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Inorganic Chemistry Jul 2024The electrochemical conversion of nitrate pollutants into value-added ammonia (NH) is an appealing alternative synthetic route for sustainable NH production. However,...
The electrochemical conversion of nitrate pollutants into value-added ammonia (NH) is an appealing alternative synthetic route for sustainable NH production. However, the development of the electrocatalytic nitrate-to-ammonia reduction reaction (NORR) has been hampered by unruly reactants and products at the interface and the accompanied sluggish kinetic rate. In this work, a built-in positive valence space is successfully constructed over FeCu nanocrystals to rationally regulate interfacial component concentrations and positively shift the chemical equilibrium. With positive valence Cu optimizing the active surface, the space between the stern and shear layers becomes positive, which is able to continuously attract the negatively charged NO reactant and repulse the positively charged NH product even under high current density, thus significantly boosting the NORR kinetics. The system with a built-in positive valence space affords an ampere-level NORR performance with the highest NH yield rate of 150.27 mg h mg at -1.3 V versus RHE with an outstanding NH current density of 189.53 mA cm, as well as a superior Faradaic efficiency (FE) of 97.26% at -1.2 V versus RHE. The strategy proposed here underscores the importance of interfacial concentration regulation and can find wider applicability in other electrochemical syntheses suffering from sluggish kinetics.
PubMed: 38946339
DOI: 10.1021/acs.inorgchem.4c01264 -
ACS Applied Materials & Interfaces Jun 2024The practical applications of bifunctional ruthenium-based electrocatalysts with two active sites of Ru nanoparticles covered with RuO skins are limited. One reason is...
The practical applications of bifunctional ruthenium-based electrocatalysts with two active sites of Ru nanoparticles covered with RuO skins are limited. One reason is the presence of multiple equally distributed facets, some of which are inactive. In contrast, ruthenium nanorods with a high aspect ratio have multiple unequally distributed facets containing the dominance of active faces for efficient electrocatalysis. However, the synthesis of ruthenium nanorods has not been achieved due to difficulties in controlling the growth. Additionally, it is known that the adsorption capacity of intermediates can be impacted by the surface of the catalyst. Inspired by these backgrounds, the surface-modified (SM) ruthenium nanorods having a dominant active facet of hcp (100) through chemisorbed oxygen and OH groups (SMRu-NRs@NF) are rationally synthesized through the surfactant coordination method. SMRu-NRs@NF exhibits excellent hydrogen evolution in acid and alkaline solutions with an ultralow overpotential of 215 and 185 mV reaching 1000 mA cm, respectively. Moreover, it has also shown brilliant oxygen evolution electrocatalysis in alkaline solution with a low potential of 1.58 V to reach 1000 mA cm. It also exhibits high durability over 143 h for the evolution of oxygen and hydrogen at 1000 mA cm. Density functional theory studies confirmed that surface modification of a ruthenium nanorod with chemisorbed oxygen and OH groups can optimize the reaction energy barriers of hydrogen and oxygen intermediates. The surface-modified ruthenium nanorod strategy paves a path to develop the practical water splitting electrocatalyst.
PubMed: 38941512
DOI: 10.1021/acsami.4c05286 -
Scientific Reports Jun 2024We utilize a Fourier transformation-based representation of Maxwell's equations to develop physics-constrained neural networks for electrodynamics without gauge...
We utilize a Fourier transformation-based representation of Maxwell's equations to develop physics-constrained neural networks for electrodynamics without gauge ambiguity, which we label the Fourier-Helmholtz-Maxwell neural operator method. In this approach, both of Gauss's laws and Faraday's law are built in as hard constraints, as well as the longitudinal component of Ampère-Maxwell in Fourier space, assuming the continuity equation. An encoder-decoder network acts as a solution operator for the transverse components of the Fourier transformed vector potential, , whose two degrees of freedom are used to predict the electromagnetic fields. This method was tested on two electron beam simulations. Among the models investigated, it was found that a U-Net architecture exhibited the best performance as it trained quicker, was more accurate and generalized better than the other architectures examined. We demonstrate that our approach is useful for solving Maxwell's equations for the electromagnetic fields generated by intense relativistic charged particle beams and that it generalizes well to unseen test data, while being orders of magnitude quicker than conventional simulations. We show that the model can be re-trained to make highly accurate predictions in as few as 20 epochs on a previously unseen data set.
PubMed: 38926466
DOI: 10.1038/s41598-024-65650-9 -
Science (New York, N.Y.) Jun 2024The oxygen evolution reaction is the bottleneck to energy-efficient water-based electrolysis for the production of hydrogen and other solar fuels. In proton exchange...
