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In contemporary society, efficient energy management is becoming crucial for achieving energy sustainability and the reliability of power systems. Microgrids stand out as an essential solution to attain these goals, integrating various energy sources and optimizing transmission costs. A detailed analysis of different methods for microgrid optimization is key to achieving maximum energy efficiency and economic viability in its integration. This paper is based on comprehensive research into optimal energy management in a grid-connected microgrid using a genetic algorithm. The aim of optimal management is to reduce active and reactive power losses, as well as voltage deviation, through precise optimization of electricity production. Research has shown that the proper engagement of production resources and energy consumption can contribute to reducing the cost of electricity production, as well as reducing losses and voltage deviation.

Periodic verification of the quality of low-voltage electrical installations is very important from the point of view of safety of people in the building from electric shock and initial fire caused by failures of low-voltage electrical installations (usually poor electrical contact). The standardized procedure for verifying the quality of electrical installations by electrical measurements involves checking which can determine with certainty only whether the protection system by automatic shutdown of the power supply in case of failure is effective or not. However, this check can only detect some poor electrical contacts in the circuit that are potential causes of fire. The paper provides an overview of research results conducted within the project of the Ministry of Education, Science and Technological Development of the Republic of Serbia (project record number 36018), on the basis of which the correction of the existing procedure of periodical verification of the quality of electrical installations is proposed. The proposed correction, which was developed based on the experience gained by performing periodical verification of the quality of electrical installations in the field, as well as analysis of measurement results obtained experimentally in laboratory conditions, allows poor electrical contacts to be detected in a timely manner.

Cycloid drives are a relatively new group of planetary power transmissions. These transmissions have numerous favorable characteristics, such as a wide range of transmission ratios, very compact design, high reliability in dynamic exploitation conditions, high efficiency, etc. As they are part of a newer generation of transmissions, the possibility of using other materials other than steel in their production is not yet fully investigated. For the purposes of this investigation a single stage cycloid reducer was designed and manufactured out of mainly plastic components. The theoretical efficiency was determined and experimentally tested. Their comparative analysis is given through the discussion. The paper concludes with suggestions for further research on this type of cycloid reducers. [ABSTRACT FROM AUTHOR]

Introduction/Objective. The purpose of this study was to determine if patient-related factors, such as hospitalization length and preoperative use of walking aids, and geometrical factors, measured with antero-posterior radiographs of hip, affect the risk of hip dislocation after total hip arthroplasty. Methods. A total of 36 of 433 (8.31%) patients with hip dislocation were identified in the institutional registry during a two-year period. The data for patients with and without hip dislocation were matched and compared. Results. Hip dislocation more often occurred in patients who had used walking aids before the operation compared to the ones who had not (p < 0.001). Also, a difference in the number of hip dislocations was noticed between the patients who stayed longer in the hospital after THA (p < 0.001). The patients with higher acetabular inclination angle (p < 0.005) and height of greater trochanter (p < 0.001) on radiographs had been more prone to hip dislocation. In addition to this, the “safe-zone” was not identified in our study (p > 0.005). Conclusion. Several factors which influence hip dislocation were identified in this study: patient characteristics and radiograph characteristics. Both groups of factors require attention and monitoring in future studies.

In this paper the effects of adding buckling constraints to truss sizing optimization for minimizing mass are investigated. Introduction of buckling testing increases the complexity of the optimization process as Euler buckling criteria changes with each iteration of the optimization process due to the changes in element cross section dimensions. The resulting models which consider this criteria are practically applicable. For the purposes of showing the effects of dynamic constraints for buckling, optimal parametric standard test models of 10 bar, 17 bar, and 25 bar trusses from the literature are tested for buckling and compared to the models with the added constraint. Models which do not consider buckling criteria have a considerable number of elements which do not meet buckling criteria. The masses of these models are substantially smaller than their counterparts which consider buckling.

Truss optimization has the goal of achieving savings in costs and material while maintaining structural characteristics. In this research a 10 bar truss was structurally optimized in Rhino 6 using genetic algorithm optimization method. Results from previous research where sizing optimization was limited to using only three different cross-sections were compared to a sizing and shape optimization model which uses only those three cross-sections. Significant savings in mass have been found when using this approach. An analysis was conducted of the necessary bill of materials for these solutions. This research indicates practical effects which optimization can achieve in truss design.

