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Microvawe synthesis of disubstituted pyrrolidine-2,5-dione derivatives
No full textSuccinimide (pyrrolidine-2,5-dione) derivatives are organic compounds with a broad spectrum of pharmacological activities. Analogs of this cyclic ureide are well-known and comercially available anticonvulsants (ethosuccinimide, metosuccinimide and fensuccinimide), antipsychotics, sedatives, anticancer and antiviral agents. In this paper, using a modified microwave procedure, three succinimide derivatives were synthetized and completely structurally characterized by determination of melting points, as well as FT-IR/ATR, 1H NMR, 13C NMR and elemental analysis. The influence of chemical structure on the pharmacological activity of succinimide derivatives was evaluated using the pioneering "rule of five", Veber, Egan, and Ghose’s empirical criteria, as well as using different in silico methods. Obtained values of molecular descriptors were compared with the characteristic values for reference drugs such as methosuccinimide and ethosuccinimide. Calculated molecular descriptors suggest that the investigated compounds fulfill necessary empirical criteria which qualify them as interesting drug candidates. The obtained descriptors indicate a high degree of gastrointestinal absorption (98%) of the synthesized succinimide derivatives. They are expected to successfully pass through the blood-brain barrier due to the adequate lipophilicity
Microbial applications of natural zeolite
No full textNatural zeolites (NZ) have found numerous applications in the life science such as
medicine, agriculture, and environmental protection, in practical applications, and in basic
research. Various ways in which natural zeolites are used in microbiology, where they are
desirable due to their non-toxicity and ion exchange capacity, are presented here. Natural
zeolites of the clinoptilolite type are excellent bacterial carriers with potential applications in
biotechnology. When modified with heavy metals, the zeolites could fill biofilters and be used
in wastewater treatment. Since zeolites facilitate biofilm growth, they can be used as an
excellent support and model material that enables biofilm formation in porous media and
subsequent visualization of biofilm in 3D by using X-ray microtomography
SrTiO3-based nanoparticles in dental poly(methyl methacrylate): mechanical and thermal properties
No full textPoly(methyl methacrylate) (PMMA) for dental application offers advantages such as ease of
fabrication, cost-effectiveness, and favorable physical and mechanical properties. However,
these characteristics alone do not provide sufficient impact strength and hardness. As a result,
pure PMMA is less suitable for dental applications. This research aimed to enhance the impact
resistance and hardness of PMMA by incorporating hybrid nanoparticles based on SrTiO3
(STO). Field emission scanning microscopy was used for the identification of agglomerates in
the composites, as well as for the determination of toughening mechanisms at the fracture
surface. Various toughening mechanisms were observed, with crack pinning being dominant.
Differential scanning calorimetry was conducted to study the influence of nanoparticles on the
glass transition temperature (Tg) of PMMA. It was established that there was no significant
influence on Tg. Mechanical property investigations revealed that the STO-based hybrid
reinforcements significantly improved microhardness and total absorbed impact energy. The
results of this study highlight the reinforcing potential of hybrid nanoparticles, suggesting that
their application does not have to be limited to PMMA
Designing biopolymer scaffolds and oral mucoadhesive films for controlled drug delivery
No full textThere is a great potential to use electrospun nanofibers and 3D-printed structures as drug carriers
for biomedical applications, due to the possibility of delivering drugs at a controlled rate over some time at the site of
action.ExcellMater Conference 2024: Innovative Biomaterials for Novel Medical Devices, Belgrade, Serbia, April 10-12, 202
FLY ASH – FROM WASTE MATERIAL TO RAW MATERIAL FOR OBTAINING STRATEGICALLY IMPORTANT ELEMENTS Optimization of extraction methods and influence on leaching of toxic and rare earth elements from coal fly ash – chemometric approach
