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Determination of the ductile-to-brittle transition temperature of NIOMOL 490 K steel welded joints
No full textThis paper is dedicated to the ductile–brittle transition behaviour of the microalloyed structural steel NIOMOL 490 K. This steel grade is used for welded pressure vessels subjected to dynamic loads and operating at sub-zero temperatures. Therefore, it must have an acceptable toughness. Due to its importance for the safety assessment of pressure vessels, a characterization of this steel was carried out using the Charpy V-notch impact test in the temperature range between −60 °C and + 60 °C. The notches were located in parent material, heat affected zone and weld metal. In this paper, the tensile strength properties at ambient temperature and the nil ductility temperature in the temperature range from −60 °C to + 60 °C are presented
The impact of sodium periodate oxidation and alginate coating on the capillarity of jute fabric
No full textThis study explores the impact of sodium periodate oxidation time (30min, 60min, or 120min) and alginate coating on the capillarity of jute fabrics. Raw jute fabric exhibits a rapid increase in capillary rise height (h) over time, reaching 72mm at 1200s. Fabrics oxidized for 30, 60, and 120min show significantly lower h values of 19, 18, and 28mm at 1200s, respectively, which can be ascribed to the oxidation process itself. Precisely, oxidation-induced conversion of hydroxyl
groups of cellulose (the main constituent of jute fiber) to aldehyde groups contributed to the fabric reduced affinity for water, hence negatively affecting its capillarity. Approximately 47% and 55% lower h values of fabrics oxidized for 30 and 60min compared to that oxidized for 120min can be explained by their lower weight loss after oxidation as well as less pronounced liberation of elementary fibers. Oxidized fabrics characterized by low capillarity can be used for the manufacturing of packaging materials, outdoor gear, and protective covers for crops. To expand jute fabric applications in biocarpet engineering, that is, to obtain polysaccharide-based supports, raw and oxidized jute fabrics were treated with a 1% sodium alginate solution. At 1200s, oxidized fabrics coated with alginate exhibited 4.3–5.8 times higher h values compared to solely oxidized counterparts. The diffusion coefficients of oxidized fabrics coated with alginate increase up to 35% with prolonged oxidation, emphasizing the oxidation impact on alginate binding
PLAZMA AKTIVIRANI VODENI EKSTRAKATI CVETA KOPRIVE KAO SUPSTRAT ZA GAJENJE BIOMASE LIGILACTOBACILLUS SALIVARIUS
No full textKopriva (Urtica dioica) je samonikla biljka bogata flavonoidima, karotenoidima, fitosterolima,
terpenima. Ima izuzetan farmaceutski potencijal zbog svojih antiinflamatornih, antioksidativnih i
diuretskih svojstava. Koristi se u ishrani, kao caj ili u formi suvih ili tecnih ekstrakta. U cilju
pobiljšanja karakteristika, bioraspoloživosti i stabilnosti ekstrakata, koriste se ekstrakcije ekološki
prihvatljivim rastvaracima, zeleni fizicki tretmani i fermentacija probiotickim bakterijama. Zeleni
rastvaraci kao što su voda, etanol i biokompatibilni eutekticke tecnosti su pogodni za dobijanje
ekstrakata u skladu sa principima održivog razvoja. Inovativni fizicki tretmani kao netermalni
tretman plazmom mogu obezbediti bolju ekstrakciju i mikrobiološku stabilnost posebno vodenih
ekstrakata. Takode, fermentacije bakterijama, kao što je Ligilactobacillus salivarius, mogu da
metabolišu jedinjenja prisutna u ekstraktima i biotransformišu glikozide, tanine i lignane u biološki
aktivnije oblike.
U radu smo ispitivali rast i antioksidativnu aktivnost vodenih ekstrakata cveta koprive dobijenih uz
tretman netermalnom plazmom i potom fermentaciju sa L. salivarius. Ispitali smo rast L. salivarius
u medijumima sa razlicitim udelom vodenog ekstrata cveta koprive i Man Rogosa Šarp (MRS) bujona
koji je koristi kao standardni mikrobiološki medijum za kultivaciju bakterija mlecne kiseline.
