In this research the effect of cooling rate and mold type on mechanical properties of the eutectic
and hypoeutectic (Al-Si) alloys has been studied. The alloys used in this research work were (Al- 12.6%Si
alloy) and (Al- 7%Si alloy).The two alloys have been melted and poured in two types of molds with
different cooling rates. One of them was a sand mold and the other was metal mold. Mechanical tests
(hardness, tensile test and impact test) were carried out on the specimens. Also the metallographic
examination was performed.
It has been found that the values of hardness for the alloys(Al-12.6%Si and Al-7%Si) which poured in
metal mold is greater than the values of hardness for the same alloy when it poured in a heated metal
mold at different temperatures or in sand mold. The strength and impact resistance for the alloys (Al-
12.6%Si and Al-7%Si) are greater when these were poured in a metal molds than that when it poured in a
sand mold.
Furthermore, the higher cooling rates enhance the strength, hardness and impact resistance for the
two alloys, while the low cooling rates reduces these mechanical properties.
The percentage of elongation and the amounts of formed porosity decreased when the cooling rates
increased
The dangers of (Israel's) integration with Arab countries in the middle east region will threaten the Arab security structure dimension, which the latter makes the Arab regional system vulnerable for distortion due to its nominal and symbolic value which is far from the Arab self and questioning with its effectiveness in comparing with the real capabilities to Arab countries in achieving the common targets. So, how to assess the different problems that began to hit the structure of the Arab regional system? and how to pledge an allegiance after putting forward what is known as the American Deal of the Century for the administration of former US President Donald Trump for making another step toward normalization with (Israel)?. The reveal
... Show MoreThis research aims to predict the value of the maximum daily loss that the fixed-return securities portfolio may suffer in Qatar National Bank - Syria, and for this purpose data were collected for risk factors that affect the value of the portfolio represented by the time structure of interest rates in the United States of America over the extended period Between 2017 and 2018, in addition to data related to the composition of the bonds portfolio of Qatar National Bank of Syria in 2017, And then employing Monte Carlo simulation models to predict the maximum loss that may be exposed to this portfolio in the future. The results of the Monte Carlo simulation showed the possibility of decreasing the value at risk in the future due to the dec
... Show MoreThe present paper focuses on examining the style of both the civilized dialogue of Prophet Hud (PBUH) in the Glorious Qur'an, and the debated dialogue of Aad’s people. The study consists of an introduction which shows the importance of the civilized dialogue and its significant impact on containing, accepting, and persuading the other in peaceful ways without intolerance and violence. Then, the conditions and techniques of the civilized dialogue and its types have been mentioned. This is followed by the practical side of the study, which involves examining stylistically the techniques used in Hud’s (PBUH) civilized dialogue to be invested later in people’s future conversations. It is also concerned with investigating stylistically
... Show MoreBackground: Irrigation of the canal system permits removal of residual tissue in the canal anatomy that cannot be reached by instrumentation of the main canals so the aim of this study was to compare and evaluate the efficiency of conventional irrigation system, endoactivator sonic irrigation system,P5 Newtron Satelec passive ultrasonic irrigation and Endovac irrigation system in removing of dentin debris at three levels of root canals and to compare the percentage of dentin debris among the three levels for each irrigation system. Materials and methods: Forty extracted premolars with approximately straight single root canals were randomly distributed into 4 tested groups of 10 teeth each. All canals were prepared with Protaper Universal ha
... Show MoreBackground: Ischemic heart disease is a major cause of the diastolic heart failure. Risk of heart failures was increased with microvascular coronary disease, which is characterized by left ventricular stiffness with impaired relaxation and reduced compliance. Aim of this study is to estimate the effect of the severity of myocardium ischemia on the left ventricle ejection fraction and left ventricular volume using SPECT with 99mTc MIBI and to compare the results with the echocardiography. The study included 117 subjects with ischemic heart disease were examined using SPECT and echocardiography techniques. The following
... Show MoreIn this study, from a total of 856 mastitis cases in lactating ewes, only 34 Streptococcus agalactiae isolates showed various types of resistance to three types of antibiotics (Penicillin, Erythromycin and Tetracycline). St. agalactiae isolates were identified according to the standard methods, including a new suggested technique called specific Chromogenic agar. It was found that antibiotic bacterial resistance was clearly identified by using MIC-microplate assay (dilution method). Also, by real-time PCR technique, it was determined that there were three antibiotics genes resistance ( pbp2b, tetO and mefA ). The high percentage of isolate carried of a single gene which was the Tetracycline (20.59%) followed by percentage Penicillin was
... Show MoreArgumentation is not a contemporary, yet a deep rooted intellectual phenomenon dates back to Romans and Greeks times. The argumentative elements ,the author is trying to convey to the reader, are linguistic procedures aim at persuading and being persuaded of what is true. The present study traces, through Camus’ novel The plague, the best method to construct argumentative techniques used to express the author’s deep philosophies.
Résumé
L’argumentation n’est pas un phénomène intellectuel nouveau, ses origines reviennent aux savants grecs et romains. Elle est une act
... Show MoreAcute Respiratory Distress Syndrome (ARDS) causes up to 40% mortality in humans and is difficult to treat. ARDS is also one of the major triggers of mortality associated with coronavirus-induced disease (COVID-19). We used a mouse model of ARDS induced by Staphylococcal enterotoxin B (SEB), which triggers 100% mortality, to investigate the mechanisms through which Δ9-tetrahydrocannabinol (THC) attenuates ARDS. SEB was used to trigger ARDS in C3H mice. These mice were treated with THC and analyzed for survival, ARDS, cytokine storm, and metabolome. Additionally, cells isolated from the lungs were used to perform single-cell RNA sequencing and transcriptome analysis. A database analysis of human COVID-19 patients was also performed t
... Show MoreIn the current work, the mixing ratios ( 𝛿 ) of gamma transitions were calculated from energy levels in the isotopes neodymium 60𝑁𝑎 142−150 populated in the 60Nd 142− 150 (n, n ˊγ) 60Nd 142− 150 using the 𝑎2 ratio method. We used the experimental coefficient (𝑎2 ) for two γ-transitions from the initial state itself, the statistical tensor 𝜌2(𝐽𝑖), associated with factor 𝑎2 , would be the same for the two transitions. The results obtained are in good agreement or within the experimental error with -those previously published. And existing contradictions resulting from inaccuracies in the empirical results of previous work. The current results confirm that the , 𝑎2 − method is used to calculate th
... Show More