Background/Aim. To our knowledge there are no data about the relationship between elevated risk for developing type 2 diabetes mellitus (DM2) and altered cardiac autonomic function. The aim of this study was to evaluate the association between heart rate variability (HRV) and slightly increased risk for DM2. Methods. We evaluated 69 subjects (50.0 ± 14.4 years; 30 male) without DM2, coronary artery disease and arrhythmias. The subjects were divided into two groups according to the Finnish Diabetes Risk Score (FINDRISC): group I (n = 39) included subjects with 12 > FINDRISC ≥ 7; group II (n = 30) subjects with FINDRISC < 7. HRV was derived from 24-h electrocardiogram. We used time domain variables and frequency domain analysis performed over the entire 24-h period, during the day (06-22 h) and overnight (22-06 h). Results. Standard deviation of the average normal RR intervals was significantly lower in the group with increased risk for DM2 compared to the group II (127.1 ± 26.6 ms vs 149.6 ± 57.6 ms; p = 0.035). Other time domain measures were similar in both groups. The group I demonstrated significantly reduced frequency domain measures, total power - TP (7.2 ± 0.3 ln/ms2 vs 7.3 ± 0.3 ln/ms2; p = 0.029), and low frequency - LF (5.9 ± 0.4 ln/ms2 vs 6.3 ± 0.6 ln/ms2; p = 0.006), over entire 24 h, as well as TP (7.1 ± 0.3 ln/ms2 vs 7.3 ± 0.3 ln/ms2; p = 0.004), very low frequency (6.2 ± 0.2 ln/ms2 vs 6.3 ± 0.2 ln/ms2; p = 0.030), LF (5.9 ± 0.4 ln/ms2 vs 6.2 ± 0.3 ln/ms2; p = 0.000) and high frequency (5.7 ± 0.4 ln/ms2 vs 5.9 ± 0.4 ln/ms2; p = 0.011) during the daytime compared to the group II. Nocturnal frequency domain analysis was similar between the groups. The low diurnal frequency was independently related to elevated risk for diabetes mellitus (beta = -0,331; p = 0.006). Conclusion. The obtained results suggest that even slightly elevated risk for developing diabetes mellitus may be related to impaired HRV.

Vascular stents are general medical devices of class III or IIb, which are placed along the walls of the constricted coronary and peripheral blood vessels thus keeping them viable. According to the mechanism of expansion, stents may be balloon-expandable or self-expanding. Depending on the geometry they can be classified into: coil stents, open-cell modular stents and multi-cell closed cell stents. The most important characteristic of vascular stents is their flexibility, but a number of additional requirements must also be met: high radial strength, low elastic deformation, small diameter, the possibility of monitoring through the bloodstream, minimum subsequent shortening, minimum elastic longitudinal deformation, and the optimal retention at target site. Materials for production of stents must be biologically inert, visible by radiological techniques, biocompatible, corrosion-resistant and resistant to stress due to blood flow. The most significant adverse event after stent implantation is the occurrence of restenosis, which is most efficiently overcome by the application of drug releasing stents. These stents are composed of three parts: stent platform, drug carrier and a drug that inhibits neointimal hyperplasia - paclitaxel and limuses (sirolimus, everolimus, zotarolimus, tacrolimus, pimecrolimus, etc.). In recent years, stents with surfaces coated with substances that accelerate endothelialisation and thus reduce thrombosis have been developed. The latest approach is represented by a stent with the lumen coated with CD34 antibody, and the outer side coated with sirolimus. By using these devices a double effect is achieved: acceleration of endothelialisation and inhibition of neointimal hyperplasia.

