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Durability of high volume fly ash binders
No full textFly ash (FA), a by-product from thermal power plants, has been used for decades as Portland cement replacement material. Recently, additional efforts have been made by scientist and engineers worldwide with an aim to increase, as much as possible, content of FA in a binder, thus reduce negative environmental and economic impacts of the power and cement production. Furthermore, extensive work is being done on evaluating properties of the new binders, with a goal to ensure their wider use.
This work analyzes durability of the high volume FA binders (HVFA, ≥ 50 mass% of FA in a binder). In order to increase FA content and improve properties of the HVFA binders, FA was mechanically activated and a chemical activator was used for the binder synthesis. Freeze-thaw, carbonation and sulfate attack resistance of the binders were analyzed. It was found that the freeze-thaw resistance of the HVFA binder was in accordance with the standard requirements. Carbonation depth after 56 days of testing of the HVFA binder was 7.3–8.1 mm, and an increase in the compressive strength of the mortar was observed. Studying of the sulfate attack on the HVFA binder showed that the resistance of the FA based binder was good, and even superior to the performance of the Portland composite cement CEM II 42.5N, tested under the same conditions and used for comparison. The obtained results indicated that the HVFA binders can be used for applications where moderate compressive strength and good durability of the binder is needed
CHARACTERIZATION OF Pseudomonas syringae pv. morsprunorum ORIGINATING FROM SWEET CHERRY AND PLUM IN SERBIA
Get PDFPseudomonas strains originating from symptomatic (bacterial spot) leaf tissues of sweet cherry (Topola, Šumadija) and plum (Krušedol Selo, Srem) were isolated during 2016 and 2020, respectively. Based on the findings yielded by classical microbiological methods, LOPAT (+---+), GATTa (--++) and pathogenicity tests performed on detached fruitlets (sweet and sour cherry) and pods (bean pods), all strains were confirmed to belong to P. syringae pv. morsprunorum. The detection of cfl gene allowed strains that belong to race 1 to be identified. The DNA fingerprinting patterns obtained with four rep-PCR (BOX and ERIC), RAPD-PCR (M13), and IS50-PCR (IS50) methods revealed that the seven tested sweet cherry and plum P. s. pv. morsprunorum strains, as well as comparative KBNS71 and the reference strain CFBP 2119, were genetically heterogeneous. Conversely, MLSA based on the four-gene-based scheme (gapA, gltA, gyrB, and rpoD) indicated genetic homogeneity among all tested Serbian sweet cherry and plum strains, as well as P. s. pv. morsprunorum race 1 strains from the NCBI. Although the MLSA findings indicate that the sweet cherry and plum strains used in this study are 100% identical, as they might have different virulence genes, genome sequencing should be performed to eventually find the strain sub-clades based on the host
Impact of dolomite rock waste on soil acidity and absorption of Ca and Mg by barley and wheat
No full textThe dumps of dolomite dropouts from road construction occupy huge arable areas in north-western Russia. Although coarse dolomite particles neglected as a liming material due to its slow solubility, we hypothesise that they can serve as a cheap and long-lasting liming material. The weight loss of dolomite particles of various sizes from the dump applied to Albic Retisol and its effect on assimilation of Ca and Mg by barley and wheat were studied. The pot experiment with 300 g soil was conducted for 30 days in a laboratory phytotron. Results showed that coarse particles of dolomite waste had a positive effect on soil acidity already at the initial phases of the experiment. In the process of dissolution of dolomite, all forms of soil acidity decreased. The cultivation of barley had a stronger effect on the dissolution of dolomite particles than the cultivation of wheat. Barley plants
accumulated Ca by 1.1-1.4 times higher than wheat, other factors being identical. The relationship between the yield of green biomass and the accumulation of calcium and magnesium in the plants were empirically described using regression analysis. Results of this preliminary study showed that the by-products from dolomite stone processing can be effectively used for reclamation of strongly acidic soil in north-western Russia. This has the dual benefit of reducing the burden on the environment and reclaiming acidic soils. Further studies should include soil microbiological and biological parameters to trace the effect of root activities and dolomite dissolution rate on a field scal
Simplified validation and optimization methods for determination polychlorinated biphenyls in tuna fish
No full textPolychlorinated biphenyls (PCBs) represent important environmental pollutants from
the group of persistent organic pollutants. Although the use of PCBs is banned in many
countries, but they still figure in the environment. Due to its lipophilic character and
accumulation in fats, food of animal origin is the one that is most exposed to accumulation
and the possibility of the presence of PCB residues [2, 3]. It can be said that fish can be
considered environmental indicators. Consumption of fish and fish products is growing
globally, because consumers see fish as a natural and safe product. Fish safety control and
testing for the presence of PCBs is important because it is an indicator of the state of the
environment.
