The age of the Dinaride Ophiolite Belt: Derived olistostrome melange at the northern slope of Moračka Kapa (Montenegro)

This paper presents the first results of a palynological investigation of the Dinaride Ophiolite Belt - derived olistostrome melange at the northern slope of Moračka Kapa (Montenegro). The analysis of microfloral association provided a reconstruction of the Late Jurassic sedimentation conditions and depositional environment in the Morača Kapa Unit. The samples (8) collected from the different parts of ophiolite matrix yielded palynomorph assemblages (fossil spores, pollen grains and dinoflagellates) of the Upper Jurassic age. The uppermost part of the ophiolite suite on the presented palynomorphs could also indicate the lowermost Lower Cretaceous. These palynological results provide a very interesting framework of these widespread, but poorly stratigraphically understood sediments. The paleoecological results suggest humid and subtropical conditions in the hinterland

Likvefakcija mekog mrkog uglja kosovskog basena

The behavior of Kosovo Basin (Yugoslavia) soft brown coal was studied during a direct liquefaction process by catalytic hydrogenation. A stream of hydrogen was passed through a tetralin dispersion of the pulverized coal in the presence of commercial extruded hydrogenating-desulphurizing cobalt-moly­bdenum/alumina catalyst. The experiments were carried out in the temperature range between 365 and 440°C at 13.5 and 15.0 MPa, the reactants being kept at selected stationary working conditions for 1-8 hrs. The yields of liquid products soluble in n-heptane (light oils), asphaltenes (n-heptane insoluble liquid products) and the solid coal residue served as a basis for the estimation of coal reactivity and for the calculation of total coal conversion. The liquid product yields varied substantially depending on the reaction temperature and the residence time. The total conversion under most of the applied reaction conditions was found to be around 80%, the highest (~86%) being observed with the longest, 8 h residence time. Various types of grains of modified coal and newly formed types of coal grains, as well as mineral matter were identified by micropetrographic analysis, indicating the release of gases in the initial stages of hydrogenation and the formation of semi-coke and coke by the polymerization of liquid products in the later reaction stages.Ispitivano je ponašanje mekog mrkog uglja Kosovskog basena (Jugoslavija) pri direktnoj likvefakciji. Katalitička hidrogenizacija izvođena je u protočnom šaržnom reaktoru propuštanjem vodonika kroz suspenziju tetralina i usitnjenog uglja, u prisustvu komercijalnog presulfidiziranog CO-MO/AI2O3 katalizatora. Eksperimenti su izvođeni na temperaturi 365 i 440°C, pritisku 13,5 i 15,0 MPa, u trajanju 1-8 sati. Reaktivnost uglja je procenjivana i ukupna totalna konverzija izračunavana je na osnovu prinosa tečnih proizvoda rastvornih u n-heptanu (laka ulja), asfaltena (proizvodi nerastvorni u n-heptanu) i čvrstog ostatka. Konverzija uglja pri navedenim uslovima iznosila je oko 80 %, a najveća je bila (~86 %) pri najdužem reakcionom vremenu. Mikropetrografskom analizom identifikovane su različite vrste zrna modifikovanog uglja kao i novo stvoreni tipovi zrna uglja kao i mineralnog materijala. Dobijeni rezultati ukazuju da se gasovi oslobađaju u početnim fazama hidrogenizacije, a da polimerizacijom tečnih proizvoda polu-koks i koks postaju u kasnijim fazama hidrogenizacije

