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Luminescent Metal–Organic Frameworks for Electrochemiluminescent Detection of Water Pollutants
Get PDFThe modern lifestyle has increased our utilization of pollutants such as heavy metals,
aromatic compounds, and contaminants that are of rising concern, involving pharmaceutical and personal products and other materials that may have an important environmental impact. In particular, the ultimate results of the intense use of highly stable materials, such as heavy metals and chemical restudies, are that they turn into waste materials, which, when discharged, accumulate in environmental water bodies. In this context, the present review presents the application of metal–organic frameworks (MOFs) in electrochemiluminescent (ECL) sensing for water pollutant detection. MOF composites applied as innovative luminophore or luminophore carriers, materials for electrode modification, and the enhancement of co-reaction in ECL sensors have enabled the sensitive monitoring of some of the most common contaminants of emerging concern such as heavy metals, volatile organic compounds, pharmaceuticals, industrial chemicals, and cyanotoxins. Moreover, we provide future trends and prospects associated with ECL MOF composites for environmental sensing
TiO2 nanotube arrays decorated with Ir nanoparticles for enhanced hydrogen evolution electrocatalysis
Get PDFDesigning cost-effective hydrogen evolution reaction (HER) electrocatalysts containing highly active, but expensive platinum group metals (PGMs) is key to the commercialization of polymer electrolyte membrane water electrolysis systems for green hydrogen production. Our recent investigations have shown that efficient and durable HER composite cathodes can be prepared by spontaneous deposition of PGM nanoparticles on self-aligned titania nanotube (TNT) arrays formed by anodization [1]. In this synthesis route, anatase TNTs are first cathodically protonated (H-TNT), and then used as the reducing agent for PGM ions at room temperature. Herein, we employ the galvanic displacement strategy to decorate H-TNT arrays with ultrafine Ir nanoparticles [2]. We demonstrate that transforming the top surface morphology of supporting TNT arrays from ordered open-top tubes to bundled nanowires (“nanograss”) is beneficial for exposing more Ir active centers during the HER operation. Consequently, applying very low concentrations of Ir(III) ions in the galvanic displacement step is sufficient to produce exceptionally active nanograss-modified Ir@TNT composites. An optimum Ir@TNT, possessing a low Ir loading of 5.7 μgIr cm–2, requires an overpotential of only –63 mV to reach a current density of –100 mA cm–2 and shows a stable long-term performance in a 1 M HClO4 solution. Computational simulations suggest that the hydrogen-rich TiO2 support not only strongly interacts with anchored Ir particles and weakens their H binding strength to a moderate level, but also actively provides hydrogen for rejuvenation of the Ir active sites at the Ir|H-TiO2 interface, thereby significantly enhancing HER catalysis.
[1] U.Č. Lačnjevac, R. Vasilić, T. Tokarski, G. Cios, P. Żabiński, N. Elezović and N. V. Krstajić, Nano Energy 47 (2018) 527.
[2] U. Lačnjevac, R. Vasilić, A. Dobrota, S. Đurđić, O. Tomanec, R. Zbořil, S. Mohajernia, N.T. Nguyen, N. Skorodumova, D. Manojlović, N. Elezović, I. Pašti, P. Schmuki, Journal of Materials Chemistry A 8 (2020) 22773
Impact of electrochemically generated iron on the performance of an anaerobic wastewater treatment process
Get PDFAnaerobic treatment of domestic wastewater has the advantages of lower biomass yield, lower energy demand and higher energy recover over the conventional aerobic treatment process. However, the anaerobic process has the inherent issues of excessive phosphate and sulfide in effluent and superfluous H2S and CO2 in biogas. An electrochemical method allowing for in-situ generation of Fe2+ in the anode and hydroxide ion (OH−) and H2 in the cathode was proposed to overcome the challenges simultaneously. The effect of electrochemically generated iron (e‑iron) on the performance of anaerobic wastewater treatment process was explored with four different dosages in this work. The results showed that compared to control, the experimental system displayed an increase of 13.4–28.4 % in COD removal efficiency, 12.0–21.3 % in CH4 production rate, 79.8–98.5 % in dissolved sulfide reduction, 26.0–96.0 % in phosphate removal efficiency, depending on the e‑iron dosage between 40 and 200 mg Fe/L. Dosing of the e‑iron significantly upgraded the quality of produced biogas, showing a much lower CO2 and H2S contents in biogas in experimental reactor than that in control reactor. The results thus demonstrated that e‑iron can significantly improve the performance of anaerobic wastewater treatment process, bringing multiple benefits with the increase of its dosage regarding effluent and biogas quality
The common nase (Chondrostoma nasus) as an indicator of aquatic pollution and human health risk assessment associated with its consumption
