Introduction of certification program in production of plum planting material

Certification program for the production of fruit planting material has not been fully established in the Republic of Serbia. Despite this fact, Fruit Research Institute, Čačak has initiated the introduction of certification into the production of plum planting material of cultivars developed at the Institute. The main goal is to establish plum mother plantations with basic material satisfying the EPPO recommendations and national certification standards.Propagated material from pomologically selected trees in commercial and experimental orchards was collected and grafted onto virus-free Myrobalan rootstock. Candidate clones are kept in screen house which ensure absence of infection. Fifteen plum (Prunus domestica) cultivars are included in this study: ‘Čačanska Lepotica’, ‘Čačanska Rodna’, ‘Čačanska Najbolja’, ‘Čačanska Rana’, ‘Valjevka’, ‘Valerija’, ‘Čačanski Šećer’, ‘Jelica’, ‘Timočanka’, ‘Boranka’, ‘Mildora’, ‘Krina’, ‘Pozna Plava’, ‘Požegača’, ‘Stanley’, and perspective hybrid 14/21.All tests were done according to the EPPO recommendations. Selected clones were tested on woody indicators Prunus tomentosa, P. persica and P. serrulata cv. Shirofugen. ELISA test was duly performed for the detection of the following viruses: Plum pox virus, Prune dwarf virus, Prunus necrotic ringspot virus, Apple chlorotic leaf spot virus, Apple mosaic virus and Myrobalan latent ringspot virus. To increase the sensitivity of Plum pox virus detection, IC-RTPCR was used. The material was also tested for the presence of ‘Candidatus Phytoplasma prunorum’ by nested-PCR method.The presence of viruses was found in 8 plants. ELISA test revealed that four plants of cv. ‘Jelica’ were found to be positive on the presence of Apple chlorotic leaf spot virus. Latent infection with Plum pox virus was detected by IC-RTPCR in 4 candidate clones (1 plant of each of cvs ‘Valerija’, ‘Čačanska Rodna’, ‘Čačanska Lepotica’ and ‘Požegača’). The rest of the material was free of all other viruses. The infection with ‘Candidatus Phytoplasma prunorum’ was not evidenced in any of the tested plants.Keywords: certification, plum, viruses, phytoplasma

Health status of pome and stone fruit planting material imported to Serbia

We summarize results of the analysis of pome and stone fruit planting material to be imported to Serbia for the presence of quarantine and economically important viruses and phytoplasmas. The analysis was conducted 2004 – 2009 whereby, in compliance with the phytosanitary law regulations of the Republic of Serbia, officially inspected samples were subjected to the examination. During the period, a total of 325 samples were analyzed, i.e. 89 rootstock samples, 215 samples of different pome and stone fruit varieties, and 21 samples of stone fruit seed. The obtained results reveal that 5 samples were infected with viruses. Apple chlorotic leafspot virus was found in one sample of apple budwood, Prune dwarf virus was detected in Prunus avium L. seedlings, Plum pox virus was confirmed in 2 plum budwood samples, and Apple mosaic virus was also found in one sample of apple budwood. Keywords: Pome fruits, stone fruits, planting material, seed, viruses, phytoplasma

Metal rings and discs Matlab/Simulink 3D model for ultrasonic sandwich transducer design

Metal-endings are integral part of different ultrasonic sandwich transducers. In this paper a new Matlab/Simulink 3D model of the finite metal rings and discs of various dimensions is realized. With this model, which describes both the thickness and the radial resonant modes, and the coupling between them, mechanical impedance of the sample can be easily computed. Resonance frequency-length curves for rings and disks with various materials and for different selected dimensions are given. Also, comparisons of the different approaches in determining of their resonant frequencies are shown. The proposed Matlab/Simulink model requires simpler implementation than other analytical models. That enabled modifying of 1D theory and simplified modelling and projecting of the ultrasonic sandwich transducers with short-endings. Finally, the computed and experimental results are compared. [Projekat Ministarstva nauke Republike Srbije, br. TR33035, br. III43014 i br. OI172057

Electrical Characterization and Impedance Response of Lanthanum Doped Barium Titanate Ceramics