No full textSagorevanjem uglja u termoelektranama u Republici Srbiji svakodnevno se izdvaja velika količina letećeg pepela, kao otpadnog materijala, Ovaj otpad, pored toga što sadrži zagađujuće materije, kao što su teški metali i toksični elementi (olovo, arsen, kadmijum, živa), sadrži i retke elemente zemlje i plemenite metale, koji su danas prepoznati kao strateški elementi. U ovom radu predstavljen je postupak optimizacije metoda pripreme uzoraka letećeg pepela i efekat koji način pripreme ima na ekstrakciju elemenata iz pepela i njihove konačne koncentracije. Uzorci letećeg pepela uzorkovani su u termoelektranama Nikola Tesla blokovi A i B. Uzorci su tretirani na više načina: digestijom mineralnim kiselinama HNO3/HF/HCl i digestijom smešom kiselina HNO3/H2SO4 uz V2O5 kao katalizator, na različitim temperaturama i pri različitim vremenima digestije. Ekstrahovani elementi određeni su metodom indukovane spregnute plazme sa optičkim emisionim detektorom (ICP-OES), dok su elementi retkih zemalja zbog izuzetno niskih koncentracija određeni korišćenjem masenog detektora, ICP-MS. Rezultati ispitivanja pokazali su da način pripreme uzorka, s obzirom na kompleksnost matrice, ima veliki uticaj na dobijene koncentracije izluženih elemenata. Za dizajniranje eksperimenta, optimizaciju procesa i ocenu efikasnosti ekstrakcije primenjen je hemometrijski pristup. Relevantne multivarijacione metode statističke analize (PCA, HCA, ANN) primenjene su kao vrlo koristan alat u obradi ogromnog broja podataka dobijenih eksperimentima u cilju pronalaženja korelacija uzmeđu retkih i toksičnih elemenata i dobijanja korisnih informacija i zaključaka vezanih za iskorišćenje letećeg pepela kao resursa za strateški važne elemente kao i za predikciju budućih istraživanja.Large amount of coal fly ash is generated as waste material from thermal power plants in Serbia. In is well known that fly ash contains pollutants such as heavy metals and toxic elements (lead, cadmium, arsenic, mercury), as well as rare earth elements, nowadays recognized as strategic elements. In this research, two methods of sample preparation have been examined in order to determine the effect of digestion method on the extraction efficiency. The coal fly ash was sampled from Nikola Tesla thermal power plant, blocks A and B. Ash samples were prepared using two digestion procedures: 1) with mineral acids mixture HNO3/HF/HCl, and 2) with a mixture of acids HNO3/H2SO4 with V2O5 as catalyst, at different temperatures and at different times of digestion. Extracted elements are determined using the ICP-OES and ICP-MS techniques, respectively. It has been shown that the method of sample preparation, considering the matrix complexity, has a great impact on the obtained results. A chemometric approach was used to design the experiment, optimize the process and evaluate the extraction efficiency. Relevant multivariate methods of statistical analysis (PCA, HCA, ANN) were applied as a very useful tool in processing a huge amount of data obtained by experiments with the aim of finding correlations between rare and toxic elements and obtaining useful information and conclusions related to the use of fly ash as resources for strategically important elements as well as for the prediction of future research.Rad po pozivu na međunarodnom skup
Assessment of Environmental Risk of Fly Ash Disposal
No full textDeponovanje letećeg pepela, kao jednog od osnovnih produkata sagorevanja uglja u termoelektranama, može izazvati brojne negativne ekološke posledice. U sastav letećeg pepela, pored osnovnih mineralnih materija (SiO2, Fe2O3 i Al2O3), ulaze u manjoj ili većoj meri i toksični elementi kao što su: Cd, Co, Cr, Cu, Mn, Ni, Pb, Zn, As i Hg. U okviru ovog istraživanja izvršena je procena ekološkog rizika na osnovu kvantitativnih faktora – ekološkog faktora rizika (ER) i indeksa rizika (RI) u sedam različitih uzoraka letećeg pepela prikupljenih iz termoelektrane Nikola Tesla. Uzorci su pripremani metodom mikrotalasne digestije smešom koncentrovanih mineralnih kiselina HNO3/HCl/HF, dok su koncentracije izluženih metala određene tehnikom ICP-OES. Rezultati su pokazali da pet uzoraka letećeg pepela pokazuje veoma visok nivo rizika, dok ostala dva uzorka pokazuju visok nivo rizika. Elementi koji su pokazali najveći nivo rizika po