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

The impedance analysis of sintered MgTiO3 ceramics

In the present study the effect of preparation conditions on microstructure and electrical properties of MgTiO3 ceramics was investigated. Mixture of MgO and TiO2 powders was subjected to mechanical activation for different time periods. Two types of sintering (two-step and HIP sintering) were performed on green bodies prepared by cold isostatic pressing. AC impedance spectroscopy in the low-frequency range (from 20 Hz to 1 MHz), at room and elevated temperatures, were performed in order to separate contribution of grains and grain boundaries to capacitance, resistance and conductivity of magnesium titanate ceramics. The special attention was directed to explanation of the influence of mechanical activation on electrical and morphological changes in sintered samples. The significant decrease of partial oxygen pressure in HP sintering atmosphere caused the change from insulating behavior of MgTiO3 samples after two-step sintering to semiconducting one

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

In vitro shoot regeneration from seedling explants in Brassica vegetables: Red cabbage, broccoli, Savoy cabbage and cauliflower

Brassica oleracea varieties (red cabbage, broccoli, Savoy cabbage and cauliflower) were tested for their ability to regenerate shoots in vitro. Cotyledon, hypocotyl and root explants of 7 day-old seedlings were incubated on Murashige and Skoog's (MS) medium supplemented with 1 mg l-1 6-benzyladenine (BA) or 6-furfurylaminopurine (KIN) in combination with 0, 0.1, and 0.2 mg l-1 indole-3-butyric acid (IBA). Hypocotyls showed the best explants in almost all varieties tested with a minimum regeneration potential of 75% and producing 3.5-7.4 shoots per explant. The BA-supplemented media were optimal for both shoot regeneration and multiplication. Shoots rooted maximally (100%) on plant growth regulator-free MS medium containing 2% or 4% sucrose. Increased sucrose content improved plant acclimation in the greenhouse.Ispitivana je sposobnost četiri varijeteta Brassica oleracea (crveni kupus, brokoli, kelj i karfiol) da regenerišu pupoljke in vitro. Eksplantati kotiledona, hipokotila i korenova, uzetih sa 7 dana starih klijanaca, su gajeni na Murashige i Skoog (MS) hranljivoj podlozi sa dodatkom 1 mg l-1 6-benziladenina (BA) ili 6- furfurilaminopurina (KIN) u kombinaciji sa 0, 0.1, i 0.2 mg l-1 indol-3-butirične kiseline (IBA). Eksplantati hipokotila su se pokazali kao najbolji za regeneraciju kod skoro svih testiranih varijeteta sa minimalnim regenerativnim potencijalom od 75% i sa produkcijom 3.5- 7.4 pupoljaka po eksplantatu. Podloge koje su sadržale BA su bile optimalne, kako za regeneraiju pupoljaka, tako i za njihovu kasniju multiplikaciju. Maksimalan procenat oživljavanja izdanaka (100%) je postignut na MS medijumu bez dodatih regulatora rastenja, a koji je sadržao 2% ili 4% saharozu. Povećan sadržaj saharoze u medijumu za ožiljavanje uticao je na poboljšanu aklimatizaciju biljaka u stakleniku.Projekat ministarstva br. 143026 i TR-20072

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

Shoot and root dry weight in drought exposed tomato populations

This research was conducted with the aim to among forty-one tested tomato (Lycopersicon esculentum Mill) populations distinguish those tolerant to limited water supply. Tolerance assessments were performed by using sixteen drought stress selection indices calculated on the basis of tomato shoot and root dry weight yields determined at water stress and non-stress conditions. Populations were differentiated in groups using the method of cluster analysis. The pot experiment was set in controlled greenhouse conditions and comprised optimally irrigated control and drought treatment (35.0 and 20.9% volumetric soil water content, respectively), imposed at the phase of intensive vegetative growth. The experiment was conducted at the Institute for Vegetable Crops in Smederevska Palanka, Serbia. The analyzed tomatoes exhibited significant differences in terms of response to limited irrigation, which had more pronounced effect on shoot dry weight than on the roots (average decrease of 64.4 and 35.7%, respectively). Consequently, root fraction in the total dry weight increased at drought for 68.2% on average. Shoot and root dry weights were positively correlated at optimal irrigation but not in drought, implying genotypic differences in terms of root adjustments to stress conditions. As for the calculated selection indices, substantial variation was found among the populations enabling their ranking in terms of drought tolerance. Since ranking was not the same in all cases, clustering the populations was performed taking into account all sixteen selection indices. The results of this analysis indicate that populations designated with numbers 126, 124, 131, 125, 128, 105, 101, 138, 110, 132 and 109 in Institute for Vegetable Crops germplasm collection exhibit satisfactory level of drought tolerance at vegetative phase and therefore may be used as parents in breeding programs

Adsorption capacity of wollastonite based adsorbents with porous structure controlled with different progeny agents

