Microbial diversity of an extremely acidic lake Robule and effect of the lake water on oxidation of sulfide minerals

Jezero Robule, formirano u podnožju rudničke raskrivke Oštreljski planir (Rudnik bakra Bor), je nastalo kao posledica rudarskih aktivnosti. Mikrobiološki diverzitet ekstremno kiselog jezera Robule ispitivan je primenom kako klasičnih mikrobioloških metoda (svetlosna mikroskopija i kultivacija na selektivnim podlogama) tako i primenom savremene metode molekularne biologije (analiza polimorfizama terminalnih restrikcionih fragmenata; T-RFLP). Takođe, ispitivan je i potencijal i efikasnost jezerske vode u biološkom luženju mineralnog koncentrata, kao i u bioluženju uzoraka stare flotacijske jalovine Rudnika bakra Bor. Na osnovu dobijenih rezultata oba pristupa potvrđeno je da je mikrobiološki diverzitet vode jezera Robule vrlo ograničen. T-RFLP analizom gena za 16S rRNK umnoženih na osnovu metagenomske DNK su identifikovane svega dve vrste: Acidiphilium cryptum (hemoorganoheterotrof), sa zastupljenošću od ~50 % i Leptospirillum ferrooxidans (hemolitoautotrofna gvožđe-oksidujuće bakterija) čija se zastupljenost kretala oko 40 %, dok je preostalih 10 % terminalnih restrikcionih fragmenata (T-RF) ostalo neidentifikovano. Hemolitoautotrofna gvožđe i sumpor oksidujuće bakterijska vrsta Acidithiobacillus ferrooxidans je identifikovana tek nakon izolovanja na odgovarajućoj selektivnoj podlozi. Analiziran je i mikrobiološki diverzitet uzorka biomase, koja se formirala u obliku tepiha zelene boje u priobalnom području jezera. Svetlosnom mikroskopijom je utvrđeno da osnovu uzorka biomase čine končaste alge, dok je T-RFLP analiza gena 16S rRNK umnoženih na osnovu metagenomske DNK dobijene iz uzorka biomase ukazala na znatno veći mikrobiološki diverzitet u odnosu na analizirani uzorak jezerske vode. Populaciju mikroorganizama u tepihu su činile pretežno heterotrofne acidofilne bakterije, mada su bile prisutne i hemolitoautotrofne bakterije. Najzastupljeniji T-RF su poticali od algi i heterotrofnih bakterija iz rodova Acidocella, Acidiphilium i Sulfobacillus. Prisustvo hemolitoautotrofnih i heterotrofnih acidofilnih bakterija je potvrđeno zasejavanjem uzoraka na selektivne podloge, mada je ovim pristupom uočen manji bakterijski diverzitet. Iz uzoraka jalovine sa deponije raskrivke na selektivnoj podlozi sa gvožđe(II)sulfatom i ekstraktom kvasca su izolovani gvožđe-oksidujući i heteroorganotrofni acidofili, koji učestvuju u stvaranju tzv. kiselih rudničkih voda koje se slivaju u jezero nakon padavina i neprekidno ga obnavljaju. Na osnovu ovih rezultata predložen je i biogeohemijski ciklus gvožđa u jezeru...Lake Robule, is an extremely acidic water body formed at the foot of the overburden Oštreljski planir (the Copper Mine Bor). Microbial diversity of the lake was investigated using both traditional microbiological methods (microscopy and bacterial isolation on selective media) and molecular fingerprinting technique – Terminal Restriction Fragment Length Polymorphism (T-RFLP) method. The Lake’s water potency for and efficacy of bioleaching of mineral concentrate has also been investigated as well as bioleaching of old flotation tailings samples. The results of both approaches confirmed that microbial diversity of the Lake’s water was very restricted, as expected. T-RFLP analysis of 16S rRNA amplified when metagenomic DNA has been used as a target, showed the presence of only two species: Acidiphilium cryptum (hemoorganoheterotrophic bacteria) that represented approximately 50 % of total number of present terminal fragments (T-RFs) and Leptospirillum ferrooxidans (chemolithoautotrophic iron-oxidizing bacteria) that corresponded to ~40 %. Remaining 10 % of T-RFs were not identified. Chemolithoautotrophic iron- and sulfur- oxidizing bacteria Acidithiobacillus ferrooxidans was identified only after its isolation on selective solid media. Microbial diversity of thick, green colored mat, formed in shallow water, was also analyzed. Light microscopy revealed the presence of the green filamentous algae on the surface of the biomass, while T-RFLP analysis of the 16S rRNA genes amplified from metagenomic DNA isolated from the mat revealed significantly higher bacterial diversity when compared to the diversity of the Lake’s surface water. The most abundant T-RFs originated from algae and heterotrophic acidophilic bacteria closely related to genera Acidocella, Acidiphilium and Sulfobacillus. Chemolithoautotrophic and heterotrophic acidophilic bacteria were also detected on selective solid media, but observed diversity was lower. Inoculation of overlay solid media containing ferrous(II)sulfate and yeast extract with soil sample of surrounding overburden resulted in development of iron- oxidizing and heterotrophic acidophilic bacterial colonies. This confirmed that, as a result of metabolic activity of iron-oxidizing bacteria, overburden has continuously been generating acid mine drainage that flows into the lake after rainfall. Based on these results a biogeochemical model of iron circulation in the lake was proposed..

