Electrical Characterization and Impedance Response of Lanthanum Doped Barium Titanate Ceramics

The dielectric permittivity and dissipation factor of La-doped and undoped BaTiO3 were investigated as a function of frequency and temperature. The impedance response was used to study the electrical properties of La-doped BaTiO3 over the temperature range from room temperature (RT) to 350 degrees C. La-doped and undoped BaTiO3, obtained by a modified Pechini method, were sintered in air at 1300 degrees C for 2 and 16 hours. The impedance spectra were analyzed in terms of equivalent circuits involving resistors, capacitors and constant phase elements (CPE). The most suitable electrical circuit for the interpretation of experimental results is found to be the equivalent circuit consisting of resistors and CPE elements which replace the capacitor elements. The contribution of grain boundary resistance to the total resistance of a system is remarkable at low temperature. Dielectric permittivity of doped BaTiO3 was in the range of 8000 to 12000 at 1 kHz and the dissipation factor was less than 1%

Synthesis of Cerium-Activated Yttrium Aluminate Based Fine Phosphors by an Aerosol Route

Polycrystalline fine powders of yttrium aluminate doped with Ce³⁺ were synthesised by spray pyrolysis of a polymeric pre-cursor, which was obtained by dissolving the corresponding nitrates in a solution of ethylenediaminetetraacetic acid (EDTA) in ethylene glycol (EG). Aerosol decomposition was performed at 550 °C followed by an additional thermal treat-ment (900–1100 °C). The yield of either a single yttrium alu-minium perovskite (YAP) phase or a single yttrium alumin-ium garnet (YAG) phase was investigated as a function of the predefined yttrium/aluminium ratio, the cerium doping concentration, the processing temperature, and the thermal-treatment regime, which included the variation of the heat-ing and cooling rates (dT/dt), the residence time (τ), and the atmosphere. Changes in the composition and structure of the precursor during thermal decomposition were investigated by thermogravimetric and differential thermal analysis (TGA/DTA) and FTIR spectroscopy. The particle morphology and structure were analysed by a combination of scanning electron microscopy and energy-dispersive X-ray spec-troscopy (SEM/EDS) and by highresolution transmission electron microscopy (HR-TEM). The structural refinement was based on the phase identification performed by X-ray powder diffraction (XRPD). The emission spectra were re-corded within the range 325–800 nm by applying excitation wavelengths of 297 (YAP) and 450 nm (YAG). The employed synthesis conditions assured the formation of spherical, non-agglomerated particles with well-developed surfaces and diameters between 200 and 800 nm. For a predefined Y/Al ratio of 1:1, lower processing temperatures combined with longer heat treatments under stationary conditions resulted in a multiphase system, composed of YAP, YAG, and mono-clinic yttrium aluminate (YAM) phases. However, a short heat treatment with a high heating rate (200 °C/min) at higher temperatures results in the formation of a kinetically favoured pure YAP hexagonal phase. On the other hand, for a predefined Y/Al ratio of 3:5, the generation of a thermody-namically favoured pure YAG phase has been confirmed, re-gardless of the applied heat-treatment conditions. Although incomplete, Ce³⁺ introduction into the host matrix has been detected by XRPD and luminescence measurements.The authors gratefully acknowledge the Ministry of Science and Education of the Republic of Serbia (Project No 172035), the University Carlos III (Madrid, Spain), and the Santander Bank (Chairs of Excellence Program for the academic year 2010–2011) for financial suppor

