is a recipient of a fellowship supported by a doctoral advanced training (call NORTE-69-2015-15) - Doctoral Program in Applied and Environmental Microbiology (DP_AEM); operation NORTE-08-5369-FSE-000060; co-financed by North 2020 through the European Social Fund (ESF)., info:eu-repo/semantics/publishedVersion

The production of biobased copolymers such as poly(styrene-co-butyl acrylate-co-methacrylic acid) for paints and coating applications is indispensable for the establishment of sustainable biorefine...

The enzyme-catalyzed degradation of the biogenic amine serotonin is an essential regulatory mechanism of its level in the human organism. In particular, monoamine oxidase A (MAO A) is an important flavoenzyme involved in the metabolism of monoamine neurotransmitters. Despite extensive research efforts, neither the catalytic nor the inhibition mechanisms of MAO enzymes are currently fully understood. In this article, we present the quantum mechanics/molecular mechanics simulation of the rate-limiting step for the serotonin decomposition, which consists of hydride transfer from the serotonin methylene group to the N5 atom of the flavin moiety. Free-energy profiles of the reaction were computed by the empirical valence bond method. Apart from the enzymatic environment, the reference reaction in the gas phase was also simulated, facilitating the estimation of the catalytic effect of the enzyme. The calculated barrier for the enzyme-catalyzed reaction of 14.82 +/- 0.81 kcal mol(-1) is in good agreement with the experimental value of 16.0 kcal mol(-1), which provides strong evidence for the validity of the proposed hydride-transfer mechanism. Together with additional experimental and computational work, the results presented herein contribute to a deeper understanding of the catalytic mechanism of MAO A and flavoenzymes in general, and in the long run, they should pave the way toward applications in neuropsychiatry.

Organocatalyzed ring-opening polymerization (ROP) of e-caprolactone (CL) and 4,4′-bioxepanyl-7,7′-dione as a bis-lactone cross-linker was performed within the oil-in-oil high internal phase emulsions (HIPEs) at 50 °C. In this way, the cross-linked poly(e-caprolactone) (PCL) polyHIPE foams of ∼85% porosity were synthesized. Thermomechanical properties of the prepared polyHIPEs were studied and proved to greatly depend on a degree of PCL cross-linking. The melting and crystallization temperatures as well as the degree of crystallinity of PCL polyHIPE foams decrease with an increasing cross-linking degree. Semi-crystalline polyHIPEs demonstrate shape memory behavior with excellent shape fixity and shape recovery. At an appropriate degree of PCL cross-linking, the polyHIPE temporary shape can be fixed at room temperature, while a transition to the permanent shape occurs upon heating at 40 °C. Moreover, a two-way shape memory behavior of the PCL polyHIPEs under constant stress was observed.

Despite the fact that the methanol synthesis process includes industrially some of the most important catalytic chemical reactions, it is still not clear how different gaseous species impact cataly...

While the function of enzymes has been well-known to researchers for decades, the driving force behind it is still a hotly debated topic. Herein, we report significant evidence for electrostatics being that driving force, using a simple, computationally inexpensive, multiscale model of monoamine oxidase A and phenylethylamine. We found that electrostatics provided by the enzyme substantially enhances the reaction by all the considered criteria (lowering the energy barrier, increasing charge transfer, decreasing the highest occupied molecular orbital–lowest unoccupied molecular orbital (HOMO–LUMO) gap, increasing the dipole moment). The catalytic effect can be rationalized by the stabilizing interaction between the dipole moment of the reacting moiety and the electric field exerted by the charged environment. Both the dipole moment and the electric field are perceivably larger in the transition state as compared to the state of reactants; hence the transition state is stabilized to a larger extent and bett...

Semi-interpenetrating polymer networks (semi-IPNs) were prepared by in situ simultaneous orthogonal polymerizations, where the linear poly(e-caprolactone) (PCL) was synthesized by ring-opening polymerization of e-caprolactone and the poly(styrene-co-divinylbenzene) (PS) network was formed by free-radical polymerization of styrene/divinylbenzene. Semi-IPNs were used as the precursors for the preparation of porous PS monoliths. To this end, the PCL domains were selectively removed by hydrolysis under basic conditions. By changing the amount of organocatalyst used for the ring-opening polymerization of e-caprolactone, the relative polymerization kinetics of both monomers was varied, which has a pronounced effect on the morphology of thus-obtained PS frameworks.

A fast, robust, and convenient method for quantitative determination of polyamide-6 (PA6) and polyamide-66 (PA66) in plastic wastes is presented. The method includes a straightforward procedure for...

The ultimate goal in the understanding of complex chemical processes is a complete description of the underlying reaction mechanism. In the present study and for this purpose, a novel experimental platform is introduced that builds upon electrochemistry capable of generating reactive intermediate species at the electrode surface. The atmospherically relevant nitration of catechols is taken as a case example. First, we confirm the recently proposed nitration mechanism, advancing the understanding of atmospheric brown carbon formation in the dark. We are able to selectively quantify aromatic isomers, which is beyond the limits of conventional electroanalysis. Second, we identify a new pathway of nitrocatechol hydroxylation, which proceeds simply by oxidation and the addition of water. This pathway can be environmentally significant in the dark aqueous-phase formation of secondary organic aerosols. Third, the developed methodology is capable of selectively detecting a wide range of nitroaromatics; a possible application in environmental monitoring is proposed.

