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.
إنَّ من أجلِّ العلومِ علوم العربيَّة , إذْ هيَ المَرقاة إلى فهمِ كتابِ الله , وقد بذلَ سلفُنا الصالح في هذا المجال جهودًا مضنية , وقفوا من خلالِها على أسرارِ الكثيرِ من لطائفِ هذه اللغةِ الشريفة, وتركوا لنا تراثًا ضخمًا أودعوه دقائقَ فكرهِم وعميقَ نظرهِم وهو عنوان لحضارة ِهذه الأمة وأمجادها .
أمَّا ابنُ خروف فهو من أشهر نحاة الأندلس في القرن السادس والسابع الهجريين , ومن أشهرِ شُرَّاح كتاب سيبويه ,
... Show Moreالمجال الحيوي للاقتصاد الايراني وانعكاساته على اقتصاديات دول الخليج العربي
يعد موضوع الثورات العربية من الموضوعات التي تحظى بأهمية كبيرة على المستويين الاقليمي والدولي، لذا فقد طورت مؤسسات الابحاث الدولية ومراكز صنع القرار السياسي والاستراتيجي الاطر والمفاهيم الجديدة في مجال السياسة الدولية، نظرا للتطورات التي شهدتها المنطقة العربية والتي استدعت التطرق الى مجموعة من المفاهيم النظرية ذات العلاقة الوثيقة بما هو حاصل في المنطقة العربية من تغييرات مما تطلب الامر البحث والتدقيق ومن
... Show MoreIn this study, the behavior of square helical piles models (5×5) mm2 embedded in expansive soil bed overlaying a layer of sandy soil was investigated. The sand layer 200mm thickness was compacted into four sub layers in a steel container with diameter 400mm in size. Sandy soil layer was compacted into two relative densities 40% and 80%. The bed of ثءحties 40% and 80%.The bed of o00mm in size.Sandy soil layer was compacted into two relative densities 40% and 80%.The bed of oexpansive soil 300mm thickness was compacted into six sub layers on sandy soil layer. Model tests are performed with helical pile length 350mm, 400mm and 450mm and with helix diameter 15mm and 20mm. Also, one helix and double helix were
... Show MoreFreedom of opinion is one of the freedoms that constitutions and laws have guaranteed to protect and is exercised through the media. However, this freedom must be exercised within certain limits, which include respecting a person’s right to preserve his privacy, image and reputation. Just as the media has the freedom to exercise its right to publish and express its opinion with complete frankness, it is in return obligated to respect the rights of others and avoid defaming them and violating their privacy. If the media does this, the injured party has the right to demand compensation for the damage he has suffered as a result.
الملخص - يهدف البحث الحالي الى تعرف اتجاهات مدرسي ومدرسات المدارس الثانوية نحو التربية الجنسية والتعرف على اثر متغير الجنس (ذكور، إناث) في تكوين اتجاهات تدريس التربية الجنسية في التعليم - الثانوي فضلاً عن تعرف التطبيقات التربوية للتربية الجنسية في المدارس الثانوية ، إذ ان التربية الجنسية واحدة من أهم فروع التربية في الإسلام , وهي ذات أهمية في نشر الوعي الديني والصحي والتربوي والاجتماعي والثقافي في المجتمع
... Show MoreSoftware testing is a vital part of the software development life cycle. In many cases, the system under test has more than one input making the testing efforts for every exhaustive combination impossible (i.e. the time of execution of the test case can be outrageously long). Combinatorial testing offers an alternative to exhaustive testing via considering the interaction of input values for every t-way combination between parameters. Combinatorial testing can be divided into three types which are uniform strength interaction, variable strength interaction and input-output based relation (IOR). IOR combinatorial testing only tests for the important combinations selected by the tester. Most of the researches in combinatorial testing appli
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MO Khudhair, 2020
The parliamentary election is one of the features of democratic systems that give individuals the right to participate in government and political election-making. Typically, the process of parliamentary elections received wide attention from media, as well as attention from large segments of the public because they understand the vast importance to assume political positions and associated fates of people and their destinies. Its importance comes from the fact that it allows citizens the right to participate in managing the public affairs by granting their confidence and voices to the elected president or his representatives in the parliamentary.
Media task is to emerge democratic societies, in particular, in the mission of urging p