Background: This in vitro study was carried out to investigate the effect of post space regions (coronal, middle and apical), the effect of post types ( Manually Milled Zirconia post, Prefabricated Fiber post, prefabricated Zirconia post) and the type of cement used (GIC, self-adhesive resin cement) on the bond strength between the posts and root dentin by using push-out test. Material and methods: Forty eight mandibular premolars extracted for orthodontic reasons (single rooted) were instrumented with ProTaper system (hand use) and obturated with gutta percha for ProTaper using AH26® root canal sealer following the manufacturer instructions. After 24 hours, post space was prepared using Zirix and Glassix drills no.3 creating 8 mm depth post space. The prepared samples were randomly divided into three main groups (16 samples each) according to the type of post used (Group A. Manually Milled Zirconia post, Group B. Prefabricated Fiber post and Group C. Prefabricated Zirconia post) .each group was subdivided into two subgroups (each subgroup contains 8 samples) according to the type of cement used (subgroup A1.Manually Milled Zirconia post cemented with GIC, subgroup A2.Manually Milled Zirconia post cemented with Speed cem),( subgroup B1.Prefabricated Fiber post cemented with GIC, Group B2. Prefabricated Fiber post cemented with Speed cem) and (subgroup C1.Prefabricated Zirconia post cemented with GIC, subgroup C2. Prefabricated Zirconia post cemented with Speed cem), after cementation and incubation for 24hrs, at 37°c and 100% humidity. Each root was sectioned horizontally into 3 slices (2 mm in thickness) representing the coronal, middle and apical regions of the post space. Push out bond strength test was performed and measured using a universal testing machine (Tinius-Olsen) at across head speed of 0.5 mm/min. Results: The results showed that regarding the root region, the bond strength values increased significantly from apical to coronal region for all types of posts in both tested cements. For the effect of post type, the manually Milled Zirconia post cemented with the self-cured resin cement (Speed cem) showed higher bond strength values. For type of cement, the self-adhesive resin cement (Speed cem) showed higher bond strength values. Conclusions: the retention of post restoration was affected by root region, type of post and type of cement used.
Introduction: This study was performed to compare the effect of Fractional CO2 laser or Q switched Nd:YAG laser of surface treatment on the shear bond strength of zirconia-porcelain interface. Methods: Fractional CO2 laser at 30 W, 2 ms, time interval 1 ms, distance between spots 0.3 mm, and number of scans is (4) or Q switched Nd:YAG laser at 30 J/mm2 and 10 Hz were used to assess the shear bond strength of zirconia to porcelain. Pre-sintered zirconia specimens were divided into three groups (n = 10) according to the surface treatment technique used: (a) untreated (Control) group; (b) CO2 group; (c) Nd:YAG group. All samples were then sintered and veneered with porcelain according to the manufacturer’s instructions. Surface morph
... Show MoreIn this research, the performance of electrocoagulation (EC) using aluminum (Al) electrodes with Monopolar- parallel (MP-P), and bipolar - series (BP-S) arrangement for simultaneous removal of dissolved silica, and hardness ions (calcium, and magnesium) from synthetic blowdown water of cooling tower were investigated. The effects of current density, initial pH and time of electrolysis on the removal efficiency were studied in a batch stirred unit to find out the best-operating conditions. The obtained results for each target species are evidence that BP-S approach is the best for both electrodes configuration operated at a Current density of 1mA/cm2 through 30 min of treatment and pH=10 with the removal of
... Show MoreThis paper presents a sight about the chemical structure deformation of poly (ethylene-co-vinyl acetate) (EVA) samples according to the change ratio of rate constant values. Spectroscopy kinetics fluorescence curves are fitted for two characteristic wavelength domains of fluorescent intensities. The short wavelengths (320-400 nm) domain show spectra overlapping, while at long wavelengths (400-800 nm) domain spectra are arranged in regular for each specific accelerated aging time. The ratio of kinetics rate constant at long wavelengths to kinetics rate constant of short wavelengths is the criterion of the degree chemical structure deformation. Molar extrin
... Show MoreThe aim of this study was to determine the effect of different dietary fat on carcass traits in Japanese quail (Coturnix coturnix japonica). A total of 168 7-week-old Japanese quail (48 males and 120 females) were used in this study. They were evenly distributed into 4 treatment groups, with 3 replicates per group containing 4 males and 10 females each. The birds were fed a basal diet with different fats (sunflower, flax, corn, and fish oils) at a 3% level for 13 weeks. On the last day of the experiment, 12 birds were randomly selected from each treatment group (6 males and 6 females) and slaughtered to determine carcass characteristics included in this study, which were carcass weight, dressing percentage with or without giblets, and the r
... Show MoreThe use of worn-out agricultural nozzles in pesticide application has a negative effect on the efficiency and cost of the application process. It also has an effect on environmental pollution due to an excessive amount of pesticide being applied when spraying with worn-out nozzles. In this paper, the resistance to wear of three different internal design hydraulic nozzles was ascertained. Changes in the flow rate and spray distribution as a result of this wear were also investigated. The wear test was done inside a closed system, and it was accelerated using an abrasive material to generate 100 h of wear. The tested nozzles were the Turbo TeeJet (TT)-twin chambered, Turbo Twinjet (TTj60)-dual outlet, and Drift Guard (DG)-pre-orifice.
