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Microplastic (MPs) contamination in groundwater has received massive attention since plastic waste has been released directly into the environment. This study investigates MPs contamination in groundwater on the Jeju volcanic Island, Korea. To the best of our knowledge, this is the first study to identify MPs in groundwater from volcanic islands. A total of 21 sites were sampled for groundwater wells and springs in July and September (2021). Sampling was performed without cross-contamination through quality assurance and quality control. The results showed that MPs abundance ranged from 0.006 to 0.192 particles/L in groundwater samples. Additionally, MPs were detected in deep groundwater wells where the groundwater level was 143 m below ground surface. Eight MPs polymer types, including polypropylene, polyethylene, polyethylene terephthalate, polyvinyl chloride, polystyrene, polyamide, acrylonitrile butadiene styrene, and polyurethane, were detected using Micro-Fourier Transform Infrared Spectroscopy (μ-FT-IR). Most of the detected MPs size ranged from 20 to 100 μm, accounting for 95% of the total. Fragments and fiber shaped MPs were detected, with the majority of them being fragmented in groundwater samples. The concentrations of MPs and major ions in groundwater showed a positive correlation. A negative correlation was observed between MPs concentration and topographic elevation (r = −0.59, p = 0.01). The source of MPs contamination is most likely attributed to agricultural activities, such as plastic mulching and greenhouses, which account for most of the land use in the study area. In this study, MPs entered the aquifer through the soil at the surface and seeped through cracks in fractured rock on basalt with sealed groundwater wells. This study takes 500 L of samples to prevent sample bias, reveal plastic contamination in groundwater, and indicating the characteristics and sources of contaminated plastics. [Display omitted] • Most MPs detected in groundwater were smaller than 50 μm. • Eight polymers were identified, with PP and PE being dominant types in groundwater. • Predominant shapes of MPs in groundwater were fragments. • MPs abundance and groundwater levels have a negative correlation. [ABSTRACT FROM AUTHOR]

Carbon allotropes have contributed to all aspects of people's lives throughout human history. As emerging carbon-based low-dimensional materials, graphyne family members (GYF), represented by graphdiyne, have a wide range potential applications due to their superior physical and chemical properties. In particular, graphdiyne (GDY), as the leader of the graphyne family, has been practically applied to various research fields since it was first successfully synthesized. GYF have a large surface area, both sp and sp2 hybridization, and a certain band gap, which was considered to originate from the overlap of carbon 2pz orbitals and the inhomogeneous π-bonds of carbon atoms in different hybridization forms. These properties mean GYF-based materials still have many potential applications to be developed, especially in energy storage and catalytic utilization. Since most of the GYF have yet to be synthesized and applications of successfully synthesized GYF have not been developed for a long time, theoretical results in various application fields should be shared to experimentalists to attract more intentions. In this Review, we summarized and discussed the synthesis, structural properties, and applications of GYF-based materials from the theoretical insights, hoping to provide different viewpoints and comments. [ABSTRACT FROM AUTHOR]

Although layered double hydroxides (LDHs) are extensively investigated for oxygen electrocatalysis, their development is hampered by their limited active sites and sluggish reaction kinetics. Here, sulfur mismatch substitution of NiFe–LDH (S–LDH) is demonstrated, which are in‐situ deposited on nitrogen‐doped graphene (S–LDH/NG). This atomic‐level sulfur incorporation leads to the construction of the tailored topological microstructure and the modulated electronic structure for the improved catalytic activity and durability of bifunctional electrocatalysts. The combined computational and experimental results clarify that the electron transfer between the sulfur anion and Fe3+ generates the high‐valence Fe4+ species, while the mismatch substitution of the sulfur anion induces the metallic conductivity, an increased carrier density, and the reduced reaction barrier. Consequently, the as‐fabricated Zn–air battery achieves a high power density of 165 mW cm‐2, a large energy density of 772 Wh kgZn‐1 at 5 mA cm‐2, and long cycle stability for 120 h, demonstrating its real‐life operation. [ABSTRACT FROM AUTHOR]

Polyaniline/gamma aluminum oxide (PAn/γ-Al 2 O 3 ) nanocomposites were synthesized via in situ electropolymerization on gold electrodes and modified electrodes (Au/PAn/γ-Al 2 O 3 ) were used for the detection of vitamin E (VE). The electrochemical and electropolymerization performance of aniline in the presence of γ-Al 2 O 3 nanoparticles improved dramatically. The kinetic results indicate that the polymerization growth rate of PAn in the presence of nanoparticles catalyst on Au electrode is fast. The resulting electrode exhibited excellent performance with regard to detecting VE. The mechanisms of electropolymerization of aniline in presence of γ-Al 2 O 3 nanoparticle catalyst and mechanism of redox behavior of VE are investigated. The limit of detection (LOD) was observed to be around 0.06 μM. The tolerance limits of some important interfering species with VE were studied. [ABSTRACT FROM AUTHOR]

