The efficiency of solar energy absorption in solar heaters is increased by the use of selective absorption coating that possesses high absorption of solar radiation in the UV-visible spectrum as well as low emission at the operating temperature in the infrared region. In this work, novel selective coatings were synthesized by improving the selectivity of chromium oxide (Cr2O3) nanoparticles by doping with carbon nanoparticles using the exploding wire technique for carbon rods by high current in suspended Cr2O3 particles. The structural properties and surface topography were studied by XRD and FE-SEM, which illustrate the carbon-coated Cr2O3 nanoparticles. The prepared nanoparticles were mixed with a support material, Polyvinyl pyrrolidone (PVP) as a matrix, for use as a selective coating for three metals, namely copper, aluminium and stainless steel (SST). Reflectivity measurements were performed within the UV-Visible spectrum to calculate the absorption of solar radiation using numerical integration. The reflectivity was also measured in the range from 2.5 to 25 μm to calculate the thermal emission of the solar heater within the proposed operating temperature of 373 K. The measurements showed good efficiency of using the produced material as a selective coating which was prepared in a simple way compared to conventional methods. The best sample with efficient absorptance (α) for solar spectrum and of lowest emittance (ε) in IR region was for Al substrate coated by Cr2O3:C:PVP of α =0.886 and ε= 0.260.
Issam al-Din al-Asfrani's footnote
On the interpretation of the oval
Imam
Issam al-Din Ibrahim Arbashah al-Asfrani
(Th 159 e)
Surah Al-Baqarah (verse 55-911)
Vorwort:
Die Übersetzung gilt in der Vergangenheit als Brücke zwischen verschiedenen Gesellschaften. Sie spielt eine große Rolle im Bereich Kulturaustausch der Länder. Die Araber haben das früh betrachtet, und die Übersetzung als Wissenschaft wird eine der wichtigsten Lehren. Viele griechische Wissenschaften waren durch Übersetzung in den arabischen Ländern bekannt.
In dieser Forschung findet man einen Überblick über die Wichtigkeit der Sprichwörterübersetzung und welche Rolle spielt diese Übersetzung im Z
... Show MoreNovel bidentate Schiff bases having nitrogen-sulphur donor sequence was synthesized from condensation of racemate camphor, (R)-camphor and (S)-camphor with Methyl hydrazinecarbodithioate (SMDTC). Its metal complexes were also prepared through the reaction of these ligands with silver and bismuth salts. All complexes were characterized by elemental analyses and various physico-chemical techniques. These Schiff bases behaved as uninegatively charged bidentate ligands and coordinated to the metal ions via ?-nitrogen and thiolate sulphur atoms. The NS Schiff bases formed complexes of general formula, [M(NS)2] or [M(NS)2.H2O] where M is BiIII or AgI, the expected geometry is octahedral for Bi(III) complexes while Ag(I) is expected to oxidized t
... Show MoreThe research includes the synthesis and identification of the mixed ligands complexes of M(II) Ions in general composition [M(Lyn)2(phen)] Where L- lysine (C6H14N2O2) commonly abbreviated (LynH) as a primary ligand and 1,10-phenanthroline(C12H8N2) commonly abbreviated as "phen," as a secondary ligand . The ligands and the metal chlorides were brought in to reaction at room temperature in ethanol as solvent. The reaction required the following molar ratio [(1:1:2) (metal): phen:2 Lyn -] with M(II) ions, were M = Mn(II),Cu(II), Ni(II), Co(II), Fe(II) and Cd(II). Our research also includes studying the bio–activity of the some complexes prepared against pathogenic bacteria Escherichia coli(-),Staphylococcus(-) , Pseudomonas (-), Bacillus (-)
... Show MoreNew Schiff base ligand 2-((4-amino-5-(3, 4, 5-trimethoxybenzyl) pyrimidin- 2-ylimino) (phenyl)methyl)benzoic acid] = [HL] was synthesized using microwave irradiation trimethoprim and 2-benzoyl benzoic acid. Mixed ligand complexes of Mn((ІІ), Co(ІІ), Ni(ІІ), Cu(ІІ), Zn(ІІ) and Cd(ІІ) are reacted in ethanol with Schiff base ligand [HL] and 8-hydroxyquinoline [HQ] then reacted with metal salts in ethanol as a solvent in (1:1:1) ratio. The ligand [HL] is characterized by FTIR, UV-Vis, melting point, elemental microanalysis (C.H.N), 1H-NMR, 13C-NMR, and mass spectra. The mixed ligand complexes are characterized by infrared spectra, electronic spectra, (C.H.N), melting point, atomic absorption, molar conductance and magnetic moment me
... Show MoreDerivational word formation process is one of the most substantial linguistic procedures that solves many problems in the translation of the language new vocabulary and helps to comprehend the smallest language component that not simply semantically and structurally explain the elements of both Russian and Arabic but also enables translators to comprehend the derivational method procedures of both languages. It also reveals the structural aspects of translation equivalences, cognitive and semantic foundations of translation. The rapid development of languages and the appearance of a new vocabulary like ṭabaʿa "print → ṭābiʿat "printer", kataba "to write" → kātib → kātibat, rafaʿa "to raise" → rāfiʿat "a crane" d
... Show MoreThe ability of insurance companies to achieve goals depends on their ability to meet customers' requirements, and this requires them to identify target markets and respond to needs and wishes of the markets, the skill is to convince the company to operate what is in the interest of the customer if he is convinced the customer service provided to him, he would repeat to deal with, and where the cost of maintaining existing customers is less than the cost of attracting new customers, the insurance companies that is working hard to maintain their customers, the more customer satisfaction with the services provided has increased loyalty and weakened the ability of competitors lured.
&nbs
... Show MoreThe current study aims to identify the feeling of job alienation and organizational commitment among free lecturers in secondary schools, as well as to identify the significance of the differences in the feeling of job alienation according to the gender and the significance of the differences in organizational commitment according to the gender. It also aims to identify the correlation between the feeling of job alienation and organizational commitment. To achieve the objectives of the research, the researcher developed two scales: one consisted of (24) items to measure the vacancy in job alienation and the other consisted of (24) items to measure the organizational commitment. The two tools were applied to a sample of (200) male and fem
... Show MoreThe present study deals with the story of Epidemic in two literary works issued in the same year (1947). One of them is a novel titled "Plague" written by the French writer Alber Kamo, the second is a poem of the Iraqi poetess Nazik Al-Malaekah. The research reflects a contrastive study of the war vision in the two works as both writers used science to serve literature by using Epidemic as a metaphor to refer to the dangers that the societies faced.
The problem of the present research lies in answering the question about the reason that makes the two writers use metaphor while narrating the issues of the society instead of mentioning them directly and illuminate what implications do the narrative style of Epidemic story have and
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