SEM study of Thermafil obturation technique with 5 endodontic sealers

Aim: To measure layer thickness of 5 endodontic sealers and evaluate sealer distribution and adaptation of thermafil and sealer within root canals. Material and Methods: 20 single-rooted teeth divided into 5 groups were prepared in the crown-down technique. Smear layer was removed and root canals were obturated with Thermafil and 1 of 5 different endodontic sealers: AH Plus, Tubliseal, Acroseal, Apexit and Sealapex. Roots were cross-sectioned in 3 levels resulting in 4 sections for scanning electron microscopy (SEM). Results: Acroseal exhibited the greatest mean layer thickness, followed by AH Plus, while Tubliseal showed the thinnest mean layer. Sealers were unevenly distributed with incomplete layer along root canal perimeter. No sealer formed a continuous layer between the dentinal wall and guttapercha. Gaps of up to 10 μm were observed between core plastic carrier and gutta-percha. Microscopically visible voids were present in different levels of root canals, usually between dentinal wall and sealer/gutta-percha. Conclusions: The layer thickness in decreasing order were: Acroseal > AH Plus > Sealapex > Apexit > Tubliseal. Microgaps between dentinal wall and the obturating material and gutta-percha / carrier could contribute to inadequate adhesion within the root canal and increased microleakage of Thermafil compared to other obturation techniques

Estimating subseasonal variability and trends in global atmosphere using reanalysis data

A new measure of subseasonal variability is introduced that provides a scale-dependent estimation of vertically and meridionally integrated atmospheric variability in terms of the normal modes of linearized primitive equations. Applied to the ERA-Interim data, the new measure shows that subseasonal variability decreases for larger zonal wave numbers. Most of variability is due to balanced (Rossby mode) dynamics but the portion associated with the inertio-gravity (IG) modes increases as the scale reduces. Time series of globally integrated variability anomalies in ERA-Interim show an increase in variability after year 2000. In recent years the anomalies have been about 2% above the 1981–2010 average. The relative increase in variability projecting on the IG modes is larger and more persistent than for the Rossby modes. Although the IG part is a small component of the subseasonal variability, it is an important effect likely reflecting the observed increase in the tropical precipitation variability. ©2018. The Authors

Pokazatelji rada kružne peći u restriktivnim uvjetima proizvodnje

The heating operation of the rotating-hearth furnace involving semi-finished steel products was analysed, and specific heat consumption was determined as a function of furnace productivity. The aim was to find out how a change in productivity, which is not accompanied by a modification of the thermal regime, can affect the heating quality and surface oxidation of products.Analizirana je provedba zagrijavanja čeličnih poluproizvoda u kružnoj peći i određena je specifična potrošnja topline u ovisnosti o proizvodnosti peći. Istražen je utjecaj promjene proizvodnosti kružne peći pri nepromijenjenom toplinskom režimu na kvalitetu zagrijavanja čeličnih poluproizvoda i na oksidaciju njihove površine

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.

Innovative protected areas management models in support of the establishment and operation of the ecological network of Serbia