The oxygen evolution reaction is the bottleneck to energy-efficient water-based electrolysis for the production of hydrogen and other solar fuels. In proton exchange membrane water electrolysis (PEMWE), precious metals have generally been necessary for the stable catalysis of this reaction. In this work, we report that delamination of cobalt tungstate enables high activity and durability through the stabilization of oxide and water-hydroxide networks of the lattice defects in acid. The resulting catalysts achieve lower overpotentials, a current density of 1.8 amperes per square centimeter at 2 volts, and stable operation up to 1 ampere per square centimeter in a PEMWE system at industrial conditions (80°C) at 1.77 volts; a threefold improvement in activity; and stable operation at 1 ampere per square centimeter over the course of 600 hours.
PubMed: 38900890
DOI: 10.1126/science.adk9849 -
Dalton Transactions (Cambridge, England... Jun 2024Nuclear magnetic resonance (NMR) chemical shifts and the magnetically induced current density (MICD) susceptibility of four osmium containing molecules have been...
Nuclear magnetic resonance (NMR) chemical shifts and the magnetically induced current density (MICD) susceptibility of four osmium containing molecules have been calculated at the density functional theory (DFT) level using three relativistic levels of theory. The calculations were performed at the quasi-relativistic level using an effective core potential (ECP) for Os, at the all-electron scalar exact two-component (X2C) relativistic level, and at the relativistic X2C level including spin-orbit coupling (SO-X2C). In earlier studies, the osmapentalene (1) and the osmapentalynes (2 and 3) were considered Craig-type Möbius aromatic and it was suggested that the analogous osmium compound (4) is Craig-type Möbius antiaromatic. Here, the ring-current strengths were obtained with the gauge including magnetically induced currents (GIMIC) method by integrating the MICD susceptibility passing through planes that intersect chemical bonds and by line integration of the induced magnetic field using Ampère-Maxwell's law. The ring-current calculations suggest that 1, 2 and 3 are weakly aromatic and that 4 is nonaromatic. The accuracy of the MICD susceptibility was assessed by comparing calculated NMR chemical shifts to available experimental data. Visualization of the MICD susceptibility shows that the ring current does not pass from one side of the molecular plane to the other, which means that the MICD susceptibility of the studied molecules does not exhibit any Möbius topology as one would expect for Craig-type Möbius aromatic and for Craig-type Möbius antiaromatic molecules. Thus, molecules 1-3 are not Craig-type Möbius aromatic and molecule 4 is not Craig-type Möbius antiaromatic as previously suggested. Calculations of the H NMR and C NMR chemical shifts of atoms near the Os atom show the importance of including spin-orbit effects. Overall, our study revisits the understanding of the aromaticity of organometallic molecules containing transition metals.
PubMed: 38888198
DOI: 10.1039/d4dt01110d -
Arthroscopy : the Journal of... Jun 2024This multicenter study aimed to determine the incidence of lateral meniscus posterior root tears (LMPRTs) in patients undergoing ACL reconstruction and identify...
Male sex, revision surgery, low volume of anterior cruciate ligament remnant, and significant instability are risk factors for Posterior Root Tear of the Lateral Meniscus in patients undergoing Anterior Cruciate Ligament Reconstruction.
PURPOSE
This multicenter study aimed to determine the incidence of lateral meniscus posterior root tears (LMPRTs) in patients undergoing ACL reconstruction and identify associated risk factors.
METHODS
We conducted a retrospective, multicenter study using data from the Francophone Arthroscopic Society's registry. The study included all the patients in the registry who underwent ACL reconstruction surgery between June 2020 and June 2023, we excluded incomplete data. We compared delay from injury to surgery between LMPRTs group and No LMPRTs group. Variables investigated as potential risk factors for LMPRTs included age, sex, nature of surgery (primary or revision), pivot shift test result, side-to-side laxity under anesthesia, presence of ACL remnant, occurrence of medial meniscal tear, and presence of collateral ligament injury. Risk factors were analyzed using a logistic regression model.
RESULTS
Among the 5359 patients analyzed, LMPRTs occurred in 7.0% (n=375) of cases during ACL reconstruction. Mean age at surgery was 29.3 +/- 10.3 years old [11-77]. Concerning delay to surgery, the mean time was 8.4 +/- 23.1 weeks [0.0-347.2] in the No LMPRTs group and 6.5 +/- 10.2 weeks [0.2-61.6] in the LMPRTs group (p = 0.109). Univariate analysis revealed that male sex (p < 0.001), revision surgery (p < 0.001), medial meniscal injury (p = 0.007), ACL remnant (0% vs > 70%, <10% vs > 70%, 10 to 30% vs > 70%, 30 to 50% vs > 70%, 50 to 70% vs > 70%; p < 0.001) and higher pivot shift grade (p = 0.011) were significantly associated with a presence of LMPRTs. Age, side-to-side laxity, and collateral ligament injury were not found to be significant risk factor In multivariate analysis : male sex, revision surgery, pivot shift test result and a low volume of ACL remnant remained significant. Side to side laxity was also a significant factor in multivariate analysis.