In this paper the experimental conditions for optimal reversed-phase liquid chromatographic (RP-HPLC) determination of sulfamethoxazole, trimethoprim and preservatives, as well as degradation products of sulfamethoxazole and trimethoprim in syrup were defined. The determination of active compounds and preservatives was carried out on Zorbax Eclipse XDB-C18, 150 mm × 4.6 mm, 5 μm particle size column, mobile phase flow rate was 1.5 mL min-1, and detection at 235 nm for the active compounds and 254 nm for preservatives. Mobile phase A consisted of 150 mL of acetonitrile, 850 mL of water and 1 mL of triethanolamine (pH 5.90 adjusted with diluted acetic acid), while mobile phase B was acetonitrile. The mobile phase ratio was defined by the gradient program. For the determination of degradation products Zorbax Eclipse Plus C18, 100 mm x 4.6 mm, 3.5 μm particle size column was used, the mobile phase flow rate was 0.5 mL min-1 and detection at 210 nm for 3,4,5-trimethoxybenzoic acid and 254 nm for sulfanilic acid and sulfanilamide. Mobile phase A was 50 mM potassium dihydrogenphosphate (pH 5.60 adjusted with a 0.5 mol L-1 potassium hydroxide), while mobile phase B was acetonitrile. The mobile phase ratio was defined by the gradient program. Through the validation of the developed methods their efficiency and reliability is confirmed and consequently the adequacy for the routine control.

Modern trends in drug quality control are moving toward incorporating quality into the method during its development. That course is in accordance with Quality by Design (QbD) concept defined by ICH Q 8 (R2) guideline. This implies that the method development begins by defining the method goals and collecting the relevant data, i.e. analyzing the properties of a given active pharmaceutical ingredient and evaluating the optimal experimental conditions. It is followed by a risk assessment defined by systematic robustness testing with the application of experimental design, while the final confirmation of the method reliability is done through the complete validation tests. In this paper, development of Karl Fischer titration for water determination in active pharmaceutical substance clindamycin phosphate is presented. Karl Fischer titration (KFT) is a widely used method in the pharmaceutical industry for determination of water content. For the analyzed substance, the European Pharmacopoeia suggests a relatively large amount of samples for the determination of water, so the objective of this study is to confirm the applicability of the developed method for the determination of water in small amount of samples applying QbD approach. According to QbD rules, detail development of coulometric Karl Fischer titration for water determination in clindamycin phosphate was done. For robustness testing fractional factorial design 24-1 was successful applied and confirmed that method was robust. Robustness was evaluated using statistical and graphical methods. Also, design space was defined so the region, in which factors could be changed without significant changes in water content, was defined. At the end, other validation parameters were determined and it was proved that analytical test system was capable of providing useful and valid analytical data.

Cycloid reducers are gear trains which can be classified as planetary transmissions. These transmissions have a very wide range of uses in industry in transporters, robots, satellites, etc. This research presents a comparative analysis of three analytical methods for determining cycloid drive efficiency. The paper explores every mathematically formulated method and compares them to experimental results from literature. The presented methods for determining efficiency have a common property, in that they all determine losses due to friction on the bearing cam surface of the shaft, the rollers of the central gear and the output rollers. The calculation of efficiency values is done for standard power values. The methods differ primarily in the way they calculate losses. For each method of calculating efficiency there is an analysis of pros and cons. The paper concludes with suggestions as well as possible directions for further research.

Introduction. The metabolic syndrome and its influence on coronary artery disease development and progression remains in focus of international research debates, while insulin resistance, which represents its core, is the key component of hypertension, dyslipidaemias, glucose intolerance and obesity. Objective. The aim of this study was to establish relationship between basal glucose and insulin levels, insulin sensitivity and lipid panel and the degree of coronary atherosclerosis in nondiabetic patients. Methods. The coronary angiograms were evaluated for the presence of significant stenosis, insulin sensitivity was assessed using the intravenous glucose tolerance test with a minimal model according to Bergman, while baseline glucose (G0), insulin (I0) and lipid panel measurements (TC, HDL, LDL, TG) were taken after a 12-hour fasting. Results. The protocol encompassed 40 patients (19 men and 21 women) treated at the Institute for Cardiovascular Diseases of the Clinical Centre of Serbia, Belgrade. All were non-diabetics who were divided into 3 groups based on their angios: Group A (6 patients, 15%, with no significant stenosis), Group B (18 patients, 45%, with a single-vessel disease) and Group C (16 patients, 40%, with multi-vessel disease). Presence of lower insulin sensitivity, higher I0 and TC in the group of patients with a more severe degree of coronary atherosclerosis (insulin sensitivity: F=4.279, p=0.023, A vs. C p=0.012, B vs. C p=0.038; I0: F=3.461 p=0.042, A vs. B p=0.045, A vs. C p=0.013; TC: F=2.572, p=0.09), while no significant difference was found for G0, LDL, HDL and TG. Conclusion. Baseline insulinaemia, more precisely, fasting hyperinsulinaemia could be a good predictor of significant coronary atherosclerosis in non-diabetic patients, which enables a more elegant cardiometabolic risk assessment in the setting of everyday clinical practice.

