Background: Polymethyl methacrylate (PMMA) is the most commonly used material in denture fabrication. The material is far from ideal in fulfilling the mechanical requirements. Midline fracture; poor thermal conductivity and water sorption, are common problem in this material. The purpose of this study was to evaluate the effect of addition of surface treated Aluminum oxide nano fillers on some properties of heat cured (PMMA). Materials and methods: In addition to controlled group of heat cured PMMA the silanized (Al2O3) nanoparticles was added to PMMA powder by weight in three different percentages 1wt%, 2wt% and 3wt%, mixed by probe ultra-sonication machine. 200 specimens were constructed and divided into 5 groups according to the test (each group consist of 40 specimens) and each group was subdivided into 4 sub-groups. The tests conducted were thermal conductivity, thermal diffusivity, transverse strength, indentation hardness (shore D), surface roughness, water sorption and solubility. The results were statistically analyzed using ANOVA and Dunntt t-test. Results: A highly significant increase in transverse strength was observed with the addition of (Al2O3) nanoparticles to (PMMA) at the percentage of 1wt%, the value was 117.72 Mpa and significant increase at 2wt%; while a significant reduction occurred in transverse strength at the percentage of 3% the value was 90.110 Mpa. A significant increase in surface hardness and non significant differences in surface roughness were observed for all percentages. Conclusion: The addition of Al2O3 nanoparticles to acrylic resin improves the thermal properties and transverse strength of acrylic resin at the same time this addition decreases water sorption and solubility.
Free Radical Copolymerization of Styrene/ Methyl Methacrylate were prepared chemically under Nitrogen ,which was investigated, in the present of Benzoyl Peroxide as Initiator at concentration of 2 × 10-3 molar at 70 °C, which was carried out in Benzene as solvent to a certain low conversion . FT-IR spectra were used for determining of the monomer reactivity ratios ,which was obtained by employing the conventional linearization method of Fineman-Ross (F-R) and Kelen-Tüdos (K- T). The experimental results showed the average value for the Styrene r1 / Methyl Methacrylate r2 system, Sty r1 = 0.45 , MMA r2 = 0.38 in the (F–R) Method and r1 = 0.49 , r2 = 0.35 in the (K–T) Method, The Results of this indicated show the random distri
... Show MorePVA:PEG/MnCl2 composites have been prepared by adding (MnCl2) to the mixture of the poly vinyl alcohol (PVA) and poly ethylene glycol (PEG) with different weight percentages (0, 2, 4, 6, 8 and 10) wt.% by using casting method. The type of charge carriers, concentration (nH) and Hall mobility (μH) have been estimated from Hall measurements and show that the films of all concentration have a negative Hall coefficient. In D.C measurement increase temperature leads to decrease the electrical resistance. The D.C conductivity of the composites increases with the increasing of the concentration of additive particles and temperature. The activation energy decreases for all composites with increasing the concentration of the additive particles.
... Show MoreAchieving goals effectively reflects the success of the institution. However, unless this indicator is coupled with efficiency when achieving goals, the institution will be equal in its achievements, and distinction will remain unachieved. Perhaps the role of the teaching staff in pushing the institution or college towards brilliance focuses on their ability to motivate people on the one hand and their interest in achieving brilliance for the institution. On the other hand, the importance of the research lies in the institution’s reaching a prominent position through the brilliance and creativity of teaching and achieving competition between institutions that make it more brilliance. The study seeks to achieve the goal of the real
... Show MoreSeeds of Nigella sativa were sown in containers containing 15kg Loamy soil. The seeds were divided before sewing into two groups. The first group was soaked with ordinary tap water end the second group was treated with magnetized water for 24hrs. The irrigation process was completed until 75% of capacity field with two types of water (tap water of magnetized water with three replications).The magnetized water was obtained from special electric device designed for this purposeRecorded measurements (plants height, the number of branches/ plant, dry weight ofplant, number of flowers, 1000 seed weight) during the harvest period.Results indicated that the seed group which was treated with magnetized water was more significant than the one which
... Show More؛ ١٨his study male and female albino mice werdministr^d doses of alkaloid and phenolic extracts of Allium cepa at doses of( 25 ,50,100, 200) mg / kg of( body weight). males and females were divided into four groups and each croup comprised mice were injected intra^ritonially daily for one week and orally ٢٠٢ one month . After which animals were killed and the serum was separated for biochemical analysis (total blood suger, total protein , otal cholesterol). Results showed significant decrease ( p< 0,05) in the total blood suger and total cholesterol on the serum of both males and females and significant increase( p< 0,05) in the total serum protein of both males and females of the two types of injection and oral administr
... Show MoreAim: To evaluation the effect of Lactobacillus acidophilus on Enterohemorrhagic Escherichia coli (EHEC) serotype O157:H7 with detection of some virulence factors. Methods: Two hundred and fifty specimens (stool) from children under five years for both sexes were collected from some hospitals. All isolates were diagnosed according to morphological characteristics, biochemical tests. Monoplex pattern of PCR was used also for detection different genes in (7) Escherichia coli )O157:H7 (isolates; include 16SrRNA, eae, lifA, Stx1,Stx2 that encoded for ribosomal RNA, intimin, lymphocyte inhibitory factor, shiga toxins. Three types of probiotics strains were obtained, Lactobacillus fermentum, Lactobacillus plantarum and Lactobacillus acidophilus (A
... Show MoreThermal energy storage is an important component in energy units to decrease the gap between energy supply and demand. Free convection and the locations of the tubes carrying the heat-transfer fluid (HTF) have a significant influence on both the energy discharging potential and the buoyancy effect during the solidification mode. In the present study, the impact of the tube position was examined during the discharging process. Liquid-fraction evolution and energy removal rate with thermo-fluid contour profiles were used to examine the performance of the unit. Heat exchanger tubes are proposed with different numbers and positions in the unit for various cases including uniform and non-uniform tubes distribution. The results show that
... Show MoreGoal of research is to investigate the impact of the use of effective learning model in the collection of the fourth grade students/Department of physics in the material educational methods and the development of critical thinking .to teach this goal has been formulated hypothesis cefereeten zero subsidiary of the second hypothesis .To investigate the research hypothesis were selected sample of fourth-grade students of the department of physics at the univers
... Show MoreThis investigation was carried out to examine the effect of replacing partial of flour by dried Lentils (Lens culinaris) to white flour in different percentages on the chemical, sensory and storage properties of the Laboratory bread. The results revealed that replacing 0% than wheat flour by lentil powder (1) control was high significan than the replacing 25 and 35% than wheat flour by lentil powder ( 4 and 5) in flavor and chewiness . The results of sensory evaluation showed that replacing 4 were high significan different than that of replacing 1 in external layer colour. Other replacing percentages, however, did not show significant differences of in comparison with control . In regards with chemical analysis of Iron and copper, i
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