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The occurrence and temporal variation of selected priority substances and contaminants of emerging concerns, i.e., eleven perfluorinated compounds (PFCs, belonging to perfluorosulphonates, perfluorocarboxylic acids, and perfluorinated sulphonamides) have been investigated in composite surface water samples of the Danube River at the upstream and downstream locations from the discharge point of wastewater. Among the analyzed compounds, six PFCs (PFOA, PFOS, PFHxA, PFNA, PFDA and PFUnA) were quantified. Overall, the detection frequency for most quantified compounds was very high (>90 %), only PFDA and PFUnA were quantified with less frequency, 33 and 67 %, respectively. The highest quantified concentrations of PFOA and PFOS were 14.9 ng/L (average 12.1 ng/L) and 14.2 ng/L (average 6.11 ng/L), respectively. These ones together with PFHxA (average 10.0 ng/L) were quantified at the highest concentrations in comparison to the other investigated compounds. However, the determined levels of PFOS during investigated sampling period, for all samples analyzed, were always lower than the maximum allowable concentration set for inland river waters but always higher than the environmental quality standard threshold value-AA-EQS of 0.65 ng/L sets by the Directive of European Parliament. Moreover, the levels of PFOA were always several times lower than the set AA-EQS value.

A procedure is developed for producing basic electronic components utilizing materials sourced from discarded orange, grapefruit, lemon, apple, banana, potato, and carrot peels. Initially, these materials undergo dehydration, followed by a meticulous pulverization process to obtain fine powder. Natural adhesives like water, honey, sugar, starch, and gelatin are employed to interconnect the materials. Formed substrates are characterized using Scanning Electron Microscopy, Energy Dispersive X‐ray Spectroscopy, and an optical profilometer. Furthermore, the relative permittivity of the materials is determined. Three distinct types of substrates, derived from the aforementioned peels, are crafted in varying dimensions. Substrates measuring 4 cm × 2.5 cm host interdigital capacitive sensors, whereas larger 6 cm × 3.5 cm substrates accommodate inductor‐capacitor (LC) sensors. Each of the six samples undergoes individual dry testing, while LC sensors are additionally tested with the post‐application of artificial saliva and mouthwash liquids. The sensor's characterization involves measurement of impedance and phase angle for all samples. Capacitance is additionally measured for capacitors, and inductance for LC circuits. These assessments are carried out within the frequency range spanning from 1 MHz to 400 MHz. The objective is the development of fully functional electronic components, derived from discarded edible items, fostering sustainable practices, and finding applications in biomedicine. [ABSTRACT FROM AUTHOR]

The aim of this paper was to determine spatial variation of 6 indicator polychlorinated biphenyls (PCBs) and 18 organochlorine pesticides (OCPs) in street dust samples (n=49) collected during summer season from suburban/urban zones of Tianjin, China. Sample preparation was performed by using accelerated solvent extraction with simultaneous extraction and clean-up of PCBs and OCPs, while quantification was carried out using gas chromatography coupled with microelectro absorption detector and gas chromatography coupled with mass spectrometry. The total concentrations of studied PCBs varied from

The contents of major ions in bottled waters were analyzed by principal component (PCA) and hierarchical cluster (HCA) analysis in order to investigate if these techniques could provide the information necessary for classifications of the water brands marketed in Serbia. Data on the contents of Ca2+, Mg2+, Na+, K+, Cl-, SO4 2-, HCO3 - and total dissolved solids (TDS) of 33 bottled waters was used as the input data set. The waters were separated into three main clusters according to their levels of TDS, Na+ and HCO3 -; sub-clustering revealed a group of soft waters with the lowest total hardness. Based on the determined chemical parameters, the Serbian waters were further compared with available literature data on bottled waters from some other European countries. To the best of our knowledge, this is the first report applying chemometric classification of bottled waters from different European countries, thereby representing a unique attempt in contrast to previous studies reporting the results primarily on a country-to-country scale. The diverse character of Serbian bottled waters was demonstrated as well as the usefulness of PCA and HCA in the fast classification of the water brands based on their main chemical parameters. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 172050]

Energy security and independence, increase and fluctuation of the oil price, fossil fuel resources depletion and global climate change are some of the greatest challanges facing societies today and in incoming decades. Sustainable economic and industrial growth of every country and the world in general requires safe and renewable resources of energy. It has been expected that re-arrangement of economies towards biofuels would mitigate at least partially problems arised from fossil fuel consumption and create more sustainable development. Of the renewable energy sources, bioenergy draws major and particular development endeavors, primarily due to the extensive availability of biomass, already-existence of biomass production technologies and infrastructure, and biomass being the sole feedstock for liquid fuels. The evolution of biofuels is classified into four generations (from 1st to 4th) in accordance to the feedstock origin; if the technologies of feedstock processing are taken into account, than there are two classes of biofuels - conventional and advanced. The conventional biofuels, also known as the 1st generation biofuels, are those produced currently in large quantities using well known, commercially-practiced technologies. The major feedstocks for these biofuels are cereals or oleaginous plants, used also in the food or feed production. Thus, viability of the 1st generation biofuels is questionable due to the conflict with food supply and high feedstocks’ cost. This limitation favoured the search for non-edible biomass for the production of the advanced biofuels. In a general and comparative way, this paper discusses about various definitions of biomass, classification of biofuels, and brief overview of the biomass conversion routes to liquid biofuels depending on the main constituents of the biomass. Liquid biofuels covered by this paper are those compatible with existing infrastructure for gasoline and diesel and ready to be used in mixture with them as „drop-in“ fuels: bioethanol, celullosic ethanol, biodiesel, renewable diesel and BtL diesel; their major advantages and drawbacks are compared. [Projekat Ministarstva nauke Republike Srbije, br. 172050]

The purpose of this work is to characterize biodiesel (i.e. methyl esters, MEs) produced from linoleic and oleic sunflower oils (LSO and OSO, respectively) by alkali transesterification with methanol and CaO as a heterogeneous catalyst under different reaction parameters. The parameters investigated were the methanol/oil molar ratio (4.5:1, 6:1, 7.5:1, 9:1 and 12:1) and the mass ratio of CaO to oil (2% and 3%). The physical and chemical properties of the feedstocks and MEs, like density at 15oC, kinematic viscosity at 40oC, acid value, iodine value, saponification value, cetane index, fatty acid (methyl ester) composition, were determined in order to investigate the effects of LSO and OSO properties and reaction parameters on the product characteristics, yields and purity. The properties of feedstock had decisive effect on the physical and chemical properties of MEs as majority of them did not differ significantly under studied reaction conditions. The MEs produced generally met the criteria required for commercial biodiesel; in fact, the only exception was in the case of iodine value of ME produced from LSO. The product yields only slightly changed with the applied conditions; the highest yield (99.22%) was obtained for ME-LSO produced at 6 mol% methanol to oil ratio, while the lowest one (93.20%) was for ME-OSO produced under the lowest methanol/oil molar ratio (4.5:1). The applied catalyst amounts had similar influence on the oil conversion to biodiesel. The yields of ME-LSOs were in general somewhat higher than those obtained for ME-OSOs under the same conditions, which was attributed to the influence of the respective feedstocks' acid value and viscosity.