The aim of this study was to evaluate the effect of rearing systems and genotypes on production performance and egg quality. Isa Brown and New Hampshire genotypes were used in this study. These two genotypes were housed in floor and organic rearing systems. During the experimental period, which lasted one year (52 weeks), the following production performance parameters were recorded: egg production, daily egg mass, feed consumption, feed conversion efficiency, and mortality. Fifteen eggs per group were collected for analysis at 64 weeks of hen age. These samples were evaluated for external parameters (egg weight and egg shape index), internal parameters (albumen height, Haugh unit, and the proportions of albumen, yolk and shell), eggshell quality parameters (shell thickness, shell deformation and shell breaking strength), and eggs' chemical composition (dry matter, minerals, protein and lipids). Generally, Isa Brown hens had better production performance than New Hampshire hens. At the same time, organic New Hampshire layers performed better than floor-reared ones. Genotype had a significant effect on all ten egg quality parameters (external, internal and eggshell quality), rearing system independently affected only egg weight, and the interaction of the observed factors significantly influenced seven parameters. Genotype had a significant effect on three of the four chemical composition parameters, while no significant effect of the rearing system was established on the chemical composition of eggs. The rearing system x genotype interaction significantly affected the eggs' protein content.

Nanosized Ag-doped ceria (Ce1-xAlxO2-delta)powders (0.1 <= x <= 0.04) were obtained by self-propagating room temperature reaction. The solid solubility of Ag into ceria lattice was the highest reported so far. X-ray diffraction analysis and field emission scanning microscopy results showed that the doped samples are single phase solid solutions with fluorite-type structure and all prepared powders were nanometric in size. The average size of Ce(1-x)Ag(x)O2-square particles lies at about 4 nm. Raman spectra revealed an increase in the amount of oxygen vacancies with the increase of Ag concentration, such as is foreseen. The thermal stability of solid solution was followed by XRD. Microstructure development was studied by scanning electron microscopy. By controlling the processing variables, it was possible to obtain high density samples with homogeneous microstructure at low sintering temperature.

The nanopowdery solid solutions of multidoped ceria Ce0.8Nd0.0025Sm0.0025Gd0.005Dy0.095Y0.095O2-δ (x=0.2) with the fluorite type crystal structure of CeO2 were synthesized for the first time. Two synthesis procedures were applied: the modified glycine-nitrate procedure (MGNP method) and room temperature self-propagating reaction (SPRT method). All nanopowders were characterized by XRPD analysis, Raman spectroscopy, low temperature nitrogen physisorption, TEM, and SEM methods. According to the XRPD and Raman spectroscopy results, single phase solid solutions of fluorite structure were evidenced regardless of the number of dopants and synthesis procedure. Both XRPD and TEM were analyses evidenced nanometer particle dimensions. The SPRT method results in obtaining sample with higher specific surface area, smaller crystallite and particles sizes, and the same values of the lattice parameter in comparison to pure CeO2. Raman spectroscopy was confirmed to the oxygen vacancies introduced into the ceria lattice when Ce4+ ions were replaced with cations (dopants) of lower valence state (3+), which may indicate the potential improvement of ionic conductivity. Additionally, the presence of oxygen vacancies in the lattice ceria, as well as very developed grain boundaries, gives a new possibility for potential application of obtained nanopowders in the area of room temperature ferromagnetism as spintronics.

The nanopowdery solid solutions of multidoped ceria Ce 0.8 Nd 0.0025 Sm 0.0025 Gd 0.005 Dy 0.095 Y 0.095 O 2−δ ( x = 0.2) with the fluorite type crystal structure of CeO 2 were synthesized for the first time. Two synthesis procedures were applied: the modified glycine-nitrate procedure (MGNP method) and room temperature self-propagating reaction (SPRT method). All nanopowders were characterized by XRPD analysis, Raman spectroscopy, low temperature nitrogen physisorption, TEM, and SEM methods. According to the XRPD and Raman spectroscopy results, single phase solid solutions of fluorite structure were evidenced regardless of the number of dopants and synthesis procedure. Both XRPD and TEM were analyses evidenced nanometer particle dimensions. The SPRT method results in obtaining sample with higher specific surface area, smaller crystallite and particles sizes, and the same values of the lattice parameter in comparison to pure CeO 2 . Raman spectroscopy was confirmed to the oxygen vacancies introduced into the ceria lattice when Ce 4+ ions were replaced with cations (dopants) of lower valence state (3+), which may indicate the potential improvement of ionic conductivity. Additionally, the presence of oxygen vacancies in the lattice ceria, as well as very developed grain boundaries, gives a new possibility for potential application of obtained nanopowders in the area of room temperature ferromagnetism as spintronics.