We examined the current groundwater (used for drinking) quality in Pakistan after implementation of Millennium Development Goals, including contaminants, their sources, and relevant health impacts. The drinking water quality parameters of most of the reported results exceeded the guidelines suggested by the World Health Organization (WHO) and National Environmental Quality Standards (NEQS). Natural sources of groundwater contamination have been activated due to anthropogenic activities like mining, and open dumping of industrial and domestic wastes which lead to poor groundwater quality. Globally, 780 million people, and 100 million people in Pakistan are exposed to unsafe water sources. Therefore, this review demonstrates the potential needs to achieve the safe drinking water goal of the Agenda 2030. The development of a proper monitoring network, installation of treatment plants, and implementation of legislations are recommended in this review. [ABSTRACT FROM AUTHOR]

Controlling protein misfolding and accumulation in neurodegeneration is a challenge in chemical neuroscience. The application of appropriate electric fields (EFs) can be a potential noninvasive therapy to treat neuro disorders. The effect of EFs of varying intensities and directions on the conformational dynamics of β-Amyloid40 (Aβ40) under histidine tautomerism has been investigated for the first time. Our findings suggest that peptides tend to align their dipole moments with the orientation of EF. Irrespective of the EF direction, the dipole moment magnitude is affected by the EF strength. With the conformational changes, the EF strength equal to 0.5 V/nm destroyed the β-sheet content of the δδδ isomer as a potentially toxic agent. The content of the alpha-helical structure which can be transformed into the β-sheet is reduced. The strength of the EF showed a significant influence on the reduction of the number of intra-protein hydrogen bonds especially when EF is equal to 0.5 V/nm which could facilitate destabilization of the structure of the peptides. Current findings provide quantitative insights into the tautomerization-mediated Aβ40 dynamic and conformational changes induced by the external EFs in aqueous solutions, which may provide beneficial information for use as a therapeutic technique. • We explored the combined effect of an external EF and histidine tautomerism on the misfolding of monomeric Aβ40. • When EF = 0.5 V/nm was applied the β-sheet structure of the δδδ isomer was destroyed. • This work can be helpful for studying EF dependency structural changes in the presence of the tautomeric states. [ABSTRACT FROM AUTHOR]

Targeting the signaling pathway of the Vascular endothelial growth factor receptor-2 is a promising approach that has drawn attention in the quest to develop novel anti-cancer drugs and cardiovascular disease treatments. We construct a screening pipeline using machine learning classification integrated with similarity checks of approved drugs to find new inhibitors. The statistical metrics reveal that the random forest approach has slightly better performance. By further similarity screening against several approved drugs, two candidates are selected. Analysis of absorption, distribution, metabolism, excretion, and toxicity, along with molecular docking and dynamics are performed for the two candidates with regorafenib as a reference. The binding energies of molecule1, molecule2, and regorafenib are − 89.1, − 95.3, and − 87.4 (kJ/mol), respectively which suggest candidate compounds have strong binding to the target. Meanwhile, the median lethal dose and maximum tolerated dose for regorafenib, molecule1, and molecule2 are predicted to be 800, 1600, and 393 mg/kg, and 0.257, 0.527, and 0.428 log mg/kg/day, respectively. Also, the inhibitory activity of these compounds is predicted to be 7.23 and 7.31, which is comparable with the activity of pazopanib and sorafenib drugs. In light of these findings, the two compounds could be further investigated as potential candidates for anti-angiogenesis therapy. [ABSTRACT FROM AUTHOR]

The oxidation degradation by unsaturated metal atoms or dangling bonds at MXene edges and defects severely hinders the practical application of MXene. Herein, a passivation scheme for Ti3C2Tx MXene is demonstrated by utilizing a sulfhydryl‐containing molecule, β‐mercaptoethanol (BME), which can significantly suppress the Ti3C2Tx oxidation in various environments, including long‐term storage of Ti3C2Tx aqueous dispersions (2 m), single‐layer Ti3C2Tx‐based devices in humid air (2 m), and high‐temperature environment (12 h). Notably, the nonionic BME does not cause aggregation but maintains the 2D morphology of Ti3C2Tx. A comprehensive investigation of the protection mechanism through density functional theory (DFT) calculations and experimental characterizations reveals that BME is adsorbed especially at the edges and surface defects of MXene (binding energy −1.70 and −1.05 eV), where the degradation starts. Further, the electron‐donating effect of sulfhydryl groups tunes the work function of Ti3C2Tx from 4.70 to 4.39 eV, resulting in improved carrier‐transport performances in MoS2 field‐effect transistors owing to band alignment, where BME–Ti3C2Tx serves as the source electrode. The described methodology can largely contribute to the ultralong service life of 2D Ti3C2Tx without affecting its excellent properties, thereby promoting the practical application of this emerging material. [ABSTRACT FROM AUTHOR]