životnu sredinu su Cd, As i Hg.The deposition of fly ash, a primary byproduct of coal combustion in thermal power plants, can lead to numerous negative environmental consequences. Apart from its basic mineral components (SiO2, Fe2O3, and Al2O3), fly ash may contain toxic elements such as Cd, Co, Cr, Cu, Mn, Ni, Pb, Zn, As, and Hg. In this study, ecological risk was assessed using quantitative factors - ecological risk factor (ER) and risk index (RI) - across seven different samples of fly ash collected from the Nikola Tesla thermal power plant. The samples were prepared using the microwave digestion method with a mixture of concentrated mineral acids (HNO3/HCl/HF), and the concentrations of leached metals were measured using the ICP-OES technique. The results indicate that five ash samples exhibit a very high level of risk, while the remaining two samples show only a high level of risk. Elements posing the highest environmental risk include Cd, As, and Hg
„SILKO ZA TRAVE I ŽITARICE“ – NOVI INOKULANT ZA SILIRANJE I SENAŽU TRAVA I ŽITARICA
No full textOdrživa poljoprivreda podrazumeva efikasnu proizvodnju visokokvalitetnih poljoprivrednih proizvoda, sa ciljem da se zaštiti životna sredina, obezbedi zdravlje i dobrobit životinja, održivih društvenih i ekonomskih uslova za farmere, radnike i lokalne zajednice. Sa brzim razvojem globalne ekonomije, nivo potrošnje i potražnje za proizvodima životinjskog porekla kao što su meso, mleko i jaja se po glavi stanovnika značajno povećavaju. Uporedo sa razvojem stočarstva, potrebe za kvalitetnom hranom za životinje se takođe povećavaju. Osnova savremenog koncepta ishrane preživara zasniva se na balansiranoj upotrebi hraniva i kvalitetne nutritivno visoko vredne kabaste hrane u vidu sena, senaže ili silaže. Fermentisana hrana za životinje, silaža, se vrlo često uvodi u ishranu stoke, jer je brojnim studijama i praksom potvrđeno da ovakva hrana ima pozitivan uticaj na kvalitet (sadržaj hranljivih materija, uključujući proteine), ukus i izgled mesa, poboljšava se mramornost mesa i smanjuje se sadržaj vode. Fermentacija je proces u kome se ugljeni hidrati rastvorljivi u vodi (eng. water soluble carbohydrates – WSC) pod anaerobnim uslovima pretvaraju u organske kiseline, uglavnom mlečnu kiselinu, pomoću bakterija mlečne kiseline (lactic acid bacteria – LAB). Raznovrsnost mikrobioma biljnih useva može tok fermentacije da usmeri u negativnom smeru, tačnije da se podstakne rast patogenih mikroorganizama kao što su E. coli, B. cereus, Clostridium botulinum, L. monocytogenes, kvasci i plesni tokom siliranja, što daje nekvalitetnu hranu koja može biti izvor teških bolesti kod ljudi i životinja. Pronalaženje pravog rešenja za siliranje je i dalje veliki izazov, iako na tržištu postoje izvesni preparati koji daju dobre rezultate kada je u pitanju spravljanje silaže. Inokulanti se dodaju u toku procesa siliranja da bi se povećala brojnost pozitivnih bakterija u poređenju sa prirodnom populacijom bakterija koja se nalazi na biljnom materijalu koja prouzrokuje gubitke suve materije usled neadekvatnog iskorišćenja šećera. Predloženi postupak pored uvođenja inokulanata homo- i heterofermentativnih bakterija mlečne kiseline Lactobacillus plantarum; Lactobacillus buchneri; Lactobacillus casei u proces siliranja, obuhvata uvođenje i enzimskih aditiva, konkretno ksilanaza. Potencijal za primenu ksilanaza se nalazi u činjenici da je ovo grupa enzima koja hidrolizuje hemiceluloznu frakciju biljne ćelije, čime se povećava prinos rastvorljivih šećera što dalje znači intenzivniji metabolizam bakterija mlečne kiseline, tačnije veću produkciju mlečne kiseline i snižavanje pH vrednosti, pri čemu je sprečen rast mikroorganizama uzročnika kvarenja silaže. Postupak proizvodnje novog inokulanta je u potpunosti razrađen sa aspekta selekcije i odabira mikroorganizama, bakterija mlečne kiseline i bakterija producenata ksilanaza. 3 Potom, optimizovan je celokupan postupak fermentacije sa ciljem maksimalne produkcije bakterijskih ksilanaza. Dobijene ksilanaze nakon biohemijske karakterizacije u kombinaciji sa inokulantima mlečne kiseline su testirane na lignoceluloznim supstratima. Rezultati u okviru ovog Tehničkog rešenja su pokazali da je preparat „Silko za trave i žitarice“ efikasan u procesu siliranja trava i žitarica, što je potvrđeno proverama pH vrednosti silirane trave i žitarica, sadržaja vlakana (NDF i ADF), sadržaja suve materije i proteina, kao i sadržaja sirćetne, propionske i buterne kiseline. Prijavu ovog Tehničkog rešenja treba uputiti Matičnom naučnom odboru za biotehnologiju i poljoprivredu Ministarstva prosvete nauke i tehnološkog razvoja.Usvojena kategorija M8
