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A review of ultra-high temperature materials for thermal protection system
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Abstract<p>Ultra-High Temperature Materials (UHTMs) are at the base of entire aerospace industry; these high stable materials at temperatures exceeding 1600 °C are used to manage the heat shielding to protect vehicles and probes during the hypersonic flight through reentry trajectory against aerodynamic heating and reducing plasma surface interaction. Those materials are also recognized as Thermal Protection System Materials (TPSMs). The structural materials used during the high-temperature oxidizing environment are mainly limited to SiC, oxide ceramics, and composites. In addition to that, silicon-based ceramic has a maximum-use at 1700 °C approximately; as it is an active oxidation process over low temperature and water vapor environment condition. However, a great emphasis is required for developing structural materials in oxidation and rapid heating environment where the temperature is greater than 1700 °C. This review covers briefly all main types of Thermal Protection Systems (TPSs) and all the materials are used to fabricate them with the maximum operational temperatures. Also, it covers the promised UHTMs (SiC, ZrB<sub>2</sub>, HfB<sub>2</sub>, SiB<sub>6</sub> and B<sub>4</sub>C) which are currently using for several aerospace applications, especially for TPS. Besides, it discusses the oxidation of SiC, B<sub>4</sub>C, SiB<sub>6</sub>, ZrB<sub>2</sub> and HfB<sub>2</sub>. Therefore, the carbides and borides of the transition metals, Zr and Hf have a high-melting temperature and good stability in forming high-melting temperature oxides.</p>
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Publication Date
Thu Jun 15 2017
Journal Name
Journal Of Baghdad College Of Dentistry
Mechanical evaluation of nano hydroxyapatite, chitosan and collagen composite coating compared with nano hydroxyapatite coating on commercially pure titanium dental implant
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Background: Dental implants act as infrastructure for fixed restoration to look like as a natural tooth. Osseointegration is a biological events and considered as a base for success of dental implant. The aim of this study is to evaluate the bond strength between bone and Ti implant coated with mixture of nano hydroxyapatite-chitosan-collagen compared with Ti implants coated with nano hydroxyapatite implanted in rabbit tibia, after different period of implantation time (two and six weeks) by torque removal test. Material and methods: 36 screws of commercially pure titanium; 8mm in length and 3mm diameter , 18 screws coated with mixture of nano hydroxyapatite-chitosan-collagen and18 screws coated with nano hydroxyapatite by dip coating. St

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Publication Date
Fri Dec 01 2017
Journal Name
International Journal Of Science And Research (ijsr)
Histological Study of Some Isolation Fungi from Iraq / Baghdad Hospitals Apparatus that affected in Liver, Kidney and Testes in Albino Mice
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Publication Date
Fri Jun 28 2024
Journal Name
Curr Pharm Des
Synthesis, Characterization, and Antimicrobial Evaluation of Schiff base-mixed Ligand Complexes with Divalent Metal Ions Derived from Amoxicillin and Vanillin/Nicotinamide
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Publication Date
Fri Jun 28 2019
Journal Name
Journal Of The College Of Education For Women
Creative Formation in the Poetry of Thafer Bin Qasim Al-Haddad (529 A.H) (Creative Ingenuity as Model): خلود هاشم جوحي الوائلي
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Through research and research in the creative composition in the poetry of Zafer-Alhaddad it turned out to be superior in its systems, especially that he chose a linguistic and verbal texture accompanied by a cultural dictionary full of creativity and beauty helped this culture arrangement reflects the poetically wonderful and beautiful custom led to the harmony of colors and bodies painted by the poet brush the creative artist evaluates the metaphorical and metaphorical relations that would explain the poets idea, most of which were inspired by the wonderful spirit of nature, its beautiful landscapes and bright colors, especially that we do not forget the beautiful colors and the aesthetic touch that created a fascinating musical intera

