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Marie-thérèse Oberthür - One of the best experts on this subject based on the ideXlab platform.
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Effect of sonic-activated resin composites on the repair of aged substrates: an in vitro investigation
Clinical Oral Investigations, 2014Co-Authors: Nicoleta Ilie, Marie-thérèse OberthürAbstract:ObjectivesThis study aimed to evaluate whether sonic-activated resin-based composites (RBCs) used as repair materials might improve the repair bond strength of aged RBC substrates.Materials and methodsFive RBCs were repaired by themselves and by all other materials. The repair was applied with and without sonic activation, resulting in 50 material application technique combinations ( n = 15) and 750 specimens. The cohesive strength of the five materials was used as control ( n = 15). Substrates were aged for 8 weeks in distilled water at 37 °C, roughened, cleaned with phosphoric acid, and repaired by using a silane primer and an adhesive as intermediate agents. The repair bond strength was assessed in a shear test. The modulus of elasticity ( E ) of the five RBCs was additionally evaluated in a three-point bending test.ResultsResults were compared using one- and multiple-way analyses of variance and Tukey’s honestly significant difference post hoc test ( α = 0.05), partial eta-square statistics, Pearson’s correlation, and Weibull’s analysis. No significant effect of sonic activation on the repair material was found in any material combination. The repair strength was 35.4–90.9 % of the cohesive strength of the original composites. E varied between 4.1 GPa (CLEARFIL MAJESTY Esthetic) and 9.7 GPa (CLEARFIL MAJESTY Posterior). The strongest influence on the shear bond strength was performed by E _repair ( η ^2 _P = 0.167), whereas the effect of E _substrate was significant but low ( η ^2 _P = 0.098). None of these Parameters influenced the reliability of the repaired specimens (the Weibull Parameter, m ). The fracture pattern was mainly cohesive (93.3 %) in the control group and predominantly adhesive (89.2 %) in the repaired specimens.ConclusionsExcept for the material with the highest modulus of elasticity used as a substrate material, it was not detrimental to combine different RBCs in terms of repair.Clinical relevanceIf a substrate material is unknown, the recommendation for repairing would be in favor of a material with a high modulus of elasticity.
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Effect of sonic-activated resin composites on the repair of aged substrates: an in vitro investigation
Clinical Oral Investigations, 2014Co-Authors: Nicoleta Ilie, Marie-thérèse OberthürAbstract:ObjectivesThis study aimed to evaluate whether sonic-activated resin-based composites (RBCs) used as repair materials might improve the repair bond strength of aged RBC substrates.Materials and methodsFive RBCs were repaired by themselves and by all other materials. The repair was applied with and without sonic activation, resulting in 50 material application technique combinations ( n = 15) and 750 specimens. The cohesive strength of the five materials was used as control ( n = 15). Substrates were aged for 8 weeks in distilled water at 37 °C, roughened, cleaned with phosphoric acid, and repaired by using a silane primer and an adhesive as intermediate agents. The repair bond strength was assessed in a shear test. The modulus of elasticity ( E ) of the five RBCs was additionally evaluated in a three-point bending test.ResultsResults were compared using one- and multiple-way analyses of variance and Tukey’s honestly significant difference post hoc test ( α = 0.05), partial eta-square statistics, Pearson’s correlation, and Weibull’s analysis. No significant effect of sonic activation on the repair material was found in any material combination. The repair strength was 35.4–90.9 % of the cohesive strength of the original composites. E varied between 4.1 GPa (CLEARFIL MAJESTY Esthetic) and 9.7 GPa (CLEARFIL MAJESTY Posterior). The strongest influence on the shear bond strength was performed by E _repair ( η ^2 _P = 0.167), whereas the effect of E _substrate was significant but low ( η ^2 _P = 0.098). None of these Parameters influenced the reliability of the repaired specimens (the Weibull Parameter, m ). The fracture pattern was mainly cohesive (93.3 %) in the control group and predominantly adhesive (89.2 %) in the repaired specimens.ConclusionsExcept for the material with the highest modulus of elasticity used as a substrate material, it was not detrimental to combine different RBCs in terms of repair.Clinical relevanceIf a substrate material is unknown, the recommendation for repairing would be in favor of a material with a high modulus of elasticity.
Nicoleta Ilie - One of the best experts on this subject based on the ideXlab platform.
