Roman agricultural tools in the ager of Viminacium

The several decades long rescue excavations of the ancient city of Viminacium have brought to light a large number of finds with very varied functions. In this paper, we will focus our attention on the remains of agricultural tools. They can be grouped according to their application: tools for clearing plants and preparing the soil for cultivation, tools used for tillage, implements for shredding and preparation for planting, as well as those used for mowing, harvesting, soil cleaning, and haymaking. The finds of agricultural tools that we present in this paper, although small in number, represent the most reliable indicators of agricultural activities in the period from the 2nd to the beginning of the 4th century, when Viminacium went through its period of greatest prosperity

Let biljnih vaši, potencionalnih vektora virusa, u usevu lucerke u Srbiji

Flight activity of aphids as potential vectors of viral infection of alfalfa plants were monitored in Serbia for the first time in Europe. Research was conducted at the location Progar (Srem) for two years using six yellow water traps. A total of 1626 individual winged aphids were collected. The collected specimens were classified into 49 different taxa. During the two-year study, maximum population density of aphids and maximum potential vector activity were noted at the beginning of June, during the second alfalfa intercut. More than 65% of the collected specimens were potential vectors of the most important alfalfa viruses, Alfalfa mosaic virus (AMV) and Cucumber mosaic virus (CMV). The most numerous winged aphid species on alfalfa were Aphis craccivora, Aphis fabae, Aphis gossypii, Aphis pomi/ spiraecola and Therioaphis trifolii. The Morisita-Horn similarity index was used to calculate similarities in species composition among the traps. High values of this index showed no significant differences among the aphids in traps. It indicates that one trap alone could provide good insight into the abundance, aphid diversity and number of potential vector species in small alfalfa fields.Praćenje leta biljnih vaši, potencijalnih vektora virusa, na lucerki istraživano je na teritoriji Srbije po prvi put u Evropi. Let biljnih vaši na lucerki praćen je na lokalitetu Progar (Srem) tokom dve godine korišćenjem šest žutih lovnih klopki. Sakupljeno je ukupno 1626 krilatih jedinki biljnih vaši. Prikupljene jedinke su klasifikovane u 49 različitih taksona. Tokom dve godine praćenja leta, najveća brojnost biljnih vaši, kao i najveća aktivnost potencijalnih vektora, registrovana je početkom juna, u drugom otkosu lucerke. Više od 65% prikupljenih jedinki su potencijalni vektori dva najvažnija virusa lucerke: virusa mozaika lucerke - Alfalfa mosaic virus (AMV) i virusa mozaika krastavca - Cucumber mosaic virus (CMV). Najbrojnije biljne vaši u klopkama na lucerki bile su: Aphis craccivora, Aphis fabae, Aphis gossypii, Aphis pomi/spiraecola i Therioaphis trifolii. U cilju poređenja sličnosti sastava biljnih vaši u lovnim klopkama, izračunat je Morisita-Horn indeks sličnosti. Visoke vrednosti ovog indeksa ukazuju da nema značajnih razlika u sastavu afidofaune poređenih klopki. Dovoljna je samo jedna lovna klopka radi uvida u brojnost i diverzitet biljnih vaši potencijalnih vektora virusa u lucerki

Effects of welding technology on the occurrence of fracture in welded joints

Welded joints represent locations where failure is most likely to occur in welded structures. Welded joint failure depends on their vulnerability to crack initiation and growth. These factors are significantly influenced by the welding technology. The effect of welding technology on the frequency of welded joint failure is complex, and has been thoroughly researched in literature. However, there are still numerous factors whose influence is not sufficiently explained. In this paper, the ratio of strength and plasticity of parent materials and weld metals on deformation properties of welded joint zones were analysed, along with the effects of groove edge temperature on cooling time in the heat affected zone and the effect of multiple defects on local stress increase

Stanje oralnog zdravlja dece obolele od nasledne distrofičke bulozne epidermolize

