Background: Crown preparation of vital teeth involve the removal of a sound tooth structure, and when enamel removed this lead to exposed dentin with an increase in the number of open dentinal tubules also the diameter of dentinal tubules will increase, furthermore lead to increase movement of fluids inside the tubules all that causes post preparation sensitivity. The aim of this study is to evaluate the effect of desensitizing by Er:Cr:YSGG laser on shear bond strength of prepared tooth and resin cement. Materials and methods: Thirty sound maxillary premolars, grouped into three groups(n=10). Group A is the control group, group B irradiated by Er:Cr:YSGG laser with (0.25 W, 20 Hz, 10%water and air), group C irradiated by Er:Cr:YSGG laser with (0.5 W, 20 Hz, 10% water and air). Results: SEM examination showed complete occlusion of opened dentinal tubules after laser irradiation of both groups that irradiated with laser. Statistical analysis showed significant increase in surface roughness in group B and C. SBS was significantly increase in group B with no significant increase in group C. Conclusion: Er:Cr:YSGG laser can occlude open dentinal tubules without and adverse effect on the retention of the restoration, on the contrary it increase bonding strength. And this increasing was significant in group B with (0.25W, 20 Hz, 10 % water and air). suggestion: so the parameters used in group B (0.25 W, 20Hz, 10 % water and air) is recommended for desensitizing prepared tooth and induce enhancement to the bonding strength of resin to tooth surface.
Speech is the essential way to interact between humans or between human and machine. However, it is always contaminated with different types of environment noise. Therefore, speech enhancement algorithms (SEA) have appeared as a significant approach in speech processing filed to suppress background noise and return back the original speech signal. In this paper, a new efficient two-stage SEA with low distortion is proposed based on minimum mean square error sense. The estimation of clean signal is performed by taking the advantages of Laplacian speech and noise modeling based on orthogonal transform (Discrete Krawtchouk-Tchebichef transform) coefficients distribution. The Discrete Kra
During the two last decades ago, audio compression becomes the topic of many types of research due to the importance of this field which reflecting on the storage capacity and the transmission requirement. The rapid development of the computer industry increases the demand for audio data with high quality and accordingly, there is great importance for the development of audio compression technologies, lossy and lossless are the two categories of compression. This paper aims to review the techniques of the lossy audio compression methods, summarize the importance and the uses of each method.
The quality of Global Navigation Satellite Systems (GNSS) networks are considerably influenced by the configuration of the observed baselines. Where, this study aims to find an optimal configuration for GNSS baselines in terms of the number and distribution of baselines to improve the quality criteria of the GNSS networks. First order design problem (FOD) was applied in this research to optimize GNSS network baselines configuration, and based on sequential adjustment method to solve its objective functions.
FOD for optimum precision (FOD-p) was the proposed model which based on the design criteria of A-optimality and E-optimality. These design criteria were selected as objective functions of precision, whic
... Show MoreThe study presents the test results of Completely Decomposed Granite (CDG) soil tested under drained triaxial compression, direct shear and simple shear tests. Special attention was focused on the modification of the upper halve of conventional Direct Shear Test (DST) to behave as free
head in movement along with vertical strain control during shear stage by using Geotechnical Digital System (GDS). The results show that Free Direct Shear Test (FDST) has clear effect on the measured shear stress and vertical strain during the test. It has been found that shear strength
parameters measured from FDST were closer to those measured from simple shear and drained triaxial compression test. This study also provides an independent check on
Givers of foreign Audit about Social Responsibility of Profit Organization. The recent time is charcterstically with big economic Organization activities, because there are many transactions between these Organizations and different financial markets development techniques.
This encourgage business men to increase their efforts for investment in these markets. Because the Accounting is in general terms it represents a language of these Unions Activities and translate them in to fact numbers, for that there is need for Accounting recording for certain of these Organizations behavior and their harmonization with their Objectives.
In this respect the Audit function comes to che
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These experiments seek to investigate the effects of the fixed variations to the basic box plot on subjects' judgments of the box lengths. The study consists of two experiments, were constructed as an extension to the experiments carried out previously by Hussin, M.M. (1989, 2006). Subjects were asked to judge what percentage the shorter represented of the longer length in pairs of box lengths and give an estimate of percentage, one being a standard plot and the other being of a different box length and also varying with respect to other elements such as, box width or whisker length. When he (1989) suggested in the future research points (1, 2), the changing length of the st
... Show More. The concepts of structural flexibility became one of the important goals in the design phases to reach high performance in architecture. The pioneering projects and ideas that linked architecture with technologies and scientific innovations appeared, with the aim of reaching projects that mix the concepts of flexibility with the development of machine thought and modern technology to meet the functional, environmental, and aesthetic requirements for human wellbeing. The aim of this paper is to identify the mechanisms used in order to reach flexible structural systems capable of accommodating technological changes and developments. The research hypothesizes that the structural design according to the concepts of flexibility achieves high s
... Show MoreMercury is a heavy metal that is extremely toxic. There are three types of it: inorganic, organic, and elemental. Mercury in all its forms has been shown to have harmful effects on living things. It can multiply its concentration from lower to higher trophic levels and accumulate in the body's various tissues. Aquatic organisms bodies have been exposed to mercury mostly through various human activities. The largest source of mercury pollution in the air is thermal power plants that mostly use coal as fuel. It is carried to a body of water after being deposited on the ground surface from the air. The way it enters the food chain is through aquatic plants and animals. Mercury accumulations in the kidney, liver, gills, or gonadal tissues of sp
... Show MoreThis paper presents the results of the slope failure analyses from fracture distributions and their relation to tectonic activity; the analytical results have indicated that the phenomena of plane failure, wedge failure and toppling failure can occur at almost of the survey sites within the study area.
The statistical data show that the fracture orientation mainly develop in the E-W, N-S and NW-SE due to the influence of tectonic activity. The occurrence of them together with the rock slope surface orientation has formed plane failure on the slope surface of the 3B highway in the E-W direction and the types of wedge failure and toppling failure on the slope surface of the highw
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