In the period from 1991. to 1999. over 1500000 people in former Yugoslavia were members of dozens military formations that participated in the war in different manners and with various motives. These persons have actively contributed to the tragedy caused by war, that was and for some time will be the most important factor of social and personal relationships between individuals and the nations in the member states of former Yugoslavia. They are now left on their own and exposed to manipulation by nationalist centers and certain politicians. Because of their wartime past, they are usually depicted as the carriers of nationalistic and warmongering ideas on the 'other' side. However, viewed from the aspect of peace-building, ex-soldiers represent a significant potential, because many of them, in fact, have a need to contribute to building a more just society and feel responsible for what happened. In this paper it is discussed how some war veterans decided to join forces and contribute to the reconciliation in the former Yugoslavia by their joint activities.

Introduction. Antioxidant systems are important factors affecting the oxidation of lipoproteins and thereby the progression of atherosclerotic disease. It has been suggested that physical activity might maintain and promote the antioxidant defence capacity against the oxidative stress. Left ventricular dysfunction (LVDD) and hypertension are more common in subjects with diabetes mellitus (DM) type 2. Objective. To evaluate the oxidative stress in patients with DM type 2, particularly with LVDD and hypertension and to determine the influence of acute exercise training on the investigated parameters. Methods. To assess the oxidative stress of patients, we determined the following antioxidative parameters: triglycerides (TG), total cholesterol, low density cholesterol, OxLDL cholesterol, superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), plasminogen activator-type 1 (PAI-1) which were measured at rest and immediately after the acute bout of the cardiopulmonary exercise cycle ergometer test. Results. In basal conditions, diabetic patients had a significant increase of TG (3.12±1.09 vs 1.74±0.9 mmol/l; p

Introduction. Elevated levels of oxidized LDL cholesterol (OxLDL) are considered to be a key factor of initiating and accelerating atherosclerosis. It promotes atherosclerosis through inflammatory and immunologic mechanisms that lead to the formation of macrophage foam cells. Objective. To determine the relationship among OxLDL, C-reactive protein (CRP) level and carotid intima-media thickness (IMT) in population with risk factors for atherosclerosis. Methods. The study group consisted of 125 clinically healthy, hypercholesterolaemic subjects (49.3±5.7 years; 75 females and 50 males) compared with 100 age-matched population-based control subjects. The study group was divided into two subgroups: subgroup A (the levels of LDL cholesterol > 5 mmol/L) and subgroup B (the levels of LDL cholesterol

Background/Aim. Many studies support the hypothesis that oxidative stress is involved in the pathogenic process of a variety of diseases including hypertension. In humans, hypertension is also considered a state of oxidative stress that can contribute to the development of arteriosclerosis and other hypertension- induced organ damage. The aim of this study was to evaluate an influence of acute physical exercise on antioxidative enzymes activity and lipid status in patients with hypertension. Methods. Forty patients with hypertension and 20 age-matched controls were included in the study. To assess an influence of acute exercise on lipids and antioxidative enzymes activity the following parameters were determined at rest and immediately after the acute cardiopulmonary exercise cycloergometer test: triglycerides (TG), total cholesterol, low density cholesterol (LDL), oxidised LDL cholesterol (OxLDL), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and plasminogen activator inhibitor (PAI). Results. In basal condition, hypertensive patients compared to the control group had increased, but not significantly, level of Ox LDL (88.61±14.06 vs 79.00±29.26 mmol/L), PAI (3.06±0.56 vs 2.6±0.35 U/mL) and activity of GSH-Px (50.22±15.20 vs 44.63±13.73 U/g Hb). After acute exercise test, there was significantly greater level of Ox LDL (79.0±29.26 vs 89.3±29.07 mmol/L; p < 0.05) only in the control group. GSH-Px activity was significantly decreased only in hypertensive patients after acute exercise (50.22±15.2 vs 42.82±13.42 U/g Hb; p < 0.05), but not in the controls. Conclusion. No significantly elevated Ox LDL, GSH-Px and PAI-1 levels were found in hypertensive patients during basal condition in comparison with healthy subjects. Decreased GSH-Px activity was associated with those in acute exercise only in hypertensive patients. It could be an important indicator of deficiency of physiological antioxidative defense mechanism in hypertensive patients during an acute exercise.

