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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
Sat Feb 27 2021
Journal Name
Iraqi Journal Of Science
Specifications study of Hydrophobic Silica Aerogel Doped with Rhodamine 6G Prepared via Sub-Critical Drying Technique
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The influence of dye laser Rhodamine 6G (R6G) on the molecular structure of silica aerogel prepared by normal drying method is reported. The study also tests the effect of dye concentration on morphological and physical properties. Fourier Transform Infrared Spectroscopy (FTIR) was used to examine this effect, in addition to Field Emission Scanning Electron Microscopy (FESEM), contact angle, and surface area measurement. It was found from FTIR data that the dye laser stays with the inner structure of samples and, at high concentration, it gives a good influence by reducing (OH) band and increasing (CH) band, leading to changing the contact angle from (123á´¼) to (145á´¼). Whereas particle size varied from 22 n

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Publication Date
Fri Jan 01 2016
Journal Name
8th Conference On Power Electronics, Machines And Drives (pemd), Glasgow, Uk
Design of tubular moving magnet linear alternator for use with an external combustion - free piston engine
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Publication Date
Thu May 31 2018
Journal Name
International Journal Of Control And Automation
Power Flow Control of Iraqi International Super Grid with Two-Terminal HVDC Techniques Using PSS/E
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Publication Date
Sat Dec 11 2021
Journal Name
Engineering, Technology & Applied Science Research
Behavior of RC Beams Strengthened with NSM-CFRP Strips Subjected to Fire Exposure: A Numerical Study
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The use of Near-Surface Mounted (NSM) Carbon-Fiber-Reinforced Polymer (CFRP) strips is an efficient technology for increasing flexural and shear strength or for repairing damaged Reinforced Concrete (RC) members. This strengthening method is a promising technology. However, the thin layer of concrete covering the NSM-CFRP strips is not adequate to resist heat effect when directly exposed to a fire or at a high temperature. There is clear evidence that the strength and stiffness of CFRPs severely deteriorate at high temperatures. Therefore, in terms of fire resistance, the NSM technique has a significant defect. Thus, it is very important to develop a set of efficient fire protection systems to overcome these disadvantages. This pape

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Publication Date
Wed May 24 2017
Journal Name
Ibn Al-haitham Journal For Pure And Applied Sciences
Antifungal Activity of Propolis Ethanol Extract Against Botrytis cinerea, Altrnaria sp Which Caused Many Plant Diseases
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  This study was conducted to determine the effect of different concentrations of   ethanol  extract of propolis against two  fungi Botrytis cinerea, Altrnaria sp.      The most important chemical constituents of propolis diagnosed by the Infra Red Spectroscopy, were the  Flavonoids  specificaly.       Results showed a high antifungal activity of ethanol  extract of propolis, evidently with a high concentration  of extract (5) mg\ml, which completely inhibited the radial growth on both  solid and liquid media (PDA &PD Broth ) of both fungi .         We observed that , ethanol  extract p

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Publication Date
Wed Jun 27 2018
Journal Name
Iraqi Journal Of Science
Proposed Method of Air Traffic Routing in Dynamic Environment Usiing Modifed rrt With Collision Avoid Nace
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     In the current Airlines Air Traffic Management (ATM), the Air Traffic Control Operators (ATCO), with the Air Traffic Control systems (ATC), operate air traffic paths with a small number of fixed routes. Problems of fixed routes appear such that even when they reduce the chance for conflict, they also produce flight paths plans that do not reduce flight time or fuel usage. In nowadays Airlines are heavily overloaded and anxious to minimize the aircrafts fuel usage costs, increase airplanes, and optimize the paths or the flight routes in order to find the most optimal suitable flight paths. This paper presents a new path planning method that deal with such problem effectively, the idea was to produce flights routes

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Publication Date
Sat May 08 2021
Journal Name
Iraqi Journal Of Science
Oscillatory Flow MHD of Jeffrey Fluid with Temperature-Dependent Viscosity (TDV) in a Saturated Porous Channel
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In this research, we studied the impact of Magnetohydrodynamic (MHD) on Jeffrey fluid with porous channel saturated with temperature-dependent viscosity (TDV). It is obtained on the movement of fluid flow equations by using the method of perturbation technique in terms of number Weissenberg ( ) to get clear formulas for the field of velocity. All the solutions of physical parameters of the Reynolds number , Magnetic parameter , Darcy parameter , Peclet number  and are discussed under the different values, as shown in the plots.

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Publication Date
Fri Mar 31 2017
Journal Name
Iraqi Journal Of Pharmaceutical Sciences ( P-issn 1683 - 3597 E-issn 2521 - 3512)
A Modified Organic Method for Preparation of Ibuprofen Microcapsules As a Sustained Release Solid Dosage Form
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ABSTRACT:
Microencapsulation is used to modify and retard drug release as well as to overcome the unpleasant effect
(gastrointestinal disturbances) which are associated with repeated and overdose of ibuprofen per day.
So that, a newly developed method of microencapsulation was utilized (a modified organic method) through a
modification of aqueous colloidal polymer dispersion method using ethylcellulose and sodium alginate coating materials to
prepare a sustained release ibuprofen microcapsules.
The effect of core : wall ratio on the percent yield and encapsulation efficiency of prepared microcapsules was low, whereas
, the release of drug from prepared microcapsules was affected by core: wall ratio ,proportion of coa

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Publication Date
Fri Jun 01 2018
Journal Name
Journal Of The College Of Languages (jcl)
Проблемы преподавания русской литературы в иракской аудитории Problems of Teaching Russian Literature to Iraqi College Students
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Аннотация

    в статье рассматриваются проблемы преподавания русской литературы в иракской аудитории.. Использование литературы в преподавании иностранного языка, как правило, имеет две цели. Первая-чисто лингвистическая .. Вторая цель, однако, ассоциируется больше с экстралингвистикой  и представляет собой ознакомление студентов с различными аспектами русской жизни, культуры,

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Publication Date
Wed Dec 01 2021
Journal Name
Bioresource Technology Reports
Biosynthesis of polyhydroxyalkanoate (PHA) by a newly isolated strain Bacillus tequilensis ARY86 using inexpensive carbon source
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