Analiza faktora rizika za nastanak okluzije grafta kod femoropoplitealnog bajpasa

Utvrđivanje značajnih faktora rizika za nastanak okluzije grafta kod femoropoplitealnog bajpasa. METODE. Retrospektivnom studijom tipa slučaj-kontrola obuhvaćeni su pacijenti kod kojih je urađen femoropoplitealni bajpas zbog arterijske bolesti donjih ekstremiteta od 2008. do 2011.godine u Kliničkom centru Kragujevac, Srbija. Slučajevi(n35) su bili pacijenti sa okluzijom grafta nakon femoropoplitealnog bajpasa, koja je zahtevali hiruršku intervenciju. Kontrolnu grupu (n70) činili su pacijenti bez okluzije grafta. Slučajevi i kontrole su usklađeni prema polu i starosti. REZULTATI. Značajan uticaj na okluziju grafta utvrđen je za vrstu femoropoplitealnog bajpasa, vrstu grafta, kardiovaskularna oboljenja, prethodne vaskularne postupke i preoperativni stadijum bolesti po Raderfordu. Značajan sinergistički uticaj utvrđen je za kombinaciju vrste bajpasa I vrste grafta, vrste grafta i prethodnih vaskularnih postupaka, vrste bajpasa i kardiovaskularnih oboljenja, vrste grafta I kardiovaskularnih oboljenja, vrste grafta I preoperativnog stadijuma bolesti po Raderfordu, vrste bajpasa i preoperativnog stadijuma bolesti po Raderfordu. Zaključci. Rezultat naše studije ukazuje da prateća kardiovaskularna oboljenja i uznapredovalost vaskularne bolesti treba uzeti u razmatranje zajedno sa vrstom grafta i operativnom procedurom kada se planira femoropoplitealni bajpas kod pacijenata sa vaskularnom bolešću donjih ekstremiteta.To identify significant risk factors for femoropopliteal bypass graft occlusions. METHODS. A retrospective case-control study included patients who had undergone femoropopliteal bypass due to lower extremity arterial disease at the Clinical Centre Kragujevac, Serbia, between 2008. and 2011. The cases (n 35) were patients with femoropopliteal bypass graft occlusion which required surgical intervention. The control group (n 70) consisted of patients without graft occlusion. The cases and controls were age and sex matched. RESULTS. Significant impact on graft occlusion was found for the form of femoropopliteal bypass, type of graft, cardiovascular disease, previous vascular procedures, preoperative disease stage according to Rutherford. A significant synergistic effect on graft occlusion was observed for the combination of form of bypass and type of graft, combination of type of graft and previous vascular procedures, combination of form of bypass and cardiovascular diseases, combination of type of graft and cardiovascular diseases, combination of type of graft and preoperative disease stage, and combination of form of bypass and preoperative disease stage. CONCLUSIONS. The results of our study suggest that concomitant cardiovascular diseases and severity of the vascular disease itself should always be taken into account together with type of the graft and type of the operative procedure when planning femoropopliteal bypass in a patient with lower extremity vascular disease

Effect of Different Types of Fly Ash on Properties of Asphalt Mixtures

In order to preserve natural resources, the use of waste and alternative materials in the construction and maintenance of roads is increasingly investigated. This paper presents the results of testing wearing course asphalt mixtures (AC 11s SURF 50/70) made with various percentages of fly ash, used as a partial or complete substitute for mineral filler. The properties of fly ash were determined to assess their suitability for use in asphalt mixtures. The experimental research was performed on asphalt samples containing fly ash from three different sources, with 25%, 50%, 75%, and 100% of mineral filler substitution. The control mixture was prepared with 100% of mineral filler. The paper presents the volumetric composition, stability, and flow of asphalt mixtures tested on standard Marshall's samples, water sensitivity, and resistance to permanent deformation. The results of this study indicate that a satisfactory volumetric composition can be achieved by adding fly ash, while the bulk density and voids of the mineral and asphalt mixture generally depend on the type of fly ash and its content. The stability and flow of mixtures with fly ash are favourable compared with the control mixture. The water sensitivity of mixtures with fly ash is generally lower compared with the control mixture and depends on the type and percentage of fly ash. The resistance to permanent deformation of the asphalt mixtures depends on the fly ash type and percentage. The results obtained in this study are an important step towards broader implementation of fly ash in asphalt mixtures

Primena 3D kompatibilnih materijala u građevinarstvu

Zbornik radova Građevinskog fakultet

Veza donjeg i gornjeg stroja betonskih mostova sa aspekta seizmičke izolacije konstrukcije

This paper presents the basic principles seismic isolation of concrete bridgesusing different types connections between superstructure and substructure of construction.In the particular case of the bridge over river Dičina on the section Takovo – Preljina ofhighway E-763 Belgrade - Požega modeled cases with rigid and hinge connection, andcase with elastomeric bearings. Analised influence of the type connection on improvingseismic isolation of construction as well as the impact changes the stiffness of elastomericbearings on the resulting seismic forces. In the conclusions were presented basicobservations conducted analysis could be applied at the calculation similar bridges of thistype in seismic active areas.Zbornik radova Građevinskog fakultet

