Study of the spatial redistribution of the analyte spectral emission in dc arc plasma induced by external oscillating magnetic field

Monochromatic digital imaging technique was developed for studying the spatial emission intensity distribution of atmospheric pressure dc arc plasma with aerosol supply. Arc plasma was imposed to external oscillating magnetic fields of strengths up to 12 mT and frequency of 50 Hz. This plasma was studied in a laterally resolved manner and at selected observation heights. The intensity enhancement and spatial redistribution of the analyte emission was evaluated and compared to the steady state plasma. The intensity enhancements were correlated with the attained speeds of plasma core movement. Spatial regions in the arc plasma with maximal emission enhancement are identified and clarified. The effect of the electrode polarity was also investigated.Physical chemistry 2008 : 9th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 200

Cesium removal from aqueous solution by natural mineral clinoptilolite

The aim of this study was to investigate the Cs+ ions sorption on natural minerals clinoptilolite. The analysis of clinoptilolite and clinoptilolite with adsorbed Cs+ ion was conducted by X-ray diffraction, scanning electron microscopy, X-ray fluorescence, and gamma spectrometry. The specific activity of naturally occurring radionuclides in clinoptilolite was determined by gamma spectrometry by using the HPGe semiconductor detector. Obtained activity concentrations ranged from 49 Bq/kg to 810 Bq/kg for K-40, 5.7 Bq/kg to 10 Bq/kg for U-238, 5.8 Bq/kg to 70 Bq/kg for Th-232(Ac-228), and the presence of artificial radionuclides was not detected (Cs-137 lt 0.02 Bq/kg). The study of the thermal decomposition of raw clinoptilolite and Cs adsorbed clinoptilolite by differential thermal analysis is presented in this paper. The activation energy of the reaction phase transformation of raw clinoptilolite is 156.7 kJ/mol, while Cs adsorbed clinoptilolite is 121.7 kJ/mol. The lower value of activation energy reaction of the phase transformation Cs adsorbed clinoptilolite indicates that Cs which is adsorbed destabilizes the crystal structure of clinoptilolite and thus facilitates the transition to the amorphous state

Supplementary data for the article: Pavlović, R. Z.; Bjelaković, M. S.; Milić, D. Diamide-Based Fullerosteroidal and Disteroidal [2] Rotaxanes: Solvent-Induced Macrocycle Translocation and/or Unthreading. RSC Advances 2016, 6 (43), 37246–37253. https://doi.org/10.1039/c6ra03872g

Supplementary material for: [https://doi.org/10.1039/c6ra03872g]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/1921

Activity of antioxidative defense enzymes in the blood of patients with liver echinococcosis

Background/Aim. Chronic echinococcocal disease is the parasite human disease caused by the penetration of larval (asexual) stages of the canine tapeworm (Echinococcus granulosus) in the liver of humans. After the penetration of the parasite, the host organism react by activating complement- depending immune response. The aim of this study was to elucidate the influence of larval form of Echinococcus granulosus in the liver on the activity of antioxidative defense enzymes in the blood of patients before and after the surgical intervention. Methods. We investigated the activity of antioxidative defense enzymes: copper/zinc containing superoxide dismutase (CuZn SOD), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione reductase (GR) and glutathione-S-transferase (GST) in the blood of patients before and after the surgical intervention in respect to the controls, clinically healthy persons. Results. Our results showed that the activity of the GSH-Px was significantly decreased in the plasma of the patients with echinocococal disease before the surgery in respect to the controls. The activity of GST was significantly higher in the blood of the patients after the surgery in comparison to the controls. Conclusion. Chronic liver echinoccocal disease caused significant changes of some antioxidative defense enzymes, first of all Se-dependent enzyme GSH-Px, which could be a suitabile biomarker in the biochemical evaluation of the disease. This work represents a first comprehensive study of the activity of antioxidative defense enzymes in cronic liver echinococcocosis in the patients before and after the surgical intervention in respect to the clinically healthy persons

Structural and electrical properties of geopolymer materials based on different precursors (kaolin, bentonite and diatomite)

