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Effect of ageing media on shear bond strength of metal orthodontic brackets bonded with different adhesive systems (A comparative in-vitro study)
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Background: The aim of this study was to evaluate the shear bond strength (SBS) and adhesive remnant index (ARI) of different orthodontic adhesive systems after exposure to aging media (water storage and acid challenge). Materials and methods: Eighty human upper premolar teeth were extracted for orthodontic purposes and randomly divided into two groups (40 teeth each): the first group in which the bonded teeth were stored in distilled water for 30 days at 37°C, and the second group in which the bonded teeth were subjected to acid challenge. Each group was further subdivided into four subgroups (10 teeth each) according to the type of adhesive system that would be bonded to metal brackets: either non-fluoride releasing adhesive (NFRA), fluoride releasing adhesive (FRA), Fluoride releasing bond with self-etching primer (FRBSP), or powder and liquid orthodontic fluoride releasing adhesive (PLFRA). After 30 days of water storage and acid challenge ageing procedures, the SBS was determined using Instron testing machine with a crosshead speed of 1 mm/min. The ARI was assessed using a stereomicroscope with 10 X magnification. Result: The SBS testing revealed significant differences (p< 0.05) among the four tested adhesive systems in water storage and acid challenge groups using ANOVA F-test. In both groups, the NFRA subgroup exhibited the highest mean SBS value, followed by FRASP, then FRA subgroups, while the PLFRA subgroup had the lowest value of mean SBS. The independent t-test showed non-significant differences in mean SBS values between water storage and acid challenge groups. In respect to the ARI analysis, the Chi-square test showed significant differences among the tested adhesive systems. Conclusion: The shear bond strength of the fluoride releasing adhesive system was less than that of the non-fluoride releasing adhesive system, but still above the clinically acceptable range.

 

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Publication Date
Mon Jan 11 2021
Journal Name
Engineering, Technology & Applied Science Research
The Effect of Low Velocity Impact Loading on SelfCompacting Concrete Reinforced with Carbon Fiber Reinforced Polymers
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t-Self-Compacting Concrete (SCC) reduces environmental noise and has more workability. This research presents an investigation of the behavior of SCC under mechanical loading (impact loading). Two types of cement have been used to produce SCC mixtures, Ordinary Portland Cement (OPC) and Portland Limestone Cement (PLC), which reduces the emission of carbon dioxide during the manufacturing process. The mixes were reinforced with Carbon Fiber Reinforced Polymer (CFRP) which is usually used to improve the seismic performance of masonry walls, to replace lost steel reinforcements, or to increase column strength and ductility. Workability tests were carried out for fresh SCC. Prepared concrete slabs of 500×500×50mm were tested for lo

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Publication Date
Fri Jan 01 2021
Journal Name
Aip Conference Proceedings
Integration between hydrochemical and physical data with geographic information systems (GIS) for selecting the best locations groundwater wells in Baghdad city
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Publication Date
Tue Dec 01 2009
Journal Name
Iraqi Journal Of Physics
Study the Effect of the High Voltage on The preparation of Polyvinyl Alcohol/ Tio2 Nano Fiber by Electrospinning
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Abstract:In this research we prepared nanofibers by electrospinning from poly (Vinyl Alcohol) / TiO2. The spectrum of the solution (Emission) was studied at 772 nm. Several process parameter were Investigated as concentration of PVA, the effect of distance from nozzle tip to the grounded collector (gap distance), and final the effect of high voltage. We find the optimum condition to prepare a narrow nanofibers is at concentration of PVA 16gm, the fiber has 20nm diameter.

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Publication Date
Mon Jan 01 2018
Journal Name
Journal Of Engineering And Applied Sciences
Study the effect of Ultraviolet radiation on the optical properties of pure PC and anthracene doping PC films
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The aim of the present research is concerned with study the effect of UV radiation on the optical properties at wavelengths 254, 365 nm of pure PC and anthracene doping PC films prepared using the cast method for different doping ratio 10-60 mL. Films of pure PC and anthracene doping PC were aged under UV radiation for periods of up to 360 h. It found that the effect of UV radiation at wavelength 254 nm on the optical properties is great than the effect of UV radiation at wavelength 365 nm. Also, it found that the optical energy gap of pure PC and anthracene doping PC films is stable against radiation.

