Lichens as bioindicators of air quality in Dimitrovgrad (South-Eastern Serbia)

Air pollution detection in Dimitrovgrad has not been done yet. In this work different lichen have been used as a bioindication to establish different air pollution levels. At 18 investigated points 22 lichen taxa have been found. Using the Index of Atmospheric Purity (IAP) it has been found that there are 3 different air pollution zones in Dimitrovgrad: 'lichen desert', 'transitional' and 'normal zone'. The most sensitive lichen taxa in Dimitrovgrad are Evernia prunastra, Ochrolechia pallescens, Parmelia sulcata, and Physcia tenella and the most tolerant are Phaeophyscia orbicularis, Physcia adscendens, Physconia distorta, Physconia grisea, and Xanthoria parietina.

Adaptative significance of amylase polymorphism in Drosophila. III. Geographic patterns in Drosophila subobscura tissue-specific expression of amylase in adult midgut

International audienc

Experimental and numerical investigation of flow around a sphere with dimples for various flow regimes

Flow over a sphere is a typical bluff-body flow with many engineering applications. However, it has not been studied in depth, as compared to flow over a circular cylinder, because of the difficulties in the experimental set-up as well as in the computational approach for studying flow over a sphere. The main challenges are to understand the flow hydrodynamics and to clarify the flow pattern around a dimpled sphere because the flow pattern complying with the dimple structure on its surface is very complicated. In this paper experimental and numerical investigations of the fluid flow around a sphere with dimples, are represented. The sphere with dimples is placed in a quadratic cross section duct (measuring section) and numerical simulation results are obtained by solving RANS equations. Furthermore, experimental measurements are carried out using a Laser-Doppler Anemometer (LDA). Experimental and numerical results of flow velocity fields were compared for three different flow regimes (Re=8×103, 2×104 and 4×104). Numerical investigation was performed for wide range of Reynolds numbers (Re=270%106). The final purpose of this paper is experimental and numerical determination of velocity field, separation point, pressure and drag coefficient, the length of reverse flow region in the wake and RANS turbulent model which gives the best results for engineering practice

Successful resuscitation from two cardiac arrests in a female patient with critical aortic stenosis, severe mitral regurgitation and coronary artery disease

Introduction. The incidence of sudden cardiac death in patients with severe symptomatic aortic stenosis is up to 34% and resuscitation is described as highly unsuccessful. Case report. A 72-year-old female patient with severe aortic stenosis combined with severe mitral regurgitation and three-vessel coronary artery disease was successfully resuscitated following two in-hospital cardiac arrests. The first cardiac arrest occurred immediately after intraarterial injection of low osmolar iodinated agent during coronary angiography. Angiography revealed 90% occlusion of the proximal left main coronary artery and circumflex branch. The second arrest followed induction of anesthesia. Following successful open-chest resuscitation, aortic valve replacement, mitral valvuloplasty and three-vessel aortocoronary bypass were performed. Postoperative pericardial tamponade required surgical revision. The patient recovered completely. Conclusion. Decision to start resuscitation may be justified in selected patients with critical aortic stenosis, even though cardiopulmonary resuscitation in such cases is generally considered futile

Zlato u prošlosti, sadašnjosti i budućnosti

This paper deals with gold, which is described as a chemical element. Special attention is paid to its physical-chemical properties and, furthermore, where or in what form it can be found in nature. We discuss the role it has played through history and we inform how gold has been developed to the level it has reached today’s value. Still more, when gold is broken into nanoparticles, this form could be highly useful for a wide range of processes, including general nanotechnology, electronics manufacturing and the synthesizing of different functional materials. It is important that we know that gold is also used in industry in many engineering applications (contacts in micro-electronics) and medicine (dental alloys, implants).Ovaj članak govori o zlatu kao kemijskom elementu. Posebna pažnja posvećena je njegovim fizikalno-kemijskim svojstvima i gdje i u kojem obliku se može pronaći u prirodi. Razmatra se uloga koju je zlato odigralo u povijesti i donosi se informacije o tome kako je doseglo razinu vrijednosti koju ima danas. Zlato razlomljeno na nanočestice upotrebljivo je u širem spektru procesuiranja, uključujući opću nanotehnologiju, elektroničku prizvodnju i spajanju materijala raznih funkcionalnosti. Važno je znati da se zlato koristi i u industriji, mnogim inženjerskim procesima (kontakti u mikro-elektronici) i medicini (dentalne slitine, implatanti)

Biocompatibility and cytotoxicity study of nanophotonic rigid gas permeable contact lens material

