The ceramic compound Mg1-xSixAl2O4 (x= 0, 0.1, 0.2, 0.3, 0.4) was prepared from nano powder of Al2O3 and MgO doped with Nano powder of SiO2 at different molar ratios. The specimens were prepared by standard chemical solid reaction technique and sintered at 1450 oC. Structure of the specimens was analyzed by using X-ray diffraction (XRD). The X-ray patterns of the specimens showed the formation of pure simple cubic spinel structure MgAl2O4 phase with space group of ̅ . The average grain size and surface topology were studied by atomic force microscopy. The results showed that the average grain size was about 73-90 nm. The DC electrical properties of the specimen were measured. The apparent density was found to increase and the porosity and water absorption were found to decrease with increase of Si addition. Mechanical properties were characterized by Vicker’s micro hardness and Brazilian fracture test to measure the fracture toughness of the samples. The micro hardness decreased with Si addition increase. Fracture toughness increased with the increase in Si addition.
The current problem is summarized in what is called the development failing experience
in comprehencing the studying materials , so the students will feel worry of repeating failure
in he future , so he would seek blind keeping on heart for the studying material bond this isbad due to the forgetting in the future , one side of thesis research problem is that there is
many contradictory researches result in relation to the learning styles which impose the
nessicity to find results lessen this contradiction . the importance of the research is
summarized in the importance of the subject under the study , in that the researcher ( as in
her knowledge ) did not find a thesrs tackling the subject of the distinguished students
Deconstructionism opened the door wide to multiple readings and restore the reader his authority that he lost in the modernism, thus became more able to decipher the plastic discourse through reconstruction according to what he wants or what the plastic discourse gives him of possibilities beyond consumerism and thus the author has been canceled. The problem of the current research is limited to the following question: does deconstructionism in postmodern arts have a role in teaching the artistic tasting for the learner? The aim of the current research is to reveal the deconstruction work mechanisms in postmodern arts and their role in teaching the artistic tasting for the learner. As for the theoretical framework, the first section focu
... Show MoreBackground: Automobile spray painting is considered an occupation with a high risk of respiratory impairment and asthma. Exposure to organic solvents used for spraying might be of high risk for development of dysfunction in other organs.
Objective: The study was designed to evaluate the pulmonary and hepatic toxicity due to exposure of automobile painters to organic solvents in work places within the Baghdad governorate area.
Methods: Thirty cross sectional selected male workers employed in automobile body paint shops in two industrial areas within Baghdad city (Al-Sheikh Omar and Al-Rasheed camp regions) were recruited to the study during the period from March to May 2012. Thirty non-exposed students and employees in the college o
Liquid – liquid interface reaction is the method for
preparation nanoparticles (NP'S) which depend on the super
saturation of ions that provide by using the system that consist from
toluene and water, the first one is above the second to obtain
nanoparticles (NP's) CdS at the interface separated between these
two immiscible liquid. The structure properties were characterized by
XRD-diffraction and transmission electron microscopy.
The crystalline size estimate from X-ray diffraction pattern
using Scherer equation to be about 7nm,and by TEM analysis give us
that ananosize is about 5 nm which give a strong comparable with
Bohr radius. Photoluminescence analysis give two emission peak,
the first one around
Effect of antioxidants (vitamins C and E) (500mg/kg) was studied on function of testes in albino mice treated with hexavalent chromium (1000ppm). The results showed that exposure to hexavalent chromium caused a significant decrease in body weights, without changes in weight of testes, seminal vesicles and prostate. A significant decrease was observed in the percentage of dead sperms, sperms abnormalities, diameter of seminiferous tubules and the number of leydig cells. Degenerative changes and necrosis were observed in the lumen of seminiferous tubules. Treatment of hexavalent chromium-exposed mice with vitamin C caused improvement in weights and characters of sperms and improvement of the tissue of seminiferous tubules. Tre
... Show MoreA reinforced concrete frame is referred as "RIGID FRAMES". However, researches indicate that the Beam-Column joint (BCJ) is definitely not rigid. In addition, extensive research shows that failure may occur at the joint instead of in the beam or the column. Joint failure is known to be a catastrophic type which is difficult to repair.
This study was carried out to investigate the effect of hoops and column axial load on the shear strength of high-strength fiber reinforced Beam-Column Joints by using a numerical model based on finite element method using computer program ANSYS (Version 11.0). The variables are: diameter of hoops and magnitude of column axial load.
The theoretical results obtained from ANSYS program are in a good a
Coating materials have an extraordinarily high use, for industrial or technical applications. This study compares the effect of short glass and polypropylene fibers on the hardness, water absorption and anti-bacterial activity of acrylic composites against Gram positive (Streptococcus sp.) and Gram negative bacteria (E.coli, Pseudomonas aeruginosa, Klebsiella sp.).To prepare acrylic polymer and acryliccomposites (glass fibers and polypropylene fiber) the weight fraction (20 %,) (v0= lama acrylic, v1= lama acrylic/ glass fiber, and v2= lama acrylic /poly propylene fiber), of chopped glass fibers and polypropylene were added to acrylic , the resultant solution was stirred by hand for 5 minutes, using the Hand-lay-up technique.
Results s
This research studies the effect of adding micro, nano and hybrid by ratio (1:1) of (Al2O3,TiO2) to epoxy resin on thermal conductivity before and after immersion in HCl acid for (14 day) with normality (0.3 N) at weight fraction (0.02, 0.04, 0.06, 0.08) and thickness (6mm). The results of thermal conductivity reveled that epoxy reinforced by (Al2O3) and mixture (TiO2+Al2O3) increases with increasing the weight fraction, but the thermal conductivity (k) a values for micro and Nano (TiO2) decrease with increasing the weight fraction of reinforced, while the immersion in acidic solution (HCl) that the (k) values after immersion more than the value in before immersion.
The experiment was carried out in the wooden canopy in the green garden of Biology Department , College of Education for Pure Science – Ibn AL –Haitham, Baghdad University, during the growing season of 2012- 2013 , to study the influence of foliar application of three concentrations of zinc (0,50,75)mg. L ¯¹ with four concentrations of boron (0, 25, 50, 75) mg. L¯¹ and their interactions on some growth parameters of vegetative part of chickpea plant. The experiment was designed according to Randomized Completely Block Design(RCBD)with three replications, results indicated that:- 1- Foliar application of zinc and boron caused a significant increase in the averaye of dry weight for t
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