Lanthanum-Doped Graphene for Electrocatalytic Reduction of Nitrogen Monoxide

Electrocatalytic conversion of nitrogen oxides is a promising approach to address nitrogen pollution in underground water. Nitrogen oxides, such as nitrate and nitrite, can be reduced to N2 and NH3 over an electrocatalyst, with NO as the key intermediate, subsequent reaction of which controls the overall activity and selectivity. Here, we report density functional theory calculations of NO electrocatalytic reduction (NOER) over lanthanum embedded in graphene, through which we show that the localized states in La drive the reaction favorably due to more pronounced molecular adsorption and charge transfer than transition metals such as Co. The free energy profiles are compared between the La-based single-atom catalyst (SAC) and Co-based SAC, for producing N2 and NH3. We find that the La-SAC intensifies the electron transfer to the adsorbed NO, promoting the first protonation step of NO, which is the potential-limiting step on the Co-SAC. Also, an intriguing effect of the water solvent is revealed on the La-SAC. In addition to stabilizing the intermediate species, water molecules that are coordinated with La participate directly in the protonation steps, enhancing the catalyst activity. This study reveals the unique mechanism of NOER over rare-earth-based catalysts, highlighting the potential application of atomically dispersed f-block elements for electrocatalytic reactions

Density Functional Theory Studies on the Structures and Water-Exchange Reactions of Aqueous Al(III)–Oxalate Complexes

The structures and water-exchange reactions of aqueous aluminum-oxalate complexes are investigated using density functional theory. The present work includes (1) The structures of Al(C2O4)(H2O)4+ and Al(C2O4)2(H2O)2– were optimized at the level of B3LYP/6-311+G(d,p). The geometries obtained suggest that the AlOH2 bond lengths trans to C2O42‑ ligand in Al(C2O4)(H2O)4+ are much longer than the AlOH2 bond lengths cis to C2O42‑. For Al(C2O4)2(H2O)2–, the close energies between cis and trans isomers imply the coexistence in aqueous solution. The 27Al NMR and 13C NMR chemical shifts computed with the consideration of sufficient solvent effect using HF GIAO method and 6-311+G(d,p) basis set are in agreement with the experimental values available, indicating the appropriateness of the applied models; (2) The water-exchange reactions of Al(III)–oxalate complexes were simulated at the same computational level. The results show that water exchange proceeds via dissociative pathway and the activation energy barriers are sensitive to the solvent effect. The energy barriers obtained indicate that the coordinated H2O cis to C2O42‑ in Al(C2O4)(H2O)4+ is more labile than trans H2O. The water-exchange rate constants (kex) of trans- and cis-Al(C2O4)2(H2O)2– were estimated by four methods and their respective characteristics were explored; (3) The significance of the study on the aqueous aluminum-oxalate complexes to environmental chemistry is discussed. The influences of ubiquitous organic ligands in environment on aluminum chemistry behavior can be elucidated by extending this study to a series of Al(III)–organic system

Enhancement of Perpendicular Magnetic Anisotropy and Curie Temperature in V‑Doped Two-Dimensional CrSI Janus Semiconductor Monolayer

Two-dimensional (2D) intrinsic ferromagnetic semiconductors (FMSs) with high Curie temperatures (TC) and large perpendicular magnetic anisotropy (PMA) have immense potential in spintronic applications. Recently, the TC of the discovered 2D intrinsic FMSs is below room temperature, and the easy magnetization axis (EMA) is oriented in the in-plane direction. Here, using the first-principle calculations and the Monte Carlo simulations, we investigate the effect of V doping on structure, electronic structure, and magnetic properties of the CrVS2I2 monolayer. The calculated formation energy, phonon dispersion, ab initio molecular dynamics simulations, and elastic constants of the CrVS2I2 monolayer indicate that it is stable at room temperature. More importantly, V doping converts the EMA direction of the CrVS2I2 monolayer from in-plane to out-of-plane, accompanied by a significant enhancement of magnetic anisotropy energy from 0.0011 to 0.997 meV/atom, and it also enhances TC from 175 to 352 K. Moreover, the CrVS2I2 monolayer remains as a semiconductor with a direct band gap of 0.38 eV. Our findings provide a feasible route for the realization of high TC and large PMA in 2D intrinsic FMSs

