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Примена инверзне гасне хроматографије при нултој и коначној прекривености за испитивање адсорпције органских мoлекула на зеолиту и композиту зеолита и гвожђе-оксихидроксида
No full textThe surfaces of natural (NZ) and zeolite/iron oxyhydroxide composite (ZFe) samples were analysed by means of inverse gas chromatography (IGC) using the adsorption data of organic non-polar and polar probes, in the infinite and finite-dilution regimes, in the temperature range 483-513 K. The dispersive components of the free energy of adsorption, γS, determined by the Gray method, decreased with increasing temperature for both zeolites. The specific interactions were characterised by the specific free adsorption energy change, ΔGaS, the specific enthalpy change of adsorption, ΔHaS, as well as the donor and acceptor interaction parameters (KA, KD) and the basic character of the NZ and ZFe was evidenced. The adsorption isotherms of n-hexane, benzene, chloroform and tetrahydrofuran (THF) were determined under finite surface coverage and used to estimate the specific surface area and the adsorption energy distribution. The adsorption capacity of the ZFe was higher than for NZ for all the investigated adsorbates. The specific surface areas and pore size distributions were also determined using nitrogen adsorption-desorption isotherms, i.e., the BET method. It was observed that the nature of the adsorbate and the properties of the solid surface of the initial and modified samples governed the uptake of adsorbates.Применом инверзне гасне хроматографије, испитана су површинска својства природног зеолита (NZ) и композита зеолита и гвожђе-оксихидроксида (ZFe), коришћењем поларних и неполарних проба у условима нулте и коначне прекривености у температурном опсегу 483–513 K. Вредности дисперзивне компоненте слободне енергије адсорпције, γS, одређене методом Греја, опадају са порастом температуре за оба зеолита. Одређивањем промене специфичне слободне енергије адсорпције, ΔGa S, и промене специфичне енталпије адсорпције, ΔHa S, које одговарају кисело/базним интеракцијама на чврстој површини, одређени су и акцепторски и донорски параметри (KА и KD) на основу којих је утврђено да су површине узорака NZ и ZFe базног карактера. На основу добијених адсорпционих изотерми за n-хексан, бензен, хлороформ и тетрахидрофуран, применом инверзне гасне хроматографије у условима коначне прекривености, израчунате су вредности специфичне површине као и расподела адсорпционе енергије. Капацитет адсорпције узорка ZFe је био већи у односу на капацитета узорка NZ, за све испитане адсорбенте. Специфична површина узорака као и расподела величине мезопора одређени су применом адсорпионе/десорпционе изотерме за гасовити азот, односно применом BET методе. Закључено је да су природа адсорбата и површинска својства адсорбената главни фактори који одређују капацитет адсорпције
The current trend in innovative bioactive materials for dental and orthopedic applications
Get PDFBioactive materials for the repairand regeneration of human bone tissue, as well as for the restoration of teeth, are the focus of numerous studies in the field of biomaterials.Orthopaedic surgeons anticipate that bioactive materialshave the potential to facilitate the formation of new apatite-like crystals upon contact with body fluids, promoting the development of new bone tissue under in vivoconditions. On the other hand, dentists expect that bioactive materials have the potential for remineralization of partially demineralized enamel and dentin. In the preceding years, the Bioceramic Materials Group, founded within the Department of Inorganic Chemical Technology at the Faculty of Technology and Metallurgy, University of Belgrade (FTM-UB), conducted extensive research on the advancement of bioactive and biocompatible materials with adequate mechanical properties, designed for applicationin dentistry, orthopaedics, maxillofacial surgery, and also bone tissue engineering(BTE).ExcellMater Conference 2024: Innovative Biomaterials for Novel Medical Devices, Belgrade, Serbia, April 10-12, 202
Delignifikacija kukuruzne stabljike primenom zelenih rastvarača
