Mechanically activated ceria

The reduction of comercial and mechanically activatedCeO2 powder at 1200 °C in an argon atmosphere was examined by XRD. Mechanical activation of oxide powder was performed by milling in a vibratory mill for different lengths of time. During 30 min of milling it came to the greatest change in crystallite size, as well as of lattice distortion of CeO2 while after 60 min of activation effect of milling on the CeO2 properties was negligible. Fired CeO2 was partly reduced but firing of 60 min milled CeO2 produced only CeO2-x with lattice parameter a = 0,550 nm.Physical chemistry 2004 : 7th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 21-23 September 200

Synthesis of apatite-type Ce4.67(SiO4)3O via glycinenitrate combustion

The pure Ce4.67(SiO4)3O with the apatite-type of structure was obtained for the first time from cerium nitrate, glycine and tetraethyl orthosilicate (TEOS) through the self-combustion of the gel. The solution of the reactants with the molar ratio of TEOS to water 1: 42 and glycine to NO3 ¯ 1: 3 was transformed into gel. During combustion of the gel the ash containing nanostructured CeO2 and noncrystalline SiO2 was formed. The phase identification and the measurement of the crystallite size was done by XRD diffraction. Ce4.67(SiO4)3O was synthesized from the ash subsequently fired in argon at 1200 °C.Physical chemistry 2008 : 9th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 200

The effects of the parents’ genotype on susceptibility to leaf curl (Taphrina deformans (Berk.) Tul) of vineyard peach hybrid seedlings

Leaf curl is one of the peach diseases with the most economically important impact, because very strong infection can cause total defoliation. Susceptibility to a leaf curl was examined from the period 1994-1998 in a collection of selected vineyard peach genotypes and newly peach and nectarine cultivars. Selected low susceptible genotypes (vineyard peach GR/65/87 and processing peach Villa Ada) were used in cross-pollination with differently susceptible genotypes. The process produced more than 250 seedlings of F1 progeny from few combinations of the parents. Susceptibility of hybrid seedlings to the leaf curl pathogen was investigated several years in the open field, without application of pesticide. More types of inheritance of examined characteristic were determinate in the progenies from different combinations of the parents. The results agree with polygenic inheritance.

Isoenzyme polymorphism of almond genotypes selected in the region of northern Serbia

Isoenzyme polymorphism was studied in 20 almond (Prunus dulcis [Mill.] D. A. Webb) genotypes selected from seedling populations of unknown almond cultivars in the region of northern Serbia (Vojvodina). Fourteen enzyme systems were studied using the method of vertical polyacrylamide gel electrophoresis. Ten systems were polymorphic in twelve loci. This polymorphism allowed unique identification of all studied genotypes. The most useful enzyme for analysis of almond genetic variability was menadione reductase. Polymorphism identified for alkaline phosphatase, formate dehydrogenase, glutamate dehydrogenase, malic enzyme, and menadione reductase was reported for the first time in almond. Cluster analysis was used to construct a dendrogram on which five clusters with different number of genotypes could be identified

Ispitivanje auto-(in)kompatibilnosti genotipova badema (Prunus amygdalus batsch) selekcionisanih na Slankamenačkom bregu

Due to the importance of obtaining almond cultivars adapted to the agroecological conditions of Serbia, in the period 2005-2006 pollen viability and self-(in)compatibility in 19 almond genotypes selected from the seedling population on Slankamen hill, were studied. All analyzed almond genotypes had good (50-70%) or high (over 70%) pollen germination. The study of self-(in)compatibility was done by monitoring of the fruit set in the field and observing self-pollen growth by fluorescence microscopy. Self-incompatibility was confirmed in all the 19 genotypes by both methods. Pollen tube penetration was stopped mostly at the upper third of the style of all genotypes, with characteristic irregularities.U cilju stvaranja sorti badema prilagođenih agro-ekološkim uslovima Srbije u periodu 2005.-2006. godine proučavana je klijavost polena i auto (in)kompatibilnost 19 genotipova badema odabranih iz populacije sejanaca na Slankamenačkom bregu. Svi ispitivani genotipovi badema imali su dobru (50-70- %) ili visoku klijavost polena (preko 70%). Ispitivanja auto (in)kompatibilnosti su obavljena praćenjem zametanja u poljskim uslovima i metodom fluorescentne mikroskopije. Auto inkompatibilnost je u oba slučaja bila izražena kod svih 19 genotipova. Kod svih genotipova polenove cevčice su zaustavljale rast najdalje u gornjoj trećini stubića uz karakteristične petlje, zadebljanja i krivudanja

An austempering study of ductile iron alloyed with copper

Austempered ductile iron (ADI) has proved to be an excellent material as it possesses attractive properties: high strength, ductility and toughness are combined with good wear resistance and machinability. These properties can be achieved upon adequate heat treatment which yields the optimum microstructure for a given chemical composition. In this paper the results of an investigation the austempering of ADI alloyed with 0.45 % Cu for a range of times and temperatures are reported. The microstructure and fracture mode developed throughout these treatments have been identified by means of light and scanning electron microscopy and X-ray diffraction analysis. It was shown that the strength, elongation and impact energy strongly depend on the amounts of bainitic ferrite and retained austenite. Based on these results, and optimal processing window was established

