Laser etching may be an alternative to acid etching of enamel and dentin. Several characteristics of irradiated dental hard tissues have been considered advantageous, microscopically rough surfaces without demineralization, open dentinal tubules without smear layer production and dentin surface sterilization. The aim of this study is to determine and compare histology the microleakage in class V cavity restored with a light cured composite after conditioning the samples(tooth surface) with 1-acid etching, 2-Q-switched Nd:YAG Laser etching and finally 3- acid and laser etching. Materials and methods: Twenty four non carious human extracted teeth were used in this study. The samples were equally grouped into four groups of six teeth each. A class V cavity was prepared. In group I, tooth surface was etched with a 37% phosphoric acid gel. In group II, the tooth surface was conditioned using a pulsed Nd:YAG Laser alone with a wavelength of 532 nm. The parameters were of pulse energy 60 mJ, pulse repetition rate 6Hz and energy density was 0.48 J/cm2. In group III, the tooth surface was treated with Nd: YAG Laser and then was etched with phosphoric acid. In group IV, the surface was treated with 37% phosphoric acid then irradiated with Nd: YAG Laser; with the same parameters and concentration mentioned in group I and II. The samples immersed in 1% basic fuschin dye to mimic the normal stains in oral cavity and the sections were examined by a stereomicroscope and the readings were scored. Results: The results showed that group IV, in which the surface was treated with 37% phosphoric acid and then irradiated with Nd: YAG Laser) recorded the least microleakage of the four groups, where group III, in which the tooth surface was treated with Nd: YAG Laser and then was etched with phosphoric acid)recorded reasonable results better than group I (group I tooth surface was etched with a 37% phosphoric acid gel) or group II , in which the tooth surface was conditioned using a pulsed Nd:YAG Laser alone) Conclusion: The use of Q-switched Nd:YAG laser in etching the tooth surface was so effective that it can be used in treating or conditioning the tooth surface to enhance bonding and the best parameters among the tested samples were pulse energy of 60mJ, pulse repetition rate of 6Hz and energy density 0.48 J/cm2.
Normal concrete is weak against tensile strength, has low ductility, and also insignificant resistance to cracking. The addition of diverse types of fibers at specific proportions can enhance the mechanical properties as well as the durability of concrete. Discrete fiber commonly used, has many disadvantages such as balling the fiber, randomly distribution, and limitation of the Vf ratio used. Based on this vision, a new technic was discovered enhancing concrete by textile-fiber to avoid all the problems mentioned above. The main idea of this paper is the investigation of the mechanical properties of SCC, and SCM that cast with 3D AR-glass fabric having two different thicknesses (6, 10 mm), and different layers (1,2 laye
... Show MoreIn this study, the modified Rayleigh-Ritz method and Fourier series are used to determine the thermal buckling behavior of laminated composite thin plates with a general elastic boundary condition applied to in-plane uniform temperature distribution depending upon classical laminated plate theory(CLPT). A generalized procedure solution is developed for the Rayleigh-Ritz method combined with the synthetic spring technique. The transverse displacement of the orthotropic rectangular plates is not a different term as a new shape expansion of trigonometric series. In this solution approach, the plate transverse deflection and rotation due to bending are developed into principle Fourier series with a sufficient smoothness auxi
... Show MoreIn composite steel-concrete structures, shear connectors in the form of headed steel studs are commonly utilized to transfer longitudinal shear force developed at the interface between the two materials. To overcome the shortcomings of design codes, which frequently understate shear capacity and fail to take advantage of sophisticated computational methods, this paper presents an optimization attempt to estimate the shear strength of headed steel studs utilizing the Grey Wolf Optimizer (GWO) technique using MATLAB software. Data from 234 experimental tests are employed to identify and highlight key input parameters influencing the shear strength of headed steel studs. These key parameters include concrete compressive strength (f’c
... Show MoreTwo samples of (Ag NPs-zeolite) nanocomposite thin films have been prepared by easy hydrothermal method for 4 hours and 8 hours inside the hydrothermal autoclave at temperatures of 100°C. The two samples were used in a photoelectrochemical cell as a photocatalyst inside a cell consisting of three electrodes: the working electrode photoanode (AgNPs-zeolite), platinum as a cathode electrode, and Ag/AgCl as a reference electrode, to study the performance of AgNPs-zeolite under dark current and 473 nm laser light for water splitting. The results show the high performance of an eight-hour sample with high crystallinity compared with a four-hour sample as a reliable photocatalyst to generate hydrogen for renewable energies.
The present study experimentally and numerically investigated the impact behavior of composite reinforced concrete (RC) beams with the pultruded I-GFRP and I-steel beams. Eight specimens of two groups were cast in different configurations. The first group consisted of four specimens and was tested under static load to provide reference results for the second group. The four specimens in the second group were tested first under impact loading and then static loading to determine the residual static strengths of the impacted specimens. The test variables considered the type of encased I-section (steel and GFRP), presence of shear connectors, and drop height during impact tests. A mass of 42.5 kg was dropped on the top surface at the m
... Show MoreIn this work, the photodetection performance of polyvinyl alcohol (PVA) nanofibers and its composite with yttrium oxide (Y2O3) at different concentrations (2.5, 5, 10) wt% are examined deposited on p-type Si with (111) orientation. Electrospinning technique was used to create nanofiber composites. Adding Y2O3 significantly impacts the PVA nanofibers where ultraviolet-visible (UV-Vis) spectroscopy optical absorption energy gap decreases with increased concentration (2.8, 2.6, and 2.3) eV. X-ray diffraction was used to investigate crystal structure, which is cubic structure. The chemical composition study was conducted using Fourier transform infrared spectroscopy (FTIR) spectra, which revealed the stretching vibrations related to the Y-O bon
... Show MoreIn this investigation, Rayleigh–Ritz method is used to calculate the natural frequencies of rectangular isotropic and laminated symmetric and anti-symmetric cross and angle ply composite plate with general elastic supports along its edges. Each of the admissible functions here is composed of a trigonometric function and an arbitrary continuous function that is introduced to ensure the sufficient smoothness of the so-called residual displacement function at the edges. Perhaps more importantly, this study has developed a general approach for deriving a complete set of admissible functions that can be applied to various boundary conditions. Several numerical examples are studied to demonstrate the accuracy and convergence of the current s
... Show MoreSummary of the researchThe style of playing in basketball, represented by the performance of complex movements as a result of the rapid movement and changing positions is one of the advantages of this game, which adds beauty and excitement to this game, so it was necessary for players to use forms of mobility and complex skills mixed with precision and speed, In the attack to overcome the difficult positions defenders are trying to impose on the attacking team.Complex offensive skills in basketball are difficult skills that a player can not easily perform so they need to be specially trained to handle those situations so that the player can use them in difficult situations.The research community represented a sample of Baghdad players for t
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