No full textLignoceluloza čini glavnu komponentu poljoprivrednog i organskog komunalnog otpada. Zahvaljujući svom sastavu, koji uključuje visok sadržaj šećera, dostupnosti i biorazgradivosti, predstavlja kvalitetnu polaznu sirovinu u biorafinerijskim procesima. Razgradnja kompleksne lignocelulozne strukture je ključni korak u njenoj valorizaciji. Konvencionalne metode za razgradnju lignoceluloze zasnivaju se na upotrebi jakih kiselina i baza i/ili visokih temperatura i pritisaka, čineći ih energetski, ekonomski i ekološki nepovoljnim. Jedan od načina da se ovaj problem prevaziđe je upotreba tzv. „zelenih“ rastvarača, poput vode i etanola. Predmet ovog rada je upotreba zelenih rastvarača u kombinaciji sa gasnom plazmom za razgradnju lignocelulozne biomase pri atmosferskim uslovima. Kukuruzna stabljika je korišćena kao model supstrat, pripremljen sa vodom ili 96% etanolom kao rastvaračima. Za tretman gasnom plazmom korišćena je netermalna gasna plazma igla. Efikasnost primenjenih tretmana praćena je sa aspekta delignifikacije kukuruzne stabljike i naknadne enzimske hidrolize tretirane frakcije. Sadržaj lignina u uzorcima nakon tretmana određivan je na osnovu njegove rastvorljivosti u acetil bromidu (ABSL – acetyl-bromide soluble lignin, engl.). Frakcije dobijene nakon tretmana su podvrgnute enzimskoj hidrolizi sa komercijalnom smešom celulaza, hemicelulaza i ?-galaktozidaza, Cellic CTec 2 (Novozymes, Danska). Nakon 48-časovne hidrolize u dobijenim hidrolizatima je određivan sadržaj heksoza i pentoza. Sadržaj lignina smanjen je za 40% tokom tretmana plazmom u trajanju od 30 minuta u etanolu. U slučaju vode razgrađeno je 20% lignina pri istoj dužini tretmana. Međutim, produžavanjem dužine tretmana na 60 minuta u vodi postignuta je značajna delignifikacija, smanjenjem sadržaja lignina za 50% u odnosu na netretiranu biomasu. Dodatno produžavanje tretmana plazmom na 90 minuta nije dovelo do povećanja stepena delignifikacije. Prinosi šećera ostvareni nakon hidrolize su u skladu sa delignifikacijom, pri čemu je najveći prinos postignut nakon plazma tretmana u etanolu tokom 30 minuta, odnosno u vodi tokom 60 minuta. Primenom kombinovanog plazma tretmana moguće je razgraditi lignin i olakšati prodor enzima do ugljeno-hidratne komponente lignoceluloze pri atmosferskim uslovima, bez upotrebe jakih kiselina, baza ili organskih rastvarača. Upotrebom navedenih zelenih rastvarača smanjuje se potreba za dodatnim koracima prečišćavanja tretirane biomase, a i naknadne faze enzimske hidrolize i fermentacije su značajno jednostavnije. Osim toga, moguća je rekuperacija iskorišćenog etanola, što je u skladu sa principima cirkularne bioekonomije
Recovery of Rare Earth Elements from Coal Fly and Bottom Ashes by Ultrasonic Roasting Followed by Microwave Leaching
No full textConsidering the rising demand for rare earth elements (REEs), researchers are looking for new sources for their extraction, thereby fostering economic and environmentally justified processing solutions. Among potential industrial sources, coal fly ash emerges as one of the most promising. The recovery of REEs from coal fly and bottom ashes derived from different thermal power plants was the main focus of this study. A dual-step methodology was conducted on ash samples, which involved an ultrasonic roasting process to disintegrate the silica matrix, followed by a microwave-assisted acid leaching step to extract REEs. The roasting procedure was studied using the Plackett–Burman design, and the Box–Behnken design was subsequently implemented to optimize the leaching procedure. The optimized ultrasonic roasting procedure was set up at 95 °C for 10 min with an ash-to-roasting agent (3M NaOH) ratio of 0.5:1 (m/V). For acid leaching, the optimal conditions were obtained at 174 °C for 30 min with an HCl ÷ HNO3 mixture (1:1 V/V). The standard reference material (NIST 1633c) was used in the conclusive experiments to estimate the average recovery (80%) of REEs. The green aspects of this methodology were evaluated using several metrics (atom economy, E-factor, and energy consumption). The proposed process outperforms high-temperature roasting procedures in terms of greenness; however, the REE recovery rate is lower
Mineralogical Characterization of the Grot Lead and Zinc Mine Tailings from Aspects of Their Further Use as Raw Material
