The Progeny of Stellar Dynamics and Stellar Evolution within an N-body model of NGC 188

We present a direct N-body simulation modeling the evolution of the old (7 Gyr) open cluster NGC 188. This is the first N-body open cluster simulation whose initial binary population is directly defined by observations of a specific open cluster: M35 (150 Myr). We compare the simulated color-magnitude diagram at 7 Gyr to that of NGC 188, and discuss the blue stragglers produced in the simulation. We compare the solar-type main sequence binary period and eccentricity distributions of the simulation to detailed observations of similar binaries in NGC 188. These results demonstrate the importance of detailed observations in guiding N-body open cluster simulations. Finally, we discuss the implications of a few discrepancies between the NGC 188 model and observations and suggest a few methods for bringing N-body open cluster simulations into better agreement with observations.Comment: Contributed talk at IAUS 266 'Star clusters: basic galactic building blocks', R. de Grijs and J.R.D. Lepine, eds. 6 pages, 4 figure

New quantitative criteria assess the degree of environmental water pollution with organochlorine insecticides

Environmental pollution is the result of rapid urbanization, industrialization, transport development and intensive agricultural production with the constant introduction of new technologies. Since the middle of last century, a disproportion occurs between the increase in human population and the necessary renewal of natural resources. The problem of water protection is an integral part of the overall problem of protection, promotion and preservation of the environment. Water protection is a broad and complex topic, so it is interdisciplinary. Increased use of chemicals in agriculture, particularly organochlorine insecticides (OCI) plant protection products, lead to their increased amount in water. Although OCI are very toxic substances for wildlife, especially for humans, a large part of the population is exposed to their daily activities in small quantities. For many OCI there is not enough data on the toxicity and we can not perform an accurate assessment of security. Previous studies did not provide accurate information about the effects on human health at concentrations normally found in drinking water. OCI presence in drinking water is generally below the maximum allowable concentration, but repeated doses can cause chronic toxic effects. For these reasons, the main objective of cleaning water is getting water from the lower concentration of OCI. Standard methods of water purification do not remove pesticides, so it is necessary to introduce some additional treatment using coagulation, oxidation and adsorption agents. Many studies suggest a beneficial effect of water purification, activated carbon. Activated carbon is, today, considered the most effective substance in purification of water contaminated with OCI but the procedure is still under developement. Adsorption characteristics of activated carbon must meet the requirement of efficient water purification of organochlorine insecticides, and other substances that are prohibited in concentrations. For these reasons, the goal of research is to analyze the state of the burden of drinking and wastewater aggregate and individual OCI prescribed in the Regulations of the chemical quality of drinking water (Official Gazette of FRY, no. 42/98 and 44/99). The survey covered the following OCI: alpha-hexachloro cyclohexane, lindane, heptachlor, aldrin, dieldrin, endrin, dichlorodiphenyl-trichloroethane. For some OCI values of maximum permissible concentrations are not organized in our normative and EU reulative. Therefore, the overall goal of the research is to establishing new criteria for each tested OCI. In addition, the aim of the research includes finding the most efficient method of water purification using commercial activated carbons. To achieve the objective of the survey water was analyzed from the water supply of the City of Kraljevo and waste water from fruit plants PIK „Takovo” and ZZ „Lunovo selo”. In the water samples qualitative and quantitative analysis of physical-chemical parameters were performed, total and individual OCI required by the current regulations. The analyzes were performed before and after the water purification. For the purification of water we used an experimental model of columns filled with four kinds of activated carbons, which can be found on the market. Physico-chemical analysis of water were made by following methods: · volumetric methods (volumetric determination of organic substances-consumption of KMnO4, calcium and magnesium); · electrochemical method (pH); · spectrophotometric methods (determination of nitrate, ammonia, iron); · chemical methods: chemical oxygen demand (COD), biochemical oxygen demand (BOD), suspended solids, total organic carbon (TOC) and surface-active matters (SAM). Present organochlorine insecticides were treated according to the appropriate method of the EPA-608, a liquid-liquid extraction. The method is equally applicable for determination of organochlorine insecticides in drinking water and wastewater. Investigated organochlorine insecticides were detected by gas chromatography chromatograph "Perkin Elmer" 8500 with ECD detector, with appropriate columns . Quantitative