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Open access

Jelena Jaćimović

Summary

Introduction Citation analysis, as one of the best-known bibliometric approaches, is widely used in the evaluation of research output and assessment of research performance and impact. The purpose of this study was to identify the top cited articles published by researchers affiliated to Serbian dental institutions and to analyze their characteristics in order to describe cooperation at individual and institutional, as well as at national and international level.

Material and Methods Articles that cited the most 2018 publication in the Web of Science were assessed. The analyzed aspects covered distribution of annual production, annual citations, journals, categories, countries, institutions, authors, research focuses and trends by author keywords and KeyWords Plus.

Results The top cited papers were published in 60 journals from 1997 to 2016, with the mean number of 45.08 citations per article. These papers were co-authored by 449 authors, responsible for 726 authorships, affiliated to 149 institutions from 41 countries. Among the overall number of authors, 238 were from Serbia, while 211 were affiliated with international institutions. The most productive institutions were the University of Belgrade and Military Medical Academy from Serbia, whilst the international contributing institutions were primarily from the USA, England, and Italy.

Conclusion The present study presented useful insight into the most influential Serbian dental institutions research, revealing the most productive actors and multidisciplinary nature of the research contribution.

Open access

Agnieszka Wójtowicz

Abstract

The aim of the research was to determine the selected properties of packaging materials applicable for vacuum and modified atmosphere packaging. Six samples of multilayer films with different composition were tested to evaluate the thickness, basic weight, density and the mechanical properties in elongation and puncture tests. Zwick/Roell apparatus equipped with elongation jaws and a puncture pin was used in the experiments. The tensile modulus, tensile strength, elongation at tensile strength, stress at break and work at break were investigated with the elongation test, whereas the breaking force, puncture work and extension at break were evaluated with the puncture test. The obtained results allow conclusion that the thickness and basic weight of the packaging films used in the vacuum system was higher comparing with the MAP system. Analyzing the results of the elongation modulus and stress at break it was reported that the materials used for food packaging in the MAP system were characterized with better properties, whereas elongation at the tensile strength was higher for films applied in the vacuum system, except for a film with a metalized layer. The highest resistance for puncture was evaluated for OPET/PE film used in MAP packaging. The extension at break under the puncture test was higher for films dedicated for vacuum packaging suggesting their better resistance for the mechanical damage by a thin pin. Several correlations between physical and mechanical properties of multilayer films were found.

Open access

Waclaw Romaniuk, Tetyana Zheliezna, Semen Drahniev, Anatoliy Bashtovyi, Henryk Sobczuk, Andrzej Marczuk, Liudmyla Titova, Ivan Rogovskii and Kinga Borek

Abstract

The article analyzes the current state of production of second generation biofuels in the world and evaluates the possibility of launching such production in Ukraine. The work is topical due to the fact that liquid biofuels can replace a certain share of motor fuels consumed in Ukraine, thus contributing to the strengthening of the country’s energy independence. The purpose of the study is to assess feasibility of a project on the production of second generation bioethanol in Ukraine; the task is to carry out a preliminary feasibility study for such a project. The analysis of the study of pure co-substrate fermentation and as a supplement for cattle manure proves that the maximum biogas yield obtained using alcohol stillage in a ratio of 40-80% increased compared to fermentation of pure cattle manure. The use of pure bards compared to the bard and the slurry mixture increases the maximum yield of biogas. It was found that the biogas obtained from the use of alcohol stillage is a high con-sumption of biogas with the methane content of between 70 and 78%.

Open access

Okey Francis Obi and Clement O. Akubuo

Abstract

This paper reports the effect of the parboiling time on dehulled kernel out-turns (DKO) of African breadfruit seeds, and the most recent effort to upgrade an existing dehuller and its performance. Two common and readily available varieties – Treculia var. africana and var. inverse were used in the study. The seeds were parboiled for 0 (control), 2, 5, 8, 11 and 14 minutes and then dehulled. The result revealed that the parboiling time had a significant effect on the DKO of the two varieties of the seed. The DKO increased from 0 to 5 min of the treatment, after which it decreased considerably up to 14 min of the parboiling time. The obtained data were used to develop a non-linear quadratic regression model to predict the DKO as a function of the parboiling time. The performance evaluation of the breadfruit seeds dehuller revealed that it was significantly influenced by the variety.

Open access

Jelena Nešković, Milica Jovanović-Medojević, Đurica Grga, Branka Popovic and Slavoljub Živković

Summary

Introduction The main objective of endodontic treatment is to eliminate infection from root canal and prevent reinfection by three-dimensional hermetic obturation of the canal system. Endodontic failure can occur due to inability of complete control and elimination of infection from the root canal.

The aim of this study is to investigate, by PCR technique, microbiological status of previously endodontically unsuccessfully treated teeth immediately after the removal of obturation material.

Material and Methods The analysis included 30 teeth indicated for endodontic retreatment. After removing previous root canal filling material, the bacteriological sample was taken by sterile instrument (# 15) and paper points. Standard PCR technique was used to analyze the incidence of E.faecalis, P.micros, P.intermedia, P. endodontalis and A.actinomycetemcomitans.

Results Positive bacteriological findings were registered in 80% of cases, while bacteria were not identified in 20% of all samples (all taken from the root canals without significant changes in periapical tissue). From 24 canals with identified bacteria, 17 had affected apical periodontium. The most dominant microbe in root canals with positive bacteriological finding was E.faecalis (83.3% of the canals) and P.intermedia (75%). In case of teeth with chronic periapical changes, the most common was E. faecalis (94%) and P.intermedia (82.3%).