Geopolymers (GP) were successfully synthesized from metabentonite (MB), metadiatomite (MD) and metakaolinite (MK). Characterization of their phase structure and microstructure was performed by XRD, FTIR, SEM/EDX methods. A SEM micrograph of GPMD shows a homogeneous surface with some longitudinal cavities in the gel, and it is significantly different from the micrographs of the other two geopolymer samples, GPMB and GPMK. A considerable amount of unreacted particles, as well as the presence of pores in the geopolymer matrix of GPMK and GPMD, indicate an incomplete reaction in the system. Aluminosilicate inorganic polymers, geopolymers, are quasi solid electrolytes which possess a high electrical conductivity at room temperature in relation to materials of similar chemical composi-tion. The highest conductivity was found for the sample obtained from GPMK, amounting to 2.14 x 10-2 Ω-1cm-1 at 700 oC. The corresponding activation energies of conductivity for this sample amounted to 0.33 eV in the temperature range of 500-700 oC. The geopolymer synthesized from metakaolin has good ionic conductivity values, which recommends it for use as an alternative material for an SOFC (Solid Ox-ide Fuel Cell)

The influence of alumino-silicate matrix composition on surface hydrophobic properties

The purpose of this investigation is to investigate the hydrophobicity of geopolymers, new alumino-silicate materials and the influence of Si/Al ratio on their surface properties. Contact angle measurement (CAM) as reliable indicator of hydrophobicity was determined for synthesized geopolymers using water and ethylene-glycol as reference liquids. Geopolymers were synthesized from various precursors: Kaolin, bentonite and diatomite. Characterization of phase structure and microstructure was performed by XRD, FTIR, SEM/EDX methods. Contact angle measurements confirmed that the geopolymers synthesized from metakaolin are the most porous, which can be explained by the smallest Si/Al ratio. The maximum value of contact angle and free surface energy (110.2 mJ/m2) has been achieved for geopolymer synthesized by diatoms (GPMD). SEM micrograph of GPMD shows a homogeneous surface with some longitudinal cavities in the gel and is significantly different from the micrographs of other two geopolymer samples, GPMB and GPMK

Radionuclides and heavy metals in soil, vegetables, and medicinal plants in suburban areas of the cities of Belgrade and Pancevo, Serbia

The content of radionuclides (K-40 , U-238 , Ra-226 , Th-232, and Cs-137) and heavy metals (As, Cd, Cu, and Pb) was determined in samples of soil, vegetables and medicinal plants collected in the period 2007-2017, from two suburban areas of Belgrade - the municipalities of Palilula and Surcin, and Pancevo - the Dr Josif Pancic Institute for the Study of Medicinal Herbs. During the research period, activity concentration of Cs-137 in soil decreased from 16 Bqkg(-1) to 3.9 Bqkg(-1) (Palilula, Belgrade) and from 18 Bqkg(-1) to 12 Bqkg(-1) (Surcin, Belgrade). Mean activity concentrations of natural radionuclides in the soil were higher than the global average. lkend for heavy metal levels, according to the average concentrations found in the soil, were as follows: Cu >Pb >As >Cd for Palilula, Pb >Cu >As >Cd for Surcin and Dr Josif Pancic Institute, Pancevo. The obtained results indicate that the industrial pollution has no impact on food production in the study area and that the main anthropogenic source of radionuclides and heavy metals in soil are mineral phosphorous fertilizers, often used in agricultural fields

Dinamički rekonfigurabilni upravljački sistem sa promenljivim tokom izvršavanja kinematičkog algoritma

U radu je predstavljen sistem upravljanja otvorene arhitekture koji je implementiran na troosnoj glodalici za obradu drveta koja može raditi i u vertikalnoj i u horizontalnoj konfiguraciji, kao i upravljanje preko digitalnog dvojnika. Razvoj sistema upravljanja putem digitalnog dvojnika motivisan je istraživačkim i edukacionim zahtevima. Razmatrani CNC sistem za obradu drveta je podržan od ekvivalentne virtuelne mašine u sistemu upravljanja kao digitalni dvojnik. Konfigurisana virtuelna mašina se koristi za simulaciju obrade i verifikaciju sistema upravljanja. Prikazan je jedan test predmet koji je obrađen u vertikalnoj i horizontalnoj konfiguraciji da bi se potvrdila efikasnost razvijenih sistema upravljanja koji su zasnovani na LinuxCNC-u