Influence of Different Curing Modes on Polymerization Behavior and Mechanical Properties of Dual-Cured Provisional Resins

2017 ◽  
Vol 42 (5) ◽  
pp. 526-536 ◽  
Author(s):  
S Shibasaki ◽  
T Takamizawa ◽  
T Suzuki ◽  
K Nojiri ◽  
A Tsujimoto ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Expansion ◽  
Filler Content ◽  
Linear Thermal Expansion ◽  
The Self ◽  
Inorganic Filler ◽  
Significant Difference ◽  
Polymerization Behavior ◽  
Light Curing ◽  
The Mean

SUMMARY This study determined the influence of curing mode on polymerization behavior and mechanical properties of dual-cured provisional resins. Three dual-cured bisacryl-based provisional resins were used: Tempsmart (TS; GC Corp), Luxatemp Automix Solar (LX; DMG Chemisch Pharmazeutishe Fabrik GmbH), and Integrity Multi·Cure (IG; Dentsply Caulk). A self-cured bisacryl-based provisional resin, Protemp Plus (PP; 3M ESPE) and a conventional poly(methyl methacrylate) (PMMA) provisional resin, Unifast III (UF; GC Corp) were used as controls. The inorganic filler content and coefficients of linear thermal expansion of the test materials were measured. Six specimens of each material were used to determine the flexural strength, elastic modulus, and resilience. The changes in ultrasound velocity during polymerization were measured. The average inorganic filler contents of the provisional resins, apart from UF, ranged from 24.4 to 39.3 wt%. The highest inorganic filler content was determined for LX, whereas TS showed the lowest value among the tested materials. The average coefficients of thermal expansion of the tested provisional resins ranged from 77.3 to 107.7 (×10−6/°C). TS and IG showed significantly lower thermal expansions than the other tested provisional resins. The mean flexural strengths of the provisional resins ranged from 70.4 to 122.6 MPa, the mean elastic moduli ranged from 1.8 to 3.7 GPa, and the mean resilience of the provisional resins ranged from 1.1 to 2.3 MJ/mm3, respectively. Dual-cured provisional resins showed significantly higher flexural strengths than the PMMA resin. However, in all cases, the light-curing mode showed significantly higher flexural strengths than the self-curing mode. In the initial polymerization phase, dual-cured resins in the light-curing mode showed a rapid increase in the speed of sound (V) during light irradiation, followed by a slower increase. Conversely, the dual-cured resins in the self-curing mode showed a slower initial increase, followed by a rapid increase. Although no significant difference in V was observed between 10 and 15 minutes in the light-curing mode of all tested dual-cured resins, a significantly higher V value was obtained at 15 minutes than at 10 minutes in the self-curing modes for LX and IG. Regardless of the curing mode, tested dual-cured provisional resins showed superior mechanical properties than the conventional PMMA provisional resin. However, dual-cured provisional resin flexural properties and polymerization behavior were affected by the curing mode. This study indicated that the light-curing mode might be recommended for all dual-cured provisional resins because of the enhancement of their mechanical properties and reduction of chair time.

Comparison of the effect of self-care education in a disaster with two student-centered and family-centered approaches to self-care in students

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
Ali Eskandari ◽  
Minoo Motaghi
Keyword(s):  
Self Care ◽  
The Self ◽  
Care Group ◽  
Control Group ◽  
Student Centered ◽  
Care Education ◽  
Significant Difference ◽  
Quasi Experimental ◽  
The Mean ◽  
Family Centered

Abstract Objectives The purpose of this research was to compare the effect of self-care education in disasters with two student-centered and family-centered approaches to self-care in students of the Red Crescent Societies in the city of Lenjan in 2017. Methods One hundred and fifty individuals were selected by random sampling from 270 people. The research instrument was a questionnaire. The questionnaire was approved by the opinion of supervisors and other experts. The present research is a quasi-experimental study. The covariance analysis was used to determine the difference between the two groups in the experimental and control groups and the effect of educational intervention. All of the above steps were performed using the SPSS 23 statistical program. Results The results indicate that there is a significant difference between the two groups in self-care through the student-centered approach. The mean of the self-care group with a family-centered approach (21.72) was more than the mean of the control group in this variable (16.61). Moreover, the mean of the self-care group’s education with family-centered approaches (42.61) was more than the mean of self-care education h in a disaster with a student-centered approach (31.23). Conclusion According to the results of this study, it can be concluded that there is a significant difference between self-care education with two student-centered and family-based approaches to self-care in students, and a family-centered approach has better outcomes.