Likvefakcija mekog mrkog uglja kosovskog basena

The behavior of Kosovo Basin (Yugoslavia) soft brown coal was studied during a direct liquefaction process by catalytic hydrogenation. A stream of hydrogen was passed through a tetralin dispersion of the pulverized coal in the presence of commercial extruded hydrogenating-desulphurizing cobalt-moly­bdenum/alumina catalyst. The experiments were carried out in the temperature range between 365 and 440°C at 13.5 and 15.0 MPa, the reactants being kept at selected stationary working conditions for 1-8 hrs. The yields of liquid products soluble in n-heptane (light oils), asphaltenes (n-heptane insoluble liquid products) and the solid coal residue served as a basis for the estimation of coal reactivity and for the calculation of total coal conversion. The liquid product yields varied substantially depending on the reaction temperature and the residence time. The total conversion under most of the applied reaction conditions was found to be around 80%, the highest (~86%) being observed with the longest, 8 h residence time. Various types of grains of modified coal and newly formed types of coal grains, as well as mineral matter were identified by micropetrographic analysis, indicating the release of gases in the initial stages of hydrogenation and the formation of semi-coke and coke by the polymerization of liquid products in the later reaction stages.Ispitivano je ponašanje mekog mrkog uglja Kosovskog basena (Jugoslavija) pri direktnoj likvefakciji. Katalitička hidrogenizacija izvođena je u protočnom šaržnom reaktoru propuštanjem vodonika kroz suspenziju tetralina i usitnjenog uglja, u prisustvu komercijalnog presulfidiziranog CO-MO/AI2O3 katalizatora. Eksperimenti su izvođeni na temperaturi 365 i 440°C, pritisku 13,5 i 15,0 MPa, u trajanju 1-8 sati. Reaktivnost uglja je procenjivana i ukupna totalna konverzija izračunavana je na osnovu prinosa tečnih proizvoda rastvornih u n-heptanu (laka ulja), asfaltena (proizvodi nerastvorni u n-heptanu) i čvrstog ostatka. Konverzija uglja pri navedenim uslovima iznosila je oko 80 %, a najveća je bila (~86 %) pri najdužem reakcionom vremenu. Mikropetrografskom analizom identifikovane su različite vrste zrna modifikovanog uglja kao i novo stvoreni tipovi zrna uglja kao i mineralnog materijala. Dobijeni rezultati ukazuju da se gasovi oslobađaju u početnim fazama hidrogenizacije, a da polimerizacijom tečnih proizvoda polu-koks i koks postaju u kasnijim fazama hidrogenizacije

Direct hydroliquefaction of a low rank soft brown coal

The behaviour of the soft brown coal from the Kostolac Mine (Serbia, Yugoslavia) was investigated during hydroliquefaction carried out in a batch reactor by direct catalytic hydrogenation of the pulverized coal (- 160 μm) dispersed in tetralin. The effects of temperature (ranging from 365 to 440°C), pressure (13.5 to 15.0 MPa) and residence time (1 to 8 h) on the yield of individual liquefaction products as well as the petrographic composition of the coal residues were closely followed by separation and analysis of the products. These consisted of liquid products soluble in n-heptane (light oils), n-heptane insoluble products (asphaltenes), the solid coal residue and gaseous products. A good reactivity of this soft brown coal was observed. The yield of liquid products varied from 23 to 64 wt.% (based on dry ash-free coal). A total coal conversion of 80 to 86% was achieved. Petrographic composition and optical properties of the solid coal residues were analyzed microscopically in order to establish the character and intensity of the coal changes. The solid residues were found to consist of 12 various grain categories. The low proportions of unreacted or partly reacted coal grains confirmed the good reactivity of the Kostolac soft brown coal in the applied liquefaction process

Etiology of ischemic stroke among young adults of Serbia

Background/Aim. Etiology of ischemic stroke (IS) among young adults varies among countries. The aim of the study was to investigate the causes and risk factors of IS in the young adults of Serbia. Methods. A total of 865 patients with IS, aged 15 to 45 years, were treated throughout the period 1989-2005. Etiologic diagnostic tests were performed on the patient by the patient basis and according to their availability at the time of investigation. The most likely cause of stroke was categorized according to the TOAST (Trial of ORG 10172 in Acute Stroke Treatment) criteria. Results. There were 486 men and 379 women, with 19% of the patients ≤ 30 years old. Large artery arteriosclerosis and small artery disease were confirmed in 14% of the patients, and embolism and other determined causes in 20%. Undetermined causes made up 32% of the patients, mostly those (26%) with incomplete investigations. Smoking (37%), hypertension (35%) and hyperlipidemia (35%) were the most common risk factors. Rheumatic heart diseases and prosthetic valves were the most common causes of IS. Arterial dissections and coagulation inhibitors deficiency were detected in a small number of patients. Conclusion. Etiology of IS among Serbian young adults shares characteristics of those in both western and less developed countries

Liquefaction behaviour of Kolubara soft brown coal

The behaviour of Kolubara soft brown coal during direct liquefaction by catalytic hydrogenation was studied and was compared with the Banovići brown coal investigated previously. A sample of washed and dried coal was ground dry, or was ground in the presence of different liquids. Addition of water during grinding resulted in a somewhat coarser granular composition, while n-heptane did not have a noticeable effect. High reactivity of the soft brown coal, which initially was indicated by thermal analysis, was confirmed by high yields of liquid products, particularly of oils soluble in n-heptane. The solid liquefaction residues did not contain pyrolytic carbon and cenospheres, and contained a low proportion of humoplasts indicating the high liquefaction efficiency of the coal in spite of its high content of xylite