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Publication Date
Fri Sep 27 2019
Journal Name
Journal Of Baghdad College Of Dentistry
The Impact of Chronic Periodontitis on Mother-Infant Bonding Status in Relation to Salivary Tumor Necrosis Factor Alpha and Interleukin-6
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Background: Chronic periodontitis is a bacterial infection that result in bone destruction associated with the increasing level of salivary tumor necrosis alpha and interleukin6 that affect Mother-infant bonding status. The aim of the present study was to assess the relationship between the Mother-infant bonding status in mothers with chronic periodontitis in relation to Salivary Tumor necrosis factor alpha and Salivary Interleukin6. Materials and Methods: The selected sample consisted of mothers with chronic periodontitis compared with mothers with healthy periodontium in postpartum period, their age ranged between 30-40 years. Both groups were subjected to postpartum Bonding Questionnaire (PBQ). Periodontal health status was assessed f

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Publication Date
Mon Mar 01 2021
Journal Name
World Heart Journal
Change in Left Ventricular Size and Ejection Fraction in Patients at Rest vs. Stress with Different Degrees of Ischemic Heart Failure
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Background and Aim. Coronary artery disease (CAD) is a major risk factor for the progression to heart failure (HF), which is associated with an increase in left ventricular volume (LVV). This study aims to measure ventricular function and myocardial perfusion imaging markers of the left side of the heart, which can be performed with injection of a 99mTc at stress and rest by using single-photonemission-computed-tomography (SPECT). Subject and methods. The study included 121 patients with CAD, comprising 53 females and 68 males with ages between 25 to 88 years and 265 healthy subjects comprising 84 males and 181 females. All patients and healthy subjects volunteered to participate in this study. They were classified according to

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Publication Date
Thu Nov 30 2023
Journal Name
Iraqi Geological Journal
Multiple and Coherent Noise Removal from X-Profile 2D Seismic Data of Southern Iraq Using Normal Move Out-Frequency Wavenumber Technique
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Multiple eliminations (de-multiple) are one of seismic processing steps to remove their effects and delineate the correct primary refractors. Using normal move out to flatten primaries is the way to eliminate multiples through transforming these data to frequency-wavenumber domain. The flatten primaries are aligned with zero axis of the frequency-wavenumber domain and any other reflection types (multiples and random noise) are distributed elsewhere. Dip-filter is applied to pass the aligned data and reject others will separate primaries from multiple after transforming the data back from frequency-wavenumber domain to time-distance domain. For that, a suggested name for this technique as normal move out- frequency-wavenumber domain

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Publication Date
Sat Jan 01 2022
Journal Name
Annals Of Biology
The Comparative Effect of Copper Oxide Nanoparticles and Copper Sulfate on Reproductive Hormones and Sperm Parameters in Mature Male Albino Mice
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Publication Date
Mon Nov 01 2021
Journal Name
Clinics And Research In Hepatology And Gastroenterology
Genetic polymorphism of fibroblast growth factor receptor 2 and trinucleotide repeat-containing 9 influence the susceptibility to HCV-induced hepatocellular carcinoma
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Background Fibroblast growth factor receptor 2 (FGFR2) and trinucleotide repeat-containing 9 (TNRC9) gene polymorphisms have been associated with some cancers. We aimed to assess the association of FGFR2 rs2981582 and TNRC9 rs12443621 polymorphisms with hepatocellular cancer risk. Methods One hundred patients with HCV-induced HCC, 100 patients with chronic HCV infection, and 100 controls were genotyped for FGFR2 rs2981582 and TNRC9 rs12443621 using allele-specific Real-Time PCR analysis. Results FGFR2 rs2981582 genotype TT was associated with increased risk of HCC when compared to controls (OR = 3.09, 95% CI = 1.24–7.68). However, it was significantly associated with a lower risk of HCC when using HCV patients as controls (OR =

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Scopus
Publication Date
Wed Jan 01 2020
Journal Name
Biochemical And Cellular Archives
Histological and histochemical studies of the duodenum in the small asian mongoose (herpestes javanicus, E. geoffroy saint. Hilaire, 1818) in Iraq
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