Background/Aim. Exercise is a well recognized model of oxidative stress and, also, an important tool in diabetes management. The aim of our study was to evaluate oxidative stress in patients with diabetes mellitus type 2 and to determine influence of acute exercise training on the investigated parameters. Methods. To evaluate oxidative stress in the patients, we determinated following parameters: triglycerides (TG), total cholesterol, low density lipoprotein cholesterol (LDL), oxidized LDL cholesterol (Ox LDL), superoxide dismutase (SOD), glutathione peroxidase (GSHPx), plasminogen activator inhibitor (PAI) which were measured at rest and immediately after the acute bout of cardiopulmonary exercise cycle-ergometer test. Results. In basal condition, diabetic patients compared to controls have significant higher values of TG (3.12 ± 1.09 vs 1.74 ± 0.9 mmol/L, p < 0.01), Ox LDL (84.73 ± 16.90 vs 79.00 ± 29.26 mmol/L, p < 0.05) and SOD enzyme activity (913.38 ± 120.36 vs 877.14 ± 153.18 U/g Hb, p < 0.05). During the acute exercise test, there was significant increase of Ox LDL in both the study patients (from 84.73 ± 16.90 to 92.33 ± 23.29 mmol/L, p < 0.05) and in the control group (from 79.00 ± 29.26 to 89.30 ± 29.07 mmol/L, p < 0.05). SOD activity was significantly increased in both groups during exercise, in diabetic patients from 913.38 ± 120.36 to 921.50 ± 130.03 U/gHb, p < 0.05, and in the controls from 877.14 ± 153.18 to 895.00 ± 193.49, U/gHb, p < 0.05. GSH-Px activity was significantly increased only in the diabetic patients after the acute exercise (from 45.04 ± 11.19 to 51.81 ± 15.07 U/gHb, p < 0.01), but not in the controls (from 44.63 ± 13.73 to 43.97 ± 25.97 U/gHb, p = ns). PAI significantly decreased during the exercise test, only in the healthy subjects (from 2.60 ± 0.35 to 2.22 ± 0.65, p < 0.05). Type 2 diabetic patients with complications had only significant increase in GSH-Px activity (from 47.10 ± 7.37 to 54.52 ± 11.97 U/gHb, p < 0.01). Conclusion. Elevated Ox LDL, SOD and GSH-Px levels are associated with acute exercise in type 2 diabetic patients. We suggest that it could be a compensatory mechanism to preventing free radicals tissue damage. We hypothesize that a physical training program induces an enhance of muscular and liver antioxidant enzymes activity and reduces oxidative stress. Further studies are needed to explore the relationship between exercise and antioxidant system in diabetic patients with and without complications.

