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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
Tue Jan 01 2019
Journal Name
Energy Procedia
Humidity effect on diffusion and length coefficient of radon in soil and building materials
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Publication Date
Wed Apr 01 2026
Journal Name
Journal Of Nanostructures
Synthesis of New Polymeric Composite Materials Derived from 2,2-(1,6-Dioxohexane-1,6-diyl) Dihydrazinecarbothioamide
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In this study, a new class of polymeric nanocomposites was synthesized and characterized.  One mole of dimethyl adipate and two moles of thiosemicarbazide in ethanol first reacted to form the compound [C1]. Compound [C1] then reacted with sodium hydroxide to produce compounds [C2]. Hydrazine hydrate reacted with compound [C2] to generate compound [C3]. Compound [C4] was synthesized from compound [C3] and maleic anhydride. A polymer [C5] is formed by the reaction of the compound [C4] with ammonium persulfate as an initiator. This polymer was then combined with nano: ZnNPs, AgNPs, SiNPs, or IONPs using a hotplate stirrer for 3 hours to produce nanocomposites [C6-C9]. FTIR, 1H-NMR, and Field Emission Scanning Electron Microscope (FESEM) were

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Publication Date
Mon Jun 15 2026
Journal Name
Journal Of Baghdad College Of Dentistry
The role of knowledge and practice in orthodontists' attitudes towards bonding materials and techniques
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Background: The materials and techniques of orthodontic bonding systems remain a pivotal concern in orthodontic research. This issue is further complicated by orthodontists' preferences. To assess the effect of knowledge and practice on the attitudes of orthodontists towards bonding materials and techniques. Methods: A cross-sectional, questionnaire-based study was conducted using Google Forms. The questionnaire comprised 17 multiple-choice questions that targeted orthodontists' awareness, knowledge, and attitude towards bonding materials. It was distributed via email or social networking platforms to specialist Iraqi orthodontists. Results: A total of 176 participants responded with nearly equal representation between the sexes. Th

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Publication Date
Tue Dec 29 2020
Journal Name
Journal Of Accounting And Financial Studies ( Jafs )
Personal tax exemptions "a comparative study with some Arab and European system legislations
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This research aims primarily to highlight personal tax exemptions A comparative study with some Arab and European regulations. And by conducting both theoretical comparative analyses. Most important findings of the study is the need to grant personal and family exemptions that differ according to the civil status of the taxpayer (single or married). In other words, the exemption increases as the number of family members depend on its social sense. Also taking into account some incomes that require a certain effort and looking at the tax rates, it is unreasonable for wages to be subject to the same rates applied to commercial profits.      

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Publication Date
Mon Nov 22 2021
Journal Name
Nanomaterials
Melting Enhancement in a Triple-Tube Latent Heat Storage System with Sloped Fins
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Due to the potential cost saving and minimal temperature stratification, the energy storage based on phase-change materials (PCMs) can be a reliable approach for decoupling energy demand from immediate supply availability. However, due to their high heat resistance, these materials necessitate the introduction of enhancing additives, such as expanded surfaces and fins, to enable their deployment in more widespread thermal and energy storage applications. This study reports on how circular fins with staggered distribution and variable orientations can be employed for addressing the low thermal response rates in a PCM (Paraffin RT-35) triple-tube heat exchanger consisting of two heat-transfer fluids flow in opposites directions throug

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Publication Date
Mon Sep 30 2024
Journal Name
Tikrit Journal Of Administrative And Economic Sciences
Ambidextrous Leadership: Literature Review
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The goal of the research is to theoretically establish the variable of brilliant leadership and explain the importance of this variable and the philosophical orientation of researchers in taking it as an original variable in their research as an independent variable. The descriptive approach and theoretical framing of brilliant leadership were followed. We relied on secondary data represented by books, dissertations, dissertations, scientific research, and the information network (the Internet) as a tool for collecting data. The scientific value was represented by the importance of consolidating brilliant leadership and reviewing the most important things that were confirmed by the research and studies that dealt with this research.

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Publication Date
Wed Nov 29 2023
Journal Name
International Journal Of Advances In Scientific Research And Engineering (ijasre), Issn:2454-8006, Doi: 10.31695/ijasre
Yolo Versions Architecture: Review
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Deep learning techniques are applied in many different industries for a variety of purposes. Deep learning-based item detection from aerial or terrestrial photographs has become a significant research area in recent years. The goal of object detection in computer vision is to anticipate the presence of one or more objects, along with their classes and bounding boxes. The YOLO (You Only Look Once) modern object detector can detect things in real-time with accuracy and speed.&nbsp; A neural network from the YOLO family of computer vision models makes one-time predictions about the locations of bounding rectangles and classification probabilities for an image. In layman's terms, it is a technique for instantly identifying and recognizing

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Publication Date
Mon Oct 17 2022
Journal Name
Journal Of The Faculty Of Medicine Baghdad
Review on Viral Encephalitis-
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Background: Inflammation of the brain parenchyma brought on by a virus is known as viral encephalitis. It coexists frequently with viral meningitis and is the most prevalent kind of encephalitis. Objectives: To throw light on viral encephalitis, its types, epidemiology, symptoms and complications. Results: Although it can affect people of all ages, viral infections are the most prevalent cause of viral encephalitis, which is typically seen in young children and old people. Arboviruses, rhabdoviruses, enteroviruses, herpesviruses, retroviruses, orthomyxoviruses, orthopneumoviruses, and coronaviruses are just a few of the viruses that have been known to cause encephalitis. Conclusion: As new viruses emerge, diagnostic techniques advan

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Publication Date
Sun Jan 01 2023
Journal Name
International Journal Of Research In Social Sciences &amp; Humanities
Corporate Governance: Article Review
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The purpose of this article is to provide a comprehensive definition of corporate governance and to review the existing literature on the subject. The researchers examine various corporate governance theories, including agency theory, stakeholder theory, and resource-based theory. The study concludes by emphasizing that the primary goal of corporate governance theories is not to examine how managers govern but rather to analyze how governance operates in an company.

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Publication Date
Fri Jul 24 2026
Journal Name
Economic Sciences
Subject Review: Strategic mind
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