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The paper discusses possibilities for the application of the essential facilities doctrine in the Serbian telecommunications sector and the consequences of that application for the protection of competition. Based on the findings in the paper, the conclusion is, among other things, that the essential facilities doctrine may be applied in different ways and under different conditions by the Regulatory Agency for Electronic Communications and Postal Services (RATEL), the Commission for Protection of Competition (KZK), as well as the Administrative Court. Furthermore, bearing in mind the existing relationship between these bodies, as well as the relationship between the law on protection of competition and sectoral regulation, we conclude that KZK should primarily apply the essential facilities doctrine, while RATEL is the one to additionally enhance competition within the sector based on the sectoral regulation.

An intense public debate is currently taking place in the US. The main subject of this debate is tech giants and the antitrust law reform. The fundamental dilemma is whether giant corporations, such as Apple, Google, Amazon, Microsoft, and Facebook, fit the traditional antitrust law or not. Senator Klobuchar proposed the new bill (the Competition and Antitrust Law Enforcement Reform Act) in 2021, and Congress is currently between a rock and a hard place. If Congress decides to support the New Brandeis movement and enact the bill, it could harm the tech giants and make the US start lagging behind China. If it decides otherwise, it could cause considerable dissatisfaction among US voters. This paper analyses the bill in detail and explores the possible outcomes. The conclusions suggest that enactment of the bill could have overwhelmingly adverse economic consequences for the competitiveness of US markets, innovation, and consequently for consumer welfare.

Changes in weather conditions affect people's lifestyle in many ways. This paper presents the influence of weather conditions on the parameters of traffic flows on a two - lane suburban road. Main goal for comparing parameters of traffic flow for bad and good weather conditions is to draw conclusions about which parameters and to what extent are affected by different weather conditions. Based on the foreign literature, it is necessary to define an appropriate research methodology adapted to local conditions and apply it in an adequate way in order to obtain the most accurate results and draw conclusions. In this study, the influence of rainfall on the reduction of anxiety and traffic flow in the vicinity of the town of Loznica is presented. Based on meteorological data for 2019, a sample of days and hours when it rained was determined and compared with days when there was no precipitation.

Multiferroic composites containing ferroelectric Ba(Ti0.80Zr0.20)O3 (BT80Zr20) phase and magnetic Ni0.7Zn0.3Fe2O4 (NZF), CoFe2O4 (CF) or Ni0.7Cu0.01Sm0.05Zn0.29Fe1.95O4 (NCuSmZF) phase were investigated in this study. Three composites, BT80Zr20-NZF, BT80Zr20-CF and BT80Zr20-NCuSmZF were prepared by mixing chemically synthesized powders in the planetary mill, uniaxial pressing and sintering at 1300?C. X-ray diffraction data for the single phase and composites ceramics indicated the formation of crystallized structure of both ferrites and barium zirconium titanate, without the presence of undesirable phases. Microstructure analysis has shown the formation of two types of nanosized grains, polygonal ferromagnetic andd rounded ferroelectric grains. Non-saturated hysteresis loops were evident in all composite samples possibly due to the presence of very high conductive ferrite phases. The BT80Zr20-CF has shown the lowest conductivity values in comparison with other two compounds and therefore the highest potential for ferroelectric application. The impedance investigations confirmed the presence of different relaxation processes that originate from the grain and grain boundary contributions. Investigation of J-E relation between leakage and electric field for the BT80Zr20 and composites revealed the presence of four possible mechanisms of conduction in these materials.

Multiferroic composites with general formula Ba(Ti0.95Zr0.05)O3 – Ni0.7Zn0.3Fe2O4, Ba(Ti0.95Zr0.05)O3 – CoFe2O4, Ba(Ti0.95Zr0.05)O3 – Ni0.7Cu0.01Sm0.05Zn0.29Fe1.95O4, (BTZr(95–5) – NZF, BTZr(95–5) – CF, BTZr(95–5) – NCuSmZF) were prepared by mixing chemically obtained different types of ferrites and BTZ(95–5) powders in the planetary mill for 24 h. The optimization of sintering process was performed and powders were pressed and sintered at 1300 °C for obtained composites samples. From the X-ray analysis for single phase and composites ceramics the formation of crystallized structure of ferrites and barium zirconium titanate can be noticed. SEM analyses indicated the formation of two types nanosized grains, polygonal ferromagnetic and rounded ferroelectric grains. The electrical properties of these materials were investigated using impedance spectroscopy and analysis of ferroelectric measurements. Impedance analysis of all investigated samples has shown different relaxation processes that originated from the grain and grain boundary contributions. The results of polarization vs. electric field measurements have shown the influence of magnetic phase type and its concentration on the ferroelectric properties of the composites. Due to high conductivity of ferrite phases and presence of interfacial polarization, the shapes of these curves differed from the conventional ferroelectric materials.

