bluuebunny/crossref_metadata_2025 huggingface dataset:
Dr. Djura Djurovic a lifelong opponent of Yugoslav communist totalitarianism
Authors: Markovich Slobodan
Published: January 2013

The paper deals with the life story of Dr. Djura Djurovic (1900-1983), one of
key targets of Yugoslav communist totalitarianism. He was a Belgrade lawyer
who worked in the Administration of the City of Belgrade before WWII. In 1943
he joined the Yugoslav Home Army (YHA) of General Mihailovic, and held high
positions in the YHA press and propaganda departments. His duties included
running the Radio-telegraphic agency Democratic Yugoslavia. He accompanied
General Mihailovic on his meetings with OSS Colonel McDowell, and with
Captain Rakovic he established successful cooperation with Red Army units in
October 1944. He was arrested by Tito?s partisans in 1945, given a show-trial
and sentenced to twenty years in prison. In his writings he described
horrible conditions, sufferings and various types of torture used against
political prisoners in Yugoslav communist prisons. He himself spent more than
two years in solitary confinement, and on several occasions nearly died in
prison. He was released in 1962, and was able to establish a circle of former
political convicts from the ranks of the YHA and other anticommunists in
Belgrade and Serbia. He maintained this network, advocated pro-American
policies and hoped that at some point the United States might intervene
against communism in Yugoslavia. Gradually he came to the conclusion that
Tito was an American ally, and was satisfied to maintain his network of
likeminded anticommunists and prepare reports on the situation in Yugoslavia.
As a pre-war freemason, he sent one such report to Luther Smith, Grand
Commander of AAFM of Southern Jurisdiction of American masons, describing the
ghastly conditions in Yugoslav communist prisons. He was rearrested in 1973
on account of his relations with a Serbian ?migr? in Paris, Andra Loncaric,
and spent another four years in prison. Thus, the almost twenty-one years he
spent in communist prisons qualify him for the top of the list of political
prisoners in Yugoslav communism. In 1962-1973 he was spied on by a network of
in?formers and operatives of the Yugoslav secret service. The paper is based
on Djurovic?s personal files preserved in the penitentiaries in Sremska
Mitrovica and Zabela, and his personal file from the archive of the Yugoslav
secret service (UDBA/SDB). This is the first paper based on personal files of
?political enemies? compiled by the Yugoslav communist secret service,
disclosing the latter?s activities and methods against anti?communist circles
in Belgrade.
Modeling of arterial stiffness using variations of pulse transit time
Authors: Peulic Aleksandar , Milojevic Natasa , Jovanov Emil , Radovic Milos , Saveljic Igor , Zdravkovic Nebojsa , Filipovic Nenad
Published: January 2013

In this paper, a finite element (FE) modeling is used to model effects of the
arterial stiffness on the different signal patterns of the pulse transit time
(PTT). Several different breathing patterns of the three subjects are
measured with PTT signal and corresponding finite element model of the
straight elastic artery is applied. The computational fluid-structure model
provides arterial elastic behavior and fitting procedure was applied in order
to estimate Young?s module of stiffness of the artery. It was found that
approximately same elastic Young?s module can be fitted for specific subject
with different breathing patterns which validate this methodology for
possible noninvasive determination of the arterial stiffness.
Institutional homes: The evolution of open space in the case of some workers' colonies in history
Authors: Zupancic Domen
Published: January 2013

This is a critical review of examples of how workers' settlements have been
organized throughout history. I examine some examples of workers' settlements
from the perspective of spatial organization, architectural economics and
urban design. The hypothesis is that workers' dwellings have not basically
changed since the earliest civilizations. The role of workers' dwellings has
been constantly on the fringes of spatial organization. Generally, workers as
a class were not considered an integral part of business management. Workers
are part of any industrialized process and cannot be overlooked in an
architectural analysis of their dwellings. The conclusions of the paper are
oriented from praxis to theory. Analogies from the past to the present are
presented, with a set of sketches in which the theory of spatial
organization, architectural economics and urban design patterns may be
evident.
Towards preparation of design spectra for Serbian National Annex to Eurocode 8: Part I: spectral shapes and regional empirical equations for scaling pseudo-acceleration spectra
Authors: Bulajic Borko , Manic Miodrag , Ladjinovic Djordje
Published: January 2013

Eurocode 8 allows that any country can use its own shape of the elastic
response spectrum after it defines it in the National Annex. Having in mind
that such country-specific spectra are to be derived through analysis of the
strong motion data recorded in the considered seismo-tectonic region, in this
Paper we discuss the existing and a set of new empirical equations for
scaling pseudo-acceleration spectra in Serbia and the whole region of
north-western Balkans. We then compare the presented spectra to those
proposed by Eurocode 8. Results show that the indiscriminate use of the
strong motion data from different seismo-tectonic regions, improper
classification of the local soil conditions, and neglect of the effects of
deep geology, may all lead to unreliable scaling equations and to extremely
biased ground motion estimates. Moreover, only two spectral shapes that are
defined for wide magnitude ranges and scaled by a single PGA value, are not
able to adequately represent all important features of real strong ground
motion, and instead of using such normalized spectra one should rather employ
the direct scaling of spectral amplitudes that is based on the analysis of
regionally gathered and processed strong motion data.
Shape grammar in contemporary architectural theory and design
Authors: Tepavcevic Bojan , Stojakovic Vesna
Published: January 2013

