Karakteristike betona sa delimičnom zamenom prirodnog agregata struganim asfaltom

Predmet ovog istraživanja bila je procena mogućnosti upotrebe struganog asfalta (RAP) u betonima namenjenim za krute kolovozne konstrukcije. Izuzev kontrolne mešavine spravljene sa prirodnim agregatom, eksperimentalna ispitivanja su obuhvatila i ispitivanja četiri betonske mešavine sa delimičnom zamenom prirodnog agregata recikliranim (RAP-om) u količinama od: 25% i 50% (za sitan i krupan agregat 0/22.4 mm); 50% (za sitan agregat 0/4 mm); 50% (za krupan agregat 4/22.4 mm). Sprovedena ispitivanja su pokazala da dodatak RAP-a dovodi do pada čvrstoće pri pritisku u granicama od 27% do 47% i srazmerno niže vrednosti modula elastičnosti i otpornosti na habanje. Dodatak RAP-a nije imao negativan efekat na trajnost betona

Promene u mikrostrukturi kao osnova povećane fragilnosti vrata butne kosti osoba sa tip 2 dijabetesom

Introduction: The number of individuals with type 2 diabetes (T2DM) has reached alarming levels worldwide, with projections indicating that it will assume pandemic proportions in the future. Physicians and scientists are becoming increasingly aware of the elevated fracture risk in individuals with T2DM compared with non-diabetic individuals. However, the fracture mechanisms associated with T2DM are not yet fully understood, and preventive programs remain underdeveloped. Aim: This thesis aimed to investigate the alterations in cortical and trabecular bone caused by the presence of T2DM in the femoral neck, a common site of fracture in diabetic subjects. In parallel with this investigation, we conducted a detailed analysis of the microarchitecture along the superolateral femoral neck in elderly individuals for two reasons. First, it is a common site for the initiation of fractures, and second, if the microarchitecture of the superolateral femoral neck is non-uniform, the areas with weaker microarchitecture might experience additional deterioration in the presence of diabetes. Material and methods: We performed densitometric (DXA) measurements, microarchitectural analyses, bone mineral density distribution, osteocyte lacunar density, and microhardness measurements in the trabeculae of the femoral head (18 individuals with T2DM and fracture, and 25 non-T2DM individuals without fracture), as well as DXA measurements, microarchitectural analyses, osteocyte lacunar density, and microhardness measurements in the regions of the superolateral femoral neck (8 individuals with T2DM without fracture, and 8 non-T2DM individuals without fracture). The surgical samples of the femoral heads from individuals who had sustained fragility fractures and had been diagnosed with T2DM prior to the appearance of the fracture were collected at surgery (Institute for Orthopedic Surgery Banjica), while their appropriate control specimens and specimens of the superolateral femoral neck (both T2DM and control) were collected during autopsies (Institute of Forensic Medicine, Belgrade). Results: The femoral neck T-score was similar between T2DM individuals and controls without fractures. However, we observed a lower femoral neck T-score in T2DM individuals who had sustained fragility fractures compared with controls. The presence of T2DM was associated with lower cortical porosity and thickness in the superolateral femoral neck, indicating weaker cortical bone. Although the trabecular microarchitecture was similar between T2DM individuals and controls at the examined sites, the presence of vascular complications in T2DM subjects contributed to the deterioration of trabecular microarchitecture. The microhardness measurements revealed lower values in both cortical and trabecular bone of the superolateral femoral neck, as well as in the trabeculae of the femoral head, in individuals with T2DM. This suggests a reduction in the overall hardness and mechanical strength of bone in T2DM. Bone mineral density distribution analysis revealed decreased calcium heterogeneity in the trabeculae of the femoral head in T2DM individuals. There were no significant differences in osteocyte lacunar density parameters between T2DM individuals and controls for the trabeculae of the femoral head and femoral neck, but the cortex of the superolateral femoral neck exhibited an altered pattern of osteocyte distribution...Uvod: Broj obolelih od dijabetesa tipa 2 (T2DM) je dostigao alarmantne razmere širom sveta, sa projekcijama koje ukazuju da će ovo hronično nezarazno oboljenje u budućnosti dostići pandemijske razmere. Sa druge strane, lekari i naučnici sve više postaju svesni povećanog rizika od preloma kod osoba sa T2DM u poređenju sa osobama bez dijabetesa. Međutim, mehanizmi koji dovode do povećane koštane fragilnosti kod osoba sa T2DM još uvek nisu potpuno razjašnjeni, a preventivni programi su nedovoljno razvijeni. Cilj: Stoga, cilj ovog istraživanja je bio da se ispitaju promene koje T2DM izaziva kako u kortikalnom tako i u trabekularnom delu vrata butne kosti, uobičajenom mestu nastanka preloma. Paralelno sa ovim istraživanjem, detaljno smo analizirali mikroarhitekturne varijacije duž superolateralnog dela vrata butne kosti iz dva razloga. Prvo, superolateralni deo vrata je uobičajeno mesto za inicijaciju frakture prilikom pada na bok, a drugo, ako mikroarhitektura superolateralnog dela vrata nije uniformna, područja sa slabijom mikroarhitekturom mogu biti dodatno oslabljena u prisustvu dijabetesa. Materijal i metode: Za potrebe ovog rada, izvršili smo denzitometrijska merenja, analizu mikroarhitekture, stepena mineralizacije koštanog tkiva, gustine mineralizovanih i nemineralizovanih osteocitnih lakuna, kao i merenje mikrotvrdoće na trabekulama glave femura (18 osoba sa T2DM i frakturom, i 25 osoba bez T2DM i frakture); obavili smo i denzitometrijska merenja, analizu mikroarhitekture, gustine mineralizovanih i nemineralizovanih osteocitnih lakuna, kao i merenje mikrotvrdoće u regionima superolateralnog dela vrata femura (8 osoba sa T2DM bez frakture i 8 osoba bez T2DM i frakture). Uzorci glave femura su dobijeni sa operacija (na Institutu za ortopedskohirurške bolesti „Banjica“) osoba sa prelomom vrata butne kosti kod kojih je pre pojave preloma postavljena dijagnoza T2DM, dok su adekvatni kontrolni uzorci i uzorci superolateralnog dela vrata femura (i T2DM i kontrolna grupa) prikupljeni tokom rutinskih obdukcija na Institutu za sudsku medicinu u Beogradu. Rezultati: T-skor vrata femura je bio sličan između osoba sa T2DM i kontrolne grupe (obe grupe bez preloma), dok smo uočili niži T-skor vrata femura kod osoba sa T2DM sa prelomom kuka u poređenju sa kontrolnom grupom. Grupa sa T2DM je pokazala manju kortikalnu poroznost i debljinu superolateralnog dela vrata butne kosti, što je ukazalo na smanjenu mehaničku otpornost kosti. Iako je generalno trabekularna mikroarhitektura bila slična kod osoba sa T2DM i kontrolne grupe na oba ispitivana mesta, prisustvo vaskularnih komplikacija kod osoba sa T2DM je dovelo i do pogoršanja trabekularne mikroarhitekture glave butne kosti. Mikrotvrdoća je bila niža i u kortikalnoj i u trabekularnoj kosti superolateralnog dela butne kosti, kao i u trabekulama glave butne kosti, što ukazuje na smanjenje ukupne tvrdoće i mehaničke otpornosti kostiju kod T2DM. Analiza mineralizacije koštanog matriksa je pokazala homogeniju raspodelu kalcijuma u trabekulama glave butne kosti kod osoba sa T2DM. Gustina osteocitnih lakuna je bila slična kod osoba sa T2DM i kontrolne grupe u trabekulama glave butne kosti. Međutim, kortikalna kost superolateralnog dela vrata butne kosti je pokazala promene u gustini osteocitnih lakuna. Konkretno, pronađen je manji broj nemineralizovanih osteocitnih lakuna po koštanoj površini u endokortikalnim i periostealnim regijama superolateralnog dela vrata butne kosti kod grupe sa T2DM u poređenju sa odgovarajućim regijama u kontrolnoj grupi..

