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 t

Developing routes to produce cellulose nanocrystals (CNCs) from high-lignin wood residues is essential for expanding sustainable nanocellulose feedstocks. In this work, Meranti (Shorea sp.) sawdust was valorized into CNCs by integrating ammonium persulfate (APS) pretreatment with subsequent sulfuric acid hydrolysis. To establish a severity map and define an operating window, APS pretreatment severity was systematically varied by adjusting APS concentration and the sawdust-to-APS (solid-to-liquid) ratio, and its influence on CNC structural properties was evaluated. APS pretreatment partially disrupted and oxidized the lignocellulosic matrix, enabling acid hydrolysis to liberate crystalline cellulose domains. XRD analysis confirmed th

Arcology is a new vision of urban design for densely populated settlements. It is referred to as the urban formation aimed at achieving the highest level of utilization in the least area of land to reduce human impact on the environment. Moreover, the integration of this formation with the environment will work to reduce energy consumption, and achieve an economy that is characterized by adaptation and self-sufficiency, leading towards sustainable urbanism. The current study deals with this new concept in sustainable urban design, in an attempt to investigate its impact on traditional urban formation and to make a comparison between them. The lack of a clear conception of the term ‘arcology’ and comparing it with the organic compact urb

Gas and downhole water sink-assisted gravity drainage (GDWS-AGD) is a new process of enhanced oil recovery (EOR) in oil reservoirs underlain by large bottom aquifers. The process is capital intensive as it requires the construction of dual-completed wells for oil production and water drainage and additional multiple vertical gas-injection wells. The costs could be substantially reduced by eliminating the gas-injection wells and using triple-completed multi-functional wells. These wells are dubbed triple-completion-GDWS-AGD (TC-GDWS-AGD). In this work, we design and optimize the TC-GDWS-AGD oil recovery process in a fictitious oil reservoir (Punq-S3) that emulates a real North Sea oil field. The design aims at maximum oil recovery us

المقدمة

تتعامل الجهات الضريبية في مختلف دول العالم بأساليب عديدة لجباية الضرائب من المكلفين بغض النظر عن فئات وأصناف هؤلاء المكلفين،وفي العراق تم اعتماد العديد من الأساليب لجباية الضرائب على امتداد المدد الزمنية المتعاقبة،وكان لأسلوب التقدير الذاتي وهو أحد تلك الأساليب مجالاً للتطبيق خلال مدة زمنية معينة،حيث جرى تطبيق هذا الأسلوب على وحدات اقتصادية معينة، وبالرغم من المساوئ التي قد ترافق تطبيق

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