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Impact of wastewater effluents at two sites at Danube river: genotoxicological assessment.
Get PDFOne of the most severe threats to the Danube River course through Serbia is the direct discharge of untreated wastewater. In biomonitoring studies, faecal indicator bacteria are used to reveal the presence of untreated communal wastewater, while biomarker response in indigenous biota serves as a useful indicator of their harmful potential. The objective of this study was to estimate the genotoxic potential of untreated communal wastewater at two sites on the Danube River, Višnjica (Belgrade) and Novi Banovci, by using in situ approach in white bream (Blicca bjoerkna L.). A comet assay was selected to measure DNA damage in erythrocytes, liver, and gill cells, while the micronucleus test was applied to measure chromosomal aberrations in erythrocytes.
Additionally, the accumulation of 22 elements in fish liver and muscle was analysed by ICP-OES meth- od. Simultaneous detection of total coliforms and E.coli in water was performed by enzyme-based Colilert-18 test (IDEXX). Comet assay revealed the highest level of DNA damage in gills at the site Novi Banovci, and in blood at the site Višnjica. The overall frequency of micronucleus at both sites was low. At both localities, the majority of analysed elements showed higher levels in the liver in comparison to muscle. Microbiological indicators confirmed the poor water quality, since at both sites water was categorised as critically to strongly polluted. The results of this study highlighted the importance of in situ biomonitoring approach and the need for more effective management of natural resources and implementation of wastewater treatment systems
Mineral nutrition, yield, and source-sink relationships
No full textThis chapter describes the role of nutrients in regulating plant processes underlying yield formation. The yield of crop plants is
controlled by biomass production and its partitioning to harvested plant organs. Biomass production is dependent on the capture
of light energy, through the photosynthetic activity of leaves (i.e., source activity) and leaf area, to provide carbon and energy
for the entire plant. Roots supply plants with water and nutrients from the soil. Nutrients are required for leaf growth and as
integral constituents of the photosynthetic apparatus. Nutrient supply also affects photosynthesis and leaf senescence indirectly
via photooxidation, hydraulic and phytohormonal signals as well as by sugar signaling. Nutrients impact respiration as constituents
of the respiratory electron chain and by their influence on the efficiency of respiratory ATP synthesis. The chapter
describes how photosynthate partitioning to plant organs is controlled by the capacity of these organs to utilize assimilates for
growth and storage, that is, their sink strength, and how this is influenced by nutrient supply. Nutrients play an important role
in regulating sink formation, for example, by their effects on plant architecture, flowering, pollination, and tuber initiation, as
well as in controlling storage processes in the sink organs. Nutrient supply also modifies endogenous concentrations of phytohormones
that regulate sink source relationships. The source and sink organs are physically separated. Therefore, long-distance
transport of photosynthates and nutrients in the phloem from source to sink is essential for growth and plant yield. The principles
of phloem loading of assimilates at source sites, phloem transport, and phloem unloading at the sink sites are described
LEAF NITROGEN BALANCE INDEX USED TO MONITOR STRESS RESPONSE TO AIR POLLUTION OF DECIDUOUS TREE SPECIES GROWN IN URBAN ZONE OF BELGRADE
Get PDFStreet trees are important component of urban forest presenting a first barrier between air pollution
originated from vehicle traffic and pedestrians. It implies that an improvement of air quality in urban
areas greatly depends on green biomass, in short, the bigger and greener tree crown, better for human
health and wellbeing. Determination of Leaf Nitrogen Balance Index (LNBI) and chlorophyll
concentration (ChlC) by a non-invasive methodology and a user friendly instrument (Dualex 4,
Force), widely used in agronomy and horticulture, was tested here for the assessment of tree fitness in
urban zones. Investment of energy and resources either in growth or defence according to the tradeoff
strategy of plants may be indicated by LNBI, which approximately presents a Nitrogen/Carbon
ratio. We selected few tree species from Belgrade’s streets to determine those two parameters during
summer. We also presented the changes in those parameters of the introduced bamboo species within
ten years at several urban locations in Belgrade differing in air pollution aiming to evaluate
usefulness the LNBI parameter in access of multiyear exposure to the effect of intense vehicle traffic.