Background Low grade fibromyxoid sarcoma (LGFMS) is a rare and benign mesenchymal tumor with indolent course, most commonly found in young or middle-aged men. The majority of the LGFMSs are located in the trunk and deep soft tissue of the lower extremities. They appear as well circumscribed, although not encapsulated, which often leads to incomplete surgical resection. Despite their seemingly benign appearance, these tumors have aggressive behavior with high metastatic and recurrence rates. Accurate histopathologic examination of the specimen and its immunohistochemical analysis are mandatory for a precise diagnosis. Case summary We report a case of a 38 year-old-man who presented with jaundice and upper abdominal discomfort. Multi-detector computed tomography and magnetic resonance imaging showed a large left liver tumor mass, extending to the hepatoduodenal ligament. Left hepatectomy was performed with resection and reconstruction of hepatic artery and preservation of middle hepatic vein. Histopathologic examination confirmed the tumor being a low-grade fibromyxoid sarcoma. Three and a half years after surgery, the patient died after being diagnosed with spine metastasis. Conclusion Due to poor response to all modalities of adjuvant treatment, we consider that the focus of treatment should be on surgery as the only option for curing the disease.

Preoperative anxiety is associated with increased morbidity and/or mortality in surgical patients. This study investigated the incidence, predictors, and association of preoperative anxiety with postoperative complications in vascular surgery.Consecutive patients undergoing aortic, carotid, and peripheral artery surgery, under general and regional anesthesia, from February until October 2019 were included in a cross-sectional study. Anesthesiologists assessed preoperative anxiety using a validated Serbian version of the Amsterdam Preoperative Anxiety and Information Scale. Patients were divided into groups with low/high anxiety, both anesthesia- and surgery-related. Statistical analysis included multivariate linear logistic regression and point-biserial correlation.Of 402 patients interviewed, 16 were excluded and one patient refused to participate (response rate 99.7%). Out of 385 patients included (age range 39-86 years), 62.3% had previous surgery. High-level anesthesia- and surgery-related anxieties were present in 31.2 and 43.4% of patients, respectively. Independent predictors of high-level anesthesia-related anxiety were having no children (OR = 0.443, 95% CI: 0.239-0.821, p = 0.01), personal bad experiences with anesthesia (OR = 2.294, 95% CI: 1.043-5.045, p = 0.039), and time since diagnosis for ≥ 4 months (OR = 1.634, 95% CI: 1.023-5.983, p = 0.04). The female sex independently predicted high-level surgery-related preoperative anxiety (OR = 2.387, 95% CI: 1.432-3.979, p = 0.001). High-level anesthesia-related anxiety correlated with postoperative mental disorders (rSince preoperative anxiety affects the postoperative course and almost every third patient experiences anxiety preoperatively, routine screening might be recommended in vascular surgery.

BACKGROUND Development of colonic ischemia (CI) after ruptured abdominal aortic aneurysm (RAAA) treatment is a lethal complication with perioperative mortality reported to be high as 50%. Therefore, the main goal of this study was to identify pre-, intra- and postoperative risk factors associated with CI in patients undergoing open repair (OR) due to RAAA, that might help to select patients who are more prone to develop CI. METHODS This was a single-center prospective cohort study on patients with RAAA undergoing OR between January 1st 2018 and July 1st 2019, at the Clinic for Vascular and Endovascular Surgery, Clinical Center of Serbia. During this period 89 patients were treated due to RAAA and all were included in the study. The primary endpoint was grade III CI, or transmural necrosis, diagnosed by laparotomy. RESULTS Out of 89 patients operated due to RAAA, CI was diagnosed in 14 (15.73%). During the operation, patients with CI had a longer duration of hypotension (42.86±35.82 vs 24.13±23.48, p=.021) and more common significant hypotension (54.54% vs 14.66%, p=.024). In the postoperative course, patients with CI had more common signs of abdominal compartment syndrome (71.42% vs 25.33%, p=.001) and higher mortality rate (78.57% vs 29.33%, p=.001). The univariate regression model showed that one of the most significant factors that were associated with CI were age higher than 75 years, significant hypotension lasting more than one hour, organ lesion, development of abdominal compartment syndrome and higher potassium values on third and fourth quartile. CONCLUSIONS Grade III colon ischemia (transmural) remains the important cause of mortality after ruptured abdominal aortic aneurysm repair. We identified pre- and intraoperative and postoperative risk factors that could improve the selection of patients for primary open abdomen treatment or early exploratory laparotomy in order to prevent or timely diagnose colon ischemia.

