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Using Douglas Fir and European Larch Needles for the Assessment of Their Retention Capacity for Atmospheric Heavy Metals
No full textAmong numerous global problems, one of the most significant is air pollution. In
this paper, unwashed (U) and water-washed (W) needles of two conifers—European larch
and Douglas fir—were used to assess their capacity for the retention and accumulation
of heavy metals. The needle samples were used to represent the atmospheric deposition
of heavy metals located on the surface of the needles. The sampled European larch and
Douglas fir plantations were situated at three locations in Serbia: a least polluted (Kuˇcevo),
a moderately polluted (Avala), and a very polluted (Lazarevac) site. The content of five
heavy metals (Ni, Cu, Co, Cd, Pb) was investigated in the study. The concentration of
cadmium (Cd) was higher in the European larch needles compared to Douglas fir, while
the differences in the content of the other heavy metals between the species studied were
insignificant. For both species, the following trend applied with respect to the heavy metal
content in their needles: Ni > Cu > Co > Pb > Cd. Based on the results obtained, we
deduced that the concentrations of all investigated heavy metals at all three locations for
both species were within the allowed limits, except for nickel (Ni) content, which was
over the predicted limit values for both species in the highly polluted area (Lazarevac). A
PCA (principal component analysis) undertaken suggests that European larch has a greater
ability to accumulate Co than Douglas fir on sites contaminated with heavy metals. The
predictive foliar metal accumulation index (MAI) value was slightly higher in Douglas fir
(4.14) than in European larch (3.76); therefore, the results suggest that this species would be
a good planting choice, particularly in urban and industrial environments
An Estimate of Penetration Depth of Rigid Rods Through Materials Susceptible to Microcracking: Part 2 – Validation and Parameter Sensitivity
No full textA simple, approximate model aimed at estimating the penetration depth of slender rigid projectiles into massive targets made of quasibrittle solids is proposed in the companion article [1]. The key ingredient for that novel analytical approach—namely, the functional dependence of the radial traction at the cavity surface on the radial velocity of the cavity expansion—is provided by postprocessing of results of particle dynamics simulations. In this article, this model is validated using experimental results on the depth of penetration of long (virtually rigid) projectiles into Salem limestone targets. Salem limestone is a typical example of quasibrittle materials with random, discontinuous and heterogeneous micro/meso structure, inherently predisposed to microcracking, which is attributed to their inferior tensile strength. Such materials are known for their pronounced scatter of experimental data. This inherent stochasticity is explored in this paper through a comparative analysis of key model input parameters; primarily, the indirect (uniaxial) tensile strength and the coefficient of friction
Influence of Er3+ concentration and sintering temperature on structural and spectroscopic properties of BaTiO3:Er3+
No full textThis study analyzes the effects of doping BaTiO3 with Er3+ within its perovskite ABO3 structure, specifically investigating how substituting Er3+ at the Ba (A-site) and Ti (B-site) locations influences the material at different doping levels. Scanning electron microscopy (SEM)/energy-dispersive X-ray spectrometry (EDS) analysis shows that all of the samples have polygonal grains. In BTO doped with 0.01 wt% and 0.1 wt% Er3+ grain size was up to 45 μm. With the higher amount, the growth is slowing down and grains are 2–10 μm. Raman spectra show part of common BaTiO3 modes only for the lowest content of Er3+. At higher Er3+ content, the usual modes are completely covered by strong luminescence originating from Er3+ deexcitation from energy level 2H11/2. The intensity of the photoluminescence (PL) bands shows the influence of not only the Er3+ concentration, but also the crystallinity of the sample, especially their surface. The FIR reflectivity shows а slight wavelength shift for higher sintering temperature, but all spectra show lower intensity comparing with pure BaTiO3. FTIR transmission spectra show slight shifts of characteristic Ti–O bending mode at about 480 cm−1 confirming the incorporation of Er3+ in BaTiO3 at 1320 °C and 1350 °C. Near IR excitation (1530 nm) provoked upconversion photoluminescent (UCPL) spectra of BaTiO3:Er3+ with PL lines at higher energies. The upconversion mechanism for each line was determined and the fluorescence lifetime was estimated. It is observed that the obtained intensities of UCPL increase gradually at both sintering temperatures with increase of Er3+ content
Modified Z-scheme Heterojunction of Polypyrrole/TiO2: A Recyclable Photocatalyst for Azo Dyes Removal
No full textIt is well known that titanium dioxide is widely applied in photocatalysis regarding
chemical and thermal stability, availability on the market, durability, and non-toxicity. Anatase,
rutile, and brookite are three different crystalline modifications of TiO2, whereby anatase is the
most efficient for photocatalytic application. However, TiO2 has some drawbacks: low
adsorption power towards organic pollutants, high recombination rate during photocatalysis, and
it can be excited only by UV light. Coupling TiO2 with a conductive polymer, i.e. creating a
conductive polymer/TiO2 heterojunction, is a promising way to overcome these obstacles.