Успостављање заштићених подручја представља један од најефикаснијих начина заштите предела у којима је природа остала сачувана, па самим тим ова подручја чине један од најважнијих природних ресурса једне земље. Добро управљање подразумева постојање јасних и прецизних управљачких циљева, а реализује се преко планова управљања, који представљају прописе којима се јасно планирају мере и активности заштите неког подручја, као и развојне смернице, уз уважавање потреба локалног становништва које на том простору живи или користи његове ресурсе. Ефикасно управљање заштићеним подручјима је од кључне важности, да би сврха њиховог успостављања била оправдана, а постављени циљеви остварени. Циљ овог рада је анализа стања заштите природе у Србији у области заштићених подручја, указивање на недостатке и проблеме, препоруке и могућа решења, како би се капацитети управљача повећали, а управљање постало ефикасније. Ради упознавања са конкретном ситуацијом и ставовима самих управљача припремљена је анкета, односно упитник, а ради испитивања институционалног окружења урађен је експертски интервју, који је омогућио сагледавање међусобних односа и будућих планова. Одабрана питања била су отвореног, затвореног и мешовитог типа, а анкетирање управљача и интервју су реализовани у периоду од децембра 2014. до марта 2015. Упитнике је доставило 50 управљача, који управљају на 100 заштићених подручја, а на основу њихових одговора анализирани су капацитети управљача,њихов однос са локалном заједницом, туризам у заштићеним подручјима, реализација пројеката, постојање база података и вршење мониторинга, фактори угрожавања добра, као и мере заштите које се у односу на њих предузимају...The establishment of protected areas is one of the most effective ways to protect the areas with preserved nature, which are, as such, among the most important natural resources of a country. Proper management implies clear and precise management objectives, implemented through management plans, that is, clear procedures for planning measures and activities to protect certain area, as well as development guidelines, while observing the needs of the local population living in the area or using its resources. Effective management of protected areas is essential in justifying the purpose of their establishment and meeting their objectives. The aim of this paper is to assess the state of nature conservation in Serbia in the field of protected areas, to point out the shortcomings and problems, as well as recommendations and possible solutions, in order to increase the management efficiency and capabilities. In order to assess the actual situation and positions of the managers themselves, a questionnaire - survey was developed, and an expert interview was conducted in order to examine the institutional environment, which enabled consideration of the mutual relations and future plans. Selected questions were of open, closed and mixed types; the survey and the interview were conducted in the period from December 2014 to March 2015. The questionnaires were submitted by 50 managers operating in 100 protected areas. On the basis of their responses, the capabilities of the managers were analyzed, as well as their relationship with the local community, tourism in protected areas,implementation of projects, existence of databases and monitoring, factors threatening the environment, and appropriate protection measures..

Galactic interstellar filaments as probed by LOFAR and Planck

Recent Low Frequency Array (LOFAR) observations at 115-175 MHz of a field at medium Galactic latitudes (centered at the bright quasar 3C196) have shown striking filamentary structures in polarization that extend over more than 4 degrees across the sky. In addition, the Planck satellite has released full sky maps of the dust emission in polarization at 353GHz. The LOFAR data resolve Faraday structures along the line of sight, whereas the Planck dust polarization maps probe the orientation of the sky projected magnetic field component. Hence, no apparent correlation between the two is expected. Here we report a surprising, yet clear, correlation between the filamentary structures, detected with LOFAR, and the magnetic field orientation, probed by the Planck satellite. This finding points to a common, yet unclear, physical origin of the two measurements in this specific area in the sky. A number of follow-up multi- frequency studies are proposed to shed light on this unexpected finding.Comment: 6 pages, 4 figures, accepted for publication in MNRAS Letter