The ferroelectric and magnetic properties of four-layered Aurivillius Bi5Ti3FeO15 (BFT) compounds via partial substitution of Bi3+ with Y3+ and Fe3+ with Co2+ (according to formula: Bi5 − xYxTi3FeO15, x = 0.1, 0.2, 0.3; Bi5Ti3Fe1 − yCoyO15, y = 0.1, 0.3, 0.5) were investigated. Polycrystalline ceramics of Co and Y substituted BFT were prepared by conventional solid-state reaction. Crystal structure and phase purity were confirmed via X-ray diffraction. Raman spectral signatures indicate that Y replaces Bi ions in the pseudo-perovskite layers and Co replaces Fe ions in the octahedral sites. SEM micrographs show a decrease in grain size for both chemically modified samples when compared to plate-like morphology for pure BFT with dimensions ranging from 3–5 µm in length and a thickness of ~ 0.5 µm. The decrease in grain size is more pronounced in Co substituted samples with plate-like grain dimensions of 1 µm in length and 0.1 µm in thickness. Ferroelectric measurements show unsaturated leaky hysteresis loops in both chemically modified samples until the maximum applied electric field. Magnetic measurements confirm the paramagnetic nature of pure and Y substituted BFT ceramics while Co substituted BFT ceramics exhibit a typical ferromagnetic M-H loop. The largest remanent magnetization value of 0.084 emu/g at room temperature is recorded for the Co2+ substituted sample with x = 0.30.

The Federal Trade Commission of the United States (FTC) filed a Complaint against Facebook on 9th December 2020, in the midst of the COVID-19 crisis. While facing one of the biggest social and economic crises in American history, FTC has enough time and resources to (re)investigate Facebook’s acquisitions of Instagram and WhatsApp. This paper analyses motives and rationale behind the FTC’s Complaint requesting Facebook’s break-up and what could be possible alternatives from a competition law perspective. All the findings suggest that the FTC’s Complaint is politically motivated, and the competition authorities should enable digital platforms to expand. However, the expansion should be controlled, to ensure that the benefits for consumers are not undermined by relatively slower (not diversified) technological development.

BACKGROUND Acute aortic occlusion (AAO) represents potentially fatal acute vascular emergency that requires prompt diagnosis and intervention. Clinical condition of patients with AAO is frequently severely devastated when surgical intervention is questionable. Our objective was to retrospectively review our institutional experience with AAO and assess predictors of intrahospital mortality and morbidity. METHODS This is a retrospective single-center cohort study with prospectively collected data between January 1, 2005 and January 1, 2018. The total number of 28 consecutive patients with AAO were included in our analysis. Patients with acute aortic thrombosis manifested by bilateral acute limb ischemia were divided in two groups based on potential caues of AAO (embolism or in-situ thrombosis) differentiated according to condition of aortoilical segment. RESULTS We identified 28 patients with AAO. All of them underwent either aortobifemoral bypass (N.=20, 71%) or bilateral trans-femoral thrombectomy (N.=8, 29%). The overall in-hospital mortality was 36%. Factors that influenced in-hospital mortality were: paralysis (OR=4.41, 95% CI: 1.88-21.78) and higher lactate values on admission (OR=1.23, 95% CI: 1.09-1.83), postoperative development of severe acute kidney injury (OR=3.08, 95% CI: 1.42-14.66), hemodialysis (OR=10.74, 95% CI: 1.64-109.78) and bowel ischemia (OR=5.19, 95% CI: 1.58-55.63). CONCLUSIONS Paralysis, higher lactate values, development of acute kidney injury, hemodialysis and bowel ischemia are predictors of worse outcome and may be used for risk stratification of patients with acute aortic occlusion and improve counseling patients and their families about expected postoperative outcomes. Patients with embolism and malignant disease have worse outcome; however, this should be tested in future studies on larger sample.

Ni-Zn ferrites, with the general formula Ni1-xZnxFe2O4 (x = 0.0, 0.3, 0.5, 0.7, 1.0), CoFe2O4, BaTiO3 and PbZr0.52Ti0.48O3 powders were synthesized by auto-combustion method. The composites were prepared by mixing the appropriate amounts of individual phases, pressing and conventional sintering. X-ray analysis, for individual phase and composites, indicated the formation of crystallized structure of NiZnFe2O4, BaTiO3 and PbZr0.52Ti0.48O3 without the presence of secondary phases or any impurities. SEM analyses indicated a formation of uniform grain distribution for ferromagnetic and ferroelectric phases and formation of two types of grains, polygonal and rounded, respectively. Magneto-dielectric effect was exhibited in all samples because of the applied stress occurring due to the piezomagnetic effect and the magnetic field induced the variation of the dielectric constant. For all samples the dielectric constant was higher in applied magnetic field. At the low frequency, the dispersion of dielectric losses appeared, while at the higher frequency the value of tan δ become constant (Maxwell-Wagner relaxation). Investigation of J-E relation between leakage and electric field revealed that both nickel zinc ferrite and composites have three different regions of conduction: region with ohmic conduction mechanism, region with the trap-controlled space charge limited current mechanism and region with space charge limited current mechanism.

The healthcare environment in Serbia has changed dramatically over a last two decades, pointing out the necessity of clinical informatics (CI) education for future MDs. Total of 77 students were enrolled and 72 (93.5%) have successfully finished this course during 4 academic years. Mean total score for all students was 83.4 Âś 9.0 points, without difference between genders. We presented blended learning module as an effective way of gaining competences in CI and recommend this course to be required for future MDs.

