Background: In dentistry, dentist takes the advantages of soft lining materials due to the viscoelastic properties. The major problem is the adhesion of the soft liner with the denture base material. Materials and Methods: Heat cured of high impact acrylic resin specimens prepared with dimensions 75x13x13mm for shear bond strength test, soft lining material (Refit and Mollosil) with a 3-mm thickness and used to join each two acrylic blocks. Also four specimens with the same previous dimensions utilized for chemical and physical surface analysis. The specimens grouped as control (without plasma) and experiment (with oxygen plasma) treated high impact acrylic specimens. Results: Plasma treatment increased the shear bond strength for both Refit and Mollosil soft lining material after immersion in distilled water for 30 days as compared with the control group, also there was decrease in shear bond strength for both Refit and Mollosil soft lining material of the experimental group after immersion in denture cleanser for 30 days as compared with the control (without plasma treated) group. AFM analysis revealed that oxygen plasma treatment led to formation of (pits and protuberances) that increase the surface area and increase the shear bond between soft liners and high impact acrylic denture base. Conclusions: Oxygen plasma surface treatment was an effective method for increasing adhesion by physical topographic surface (due to the plasma etching process which in turn led to removal of some material from the surface and this led to increase the bond strength).
ھدف البحث الـــــى : ١ -إعداد تدریبات القوة الارتدادیة في وسطین متباینین على بعض المؤشرات الفسیولوجیة لتطویر القوة الانفجاریة ودقة مھارتي الأرسال والضرب الساحق بالكرة الطائرة . ٢ -التعرف على تأثیر تدریبات القوة الارتدادیة في وسطین متباینین على بعض المؤشرات الفسیولوجیة لتطویر القوة الانفجاریة.. ٣ -التعرف على تأثیر تدریبات القوة الارتدادیة في وسطین متباینین على دقة مھارتي الأرسال والضرب الساحق بالكرة الطائرة
... Show MoreThe research involves using phenol – formaldehyde (Novolak) resin as matrix for making composite material, while glass fiber type (E) was used as reinforcing materials. The specimen of the composite material is reinforced with (60%) ratio of glass fiber.
The impregnation method is used in test sample preparation, using molding by pressure presses.
All samples were exposure to (Co60) gamma rays of an average energy (2.5)Mev. The total doses were (208, 312 and 728) KGy.
The mechanical tests (bending, bending strength, shear force, impact strength and surface indentation) were performed on un irradiated and irrad
... Show MoreBackground: Denture cleansing is an important step that can prevent the spread of infection and improve a patient's health, the durability of the dentures, and the overall quality of life; therefore, it is necessary to choose a suitable cleanser that, in addition to being effective, does not have an unfavorable effect on the qualities of the denture base resin itself when used for an extended period. Aim: This research aims to assess the effects of ozonated water on the surface roughness and hardness of heat-cured acrylic resin by immersion technique. Materials: Sixty bars shapemade of heat-cured acrylicweremanufactured.Thirty samples for every test, including: (surface hardness and surface roughness). Then, these samples were divided into
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Abstract
A two electrode immersion electrostatic lens used in the design
of an electron gun, with small aberration, has been designed using
the finite element method (FEM). By choosing the appropriate
geometrical shape of there electrodes the potential V(r,z) and the
axial potential distribution have been computed using the FEM to
solve Laplace's equation.
The trajectory of the electron beam and the optical properties of
this lens combination of electrodes have been computed under
different magnification conditions (Zero and infinite magnification
conditions) from studying the properties of the designed electron
gun can be supplied with Abeam current of 5.7*10-6 A , electron
gun with half acceptance
Objective(s): This study aims to evaluate the hardness of two commercially available cold cured acrylic resin material
(Vertex and PAN) when polymerized at different temperature in comparison to those polymerized by conventional
methods in air at 23C ± 5C.
Methodology: Eighty specimens, forty from cold cured acrylic (Vertex Type) and forty from cold cured acrylic (PAN
type) were prepared, flasking and packing procedure were done according to manufacturer direction and divided
according to processing as follow: 20 specimens (10 from Vertex type and 10 from PAN type) were processed in air for
two hours at 23C ± 5C under press (bench curing) as a control, and 60 specimens (30 from Vertex type and 30 from
PAN type) wer
research aim :
- The research aimed to investigate the effect of two treatment
methods in the gaining of fourth grade students in geography
object.
- Research hypothesis
there are no statistically significant differences at the level of ( 0.05 )
in the average level of achievement in geography between the first
experimental group ( strengthening lessons ) and the second group
( re- teaching )
no individual differences statically significant at the level of ( 0.05 )
in the average level achievement in geography object of the second
experimental group ( re- teaching ) and the first experimental group
( strengthening lesson )
the research sample : the researcher selected randomly Baghdad
The performance and durability of the asphalt pavement structure mainly depend on the strength of the bonding between the layers. Such a bond is achieved through the use of an adhesive material (tack coat) to bond the asphalt layers. The main objective of this study is to evaluate the effect of moisture in conjunction with repeated traffic loads on the strength of the bonding between asphalt layers using two types of tack coats with different application rates. Using the nominal maximum size of aggregate (NMAS), the layers were graded (25/19) and (19/9.5) mm. The slabs of multilayer asphalt concrete were prepared using a roller compactor using two types of tack coats to bond between layers, namely rapid curing cut back a
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(3)
The behavior and shear strength of full-scale (T-section) reinforced concrete deep beams, designed according to the strut-and-tie approach of ACI Code-19 specifications, with various large web openings were investigated in this paper. A total of 7 deep beam specimens with identical shear span-to-depth ratios have been tested under mid-span concentrated load applied monotonically until beam failure. The main variables studied were the effects of width and depth of the web openings on deep beam performance. Experimental data results were calibrated with the strut-and-tie approach, adopted by ACI 318-19 code for the design of deep beams. The provided strut-and-tie design model in ACI 318-19 code provision was assessed and found to be u
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(6)
(8)
To achieve sustainability, use waste materials to make concrete to use alternative components and reduce the production of Portland cement. Lime cement was used instead of Portland cement, and 15% of the cement's weight was replaced with silica fume. Also used were eco-friendly fibers (copper fiber) made from recycled electrical. This work examines the impact of utilizing sustainable copper fiber with different aspect ratios (l/d) on some mechanical properties of high-strength green concrete. A high-strength cement mixture with a compressive strength of 65 MPa in line with ACI 211.4R was required to complete the assignment. Copper fibers of 1% by volume of concrete were employed in mixes with four different aspect ratios
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(6)
The research in the variables of the political process and government stability tried to show the impact of the political process on political stability first, and then on government stability second, given that the political process that was established in 2005 was aimed at achieving legitimacy, and its most prominent tools are elections, leading to achieving political stability, including government stability. The issue of governmental stability is one of the important issues in Iraq, but it has not been achieved, as a result of several factors, including problems in political action, as the political process has not succeeded in leading Iraq to stability.