scholarly journals Creep, Hardness, and Elastic Modulus of Lingual Fixed Retainers Adhesives

Materials ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 646 ◽  
Author(s):  
Manar Hassan ◽  
Spiros Zinelis ◽  
Monika Hersberger-Zurfluh ◽  
Theodore Eliades
Keyword(s):  
Indentation Creep ◽  
Indentation Modulus ◽  
Spearman Correlation ◽  
Orthodontic Adhesives ◽  
Spearman Correlation Test ◽  
Post Hoc ◽  
One Way Anova ◽  
Fixed Retainers

The aims of this study were twofold: a) to characterize a wide array of time-independent and -dependent properties and b) to find possible correlations among the properties tested. Seven commercially available orthodontic adhesives were included in this study and ten cylindrical specimens were prepared from each material. Five specimens from each material were used for the characterization of Martens Hardness (HM), indentation modulus (EIT), and elastic index (ηIT), and the remaining five for the determination of indentation creep (CIT). Al the aforementioned properties were identified by employing an Instrumented Indentations Testing (IIT) device with a Vickers indenter. The results of HM, EIT, ηIT, and CIT were statistically analyzed by one way ANOVA and Tukey post hoc test, while the possible correlations among the aforementioned properties were determined by Spearman correlation test. Statistical significant differences were identified for all properties among the materials tested. Spearman correlation reveals that HM has a positive correlation with EIT. Both properties demonstrated a negative correlation with ηIT and CIT, while no correlation was identified between ηIT and CIT. Significant differences in the mechanical properties tested may also imply differences in their clinical behavior and efficacy.

scholarly journals Examining the Associations between Oases Soundscape Components and Walking Speed: Correlation or Causation?

2020 ◽  
Vol 12 (11) ◽  
pp. 4619
Author(s):  
Djihed Berkouk ◽  
Tallal Abdel Karim Bouzir ◽  
Luigi Maffei ◽  
Massimiliano Masullo
Keyword(s):  
Walking Speed ◽  
Significant Negative Correlation ◽  
Urban Settlements ◽  
Spearman Correlation Test ◽  
The Mean ◽  
Mode Of Transport ◽  
Post Hoc ◽  
One Way Anova

The feeling of calm and tranquillity provided by the oases of Algeria can disappear because of the outdated urbanization strategy which is based on the vehicle as a mode of transport. Walkability is one of the most adoptable sustainable strategies to reduce the negative mechanical transportation effects on the quality of life. This paper aimed to examine the correlation and the causation between oases soundscape components and walking speed. The methodology of this field study was based on an empirical approach at the urban settlements in three oases in Algeria. The correlation between walking speed and soundscape components was obtained through the use of the Spearman correlation test. A one-way ANOVA analysis was conducted to assess the effect of the soundscape components on walking speed. A post hoc Tukey test was adopted to explore the sound component that causes increased walking speed. In this study, no significant correlation was explored between the walking speed and the anthrophonical sounds. In contrast, the statistical analysis of the sound walks experience suggests a moderate and significant negative correlation between geophonical and biophonical sounds, with mean walking speed. The results showed that, the cause of the increase in the mean walking speed of the pedestrians is human sound. The findings suggest that further research is needed to focus on the long-term subjective investigation to explore the correlations and the effects between soundscape, walkability and walking speed.

scholarly journals Characterization of water sorption, solubility and filler particles of light-cured composite resins

2009 ◽  
Vol 20 (4) ◽  
pp. 314-318 ◽  
Author(s):  
Sandrine Bittencourt Berger ◽  
Alan Rodrigo Muniz Palialol ◽  
Vanessa Cavalli ◽  
Marcelo Giannini
Keyword(s):  
Water Sorption ◽  
Resin Composite ◽  
Composite Resins ◽  
Resin Matrix ◽  
Filler Size ◽  
Filler Particles ◽  
Particle Size And Shape ◽  
Post Hoc ◽  
One Way Anova

The goals of this study were to measure the water sorption (WS) and solubility (SO) of 3 composite resins containing different filler contents. Additionally, the size, shape, type and other characteristics of fillers were analyzed by scanning electron microscopy (SEM). Three composites, classified according to filler size, were selected: Filtek Supreme nanofill (3M/ESPE), Esthet-X minifill (Dentsply/Caulk) and Renamel microfill (Cosmedent Inc.). Ten disk-shaped specimens of each resin composite were made and stored in desiccators until constant mass was achieved. Specimens were then stored in water for 7 days, and the mass of each specimen was measured. The specimens were dried again and dried specimen mass determined. The WS and SO were calculated from these measurements. Data analyzed by one-way ANOVA and Tukey's post-hoc test (?=0.05). Composite filler particles were observed under SEM after removal of resin matrix by organic solvents. WS values were not significantly different among the resins; however, SO values were lower for Filtek Supreme. The materials presented differences in filler contents (e.g. particle size and shape). The composite resins had similar WS, while the SO was lower for the nanofill than for mini and microfill resins. The filler characteristics varied and were different among the materials.