Antioksidativna aktivnost dobijenih ekstrakata je ispitana DPPH metodom, pre i nakon fermentacije.
L. salivarius je pokazao najbolji rast (11 log CFU/ml) u ekstraktima obogacenim sa 25% MRS. Potom
je je ispitivan rast L. salivarius u plazma tretiranom vodenom ekstraktu koprive sa 25% MRS. Nakon
tretmana netermalnom plazmom od 3 min i naknadne fermentacije ovih ekstrakata, postignut je rast
od 9 log CFU/ml i porast antioksidativne aktivnosti od 27% DPPH metodom. Uocen je pozitivan
kombinovani efekat netermalne plazme i fermentacije na povecanje antioksidativne aktivnosti,
posebno pri kracim tretmanima netermalnom plazmom. Rezultati rada ukazuju na mogucnost
primene zelenih tretmana i fermentacije za dobijanje proizvoda ekstrakta cveta koprive obogacenih
sa L. salivarius. Plazma tretman može uticati i na mikrobiološki sastav vodenih ekstrakata, kao
važnog aspekta za primenu u prehrambenoj i farmaceutskoj industriji
Concentration unit mistakes in health risk assessment of polycyclic aromatic hydrocarbons in soil, sediment, and indoor/road dust
No full textMechanical performance of denture acrylic resin modified with poly(4‐styrenesulfonic acid‐ co ‐maleic anhydride) sodium salt and strontium titanate
No full textSince acrylate-based materials are widely used in dentistry, their drawbacks such as low impact resistance and hardness, require continuous research in the field of materials science in order to avoid sudden fracture caused by chewing or fall. In this study, auto-polymerizing poly(methyl methacrylate) (PMMA), commonly used as denture base material, was reinforced with poly(4-styrenesulfonic acid-co-maleic anhydride) sodium salt (PSSMA) and strontium titanate (STO), with the aim of improving impact behavior and microhardness. Morphological analysis confirmed formation of phase-separated and co-continuous microscopic structures of PSSMA in PMMA, without visible agglomerates of STO nanoparticles, indicating that PSSMA-STO interaction contributed to a better distribution of nanoparticles. Fourier transformed infrared spectroscopy revealed that PSSMA and STO did not interfere in the polymerization of methyl methacrylate. This was further supported by thermal analysis, which also showed that the addition of PSSMA and STO had no significant influence on thermal degradation. On the other side, PSSMA and STO significantly enhanced mechanical performance of PMMA. The modulus of elasticity increased by up to 48.6%, total absorbed impact energy improved by up to 108.4%, and microhardness increased by up to 272.8% when PSSMA was combined with STO for reinforcing denture PMMA. These results demonstrate the significant potential of PSSMA, which could be combined with other ceramic nanoparticles for denture reinforcement in the future. Highlights: This research presents novel dental hybrid composite. Influence of strontium titanate (STO) and poly(4-styrenesulfonic acid-co-maleic anhydride) sodium salt (PSSMA) on poly(methyl methacrylate) (PMMA) was investigated. PSSMA/STO improved modulus of elasticity, microhardness and impact resistance. Sample with 5 wt% PSSMA and 1 wt% STO showed the highest improvement compared to PMMA. Presented hybrid composite could use as denture base material
Parametric study of bio-char production from the co-pyrolysis of tire and coffee wastes via fixed bed reactor
No full textCo-pyrolysis has become an eye-catching process for obtaining fuel and biochar and is attracting attention from both the scientific and industrial communities. One of the reasons for this is the wide variety of raw materials for the process itself and the possibility of obtaining attractive and high-quality products. The influence of three distinctive parameters has been studied on the co-pyrolysis reaction. These variables were temperature, reaction time, and plastic ratio. The results were analysed using Response Surface Methodology (RSM), and it was found that the optimum conditions to produce biochar from the co-pyrolysis of coffee and tire wastes were 359.441 °C, 10 minutes of reaction duration, and a plastic ratio of 97.8528 wt.%.Sharjah International Conference on Physics of Advanced Materials, SICPAM 2023, Sharjah, 25 April through 27 April 2023