Additional file 2 of Hospital mortality of blunt abdominal aortic injury (BAAI): a systematic review and meta-analysis

Additional file2. Search terms forliteratures

Additional file 1 of Hospital mortality of blunt abdominal aortic injury (BAAI): a systematic review and meta-analysis

Additional file 1. PRISMA 2020 checklist

Tuning Stiffness of Free-Standing Hydrogen-Bonded LbL Films with Fe³⁺ Coordination

Layer-by-layer (LbL) assembly of polymers through hydrogen bonding is a versatile technique for building ultrathin functional films. However, the hygroscopic nature of the polymer building blocks and hydrogen-bonding propensity of water can render the assembled films sensitive to environmental conditions, especially humidity, resulting in the low stiffness of such films. In this paper, we report a simple approach to cross-link free-standing hydrogen-bonded LbL films by coordination with iron­(III). The stiffnesses of these films increased by three orders of magnitude upon cross-linking with Fe3+, allowing the films to be handled and manipulated easily at high humidity. Moreover, we used the photoinduced reduction of the coordinated iron­(III) ions to demonstrate the potential for tuning the mechanical properties of these films using light. In sum, this paper demonstrates a simple and effective approach for strengthening and tuning the mechanical properties of hydrogen-bonded LbL films

Charge Inversion, Water Splitting, and Vortex Suppression Due to DNA Sorption on Ion-Selective Membranes and Their Ion-Current Signatures

The physisorption of negatively charged single-stranded DNA (ssDNA) of different lengths onto the surface of anion-exchange membranes is sensitively shown to alter the anion flux through the membrane. At low surface concentrations, the physisorbed DNAs act to suppress an electroconvection vortex instability that drives the anion flux into the membrane and hence reduce the overlimiting current through the membrane. Beyond a critical surface concentration, determined by the total number of phosphate charges on the DNA, the DNA layer becomes a cation-selective membrane, and the combined bipolar membrane has a lower net ion flux, at low voltages, than the original membrane as a result of ion depletion at the junction between the cation- (DNA) and anion-selective membranes. However, beyond a critical voltage that is dependent on the ssDNA coverage, water splitting occurs at the junction to produce a larger overlimiting current than that of the original membrane. These two large opposite effects of polyelectrolyte counterion sorption onto membrane surfaces may be used to eliminate limiting current constraints of ion-selective membranes for liquid fuel cells, dialysis, and desalination as well as to suggest a new low-cost membrane surface assay that can detect and quantify the number of large biomolecules captured by probes functionalized on the membrane surface

Charge Inversion, Water Splitting, and Vortex Suppression Due to DNA Sorption on Ion-Selective Membranes and Their Ion-Current Signatures

The physisorption of negatively charged single-stranded DNA (ssDNA) of different lengths onto the surface of anion-exchange membranes is sensitively shown to alter the anion flux through the membrane. At low surface concentrations, the physisorbed DNAs act to suppress an electroconvection vortex instability that drives the anion flux into the membrane and hence reduce the overlimiting current through the membrane. Beyond a critical surface concentration, determined by the total number of phosphate charges on the DNA, the DNA layer becomes a cation-selective membrane, and the combined bipolar membrane has a lower net ion flux, at low voltages, than the original membrane as a result of ion depletion at the junction between the cation- (DNA) and anion-selective membranes. However, beyond a critical voltage that is dependent on the ssDNA coverage, water splitting occurs at the junction to produce a larger overlimiting current than that of the original membrane. These two large opposite effects of polyelectrolyte counterion sorption onto membrane surfaces may be used to eliminate limiting current constraints of ion-selective membranes for liquid fuel cells, dialysis, and desalination as well as to suggest a new low-cost membrane surface assay that can detect and quantify the number of large biomolecules captured by probes functionalized on the membrane surface

