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Ecological and Health Risks Attributed to Rare Earth Elements in Coal Fly Ash
No full textThe occurrence and distribution of yttrium and rare earth elements (REYs), along with major elements and heavy metal(loid)s (HMs) in coal fly ash (CFA) from five coal-fired power plants (CFPPs), were analyzed, and the REY-associated ecological and health risks were assessed. The individual REYs in CFA were abundant in the following order: Ce > La > Nd > Y > Pr > Gd > Sm > Dy > Er > Yb > Eu > Ho > Tb > Tm > Lu. The total REY content ranged from 135 to 362 mg/kg, averaging 302 mg/kg. The mean light-to-heavy REY ratio was 4.1, indicating prevalent light REY enrichment in CFA. Significantly positive correlations between the REYs suggested that they coexist and share similar origins in CFA. REYs were estimated to pose low to moderate ecological risks, with risk index (RI) values ranging from 66 to 245. The hazard index (HI) and target cancer risk (TCR) of REYs from CFA, estimated to be higher for children (HIc = 0.15, TCRc = 8.4 × 10−16) than for adults (HIa = 0.017, TCRa = 3.6 × 10−16), were well below the safety limits (HI = 1, TCR = 1.0 × 10−6). However, the danger to human health posed by HMs in the same CFA samples (HIc = 5.74, TCRc = 2.6 × 10−4, TCRa = 1.1 × 10−4) exceeded the safe thresholds (excl. HIa = 0.63). The mean RI and HI attributed to REYs in CFA were 14% and 2.6%, respectively, of the total risks that include HMs
Influence of Feeder Positions at Preheating Temperature Distribution in Railway Aluminothermic Welding Simulation
No full textOne of the most used techniques for making a continuous rail track is aluminothermic welding. This
technique has its advantages in its simplicity, portability, and it does not require external energy when
repairing or connecting tracks. One of the crucial parts when implementing this process is the mold
design that influences the solidification of the casting. In this study three models were investigated that
have varying positions of the feeders: asymmetrical mold, centered mold, and symmetrical mold. The
focus of the paper is to determine how the position of the feeder effects the preheating of the side rails
that would be welded together. This was carried out using NovaFlow & Solid CV and utilizing its sensor
function. The rail was modeled after the 49E1 standard rail, and the preheating was carried out by
simulating a burner at 1000 oC for 900 seconds. The asymmetrical model had a negligible increase in
temperature, while the symmetrical and centered model were similar. One side rail was more heated
than the other, which can be attributed to the positioning and shape of the burner source area
Gut microbiota - the key mediator between nutrition and health [Predavanje po pozivu štampano u izvodu]
No full textHumans live in symbiosis with a complex microbial ecosystem that inhabits the entire digestive tract. The densest microbial community is present in the colon, which can be perceived as a specialized bioreactor. These microbes, collectively termed gut microbiota, utilize indigested food components and host-derived substrates to produce metabolites that complement human physiology. It is well established that nutrition is essential for human health, but in order to fully comprehend the health impact of food, the interaction between (indigested) food components and microbiota should also be taken into account. Microbiota can produce beneficial and hazardous chemicals depending on the available substrates. The availability of different substrates for fermentation largely depends on nutritional intake. Various plant-derived compounds, such as indigestible carbohydrates and polyphenols are transformed by gut microbiota into beneficial bioactive compounds. Therefore, several carbohydrates and polyphenols are considered to be prebiotics. In addition, food can contain probiotic microorganisms which can improve human health through direct interaction with humans or indirectly by modifying gut microbiota. On the contrary, some gut microbiota metabolites generated in the fermentation of proteins impair metabolic and cardiovascular health. Furthermore, some food additives also interact with gut microbiota. Conserving agents, but also artificial sweeteners and emulsifiers can impact the composition and function of microbiota, mostly in a negative manner. Epidemiological studies have shown that consumption of some presumably safe processed foods can compromise health. This surprising finding could be, at least to some extent, explained by the negative interaction between food additives and microbiota. This interaction is recognized as a missing link in the risk assessment of food additives by regulatory agencies. Given the importance of gut microbiota for systemic health, it is clear that food should nourish both humans and their microbiota to preserve and improve health.Plenarno predavanje po poziv
Doxorubicin application in a 3D osteosarcoma cell culture model