No full textIndividuals of common nase were sampled from three waterbodies (Kačer river, Zaovine, and Medjuvršje reservoirs) with different characteristics, types, and levels of anthropogenic pressure. The aims of this study were to determine the concentra-tions of 26 elements in gills, liver, and muscle using inductively coupled plasma optical emission spectrometry (ICP-OES); determine the concentrations of 17 organochlorine pesticides (OCPs) in muscle tissue using gas chromatography with mass spectrometric detection (GC–MS); compare these findings with fish condition (CF); and conduct human health risk and benefit assessments due to consumption of fish meat using target hazard quotient, target carcinogenic risk factor, Se:Hg molar ratio, Na:K and Ca:Mg ratios, and contribution of elements to human diet. Results indicated that in addition to the fact that the type of ecosystem (lentic vs. lotic) plays an important role in the fate and kinetics of pollutants, the degree of anthropogenic pressure is one of the most important factors of environmental pollution — Zaovine and Medjuvršje reservoirs (both lentic ecosystems) had the lowest and the highest levels of pollution, respectively. CF did not reflect the differences in accumula-tion of all analyzed elements in nase tissues. None of the 17 analyzed OCPs were detected due to the absence of recent use. Fish muscle was the least affected by metal pollution at all studied localities and could be safely used for consumption. We recorded several benefits for human health when using the nase meat in human diet
TAXONOMY AND PHYTOGEOGRAPHY ANALYSIS OF MEDICINAL PLANTS AT THE AREA OF NATURE MONUMENT “ŠUMA KOŠUTNJAK”
Get PDFThe study was carried out during two consecutive growing seasons (2020-2021) with the aim
to record medicinal plants at the area of protected nature monument “Šuma Košutnjak”.
Based on field research, together with numerous references, there was established presence of
total of 147 medicinal plants at the whole researched locality. After the plants were
determined, taxonomy and phytogeography analyses of collected material were performed. As
for taxonomy, the most distributed families are Rosaceae (10.88 %) and Lamiaceae (9.52 %),
while Fabaceae (5.44%) and Asteraceae (5.44%) are a bit less present. In the phytogeography
analysis participation of different life forms and floral elements was determined. Among life
forms the most common are hemicryptophytes (40.14%), then phanerophytes (24.49%) and
therophytes (11.56%). The most dominant floral elements are Eurasian (20.41%),
submideuropean (17.69%), mideuropean (12.24%) and submediterranean (11.56%). It should
be noted that some species, according to destructive human effect, are very endangered due to
low rate of their natural regeneration. Therefore it is needed to conduct protective measures in
order to conserve gene pool of these species. If we want to obtain reliable information about
the number and presence of medicinal plants at this area, it is necessary to perform detailed
monitoring which would include several consecutive growing seasons
Novel Strategies for the Control of Gastrointestinal Nematodes in Sheep
Get PDFГастроинтестиналне нематоде представљају веома значајне паразите домаћих животиња, нарочито код малих преживара. Код оваца обољења најчешће имају субклиничан ток са смањењем телесне масе и производње, а понекад може доћи и до видљивих клиничких симптома попут анорексије, анемије, јаке дијареје и губитка протеина што све заједно може довести и до угинућа. Комерцијални лекови попут бензимидазола и макроцикличних лактона су се деценијама са успехом користили за контролу ових паразита. Међутим, нерационална примена ових лекова је довела до развоја антихелминтичке резистенције, опадања њихове ефикасности и последичних економских губитака који угрожавају одрживост гајења оваца. Поред тога, примена комерцијалних препарата је повезана и са резидуама које остављају у животињским производима и животној средини, а присутан је и раст цене ових препарата. Због тога се активно трага за новијим стратегијама за контролу ових паразита, а у циљу успостављања интегрисаног приступа који подразумева примену више различитих стратегија. Са једне стране, ту спадају стратегије рационалне примене комерцијалних препарата заснованих на рефугији (циљани третмани, циљани селективни третмани), као и комбинација и ротација антихелминтика из различитих хемијских група. Са друге стране, интегрисан приступ подразумева и употребу различитих алтернативних стратегија попут генетске селекције животиња природно отпорних на нематоде, рационалног управљања пашњацима, избалансиране исхране уз допунска хранива, биолошке контроле (употреба гљива, бактерија и слично), развоја вакцина као и употребе ботаничких препарата (биљака и њихових производа попут екстракта и етарских уља). Различита истраживања су доказала ефикасност наведених стратегија у контроли гастроинтестиналних нематода оваца, при чему се најбољи резултати постижу њиховом комбинованом применом. На овај начин је могуће успорити развој и ширење антихелминтичке резистенције, као и постићи одрживу контрола ових паразита и смањење економских губитака.Gastrointestinal nematodes are very important parasites of domestic animals, especially in small ruminants. In sheep, diseases usually have a subclinical form with a decrease in body weight and production, and sometimes there can be visible clinical symptoms such as anorexia, anemia, severe diarrhea and protein loss, all of which together can lead to death. Commercial drugs such as benzimidazole and macrocyclic lactones have been successfully used for decades to control these parasites. However, the irrational application of these