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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
Mon Apr 17 2017
Journal Name
Iraqi Journal Of Market Research And Consumer Protection
10.28936 STUDY OF THE KINETIC AND ADSORPTION ISOTHERM PARAMETERS FOR REMOVING COPPER AND IRON IONS FROM AQUEOUS SOLUTIONS BY USING AGRICALTURAL BY-PRODUCTS.: STUDY OF THE KINETIC AND ADSORPTION ISOTHERM PARAMETERS FOR REMOVING COPPER AND IRON IONS FROM AQUEOUS SOLUTIONS BY USING AGRICALTURAL BY-PRODUCTS.
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Wheat straw was modified with malonic acid in order to get low cost adsorbent have a good ability to remove copper and ferric ions from aqueous solutions, chemical modification temperature was 120°C and the time was 12 h. Parameters that affect the adsorption experiments were studied and found the optimum pH were 6 and 5 for copper and iron respectively and the time interval was 120 min and the adsorbent mass was 0.1 g. The values for adsorption isotherms parameters were determined according to Langmuir [qmax were 54.64 and 61.7 mg/g while b values were 0.234 and 0.22 mg/l] , Freundlich [Kf were 16.07 and 18.89 mg/g and n were 2.77 and 3.16], Temkin [B were 0.063 and 0.074 j/mol and At were 0.143 and 1.658 l/g] and for Dubinin-Radushkev

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Publication Date
Sat Jan 09 2021
Journal Name
Review Of International Geographical Education
E-Learning Applications According To The Levels Of STEM Literacy For Teachers Of Physics At The Secondary Stage
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E-learning applications according to the levels of enlightenment (STEM Literacy) for physics teachers in the secondary stage. The sample consists of (400) teachers, at a rate of (200) males (50%), and (200)females (50%), distributed over (6) directorates of education in Baghdad governorate on both sides of Rusafa and Karkh. To verify the research goals, the researcher built a scale of e-learning applications according to the levels of STEM Literacy, which consists of (50) items distributed over (5) levels. The face validity of the scale and its stability were verified by extracting the stability coefficient through the internal consistency method “Alf-Cronbach”. The following statistical means were used: Pearson correlation coefficient,

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Publication Date
Mon Jan 28 2019
Journal Name
Journal Of Accounting And Financial Studies ( Jafs )
The contribution of information systems to increase tax revenues: An applied research at the General Commission of Taxes
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The research aims to study the contribution of tax information systems to increase tax revenues, and to identify how efficiently used information systems currently by the tax authority and their effectiveness in the detection of irregularities by the tax payers such as the cleclaration of incorrect statements that do not show real results of their business activities or hide information from sources related to their income subject to tax, which would negatively affect the outcome of tax revenues and thus damage important sourse of the public treasury of the states resources. The data of research was collected by studying and analysing the tax information systems used by the General Commission of taxs and its branches and a number of prac

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Crossref
Publication Date
Tue Jan 01 2019
Journal Name
Energy Procedia
Evaluation of the optical properties for thick films of epoxy-diamond paste blend prepared by the casting method
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Publication Date
Sat Sep 28 2024
Journal Name
Journal Of The Pakistan Medical Association
Investigating the correlation of the second derivative of digital pulse wave (DPW) with QT variability index in women
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Objective: To determine the correlation between the second derivative of digital pulse wave and the QT variability index. Method: The cross-sectional study was conducted from October 2021 to May 2022 at the Department of Physiology, College of Medicine, University of Mustansiriyah, Baghdad, Iraq, and comprised healthy women. Samples were raised by simple random technique. Digital pulse waves were captured using a fingertip pulse wave transducer. Lab Chart Pro version 7.2 was used to automatically detect and quantify the amplitude of A, B, C, D and E waves expressed by the second derivative. QT interval of each beat was recorded by electrocardiogram, and was calculated automatically via Lab chart Pro version 7.2 without averaging. D

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Publication Date
Fri Sep 15 2023
Journal Name
Al-academy
A new vision inspired by the school of geometric abstraction to enrich the field of Saudi plastic painting
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Art is a language in which the artist expresses himself, his society, and the events he lives in, so new artistic trends emerged, so the artist no longer practices his art as required by any previous artistic rules. And the thoughts wandering inside him, which led him to the abstract method in which the artist tries to employ the elements of the artwork in a plastic construction through which he achieves the relationships of the abstract form through the rhythms of lines, colors, spaces, shapes and textures without these plastic elements having any connection with the visual reality.
The research aims to find a new vision inspired by the school of geometric abstraction to enrich the field of Saudi plastic painting. And to take advan

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Crossref
Publication Date
Mon Oct 17 2016
Journal Name
Gstf Journal Of Advances In Medical Research (jamr)
An investigation into the factors governing the degree of dissolution enhancement of solid dispersion for poorly soluble drugs
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Solid dispersion (SD) formulation has attracted much attention due to its potential in enhancing dissolution performances of poorly soluble active pharmaceutical ingredients (API). Recently, a review on dissolution performances of SDs classifies the improvement into 3 categories, where 82 % of the studies showed improved bioavailability, 8 % showed reduced bioavailability and 10 % revealed similar bioavailability as compared to pure APIs. This indicates the inconsistent degrees of dissolution improvement of poorly soluble APIs in SD. Although a few factors related to the choice of carriers have been suggested to contribute to the dissolution improvement, however, the underlying factor determining the discrepancy in the degree of dissolution

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Publication Date
Tue May 20 2008
Journal Name
Journal Of Planner And Development
The use of mathematical formulas to control river pollution Study area Diyala River within the city of Baquba
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Pollution of the aquatic environment and the depletion of the natural resource cause imbalance in the natural balance of the river environment and contributes to the deterioration of life and the killing of living organisms. Most of the old and modern cities and urban centers were set up close to the rivers because water enters the main lifeblood and all its facilities. The proximity of cities to rivers caused environmental problems resulting from the dumping of residues of these cities to a large and continuous, these wastes include all uses of the city (industrial, agricultural, residential and commercial) and others. The accumulation of these wastes inside the rivers water kills life and makes them unsuitable for various uses to bury

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Publication Date
Fri Apr 01 2022
Journal Name
Chemical Engineering Science
Numerical modelling of flow through nodes in foams within the “dry” limit in the presence of solid particles
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Publication Date
Sun Jun 11 1989
Journal Name
مجلة متحف التاريخ الطبيعي
The Role of Specific Amino Acids in the Protection of Escherichia coli Against B-Lactam Antibiotics In Vitro
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ABSTRACT The role of specific amino acids namely cysteine, methionine, threonine and asparagine in the protection provided by vamin solution against B-lactam inhibition to E. coli was evaluated in vitro. In minimal medium, Cells were treated with 32 ug/ml of penicillin G, carbencillin, hostacillin, cloxacillin and cephalotin in the presence of specific amino acid supplementations. Deletion of specific amino acids from the media abolished the protection provided by vamin. Threonine was essential for the protection of cells against all tested antibiotics, while cysteine was essential for protection against carbencillin and cephalotin Deletion of methionine or asparagine abolished the protec- tion against carbencillin and to a less extent ce

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