Back ground: This in vitro study was carried out to investigate the effect of post space regions (coronal, middle and apical), Time and the mode of polymerization (dual, self-cured) of the cements used on the bond strength between translucent fiber post and root dentin by using push-out test. Materials and Methods: Forty eight extracted mandibular first premolars (single root) were instrumented with ProTaper Universal system files (for hand use) and obturated with gutta percha for ProTaper and AH26® root canal sealer following the manufacturer instructions, after 24 hours post space was prepared using FRC postec® plus drills no.3 creating 8 mm depth post space. The prepared samples were randomly divided into two main groups (24 samples each) according to the used cement (Group M, self-cure, Multilink N) and (Group R, dual cure, Relyx U100). Then each group was subdivided into three groups (each group contains 8 samples) according to the testing time after cementation. (g M1: push out test after 24 hour of cementation with Multilink N), (g M2: push out test after one week of cementation with Multilink N),(g M3: push out test after two weeks of cementation with Multilink N), (g R1: push out test after 24 hours of cementation with RelyxU100), (g R2: push-out test after one week of cementation with RelyxU100), (g R3: push out test after two weeks of cementation with RelyxU100). After cementation and incubation each root was sectioned horizontally into 3 slices (2 mm in thickness) represent the coronal, middle and apical regions of the post space. Push out bond strength test was performed and measured using a universal testing machine (Tinius-Olsen) at across head speed of 0.5 mm/min. Results: showed that regarding the root region, the bond strength values increased significantly apical to coronal region in both tested cements. For the effect of time, the bond strength values also significantly increased with time for both tested cements. For mode of polymerization, the self-cured resin cement Multilink N showed higher bond strength values. Conclusion: the retention of fiber post was affected by root region, mode of polymerization of the cements used and time elapsed after cementation of the post.
Traction force and power requirement when performing primary tillage occupy the minds of almost farmers, this field research had aim to determine and calculate the pulling force of the most commonly used moldboard and chisel plows, the research conducted in silt clay loam for chisel and moldboard plows as the main factor, two depths of tillage 18 and 25 cm as a second factor and three speeds of tractor 2.55, 4.30 and 6.15 km.h-1 as a third factor. Moldboard plow recorded least traction force 7.550 kN, drawbar power 11.583 hp, power losses due to slippage 1.088 hp, power on the rear axle of the tractor 15.770 hp and brake horse power 17.495 hp. Chisel plow recorded best traction efficiency 76.217 % and total traction efficiency 68.659 %. Dep
... Show MoreThis research aims to suggest formulas to estimate carry-over effects with two-period change-over design, and then, all other effects in the analysis of variance of this design, and find the efficiency of the two-period change-over design relative to another design (say, completely randomized design).
Two unsupervised classifiers for optimum multithreshold are presented; fast Otsu and k-means. The unparametric methods produce an efficient procedure to separate the regions (classes) by select optimum levels, either on the gray levels of image histogram (as Otsu classifier), or on the gray levels of image intensities(as k-mean classifier), which are represent threshold values of the classes. In order to compare between the experimental results of these classifiers, the computation time is recorded and the needed iterations for k-means classifier to converge with optimum classes centers. The variation in the recorded computation time for k-means classifier is discussed.
An annular two-phase, steady and unsteady, flow model in which a conductingfluid flow under the action of magnetic field is concavely. Two models arepresented, in the model one; the magnetic field is perpendicular to the long side ofthe channel, while in the model two is perpendicular to the short side. Also, westudy, to some extent the single-phase liquid flow.It is found that the motion and heat transfer equations are controlled by differentdimensionless parameters namely, Reynolds, Hartmann, Prandtl, and Poiseuilleparameters. The Laplace transform technique is used to solve each of the motion andheat transfer equations. The effects of each of dimensionless parameters upon thevelocity and heat transfer is analyzed.A comprehensive study fo
... Show MoreIn this paper, the theoretical cross section in pre-equilibrium nuclear reaction has been studied for the reaction at energy 22.4 MeV. Ericson’s formula of partial level density PLD and their corrections (William’s correction and spin correction) have been substituted in the theoretical cross section and compared with the experimental data for nucleus. It has been found that the theoretical cross section with one-component PLD from Ericson’s formula when doesn’t agree with the experimental value and when . There is little agreement only at the high value of energy range with the experimental cross section. The theoretical cross section that depends on the one-component William's formula and on-component corrected to spi
... Show MoreThe study aims to develop the awareness of the criteria for judging electronic educational materials among students of educational qualification at Dhofar University over spreading the Corona pandemic through a program based on mini-educational units. The study was applied to (18) students studying Teaching diploma at Dhofar University for the academic year 2020-2021, and their number. They were chosen intentionally. The study resulted in reaching a list of criteria for judging electronic educational materials, roughly (18) criteria in the selection themes and (15) criteria in the use theme. The level of awareness of the sample members with the criteria for selecting and using electronic educational materials and the effectiveness of the
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The research study about the empowerment as an independent variable, in which details include (training and improvement, incentives, information sharing, trust, and delegation), has also focused on the performance of the service organization as a dependent variable in all dimensions which include (improve work efficiency, building the core competencies, focus on the beneficiary of the service, increasing the feeling of satisfaction of the employees, and the organizational support commitment). The research has been based on the opinions of a chosen sample of 75 service officers of the Ministry of Interior who work at the General Directorate of Traffic. The research problem has been identified by t
... Show MoreThe study aimed to explore the effectiveness of using rational judgment strategy in teaching science to develop scientific thinking for second-grade students. The researcher utilized the quasi-experimental approach based on (the pre/post designing) of two groups: experimental and control. As for tools: a test of scientific thinking prepared by the researcher that proved its verification of their validity and reliability. The test applied on a random sample of (66) students, divided into two groups: (34) experimental, and (32) control. The results showed that the experimental group outperformed the control group in the post-application of the scientific thinking test, In each skill separately, and in the total skills. The study recommende
... Show MoreIn Iraq, government contributions to the public companies have become a very important aspect which contributes to the survival and sustainability of these institutions as it consider one of the main sources of funding, if not it consider the basis of funding.
According to the vital roles assigned to these institutions to follow up, which usually include important activities in the national economy, the research focused on studying the field reality of the method used in evaluating the stock of total production and purchases of goods for the purpose of selling the strategic commodities of the General Company for Grain Trade. As a result, the aim of this study came to came to highlight&n
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