BaTiO3 nanopowders doped with La and co-doped with La/Mn were prepared by auto-combustion and Pechini methods, respectively. The influence of the synthesis methods, dopants and sintering temperature on the BaTiO3 structure and its potential to be used as humidity and/or H2 gas sensor were studied. The optimization of all process parameters was performed to obtain adequate microstructure for the development of good sensor properties. The difference in the grain size between the La-doped and La/Mn co-doped samples and the formation of different types of defect structures in these ceramics were found to be significant for the desired electrical and ferroelectric properties. The La-doped ceramics with a pseudo-cubic structure showed the highest potential for gas sensors. The materials obtained by the Pechini method had a tetragonal structure and showed the best response, i.e., the change in electrical resistivity by four orders of magnitude in the humid atmosphere.

INTRODUCTION Acute lower limb ischaemia (ALI) is the sudden onset of decreased arterial perfusion with imminent threat to limb viability. Contrast induced acute kidney injury (CI-AKI) is one of the complications that increases mortality in patients who undergo contrast imaging in coronary procedures. The goal of this study is to evaluate the impact of chronic kidney disease (CKD) and CI-AKI on long-term clinical outcomes in patients with ALI undergoing lower limb revascularisation. METHODS A total 1017 consecutive patients with acute lower limb ischaemia who were admitted between July 1, 2006, and January 1, 2017, were retrospectively reviewed. Patients who had end stage renal disease, those who had end stage heart and malignant disease and died within 7 days of limb revascularisation, and those who did not undergo angiography were excluded. Thus 546 patients were included in the final analysis. Patients were classified as with or without CKD and were then subdivided according to the presence or absence of the development of CI-AKI, defined as an increase in serum creatinine of ≥0.5 mg/dL or by ≥25% from the baseline value within the first 72 h after contrast exposure. The primary end point was all cause mortality and secondary major adverse limb event (MALE). RESULTS Both CKD and CI-AKI were associated with the highest rate of all cause mortality (chi square = 55.77, d.f. = 1, p

Comparative study of different PZT-based composite materials ((x)PbZr 0.52 Ti 0.48 O 3 + (1-x)CoFe 2 O 4 and (x)PbZr 0.52 Ti 0.48 O 3 +(1-x)Ni 0.7 Zn 0.3 Fe 2 O 4 (x = 0.8 and 0.9)) is presented in the frame of structural, dielectric, ferroelectric and magnetic properties. PZT and NZF/CF powders were synthesized by auto combustion technique. The composites were synthesized by mixing the appropriate amount of individual phases using conventional sintering. XRD data indicated the formation of well crystallized structure of PZT and NZF/CF, without the presence of undesirable phases. SEM micrographs revealed a uniform grain distribution of both, ferroelectric and ferromagnetic phases. Non-saturated hysteresis loops are evident in all samples due to the existence of non-ferroelectric ferrite phase. All the samples exhibit typical ferromagnetic hysteresis loop, indicating the presence of the order magnetic structure. Dielectric investigations revealed that ferrites are the main source of charge carriers, which must be of electronic origin. The activation energy of effective electrical resistivity is heavily influenced by the ferroelectric phase.

Background The aim was to evaluate the causes of thoracic endovascular aortic repair (TEVAR) failure and conversion to open surgery (COS) in a vascular center with high-volume open surgery and low-volume TEVAR procedures. Methods A total of 8 patients (6 men; mean age, 55.14 years) underwent COS after TEVAR. The indications for COS, intraoperative strategy, and early postoperative and mid-follow-up results were analyzed. Results The indications for COS were persistent proximal type I endoleak with progressive aneurysm enlargement in 2 patients, type III endoleak in 1 patient, progressive aneurysm enlargement with no endoleak in 1 patient, stent-graft migration in 2 patients, secondary aortoesophageal fistula in 1 patient, secondary aortoesophageal and aortobronchial fistula in 1 patient, and distal progression of the aneurysmal disease in 2 patients. In all but one patient, thoracic stent grafts were explanted, and replacement with a Dacron graft was performed using left partial cardiopulmonary bypass. In the remaining patients with disconnection of the distal component and unfavorable anatomy, the proximal stent graft was recycled, and the Dacron prosthesis was sewn to it. Patients with secondary aortobronchial and aortoesophageal fistulas required additional bronchial and esophageal repair. The in-hospital mortality rate was 50% (4 patients). Four (50%) patients were followed up between 7 and 24 months (mean, 16.75 months) without mortality. Conclusions COS after TEVAR has a high mortality rate, and endovascular techniques should be considered as the first line of treatment. Those procedures should be performed by surgeons experienced in open repair which one might expect to be a challenging problem in the era of endovascular therapy.

