Statistika RUNG

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Ključne besede: fotoaktivnost, fotokataliza, katalizatorji, kemijska kinetika, materiali, piroklorna struktura, rekombinacija, železove spojine
Objavljeno: 30.12.2015; Ogledov: 12965; Prenosov: 227
Polno besedilo
Ogledov v tednu: 954

Opis: This thesis represents a comprehensive study, giving first extensive information on the hydrogeological and speleological characteristics of the spring cave Slatinski Izvor and its catchment area. The researched spring is located in the Poreče basin of West-Central Macedonia, in the river valley of Slatinska Reka. The wider area around the spring belongs to two tectonic units. The Slatinski Izvor spring is situated on the Pelagonian horst anticlinorium, which is composed of carbonate rocks. The second is the Western Macedonian zone, and it is composed of non-carbonate rocks. The spring represents a significant potential for water supply for the settlement Slatina. Prior to this research only some basic information about the karst aquifer in Precambrian dolomite marbles was available. Therefore, my goal was to ensure better understanding of the functioning of the karst system in the recharge area of the spring, assessment of its vulnerability to various pollution sources, as well as study of karst development of the area. Because karst aquifers have unique hydrogeological characteristics and specific nature, they also require specifically adapted investigation methods. In order to reach the main goal, speleological investigations, hydrological methods, hydrochemical methods and tracer test were used. A monitoring network was combined with regular samplings for major and trace elements analysis, which enabled considerable advances in understanding the functioning of the karst system. The data from two-year period (December 2011 – November 2013) was compared and analyzed. The controlling of the karst development in the study area mostly depends on the tectonic and geologic conditions. Incision of Slatinska Reka is the main controlling factor in cave development by lowering the base level of karst terrains. All investigated caves (Gorna Slatinska, Slatinska II, Ovčarska Peštera, Puralo, Slatinski Izvor) have “normal” epigenic karst development. Slatinski Izvor is the youngest cave. The Slatinski Izvor spring serves as a cave entrance for the same cave and, represents the outflow of groundwater from the karst system. A conceptual model of the karst system of the study area was developed. The Slatinski Izvor spring has typical karst hydrological regime. The karst system is well developed by conduits and rains infiltrated into vadose zone flow rapidly towards the spring. The travel time of low mineralized water within the system corresponds well with the results from an artificial tracer test. Performed artificial tracer test confirmed that the Slatinski Izvor spring is recharged by allogenic stream. The dominant apparent flow velocity of 250 m/h, a single peak of the tracer breakthrough curve and more than 87% of tracer recovered indicate a rapid conduit flow and high vulnerability of the observed drinking water source. Analysis of spatial and temporal variations of physical and chemical parameters show that waters in the study area had different origin and were transmitted along different flow paths. The origin of the water of the Slatinski Izvor spring is from non-carbonate area, but the influence of mixed limestone-dolomite sequence in the carbonate area is significant. The results point out to short residence time of the water in the karst aquifer. The anthropogenic impact in the study area is insignificant which is reflected in the good water quality. In order to preserve it, land surface zoning was performed in terms of groundwater and spring water vulnerability to pollution according to the hydrogeological research. A comprehensive research with a combined use of various research tools presents an innovative approach and a new contribution to the Macedonian karstological science. Applied methods proved to be successful for to study of the karst system. Finally, the results of the study have clear applicative significance in terms of drinking water management.
Ključne besede: karst hydrology, cave, speleological investigation, hydrochemistry, tracer test, spring Slatinski Izvor
Objavljeno: 14.10.2016; Ogledov: 14368; Prenosov: 70
Polno besedilo
Ogledov v tednu: 951

Opis: Calcium batteries represent a promising alternative to lithium metal systems. The combination of the low redox potential and low cost and the energy-dense calcium anode (2073 mAh/cm3, similar to 2044 mAh/cm3 for Li) with appropriate low-cost cathode materials such as sulfur could produce a game-changing technology in several fields of applications. In this work, we present the reversible activity of a proof-of-concept Ca/S battery at room temperature, characterized by a surprising medium-term cycling stability with low polarization, promoted by the use of a simple positive electrode made of sulfur supported on an activated carbon cloth scaffold, and a state-of-the-art fluorinated alkoxyborate-based electrolyte. Insights into the electrochemical mechanism governing the chemistry of the Ca/S system were obtained for the first time by combining X-ray photoelectron spectroscopy and X-ray absorption spectroscopy. The mechanism implies the formation of different types of soluble polysulfide species during both charge and discharge at room temperature, and the formation of solid CaS at the end of discharge. The reversible electrochemical activity is proven by the reformation of elemental sulfur at the end of the following charge. These promising results open the way to the comprehension of emerging Ca/S systems, which may represent a valid alternative to Mg/S and Li/S batteries.
Ključne besede: Calcium/Sulfur Batteries EXAFS, XANES
Objavljeno: 17.10.2020; Ogledov: 37; Prenosov: 0
Polno besedilo
Ogledov v tednu: 37

Opis: Cartographic approach to syntax models strict universal word orders with a universal hierarchy of functional projections. For example, universal order of adjectives [Adjs] (cf. Hetzron 1978, Sproat & Shih 1991, etc.), supposedly comes from a universal hierarchy of FPs which host specific types of Adjs (Scott 2002). Adopting this as a premise, we explore the origin of this hierarchy, i.e., the origin of the specific ordering of individual FPs in the functional hierarchy and thus the origin in which Adjs end up being linearized.
Ključne besede: adjectives, cartography, universal hierarchy of functional projections, general cognition, experimental syntax, cognitive foundations of syntax
Objavljeno: 16.10.2020; Ogledov: 30; Prenosov: 0
Polno besedilo
Ogledov v tednu: 30

Ključne besede: functionalization, modification, adsorption, extended X-ray absorption fine structure, materials
Objavljeno: 17.10.2020; Ogledov: 30; Prenosov: 0
Ogledov v tednu: 30