Polypyrrole (PPy) is easy to prepare, stable, and possesses unique structure with delocalized
π-electrons which contributes to the high mobility of charge carriers. In this work, PPy/TiO2
composites with different amounts of PPy (0, 0.5, 1, 1.5, 3, and 5 wt.%) were obtained by
physical mixing of hydrothermally synthesized TiO2 and PPy prepared by the chemical oxidative
polymerization. Prepared composites were characterized in detail by XRPD, FTIR, FESEM,
EDS, UV/Vis, and BET methods. Photocatalytic activity of the samples was examined towards
toxic textile azo dye Reactive Orange 16 (RO16) under simulated solar light, while
photocatalytic efficiency was estimated by UV/Vis and TOC methods. XRPD results showed
that TiO2 was obtained with preserved nanoanatase structure in all the samples with crystallites
of 26 nm. FTIR and EDS methods additionally confirmed presence of both, TiO2 and PPy in all
the nanocomposites. UV/Vis results revealed that band gap energy decreased with an increase in
PPy content from 3.11(3) eV for single TiO2 and 2.94(3) eV for 5%PPy/TiO2. Prepared
nanocomposites demonstrated excellent photocatalytic activity, while 1%PPy/TiO2 was the most
efficient by completely degrading RO16 dye after 120 min under simulated solar light. Such
high efficiency was reached since all relevant factors were well balanced: sufficiently small TiO2
crystallites, well distribution of PPy particles in a composite, narrowed band gap (3.08 eV), and
significant improvement in specific surface area (61.71 m2 g
−1) compared to the single TiO2
(36.46 m2 g
−1). Therefore, it can be concluded that the optimal content of PPy in the
nanocomposite is 1 wt.%. Moreover, by performing several cycles of photocatalysis the
reusability of the 1%PPy/TiO2 was confirmed since no decrease in efficiency was observed.
Finally, the photocatalytic degradation mechanism of RO16 in the presence of 1%PPy/TiO2 was
examined based on scavenger tests and thermodynamic calculations. Two important facts were
found: (i) the mechanism can be well described by a slightly modified Z-scheme heterojunction,
and (ii) PPy plays an active role in the process of photocatalysis by opening a new reaction
pathway
Durability of alternative cementitious binders
No full textOver the past few decades, various alternative binders have been developed and explored, as result of growing global pressure to reduce greenhouse gas emissions and energy use related to Portland cement production. However, wider commercial adoption of the new binders is often hindered by the lack of data on their long-term properties and durability. During their lifetime, binder materials come in contact with various aggressive solutions or conditions with deteriorating effects. Durability assessment of alternative binders is complicated by wide variety of their compositions and lack of standardized procedures, as test parameters used to determine durability of Portland cement are not always suitable for the newly developed binders. In this work, an overview of the testing procedures used and the results obtained when alternative binders, such as alkali activated materials and high volume fly ash binders, were subjected to various aggressive solutions, will be given
Evaluating biocontrol potential of Bacillus velezensis against Xanthomonas campestris pv. campestris on cabbage cv. Futoški under greenhouse conditions
No full textBacillus velezensis is recognized as a species with remarkable biocontrol potential against a wide range of plant pathogens, including the bacterium Xanthomonas campestris pv. campestris (Xcc), the causal agent of black rot of Brassicaceae crops.
