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.
تتناول هذه الورقة البحثية مسرحية عشتار في بغداد (2003) لرشا فاضل. وتسلط الضوء على العديد من المواضيع الاجتماعية والسياسية المثيرة للجدل. ويمكن اعتبار مسرحية فاضل بمثابة صدمة شخصية وثقافية. وهي تسلط الضوء على بعض الحقائق القاسية المرتبطة بالجيش الأمريكي واحتلاله للعراق بالاضافة الى انها تولد صوتًا جديدًا للشعب العراقي المغيب صوته بسبب الاستعمار. يتم فحص المسرحية في ضوء بعض دراسات الصدمات الأدبية. وتعتبر نظ
... Show Moren Segmented Optical Telescope (NGST) with hexagonal segment of spherical primary mirror can provide a 3 arc minutes field of view. Extremely Large Telescopes (ELT) in the 100m dimension would have such unprecedented scientific effectiveness that their construction would constitute a milestone comparable to that of the invention of the telescope itself and provide a truly revolutionary insight into the universe. The scientific case and the conceptual feasibility of giant filled aperture telescopes was our interested. Investigating the requirements of these imply for possible technical options in the case of a 100m telescope. For this telescope the considerable interest is the correction of the optical aberrations for the coming wavefront, th
... Show MoreThis research is intended to high light the uses of political content in foreign Arabic / speaking websites, such as “ CNN “ and” Euro News“, The research problem stems from the main question: What is the nature of the use of the websites in the political content provided through them? A set of sub-questions that give the research aspects and aims to achieve a set of objectives , including the identification of topics that included , the political content provided through , the sample sites during the time period for analysis and determine that the study uses descriptive research based on the discovery of the researcher, describing it accurately and defining the relations between the components.
The research conducted the des
The study of the current study (to the concept of the aesthetics of the imagined in Iraqi ceramics (Saad Shaker) as a model for the study, as it represents one of the most important plastic arts that was characterized by renewal and modernity and its possession of many creative potentials. And by glazing, and the use of color oxides or by the creative act of borrowing the cultural heritage to turn it into a vocal piece of art for creation and innovation.
The researcher (Saad Shaker), being one of the first potters, his ceramics had a lot of development and semantic transmission, studying and decoding codes written in ceramic works. The current study included the theoretical framework in the first research (the philosophical beauty) an
In the marsh of the vast technical development and its reflections on the public life in all of its forms man lives in the shade of this and that and he is in a disprate need to took attentively at his reality through a new artistic vision which the imagination gives it , its value, from this point we find the designers pay great efforts in creating advertising designs that creation and fertile imagination are consisting one unit, and through her flying study on the reality of employing the creative imagination in the designing of printed advertisements, the researcher submitted her questions where some of which are: -What are the requirements of employing the creative imagination in the designing process? And -What are the machineries o
... Show MoreMedina was according to its importance and religious status the basis for the emergence and emergence of historical schools, it is the emigration of the Prophet and the presence of the companions , and it was natural to shine the beginnings of historical codification, whether in the process of collecting and codification of the verses of the Koran or the Hadith, and once the pillars settled Islam in the Islamic areas until the Muslims began to go to the city to provide a broader knowledge of the Islamic religion and everything related to the biography of the Prophet and the significance and actions, and in return took the jurists and preservation and readers of the companions and followers to undertake the task of teaching in work
... Show MoreThe research risk of flooding on six water basins located in the eastern part of the western plateau, reached total area of the basin (22,998.9 km 2), has reached all the Basin area (basin to time 7056.1 km2 basin by 3585 km 2, Bath Alheiazi 6404 km 2, Abu beasts 544.1 km2 basin Abu Shannan 144.6 km 2, Bath Valley Faraj 5265.1 km 2), where it was specifically spatial degree of this risk by studying some of the hydrological basin transactions directly related to operations spate runoff study area and the occurrence of flood risks on the surface of ponds.
The objective of this study is to enable the role of modern and advanced computerized information systems. The model or mechanism should be developed by collecting the necessary information about the taxpayers and the sources of the taxpayers' income, on the basis of which the accuracy of the inventory process will be adopted. In addition to studies related to computerized information systems and showing their importance to the tax institution. To achieve the objectives of the study and to answer its questions, the researcher relied on collecting data and information on the subject on the literature and previous studies The secondary sources, which also formed the theoretical framework of the study, were obtained either as a practical fr
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