An experimental investigation of natural convection heat transfer from an isothermal horizontal,vertical and inclined heated square flat plates with and without circular hole, were carried out in two cases, perforated plates without an impermeable adiabatic hole "open core" and perforated plates with an impermeable adiabatic hole "closed core" by adiabatic plug. The experiments covered the laminar region with a range of Rayleih number of (1.11x106 ≤RaLo≤4.39x106 ), at Prandtle number (Pr=0.7). Practical experiments have been done with variable inclination angles from horizon (Ф=0o ,45o,90o,135oand 180o),facing upward (0o≤Ф<90o), and downward (90o
≤Ф<180o). The results showed that the temperature gradient increases while the thermal boundary layer thickness decreases when Grashof number and perforation ratio (m) increase . The temperature gradient for inclined position facing upward is less than facing downward,while the thermal boundary layer thickness is greater. The temperature gradient decreases while the thermal boundary layer thickness increases for perforated plates with an adiabatic core as compared with perforated plates without an adiabatic core. The value of average Nusselt number increases with increasing perforation ratio, and Grashof number for all specimens with and without an adiabatic core, also increases by increase in inclination of plates approaching the higher value at vertical position (Ф=90o
), then decreases with increasing inclination of plates till horizontal position (Ф=180o). The average Nusselt number values for perforated plates with an adiabatic core are lower than for perforated plates without an adiabatic core for all perforation ratios. Maximum heat transfer rate occurs at perforated plate with perforation ratio of (m=0.1) without adiabatic core for vertical position (Ф=90o), at a range of Grashof number (1.576x106≤GrLo≤6.292x106 ), while the rate of heat transfer decreases with increasing perforation ratio for plates with and without adiabatic core for decrease in heat transfer rate area. The rate of heat transfer for
perforated plates with circular hole is more than for perforated plates with square hole at the same perforation ratios (m=0.1,0.16,0.24 and 0.36). It found that the lack of core flow decreases the overall heat transfer rate by (6.477%) . There was a good agreement for the experimental present work results compared with other pervious results .
Abstract
The research aims to measure the level of critical thinking skills among students of A’Sharqiah University in the Sultanate of Oman, as well as identify the level of their availability based on the variables: gender, academic level, school year, cumulative average, and general diploma / high school ratio. The researchers used the descriptive approach. To achieve the objectives of the study, they used The California Test for Critical Thinking Skills Picture (A) after evaluation (Farraj, 2006). It was applied to a sample of (487) students from A’sharqiah University. The results of the study found that the critical thinking skills of A’sharqiah University students are below the educationally acceptabl
... Show MoreThe understanding exchange rate policy is fundamental in order to identify the mechanism by which works out macroeconomic, And the vital for macroeconomic analysis and empirical work to differentiate between the de facto regimes and de jure regimes, Where the proved surveys and studies issued by the international monetary fund that there is divergence between the de facto regime (Regime of exchange applied by the country actually) and between the de jure regime (Regime de jure through the documents and formal writings of officials of the central bank), And launched studies on the de facto regime (Being a the basis of evaluating monetary policy) Stabilized (peg-like)arrangements or
... Show MoreHerein, a cost-effective bio approach using extract derived from desert truffles (Tirmania nivea) is utilized to synthesize gold nanoparticles (AuNPs). AuNPs were thoroughly investigated using UV–vis, XRD, SEM, and TEM analyses. It was shown that nanoparticles had an fcc structure with a smooth spherical surface, an average diameter of 9.44 ± 0.26 nm, and an SPR band observed at 548 nm. Investigations were conducted on AuNPs' antibacterial and anti-cancer properties of prostate cancer cells. The findings suggest that AuNPs showed better antibacterial effects against S. aureus compared to E. coli, P. aeruginosa, and K. pneumoniae. AuNPs’ combination with antibiotics demonstrated a synergistic effect with significant antibacterial activi
... Show MoreIn the present study, the growth and total lipid contents of two oleaginous fungal isolates Aspergillus terreus, Aspergillus fumigatus were compared in different nitrogen and organic carbon sources. Artificially the fungi were cultured on media consisting of various mono- or di- or polysaccharides and peptone or yeast extract as elementary sources for carbon and nitrogen, respectively. Media containing sucrose /yeast extract or glucose/ yeast extract were the most effective for lipid production from fungal, during two weeks incubation period, the highest biomass of dry weight was (19.6 , 18.8) g / L , (25.8 , 30.5) g /L and lipid yield (1, 0.97 )g/L, (0.65, 0.65) g/ L for two isolates Aspergillus terreus
... Show MoreIrinotecan (CPT-11) is a semisynthetic derivative of the antineoplastic agent camptothecin used in a wide range as an anti-cancer agent in many solid tumors because of its cytotoxic effect through the interaction with the topoisomerase I enzyme. The major limiting factors for irinotecan treatment are its association with potentially life-threatening toxicities including neutropenia and acute or delayed-type diarrhea, results from distinct interindividual and interethnic variability due to gene polymorphism.
This is a cross sectional pharmacogentics study was conducted on 25 cancer patients to estimate the prevalence of UGT1A1*93 and ABCC5 allele single nucleotide polymorphism (SNP) in Iraqi cancer patients treated with irinotecan
... Show MoreBackground: Poly-ether-ether-ketone(PEEK) has been introduced to many dental fields. Recently it was tested as a retainer wire‎ following orthodontic treatment. This study aimed to investigate the effect of changing the bonding spot size and location on the performance of PEEK retainer wires. Methods: A biomechanical study involving four three-dimensional finite element models was performed. The basic model was with a 0.8 mm cylindrical cross-section PEEK wire, bonded at the center of the lingual surface of the mandibular incisors with 4 mm in diameter composite spots. Two other models were designed with 3 mm and 5 mm composite sizes. The last model was created with the composite bonding spot of the canine away from the center
... Show MoreCOVID-19 is a pandemic disease that has a wide spectrum of symptoms from asymptomatic to severe fatal cases due to hyperactivation of the immune system and secretion of pro-inflammatory cytokines. This study aimed to assess the level and impact of interleukin (IL)-13, IL-33, and tumor necrosis factor (TNF)-α cytokines on immune responses in mild and moderate COVID-19-infected Iraqi patients. A prospective case-control study was conducted from January 2023 to January 2024; it included 80 patients infected with moderate COVID-19 infection who consulted in different private clinics and 40 healthy controls. The serum of both groups was tested for quantification of serum IL-13, IL-33, and TNF-α using the human enzyme-linked immunosorbe
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The increasing of some traded Agricultural crops prices coincide with the increasing of crude oil prices in global market since the beginning of 21st century which indicate the possibility of short run and long run causality relation between the imported economic variables. The study aims to analysis the causality effects between some of Agricultural crops prices imported by Iraq and the prices of crude oil and Iraq dinar exchange rate in global markets for period (2004:1 -2016:4) theory for developing the adequate price and economic police for Iraqi economic sector. The results show the existence of short- run and long- run between the eco
... Show MoreOrganizations nowadays, whether public or private organizations, productive or service (such as banks), face major challenges as a result of rapid and continuous changes, and in front of these challenges traditional management operations and tools become unable to make the organization able to work, which makes it imperative for these organizations to follow the methods and management practices, including the proposed knowledge risk management and strategic direction so that it can elevate its actions at the level of developments in reality, in the sense that these organizations and in the light of environmental developments to characterize their strategic direction as an intellectual approach characterized by mo
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