In the past decade, digital technologies had a great impact on contemporary
architectural practice, design and theory. CAD/CAM technologies opened up new
opportunities by allowing design and production of complex geometric shapes.
One of the first applications of computational process in architecture was
based on using shape grammars, a rule-based expert systems in artificial
intelligence generating geometric shapes. Early applications of shape
grammars in art and architecture started shortly after its invention during
the 70ies and 80ies of the XX century, however, their potential as a
generative design tool still has not been fully exploited in practice.
Despite their popularity in academic circles, shape grammars have not found a
widespread place/usage in computer aided architectural design. Role of shape
grammar as a generative design and analysis tool and their influence on
contemporary architectural design and theory are examined in this paper.
Also, new and ongoing issues concerning shape grammars are discussed in order
to indicate further directions of their usage.
Sustainable schools as 3D textbooks: Safeguards of environmental sustainability
Authors: Brkovic Marta , Milosevic Predrag
Published: January 2013

At times when Serbia is planning to invest in improving the quality of
learning environments up to a hundred million Euros through School
Modernization Project 2010-2014, describing some of the trends in school
buildings design in Western countries is regarded to be crucial. Schools are
places where young members of our society are educated. School building
design can have a direct influence on the way we assimilate, learn and
integrate with other people, and can also affect the way we, as a society,
integrate sustainability into our lives. A building is able to teach and
convey new ways of materializing sustainable principles. Nowadays many
experts claim that ?sustainable school is the most appropriate strategy for
renovating educational processes and achieving quality education' [1].
Therefore, this paper deals with some of the aspects of school development in
relation to environmental sustainability principles. Each aspect is supported
by an example of a contemporary school that included one or more of those
principles. Towards the end some of the benefits of approaching schools with
environmental sustainability in mind are presented. It is hoped that the
results of this article will act as an invitation and stimuli for architects
and planners, especially in Serbia, to reconsider their previous practice and
start observing school design through the prism of sustainable development.
Waste glass as additive to clayey material in subgrade and embankment of road pavement
Authors: Davidovic Nebojsa , Bonic Zoran , Prolovic Verka
Published: January 2013

In this paper the possibility of using waste glass in road construction is
discussed. Samples of clay material with the addition of waste glass were
subjected to a series of laboratory geotechnical tests performed at the
Laboratory of Geotechnics at the Faculty of Civil Engineering and
Architecture in Nis. The obtained results were compared with criteria defined
in the document ?General technical requirements for road construction?. On
this basis, the conclusions on the suitability of this mixture for the
intended purpose are given.
The subsurface geology along the route of the new bridge at Ada Ciganlija Island (Belgrade, Serbia)
Authors: Knezevic Slobodan , Rundic Ljupko , Ganic Meri
Published: January 2013

The largest single-pylon, cable-stayed bridge in the world was opened in
Belgrade on January 1, 2012 and it passes over the tip of the Ada Ciganlija
Island. Its monumentality, architectural design and construction innovations
became a new symbol of Belgrade. Core samples from the boreholes drilled for
the construction of the bridge revealed a relatively complex subsurface
geological structure. An Upper Cretaceous-Paleogene flysch formation and
Middle Miocene Sarmatian sediments were found near the surface on the right
bank of the Sava River. However, at the tip of Ada Ciganlija, the Upper
Cretaceous-Palaeogene flysch strata were found below several different
Miocene and Quaternary units. In the deepest borehole DB-6, the flysch
deposits were found at a depth of 80 meters. On the left bank of the Sava
River in New Belgrade, only Upper Miocene Pannonian marls and Pleistocene and
Holocene alluvial deposits were drilled. Based on a comparative analysis of
the borehole sections and structural characteristics of the rocks, it could
be concluded that the Pre-Quaternary units cascade subsided along
sub-parallel faults towards N-NW.
Upper cretaceous of the Cerevicki Potok, Fruska Gora Mt., Serbia: State of art
Authors: Radoicic Rajka , Jovanovic Divna
Published: January 2013

The paper is dealing with three interpretations of well known section
Cerevicki Potok (Fruska Gora Mt., Serbia): 1. According to KOCH, in: PETH?
(1906), undisturbed succession of 23 lithologically different members,
?Hipersenonian?; 2. According to PASIC (1974; unpublished text is used in
monography of PETKOVIC et al. 1976), tectonically disturbed lithologically
different Maastrichtian blocks; and 3. According to CICULIC-TRIFUNOVIC &
RAKIC (1977), tectonically disturbed stratigraphic column, the Srem-Slavonian
type of the Upper Cretaceous sediments, south of Srem dislocation,
Maastrichtian.
Correlation of metabasic rocks from metamorphic soles of the Dinaridic and the Western Vardar zone ophiolites (Serbia): Three contrasting pressure-temperature-time paths
Authors: Sreckovic-Batocanin Danica , Vaskovic Nada , Matovic Vesna , Gajic Violeta
Published: January 2013