The Application of Protein Concentrate Obtained from Green Leaf Biomass in Structuring Nanofibers for Delivery of Vitamin B12
No full textNanofibers made of natural proteins have caught the increasing attention of food scientists because of their edibility, renewability, and possibility for various applications. The objective of this study was to prepare nanofibers based on pumpkin leaf protein concentrate (LPC) as a by-product from some crops and gelatin as carriers for vitamin B12 using the electrospinning technique. The starting mixtures were analyzed in terms of viscosity, density, surface tension, and electrical conductivity. Scanning electron micrographs of the obtained nanofibers showed a slight increase in fiber average diameter with the addition of LPC and vitamin B12 (~81 nm to 109 nm). Fourier transform infrared spectroscopy verified the physical blending of gelatin and LPC without phase separation. Thermal analysis showed the fibers had good thermal stability up to 220 °C, highlighting their potential for food applications, regardless of the thermal processing. Additionally, the newly developed fibers have good storage stability, as detected by low water activity values ranging from 0.336 to 0.376. Finally, the release study illustrates the promising sustained release of vitamin B12 from gelatin-LPC nanofibers, mainly governed by the Fickian diffusion mechanism. The obtained results implied the potential of these nanofibers in the development of functional food products with improved nutritional profiles
Monte Carlo simulation of source-specific risks of soil at an abandoned lead-acid battery recycling site
No full textAnthropogenic activities predominantly affect environmental Pb pollution, especially during waste lead-acid battery (LAB) recycling operations. In this study, the presence of Pb and nine other potentially toxic elements (PTEs) in the soil at an abandoned LAB recycling site was investigated. The focus was on spatial and vertical distributions and potential health issues related to PTEs. Average concentrations of Cd, As, Hg, Pb, Al, Zn, Cu, and Sb were elevated at all investigated soil depths, whereas the concentrations of Zn, Cu, and Sb were significant only on the soil surface. Positive matrix factorization, correlation and cluster analyses, as well as self-organizing maps, identified four primary pollution sources: recycling activities (Cd, Hg, Pb, and Sb), mixed anthropogenic sources (Zn and Cu), the soil parent material (As, Cr, and Ni), and surface runoff combined with sand application (Al and pH). While the non-carcinogenic risk results revealed a negligible risk for adults, the hazard index (HI) values for children were greater than one in 26% of the samples. For adults and children, the total carcinogenic risk (TCR) values were acceptable for 98% and 94% of the samples, respectively. Geospatial analysis identified the main hotspot in the battery disposal area. Source-specific non-carcinogenic and carcinogenic risks were most influenced by recycling activities. Monte Carlo simulation (MCS) of total HI for children showed that the risk value exceeded the threshold level (HI > 1) at the 10th percentile, whereas the maximum value of total HI for adults was 0.2. Regarding carcinogenic risk, the TCR values at the 95th percentile of all four sources for adults and children were below the limit value (1 × 10−4), indicating a low probability of cancer development
VEŠTAČKI ZASLAĐIVAČI ACESULFAM I SUKRALOZA: OD SASTOJAKA OTPADNE VODE DO ZAGAĐUJUĆIH MATERIJA PODZEMNIH VODA