Conclusion The presence of periapical lesions significantly affects microbiological status of endodontically treated teeth. The presence of bacteria was confirmed in most teeth with periapical lesions, while the most frequently identified bacteria were E. faecalis, P.intermedia and P.micros.

Open access

Maciej Kuboń

Abstract

The objective of the paper is to determine the size of human and objectified labour in selected specialist vegetable farms. The paper covered studies carried out in the area of southern Poland in 50 organic vegetable farms. Based on the detailed studies, the size and structure of work, and energy inputs used in the production process were determined. The highest inputs of labour per a unit of the production area and 1 tonne of a product were incurred in production of Cucurbita vegetables – 1883.1 and 547.74 man-hour, while the lowest of Solanacea vegetables – 342.8 and 7.11 man-hour. From among all analysed groups of plants, the highest energy inputs were incurred in cultivation of root and onion vegetables and they were three times higher than in traditional farms. Contrary, the lowest inputs were incurred in cultivation of brassica and Solanaceae vegetables.

Open access

Maja Ležaja Zebić, Nikola Jakovljević and Vesna Miletić

Summary

Introduction The aim of the study was to quantify and compare fluoride release from four different glass ionomer cement products (GICs).

Materials and Methods Standardized disk-shaped samples (5x2mm; n=5/group) of GIC restorative materials: conventional (Fuji IX, GC Corp., Japan), resin-modified (Fuji II LC, GC) and hybrid glass ionomer cement (Equia Forte, GC) and a conventional GIC liner/base material (Alfagal, Galenika, Serbia) were tested for fluoride release up to 21 days postsetting. Each sample was immersed in 5 mL of fresh deionized water during each time interval. Universal microhybrid composite (Filtek Z250, 3M EPSE, USA) and adhesive (Adper Single Bond, 3M ESPE) were used as negative controls. Fluoride release was measured using an F-selective electrode (Cole-Parmer, USA) and an ion meter (Oakton 700, Cole-Parmer, USA). Data were statistically analyzed using one-way ANOVA, regression and correlation analysis at 0.05.

Results The highest total fluoride release was measured from Alfagal (386±61 ppm/g), and significantly less from Equia (188±29 ppm/g), Fuji IX (143±11 ppm/g) and Fuji II LC (104±14 ppm/g) (p < 0.05). All GICs showed the highest fluoride release during the first 24 hours post-setting. After 3 days, fluoride release slowed down reaching a plateau for all materials. Regression and Pearson correlation analysis showed significant inverse relationship between fluoride release and sample mass and density (p<0.001).

Conclusion Of the three GICs indicated for use as restorative materials, Equia Forte released the highest fluoride concentration. Fluoride release was material and density dependent, with higher release occurring from lower density GICs.

Open access

Mirjana Umićević Davidović, Marijana Arapović Savić and Adriana Arbutina

Summary

Introduction In everyday clinical practice, we often encounter a lack of space for placing all the teeth present into dental arch; therefore it is often recommended to extract teeth within orthodontic treatment. In clinical practice, the most commonly used methods of closing space after are elastic chains and NiTi closed spiral springs. The aim of this paper was to compare postextraction space closure speed using two different sliding mechanisms, NiTi closed coil springs and elastic chains within treatment with fixed orthodontic appliances.

Material and Method The total sample in this study consisted of 46 postexstraction spaces in 23 patients indicated for the extraction of first premolars using treatment with fixed orthodontic appliances. Two sliding mechanisms, NiTi closed coil spring and elastic chains were applied to postextraction space closure. Postextraction spaces were monitored for 4 months with appointments every 4 weeks. During appointments mechanisms were activated and digital caliper was used to measure the width of the postextraction space.

Results The results showed that NiTi closed coil springs method achieved greater reduction in postexstraction space (3.94 mm) while with elastic chain method the closure of 3.10 mm was achieved. The total difference between these two methods in the observed period was 0.84mm and no statistically significant difference was found (p> 0.05). The lowest value for NiTi closed springs was 2.19 mm, while for the elastic chain it was 1.29 mm. The best postextraction space closure was 5.70 mm and it was completed using NiTi closed springs while for elastic chain the best value was 4.80 mm.

Conclusion: NiTi closed coil springs lead to faster closure of postextraction spaces in relation to elastic chain. Since this difference is minimal, in practice, both methods can be used equally.

Open access

Stanisław Parafiniuk, Marek Milanowski, Anna Krawczuk, Józef Sawa and Alaa Kamel Subr

Abstract

Two tests were carried out to measure the standard flat fan nozzles wear during a specific period of an accelerated wear procedure. The first test aimed at getting 10% increase in the flow rate compared to the nominal flow rate, which is the threshold to replace the nozzles according to the nozzles testing standards. The second test was to wear the nozzles intensively (100 hours of accelerated wear), which represents the use of nozzles beyond the allowed threshold. The results showed that the flow rate reached 1.31 l·min−1 (equal to 10% increase) for the tested nozzles after 35 hours of the wear test. For the second test, the 10% increase of the flow rate was reached after approximately 30 hours. The wear rate reached 27.5% at the end of the test and this is 2.7 times more than the standardized threshold.