This study aimed to establish the most suitable technique for application of four B. velezensis strains (BFC55, BFC88, BFC102, and BFC114) against Xcc on cabbage cv. Futoški.
The efficacy of three application techniques (seed-soaking, preventive and curative foliar spraying) was evaluated on cabbage plants under the controlled greenhouse conditions in two independent experiments. Simultaneously, the efficacy of whole cultures and cell-free supernatants of B. velezensis strains were tested. The disease intensity was scored 14 days after inoculation using the Horsfall–Barratt scale. Upon the end of the experiment, fresh and dry biomass, as well as chlorophyll and epidermal flavonoid content and nitrogen balance index were measured for all treatments.
Among the compared treatments, preventive application showed the greatest disease suppression (89.71–93.09%) ability, while the curative exhibited the lowest efficacy (55.00–75.68%). The highest efficacy was observed after preventive application of strain BFC88 in the form of whole culture (93.09%). Preventive treatment showed increased epidermal flavonoid accumulation compared to all other application treatments, along with a decrease in fresh/dry biomass ratio.
Preventive treatment has been highlighted as the most effective method for controlling black rot in cabbage cv. Futoški in comparison to other treatments. The demonstrated efficacy of tested strains in greenhouse conditions suggests their potential for successful application in the field.У књизи апстраката није наведен ISBN број
PRIRUČNIK ZA PREPOZNAVANJE RIBA SRBIJE
No full textPriručnik koji ste otvorili namenjen je svima koji nemaju posebnih predzananja o slatkovodnim
ribama, sa ciljem da im omogući da što lakše prepoznaju vrste riba koje žive u vodama Srbije. Priručnik nije strogo naučni dihotomi ili politomi ključ za ribe namenjen ekspertima ihtiologije, već predstavlja ideju da se, poglavito pomoću ilustracija ( crteža i fotografija) i deskripcija, obavi prepoznavanje riba po odredjenim osnovnim spoljašnjim morfološkim odlikama i da se sistemom eliminacije dodje do vrste koja je predmet interesovanja.
Izrada i verifikacija različitih priručnika za identifikaciju vrsta pojedinačnih grupa organizama sa
priloga II, IV i V Direktive o staništima (engl. Habitat directive – Council Directive 92/43/EEC) od značaja za uspostavljanje ekološke mreže Evropske unije NATURA 2000 u Republici Srbiji deo je obaveza koje naša zemlja treba da realizuje. Priručnici treba da sadrže osnovne podatke o vrstama pojedinačnih grupa organizama, njihovoj ekologiji i distribuciji, kao i jednostavan ključ za identifikaciju. Mi smo u ovom priručniku pored vrsta koje su na različitim listama zaštićenih vrsta u Evropi i Srbiji, dali i opise vrsta koje nisu na listama i ne uživaju posebne mere zaštite. Dati su i opisi alohtonih vrsta koje naseljavaju vode Srbije i čijii značaj u vodenim ekosistemima postaje sve veći i ozbiljniji.