Abstract. Background: The effect of atmospheric pressure (AP) on the onset of abdominal aorta aneurysm rupture (RAAA) remains an unanswered question. We have investigated the seasonal variation and the effect of AP dynamics on RAAA by analysing the largest series of intraoperatively confirmed RAAA. Patients and methods: To realize this study we have performed a retrospective analysis of 546 patients with RAAA, operated within 503 days at the Clinic for vascular and endovascular surgery CCS between 1.1.2003 and 31.12.2012. AP data for Belgrade city were obtained from meteorological yearbooks published by the Republic Hydrometeorological Service of Serbia measured at the hydrometeorological station “Belgrade Observatory”. Only patients with a residence within the extended Belgrade region, exposed to the similar AP values, were included in the analysis of the AP effect on RAAA. Results: RAAA were observed more frequently during winter and autumn months but without significant difference in comparison to other seasons. Months with higher AP values were associated with a higher RAAA rate (p = 0.0008, R2 = 0.665). A similar trend was observed for the monthly AP variability (p = 0.0311, R2 = 0.374). Average AP values did not differ between days with and without RAAA. However, during the three and seven days periods preceding RAAA AP variability parameters were greater and AP was rising. Conclusions: Although these pressure differences are very small, higher AP values over longer periods of time as well as greater variability are associated with RAAA. The exact mechanism behind this association remains unclear. The postulation that low AP may precipitate RAAA based on the Laplace law should be discarded.

Di-phase ceramic composites, with general formula xNi 0.7 Zn 0.3 Fe 2 O 4 – (1-x)BaTiO 3 (x = 0.9, 0.7, 0.5, 0.3, 0.1), were prepared by a mixing method. X-ray analysis, for powder and ceramics, indicated the formation of ferrite and barium titanate phases without the presence of the impurities. SEM analysis indicated that the composite morphology contained two types of grains, polygonal and rounded. Homogeneous microstructure and the smallest grain size were obtained in ceramics with 70% of barium titanate. The electrical properties of these materials were investigated using impedance spectroscopy, dielectric and ferroelectric measurements. The NZF-BT(30-70) composite has shown better electrical properties in comparison to other investigated ceramics, confirmed by dielectric and ferroelectric data analysis. Saturation magnetization and coercive field decreased with the increase of the content of ferroelectric phase.

The idea of this work is finding the way to efficiently and safely use mechanical energy released in small quantities around us to power up small-scale electronic devices used in everyday life. To this purpose, flexible lead-free piezoelectric composite films were prepared by hot pressing. Different amounts (30, 35 and 40 vol%) of lead-free piezoelectric material bismuth sodium titanate-barium titanate were embedded in the matrix of polyvinylidene fluoride under carefully optimized conditions of temperature and pressure, obtaining flexible films with quite homogeneous distribution of piezo-active filler. ATR-FTIR analysis revealed that hot pressing the flexible films caused a transformation of electro-inactive PVDF α-phase into electro-active β and γ phases. Dielectric measurements showed an increase of the permittivity up to 80 with the active phase increasing. Anelastic measurements showed that the elastic modulus increases as well with the fraction of active ceramic phase. Lastly, obtained flexible polymer-composites demonstrated notable properties both for energy storage and energy harvesting application, showing up to 74% of energy storage efficiency and, from testing of the force impact, up to 9 V and ~ 80 μW of output voltage and power.

We have studied Ho-doped BiFeO 3 nanopowders (Bi 1−x Ho x FeO 3 , x = 0–0.15), prepared via sol-gel method, in order to analyse the effect of substitution-driven structural transition on dielectric and ferroelectric properties of bismuth ferrite. X-ray diffraction and Raman study demonstrated that an increased Ho concentration (x ≥ 0.1) has induced gradual phase transition from rhombohedral to orthorhombic phase. The frequency dependent permittivity of Bi 1−x Ho x FeO 3 nanopowders was analysed within a model which incorporates Debye-like dielectric response and dc and ac conductivity contributions based on universal dielectric response. It was shown that influence of leakage current and grain boundary/interface effects on dielectric and ferroelectric properties was substantially reduced in biphasic Bi 1−x Ho x FeO 3 (x > 0.1) samples. The electrical performance of Bi 0.85 Ho 0.15 FeO 3 sample, for which orthorhombic phase prevailed, was significantly improved and Bi 0.85 Ho 0.15 FeO 3 has sustained strong applied electric fields (up to 100 kV/cm) without breakdown. Under strong external fields, the polarization exhibited strong frequency dependence. The low-frequency remnant polarization and coercive field of Bi 0.85 Ho 0.15 FeO 3 were significantly enhanced. It was proposed that defect dipolar polarization substantially contributed to the intrinsic polarization of Bi 0.85 Ho 0.15 FeO 3 under strong electric fields at low frequencies.