The field, petrological-mineralogical, geochemical and geochronological data
of the metamorphic sole rocks recorded beneath the Fruska Gora, Povlen
(Tejici), Stolovi and Banjska ophiolites in the Western Vardar Zone (WVZ) and
beneath the Zlatibor, Bistrica, Sjenicki Ozren and Brezovica ophiolites in
the Dinaridic ophiolite belt (DOB) in Serbia are compared. The focus has been
made on metabasic rocks formed in contact with the oceanic crust members:
cumulate gabbro and basalts of SSZ-type with E-MORB and OIB-signature and
more evolved tholeiitic basalts of MOR-affinity. Amphibole, the major phase
formed from the mafic sole components, depending on pressure-temperature
conditions exhibits compositional variations. According to mineral
assemblages, estimated P-T conditions and ages, the potential P-T paths are
given: high pressure - low temperature blueschist facies assemblage (7-9 kbar
and ~400?C and <300-350?C and 4-8 kbar), recorded only in the metamorphic
sole at the Fruska Gora (WVZ); high pressure - high temperature amphibolite
to granulite facies (8-10 kbar and >700-850?C), recorded in both domains, the
WVZ (Banjska) and the DOB (Bistrica, Sjenicki Ozren, Brezovica) and medium
pressure - medium temperature amphibolite facies assemblages (~3.5-7 kbar and
>350-650?C) recognized in the WZV (Tejici, Devovici) and the DOB (Zlatibor).
The peak metamorphic conditions point to depths of the oceanic lithosphere
detachment and its initial cooling at 10-30 km, but the ages and tectonic
setting of ophiolites remain poorly constrained. The summarized data may be
used as an important key in geodynamic evolution of the Mesozoic Tethyan
ophiolites.
The impact of geology on the migration of fluorides in mineral waters of the Bukulja and Brajkovac pluton area, Serbia
Authors: Papic Petar , Djokovic Ilija , Stojkovic Jana , Jovic Vidojko , Marinkovic Goran , Nikic Zoran
Published: January 2013

One of the hydrogeochemical parameters that classify groundwater as mineral
water is the content of fluoride ions. Their concentration is both important
and limited for bottled mineral waters. Hydrochemical research of mineral
waters in the surrounding area of Bukulja and Brajkovac pluton, in central
Serbia, was conducted in order to define the chemical composition and genesis
of these waters. They are carbonated waters, with content of fluoride ranging
from 0.2 up to 6.6 mg/L. Since hydrochemical analyses showed variations in
the major water chemistry, it was obvious that, apart from hydrochemical
research, some explorations of the structure of the regional terrain would be
inevitable. For these purposes, some additional geological research was
performed, creating an adequate basis for the interpretation of the genesis
of these carbonated mineral waters. The results confirmed the significance of
the application of hydrochemical methods in the research of mineral waters.
The work tended to emphasize that ?technological treatment? for decreasing
the concentration of fluoride in mineral waters occurs in nature, indicating
the existence of natural defluoridization.
Factors contributing to the formation of carbonated mineral water systems in Serbia
Authors: Marinkovic Goran , Papic Petar , Stojkovic Jana , Dragisic Veselin
Published: January 2013

There are more than 65 occurrences of carbonated mineral water (CMW) within
the territory of Serbia. More than 93 % of these systems are found in the
geotectonic unit referred to as the Vardar Zone and on the fringes of nearby
units. To the east, west and north of the Vardar Zone, CMWs are either rare
or nonexistent. The area featuring CMWs is characterized by Tertiary
magmatism, a complex geology and deep neotectonic structures. Based on ?13C
values of CO2 and HCO3 - in several CMWs in Serbia, and also in carbonates
and CO2 from liquid inclusions in several hydrothermal deposits around the
world, it was concluded that CO2 in the lithosphere of Serbia could originate
from hydrothermal carbonates, and carbonates from sedimentary, metamorphic
and magmatic rocks. The findings clearly showed that the main generators of
CO2 are located in the Vardar Zone and that CO2 degasification is
accomplished through temperature metamorphosis of carbonates (dolomite,
calcite). Based on the carbonate transformation temperatures and the
temperature conditions in the lithosphere of Serbia, the CO2 might be the
result of temperature-induced carbonate transformation below a depth of 3 km.
Therefore, the conclusion of the study of CMWs in Serbia is that the
formation of CMW systems in the lithosphere depends on the geochemical,
temperature, and the magmatic and structural-neotectonic conditions.
Characterization and properties of barium bismuth titanate
Authors: Bobic Jelena , Vijatovic Mirjana , Rojac Tadej , Stojanovic Biljana
Published: January 2013

BaBi4Ti4O15 (BBiT) was prepared from stoichiometric amounts of BaTiO3 (BT) and Bi4Ti3O12 (BIT) obtained via mechanochemical synthesis. Mechanochemical synthesis was performed in air atmosphere in a planetary ball mill. BBiT ceramics were sintered at 1100?C, 1110?C and 1120?C for 1 h without pre-calcination step. The formation of phase and crystal structure of BT, BIT and BBiT were verified using X-ray analysis. The morphology of obtained powders and microstructure were examined using scanning electron microscopy. The electrical properties of sintered samples were carried out and BBiT shows behaviour typical for relaxor ferroelectrics and dielectric constant at room temperature is approximately 93. .
Microemulsion mediated synthesis of BaTi03-Ag nanocomposites
Authors: Yoon Songhak , Dornseiffer Jürgen , Hennings Detlev , Pithan Christian , Waser Rainer
Published: January 2013

BaTiO3 - Ag composite nanopowders were synthesized via microemulsion mediated synthesis through the hydrolytic decomposition of mixed metal alkoxide solutions as precursor for the BaTiO3 and the reduction of silver nitrate in the presence of polyvinylpyrrolidone (PVP) as source for the Ag nanoparticles. The X-ray diffraction (XRD) patterns indicate that BaTiO3 and Ag phases were successfully synthesized in the composite powders. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) show that the synthesized BaTiO3 nanoparticles were aggregates of nanosized primary particles as small as 10 nm in diameter and the average particle size of nanocrystalline Ag was about 100 nm. Calcination and sintering studies reveal that there exists a difference in the sintering behaviour of BaTiO3 and Ag in the composite nanopowders. Thermogravimetric analysis (TGA) shows weight losses due to the burnout of organic residues arising from the synthesis, the release of water from the surface and separation of hydroxyl ions from the lattice of BaTiO3 nanoparticles. A dilatometric study of BaTiO3-Ag composite confirmed a strong difference in the shrinkage behaviour compared to that of the pure BaTiO3 obtained by microemulsion mediated synthesis. .
Mesoporous silica matrices derived from sol-gel process assisted by low power ultrasonic activation
Authors: Savii Cecilia , Almásy László , Ionescu Claudia , Székely Kinga , Enache Corina , Popovici Mihaela , Sora Ioan , Nicoara Dan , Savii Gustav , Resiga Susan , Subrt Jan , Stengl Václav
Published: January 2013

