Effect of Sample Preparation on Portable X-Ray Fluorescence Spectrometry Analysis of Contaminated Soils

Toxic metals in soil are routinely determined by several analytical spectroscopic techniques (Atomic Absorption Spectrometry AAS, Inductively Coupled Plasma Optical Emission Spectrometry ICP-OES,and Inductively Coupled Plasma Mass Spectrometry ICPMS)[1]. Those techniques measure metals from aqueous samples. Procedures of sample dissolution or extraction typically involve a lengthy process which requires the use of harsh conditions. Sample preparation procedures make these routinely used techniques generally time-consuming and too expensive [2]. On the other side, the need for reliable, economical, and environmental friendly technique for soil composition measuring has been growing in the environmental field, so has the demand for time and cost-efficient analytical methods for soil analysis [3]. X-ray fluorescence spectrometry (XRF) is a multi-element analytical technique for direct, non-destructive analysis of various materials (including soils) with minimal sample preparation. The most attractive advantage of XRF is the wide dynamic range (from mg kg-1 to 100%). A portable X-ray fluorescence spectrometer (PXRF) is also capable of in-situ analysis in a short time (30–120 s) [4]. In situ PXRF analysis provides flexibility and allows rapid collection of data for a large number of samples, andproduces real-time data that can be used for rapid decision making. It is well-known that the physical characteristics of the sample play an important role in obtaining accurate results when it comes to XRF methods. Therefore it is important to determine how reliable in situ PXRF results are. Analytical accuracy and precision could be generally improved if adequate sample preparation procedure is applied compared to in situ measurements. The aim of this research was to determinate in what extent sample preparation procedure changes measured concentrations of elements and is that change the same for all investigated elements. Does soil sample homogenization or further pressing into the compact pellet systematically affect measured concentrations? Soil samples from 32 industrial, potentially contaminated sites were collected from a depth of 10 cm, 30 cm, and 50 cm. Such soils provide wide concentration range of different elements. Samples were first directly analyzed in the field, without any sample preparation using the Thermo Scientific™ Niton™ XL3t GOLDD+ PXRF Analyzer. The second PXRF analysis was performed in the laboratory on the dry,ground, and homogenized soil powder sample. One aliquot of soil powder was digested for AAS analysis, while another aliquot was pressed into a 32 mm diameter pellet and analyzed using PXRF. The quality control program involves comparison of the results with AAS reference technique. Additionally, certified reference materials of stream sediment (STSD-3) and soil (NCS DC 77301) are analyzed with different sample preparation procedures

Toxic Metals in 3 Fractions (d<63µm, d63-250µm and d250-1000µm) of Dust Collected on Roads of Industrial Town Kostolac, Serbia

Kostolac is a town exposed to several serious sources of toxic metals and other inorganic pollutants. They arrive from sources typical for urban environments such as traffic, but also from various heavy industry sources: coal mining, burning of coal in power plants, ash landfills, and steel factory. Toxic metals in the air are concentrated in particulate matter. Their transport and health risks depend strongly on the size of dust particles. Goals of the research were to estimate: 1. how much does traffic contributes to the total pollution load compared to the natural sources and the industry; 2. how is pollution distributed in different fractions of the dust; 3. are there any spatial trends present and is there any correlation between vicinity of pollution sources and concentrations of toxic elements in different fractions of the dust. Samples of dust were collected from 10 locations in July and in September. Each location had one sampling site on a major road with intensive traffic and the other site on auxiliary road with much less traffic, located 10- 20 m away from the major road. The dust was dried, sieved through sieves with 3 different apertures (d=63µm, 250µm and 1000µm) and pressed into 32 mm diameter pellets. The samples were analysed by WD-XRF standardless method. The results showed that Al, P, K, V, Mn, Fe, Co, Zr, Rb and Ti have the highest concentrations in the smallest fraction (d<63µm) and the lowest concentrations in the most coarse fraction with stat. significant differences among concentrations. Concentrations of: Mg, S, Zn and Cu have the same trend as previous group of elements but no stat. significant differences, wile conc. of Si and Ca have the opposite trend. Neither the time of the year nor the intensity of the traffic have had any significant effect to the concentrations, therefore it can be concluded that industrial sources of pollution have significantly higher attribution to the total pollution load than traffic. The trend that toxic elements are more concentrated in the smallest fraction of the dust indicates that the source of the pollution is rather anthropogenic than natural. Concentrations of elements in dust collected on sites from our research were compared to concentrations of the same elements in the soil collected by SEPA (Serbian Environmental Protection Agency). Although locations from both researches were in close proximity, no significant correlation between concentrations was observed. The lack of correlation can be explained by several hypotheses which should be further investigated in future researches

The Sigma - D relation for planetary nebulae

We present an extended analysis of the relation between radio surface brightness and diameter -- the so-called $\Sigma-D$ relation for planetary nebulae (PNe). We revise our previous derivation of the theoretical $\Sigma-D$ relation for the evolution of bremsstrahlung surface brightness in order to include the influence of the fast wind from the central star. Different theoretical forms are derived: $\Sigma \propto D^{-1}$ for the first and second phases of evolution and $\Sigma\propto D^{-3}$ for the final stage of evolution. Also, we analyzed several different Galactic PN samples. All samples are influenced by severe selection effects, but Malmquist bias seems to be less influential here than in the supernova remnant (SNR) samples. We derived empirical $\Sigma-D$ relations for 27 sample sets using 6 updated PN papers from which an additional 21 new sets were extracted. Twenty four of these have a trivial form of $\beta \approx 2$. However, we obtain one empirical $\Sigma-D$ relation that may be useful for determining distances to PNe. This relation is obtained by extracting a recent nearby (< 1 kpc) Galactic PN sample.Comment: 12 pages, 3 tables, 4 figures. Accepted for publication in Astronomy & Astrophysic

