Contemporary Materials最新文献

{"title":"EFFECT OF DIFFERENT CONCENTRATIONS OF THE TEETH BLEACHING AGENTS ON THE QUALITY OF BOND BETWEEN COMPOSITE MATERIAL AND BLEACHED TOOTH","authors":"Aleksandra Đeri, N. Knežević, O. Janković, Irena Kuzmanović Radman, Renata Josipović, V. Mirjanić","doi":"10.7251/comen1901064k","DOIUrl":"https://doi.org/10.7251/comen1901064k","url":null,"abstract":"Micro-morphological and organic-inorganic changes of dental structure as well as the effect of hydrogen peroxide on polymerisation of composite materials cause lower adhesion, i.e. poor bond quality between composite material and bleached tooth. The aim of this study was to determine the effect of different concentrations of carbamide (16%, 20% and 30%) and 35% hydrogen peroxide on bond strength of the composite materials and bleached endodontically treated teeth. Methods: The current study included 40 extracted human endodontically treated teeth. Internal bleaching was done using the “Walking bleach technique” method. The teeth were bleached with 16%, 20%, 30% carbamide or 35% hidrogen peroxide. After internal teeth bleaching, a class V cavity was prepared and restored with Tetric EvoCeram nanocomposite material. Microleakage was determined using dye method (silver nitrate) and measured on the incisal and gingival walls using stereoloupes. Results: The smallest dye penetration on the occlusal wall was found of teeth bleached with 20% carbamide peroxide (5,45 μm), and the largest dye penetration was on teeth bleached with 30% carbamide peroxide (7,25 μm). The smallest dye penetration on the gingival wall was found on teeth bleached with 16% carbamide peroxide (12,25 μm) and the largest dye penetration was on teeth bleached with 30% carbamide peroxide (20,00 μm). The difference was statistically significant (p 0.05). Conclusion: Microleakage was detected in all teeth restored with composite and bleached with the internal bleaching technique with 16%, 20%, 30% carbamide or 35% hydrogen peroxide.","PeriodicalId":10617,"journal":{"name":"Contemporary Materials","volume":"173 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79581563","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"3D PRINTING AND 3D BIOPRINTING TO USE FOR MEDICAL APPLICATIONS","authors":"M. Šljivić, D. Mirjanić, Nataša Šljivić, C. Fragassa, A. Pavlović","doi":"10.7251/comen1901082s","DOIUrl":"https://doi.org/10.7251/comen1901082s","url":null,"abstract":"The Additive manufacturing 3D printing is a process of creating a three dimensional solid objects or rapid prototyping of 3D models from a digital file, which builds layer by layer. The 3D bioprinting is a form sophisticated of 3D printing technology involving cells and tissues for the production of tissue for regenerative medicine, which is also built layer by layer into the area of human tissue or organ. This paper defines the modern methods and materials of the AM, which are used for the development of physical models and individually adjusted implants for 3D printing for medical purposes. The main classification of 3D printing and 3D bioprinting technologies are also defined by typical materials and a field of application. It is proven that 3D printing and 3D bioprinting techniques have a huge potential and a possibility to revolutionize the field of medicine.","PeriodicalId":10617,"journal":{"name":"Contemporary Materials","volume":"20 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76496563","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"DIGITAL IMAGING ANALYSIS OF THE PLACENTA","authors":"Vesna Ljubojević","doi":"10.7251/comen1901100lj","DOIUrl":"https://doi.org/10.7251/comen1901100lj","url":null,"abstract":"Recent studies indicate that placental and umbilical cord morphometry are the factors that may be associated with pregnancy complications, such as fetal growth restriction. Recently, placental and umbilical cord morphometry have been performed using digital image analysis. The aim of this study was to determine the morphometric parameters of placentas using digital image analysis. Material and methods: The digital imaging analysis of twenty placentas and umbilical cord were performed using Image Analysis LAS V4.3 software. Results: The length of the placentas was 191,77 mm ± 35,86 mm (mean ± standard deviation). The width of the placentas was 166,01 mm ± 19,01 mm. The placental surface area was 24495,13 mm2 ± 7038,86 mm2. The insertion of the umbilical cord to the placenta was central in 50 %, peripheral in 37,50 % and marginal in 12,5 % of analyzed placentas. The average distance of the umbilical cord insertion