Fenološke karakteristike ranih sorti jagode gajenih na otvorenom polju i u plasteniku

The objective of this study was to analyze phenological traits of newly cultivars of strawberry from early ripening group: Clery, Queen Elisa and Madeleine. Plants were grown on black mulch foil, at the distance 30x30 cm, with fertirigation. The planting was done at the end of July 2004. in the Institute PKB Agreokonomik. During the period of 2005-2007 flowering and ripening time was observed the open field and under a high plastic tunnel. The earliest flowering and ripening time had cultivar Clery. Compare to open field, in the plastic tunnel start of flowering was 11 and ripening 10 days early for all cultivars.Cilj rada je ispitivanje fenoloških osobina novijih sorti jagode ranijeg vremena zrenja: Clery, Queen Elisa i Madeleine. Jagode su gajene na crnoj foliji, sa razmakom sadnje 30x30 cm, uz obezbeđenu fertirigaciju. Sadnja je obavljena krajem jula 2004. god. na Oglednom polju Instituta PKB Agroekonomik. U periodu 2005-2007. praćeno je vreme cvetanje i sazrevanja kod biljaka gajenih na otvorenom polju i u plasteniku. Najranije vreme cvetanja i sazrevanja imala je sorta Clery. Sve ispitivane sorte počinju da cvetaju i sazrevaju prosečno 11, odnosno 10 dana ranije u plasteniku nego na otvorenom polju

The effect of boron on the amount and type of carbides in chromium white irons

The effect of boron, in the amounts of 0.26, 0.39, and 0.59 wt.%, on the volume fraction and structure of carbides in Cr white irons was examined. It was demonstrated that the addition of boron can change the microstructural characteristics of white iron containing about 13 wt.% Cr. With increasing boron content, the volume fractions of M3C carbide increase., but the volume fracton of M7C3 carbide remains unchanged. The addition of boron tends to produce hard borides and/or borocarbides. It also prevents the formation of pearlite which results in alloys possessing good wear resistance

Uticaj gustine sadnje na bujnost breskve i nektarine

Peach production in highly developed countries (France, USA, Greece, Italy) is about 20 t/ha, but average yield in Serbia is much lower. One of the main prerequisite to obtain regular and high yields in peach and nectarine orchard of Serbia is to introduce new training systems. Investigations were done in Fruit research station of the Institute PKB Agroekonomik in Padinska Skela near Belgrade. Orchard was done with vineyard peach seedlings planted and grafted directly on place. Sloping leader was used as training system. Planting distance was 3.5 x 1 m and 3.5 x 1.5 m. In standard trial one year old fruit trees were planted at distance 4 x 2 m with fuseto and at 4 x 4 m with open vase as training systems. Results of three year research how planting distance was influenced on tree vigour parameters of the peach Autumn Glo and clone of nectarine Stark Red Gold was shown. Planting density has significant influence on diameter of epibiote and hypobiote trunk so as on decreasing of central leader vigor.Prosečni prinosi breskve u zemljama sa razvijenom voćarskom proizvodnjom (Francuska, SAD, Grčka, Italija) su oko 20 t/ha, dok su prosečni prinosi breskve u Srbiji značajno manji. Jedan od osnovnih preduslova za postizanje redovnih i visokih prinosa breskve i nektarine u Srbiji je uvođenje novih sistema gajenja i uzgojnih oblika. Istraživanja su obavljena u ogledno-proizvodnom zasadu Instituta PKB Agroekomik u Padinskoj Skeli. Podizanje zasada je obavljeno sadnjom i kalemljenjem sejanaca vinogradske breskve na stalnom mestu na rastojanju 3,5 x 1 m i 3,5 x 1,5 m , i formiranjem uzgojnog oblika kosa vođica. Standardni deo ogleda je podignut sadnjom jednogodišnjih sadnica na rastojanju 4 x 2 m uz primenu fuzeta, i 4 x 4 m uz primenu kotlaste krune. Ispitivan je uticaj gustine sadnje na bujnost stabala breskve Autumn Glo i klona nektarine Stark Red Gold. U radu su prikazani trogodišnji rezultati ispitivanja parametara bujnosti. Gustina sadnje je ispoljila značajan uticaj na prečnik debla podloge, prečnik debla sorte i visinu ispitivanih stabala

The influence of chemical and thermal treatment on the point of zero charge of hydrous zirconium oxide

Two zirconia samples were prepared by precipitation from aqueous zirconium oxychloride and zirconyl sulfate solutions with potassium hydroxide. The prepared zirconia samples were amorphous. The pH(pzc) values of the zirconia samples, determined in NaCl and NaNO3 solutions, were 6.6 +/- 0.1 and 6.9 +/- 0.1, respectively. After prolonged hydration of zirconia in doubly distilled water, the pH(pzc) decreased to 4.7 +/- 0.3. Crystallization into tetragonal (metastable) + monoclinic zirconia appeared at 691 K. Above 873 K, the tetragonal metastable phase changes to a monoclinic phase. It was shown that crystallite sizes of zirconia treated at 673-1273 K increased from 9.5 to 40.5 nm, respectively. The increase in temperature from 385 to 1070 K increased the pH(pzc) of zirconia samples from 6.6 to 9.0, respectively