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.
The aim of the present research is to know the following :
What are the Science and technology, society and environment issues (S.T.S.E) which included in the content of the chemistry Book third grade intermediate ?
And to achieve the objective of search The two researchers has prepares a list of science and technology, society and environment issues (STSE) consisted of (9) key issues namely ( Air quality and the atmosphere, sustainable development, water security, health and preventive security, mineral resources investment, pollution of various kinds, energy, food industry, production of weapons technology ) and from which (70) sub-issues emerge, Arbitrators competent agreement has been received . Then, the two re
... Show Moreان المشكلة البحثية تتحدد في ان المهام والادوات التي تملكها السلطة التنفيذية، من الصعوبة تركها من دون رقابة، والرقابة والتقييد ياتي من اطراف عدة، واهمها: السلطة التشريعية، فالبرلمان في العراق منح اختصاصات للنظر في اعمال واداء السلطة التنفيذية بما يضمن تقيدها بالدستور الاتحادي. والهدف من هذا البحث هو الاشارة الى اهمية الاختصاصات الممنوحة للبرلمان العراقي، بما يضمن التاسيس لدولة القانون، اي وجود مرجعية قانو
... Show Moreلطالما تُبنى قرارات الاستثمار في أسهم الشركات المدرجة في أسواق البورصة على خلفية المؤشرات المالية لها والتي عادةً مايتم إصدارها في نشرات سنوية معتمدة من قبل تلك الاسواق، إذ غالباً مايقوم المحللون الماليون بالاستعانه بها لتوجيه المستثمرين لإتخاذ القرارات المتعلقة بشراء أو بيع أسهم هذه الشركات.
لكنه على الرغم من ذلك تحدث إنهيارات كبيرة في أسواق البورصة بين فترة وآخرى وخير مثال على ذلك ما أ
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This research aims to investigate the impact of a training program for teachers of chemistry according to the strategies for both sides of the brain together in academic achievement for their students, the sample consisted of a 12 teachers of both genders who are teaching chemistry for the students of the fifth scientific secondary schools of the General Directorate for the Education in Garmiyan/Sulaymaniyah governorate, Iraqi Kurdistan region, where five teachers of them randomly selected to involve the training program, and seven teachers did not participate in the proposed training program, where a sample of students was selected for each group of teachers about 147 male and female students for teachers of the experiment
... Show Moreتعد الحروب أحد أخطر التهديدات في النظام العالمي; فهي تعد خرقا للقوانين والاعراف الدولية، والمبادئ الإنسانية، و من هنا تأتي دراسة أهمية موضوعنا الموسوم بـ (الاحتمالات المستقبلية للحرب الروسية – الأوكرانية و مدى انعكاسها على أمن دول شرق أوربا بعد العام 2022 ،)اذ يرتكز هذا البحث على دراسة واستعراض الاحتمالات المستقبلية )السيناريوهات) للحرب الروسية – الأوكرانية، والتي شنت من الحكومة الروسية بقيادة الرئيس الروس
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Sözlü Türk halk edebiyatı ürünleri içinde önemli yere sahip olan türlerden biri de atasözleridir. Atasözleri, nesilden nesile halk ağzında dolaĢan, kimin söylediği bilinmeyen, birtakım gerçekleri kısa ve öz bir Ģekilde ifade eden sözlerdir. Türk atasözleri Orhun Abideleri‟nde ilk kez karĢımıza çıkmakla birlikte, Uygur dönemi yazıtlarında ve özellikle Dîvânü Lûgati‟t Türk‟te geniĢ yer bulmuĢtur. Dilin anlatım ve kullanım imkânlarını geliĢtiren atasözlerine, dünyanın bütün dillerinde rastlanabilir. Bunun için, söyleyiĢte güzel, anlatımda güçlü, kavramda önemli unsurlar içeren kalıplaĢmıĢ sözler halinde bulunurlar. Bu çalıĢmada, Türk halk edebiyatında atas
This study deals with the field of acieving the manuscripts of Islamic sciences by the great Imam ibn Kamal Pasha, but the mentioned book requires a great effort to explain what it contains of sciences, and to appear what it has contained
مشكلة البحث :
تعد الادارة الجامعية عاملا مهما واساسيا في اكمال البناء المعرفي لشخصية الطالب الجامعي لما يمثله من قدرة على قيادة العملية التربوية والتعليمية والوصول بها الى تحقيق اهدافها . وطالما كانت هذه الادارة ممثلة ابتداء من رئاسات الاقسام ووصولا الى اعلى الهرم الاداري في الجامعة مهمة في تحقيق الاهداف العلمية والتربوية فان اختيار الاشخاص للقيام بمهامها تاخذ جانبا كبيرا ومهما وذلك للاثر
... Show MoreThe undimensionality hypothesis which is item response theory depend it is unable in some of measurement situations because there are many dimensions which are affect of the response, so as the researches reached to expand this hypothesis to construct a new one which is multidimensional, and many of theories are pointed to the concept of meaning of life is multidimensionality, so this research aimed to construct the scale of meaning of life as the student's perception according with Multidimensional Item Response Model and this research adopt Wong's theory 1998 which point to the meaning of life consist of (7) dimensions. The research tool contains (49) items distributed at dimensions of meaning of life. Sample of statistical ana
... Show MoreLevels of the Factors structure of the scale Costa and McCrae applied to the Iraqi environment
A previously_prepared Iraqi version of Costa & McCrae the big five factor has been adminstered to (200) students at University of Baghdad in order to investigate the hypothesized differences in factor structures between the original version of Costa & McCrae test and the Iraqi version.
To verify the hypothesized differences , the minieigen value. Factors , maximum likelihood criteria of determining the number of factors , and varimax and promax as methods of rotation have been used.
The
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