PROBLEMS OF BIOFOULING ON FISH–CAGE NETS IN AQUACULTURE

Obraštanje mreža od kojih su izrađeni kavezi za uzgoj ribe ozbiljan je tehnički i ekonomski problem u akvakulturi širom svijeta. Posljedice obrastanja mreža moraju se uzeti u obzir prigodom dizajniranja i planiranja kaveznih struktura, jer obraštaj može drastično povećati težinu kaveza i opterećenje na plutnju. Naseljavanje biljnih i životinjskih organizama, te nakupljanje detritusa ima kao posljedicu smanjenje veličine i zatvaranje oka mrežnih kaveza. Negativna posljedica smanjivanja veličine oka mreže jest poremećena dinamika izmjene vode u kavezima. Sve je to problem za uzgajivače i od njih iziskuje nabavu dvostrukog broja mreža. Mreže je potrebno zamjenjivati i čistiti od obraštaja. Učestalost mijenjanja ovisi o dosta čimbenika kao što su: položaj kaveza (bliže obali ili »off shore«), produktivnost samog područja, godišnje doba, starost samog uzgajališta (zbog nakupljanja neiskorištenog P i N iz hrane u sedimentu). Sve to iziskuje visoke materijalne i radne troškove održavanja. Sam proces čišćenja izvađenih mreža od obraštaja nije adekvatan, pogotovo u malim uzgajalištima koja nemaju odgovarajuću opremu za to. Učinkovitost antivegetativnih premaza dovodi se u pitanje zbog njihova negativnog učinka i na obraštajne i na uzgajane organizme, te na okoliš.Biofouling on fish–cage netting is a serious technical and economical problem to aquaculture worldwide. Compensation for the effects of biofouling must be included in cage system design and planning, as fouling can dramatically increase both weight and drag. Settlements of sessile plants and animals, with accumulation of the detritus diminish the size of mesh and can rapidly occlude mesh. Negative effect of smaller mesh size is changing in water flow trough the cages. Biofouling problems necessitating purchase of a second sets of nets or more, and frequent cleaning and changing of biofouling. Changing and cleaning frequency depend on many factors such as: location of cages (near the coast or off shore), productivity of that location, time of the year, time period in which the cages are placed on that location (cause of loading of phosphorus and nitrogen from the unconsumed food in the sediment). Net changing and cleaning procedures are labor and capital intensive. Process of the cleaning of the nets is inadequate, especially when there isnžt adequate equipment available as it is case in smaller aquaculture industry. Chemical control of biofouling e. g. use of antifoulants is questioningly cause of their possible negative effects on breeding species and environment

Kvalitet i stanje semena pšenice (Triticum spp.) tokom skladištenja

The effect of storage on quality and condition of grain of three wheat cultivars (Ljiljana, Dragana and Simonida) selected in Serbia, was studied. Freshly harvested wheat was stored at 25°C for 12 and 20 months. Decreasing of the volume from 812.3 to 727.7 kgm-3 and absolute mass from 38.5 to 33.0% of wheat grain during storage was recorded. Grain germination in interaction of storage duration and temperature remained at the level above 95%. The interaction of studied factors exhibited no statistically significant effect on the changes in the degree of germination of wheat grain. The changes of the acid degree value (2.0- 2.4 ml 1(NaO)/100 g) were at the level of statistical significance. pH value of fresh samples of grain was 6.5 and after 20 months 5.5. The samples tested from the aspect of their glassiness were homogenous, the value of the coefficient of variation for storage duration was CV lt 10%, and for genotypes CV lt 18%. The storage duration of wheat grain mostly contributed to the increase of the acid degree value, and slightly less the genotype, as well as the interaction of these factors.Ispitivan je uticaj skladištenja na kvalitet i stanje semena pšenice za tri sorte (Ljiljana, Dragana i Simonida) koje su selekcionisane u Srbiji. Posle žetve pšenica je uskladištena na 25°C za 12 i 20 meseci. Zabeležen je pad vrednosti zapreminske 812,3-727,7 kgm-3 i apsolutne mase 38,5 - 33,0% tokom skladištenja semena pšenice. Klijavost semena u interakciji vremena i temperature skladištenja se zadržala na nivou preko 95%. Interakcija ispitivanih faktora nije ispoljila statistički značajan uticaj na promenu stepena klijavosti semena pšenice. Promene kiselinskog stepena (2,0-2,4 ml 1(NaO)/100 g) su na nivou statističke značajnosti. pH vrednost svežih uzoraka semena je bila 6,5 a nakon 20 meseci 5,5. Uzorci testirani na svojstvo staklavosti su veoma homogeni, vrednost koeficijenata varijabilnosti za dužinu skladištenja je Cv lt 10%, a za genotipove Cv lt 18%. Dužina skladištenja semena pšenice najviše doprinosi porastu vrednosti kiselinskog stepena, a nešto manje genotip, kao i interakcija ovih faktora