Background: Elastomeric chains are used to generate force in many orthodontic procedures, but this force decays over time, which could affect tooth movement. This study aimed to study the force degradation of elastomeric chains. Data and Sources: An electronic search on Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, LILACS, and PubMed was made, only articles written in English were included, up to January 2022.Study selection: Fifty original articles, systematic reviews, and RCTs were selected. Conclusion: Tooth movement, salivary enzymes, alcohol-containing mouthwash, whitening mouthwash, and alkaline and strong acidic (pH <5.4) solutions all have a significant impact on elastomeric chain force degradation. The force level of elastomeric chains degrades rapidly over time; however, the force degradation rate is slower in thermoset chains than in thermoplastic ones. An efficient tooth movement could be achieved by using a thermoset chain type with monthly replacement. Ethylene oxide and gamma sterilization methods are preferred to avoid the risk of cytotoxicity.
This research is devoted to study the effect of different in weight percentage of Sio2 particles and glass fibers (5, 10, 15, 20) wt. % on the wear rate epoxy resin. The results show that the value of hardness increase with the increase for the weight percentage of reinforcing particles and fibers, while the wear rate decrease with the increase the load level of the reinforcing particles and fibers . The largest value of the hardness, and the lowest value of the wear rate for epoxy reinforced with 20% of SiO2, the wear rate increase in general with increasing the applied load.
The research aims to identify the psychological and health risks that a child might be exposed to by playing with hazardous toys such as pellet guns. To this end, the researcher has visited Ibn Al-Haytham Eye Hospital in Baghdad, the emergency department to figure out the rate of injuries in Children for the consecutive years (2017-2018) and the first Month of (2019). The psychological risks as a result of disability are represented by the inability to accommodate the surrounding environment well. Additionally, the child experiences a kind of tension, conflict, and going in psychological crises through introversion, isolation, withdrawal tendencies, and poor conformity with himself and the Society.
The latest events in Iraq and notably the fall of Mosul in the summer of 2014 have marked a turning point in The modern history of Iraq. Violent terrorist groups have overrun a vast area comprising of many towns in mid and northern Iraq causing many casualties and mass migration. Despite Iraq’s long history of pain and suffering the events of the second half of the year 2014 have been the most violent ever witnessed. From this point of view the researcher has tried to identify specifically in this time and place the effect these events have had on the Iraqi artist and to understand how the Iraqi artists depicted this violence in their works of art. The research comprises four parts; the first looked at the language used and the and pro
... Show MoreA simple and accurate method to determinate furosemide (FUR) based on converting the secondary amine to primary amine with acidic hydrolysis then azotization by nitrous acid and coupled with resorcinol as a coupling agent in aqueous medium at pH 13. The optical characteristic like beers law limit found to be (0.25-2.5) μg.ml−1, detection and quantification limits (0.0196) (0.0654) μg.ml−1respectivly and Sandel sensitivity was 0.006738 μg.cm−2. The least-square method was used to evaluate the regression equation and the correlation coefficient. The resulted azo dye has a maximum absorbance at 430 nm with light oran
The aim of the present research is to study different protein fractions in sera of children and adolescent with β –thalassemia major and minor and to compare the results with that of healthy control.One hundred fifty children and adolescents were enrolled in this study,including 50 patients with β- thalassemia major , 50 patients with β- thalassemia minor as pathological control group and another apparently 50 healthy individuals as a control group. The age of all studied groups ranged from (4-18)years.Total protein, albumin and immunoglobulins were estimated in sera of all subjects. A Significant decrease was found in the total protein and albumin&nb
... Show MoreThe aerodynamic characteristics of the forward swept wing aircraft have been studied theoretically and experimentally. Low order panel method with the Dirichlet boundary condition have been used to solve the case of the steady, inviscid and compressible flow. Experimentally, a model was manufactured from wood to carry out the tests. The primary objective of the experimental work was the measurements of the wake dimensions and orientation, velocity defect along the wake and the wake thickness. A blower type low speed (open jet) wind tunnel was used in the experimental work. The mean velocity at the test section was (9.3 m/s) and the Reynolds number based on the mean aerodynamic chord and the mean velocity was (0.46x105). The measurements sho
... Show MoreThe Hubble telescope is characterized by the accuracy of the image formed in it, as a result of the fact that the surrounding environment is free of optical pollutants. Such as atmospheric gases and dust, in addition to light pollution emanating from industrial and natural light sources on the earth's surface. The Hubble telescope has a relatively large objective lens that provides appropriate light to enter the telescope to get a good image. Because of the nature of astronomical observation, which requires sufficient light intensity emanating from celestial objects (galaxies, stars, planets, etc.). The Hubble telescope is classified as type of the Cassegrain reflecting telescopes, which gives it the advantage of eliminating chromat
... Show MoreIt is believed that Organizations around the world should be prepared for the transition to IPv6 and make sure they have the " know how" to be able to succeed in choosing the right migration to start time. This paper focuses on the transition to IPv6 mechanisms. Also, this paper proposes and tests a deployment of IPv6 prototype within the intranet of the University of Baghdad (BUniv) using virtualization software. Also, it deals with security issues, improvements and extensions of IPv6 network using firewalls, Virtual Private Network ( VPN), Access list ( ACLs). Finally, the performance of the obtainable intrusion detection model is assessed and compared with three approaches.
The present work aims to improve the flux of forward osmosis with the use of Thin Film Composite membrane by reducing the effect of polarization on draw solution (brine solution) side.This study was conducted in two parts. The first is under the effect of polarization in which the flux and the water permeability coefficient (A) were calculated. In the second part of the study the experiments were repeated using a circulating pump at various speeds to make turbulence and reduce the effect of polarization on the brine solution side.
A model capable of predicting water permeability coefficient has been derived, and this is given by the following equations:
Z=Z0 +C.R.T/9.8(d2/D2+1) [Exp. [-9.8(d
The influence of an aortic aneurysm on blood flow waveforms is well established, but how to exploit this link for diagnostic purposes still remains challenging. This work uses a combination of experimental and computational modelling to study how aneurysms of various size affect the waveforms. Experimental studies are carried out on fusiform-type aneurysm models, and a comparison of results with those from a one-dimensional fluid–structure interaction model shows close agreement. Further mathematical analysis of these results allows the definition of several indicators that characterize the impact of an aneurysm on waveforms. These indicators are then further studied in a computational model of a systemic blood flow network. This demonstr
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