The dielectric permittivity and dissipation factor of La-doped and undoped BaTiO3 were investigated as a function of frequency and temperature. The impedance response was used to study the electrical properties of La-doped BaTiO3 over the temperature range from room temperature (RT) to 350 degrees C. La-doped and undoped BaTiO3, obtained by a modified Pechini method, were sintered in air at 1300 degrees C for 2 and 16 hours. The impedance spectra were analyzed in terms of equivalent circuits involving resistors, capacitors and constant phase elements (CPE). The most suitable electrical circuit for the interpretation of experimental results is found to be the equivalent circuit consisting of resistors and CPE elements which replace the capacitor elements. The contribution of grain boundary resistance to the total resistance of a system is remarkable at low temperature. Dielectric permittivity of doped BaTiO3 was in the range of 8000 to 12000 at 1 kHz and the dissipation factor was less than 1%

Application of the intergranular impedance model in correlating microstructure and electrical properties of doped BaTiO3

Microstructure properties of barium-titanate based materials, expressed in grain boundary contacts, are of basic importance for electric properties of this material. In this study, the model of intergranular impedance applied on a two-grain contact is considered. Globally, a BaTiO3-ceramics sample consists of a large number of mutually contacted grains, which form clusters. Such clusters can be presented as specific fractal formations. For each of them, it is possible to establish the equivalent electrical model and, for a defined set of input parameters, using symbolic analysis, obtain the frequency diagram. The influence of fractal structure is especially stressed. Realizing the totality of relations between cluster grain groups, their microelectrical schemes and corresponding frequency characteristics, on one hand, and the global equivalent electrical scheme and corresponding acquired frequency characteristics of BaTiO3-ceramics samples, on the other hand, we set a goal of correlating experimental results with the summing effect of microelectric equivalent schemes. The model is successfully tested on doped barium-titanate ceramics.Mikrostrukturna svojstva materijala na bazi barijum-titanata, izražena kontaktima granica zrna od fundamentalne su važnosti za električna svojstva ovih materijala. U ovom radu razmatrana je primena modela impedanse između dva zrna na kontakt dva zrna. Globalno posmatrano, uzorak BaTiO3-keramike sastoji se od ogromnog broja zrna u međusobnom kontaktu koji formiraju klastere. Takvi klasteri mogu biti predstavljeni kao specifične fraktalne formacije. Za svaku od ovih formacija moguće je uspostaviti ekvivalentni električni model za definisani set ulaznih parametara koristeći metod simboličke analize i dobiti odgovarajuću frekventnu karakteristiku. Posebno je naglašen uticaj fraktalne strukture. Realizujući kompletnu relaciju između klastera zrna, njihovih mikroelektričnih šema i odgovarajućih frekventnih karakteristika s jedne strane, i globalnih ekvivalentnih električnih šema i odgovarajućih frekventnih karakteristika uzoraka BaTiO3-keramike, s druge strane, uspostavljamo set ciljanih koincidentnih eksperimentalnih rezultata sa sumarnim efektima izračunavanih mikroelektričnih ekvivalentnih šema. Model je uspešno testiran na uzorcima barijum-titanatne keramike

Metagonimus yokogawai: A new parasitic trematoda species in ichtyoparasitofauna of the Serbia

During the study of fish parasites in the Serbian section of the Danube River in 2003, a new Trematoda species for ichthyofauna of Serbia has been detected. It is, at the same time, the first finding of larvae of Metagonimus yokogawai in Serbia, as adult forms have been observed from mallard Anas platyrhynchus (L.), previously. Metacercariae of M. yokogawai have been identified on the scales of chub Leuciscus cephalus (L.), barbel Barbus barbus (L.), bleak Alburnus alburnus (L.), pikeperch Sander lucioperca (L.) and rudd Scardinius erythrophthalmus (L.) in the Serbian part of Danube River. The particular risk, beside the possible negative influence of spreading on fish and other host populations (some aquatic snails, fish-eating birds and some mammals), is the potential spreading of the parasitic disease in humans - Metagonimosis.Tokom istraživanja parazita riba srpskog dela Dunava (2003) nađena je nova vrsta Trematoda za ihtioparazitofaunu Srbije. Ovaj nalaz je istovremeno i prvi nalaz larvi (metacerkarija) metilja Metagonimus yokogawai (Katsurada, 1912) s obzirom da su odrasle jedinke ovog parazita nađene prethodno kod divljih pataka Anas platyrhynchus (L). Metacerkarije M. yokogawai pronađene su na krljuštima klena Leuciscus cephalus (L.), mrene Barbus barbus (L.) uklije Alburnus alburnus (L.), smuđa Sander lucioperca (L.) i crvenoperke Scardinius erythrophthalmus (L). Posebna opasnost, pored širenja infekcije metiljem M. yokogawai i negativnog uticaja na populaciju riba i ostalih prelaznih domaćina (neki vodeni puževi, ribojedne vrste ptica i neki sisari), jeste i pojava metagonimioze kod ribojednih sisara, među kojima je i čovek.nul

