Brownfield investments as possibility of revitalization and sustainability of locations

Investments for revitalization of locations through Brownfield investments provide an opportunity to establish and test new sustainable development practices. The economic advantage of analyzed Brownfield investments is that there are already certain capacities and infrastructure in a specific location. The research found that the funds invested in the cleaning of the terrain, waste treatment with the so-called. "Wild" landfills, in adaptation of buildings, arrangement of green areas, improvement of infrastructure and the like, have economic and financial justification. In addition, a number of other qualitative effects of general interest have been highlighted. The effects of this investment are considered from socioeconomic, environmental and other aspects, as well as to the development of local economy and environmental protection. In addition to the ecological and economic aspects of investing in Brownfield investment, special attention should be paid to risk management and social aspects of local sustainable development

Evaluation of sealing ability of chemically softened gutta-percha technique

Introduction. Obturation of the root canal is the final phase of endodontic therapy and it is usually used to assess the quality of endodontic treatment. The objective of this study was to examine the quality of apical sealing of the root canal after application of chemically softened gutta-percha. Material and Methods. Thirty extracted single rooted and multi rooted teeth, divided into two groups according to the material for obturation, were used in the study. After root canal instrumentation using step-back technique, obturation was completed using chemically softened gutta-percha and AH Plus and Apexit paste. The effect of apical sealing was assessed regarding the type of material used for the obturation. After obturation, teeth were coated with two coats of varnish and immersed in 50% solution of silver nitrate for twelve hours, and then longitudinally cut using diamond disc. Linear dye penetration was observed using light microscope and twenty five times magnification. The apical leakage was calculated using the measuring scale, previously mounted on microscope lens. Results. The results showed that the average penetration of silver nitrate in single rooted teeth obturated with the AH Plus paste was 132.8 μm, while in teeth obturated with Apexit, it was 148.6 μm. The difference was not statistically significant. Apical leakage in multi rooted teeth obturated with softened gutta-percha and AH Plus paste was 117.3 μm while in teeth obturated with Apexit, it was 158.5 μm. The difference was statistically significant. Conclusion. The lowest dye penetration in the apical portion of the canal was observed in multi rooted teeth obturated with AH Plus paste and the highest penetration of silver nitrate was in multi rooted teeth obturated with Apexit paste

Synthesis and characterisation of tin and tungsten sulfide powders for application in tribological materials

U doktorskoj disertaciji su prikazani postupci sinteze prahova sulfida kalaja i volframa za primenu u tribološkim materijalima određivanjem optimalnih parametara procesa sinteze na osnovu rezultata termodinamičkog modelovanja primenom softverskog paketa HSC Chemistry® verzija 9.9.2.3. Upotreba termodinamičkog predviđanja u optimizaciji procesa sinteze je primenjena u cilju dobijanja unapređenog načina sinteze sulfida kalaja i volframa sa tehnološki optimalnim brojem operacija, što doprinosi pojednostavljenju postupka i uštedi energije. Proces sinteze je dodatno optimizovan variranjem količine i sastava polaznih materijala, kao i osnovnih procesnih parametara (temperatura i trajanje procesa sinteze). Takođe je izvršen odabir adekvatnog aditiva radi povećanja efikasnosti procesa sinteze, čiji je pozitivan uticaj potvrđen eksperimentalnim rezultatima. Pored toga, proces sinteze sufida kalaja je okarakterisan metodom termičke analize, simultanom diferencijalnom skenirajućom kalorimetrijom i termogravimetrijskom analizom (DSC – TGA). U okviru doktorske disertacije za potrebe sinteze sulfida volframa izvršena je i sinteza oksidnog prekursora metodom ultrazvučnog sprej raspršivanja. Nakon procesa sinteze izvršena je karakterizacija sintetisanih prahova različitim instrumentalnim metodama. Karakterizacija sintetisanih prahova je obuhvatila analizu hemijskog sastava optičkom emisionom spektroskopijom sa indukovano spregnutom plazmom (ICP - OES), određivanje faznog sastava i stepena kristalizacije rendgenskom difrakcionom analizom (XRD) sa Rietveldovom metodom pomoću Powder Cell i RIFRANE® programa, ispitivanje morfologije kao i elementalnog sastava skenirajućom elektronskom mikroskopijom sa energodisperzionom analizom (SEM - EDS). Ova doktorska disertacija je urađena u okviru realizacije projekta tehnološkog razvoja koje je finansiralo Ministarstvo prosvete, nauke i tehnološkog razvoja Republike Srbije, evidencioni broj 34033 ”Inovativna sinergija nus-produkata, minimizacije otpada i čistije proizvodnje u metalurgiji” (2011-u toku).This PhD thesis presents the process of synthesis of tin and tungsten sulfides powders for application in tribological materials by determining the optimal parameters of the synthesis process based on the results of the thermodynamic modeling. The thermodynamic modeling of the synthesis process was determined using HSC Chemistry® software modelling package, version 9.9.2.3. The thermodynamic modeling was applied in order to obtain an improved method of tin and tungsten sulfides synthesis with a technologically optimal number of operations, which contributes to the simplification of the process and energy savings. Further optimization of the synthesis process was done by varying quantity and composition of the starting materials for synthesis, as well as the basic process parameters (temperature, duration of the process of synthesis). The selection of adequate additives for process efficiency increase was also investigated. In addition, the synthesis process of tin sulfides was also characterized by the thermal analysis method, simultaneous differential scanning calorimetry and thermogravimetry (DSC-TGA). As a part of this doctoral dissertation, the synthesis of oxide precursor for tungsten sulfide synthesis was carried out by using the ultrasonic spray pyrolisis method. After the synthesis process, the characterization of powders with different instrumental methods was performed. The characterization of the synthesized powders included analysis of chemical composition by inductively coupled plasma optical emission spectroscopy (ICP - OES), phase composition identification and degree of crystallinity were analysed by X-ray diffraction (XRD) by employing the Rietveld method with the help of PowderCell Software and the RIFRANE® program and examination of morphology, as well as elemental composition by scanning electron microscopy with energy-dispersive spectroscopy (SEM - EDS). This PhD thesis is part of the technological development project funded by the Ministry of Education, Science and Technological Development of the Republic of Serbia, No. 34033 ”Innovative synergy of by-products, waste minimization and clean technologies in metallurgy” (2011-in progress)

