This paper presents research on hydrodynamics and mass transfer in a packed absorption column. Experimental data on dry column pressure drop, flooding point, and efficiency of absorption of CO2 in water is obtained on a lab-scale absorption column packed with Raschig rings. Auxiliary parts of equipment together with chemical analyses provide simple monitoring and collecting the data. All obtained data were used to test different mathematical models for a given problem, i.e. for determination of the dry column pressure drop, flooding point and the overall gas transfer unit height. For dry column pressure drop, models developed primarily for packed columns described the data the best, with the Billet model generating a 6.54 % mean error, followed by Mackowiak and Stichlmair models. In flooding point calculations, empirical models were tested and models of Lobo, Leva and Takahshi gave the best results. Mass transfer (absorption) experiments gave expected results, since absorption efficiency increased with the increase in the liquid/gas flow rate ratio, i.e. with approaching the flooding point. The Onda?s model was used to calculate partial mass transfer coefficients in liquid and gas phases based on which the height of the overall gas transfer unit was estimated and subsequently compared with the experimental data. Deviation of calculated and experimental results for the height of the overall gas transfer unit is in the expected range of 0-20 %, with mean value of 15.5 %. In conclusion, the available models for determination of the investigated hydrodynamics and mass transfer parameters in packed absorption columns gave adequate results in comparison to the experimental values.

With the increasing participation of renewable energy sources in the production of electricity, the answer to the question of the necessary operating reserve capacity in power systems is becoming more and more complicated. The very fact of the variability of driving energy (sun, wind, water) in photovoltaic power plants, wind power plants and small hydropower plants makes the required operating reserve capacity variable. As the electric power system itself is stochastic, the inclusion of renewable energy sources in the operation of electric power systems emphasizes its stochastic characteristic even more. For this reason, the need for operating reserve in electric power systems from the aspect of renewable energy sources and with them in connection with micro-grids, is best solved using the tools of probability, that is, statistics and estimation. The issue of operating reserve in the power system was investigated by Bayesian statistics, which connects the simultaneous occurrence of a random variable (available capacity of renewable energy sources in micro-grids) with a statistical variable (load in micro-grids). The result of this research is the probability of a deficit or surplus of available energy in micro-grids, and the consequence of that probability is the probability of the need and degree of engagement of the operating reserve in the power system using system’s thermal electric power plants and/or hydro electric power plants.

Welded structures place increasing demands on the level of increased resistance to fracture. A large number of fractures of welded structures, which occur during exploitation at a stress level below of the allowable, indicates the danger of brittle fracture. The assessment of brittle fracture susceptibility was analyzed by testing Sharpy specimens, and the total impact energy, components of total impact energy (crack energy initiation and crack energy propagation) were used as parameters in the analysis.

Multi-material design was developed as a modern design concept for lightweight structures (Lightweight design - LW) which aims to integrate different types of materials into one structure. The main problem when joining sheets made of different, i.e. dissimilar materials, primarily steel and aluminum alloys, are the different mechanical, physical and chemical properties of the materials being joined. Through this paper, the state of the art will be analyzed when it comes to modern technologies for joining steel and aluminum alloys sheets. The term "modern joining technique" refers to all innovative joining technologies that have been developed or have seen significant application in the last few years.

Social robots are unique as persuasive agents due to their embodiment, which increases their capacity to promote behavioral and motivational change [3],[4]. We therefore designed an interaction between a humanoid social desktop robot — QT (Fig. 1) — and older adults aimed at promoting positive life changes through guided self-reflective exercises. We focus on older adults as while much work has focused on using robots with this population to ameliorate loneliness and depressive symptoms through interactions with the technology (e.g., [2]), few studies have focused on using robots to increase feelings of fulfillment, value, and meaning in helping older adults thrive (and not just cope). However, research done with college students shows that robots can be used in positive psychology interventions to increase flourishing [1].

Background: Cognitive dysfunctions are considered as a poor prognostic factor that influence health-related quality of life in multiple sclerosis. Objective: The aim of the study was to evaluate the impact of cognitive impairment on the quality of life in multiple sclerosis patients. Methods: This study included 60 MS patients treated at the Department of Neurology, Clinical Center University of Sarajevo. Inclusion criteria were clinically definite diagnosis of multiple sclerosis, 18 years of age or older and were able to give written informed consent. Cognitivefunction was evaluated by the Montreal Cognitive Assessment (MoCa) screening test. Quality of life was evaluated by SF36 questionnaire. Results: 88.33% of patients had cognitive impairment with 68.33% with mild cognitive impairment. Abstraction (60,83%), language (56,66%), executive functions (53.66%) and delayed recall (28.33%) were rated the worst. The median value of SF-36 score was 54.1 (27.7-70.01). The lowest results were achieved in the QOL domains of psycial limitation with a median value of 12.5 (0-75) and emotional limitation 33.3 (0-100). It is found statistically significant correlation of the MoCa score with social functioning, energy, vitality and general health (p<0.05) and physical functioning (p<0.001) domains of quality of life, as well as with SF -36 total scores (p<0.05). Among group of patients with cognitive impairment, statistically significant positive correlation between cognitive status mental health HRQOL domain (rho=0.427; p<0.001) was found. Conclusion: Cognitive impairment is very often presented in patients with multiple sclerosis with significant contribution to a poorer quality of life. It is associated with physical and emotional limitations, as well as poorer mental health. Further studies are needed, especially when we take into account very important clinical and prognostic role of cognition in multiple sclerosis.

Background: Covid-19 primarily manifests itself as a respiratory disease, but also with numerous extrapulmonary symptoms and complications. The clinical form of the disease before hospitalization, has a great influence on the further course and occurrence of complications of the disease. Objective: To analyze the clinical and laboratory characteristics of patients with moderate and severe clinical form of the disease, the complications that developed in these patients during hospitalization and the outcome of the disease. Methods: The retrospective study included 520 patients from the Tuzla Canton, treated in the COVID-19 Hospital at University Clinical Center Tuzla in the period from March 27 to October 1, 2020. The source of data were the medical records of hospitalized patients. The clinical and laboratory characteristics of patients with moderate and severe clinical form of the disease and the complications that developed in these patients during hospitalization were analyzed. Results: The number of hospitalized men was statistically significantly higher, p=0.000. Most patients were in the age group of 60-69 years: 152 (29.3%), then in the age group of 50-59 years: 119 (22.9%). Women <70 years had more often a moderate, and women >70 years more often a severe clinical form of the disease, p<0.01. Patients with hypertension, diabetes mellitus, chronic lung diseases, cardiovascular diseases, hematological diseases and tumors of solid organs, with leukopenia and lymphopenia, elevated LDH, CRP, transaminases and serum ferritin, significantly more often had a clinically severe form of the disease (p<0.01). Patients with a severe clinical form of the disease on admission to the hospital had more frequent complications and death as outcome (p<0.01). Conclusion: Patients who were hospitalized with a severe form of COVID-19 had significantly more frequent disease complications and death as outcome.