A series of four different powders ceria doped Ce1-xErxO2-delta (0.05 <= x <= 0.20) were synthesized by applying self-propagating reaction at room temperature (SPRT method). SPRT procedure is based on the self-propagating room temperature reaction between metal nitrates and sodium hydroxide, wherein the reaction is spontaneous and terminates extremely fast. The method is known to assure very precise stoichiometry of the final product in comparison with a tailored composition. XRPD, Raman spectroscopy, TEM and BET measurements were used to characterize the nanopowders at room temperature. It was shown that all obtained powders were single phase solid solutions with a fluorite-type crystal structure and all powder particles have nanometric size (about 3-4 nm). Densification was performed at 1550 degrees C, in an air atmosphere for 2 h. XRPD, SEM and complex impedance method measurements were carried out on sintered samples. Single phase form was evidenced for each sintered materials. The best value of conductivity at 700 degrees C amounted to 1.10 x 10(-2) Omega(-1) cm(-1) for Ce0.85Er0.O-3(2-delta) sample. Corresponding activation energies of conductivity amounted to 0.28 eV in the temperature range 500-700 degrees C. (C) 2015 Elsevier B.V. All rights reserved.

Plasmon-longitudinal-optical (LO) phonon interaction in pure and Nd-doped CeO2-y nanocrystals was investigated by measuring far-infrared reflectivity spectra in the 100-700 cm(-1) spectral range at room temperature. Analysis of the obtained results revealed that the presence of free charge carriers becomes significant with the particle size decrease to nanometer range and increase of lattice defects. The free charge carriers were found to be responsible for a plasmon mode which coupled strongly with two LO phonon modes of ceria. The presence of more pronounced low-frequency Drude tail and the screening of the phonon modes in Nd-doped CeO2-y nanocrystals implied that the Plasmon-LO phonon interaction increased with doping. Factorized and additive dielectric function models were applied to deduce about the coupled and decoupled LO phonon frequencies and the structure of the decoupled plasmon mode in pure and Nd-doped CeO2-y nanocrystals. These models were combined with Bruggeman effective medium approximation in order to properly describe the influence of porosity on the infrared reflectivity spectra. With increasing dopant content, the decoupled plasmon mode exhibited redshift and damping decrease implying that doping induced semiconductor-to-metalic state transition took place.

Ceramic pigments based on cerium oxide were synthesized by self-propagating room temperature method and their color properties were assessed from the viewpoint of potential environmentally nontoxic pink pigments. Thermal stabilities of the pigments were examined at 600, 900 and 1200 degrees C. According to X-ray powder diffraction and Raman spectroscopy results, all obtained pigments were singlephase solid solutions of cerium oxide, independent of the concentration of dopants. The X-ray analysis showed that the crystallites were of nanometric dimensions, as recorded and by transmission electron microscopy analysis. Color characteristics of solid solutions, which depended on concentration erbium ions and calcination temperature, and their position in the chromaticity diagram were studied by ultraviolet visible spectrophotometry, which confirmed potential application of environmentally friendly pigments of desired color. The color efficiency of pigments was also evaluated by calorimetric analysis. (C) 2015 Elsevier Ltd. All rights reserved.

Multidoped nanosized ceria powders were prepared by either modified glycine nitrate procedure (MGNP) or self-propagating reaction at room temperature (SPRT). As the dopants to CeO 2 , trivalent rare earth oxides such as Nd 2 O 3 , Sm 2 O 3 , Gd 2 O 3 , Dy 2 O 3 and Y 2 O 3 were used, with the total molar fraction of 20%. The pressed powder pellets were subjected to the densification by sintering at 1500 °C, in an air atmosphere. A single-phase crystalline form was evidenced by X-ray diffractometry for both sintered materials. By means of complex impedance measurements, the conductivity of the sintered samples was determined as a function of temperature. At 700 °C, the conductivity amounted to 2.19×10 −2 and 1.40×10 −2 Ω −1 cm −1 for the SPRT and for the MGNP sample, respectively. The corresponding values of activation energies of conductivity amounted to 0.72 (MGNP) and 0.59 (SPRT) eV in the temperature range 550–700 °C.