scholarly journals Mechanical properties of contemporary orthodontic adhesives used for lingual fixed retention

2017 ◽  
Vol 62 (3) ◽  
Author(s):  
Iosif Sifakakis ◽  
Spiros Zinelis ◽  
Raphael Patcas ◽  
Theodore Eliades
Keyword(s):  
Mechanical Properties ◽  
Clinical Performance ◽  
Indentation Modulus ◽  
Orthodontic Adhesives ◽  
Fixed Retainers ◽  
Martens Hardness ◽  
Fixed Retention

AbstractObjective:The aim of the present study was to test the mechanical properties of different adhesives used in orthodontics for fixed retainers and to investigate their possible interrelations.Materials and methods:Specimens of six different adhesive resins were prepared: Transbond XT, Transbond LR and an experimental BPA-free orthodontic adhesive, as well as IPS Empress Direct (IPS-ED), ZNano and Accolade. The mechanical properties tested were Martens hardness (HM), indentation modulus (EResults:Significant differences were identified among all the materials tested for HM, with Transbond LR presenting the highest value. This resin presented the highest EConclusions:The materials tested demonstrated significant differences in their mechanical properties, and thus differences in their clinical performance are anticipated.

scholarly journals Indentation Modulus, Indentation Work and Creep of Metals and Alloys at the Macro-Scale Level: Experimental Insights into the Use of a Primary Vickers Hardness Standard Machine

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2912
Author(s):  
Alessandro Schiavi ◽  
Claudio Origlia ◽  
Alessandro Germak ◽  
Andrea Prato ◽  
Gianfranco Genta
Keyword(s):  
Contact Stiffness ◽  
Calculation Model ◽  
Indentation Load ◽  
Indentation Creep ◽  
Indentation Modulus ◽  
Indentation Curve ◽  
Metrological Research ◽  
Macro Scale ◽  
Applied Forces

In this work, the experimental method and the calculation model for the determination of indentation moduli, indentation work, and indentation creep of metallic materials, by means of macroscale-level forces provided by a primary hardness standard machine at the National Institute of Metrological Research (INRIM) at the at room temperature were described. Indentation moduli were accurately determined from measurements of indentation load, displacement, contact stiffness and hardness indentation imaging and from the slope of the indentation unloading curve by applying the Doerner-Nix linear model; indentation work, representing the mechanical work spent during the force application of the indentation procedure, was determined by calculating the areas under the loading–unloading indentation curve, through fitting experimental data with a polynomial law. Measurements were performed with a pyramidal indenter (Vickers test). The applied force was provided by a deadweight machine, and the related displacement was measured by a laser interferometric system. Applied forces and the occurring indentation depths were simultaneously measured: the resulting loading–unloading indentation curve was achieved. Illustrative tests were performed on metals and alloy samples. Discussion and comments on the suitability of the proposed method and analysis were reported.

scholarly journals Surface, Microstructural, and Mechanical Characterization of Prefabricated Pediatric Zirconia Crowns

Materials ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3280 ◽  
Author(s):  
Valeria Diener ◽  
Georgrios Polychronis ◽  
Juliane Erb ◽  
Spiros Zinelis ◽  
Theodore Eliades
Keyword(s):  
Surface Roughness ◽  
Clinical Performance ◽  
Indentation Modulus ◽  
Roughness Parameters ◽  
Raman Analysis ◽  
Surface Roughness Parameters ◽  
Multiple Comparison Test ◽  
Zirconia Crowns ◽  
One Way Anova

The purpose of this study was to characterize the surface roughness, the microstructure, and mechanical properties of four prefabricated zirconia pediatric crowns. Ten prefabricated crowns from four different manufacturers (Cheng Crowns Zirconia), (EZCrowns), (NuSmile ZR), and (Zirconia Pediatric Crowns) were included in this study. The surface roughness parameters (Sa, Sq, Sz, Sc, and Sv) of all samples were studied by optical profilometry and then the microstructure was studied by Raman spectroscopy. Then, all samples were embedded in epoxy resin and after metallographic polishing, the Martens hardness (HM), indentation modulus (EIT), elastic index (ηIT), Vickers hardness (HV), and fracture toughness (KIC) were identified by the Instrumented Indentation Testing (IIT). All data were statistically analyzed by a one-way ANOVA and a Tukey multiple comparison test at α = 0.05. Only the tetragonal phase of zirconia for all materials tested was identified after Raman analysis. However, statistically significant differences were found among the surface roughness parameters, HV and KIC, while no differences were allocated for HΜ, EIT, and ηΙΤ. Although the materials tested shared a similar microstructure, significant differences in surface roughness parameters HV and KIC were identified and, thus, differences in their clinical performance were anticipated.

