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 existence of succession system has appeared in Arab Islamic state after the death of the prophet Mohammed (peace be upon God and peace), So there was caliphate, then the Umayyad dynasty in Syria , until 132 AH , the date o the emergence of the Abbasid state adopted a system ministry formally , hafs bin sulaiman ( Abu salamah Khallal ) was the first minister emerged on the political scene. He was killed at the time of the first Abbasid caliph , Abu Albbas , incest 132-136 who had put Khalid bin barmak as a minister instead of Hafs bin Sulaiman . During the reign of AL-Mansur 136-158 , there was an importance and a place for the ministry , despite of AL-Mansur strength personality that covered on his ministers personalities
... Show MoreThis research aims to identify the factors effecting the investigation of insurance fraud from the perspective of the National Insurance Company employees, by analyzing the study variables and make recommendations on how to enhance the company and employees performance, and to achieve the objectives of the study and test hypotheses a questionnaire was designed after referring to the international standards and the 1969 Iraqi punishment law, and it was answered by 20 employees that were approved for the purposes of this research and analysis.
The study found that lack of employee training was a strong factor, while the supervisory staff and operational procedures was a weak one.
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... Show MoreWhat linguists mentioned about the infinitive and its use in the linguistic levels of speech, whether with its verb, or what was mentioned in the difference between the infinitive and the noun of the source, are matters that are related to the phenomenon of hearing in speech, a need necessitated by the nature of the linguistic law and its connection with the Arabic dialects, which proceeded in the linguistic levels to form Phenomenon inherent in the use of the source and the name of the source
Highlights the role of taxes in being a major source of funding sources internal economic and social development, and then, any decrease in tax revenue caused by tax evasion, for example, would weaken the government's ability to finance their investments and core financing private sector investment as a result of reduced ability to increase their reserves's cash banks, as well as the weakening of the effectiveness of tax evasion taxes as a tool to guide economic activity in the framework of service for development, and to achieve justice. And the statement of the reasons for and methods of evasion mandated to pay the tax due on them, whether legitimately or illegal with the statement of the proposed methods to tackle tax evasion and elim
... Show MoreAcceptable Bit Error rate can be maintained by adapting some of the design parameters such as modulation, symbol rate, constellation size, and transmit power according to the channel state.
An estimate of HF propagation effects can be used to design an adaptive data transmission system over HF link. The proposed system combines the well known Automatic Link Establishment (ALE) together with variable rate transmission system. The standard ALE is modified to suite the required goal of selecting the best carrier frequency (channel) for a given transmission. This is based on measuring SINAD (Signal plus Noise plus Distortion to Noise plus Distortion), RSL (Received Signal Level), multipath phase distortion and BER (Bit Error Rate) fo
... Show Moreمشكلة البحث واهميته:-
اخذ موضوع العولمة قدراً وافياً من الاهتمام سواء على المستوى الاكاديمي او على مستوى اجهزة الاعلام والرأي العام ومختلف التيارات السياسية والاقتصادية والاجتماعية ، فلا يخلو أي لقاء اقتصادي او سياسي او اجتماعي من الحديث عن العولمة اذ نشرت العديد من الابحاث والدراسات وعقدت الكثير من الندوات والمؤتمرات لدراسة العولمة وبيان اثارها ولعل ذل
... Show MoreThe searchers opinions are variant in determining the extent of impacting political risk in the host country on foreign direct investment decision. (Aharoni,1966) found, in his questionary study for group of foreign companies operating in India, that a political stability is one of the two most important factors, besides the market size, in the attraction of foreign investment, and its availability means that whether this specific country is good for foreign investment. On the other side, (Green and Benntt, 1972) are present a variant opinion to Aharonis opinion. They are reach to result state that a political instability do not impact on the general distribution of foreign i
... Show Moreعرض كتاب على خط النار مذكرات الرئيس الباكستاني
The Arab economy suffers from many structural imbalances problems which are getting complicated by the appearance of the world economic variables.
This change held risky challenges for the Arab economies in the light of unsuitable regional and international conditions. Since that it has been very essential for the Arab experts, especially those related to economy and politics, to face those new challenges or, at least, adapt with them believing that they can have both positive and negative impacts on the Arab economy.
This study has acquired its importance in the light of the critical levels the Arab economy reached out of the world economic variables, resulting in long-term
... Show MoreThe design and implementation of an active router architecture that enables flexible network programmability based on so-called "user components" will be presents. This active router is designed to provide maximum flexibility for the development of future network functionality and services. The designed router concentrated mainly on the use of Windows Operating System, enhancing the Active Network Encapsulating Protocol (ANEP). Enhancing ANEP gains a service composition scheme which enables flexible programmability through integration of user components into the router's data path. Also an extended program that creates and then injects data packets into the network stack of the testing machine will be proposed, we will call this program
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