Background: The polymethyl methacrylate is the most reliable material for the construction of complete and partial dentures, despite satisfying esthetic demand itsuffered from having unsatisfactory properties like impact strength and transverse strength. This study was designed to improve the impact strength and transverse strength of heat cure acrylic resin by adding untreated and oxygen plasma treated polypropylene fibers and investigate the effect of this additive on some properties of acrylic resin materials. Materials and methods: Untreated and oxygen plasma treated polypropylene fibers was added to PMMA powder by weight 2.5 %. Specimens were constructed and divided into 5 groups according to the using tests; each group was subdivided in to 3 subgroups. The tests conducted were impact strength, transverse strength, surface hardness, surface roughness, water sorption and solubility. Data were analyzed by one way analysis of variance (ANOVA) and least significant differences (LSD). Results: After incorporation of untreated and oxygen plasma treated polypropylene fibers there was a highly significant increase in impact strength and surface hardness; while there was a non significant difference in transverse strength. Also the value of water sorption increase significantly but with the limit of ADA specification. Conclusion:Within the limit of this study it can be concluded that the reinforcement with polypropylene fibers effective method to increase fracture resistance of denture base; while reinforcement with oxygen plasma treated polypropylene fibers further increase fracture resistance.
The effect of micro-and nano silica particles (silica SiO2 (100 μm), Fused silica (12nm)) on some mechanical properties of epoxy resin was investigated (Young's modulus, Flexural strength). The micro-and nano composites were prepared by using three steps process with different volume fraction of micro-and nano particles (1, 2, 3, 4, 5, 7, 10, 15, and 20 vol. %). Flexural strength and Young's modulus of nano composites were increased at low volume fraction (max. enhancement at 4 vol.% ). However at higher volume fraction both Young's modulus and flexural strength decrease. Moreover, above, the mechanical properties are enhanced more than that of neat epoxy resin. The flexural strength decreases with increasing the volume fraction of micr
... Show MoreThe refractive indices, nD densities 𝜌, and viscosities of binary mixtures of sulfolane + n -butanol + sec- butanol + iso- butanol + tert – butanol + n-propanol and iso- propanol were measured at 298.15K. Form experimental data, excess molar volum VE , excess molar refractivity ∆nD, excess molar viscosity E and excess molar Gibbs free energy of activation of viscous flow G *E were calculated. From n-propanol – sulfolane and iso- propanol sulfolane mixtures showed negative ∆nD, n-butanol – sulfolane, sec-butanal – sulfolane, iso-butanol – sulfolane and tert- butanol sulfolane , nD was positive over the whole mole fraction rang , while VE , E and G *E show a negative deviation. The
... Show MoreSelf-compacted concrete (SCC) considered as a revolution progress in concrete technology due to its ability for flowing through forms, fusion with reinforcement, compact itself by its weight without using vibrators and economic advantages. This research aims to assess the fresh properties of SCC and study their effect on its compressive strength using different grading zones and different fineness modulus (F.M) of fine aggregate. The fineness modulus used in this study was (2.73, 2.82,2.9& 3.12) for different zones of grading (zone I, zone II& marginal zone(between zone I&II)) according to Iraqi standards (I.Q.S No.45/1984).Twelve mixes were prepared, each mix were tested in fresh state with slump, V-Funnel and L-Box tests, t
... Show MoreSelf-compacted concrete (SCC) considered as a revolution progress in concrete technology due to its ability for flowing through forms, fusion with reinforcement, compact itself by its weight without using vibrators and economic advantages. This research aims to assess the fresh properties of SCC and study their effect on its compressive strength using different grading zones and different fineness modulus (F.M) of fine aggregate. The fineness modulus used in this study was (2.73, 2.82,2.9& 3.12) for different zones of grading (zone I, zone II& marginal zone(between zone I&II)) according to Iraqi standards (I.Q.S No.45/1984).Twelve mixes were prepared, each mix were tested in fresh state with slump, V-Funnel and L-Box tests, then 72
... Show MoreIn the present study, the effect of Zinc nanoparticles on levels of (T3 , T4 and TSH) hormones was investigated. Zinc nanoparticles were synthesized by Laser induced plasma.The Nd: YAG Nd: YAG laser with a wavelength of 1064 nm was used to generate nanomaterials of the elements (zinc) upon collision with target atoms. Plasma generated by different laser intensity is generated. After confirming the preparation of zinc nanoparticles, XRD, AFM was examined, and the effect of these substances on the thyroid gland (T3, T4, TSH) was observed for two doses of each component (1 ml / kg, 4 ml / kg) after conducting a cytotoxicity examination of the lymphocytes of the rats extracted from Rat spleen was 1.8% less toxic to zinc, and as noted The
... Show MoreThis Study aimed to studying the effect of Volatile oil extracted from the leaves of Myrtus communis on the growth and activities of the following types of bacteria: Staphylococcus aureus, Streptococcus pyogenes, Klebsilla pneumoniae, Pseudomonas aeruginosa, and the yeast Candida albicans. The results showed an inhibitory effect of the oil on both the growth and activity of the tested microbes. This was reflected by the minimum inhibitory concentration (MIC) of Staphylococcus aureus, Streptococcus pyogenes, Klebsilla pneumoniae, Pseudomonas aeruginosa which was: (2.5, 1.25, and 2.5,5 % respectively), and the yeast (5) %. Also, the Minimum bactericidal concentration (MBC) to the bacteria mentioned above was (5, 2.5,5,10 % respectivel
... Show MoreO estudo destaca a necessidade crítica de se focar nas capacidades físicas, motoras e técnicas das jogadoras de esgrima, desenvolvendo e testando metodologias de treino modernas, baseadas na ciência, adaptadas às exigências específicas do desporto. O objetivo do estudo foi avaliar a eficácia do treino tridimensional visando melhorar as capacidades motoras e o desempenho técnico dos participantes. Recorrendo a um desenho experimental, o estudo envolveu a formação de grupos experimentais e de controlo. A amostra incluiu 16 esgrimistas da Faculdade Feminina de Educação Física e Ciências do Desporto. Após a exclusão de dois jogadores durante a fase exploratória, os restantes 14 foram divididos igualmente em grupos experimental
... Show More