Kapacitet lokalne samouprave da poboljša poslovno okruženje: Dokazi iz Srbije

The aim of this paper is to draw attention on the need to strengthen institutional cooperation between local self-governments and the business community. The paper analyses the ability of socio-economic councils in Serbia, as a part of local governments, to improve the business environment and indicators of social status at the local level. In addition to socio-economic councils, this analysis includes the departments, divisions and offices for local economic development and their responsibilities. The results in the paper has been generated using descriptive statistics, Chi-Square test, t-test and regression analysis, based on the analysis of primary data collected in empirical research on 55 municipalities in Serbia. The fundamental results obtained using the stated analysis is that socio-economic councils have positive impact on the social and economic development in the survived municipalities. Finally, the basic conclusion from the executed research is that size of the municipality is not a limiting factor for the establishment of the socio-economic councils and their functionality.Cilj rada je skrenuti pozornost na potrebu za jačanjem institucionalne suradnje između lokalne samouprave i poslovne zajednice. Rad analizira sposobnost socioekonomskih savjeta u Srbiji, kao sastavnog dijela tijela lokalne samouprave, da unaprijedi poslovno okruženje i indikatore socijalnog statusa na lokalnoj razini. Pored socio-ekonomskih savjeta, analizom su obuhvaćeni odjeli i uredi za lokalni ekonomski razvoj i njihove nadležnosti. Rezultati istraživanja su generirani primjenom deskriptivne statistike, Hi kvadrat testa, t-testa i regresijske analize, a na temelju primarno prikupljenih podataka u empirijskom istraživanju na uzorku od 55 općina u Srbiji. Najznačajniji rezultat dobiven primjenom navedenih analiza je da socio-ekonomski savjeti imaju pozitivan utjecaj na socijalni i ekonomski razvoj u promatranim općinama. Na kraju, osnovni zaključak provedenog istraživanja je da veličina općina nije limitirajući faktor za osnivanje socio-ekonomskih savjeta i njihovu funkcionalnost

Višekriterijska evaluacija pametnih performansi europskih gradova: gospodarski, socijalni i okolišni aspekti

The purpose of the paper is to provide the ranking of Central and Eastern European cities, based on various elements of cities’ smart performance. Our analysis enables the evaluation of social, economic and environmental aspects of urban life that represent the determinants of cities’ competitive profiles and consequently, the positions on the ranking lists. The research is based on the data on perceptions of citizens on different aspects of urban quality, provided by the Eurostat’s Urban Audit Perception Survey. For the assessment of various hierarchically structured indicators of cities’ smart performance, a multi-criteria analysis model is developed, combining the AHP (Analytic Hierarchy Process) for determining the relative importance of criteria and TOPSIS (Technique for Order Preference by Similarity to Ideal Solution) method of ranking. The main finding of the paper implies that direct perceptions of citizens on the overall life satisfaction in the analyzed European cities are not influenced by their smart performance. The comparison of ranks obtained by the constructed multi-criteria model and perceived satisfaction of life indicates a rather weak relation.Svrha rada je rangirati gradove srednje i istočne Europe na temelju različitih elemenata pametnih performansi gradova. Ova analiza omogućuje procjenu društvenih, ekonomskih i ekoloških aspekata urbanog života, koji predstavljaju odrednice konkurentnosti gradova, a time i pozicije na rang listi. Istraživanje se temelji na podacima o percepciji građana o različitim aspektima urbane kvalitete, koje pruža Eurostatova baza Urban Audit Perception Survey. Za procjenu raznih hijerarhijski strukturiranih pokazatelja pametnih performansi gradova, razvijen je višekriterijski model analize koji kombinira metodu Analitički hijerarhijski proces (Analytic Hierarchy Process – AHP) za određivanje relativne važnosti kriterija i TOPSIS (Technique for Order Preference by Similarity to Ideal Solution) metodu rangiranja. Glavni nalaz rada sugerira da izravna percepcija građana o cjelokupnom životnom zadovoljstvu u analiziranim europskim gradovima nije uvjetovana “pametnim” performansama gradova. Usporedba poretka dobivenih konstruiranim višekriterijskim modelom i percipiranog zadovoljstva života ukazuje na njihov prilično slab odno

