Compounds

17 pages, 18853 KiB

Open AccessFeature PaperArticle

Mechanical Properties of Spark Plasma Sintering-Processed Pure Ti and Ti-6Al-4V Alloys: A Comparative Study between Harmonic and Non-Harmonic Microstructures

by Tarik Sadat, Kyohei Hayashi, Gregory Haugou, Herve Morvan, Eric Markiewicz, Laurent Dubar, Maxence Bigerelle, Kei Ameyama and Guy Dirras

Compounds 2021, 1(1), 41-57; https://0-doi-org.brum.beds.ac.uk/10.3390/compounds1010005 - 17 May 2021

Cited by 5 | Viewed by 3600

Abstract

Microstructure characteristics and compressive property relationships of so-called harmonic (composed by fine and coarse grains) and conventional pure titanium (Ti) and Ti-6Al-4V alloy processed by powder metallurgy route are presented in the present work. Electron backscatter diffraction (EBSD) analysis was performed to characterize [...] Read more.

Microstructure characteristics and compressive property relationships of so-called harmonic (composed by fine and coarse grains) and conventional pure titanium (Ti) and Ti-6Al-4V alloy processed by powder metallurgy route are presented in the present work. Electron backscatter diffraction (EBSD) analysis was performed to characterize the as-processed microstructures. The harmonicity structure of selected samples is described, and relevant EBSD maps are presented. The bulk samples’ hardness is reported, along with compressive responses at quasi-static and intermediate strain rates, ranging from 0.005 s⁻¹ to 16 s⁻¹. The strain rate sensitivity of these metallic samples is discussed, and the benefits in terms of mechanical properties of the harmonic microstructures compared with the non-harmonic conventional ones are highlighted. Finally, a modified Johnson–Cook model was shown to predict fairly the experimental results. Full article

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12 pages, 3451 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

A Novel Quinoxaline-Rhodamine Conjugate for a Simple and Efficient Detection of Hydrogen Sulphate Ion

by Sutapa Sahu, Yeasin Sikdar, Riya Bag, Dilip K. Maiti, José P. Cerón-Carrasco and Sanchita Goswami

Compounds 2021, 1(1), 29-40; https://0-doi-org.brum.beds.ac.uk/10.3390/compounds1010004 - 08 Apr 2021

Cited by 3 | Viewed by 2919

Abstract

This work presents the development of a quinoxaline and rhodamine conjugate system that acts as a colorimetric chemosensor for hydrogen sulfate (

{HSO}_{4}^{-}

) ions in methanol media. This sensor has been characterized both theoretically and experimentally. The detection limits for [...] Read more.

This work presents the development of a quinoxaline and rhodamine conjugate system that acts as a colorimetric chemosensor for hydrogen sulfate (

{HSO}_{4}^{-}

) ions in methanol media. This sensor has been characterized both theoretically and experimentally. The detection limits for

{HSO}_{4}^{-}

are small as 0.71 µM and 3.8 µM for the absorption and emission experiments, respectively. The effectiveness of the probe in recognizing

{HSO}_{4}^{-}

both in gel and solid phase is evaluated as well. Thus, this works presents a simple strategy to detect the environmental

{HSO}_{4}^{-}

pollutant event at tiny concentrations. Full article

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14 pages, 4847 KiB

Open AccessFeature PaperArticle

Oxovanadium(V/IV) Complexes as Redox Mediators for Biofuel Cells: Physical, Magnetic, and Electrochemical Characterization, DFT and Molecular Docking

by Natsuki Katsuumi, Hiba Sehimi, Sayantan Pradhan, Sanyobi Kim, Tomoyuki Haraguchi and Takashiro Akitsu

Compounds 2021, 1(1), 15-28; https://0-doi-org.brum.beds.ac.uk/10.3390/compounds1010003 - 29 Mar 2021

Cited by 2 | Viewed by 2755

Abstract

Based on the potential redox and catalytic ability of oxovanadium complexes, our goal was to characterize the physical properties of two such complexes to be used as mediators for laccase. Computational studies, TD-DFT calculations and docking simulations were performed to elucidate the interaction [...] Read more.

Based on the potential redox and catalytic ability of oxovanadium complexes, our goal was to characterize the physical properties of two such complexes to be used as mediators for laccase. Computational studies, TD-DFT calculations and docking simulations were performed to elucidate the interaction between laccase and the two anionic complexes (aquabis(oxalato)oxidovanadate(IV) (1) and bis(oxalato)dioxidovanadate(V)) (2), respectively. Electrochemical measurements carried out on anion complexes of 1 and 2 docked into laccase were compared to laccase alone, showing changes in oxidation-reduction potential and current value, especially with the oxovanadium anion of 2. Since both internal tiny magnetic fields of ferromagnetic catalysts and external applied magnetic fields were found in previous investigations to constitute effective ways to improve the oxygen transfer rate, the magnetic susceptibility was measured. A valence change proneness was confirmed with higher valence for the oxovanadium anion of 2, which is in accordance with the electrochemical results. Full article

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12 pages, 3479 KiB

Open AccessEditor’s ChoiceArticle

Hf-Based UiO-66 as Adsorptive Compound and Oxidative Catalyst for Denitrogenation Processes

by Rui G. Faria, Diana Julião, Salete S. Balula and Luís Cunha-Silva

Compounds 2021, 1(1), 3-14; https://0-doi-org.brum.beds.ac.uk/10.3390/compounds1010002 - 19 Jan 2021

Cited by 8 | Viewed by 5076

Abstract

A series of porous metal–organic frameworks (MOFs) of the UiO-66 family, namely UiO-66(Zr), UiO-66(Hf) and UiO-66(Hf)-NH₂, prepared by solvothermal procedures were characterized, and their catalytic efficiency for oxidative denitrification (ODN) was investigated for the first time. Sustainable denitrogenation systems combining adsorption [...] Read more.

A series of porous metal–organic frameworks (MOFs) of the UiO-66 family, namely UiO-66(Zr), UiO-66(Hf) and UiO-66(Hf)-NH₂, prepared by solvothermal procedures were characterized, and their catalytic efficiency for oxidative denitrification (ODN) was investigated for the first time. Sustainable denitrogenation systems combining adsorption and oxidative catalytic capacity were designed using a model diesel containing two distinct nitrogen compounds (NCs) in a solvent-free medium and using an environment-friendly oxidant (H₂O₂). An efficient adsorptive denitrogenation process was only achieved after long reaction times (24 h): using the Hf-based MOFs, the adsorptive denitrogenation increased from 19% to 79% at 5 to 24 h, while the UiO-66(Zr) reached 76% after 24 h, although the absence of adsorption capacity after 5 h. UiO-66(Hf) and UiO-66(Hf)-NH₂ also revealed superior oxidative catalytic denitrogenation than UiO-66(Zr), attaining 97% of efficiency instead of 80%. ODN processes demonstrated to be more effective than the adsorptive denitrogenation, mainly during the first hours of the process. In addition, the metal center in the MOF structure had a larger influence than the presence of the amine-functional groups. Hf-based compounds revealed higher denitrogenation efficiency than the UiO-66(Zr) for a shorter reaction time (5 h). Full article

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