Thermodinamic modelling of Pb/Ag Jarosite sulfidation for valuable metals recovery

In this paper thermodynamic modeling of sulfidation of non-standard Pb/Ag - Jarosite is shown, in order to propose optimal technological process for valuable metals recovery. Given the current state of natural resources, demand and consumption, sustainable production of critical metals, especially technological metals, is focus of this research. Neutral leaching residue, Pb/Ag - Jarosite, as a primary zinc production by-product is usually disposed at landfills, despite the fact that contains recyclable base (Zn, Pb, Cu), precious (Ag) and technological, critical metals (In, Ge, Ga). Thermodynamic data for detailed sulfidation behavior of technological metals contained in Pb/Ag - Jarosite were calculated using HSC Chemistry Software v. 9.0 in order to recommend optimal recycling process conditions. The main objectives were determination of temperature effect, input material/sulfidation agent ratio and modeling of phase stability diagrams of chosen technological metal sulfides. Synergetic metallurgy activities including utilization of primary and secondary raw materials can be result of this process modeling

Production of technology metals from waste electronics

The rising criticality of technologically inevitably metals and the continuous growth of the waste electronics promote a scientific need for development of innovative recycling process, both efficient and selective. Experimental results showed primarily that by pyrometallurgical treatment it is difficult to achieve selectivity, and secondary that the distribution of metals in melting products is too complicated, deviating from the experiential and expected. Therefore, application of an integral pyro - hydrometallurgical treatment is suggested for improved raw materials efficiency. Successful implementation of the developed state-of-art technological process, guarantee more efficient approach to recycling processes, production of new materials which supports the concepts of sustainable development and cleaner production. Proposed technological solution is applicable in industry with relatively low investments compared to expected revenues, allowing companies to become competitive in the regional market and beyond, which is particularly important for small and medium enterprises with lower operating capacities. Techno-economic justification and integral pyro - hydrometallurgical process for waste electronics recycling is presented. This paper explains measures for the further development of the recycling industry as a part of circular economy strategy in Serbia

Elisa and HPLC analyses of deoxynivalenol in maize and wheat

Deoxynivalenol (DON) is a part of the family of mycotoxins called trichothecenes which are produced by a number of different Fusarium mold species. The presence of DON in 25 wheat and 25 maize samples was examined by Enzyme Linked Immunosorbent Assay (ELISA) and High Performance Liquid Chromatography (HPLC) methods. The presence of DON was detected and determined in 5 (20%) maize and 6 (25%) wheat samples by both of the methods. Correlation between ELISA and HPLC results was established, with the correlation coefficients (r) of 0.9691 and 0.9735 for wheat and maize samples, respectively. The results obtained by ELISA method were significantly higher than those obtained by HPLC method. This fact can be explained by the presence of conjugated or masked mycotoxins in the samples, especially DON-3-glucoside (DON-3-Glc), which could not be determined by HPLC method due to the lack of external standards. Contrary to this, being insufficiently selective towards masked DON, ELISA method measures total DON content of a sample. According to the obtained results, ELISA can be used as a reliable screening method, but the confirmation of positive results must be done by HPLC method

Screening of mycotoxins in animal feed from the region of Vojvodina

This paper shows the results of screening of mycotoxins in animal feed originating from the region of Vojvodina. Permanent screening is needed on all levels of production and storage, as well as the use of known methods to reduce mould contamination or toxin content in feedstuffs and feed. A total of 56 representative samples were collected from feed companies from the region of Vojvodina. Samples were collected during February 2009. The collected samples included 41 samples of feedstuffs (soybean, soybean meal, soybean grits, soybean cake, maize, sunflower meal, barley, wheat feed flour, rapeseed meal, dehydrated sugar beet pulps, alfalfa meal, yeast, dried whey, fish meal, meat-bone meal) and 15 samples of complete feedingstuffs. The amounts of aflatoxins, ochratoxin A, zearalenone, fumonisin and deoxynivalenol were determined. Screening method for the analysis was done using Neogen Veratox® testing kits. The test itself is a competitive direct enzyme-linked immunosorbent assay (CD-ELISA). Mycotoxins were present in 71.4% of the samples, but the values determined were below the maximum allowed limits for both Serbian and EC reference values. Zearalenone was found with the highest incidence (57.1% of samples), followed by ochratoxin A (37.5%), fumonisin (33.9%), deoxynivalenol (14.3%) and aflatoxins (3.6%)

Vitamin D status in mothers with pre-eclampsia and their infants: a case-control study from Serbia, a country without a vitamin D fortification policy