Numerous limiting factors for development of healthy tree crowns in urban ecosystem, such as low
capacity to cope with toxic pollutant, sensitivity to diseases, early senescence and etc., greatly depends
on tree species. We propose this methodology may also contribute in the process of choice of the
adequate tree species to be planted along streets
Ag/ZnO NANOCOMPOSITES FOR PHOTOCATALYTIC APPLICATION
Get PDFIn this work, the decoration of noble metal nanoparticles on a semiconductor
surface was used as a strategy to reach strong visible light absorption and efficient
electron-hole separation to enhance the photocatalytic activity of ZnO.
The Ag-modified ZnO nanopowders were obtained by the green synthesis. Zinc
acetate dihydrate with different silver nitrate content (0, 0.75, 1.5 and 3 mol%) was
dissolved in ethylene glycol in the presence of chitosan. The obtained mixtures in
the form of gel were heated at 150 °C for 2 h and subsequently calcined at 400 °C
for 1 h. The obtained samples were characterized by XRPD, FESEM, HRTEM, and
UV-vis techniques while the photocatalytic efficiency was tested by monitoring the
degradation of textile dyes Reactive Orange 16 (RO16), Acid Green 25 (AG25),
Mordant Blue 9 (MB9), and Ethyl Violet (EV) then compared with the commercial
ZnO nanopowder.
The results showed that the Ag/ZnO samples consisted of ZnO nanoparticles
with an average crystallite size of about 25 nm and Ag (20–30 nm) distributed on
the surface of ZnO. The uniformity in size and nearly spherical shape of ZnO
nanoparticles, forming various forms of agglomerates, were observed. Compared to
both, the unmodified and commercial ZnO, all the prepared Ag/ZnO composites
showed a broad band in the visible region at 500 nm, resulting in a narrowing of the
band gap. This band confirms the surface plasmon resonance of the metallic Ag
nanoparticles, since they can absorb visible light and activate the photocatalyst in
the visible spectrum.
All the obtained nanopowders showed higher adsorption power and
photocatalytic activity in the degradation of RO16 dye than the commercial ZnO.
The powder with 1.5 mol% of Ag had the highest photocatalytic efficiency as a
consequence of smaller Ag particles and their good distribution, as well as the
narrowest band gap. This means that the photocatalytic activity does not depend on
the Ag content only and that the size and distribution of the metal particles play an
important role. Since the ZnO with 1.5 mol% of Ag demonstrated the best
photocatalytic activity, the same sample was tested for diverse dyes and the high
photocatalytic efficiency was also confirmed by testing on AG25, MB9 and EV
dyes
Background norepinephrine impacts activity of cortical astrocytes
No full textThe neurotransmitter norepinephrine (NE) plays a central role in regulating arousal,
attention, cognitive function and stress responses. Unlike fast neurotransmitters which
act at synapses, NE is released in the neuropil and performs multiple targeting in the
surrounding area. The glial cells astrocytes are a direct target of NE, as they express
all adrenergic receptor subtypes and respond with Ca2+ increases to NE. Astroglial
responses elicited by strong and transient increases of NE in the brain are well studied,
but the effect of a low background NE concentration on astrocytes is unknown. This
background level of NE is maintained by basal noradrenergic activity and is
constantly present in the brain. Therefore, the response of astrocytes to the
background NE could have been unintentionally evoked in previous studies but its
effect overlooked.
To assess action of background NE on astrocytes we combined the whole-cell patch
clamp, immunohistochemistry, Ca2+ imaging and pharmacology. We used cultured
cortical astrocytes to bypass NE targeting of multiple cell types.