Urbano zapošljavanje u post-tranzicijskim gospodarstvima: neusklađenost vještina na lokalnom tržištu rada

The paper explores the mismatch between the skills and qualifications required by the labour market and those acquired through education and on-the-job learning. The skill mismatch in transition economies tends to be even more pronounced as the labour markets in these countries are characterized by structural unemployment, affecting both older workers with obsolete skills and the young ones. Employers face poor incentives for investing in workforce skill development, due to the inadequate investment climate and volatile business environment. Transition countries face increasing outward mobility of an educated workforce, loss of human capital, and shortage of workforce in the fields such as ICT, medicine, science and research. The research is based on empirical data generated in a survey on ICT and manufacturing enterprises in the City of Niš, Serbia. The research methodology combines workers\u27 self-assessment method for the skill gap measurement and the competence approach combined with the statistical methods. The findings indicate the presence of a qualification mismatch, in the form of the over-qualification as a dominant irregularity in the analysed labour market. The results of the study are expected to contribute to creating a network of policy instrumentaria that tend to be effective on a sub-national level in addressing the mismatch.Ovaj rad istražuje neusklađenost između vještina i kvalifikacija koje zahtijeva tržište rada i onih koje se stječu obrazovanjem i učenjem na radnom mjestu. Neusklađenost vještina u tranzicijskim gospodarstvima ima tendenciju da bude još izraženija budući da tržišta rada u tim zemljama karakterizira strukturna nezaposlenost, koja istovremeno pogađa i starije radnike sa zastarjelim vještinama i mlade. Poslodavci se suočavaju s lošim poticajima za ulaganje u razvoj vještina radne snage zbog neodgovarajuće investicijske klime i nestabilnog poslovnog okruženja. Zemlje u tranziciji suočavaju se sa sve većom vanjskom mobilnošću obrazovane radne snage, gubitkom ljudskog kapitala i nedostatkom radne snage u područjima kao što su ICT, medicina, znanost i istraživanje. Istraživanje se temelji na empirijskim podacima prikupljenim u anketi o ICT-u i proizvodnim poduzećima u gradu Nišu u Srbiji. Metodologija istraživanja kombinira metodu samoprocjene radnika za mjerenje jaza u vještinama i pristup temeljen na kompetencijama u kombinaciji sa statističkim metodama. Nalazi ukazuju na prisutnost kvalifikacijske neusklađenosti, u vidu prekvalificiranosti za posao kao dominantne nepravilnosti na analiziranom tržištu rada. Očekuje se da će rezultati studije doprinijeti stvaranju mreže političkih instrumenata koji imaju tendenciju da budu učinkoviti na podnacionalnoj razini u rješavanju neusklađenosti

Treatment of Barrett's Esophagus with radiofrequency ablation

Introduction: Barrett’s esophagus (BE) represents the distal esophageal epithelium changes that carry a high risk of developing esophageal adenocarcinoma. One of the most challenging aspects of diagnosing BE by endoscopy is precisely discerning between normal epithelium and BE changes, which is essential for therapy success. The objectives of this study were to compare the success of radio-frequency ablation (RFA) therapy to conservative treatment with proton pump inhibitor (PPI) drugs between the clinical presentation and endoscopy findings of BE at 2, 6, 12, and 24 months after administered therapy. Material and methods: Seventy-five subjects were divided into two groups (RFA and PPI) based on the BE treatment regimen in this case-control study to compare the quality of treatments applied over a 24-month follow-up. Subjects who received RFA therapy were further divided into groups: those who received focal HALO 90 and those who received circumferential HALO 360, based primarily on EGDS findings or endoscopist experience. Results: The results show that using the RFA therapeutic modality in the treatment of BE is more effective (by 94.2% in the second month of follow-up, i.e., by 99% at the final visit after 24 months) than using PPI therapy alone. Re-RFA therapy was given to 15% of the subjects, mostly applied in the same therapeutic modality (HALO 90). Conclusions: Our findings show that RFA and re-RFA therapy have a high efficacy and safety profile, with no registered worsening of histology findings, the occurrence of esophageal adenocarcinoma, or adverse effects of the therapy

