Background: Reduction in bond strength when bonding was done immediately after intracoronal bleaching procedure has been recognized. The purpose of this study is to assess the effect of antioxidants (10% sodium ascorbate (SA), 0.1M thiourea and7% sodium bicarbonate (SB)) on reversing bonding strength of composite resin to bleached dentin. Materials and method: Sixty upper 1st premolar teeth, were selected, the crowns of the teeth were embedded in acrylic resin blocks exposing a flat dentin from the buccal surface, then divided into 6 groups (10 samples each). Bleaching for the experimental groups was performed using 35% hydrogen peroxide bleaching gel (pola–office).Group A (Negative control group; dentin samples immediately bonded with composite without bleaching)Group B (Positive control group; dentin samples bleached and immediately bonded with composite). Group C (Dentin samples bleached and stored for 14 days in DDW then bonded with composite). Group D (Dentin samples bleached and treated with 10% (SA) then immediately bonded with composite). Group E (Dentin samples bleached and treated with 0.1M thiourea then immediately bonded with composite). Group F (Dentin samples bleached and treated with 7% SB then immediately bonded with composite).The shear bond strength was determine using instron testing machine. Results: Bleaching the dentin with 35 % hydrogen peroxide gel for 24 minutes resulted in reduction in bond strength of the bleached teeth when bonding was performed immediately after bleaching. Delayed bonding of composite to the bleached dentin for 14 days will result in a highly significant increase in the shear bond strength. Conclusion: Treating the bleached dentin with 10% (SA) in water base showed a highly significant increase in the shear bond strength of the composite to dentin and reversing the bond strength value to the level of the unbleached dentin. Treating the bleached dentin with 0.1M thiourea significantly increased the shear bond strength of the composite to dentin.
The paper is concerned with, the behavior of the hydrostatic thrust bearings lubricated with liquid-solid lubricants using Einstein viscosity formula, and taking into account the centrifugal force resulting from high speed. Also studied is the effect of the bearing dimensions on the pressure, flow rate, load capacity, shear stress, power consumption and stiffness.
The theoretical results show an increase in load capacity by (8.3%) in the presence of solid graphite particles with concentration of (16%) by weight as compared with pure oil, with increasing shear stress. .
In general the performance of hydrostatic thrust bearings improve for load carrying capacity, volume flow rate,
... Show MoreThis research studying the phenomenon of Doppler (frequency Doppler) as a method through which the direction and speed of the blood cells flows in blood vessels wear measured. This Doppler frequency is relied upon in medicine for measuring the speed of blood flow, because the blood flow is an important concept from the concepts of medicine. It represents the function and efficient of the heart and blood vessels in the body so any defect in this function will appear as a change in the speed of blood flow from the normal value assumed. As this speed changes alot in cases of disease and morbidity of the heart, so in order to identify the effect of changing the Doppler frequency on the speed of blood flow and the relationship of
... Show MoreTwilight is that light appear on the horizon before sunrise and after sunset, Astronomically it is known that sunrise and sunset are effected by high above sea level, but the effect of high above sea level on the time of astronomical twilight still not decided and controversy among astronomers, in This research we studies the effect of high above sea level on the time of astronomical twilight, through adding the equation correct high above sea level to equation computation of twilight and then calculate of changing in the time of twilight for different highest (0-10000) meters above sea level , and the ratio of increase for time with high between (15.45-20.5) minutes. It was found that there was an increase in the time of the twilight along
... Show MoreMR Younus, Nasaq Journal, 2022
The purpose of this paper is to depict the effect of adding a hydraulic accumulator to a hydraulic system. The experimental work includes using measuring devices with interface to measure the pressure and the vibration of the system directly by computer so as to show the effect of accumulator graphically for real conditions, also the effects of hydraulic accumulator for different applications
have been tested. A simulation analysis of the hydraulic control system using MATLAB.R2010b to study was made to study the stability of the system depending on the transfer function, to estimate the effect of adding the accumulator on stability of the system. A physical simulation test was made for the hydraulic system using MATLAB to show the ef
The importance of internal audit in the growing demand for services in the public and private economic units, and in the rapid growth of its systems professional, has also been recognition of the importance of internal audit quality and the quality of information provided in a long time, as well as the importance of achieving the greatest possible quality in his work to reduce accounting risks of financial reports misleading or fraudulent, which is one of the important features of the audit.
The internal audit quality are linked with the ability of auditors to detect errors in the financial statements, and their willingness to express an opinion technical neutral and non-aligned based on the results of th
... Show MoreThis study includes the direct influence of (single & multi) dose of Cold Atmospheric Plasma (CAP) on the no. of platelets for mice for different exposure time (15, 30, 60, and 120) sec. the influence of CAP on mice was measured after 1, 2, 3, 7, and 14 day from exposure.
The results obtained in this study indicate that the effect of low doses of CAP on platelets was stimulatory effect in the first few hours from exposure (1day) but the high dose was inhibitory, It was found that after two weeks of exposure that the number of platelets became normal comparable to the control one, and this indicates that plasma effect was removed after this period.
Many studies have been made and still concerning the field of translation. Since the mid-90's a considerable amount of researches has tackled the problem of gender and its effect on the process and the product of translation. Simon (1996, p 508) points out that when comparing women and men as translators and writers through history, women seem to be the weaker side. This paves the way to feminist movements which produce prominent studies concerning gender as a concept and translator's gender as practice on the quality and the accuracy of the translation.
Flotow (in Meschia, 2012, p 1-4) outlines several issues that can be
... Show MoreThe world is keeping pace with evolution in all its fields as a result of scientists' pursuit of continuous scientific and technological development. This evolution included the sports field, which had a large space in the aspect of development and for all disciplines, Therefore, it's reflected today in what we see of records and advanced achievements in sporting events and activities. The development in the field of sports was the result of scientific research (Hussein and Jawad., 2022), where the interest in the training process has become one of the most important pillars of the development of achievement (Neamah and Altay., 2020). The shooting sport has also witnessed a remarkable development due to the diversity and development of its
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