No full textThe possibility of using waste tailings produced by flotation in the lead and zinc mine of Grot, Serbia as a potential source of secondary mineral raw materials was examined. The aim of the research was primarily to carry out a detailed characterization in order to determine the dominant minerals, and, for the first time, to trace the changes occurring in the unit cells of the minerals present in that deposit. There was also a need to determine the exact proportions of the present mineral phases for their further application and utilization as natural resources in environmental protection. Samples were taken from three different sections of tailings: the crest of dam (JKB), outlet pipe of the flotation facility (JOF) and hydrocyclone overflow (JHC). Granulometric separation was performed to facilitate the extraction of certain minerals from waste. The results showed that all samples mainly contained quartz, clinochlore, calcite, albite, pyrite and biotite, but their ratios in each sample varied significantly. After characterization, samples were separated into different fractions and their mineralogical compositions were determined. Depending on the fraction, the mineralogical compositions also changed. Mineralogy and geochemical analysis indicate that waste tailings can be used as a secondary mineral raw materials source applicable in various industries
Resistive switching memories with enhanced durability enabled by mixed-dimensional perfluoroarene perovskite heterostructures
No full textHybrid halide perovskites are attractive candidates for resistive switching
memories in neuromorphic computing applications due to their mixed
ionic-electronic conductivity. Moreover, their exceptional optoelectronic
characteristics make them effective as semiconductors in photovoltaics,
opening perspectives for self-powered memory elements. These devices,
however, remain unexploited, which is related to the variability in their
switching characteristics, weak endurance, and retention, which limit
their performance and practical use. To address this challenge, we
applied low-dimensional perovskite capping layers onto 3D mixed halide
perovskites using two perfluoroarene organic cations, namely (perfluorobenzyl)ammonium and (perfluoro-1,4-phenylene)dimethylammonium
iodide, forming Ruddlesden–Popper and Dion–Jacobson 2D perovskite
phases, respectively. The corresponding mixed-dimensional perovskite
heterostructures were used to fabricate resistive switching memories
based on perovskite solar cell architectures, showing that the devices
based on perfluoroarene heterostructures exhibited enhanced performance and stability in inert and ambient air atmosphere. This opens
perspectives for multidimensional perovskite materials in durable selfpowered memory elements in the future
Supramolecular assembly of zinc(II) complexes with pyridine/azo-based ligands carrying long carbon chains
No full textTwo zinc(II) complexes, [Zn3(OAc)6(L1)2] (1) and [Zn(NO3)2(L2)2] (2), were
synthesized using the ligands 2-(4-dodecyloxyphenylazo)pyridine (L1) and 2-(4-
dodecyloxyphenylazo)pyrimidine (L2) (Figure). Complex 1 crystallizes in the triclinic
P space group with Z = 1, with three Zn atoms coordinated by six bridging acetate ions
and two chelate L1 ligands, forming a centrosymmetric trinuclear structure. Complex 2
crystallizes in the monoclinic C2/c space group as a discrete mononuclear structure with
a six-coordinated Zn atom bonded to two chelate L2 ligands and two nitrate ions. The
development of the crystal packing was discussed through cooperativity of dimeric
motifs associated with different recognition modes. Single crystal X-ray analysis
revealed that the primary structural motif in both complexes involves ribbons formed
through various intermolecular interactions. Complex 1 exhibits ribbons stabilized by
C−H···O and π-π interactions, while complex 2 features ribbons stabilized only by C–
H···O interactions. The supramolecular ribbons in complex 1 are further linked by
C−H···N and C–H···π interactions, leading to its three-dimensional packing. In
contrast, the supramolecular networking of complex 2 is achieved through C–H···O, C–
H···N, and π-interactions. Hydrophobic interactions between the long alkyl chains of
the ligands further support the crystal structures of both complexes. The intermolecular
interactions were thoroughly examined using Hirshfeld surface analysis and 2D
fingerprint plots, providing insights into the packing and stability of these complexes
β-glucan-enriched fraction from mosaic puffball induces inflammation in an in vitro 3D bovine chondrocytes model