Electronic Ceramic Structure within the Voronoi Cells Model and Microstructure Fractals Contacts Surfaces New Frontier Applications

In this study, in order to establish grain shapes of sintered ceramics, new approach on correlation between microstructure and doped BaTiO3 -ceramics properties based, on Voronoi model and mathematical statistics calculations on fractal geometry, has been developed. BaTiO3-ceramics doped with Yb2O3 (from 0.1 to 1.0wt% of Yb) were prepared by using conventional solid state procedure and were sintered from 1320 degrees C to 1380 degrees C for four hours. The microstructure of sintered specimens was investigated by Scanning electron microscope JEOL-SEM-5300. For better and deeper characterization and understanding of the ceramics material microstructure, the methods which include the fractal nature structure, and also Voronoi model and mathematical statistics calculations, are applied. In our research the Voronoi is one specific interface between fractal structure nature and different stochastically contact surfaces, defined by statistical mathematical methods. Also, the Voronoi model practically provided possibility to control the ceramics microstructure fractal nature. Mathematical statistic methods enabled establishing the real model for the prognosis based on correlation: synthesis-structures-properties

Study of Barium Bismuth Titanate Prepared by Mechanochemical Synthesis

Barium-bismuth titanate, BaBi4Ti4O15 (BBT), a member of Aurivillius bismuth-based layer-structure perovskites, was prepared from stoichiometric amounts of barium titanate and bismuth titanate obtained via mechanochemical synthesis. Mechanochemical synthesis was performed in air atmosphere in a planetary ball mill. The reaction mechanism of BaBi4Ti4O15 and the preparation and characteristics of BBT ceramic powders were studied using XRD, Raman spectroscopy, particle analysis and SEM. The Bi-layered perovskite structure Of BaBi4Ti4O15 ceramic forms at 1100 degrees C for 4 h without a pre-calcination step. The microstructure of BaBi4Ti4O15 exhibits plate-like grains typical for the Bi-layered structured material and spherical and polygonal grains. The Ba2+ addition leads to changes in the microstructure development, particularly in the change of the average grain size

The application of autochthonous potential of probiotic lactobacillus plantarum 564 in fish oil fortified yoghurt production

The objective of this work was to investigate the survival of autochthonous, potentially probiotic bacteria Lactobacillus plantarum 564, and the influence of long-chain polyunsaturated fatty acid omega-3 (omega-3 PUFA) fish oil fortification on the sensory quality of yoghurt. Three variants of yoghurt were produced using starter cultures of Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus thermophilus (Chr. Hansen, Denmark), and the potentially probiotic Lactobacillus plantarum 564 (Culture Collection of the Department for Industrial Microbiology, Faculty of Agriculture, University of Belgrade) as follows: (1) without omega-3 PUPA; (2) with 100 mg/l omega-3 PUFA; and (3) with 200mg/l omega-3 PUFA. The survival of potential probiotic Lb. plantarum 564, the changes of starter bacteria counts, changes of pH values, as well as sensory evaluation, were examined during 3 weeks of yoghurt storage. Cells of Lb. plantarum 564 were maintained at > 10(8) cfug(-1). Starter bacteria counts were > 10(7)cfug(-1) for streptococci and > 10(6) cfug(-1) for lactobacilli. The changes of pH were within normal pH of fermented milks. Sensory evaluation showed that all variants of yoghurt produced with Lb. plantarum 564 and 2 concentrations of omega-3 polyunsaturated fatty acids had a high sensory quality (above 90% of maximal quality), and which did not change significantly throughout the examined storage period. Although the sensory quality of the control sample was evaluated as better, the experimental samples fortified with fish oil were also characterized with very acceptable sensory properties. Results of high viability of potential probiotic Lb. plantarum 564, as well as very acceptable yoghurt sensory properties, indicate that this strain can be successfully used in the production of yoghurt fortified with PUFA omega-3 fish oil as a new functional dairy product