Background: The aim of this study was to evaluate and compare the static frictional forces produced by monocrystalline ceramic (sapphire) bracket and polycrystalline ceramic bracket. Materials and methods: one hindered twenty brackets/segment of archwire combinations were used, each bracket/segment of archwire combination was tested 10 times. The tests were performed in a universal testing Instron machine. The data was submitted to in depended t-test. Results: The independent sample t-tests showed a highly significant difference in the static frictional forces between monocrystalline ceramic (sapphire) bracket and polycrystalline ceramic bracket. Conclusion: According to the biomechanical result gained from the present study, the monocrystalline ceramic (sapphire) brackets produced lower static friction level than polycrystalline ceramic bracket.
Reinforcing asphalt concrete with polyester fibers considered as an active remedy to alleviate the harmful impact of fatigue deterioration. This study covers the investigation of utilizing two shapes of fibers size, 6.35 mm by 3.00 mm and 12.70 mm by 3.00 mm with mutual concentrations equal to 0.25 %, 0.50 % and 0.75 % by weight of mixture. Composition of asphalt mixture consists of different optimum (40-50) asphalt cement content, 12.50 mm nominal aggregate maximum size with limestone dust as a filler. Following the traditional asphalt cement and aggregate tests, three essential test were carried out on mixtures, namely: Marshall test (105 cylindrical specimens), indirect tensile strength test (21 cylindrical specimens)
... Show MoreObjective: The present work was undertaken to investigate the impact of sub inhibitory concentration of gentamicin on hla gene expression in methicillin resistant Staphylococcus aureus isolates. Methods: The bacterial isolates used in this study represent 33 MRSA strains, previously isolated form patients visiting several hospitals in Baghdad. Gentamicin, vancomycin, and oxacillin MIC were determined using broth dilution method. Microtiter plate method was adopted to investigate the biofilm forming capacity. Alpha hemolysin was detected by culturing MRSA isolates on rabbit blood agar. Furthermore, hla gene was detected in MRSA isolates using conventional PCR technique; while, qRT-PCR method was performed to assay the hla expression in plank
... Show MorePseudomonas aeruginosa is the most common opportunistic pathogen causing morbidity and mortality in hospitalized patients due to its multiple resistance mechanisms. Therefore, as a therapeutic option becomes restricted, the search for a new agent is a preference. So P. aeruginosa is an extremely versatile Gram-negative bacterium capable of thriving in a broad spectrum of environments, and this performs main problems to workers in the field of health. One hundred and fifty samples were collected from different sources from Baghdad hospitals, divided into two main groups: clinical (100) specimens and (50) samples as an environmental, collected from October 2019 to the March 2020. All of these samples were cultured by specific and differential
... Show MoreOne of the most important challenges facing the designers of the sewerage system is the corrosion of sewers due to the influence of sewerage contaminates which lead to failure of the main lines of sewers. In this study, a reference mix of 1: 1.5: 3 was used and the 4% Flocrete PC200 by weight of cement was added to the same mixing ratio in the second mixture. Twenty-four samples were tested for each mixture, 12 of which were used to compression strength test in ages (7, 14 and 28) day and six samples were submerged after 28 days of wet treatment at (5 and 10) % concentrations of sulfuric acid. The other six samples were painted after 28 days of wet treatment with coating Polyurethane and after 24 hours were flooded with a concentrat
... Show MoreChemical resistance ceramic tiles and mortar to alkali solution are prepared and characterized in this study due to the lack of this kind of publications in ceramic literature. Most of the utilized materials are readily available raw materials and the other materials are available commercially. Physical and mechanical properties are measured and indicate that the prepared ceramic tile and mortars are competitive to traditional building materials. Chemical resistance test against alkali solution is also performed by subjecting test specimens to 10%NaOH liquid for two weeks. The results give no indication of chemical attack to specimens of ceramic tile and mortar. The results are discussed and important conclusions are drawn to encourage c
... Show MoreA total of 291 specimens were obtained from hospitalized and out patients. They were 10-70 years old, males and females suffering from burn wound infections, during the period29/4/2007–29/9/2007. InAl-Karekh-surgical-hospital&Al-Kadhemiatechinghospital The most common single isolated pathogen was Pseudomonas aeruginosa %38.6 , Escherichia coli %23.7 Klebsiella spp. %12.2 , Staphylococcus spp. %2.19 and Proteas spp. %1.32. As mixed isolates Pseudomonas aeruginosa and Escherichia coli %12.3, Pseudomonas aeruginosa and Klebsiella spp. %0.9 were found. The study isolats were highly resistant to chloromphenicol %10 Tobromycin %97.43, Gentamycin %87.14, Garamycin %83, Pipracellin %83, Penicillin %
... Show MoreCorrosion Resistance Enhancement for low carbon steel is very important to extend its life service, the coating process is one of the methods which can using to achieve this, and it's the most important in surface treatments to improve the properties of metals and alloys surfaces such as corrosion resistance. In this work, low carbon steel was nitrided and coated with nano zinc using gas phase coating technical, to enhance the resistance of corrosion. The process included adding two layers. The first, a nitride layer, was added by precipitating nitrogen (N) gas, and the second, a zinc (Zn) layer, was added by precipitating Zn. The process of precipitating was carried out at different periods (5, 10, and 15 minutes). Scan electron mi
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This work involves studying corrosion resistance of AA 6061T6 butt welded joints using Two different welding processes, tungsten inert gas (TIG) and a solid state welding process known as friction stir welding, TIG welding process carried out by using Rolled sheet of thickness6mm to obtain a weld joint with dimension of (100, 50, 5) mm using ER4043 DE (Al Si5) as filler metal and argon as shielding gas, while Friction stir welding process carried out using CNC milling machine with a tool of rotational speed 1000 rpm and welding speed of 50mm/min to obtain the same butt joint dimensions. Also one of weld joint in the same dimensions subjected to synergistic weld
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