Geometric characteristics of the portals of the katholika in the Studenica, Sopoćani and Dečani monasteries in medieval Serbia

This paper analyzes the geometric characteristics of the church portals in the Serbian medieval monasteries of Studenica (12 c), Sopoćani (13 c), and Dečani (14 c). The comparative analysis of the portals, regarding their compositions of structural elements (jambs, colonettes, lesenes, and archivolts) and dimensional articulation of ground floor plans and archivolts, is based on the precise digital data collected by terrestrial laser scanning and on the reliable literature and the drawings prepared by architectural conservators. The paper shows that medieval architects applied harmonious proportioning in the design, characteristic of the Romanesque portals along the Adriatic coast. The proposed parametric interpretation of geometric characteristics of analyzed medieval church portals has the potential for use in Heritage building information modeling (HBIM), which is needed to reconstruct and preserve these or other cultural heritage monuments.Rad je prezentovan na konferenciji, ali nije publikovan, sa namerom da se proširi i publikuje u časopisu Wo

Mitotic crossover promotes leukemogenesis in children born with TEL-AML1 via the generation of loss of heterozygosity at 12p

TEL-AML1 (ETV6-RUNX1) fusion gene which is formed prenatally in 1% of the newborns, is a common genetic abnormality in childhood Bcell precursor acute lymphoblastic leukemia. But only one child out of a hundred children born with this fusion gene develops leukemia (bottleneck phenomenon) later in its life, if contracts the second mutation. In other words, out of a hundred children born with TEL-AML1 only one child is at risk for leukemia development, which means that TEL-AML1 fusion gene is not sufficient for overt leukemia. There is a stringent requirement for a second genetic abnormality for leukemia development and this is the real or the ultimate cause of the leukemia bottleneck phenomenon. In most cases of TEL-AML1+ leukemia, the translocation t(12;21) is complemented with the loss of the normal TEL gene, not involved in the translocation, on the contralateral 12p. The loss of the normal TEL gene, i.e. loss of heterozygosity at 12p, occurs postnatally during the mitotic proliferation of TEL-AML1+ cell in the mitotic crossing over process. Mitotic crossing over is a very rare event with a frequency rate of 10–6 in a 10 kb region. The exploration and identification of the environmental exposure(s) that cause(s) proliferation of the TELAML1+ cell in which approximately 106 mitoses are generated to cause 12p loss of heterozygosity, i.e. TEL gene deletion, may contribute to the introduction of preventive measures for leukemia