Conventional solid-state method was used to prepare powders of pure and barium titanate (BT) doped with different concentration of samarium. Influence of samarium addition on the structure modification, grain growth inhibition and microstructure development was studied. Dielectric properties of doped samples were significantly modified. With doping, a diffuse kind of ferro-para phase transition was induced, phase transitions positions were shifted and dielectric permittivity values were lowered in comparison with pure barium titanate. Detailed impedance and modulus data analysis were presented. The impedance complex plane showed two semicircular arcs for pure BT and one single depressed semicircular arc for all doped ceramics. Different electro-active regions in the modulus plane plots were also distinguish. The comparison between impedance and modulus scaling behavior presented the localized movement of charge carriers in the pure barium titanate and both, short and long range relaxations in the ceramics doped with 0.05 mol% of Sm. P-E hysteresis loops have shown the dilution of ferroelectric properties with Sm doping.

The effect of tungsten (W 6+ ) doping on modification of the structure, dielectric, ferroelectric and electrical properties of BaBi 4 Ti 4-x W x O 15 (BBTWx, x = 0, 0.03, 0.05 and 0.07) was investigated. The ceramic samples were synthesized by the conventional solid state reaction method. XRD data indicated the formation of single-phase layered crystalline structure that confirmed orthorhombic structure type of all compositions with space group A2 1 am . SEM micrographs suggest that the grain size slightly decreases with W doping. The temperature dependent dielectric study revealed that the dielectric constant decreases with W doping while transition temperature slightly increases. Influence of tungsten on relaxor behavior and diffuseness of phase transition is also discussed. Effect of W doping on the dielectric and electrical properties were investigated in terms of ion doping and defect mechanism. The ferroelectric properties were studied by P-E hysteresis loop and it was observed that the remanent polarization increases with a small level of W doping.

The growing interest in science community today is finding the ways to safely use mechanical energy which is being released in small portions around us. The idea of this work is to use vibrational energy present everywhere in small quantities to power the small-scale electronic devices used in everyday life. Flexible electronics, which can be bent, rolled, and stretched into arbitrary shapes, would significantly expand the application of modern electronic devices [1, 2]. As a lead-free piezoelectric material bismuth sodium titanate-barium titanate (BNBT) was selected and prepared by a solid state reaction. Since polymer polyvinylidene fluoride (PVDF) has interesting properties and advantages over the other polymers, it was used as a matrix for the processing of polymer/ceramics flexible films by hot pressing. Implementation of piezoelectric powder into the matrix of ?- phase PVDF was performed under the carefully optimized conditions of temperature and pressure. Three different volume rations of active phase vs. polymer (BNBT 30, 35 and 40 vol%) were used for the preparation of flexible films. The homogeneous distribution of piezoelectric powder in the polymer was obtained. IR analysis pointed that after the hot pressing, in the obtained flexible films, there is a transformation of electrically inactive PVDF ?-phase into electrically active ? and ? phases. Ferroelectric analysis evidenced the difficulties to obtain fully saturated hysteresis loops in inhomogeneous ferroelectric materials due to the formation of charge layers at the ferroactive-polymer phase interfaces. The dielectric permittivity for 40 vol% is nearly two times higher than for 30 vol% and eight times higher than for pure PVDF, while the losses at room temperature (at 1 kHz) remain below 3 %. Anelastic measurements confirmed the results obtained with the dielectric spectroscopy. [1] A. Jain et al. Polymer Engineering and Science, (2015) 1589-1616 [2] H. Li, Applied Physics Reviews 1, 041301 (2014)

The modern theoretical concept of independence is crucial for the establishment of institutional arrangements relating to monetary authority. It is theoretically demonstrated and empirically verified that a central bank can function effectively only if it is provided with institutional independence. The modern theoretical concept of central bank independence is presented in the first part of the paper, while the second part deals with applicable legislation defining the institutional framework and legal status of the National Bank of Serbia. By juxtaposing the formal and factual status currently afforded to the National Bank of Serbia with institutional arrangements derived from the practical application of the theoretical concept of independence, the author takes a critical position toward the domestic institutional framework. The adequate legal solutions are highlighted in the paper while, at the same time, the appropriate amendments are suggested for the solutions that clearly violate the institutional independence of the National Bank of Serbia.

This paper deals with the issue of whether intellectual property (IP) rights may be qualified as investments in terms of Serbian laws on investments, bilateral investment treaties (BIT) currently in force, and the ICSID Convention. The author first analyses the provisions of the Law on Investments with a special focus on the provisions defining an investment. By comparing these provisions with the corresponding norms of the previous law, as well as the relevant laws of the countries in the region, the enhanced solutions are highlighted, while the space for further improvement is identified. Subsequently, the author turns his attention to the applicable BITs and the ICSID Convention to examine whether IP rights may represent an investment under their terms. In the case of qualification of IP rights as investments, the right holders could be entitled to rely on the additional standards of legal protection and a new form of dispute settlement mechanism known as investment arbitration, while the host state could be exposed to a greater risk of being declared liable for breaches of legal standards and ordered to pay compensation to the investors. Upon analysing the main practical consequences of the qualification of IP rights, the author critically addresses major principles of the Serbian investment policy, which are identified through a detailed scrutiny of the relevant legal norms.