Cross-national variations in reported discrimination among people treated for major depression worldwide: The ASPEN/INDIGO international study

Background: No study has so far explored differences in discrimination reported by people with major depressive disorder (MDD) across countries and cultures. Aims: To (a) compare reported discrimination across different countries, and (b) explore the relative weight of individual and contextual factors in explaining levels of reported discrimination in people with MDD. Method: Cross-sectional multisite international survey (34 countries worldwide) of 1082 people with MDD. Experienced and anticipated discrimination were assessed by the Discrimination and Stigma Scale (DISC). Countries were classified according to their rating on the Human Development Index (HDI). Multilevel negative binomial and Poisson models were used. Results: People living in 'very high HDI' countries reported higher discrimination than those in 'medium/low HDI' countries. Variation in reported discrimination across countries was only partially explained by individual-level variables. The contribution of country-level variables was significant for anticipated discrimination only. Conclusions: Contextual factors play an important role in anticipated discrimination. Country-specific interventions should be implemented to prevent discrimination towards people with MDD

A cloud-based with microcontroller platforms system designed to educate students within digitalization and the industry 4.0 paradigm

The primary purpose of this paper is to present a system intended for student education based on a microcontroller platform and a cloud system where data will be stored. Obtained research results will be based on the application of The NodeMcu platform for data collection with sensor systems. MatLab, ThingSpeak cloud system, and the Virtuino platform will be used for data presentation. Quantitative data are applied to determine conditions for agriculture system performance management. By analyzing the literature and the current situation in monitoring and managing in the agriculture and ecology field, it can be concluded that there are no special education courses regarding these issues. This knowledge was a good starting point for the research presented in this paper. Accordingly, the findings include developing a monitoring and management system intended for student education in mentioned fields. In addition, the practical implications of this research includes the acquisition of information related to student satisfaction with this method of education in the courses of engineering, agriculture, and ecology. The presented system may enable benchmarking, simulation, and verification of different scenarios to improve students’ knowledge regarding sensors’ application in natural conditions. The originality of the research lies in the presented software solution that can be made available to educational institutions and other scientific institutions to serve as a basis in the overall monitoring and management of agricultural and ecology parameters

People with physical disability in Serbia: Relationship between internalized stigma, experienced and anticipated discrimination, and empowerment

The aim of present study was to explore relationships between experienced and anticipated discrimination, internalized stigma, and empowerment among people with physical disabilities in Serbia. The convenience sample consisted of persons with different types of physical disabilities. The following scales were administrated: The Discrimination and Stigma Scale, the Internalized Stigma of Mental Illness Scale, and the Boston University Empowerment Scale. An analysis showed that internalized stigma was correlated with experienced and anticipated discrimination and empowerment, while no correlation was found between empowerment and discrimination. People with physical disabilities who experienced and anticipated discrimination are at higher risk of reporting internalized stigma

Microbiota associated with pollen, bee bread, larvae and adults of solitary bee Osmia cornuta

Using cultivation-dependant method, we isolated 184 strains from fresh and old bee bread, pollen, larvae and adults of solitary bee Osmia cornuta. The 16S rDNA sequencing of 79 selected isolates gave the final species-specific identification of strains. Phylogenetic analysis indicated that microbiota isolated from five different sources were represented with 29 species within three different phyla, Firmicutes with 25 species, Actinobacteria with only one species and Proteobacteria with three species of Enterobacteriaceae. Bacterial biodiversity presented with Shannon-Wiener index (H') was highest in the alimentary tract of adults and old bee bread (H' = 2.43 and H' = 2.53, respectively) and in the same time no dominance of any species was scored. On the contrary, results obtained for Simpson index (D) showed that in pollen samples the dominant species was Pantoea agglomerans (D = 0.42) while in fresh bee bread that was Staphylococcus sp. (D = 0.27). We assume that microbial diversity detected in the tested samples of solitary bee O. cornuta probably come from environment

In vivo MRI biocompatibility evaluation of functionalized carbon fibers in reaction with soft tissues

In modern medicine implants are very important and so is their design and choice of materials. Almost equally important is the choice of imaging technique used to in vivo monitor their fate and biocompatibility. The aim of this study was to evaluate the ability of magnetic resonance imaging (MRI) in monitoring the biocompatibility of two newly designed carbon fibers. We have analyzed the interaction of surface functionalized carbon fibers (basic and acidic) with muscle and subcutaneous tissues of rabbits. MRI techniques showed to be useful in longitudinal monitoring of the surrounding tissues, assessment of biocompatibility of new implants, and in the distinction of in vivo surgical edema from inflammation. Histopathology confirmed MRI results, thus showing that MRI has a great potential for in vivo studies of such materials. [Projekat Ministarstva nauke Republike Srbije, br. III 45006 and III 41005