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The effect of composite bonding spot size and location on the performance of poly-ether-ether-ketone (PEEK) retainer wires
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Background: Poly-ether-ether-ketone(PEEK) has been introduced to many dental fields. Recently it was tested as a retainer wire‎ following orthodontic treatment. This study aimed to investigate the effect of changing the bonding spot size and location on the performance of PEEK retainer wires. Methods: A biomechanical study involving four three-dimensional finite element models was performed. The basic model was with a 0.8 mm cylindrical cross-section PEEK wire, bonded at the center of the lingual surface of the mandibular incisors with 4 mm in diameter composite spots. Two other models were designed with 3 mm and 5 mm composite sizes. The last model was created with the composite bonding spot of the canine away from the center of the crown, closer to the lateral incisor. The linear displacement of the teeth, strains of the periodontal ligament, and stresses in PEEK wire and composite were evaluated. The data was numerically produced with color coded display by the software. Selected values were tabulated and compared among models. Results: The amount of linear displacement and strain was very low. Stresses in the wire and composite were affected by the size and position of the composite bonding spot. The safe limits were identified at 235 MPa for PEEK and 100 MPa for composite. The basic model had a von Mises stress in the PEEK wire of 122.09 MPa, and a maximum principal stress in the composite of 99.779 MPa. Both stresses were within the safe limits, which means a lower risk of failure in PEEK and composite. All other models had stresses that exceeded the safe limit of the composite. The 3 mm composite model was the only one that developed stresses in the wire more than the safe limits of PEEK. Conclusions: Within the limitations of this study, bonding PEEK wires with 4 mm bonding spots to the clinical crown center provided the best mechanical performance of the wires and spots; otherwise, the mechanical properties of the wire and composite would be affected and, therefore, might affect the retention process. Keywords: Retention, PEEK, Finite element analysis

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Publication Date
Thu Jan 14 2021
Journal Name
Iraqi Journal Of Science
Modelization of the Personal Learning Environment in the Moroccan Higher Education
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Any research focusing on the teaching-learning process must focus on the learner, by mobilizing the various devices to facilitate and optimize learning. In this context, we introduce the integration of educational technologies into a personal learning environment (PLE). The PLE has significant potential for learning; namely self-construction and self-management of knowledge. According to Attwel (2007b), the development and improvement of PLE will lead to drastic changes in the way we use educational technology, as well as in the organization and ethics of education. With the present contribution, we try to modelize the PLE of students within institutions of higher education in Morocco. Based on data from a questionnaire put online using

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Publication Date
Wed Dec 30 2015
Journal Name
College Of Islamic Sciences
The concept of sohba when the Golden Imam Through his books
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Scientists were interested in the statement of the concept of companions and the definition of the companion in terms of his status or his novel or inherent to the Prophet of Allah (peace be upon him) and was for those who did not walk in the translations and the abundant share in this work, and among these scientists Hafiz Shams al-Din al-Dhahabi, which was translated to the companions His books, indicating their status and effort, and who had a novel of them - what we will see in the folds of the research, God willing -

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Publication Date
Thu Mar 19 2015
Journal Name
Al-academy
The concept of Sustainable Environments in the UAE: عبد الصمد الخالدي
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Over last decade, rapid growth in economic and population accompanied with depletion of the energy resources lead to serious impacts on environment and humanity. This development coupled with active constructions, which in some examples ignore the impact on the environment and human activities. Therefore, principle of sustainability has required in order to reducing this negative impact on the environment and the humanity.In developing countries, it seems that there is a huge gap between the current construction practices and sustainable principle, which need more attention to clarify and define the problems in order to find suitable solutions before it comes more difficult and expensive. The study aims to choose one of the develo

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Publication Date
Sun Jan 26 2020
Journal Name
Iraqi Journal Of Science
The Seismic Image of The Direct Hydrocarbon Indicators in Offshore Syria
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     The easternmost Mediterranean Basin is a candidate to be one of the most important hydrocarbon regions in the world, especially after significant gas discoveries in Levantine Basin in 2009. Offshore Syria is one of the easternmost Mediterranean areas which is still an unexplored virgin area. The seismic interpretation results of the study area showed encouraging evidences of considerable hydrocarbon accumulations within different sedimentary successions, which are Direct Hydrocarbon Indicators (DHIs). Indicators such as reflectivity anomalies (flat spots and dim spots) and polarity reversal were found within significant structural highs of Tertiary or/Late Cretaceous and Early Jurassic successions. Also, gas chim

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Publication Date
Sun Jul 04 2010
Journal Name
Journal Of The Faculty Of Medicine Baghdad
The role of pepsinogen test among the patients with gastric cancer.
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Background: Identification the relationship of pepsinogen test (pepsinogenI and I /pepsinogen II ratio) and gastric cancer patients make the gastric cancer early diagnosed and prolong the life surviving rate.
Patients and Methods: Serum pepsinogen I and pepsinogen II (PG I and PG I / PG II ratio) measured in 50 patients with gastric cancer ,30 gastritis patients diagnosed , and 16 healthy control by using enzyme immunoassay in those study groups, and the results of PG I and PG I / PG II ratio were comparing to 50 gastric cancer patients whom diagnosed histopathologically according the stomach regions, while the gastritis patients diagnosed endoscopically.
Results: This study showed that the age of pati

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Publication Date
Mon Jun 01 2009
Journal Name
Al-khwarizmi Engineering Journal
Analytical Modeling of Stresses in the Wall 0f the Human Heart
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The mechanical function of the heart is governed by the contractile properties of the cells, the mechanical stiffness of the muscle and connective tissue, and pressure and volume loading conditions on the organ. Although ventricular pressures and volumes are available for assessing the global pumping performance of the heart, the distribution of stress and strain that characterize regional ventricular function and change in cell biology must be known. The mechanics of the equatorial region of the left, ventricle was modeled by a thick-walled cylinder. The tangential (circumferential) stress, radial stress and longitudinal stress in the wall of the heart have been calculated. There are also significant torsional shear in the wall during b

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Publication Date
Thu Nov 01 2018
Journal Name
International Journal Of Computing And Digital Systems
The Perception of Information Security Threats Surrounding the Cloud Computing Environment
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Publication Date
Fri Apr 01 2016
Journal Name
Astronomy Reports
Ionized gas in the circumgalactic vicinity of the M81 galaxy group
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Publication Date
Wed Nov 17 2021
Journal Name
International Journal Of Knowledge Management
Assessing the Success of the Perceived Usefulness for Knowledge Management Systems
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Recently, Knowledge Management Systems (KMS) consider one of the major fields of study in educational institutions, caused by the necessity to identify their knowledge value and success. Hence, based on the updated DeLone and McLean’s Information Systems Success Model (DMISSM), this study set out to assess the success of the Perceived Usefulness of Knowledge Management Systems (PUKMS) in Iraqi universities. To achieve this objective, the quantitative method is selected as the research design. In total, 421 university administration staff members from 13 Iraqi private universities were conducted. This study highlights a number of significant results depending on structural equation modeling which confirms that system, information, and s

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Publication Date
Tue Jan 03 2023
Journal Name
International Journal Of Advances In Science, Engineering And Technology
VISUAL INTERACTION TECHNOLOGY IN THE PEDIATRIC MEDICALDEPARTMENTS OF THE EDUCATIOAL HOSPITAL.
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