The aim of this research is to present the current determination of PCBs in fatty tissue
of tuna fish. Gas chromatography coupled with mass spectrometry (GC/MS) was used for
the detection of selected polychlorinated biphenyls. The work was performed for validation
of the most important congeners (PCB 28, 52, 101, 153, 138 and 180) which are defined by
national and international legislation.
The first step in the analysis was the validation and optimization of the determination
method with simple and quick preparation using commercial extraction kits. The validation
of basic parameters was carried out according to the guidelines of the SANTE 11312/2021
guide for precise control of pesticides in food (European Commission, 2021). Calibration
curve, correlation coefficient, limit quantification (LOQ), recovery for the spike level of 10
μg/kg and precision are shown in Table 1. The tuna fish matrix was used for validation,
because it is necessary that the matrix of all the examined samples be identical with the
matrix used for calibration. The linear calibration coefficient was between 0.9968 and
0.9999 and limit quantification ranged between 2.5 and 3.8 μg/kg (Table 1). Table 1 shows
the signal-to-noise ratios for individual PCBs obtained at the lowest point of calibration, i.e.
the value of the PCB standard of 10 μg/kg. The value of S/N for the mass spectrum
acquisition frequency of the examined congeners were greater than 50. The enhancement in
S/N is largely attributed to moving the signal to a higher frequency domain, and a higher
value confirms greater accuracy, selectivity and precision in quantification. The signal-tonoise
ratio for the peak congeners of PCB 153 in the fish matrix is shown in Figure 1. The
validated method was used for the analysis of PCBs present in 30 samples of frozen tuna
from the Adriatic Sea.
Extraction and clean-up procedural steps were applied with some modifications of the
original developed QuEChERS method. The analysis was conducted on fish samples that were frozen before analysis and measured after homogenization. The content of
polychlorinated biphenyls is expressed as the amount of micrograms of PCB on wet fish in
order to comply with the units (ng/g of wet weight) prescribed by the regulation. The
presence of tested PCBs was not confirmed in the tested tuna samples.
The validated method can also be applied to routine analysis and monitoring of
processed tuna fish products on the Serbian market and improve food safety
Modeling the effect of temperature on relative humidity sensing
Get PDFIn this work we have established a mathematical function to model the influence of the ambient temperature, relative humidity and frequency on the change of impedance. The proposed empirical description is a combination of the power function (modeling the temperature effect) and a reverse-sigmoid function inspired by the three-parameter Weibull cumulative distribution function (modeling the relative humidity and frequency effects). This empirical model was validated by using our iron manganite (FeMnO3) thick film measurement data. The reduction of impedance of thick film samples with change in relative humidity in the range 30-90% was measured in a temperature and climatic chamber in the frequency range 42 Hz – 1 MHz at three ambient/working temperatures (25, 50 and 75 C). The obtained experimental data was successfully fitted using the specially tailored empirical model. Application of this model enables prediction of the iron manganite sensor performance for different temperatures both within the confines of the analyzed temperature range (interpolation) and outside of it (extrapolation). Future development will include applying this model to analyzing the temperature influence on relative humidity sensing for other metal oxide sensing materials that have shown a similar dependence and in a wider ambient temperature range
Horseradish peroxidase immobilization within micro-beads of oxidized tyramine-alginate for phenol removal from wastewater
Get PDFNatural polymers such as alginate, pectin, chitosan etc. were used as carriers for the immobilization of different types of enzymes. Among investigated enzymes, peroxidases hold a special place. Immobilized enzymes are frequently used in phenol removal reactions. In this research horseradish peroxidase was immobilized within alginate micro-beads. This natural polymer was previously oxidized with sodium periodate and modified with tyramine hydrochloride. Percent of oxidation was varied from 2.5 mol% to 10 mol%, and an increase in specific activity was noticed with increasing the oxidation percent. Immobilized peroxidases showed satisfactory stabilities after 10 days of storage. Phenol concentration in a batch reactor decreased during its oxidation with horseradish peroxidase immobilized on tyramine-alginate hydrogels
Experimental Setup for Testing Low Energy Harvesting Devices Based on Lead-Free NBT-BTPVDF Composite Flexible Films
No full textThe paper presents the realization of an experimental setup used for testing energy harvesting and storage devices based on the use of lead-free bismuth sodium titanate-barium titanate (NBT-BT) in combination with polyvinylidene fluoride (PVDF) polymer. PVDF is a polymer matrix in which
piezoelectric phase is dispersed and enables formation of flexible films by hot pressing method. The paper presents an electromechanical model of a typical PVDF module, generates a
simulation model, and presents simulation results. The experimental setup is based on a mechanical excitation for generating pulses of an force of different amplitude and duration,
