The influence of fiber orientation and water absorption on fatigue crack growth resistance for cold cure acrylic (PMMA) reinforced by chopped and woven -glass-fibers were investigated. A weight of 2 g for chopped fibers and the same weight for woven -glass-fibers (one layer) were used to prepare samples. Some of these samples would storage in dry condition; the others were immersed in water for 15 days. Fatigue test was carried out. The results shows that, for PMMA, the initial bending stress for dry specimen was 3.392 N/cm2 and the number of cycles were 1364, the initial bending stress for wet samples was 4.20 N/cm2, and the number of cycles was 2411. The samples would cut in two pieces because of the cracks would propagated fast during

The current investigation examines the combined impacts of ultrasonic radiation and hydrogen donors on the viscosity of heavy crude oil. The impact of exposure time, power, duty cycle, and temperature on the viscosity of Iraqi heavy crude oil with 20.32 API was studied. Also, the viscosity of the oil samples, which were mixed with a hydrogen donor (decalin) and subjected to ultrasonic treatment under optimal conditions, was examined to evaluate the combined impact of ultrasonic radiation and hydrogen donor on the viscosity of crude oil. The viscosity experienced a decrease of 52.34% at 2 min of irradiation, 360 W ultrasonic power, 0.8 duty cycle, 35 ⁰C, and 8vol% decalin. To validate the outcomes of the experiments, asphaltene content, s

The effect of Wood Flour addition to the gamma alumina powder used in the preparation of gamma alumina (ɤ-Al₂O₃) catalyst carrier extrudates on the pore volume and BET surface area physical properties was investigated. Two parameters which are size of wood flour particles and its quantity were studied. The sizes of wood flour particles used are 150 µm, 212 µm and 500 µm and the weight percentage added to the gamma alumina powder during the preparation of the extrudates are (1%, 3%, 5% and 10%). The results showed that the addition of wood flour to the gamma alumina powder in order to get gamma alumina extrudates used as catalyst carrier is one of the successful methods to improve the pore volume

Lithium-rich layered oxide cathodes have attracted considerable attention due to their high energy density, but have suffered from voltage drop, structural instability, and limited electrical conductivity. In this study, the electrochemical performance of the lithium-rich cathode material Li[Li0.20Mn0.54Ni0.13Co0.13]O2 was evaluated after modification by zinc doping and composition with graphene oxide or graphene. The zinc-doped powders were synthesized by the sol-gel method, while the graphene-based composites were prepared by the hydrothermal route. The structural, morphological and electrochemical characteristics of the modified materials were examined using X-ray diffraction, Fourier transform infrared spectroscopy, field emission scann

ABSTRACT Background: Color changes that are detectable to human eye can affect the esthetic appearance of ceramic veneers. The purpose of this study was to evaluate and compare the effect of artificial accelerated aging on the color of ceramic veneers cemented with different resin cements. Materials and Methods: Sixty discs were prepared with 0.5 mm thickness, 30 discs made from IPS e.max press (Ivoclar Vivadent) and 30 discs were made from VITA Enamic (VITA Zahnfabrik). The discs were cemented with three resin cements: Variolink Veneer MV 0 shade (Ivoclar Vivadent), Rely X veneer Translucent shade (3M ESPE) and NX3 Nexus Clear shade (Kerr Corporation) with 0.1 mm thickness. The spectrophotometer Easyshade Advance was used to measure the co

Sustainable crop production in a coarse soil texture is challenging due to high water permeability and low soil water holding capacity. In this paper, subsurface water retention technology (SWRT) through impermeable polyethylene membranes was placed at depth 35 cm below ground surface and within the root zone to evaluate and compare the impact of these membranes and control treatment (without using the membranes) on yield and water use efficiency of eggplant inside the greenhouse. The study was conducted in Al-Fahamah Township, Baghdad, Iraq during spring growing season 2017. Results demonstrated the yield and water use efficiencies were 3.483 kg/m² and 5.653 kg/m³, respectively for SWRT treatment p

Background: Sealers should demonstrate adhesive properties to dentin, decreasing the chance of endodontic treatment failure. Increased adhesive properties to dentin may lead to greater strength of the restored tooth, which may provide greater resistance to tooth fracture and clinical longevity of an endodontically treated tooth. The aim of this study was to evaluate the shear bond strength of Bioceramic iRoot SP sealer, AH plus sealer and Apexit plus sealer in absence or presence of smear layer using push out bond strength test. Materials and Methods: Sixty straight single roots of the mandibular premolars were selected for this study. All canals were instrumented using ProTaper rotary instruments to achieve tapered canal walls, instrumenta

The research problem lies in: The use of positive and negative flexibility exercises to develop the special strength of the 400m hurdles player, that some young people face weakness and a problem in performance, which requires the need to prepare special exercises for physical and skill numbers using the types of exercises that have resilient strength, flexibility and have the effect on developing and determining the level of physical and skill performance. To develop 400m hurdles, special strength, explosive power and the characteristic velocity of arms and legs. Research aims: 1. Preparing positive and negative flexibility exercises to develop the special force and the effectiveness of 400m youth barriers. 2. Identify the effect of exerci