Get PDFFungal β-glucans are well-known for their immunomodulatory activity. They act as pathogen-associated molecular patterns (PAMPs) and can bind to a number of pattern-recognition receptors (PRRs). Activation of PRRs leads to inflammatory response and, although these receptors are primarily found in immune cells, chondrocytes express certain types of PRRs as well (toll-like receptors –TLRs). Although β-glucans are primarily considered immunestimulatory agents, recent research found that they may have beneficial effects in some inflammatory conditions (hence the term “immunomodulators”), in a complex way that is yet to be uncovered. The aim of this study was to investigate if the mushroom β-glucans could induce any changes in metabolic activity and phenotype of bovine chondrocytes, using a 3D cell culture model. For this purpose, glucan-enriched extract of mosaic puffball fruiting bodies, containing up to 70% (1→6)(1→3)β-D-glucan-protein complex was used.ExcellMater Conference 2024: Innovative Biomaterials for Novel Medical Devices, Belgrade, Serbia, April 10-12, 202
Physical aspects of epithelial cell–cell interactions: hidden system complexities
No full textThe maintenance of homeostasis and the retention of ordered epithelial cell self-organization are essential for morphogenesis, wound healing, and the spread of cancer across the epithelium. However, cell–cell interactions in an overcrowded environment introduce a diversity of complications. Such interactions arise from an interplay between the cell compressive and shear stress components that accompany increased cell packing density. They can lead to various kinds of cell rearrangement such as: the epithelial-to-mesenchymal cell state transition; live cell extrusion; and cell jamming. All of these scenarios of cell rearrangement under mechanical stress relate to changes in the strengths of the cell–cell and cell–matrix adhesion contacts. The objective of this review study is twofold: first, to provide a comprehensive summary of the biological and physical factors influencing the effects of cell mechanical stress on cell–cell interactions, and the consequences of these interactions for the status of cell–cell and cell–matrix adhesion contacts; and secondly, to offer a bio-physical/mathematical analysis of the aforementioned biological aspects. By presenting these two approaches in conjunction, we seek to highlight the intricate nature of biological systems, which manifests in the form of complex bio-physical/mathematical equations. Furthermore, the juxtaposition of these apparently disparate approaches underscores the importance of conducting experiments to determine the multitude of parameters that contribute to the development of these intricate bio-physical/mathematical models
Laser processing effects on Ti−45Nb alloy surface, corrosive and biocompatible properties
No full textThe Ti−45Nb (wt.%) alloy properties were investigated in relation to its potential biomedical use. Laser surface modification was utilized to improve its performance in biological systems. As a result of the laser treatment, (Ti,Nb)O scale was formed and various morphological features appeared on the alloy surface. The electrochemical behavior of Ti−45Nb alloy in simulated body conditions was evaluated and showed that the alloy was highly resistant to corrosion deterioration regardless of additional laser surface modification treatment. Nevertheless, the improved corrosion resistance after laser treatment was evident (the corrosion current density of the alloy before laser irradiation was 2.84×10−8 A/cm2, while that after laser treatment with 5 mJ was 0.65×10−8 A/cm2) and ascribed to the rapid formation of a complex and passivating bi-modal surface oxide layer. Alloy cytotoxicity and effects of the Ti−45Nb alloy laser surface modification on the MRC-5 cell viability, morphology, and proliferation were also investigated. The Ti−45Nb alloy showed no cytotoxic effect. Moreover, cells showed improved viability and adherence to the alloy surface after the laser irradiation treatment. The highest average cell viability of 115.37% was attained for the alloy laser-irradiated with 15 mJ. Results showed that the laser surface modification can be successfully utilized to significantly improve alloy performance in a biological environment