Objective: The objective of the present study was to determine if vitamin D intake and status are associated with pre-eclampsia in a country without a vitamin D fortification policy. Design: A case-control study of pregnancies with (case) and without (control) pre-eclampsia was conducted from January to April when UVB is minimal. Maternal and cord blood obtained at delivery were measured for plasma 25-hydroxycholecalciferol (25-OH-D-3), 3-epimer of 25-OH-D-3 (3-epi-25-OH-D-3) and 24,25-dihydroxycholecalciferol (24,25-(OH)(2)D-3) by LC-MS/MS and maternal 1,25-dihydroxyvitamin D (1,25-(OH) 2D). Differences between groups were tested with ANOVA and Bonferroni post hoc tests (P lt 0.05). Setting: Clinical Center of Serbia. Subjects: Pregnant women with and without pre-eclampsia (n 60) and their infants. Results: Exogenous vitamin D intake (0.95-16.25 mu g/d (38-650 IU/d)) was not significantly different between groups. Women with pre-eclampsia delivered infants at an earlier gestational age and had significantly lower mean total plasma 25-hydroxyvitamin D (25-OH-D; case: 11.2 (SD 5.1); control: 16.1 (SD 5.7) ng/ml; P=0.0006), 25-OH-D-3 (case: 10.0 (SD 4.9); control: 14.2 (SD 5.8) ng/ml; P=0.002), 3-epi-25-OH-D-3 (case: 0.5 (SD 0.2); control: 0.7 (SD 0.2) ng/ml; P=0.0007) and 1,25-(OH)(2)D (case: 56.5 (SD 26.6); control: 81.0 (SD 25.7) pg/ml; P=0.018), while 24,25-(OH)(2)D-3 was not different between groups. Infants did not differ in total plasma 25-OH-D, 25-OH-D-3, 3-epi-25-OH-D-3 and 24,25-(OH)(2)D-3, but the mean proportion of 3-epi-25-OH-D-3 was higher in the infant case group (case: 7.9 (SD 1.1); control: 7.0 (SD 1.4) % of total 25-OH-D-3; P=0.005). Conclusions: A high prevalence of vitamin D deficiency, as defined by plasma 25-OH-D lt 12 ng/ml, was observed in 47 % of all mothers and 77 % of all infants. These data underscore the need for prenatal vitamin D supplementation and a food fortification policy in Serbia

Supplementary material for the article: Djekic-Ivankovic, M.; Weiler, H.; Jones, G.; Kaufmann, M.; Kaludjerovic, J.; Aleksic-Velickovic, V.; Mandić, L. M.; Glibetic, M. Vitamin D Status in Mothers with Pre-Eclampsia and Their Infants: A Case-Control Study from Serbia, a Country without a Vitamin D Fortification Policy. Public Health Nutrition 2017, 20 (10), 1825–1835. https://doi.org/10.1017/S1368980016000409

Supplementary material for: [https://doi.org/10.1017/S1368980016000409]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2161

PRESENCE OF AFLATOXINS IN CEREALS FROM SERBIA

ABSTRACT: Aflatoxins (AFs), one of the most toxic and the strongest natural carcinogens can be found in a variety of food commodities, including cereals. For that purpose, the aim of this study was to investigate occurrence of AFs (AFB1, AFG1, AFB2 and AFG2) in 130 cereal samples

Brašno - Kruh '15

Proceedings contains 28 original research articles presented at 8th International Congress Flour – Bread ’15 and 10th Croatian Congress of Cereal Technologists Brašno – Kruh ’1

Production of technology metals from waste electronics

The rising criticality of technologically inevitably metals and the continuous growth of the waste electronics promote a scientific need for development of innovative recycling process, both efficient and selective. Experimental results showed primarily that by pyrometallurgical treatment it is difficult to achieve selectivity, and secondary that the distribution of metals in melting products is too complicated, deviating from the experiential and expected. Therefore, application of an integral pyro - hydrometallurgical treatment is suggested for improved raw materials efficiency. Successful implementation of the developed state-of-art technological process, guarantee more efficient approach to recycling processes, production of new materials which supports the concepts of sustainable development and cleaner production. Proposed technological solution is applicable in industry with relatively low investments compared to expected revenues, allowing companies to become competitive in the regional market and beyond, which is particularly important for small and medium enterprises with lower operating capacities. Techno-economic justification and integral pyro - hydrometallurgical process for waste electronics recycling is presented. This paper explains measures for the further development of the recycling industry as a part of circular economy strategy in Serbia

Effect of Temperature on S32750 Duplex Steel Welded Joint Impact Toughness

The search for alternative materials that can be used for parts of aircraft hydraulic systems has led to the idea of applying S32750 duplex steel for this purpose. This steel is mainly used in the oil and gas, chemical, and food industries. The reasons for this lie in this material’s exceptional welding, mechanical, and corrosion resistance properties. In order to verify this material’s suitability for aircraft engineering applications, it is necessary to investigate its behaviour at various temperatures since aircrafts operate at a wide range of temperatures. For this reason, the effect of temperatures in the range from +20 °C to −80 °C on impact toughness was investigated in the case of S32750 duplex steel and its welded joints. Testing was performed using an instrumented pendulum to obtain force–time and energy–time diagrams, which allowed for more detailed assessment of the effect of testing temperature on total impact energy and its components of crack initiation energy and crack propagation energy. Testing was performed on standard Charpy specimens extracted from base metal (BM), welded metal (WM), and the heat-affected zone (HAZ). The results of these tests indicated high values of both crack initiation and propagation energies at room temperature for all the zones (BM, WM, and HAZ) and sufficient levels of crack propagation and total impact energies above −50 °C. In addition, fractography was conducted through optical microscopy (OM) and scanning electron microscopy (SEM), indicating ductile vs. cleavage fracture surface areas, which corresponded well with the impact toughness values. The results of this research confirm that the use of S32750 duplex steel in the manufacturing of aircraft hydraulic systems has considerable potential, and future work should confirm this