No full textThe most common primary malignant bone tumor that predominantly affects children andadolescents is osteosarcoma. Comprehensive osteosarcoma treatment involves neoadjuvantmulti-agent chemotherapy followed by surgical resection and adjuvant multi-agentchemotherapy. Unfortunately, this complex treatment is insufficiently effective, as the tumorrecurs in over 40 % of cases. The development of new drugs for osteosarcoma is a complexand slow process due to various limitations of preclinical drug evaluation methods. Onepotential solution is to develop three-dimensional (3D) systems that replicate key in vivophysiological conditions, using biomaterials as extracellular matrices and biomimeticbioreactors to ensure efficient mass transport and adequate biophysical signals. This studyaimed to evaluate a previously developed 3D culture model for osteosarcoma cells based onmacroporous composite scaffolds (2 wt.% alginate and 2 wt.% hydroxyapatite) in conjunctionwith a perfusion bioreactor for anticancer drug screening. Murine osteosarcoma cells (K7M2-wt) were seeded onto the scaffolds (15x106 cells cm-3 of scaffold volume) and cultivated understatic conditions for one day. Two experimental studies were performed using the anticancerdrug doxorubicin. In the first study, following the static cultivation, doxorubicin (1 μg cm-3 ofculture medium) was applied for 1 day in a “3D Perfuse” bioreactor (Innovation Center ofFaculty of Technology and Metallurgy, Belgrade, Serbia) at a flow rate of 0.27 cm³ min-1,corresponding to the superficial velocity of 40 μm s-1. In the second study, after the 1-day staticcultivation, cell seeded scaffolds were cultivated for 7 days under the same continuous flowconditions, which allowed spontaneous formation of spheroid-like structures. Next,doxorubicin was applied in the same manner as in the first study. The cultivated scaffolds inboth studies were then assessed regarding the cell metabolic activity using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. The obtained results indicatedlower sensitivity of cells cultured in the 3D environment to the tested drug as compared tothose in 2D in agreement with chemotherapy resistance observed in patients
Triboelectricity and Applications in Heritology
No full textТрибоелектрицитет, појава генерисања наелектрисања путем трења, привукао је значајну пажњу последњих година због минијатуризације трибоелектричних уређаја и потенцијалних примена у различитим областима, првенствено као метод за energy harvesting (сакупљање енергије) и sensing (детекцију, мерење). Овај прилог пружа преглед и анализу области трибоелектрицитета (обухватајући историју, основне принципе и модерне трендове истраживања) и савремених примена трибоелектричних генератора, сензора и других уређаја, са нагласком на област очувања културног наслеђа (херитологију). Приказани су и изазови и претпостављени будући правци у овој области која се брзо развија.Triboelectricity, the phenomenon of electric charge generation through friction, has attracted significant attention in recent years due to the miniaturisation of triboelectric devices and their potential applications in various fields, primarily as a method for energy harvesting and sensing. This contribution provides an overview and analysis of the field of triboelectricity (including basic principles, history and modern research trends) and modern applications of triboelectric generators, sensors and other devices. Particular emphasis is placed on applications in cultural heritage preservation (heritology). Challenges and future directions in this rapidly developing field are also discussed.Зборник изабраних радова и апстраката под називом Научна слика о
еколошким аспектима у уметности и заштити културног наслеђа, представља
радове и дискусије са Округлог стола одржаног 31. октобра 2018. године, у
Педагошком друштву Србије
Source-specific probabilistic health risk assessment of potentially toxic elements in groundwater of a copper mining and smelter area
No full textThe occurrence of potentially toxic elements (PTEs), including twelve heavy metal(loid)s (Cd, Cr, Cu, Ni, Pb, Zn, Hg, As, Co, V, Fe, Mn), fluoride (F−), and nitrate (NO3−) was evaluated in groundwater in the copper mining and smelter area of Bor city (south Carpathian, eastern Serbia). Groundwater samples were analyzed to determine the extent of pollution, identify natural and anthropogenic input of PTEs, and estimate potential human health risks due to exposure to these substances. The results revealed that the groundwater in the study area was highly contaminated with PTEs, particularly Cu and Zn. Multivariate analysis supported the natural and anthropogenic origin of PTEs, with Fe, Mn, and F− classified as naturally occurring, NO3− resulting from agricultural activities, while other PTEs were linked to smelter/mining processes. Geospatial mapping discovered several hotspots with potential high non-cancer and cancer risks to humans through ingestion pathway. From the studied PTEs, As is the most health risk contributing toxic element. The source-specific probabilistic risk assessment indicated the most significant contribution to the hazard index and total cancer risk from accidental leakage of metallurgical wastewater and wastewater from open mine pits. Monte Carlo analysis identified the human body weight and the ingestion rate as the most sensitive risk parameters. The study underscores the need for stringent environmental management measures, emphasizing the critical role of source-specific risk assessments in mitigating potential hazards associated with metallurgical wastewater and open mine pits
Influence of Novel SrTiO3/MnO2 Hybrid Nanoparticles on Poly(methyl methacrylate) Thermal and Mechanical Behavior