Sintering process optimization for Cu-Al2O3 powders synthesized by novel method

This paper presents sintered materials for use as contacts produced via novel synthesis method of starting powders by combination of explored conventional routes of thermochemical synthesis and mechanical alloying. Starting raw materials for powder synthesis by thermochemical route were soluble salts, nitrates of copper and aluminum of p.a. quality, dissolved in distilled water (50wt.% solution) in suitable ratio for final powder to contain 50wt.% of Al2O3 in structure. Nitrate solution was spray dried and subjected to heat treatment (900 ºC/1h). Obtained oxides were reduced in hydrogen atmosphere (flow rate 20L/h at 350 °C for 1h) in order to obtain composite of Cu-Al2O3. Produced powders were used for mechanical alloying of atomized copper (5h, 300 min-1). Final amount of alumina Al2O3 in composite powder were 1, 1.5 and 2 wt.%. After mechanical alloying obtained powders were compacted by a uniaxial pressing (8×32×3mm, 500 kN). Sintering of samples was performed in hydrogen atmosphere in isothermal conditions at five different temperatures in the range from 725-925 °C for 15 to 120 min. Results of characterization show, that increase of Al2O3 content has more noticeable effect on the electrical conductivity and hardness than sintering temperature and time. With increase of Al2O3 from 1 to 1.5 wt.% there is a slight decrease in both investigated properties, while with increase up to 2 wt.% Al2O3 significant decrease in electrical conductivity and hardness of sintered samples is observed. According to achieved results optimum sintering parameters for composite materials produced by novel synthesis method based on copper with dispersed 1% Al2O3 are 875 ºC/60 min. Based on the achieved results, this method provides production of contact materials with good combination of electrical and mechanical properties, but with estimated lower production costs

Economic model of raising sour cherry plantations on technically recultivated land area

The Experiences so far in the world and in the Republic of Serbia show that it is possible to create new agricultural, forest, recreational, landscape, and other systems through reclamation. Biological measures include the application of agricultural and forest reclamation, which contribute to the stability and maintenance of reclaimed areas, but are much more important from the aspect of spatial revitalization and the establishment of natural biocenoses. The need for land reclamation in Serbia is especially pronounced in the surface exploitation of coal, primarily in the Kolubara and Kostolac coal lignite basin. Based on data from practice and technical-technological norms, in this paper an economic model of investing in raising and exploiting cherry orchards on a technically recultivated land area at the location of a former coal mine in the western part of Serbia was compiled. The aim of the research is to determine the amounts and reach a solution to some questions that are more important for the investor, such as: What is the upper limit of investing financial resources? With what degree of interest and within what period can the invested capital in the investment be returned, etc.? By determining the indicators of return value, net present value, internal interest rate and others, the economic justification of the investment was assessed. Input-output parameters and indicators of economic justification were made for one hectare of sour cherry orchard area, with a cultivation period of three years and an exploitation period of 15 years. Investments in the establishment and cultivation of sour cherry orchards are set at 7,800 €/ha. The average annual net profit from sour cherry production is 2,800 €/ha. With an interest rate of 8%, the net present value of sour cherry orchards is 16,168 €/ha, and the yield value is 23,968 €/ha. The accumulation rate is 36%. The capital invested in raising sour cherry orchards can be returned in the third year, which is a much shorter period compared to the period of exploitation of orchards. By applying appropriate criteria for making an assessment, based on established economic indicators, such a project is economically justified. Opportunities, weaknesses, threats and potential risks to the economic viability of the reclaimed area were considered. From the aspect of the wider environment and general interests, an analysis of the relationship between benefits and costs, as well as potential qualitative environmental, social and economic external effects