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Effect of sonic-activated resin composites on the repair of aged substrates: an in vitro investigation
Clinical Oral Investigations, 2014Co-Authors: Nicoleta Ilie, Marie-thérèse OberthürAbstract:ObjectivesThis study aimed to evaluate whether sonic-activated resin-based composites (RBCs) used as repair materials might improve the repair bond strength of aged RBC substrates.Materials and methodsFive RBCs were repaired by themselves and by all other materials. The repair was applied with and without sonic activation, resulting in 50 material application technique combinations ( n = 15) and 750 specimens. The cohesive strength of the five materials was used as control ( n = 15). Substrates were aged for 8 weeks in distilled water at 37 °C, roughened, cleaned with phosphoric acid, and repaired by using a silane primer and an adhesive as intermediate agents. The repair bond strength was assessed in a shear test. The modulus of elasticity ( E ) of the five RBCs was additionally evaluated in a three-point bending test.ResultsResults were compared using one- and multiple-way analyses of variance and Tukey’s honestly significant difference post hoc test ( α = 0.05), partial eta-square statistics, Pearson’s correlation, and Weibull’s analysis. No significant effect of sonic activation on the repair material was found in any material combination. The repair strength was 35.4–90.9 % of the cohesive strength of the original composites. E varied between 4.1 GPa (CLEARFIL MAJESTY Esthetic) and 9.7 GPa (CLEARFIL MAJESTY Posterior). The strongest influence on the shear bond strength was performed by E _repair ( η ^2 _P = 0.167), whereas the effect of E _substrate was significant but low ( η ^2 _P = 0.098). None of these Parameters influenced the reliability of the repaired specimens (the Weibull Parameter, m ). The fracture pattern was mainly cohesive (93.3 %) in the control group and predominantly adhesive (89.2 %) in the repaired specimens.ConclusionsExcept for the material with the highest modulus of elasticity used as a substrate material, it was not detrimental to combine different RBCs in terms of repair.Clinical relevanceIf a substrate material is unknown, the recommendation for repairing would be in favor of a material with a high modulus of elasticity.
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Effect of sonic-activated resin composites on the repair of aged substrates: an in vitro investigation
Clinical Oral Investigations, 2014Co-Authors: Nicoleta Ilie, Marie-thérèse OberthürAbstract:ObjectivesThis study aimed to evaluate whether sonic-activated resin-based composites (RBCs) used as repair materials might improve the repair bond strength of aged RBC substrates.Materials and methodsFive RBCs were repaired by themselves and by all other materials. The repair was applied with and without sonic activation, resulting in 50 material application technique combinations ( n = 15) and 750 specimens. The cohesive strength of the five materials was used as control ( n = 15). Substrates were aged for 8 weeks in distilled water at 37 °C, roughened, cleaned with phosphoric acid, and repaired by using a silane primer and an adhesive as intermediate agents. The repair bond strength was assessed in a shear test. The modulus of elasticity ( E ) of the five RBCs was additionally evaluated in a three-point bending test.ResultsResults were compared using one- and multiple-way analyses of variance and Tukey’s honestly significant difference post hoc test ( α = 0.05), partial eta-square statistics, Pearson’s correlation, and Weibull’s analysis. No significant effect of sonic activation on the repair material was found in any material combination. The repair strength was 35.4–90.9 % of the cohesive strength of the original composites. E varied between 4.1 GPa (CLEARFIL MAJESTY Esthetic) and 9.7 GPa (CLEARFIL MAJESTY Posterior). The strongest influence on the shear bond strength was performed by E _repair ( η ^2 _P = 0.167), whereas the effect of E _substrate was significant but low ( η ^2 _P = 0.098). None of these Parameters influenced the reliability of the repaired specimens (the Weibull Parameter, m ). The fracture pattern was mainly cohesive (93.3 %) in the control group and predominantly adhesive (89.2 %) in the repaired specimens.ConclusionsExcept for the material with the highest modulus of elasticity used as a substrate material, it was not detrimental to combine different RBCs in terms of repair.Clinical relevanceIf a substrate material is unknown, the recommendation for repairing would be in favor of a material with a high modulus of elasticity.
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effect of gloss and heat on the mechanical behaviour of a glass carbomer cement
Journal of Dentistry, 2013Co-Authors: Ulrike Mennehapp, Nicoleta IlieAbstract:Abstract Objectives The effect of gloss and heat on the mechanical behaviour of a recently launched glass carbomer cement (GCP, GCP dental) was evaluated and compared with resin-modified glass ionomer cements (Fuji II LC, GC and Photac Fil Quick Aplicap, 3M ESPE). Methods 120 bar-shaped specimens ( n = 20) were produced, maintained in distilled water at 37 °C and tested after one week. The GCP specimens were cured with and without heat application and with and without gloss. The flexural strength and modulus of elasticity in flexural test as well as the micro-mechanical properties (Vickers Hardness, indentation modulus, creep) of the top and bottom surface were evaluated. The amount and size of the fillers, voids and cracks were compared using a light and a scanning electron microscope. Results In the flexural test, the resin-modified glass ionomer cements performed significantly better than GCP. Fuji II LC and Photac Fil (Weibull Parameter: 17.7 and 14.3) proved superior reliability in the flexural test compared to GCP (1.4–2.6). The highest Vickers Hardness and lowest creep were achieved by GCP, whereas Fuji II LC reached the highest indentation modulus. The results of this study proved that relationships exist between the compositions, microstructures and mechanical properties of the cements. Conclusions Heat treatment and gloss application did not influence the mechanical properties of GCP. The mechanical properties were basically influenced by the type of cement and its microstructure. Clinical significance Considering the measured mechanical properties, there is no need of using gloss or heat when restoring teeth with GCP.
