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

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

Antioxidant and Antiproliferative Activity of Allium ursinum and Their Associated Microbiota During Simulated in vitro Digestion in the Presence of Food Matrix

In this study, for the first time, the comprehensive analysis of antiproliferative and antioxidant activities of ramson, followed by the analysis of its associated microbiota and health-promoting effects of lactic acid bacteria (LAB), was performed. Ramson (Allium ursinum) is recognized as a medicinal plant with a long history of use in traditional medicine due to its antimicrobial and antioxidant activity. In this study the influence of in vitro gastrointestinal digestion on the cytotoxic activity of A. ursinum extracts against human malignant cell lines was demonstrated. Seven sulfur compounds, the degradation products of thiosulfinates, including diallyl disulfide were shown to inhibit proliferation of malignant cells by inducing accumulation within G2/M phase as well as to induce apoptosis through activation of caspase-3 and mitochondrial signaling pathway. Further, the A. ursinum microbiota, particularly LAB with potential probiotic effects, was analyzed by culture-dependent method and culture-independent method [denaturing gradient gel electrophoresis (DGGE)]. The obtained results revealed that the most abundant genera were Streptococcus, Lactobacillus, and Bacillus. The Lactobacillus genus was mainly represented by L. fermentum. The pulsed-field gel electrophoresis (PFGE) analysis revealed the presence of two PFGE pulsotypes. The probiotic potential of the strain L. fermentum BGSR163 belonging to PFGE pulsotype 1 and the strain L. fermentum BGSR227 belonging to the PFGE pulsotype 2 was characterized. The results revealed that both strains are safe for human use, successfully survive the simulated gastrointestinal conditions, have potential to transiently colonize the gastrointestinal tract (GIT) and have a protective immunomodulatory effect, inducing the production of proinflammatory cytokine IL17 and regulatory cytokine IL10, while decreasing the production of proinflammatory cytokine IFN-γ. In conclusion, the results of this study suggest that consumption of A. ursinum might have health-promoting properties, including anticancer effects, while L. fermentum strains isolated from A. ursinum leaves could be used as probiotics for human consumption

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

Effects of international development assistance to Sub-Saharan Africa

Рад се бави истраживањем и анализом ефеката званичне развојне помоћи државама Подсахарске Африке. Ауторка сарадњу у области развоја између сиромашних подсахарских држава, и развијених држава које припадају групи традиционалних међународних донатора, смешта у шири историјски контекст, у којем она заправо представља само једну од фаза у односима две стране. Ова последња фаза, фаза тзв. „постмодерног империјализма“, је поред атрибута из претходног периода, развила и читав низ нових одлика. Позиционирање званиче развојне помоћи афричким државама у шири историјски контекст, представља нужан предуслов за разумевање озбиљности развојне кризе са којима се суочавају постколонијалне афричке државе, као и улоге коју развојна помоћ има у њеном одржавању, односно продубљивању. Када је након завршетка Другог светског рата, уследила дезинтеграција великих европских империја и започео процес деколонизације Африке, отпочело је и успостављање сложене архитектуре међународне помоћи за развој. Од успостављања глобалног режима помоћи, па до данас, редистрибуција помоћи за развој се одвијала унутар граница које су исцртавали, с једне стране себични интереси богатих држава, и, с друге стране, жеља да се афричка друштва фундаментално трансформишу према западном моделу, што је, према схватању донатора, представљало основни предуслов њиховог одрживог економског развоја. Развојна помоћ коју обезбеђују међународни донатори, никада није била безусловна, с тим што је од почетка 1980-их година, условљавање постало екплицитно, са циљем да се оствари свеобухватно редефинисање фундаметалних принципа на којима су афричке државе успостављене. Истовремено, регион Подсахарске Африке је постао регион у којем је интензитет развојне помоћи, и у историјској али и компаративној перспективи, без преседена.The dissertation is researching and analysing the effects of official development assistance (ODA) to Sub-Saharan Africa. Development cooperation between poor African states, and developed donor countries, gathered in the Development Assistance Committee, has been positioned within wider historical context, in which it represents only one of the phases in the relationship between two sides. The latest phase, the phase of the so called “postmodern imperialism”, along with some attributes inherited from the previous stages, developed a whole range of new, distinctive features. Positioning of ODA within the wider context, represents one of the crucial and therefore necessary preconditions for better understanding of permanent development crisis of the postcolonial African states, and the role of ODA in its persistence. Right after the end of the World War II, the process of the disintegration of the European empires and decolonization of Africa, was followed by the establishment of the global aid architecture. Since the establishment of the global aid regime, the redistribution of ODA has been taking place within the boundaries drawn by the selfish national interests of the developed countries, but also by the attempt of the international donor community to fundamentally transform African societies in accordance with the Western model, which is considered to be a precondition for the sustainable economic growth and development. Foreign aid, provided by the developed countries, was never unconditional, but since the beginning of the 1980s, it has become explicitly conditional in order to contribute to the fundamental re-conceptualization of the very foundations of the African societies. At the same time, intensity of the foreign aid to Sub-Saharan Africa is, historically and comparatively, unprecedented

Statistical Analysis of Langmuir Waves Associated with Type III Radio Bursts: II. Simulation and Interpretation of the Wave Energy Distributions

