Structural analyses of sintered MT and BZT ceramics

Development of dielectric materials is increasing with a rapid progress in mobile and satellite communications systems, where magnesium titanates find their place owing to good dielectric properties. Recently it has been established that, these materials, which are based on binary magnesium titanates (MgTi03 and Mg2Ti04) can be applied in MW engineering. These materials differ extremely low dielectric loss in the microwave range and high dielectric constant. On the other hand, barium-titanate compounds have attracted great attention for their specific microwave properties, as well. They were commonly used as parts of resonators, filters and multilayer ceramic capacitors, in the microwave region. The crystal phase with the structure BaZn2Ti40 11 is present in various commercial microwave dielectric materials based on barium-titanate compounds. Taking all this into account, in this article, the influence of mechanical activation of the MgO-Ti02 and BaCOr ZnO-Ti02 systems on phase composition, crystal structure and microstructure before and after sintering process, has been reported

Assessment of the quality of newly-formed bone for implant insertion after augmentation of the maxillary sinus floor

Background: Presence of the maxillary sinus and low bone density in this area often could create a problem for prosthetic rehabilitation with dental implants. Sinus floor augmentation technique can successfully increase dimensions of the posterior maxilla for implant placement. Objective: To assess quality of newly formed bone for implant insertion after augmentation of the floor of the maxillary sinus using Digora for Windows computer programme. Materials and Methods: 30 patients with indications for sinus lift procedure were involved in this clinical study. Bone density was analyzed by Digora for Windows computer programme. Results: 16 patients completed this clinical study with preoperative and postoperative orthopantomographs. Conclusion: Cases with sufficient density and bone volume in the posterior maxilla require sinus lift technique with adequate bone graft for implant insertion. This is confirmed by pre- and post-operative analysis of radiographic images in Digora for Windows programme

Izolacija i karakterizacija autohtonih sojeva bakterija mlečne kiseline izdvojenih iz sjeničkog sira

Lactic acid bacteria strains isolated from autochtonous cheeses of Sjenica were researched. In those products, where starters were not added fermentation occurs as a result of natural flora present in the surrounding environment. Forty thermophilic, mesophilic and citrat+ LAB strains were isolated by selective mediums (MRS agar, LM17 agar and LDC agar) from 5 samples of Sjenica-cheese. These strains were exposed to the further analysis and indetification. After examination by Gram test and catalase test, 23 strains of LAB, were selected for further analysis. On the basis of lactose fermentation manner and acid production in 1% reconstituted skim milk, only 6 strains were selected. Determination of theese strains by API 50 CHL and Rapid ID 32 Strep tests, showed that 2 strains belong to the Lactococcus lactis ssp. lactis, 1 strain to the Lactococcus lactis ssp. cremoris, 1 strain to the Lactococcus lactis ssp. lactis bivar. diacetylactis and 2 strains to the Lactobacillus para. paracasei.U radu su izolovani i karakterisani sojevi bakterija mlečne kiseline izdvojeni iz sjeničkog sira, proizvedenog autohtonom tehnologijom, bez dodavanja starter kultura. Iz pet uzoraka sjeničkog sira izvršena je izolacija 40 termofilnih, mezofilnih i citrat+ sojeva BMK na odgovarajućim selektivnim podlogama (MRS agar, LM17 agar i LDC agar). Ovi sojevi su dalje podvrgnuti ispitivanju na Gram reakciju i katalaza test, posle čega je izabrano 23 soja za dalja ispitivanja. Na osnovu načina fermentacije laktoze i acidogene sposonosti praćene u 1% rekonstituisanom obranom mleku selekcionisano je samo šest sojeva. Determinacijom ovih sojeva pomoću API CHL 50 i Rapid ID 32 Strep testa, pokazalo se da dva soja pripadaju Lactococcus lactis ssp. lactis, jedan soj Lactococcus lactis ssp. cremoris jedan soj Lactococcus lactis ssp. lactis bivar. diacetylactis i dva soja Lactobacillus para. paracasei vrsti

Geopolitical positioning of the Russian federation after the intervention in Syria