applied on the aforementioned energy harvesting NBT-BT-PVDF devices, likewise, on an electronic assembly for measuring the pulses of electrical quantities (current and voltage), that are
generated at the output electrodes. The research in this paper is predominantly experimental and it shows the obtained oscilloscope recordings of the excitation force and output voltage
of energy harvesting modules at different modes and conditionsof mechanical excitation. After this, a comparison of the simulation and experimental results is made
Trans-generational effect of cerium oxide-nanoparticles (nCeO2) on Chenopodium rubrum L. and Sinapis alba L. seeds
Get PDFCerium oxide nanoparticles (nCeO2) are interesting nanomaterials due to their redox properties. Their wide application could result in unexpected consequences to environmental safety. Unlike acute toxicity, the trans-generational effects of carbohydrate-coated nCeO2 in the environment are still unknown. The main aim of this study was to investigate the effect of treating maternal plants of Chenopodium rubrum L. (red goosefoot) and Sinapis alba L. (white mustard) with uncoated (CeO2) and glucose-, levan-, or pullulan-coated nCeO2 (G-, L-, or P-CeO2) during seed germination on morphological and physiological characteristics of produced seeds in two subsequent generations. The plant response was studied by measuring germination percentage (Ger), total protein content (TPC), total phenolic content (TPhC), total antioxidative activity (TAA), and catalase (CAT) activity. Results showed that maternal effects of the different nCeO2 treatments persist to at least the second generation in seeds. Generally, C. rubrum was more sensitive to nCeO2 treatments than S. alba. The coated nCeO2 were more effective than uncoated ones in both plant species; L- and P-CeO2 were the most effective in S. alba, while CeO2 and G-CeO2 had a dominant impact in C. rubrum. Enhanced germination in all tested generations of S. alba seeds recommends nCeO2 for seed priming
Maize metabolomics in relation to cropping system and growing year
Get PDFMaize is important to global food security, being one of the predominant cereals in human and domesticated livestock diets worldwide. Due to the increasing human population, it will be important to not only design cropping systems to increase maize yield and sustainability but also to improve the nutritional quality of maize edible tissues. To determine cropping system impacts on maize grain nutritional content, we sampled grain from conventional and organic maize varieties grown for three growing seasons using five cropping systems. We analyzed the grain using metabolic fingerprinting of methanol extracts with ultra-high performance liquid chromatography (UHPLC) coupled with mass spectrometry (MS), adopting both non-targeted and targeted approaches. The cropping systems are part of a long-term study at the Beltsville Agricultural Research Center in Beltsville, Maryland, and were a three-year conventional no-till rotation (NT), a three-year conventional chisel-till rotation (CT), a two-year organic rotation (Org2), a three-year organic rotation (Org3), and a six-year organic rotation (Org6). Each cropping system had been in place for at least 10 years, allowing specific cropping-system-induced alterations of soil edaphic and microbial properties. Non-targeted metabolic fingerprinting detected a total of 90 compounds, the majority of which were phenolics. Metabolic profiling was further targeted toward 15 phenolics, 1 phytohormone, 7 carbohydrates and 7 organic acids, which were quantified in the maize grain originating from the five cropping systems. Statistical analysis of this subset of quantitative data determined that cropping system can significantly influence levels of certain maize grain metabolites. However, natural impacts (growing year) were substantially greater than cropping system impacts, likely masking or over-riding some cropping system impacts. Additionally, maize cultivar genetics had greater impact than cropping system on the maize grain metabolome and was the greatest “managed” impact on the metabolite profiles. Results indicate that until natural environmental impacts on maize grain metabolite levels are understood and managed, the best approach to reliably increase maize grain nutritional quality is through development of maize cultivars with enhanced nutritional content that are robust to natural environmental influence
Political and Socio-Economic Aspects of Fisheries in Inland and Coastal Waters of the Western Balkan
Get PDFIn the last decades in Europe, especially in the Balkan region, modernization of agriculture gave priority to economic growth without consideration of the environmental impact and sustainable development. Fisheries have traditional and essential importance of food and income in the Slovenia, Croatia, Serbia, Bosnia and Herzegovina, Montenegro, North Macedonia, and Albania (Western Balkans). The fisheries sector in Western Balkans is still not organized according to requirements of ecosystem integrity and sustainable utility. Practical application of the legislation indicates that the fishery has been developed without adequate harmonization with socio-economic characteristics, enforcement resources, and adequate control measures. Policymakers continue to be reluctant to give importance to the fishery sector, when allocating fishery resources among multifunctional users of water resources. In the following text, we gave review of the fisheries policy and socio-economic aspects of fishery sector in the Western Balkan countries. Critical fisheries policy and management measures are discussed and the propositions and recommendations of environmental sustainability measures under modern anthropogenic pressures are presented