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.
Background: The aim of this study was to evaluate and compare the apical microleakage around retrograde cavities prepared with ultrasonic technique and filled with (Biodentineâ„¢) Materials and methods: 40 extracted single rooted human permanent maxillary teeth with mature apices were selected. The roots were prepared chemo-mechanically using k-files with crown-down technique and then obturated with lateral condensation gutta-percha technique. Teeth were divided into four main groups according to the cavity preparation method either manual or ultrasonic technique: Group A (n=10): A class I retrograde cavity at root end was prepared with traditional handpeice equipped and placement of Biodentine with manual condensation. Group B (n=10):
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Measuring the level of communicative competence in news headlines and the level of stylistic and semantic processing in its formulation requires creating a quantitative scale based on the bases on building the scales and their standards. As judging by scientific of journalism studies lies in the possibility of quantifying the journalistic knowledge, i.e. the ability of this knowledge to shift from qualitative language to its equivalent in the language of numbers.
News headlines and editorial processing are one of the journalistic knowledges that should be studied, analyzed stylistically and semantically; their conclusions drawn and expressed in numbers. Press knowledge is divided into two types:<
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The plethora of the emerged radio frequency applications makes the frequency spectrum crowded by many applications and hence the ability to detect specific application’s frequency without distortion is a difficult task to achieve.
The goal is to achieve a method to mitigate the highest interferer power in the frequency spectrum in order to eliminate the distortion.
This paper presents the application of the proposed tunable 6th-order notch filter on Ultra-Wideband (UWB) Complementary Metal-Oxide-Semiconductor (CMOS) Low Noise
Gabriel Garcia Marquez, the Nobel laureate of literature in 1982, is one of the most famous Latin American writers who have been distinguished by the magic of realism. We can say the months in the world and he is almost the most controversial for many reasons and for these reasons he did not accept that his novels turn into movies Marquez agreed to turn one of his most important and most beautiful novels, "Love in the Time of Cholera," which he wrote in 1985 and agreed to convert to a film in 2006 after the novel was bought by the author for $ 3 million. Mike Noel to bring out
Cooling towers is one of the most important unit in industry, they are used to dispose heat from cooling media used in the integrated units. The choice of the cooling media plays recently an important rule due to fresh-water scarcity. The use of saline as a cooling media become of growing interest, but the corrosion problem has to be taken in consideration. In this study the simultaneous effect of cooling tower operation parameters on the corrosion rate of mild-steel is considered. The role of NaCl content is found to be pronounced more than the working solution temperature and flowrate. The corrosion of mild-steel in these studied factors had shown an interesting result especially with the NaCl% content. Firstly, there was an increase in t
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a porentioncsisteve has been carried out of the corrosion behavior of inconel(600) in chloride ions (Cl) over the tempreatures 293 over the temperatures 308K in both the dcacrated and the alloy
The inhibitive power of Polyvinyl Alcohol (PVA) was investigated toward the corrosion of carbon steel in 0.2N H2SO4 solution in the temperature range of 30-60˚C and PVA concentration range of 150-2000 ppm.
The corrosion rate was measured using both the weight loss and the electrochemical techniques. The weight loss results showed that PVA could serve as a corrosion inhibitor but its inhibition power was found to be low for the corrosion of carbon steel in the acidic media. Electrochemical analysis of the corrosion process of carbon steel in an electrochemical corrosion cell was investigated using 3-Electrode corrosion cell. Polarization technique was used for carbon steel corrosion in 0.2N H
The characteristics of sulfur nanoparticles were studied by using atomic force microscope (AFM) analysis. The atomic force microscope (AFM) measurements showed that the average size of sulfur nanoparticles synthesized using thiosulfate sodium solution through the extract of cucurbita pepo extra was 93.62 nm. Protecting galvanized steel from corrosion in salt media was achieved by using sulfur nanoparticles in different temperatures. The obtained data of thermodynamic in the presence of sulfur nanoparticles referred to high value as compares to counterpart in the absence of sulfur nanoparticles, the high inhibition efficiency (%IE) and corrosion resistance were at high temperature, the corrosion rate or weig
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The inhibitor property of curcuma longa L. extract in different concentrations of simulated refinery wastewater (0.05% - 2% wt) and at various temperatures (30, 35 and 40 ˚C) was investigated using weight loss method. The results showed that the presence of about 1.2 % (v/v) of curcuma extract gave about 84% inhibition indicating its effectiveness on mild steel corrosion in simulated refinery wastewater, besides the adsorption process on the mild steal surface obeyed the Langmuir adsorption isotherm.
Hypothyroidism is a condition in which thyroid hormones levels decreased in the blood. These hormones are necessary for energy production and body viability. In many occasions this condition is accompanied or followed by different metabolic disorders. The current study is conducted in the "Specialized center for endocrinology and diabetes" and carried on 70 hypothyroid patients and 60 randomly chosen individuals with normal thyroid function .Both groups were submitted to laboratory tests to evaluate thyroid function (T3,T4.TSH). The study involved evaluation of the relationship between hypothyroidism and insulin resistance (IR) . Health problem related to many diseases , became common lately. Insulin resistance diagnosed through
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