drugs has led to the development of anthelmintic resistance, a decrease in their effectiveness and consequent economic losses that threaten the sustainability of sheep breeding. In addition, the use of commercial preparations is also associated with the residues in animal products and the environment, and there is also an increase in the price of these preparations. For this reason, novel strategies for controlling of these parasites are actively seeking, with the goal of establishing an integrated approach that involves the application of several different strategies. On the one hand, these include strategies for the rational application of commercial preparations based on refugia (targeted treatments, targeted selective treatments), as well as the combination and rotation of anthelmintics from different chemical groups. On the other hand, an integrated approach implies the use of different alternative strategies such as genetic selection of animals naturally resistant to nematodes, rational management of pastures, balanced nutrition with supplementary nutrients, biological control (use of fungi, bacteria, etc.), development of vaccines as well as the use of botanical preparations (plants and their products such as extracts and essential oils). Various studies have proven the effectiveness of the mentioned strategies in the control of gastrointestinal nematodes of sheep, whereby the best results are achieved by their combined application. Thus, it is possible to slow down the development and spread of anthelmintic resistance, as well as achieve sustainable control of these parasites and reduce economic losses
Magnesium substitution with nickel and its influence on the sensing properties of MgFe2O4
Get PDFMixed spinel ferrites MgxNi1-xFe2O4 were synthesized via sol-gel combustion synthesis with citric acid as fuel, followed by calcination at 700 °C for 3 hours. Obtained powders were characterized via X-ray diffraction analysis (XRD), X-ray photoelectron (XPS), FTIR and Raman spectroscopy and FESEM microscopy. Elemental composition was examined via energy dispersive spectroscopy (EDS). Humidity sensing properties were tested by measuring AC impedance in a climactic chamber at 25 °C and in the relative humidity range of 40–90%. Temperature sensing properties were tested by measuring DC resistance at 40% RH in the temperature range 40–90 °C. Synthesized powders were proven to be pure spinel Fd 3m phase with spherical, slightly agglomerated particles. Substitution of Mg with Ni results in structural changes such as a change in inversion parameter and particle agglomeration, which influences sensing properties of the material. Results show that the sensing properties of magnesium ferrite can be improved by incorporating 10% of nickel in the spinel lattice structure. Mg0.9Ni0.1Fe2O4 exhibited higher temperature sensitivity and higher sensitivity towards humidity compared to MgFe2O4, while further substitution of Mg with Ni resulted in the decline of sensing properties, increase in particle size and agglomeration degree
The influence of dopants on anatase-rutile phase transition
Get PDFTitanium dioxide exists in three different crystalline forms: anatase, rutile, and brookite.
It is well known that on heating, anatase and brookite can be easily transformed to rutile
which is considered as the most stable phase [1]. The aim of this study was to investigate
the influence of different dopants on anatase-rutile phase transition. Doped TiO2 samples
(TiO2-M, M = V, Mn, and Cu) containing 5 at% of the dopant were prepared by mixing
anatase and appropriate oxide (V2O5, MnO2, and CuO) in agate mortar for 30 min. In
order to determine the heat treatment conditions, TG/DTA analysis of the samples was
performed. Finally, mixed powders as well as the pure anatase phase (TiO2) were heat
treated at 700 °C for 3 h. XRD analysis was performed to estimate the phase composition,
unit cell parameters, and crystallite sizes. Rutile was formed in all samples: 2.8 wt% in
TiO2, 25.5 wt% in TiO2-Mn, 75.8 wt% in TiO2-V, and 95.2 wt% in TiO2-Cu. In TiO2-
Mn, TiO2-V, and TiO2, anatase was present beside rutile, while in the case of TiO2-Cu
4.8 wt% of the unreacted CuO was found. Obtained results revealed that all the dopants
accelerated anatase-rutile phase transition in the following order: Cu2+ > V5+ > Mn4+. It
is well known that defects are the driving force for the anatase-rutile phase transition and
since Ti4+ and Mn4+ are isovalent, no new defects were formed by incorporating Mn4+
ions into TiO2 lattice. This resulted in the least amount of rutile in TiO2-Mn comparing
to TiO2-V and TiO2-Cu where new defects were probably formed. As no initial oxides
were found in TiO2-Mn and TiO2-V, it can be concluded that Mn4+ and V5+ ions were
incorporated into the anatase lattice. On the other hand, in the case of TiO2-Cu, even 4.8
wt% of initial CuO was found. The detected residue of CuO can be explained by the fact
that the ionic radius of Cu2+ for an octahedral environment (0.870 Å) is much larger than
that of Ti4+ (0.745 Å), unlike those for Mn4+ (0.670 Å) and V5+ (0.680 Å). Although
almost all introduced quantity of CuO, i.e. 96 %, was found in TiO2-Cu, a small amount
was surely necessary to cause the anatase-rutile phase transition. According to calculated
crystallite sizes which were in the range of 55 – 90 nm, nanocrystalline samples were
prepared.
