Abstract: Objectives: To investigate the effect of temperature elevation on the bonding strength of resin cement to the zirconia ceramic using fractional CO2 laser. Background: Fractional CO2 laser is an effective surface treatment of zirconia ceramic, as it increases the bonding strength of zirconia to resin cement. Methods: Thirty sintered zirconia discs (10 mm diameter, 2 mm thickness) were prepared and divided to three groups (N=10) and five diffident pulse durations were used in each group (0.1, 0.5, 1, 5 and 10 ms). Group A was treated with 10 W power setting, group B with 20 W and group C with 30 W. During laser irradiation, temperature elevation measurement was recorded for each specimen. Luting cement was bonded to the treated zirconia surfaces and cured for 30 seconds. Shear bond strength was evaluated by a testing machine (universal) with bond failure mode determination. Results: The lowest temperature elevation measurement of the irradiated specimen which gave maximum shear bond strength was about 1.6±0.3 Ċ higher than ambient room temperature (27±0.2 ºC). Apparent micromechanical irregularities were seen in the treated samples and cracks formation with increased pulse duration and power setting were also observed. Conclusions: The temperature elevation is a vital factor in the surface roughness of zirconia ceramic with fractional CO2 laser irradiation and the lowest temperature elevation at best shear bond strength of zirconia ceramic to the resin cement is satisfied with the shorter pulse duration of 0.1 millisecond.
Abstract
The Classical Normal Linear Regression Model Based on Several hypotheses, one of them is Heteroscedasticity as it is known that the wing of least squares method (OLS), under the existence of these two problems make the estimators, lose their desirable properties, in addition the statistical inference becomes unaccepted table. According that we put tow alternative, the first one is (Generalized Least Square) Which is denoted by (GLS), and the second alternative is to (Robust covariance matrix estimation) the estimated parameters method(OLS), and that the way (GLS) method neat and certified, if the capabilities (Efficient) and the statistical inference Thread on the basis of an acceptable
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The analytical results of the failure types of six limestone islands in the Ha Long bay of Vietnam have been identified. The calculated results of safety factor for 03 plane failure blocks lie within 0.9 and 2, have high potential failure. The analytical results have been also simulated these islands in three-dimensional space and have been also analyzed their potential failure on the fracture surfaces. The results obtained in this paper have important significance for planning and development of the Ha Long bay area, as World Natural Heritage, Quang Ninh province of Vietnam.
Factors affecting consumer consumerism Iraqi The research aims to shed light on the factors influencing consumer consumerism Iraqi and arranged in terms of the degree of importance in influencing through poll sample, which amounted to (85) members of the shoppers of electrical goods in the markets of Baghdad, Questionnaire has been used as a tool head to collect data and information from the sample surveyed and their answers were analyzed using factor analysis and test ( ), and The research group was the most prominent
Examination is a form of tax audits which have been done by tax examiner rests with the General Commission for Taxes is responsible for determining the extent to which the amounts subject to tax provided by the holders of admissions with the laws and regulations, taxes. So the tax-examination is the major means of tax administration to make sure the fact that tax revenues generated from the imposition of taxes different kinds of direct and indirect search result, the importance of the role played by the (Department of Control and Internal Audit / Audit Division in charge) in charge of auditing the accounts, which may be Maclvoha clung to their accounts and access to the tax base acceptable to the expensive and fin
... Show Moreهدف البحث الى التعرف على القياس المحاسبي عن التنمية المستدامة، وبيان العلاقة بين القياس المحاسبي عن التنمية المستدامة وتقارير الابلاغ المالي، وكذلك بيان أثر القياس المحاسبي عن الاستدامة على تقارير الإبلاغ المالي في الشركة العامة للمنتوجات الغازية، وقد تمحورت مشكلة البحث في بيان أثر عناصر المحاسبة عن التنمية المستدامة، البيئية، والاجتماعية، والاقتصادية، على تقارير الإبلاغ المالي في الشركة العامة للمنتو
... Show Moreيتناول البحث الاخلال المسبق واثره في تنفيذ الالتزام العقدي على حساب المدين ـ دراسة مقارنة في القوانين المدنية والقانون الانكليزي
The article is final after making all the modifications. 2,259 / 5,000 يهدف البحث إلى قياس وتحليل الفجوة بين الواقع الفعلي لبنود التخطيط والدعم وفق المواصفة (IATF16949:2016) في مصنع البطاريات أحد مصانع الشركة العامة لصناعة وتجهيز السيارات، وكذلك التعرف على نقاط القوة والضعف لبنود التخطيط والدعم وفق المواصفة محل البحث. ينطلق البحث من حاجة الشركة العامة لصناعة وتجهيز السيارات إلى إتباع المعايير العالمية في صناعة السيارات والمنتجات المرتبطة بها،
... Show MoreThe income tax that is imposed on the salaries & wages of employees in the governmental fields &the companies of public & mixed sectors by direct deduction in a manner similar to the employees in the private sector according to the order NO.49 of 2004 issued by Coalition Provision Authority in Iraq , from the validity of Security Council resolutions NO. 1482 of 2003, &1511 of 2004.  
... Show MoreProblem: Find dimensions of the problem by answering the following question: what the effect of using the Six Thinking Hats strategy to acquire the historical concepts and retain the fourth-grade students in the subject of literary history. Importance of research: current research is gaining importance in many ways, including: 1. Keep pace with the new in the field of education and modern educational strategies. 2. Shed light on innovative education strategy in the teaching of history, which is one of the materials that need to renew the tragedy of instruction methods for students. 3. Out of the monotony and traditional way of teaching to a method and a new strategy to develop the teacher and the learners thinking skills through various
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