University of Rijeka

About: University of Rijeka is a education organization based out in Rijeka, Croatia. It is known for research contribution in the topics: Population & Tourism. The organization has 3471 authors who have published 7993 publications receiving 110386 citations. The organization is also known as: Rijeka University & Sveučilište u Rijeci.

Marine AChE inhibitors isolated from Geodia barretti: natural compounds and their synthetic analogs

Abstract: Barettin, 8,9-dihydrobarettin, bromoconicamin and a novel brominated marine indole were isolated from the boreal sponge Geodia barretti collected off the Norwegian coast. The compounds were evaluated as inhibitors of electric eel acetylcholinesterase. Barettin and 8,9-dihydrobarettin displayed significant inhibition of the enzyme, with inhibition constants (Ki) of 29 and 19 μM respectively towards acetylcholinesterase via a reversible noncompetitive mechanism. These activities are comparable to those of several other natural acetylcholinesterase inhibitors of marine origin. Bromoconicamin was less potent against acetylcholinesterase, and the novel compound was inactive. Based on the inhibitory activity, a library of 22 simplified synthetic analogs was designed and prepared to probe the role of the brominated indole, common to all the isolated compounds. From the structure-activity investigation it was shown that the brominated indole motif is not sufficient to generate a high acetylcholinesterase inhibitory activity, even when combined with natural cationic ligands for the acetylcholinesterase active site. The four natural compounds were also analysed for their butyrylcholinesterase inhibitory activity in addition and shown to display comparable activities. The study illustrates how both barettin and 8,9-dihydrobarettin display additional bioactivities which may help to explain their biological role in the producing organism. The findings also provide new insights into the structure-activity relationship of both natural and synthetic acetylcholinesterase inhibitors.

Global Financial Crisis and VaR Performance in Emerging Markets: A Case of EU Candidate States - Turkey and Croatia

Abstract: We investigate the relative performance of a wide array of Value at Risk (VaR) models with the daily returns of Turkish (XU100) and Croatian (CROBEX) stock index prior to and during the ongoing financial crisis. In addition to widely used VaR models, we also study the behaviour of conditional and unconditional extreme value theory (EVT) and hybrid historical simulation (HHS) models to generate 95, 99 and 99.5% confidence level estimates. Results indicate that during the crisis period all tested VaR model except EVT and HHS models seriously under-predict the true level of risk, with EVT models doing so at a higher cost of capital compared to HHS model.

Modeling influence of hysteretic moisture behavior on distribution of chlorides in concrete

Abstract: Aggressive environmental conditions, such as exposure to the sea climate or use of de-icing salts, can have a considerable influence on the durability of reinforced concrete structures due to corrosion-induced damage of reinforcement. Recently, the coupled 3D chemo-hygro-thermo-mechanical (CHTM) model for simulation of processes related to the chloride induced corrosion of steel reinforcement in concrete was developed. In the model, it is assumed that for wetting and drying of concrete, the transport of water is controlled by a single sorption curve. However, it is well known that concrete exhibits a hysteretic moisture behaviour, which significantly influences the distribution of moisture and chlorides. To account for the hysteretic moisture behaviour of concrete and for simulating a more realistic time and space distribution of moisture, the CHTM model was further improved. The proposed hysteretic model is implemented into a 3D finite element code and it is validated using a numerical example, which shows reasonably good agreement with the available test results. Similar to what is observed in the experimental tests, it is shown that due to the wetting and drying of the concrete surface, the peak concentration of chloride moves progressively deeper into the concrete specimen.

Ethics, social responsibility and business performance in a transition economy

Abstract: Purpose – This paper seeks to explore the perceived role of ethics and social responsibility in achieving the organisational effectiveness among managers in transition economy, the impact of demographic characteristics of managers on it, and the relationship between managers' attitudes towards the role of ethics in business and the firm's performance.Design/methodology/approach – The research was been done by a survey method based on a sample of managers from the most successful Croatian firms. In order to establish the attitudes of Croatian managers on social responsibility, the PRESOR scale was used.Findings – It has been established that among Croatian managers a positive attitude on the importance of ethics and social responsibility for the firm's success prevails. Except for the age, the connection between other individual variables and the perception of the role of ethics and social responsibility in doing business was not established. A positive correlation between the perception of the role of eth...