Background: Denture relining is the process of resurfacing of the tissue side of the ill fitting denture, the bond strength at the relining-denture base interface is most important for denture durability.The aim of present study was to evaluate the shear bond strength between the thermosens as relining material and different denture base materials that bonded by thermo fusing liquid. As this corrective procedureis the common chair side procedure in the dental clinic. Material and method: Sixty samples were prepared and divided into three main groups according to the type of denture base materials.Group (A) referred to the heat cure acrylic samples which consisted of 20 samples. Group (B) referred to the high impact acrylic samples which consisted of 20 samples. Group (C) referred to the thermosens samples which consisted of 20 samples. All groups then subdivided into two groups; each one consists of 10 samples, according to the surface roughness: (A1, B1and C1 for groups with surface roughness and A2, B2 and C2for groups without surface roughness). Each sample consisted of two similar parts represent the denture base material each part of the sample was designed with dimensions of (70mm X 12mm X 5mmlength, width and depth respectively) having a stopper of depth 3mm. One part of the sample was placed on the other in a manner thatleaving a space between them of dimensions (12mm X 12mm X 3mm length, width and depth respectively) to sandwich the relining material. Results: The results showed that the thermosens samples had the highest value of shear bond strength followed by the high impact acrylic samples, then heat cure acrylic samples which had the lowest value of shear bond strength. The results of present study showed that rough samples had reducedshear bondstrength in comparison with the smooth samples of the same denture base material.
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Heat transfer process and fluid flow in a solar chimney used for natural ventilation are investigated numerically in the present work. Solar chimney was tested by selecting different positions of absorber namely: at the back side, front side, and at the middle of the air gap. CFD analysis based on finite volume method is used to predict the thermal performance, and air flow in two dimensional solar chimney under unsteady state condition, to identify the effect of different parameters such as solar radiation. Results show that a solar chimney with absorber at the middle of the air gap gives better ventilation performance. A comparison between the numerical and previous experimental results shows fair agreement.
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The behaviour of the electrical conductivity (σ) and the activation energies (Ea1, Ea2) have been investigated on a-InAs thin films as a function of thickness (250,350,450,550,650) nm, before and after heat treatment. The films were annealed at (373, 423, 473) K for one hour. The films contain two types of transport mechanisms, and the electrical conductivity (σ) increases whereas the activation energy (Ea) would decrease as the films thickness increases.
In this work the corrosion behavior of Ti-6Al-4V alloy was studied by using galvanostatic measurements at room temperature in different media which includ sodium chloride (food salt), sodium tartrate (presence in jellies, margarine, and sausage casings,etc.), sodium oxalate (presence in fruits, vegetables,etc.), acetic acid (presence in vinegar), phosphoric acid (presence in drink), sodium carbonate (presence in 7up drink,etc.), and sodium hydroxide in order to compare.
Corrosion parameters were interpreted in th
... Show MoreIn this paper a two dimensional numerical simulation have been applied using
MATLAB program for generating Fraunhofer diffraction pattern from different
apertures. This pattern is applied for three types of apertures, including, circular,
square, and rectangular functions, and it's could be generated any wavelength in the
visible light. The studying demonstrated the capability and the efficiency of optical
imaging systems to observe a point source at very long distance. The circular
aperture shows better results across the shape of Fraunhofer pattern and optical
transfer function (otf). Also, the minimum values of the normalized irradiance of
different diffracted apertures have been computed at different dimension
Background: Coated aesthetic archwires are currently the existing solutions for the esthetic problem, but the color of these archwires tends to change overtime. This study was aimed to evaluate the color stability of different types of esthetic archwires from four different companies at different time periods after immersion of two different staining drinks which are tea and Pepsi cola. Materials and methods: 48 specimens were prepared, each specimen contains 10 aesthetic archwires; and were divided according to type of solution into two groups: A (tea) &B (Pepsi cola); each group contained 24 specimens (12 specimens were immersed in the staining solution as 4 specimens for each time intervals and 12 specimens were immersed in distilled wa
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In all process industries, the process variables like flow, pressure, level, concentration
and temperature are the main parameters that need to be controlled in both set point
and load changes.
A control system of propylene glycol production in a non isothermal (CSTR) was
developed in this work where the dynamic and control system based on basic mass
and energy balance were carried out.
Inlet concentration and temperature are the two disturbances, while the inlet
volumetric flow rate and the coolant temperature are the two manipulations. The
objective is to maintain constant temperature and concentration within the CSTR.
A dynamic model for non isothermal CSTR is described by a first order plus dead
time (FO