Background: Thermocycling simulates the temperature dynamics in the oral environment. This in vitro study done to measure and compare the effect of thermocycling on the shear bond strength of stainless steel and sapphire brackets bonded to human enamel teeth using light cured orthodontic adhesive and debonded at various time, and to measure adhesive remnant index after debonding. Materials and Methods: one-hundred-twenty extracted upper first premolars for orthodontic reason were used in this study; depending on weather thermocycled or not, the sample was divided into two main groups, then within each group 30 teeth were used for stainless-steel brackets (Bionic®) and for sapphire brackets (Pure®). Both groups were subdivided into three groups (n = 10) according to the debond times: I: debond after 24 hour, II: debond after 7 days and III: debond after 30 days. Within 24 hr, half of the sample was thermocycled manually for 500 complete cycles between 5/55°C and the remaining sample was stored in distilled water at room temperature and water was changed daily until debond time for each group was performed. The adhesive remnant index was tested under 20X magnification lens using stereomicroscope. Results and Conclusions: Both bracket types demonstrated high shear bond strength values before thermocycling (P?0.05), whereas after 500 thermocycles, there were significant changes in shear bond strength resulted in marked reduction in the stainless steel brackets than in the sapphire brackets (P?0.05). Shear bond strength values increased with time for both stainless steel and sapphire brackets with and without thermocycling (P?0.05). The tendency of bond failure was increased at the bracket/adhesive interface rather than enamel/bracket interface in the stainless steel brackets whereas at the enamel/bracket interface rather than bracket/adhesive interface in the sapphire brackets.
The protective effect of benfotiamine against doxorubicin-induced cardiotoxicity was evaluated in rabbits. Pretreatment of rabbits with 70mg/kg benfotiamine orally 7 days before induction of cardiotoxicity with I.V 15mg/kg doxorubicin. injection resulted in significant reduction of the activities of lactate dehydrogenase and creatine phosphokinase enzyme in the serum compared to doxorubicin treated animals; benfotiamine also improves the histological changes produced by doxorubicin in the cardiac muscle compared to control. In conclusion, benfotiamine when used concomitantly with doxorubicin protects the myocardium against the cardiotoxicity induced by this cytotoxic drug.
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Polyvinyl chloride (PVC) finds use in various industries due to its versatility but is not thermostable, serving as a barrier to causing degradation and release of hydrochloric acid (HCl) under heat stress conditions. Lead and organotin compounds have traditionally been used for stabilizer purpose to discourage such degradation but pose serious ecological as well as health risks. As a counter measure, bio-based stabilizers from plant oils have become popular as a green and sustainable alternative. This review looks back at recent developments in plant oil-based stabilizers for PVC, focusing on the mechanisms of stabilization, sustainability, and cost-effectiveness. We review plant oils such as tung oil, castor oil, and soybean oil,
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The interest in pre-service teacher training has become influential in teaching English as a foreign language, and the purpose of this training course is to prepare qualified teachers to teach effectively through the application of this technique by undergraduate students. This research aims to find out the effect of using the seven principles of good practice as a teaching technique on the fourth stage student-teachers’ performance at the College of Education for Women/University of Baghdad, during the academic year 2017-2018. The sample includes (60) students selected according to the stratified sampling method. The observational checklist used by the department to assess the student teachers’ performance during the practicum perio
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The aim of this paper is to prove a theorem on the Riesz means of expansions with respect to Riesz bases, which extends the previous results of [1] and [2] on the Schrödinger operator and the ordinary differential operator of 4-th order to the operator of order 2m by using the eigen functions of the ordinary differential operator. Some Symbols that used in the paper: the uniform norm. <,> the inner product in L2. G the set of all boundary elements of G. ˆ u the dual function of u.
The impact of applying the K-W-L self-scheduling technique on first-year intermediate students' learning of basic volleyball skills, Ayad Ali Hussein*, Israa Fouad Salih
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The aim of this paper is prove a theorem on the Riesz mean of expansions with respect to Riesz bases, which extends the previous results of Loi and Tahir on the Schrodinger operator to the operator of 4-th order.
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Iraqi industrial units face strong competition due to many problems including1- high production costs2- weak interest in studying the market3- lack of government support for their products4- dumping the market with imported products with specifications and a competitive price as well as adopting the traditional cost system in calculating costs that do not provide appropriate information for pricing decisions Which requires studying and analyzing these problems and dealing with them by adopting modern technologies so that they can compete, so the research aims to show the knowledge bases of technology Activity- Based Costing, with an indication of the role of technology Activity- Based Costing in rationalizing the tax In, and the
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