Constructing the Self-Ideal: A Note on Spence and Helmreich's Personality Attributes Questionnaire

1994 ◽  
Vol 75 (2) ◽  
pp. 993-994 ◽  
Author(s):  
John G. Rechtien
Keyword(s):  
The Self ◽  
Men And Women ◽  
Self Image ◽  
Significant Difference ◽  
The Mean

On the first and last days of the semester, 28 literature students (8 men, 20 women) rated themselves according to Spence and Helmreich's 1978 Personality Attributes Questionnaire. As expected, no significant differences between men and women appeared in comparisons of the scores of the dualistic Instrumental (Masculine or M) and Expressive (Feminine or F) traits from the first and second administrations. However, the combined scores of men and women for the bipolar M-F traits showed a significant difference between their initial responses and their second responses to the M-F traits. Further, men had significantly higher mean scores than did women for the first and second administrations. The mean scores on the second administration suggest that men had reinforced their initial stereotypical self-image of themselves, while women had appropriated manifestations of dominance in their self-ideal.

Thermal Expansion of Silver Iodide

1973 ◽  
Vol 28 (9) ◽  
pp. 1539-1541 ◽  
Author(s):  
Bert Jansson ◽  
Carl-Axel Sjöblom
Keyword(s):  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Silver Iodide ◽  
Linear Thermal Expansion Coefficient ◽  
Linear Thermal Expansion ◽  
Thermal Expansivity ◽  
Fused Quartz ◽  
The Mean ◽  
Polycrystalline Silver

The linear thermal expansivity of polycrystalline silver iodide has been measured with a "Fused-Quartz Tube" apparatus in the temperature range 170 - 500 °C, the mean linear thermal expansion coefficient beingαt180=(2.607 + 0.00182 t) 10-5 (°C-1).An irregular change in the thermal expansivity was found close to 432 °C where an order-disorder transition has been reported.

scholarly journals Mechanical test suitable for detection of bug-damage wheat grains abstract

2018 ◽  
Vol 64 (No. 2) ◽  
pp. 77-84
Author(s):  
Basati Zahra ◽  
Rasekh Mansour ◽  
Abbaspour-Gilandeh Yousef
Keyword(s):  
Mechanical Properties ◽  
Mechanical Test ◽  
Compressive Loading ◽  
Mean Value ◽  
Elastic Coefficient ◽  
Wheat Grains ◽  
Significant Difference ◽  
Rupture Energy ◽  
The Mean ◽  
Four Levels

Considering the fact that the presence of bug-damaged wheat in the bulk results in a decrease of the flour quality and its final product, which is bread, it is necessary to differentiate the bug-damaged wheat grains from the healthy ones. Therefore, the present study investigated the mechanical properties of bug-damaged and healthy wheat grains of the Azar cultivar. By making use of these mechanical properties, it would be possible to provide a more precise texture identification of the bug-damaged wheat grains compared to the healthy ones. In this study, the mechanical properties (rupture energy, toughness and apparent elastic coefficient) were determined under compressive loading, with four levels of loading velocity (5, 15, 25 and 35 mm.min<sup>–1</sup>) and four levels of moisture content (9, 11.5, 14 and 16.5% wet basis) in both bug-damaged and healthy wheat grains. Due to the significant difference in the mean value of apparent elastic coefficient between the bug-damaged grains (74.779 MPa) and the healthy ones (289.071 MPa), this parameter can be employed as the most appropriate factor to distinguish the bug-damaged wheat grains from the healthy ones. 

Effect of Filler Content and Waiting time Before Light-Curing on Mechanical Properties of Dual-Cured Cement

2020 ◽  
Vol 2 (1) ◽  
pp. 45-52
Author(s):  
Ana C. de Assunção Oliveira ◽  
Sandro Griza ◽  
Rafael R. de Moraes ◽  
André L. Faria-e-Silva
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Flexural Strength ◽  
Waiting Time ◽  
Filler Content ◽  
Bending Test ◽  
Resin Cements ◽  
Three Point Bending ◽  
Light Curing ◽  
Curing Procedure