U skladu sa Direktivom o staništima koja se bavi očuvanjem prirodnih staništa divlje flore i faune i
Direktivom o pticama (engl. Bird Directive Council Directive 2009/147/EC) uspostavlja se evropska ekološka mreža NATURA 2000. Natura 2000 je široka mreža zaštićenih područja sa staništima i vrstama od nacionalnog i medjunarodnog značaja koja predstavlja okosnicu politike EU za očuvanje prirodne i biološke raznovrsnosti (Slika I). Ova mreža nije sistem strogih prirodnih rezervata u kojima su isključene sve ljudske aktivnosti, već uključuje prirodne rezervate i zemljišta u privatnom vlasništvu, a posebna pažnja se posvećuje obezbedjivanju održivog upravljanja u budućnosti kako sa ekološkog, tako i sa ekonomskog stanovišta. Osim
NATURE 2000, u Srbiji je uporedo uspostavljena i EMERALD evropska ekološka mreža za očuvanje divlje flore i faune i njihovih prirodnih staništa. Sastavljena je od područja od posebnog interesa za očuvanje (engl. Areas of Special Conservation Interest – ASCIs). EMERALD je kod nas počela da se sprovodi od 2005. godine. Kao rezultat izvršena je identifikacija vrsta i staništa uz predloge za proširenje liste EMERALD vrsta koje su značajne za Srbiju, kao i izbor i opise potencijalnih EMERALD područja u Srbiji. Od 61 predloženog područja detaljno je odradjeno šest (9.83%): Gornje Podunavlje, Kopaonik, Obedska bara, Prokletije,
Deliblatska peščara i Vlasina.
Osim NATURE 2000 i EMERALD-a kao medjunarodnih obaveza (Slika II), za Srbiju je značajna
izrada Crvenih lista i Crvenih knjiga pojedinačnih grupa organizama flore, faune i gljiva, u skladu sa Zakonom o zaštiti prirode ("Sl. glasnik RS", br. 36/2009, 88/2010, 91/2010 - ispr., 14/2016, 95/2018 - dr. zakon i 71/2021), koji veliku pažnju posvećuje divljim vrstama koje su ugrožene ili mogu postati ugrožene, a imaju poseban značaj sa genetičkog ekološkog, ekosistemskog, naučnog, zdravstvenog, ekonomskog i drugih aspekta i koje se štite kao strogo zaštićene ili zaštićene divlje vrste.
Redovno ažuriranje i revizije procena ugroženosti različitih vrsta u Srbiji i formiranje baza podataka
o distribuciji potencijalno ugroženih vrsta (endemiti, relikti, po medjunarodnim i nacionalnim kriterijumima retke, ugrožene i zaštićene vrste) je od najvećeg konzervacionog značaja i neophodno ih je uraditi u najskorijoj budućnosti
Biomarker-Based Assessment of Four Native Fish Species in the Danube River Under Untreated Wastewater Exposure
No full textThis study assessed the impact of untreated wastewater discharge in the Danube River on four native fish species: barbel (Barbus barbus), vimba bream (Vimba vimba), perch (Perca fluviatilis), and white bream (Blicca bjoerkna). Biomarkers of exposure and effect were evaluated, including metal and metalloid bioaccumulation in gills, liver, and gonads, DNA damage (comet assay), chromosomal abnormalities (micronucleus assay), liver enzyme activities (ALT, AST), and erythrocyte maturation. White bream showed the highest genotoxic damage (TI% = 22.57), particularly in liver tissue, indicating high sensitivity to pollution. Perch had elevated DNA damage in blood (TI% = 22.69) and strong biomarker responses, likely due to its predatory behavior. Barbel displayed notable DNA damage in gills (TI% = 30.67) and liver (TI% = 20.35), aligning with sediment exposure due to its benthic habits. Vimba bream had the lowest responses, possibly reflecting reduced exposure or resilience. Element accumulation varied across tissues and species, with perch showing the highest overall levels. Hepatic enzyme activities (highest values: ALT = 105.69 in barbel; AST = 91.25 in white bream) and changes in erythrocyte profiles supported evidence of physiological stress. Integrated Biomarker Response (IBR) analysis identified white bream as the most sensitive species, followed by perch and barbel. These results emphasize the value of multi-species biomonitoring and the importance of species-specific traits in freshwater ecotoxicology
SYNTHESIS OF SnO2 NANOFIBERS BY ELECTROSPINNING METHOD AND STUDY OF ITS ETHANOL AND ACETONE SENSING PROPERTIES
No full textGas sensors are crucial in multiple aspects of daily life, such as environmental and food quality monitoring, human and industrial safety, and illness detection. Among semiconducting metal oxides, SnO2 has been extensively investigated for gas-sensing applications owing to its wide bandgap, non-stoichiometric nature, excellent electronic mobility, and stability. To tailor its gas sensing functionalities, numerous approaches regarding its synthesis into useful nanostructured morphologies have been explored. For this purpose, electrospinning proved to be one of the most simple, versatile and low-cost method for producing nanofibers with high surface area-to-volume ratio and interconnectivity of nanoparticles.
