ABSTRACT Background: This study measured the effects of three parameters pH value, length of immersion and type of archwire on metal ions released from orthodontic appliances. Materials and Methods: Ninety maxillary halves simulated fixed orthodontic appliances that were immersed in artificial saliva of different pH values (6.75, 5 and 3.5) during 28 day period. Three types of archwires were used: stainless steel, nickel titanium and thermal activated nickel titanium. The quantity of nickel and chromium ions was determined with the use of atomic force spectrophotometer while iron ions by spectrophotometer. Each orthodontic set was weighted two times, before the ligation and immersion in the artificial saliva and after 28 days at the end of immersion period using analytic balance device. Results: The release different metal ions was observed: nickel (Ni), chromium (Cr) and iron (Fe)). Statistically analysis of variance (ANOVA) and t-test were used. Results showed that (1) the appliances released measurable quantities ofall ions examined; (2) the change in pH had a very strong effect on the release of ions; (3) the release of ions was dependent on wire composition, but it was not proportionalto the content of metal in the wire and (4) orthodontic samples showed decreases in the weight at the end of the study. Conclusion: Levels of released ions are sufficient to cause delayed allergic reactions. This must be taken into account when type of archwire is selected, especially in patients with hypersensitivityor compromised oral hygiene.
Abstract The success of the system of government in any country needs to have a handle on the amount of power efficiency , capacity , capability and wisdom, Iraq has gone through since its inception through several stages of time, namely: The first stage: which ran from August 23, 1921 until July 14, 1958 and was ruling monarchy (rule of the royal family) and punishing power of political elites both of them and works access to power without taking into consideration the laws and principles of the Constitution, and as a result of the inability of civilian powers and political parties access to power to grant that army officers regulatory and disciplinary specifications as well as possessing arms and overthrow the rule of the minority coup
... Show MoreAn experimental investigation of the variation of argon discharge current with a glow and afterglow time intervals of a square discharge voltage was carried out at low pressure (6-11 mbar). The discharge was created between two circular metal electrodes of diameter (7.5 cm), separated horizontally by a distance (10 cm) at the two ends of a Pyrex cylindrical tube. A composite of two Gaussian functions has been suggested to fit and explain the variation graphs clearly. It is shown that the necessary times of glow and afterglow needed to attain a maximum discharge current are (70 us) and (60 us), respectively. The discharge current is observed to drop to the lowest value when the two times are serially longer than (85 us) and (72 u
... Show MoreThe wide use of pesticides in recent years leads to rapid distribution of these pollutants in the environment (air, water and soil).They were transported by means of air or water to biological ecosystems. They become more toxic through the processes of biological magnification while some of them persist for along period.The aim of this work is to show the negative effect that chemical pesticides causes, and in the same to show their side effect on the environment and health in Iraq. We could conclude that the bad use of these chemicals could cause an urgent impact now or in the future. Governmental offices dealing with these materials should take the right measures to minimize the danger and the misuse of these chemicals by seeking alternat
... Show MoreThe primary issue addressed in this research revolves around identifying the interactive elements provided by the Twitter platform and understanding their utilization by digital newspapers with official accounts. These newspapers broadcast content in line with their policies. This study is classified within descriptive research that employed a survey method and content analysis tool. The methodology relies on the "how was it said?" approach to categorize the analysis. The research yielded the following results:
Twitter utilized numerous interactive elements for disseminating tweets, which include "text, branching links, hashtags, digital images, digital videos, digital audio, and digital polls." However, thes
Subjected Find winged bull Assyrian monetary analysis in order to identify the formative relations in terms of percentages, movement and public swab for being aesthetic values upon which the mechanisms of artistic composition, which did not give researchers artistic interest that affects the status of these sculptures and the like of the achievements of the Iraqi civilization in Assyria.
Resulting analysis to a number of the most important results, the percentages approved in the calculation of the parts to do with all when viewed status horizontal with a realistic formulas while in the case of considering frontally clear for Ras stylized proportions and head size larger in length, a ratio confirmed by previous studies, and
... Show MoreThe population studies are one of the difficult tasks facing the world in all periods. most of the researchers and who have relationship to population policies and development plans, may have succumbed to the idea that the population problem is based and confined mainly in the rate of increase in population, or the so – called population explosion, and not the content because of its pressure on resources and there is no problem of population if the resources are available and therefore no need for the development and implementation of population policies in any way . While the population policies here should take a range of general and comprehensive in every respect to population and demographic phenomena distribution, not only
... Show MoreThe present study was conducted to evaluate the effect of different inhibitors on the corrosion rate of aluminum in 50% (v/v) ethylene glycol solution at 80°C and pH 8.0 in which the electrochemical technique of linear sweep voltammetry was employed to characterize each inhibitor function and to calculate the corrosion rate from Tafel plots generated by a computer assisted potentiostat.
It is found that both sodium dichromate and borax reduces the corrosion rate by polarizing the anodic polarization curve while sodium phosphate, potassium phosphate, and sodium benzoate reduces the corrosion rate by polarizing both the anodic and cathodic polarization curve.
When inhibitor concentration increases from I g/l up
... Show More