Analogous to conventional carbon nanotubes, single-walled, chiral, γ-graphyne nanotubes (C-γGyNTs) are modeled based on the synthesized 2D γ-graphyne motif, and their electronic properties are investigated via density-functional tight-binding calculations for the first time. The resulting γGyNTs are predicted to be excellent semiconductors with moderate bandgaps ranging from 1.291 eV to 1.928 eV. In addition, the bandgaps of zigzag γGyNTs and armchair γGyNTs show damped oscillatory behaviour, while those of C-γGyNTs do not show any chirality- or diameter-dependent oscillatory behaviour. Interestingly, it is revealed that the (2a, m)-γGyNTs, where a is a positive integer, have nearly identical bandgap values, which provides a fresh method of bandgap manipulation for semiconductor devices that has not yet been reported. [ABSTRACT FROM AUTHOR]

Hexagonal turbostratic birnessite, one of the most reactive Mn oxide minerals, is ubiquitous throughout the ocean floor to the surface environment. During its crystallization, birnessite may coexist with Al 3+ , which is the third most abundant crustal element. However, interactions of Al 3+ with birnessite compared to the transition metal (TM) ions have rarely been explored thus far. This study examines the structure and properties of Al 3+ -doped hexagonal turbostratic birnessite to obtain insights into the interaction of metal cations with birnessite-like minerals in natural environments. For Al 3+ -incorporated birnessite, the crystal chemistry of Al 3+ , as well as alteration in the mineral structure, physicochemical properties, and reactivity toward the sorption of Pb 2+ /Zn 2+ is investigated by powder X-ray diffraction, chemical analysis, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy. Electronic structure calculations based on density functional theory (DFT) are further combined to aid in the experimental interpretation of Al 3+ incorporation. As a comparative system, Fe 3+ -coprecipitated birnessite is also examined. Under the experimental conditions used, only a small amount of Al 3+ is incorporated into birnessite, with a final Al/(Al + Mn) molar ratio of ∼0.07, whereas Fe 3+ is incorporated into birnessite with a final Fe/(Fe + Mn) molar ratio of up to ∼0.21. Irrespective of metal type, the incorporation of a metal cation significantly alters the physicochemical properties of birnessite, such as decrease in the thickness of crystals along the c ∗ axis and coherent scattering domain sizes in the a – b plane and the Mn average oxidation state, increase in the specific surface area and the total amount of hydroxyl groups, in which the contents of hydroxyl groups around vacancies are decreased. The lattice parameters in the a – b plane tend to decrease in Al–incorporated birnessites but first significantly decrease and then increase in Fe-incorporated birnessites. In Fe-incorporated birnessites, ∼32–50% of the total Fe 3+ is located inside the Mn octahedral sheets (INC species). In Al–incorporated birnessites, the edge- and corner-sharing Mn–Mn distances gradually decrease. Density function theory (DFT) computation results support that the dominant species in Al–birnessite is a triple-corner-sharing complex on vacancies. The DFT geometry optimization further demonstrates that the in-plane cell size experimentally observed for these birnessites depends on not only the metal type but also its position in the mineral. The Al- or Fe-birnessites exhibit significantly increased adsorption capacities for Pb 2+ but reduced capacities for Zn 2+ . The metal incorporation effects on the chemical reactivity are discussed with the observed changes in the particle size and available vacancy sites. [ABSTRACT FROM AUTHOR]

Density functional theory calculations were carried out to investigate how single-atom vacancies affect the electronic and magnetic properties of three types of graphyne model systems. Our simulations demonstrate that a single-atom vacancy can lead to an in-plane structural rearrangement, which plays an important role in tuning the electronic structures. A dispersionless spin-polarized band was observed around the fermi level, inducing strong magnetism in the three graphyne models. The single-atom vacancy can induce a 1.1–1.3 μ B magnetic moment into αGy and βGy, while this value increases significantly to about 1.8μ B for γGy. This single-atom vacancy technique is a promising method of manipulating the electronic and magnetic properties of graphyne. [ABSTRACT FROM AUTHOR]

The properties of vulcanizates based on graphitic nanofiller (GR) with flakes of medium surface area (150–450 m 2 /g) were studied for industrial applications. Room-temperature-vulcanized (RTV) silicone rubber was used as the matrix for preparing specimens. AFM micrographs reveal molecular level dispersion of GR with distributed particles in the range of 7–12 nm. The compressive load at 5 phr increased by ∼85% in the presence of a magnetic field. As the surface area of GR increases, the compressive modulus at 10 phr decreases by ∼35% and the actuation displacement at 15 phr increases by ∼340%. The transitional behavior in the mechanical properties was almost linear up to 300 m 2 /g and then fell sharply. The features of the vulcanizates are influenced by the nanoscale effect of the fillers, rapid stress-transfer from the polymer to the filler particles and consistent inter-particle connectivity in the rubber matrix. [ABSTRACT FROM AUTHOR]

Investigates the nature of the cation-pi interaction as a binding force in the binding of acetylcholine to acetylcholinesterase. Ab initio calculations for the complexes of tetramethylammonium cation with various substances; Comparison of Hartree-Frock and Moller-Plesset second-order perturbation treatments; Role of electron correlation effect.