Nanomechanical Characterization of Iron Borides in Fe-Mn-B Ternary Alloys

2020 ◽  
Vol 405 ◽  
pp. 66-71
Author(s):  
Ivana Kirkovska ◽  
Viera Homolová ◽  
Lucia Čiripová ◽  
Ivan Petryshynets
Keyword(s):  
Testing Machine ◽  
Treatment Temperature ◽  
Ternary Alloys ◽  
Indentation Modulus ◽  
Nanomechanical Properties ◽  
Arc Melting ◽  
Time Period ◽  
Diamond Indenter

Nanomechanical properties of iron borides, FeB and Fe2B were studied in Fe-Mn-B ternary alloys. The alloys were produced by arc melting method using high purity powders, which were subsequently annealed at temperature of 873 K and 1223 K, until fully equilibrated for a time period of 2160 hours and 1440 hours, respectively. Based on results obtained from experimental study and thermodynamic modeling of Fe-Mn-B system the solubility of Mn in these borides was determined. For the purpose of this study the influence of heat treatment temperature, as well as, the solubility of Mn in these borides on their nanomechanical properties is investigated. Nanomechanical properties, including determination of indentation modulus and hardness were measured using nanoindentation testing machine equipped with Berkovich type diamond indenter. The indentation process was carried out using an indentation depth controlled method, to a maximum depth of 500 nm.

scholarly journals Female Athletes And Performance-Enhancer Usage

2007 ◽  
Vol 4 (12) ◽  
Author(s):  
Barbara K. Fralinger ◽  
Genevieve Pinto-Zipp ◽  
Valerie Olson ◽  
Susan Simpkins
Keyword(s):  
Female Athletes ◽  
School Level ◽  
Spearman Correlation ◽  
High School Level ◽  
Chi Square ◽  
Significance Level ◽  
Prevention Education ◽  
Athletic Coaches ◽  
Post Hoc ◽  
One Way Anova

The purpose of this study was to develop a knowledge base on factors associated with performance-enhancer usage among female athletes at the high school level in order to identify markers for a future prevention-education program.  The study used a pretest-only, between-subjects Likert Scale survey to rank the importance of internal and external pressures that may lead to performance-enhancer usage among this population.  Subjects included 122 female athletes from top-ranked sport programs at 7 New Jersey high schools.  Descriptive and quantitative statistics were used to analyze the data at a p<.05 significance level.  The Chi Square Test of Homogeneity, Spearman Correlation Coefficient, Kruskal-Wallis One-Way ANOVA, and Scheffé Post-Hoc Test were used to analyze associations between the nine survey issues and five levels of importance.  Results indicated that subjects rated the pressure to win and self-induced competitive pressures as the two most important factors in leading to performance-enhancer usage.  Chi-Square results showed significant differences in the level of importance for each of the nine issues presented, while the Spearman Correlation revealed several correlations among certain issues.  The Kruskal-Wallis One-Way ANOVA showed significant differences in ranks when data were grouped by school and sport.  Post-Hoc analysis supported findings of the Kruskal-Wallis One-Way ANOVA.  This study provided descriptive and quantitative data that added to the existing research.  The findings may be used by health educators and athletic coaches for performance-enhancer prevention-education programs.

Characterization of Impressed Current Technique to Model Corrosion of Reinforcement in Concrete

2020 ◽  
Vol 11 (1) ◽  
pp. 93-99
Author(s):  
Abu Zakir Morshed ◽  
Sheikh Shakib ◽  
Tanzim Jahin
Keyword(s):  
Immersion Time ◽  
Chloride Content ◽  
Engineering Science ◽  
Coastal Regions ◽  
Faraday’S Law ◽  
Current Technique ◽  
Corrosion Cell ◽  
Impressed Current

Corrosion of reinforcement is an important durability concern for the structures exposed to coastal regions. Since corrosion of reinforcement involves long periods of time, impressed current technique is usually used to accelerate the corrosion of reinforcement in laboratories. Characterization of impressed current technique was the main focus of this research,which involved determination of optimum chloride content and minimum immersion time of specimens for which the application of Faraday’s law could be efficient. To obtain optimum chloride content, the electrolytes in the corrosion cell were prepared similar to that of concrete pore solutions. Concrete prisms of 200 mm by 200 mm by 300 mm were used to determine the minimum immersion time for saturation. It was found that the optimum chloride content was 35 gm/L and the minimum immersion time for saturation was 140 hours. Accounting the results, a modified expression based on Faraday’s law was proposed to calculate weight loss due to corrosion. Journal of Engineering Science 11(1), 2020, 93-99

The Determination of Sense via Deleuze and Blanchot: Paradoxes of the Habitual, the Immemorial, and the Eternal Return

2008 ◽  
Vol 2 (2) ◽  
pp. 155-177 ◽  
Author(s):  
Eugene Brently Young
Keyword(s):  
Eternal Return

Eternal return is the paradox that accounts for the interplay between difference and repetition, a dynamic at the heart of Deleuze's philosophy, and Blanchot's approach to this paradox, even and especially through what it elides, further illuminates it. Deleuze draws on Blanchot's characterisations of difference, forgetting, and the unlivable to depict the ‘sense’ produced via eternal return, which, for Blanchot, is where repetition implicates or ‘carries’ pure difference. However, for Deleuze, difference and the unlivable are also developed by the living repetition or ‘contraction’ of habit, which results in his distinctive characterization of ‘force’, ‘levity’, and sense in eternal return.

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