Since materials on nanoscale have different characteristics from materials on macro scale their biocompatibility should be precisely and specifically investigated. Fullerenes, the third carbon allotrope, are one of the most used nanomaterials. The least stable and the most common is fullerene C-60. One of the main disadvantages of fullerene is its low solubility in water. In order to make it soluble, it must be functionalized with polar groups such as -OH and -COOH. From all the water soluble fullerenes the most important ones are those with -OH groups attached named fullerols. We have developed new materials for contact lenses by adding fullerene (C-60) and fullerol (C-60(OH)(24)) into PMMA. The aim of our investigation was to compare the influences of those materials on aqueous solutions similar to tear film. For the analysis of the solutions we used opto-magnetic imaging and IR spectroscopy. The acquired spectrums were commented and compared with the standard contact lens material, which was analyzed by the same methods. The ISO 10993 cytotoxicity test on extract of nanophotonic material with incorporated C-60 was done as well. This research contributes to better understanding of the biocompatibility of new rigid gas permeable contact lens materials

Inversion polymorphism in populations of Drosophila subobscura from urban and non-urban environments

Populations of Drosophila subobscura from the urban area of Belgrade and from the locality, Deliblato, which is not under strong anthropogenic influence, were studied with the aim to characterize and compare their genetic structure by examining chromosomal inversion polymorphism. Additional analysis and comparison of this type of polymorphism with several other populations from different habitats in the central Balkans, was done. The obtained results indicate higher heterozygosity in the population from Belgrade. Despite being ecologically marginal and under strong and complex influences, this population did not show a decline in the number of inversions and it is not highly differentiated compared to the referent populations.

Detection of cause of pipe burst in economizer of process CO steam boiler

U radu su prikazani rezultati analize rada procesnog parnog kotla sa maksimalnom kontinualnom produkcijom pare od 75 t/h pritiska 45,5 bar i temperature 412 oC. Predmetni kotao je deo postrojenja za proizvodnju pare u Rafineriji nafte u Pančevu, Srbija. Prema zahtevu naručioca predviđeno je da kotao radi sa više vrsta goriva kao i sa dve ili tri vrste goriva istovremeno. Pristupnim instalacijama u ložište je moguće dovesti rafinerijski gas, ložno ulje kao i otpadni gas visoke temperature. Otpadni gas se u kotao dovodi iz postrojenja za katalitički kreking (eng. FCC - Fuel catalyst cracking) i predstavlja dvokomponentu mešavine gasne faze i polidisperznih čestica prečnika ne većeg od 40 µm. Skorije promene u proizvodnji pare u rafineriji dovele su do potrebe za modifikacijom radnog režima kotla, odnosno, do modifikacije njegovih radnih parametara. Trenutno, u novim radnim uslovima, u toku rada kotla dešavaju se učestala pucanja cevi na zagrejaču vode što zahteva momentalni prekid proizvodnje pare kao i sprovođenje vremenski i finansijski zahtevanih postupaka u cilju otklanjanja uzroka zastoja i nastavka rada parnog kotla. U ovom radu predstavljeni su rezultati termičkog proračuna predmetnog kotla za projektne i nove uslove rada u cilju identifikacije uzroka učestalih neplankih zastoja u proizvodnji pare. Nakon izvršene analize rezultata proračuna date su preporuke u vezi modifikacije radnih parametara u cilju eliminisanja ili smanjivanja mogućnosti za pojavu neželjenih efakata na zagrejaču vode.In this paper results of analysis of process steam boiler operation with maximum continuous steam production of 75 t/h, steam pressure and temperature of 45,5 bar and 412 oC are presented. Steam boiler is predicted to operate within steam production facility of oil and gas refinery in Pancevo, Serbia. On the demand of purchaser steam boiler is enabled to operate with various fuels as well as with two or three fuels simultaneously. By fuels intake facilities it is enabled to introduce refinery gas, fuel oil and high-temperature waste gas to the boilers furnace. Waste gas is guided from FCC (Fuel catalyst cracking) facility and presents two-component fluid with polydisperse solid phase composed of particles of diameter smaller than 40 µm. Recent changes in steam consumption in refinery resulted in modifications in boiler's operating regime and, further on, in significant changes in its operational parameters. At present, in new conditions, boiler operates with frequent pipe bursts on pipe bundles of boiler economizer which requires forced interruption in steam production as well as time and cost consuming operations for resuming boiler work. In this paper results of thermal calculations for design and new operational conditions are presented for the purpose of identification of cause of frequent unscheduled steam production interruptions. After analysis of presented results, recommendations on how to modify certain boiler operational parameters in order to eliminate or reduce possibility of such unfavourable occurance has been provided