FOLLOW-UP OF BIOCHEMICAL PARAMETERS AND INTENSITY OF OXIDATIVE STRESS IN PATIENTS WITH EXTRAHEPATHIC CHOLESTASIS

In cholestasis, due to impossibility of gall flow into duodenum, there occurs a subsequent return of gall constituents to hepatocytes and circulation. Extrahepatic cholestasis is the result of mechanic obstacle of gall flow through ductus hepaticus, choledochus or papilla Vateri, leading to the occurrence of manifest icterus. In cases leading to liver damage, hydrophobic gall salts and non-conjugated bilirubins have the most important toxic effects.The aim of this study was to follow up the biochemical parameters, enzyme activity AST, ALT, *-GT and AF, bilirubin concentration and albumins, and intensity of oxidative stress in blood plasma in patients with different types of extrahepatic cholestasis.The study included 60 subjects divided into two groups. The first one was control group (30 healthy subjects), while II group involved 30 patients with intraluminar extrahepatic obstruction.Significant increase of enzyme activity of AST, ALT, *-GT and AF in plasma of cholestatic patients was present in comparison to the control group (p< 0,001). The levels of total direct and indirect bilirubin in plasma of cholestatic patients increased (p<0,001) when compared to the control group. The level of albumin in plasma of cholestatic patients significantly decreased in comparison to the control group (p<0,05). The intensity of oxidative stress measured through the levels of malondialdehide (MDA) and carbonyl group concentration in plasma of cholestatic patients increased (p<0,001) when compared to the control group.Significant increase of cholestasis enzyme markers (AST, ALT, *-GT and AF) and bilirubin levels in blood plasma was noticed in patients with extrahepatic cholestasis. Cholestasis leads to significant disorders of synthetic function of the liver that are manifested by decrease of albumin concentration in plasma

MIGRATION PANORAMA | The Western Balkans migratory route: perspectives and persisting challenge. EPC Report December 2016 (2nd Edition)

In the past few years, the EU’s capacities have been stretched thin as it grappled with multiple challenges, leaving the Western Balkans and the EU membership aspirations of the countries in the region somewhat marginalised. But the Western Balkans suddenly returned to the top of the EU’s agenda last year as an unprecedented number of refugees crossed the Aegean Sea from Turkey to Greece and transited through the region to reach Central Europe. Given their geographic location and the fragility of the EU’s cooperation with Turkey, countries along the Western Balkans route have in fact become crucial partners for the effective management of migratory flows towards the EU. This second edition of the EPC’s Migration Panorama includes five articles offering diverse perspectives on the Western Balkans route, the region’s role in managing the influx, and how EU-Western Balkans cooperation on this issue might affect further progress on enlargement. Milica Mancic and Kristine Anderson of the International Rescue Committee highlight humanitarian considerations and the effect of EU policies on governance in the region; Vladimir Petronijević from Grupa 484, a Serbian NGO, focuses on the situation in Serbia – a key transit country at the heart of the Western Balkan route; Raphaela Engel of the Austrian Federal Ministry of Defence explains Austria’s special role in managing irregular migration flows in the region, stressing the importance of close cooperation with Balkan states; MEP Tanja Fajon’s contribution examines the impact of events on EU-Western Balkan relations and potential implications for EU enlargement; finally, the EPC’s Matteo Bonomi provides a comprehensive analysis of the political dynamics resulting from the refugee influx, in particular regarding EU enlargement

ANALYSIS OF A SQUARE COAXIAL LINE WITH ANISOTROPIC SUBSTRATES BY THE STRONG FEM FORMULATION

In this paper, concept of the strong Finite Element Method (FEM)formulation is explained first. A brief review of strong basis functions that are used forquasi-static analysis of transmission lines with piecewise homogeneous anisotropicmedium is presented next. As numerical examples, effective relative permittivities ofsquare coaxial lines with two anisotropic layers or one isotropic and one anisotropiclayer are calculated by using the Galerkin variant of the strong FEM formulation. It isshown that in the case of the half-filled line, effective relative permittivity is practicallyequal to the value obtained by a simple formula

Stressing Issue of a Piezoceramic Cantilever with Electrode Coatings and Transversal Polarization

This paper presents a general case of stressing a rectangular piezoceramic cantilever with transversal polarization which is loaded at the free end by a concentrated force. Two mutually opposite surfaces of the rectangular cantilever are with electrode coatings on which an excitation electric voltage is applied to. By applying the reverse method for solving the problems of electroelasticity theory, componential displacements, electric potential, specific strains, electric fields and piezoelectric displacements are determined for the rectangular piezoceramic cantilever made from PZT4 piezoceramic material