CONCLUSION
This study identified male sex, revision surgery, low volume of ACL remnant, side to side laxity and higher grade of pivot shift as significant risk factors for LMPRTs during ACL reconstruction.
PubMed: 38876444
DOI: 10.1016/j.arthro.2024.05.028 -
Dalton Transactions (Cambridge, England... Jun 2024LiFeOHS is a material with Li(OH) layers intercalated between FeS planes. Its hydrothermal synthesis in various concentrations of LiOH yields materials with a high...
LiFeOHS is a material with Li(OH) layers intercalated between FeS planes. Its hydrothermal synthesis in various concentrations of LiOH yields materials with a high non-stoichiometry of the Li/Fe ratio which can be explained by partial substitution of Li for Fe in the Li(OH) layers. Thermogravimetry, X-ray diffraction and Mössbauer studies indicate that the charge balance is obtained by substitution of hydroxyl ions OH by oxide ions O. This material has been tested as an electrode for lithium-ion batteries against lithium metal. Specific capacities above 200 mA h g at C/10 are achieved, involving 1 lithium per chemical formula when cycled between 1 V and 3 V lithium. The first irreversible discharge leads to the insertion of one lithium atom and the evolution of hydrogen gas while iron remains in its +2-oxidation state. An original LiOFeS oxysulfide is formed. The following reversible oxidation/reduction cycles involve the Fe/Fe redox couple between the two limiting compositions: LiOFeS and LiOFeS.
PubMed: 38874566
DOI: 10.1039/d4dt00405a -
Clinical Journal of the American... Jun 2024
PubMed: 38865192
DOI: 10.2215/CJN.0000000000000514 -
Analytical Methods : Advancing Methods... Jun 2024This study presents the first insights into vinpocetine (VIN) behavior, a nootropic compound, on a glassy carbon electrode (GCE). Cyclic voltammetry (CV) revealed an...
This study presents the first insights into vinpocetine (VIN) behavior, a nootropic compound, on a glassy carbon electrode (GCE). Cyclic voltammetry (CV) revealed an irreversible oxidation peak at +1.0 V ( Ag/AgCl), with pH dependency indicating proton involvement in the electrochemical reaction. Density functional theory (DFT) optimized VIN's molecular geometry, while Fukui functions and dual descriptors elucidated its reactivity for a more straightforward exploration of the complete electrooxidation mechanism. Differential pulse voltammetry (DPV) demonstrated VIN sensing capabilities within a concentration range of 0.20 to 12.8 mg L, with a theoretical limit of detection (LOD) at 0.07 mg L, using optimized conditions of supporting electrolyte. The method showed selectivity in the presence of excipients and interfering species commonly found in pharmaceutical formulations. Recovery tests yielded 95.5% ( = 3), and quantification in pharmaceutical formulations showed no significant differences compared to the reference method based on HPLC DAD. This novel electroanalytical method holds promise for VIN nootropic sensing and routine pharmaceutical analysis.
Topics: Vinca Alkaloids; Oxidation-Reduction; Electrochemical Techniques; Electrodes; Limit of Detection
PubMed: 38855859
DOI: 10.1039/d4ay00598h -
Nature Communications Jun 2024Achieving satisfactory multi-carbon (C) products selectivity and current density under acidic condition is a key issue for practical application of electrochemical CO...
Achieving satisfactory multi-carbon (C) products selectivity and current density under acidic condition is a key issue for practical application of electrochemical CO reduction reaction (CORR), but is challenging. Herein, we demonstrate that combining microenvironment modulation by porous channel structure and intrinsic catalytic activity enhancement via doping effect could promote efficient CORR toward C products in acidic electrolyte (pH ≤ 1). The La-doped Cu hollow sphere with channels exhibits a C products Faradaic efficiency (FE) of 86.2% with a partial current density of -775.8 mA cm. CO single-pass conversion efficiency for C products can reach 52.8% at -900 mA cm. Moreover, the catalyst still maintains a high C FE of 81.3% at -1 A cm. The channel structure plays a crucial role in accumulating K and OH species near the catalyst surface and within the channels, which effectively suppresses the undesired hydrogen evolution and promotes C-C coupling. Additionally, the La doping enhances the generation of *CO intermediate, and also facilitates C products formation.
PubMed: 38844773
DOI: 10.1038/s41467-024-49308-8