Apical leakage of root canal system obturation materials

Hermetical obturation on dentine-cement junction is one of the conditions for success in endodontic treatment. The aim of this paper was to evaluate apical obturation of three different root canal obturation materials. Methods consisted of in vitro semiquantitatively measured penetration of colored solutions. Total number of 55 single-canal teeth was used and obturation test materials were AH-plus, Ketac-Endo and Endomethasone. Linear color penetration was evaluated following illumination of teeth in 2% sol. Metylsalicilate. Results obtained have shown better adhesion between sealer and root canal walls, i.e. better apical obturation when AH-plus (0.25mm) and Ketac-Endo (0.52mm) were used and highest rate of apical leakage when Endomethasone was used (2.35mm). None of the tested obturation materials have sealed apical portion completely

THE SIGNIFICANCE OF DIDACTIC MEDIA IN TEACHING PHYSICAL EDUCATION

The aim of this paper is to present the significance of modern, electronic didactic media in the realization of physical education (PE) classes. PE helps students become skilled, active, healthy, responsible, independent and competent, able to think analytically and critically, and ready to act in new and unexpected situations. The didactic media open up wide application in contemporary PE classes that seeks to overcome the disadvantages of traditional teaching. It involves the introduction of innovative models of PE, as well as the use of modern didactic media. Advantages of the implementation are numerous, and most often emphasized: better motivation, and better communication between PE teachers and students in the educational process

Phenolic Content, and Antioxidant and Antimicrobial Activities of Crataegus Oxyacantha L (Rosaceae) Fruit Extract from Southeast Serbia

Purpose: The aim of this work was to determine the content of total phenols, total flavonoids, anthocyanins, as well as antioxidant and antimicrobial activities of hawthorn (Crataegus oxyacantha L.) alcohol, hydroalcohol and aqueous extracts.Methods: The content of total phenols, flavonoids and anthocyanins of the alcohol, hydroalcohol and aqueous extracts of hawthorn were determined using spectrophotometric methods. Antioxidant assay was based on the measurement of DPPH absorbance at 517 nm caused by the reaction of DPPH with the test sample. Antimicrobial activity was evaluated by measuring the zone of inhibition against selected test microorganisms: Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Pseudomonasaeruginosa, and Salmonella abony while antifungal activity was tested against two organisms: Aspergillus niger and Candida albicans.Results: The results of spectrophotometric investigations indicate that the content of total phenol compounds in the investigated extracts varied from 2.12 to 30.63 mg GAE g-1 of fresh hawthorn sample. The content of anthocyanins ranged from 0.3207 to 3.168 mg of cyanidin-3-O-glucoside g-1 of fresh hawthorn fruit. The fruit extracts showed high antioxidant activity with DPPH radical transformation value as high as 89.9 % in the methanol-water (50/50, v/v%)) extract. The ethanol extract exhibited antimicrobial activity against all test microorganisms except two, Bacillus subtilis and Staphylococcus aureus, and one species of fungi, Aspergillus niger. Flavonoid structure influenced the extract’s selectivity towards Gram-positive and Gram negative bacteria.Conclusion: Extracts of the fruit of Crataegus oxyacantha L. can be used as natural antioxidant and antimicrobial preparations.Keywords: Crataegus oxyacantha L.; Natural phenolic compounds; Antioxidant and antimicrobial activity, Southeast Serbia

Temperature and stress fields in thin metallic partially fixed plate induced by harmonic electromagnetic wave

U radu se razmatra ponašanje tanke elastične metalne ploče izazvano harmonijskim elektromagnetskim ravanskim talasom. Ploča je slobodno oslonjena duž tri ivice i ukleštena duž četvrte. Kao rezultat dejstva vremenski promenljivog elektromagnetskog polja pojavljuju se kondukcione struje u ploči. Raspodela snage kondukcionih i histerezisnih gubitaka po debljini ploče određena je primenom kompleksnog računa. U daljem proračunu ta snaga je tretirana kao zapreminski izvor toplote. Diferencijalne jednačine polja temperature rešene su metodom integralnih transformacija. Razmatran je i uticaj debljine ploče, frekvencije talasa i faktora histerezisnih gubitaka na temperaturno polje. Polja napona i deformacije određena su primenom metode konačnih elemenata i metode integralnih transformacija.In the paper the behavior of thin elastic metallic plate influenced by the harmonic electromagnetic plane wave is considered. The plate is simply supported along three edges and fixed along the fourth one. As a result of time-varying electromagnetic field the conducting currents appear in the plate. Distribution of eddy-currents and hysterisis power losses across the plate thickness are obtained by use of complex analysis. There after, by treating this power stemming from a volume heat source, differential equations governing distribution of the temperature field are formulated and solved by using integral-transform technique. The influence of the plate thickness, wave frequency and hysterisis factor on the temperature field are considered, as well. Strain and stress fields are obtained by using finite element method (FEM) and integral-transform technique