We show that cortical astrocytes detect and respond to the background NE
concentration with an increase in intracellular Ca2+. This Ca2+ liberated from
intracellular stores further increased large-conductance, Ca2+-sensitive potassium
(BK) currents in astrocytes. Notably, immunohistochemistry data showed that BK
channels and alpha 1 adrenoreceptor are highly expressed in astrocytes in the rat
cortex. Furthermore, stimulation of astrocytes by background NE was inhibited by
alpha-adrenoceptor antagonist.
Our results suggest that astrocytes maintain basal brain activity by perceiving and
responding to the background NE.kategorija M6
Upgraded Two-Step-Scaling Approach to the DTB Characterization of Ferritic Steels
Get PDFThe fracture toughness of ferritic steels in the DTB (ductile-to-brittle) transition temperature region is a stochastic extrinsic property known for pronounced experimental data scatter that necessitates statistical approach in the DTB characterization. The novel two-step-scaling (2SS) method, proposed recently for the size effect-modeling across the DTB transition region, is developed based on the weakest-link statistics and the two-parametric Weibull distribution. Specifically, the size sensitivity of the Weibull parameters of scale and shape are built into the appropriate framework. This approach is upgraded in this article to render the comparison with the existing models more transparent. Specifically, the original 2SS method is enhanced by adding a lower limit on fracture toughness, resulting in the translated (three-parameter) Weibull cumulative distribution function. This third Weibull parameter, often dubbed the location parameter, defines a threshold value that limits the accessible fracture toughness domain. The upgraded 2SS approach is compared to two established methods of the DTB fracture toughness assessment, which favorably reflected upon its generality and application flexibility.The papers presented at the Ninth International Congress of the Serbian Society of Mechanics (July 5-7, 2023, Vrnjačka Banja, Serbia) were not published in the usual proceedings format, neither in paper nor in electronic form, but only as a collection of peer-reviewed and accepted articles published at the congress internet site
Ferroelectric, Magnetic and Dielectric Properties of SrCo0.2Zn0.2Fe11.6O18.8 Hexaferrite Obtained by “One-Pot” Green Sol-Gel Synthesis Utilizing Citrus reticulata Peel Extract
Get PDFSrCo0.2Zn0.2Fe11.6O18.8 hexaferrite was obtained by a “one-pot” green sol-gel synthesis
method utilizing aqueous mandarin orange (Citrus reticulata) peel extract as an eco-friendly reactant.
The research objective was to analyze the influence of cobalt and zinc co-doping and the synthesis
process on the structure, morphology, magnetic, dielectric and ferroelectric properties of strontium
hexaferrite in view of future applications. Structural and morphological characterization using
X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron
microscopy coupled to energy dispersive X-ray spectrometry (SEM-EDX) confirmed the formation
of a Co and Zn ion incorporated M-type magnetoplumbite with c/a lattice parameter ratio of 3.919
as crystallite nanoplatelets of 32 and 53 nm in thickness and width, respectively. The magnetic
hysteresis loop of the synthesized powder recorded by a vibrating sample magnetometer (VSM) at
room temperature confirmed its ferromagnetic nature with a coercive field (Hc) of 2539 Oe and a
saturation magnetization (Ms) and remanent magnetization (Mr) of 44.6 emu/g and 21.4 emu/g,
respectively. Room temperature ferroelectric loops measured at 100 Hz showed a maximal (Pmax)
and a remanent (Pr) polarization of 195.4 and 31.0 nC/cm2, respectively. Both increased when the
magnitude of the applied electrical field increased in the 1–24 kV/cm range. The dielectric constant
decreased with the frequency increase, in accordance with the Maxwell–Wagner model, while the
conductivity changed according to the Jonscher power law. The complex impedance was modeled
with an equivalent circuit, enabling identification of the dominant contribution of grain boundary
resistance (272.3 MW) and capacitance (7.16 pF)
A Method for Fracture Probability Assesment in Function of J-integral in Transition Temperature Regime of Ferritic Steel
