Background: The aim of this study was to evaluate the effect of three types of light curing devices QTH, LED and Flashmax on the surface microhardness of three types of bulkfill composite resins; Filtek Bulkfill posterior composite ( 3M), Tetric Evo Ceram ( Ivoclar Vivadent) and Sonicfill composite ( Kerr) Materials and methods: Total number of 90 samples was prepared, 30 samples for each type of bulkfill composite, were divided into three main groups, group A: Filtek posterior bulkfil (3M), group B: Tetric Evo Ceram (Ivoclar Vivadent) and group C: contain Sonicfill composite (kerr). Which then divided into three subgroups (n= 10) (1) Samples cured by QTH system (2) Samples cured by LED system and (3) samples cured by Flashmax system then all samples were subjected for microhardness test (by Vickers hardness tester). The data were recorded and statistically analyzed, by the ANOVA and the Tukey test. Results: the data was subjected to statistical analysis using one way ANOVA and Tukey test, the result revealed that there was a high significant difference among the tested units with LED had high VHN values followed by QTH while Flashmax had lowest VHN values, also there was high significant difference among the tested materials in which Sonicfill composite had higher VHN value followed by Tetric EvoCeram while Filtek bulkfill posterior composite had the lowest VHN. Conclusions: microhardness of the composite resin materials depend upon energy of the curing device, time of exposure, composition of the composite material.
In this work, an investigation for the dynamic analysis of thin composite cylindrical and spherical shells is presented. The analytical solution is based upon the higher order shear deformation theory of elastic shells from which the developed equations are derived to deal with orthotropic layers. This will cover the determination of the fundamental natural frequencies and mode shapes for simply supported composites cylindrical and spherical shells.
The analytical results obtained by using the derived equations were confirmed by the finite element technique using the well known Ansys package. The results have shown a good agreement with a maximum percentage of discrepancy, which gives a confidence o
... Show MoreThe behavior of externally prestressed composite beams under short term loading has been studied. A computer program developed originally by Oukaili to evaluate curvature is modified to evaluate the deflection of prestressed composite beam under flexural load. The analysis model based on the deformation compatibility of entire structure that allows to determine the full history of strain and stress distribution along cross section depth, deflection and stress increment in the external tendons .
The evaluation of curvatures for the composite beam involves iterations for computing the strains vectors at each node at any loading stage. The stress increment determined using equations depended on the member deflection at points of connecti
The study aimed to reveal the level to which the international issues are integrated into the books of Saudi public education social studies and citizenship in the light of the principles of international education, and to know the level of continuity and integration of these issues in the books, to build a range and sequence matrix of international issues through it. The study followed the descriptive and analytical method that used the content analysis card as a tool for study when the tool achieved the necessary validity and reliability characteristics. The data of this study has been processed using the SPSS statistical program according to a set of appropriate methods of descriptive and inferential statistics.
The resu
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The study aims to identify the reality of knowledge management in decision-making in academic departments from the point of view of faculty members at Blonde University. It also aims to propose mechanisms and suggestions to improve decision-making in the academic departments of the university in light of the management of knowledge. To achieve the objectives of the study, a descriptive method was used, in which a questionnaire consisted of (40) items administered to (137) participants of the faculty members. The results of the study indicated that the reality of the application of knowledge management in the decision-making process showed a high score mean. There are no statistically significant d
... Show MoreThe aim of this research is to analyze the content of the science textbook for 7th grade Iraqi schools in the light of the educational concepts of sustainable development, the science textbook (1st edition), for the academic year 2017-2018. To this end, the researchers prepared list of issues in the light of the educational concepts of sustainable development, consisted of (13) issues, branched to (51) subissues, presented to a group of arbitrators and specialists in science curriculum and methods of teaching. The researchers analyzed the content of the 7th grade science textbook, in the light of the list that is built, the idea has been adopted as a unit of analysis. One of the most important findings is attention to neglected sub-issues o
... Show MoreThis study aimed to determine the level of spiritual intelligence among students of educational psychology course at the Jerash University. and whether this level of varies depend on the gender of the student as well as the college type. The study sample consisted of (180) male and female students of bachelor students at the University Jerash, in the second semester of academic year2014-2015. The main results of the study were that the level of spiritual
Intelligence of Jerash University students was high. More over There were no statistically significant differences at the level of significance (0.05) due to the effect of gender, college type or academic achievement
An experiment was conducted to study how SAE 50 engine oil contaminated with diesel fuel affects engine performance. The engine oil was contaminated with diesel fuel at concentrations of 0%, 1%, and 3%. The following performance characteristics were studied: brake-specific fuel consumption, brake thermal efficiency, friction power, and exhaust gas temperature. Each treatment was tested three times. The three treatments (0%, 1%, and 3%) were analyzed statistically with a one-way ANOVA model at the 5% probability level to determine if the three treatments produced significant differences in engine performance. The statistical results showed that there were significant differences in engine performance metrics among the three treatments. The 3
... Show MoreBackground: Odontogenisis is a complex process controlled by dynamic and reciprocal interactions that regulated by various molecules. Thymosin β4 is a small bioactive peptide with wide spectrum biological effects on much cell types. The present study was designed to highlight the effect of synthetic exogenous Tβ4 on developing dental tissue of the upper central teeth of rats, by histological examination and immunohistochemical evaluation of TGFβ1. Materials and method: Thirty six Albino Wister pregnant rat 18control group received intraperitoneal injection of normal saline and the others are experimental group received 50µg/300µl of Tβ4 injection. The animals were sacrificed at periods 16th and 18th day I.U.L and one day p
... Show MoreReceipt date:3/13/2021 accepted date:5/26/2021 Publication date:12/31/2021
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energy is one of the strategic resources within international politics, and this is through the existing competition between the international powers on it, and the global powers have begun to rely on interest in new areas, such as import, depending on new projects an
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