data on the toxicity of the investigated physico-chemical parameters and specific organochlorine insecticides in water were obtained as the sum of the quotient of measured concentrations and corresponding boundary residue levels (MAC) taken from the applicable ordinances and regulations: Based on the objectives and the results obtained, among other things, following conclusions were derived: · Analysis of physico-chemical parameters and total organochlorine insecticides in samples of drinking water indicates that the water meets the standards of the Ordinance on the sanitary quality of drinking water (Official Gazette of FRY, no. 42/98 and 44/99). · The tap water: Institute of Public Health, Kraljevo and pumping stations Konarevo showed increased concentration of organochlorine insecticide heptachlor and aldrin, which is an alarming fact, and further extensive testing and water treatment are necessary. · The drinking water of the city of Kraljevo must be treated with activated carbon to meet standards given by the Regulations. · It was found that, of the tested commercial activated carbons, the best effect of drinking water treatment, based of physico-chemical parameters, total and individual OCI, achieved by column experimental model, which is filled with active carbon NORIT ROW-0.8. When it comes to changes in water quality predicted Regulation on hygienic drinking water. · The effect of wastewater treatment on the physical and chemical parameters, total and individual OCI is high and the best column in an experimental model which is filled with active carbon NORIT ROW-0.8, more than 92%. Treated waste water have, a pH value that is increased compared to the values predicted applicable statutes and regulations. · Based on the results of determining the toxicity of hazardous substances examined, it can be concluded that drinking and waste water must be purified. · Ordinance on Hazardous Substances in water prescribed values of maximum permissible levels for drinking water, wastewater and river waters are high and inadequate, we clearly identify our research. · The maximum allowable concentrations of organochlorine insecticides in rivers of all classes have changed and they need to be srticter because most cities is supplying drinking water from rivers that are not treated or only partially treated. · For waste water, regardless of whether they are discharged into the sewer or river must be established purification systems. The results of this study indicate the need for treatment of wastewater from industrial fruit before discharge to receiving waters. · This research suggests that the experimental model with active carbon NORIT ROW-0.8 is an efficient process for purification of water and that further research should focus on developing a commercial model. Its application would be particularly important in rural areas in order to obtain good quality water for irrigation. The overall objective of our research was to determine the value of the maximum allowable concentration, or new quantitative criteria for each tested organochlorine insecticide, but during the preparation of this dissertation in Serbia new rules and regulations were established: · Ordinance on the determination of surface water bodies and ground water, Official Gazette of RS, 96/10; · Ordinance on the parameters of the ecological and chemical status of surface water and chemical parameters and quantitative status of groundwater, Official Gazette of RS, 74/11 and · Regulation on limit values for pollutants in surface and ground waters and sediments and deadlines for their achievement, Official Gazette of RS, 50/12, who do not recognize the organochlorine insecticides such pollutants of surface, ground and waste water. Our obtained results provide evidence that the studied organochlorine insecticides belong to the pollutants and waste drinking water and justify the need for their return to the rules and regulations. There is a need of adopting new MAC values for all OCI that regulations and their harmonization with EU directives and guidelines of the WHO. Also, we should not forget that the purification of drinking and waste water especially from the present organochlorine insecticides, are increasingly necessary if we want to join Europe and to meet European standards for discharge of wastewater into the city sewers or rivers. To maintain the quality of surface, and therefore drinking water, following measures must be carried out: · rational and adequate use of fertilizers; · optimal use of protective equipment; · intensive channeling urban areas and settlements; · proper construction and siting landfills; · reduction of emissions from industry; · planning of green areas; · proper use of technology in agricultural production (land cultivation, land fragmentation, directional winds, relationships and waste disposal); · prohibition of discharges of waste water without treatment; · construction of a wastewater treatment plant; · regular control by the inspection and the others professional services in all phases and stages of various human activities. The results obtained during the research can be beneficial for everyone involved in assessing the level of environmental improvement, protection water and health protection.The research is of great public interest and has undoubted theoretical and practical significance