The present work contributes to elucidating the differences between silica gels obtained by low doses ultrasonic activation, and those obtained by the conventional method, termed as classical sol gel. Silica matrices were produced by sol-gel synthesis process, assisted and non-assisted by an ultrasonic field, and subsequently characterized by various methods. Nitrogen adsorption and small-angle neutron scattering (SANS) measurements provided texture and microstructure of the dried gels. The adsorption results show that the sample sonicated for 2 hours presents the most ordered microstructure, characterized by pore shape close to spherical and the narrowest size distribution - about 90 % of the pores for this sample fall into the mesopore range (2-50 nm). SANS data reveal the formation of primary structural units of sizes around 1.5-2 nm which are small linear or branched polymeric species of roughly spherical shape and with rough surface. They are generated in the very early stage of sol gel process, as a result of hydrolysis and condensation reactions. The aggregated primary units form the secondary porous structure which can be described as a rough surface with fractal dimension above 2. The best porosity characteristics were obtained for the sample activated for 2 hours, indicating the optimal doses of sonication in the present conditions. Our results demonstrate the possibility of tailoring the pore size distribution using a low power ultrasonic bath. .
Influence of the synthesis route on the properties of BNBT ceramics
Authors: Mercadelli Elisa , Sanson Alessandra , Capiani Claudio , Costa Luisa , Galassi Carmen
Published: January 2013

BNBT (0.94[(Bi0.5Na0.5)TiO3]-0.06BaTiO3) nanopowders were prepared starting from an aqueous solution of inorganic salts (barium acetate, bismuth nitrate, sodium nitrate and titanium isopropoxide) either by the citrate- nitrate sol-gel combustion (SGC) or by spray drying (SD). Their chemical and microstructural properties were compared with the ones of the same system obtained by mechanical mixing of oxides (SSCO). The SD and SGC powders require temperatures 150 and 300?C lower than SSCO powder to form the perovskite phase. The chemical and physical properties of the obtained powders strongly depend on the considered chemical route. Therefore the subsequent sintering step and consequently the microstructure of the obtained ceramics differ significantly. The microstructures as well the piezoelectric properties of the sintered SGC, SD, SSCO samples are investigated and a critical comparison is presented. .
Synthesis and characterization of Ce and La modified bismuth titanate
Authors: Pavlovic Nikolina , Kancko Dejan , Szécsényi Mészáros , Srdic Vladimir
Published: January 2013

Bismuth titanate based nanopowders with the different content of La or Ce were synthesized by the modified sol-gel method. After calcination at 600?C, in addition to Aurivillius layered structure, a small quantity of cubic pyrochlore phase was detected in the La modified powders, while this second phase was much more pronounced in the Ce substituted powders. In fact, as the powder with the highest amount of Ce (Bi3CeTi3O12) has the pure pyrochlore phase it seems that the presence of Ce stabilizes the formation of this phase. This different influence of cerium and lanthanum could be explained by the incorporation of their ions on the different sites in the titanate structure. Bismuth titanate based ceramics, sintered at 1050?C/2h, had densities above 93% of theoretical density and characteristic plate-like grain morphology. Small quantity of cubic pyrochlore phase was detected only in the Ce modified bismuth titanate ceramics. On the other hand, lanthanum addition caused formation of smaller grain size with pronounced plate-like morphology. .
The effect of nanometric zirconia particle additives on microstructure and mechanical properties of dense alumina
Authors: Zych Lukasz , Lach Radoslaw , Haberko Krzysztof , Rutkowski Pawel , Trybalska Barbara , Piekarczyk Jan
Published: January 2013

Zirconia additives have favourable influence on mechanical properties of dense alumina polycrystals. It results from the martensitic transformation of tetragonal zirconia particles into monoclinic symmetry at the crack tip propagating through a material. Usually applied zirconia particles were of sub-micrometer or micrometer sizes. In the present work nanometric zirconia particles prepared by hydrothermal crystallization technique were introduced into the alumina matrix. Both, zirconia and alumina powders were homogenized in an aqueous suspension of pH selected on the basis of the zeta (?) potential measurements. It was found that this factor influences greatly strength of the resulting powder agglomerates and hence mechanical properties of the sintered material. .
Investigation of electrical properties of vacuum annealed titanium oxide containing ceramics
Authors: Pavlova Agnese , Barloti Janis , Teters Valdis , Locs Janis , Berzina-Cimdina Liga
Published: January 2013

