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).
Programs directed to children through the media in general and in television in particular are among the main factors that help in forming the cultural and educational values of this important segment of society, and in light of this the study problem was identified in answering a major question: What are the cultural and educational values that Ajyal channel seeks Space planted in children through my program, Iftah Ya Simsim (in its new season) and Friends of Ajyal? , While the objectives of the study were evident in identifying the most prominent cultural and educational values that the Ajyal satellite channel worked to instill in children, and identifying the nature of the techniques used by Ajyal channel in providing the value conten
... Show MoreIn this work the design and construction of optical pumping system was presented. The parameters of the pumping source to obtain discharge current density sufficient to shift the flash lamp spectrum towards uv portion of spectrum were measured.The current density was supplied to the flash lamp must be greater than 4000Amp./cm2 to obtain the spectral range wavelength lies between 0.2 and 0.35?m. The current density was obtained by a capacitor 50?F, at 7KV discharge voltage. The applied electrical energy to the flash lamp was more than 1200 J, and the current density was around 5000 Amp./cm2.The electrical parameters of the flash lamp were calculated. The impedance parameters(K0) from the voltage and the peak current pulse was measured in ran
... Show MoreThis is a research in which I studied the opinions of Arab scholars, in their studies
For (what) and (whatever) the two conditionals and their indication of time, and its name
B (time in (what) and (whatever) the two conditions), and I mentioned their opinions in it
This issue was discussed and discussed, and in this study it relied on the sources of the Arabic language.
Especially the books of grammar, interpretation, and the opinions of the scholars of the principles of jurisprudence are mentioned,
I also mentioned the opinion of the scholars of jurisprudence, and how they likened (whatever) to (everything).
In its indication of repetition, and as long as it indicates repetition, it indicates
time Because repetitio
It is not often easy to identify a certain group of words as a lexical bundle, since the same set of words can be, in different situations, recognized as idiom, a collocation, a lexical phrase or a lexical bundle. That is, there are many cases where the overlap among the four types is plausible. Thus, it is important to extract the most identifiable and distinguishable characteristics with which a certain group of words, under certain conditions, can be recognized as a lexical bundle, and this is the task of this paper.
The primary objective of this paper, is to introduce eight types of topologies on a finite digraphs and state the implication between these topologies. Also we used supra open digraphs to introduce a new types for approximation rough digraphs.
Abstract Rationality and freedom are fundamental elements of Western modernity. Although modern and contemporary Islamic thought has established its intellectual foundations on the fundamentals of intellectual thought that are at the core of its Islamic intellectual system, at the same time many of its intellectual products have been a response In spite of the fact that this Islamic intellectual response stands out from Western modernity as a negation or a positive attitude. The Islamic intellectual response differed in determining its position on Western modernity, depending on the nature of the historical stage that was The Islamic nation, as well as the nature of the challenge posed by Western civilization to other nations and other c
... Show MoreBackground: Total superficial parotidectomy is the most commonly used approach in excising the tumors that affect the superficial lobe of the parotid gland, whether they're benign or malignant. The aim of the study is to evaluate the benefits and drawbacks of total superficial parotidectomy for parotid gland tumors within five years of follow-up. Patients and methods: Nineteen patients with lateral facial swelling affecting the parotid region were included in this study. All of them operated under general anesthesia with oral endotracheal intubation, where Modified Blair Incision (lazy S incision) was utilized in all cases. Anterograde dissection with facial nerve identification was accomplished with total superficial parotidectomy.
... Show MoreMelatonin, a hormone synthesized mainly by the pineal gland, has been found in extra-pineal organs as well. It’s known as an organizer of circadian rhythms and more recently as an anti-oxidant. In addition to its role in maintaining immunity, pathophysiology of cardiovascular and neurological diseases, and as an anti-cancer agent, evidence has demonstrated that melatonin exerts a positive impact on male and female fertility primarily through oxygen scavenging effects. In In Vitro Fertilization (IVF) programs, supplementation of melatonin may be associated with better outcomes in terms of sperm quality, oocyte quality, embryo quality and pregnancy rates. This review summarizes various actions of melatonin on the body focusing on male an
... Show MoreAn abortion that occurs spontaneously is known as a miscarriage. Various effectors associated with abortion such as Genetic and uterine anomalies, Endocrinopathy, immunological dysfunctions, infectious agents, environmental contaminants, psychogenetic elements, and endometriosis. Maternal infections considered the main reason for pregnancy wastage in females with Bad Obstetric History (BOH). Candida albicans is a dimorphic fungus that can grow as yeast or filamentous cells and considered one of the limited species of the Candida genus that cause humans candidiasis. It is an opportunistic fungus that responsible for mucosal infections in the mouth and genital tract. Excessive growth of C. albicans will follow with Vulvovaginal candid
... Show More