No full textIn this paper is presented the 1-point method for material behaviour prediction, in terms of fracture toughness,
of the ferritic steel EN 1.6310 in the transition temperature regime (-60°C and -90°C). Experiments were carried
out at two different temperatures, representing two studies joined in one. Experimental testing was perfomed
according to ASTM 1820 standard. This 1-point method is based on statistical processing (of 2-parameters
Weibull statistics) of obtained experimental results, i.e. scattered J-integral values, of C(T) specimens with
different geometries. Fixing value of one Weibull parameter and taking into account size-dependence of
second one, fracture probabilities in the function of J-integral for large C(T)100 and C(T)200 were determined
based on testing of C(T)50 specimen size. This research pointed out the sensitivty of proposed method on
statistical sample size. One of the aims of proposed method was reducing the cost and price of laboratory
tests in overall by predicting material behaviour and testing smaller C(T) specimen size. This research
represents an upgrade of the Landes and Heerens works, and it is dedicated to their efforts in understanding
and characterisation of transition temperature regime of ferritic steels
Single and combined potential of polystyrene microparticles and fluoranthene in the induction of DNA damage in haemocytes of Mediterranean mussel (Mytilus galloprovincialis)
No full textIn this study, the possible ‘vector effect’ within the exposure of Mediterranean mussels (Mytilus galloprovincialis) to polystyrene microplastics with adsorbed fluoranthene was investigated by applying the multibiomarker approach. The major focus was placed on genotoxicological endpoints as to our knowledge there are no literature data on the genotoxicity of polystyrene microparticles alone or with adsorbed fluoranthene in the selected experimental organisms. DNA damage was assessed in haemocytes by comet assay and micronucleus test. For the assess- ment of neurotoxicity, acetylcholinesterase activity was measured in gills. Glutathione S-transferase was assessed in gills and hepatopancreas since these enzymes are induced for biotransformation and excretion of lipophilic compounds such as hydrocarbons. Finally, differences in physiological response within the exposure to polystyrene particles, fluoranthene, or particles with adsorbed fluoranthene were assessed by the variation of heart rate patterns studied by the noninvasive laser fibre-optic method. The uniform response of individual biomarkers within the exposure groups was not recorded. There was no clear pattern in variation of acetylcholinesterase or glutathione S-transferase activity which could be attributed to the treatment. Exposure to polystyrene increased DNA damage which was detected by the comet assay but was not confirmed by micronucleus formation. Data of genotoxicity assays indicated differential responses among the groups exposed to fluoranthene alone and fluoranthene adsorbed to polystyrene. Change in the heart rate patterns within the studied groups supports the concept of the Trojan horse effect within the exposure to polystyrene particles with adsorbed fluoranthene
Effect of the Deposition of Vanadium-Oxide on the Photocatalytic Activity of TiO2 Nanotubes and Its Photodiode Performance Interfaced with CH3NH3PbI3 Single Crystal
Get PDFIn this study, we report the influence of vanadium oxide (VO), as a photosensitive component, on the photoactivity of TiO2 nanotubes (TNTs). A series of TNTs of varying tube diameter were synthesized by the anodization of titanium foils at different voltages, while vanadium oxide was deposited on TNTs by wet chemical deposition. An improvement in the optical properties of nanotubes was observed after the deposition of vanadium oxide. An improvement in the optical properties (redshift in UV-Vis spectra) of TNTs and TNT/VO was noted. The photocatalytic activity was improved with increasing tube diameter, while it was weakened after the deposition of VO. Furthermore, photoactivity was investigated in photodiodes based on TNTs or TNT/VO and single crystals of CH3NH3PbI3. The photoelectric measurement revealed that different TNT diameters did not influence the I-V characteristic of the photodiodes, while the deposition of VO improved the photocurrent for smaller TNT