Историја 20. века обележена је са два велика, светска рата, као и са великим бројем мањих, регионалних сукоба, који су били део борбе за глобалну превласт и доминацију у погледу друштвених релација, организације друштва, тржишта, политичког и социјалног усмерења мањих народа и држава. Такође, током добро познатог Хладног рата „мали“ народи су по неписаном правилу били принуђени да се опредељују за приклањање једном од два супротстављена блока. Окончањем Хладног рата и сломом совјетског модела доминације погрешно се претпостављало у другом, победичком блоку, да је победа коначна те да је дошло време апсолутне превласти интереса и мишљења преостале глобалне суперсиле, Сједињених Америчких Држава (САД). Ипак, време апсолутне доминације трајаће, историјски посматрано, јако кратко, тек нешто више од 20 година, када се поново полако почиње успостављати одређена равнотежа глобалне моћи јачањем пре свих Кине, Европске Уније, Индије, као и Руске Федерације, формално-правне наследнице СССР-а па и делимично совјетског модела друштвеног и политичког уређења. Временски период своје апсолутне доминације САД су искористиле за глобално приближавање границама интересног утицаја како Кине, тако и Руске Федерације, задирући у територије вишегодишњег глобалног позиционирања наведених држава, као глобалних и регионалних сила. Јачање политичких па и војних притисака на пробуђену Русију у другој декади 21. века доводи до повећања субјективног осећаја сопствене угрожености, која ипак није била толико изражена у војном колико у економском погледу, будући да су активности западних сила тежишно биле усмерене ка ограничавању руског снабдевања Европе природним гасом. Узимајући у обзир значај и удео енергетике у укупном привредном билансу Руске Федеције, војна интервенција ове државе у Сирији била је од виталног значаја за њен даљи економски развој. Руска Федерација је овим искораком, још једном, од окончања Хладног рата успела да заустави експанзионистичку политичку и војна настојања Вашингтона, пре свега за успоставом доминације и изласком на интересне па чак и на државне границе Руске Федерације.The history of the 20th century is marked by two great, world wars, as well as a large number of smaller, regional conflicts, which were part of the struggle for global supremacy and domination in terms of social relations, organization of society, markets, political and social orientation of smaller nations and country. Also, during the well-known Cold War, „small“ nations were, by an unwritten rule, forced to opt for one of the two opposing blocs. With the end of the Cold War and the collapse of the Soviet model of domination, it was wrongly assumed in the second, victorious bloc, that victory was final and that the time had come for the absolute dominance of interests and opinions of the remaining global superpower, the United States (USA). However, the time of absolute domination will last, historically speaking, very short, just over 20 years, when a certain balance of global power is slowly being re-established by strengthening China, the European Union, India, as well as the Russian Federation, the formal legal successor of the USSR, and even a partially Soviet model of social and political organization. The United States used the time period of its absolute domination to globally approach the borders of interesting influence of both China and the Russian Federation, encroaching on the territories of many years of global positioning of these countries, as global and regional powers. The intensification of political and even military pressures on awakened Russia in the second decade of the 21st century leads to an increase in the subjective feeling of self-threat, which was not so much expressed in military as in economic terms, since the activities of Western powers were focused on limiting Russia's supply to Europe. natural gas. Taking into account the importance and share of energy in the overall economic balance of the Russian Federation, the military intervention of this country in Syria was of vital importance for its further economic development. With this step forward, once again since the end of the Cold War, the Russian Federation has managed to stop the expansionist political and military efforts of Washington, above all, to establish dominance and reach the interesting and even state borders of the Russian Federation

New characterization based symmetry tests

Two new symmetry tests, of integral and Kolmogorov type, based on the characterization by squares of linear statistics are proposed. The test statistics are related to the family of degenerate U-statistics. Their asymptotic properties are explored. The maximal eigenvalue, needed for the derivation of their logarithmic tail behavior, was calculated or approximated using techniques from the theory of linear operators and the perturbation theory. The quality of the tests is assessed using the approximate Bahadur efficiency as well as the simulated powers. The tests are shown to be comparable with some recent and classical tests of symmetry

