Background: This study was formulated to compare the effect of 5%hydrofluoric acid in comparison to 37%phosphoric acid with and without the application of silane on bond strength of composite to porcelain. Materials and Methods: Specimen preparation was divided in to two phases, metal-disks fabrication (8mm-diameter and 4mm-thickness) and ceramic veneering. Thirty two specimens were prepared, sandblasted with 50 μm aluminum oxide, and divided into four groups of eight samples. Groups I and III were etched with 37%phosphoric acid while groups II and IV were etched with 5%hydrofluoric acid; and groups I and II were silaneted while groups III and IV were not. Heliobond, and resin composite were applied to each specimen using a plastic transparent split mold (4mm- diameter and 4mm-height). Specimens were stored in distilled water for 24 hours then thermocycled for 100 cycles. Shear bond strength was determined by a Zwick universal machine at a cross-head speed 5 mm/minute. Results: Mean shear bond strength values were 21.02(group I), 23.31(group II), 4.00(group III), and 18.60(group IV). Paired-t revealed that specimens treated with 5%hydrofluoric acid were significantly higher than those treated with 37%phosphoric acid regardless the use of silane. The use of silane dramatically enhanced the bond strength of composite resin to porcelain for both acids. All specimens treated with 37%phosphoric acid without silane showed adhesive failure, while those treated with 5%hydrofluoric acid showed mostly cohesive failure within ceramic. Conclusion: Silane improved the shear bond strength of composite to ceramic, and hydrofluoric acid performed greater bond strength compared to phosphoric acid.
The influence of different thickness (500, 1000, 1500, and 2000) nm on the electrical conductivity and Hall effect measurements have been investigated on the films of copper indium gallium selenide CuIn1-xGaxSe2 (CIGS) for x= 0.6.The films were produced using thermal evaporation technique on glass substrates at R.T from (CIGS) alloy. The electrical conductivity (σ), the activation energies (Ea1, Ea2), Hall mobility and the carrier concentration are investigated and calculated as function of thickness. All films contain two types of transport mechanisms of free carriers, and increases films thickness was fond to increase the electrical cAnductivity whereas the activation energy (Ea) would vary with films thickness. Hall Effect analysis resu
... Show MoreThis paper aims to decide the best parameter estimation methods for the parameters of the Gumbel type-I distribution under the type-II censorship scheme. For this purpose, classical and Bayesian parameter estimation procedures are considered. The maximum likelihood estimators are used for the classical parameter estimation procedure. The asymptotic distributions of these estimators are also derived. It is not possible to obtain explicit solutions of Bayesian estimators. Therefore, Markov Chain Monte Carlo, and Lindley techniques are taken into account to estimate the unknown parameters. In Bayesian analysis, it is very important to determine an appropriate combination of a prior distribution and a loss function. Therefore, two different
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In this study, six square reinforced concrete flat plates with dimensions of (1500×1500×100) mm were tested under a concentrated load applied on a column located at the center of the slabs. One of these slabs was the control specimen, whereas, in the others, steel angles (steel collars) were used, fixed at the connection region between the slab and the column to investigate the effect of the presence of these collars on punching shear strength. Five thicknesses were used (4, 5, 6, 8, 10mm) with constant legs of angles (75×75) mm of the steel collars to investigate the effects on the punching shear resistance with respect to the control slab. The results of the experimental study show that the punching shear resistance increased b
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The social networking sites have brought about fundamental changes and a qualitative shift in the marketing industry and its strategies. The Iraqi ministries have used this site i.e. Facebook to spread and disseminate values in order to consolidate it in Iraqi society which has witnessed many changes in all aspects of life.
The researcher studies the pages of both ministries to know the values contained in the publications of the pages of these two ministries, the quality of grooming as well as the forms in which these values are marketed.
The researcher uses a survey method and content analysis for the publications of these two pages during the study period starting from January 1, 2
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The stress(Y) – strength(X) model reliability Bayesian estimation which defines life of a component with strength X and stress Y (the component fails if and only if at any time the applied stress is greater than its strength) has been studied, then the reliability; R=P(Y<X), can be considered as a measure of the component performance. In this paper, a Bayesian analysis has been considered for R when the two variables X and Y are independent Weibull random variables with common parameter α in order to study the effect of each of the two different scale parameters β and λ; respectively, using three different [weighted, quadratic and entropy] loss functions under two different prior functions [Gamma and extension of Jeffery
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لمعرفة مدى تأثير تمرينات مهارية وفق تقنية تركيز للتفكير الجاني على الدقة الحركة وتعلم هجمة الإيقاف بالغطس للطلاب في سلاح الشيش استخدمت الباحثتان المنهج التجريبي على عينة من طلاب المرحلة الثالثة بكلية التربية البدنية وعلوم الرياضة –جامعة ديالى والتي بلغت (30) طالباً موزعين على مجموعتين التجريبية والضابطة وبعد إكمال اجراءات البحث وتطبيق الاختبارات القبلية وتنفيذ التمرينات والاختبار البعدي ومعالجة الب
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in this worl three types of complexed phenolic resins were prepared using various additives such as and improving the aim of this work higher mechanical properties this work is done
ABSTRACT Background: One of the major problems of all ceramic restorations is their probable fracture against the occlusal forces. The objective of this in vitro study was to evaluate the effect of two gingival finishing lines (90°shoulder and deep chamfer) on the fracture resistance of full contour CAD/CAM and heat press all-ceramic crowns. Materials and Methods: Thirty two maxillary first premolars were prepared to receive full contour CAD/CAM (zolid) and heat press (Cergo Kiss) ceramic crowns using a special paralleling device (Parallel-A-Prep). The teeth were divided into four groups according to the type of finishing line prepared. Each crown was cemented to its corresponding tooth using self-etch, self-adhesive dual cure resin ceme
... Show MoreThe study was planned to evaluate the effect of adding Guanidinoacetic acid in some characteristics of the sperm of the rams. This study was conducted in the animal field of the Animal Production Department / Faculty of Agricultural Engineering Sciences / University of Baghdad, for the period from 5/8/2018 to 28/2/2019. In this experiment, 3 rams were used at the age of 2-2.5 years and weighed 50-54 kg. The semen was collected early in the morning and once a week and the semen was pooled to remove the individual differences. The treatments were divided: GAA-free control group, treatment T1 (0.05 mg / 100 ml GAA), T2 treatment (0.1 mg / 100 ml GAA) and T3 treatment (0.2 mg / 100 ml GAA). The results of the study showed a significant decrease
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It is believed that culture plays an important role in the ELF classroom activities (Al- Mutawa, & Kilani, 1989:87). It is important for the teacher to recognize potential negative (culturally based) perceptions of their learners. In Iraq, for instance, it is not. Uncommon to meet silent expressionless students that arc supposedly English language learners. It is possible for the beginner to interpret this negatively as a lack of interest in the study of English. This interpretation may play a harmful role in the classroom methodology. An instructor has to be intercultural competent to be an effective teacher. It will be more effective if the instructor adopts a consistent style of instruction to allow learners to adapt within the bounds of
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