Analysis of morphological traits of bird's foot trefoil plants cv. Bokor transformed with Agrobacterium rhizogenes

An efficient method for genetic transformation and shoot regeneration was achieved in bird's foot trefoil cv. Bokor using A. rhizogens. The transformed shoots were regenerated on hairy root segments in high frequency. After rooting and acclimation, transformed To plants were grown in experimental field. Analysis of morphological traits and chemical content in ten unintentionally chosen To bird's foot trefoil plants (genotypes no. 2 and no. 5) was performed. They were compared to those of control non-transformed plants. The traits as a number of stems per plant, length of internodes in longest stem, number of flowers per plant and plan high were very significant differed than the same traits in control plants, while there were no significant differences in the leaf area. No signs of the rol genes genotype and "T" phenotype were present. The transformed plants had significantly higher content of cellulose, while the protein and nitrogen contents of are in the range of control plants

Student choice of higher education institutions in a post-transitional country: evidence from Serbia

The sector of higher education in developed countries has been facing important structural changes over the last decade, which is now expanding to developing countries also. As the competitive landscape is changing, the trend of commercialisation of higher education has become more evident. Higher education institutions (H.E.I.s) have been developing their business strategies, with a clear focus on marketing activities, changes in organisational processes, and even changes in their priorities and missions, thus becoming more lucrative. Knowing student behaviour and criteria for choice decisions and recognising the main determinants of students’ choice is the basis for establishing an effective strategy of H.E.I.s. The aim of this article is to shed light on student choice criteria when deciding which institution in higher education to enrol, and to identify main moderating influences. Linear mixed model (L.M.M.) was used as the main methodological tool for analysing the main variation in the attitudes and expectations of students, based on several moderating variables, their socio-demographic and personal characteristics. The results reveal main institutional attributes that HEIs from a posttransitional country can use for the effective market positioning, and the influence of gender, academic aspirations and achievements on the assessment of various students’ choice criteria

Temperature and stress fields in thin metallic partially fixed plate induced by harmonic electromagnetic wave

U radu se razmatra ponašanje tanke elastične metalne ploče izazvano harmonijskim elektromagnetskim ravanskim talasom. Ploča je slobodno oslonjena duž tri ivice i ukleštena duž četvrte. Kao rezultat dejstva vremenski promenljivog elektromagnetskog polja pojavljuju se kondukcione struje u ploči. Raspodela snage kondukcionih i histerezisnih gubitaka po debljini ploče određena je primenom kompleksnog računa. U daljem proračunu ta snaga je tretirana kao zapreminski izvor toplote. Diferencijalne jednačine polja temperature rešene su metodom integralnih transformacija. Razmatran je i uticaj debljine ploče, frekvencije talasa i faktora histerezisnih gubitaka na temperaturno polje. Polja napona i deformacije određena su primenom metode konačnih elemenata i metode integralnih transformacija.In the paper the behavior of thin elastic metallic plate influenced by the harmonic electromagnetic plane wave is considered. The plate is simply supported along three edges and fixed along the fourth one. As a result of time-varying electromagnetic field the conducting currents appear in the plate. Distribution of eddy-currents and hysterisis power losses across the plate thickness are obtained by use of complex analysis. There after, by treating this power stemming from a volume heat source, differential equations governing distribution of the temperature field are formulated and solved by using integral-transform technique. The influence of the plate thickness, wave frequency and hysterisis factor on the temperature field are considered, as well. Strain and stress fields are obtained by using finite element method (FEM) and integral-transform technique