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.
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Advancements and modernizations introduced into the educational and pedagogical systems have significantly impacted teaching processes and how subjects are presented and explained to students. The focus has shifted to how learners interact with the material they need to learn, providing sufficient opportunities for learning and granting them freedom and self-confidence to achieve learning objectives. The research problem stems from the researcher's experience as a lecturer in the College of Physical Education and Sports Science, particularly in teaching basketball. She observed that some instructors were deficient in using the most effective teaching methods. The researcher formulated her research question based on these observations: "What
... Show MoreThe auditor plays a key role in economic life because of the confidence his report adds to the audited financial statements. In applying the various stages of the audit process, the auditor must maintain a high moral level that determines his type of commitment in his professional behavior before God first, And to the society at last in a way that supports its independence. On this basis, the aim of the research is to identify the threats that affect the independence of the auditor. To achieve the objective of the research, the hypothesis that there is a statistically significant relationship between the threats facing the auditor and his professional independence was formulated. In the light of testing the hypotheses of research it was
... Show Moreان استمرارية دول منطقة الشرق الاوسط بالسعي نحو حيازة القدرات النووية تعد في حد ذاتها كابحاً او محدداً اساسياً حيال انشاء منطقة خالية من اسلحة الدمار الشامل، فضلا عن عدم توافر الضمانات الكفيلة لا رساء مقومات الامن فيما بين دول الشرق الاوسط، مما ينعكس بالمحصلة سلبا على مقتربات الامن الاقليمي والدولي لمنطقة الشرق الاوسط، وبما يؤدي بطبيعة الحال الى ان تنتهج دولها سياسات امنية متعارضة ازاء بعضها البعض ضمن اطار
... Show MoreTransparency is considered as one of the modern administrational terms which started to be largely used in the last period, because of its political, economical, social and cultural dimensions. As well as, its administrational dimension that helps to create a work environment marked by order and flawless from wrong practices and Transparency provides credibility to the sides that pursue it in their practices, till it became a mean of distinction. The choice of the subject of the research ((Transparency and its effect on quality of message announcement of Insurance company)), which aims to measure the effect of Transparency on the announcement message quality of Insurance services. Came in the time when many countries tend to depend on se
... Show MoreCorpus linguistics is a methodology in studying language through corpus-based research. It differs from a traditional approach in studying a language (prescriptive approach) in its insistence on the systematic study of authentic examples of language in use (descriptive approach).A “corpus” is a large body of machine-readable structurally collected naturally occurring linguistic data, either written texts or a transcription of recorded speech, which can be used as a starting-point of linguistic description or as a means of verifying hypotheses about a language. In the past decade, interest has grown tremendously in the use of language corpora for language education. The ways in which corpora have been employed in language pedago
... Show Moreان الاستثمار في راس المال البشري االمتمثل بالقوى العاملة مرتبط بالتنمية المستدامة وان الانسان هو الثروة الحقيقية للأمم. والانفاق على التعليم تكون له انعكاسات ايجابية على الواقع الاقتصادي ووالاجتماعي والسياسي. ومن اجل تحديد العوامل المؤثرة على القوى العاملة تم تحليل العلاقة السببية (كرانجر) بين القوى العاملة و عدد الخريجين والسكان وعدد الجامعات والناتج المحلي الاجمالي والانفاق على االتعليم العالي ، بوجو
... Show MoreThe no parity problem causes determining is the most interesting case by doctors and researchers in this filed, because it helps them to pre-discovering of it, from this point the important of this paper is came, which tries to determine the priority causes and its fluency, thus it helps doctors and researchers to determine the problem and it’s fluency of increase or decrease the active sperm which fluencies of peregrinating. We use the censored regression (Tobit) model to analyze the data that contains 150 observations may by useful to whom it concern.
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The importance of the topic lies in explaining the extent of Sheikh Abdul Qadir Al-Kilani’s interest in social and scientific life in Baghdad
ان الحرب الاوكرانية والتصعيد الروسي ضد اوكرانيا يرتبط بصراع جيوسياسي واسع على مناطق القوة والنفوذ والمجالات الحيوية، وتنافس تجاري دولي محتدم على النفط والغاز ومسارات خطوط التجارة الدولية بين اقطاب استراتيجية دولية تتجاوز اوكرانيا، إذ يأتي الصراع ضمن اطار التحولات الدولية الراهنة والصراعات على مناطق القوة والنفوذ الجيوستراتيجي والمكانة الدولية بين القوى الدولية المؤثرة في القضايا والشؤون الدولية، ويبق
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