Solvent- (SB) and water-borne (WB) fluoropolymer coatings were produced for the outdoor protection of bronze. The coatings were prepared from commercially available resins with alternating fluoroethylene/vinylether copolymers. Because any application of protective coatings on works of art requires that they be removable in accordance with conservation ethics, various approaches to achieve removability of coatings were tested. The influence of modifications was verified through comparisons of hydrophobic, compact and irremovable protective coatings. Consequently, we prepared four types of coatings: two SB coatings and two WB coatings. The first SB coating was designed to have a hydrophobic compact structure (SB-c coating), and the second SB coating was modified with the addition of agents that impart strippability (SB-h coating). The same approach was used for the preparation of the two WB coatings: a compact (WB-c) coating vs. a hydrophilic (WB-h) coating, the latter being prepared through the addition of hydrophilic polyisocyanate. The surface properties of the coatings were compared using scanning electron (SEM) and atomic force (AFM) microscopy. WB coatings were found to be more homogeneous in comparison with SB coatings and to have lower surface roughness. Contact angles confirmed the more hydrophobic nature of SB coatings. Potentiodynamic polarisation measurements and accelerated corrosion tests (exposure to acid vapours) revealed that protection efficiency not only increased with thickness but significantly depended on the coating structure. The structure of coatings depended on the rheological parameters of the formulations simulating their behaviour during storage, deposition, and formation of the dry coating. Combined electrochemical and vibrational spectroscopic experiments were used to simulate long-term outdoor exposure of the protective coatings. Ex situ IR RA spectroelectrochemical measurements showed that hydration was more prevalent with WB coatings, and oxidation of bronze at the interface eventually occurred (656 cm −1 band). WB coatings with more free C O groups were more prone to degradation. In situ Raman spectroelectrochemistry confirmed the better protection efficiency of SB over WB coatings. The optical properties of the coatings on glass showed higher transmittance for WB coatings compared to SB coatings.

The use of rare earth elements is a growing trend in diverse industrial activities, leading to the need for eco-friendly approaches to their efficient recovery and reuse. The aim of this work is the development of an environmentally friendly and competitive technology for the recovery of those elements from wastewater. Kinetic and equilibria batch assays were performed with zeolite, with and without bacterial biofilm, to entrap rare earth ions from aqueous solution. Continuous assays were also performed in column setups. Over 90% removal of lanthanum and cerium was achieved using zeolite as sorbent, with and without biofilm, decreasing to 70% and 80%, respectively, when suspended Bacillus cereus was used. Desorption from the zeolite reached over 60%, regardless of the tested conditions. When in continuous flow in columns, the removal yield was similar for all of the rare earth elements tested. Lanthanum and cerium were the elements most easily removed by all tested sorbents when tested in single- or multi-solute solutions, in batch and column assays. Rare earth removal from wastewater in open setups is possible, as well as their recovery by desorption processes, allowing a continuous mode of operation., This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the research project PTDC/AAG-TEC/5269/2014, the strategic funding of UID/BIO/04469/2013 unit and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte, Portugal., info:eu-repo/semantics/publishedVersion

Two-component solvent-born polyurethane coatings for the protection of bronze from corrosion were prepared. Trisilanol-heptaisooctyl polyhedral oligomeric silsesquixane (POSS) nanoparticles were exploited to increase the coating protective efficiency. Its improvement was confirmed through a combination of characterisation techniques. In particular, the POSS addition caused an increase of the water contact angle, and an enhancement of the elastic connotation and abrasion resistance of the polyurethane coating. Potentiodynamic polarisation measurements also indicated that the coating containing POSS nanoparticles has an improved protection efficiency. Impedance spectroscopy revealed that the magnitude of low-frequency impedance of polyurethane coatings decreased more for the coating without POSS during exposure in electrolyte for thirty days. Ex situ IR reflection-absorption spectroelectrochemistry was exploited to get insight into the degradation of coatings during chronocoulometric charging at anodic potentials. IR reflection-absorption technique was also used to evaluate any possible effect of different stripper solutions on the bronze substrate.

Densities of ethanol-water mixtures have been measured using a vibrating tube densimeter and a different arrangement high-pressure experimental set-up. Measurements were carried out at 298,15 K in a pressure range from 0.1 MPa to 5MPa. Partial molar volumes, excess molar volumes and coefficients of isothermal compressibility were calculated. The molar volumes of alcohol and its partial molar volumes in mixtures with water are found to decrease monotonously with increasing pressure. Excess molar volumes are negative at all pressures. The numerical P-V relations at each composition are correlated satisfactorily as a function of pressure by the Hayward equation. Gostote mešanic etanola z vodo smo izmerili z gostometrom, ki je bil prirejen za visokotlačne poskuse. Meritve so potekale pri 298,15 K v območju tlakov od 0,1 MPa do 5 MPa. Iz izmerjenih gostot smo izračunali parcialne molske prostornine, presežene molske prostornine in koeficiente izometrične stisljivosti. Molske prostornine etanola in njegove parcialne molske prostornine v mešanicah z vodo se monotono zmanjšujejo s povečanjem tlaka. Pri vseh tlakih so presežene molske prostornine negativne. Numerične P-V zveze v odvisnosti od tlaka so za vsako sestavo raztopine podane s Hayworthovo enačbo.