Titanium oxide ceramics were prepared using extrusion process and subsequent thermal treatment in two stages - in air atmosphere at 1150?C and than in vacuum at temperatures between 1200 and 1350?C. Influence of thermal treatment conditions on microstructure and electrical properties (thermopower, conductivity of semiconductor and electron activation energy) of obtained ceramics was investigated. It was confirmed that all samples treated in vacuum are n-type semiconductors. It was also found that the increase of temperature during sintering in vacuum leads to increased electrical conductivity, however, the highest thermopower values were obtained for samples thermally treated in vacuum at 1225?C. Electron activation energy (?E), calculated using dependence of conductivity of samples on temperature, was is in the range from 0.049 to 0.061 eV. The obtained products can be used as electrodes for water treatment technology based on photoelectrolysis. .
Preparation and properties of low cement castable sintered at different temperatures
Authors: Martinovic Sanja , Majstrovic Jelena , Vidojkovic Velislav , Volkov-Husovic Tatjana
Published: January 2013

The low cement high alumina castable (LCC) studied in this paper was synthesised, cured and then treated at different sintering temperatures. Since any inhomogeneity introduced during the castable preparation can remain inside the material degrading its properties and therefore the quality during service life, particular attention was given to the processing procedure in order to produce the material with the optimum characteristics. Composition of the castable regarding particle size distribution was adjusted according to the Andreassen's packing model. The samples were sintered at 1100, 1300 and 1600?C for three hours. Influence of the different sintering temperatures on the castable properties is discussed. Compressive and flexural strengths were determined by destructive testing method, while the water immersion method was used for determination of the bulk density and the water absorption. Changes of elastic properties and microstructure (porosity) were observed by the non-destructive testing methods, ultrasonic measurements and image analysis. Based on the results, it can be concluded that sintering temperature has strong influence on the properties of the LCC. Exceptionally good properties were obtained for the sample sintered at 1600?C, but it should be highlighted that the samples treated at 1100 and 1300?C were provided with good properties, too. This should not be neglected because of the energy saving importance, in cases where the material sintered at lower temperature satisfies the application requirements. .
Composite material in the Al2O3-20 vol% YAG system
Authors: Lach Radosław , Haberko Krzysztof , Trybalska Barbara
Published: January 2013

Within alumina particle suspension yttria precursor was precipitated with ammonium carbonate. Drying and calcination at 600?C resulted in the mixture of alumina and yttria particles, the latter being much finer than alumina particles. This mixture was additionally homogenized by short attrition milling in aqueous suspension of pH selected on the basis of zeta (?) potential measurements. It was found that acidic conditions (realized with HNO3) resulted in hard agglomerates. Such powder shows poor sintering ability. Much better properties showed powders homogenized under basic conditions. They give dense materials composed of YAG inclusions within alumina matrix. YAG particles resulted from the reaction of Y2o3 with Al2o3 during heat treatment. Homogenization of the system mixed at pH=8, corresponding to the heterofloculation conditions, is slightly better than observed at pH=10. YAG inclusions (20 vol%) increase hardness and fracture toughness of the material in comparison with pure alumina polycrystals. .
Electrical characteristics of bismuth titanate glass-ceramics containing SiO2 and Nd2O3
Authors: Slavov Stanislav , Krapchanska Milena , Kashchieva Elena , Dimitriev Yanko
Published: January 2013

Bismuth-titanate ceramics containing SiO2 and Nd2O3 as additives are synthesized at two different ways of cooling of the melts. The introduction of SiO2 and Nd2O3 leads to more complex crystallization with participation of several phases including Bi4Ti3O12. It is proved that the applied methods of synthesis are suitable for generation of different microstructures in the bulk doped bismuth titanate ceramics, which is promising basis for modification of their electrical properties. The increasing of SiO2 content improves the glass formation ability and addition of Nd2O3 stimulates the crystallization. The conductivity of selected samples is determined by impedance analyzer in the frequency range from 10 to 100 kHz and DC resistible bridge using two-terminal method. All investigated samples are dielectrics with conductivity 10-6-10-9 (??cm)-1.
Direct synthesis of nanocrystalline oxide powders by wet-chemical techniques
Authors: Srdic Vladimir , Djenadic Ruzica , Milanovic Marija , Pavlovic Nikolina , Stijepovic Ivan , Nikolic Ljubica , Moshopoulous Evagelia , Giannakopoulos Konstantinos , Dusza Jan , Maca Karel
Published: January 2013

In a recent period there is a great need for increasing the knowledge of tailoring the innovative procedures for the synthesis of electroceramic nanopowders and materials with improved quality for specific application. In order to produce electroceramics with desirable microstructure and properties, synthesis of stoichiometric, ultra-fine and agglomerate free powders with narrow size distributions is one of the most important steps. Within this scope, in the present paper we summarize our recent results on direct synthesis of some important perovskites and ferrites nanopowders by wet-chemical techniques.
Nanopowder metrology and nanoparticle size measurement: Towards the development and testing of protocols
Authors: Aimable Anne , Bowen Paul
Published: January 2013

There are many methods and instruments available for powder characterization and they are more or less well suited to powders in different size ranges. This report presents in more detail the relatively recent Centrifugal Particle Sizer (CPS) and its potential for particle size distribution measurement compared to more classical techniques (microscopy, laser diffraction, or photo correlation spectroscopy). To get reliable comparable data is of primary importance for new application developments. A series of protocols for nanosized powders - nanopowder metrology - was produced within the framework of a COST Action - COST 539 'Electroceramics from Nanopowders Produced by Non-conventional Methods'. The protocols have been tested using well-characterized commercial products, and for a series of powders produced in the COST Action 539. The results show that results between methods and or laboratories are often very good but some show significant deviations illustrating the need for a systematic approach and how the protocols can help us develop a Nanometrology for new functional powders.
Properties of BaTiO3 confined in nanoporous Vycor and artificial opal silica
Authors: Nuzhnyy Dmitry , Vaněk Přemysl , Petzelt Jan , Bovtun Viktor , Kempa Martin , Gregora Ivan , Savinov Maxim , Krupková Radmila , Studnicka Václav , Bursík Josef , Samoylovich Mihail , Schranz Wilfried
Published: January 2013