A meta-analysis of tumor necrosis factor-α and <i>FAS/FASL</i> polymorphisms with risk of pre-eclampsia

Previous observations investigated the association of tumor necrosis factor-α (TNF-α), FAS and FASL polymorphisms with the risk of pre-eclampsia (PE). Conflicting results, however, were obtained. In this study, we aimed to evaluate the association between TNF-α −308 A/G, −850 C/T, −238 A/G, FAS −670 A/G, and FASL −844 C/T and PE risk using a meta-analysis. Pubmed, EBSCO, Embase, China National Knowledge Infrastructure, and Wanfang databases were searched up to April 10th 2018. Summarized odds ratios (ORs) with 95% confidence intervals (CIs) for the association between the five polymorphisms and PE risk were computed using a fixed or random effects model. The TNF-α −308 GA and GA/AA genotypes were associated with increased risks of PE in Asians (heterozygous comparison: OR = 2.68, 95% CI, 1.07–6.66; dominant model: OR = 2.70, 95% CI, 1.08–6.73) rather than in Caucasians. The FAS −670 AA genotype was associated with increased risks of PE in both overall analysis (heterozygous comparison: OR = 1.69, 95% CI, 1.17–2.45; homozygous comparison: OR = 2.47, 95% CI, 1.62–3.76; dominant model: OR = 1.91, 95% CI, 1.31–2.78; and recessive model: OR = 1.97, 95% CI, 1.35–2.87) and subgroup analyses. No significant association was found between TNF-α −850 C/T, −238 A/G and FASL −844 C/T polymorphisms and PE risk. These findings indicate that FAS −670 A/G polymorphism may be a susceptibility gene for the development of PE. Further genetic association studies with sufficient sample sizes are a research priority to confirm these findings.</p

Regulation of Local Site Structures to Stabilize Mixed-Valence Eu^2+/3+ under a Reducing Atmosphere for Multicolor Photoluminescence

Co-doping mixed-valence Eu2+/3+ in a single-phase phosphor is an efficient method to realize the emission color regulation, which holds great potential for anticounterfeiting and ratiometric temperature sensing. Here, the mixed-valence Eu-doped Sr1.95+xLi1–xSi1–xAlxO4F (0 ≤ x ≤ 0.25) phosphors were designed and prepared under a reducing atmosphere. The correlation of local phase structures and luminescence properties was discussed. Replacing Si4+–Li+ ion pairs with Al3+–Sr2+ ion pairs compresses the Sr sites occupied by Eu2+, and it stabilizes Eu3+ in a reducing atmosphere and leads to the coexistence of Eu2+ and Eu3+ in single-phase Sr1.95+xLi1–xSi1–xAlxO4F:0.05Eu (0 ≤ x ≤ 0.25) phosphors. Based on the wavelength-dependent luminescence color behaviors of Sr1.95+xLi1–xSi1–xAlxO4F:0.05Eu phosphors, the fluorescent anticounterfeit papers/patterns containing Sr1.95+xLi1–xSi1–xAlxO4F:0.05Eu phosphors were the same as ordinary paper under ambient conditions. However, the hidden colors or images can be read out with green-orange luminescence under 365/300 nm light excitation. Benefiting from the diverse thermal response emission behaviors of Eu2+ (530 nm) and Eu3+ (703 nm), Sr1.95+xLi1–xSi1–xAlxO4F:0.05Eu phosphors exhibit temperature sensing performances, with the maximum absolute and relative sensitivity being 0.0294 K–1 at 573 K and 0.83% K–1 at 348 K. More importantly, Sr1.95+xLi1–xSi1–xAlxO4F:0.05Eu phosphors showed excellent stability in humid, acid, and alkali environments, which contributed to applying mixed-valence Eu2+/3+-doped Sr1.95+xLi1–xSi1–xAlxO4F to the fields of multicolor anticounterfeiting and noncontact optical thermometry