A pioneering idea for increasing the thermal performance of heat transfer fluids was to use ultrafine solid particles suspended in the base fluid. Nanofluids, synthesized by mixing solid nanometer sized particles at low concentrations with the base fluid, were used as a new heat transfer fluid and developed a remarkable effect on the thermophysical properties and heat transfer coefficient. For any nanofluid to be usable in heat transfer applications, the main concern is its long-term stability. The aim of this research is to investigate the effect of using four different surfactants (sodium dodecyl benzene sulfonate (SDBS), sodium dodecyl sulfate (SDS), cetyl trimethylammonium bromide (CTAB), and gum Arabic (GA)), each with three different concentrations, and five ultrasonication times (15, 30, 60, 90, and 120 min) on the stability of water-based graphene nanoplatelets (GNPs) nanofluids. In addition, the viscosity and thermal conductivity of the highest stability samples were measured at different temperatures. For this aim, nineteen different nanofluids with 0.1 wt% concentration of GNPs were prepared via the two-step method. An ultrasonication probe was utilized to disperse the GNPs in distilled water. UV–vis spectrometry, zeta potential, average particle size, and Transmission Electron Microscopy (TEM) were helpful in evaluating the stability and characterizing the prepared nanofluids. TEM and zeta potential results were in agreement with the UV–vis measurements. The highest nanofluid stability was obtained at 60-min ultrasonication time. The prepared water-based pristine GNPs nanofluids were not stable, and the stability was improved with the addition of surfactants. The presence of SDBS, SDS, and CTAB surfactants in the nanofluids resulted in excessive foam. The best water-based GNPs nanofluid was selected in terms of better stability, higher thermal conductivity, and lower viscosity. From all the samples that were prepared in this research, the (1–1) SDBS–GNPs sample with 60-min ultrasonication showed the highest stability (82% relative concentration after 60 days), the second better enhancement in the thermal conductivity of the base fluid (8.36%), and nearly the lowest viscosity (7.4% higher than distilled water).
The study aimed to reveal the role of social capital represented by its dimensions (structural, relational, and cognitive) in strengthening the management of excellence in Azadi Hospital / Duhok. In order to reach the goal of the study, the study variables were highlighted in theory through framing concepts and literary contributions for researchers in this field, In the field, the questionnaire was used as a basic tool to collect data from the individuals in the research sample who were represented by officials and individuals working from administrators and technicians, as (120) forms were distributed to the respondents, and (110) were retrieved from them in a way that is valid for analysis. Several statistical methods have bee
... Show MoreThe current study aims to investigate the effect of (SWOM) strategy on acquiring the psychological concepts of educational psychology course and its retention among education college students. To do this, a sample of (57) male and female student were intentionally selected from first grade, Kurdish department / college of education / Ibin Rushd of human sciences. The sample distributed on two classes, whereby the experimental group consisted of (28) student were taught according to the (SWOM) strategy while the control group made up of (29) student were taught based on the tradition method. The two researchers designed a scale included (50) item to measure students' achievement. The experiment lasted for ten weeks, SPSS was used
... Show MoreBackground: The vasoconstricting agents: nor-adrenaline and 5- hydroxytryptamine
(5-HT) have a stimulant action on smooth muscle contractility of the rat vas deferens.
Objective: This study aimed to investigate the effect of exposure to continuous
darkness and continuous light on the contractility of the vasa deferntia smooth
muscles from rats to applied nor-adrenaline and 5-HT.
Method: Male albino wistar rats were divided into 3 experimental groups. Group 1:
Control animals, were exposed to the ordinary photoperiod each day. Group 2: Rats
were kept in a dark room. Group 3: In a room under a bright artificial light.
All animals were killed after 4 weeks.
Results: Vasa deferentia preparations from continuous dar
The method of analysis is one of the tools the coach to identify strengths andweaknesses of each player, and how to avoid mistakes that in the course ofperformance on the other hand, Voslob analysis is important for the player, as throughthe analysis will determine the capacity enjoyed by both the coach and player, as wellas being the possibility of progress in a scientific manner thoughtful, and also helps inthe evaluation of physical and skill level and tactical, psychological and trainingcapacity of the coach in order to avoid obstacles and make the coach is movingtowards the right track to improve the good level, and then an investigation tocomplete higher education.Hence the importance of research in the analysis of simple attack and n
... Show More؛ ١٨his study male and female albino mice werdministr^d doses of alkaloid and phenolic extracts of Allium cepa at doses of( 25 ,50,100, 200) mg / kg of( body weight). males and females were divided into four groups and each croup comprised mice were injected intra^ritonially daily for one week and orally ٢٠٢ one month . After which animals were killed and the serum was separated for biochemical analysis (total blood suger, total protein , otal cholesterol). Results showed significant decrease ( p< 0,05) in the total blood suger and total cholesterol on the serum of both males and females and significant increase( p< 0,05) in the total serum protein of both males and females of the two types of injection and oral administr
... Show MoreResearch Summary
Praise be to God, and may blessings and peace be upon the Messenger of God. As for:
The Noble Qur’an is the constitution of life, and a comprehensive educational approach that deals with individuals comprehensively, as it organizes worldly and eschatological life, and it is a curriculum concerned with organizing life starting with individuals and the family until the establishment of states, and from its comprehensiveness is reform, guidance and establishing boundaries. They have a disease in their hearts. They are exposed to this and are trying, by falsehood, to subjugate the Islamic world with man-made laws set by the West. Their aim is to distance people from
... Show MoreMarriage outside the court is a manifestation of the oppression that women are subjected to in Iraq its seriousness comes out of the consequences that it leads to The. It overlooks the age of the girl and her marriage in younger age or coerced to marry as it leads to neglecting the affordability of marital relationship as long as the marriage does not have any legal or material consequences. The present study aims to detect Characteristics of both wives, husbands and families Who agree to marry her daughters outside the court. And the reasons that lead them to marry outside the courts. It also aims to provide information on the circumstances of marriage and reasons for refusing to ratify it in court. The study was based on the sample soc
... Show MoreBack ground: Cancer is the second leading cause of death throughout the world. Breast cancer, is one of the leading mortality reasons in women from Western Countries, in Iraq, breast cancer is the second reason of death After cardiovascular Diseases.
Material and method:
The study was carried out of period from October/2016-january /2017 and included (90) serum samples for Iraqi women suffered from breast cancer . Samples were divided into two groups ,the first group included (66) patients (females) their age rang (22-55) years which attended to (tumor unit) at medical city educational oncology hospital and Al-Amal Al-Waatanii hospital in Baghdad ,the second group included (38) for
... Show MoreBackground: Chronic renal failure (CRF) is a clinical syndrome that occurs when there is gradual decline in renal operation overtime.
Objective: This study aims to investigate the prevalence of depression among medical students at university of Baghdad, college of medicine in Iraq and the association between some variables and depression.
Aim: This study aimed to identify the impact of tobacco use in the etiology of chronic renal failure among Sudanese patients in Omdurman Military Hospital and Omdurman Kidney Dialysis Center
Materials and methods: This descriptive community-based study was conducted in Khartoum State. A random sample of 100 cases with chronic renal failure and 100
... Show MoreFormed leadership skills and organizational trust Based on intellectual that underpinned the current research, as represented leadership skills variable interpretative represented in organizational trust-response variable.
The research aims to test the relationship and the impact of leadership skills dimensions in organizational trust dimensions for the purpose of achieving its objectives were formulated hypotheses main relate to test the effect and the relationship between the variables of research for the purpose of testing those hypotheses applied research on a sample of heads of departments and officials of the people at the center of the Ministry of Higher Education and Scientific Research, where th
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