Using the sol-gel technique, BaTiO3 was embedded into nanoporous Vycor and artificial vitreous opal silica for the first time. About 50 vol% of the pores was filled. In case of the Vycor glass (pore diameter 4-6 nm) only amorphous phase was revealed by XRD, IR reflectivity and Raman spectra. After additional gradual annealing, no crystallization was achieved. Chemical reaction with the SiO2 skeleton started at ~1000 K. The room-temperature IR and Raman spectra clearly show characteristic vibrational modes of the ferroelectrically distorted TiO6 octahedra without any long-range order. In case of the opal matrix (densely packed silica spheres, pore diameter up to ~50 nm), crystallization of the ferroelectric BaTiO3 appeared in coexistence with the amorphous phase, but the penetration depth of the crystalline BaTiO3 was limited. From the apparent temperature independence of the effective wide-frequency dielectric response due to the essentially temperature independent effective soft mode stiffened to ~100 cm-1, we can deduce that no macroscopic percolation of the crystalline BaTiO3 has appeared in our opal matrix. Nevertheless, Raman spectra bring evidence of a diffuse ferroelectric phase transition in the opal-BaTiO3 composite.
Piezoresponse force microscopy behaviour of Bi4Ti3O12 ceramics with various excess bismuth
Authors: Aguiar Ederson , Simões Alexandre , Moura Francisco , Cilense Mario , Longo Elson , Varela Jose
Published: January 2013

Bismuth titanate (Bi4Ti3O12 - BIT) ceramics derived from different amounts of excess Bi2O3 were prepared using the polymeric precursor method. In spite of excess bismuth, single phase ceramics were obtained with a con?trolled microstructure. Raman analysis evidenced typical vibrational bands of the BIT phase. UV-vis spectra indicated that excess Bi2O3 causes a reduction in defects in the BIT lattice due to the suppression of oxygen vacancies located at the octahedral BO6-ion. The microstructure and electrical properties are strongly depen?dent on the excess Bi2O3. Appropriate initial Bi2O3 excess reduces the leakage current and loss tangent and thereby improves the polarization of BIT ceramics. Rietveld analyses confirmed that the powders crystallize in an orthorhombic structure with a space group of Fmmm at room temperature. The polarization reversal was investigated by applying ac voltage through a conductive tip during the area scanning and was investigated by piezoresponse force microscopy (PFM).
Thermal decomposition, phase evolution, sintering and characterization of lithium titanate synthesized by sol-gel process
Authors: Kumar Sanjay , Ramnathan Srinivasan , Krishnamurthy Nagaiyar
Published: January 2013

Lithium titanate powder was prepared by evaporation of an aqueous suspension obtained in reaction between lithium nitrate (LiNO3) and titanium hydroxide, formed by the hydrolysis of titanium tetrabutoxide Ti(C4H9O)4. Thermal decomposition and phase evolution behaviour of the dried powder were studied using TG-DTA and XRD, while powder characteristics (crystallite size, agglomerate size and morphology) were studied using X-ray diffraction, laser light scattering and SEM techniques. The synthesized powder exhibited loss in weight accompanied by corresponding heat effects in stages up to 550?C, transformed into an amorphous lithium titanate (Li2TiO3) compound and finally underwent crystallization at temperatures ranging from 550 to 650?C (accompanied by an exotherm at the DTA pattern). The powder formed at 650?C was found to be nanocrystalline (crystallite size ~10 nm), while the crystallites grew to 50 nm with increasing temperature to 1000?C. Both SEM and particle size data confirmed that the calcined powder consists of agglomerates with the mean size of ~3 ?m. Study of the powder sintering behaviour showed that densification and grain growth were very intensive during heat treatment up to 1050?C. Sintering at 1200?C led to loss of lithium and formation of Li0.14TiO2 phase. Thus, fine grained Li2TiO3 bodies with density higher than 85% TD, required for tritium breeding in ITER (International thermonuclear experimental reactor) application, can be formed by sintering of the prepared powder at temperature of 1050?C.
Antimicrobial properties of ZnO nanoparticles incorporated in polyurethane varnish
Authors: Zvekic Dusan , Srdic Vladimir , Karaman Maja , Matavulj Milan
Published: January 2013

The antimicrobial effect of the ZnO nanoparticles dispersed in polyurethane varnishes was investigated. Antimicrobial activity was evaluated against three bacteria (Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa) and one strain fungi (Sacharomyces cerevisiae) by the 'pour-plate' test. It was shown that the ZnO nanoparticles efficiently inhibit growth of the colonies of Staphylococcus aureus, Pseudomonas aeruginosa and Saccharomyces cerevisiae, but their activity against Escherichia coli was found to be questionable suggesting more detailed research.
Fabrication of ZrC/SiC, ZrO2/SiC and ZrO2 powders by carbothermal reduction of ZrSiO4
Authors: Kljajevic Ljiljana , Matovic Branko , Nenadovic Snezana , Bascarevic Zvezdana , Cveticanin Nikola , Devecerski Aleksandar
Published: January 2013

