Background: The ideal force-delivery system must: provide optimal tooth moving forces that elicit the desired effects, be comfortable and hygienic for the patient, require minimal operator manipulation and patient cooperation and provide rapid tooth movement with minimal mobility during orthodontic therapy, the elastomeric chains have the greatest potential to fulfill these requirements. Materials and Methods: This in vitro study was designed to determine the effect of three different mechanisms for canine retraction : (6-3 , 6-5-3 and chain loop ) on the load relaxation behavior of three types of elastomeric chains : (maximum clear , maximum silver and extreme silver) from the same company (Ortho Technology company) with two different brand configurations: closed loop and open (short filament) chains under effect of time at (zero time, 24hr., 7, 14 , 21 and 28 days) in artificial saliva. Results: Statistical analysis showed that there was a highly significant difference in the mean percentage force decay for the three different mechanisms (P? 0.001).For all the three types, the 6-3 mechanism had the smallest mean percentage force decay. There was a highly significant difference in the mean percentage force decay for the different types (P? 0.001). For all three mechanisms, extreme silver elastomeric chains had the smallest percentage force decay while maximum silver elastomeric chains had the highest percentage force decay. Conclusion: This study illustrated that for all the three types of elastomeric chains, the (6-3) mechanism had the smallest mean percentage force decay. This finding suggests that it may be most efficient to retract a canine utilizing elastomeric chain directly from the molar hook to the canine bracket. The chain loop mechanism may not be indicated for space closure in vivo due to the excessive physiological force values involved with this mechanism.
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A simple, rapid spectrophotometric method has been established for the determination of chlorpromazine hydrochloride (CPZ) in its pure form and in a tablet formulations. The suggested method is based on the oxidative coupling reaction with4-nitroainlline using KIO3 in acidic solution to produce a violet colored product with maximum absorption at λ=526 nm.The analytical data obtained throughout this study could be summarid as follows: 1ml of 1M HCl (pH=2.2), 1 ml of 4-nitroanilline (1x10-2M), and 1.5ml of (1x10-2)KIO3 per 25 ml reaction medium. The order of a
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This research deals with the motives of the use of Facebook by elderly people and the achieved needs, which leads the researcher to ask an important question: why an old persons use Facebook and are the achieved needs through which they got? The research aims to find out the habits and patterns of using Facebook by old men and stands on the main motives of the elderly in their use of Facebook. It also identifies the most prominent needs that have been made for the elderly as a result of their use of Facebook.
The research is a descriptive one in which the researcher uses survey method to achieve the desired goals. The researcher has chosen a group of old men from Diyala province. The total sample number is about
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Often phenomena suffer from disturbances in their data as well as the difficulty of formulation, especially with a lack of clarity in the response, or the large number of essential differences plaguing the experimental units that have been taking this data from them. Thus emerged the need to include an estimation method implicit rating of these experimental units using the method of discrimination or create blocks for each item of these experimental units in the hope of controlling their responses and make it more homogeneous. Because of the development in the field of computers and taking the principle of the integration of sciences it has been found that modern algorithms used in the field of Computer Science genetic algorithm or ant colo
... Show MoreThe most universal and basic damages caused by an earthquakes are buildings damage and human casualties. A simplified method, the RADIUS 99 Tool is used to calculate seismic intensity (shaking) distribution, buildings damage, number of casualties and lifelines damage, due to assumed earthquake scenario. In this study, Al - Kadhmiya sector in Baghdad city was chosen for assessing seismic risk, for this purpose, this area was divided into mesh of 1*1 km2 cell size, and a scenario of (Manjil) earthquake (that struck Iran in 1990) was utilized with following earthquake magnitudes (5 and 7), with epicenter distance (3, 10 and 100 km), and depths (2 and 5 km). It was found that, the best soil types for constructions are those with medium and h
... Show MoreThe possibility of using the magnetic field technique in prevention of forming scales in heat exchangers pipes using
hard water in heat transfer processes, also the studying the effective and controllable parameters on the mechanism of
scale formation.
The new designed heat exchanger experimental system was used after carrying out the basic process designs of the
system. This system was used to study the effect of the temperature (40-90 °C) and water flow rate (0.6-1.2 L/min) on
the total hardness with time as a function of precipitation of hardness salts from water and scale formation.
Different magnetic field designs in the heat exchanger experimental system were used to study the effect of magnetic
field design a
The ability of using aluminum filings which is locally solid waste was tested as a mono media in gravity rapid filter. The present study was conducted to evaluate the effect of variation of influent water turbidity (10, 20and 30 NTU); flow rate(30, 40, and 60 l/hr) and bed height (30and60)cm on the performance of aluminum filings filter media for 5 hours run time and compare it with the conventional sand filter. The results indicated that aluminum filings filter showed better performance than sand filter in the removal of turbidity and in the reduction of head loss. Results showed that the statistical model developed by the multiple linear regression was proved to be
valid, and it could be used to predict head loss in aluminum filings
Background: The prediction of changes in the mandibular third molar position and eruption is an important clinical concern because third molar retention may be beneficial for orthodontic anchorage. The aims of this study were to assess the mandibular third molar position by using medical CT scan and lateral reconstructed radiograph and evaluate gender differences. Materials and Methods: The sample of present study consisted of 39 patients (18 males and 21 females) with age range 11-15 years who were attending at Al-Suwayra General Hospital/ the Computerized Tomography department. The distance from anterior edge of ramus to distal surface of permanent mandibular second molar and mesio-distal width of developing mandibular third molar were
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