The paper identifies a widespread misapprehension concerning the purpose of the foreign currency clause and analyses the various possible reasons behind that misapprehension. The omnipresent dilemmas in domestic legal theory regarding the legal principle of monetary nominalism and valoristic doctrine are deliberated in the first part of the paper. The second part deals with the wider macroeconomic context in which the legislator enabled contractual arrangements containing foreign currency clauses, thus providing a comprehensive explanation as to the origins of factual errors, and thereby misinterpretation and misunderstanding of the law.

Mortality after open repair of ruptured abdominal aortic aneurysms (RAAAs) remains high. The purpose of this study is to present the results of open RAAA treatment observing 2 different 10-year periods in a single high-volume center and to consider the possibilities of result improvement in the future.Retrospective analysis of 729 RAAA patients who were treated through 1991-2001 (229 patients, Group A) and 2002-2011 (500 patients, Group B) was performed. Variables significantly associated with mortality were defined and analyzed.Overall 30-day mortality in Group A was 53.7% (123/229 patients) with intraoperative mortality of 13.5% (31/229 patients), while in Group B it was 37.4% (187/500 patients) with intraoperative mortality of 12.4% (62/500 patients). Overall 30-day mortality was significantly lower in Group B (P = 0.012). There was no difference regarding intraoperative mortality (P = 0.797). Preoperative severe hemodynamic instability (P 0.01, P 0.001), cardiac arrest (P 0.01, P 0.001), consciousness deterioration (P 0.05, P 0.001), renal malfunction (P 0.01, P 0.001), and significant anemia (P 0.01, P 0.001) were associated with increased mortality in both A and B groups, respectively. Aortic cross-clamping level in Group A was predominantly infrarenal (68%) while in Group B it was mostly supraceliac (53%) (P 0.001). Cross-clamping time, duration of surgery, and type of aortic reconstruction had no influence on survival in Group B (P 0.05). Intraoperative hemodynamic instability (P 0.01, P 0.001), significant bleeding (P 0.05, P 0.01), and low urine output (P 0.05, P 0.001) remained parameters that favored lethal outcome in both A and B groups, respectively. Cell saving was used only in Group B. The multivariate logistic regression applied on the complete sample of patients presented several significant predictors of lethal outcome: congestive heart failure on admission (odds ratio [OR] 1.954, 95% confidence interval [CI] 1.103-3.460), intraperitoneal rupture (OR 3.009, 95% CI 1.771-5.423), aortofemoral reconstruction (OR 1.928, 95% CI 1.044-3.563), and total operative time (OR 1.005, 95% CI 1.001-1.010). Postoperative multisystem organ failure (P 0.01, P 0.001), respiratory (P 0.01, P 0.001) and renal (P 0.05, P 0.001) failure, postoperative bleeding (P 0.05), and cerebrovascular incidents (P 0.05, P 0.01) significantly increased mortality in both A and B groups.Although unselective, aggressive surgical approach in RAAA performed by teams experienced in open repair can improve patient's survival. Short admission/surgery time, supraceliac aortic cross-clamping, and the use of intraoperative cell saving are recommended.

Bismuth ferrite is one of the most promising multiferroic materials, and the main barriers for exploiting all of its specific properties are difficulties in obtaining pure, high resistive material with nanosized grains. Doping of BiFeO3 with different transition metals and rare earth elements is often used way for overcoming these obstacles. Yttrium doped bismuth ferrite, Bi1−xYxFeO3 (x = 0; 0.01; 0.03; 0.05; 0.1), was prepared by auto-combustion method. X-ray diffraction patterns and Raman results showed that partial phase transition from rhombohedral to orthorhombic structure took place at around 10 mol% of Y. Effect of Y doping on microstructure was studied from SEM micrographies, showing the reduction of grain size in doped samples. Electrical measurements showed continuous improvement of resistivity with Y doping, whereas the values of saturation and remnant polarizations exhibit maximums at around 5 mol% of Y. Yttrium doping also enhanced magnetic properties, leading to weak ferromagnetism.

Acute lower limb ischaemia (ALI) as a result of popliteal artery aneurysm (PAA) thrombosis represents a significant problem. The aim of this study was to investigate outcome of intra-operative intra-arterial thrombolysis in the treatment of acute ischaemia due to PAA thrombosis in terms of major adverse limb events (MALE), overall survival, and intrahospital complications, especially those associated with bleeding.A total of 156 patients with Rutherford grade IIa and IIb acute ischaemia resulting from PAA thrombosis were admitted between 1 January 2011 and 1 January 2017. The patients were divided into two groups, those who underwent additional treatment with intra-operative intra-arterial thrombolysis (20 patients), and those who did not (136 patients). By using covariables from baseline and angiographic characteristics, a propensity score was calculated for each patient. Each patient who underwent intra-operative thrombolysis was matched to four patients from the non-thrombolysis group. Thus, comparable patient cohorts (20 in the thrombolysis and 80 in the non-thrombolysis group) were identified for further analysis. The primary end point was MALE and the secondary endpoint all cause mortality.After a median follow up of 55 months, the estimated MALE rate was significantly lower in the thrombolysis group (30% vs. 65%, chi square = 10.86, p .001, log rank test). Also, patients in the thrombolysis group had a significantly lower mortality rate (20% vs. 42.65%, chi square = 3.65, p = .05, log rank test). The thrombolysis group had wound/haematoma related interventions performed more commonly (25% in thrombolysis vs 8%, in non-thrombolysis group), but the difference was not significant (p=.013). There were no cases of major (intracranial and gastrointestinal) bleeding in either group.The data suggest that intra-operative thrombolysis in the treatment of selected patients with ALI due to PAA thrombosis has long term MALE and overall survival benefits, without a significant risk of major, life threatening bleeding complications.