Background/Aim: Satisfaction with the chosen profession is significant aspect of work and life every individual, society and is important for progress of profession. Its not always easy for individual to recognize which profession is the best for her/him. Adolescence itself is specific period of development. The dilemma by choosing profession in that period represents one of the most important challenges the youth have to confront with. The aim of this research was to determine satisfaction of pupils and students career choice at Secondary Medical School in Belgrade and Collage of Professional Studies in Belgrade. Methods: Examination included 200 examinees, 100 graduated Secondary Medical School in Belgrade and 100 students of Collage. It has been made the questionary for this purpose, which was consisted of several thematic units. Results. Motives for choice of profession were internal - love towards job and a desire for new knowledges, and external - bigger chances for employment and higher income. Tested pupils and students are satisfied with their knowledge and the capability for independent work, a large number of responders wanted to continue their education. Responders in generally were satisfied with the choice of profession (87% students and 75% graduated Secondary Medical School believe that they made a good career choice). Conclusion: Socialization for the profession at responders is very important to retain experts in branch of business and it needs to be devoted by special attention in the future. Satisfaction by chosen profession is significant aspect of the work and life of every man, and especially the staff in the health sector, considering the delicacy of profession.

Nanometric ceria powders with fluorite-type structure were obtained by applying self-propagating room temperature method. The obtained powders were subsequently thermally treated (calcined) at different temperatures for different times. Powder properties such as specific surface area, crystallite size, particle size and lattice parameter have been studied. Roentgen diffraction analysis (XRD), BET and Raman scattering measurements were used to characterize the as-obtained (uncalcined) powder as well as powders calcined at different temperatures.It was found that the average diameter of the as-obtained crystallites is in the range of 3–5nm whereas the specific surface area is about 70m2/g. The subsequent, 15min long, calcination of as-obtained powder at different temperatures gradually increased crystallite size up to ∼60nm and reduced specific surface down to 6m2/g. Raman spectra of synthesized CeO2−y depicts a strong red shift of active triply degenerate F2g mode as well as additional peak at 600cm−1. The frequency of F2g mode increased while its line width decreased with an increase in calcination temperature. Such a behavior is considered to be the result of particle size increase and agglomeration during the calcination. After the heat treatment at 800°C crystallite size reached value larger than 50nm. Second order Raman mode, which originates from intrinsic oxygen vacancies, disappeared after calcination.

Density, microstructure and microhardness have been investigated for samples, sintered from submicro-alpha-SiC and micro-SiC powders as well as their mixtures with addition of 50 vol.% alpha-Si3N4 nanopowder in the temperature interval 1500-2000 degrees C under pressure of 4 GPa. The dispersed silicon carbide submicron powder and the composite of submicro-SiC/nano-Si3N4 powder mixture have the most homogeneous microstructure and the higher hardness (respectively, up to 24 GPa and 22 GPa).

Ceria ceramics was obtained from multi-doped nanosized ceria powders prepared by both modified glycine nitrate procedure (MGNP) and self-propagating reaction at room temperature (SPRT). Rare earth elements such as Nd, Sm, Gd, Dy, Y, Yb were used as dopants. The overall mole fraction of dopants was 0.2. One-hour long sintering of powder compacts was performed at 1500°C in oxygen atmosphere. Phase composition, microstructure and ionic conductivity of sintered samples were analysed. Single-phase ceria was detected in all samples. In general, the increase in the number of dopants improved the ionic conductivity. The samples doped simultaneously with five dopants had the highest ionic conductivity, as evidenced by the impedance measurements. At 450°C, the conductivity of sample obtained by MGNP was 3.94×10−3Ω−1cm−1 whereas the conductivity of sample obtained by SPRT was 2.61×10−3Ω−1cm−1. The conductivity activation energy for MGNP and SPRT samples was measured to be 0.348 and 0.385eV, respectively. Finally, the conductivity decreased as the number of dopants increased to six.

In this paper a short review of our results on the synthesis of nanosized CeO2, CaMnO3 and BaCeO3 solid solutions are presented. The nanopowders were prepared by two innovative methods: self propagating room temperature synthesis (SPRT) and modified glycine/nitrate procedure (MGNP). Different types of solid solutions with rare earth dopants in concentrations ranging from 0-0.25 mol% were synthesized. The reactions forming solid solutions were studied. In addition, the characteristics of prepared nanopowders, phenomena during sintering and the properties of sintered samples are discussed.

The electron-doped magnetic nanoparticles of Ca1-xYxMnO3 (x = 0, 0.05, 0.10, 0.15, 0.20, and 0.30) manganite with an average particle size of 50 nm are analyzed and discussed in relation to their bulk counterparts. Nanoparticle samples show dominant anti-ferromagnetic ordering with a significant increase of coercivity, with the maximum value of 0.9 T for x = 0. Particle size reduction in Ca1-xYxMnO3 retains the bulk-like magnetic behavior of samples having up to 15% of Y3+, with the small ferromagnetic contribution from disordered surface spins. Suppression of charge ordering state and enhancement of saturation magnetization were found in samples with higher Y3+ concentration (x = 0.2, 0.3), indicating high ferro-magnetic contribution in these samples.