We have modeled electrostatic Langmuir waves by an electric field, consisting of superposition of Gaussian wave packets with several probability distributions of amplitudes and with several Poisson distributions of wave packets. The outcome of the model is that the WIND satellite observations, especially in the low frequency domain (the WAVES experiment), do not allow to conclude whether the input wave amplitude distributions are closer to the log-normal than to the Pearson type I or uniform. The average number of wave packets in 1 s is found to be between 0.1 and 50. Therefore, there is a clear need to measure Langmuir wave energy distributions directly at the waveform level, not a posteriori in the spectral domain. This is planned to be implemented on the RPW (Radio and Plasma Wave Analyzer) instrument in the Solar Orbiter mission

Disc and halo kinematic populations from HIPPARCOS and Geneva-Copenhagen surveys of the solar neighbourhood

Discontinuities in the local velocity distribution associated with stellar populations are studied using the Maximum Entropy of the Mixture Probability from HIerarchical Segregation (MEMPHIS) improved statistical method, by combining a sampling parameter, an optimisation of the mixture approach, and a maximisation of the partition entropy for the constituent populations of the stellar sample. The sampling parameter is associated with isolating integrals of the stellar motion and is used to build a hierarchical family of subsamples. We provide an accurate characterisation of the entropy graph, in which a local maximum of entropy takes place simultaneously with a local minimum of the $\chi^2$ error. By analysing different sampling parameters, the method is applied to samples from the HIPPARCOS and Geneva-Copenhagen survey (GCS) to determine the kinematic parameters and the stellar population mixture of the thin disc, thick disc, and halo. The sampling parameter P=|(U,V,W)|, which is the absolute heliocentric velocity, allows us to build an optimal subsample containing both thin and thick disc stars, omitting most of the halo population. The sampling parameter P=|W|, which is absolute perpendicular velocity, allows us to create an optimal subsample of all disc and halo stars, although it does not allow an optimal differentiation of thin and thick discs. Other sampling parameters, such as P=|(U,W)| or P=|V|, are found to provide less information about the populations. By comparing both samples, HIPPARCOS provides more accurate estimates for the thick disc and halo, and GCS for the total disc. In particular, the radial velocity dispersion of the halo fits perfectly into the empirical Titius-Bode-like law $\sigma_{U} = 6.6 \, (\frac43)^{3n+2}$, previously proposed for discrete kinematical components, where the values n=0,1,2,3 represent early-type stars, thin disc, thick disc, and halo populations, respectively. The kinematic parameters are used to segregate thin disc, thick disc, and halo stars, and to obtain a more accurate Bayesian estimation of the population fractions. To check the reliability of our results, an alternative segregation approach is used. GCS stars are classified into different kinematical populations in terms of their orbital parameters. The population fractions and velocity moments obtained by both methods are in excellent agreement.

Statistical Analysis of Langmuir Waves Associated with Type III Radio Bursts: I. Wind Observations

Interplanetary electron beams are unstable in the solar wind and they generate Langmuir waves at the local plasma frequency or its harmonic. Radio observations of the waves in the range 4-256 kHz, observed in 1994-2010 with the WAVES experiment onboard the WIND spacecraft, are statistically analyzed. A subset of 36 events with Langmuir waves and type III bursts occurring at the same time was selected. After removal of the background, the remaining power spectral density is modeled by the Pearson system of probability distributions (types I, IV and VI). The Stochastic Growth Theory (SGT) predicts log-normal distribution for the power spectrum density of the Langmuir waves. Our results indicate that SGT possibly requires further verification

Molecular characterization of natural dairy isolates of enterococcus faecalis and evaluation of their antimicrobial potential

Due to their ability to survive adverse conditions, enterococci are widespread in nature and can be found in milk, dairy products and human and animal gastrointestinal tracts. Still, the use of enterococci in food preparation is controversial, since they have traditionally been branded as indicators of faecal contamination and their role in food spoilage is well known. However, some enterococcal strains exhibit antimicrobial effects and have probiotic potential, contributing to the improvement of the general state of health. For that reason, we have analyzed natural isolates of Enterococcus faecalis originating from various dairy products manufactured in rural households located in the mountains of Serbia. Genotyping analysis of selected enterococci showed high diversity among the isolates. The antimicrobial activity of the isolates showed a great effect on the number of pathogenic and non-pathogenic strains, including L. monocytogenes, L. innocua, E. coli, Pseudomonas sp., and Candida pseudotropicalis. Furthermore, analysis of the presence of known bacteriocin encoding genes showed that the genes for various enterocins were present. Although in some strains more than one enterocin gene was detected, there was no correlation between the number of enterocin genes and the antimicrobial spectrum. Nevertheless, in order to characterize the strains that could be safely used as starter cultures in functional food, the frequency of virulence determinants and antibiotic resistance, as well as the synthesis of biogenic amines, was analyzed. The results show that the presence of virulence determinants and antibiotic resistance is strain dependent and region specific. In addition, a large percentage of the strains have the ability to decarboxylate tyrosine and other amino acids. Such capacity for decarboxylation of amino acids limits the use of the strains in the food industry. Based on these results, it can be concluded that enterococci isolated from animal food must be viewed with particular caution because they are reservoirs of genes for antibiotic resistance and virulence