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Publication Date
Wed Dec 30 2009
Journal Name
Iraqi Journal Of Physics
Study the Effect of the High Voltage on The preparation of Polyvinyl Alcohol/ Tio2 Nano Fiber by Electrospinning
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In this research we prepared nanofibers by electrospinning
from poly (Vinyl Alcohol) / TiO2. The spectrum of the solution
(Emission) was studied at 772 nm. Several process parameter were
Investigated as concentration of PVA, the effect of distance from
nozzle tip to the grounded collector (gap distance), and final the
effect of high voltage. We find the optimum condition to prepare a
narrow nanofibers is at concentration of PVA 16gm, the fiber has
20nm diameter

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Publication Date
Sun Apr 08 2018
Journal Name
Al-khwarizmi Engineering Journal
Study the Effect of Welding Heat Input on the Microstructure, Hardness, and Impact Toughness of AISI 1015 Steel
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In the present study, MIG welding is carried out on low carbon steel type (AISI 1015) by using electrode ER308L of 1.5mm diameter with direct current straight polarity (DCSP). The joint geometry is of a single V-butt joint with one pass welding stroke for different plate thicknesses of 6, 8, and 10 mm. In welding experiments, AISI 1015 plates with dimensions of 200×100mm and edge angle of 60o from both sides are utilized. In this work, three main parameters related to MIG welding process are investigated, which are welding current, welding speed, heat input and plate thickness, and to achieve that three groups of plates are employed each one consists of three plates. The results indicate that increasing the weld heat input (t

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Publication Date
Wed Jul 01 2020
Journal Name
Journal Of Engineering
Study the Effect of Catalyst -to- Oil Ratio Parameter (COR) on Catalytic Cracking of Heavy Vacuum Gas Oil
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This work deals with the production of light fuel cuts of (gasoline, kerosene and gas oil) by catalytic cracking treatment of secondary product mater (heavy vacuum gas oil) which was produced from the vacuum distillation unit in any petroleum refinery. The objective of this research was to study the effect of the catalyst -to- oil ratio parameter on catalytic cracking process of heavy vacuum gas oil feed at constant temperature (450 °C). The first step of this treatment was, catalytic cracking of this material by constructed batch reactor occupied with auxiliary control devices, at selective range of the catalyst –to- oil ratio parameter (  2, 2.5, 3 and 3.5) respectively.  The conversion of heavy vacuum gas

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Publication Date
Tue Oct 02 2018
Journal Name
Iraqi Journal Of Physics
Study of effect acidic solution (HCl) and (EP/Al2O3 & EP/ TiO2) hybrid on thermal conductivity of epoxy resin.
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This research studies the effect of adding micro, nano and hybrid by ratio (1:1) of (Al2O3,TiO2) to epoxy resin on thermal conductivity before and after immersion in HCl acid for (14 day) with normality (0.3 N) at weight fraction (0.02, 0.04, 0.06, 0.08) and thickness (6mm). The results of thermal conductivity reveled that epoxy reinforced by (Al2O3) and mixture (TiO2+Al2O3) increases with increasing the weight fraction, but the thermal conductivity (k) a values for micro and Nano (TiO2) decrease with increasing the weight fraction of reinforced, while the immersion in acidic solution (HCl) that the (k) values after immersion more than the value in before immersion.

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Publication Date
Sun Feb 24 2019
Journal Name
Iraqi Journal Of Physics
Study the effect of gamma radiation on the some properties of glass and glass-ceramic immobilize nuclear waste
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Vitrifications process one of the important methods to immobilize nuclear waste.  In this research nuclear waste (Strontium Oxides) with molecular weight (5%) was immobilized by vitrification methods in two types of borosilicate glass (c-type) which are glass and glass-ceramics. To investigate the physical, chemical and mechanical properties of glass and glass-ceramic after immobilize nuclear waste these samples irradiated by gamma ray radiation. Co-60 was used as gamma a irradiation with dose rate 0.38 kGy/hr for different period of time. It’s found that gamma radiation affected the glass and glass-ceramic properties. From phase analysis by the x-ray diffraction for glass-ceramic samples proved that at doses 343kGy change the cry

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Publication Date
Sat Jun 01 2019
Journal Name
Prensa Medica Argentina
The effect of niclosamide in acetic-acid induce colitis: An experimental study
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