The zirconia/silicon carbide (ZrO2 /SiC) and ZrO2 powders are prepared by carbothermal reduction of natural mineral zircon (ZrSiO4). The zircon powder was mixed with activated carbon as a reducing agent and heattreated in a controlled flow atmosphere of Ar. Phase evolution and phase content were followed as a function of temperature (1573-1973 K) and C/ZrSiO4 ratio (C/ZrSiO4 = 1, 4, 5 and 7), by means of ex-situ X-ray diffraction and SEM/EDS analysis. By varying the temperature and C/ZrSiO4 ratio, different powder compositions were obtained (m-ZrO2; m-ZrO2/c-ZrO2; c-ZrO2; c-ZrO2/SiC). .
Effect of oxidizing and reducing atmospheres on Ba(Ti0.90 Zr0.10)o3:2V ceramics as characterized by piezoresponse force microscopy
Authors: Moura Francisco , Simões Alexandre , Riccardi Carla , Zaghete Maria , Varela Jose , Longo Elson
Published: January 2013

The effect of annealing atmospheres (Atamb, N2 and O2) on the electrical properties of Ba(Ti0.90Zr0.10 )O3:2V (BZT10:2V) ceramics obtained by the mixed oxide method was investigated. X-ray photoelectron spectroscopy (XPS) analysis indicates that oxygen vacancies present near Zr and Ti ions reduce ferroelectric properties, especially in samples treated in an ambient atmosphere (Atamb ). BZT10:2V ceramics sintered in a nitrogen atmosphere showed better dielectric behaviour at room temperature with a dielectric permittivity measured at a frequency of 10 kHz equal to 16800 with dielectric loss of 0.023. Piezoelectric force microscopy (PFM) images reveal improvement in the piezoelectric coefficient by sintering the sample under nitrogen atmosphere. Thus, BZT10:2V ceramics sintered under a nitrogen atmosphere can be useful for practical applications which include nonvolatile digital memories, spintronics and data-storage media.
Synthesis and characterization of EuB6 by borothermic reduction of Eu2O3
Authors: Kumar Sanjay , Krishnamurthy Nagaiyar
Published: January 2013

Carbon free high pure europium hexaboride is an urgent need for the fast breeder nuclear reactor program. The properties of EuB6 are highly influenced by the presence of one or more substitutional impurities, particularly, carbon, oxygen and nitrogen. In the present investigation carbon and nitrogen free high pure europium hexaboride was synthesized by borothermic reduction of europium oxide Eu2O3 (using boron as a reducing agent) at relatively low temperature (< 900?C). Glassy B2O3, the by-product of the synthesis process, was leached out completely in slightly acidic warm water from which boron could be recovered by usual electrolysis process. The product obtained was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and chemical analysis. Oxidation behaviour of pressureless sintered EuB6 pellets (> 90 % of theoretical density) was studied at 850?C and revealed that an adherent thin surface of Eu2O3 was formed which prevent the further oxidation.
Collagen/silicocarnotite composites, cross-linked with chondroitin sulphate: In vitro bioactivity
Authors: Radev Lachezar , Hristov Vladimir , Michailova Irena , Fernandes Maria , Salvado Isabel
Published: January 2013

In this work we present the experimental results on synthesis, structure evolution and in vitro bioactivity of collagen- silicocarnotite-chondroitin sulphate composites. The obtained samples were synthesised by mixing collagen (C) and silicocarnotite (S) powder with C:S ratio of 75:25 and 25:75 wt.% in the presence of chondroitin sulphate (ChS). Collagen was diluted in 5M CH3COOH before mixing. The obtained materials were characterized by X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) before and after in vitro test in 1.5 simulated body fluid. XRD of synthesized samples showed that before immersion carbonate containing hydroxyapatite (CO3HA) were formed in situ in the composites. FTIR depicts the presence of HPO4 2- and the 'red shift' of COO- and SO3 - from ChS was also observed. This 'red shift' could be attributed that the ChS prefers to chelate Ca2+ from partially dissolved S powder. SEM of the prepared samples show the presence of nanosized hydroxyapatite (HA) whiskers and flower-like HA assemblies. After in vitro test, XRD proved the presence of HA with well-defined crystallinity. According to the FTIR results B-type CO3HA can be observed. SEM of the precipitated layers show the presence of HA spheres. Inductively coupled plasma atomic emission spectroscopy results lead to a conclusion that after in vitro test of the prepared composites silicon containing carbonate substituted hydroxyapatite (Si-CO3HA) may be formed on the surface of the immersed samples.
Synthesis of V-Ti-Cr alloys by aluminothermy co-reduction of its oxides
Authors: Kumar Sanjay , Krishnamurthy Nagaiyar
Published: January 2013

Synthesis of V-Ti-Cr solid solution alloy by co-reduction of V2O5, Cr2O3 and TiO2 with aluminium in an open bomb reactor was investigated. The reduction of V2O5 and Cr2O3 was highly exothermic while reduction of TiO2 was not sufficiently exothermic for self-sustaining reaction. A range of composition of V2O5, Cr2O3 and TiO2 mixture was chosen to make overall process sufficiently exothermic to sustain the reaction in a controlled manner. After the co-reduction, V-Ti-Cr-Al solid solution was obtained. As-obtained solid solution was refined by electron beam melting (EB) to remove the aluminium and residual oxygen. EB melted V-Ti-Cr thus obtained contains substantially less amount of aluminium (~0.081%.) Throughout the synthesis process the prepared products were analyzed using scanning electron microscope (SEM), energy dispersive X-ray fluorescence (EDAX), chemical analysis, gravimetric analysis and X-ray diffraction.
Synthesis of nano-sized β-tricalcium phosphate via wet precipitation
Authors: Mirhadi Bahman , Mehdikhani Behzad , Askari Nayereh
Published: January 2013