A step towards tuning the jute fiber structure and properties by employing sodium periodate oxidation and coating with alginate
No full textThis paper outlines a novel simple protocol for tuning the structure and properties of jute using sodium periodate (NaIO4) oxidation and coating with alginate. When compared to the raw jute, fabrics oxidized with a 0.2 or 0.4 % NaIO4 solution for 30–120 min exhibited an increased aldehyde group content (0.185 vs. 0.239–0.398 mmol/g), a significantly increased negative zeta potential (from − 8.57 down to − 20.12 mV), a slight disruption of fiber crystallinity, 15.1–37.5 % and 27.9–49.8 % lower fabric maximum force and stiffness, respectively. Owing to the removal of hydrophobic surface barrier, decreased crystallinity index and the presence of micropores on the
fabrics' surfaces, oxidized fabrics have a 22.3–29.6 % improved ability for moisture sorption compared to raw fabric. Oxidized fabrics characterized by very long wetting times and excellent antioxidant activities (> 98 %), can find applications as hydrophobic packaging materials. To further extend the utilization of jute in biocarpet engineering such as water-binding geo-prebiotic supports, oxidized fabrics were coated with alginate resulting in 7.9–24.9 % higher moisture sorption and 352–660 times lower wetting times than their oxidized counterparts. This modification protocol has never been applied to lignocellulosic fibers and sheds new light on obtaining jute fabrics with tuned structure and properties intended for various applications.Supplementary information: [https://technorep.tmf.bg.ac.rs/handle/123456789/7334
Effects of Water Immersion on Mechanical Properties of Kevlar Composites Reinforced with ZnO Nanoparticles
No full textThe Kevlar fabric composites have a wide range of applications in the
body armor and lightweight vehicle-armor structures. Nanoparticles are one of the
most common nanofillers for these structures. In this research, the testing specimens have been made from the Kevlar fabrics impregnated with the poly (vinyl
butyral)/ethanol solution which had been reinforced with the ZnO nanoparticles.
The two-layered composite samples have been fabricated by means of hot compression. The immersion of the square Kevlar/PVB specimens for the water uptake
measurements has been performed according to the ISO 62 standard. The specimens have been immersed in a water bath filled with the distilled water (40 °C) in
the period of 8 weeks. The Kevlar/PVB specimens have been tested in accordance
with the ASTM D 3039 standard for the tensile properties and the ASTM D 790–
03 standard for the flexural properties. The tensile and bending characteristics of
the dry specimens have been compared with the ones that had undergone the water
immersion
Selection of processing parameters for the integrated supercritical CO2 extraction from green tea leaves and extract impregnation onto starch-chitosan based films
No full textThe study aimed toward the development of biocompatible and biodegradable polymeric films (starch-chitosan and starch-chitosan-cyclodextrin) with biologically valuable green tea leaf extract using an environmentally friendly integrated process of supercritical fluid extraction (SFE) and supercritical solvent impregnation (SSI). The SFE-SSI process parameters were selected through the initial estimation of the SFE parameters effect (temperatures 35 and 70 °C and the addition of co-solvents ethanol, ethanol/water, and water). The present early-stage work showed that an increase in temperature increased extraction yield (from 0.9 to 4.2%) and caffeine content while it decreased polyphenolic and pigment content as well as antioxidant activity and extract loading onto films (from 7.1 to 0.1%). The addition of co-solvents to sc-CO2 had an adverse effect on extract yield, composition, and loading. The highest recorded total phenolic, flavonoid, chlorophyll A, and caffeine content in extracts were 136.5 mg GE/g, 22.7 mg RE/g, 8.1 mg/g, and 460.0 mg/g, respectively