Background/Aim. Epidermolysis bullosa is a group of rare, genetic connective tissue diseases that cause blisters in the skin and mucosal membranes. The aim of this study was to evaluate the oral health status of patients with epidermolysis bullosa dystrophica and level of knowledge and opinion of parents about the implementation of preventive measures and quality of dental care of affected children. Methods. This study included a group of 17 patients from Serbia suffering from dystrophic epidermolysis bullosa and matched control group. Dental caries status was assessed using the Klein-Palmer index. Oral hygiene status was verified with oral hygiene indices, simplified plaque index, and calculus index as described by Green and Vermillion. The gingiva was assessed as healthy or inflamed (gingivitis) on the basis of any changes in color, shape, size and surface texture. The condition of oral mucosa has been registered on the basis of inspection of the lips, tongue, a floor of the mouth, mouth vestibule and palate. The level of knowledge and the impressions of parents about the application of preventive measures were investigated through two questionnaires specifically designed for this study. Results. In both dentitions, there was the highest percentage of caries teeth. In primary dentition average value of the modified plaque index was 1.4 ± 1.14 and modified calculus was 0.7 ± 1. On permanent teeth average plaque index was 2 ± 0.4, and average calculus 1.6 ± 0.6. Statistically, significant higher values were found in permanent dentition in percentage distribution of decayed, missing, filled teeth and also for plaque and calculus indices between affected children and the control group. Most common findings on mucosa were microstomia (76.5%) and ankyloglossia (88.2%). Conclusion. The absence of protocol between the treating physician and the dentist and not sufficiently informed parents are leading to inadequate dental care. The implementation of preventive measures is of most importance to decrease the risk of severe complications that are difficult to be managed.Uvod/Cilj. Bulozna epidermoliza je grupa retkih, genetski predisponiranih bolesti vezivnog tkiva koja se karakteriše formiranjem bula (mehurova) u koži i mukoznim membranama. Cilj rada bio je da se ispita stanje oralnog zdravlja dece obolele od distrofične bulozne epidermolize, kao i nivo znanja i mišljenje roditelja o primeni preventivnih mera i kvalitetu stomatološke zaštite obolele dece. Metode. U studiju je bilo uključeno 17 bolesnika sa distrofičnom buloznom epidermolizom iz Srbije i odgovarajuća kontrolna grupa. Stanje zuba ustanovljeno je Klein Palmerovim indeksom karijesnih, ekstrakovanih plombiranih zuba - KEP indeksom. Stanje oralne higijene analizirano je indeksima oralne higijene (pojednostavljeni plak indeks i indeks zubnog kamenca po Green-Vermillionu). Stanje gingive je na osnovu inspekcije ocenjivano kao zdrava gingiva ili gingivitis, u zavisnosti od toga da li su joj bili promenjeni boja, oblik, veličina ili struktura. Stanje oralne sluzokože evidentirano je na osnovu inspekcije usana, jezika, poda usne duplje, vestibuluma, plika i frenuluma, kao i mekog i tvrdog nepca. Nivo znanja i utisci roditelja o primeni preventivnih mera i kvalitetu stomatološke zaštite dece obolele od bolozne epidermolize, ispitivani su kroz dva upitnika specijalno dizajnirana za potrebe ove studije. Rezultati. U obe denticije bilo je najviše karijesno obolelih zuba. Za mlečnu denticiju prosečan modifikovani plak indeks iznosio je 1,4 ± 1,14, a modifikovani kalkulus indeks 0,7 ± 1. U stalnoj denticiji vrednosti prosečnog plak indesa i kalkulus indeksa redom su bile 2 ± 0,4 i 1,6 ± 0,6. Utvrđena je statistički značajna razlika u procentualnoj zastupljenosti karijesnih, ekstrahovanih i plombiranih zuba stalne denticije između dece obolele od bulozne epidermolize i kontrolne grupe, kao i za vrednosti plak i kalkulus indeksa. Najčešće promene oralne sluzokože bile su mikrostomija (76,5%) i ankiloglosija (88,2%). Zaključak. Odsustvo protokolarne saradnje između ordinirajućeg lekara i stomatologa, kao i nedovoljna informisanost roditelja, glavni su razlozi lošeg stanja oralnog zdravlja. Primena preventivnih mera je od najvećeg značaja kako bi se sprečio nastanak komplikacija koje je teško sanirati kod ove grupe bolesnika

Potencijalna opasnost od pojave invazivne vaši Acyrthosiphon kondoi Shinji, 1938 (Hemiptera: Aphididae) na lucerki u Srbiji