Nano-size ?-tricalcium phosphate powders with average grain size of 50 nm were prepared by the wet chemical precipitation method with calcium nitrate and diammonium hydrogen phosphate as calcium and phosphorus precursors, respectively. The pH of the system was maintained at 8 and 10.8 by adding of sodium hydroxide. Filtered cake was dried at 80?C and calcined at 700?C. The dried and calcined powders were characterized using X-ray diffractrometry (XRD), Fourier transform infrared spectroscopy (FTIR), inductively coupled plasma atomic emission spectroscopy (ICPAES) and scanning electron microscopy (SEM).
Kinetic analysis of the thermal decomposition of Li4Ti5O12 pellets
Authors: Mosqueda Hugo , Pfeiffer Heriberto
Published: January 2013

A single dynamic kinetic analysis, describing the surface decomposition of Li4Ti5O12 pellets, has been performed. Samples were analyzed by X-ray diffraction and scanning electron microscopy. The analyses were performed between 1000 and 1100?C and different times, perceiving the Li4Ti5O12 decomposition to Li2Ti3O7 , with a loss of lithium. As expected, more rapid decomposition behaviour was found at higher temperatures. Finally, the activation energy for this decomposition of Li4Ti5O12 to Li2Ti3O7 was estimated to be equal to 383 kJ/mol.
Crystallization behaviour of Li2O·Nb2O5·SiO2 glass containing TiO2
Authors: Matijasevic Srdjan , Zivanovic Vladimir , Tosic Mihajlo , Grujic Snezana , Stojanovic Jovica , Nikolic Jelena , Zdrale Sonja
Published: January 2013

This paper deals with the crystallization of glass 30Li2O?15Nb2O5?50SiO2?5TiO2 (mol%). The crystallization behavior was studied under isothermal and non-isothermal conditions. XRD and SEM methods were employed for determination of phase composition and microstructure of crystallized glass. It was detected that this glass crystallizes by the surface crystallization mechanism. SEM micrographs of the crystallized samples revealed that the crystals grow in the form of dendrites. The glass-ceramics with complex phase composition was obtained. Three crystalline phases were detected where LiNbO3 has grown as primary phase and a secondary ones Li2Si2O5 and SiO2 appeared. The calculated average crystallite sizes are: 27 nm for LiNbO3 , 115 nm for Li2Si2O5 and 45 nm for SiO2 . From the experimental data an activation energy of crystals growth, calculated using the Kissinger relation, is Ea = 275 ?10 KJ / mol.
A Framework for Research on Corporate Accountability Reporting
Authors: Ramanna Karthik
Published: January 2013

SYNOPSIS

This paper provides an accounting-based conceptual framing of the phenomenon of corporate accountability reporting. Such reporting is seen as arising from a delegator's (e.g., a citizenry) demand to hold a delegate (e.g., shareholders) to account. When effective, corporate accountability reporting can internalize certain externalities into firms' resource allocation decisions, although doing so will not always serve shareholders' interests. I leverage the positive accounting literature's current understanding of properties of financial reports to develop three hypotheses on corporate accountability reporting. I argue that an accountability reporting system is likely to be more useful to a delegator if it: (1) mitigates information advantages across delegates and delegators, (2) reports both stocks and flows in the measures of account, and (3) has a mutually agreeable due process to match across periods the actions of delegates and the outcomes of those actions. I show how the successive incidence of these properties in observed corporate accountability reports can be used to determine whether and how those reports create or destroy value for shareholders and other constituencies.
Effects of inspired oxygen concentration on ventilation, ventilatory rhythm, and gas exchange in isoflurane-anesthetized horses
Authors: Crumley Mariana N. , McMurphy Rose M. , Hodgson David S. , Kreider Scott E.
Published: January 2013

Objective—To compare the effects of 2 fractions of inspired oxygen, 50% and > 95%, on ventilation, ventilatory rhythm, and gas exchange in isoflurane-anesthetized horses.

Animals—8 healthy adult horses.

Procedures—In a crossover study design, horses were assigned to undergo each of 2 anesthetic sessions in random order, with 1 week separating the sessions. In each session, horses were sedated with xylazine hydrochloride (1.0 mg/kg, IV) and anesthesia was induced via IV administration of diazepam (0.05 mg/kg) and ketamine (2.2 mg/kg) Anesthesia was subsequently maintained with isoflurane in 50% or > 95% oxygen for 90 minutes. Measurements obtained during anesthesia included inspiratory and expiratory peak flow and duration, tidal volume, respiratory frequency, end-tidal CO2 concentration, mixed expired partial pressures of CO2 and O2, Pao2, Paco2, blood pH, arterial O2 saturation, heart rate, and arterial blood pressure. Calculated values included the alveolar partial pressure of oxygen, alveolar-to-arterial oxygen tension gradient (Pao2 − Pco2), rate of change of Pao2 − Pao2, and physiologic dead space ratio. Ventilatory rhythm, based on respiratory rate and duration of apnea, was continuously observed and recorded.

Results—Use of the lower inspired oxygen fraction of 50% resulted in a lower arterial oxygen saturation and Pao2 than did use of the higher fraction. No significant difference in Paco2, rate of change of Pao2 − Pao2, ventilatory rhythm, or other measured variables was observed between the 2 sessions.

Conclusion and Clinical Relevance—Use of 50% inspired oxygen did not improve the ventilatory rhythm or gas exchange and increased the risk of hypoxemia in spontaneously breathing horses during isoflurane anesthesia. Use of both inspired oxygen fractions requires adequate monitoring and the capacity for mechanical ventilation.