Objective:: To investigate the effect of filler content and the time spent before light-curing on mechanical properties of dual-cured cement. Methods:: Experimental dual-cured resin cements were formulated with 60, 65 or 68wt% of filler. The viscosity of experimental cement was measured using a digital viscometer. Bar-shaped specimens (25 x 2 x 2 mm) were fabricated, while the light-curing was started immediately or 5 minutes after the insertion of cement into the mold (n = 7). A three-point bending test was performed and the values of flexural strength and elastic modulus were measured. The Vickers hardness of fractured specimens was measured on the surface of the cement. Data from viscosity were submitted to oneway ANOVA, while the data from mechanical properties were analyzed by two-way ANOVA. All pair-wise comparisons were performed using Tukey’s test (α = 0.05). Results:: The experimental cement with 68wt% of filler showed the highest viscosity and those with 60wt% showed the the lowest viscosity. Irrespective of the time spent before light-curing, the cement with 65wt% of filler presented the highest values of flexural strength and elastic modulus. The addition of 60wt% of filler resulted in the lowest elastic modulus, while 68wt% of filler resulted in lowest flexural strength. Regarding the hardness, the cement with 68wt% of filler showed the highest values, while there was no difference between 60 and 65wt% of filler. Conclusion:: Filler content affected the mechanical properties of the experimental cement and this effect did not depend on the waiting time before the light-curing procedure.

scholarly journals Structures and mechanical properties of talc and carbon black reinforced high density polyethylene composites : Effects of organic and inorganic fillers

2013 ◽  
Vol 37 (1) ◽  
pp. 11-20 ◽  
Author(s):  
Nasrin Parvin ◽  
Md Samir Ullah ◽  
Md Forhad Mina ◽  
Md Abdul Gafur
Keyword(s):  
Mechanical Properties ◽  
Carbon Black ◽  
High Density Polyethylene ◽  
Filler Content ◽  
High Density ◽  
Inorganic Filler ◽  
X Ray Diffraction ◽  
Compression Moulding ◽  
X Ray ◽  
Academy Of Sciences

Organic filler like carbon black (CB) and inorganic filler like talc (T) with 0, 0.5, 1.0, 10, 20 and 40 wt% were separately loaded in high density polyethylene (HDPE) by the extrusion moulding method at 160oC. Then, different sets of filler loaded HDPE composites were prepared using the compression moulding technique, and their structures and mechanical properties were characterized. The pure HDPE sample, as examined by the X-ray diffraction (XRD) technique, showed orthorhombic structure, which did not change either with filler types or with their concentration. The only variations found in the structure are the changes of crystallinity and crystallized size that depend on both types of fillers and their concentrations. Incorporation of CB in HDPE emphasizes the crystallinity and crystallized size more than that of T. The tensile strength of the composite decreases with the increase of both types of fillers, and this decrease is explained on the basis of Nielson model, which basically describes a poor interaction between filler and HDPE matrix. An increase of Young’s modulus of 350% is observed with the increasing CB and T contents, representing an increase of the stiffness in the materials. Flexural strength increased with the increase of CB content but decreased with the increase of talc content. Although the microhardness was observed to increase with both types of fillers, the hardness value was 80% higher for CB loaded-composites than that of T at 40 wt% filler content. These findings strongly indicate that the compatibility of HDPE is better with organic filler than with inorganic one. DOI: http://dx.doi.org/10.3329/jbas.v37i1.15675 Journal of Bangladesh Academy of Sciences, Vol. 37, No. 1, 11-20, 2013

scholarly journals Mechanical Testing of Recycled HDPE Extruded Hollow Section

2020 ◽  
Vol 4 (2) ◽  
pp. 112-121
Author(s):  
Greg Wheatley ◽  
Rendage Sachini Sandeepa Chandrasiri
Keyword(s):  
Thermal Expansion ◽  
Yield Strength ◽  
Ultimate Strength ◽  
Modulus Of Elasticity ◽  
Coefficient Of Thermal Expansion ◽  
Linear Thermal Expansion ◽  
Environmental Benefits ◽  
Hollow Section ◽  
Significant Difference ◽  
Recycled Hdpe