Up-conversion luminescence of GdVO4:Nd3+/Er3+ and GdVO4:Nd3+/Ho3+ T phosphors under 808 nm excitation

All authors acknowledge to the COST Action CM1403: The European upconversion network - from the design of photon-upconverting nanomaterials to biomedical applications (2014–2018). The authors from the University of Belgrade acknowledge the financial support of the Ministry of Education, Science and Technological Development of the Republic of Serbia (Project Nos. 45020 and 172056 ). K. S. acknowledges the Latvian National Research Program IMIS2 (Grant No. 302/2012 ). T. G. acknowledges the ERDF PostDoc project No. 1.1.1.2/VIAA/1/16/215 ( 1.1.1.2/16/I/001 ).In recent years, there exists a tendency in research of up-conversion materials to shift excitation from 980 nm to shorter wavelengths. Here, in order to produce up-conversion luminescence emission of GdVO4-based materials under 808 nm excitation, polycrystalline powders of GdVO4:Er3+/Nd3+ and GdVO4:Ho3+/Nd3+ were successfully prepared by a high-temperature solid-state reaction technique. The prepared powders were highly crystalline with a single-phase zircon-type GdVO4 structure and consisted of micrometer-sized irregular spherical particles (2–6 μm in diameter). In all studied samples, visible up-conversion luminescence was successfully achieved under 808 nm illumination. Near-infrared pumping produced emission bands in the green, yellow-orange and green regions of the visible spectrum. The bands in the green and red regions of GdVO4: Er3+/Nd3+ as well as GdVO4:Ho3+/Nd3+ were, respectively, characteristic of Er3+ and Ho3+ ions. The dominant band originating from the 4G7/2 → 4I11/2 transition in Nd3+ ions was observed around 597 nm in all samples.COST Action CM1403 (2014–2018); Ministry of Education, Science and Technological Development of the Republic of Serbia (Project Nos. 45020 and 172056 ); Latvian National Research Program IMIS2 (Grant No. 302/2012 ); ERDF PostDoc project No. 1.1.1.2/VIAA/1/16/215 ( 1.1.1.2/16/I/001 ); Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART

A comparative study of photocatalytically active nanocrystalline tetragonal T zyrcon- type and monoclinic scheelite-type bismuth vanadate

The authors from Vinča Institute of Nuclear Sciences acknowledge the financial support of the Ministry of Education, Science and Technological Development of the Republic of Serbia (Project no: 172056 ). The work of K. Smits was supported by Latvian National Research Program IMIS2 (Grant no. 302/2012 ).Monoclinic scheelite-type BiVO4 is currently considered as one of the most promising non-titania photocatalysts, wheras tetragonal zircon-type BiVO4 is still poorly understood. Herein, a new and simple synthetic approach was applied and nanostructured single-phase zircon-type BiVO4 was successfully prepared by a controllable ethylene-glycol colloidal route. In addition, nanostructured monoclinic scheelite-type BiVO4 powders were also fabricated through annealing of the as-prepared samples. A comparative study of the two BiVO4 polymorphs was conducted and it turned out that the novel synthetic approach had a significant impact on porosity and photocatalytic performance of zircon-structured BiVO4. All the prepared materials, as-prepared and annealed, were mesoporous, while measured values of specific surface area of some zircon-structured samples (∼34 m2/g) were ∼7 times higher than those reported thus far for this phase. Interestingly, for the first time, zircon-type BiVO4, previously considered to be a poor photocatalyst, exhibited a better overall performance in degradation of methyl orange compared to monoclinic scheelite-type BiVO4. Hence, it could be expected that the here-presented synthesis and observations will both arouse interest in scarcely studied tetragonal zircon-type BiVO4 and facilitate as well as speed up further research of its properties.Ministry of Education, Science and Technological Development of the Republic of Serbia (Project no: 172056 ); Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART

