The solidification process in a multi-tube latent heat energy system is affected by the natural convection and the arrangement of heat exchanger tubes, which changes the buoyancy effect as well. In the current work, the effect of the arrangement of the tubes in a multi-tube heat exchanger was examined during the solidification process with the focus on the natural convection effects inside the phase change material (PCM). The behavior of the system was numerically analyzed using liquid fraction and energy released, as well as temperature, velocity and streamline profiles for different studied cases. The arrangement of the tubes, considering seven pipes in the symmetrical condition, are assumed at different positions in the system, including uniform distribution of the tubes as well as non-uniform distribution, i.e., tubes concentrated at the bottom, middle and the top of the PCM shell. The model was first validated compared with previous experimental work from the literature. The results show that the heat rate removal from the PCM after 16 h was 52.89 W (max) and 14.85 W (min) for the cases of uniform tube distribution and tubes concentrated at the bottom, respectively, for the proposed dimensions of the heat exchanger. The heat rate removal of the system with uniform tube distribution increases when the distance between the tubes and top of the shell reduces, and increased equal to 68.75 W due to natural convection effect. The heat release rate also reduces by increasing the temperature the tubes. The heat removal rate increases by 7.5%, and 23.7% when the temperature increases from 10 °C to 15 °C and 20 °C, respectively. This paper reveals that specific consideration to the arrangement of the tubes should be made to enhance the heat recovery process attending natural convection effects in phase change heat storage systems.
Methotrexate (MTX) was used for treatment of malignancies and now is widely used in treatment of rheumatoid arthritis. In this research the evaluation of the effects of MTX on some liver enzymes and lipid profile was studied. Twenty four adult female mice divided into three groups (8 mice each). The first two groups were treated with MTX while the third group was used as a control. MTX was intraperitoneally given at 50 µg/ml and 75 µg/ml to the first and second groups respectively for 35 days ,whereas the control group was intraperitoneally injected with normal saline. The results showed a significant (p<0.05) increase in serum levels of glutamic oxaloacetate transaminase (GOT) , glutamic pyruric transaminase (GPT), Alkaline pho
... Show MoreBackground: Obesity increases the host’s susceptibility by modulating the immune and inflammatory systems in a manner that predisposes to inflammatory tissue destruction and leaves an individual at greater risk of periodontitis. Melatonin is a pineal secretory product involved in numerous actions, such as regulation of internal biological clocks and energy metabolism, and it functions as an antioxidant and anti-inflammatory agent. There exists a substantial amount of evidence supporting the beneficial effect of melatonin supplementation on obesity and its complications. Aim of the study: To investigate the effects of systemic melatonin intake on periodontal health status and lipid profiles in obese periodontitis patients. Subjects and met
... Show MoreThe study aimed to measure the effect of applying the disclosure and transparency standards criteria adopted by the Saudi Arabian Monetary Authority on improving performance indicators in the Saudi banking sector, by measuring the extent of the impact of the bank's financial indicators represented by liquidity, profitability and return on assets in Saudi banks by applying the criteria of disclosure and transparency, which is one of the Main principles in the list of governance, which was approved by the Saudi Arabian Monetary Authority. The analytical approach was followed to achieve the goal of the study, as the financial statements of Saudi banks were analyzed during a period of 8-year to test four hypotheses related to measuri
... Show MoreVisceral leishmaniasis is a neglected tropical disease on the rise in different regions of Iraq, especially in areas with poor hygiene and among refugee populations. The effectiveness of existing chemotherapy for leishmaniasis is constrained by its high toxicity, cost, and the development of drug resistance. The current research examined various concentrations (ranging from 125 to 1000 μM) of lupeol to evaluate its ability to boost the generation of nitric oxide, which has anti-leishmanial properties, in an ex-vivo macrophage model. Griess assay was used to detect the nitric oxide (NO) production in Leishmania donovani infected U937 cell-line macrophages along 24 and 48 hours post treated. The nitric oxide concentration was signifi
... Show MoreCataract is an opacity in the normally transparent focusing lens of the eye which leads to blindness. The aim of current study is to investigate the possible protective and therapeutic effects of aqueous extract of Foeniculum vulgare seed eye drops (0.5%) against selenite induced cataract in rabbits. Aqueous extract of Foeniculum vulgare seed prepared then formulated as eye drops. Sodium selenite used to induce cataract in rabbits' right eye by single intravitreal injection. Thirty-six rabbits included in the study and divided into three equal groups (12 rabbits in each group): healthy control group, Cataract-Induced group and group treated by Foeniculum vulgare seed extract eye drops. Parameters include the score of lens opacity which was
... Show MoreCopper and Zinc powders with different particle sizes were subjected to sieving of range (20-100?m) and He-Ne laser system to determine the particle size . 1wt% from each powders was blended carefully with 99wt% from Iraqi oil . Microscopic examination were carried for all samples to reveal the particle size distribution . XRF intensity measurements were conducted for all suspended samples , and the relation between XRF intensity and the particle size was found .
An anatomical study was carried out at the College of Agricultural Engineering Sciences, University of Baghdad, in 2017, on lupine crop (Lupinus albus) as a comparison guide of three seed weights of three lupine cultivars viz. ‘Giza-1’, ‘Giza-2’ and ‘Hamburg’. The nested design was used with four replications. The results showed that cultivars had a significant effect on stem anatomical traits. ‘Hamburg’ cultivar recorded the highest stem diameter, cortex thickness and xylem vascular diameter, while cultivar ‘Giza-1’ recorded the lowest values for the same traits as well as the highest collenchyma layer thickness, vascular bundle thickness, and xylem thickness. Cultivar ‘Giza-2’ recorded the lowest vascular b
... Show MoreThis study was carried out to evaluate the hepato-protective property of (Arachis hypogea L.) peanut skin extracts in CCl4 induced hepatotoxicity in mice. The antioxidant activity was measured utilizing 2, 2-diphenyl-1-1 picrylhydrazyl (DPPH) radical scavenging capacity. The results showed that the methanolic extract was the highest free radical scavenging activity than the aqueous extract with values (92.34 ± 0.45 and 87.62 ± 0.44) respectively in 12 mg/mL compared to 89.61 ± 0.34 for Butylated hydroxytoluene (BHT) and 93.25 ± 0.06 for vitamin C, which means that the methanolic extract of peanut skin is superior to BHT. Furthermore, the total phenolic content was analyzed by using Folin-Ciocalteu method, the amount of total phenol in a
... Show MoreLearn new methods of teaching mathematics contribute to raising the level of pupils to acquire mathematical concepts primary stage
Attempt advancement in the level of mathematics teaching for the better through the use of modern teaching strategies. The research aims at the progress in the acquisition of mathematical concepts schoolgirls after subjecting the fourth grade to teach in active learning strategies, the number of research sample (60) schoolgirl, by (30) schoolgirl experimental group and 30 pupils of the control group. Clear from the results shown the presence of a statistically significant difference between the acquisition of concepts of schoolgirls two groups (experimental and control) for the benefit of pupils of the exp