1. P. I. Gouma, M. J. Mills J. Am. Ceram. Soc. 2001, 84 (3) 619–622
Biološka aktivnost alkiltio i ariltio derivata 2-terc-butil-1,4-benzohinona
Get PDFU ovoj disertaciji su sintetisana jedinjenja sa istom farmakoforom kao i biološki aktivna jedinjenja poreklom iz prirodnih proizvoda, alkiltio i ariltio derivati 2-terc-butil-1,4-benzohinona – TBQ i ispitana je njihova biološka aktivnost.
Jedinjenja pokazuju dobar antioksidativni potencijal i dovode do produkcije slobodnih radikala, pri čemu se najviše ističe 2-terc-butil-5,6-(etileneditio)-1,4-benzohinon (derivat 4), koji zajedno sa 2-terc-butil-5-(propiltio)-1,4-benzohinonom (derivat 3) pokazuje najjači antineurodegenerativni potencijal. Mikrodilucionim testom uočena je jača antimikrobna aktivnost prema gram-pozitivnim bakterijama, naročito prema Staphylococcus aureus i Bacillus subtilis. Svi derivati, osim 2-terc-butil-6-(feniltio)-1,4-benzohinona (derivat 6), pokazuju manju toksičnost od TBQ prema Artemia salina. MTT i MTS testom je uočeno da jedinjenja, generalno, pokazuju umeren citotoksični efekat prema humanim ćelijskim linijama dok je derivat 4 pokazao najjači efekat. Jedinjenja su pokazala jači efekat na inhibiciju migracije tumorske A549 ćelijske linije u odnosu na zdravu MRC-5 ćelijsku liniju. Genotoksična aktivnost jedinjenja primenom SOS/umuC testa na prokariotskom model sistemu nije uočena, niti je primećena interakcija sa plazmidnom DNK. Komet testom, na eukariotskim model sistemima, pokazano je da izabrane hemijske modifikacije pojačavaju genotoksični potencijal dok je derivat 4 pokazao najjači efekat, uključujući indukciju dvolančanih oštećenja DNK γH2AX testom i značajno veće zaustavljanje ćelijskog ciklusa HepG2 ćelija u G2/M fazi u odnosu na TBQ.
Analizom svih dobijenih rezultata, derivat 4 je pokazao najjaču biološku aktivnost.Nisam sigurna koji tip licence se stavlja za doktorsku disertaciju kao i to da li ide otvoreni ili zatvoreni pristup (pretpostavljam da je otvoreni).
Takođe valjda sam ja nosilac autorskih prava pa sam stavila svoje ime. Možda sam i tu poglešila
Artificial Intelligence and Education in Serbia
Get PDFArtificial intelligence (AI) has rapidly emerged as a transformative
technology with potential applications in various fields, including education. With the increasing number of tools powered by AI technology and
especially with the launch of the artificial intelligence-based language
model, the ChatGPT, the issue of using AI has come to the center of
interest for researchers in different fields, including social sciences and
humanities, such as sociology, philosophy, pedagogy and religion studies,
but also for students and teachers. We consider the potential of AI in education, including its ability to individualize learning, improve assessment
and feedback, and enhance educational research, as well as the concerns
about depersonalization of teaching, privacy, equity, quality of human
interactions, and so on. Relying on the experience of education in Serbia
and the UNESCO Education 2030 Agenda, we analyze the practice of
using AI by teachers and students in Serbia