Sofia University

About: Sofia University is a education organization based out in Sofia, Bulgaria. It is known for research contribution in the topics: Large Hadron Collider & Laser. The organization has 8533 authors who have published 15730 publications receiving 306320 citations. The organization is also known as: University of Sofia & BFUS.

Gold catalysts supported on ceria and ceria–alumina for water-gas shift reaction

Abstract: Gold-supported catalysts on ceria and ceria–alumina with different ratios in the water-gas shift reaction were studied. It was shown that the addition of alumina leads to the deeper oxygen vacancies formation, detected by Raman and TPR measurements. It was established an increase of the ceria dispersion and as well as slightly increase of the gold particle size. In the presence of alumina after catalytic operation the dispersion of gold and ceria practically does not change. The lower WGS activity on gold/ceria–alumina can be explained on the basis of reduction–oxidation cycle of the reaction. It was established no efficiency re-oxidation of the catalyst surface at the temperatures of the reaction test by the water vapour and we consider this as a main reason of the lower catalytic activity.

Fact Checking in Community Forums.

Abstract: Community Question Answering (cQA) forums are very popular nowadays, as they represent effective means for communities around particular topics to share information. Unfortunately, this information is not always factual. Thus, here we explore a new dimension in the context of cQA, which has been ignored so far: checking the veracity of answers to particular questions in cQA forums. As this is a new problem, we create a specialized dataset for it. We further propose a novel multi-faceted model, which captures information from the answer content (what is said and how), from the author profile (who says it), from the rest of the community forum (where it is said), and from external authoritative sources of information (external support). Evaluation results show a MAP value of 86.54, which is 21 points absolute above the baseline.

From syn- to post-orogenic Tertiary extension in the north Aegean region: Constraints on the kinematics in the eastern Rhodope–Thrace, Bulgaria–Greece and the Biga Peninsula, NW Turkey