TECHNO-ECONOMIC OPTIMIZATION OF ENERGY SUPPLY OF A LIVESTOCK FARM

Livestock farming is a significant part of agriculture market in Serbia. A descending trend of livestock species was recorded recently, despite its potential for export of meet. Application of new technologies could improve competitiveness of livestock farming. In this paper, energy efficient energy supply technologies and potentials for their application in livestock farms is analyzed. A methodology for pinpointing profitable energy supply options which also provides significant energy and CO2 savings is proposed. A case study of a pig farm was used to perform an energy balance and allocation of energy supply costs. Potentials for application of energy supply technologies based on local resources were estimated in the study. Effects of integration of proposed technologies were also estimated. The proposed methodology was used to analyze feasibility of proposed energy supply options. Investment in a biogas cogeneration plant showed best profitability. Integrated option which envisages application of heat pump for heat supply and photovoltaic solar collectors for production of electricity showed best energetic and environmental performance, while maintaining financial feasibility

TECHNO-ECONOMIC OPTIMIZATION OF ENERGY SUPPLY OF A LIVESTOCK FARM

Livestock farming is a significant part of agriculture market in Serbia. A descending trend of livestock species was recorded recently, despite its potential for export of meet. Application of new technologies could improve competitiveness of livestock farming. In this paper, energy efficient energy supply technologies and potentials for their application in livestock farms is analyzed. A methodology for pinpointing profitable energy supply options which also provides significant energy and CO2 savings is proposed. A case study of a pig farm was used to perform an energy balance and allocation of energy supply costs. Potentials for application of energy supply technologies based on local resources were estimated in the study. Effects of integration of proposed technologies were also estimated. The proposed methodology was used to analyze feasibility of proposed energy supply options. Investment in a biogas cogeneration plant showed best profitability. Integrated option which envisages application of heat pump for heat supply and photovoltaic solar collectors for production of electricity showed best energetic and environmental performance, while maintaining financial feasibility

EFFECT OF A GEOMETRIC DEFECT ON LIGHT PROPAGATION THROUGH A COMPOSITE LINEAR PHOTONIC LATTICE

In this paper we investigated numerically light beam propagation through a one-dimensional composite photonic lattice composed of two structurally different lattices, with a geometric defect emerging at the interface between the two of them. Depending on the initial light beam position with respect to the geometric defect and the transverse tilt of the input beam, different dynamical regimes have been identified. Presented results may be useful for different applications, such as blocking, filtering and transporting light beams through optical media. UTICAJ GEOMETRIJSKOG DEFEKTA NA PROSTIRANJE SVETLOSTI KROZ KOMPOZITNU LINEARNU FOTONSKU REŠETKUU ovom radu, numerički je proučavano prostiranje svetlosnog snopa kroz jednodimenzionalnu fotonsku rešetku sastavljenu od dve strukturno različite rešetke. Spoj te dve rešetke je predstavljao geometrijski defekt. U zavisnosti od početnog položaja snopa i njegovog nagiba u odnosu na geometrijski defekt, prepoznati su različiti dinamički režimi. Rezultati predstavljeni ovde mogu biti korisni u različitim oblastima primene, kao što je blokiranje, filtriranje i prenošenje svetlosnog signala kroz optičke sredine. HIGHLIGHTSThe influence of a geometric defect (GD) on the propagation of a light beam across a linear composite lattice was investigatedThe influence of the asymmetric structure of the composite lattice was recognized in the evolution of a beam launched close to the area of GD;Depending on the initial beam parameters (initial position and transverse tilt), different regimes of light propagation were identified;Regimes of reflection and reflection and trapping, i.e. blocking of the beam by GD, could be phenomenologically associated with the Fano resonance;The results may be useful for different applications, such as blocking, filtering and transporting light beams through optical media.·         ·         The influence of a geometric defect (GD) on the propagation of a light beam across a linear composite lattice was investigated;·         The influence of the asymmetric structure of the composite lattice was recognized in the evolution of a beam launched close to the area of GD;·         Depending on the initial beam parameters (initial position and transverse tilt), different regimes of light propagation were identified;·         Regimes of reflection and reflection and trapping, i.e. blocking of the beam by GD, could be phenomenologically associated with the Fano resonance;The results may be useful for different applications, such as blocking, filtering and transporting light beams through optical media