This paper is dealing with the synthesis of zirconia/silicon carbide (ZrO2/SiC) and ZrO2 powders obtained by carbothermal reduction of natural mineral zircon (ZrSiO4). For the first time, the influence of carbon to ZrSiO4 ratio is thoroughly investigated for a wide range of compositions (C/ZrSiO4=1–8) and temperatures (1473–1973K). The zircon powder was mixed with activated carbon as a reducing agent and heat treated in a controlled flow atmosphere of Ar. Periclase (MgO) was added in order to facilitate the formation of high temperature form of zirconia as well as to examine the possible catalytic effect of MgO on the overall reaction. Phase evaluation and phase content were followed as a function of temperature, C/ZrSiO4 ratio and different quantity of introduced MgO. The obtained powders were characterized by means of ex-situ X-ray diffraction and SEM/EDS investigation. It was found that, depending on C/ZrSiO4 ratio, it is possible to produce either a m-ZrO2, c-ZrO2 or ZrO2/SiC powders by using zircon as precursor.

SiC-TiB2 particulate composites were fabricated by converting TiO2 to TiB2 through the reaction between TiO2, B4C and C. The presence of initially very fine, in-situ created, TiB2 particles increased driving force for sintering and enabled fabrication of a dense composite utilizing pressureless sintering and the liquid phase created between Al2O3 and Y2O3 additives. The effect of volume fraction of the in-situ formed TiB2 on density, microstructure and flexural strength was discussed. It was found that the presence of TiB2 particles suppressed the growth of SiC grains and enhanced fracture strength. The fracture strength of samples containing 12 vol% TiB2 was more than 30% higher than that of the monolithic SIC. The effect of SIC grain size on fracture strength was also analyzed. (C) 2010 Elsevier B.V. All rights reserved.

Nanocrystalline hexagonal boron nitride powder (h-BN) was synthesized by sol–gel polycondensation of resorcinol and formaldehyde in the presence of boric acid followed by freeze drying. Pyrolysis and subsequent heat treatment of these cryogels resulted in formation of boron nitride powder. Characterization by nitrogen adsorption showed that precomposite cryogels and the BN powders were micro and mesoporous materials with high surface areas. Materials have been analyzed by means of X-ray diffraction, Raman scattering and electron microscopy methods.

Structure and magnetic features of nanostructured materials with general formula Ca1-xYxMnO3 (x = 0; 0.1; 0.2; 0.3) were investigated. Goldschmidt tolerance factor, Gt and global instability index, GII were calculated for Ca1-xYxMnO3 (x = 0, 0.25, 0.5, 0.75, 1) using the software SPuDS (Structure Prediction Diagnostic Software). According to these two parameters possibility of forming perovskite structure type for Ca1-xYxMnO3 solid solution was analyzed. Substitution of Y3+ for Ca2+ provokes reduction of equivalent amount Mn4+ into Mn3+, the presence of which is a reason for many interesting magnetic, transport and structural features of doped CaMnO3. Crystal structure refinement was carried out using Rietveld analysis. Ca1-xYxMnO3 (x = 0; 0.1; 0.2; 0.3) has an orthorombic, Pnma space group that, according to Glazer?s classification belongs to a-b+a- tilt system. Influence of Y amount on Mn-O bond angles and distances, tilting of MnO6 octahedra around all three axes and octahedra deformation were analyzed. Bond valence calculations (BVC) were performed to determine Mn valence state. Using EPR (electron paramagnetic resonance) magnetic measurements were performed and magnetic properties of solid solutions, orthorombicity degree of unit cell, as well as Mn4+/Mn3+ cations ratio in position B were analyzed. Microstructure size-strain analysis was performed and these results are in nanometric range which is confirmed by TEM images.

In this paper nanometric powders of solid solution of the host compound ceria (CeO2) with Pr dopant in the lattice were synthesized by self-propagating room temperature (SPRT) synthesis with composition (Ce0.9Pr0.1O2-delta). Powder properties such as specific surface area crystallite and particle size and lattice parameters have been studied. BET, TEM, X-ray diffraction (XRD) analysis and Raman scattering measurements were used to characterize the samples at room temperature. Obtained solid solution exhibits a fluorite-type crystal structure. The average crystallite size is about 3-4 nm. Williamson-Hall plots were used to separate the effect of the size and strain in the nanocrystals. It is noticed the redshift and asymmetric broadening of the Raman F-2g mode which is explained with nanocrystalline nature of powders.Color characters of solid solution depending on calcinations temperature and their position in the chromaticity diagram were studied by UV-vis spectrophotometry (diffuse reflectance). (C) 2010 Elsevier B.V. All rights reserved.