Steven J Smith - One of the best experts on this subject based on the ideXlab platform.
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spatial and temporal patterns of global onshore wind speed distribution
Environmental Research Letters, 2013Co-Authors: Yuyu Zhou, Steven J SmithAbstract:Wind power, a renewable energy source, can play an important role in electrical energy generation. Information regarding wind energy potential is important both for energy related modeling and for decision-making in the policy community. While wind speed datasets with high spatial and temporal resolution are often ultimately used for detailed planning, simpler assumptions are often used in analysis work. An accurate representation of the wind speed frequency distribution is needed in order to properly characterize wind energy potential. Using a power density method, this study estimated global variation in wind Parameters as fitted to a Weibull density function using NCEP/climate forecast system reanalysis (CFSR) data over land areas. The Weibull distribution performs well in fitting the time series wind speed data at most locations according to R2, root mean square error, and power density error. The wind speed frequency distribution, as represented by the Weibull k Parameter, exhibits a large amount of spatial variation, a regionally varying amount of seasonal variation, and relatively low decadal variation. We also analyzed the potential error in wind power estimation when a commonly assumed Rayleigh distribution (Weibull k = 2) is used. We find that the assumption of the same Weibull Parameter across large regions can result in non-negligible errors. While large-scale wind speed data are often presented in the form of mean wind speeds, these results highlight the need to also provide information on the wind speed frequency distribution.
S Rehman - One of the best experts on this subject based on the ideXlab platform.
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techno economic assessment of wind power potential of hawke s bay using Weibull Parameter a review
Energy Strategy Reviews, 2019Co-Authors: Zahid Hussain Hulio, Wei Jiang, S RehmanAbstract:Abstract The purpose of this work is to assess the wind characteristics and wind power potential of Hawke's bay site. The wind Parameters of site have been used to calculate the wind power density, annual energy yield, and capacity factors at 30, 60 and 80 m. The five different methods including empirical, maximum likelihood modified maximum likelihood, energy pattern, and graphical methods are used to obtain the Weibull Parameters. The exactness of the five methods is obtained by correlation coefficient and root mean square error values between the measurements and the estimates. The results of all methods including empirical, maximum likelihood, modified maximum likelihood and energy pattern observed to be better fit except graphical method. Also economic assessment per kWh of energy has been carried out. The site specific wind shear coefficient is found to be 0.18 using wind speed values at 30, 60 and 80 m. The annual mean wind speeds were 6.05, 5.84 and 5.40 m/s at 80, 60 and 30 m heights with corresponding standard deviations of 2.32, 2.24 and 2.01. The mean wind power densities were 307.5, 231.5 and 184.0 W/m2 at respective heights. According to the economic assessment, the wind turbine C (2300 kW) is able to produce power at the lowest price of US$ 0.056/kWh. The results are showing the appropriateness of methodology for assessing the wind speed and economic assessment at the lowest price of energy.
Xiaozhong Liao - One of the best experts on this subject based on the ideXlab platform.
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evaluation of wind power production prospective and Weibull Parameter estimation methods for babaurband sindh pakistan
Energy Conversion and Management, 2014Co-Authors: Shahnawaz Farhan Khahro, Kavita Tabbassum, Amir Mahmood Soomro, Lei Dong, Xiaozhong LiaoAbstract:Abstract Pakistan is currently experiencing an acute shortage of energy and urgently needs new sources of affordable energy that could alleviate the misery of the energy starved masses. At present the government is increasing not only the conventional energy sources like hydel and thermal but also focusing on the immense potential of renewable energy sources like; solar, wind, biogas, waste-to-energy etc. The recent economic crisis worldwide, global warming and climate change have also emphasized the need for utilizing economic feasible energy sources having lowest carbon emissions. Wind energy, with its sustainability and low environmental impact, is highly prominent. The aim of this paper is to explore the wind power production prospective of one of the sites in south region of Pakistan. It is worth mentioning here that this type of detailed analysis is hardly done for any location in Pakistan. Wind power densities and frequency distributions of wind speed at four different altitudes along with estimated wind power expected to be generated through commercial wind turbines is calculated. Analysis and comparison of 5 numerical methods is presented in this paper to determine the Weibull scale and shape Parameters for the available wind data. The yearly mean wind speed of the considered site is 6.712 m/s and has power density of 310 W/m2 at 80 m height with high power density during April to August (highest in May with wind speed 9.595 m/s and power density 732 W/m2). Economic evaluation, to exemplify feasibility of installing wind turbines, is also done. The estimated cost of per kWh of electricity from wind is calculated as 0.0263 US$/kWh. Thus the candidate site is recommended for some small stand-alone systems as well as for wind farm.