Prikaz metoda za proračun ploča direktno oslonjenih na stubove

The paper analyzes the results of reinforced concrete flat slabs, using different methods based on the theory of elasticity and theory of plasticity. Were considered three methods: stripe method, method according to Hillerborg and Wiesinger and Yield Line theory. The stripe method based on the theory of elasticity and is one of the most commonly used methods for calculation flat slabs, which are recommended by many regulations for calculation reinforced concrete structures. This paper also presents two methods based on the theory of plasticity, the method according to Hillerborg and Wiesinger - lower bound and Yield Line theory - upper bound, which uses a solutions of Johansen. Solutions obtained by these methods define limits interval of critical load. Review the basic theoretical hypothesis of all these methods and their application to flat slabs. Conducted calculation according to Eurocode 2 with a regular arrangement of pillars, analyzed the results and commented differences that occur as a result of the adoption of various hypothesis.U radu su analizirani rezultati proračuna armiranobetonskih ploča direktno oslonjenih na stubove, koristeći različite metode koje se zasnivaju na teoriji elastičnosti i teoriji plastičnosti. Razmatrane su tri metode: metoda ekvivalentnih traka, metoda prema Hillerborg-u i Wiesinger-u i metoda linija loma. Metoda ekvivalentnih traka zasniva se na teoriji elastičnosti i jedna je od najčešće primenjivanih metoda za proračun ploča direktno oslonjenih na stubove, koju preporučuju mnogi propisi za proračun armiranobetonskih konstrukcija. U radu su predstavljene i dve metode koje se zasnivaju na teoriji plastičnosti, metoda prema Hillerborg-u i Wiesinger-u teorija donje granice i metoda linija loma (Yield Line theory) teorija gornje granice, koja koristi rešenja Johansen-a. Rešenja dobijena ovim metodama definišu granice intervala kritičnog opterećenja. Prikazane su osnovne teorijske pretpostavke svih navedenih metoda kao i njihova primena na ploče direktno oslonjene na stubove. Sproveden je proračun ploče prema Evrokodu 2 sa pravilnim rasporedom stubova, analizirani su rezultati i komentarisane razlike koje se javljaju kao posledica usvajanja različitih pretpostavki.Zbornik radova Građevinskog fakultet

Effect of Different Types of Fly Ash on Properties of Asphalt Mixtures

In order to preserve natural resources, the use of waste and alternative materials in the construction and maintenance of roads is increasingly investigated. This paper presents the results of testing wearing course asphalt mixtures (AC 11s SURF 50/70) made with various percentages of fly ash, used as a partial or complete substitute for mineral filler. The properties of fly ash were determined to assess their suitability for use in asphalt mixtures. The experimental research was performed on asphalt samples containing fly ash from three different sources, with 25%, 50%, 75%, and 100% of mineral filler substitution. The control mixture was prepared with 100% of mineral filler. The paper presents the volumetric composition, stability, and flow of asphalt mixtures tested on standard Marshall’s samples, water sensitivity, and resistance to permanent deformation. The results of this study indicate that a satisfactory volumetric composition can be achieved by adding fly ash, while the bulk density and voids of the mineral and asphalt mixture generally depend on the type of fly ash and its content. The stability and flow of mixtures with fly ash are favourable compared with the control mixture. The water sensitivity of mixtures with fly ash is generally lower compared with the control mixture and depends on the type and percentage of fly ash. The resistance to permanent deformation of the asphalt mixtures depends on the fly ash type and percentage. The results obtained in this study are an important step towards broader implementation of fly ash in asphalt mixtures.Article ID 8107264, 11 page

Use of low-energy electron-beam in the treatment of special food products with a high protein content

Special high-protein foods suitable for diabetics must be treated to ensure the complete absence of microorganisms and bacteria. It is also important to achieve that this treatment does not change the nutritional value of the product. Among the new decontamination technologies, low-energy electron-beam treatment has proven to be an effective technique for inactivating bacteria with minimal impact on food quality. The paper aims to analyze the influence of low-energy electron-beam irradiation on the microbiological properties and nutritional value of high-protein foods

Tehnički zahtevi za prijem radova na koloseku

U radu se predstavlјaju tehnički zahtevi za prijem radova na koloseku normalne širine (1435 mm) u zastoru od tucanika u skladu sa evropskim standardom EN 13231-1, koji je 2014. godine usvojen kao srpski standard. Prijem radova se odnosi na građenje novog, kao i na rekonstrukciju, obnovu i odr-žavanje postojećeg koloseka. U radu se ukazuje na to da, uprkos uspostavljenom zakonskom okviru u Republici Srbiji, domaća tehnička regulativa još uvek nije harmonizovana sa zahtevima pomenutog standarda. Pored toga, ukazuje se na važnost definisanja procedura za sprovođenje merenja vrednosti referentnih parametara i kontrole stanja koloseka, kao i postupaka za dokumentovanje rezultata merenja i sprovedenih kontrola. Prikazane su propisane tolerancije za parametre geometrije koloseka i elemente konstrukcije gornjeg stroja koloseka prema zahtevima EN 13231-1. Posebno se ukazuje na važnost utvrđivanja roka za izvršanje prijema radova u ugovoru sklopljenom između upravljača infrastrukture i izvođača radova