No full textWhile dental poly methyl methacrylate(PMMA) possesses distinctive qualities such as ease of fabrication, cost-effectiveness, and favorable physical and mechanical properties, these attributes alone are inadequate to impart the necessary impact strength and hardness. Consequently, pure PMMA is less suitable for dental applications. This research focused on the incorporation of Strontium titanate (SrTiO3-STO) and hybrid filler STO/Manganese oxide (MnO2) to improve impact resistance and hardness. The potential of STO in reinforcing PMMA is poorly investigated, while hybrid filler STO/MnO2 has not been presented yet. Differential scanning calorimetry is conducted in order to investigate the agglomeration influence on the PMMA glass transition temperature (Tg), as well as the leaching of residual monomer and volatile additives that could pose a threat to human health. It has been determined that agglomeration with 1 wt% loading had no influence on Tg, while the first scan revealed differences in evaporation of small molecules, in favor of composite PMMA-STO/MnO2, which showed the trapping potential of volatiles. Investigations of mechanical properties have revealed the significant influence of hybrid STO/MnO2 filler on microhardness and total absorbed impact energy, which were increased by 89.9% and 145.4%, respectively. Results presented in this study revealed the reinforcing potential of hybrid nanoparticles that could find application in other polymers as well
The Effect of the Nanostructured Surface Modification on the Morphology and Biocompatibility of Ultrafine-Grained Titanium Alloy for Medical Application
No full textPrimary implant stability after implantation is in relation with its good mechanical contact with the touching tissue. Adequate integration of the implant with the bone tissue is necessary to provide safety and efficiency of the implant over its life. Generally, two surface properties are the most important facts for tissue response to the implant: the surface topography and chemical composition. Compared to a smooth implant surface, a controlled rough surface provides more surface area for integration with the surrounding tissues and allows successful implant ingrowth into the tissues. It was found that the nanostructured modification of the titanium surface on the level of nano-sized pores influences the adhesion, spreading and growing of osteoblastic cells. There are many methods for nanostructure modification of biomedical alloy surfaces, but one of the common techniques is electrochemical anodization (anodic oxidation). Electrochemical anodization is a method that leads to the creation of a nanotubular oxide film on the material surface. The advantage of anodic oxidation is the possibility of controlling the nanostructured morphology of the surface and dimensions of nanotubes, such as diameter, length, wall thickness and shape of nanotubes through variation of the solution, pH value, potential or duration of anodic oxidation.
Surface modification of Ti-13Nb-13Zr alloy in a coarse-grained (as received) and ultrafine-grained state induced by high pressure torsion was conducted using an electrochemical anodization process in a 1 M H3PO4 + NaF electrolyte, for 30, 60, 90 and 120 minutes. Scanning electron microscopy (SEM) was used to analyze the morphology, while atomic force microscopy (AFM) was used to characterize the topography of the modified surface. The results showed that a homogenous nanotubular oxide film consisting of nanotubes could be obtained using the electrochemical anodization treatment, while the roughness of the nanostructured surface increased compared to the bare surface. The aim of the studies given in this chapter is to examine the morphology of the nanostructured surface and estimate in vitro biocompatibility of the above-mentioned titanium alloy after the creation of the nanotubular oxide film. In vitro examinations were performed on mouse fibroblast (L929) and human fibroblast (MRC-5) cell lines. The results showed that the nanotubular oxide film obtained on the coarse-grained Ti-13Nb-13Zr alloy (CG TNZ) and the ultrafine-grained Ti-13Nb-13Zr alloy (UFG TNZ) increased the fractions of surviving cells compared to their counterpart alloy, while the cells had better spreading and adhesion on the nanostructured and bare surfaces of the UFG titanium alloy
Human health risk assessment of artificial sweeteners detected in well water
No full textArtificial sweeteners are emerging contaminants that are widely detected in natural waters as a result of their widespread use in the food industry and continual release into aquatic ecosystems via municipal wastewater. Recent research has shown that frequent consumption of these compounds can cause negative effects on human health. In this paper, human health risk assessment for possible chronic exposure to sweeteners detected in groundwater wells in Belgrade and the surrounding area was performed. The results showed the widespread presence of acesulfame and sucralose in well water, at concentrations up to 80 ng L–1 and 25 ng L–1, respectively. According to US EPA risk characterization guidance and calculated hazard quotients, the detected levels of sweeteners do not pose a threat to human health. However, the cumulative effect of all ingested sweeteners and other food additives should be considered, as well as their potential carcinogenicity, in future long-term health risk assessments