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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 Oct 30 2018
Journal Name
Acs Omega
Catalytic Hydrogenation of <i>p</i>-Chloronitrobenzene to <i>p</i>-Chloroaniline Mediated by γ-Mo<sub>2</sub>N
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Promoting the production of industrially important aromatic chloroamines over transition-metal nitrides catalysts has emerged as a prominent theme in catalysis. This contribution provides an insight into the reduction mechanism of p-chloronitrobenzene (p-CNB) to p-chloroaniline (p-CAN) over the γ-Mo2N(111) surface by means of density functional theory calculations. The adsorption energies of various molecularly adsorbed modes of p-CNB were computed. Our findings display that, p-CNB prefers to be adsorbed over two distinct adsorption sites, namely, Mo-hollow face-centered cubic (fcc) and N-hollow hexagonal close-packed (hcp) sites with adsorption energies of −32.1 and −38.5 kcal/mol, respectively. We establish that the activation of nit

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Publication Date
Wed Aug 01 2018
Journal Name
Journal Of Economics And Administrative Sciences
The Exchange Rate of Iraqi Dinar between De facto Regime and De jure Regime in the Iraq during (2004-2012)
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         The understanding exchange rate policy is fundamental in order to identify the mechanism by which works out macroeconomic, And the vital for macroeconomic analysis and empirical work to differentiate between the de facto regimes and de jure regimes, Where the proved surveys and studies issued by the international monetary fund that there is divergence between the de facto regime (Regime of exchange applied by the country actually) and between the de jure regime (Regime de jure through the documents and formal writings of officials of the central bank), And launched studies on the de facto regime (Being a the basis of evaluating monetary policy) Stabilized (peg-like)arrangements or

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Publication Date
Fri Nov 01 2024
Journal Name
Heliyon
Strength and Deformation of Encased Concrete Columns by I- Section Steel and I- Section GFRP Subjected to Different Load Conditions
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Publication Date
Sun Mar 01 2026
Journal Name
Journal Of Molecular Structure
Synthesis, characterization, DFT calculations, molecular docking, ADMET analysis and biological activity of Schiff base metal complexes against colon cancer cells
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Publication Date
Thu Dec 06 2018
Journal Name
Iraqi Journal Of Pharmaceutical Sciences ( P-issn 1683 - 3597 E-issn 2521 - 3512)
Impact of Osteocalcin Level on Vascular Calcification in Type 2 Diabetics in Relation to Fibroblast Growth Factor-23(FGF-23)
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The present study aimed to assess the potential impact of serum concentration of undercarboxylated osteocalcin (the active form of osteocalcin) and fibroblast growth factor-23 on the incidence of cardiovascular diseases in type 2 diabetics with carotid artery calcification and the possible association with metabolic changes in relation to glucose and minerals homeostasis.

This study included 52 men with carotid artery calcification type 2 diabetes mellitus. These patients were categorized; as follows: group A includes 30 patients who had cardiovascular disease and group B includes 22 patients who had no cardiovascular disease. These groups were compared with 25 apparently healthy control (Group C). 

It has been shown

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Publication Date
Sat Oct 28 2023
Journal Name
Baghdad Science Journal
Synthesis, Characterization and Theoretical Investigation of Innovative Charge-transfer Complexes Derived from the N-phenyl 3, 4-selenadiazo Benzophenone Imine
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In the current study, a direct method was used to create a new series of charge-transfer complexes of chemicals. In a good yield, new charge-transfer complexes were produced when different quinones reacted with acetonitrile as solvent in a 1:1 mole ratio with N-phenyl-3,4-selenadiazo benzophenone imine. By using analysis techniques like UV, IR, and 1H, 13C-NMR, every substance was recognized. The analysis's results matched the chemical structures proposed for the synthesized substances. Functional theory of density (DFT)
has been used to analyze the molecular structure of the produced Charge-Transfer Complexes, and the energy gap, HOMO surfaces, and LUMO surfaces have all been created throughout the geometry optimization process ut

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Publication Date
Sat Mar 01 2014
Journal Name
International Journal For Sciences And Technology
Preparation of Carboxy Methylated mPEG-Block-(4-Dodecyl Anilide) Copolymers and Their Visco Metric and Surface Tension Properties in THF
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Preparation of Carboxy Methylated mPEG-Block-(4-Dodecyl Anilide) Copolymers and Their Visco Metric and Surface Tension Properties in THF

Publication Date
Wed Dec 14 2022
Journal Name
Bulletin Of The Chemical Society Of Ethiopia
Synthesis, characterization, theoretical study and biological evaluation of Schiff base and their La(III), Ce(IV) and UO2(II) complexes
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ABSTRACT. A new three metal complexes of La(III), Ce(IV) and UO2(II) ions have been synthesized based on a Schiff base derived from the condensation of L-histidine and anisaldehyde. All prepared compounds were characterized by different spectroscopic techniques and Density-functional theory (DFT) calculations. The complexes were proposed to have an octahedral structure based on the investigated results. The optimized shape, numbering system, and dipole moment vector of Ligand and La, Ce, and UO2 (1:1) chelates were investigated. The Schiff base ligand and complexes exhibit moderate action against all of the bacteria tested, with P. aeruginosa, Klebsiella sp., and E. faecalis respectively being the order of inhibition.  

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Publication Date
Sat Jan 03 2026
Journal Name
Journal Of Molecular Structure
Synthesis, characterization, DFT calculations, molecular docking, ADMET analysis and biological activity of Schiff base metal complexes against colon cancer cells
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Publication Date
Sun Mar 01 2026
Journal Name
Journal Of Molecular Structure
Synthesis, characterization, DFT calculations, molecular docking, ADMET analysis and biological activity of Schiff base metal complexes against colon cancer cells
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