Porous wollastonite (WL) based adsorbents were fabricated by a pressureless sintering process by using low molecular weight poly(methyl methacrylate) (PMMA), nanocellulose (NC) and yeast as the pore forming agents. WL based adsorbents were synthesized in two step process. In the first step, calcium carbonate and methylhidrogen cyclosiloxane were mixed with isopropyl alcohol, dried and calcined at 250 °C. Second step included WL mixing with porogen, followed by controlled calcination and on that way the sintered materials with randomly distributed pores were obtained. The effectiveness of the synthesis steps as well as material properties, i.e., the pore morphology were determined by FTIR analysis and scanning electron microscopy (SEM), respectively. The pore morphology and adsorption capacity was changed dramatically by changing the pore forming agent. The highest adsorption capacity was obtained when NC was used as the pore forming agent. Obtained materials showed moderate adsorption capacities of 10.56, 8.42 and 11.33 mg/g with respect to As5+, Cr6+ and phosphate, respectively. The con centrations of heavy metal ions were determined by using Ion chromatography coupled with mass spectrometry (ICP-MS)

Procena tolerantnosti paradajza na sušu na osnovu selekcionih indeksa

This study was aimed to assess drought tolerance in twelve tomato populations collected in the territory of Serbia and to investigate relationships and repeatability among sixteen drought tolerance indices. Drought tolerance was estimated at the stage of intensive vegetative growth, on the basis of dry weight yield determined at optimal and limited irrigation (volumetric soil water content of 35.0 and 20.9%, respectively). The trial was set in pots placed in the greenhouse. Significant differences were found among populations in terms of all considered parameters; populations G125, G105 and G104 performed well in both irrigation regimes. High repeatability was found between the selection indices TOL and SSPI, STI and GMP, DWdr and YI, and among SI, SSI, RDI, SDI and RD. Principal component analysis allows simultaneous evaluation of populations and interpretation of interrelationships among the indices; it may be recommended as a method of choice for data analysis in further studies on drought tolerance in tomato.Ogled je postavljen sa ciljem procene tolerantnosti na sušu dvanaest populacija paradajza prikupljenih na teritoriji Srbije, kao i sa ciljem ispitivanja šesnaest selekcionih indeksa koji se koriste za tu procenu. Tolerantnost na sušu je utvrđena u fazi intenzivnog vegetativnog rasta, na osnovu prinosa suve materije izmerenog u uslovima optimalne i ograničene obezbeđenosti vodom (zapreminski procenat sadržaja vlage u zemljištu 35,0% odnosno 20,9%). Ogled je postavljen u saksijama smeštenim u staklenik. Konstatovane su značajne razlike među populacijama u pogledu svih izučavanih parametara; za populacije G125, G105 i G104 je utvrđen visok prinos suve materije u oba režima zalivanja. Visok stepen ponovljivosti je zabeležen za TOL i SSPI, STI i GMP, DWdr i YI, kao i između SI, SSI, RDI, SDI i RD. Metod glavnih komponenata je omogućio istovremeno vrednovanje populacija i interpretaciju veza između indeksa. Zato može da se preporuči za analizu podataka u budućim istraživanjima koja se tiču tolerantnosti paradajza na sušu

Synthesis and characterization of BaTiO3/α-Fe2O3 core/shell structure

Multiferroic materials attracted a lot of attention in recent years because of their significant scientific interest and technological applications. The multiferroic core/shell powders have a better connectivity between the phases, resulting in superior dielectric and magneto electric properties. In this study, the influence of preparation condition on structure and properties of BaTiO3/α-Fe2O3 core/shell composite materials was examined. The five samples were obtained by varying synthesis conditions, such as synthesized method (co-precipitation and sonochemical method) and pH values of solution. XRD and Raman spectroscopy analyses were performed in order to determine phase composition and structural changes within samples. Morphology modifications were examined by SEM and EDS analyses. Finally, effect of structural and microstructural changes on magnetic and electrical properties was detected and explained

Sestrinsko-medicinski problemi kod bolesnika s nefrotskim sindromom

Sažetak Nefrotski sindrom može biti uzrokovan brojnim bolestima koje zahvaćaju bubrege, posljedično s gubitkom bjelančevina, osobito albumina, mokraćom, do zadržavanja viška soli i vode u tijelu i povećane razine lipida u krvi. Nefrotski sindrom nema jasnu etiologiju, što znači da se manifestira kao skup simptoma odnosno znakova bolesti. Može se javiti uslijed raznih bolesti bubrega, najčešće glomerulonefritisa i dijabetičke nefropatije. Reakcije na medicinsku dijagnozu, nefrotski sindrom, su raznolike, a upravo o tim reakcijama primarno ovisi zadovoljavanje osnovnih ljudskih potreba bolesnika. Možemo zaključiti da su reakcije na medicinsku dijagnozu zapravo sestrinsko-medicinski problemi koji se manifestiraju kod pacijenta. Na temelju tih problema medicinska sestra planira skrb za pacijenta u cilju minorizacije problema, a u krajnjem cilju riješenja uzroka problema