from the nearest placental margin was 38,89 mm ± 28,39 mm. The umbilical cord diameter at the insertion site was 21,16 mm± 5.69 mm. The diameter of the umbilical cord two centimeters from the insertion site was 12,36 mm ± 3,45 mm. Conclusion: Digital image analysis enables obtaining the objective morphometric parameters of the placenta and umbilical cord. The obtained morphometric parameters of the placenta and umbilical cord for our population are comparable to results of previous studies and open further placental research directions for the development of the screening method.","PeriodicalId":10617,"journal":{"name":"Contemporary Materials","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86841520","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"ASSESSMENT OF ENAMEL SURFACE AFTER APPLICATION OF TUNGSTEN CARBIDE BUR FOR RESIDUAL ADHESIVE REMOVAL","authors":"Marijana Arapović Savić, Adriana Arbutina, Mirjana Umićević Davidović, V. Mirjanić, Irena Kuzmanović Radman","doi":"10.7251/comen1802137a","DOIUrl":"https://doi.org/10.7251/comen1802137a","url":null,"abstract":"Enamel damage often occurs in a process of adhesive removal after the completion of therapy with fixed orthodontic appliances. The aim of this study was to evaluate the enamel surface after applying a 12-fluted round tungsten carbide bur for adhesive removal at different speeds of dental micro motor after debonding brackets. Material and method: On 40 human premolars, extracted for orthodontic purposes, metal brackets were bonded with composite material. After removing the brackets, the sample was divided into two groups: group A - 20 teeth from which the rest of the composite material was removed with a round tungsten carbide bur at 8,000 rotations per minute and group B - 20 teeth from which the rest of adhesive was removed with a round tungsten carbide bur at 32,000 rotations per minute. For each sample, four images were made under different magnifications by scanning electron microscopy, and the damage estimation was performed using the Enamel damage index (EDI) and Surface roughness index (SRI). Results: The most common EDI score on the overall level was 3 (62.5%), while the most commonly represented SRI score was 2 (52.5%). There was no statistically significant difference in the average values of the EDI index (t (38) = -.96, p> .05) and in the average SRI index values (t (38) = -. 89, p> .05) between two tooth examined groups. Conclusion: Enamel damage was found after applying a round tungsten carbide bur at 8,000 and 32,000 rpm. The number of rotations per minute did not affect the size of enamel damage.","PeriodicalId":10617,"journal":{"name":"Contemporary Materials","volume":"78 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84015473","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"ENUMERATION OF DIMER CONFIGURATIONS ON A FRACTAL LATTICE","authors":"D. Marčetić, Sunčica Elezović Hadžić, I. Živić","doi":"10.7251/comen1802115m","DOIUrl":"https://doi.org/10.7251/comen1802115m","url":null,"abstract":"In this paper, we present a solution to the close-packed dimer problem on a fractal lattice. The dimer model is canonical model in statistical physics related with many physical phenomena. Originally, it was introduced as a model for adsorption of diatomic molecules on surfaces. Here we assume that the two dimensional substrate on which the adsorption occurs is nonhomogeneous and we represent it by the modified rectangular (MR) fractal lattice. Self-similarity of the fractal lattice enables exact recursive enumeration of all close-packed dimer configurations at every stage of fractal construction. Asymptotic form for the overall number of dimer coverings is determined and entropy per dimer in the thermodynamic limit is obtained.","PeriodicalId":10617,"journal":{"name":"Contemporary Materials","volume":"49 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90208854","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"TESTING OF THE FRACTURE RESISTANCE OF THE HEAT-CURING DENTURE BASE ACRYLIC RESIN","authors":"Aleksandra Maletin, Jovana Bastajić, I. Ristić, Branislava Petronijević Šarčev, Isidora Nešković, Tanja Veljović, D. Marković","doi":"10.7251/comen1802130m","DOIUrl":"https://doi.org/10.7251/comen1802130m","url":null,"abstract":"For many years, poly-methyl methacrylate has been used as a material of choice for making the denture base, thanks to its good and desirable performances, such as: simplicity in work, possibility of reparation, aesthetics and affordable price. Considering to its insufficient hardness and fracture resistance, there