Supplementary data for the article: Savić, T. D.; Ćomor, M. I.; Abazović, N. D.; Šaponjić, Z. V.; Marinović-Cincović, M. T.; Veljković, D. Ž.; Zarić, S. D.; Janković, I. A. Anatase Nanoparticles Surface Modified with Fused Ring Salicylate-Type Ligands (1-Hydroxy-2-Naphthoic Acids): A Combined DFT and Experimental Study. Journal of Alloys and Compounds 2015, 630, 226–235. https://doi.org/10.1016/j.jallcom.2015.01.041

Supplementary material for: [https://doi.org/10.1016/j.jallcom.2015.01.041]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/1661

Novi način formiranja kompozitnih prevlaka

Ni/WC and Cu/WC composite coatings were obtained in two steps. The first step consists of the inert WC particles deposition from the aqueous solution onto steel surface by means of a micro-pipette and covering by the dilute aqueous Nafion solution. The second step is the electrochemical metal deposition from commercial baths in constant current regimes. As result, compact composite coatings were obtained with the different amounts of WC in the deposit in the entire range between a part of a percent up to a few tenths of the percent. The new two-steps method for the formation of the composite coatings renders a very homogeneous distribution of inert WC particles in the deposit and exactly defined chemical composition in each part of the coating Several advantages of splitting the process into two steps are found: the electrolyte for the metal deposition stays clean, no stirring is necessary and it is possible to deposit homogeneously large particles at desired parts of the surface. It is also possible to form multi-layer composite deposits as well as composite foils.Kompozitne prevlake nikal-volframkarbid Ni/WC i bakar-volframkarbid Cu/WC dobijene su iz dva stupnja. Prvi stupanj obuhvata nanošenje inertnih čestica volframkarbida (WC) iz vodenog rastvora mikropipetom na čeličnu površinu. Preko nanetih čestica sipan je razblažen vodeni rastvor nafiona. Drugi stupanj predstavlja elektrohemijsko taloženje metala iz komercijalnih elektrolita pri konstantnom strujnom režimu. Kao rezultat dobijene su kompaktne kompozitne prevlake, gde je količinu WC moguće menjati od dela procenta do nekoliko desetina procenata. Korišćenjem dvostepenog formiranja kompozitnih prevlaka dobija se homogena raspodela inertnih čestica u prevlaci i tačno definisan hemijski sastav u svakom delu prevlake. Prednost ovakvog formiranja kompozitnih materijala je velika, jer ne dolazi do prljanja elektrolita za taloženje osnovnog metala, nije potrebno nikakvo mešanje elektrolita, a moguće je ugraditi velike i teške čestice i to na tačno definisanim mestima na površini. Takođe, moguće je formirati i višeslojne kompozitne prevlake, kao i kompozitne folije

Eccentric binaries: Tidal flows and periastron events

A number of binary systems present evidence of enhanced activity around periastron passage, suggesting a connection between tidal interactions and these periastron effects. The aim of this investigation is to study the time-dependent response of a star's surface as it is perturbed by a binary companion. We derive expressions for the rate of dissipation, $\dot{E}$, of the kinetic energy by the viscous flows driven by tidal interactions on the surface layer. The method is tested by comparing the results from a grid of model calculations with the analytical predictions of Hut (1981) and the synchronization timescales of Zahn (1977, 2008). Our results for the orbital cycle averaged energy dissipation on orbital separation are consistent with those of Hut for model binaries with orbital separations at periastron >8 stellar radii. The model also reproduces the predicted pseudo-synchronization angular velocity for moderate eccentricities and the same scaling of synchronization timescales for circular orbits with separation as given by Zahn. The computations gives the distribution of $\dot{E}$ over the stellar surface, and show that it is generally concentrated at the equatorial latitude, with maxima generally located around four clearly defined longitudes, corresponding to the fastest azimuthal velocity perturbations. Maximum amplitudes occur around periastron passage or slightly thereafter for supersynchronously rotating stars. In very eccentric binaries, the distribution of $\dot{E}$ over the surface changes significantly as a function of orbital phase, with small spatial structures appearing after periastron. An exploratory calculation for the highly eccentric binary system delta Sco suggests that the sudden and large amplitude variations in surface properties around periastron may contribute toward the activity observed around this orbital phase.Comment: Accepted for publication in A&