Background/Aim. Exercise can positively influence risk factors associated with cardiovascular disease. The mechanisms by which exercise reduces atherogenic risk remain unknown. The aim of the present study was to investigate the effect of acute exercise (cardiopulmonary exercise cycle ergometer test) on atherogenic lipids in untreated mild hypertensive patients with or without hypercholesterolemia. This testing allows determination of exercise capacity, peak heart rate, and ventilation per minute (VE), peak oxygen uptake (pVO2) and exercise time (ET). Methods. The study group included 85 untreated mild hypertensive patients (according to VII Joint National Committee - JNC 7) divided into two subgroups: hypertensive hypercholesterolemic and hypertensive normocholesterolemic. The control group included 35 normotensive subjects divided into two subgroups: normotensive hypercholesterolemic and normotensive normocholesterolemic. Lipid profiles to determine were oxidized LDL (OxLDL) - a marker of oxidative stress, triglycerides, total cholesterol, LDL cholesterol, and HDL cholesterol, which were measured at rest and 30 minutes after the acute bout of cardiopulmonary exercise cycle ergometer test. Lipids profiles were measured by enzymatic methods. Oxidized LDL was determined by a commercially available sandwich ELISA (Mercodia AB, Uppsala, Sweden). C-reactive protein (CRP) was measured using chemiluminiscent methods (Immulite-DPC). Results. In our study OxLDL was significantly higher in hypertensive patients with atherogenic lipid profiles in basal condition, compared to the hypertensive patients without atherogenic lipid profiles and controls. There was a significant difference in CRP (p < 0.001) between hypercholesterolemics (hypertensive and normotensive) and normocholesterolemics (hypertensive and normotensive). We found increased OxLDL after exercise in both groups (hypertensive patients and normotensive), but only in the hypertensive hypercholesterolemic patients the difference was statistically significant (90.47 ± 15.31 vs. 105.94 ± 14.17 IU/L, p < 0.001). Systolic and diastolic blood pressures were significantly higher during exercise only in the hypertensive patients. There were significantly lower values of pVO2 only in hypertensive hypercholesterolemic patients. There were no significant differences between hypertensive and normotensive ones for ET and VE. In hypertensive ones we found after exercise a negative correlation between pVO2 and OxLDL (r = -0.473; p < 0.05), and pVO2 and CRP (r = -0.478; p < 0.05). We also found in normotensive normocholesterolemic patients a positive correlation between VE and systolic blood pressure (r = 0.420; p < 0.05), a negative correlation between VE and OxLDL (r = -0.421; p < 0.05), and VE and CRP (r = -0.561; p < 0.05). Conclusion. This study showed that acute exercise induces and increases oxidative stress only in untreated mild hypertensive patients with atherogenic lipid profiles. These results imply the need to normalize atherogenic lipid profile in untreated patients with mild hypertension in order to prevent an increased lipid peroxidation under acute exercise.

Introduction: Atherogenic lipid profile is an important risk factor in development of atherosclerosis in menopausal women. High level of small dense LDL, that is more susceptible to oxidation, and high levels of inflammatory markers are also associated with an increased risk for development of atherosclerosis. Objective. The aim of this study was to investigate the relationship between lipid profile, oxidized LDL (Ox-LDL) and C-reactive protein (CRP) as inflammatory reaction in healthy women dependent on age and menopause. Method. The study included a group of clinically healthy women (total of 97 women). Group 1: 15 women younger than 45 years; group 2: 62 women between 46 and 55 years, group 3: 20 women between 56 and 65 years, group of menopausal women (73) and group of premenopausal women (24). None of the women had history of obesity, diabetes mellitus, cerebrovascular, ischaemic heart disease, and hypertension. Lipid profiles were measured by enzymatic methods. Ox-LDL was measured by using a specific monoclonal antibody, mAb4E6. CRP was measured using hemiluminiscent methods (Immulite-DPC). Results. Results showed significantly higher levels of total cholesterol (p

Introduction. Lipid peroxidation and antioxidant systems are important factors affecting the metabolism of lipoproteins in diabetes mellitus. Objective. The aim of this study was to investigate the lipid and antioxidant parameters in type II diabetes mellitus patients, and also to determine the effect of diabetic complications on these parameters. Method. Lipid status, Oxidized LDL cholesterol, glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) and plasminogen activator inhibitor (PAI-1) levels in plasma of 50 type II diabetic patients were measured with commercially available kits. Results. The results showed only statistically significant higher levels of triglycerides (3.12±3.9 mmol/l) in diabetics compared with the controls. Ox-LDL cholesterol (84.7±16.9 mmol/l) and SOD activities (913.4±120.3 U/gHb) in type 2 diabetes mellitus were higher than those of the controls, but there was no statistical significance. On the other hand, in patients with diabetes mellitus and complications, LDL cholesterol, PAI-1, SOD and GSH-Px activities were higher but not significantly than those without complications. Triglycerides and Ox-LDL cholesterol were lower in the group of diabetic patients with complications in comparison to the group without complications. Conclusion. These results indicate that antioxidant status may be affected in type II diabetic patients and that the rise in some enzyme activities could be a compensatory mechanism to prevent tissue damage. Our results suggest that the rise in PAI-1 in type II diabetics with complications may be a good marker of vascular endothelial dysfunction.