In the present study, multi-walled carbon nanotubes (MWCNTs) with outside diameters of< 8 nm and 20−30 nm were covalently functionalized with β-Alanine using a novel synthesis procedure. The functionalization process was proved successful using Raman spectroscopy, FTIR, and TEM. Utilizing the two-step method with ultrasonication, the MWCNTs treated with β-Alanine (Ala-MWCNTs) with weight concentrations of 0.025%, 0.05%, 0.075%, and 0.1% were dispersed in distilled water to prepare water-based nanofluids. The aqueous colloidal dispersions of pristine MWCNTs were unstable. While for Ala-MWCNTs and after> 50 days from preparation, higher colloidal stability was obtained up to relative concentration of 0.955 and 0.939 for the 0.075-wt% samples of Ala-MWCNTs < 8 nm and Ala-MWCNTs 20−30 nm, respectively. The measured values of thermal conductivity were in very good agreement with the model of Nan, Birringer, Clarke and Gleiter and increased as temperature, specific surface area (SSA), and weight concentration increased, up to 14.74% for Ala- MWCNTs < 8 nm and 12.29% for Ala-MWCNTs 20−30 nm. The viscosity increased as weight concentration increased, up 25.69% for 0.1-wt% Ala-MWCNTs 20−30 nm, and decreased with the increase in temperature. Since the matching between the measured values of viscosity and the classical models of Batchelor, Brinkman, and Einstein was bad, a correlation was developed and revealed good agreement. The density and specific heat decreased as temperature increased. As weight concentration increased, the density slightly increased up to 0.065% for Ala-MWCNT < 8 nm while the specific heat decreased down to 0.95% for Ala-MWCNTs 20−30 nm, in comparison with water. The equations of (Pak and Cho) and (Xuan and Roetzel) were in good agreement with the measured values of density and specific heat, respectively. The aqueous colloidal dispersions of Ala-MWCNTs that were prepared in this work displayed robust candidature as successful substitutes for the conventional heat transfer fluids in different engineering applications for enhanced thermal performance.
The tax exemption, whether wholly or partially, and for an unlimited duration of the investment or for a limited period of few years, is one of the encouraging things to the flow of foreign capital. And if necessary, impose tax on the profits of the invested capital, the promotion requires that not be discriminatory taxes or payments in the amount of money with the need to avoid double taxation. The tax exemption is granted by the government and the feature according to the law of a natural person or legal entity seeking from the government purports to achieve a set of political goals, economic and social development. The reduction of taxes or grants partial exemption is one of the factors that encourage attract of direct foreign i
... Show MoreBackground: the aim of this study was to evaluate the effect of different surface acids treatments (37%phospjoric acid, 5%hydrofluoric acid, 1.23 acidulated phosphate fluoride) of feldspathic ceramic VITA 3D MASTER , and the effect of thermocycling on shear bond strength using a ceramic repair kit (ivoclar/vivadent). Material and Methods: sixty Nickel-Chromium metal base plates were prepared(9mm diameter,3mm depth) using lost wax technique, 2mm thick layer of ceramic(VITA 3D MASTER) fused to metal plates, all specimens were embedded in acrylic resin blocks except their examined surfaces and divided into 3 main groups 20 specimens each, Grp A: treatment with 37%phosphoric acid for 2 mins, Grp B: etching with 5% hydrofluoric acid for 2mins,
... Show MoreSAPO-11 is synthesized from silicoaluminophosphate in the presence of di-n-propylamine as a template. The results show that the sample obtained has good crystallinity, 396m2/g BET surface area, and 0.35 cm3/g pore volume. The hydroisomerization activity of (0.25)Pt (1)Zr (0.5)W/SAPO-11 catalyst was determined using n-decane and base oil. All hydroisomerization experiments of n-decane were achieved at a fixed bed plug flow reactor at a temperature range of 200-275°C and LHSV 0.5-2h-1. The results show that the n-decane conversion increases with increasing temperature and decreasing LHSV, the maximum conversion of 66.7 % was achieved at temperature 275°C and LHSV of 0.5 h-1. Meanwhile, the same catalyst was used to improve base oil spec
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Purpose: Providing practical knowledge of the requirements of a detailed feasibility study for selecting the investment project.
Findings: Directing the private sector towards investing in productive projects - the pre-cast reinforced concrete project - as it achieves a financial return as well as providing Providing foreign currencies by reducing imports and exploiting available natural resources
Practical implications: The importance of a detailed feasibility study to determining whether the project can be implemented or not.
The precast concrete method is one of the best modern c
... Show MoreThis work is concerned with the study of the effect of cement types, particularly OPC and SRPC, which are the main cement types manufactured in Iraq. In addition, study the effect of mineral admixtures, which are HRM and SF on the resistance of high performance concrete (HPC) to internal sulphate attack. The HRM is used at (10%) and SF is used at (8 and 10)% as a partial replacement by weight of cement for both types. The percentages of sulphate investigated are (1,2 and 3)% by adding natural gypsum as a partial replacement by weight of fine aggregate. The tests carried out in this work are: compressive strength, flexural strength, ultrasonic pulse velocity, and density at the age of 7, 28, 90 and 120 days.
The r
... Show MoreIn this work, of New Ligand [(E)-5-hydroxy-4-(3-(4-methoxy phenyl) acryl amido) naphthalene -1- sulfonic acid] (ANS) was prepared by reflexing reaction of 4-amino-5-hydroxy naphthalene sulfonic acid with para methoxy cinnamic acid, this produced and described chemical was employed as ligand to prepare tri and di-organotin complexes by condensation reaction with the salts of organotin chloride (phenyl, butyl, and methyl tin chloride). Specialized methods, including elemental analysis, (tin and proton) magnetic resonance, and infrared spectra, were used to identify the complexes. DPPH (2,2-diphenyl-1-picrylhydrazyl) and CUPRAC (Cupric Reducing Antioxidant Capacity) are both commonly used methods for measuring antioxidant capacity in v
... Show MoreThis note reported the first record of Spotted Flycatcher Muscicapa striata (Pallas, 1764) (Passeriformes, Muscicapidae) from the state of Odisha, India. This species was recorded from the north and western part of the country as well as from the Western Ghats, but this note reports the first record from the Eastern Ghats of India.
Background: five clinical phases were described in patients with chronic (HBV) infection: HBeAg- positive HBV infection, HBeAg- positive chronic HB, HBeAg negative HBV infection, HBeAg-negative CHB and occult HBV infection. Aim: This study aimed to determine the incidence of the unclassified phase (gray zone) in chronic hepatitis B patients and its significant in the clinical practice. Patients and methods: The study was conducted retrospectively on 109 patients' who have HBsAg positive for more than 6 months. The data recorded include; HbeAg and anti-HBe Ab, ultrasound of the abdomen, HBV DNA load and alanine aminotransferase (ALT), accordingly; we classify the patients to known clinical phases. Patients who were unfit one of these phases
... Show MoreThe aim of this study is to compare the effects of three methods: problem-based learning (PBL), PBL with lecture method, and conventional teaching on the understanding of thermodynamics, group work and self-directed learning skills among physics undergraduates. The actual sample size comprises of 122 students, who were selected randomly from the Physics Department, College of Education in Iraq, for academic year 2011-2012. In this study, the pre and posttest were done and the instruments were administered to the students for data collection. Inferential statistics were employed to analyze data. The independent variables were the PBL, the PBL with lecture method, and the conventional teaching. Dependent variables of statistical analysis were
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