Management of tomato bacterial spot in the field by foliar applications of bacteriophages and SAR inducers

Various combinations of the harpin protein, acibenzolar-S-methyl, and bacteriophages were compared for controlling tomato bacterial spot in field experiments. Harpin protein and acibenzolar-S-methyl were applied every 14 days beginning twice before transplanting and then an additional four applications throughout the season. Formulated bacteriophages were applied prior to inoculation followed by twice a week at dusk. A standard bactericide treatment, consisting of copper hydroxide plus mancozeb, was applied once prior to inoculation and then every 7 days, while untreated plants served as an untreated control. Experiments were conducted in north and central Florida fields during fall 2001, spring 2002, and fall 2002. In three consecutive seasons, acibenzolar-S-methyl applied in combination with bacteriophage or bacteriophage and harpin significantly reduced bacterial spot compared with the other treatments. However, it did not significantly affect the total yield compared with the standard or untreated control. Application of host-specific bacteriophages was effective against the bacterial spot pathogen in all three experiments, providing better disease control than copper-mancozeb or untreated control. When results of the disease severity assessments or harvested yield from the bacteriophage-treated plots were grouped and compared with the results of the corresponding nonbacteriophage group, the former provided significantly better disease control and yield of total marketable fruit

Influence of mechanical activation on MgO-TiO2 system

Poster presented at the 10th Conference of the Materials Research Society of Serbia - YUCOMAT 2008, Herceg Novi, Montenegro, September 8-12, 200

Structural features of near equiatomic FeCo-2V semi-hard magnetic alloy prepared by MIM technology

The structural properties of a magnetically semi-hard near equiatomic FeCo-2wt%V (FeCoV) alloy produced by Powder Injection Moulding (PIM) (option by fine metal powder - Metal Injection Moulding (MIM) technology) were investigated in this paper. Starting granulate was prepared by mixing FeCoV powder with a low-viscosity binder. After injection, the green samples were first treated with a solvent and then thermally with the same aim of removing the binder. MIM technology was completed by high-temperature sintering for 3.5 hours at temperatures from 1370 OC to 1460 OC in a hydrogen atmosphere, which provides the necessary magnetic and mechanical characteristics. The influence of sintering temperature was investigated concerning the aspects of the processes of structural transformation by the methods of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The appearance of an intense diffraction peak of the α'-FeCo phase (crystal structure type B2) was registered for all investigated samples. Structural parameters particle size Dmax, Feret X, and Feret Y exhibit constant increase with increase of sintering temperature

Structural characterization of mechanically activated MgO-TiO2 system

In this article the influence of ball miling process on structure of MgO-TiO2 system was investigated. The mixtures of MgO-TiO2 powders were mechanically activated in a planetary ball mill for the time period from 0 to 120 minutes. The influence of mechanical activation on the lattice vibrational spectra was studied by Raman spectroscopy at room temperature. Structural investigations have been performed on produced powders. Nitrogen adsorption method was used to determine the BET specific surface area and pore size distribution. Unusual results have been obtained: specific surface area continuously decreased up to 40 minutes of activation and increased after that, reaching its minimun value of 5.5 m2/g. The Raman spectra of activated powders have shown that anatase modes have been decreasing in intensity and broadening as the time of activation extended. Also, the additional modes attributed to TiO2 II, srilankite and rutile phases started to appear as a consequence of activation

The Influence of Mechanical Activation on Sintering Process of BaCO3-SrCO3-TiO2 System

In this article the influence of mechanical activation on sintering process of barium-strontiumtitanate ceramics has been investigated. Both non-activated and mixtures treated in planetary ball mill for 5, 10, 20, 40, 80 and 120 minutes were sintered at 1100-1400 °C for 2 hours in air atmosphere. The influence of mechanical activation on phase composition and crystal structure has been analyzed by XRD, while the effect of activation and sintering process on microstructure was investigated by scanning electron microscopy. It has been established that temperature of 1100 °C was to low to induce final sintering stage for the system. Electrical measurements have been conducted for the densest ceramics sintered at 1400 °C for 2 hours