Aphids (Hemiptera: Aphididae) are important pests of alfalfa all over the world. One of the most important ones is a blue alfalfa aphid - Acyrthosiphon kondoi Shinji. Morphology of the species is very similar to a green alfalfa aphid - Acyrthosipom pisum Harris. Saliva of A. kondoi is very toxic and this is why it is more important than other pest species. It can cause alfalfa wilting. Recently, A. kondoi was found in Europe, in Greece and France. It is expected to appear in other European countries. The presence of A. kondoi in Serbia was investigated from 2011 to 2015 on alfalfa and other host plants and it was not found.Biljne vaši (Hemiptera: Aphididae) svojom aktivnošću nanose značajne ekonomske gubitke u proizvodnji lucerke širom sveta. Jedna od najznačajnijih štetočina ove gajene biljke u svetu je plava lucerkina vaš - Acyrthosiphon kondoi Shinji. Ova vrsta je morfološki veoma slična zelenoj lucerkinoj vaši - Acyrthosipom pisum Harris. Zbog toksičnog sadržaja sekreta pljuvačnih žlezda A. kondoi je štetnija od drugih vaši koje se hrane na lucerki. Ishranom može prouzrokovati uvenuće biljaka lucerke. Acyrthosiphon kondoi je nedavno registrovana u Evropi, Grčkoj i Francuskoj. Postoji mogućnost pojave ove invazivne vrste i značajne štetočine lucerke u drugim evropskim zemljama. Tokom četvorogodišnjih istraživanja (2011-2015), prisustvo ove vaši nije utvrđeno na lucerki i drugim biljkama domaćinima na teritoriji Srbije

Definition of welding parameters by cooling time in temperature range 800-500ºC

Vreme hlađenja u temperaturnom intervalu 800 - 500ºC (t8/5) ima veliki uticaj na strukture koje nastaju u zoni uticaja toplote zavarenih spojeva čelika. Podaci o optimalnim vremenima hlađenja t8/5 za pojedine čelike se mogu naći u literaturi. Na veličinu vremena hlađenja t8/5, pri zavarivanju konkretnog spoja, pored debljine i fizičkih osobina zavarivanog čelika imaju uticaj i oblik spoja, postupak zavarivanja i parametri, kao što su temperatura predgrevanja, struja, napon i brzina zavarivanja. U ovom radu je prikazan postupak za izbor parametara zavarivanja za jedan sučeoni spoj zavaren na mikrolegiranom čeliku P 460 NL1. Prikazane su mikrostrukture u zoni uticaja toplote i rezultati merenja njihovih tvrdoća. Zaključeno je da parametri zavarivanja odabrani uz pomoć vremena hlađenja t8/5 daju spoj sa zadovoljavajućim strukturama i tvrdoćama.Cooling time in the temperature range 800 - 500°C has a great effect on the structures that arrise in the heat affected zone of welds steel. Data on optimal cooling time t8/5 for the certain steels can be found in the literature. The period of the cooling time t8/5, during the welding of the particular joints, in addition to the thickness and physical properties of welded steel, depends on shape of the weld, the welding process and welding parameters as well. In this work, the procedure for the selection of welding parameters for a butt joint welded to the microalloyed steel P 460 NL1 is presented. The microstructure in the heat affected zone and the results of measurement of their hardness are showed and analysed. It is concluded that the welding parameters selected with the help of cooling time t8/5 provide the satisfactory structure and hardness of welds

Biljne vaši (Aphididae, Hemiptera) u semenskom krompiru

Aphids (Aphididae, Hemiptera) are efficient vectors of plant viruses and a significant problem in potato growing. Production of healthy seed potato is possible if the number of aphids is reduced, as well as their ability to come into contact with the plant and transfer the virus. Research related to the presence and abundance of aphid species in different parts of Serbia was carried out on 30 sites in four years: 2007, 2008, 2009 and 2010. Yellow water traps were placed in potato crop immediately after potato emergence. Samples were taken once per week until the drying of the above-ground mass. Over 11,500 specimens were collected and a total of 106 different taxa of aphids were identified. This publication analyses vector pressures for two most important potato viruses (PVY and PLRV) for different localities. The best conditions for the production of healthy seed potato exist on the Golija mountain, at altitudes above 1100 m, in comparison to other tested sites. The pressure of vectors on the mountain is low and so is the risk of potato plants viral infection because of late potato planting and low aphid occurrence.Biljne vaši (Aphididae, Hemiptera) su efi kasni vektori biljnih virusa i predstavljaju značajan problem u proizvodnji krompira. Proizvodnja zdravog semenskog krompira moguća je u uslovima smanjene brojnosti vašiju i mogućnosti da vaši dođu u kontakt sa biljkom i prenesu virus. Istraživanja prisustva vrsta i brojnosti biljnih vašiju na različitim područjima Srbije obavljena su tokom 2007, 2008, 2009. i 2010. godine. Na ukupno 30 lokaliteta, u zasade krompira, postavljane su žute lovne posude odmah nakon nicanja krompira, a uzorci uzimani jednom nedeljno do sušenja nadzemne mase. Sakupljeno je preko 11.500 jedinki i utvrđeno ukupno 106 različitih taksona biljnih vašiju. U radu je analiziran pritisak vektora za dva najznačajnija virusa krompira (PVY i PLRV) na različitim lokalitetima. Od analiziranih područja, najbolji uslovi za proizvodnju zdravog semenskog krompira su na planini Golija, na nadmorskim visinama iznad 1.100 m. Usled kasne setve krompira i male brojnosti biljnih vašiju i pritisak vektora je nizak, a tako i rizik od zaražavanja krompira virusima

