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 traction property is one of the important mechanical properties, especially the rotary parts which are subjected to constant and variable loads There are many methods used to improve this property, and the shoot peening by metal balls is considered the most critical one. the study focuses on this characteristic of steel CK35 used in many engineering applications as the rotating shafts and railway This study shows that the fatigue strength is improved by14% after shoot peening with metal balls. The study includs the rehabilitation of damaged samples as a result of fatigue corrosion. The standard solution adopted was 36% MgCl2 with a 30 days immersion period. These samples has been improved by 6% after it decreased by18% d
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Carrying strength is one of the important physical capabilities in the field of competitive sports, which affects the success of the sports training process and helps players to continue to perform skillfully, physically and tactically for as long as possible, and the capacity for endurance varies depending on the type of sports activities, it may sometimes be very short. And with a high level of intensity, such as gymnastics and wrestling movements, and it may be long, and with a medium level of intensity, as in basketball, football and other games. The research community represents a sample of Baghdad players for teams (football, basketball, handball, volleyball, wrestling, weightlifting) and for the sports season (2017-2018 AD) for ages
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Abstract
Indeed, being busy with the understanding of religion is the best sort of worship that the almighty God has given each period of time a number of scholars and wise men. They receive what has been passed down to them from their great ancestors, and those who are willing to learn will learn, their students preserve their knowledge through teaching and writing. Thus, the scholars were pioneers in this field due to the value and importance of their knowledge. They have strived in learning, explaining, and writing new subjects.
One of those scholars is sheikh (Abdulrahman Al-Penjweni) who passed away 1319 AH in one of the villages of the city of Sulaimani in Iraq. He was one of the wisest scholars, a br
... Show MoreThe current research aims to identify the effect of Baska style on students’ achievement and the creative thinking in material rhetoric and the application of students for fifth grade literary. To achieve the study objectives, the researcher has designed an achievement test to measure group of students in the fifth grade literary in material application. The researcher chose a sample of 40 female students from Khansa School for Girls in Baghdad for the academic year (2014 - 2015), he applied the test on an exploratory sample consisted of 30 female students from the research community. The study resulted in being no statistically significant difference at the level of significance (0.05) between the mean scores of the experimental group
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Background: Osteoporosis is a systemic skeletal disorder that has an impact on general health, dental health and salivary composition. The mineralization of teeth happens simultaneously with that of the skeleton, but if mineral metabolism is disrupted, tooth failures will resemble those that affect bone tissue. Vitamin D plays a key role in bone and tooth mineralization.
Objective: to evaluate the impact of osteoporosis on teeth decay in relation to salivary vitamin D among menopause in Baghdad city.
Subjects and Methods: This study was cross sectional study. The study group consists of
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Although its wide utilization in microbial cultures, the one factor-at-a-time method, failed to find the true optimum, this is due to the interaction between optimized parameters which is not taken into account. Therefore, in order to find the true optimum conditions, it is necessary to repeat the one factor-at-a-time method in many sequential experimental runs, which is extremely time-consuming and expensive for many variables. This work is an attempt to enhance bioactive yellow pigment production by Streptomyces thinghirensis based on a statistical design. The yellow pigment demonstrated inhibitory effects against Escherichia coli and Staphylococcus aureus and was characterized by UV-vis spectroscopy which showed lambda maximum of
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The research aims to develop the general performance and improve the level of activity of private insurance companies in line with the current progress of the country. Besides, Evaluating financial performance to diagnose weaknesses and strengths in sample research companies and then developing appropriate solutions. The deviation in the financial performance of the research sample was revealed by measuring the various accounts of the company. The research sample included five companies in the private insurance sector listed in the Iraqi Stock Exchange Market, which represent the private insurance sector. The research concluded that the added economic value is a broad concept that goes beyond the traditional performance evaluation process a
... Show MoreCare and attention to the structure in the sixties of the last century replaced the mark, and if the structure of Ms. pampered in research and studies, it has become the mark is also a spoiled lady .. But the relationship between the structure and the mark was not a break and break, but the relationship of integration, His themes are structural analysis, and these are intellectual themes that can not be surpassed in contemporary research, especially since semiotics have emerged from the linguistic inflection.
We have tried to distinguish between text and speech, which is a daunting task, as it seems that whenever the difference between them is clear and clear, we come back to wonder whether the text is the same discourse, and is
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