... Show MoreThe hydraulic conditions of a flow previously proved to be changed when placing large-scale geometric roughness elements on the bed of an open channel. These elements impose more resistance to the flow. The geometry of the roughness elements, the numbers used, and the configuration are parameters that can affect the hydraulic flow characteristics. The target is to use inclined block elements to control the salt wedge propagation pointed in most estuaries to prevent its negative effects. The Computational Fluid Dynamics CFD Software was used to simulate the two-phase flow in an estuary model. In this model, the used block elements are 2 cm by 3 cm cross-sections with an inclined face in the flow direction, with a length
... Show MoreIn this paper, Pentacene based-organic field effect transistors (OFETs) by using different layers (monolayer, bilayer and trilayer) for three different gate insulators (ZrO2, PVA and CYEPL) were studied its current–voltage (I-V) characteristics by using the gradual-channel approximation model. The device exhibits a typical output curve of a field-effect transistor (FET). Source-drain voltage (Vds) was also investigated to study the effects of gate dielectric on electrical performance for OFET. The effect of capacitance semiconductor in performance OFETs was considered. The values of current and transconductance which calculated using MATLAB simulation. It exhibited a value of current increase with increasing source-drain voltage.
Hydrate dissociation equilibrium conditions for carbon dioxide + methane with water, nitrogen + methane with water and carbon dioxide + nitrogen with water were measured using cryogenic sapphire cell. Measurements were performed in the temperature range of 275.75 K–293.95 K and for pressures ranging from 5 MPa to 25 MPa. The resulting data indicate that as the carbon dioxide concentration is increased in the gas mixture, the gas hydrate equilibrium temperature increases. In contrast, by increasing the nitrogen concentration in the gas mixtures containing methane or carbon dioxide decreased the gas hydrate equilibrium temperatures. Furthermore, the cage occupancies for the carbon dioxide + methane system were evaluated using the Van der Wa
... Show MoreThe absorption spectrum for three types of metal ions in different concentrations has been studying experimentally and theoretically. The examination model is by Gaius model in order to find the best fitting curve and the equation controlled with this behavior. The three metal ions are (Copper chloride Cu+2, Iron chloride Fe+3, and Cobalt chloride Co+2) with different concentrations (10-4, 10-5, 10-6, 10-7) gm/m3. The spectroscopic study included UV-visible and fluorescence spectrum for all different concentrations sample. The results refer to several peaks that appear from the absorption spectrum in the high concentration of all metal ions solution.
... Show MoreThis research aims to find how three different types of mouthwashes affect the depth of artificial white spot lesions. Teeth with various depths of white spot lesions were immersed in either splat mouthwash, Biorepair mouthwash, Sensodyne mouthwash, or artificial saliva (control)twice daily for one minute for 4 weeks and 8 weeks at 37°C. After this immersion procedure, lesion depth was measured using a diagnosed pen score. A one-way analysis of variance, Dunnett T3 and Tukey's post hoc α = .05 were used to analyze the testing data. Splat mouthwash enhanced the WSL remineralization and made the lowest ΔF compared with other mouthwashes in shallow and deep enamel after 4 and 8 weeks of treatment. In the repair groups, after 4 weeks
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