Biljne vaši (Hemiptera: Aphididae) na pšenici

Aphids (Hemiptera: Aphididae) are regularly occurring on wheat, more or less numerous, depending of the year. Direct damage, as yield losses and spoiled the baking quality of the grain, is made by aphids feeding on phloem sap. Transmitting of viruses is very important indirect damage. Many aphid species could be found on wheat in Serbia. The most important species are: grain aphid (Sitobion avenae), bird cherry-oat aphid (Rhopalosiphum padi) and rose-grain aphid (Metopolophium dirodum). Some notes on morphology, host plants, biology, damage, distribution, vector role and most important natural enemies (Coccinellidae, Syrphidae i Aphidiidae) are given for every of these three species.Biljne vaši (Hemiptera: Aphididae) se redovno javljaju na pšenici, u manjoj ili većoj brojnosti, zavisno od godine. Direktne štete nanose isisavanjem biljnih sokova prouzrokujući smanjenje prinosa i kvalitet zrna. Indirektna štetnost, koja se ogleda u prenošenju biljnih virusa, može da bude izuzetno visoka i da premaši direktnu štetnost. Na pšenici kod nas, može se naći više vrsta biljnih vašiju. U radu su prikazane ekonomski najznačajnije vrste: velika žitna vaš (Sitobion avenae), sremzina vaš (Rhopalosiphum padi) i zelena ružina vaš (Metopolophium dirodum). Navedeni su osnovni morfološki podaci za svaku vrstu, biljke domaćini, biologija razvića, štetnost, rasprostranjenje, vektorska uloga, kao i najznačajniji prirodni neprijatelji (Coccinellidae, Syrphidae i Aphidiidae)

Tačkasta lucerkina vaš, Therioaphis trifolii (Monell) (Hemiptera: Aphididae) - štetočina lucerke u Srbiji

Spotted alfalfa aphid Therioaphis trifolii (Monell) (Hemiptera, Aphididae) is one of the most important alfalfa pest on the world. Also, it is the most abundant alfalfa aphid in Serbia. This aphid cause damage to alfalfa directly by feeding and indirectly by vectoring plant-pathogenic viruses. Some notes of morphology, host plants, damage, biology, vector role and distribution of spotted alfalfa aphid are given. Abundance of this aphid on alfalfa, influence of climates changes on its abundance, as well as the most important natural enemies (Coleoptera: Coccinellidae and Hymenoptera: Aphidiidae) in Serbia were analyzed.Tačkasta lucerkina vaš Therioaphis trifolii (Monell) (Hemiptera, Aphididae) jedna je od najznačajnijih štetočina lucerke u svetu, takođe, to je najbrojnija vaš na lucerki u Srbiji. Pored direktnih šteta koje nanosi ona je i vektor najznačajnijih virusa lucerke. U radu su prikazani osnovni marfološki podaci, biljke domaćini, štetnost, biologija razvića, vektorska uloga i rasprostranjenje tačkaste lucerkine vaši. Analizirana je njena brojnost na lucerki, uticaj klimatskih promena na povećanje brojnosti, kao i najznačajniji prirodni neprijatelji (Coleoptera: Coccinellidae i Hymenoptera: Aphidiidae) na teritoriji Srbije

Razvoj čelika za izradu šina

Železničke šine predstavljaju najvažniji i najskuplji deo koloseka, pa je prioritet u istraživanjima produžetak njihovog radnog veka. Pošto je šina pored oblika, određena i materijalom od kog je izrađena, brojni su pokušaji u pronalaženju što kvalitetnijeg čelika koji će da odgovori svim postavljenim zahtevima. U radu je prikazan hronološki razvoj čelika za šine, počev od prvog korišćenog ugljeničnog čelika perlitne mikrostrukture, preko postupka otvrdnjavanja glava i dobijanja premium šina, pa do najnovijih generacija beinitnih čelika. Veliki broj istraživača u svetu intenzivno radi na ovoj problematici, i preliminarni rezultati pokazuju superiorna svojstva novih čelika u pogledu tvrdoća, žilavosti, habanja i otpornosti na kontaktni zamor