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.

Experimental and numerical study of the compact heat exchanger with different microchannel shapes

Abstract: Experimental and numerical analysis of heat transfer and fluid flow in the compact heat exchanger has been done in this paper. In an open circuit wind tunnel, developed on purpose for this investigation, the measurement of working media temperatures and mass flow rates for heat exchanger with microchannel coil has been accomplished. In accordance with the heat exchangers used for experiments, numerical 3D simulation of adequate geometry shapes has been done. With utilization of air/water side numerical simulation, more detailed results have been achieved in relation to the simulation that assumes constant temperature or constant heat flux on the pipe wall. Good agreement between experimentally measured and numerically calculated results has been accomplished. The influence of different microchannel shapes on heat transfer effectiveness and pressure drop has been studied numerically. Comparison of results has been made accompanied by the discussion and final conclusions.

The Croatian–Japanese Joint Research Project on Landslides: Activities and Public Benefits

Abstract: The main activities of the research groups involved in the Croatian–Japanese joint research project on “Risk Identification and Land-Use Planning for Disaster Mitigation of Landslides and Floods in Croatia” include investigations of recent landslides using landslide monitoring, the establishment and development of early warning systems for landslides and the definition of hazard zones using a methodology for assessing susceptibility and hazards based on local geological and landslide conditions. This project is also designated as on-going IPL project 161. The final objective of the joint research is the development of risk mitigation measures that can be instituted through urban planning. Dissemination and use of the results should ensure significant benefits for the local and regional communities that are directly and indirectly threatened by landslides.

Gravitational Chern?Simons Lagrangian terms and spherically symmetric spacetimes

Abstract: We show that for general spherically symmetric configurations, contributions of broad class of gravitational and mixed gauge-gravitational Chern–Simons (CS) terms to the equations of motion vanish identically in D > 3 dimensions. This implies that such terms in the action do not affect Birkhoff's theorem or any previously known spherically symmetric solutions. Furthermore, we investigate the thermodynamical properties using the procedure described in an accompanying paper. We find that in the D > 3 static spherically symmetric case, CS terms do not contribute to the entropy either. Moreover, if one requires only for the metric tensor to be spherically symmetric, letting other fields be unrestricted, the results extend almost completely, with only one possible exception—CS Lagrangian terms in which the gravitational part is just the n = 2 irreducible gravitational CS term.

Oxidative stress parameters in different rat brain structures after electroconvulsive shock-induced seizures

Abstract: Electroconvulsive therapy has been used in the treatment of psychiatric disorders since the 1930s, but little progress has been made in understanding the cellular mechanisms underlying its therapeutic and adverse effects. Electroconvulsive shock (ECS) in animals provides a common experimental model for studying the effects of electroconvulsive therapy in humans. In order to examine the changes of the brain oxidative stress parameters in several brain structures in the early time period after ECS-induced seizures, the levels of lipid peroxidation as well as superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities in the rat hippocampus, cerebellum, frontal cortex and the pons/medulla region were determined at different time points during the first 24 h after single ECS-induced seizures. In the hippocampus and cerebellum the levels of lipid peroxidation were unchanged, while the SOD and GSH-Px activities were significantly increased. Levels of lipid peroxidation and the activities of SOD and GSH-Px were not statistically changed in the pons/medulla region. Levels of lipid peroxidation in the frontal cortex were significantly higher in comparison to the control group at all time points examined while the SOD and GSH-Px activities were not statistically changed. In conclusion, the results of the present study indicate that single ECS causes the rat brain structure-specific alterations in the levels of lipid peroxidation as well as in the SOD and GSH-Px activities at different time points within the first 24 h after the seizures induction. Oxidative lipid damage was evident only in the frontal cortex, while the hippocampus, cerebellum and the pons/medulla region remained oxidatively unaffected in our experimental conditions.