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
The study was conducted in the poultry field of the Department of Animal Production/ College of Agricultural Engineering Sciences/ University of Baghdad/ Abu Ghraib, for the period from 28/04/2022 to 08/06/2022 to demonstrate the effect of adding a mixture of Lion’s mane Hericium erinaceus and Reishi Mushroom Ganoderma lucidum to broiler's diets on productive performance, 120 one day old Ross 308 breed broiler chicks were used in the experiment, with (10 birds / replicate) with an average starting weight of 49.95 g. The experiment treatments were as follows:(T1) basic diet control treatment free of any addition. (T2) the basic diet with the addition of 0.5 g/kg fodder of Lion's Mane mushroom with 0.5 g/kg fodder of the Reishi Mus
... Show MoreDust samples have been collected from three areas in Baghdad during dust storm occurred in 18th of June 2009 to characterize elemental particle size and composition by different techniques. The x-ray diffraction detected six minerals those are calcite, and quartz, present as a major components, dolomite, kaolinite, gypsum and plagioclase present as miner components .EDX detected some normal elements presented in local soil except traces of lead , nickel, and chromium. The particle size analysis by a set of sieves have revealed that the majority particle distribution was between (32 and 45)μm . To isolate the aerosol size, PM10 buoyancy method of powder in water showed a signifying amounts of particulate size .Scheerer’s method was app
... Show MoreThe maximization of the net present value of the investment in oil field improvements is greatly aided by the optimization of well location, which plays a significant role in the production of oil. However, using of optimization methods in well placement developments is exceedingly difficult since the well placement optimization scenario involves a large number of choice variables, objective functions, and restrictions. In addition, a wide variety of computational approaches, both traditional and unconventional, have been applied in order to maximize the efficiency of well installation operations. This research demonstrates how optimization approaches used in well placement have progressed since the last time they were examined. Fol
... Show MoreField experiment conducted to measured Slippage, Effective field capacity, Field Efficiency, Soil Volume Disturbed and Specific Productivity Tillage in silt clay loam soil with depth 18 cm in Baghdad- Iraq. Split – split plot design under randomized complete block design with three replications using Least Significant Design 5 % was used. Three factor used in this experiment included Two types of plows included Chisel and Disk plows which represented main plot , Three Tires Inflation Pressure was second factor included 1.1 ,1.8 and 2.7 Bar, and Three forward speeds of the tillage was third factor included 2.35 , 4.25 and 6.50 km/hr. Result show chisel plow recorded best parameters performance
Lithium-rich layered oxide cathodes have attracted considerable attention due to their high energy density, but have suffered from voltage drop, structural instability, and limited electrical conductivity. In this study, the electrochemical performance of the lithium-rich cathode material Li[Li0.20Mn0.54Ni0.13Co0.13]O2 was evaluated after modification by zinc doping and composition with graphene oxide or graphene. The zinc-doped powders were synthesized by the sol-gel method, while the graphene-based composites were prepared by the hydrothermal route. The structural, morphological and electrochemical characteristics of the modified materials were examined using X-ray diffraction, Fourier transform infrared spectroscopy, field emission scann
... Show MoreThis study has aimed to investigate the effect of feed forms, mash and pellet on productive performance and carcass yields of broilers. 225 unsexed birds of the hybrid Ross 308 broiler were used, with a starting weight of 45.4 g one day old. The experiment lasted up to 35 days. The birds were randomly distributed into five treatments; each treatment contained 45 chicks according to three replicates (15 birds/ replicate). The experiment’s treatments included: (T1) Control mash 100% (pellet 0%), (T2) mash 75% (pellet 25%), (T3) mash 50% (pellet 50%), (T4) mash 25% (pellet 75%) and (T5) mash 0% (pellet 100%). Results were recorded a significant superior of T4 compared with other treatments (P≤0.05) in live body weight, weight gain,
... Show MoreIncreased attention to corporate governance with the increasing need for investors and other parties in the Iraqi market for securities of the information credible and confidence and greater transparency in the disclosure as well as the systems of governance lead to raise the value of the company and that by reducing the cost of capital and reduce the cost of financing, as well as that there are indications modern measurement can be adopted by the Iraqi market for securities for the purpose of evaluating the performance of listed companies and then raise their value.
The research problem is that there is no framework or structure of the legal and local rules for the application of corporate governance in Iraq obliges
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