Detecting the number of components in a non-stationary signal using the Rényi entropy of its time-frequency distributions

A time-frequency distribution provides many advantages in the analysis of multicomponent non-stationary signals. The simultaneous signal representation with respect to the time and frequency axis defines the signal amplitude, frequency, bandwidth, and the number of components at each time moment. The Rényi entropy, applied to a time-frequency distribution, is shown to be a valuable indicator of the signal complexity. The aim of this paper is to determine which of the treated time-frequency distributions (TFDs) (namely, the Wigner-Ville distribution, the Choi-Williams distribution, and the spectrogram) has the best properties for estimation of the number of components when there is no prior knowledge of the signal. The optimal Rényi entropy parameter α is determined for each TFD. Accordingly, the effects of different time durations, bandwidths and amplitudes of the signal components on the Rényi entropy have been analysed. The concept of a class, when the Rényi entropy is applied to TFDs, is also introduced

Investigation of the optimal technology for copper leaching from old flotation tailings of the copper mine bor (Serbia)

This work aimed to investigate optimal leaching technology for copper extraction from old flotation tailings of the Copper Mine Bor. The leaching degree of copper after leaching with sulphuric acid at 80 °C was 50%, the maximal leaching degree was achieved after 30 minutes. Then, old flotation tailings were leached with adapted moderately thermophilic acidophilic bacteria in a bioreactor at 40 °C. Maximal leaching degree of 84% was achieved after nine days of the experiment. The third leaching experiment was conducted with biogenic lixiviant obtained by bacterial oxidation of the ferrous iron (concentration of Fe3+ 1300 mgL-1, pH 2.14). Biogenic lixiviant with ferric sulphate was then used in the leaching experiment at 80 °C. Maximal leaching degree was 78%, and it was achieved after five minutes. Results of the leaching experiments show that the most efficient technology for copper recovery from the old flotation tailings of the Copper Mine Bor was leaching with biogenic lixiviant

FUZZY MODEL REFERENCE ADAPTIVE CONTROL OF VELOCITY SERVO SYSTEM

The Implementation of fuzzy model reference adaptive control of a velocity servo system is analysed in this paper. Designing the model reference adaptive control (MRAC) and the problem of choosing adaptation gain is considered. Tuning the adaptation gain by fuzzy logic subsystem and a simple synthesis procedure of fuzzy MRAC are proposed. Several simulation runs show the advantages of fuzzy MRAC approach. Experimental validation on laboratory speed servo is realized by the acquisition system. Results confirm benefits of proposed controller comparing to standard MRAC

Derivation of transport equations for three-dimensional non-isothermal turbulent flow in cylindrical coordinates

U radu su dati osnovni izrazi u krivolinijskim koordinatama, a zatim su u nastavku rada redom izvedene u cilindričnim koordinatama: jednačina entalpije (temperature), Navije-Stoksove i Rejnoldsove jednačine turbulentnog strujanja, transportne jednačine Rejnoldsovih (turbulentnih) napona, transportna jednačina kinetičke energije turbulencije i na kraju transportna jednačina brzine disipacije kinetičke energije turbulencije. Ovim radom je pokušano popuniti prazninu u našoj i stranoj literaturi u oblasti turbulentnih transportnih procesa u vezi sa izvođenjem turbulentnih transportnih jednačina u cilindričnim koordinatama. Ovaj rad može biti od koristi studentima diplomskih i doktorskih studija, kao i inženjerima i istraživačima u praksi pri rešavanju inženjerskih problema i modeliranju turbulentnih strujanja koja su tako česta u termotehnici i energetici.Paper initially presents the elementary expressions in curvilinear coordinates, and afterwards, the following equations have been derived in cylindrical coordinates, respectively: equation of enthalpy (temperature), Navier-Stokes and Reynolds equation for turbulent flow, transport equations of Reynolds (turbulent) stresses, transport equation of kinetic energy of turbulence, and the transport equation of dissipation rate of turbulent kinetic energy. This paper has been attempted to fill the gap in our and foreign literature with respect to derivation of turbulent transport equations in cylindrical coordinates. This work may be useful to students of graduate and doctoral studies as well as engineers and researchers in practice in solving engineering problems and modeling of turbulent flows, commonly found in thermal engineering and energy