No full textAcesulfame and sucralose are non-nutritive sweeteners widely used as sugar substitutes in food, beverages, and pharmaceuticals. As metabolically stable compounds, they are ubiquitous constitu-ents of municipal wastewaters ultimately discharged into the aquatic environment. They belong to a new class of emerging environmental contaminants with potentially harmful effects on aquatic or-ganisms. Acesulfame and sucralose are not removed in wastewater treatment, are resistant to degra-dation in the environment and, therefore, regarded as ideal indicators of sewage contamination. In order to assess the impact of untreated wastewater discharge on the quality of drinking water sources in Belgrade, the concentrations of artificial sweeteners acesulfame and sucralose in sewage wastewater, receiving river water and corresponding groundwater were investigated. The samples were collected from three sewage canals in Belgrade, along with three samples of receiving water from the Danube and the Sava rivers. Considering the potential mobility of the two sweeteners through the aquifer, two groundwater samples were also taken. All water samples were extracted and analyzed by liquid chromatography–tandem mass spectrometry method. Using the measured concen-trations of two sweeteners in river and groundwater, as well as predicted no-effect concentrations (PNEC) for aquatic organisms, ecological risk assessment was performed. The results showed high concentrations of acesulfame and sucralose in all wastewater samples (2786–7488 ng L–1 and 1836–4756 ng L–1, respectively), abundance in all river water samples (51–76 ng L–1 and 68–206 ng L–1) and significant levels in groundwater samples (20 and 73 ng L–1, and 17 and 25 ng L–1). It was also determined that concentrations of the two sweeteners in river and groundwater do not pose ecotoxi-cological risk to aquatic organisms. However, the mere presence of wastewater constituents in groundwater raises concerns about the quality of drinking water sources.Acesulfam i sukraloza su nenutritivni zaslađivači koji se široko koriste kao zamene za šećer u hrani, piću i farmaceutskim proizvodima. Kao metabolički stabilna jedinjenja, oni su sveprisutni sastojci komunalnih otpadnih voda koje se na kraju ispuštaju u vodenu sredinu. Oni pripadaju novoj klasi emergentnih zagađujućih materija u životnoj sredini sa potencijalno štetnim efektima po vodene organizme. Acesulfam i sukraloza se ne uklanjaju u tretmanima otpadnih voda, otporni su na degra-daciju u životnoj sredini, zbog čega se smatraju idealnim indikatorima kontaminacije kanalizacionim vodama. U cilju procene uticaja ispuštanja neprečišćenih otpadnih voda na kvalitet vode za piće u beogradskom vodoizvorištu, ispitivane su koncentracije veštačkih zaslađivača u kanalizacionim, pri-jemnim rečnim i odgovarajućim podzemnim vodama. Uzorci su prikupljeni iz tri kanalizaciona ispu-sta u Beogradu, zajedno sa tri uzorka prijemne rečne vode iz Save i Dunava. S obzirom na potenci-jalnu mobilnost dva zaslađivača kroz akvifer, uzeta su i dva uzorka podzemnih voda. Svi uzorci vode su ekstrahovani i analizirani pomoću metode tečne hromatografije sa tandem masenom spektrome-trijom. Koristeći određene koncentracije dva zaslađivača u rečnim i podzemnim vodama, kao i pred-viđene koncentracije bez efekta (PNEC) za vodene organizme, izvršena je procena ekološkog rizika. Rezultati su pokazali visoke koncentracije acesulfama i sukraloze u svim uzorcima otpadnih voda (2786–7488 ng L–1 i 1836–4756 ng L–1, respektivno), obilnost u svim uzorcima rečne vode (51–76 ng L–1 i 68–206 ng L–1) i značajne nivoe u uzorcima podzemnih voda (20 i 73 ng L–1, i 17 i 25 ng L–1). Takođe je utvrđeno da koncentracije dva zaslađivača u rečnim i podzemnim vodama ne predstavljaju ekotoksikološki rizik za vodene organizme. Međutim, samo prisustvo sastojaka otpadnih voda u pod-zemnim vodama izaziva zabrinutost za kvalitet izvora vode za piće
Synthesis and characterization of hydroxyapatite/clinoptilolite adsorbent for removal of organic pollutants
No full textMunicipal wastewater, as well as agricultural drainage wastewater, is the main source of
organic pollutants such as drugs and pesticides. Efficient, economically profitable and
environmentally acceptable adsorbents for their removal are the subject of intensive research.
In this work, a composite based on surfactant-modified zeolite and hydroxyapatite was
synthesized. It was in detail characterized and examined as an adsorbent of two organic
pollutants: one of the most commonly used antibiotics, ciprofloxacin, and an insecticide
necessary in agricultural production, acetamiprid. The results showed that the obtained
adsorbent removed 5.3 mg ciprofloxacin g-1 and 0.6 mg acetamiprid g-1 from the aqueous
solution