Polycrystalline Bi 1−x Pr(Ce) x FeO 3 ceramics ( x = 0, 0.03, 0.05 and 0.10) were prepared by auto-combustion method using urea as a fuel. The influence of Pr(Ce) doping on structural, vibrational, morphological, dielectric and ferroelectric properties of BiFeO 3 polycrystalline ceramics was investigated. From X-ray diffraction (XRD) and scanning electron microscopy measurements it was observed that Pr(Ce) doping generated a reduction of the crystallite (grain) size of BiFeO 3 and contraction of the rhombohedral cell due to the increased compressive strain. The changes seen in the XRD and Raman spectra of 10% Pr(Ce)-doped samples, pointed to a probable appearance of orthorhombic (pseudotetragonal) crystal structure. The pristine BiFeO 3 exhibited rounded shape, non-saturated ferroelectric hysteresis loop. The dielectric constant and dielectric loss have shown strong dispersion at lower frequencies, typical for conductive BiFeO 3 . Dielectric and ferroelectric properties at room temperature were improved with Pr doping. Concerning the Ce-doped samples, only the 3% Ce-doped sample exhibited a better shaped hysteresis loop and improved dielectric properties compared to the pristine BiFeO 3 . With further increase of Ce content the ferroelectric properties degraded.

Made available in DSpace on 2018-12-11T17:31:22Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-12-01 Ministarstvo Prosvete, Nauke i Tehnološkog Razvoja Nickel zinc ferrite (NZF) and barium titanate (BT) were prepared by auto-combustion synthesis as an effective, simple and rapid method. Multiferroic composites with the general formula yNi1−xZnxFe2O4−(1−y)BT (x=0.3, 0.5, 0.7, y=0.5) were prepared by mixing NZF and BT powders in a liquid medium in the ball mill. The FEG micrographs indicated the primary particle size less than 100 nm for both, barium titanate and nickel zinc ferrite phases. X-ray analysis and Raman spectroscopy indicated the formation of well crystallized structure of NZF and BT phase in the composite powders and ceramics, with a small contribution of the secondary phase. The homogenous phase distribution in obtained composites was also confirmed. Impedance spectroscopy measurements were carried out in order to investigate the electrical resistivity of materials, showing that grain boundaries have greater impact on the total resistivity than grains. Saturation magnetization and remnant magnetization continuously decrease with barium titanate phase increase. Institute for Multidisciplinary Research University of Belgrade Institute of Physics University of Belgrade UNESP Faculty for Engineering UNESP Institute for Chemistry UNESP Faculty for Engineering UNESP Institute for Chemistry Ministarstvo Prosvete, Nauke i Tehnološkog Razvoja: III 45021

Aurivillius Bi5Ti3FeO15 (BTF) and Bi5−xLaxTi3FeO15 (BLTF) ceramics were successfully synthesized by a simple solid state reaction method. The samples were characterized by X-ray diffraction with no impurity phase identified. SEM micrographs show an evident decrease of grain size of La modified ceramics in comparison with pure BTF. Dielectric properties were investigated in a wide range of temperatures (300–1000 K) and frequencies (1 Hz–1 MHz). The Curie temperature was found to decrease in BLTF when compared to BTF ceramics. An energy bandgap of 1.83 and 1.77 eV for the BTF and BLTF ceramics, respectively was determined from UV–Vis diffuse absorption spectrum. Influence of La doping on ferroelectric and ferromagnetic measurements of both samples was also performed. Very weak ferromagnetism inside BTF can be observed while samples with La content showed complete paramagnetic behavior.

Modified Pechini process was used to prepare nanopowders of barium titanate (BT) co-doped with different concentrations of niobium and manganese. Influence of dopants on the grain growth inhibition and microstructure development was analyzed. The addition of dopants significantly influenced the dielectric properties modification. The obtained ɛ–T curves of all ceramics have the shape of typical ferroelectric material but the increase of dielectric permittivity value and movement of phase transitions with different dopant concentrations were clearly noticed. Grain and grain boundary resistivities for all co-doped ceramics were extracted from detailed impedance analysis and the grain boundary effect was indicated as a dominant effect in the total conduction of the materials. The well-defined and saturated P–E hysteresis loops of the ceramics confirmed the existence of ferroelectric properties.