For the preparation of the electrospinning solution, a dimethylformamide DMF/ethanol (weight % = 40:60) solvent system was used. Separately, tin(II) chloride dihydrate (SnCl2·2H2O) and polyvinylpyrrolidone (PVP) were dissolved in this solvent system. Finally, both solutions were mixed and stirred further to obtain a clear and transparent solution for electrospinning. Optimal conditions for electrospinning were: applied voltage of 20 kV, a needle-to-collector distance of 18 cm, a flow rate of 0.7 mL/h, and a collector rotation speed of 1000 rpm, using aluminum foil as the substrate. Nanofibers were collected over multiple electrospinning cycles, and after each cycle, the fiber-coated foils were dried to remove residual solvent. The dried nanofibers were calcined at 550 °C for 1 h to induce complete crystallization.
TGA of nanofibers indicates complete decomposition of the organics at 550 °C and their XRD analysis confirms the formation of pure tin oxide. The specific surface area of the as spun nanofibers was 75 m²/g with pore radius of 4.5 nm. FESEM study shows cylindrical fibers with diameter in the range of 20–50 nm with aspect ratio >1000.
The sensing films were prepared by screen-printing a paste composed of calcined nanofibers dispersed in terpineol onto Al2O3 substrates pre-patterned with interdigitated electrodes and integrated microheaters. The printed films were subsequently heated at 160 °C for 1 h to remove the organic binder and improve adhesion between the sensing layer and the substrate.
The gas sensors were tested using a dynamic gas sensing measurement system. Ethanol and acetone sensing of the nanofibers showed a good and desirable sensing behavior such as high sensitivity, fast response and recovery times
Повећање фотосинтезе код бораније гајене у пољу после третмана наранџастим угљеничним тачкама
No full textБиљна нанобионика је област истраживања која користи наночестице ради побољшања биљних функција. Ова студија истражује ефекат наранџастих угљеничних тачака (енгл. orange-carbon dots, o-CDs) на фотосинтетске параметре бораније гајене у пољу током целог вегетационог циклуса. Водене суспензије o-CDs наночестица (1 mg/L и 5 mg/L) примењиване су фолијарно у једнаким временским интервалима до цветања. Фотосинтетски параметри -брзина фотосинтезе (енгл. photosynthetic rate, PR), брзина транспирације (transpiration rate, TR) и ефикасност коришћења воде (енгл. water use efficiency, WUE) су мерени након сваког третмана помоћу LC-pro + система. Након извршених третмана спректрофотометријски је одређивана концентрација фотосинтетских пигмената (хлорофила a, хлорофила b и каротеноида). Резултати су показали да третмани и временски ток значајно мењају све тестиране фотосинтетске параметре. Примећен је растући тренд ових вредности са повећањем концентрације, а значајна разлика у односу на контролу је примећена након третмана са 5 mg/L o-CDs. У првој временској тачки (након једног третмана) није било значајних разлика у испитаним фотоситетским параметрима у поређењу са контролом. Међутим, сва три фотосинтетска параметра су била значајно повећана у другој временској тачки (након два третмана) са концентрацијом o-CDs од 5 mg/L (вредности за контролу, 1 mg/L и 5 mg/L су респективно износиле 10,134/11,650/13,826 μmol CO2·m-2·s-1 за PR; 1,834/2,053/2,238 mmol H2O·m-2·s-1 за TR и 5,519/5,678/6,180 μmol CO2·mmol-1 H2O за WUE). Садржај фотосинтетских пигмената није значајно промењен ниједним третманом ни у једној временској тачки, што указује да позитиван ефекат o-CDs наночестица на фотосинтезу
није директно повезан са променом садржаја фотосинтетских пигмената