Abstract: The Aegean region experienced back-are extension related to the Hellenic subduction system at least from the latest Oligocene to the present. We document Tertiary extension-related kinematics in the north Aegean, in the eastern Rhodope–Thrace of Bulgaria–Greece and the Biga Peninsula of NW Turkey. A regionally consistent NNE–SSWto NE–SW-oriented kinematic direction, delineated in both areas by stretching lineations and associated ductile–brittle shear fabrics in exhumed metamorphic domes beneath detachments, suggests that they were kinematically coupled during the Tertiary extension. This kinematic framework, combined with regional geochronological data and the stratigraphic record in hanging-wall supradetachment basins, defines an extensional history that includes synand post-orogenic episodes from Paleocene to Miocene times. Paleocene–early Eocene synorogenic extension in the Kemer micaschists of the northern Biga Peninsula and in the Kesebir–Kardamos dome in Rhodope–Thrace accommodated gravitationally induced hinterland-directed exhumation of the orogenic stack, coeval with the closure of the Vardar Ocean. Then, following collision within the region, it was succeeded by latest Oligocene–Early Miocene extension as recorded in the Kazdaǧ Massif in the southern Biga Peninsula, which overlaps the Aegean back-arc post-orogenic extension, widely recognized in the central Aegean and southern Greek Rhodope. The protracted record of extension is interpreted to reflect progressive exhumation of the orogenic wedge along the Eurasian plate margin. Southward migration of extension and magmatism across the study areas accounts for sequential shift and roll-back of the subduction boundary at that margin, from the latest Cretaceous in the Rhodope to its present position at the Hellenic trench. The results allow recognition of the investigated areas as an important extensional domain in the north Aegean region, which underwent Tertiary synand post-orogenic extension. The Aegean region has experienced back-arc extension related to the Hellenic subduction system since the latest Oligocene to the present (e.g. McKenzie 1978; Le Pichon & Angelier 1979; Meulenkamp et al. 1988). Seismic and geodetic data indicate that this active tectonic regime developed above the northward subducting East Mediterranean slab, plunging under the Eurasian plate (Taymaz et al. 1991; Jackson 1994; Le Pichon et al. 1995; McClusky et al. 2000). Since the first recognition of metamorphic core complexes of cordilleran-type in the Cyclades (Lister et al. 1984), the Aegean region has been considered as a natural laboratory for studying processes of crustal extension and exhumation of metamorphic terranes (Jolivet & Patriat 1999; Jolivet & Faccenna 2000). Many studies of metamorphic core complexes in the Aegean region and its surroundings (e.g. south Rhodope, Cyclades and Menderes Massif) have documented pronounced latest Oligocene–Miocene extension (e.g. Dinter & Royden 1993; Sokoutis et al. 1993; Bozkurt & Park 1994; Gautier & Brun 1994; Hetzel et al. 1995). The onset of the Aegean extension in the Balkan area and within the Rhodope complex was originally set in the Late Eocene–Oligocene from stratigraphic constraints (Burchfiel et al. 2003), or in the latest Early Oligocene from radiometric dating (Lips et al. 2000). However, the extensional regime in the Rhodope complex obviously started earlier, in pre-Eocene times (Bonev et al. 2006a), implying a protracted Cenozoic extensional history of the north Aegean domain. Ductile shear fabrics associated with stretching lineations in the footwall mylonites beneath detachments were used in the central Aegean region both to establish the kinematic directions of extension (e.g. Gautier & Brun 1994; Vandenberg & Lister 1996; From: TAYMAZ, T., YILMAZ, Y. & DILEK, Y. (eds) The Geodynamics of the Aegean and Anatolia. Geological Society, London, Special Publications, 291, 113–142. DOI: 10.1144/SP291.6 0305-8719/07/$15.00 # The Geological Society of London 2007. Bozkurt & Park 1997; Ring et al. 1999), and in comparison with the present deformation (Jolivet et al. 1994; Walcott & White 1998; Jolivet 2001). Generally, a dominant north–south to NE–SW direction of extension characterizes the central–southern Aegean region (Fig. 1). In contrast, only few kinematic data on the direction of ductile extension are available for the northern Aegean region, when compared with extensive studies on fault kinematics and basin patterns (e.g. Dinter & Royden 1993; Bozkurt 2001; Koukouvelas & Aydin 2002). In this paper, we therefore present a regional kinematic study of exhumed basement rocks in the northernmost Aegean region. The key investigated areas are the eastern Rhodope–Thrace region of the Rhodope Massif of southern Bulgaria and northeastern Greece, and the Biga Peninsula of NW Turkey (Fig. 2). In the eastern Rhodope–Thrace region, the investigation combines kinematics of large-scale extensional domes in Bulgaria with additional data from Greece used to support the kinematic frame. In the Biga Peninsula, the study encompasses a northern domain along the Marmara Sea coast with previously undocumented kinematics, and the southern domain of the Kazdaǧ Massif, where further details on the kinematics are provided. We summarize the Tertiary kinematics in both areas, focusing on ductile then brittle extensional structures, to constrain the poorly known extension-related kinematic framework in this part of the Aegean domain. Finally, based on the available temporal constraints on the distinct processes involved, we discuss the kinematic frame and geodynamic context of the extensional tectonics, which collectively delineate episodes of synand post-orogenic extension. Large-scale tectonic setting and geological background of the north Aegean region Belonging to the Alpine–Himalayan mountain chains, the Rhodope Massif and the Biga Peninsula lie in the northernmost sector of the Aegean region, in the Eastern Mediterranean domain (Fig. 2). The orogenic belt exposed in this region results from the Mesozoic–Cenozoic closure of several oceanic basins belonging to the Tethyan realm, and the subsequent collision between the bordering microcontinents (e.g. Robertson & Dixon 1984; Dercourt et al. 1986; Robertson et al. 1996; Stampfli & Borel 2004). Both areas occur immediately north of the main regional suture zones, namely, the Vardar and the Izmir–Ankara sutures, and the Intra-Pontide suture propagates through the Biga Peninsula (e.g. Okay & Tuysuz 1999; Stampfli 2000). The Vardar suture zone separates the Rhodope Massif and Serbo-Macedonian massifs in the north, from the inner Hellenides in the south. The Rhodope Massif is limited in the north by the Late Alpine Maritza dextral strike-slip fault, against the Late Cretaceous volcanic arc of the Sredna Gora Zone. It consists of a metamorphic basement comprising pre-Alpine and Alpine units of continental and oceanic affinities, derived from magmatic and sedimentary protoliths. This metamorphic basement is intruded by Late Cretaceous to Early Miocene granitoids (e.g. Meyer 1968; Soldatos & Christofides 1986; Del Moro et al. 1988; Dinter et al. 1995; Peytcheva et al. 1998; Pe-Piper & Piper 2002), and covered by Late Cretaceous to Neogene sedimentary and volcanic sequences (e.g. Ivanov & Kopp 1969; Boyanov & Goranov 2001), including Late Eocene–Oligocene volcanic and volcano-sedimentary successions (e.g. Innocenti et al. 1984; Harkovska et al. 1989; Yanev & Bardintzeff 1997). The Rhodope metamorphic complex was formed as a stack of crustal-scale ductile nappes during the Late Fig. 1. Senses of ductile shear of Oligocene–Miocene age within the exhumed metamorphic basement in the Aegean region. Data sources: Dinter & Royden (1993); Schermer (1993); Gautier & Brun (1994); Jolivet et al. (1994); Hetzel et al. (1995); Bozkurt & Park (1997); Walcott & White (1998); Wawrzenitz & Krohe (1998); Kilias et al. (1999); Ring et al. (1999); Lips et al. (2000); Okay & Satir (2000b); Beccaletto & Steiner (2005). RM, Rhodope Massif; A-CM, Attica–Cycladic Massif; MM, Menderes Massif; KGM, Kazdaǧ Massif; KM, Kemer micaschists; NAFS, North Anatolian Fault System. N. BONEV & L. BECCALETTO 114