High density polyethylene (HDPE) is a thermoplastic polymer which is classified as one of the highly consumed types of plastics. One major advantage of thermoplastic materials is their ability of recycling and reprocessing which will bring considerable economicand environmental benefits. The present paper, therefore, endeavours to explore the practical possibility of using recycled HDPE hollow section as a replacement of virgin HDPE made by the extrusion process. The main focus of the study was to evaluate the mechanical performance of the recycled HDPE and compare the results with virgin or non-recycled HDPE.  The modulus of elasticity, tensile yield and ultimate strength, compressive yield and ultimate strength, flexural yield and ultimate strength and the coefficient of thermal expansion were the main parameters to be checked against the respective mechanical properties. Thus, pursuant to the rsults, it was found out  that the modulus of elasticity and the tensile yield strength are lower in recycled HDPE compared to the non-recycled HDPE. However, there is no significant difference between the recycled and non-recycled HDPE for the tensile ultimate strength, compressive yield strength and compressive ultimate strength. The flexural yield strength and flexural ultimate strength properties of the recycled HDPE proved to be superior to those of the non-recycled HDPE. The coefficient of linear thermal expansion of the recycled HDPE sample was 130 μm/(m.°C) and that for the non-recycled HDPE was 142 μm/(m.°C).

scholarly journals SELF ESTEEM OF SECONDARY SCHOOL THARU STUDENTS OF WEST CHAMPARAN

2021 ◽  
Vol 9 (02) ◽  
pp. 354-358
Author(s):  
Ignatius Topno ◽  
Keyword(s):  
Secondary School ◽  
Nuclear Family ◽  
Self Esteem ◽  
The Self ◽  
Male And Female ◽  
Significant Difference ◽  
Self Worth ◽  
The Mean ◽  
The Difference ◽  
And Behavior

SelfEsteemis a central construct in clinical, developmental, personality, and social psychology.Self Esteem can be defined as an individuals judgment of his or her self-worth (Rosenberg 1965). Self Esteem is generally considered the evaluative component of the self-concept, a broader representation of the self that includes cognitive and behavioral aspects as well as evaluative or affective ones (Tomaka&Blascovich, 1991). Self Esteem creates self-image (Judy and Arin 2004). People with high self esteem take risks more easily than those with low self Esteem. Self Esteem, that is contingent on success and competence, triggers fundamentally different habitual thought and behavior patterns than contingent self Esteem, that involves seeking compensation from emotional support and acceptance. These behaviors and attitudes have in recent studies been linked to distinctive patterns of coping with social threats and differential health outcomes.It is an extremely popular construct within psychology, and has been related to virtually every other psychological concept or domain, including personality, behavioral, cognitive, and clinical concepts. It can influence life in myriad ways, from academic and professional success to relationships and mental health. On the above criteria in mind the researcher desired using mean, standard deviation t test to study the difference between the mean scores of male and female, Private and Government job holders children, age of students, type of family and finally the standard of students in their self-esteem of secondary school Tharu children of West Champaran . The result declared that there is no significant difference between the mean scores of male and female,Private and government Job holders children, single and nuclear family, whereas there is a significant difference between the mean scores of less than 14 and above 14 years and IXth and Xth Standard secondary school Tharu students in their self-esteem.

scholarly journals One versus two adjacent interdigital neuroma excision: a patient outcome study

2021 ◽  
Vol 15 (3) ◽  
pp. 236-240
Author(s):  
Kefilwe Boineelo Benjamin ◽  
Nikiforos Saragas ◽  
Paulo Ferrão
Keyword(s):  
Patient Outcome ◽  
Patient Satisfaction ◽  
Retrospective Study ◽  
The Self ◽  
Outcome Study ◽  
Foot And Ankle ◽  
Level Of Evidence ◽  
Significant Difference ◽  
The Mean ◽  
Good For

Objective: We aimed to evaluate patient satisfaction after surgery for both single and two adjacent neuromas. Methods: We reviewed the data of patients treated operatively for interdigital neuromas between 2003 and 2016. We interviewed them and administered the Self-Reported Foot and Ankle Score questionnaire. Patient scores were then analyzed categorically, and variation between groups was assessed. Results: Sixty-two patients were available for review. Thirty-one patients had a single interdigital neuroma excised and 31 had two adjacente interdigital neuromas excised. Twenty-eight of the 31 (90%) patients with a single neuroma had good or excellent results while 23 (74.2%) of those with adjacent neuromas had similar outcomes. One patient with a single neuroma had a poor result while four patients with adjacent neuromas had poor results. The mean score was 41 (excellent) for patients with a single interdigital neuroma and 37 (good) for those with adjacent neuromas (p=0.473). The majority of patients in both groups would undergo surgery again. Conclusion: We found no statistically significant difference in outcomes of patients who undergo surgery for either single or two adjacent interdigital neuromas. General patient satisfaction is good and/or excellent post excision. Level of Evidence II; Prognostic Studies; Retrospective Study.

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