Formation of the separation layer in the production of tools by electroforming

U ovom raduje optimizovana tehnika dobijanja razdelnog sloja u procesu dobijanja alata za oblikovanje plastičnih masa postupkom elektroformiranja. Cilj je bio da se dobije što tanji sloja koji najmanje utiče na tačnost reprodukovane kopije. Ispitane su dve tehnike dobijanja razdelnog sloja i to: hemijska pasivacija u 2% bihromatu i nanošenje koloidnog sloja u 5% rastvoru albumina u etanolu. Dobijeni su zadovoljavajući rezultati, jer su dobijene kopije sa tačnošću od oko 50 nm u odnosu na model na kome se obavlja taloženje.The procedure for the formation of the separation layer in the production of tools by electroforming is optimized. The goal was to make very thin layer in order to achieve high precision in reproducing of the model. Two techniques for preparation of the separation layer were investigated chemical passivation in 2% bichromate solution and deposition of the colloid layer in 5% solution of albumin in ethanol. The precision of the copies obtained in this work was about 50 nm, what is considered to be acceptable

Phenotypes and genotypes of macrolide-resistant Streptococcus pneumoniae in Serbia

Although macrolides are widely used for treating pneumococcal infections, an increase in macrolide resistance might compromise their use. The objective of this study was to determine the prevalence of macrolide-resistant phenotypes and genotypes in macrolide-resistant S. pneumoniae isolates in Serbia. A total of 228 macrolide-resistant strains isolated during the period of 2009-2012, were analyzed. Macrolide resistance phenotypes were determined by a double disk diffusion test. The presence of macrolide resistance genes was detected by PCR. Antibiotics susceptibilities were tested using the VITEK2 system and E test. Among the examined isolates, the MLSB phenotype which is linked to the presence of the erm(B) gene dominated (83.3%), while the mef(A) gene which is associated with the M phenotype, was identified in 16.7% isolates. Over 40% of isolates expressed co-resistance to penicillin. A multiple-resistant pattern was found in 36.4% strains, more frequently in children. However, all strains were susceptible to telithromycin, vancomycin, linezolid, fluoroquinolones and rifampicin. [Projekat Ministarstva nauke Republike Srbije, br. 175039

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

Formation of the separation layer in the production of tools by electroforming

U ovom raduje optimizovana tehnika dobijanja razdelnog sloja u procesu dobijanja alata za oblikovanje plastičnih masa postupkom elektroformiranja. Cilj je bio da se dobije što tanji sloja koji najmanje utiče na tačnost reprodukovane kopije. Ispitane su dve tehnike dobijanja razdelnog sloja i to: hemijska pasivacija u 2% bihromatu i nanošenje koloidnog sloja u 5% rastvoru albumina u etanolu. Dobijeni su zadovoljavajući rezultati, jer su dobijene kopije sa tačnošću od oko 50 nm u odnosu na model na kome se obavlja taloženje.The procedure for the formation of the separation layer in the production of tools by electroforming is optimized. The goal was to make very thin layer in order to achieve high precision in reproducing of the model. Two techniques for preparation of the separation layer were investigated chemical passivation in 2% bichromate solution and deposition of the colloid layer in 5% solution of albumin in ethanol. The precision of the copies obtained in this work was about 50 nm, what is considered to be acceptable

Exploitation Properties of Ni-Pd/Al2O3 Catalyst Supported on Ceramic Foam

The goal of this research was to examine exploitation properties of Ni-Pd/Al2O3 catalyst supported on α-Al2O3 based foam in the dry methane reforming. The catalyst was prepared by using aerosol method. Chloride precursors for Ni and Pd were reduced by hydrogen at low temperature of 533 K, without previous calcination. The reforming experiment was performed for 3 h, with standing time of 1 h for each of the following temperatures: 873, 973 and 1023 K. Conclusions on selectivity, catalytic activity and stability were made on the basis of CO and H2 yields