is a tendency to improve the mechanical properties of the material, by changing its basic composition. The aim of the research was to determine the fracture resistance of the heat-curing denture base acrylic resin materials. Materials and methods: For the research ,20 samples of the 2 heat-curing acrylics had been prepared, standard ones and reinforced acrylic resin material. After the storage in the saline for 15 days, measurements of the fracture resistance were performed by using the universal testing device. The data were statistically processed using the Student’s t-test for independent samples. Results: By measuring the flexural strength and deflection at breakage, it has been proven that there was, statistically, a significant difference of the flexural strength between reinforced (179.91-248.72MPa) and standard heat-curing acrylics (183.25- 200.74MPa). The deflection at breakage showed approximately the same values for both materials (1,0-1,4mm; 1.0-1.5mm). Conclusion: By enhancing the polymer, the mechanical properties of the denture base acrylic resin materials will be improved, primarily, higher fracture resistance, that means that these technologies need to be improved.","PeriodicalId":10617,"journal":{"name":"Contemporary Materials","volume":"17 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79901484","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"POLYCRYSTALLINE SILICON PV MODULES AS ELEMENTS OF BIPV SYSTEMS","authors":"D. Milosavljević, D. Mirjanić, Darko Divnić, T. Pavlovic, L. Pantić, I. Radonjić","doi":"10.7251/comen1802176m","DOIUrl":"https://doi.org/10.7251/comen1802176m","url":null,"abstract":"In this paper, the basic information of BIPV systems and results of theoretical and experimental investigation of electrical energy generated by differently oriented PV modules as elements of BIPV systems in Banja Luka, are given. It was found that in the period from September 1, 2014 to August 31, 2015, optimally oriented polycrystalline silicon PV module of 50Wp generated 61.32 kWh, horizontal module 52.37 kWh, vertical module oriented toward the South 38.72 kWh, vertical module oriented toward the East 25.74 kWh, and vertical module oriented toward the West 24.98 kWh of electrical energy. For theoretical investigation of electrical energy generated with differently oriented PV modules, the PVGIS-CMSAF software is used. The obtained results can be applied in designing residential, commercial and other buildings with BIPV systems in the Republic of Srpska where such investigations have not been not been performed earlier. Keywords: PV electricity generation, BIPV systems, PVGIS-CMSAF software.","PeriodicalId":10617,"journal":{"name":"Contemporary Materials","volume":"42 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90587383","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"THE MINOR INFLUENCE OF CALCIUM DOPED PHOSPHATE TUNGSTEN BRONZE ON THE BRIGGS-RAUSCHER REACTION DYNAMICS","authors":"J. Maksimović, Tijana V. Maksimović, Z. Nedić, Maja C. Pagnacco","doi":"10.7251/comen1802184m","DOIUrl":"https://doi.org/10.7251/comen1802184m","url":null,"abstract":"The Briggs-Rauscher (BR) oscillatory reaction is the oxidation of malonic acid in the presence of hydrogen peroxide and iodate in the acidic environment, which is catalyzed by ions of manganese. This reaction is very sensitive to the presence of additives. In this paper, the BR reaction has been used to investigate the phosphate tungsten bronze as well as calcium doped tungsten bronze, obtained by thermal treatment. The addition (0.01-0.08 g) of phosphate tungsten bronze and calcium doped phosphate tungsten bronze has a different effect on the dynamics of the Briggs-Rauscher reaction. In the case of the addition of phosphate tungsten bronze in the Briggs-Rauscher reaction, the linear dependence of the length of the oscillatory period on the mass of the added bronze was obtained, while in the case of addition of calcium doped phosphate tungsten bronze, the oscillatory period does not significantly change with an increase of added mass. The mechanism of calcium doped and undoped phosphate tungsten bronze action in BR reaction is probably adsorptive, and it will be the subject of future work. Keywords: oscillatory reactions, Briggs-Rauscher reaction, phosphate tungsten bronze, calcium doped phosphate tungsten bronze, thermal treatment.","PeriodicalId":10617,"journal":{"name":"Contemporary Materials","volume":"142 11 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79685414","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A CASE STUDY OF THE INCREASE OF CARBON DIOXIDE DUE TO THE APPLICATION OF ENERGY EFFICIENCY REGULATIONS IN SERBIA","authors":"Marina Nikolić Topalović, M. Stanković","doi":"10.7251/comen1802159n","DOIUrl":"https://doi.org/10.7251/comen1802159n","url":null,"abstract":"In order to demonstrate the environmental impact of the increased flow of thermal insulation materials and facade joinery with improved thermal characteristics, the analysis of the carbon footprint for two scenarios for the needs of the research was done as a consequence of the new regulations on the energy efficiency of the facilities. For each of the analyzed scenarios, a project and an overview of works on the basis of which quantities of construction materials, activities and processes that participate in the construction of the analyzed scenarios were calculated (S1 and S2), were made. The reference object (S1) is designed without thermal insulation layers, the energy class „G“, and the scenario (S2) is designed in the energy class „C“, which according to the new regulations is a condition for the construction of new facilities. The study uses the Life Cycle Analysis (LCA), a methodology that is the basis for Carbon Lifecycle Analysis (LCACO2), or calculation of the carbon footprint of the facility. Construction carbon calculator, Environmental Protection Agency UK, is used to calculate the carbon footprint, and for the calculation of operational energy, the URSA Construction Physics 2 program. The study showed that the embodied carbon for the scenario (S1) is 138,40 tonnes CO2 e, with less impact on the environment. The higher values of the embodied carbon have a scenario (S2) of 148,20 tonnes CO2 e. The carbon imprint from the phase of construction, or less impact on the environment, has a scenario (S1). However, after ten years of using the facility, the scenario (S1) due to the larger carbon footprint from the operational phase becomes a scenario with a higher environmental impact, with a total carbon footprint of 186,16 tonnes CO2 e, and the scenario (S2) after ten years of use of the facility has a total carbon footprint of 163,86 tonnes CO2 e. The scenario (S1) and (S2) achieve the same values of the total carbon footprint after 3,05 years of use of the facility and (S2) has since then become a better choice from the aspect of the environment. The research has shown that the embodied carbon is neglected in the calculation of the environmental impact of the facility, as well as the average when the benefits can be expected from the application of measures for energy-efficient buildings. The research also points to the need for low-carbon thermal insulation materials to bridge the gap between the demand for the extinguishing of buildings on the one hand and the efforts to reduce greenhouse gas emissions to mitigate climate change.","PeriodicalId":10617,"journal":{"name":"Contemporary Materials","volume":"59 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76595015","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"ASSESSMENT OF THE COPPER AVAILABILITY IN THE ARABLE SOILS BY DIFFERENT EXTRACTANTS","authors":"Dijana Mihajlović, Svetlana Antić Mladenović, D. Radanović","doi":"10.7251/comen1802168m","DOIUrl":"https://doi.org/10.7251/comen1802168m","url":null,"abstract":"This paper presents an assessment of the copper availability in soil by different single extractions: DTPA (0,005 mol/L), CaCl2 (0,1 mol/L) and NH4NO3 (1 mol/L, DIN procedure). The research was carried out on 48 samples of the arable soils taken in the north-western part of the Republic of Srpska. Total Cu contents was also determined in the soil samples after the acid digestion (HNO3+H2O2). Copper contents in the extracts was determined by the atomic absorption spectrophotometry. Total soil Cu ranged from 7,7−42,9 mg/kg which corresponded to Cu-unpolluted soils. Low level of Cu mobility and availability was found in the investigated soils. In the average DTPA extracted 10,87%, CaCl2 0,31% and NH4NO3 0,44% of the total soil Cu. High statistically significant correlation (r=0,84) between the Cu contents extracted with DTPA and NH4NO3 was found, which implies that maximum allowed level of this element in the soil for the DTPA extraction procedure might be established. That conclusion has to be verified in future research including soils with high total copper content. Keywords: heavy metals, soil, extraction, pollution.","PeriodicalId":10617,"journal":{"name":"Contemporary Materials","volume":"52 4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78058079","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}