[Display omitted] • Optimal flow process can maximize the denitrification capacity of riparian zones downstream of reservoirs. • Denitrification is reaction- instead of transport-limited when the hydrograph wave amplitude/duration ratio is high. • Riparian nitrogen removal has a strongly positive correlation to return/infiltration time ratio of solutes. Flood waves generated by reservoir discharge play a crucial role in the potential for riparian denitrification downstream. The efficiency of nitrogen (N) removal from river water by riparian zones is typically enhanced with greater wave amplitude (A) and duration (T). However, a knowledge gap exists with respect to the impact of flood waves on N removal when considering a fixed-value integral over time of flood waves (IOFW). This study explored N transport and transformation in the riparian zone downstream of the dammed Inbuk River, Korea under various wave conditions with a fixed IOFW. The results revealed a logarithmic enhancement in solute infiltration into the riverbank with an increasing wave amplitude/duration ratio (A / T ratio). The solute residence time within the riparian zone displays an initial increase followed by a decrease with the increment in the A/T ratio. We identified a threshold for the wave A/T ratio that maximizes riverine N removal by the riparian zone, a phenomenon observed across various dammed rivers. Our findings indicated that riparian denitrification is reaction time-limited when the wave A/T ratio exceeds the threshold; contrarily, it becomes transport capacity-limited. Additionally, we observed a significant relationship between the net nitrate removal and the return/infiltration time ratio of water (r2 = 0.93, p < 0.05). The research results contribute to a better understanding of the impact of water level fluctuations on the N cycle in riparian zones, and provide valuable insights for developing sustainable reservoir operation strategies. [ABSTRACT FROM AUTHOR]

The bias-polarity dependent multimode threshold and bipolar resistive switching characteristics in bi-layered Pt-Fe2O3 core-shell and γ-Fe2O3 nanoparticles assembly were investigated. The Ti/Pt-Fe2O3-core-shell-nanoparticles (∼20 nm)/γ-Fe2O3-nanoparticles (∼40 nm)/Pt structure exhibited a threshold switching upon applying -V at Ti electrode. However, the filaments were formed at +V and subsequently ruptured at -V, featured to be bipolar switching. After rupturing filaments, it returned to threshold switching mode. The presence of core-shell nanoparticles facilitates the threshold switching either by temporary formation of filaments or enhanced charge transport. Also, the oxygen reservoir role of Ti electrode was essential to form stable filaments for bipolar switching. [ABSTRACT FROM AUTHOR]

Sodium-ion batteries (SIBs) are promising candidates for the replacement of lithium-ion batteries (LIBs) because of sodium's abundant reserves and the lower cost of sodium compared to lithium. This is a topic of interest for developing novel anodes with high storage capacity. Owing to their low cost, high stability, and conductivity, carbon-based materials have been studied extensively. However, sp2-C based carbon materials have low-rate capacities. Intensive density functional theory calculations have been implemented to explore the applicability of α, β, and γ graphyne nanotubes (αGyNTs, βGyNTs, and γGyNTs, respectively) as SIB anodes. Results suggest that (3, 0)-αGyNT, (2, 2)-βGyNT, and (4, 0)-γGyNT have, respectively, maximum Na storage capacities of 1535, 1302, and 1001 mAh/g, which exceeds the largest reported value of carbon materials (N-doped graphene foams with 852.6 mAh/g capacity). It was determined that αGyNTs have the largest storage capacity of the three types because they possess the largest specific surface area. Moreover, the larger pores of αGyNTs and βGyNTs allow easier diffusion and penetration of Na atoms compared to those of γGyNTs, which could result in better rate capacity. [ABSTRACT FROM AUTHOR]

In this review, rational design strategies for pure organic high-spin molecules with strong intramolecular magnetic interactions are presented, mostly focusing on the design of ferromagnetically coupled organic diradicals. After brief introduction of the calculation procedure for intramolecular magnetic coupling constant J using density functional theory (DFT), classification and standardization of magnetic character of well-known stable radicals and coupler units are discussed. Following the development of general strategy for the design of organic high-spin diradical by means of the classification and standardization scheme, applicability of the strategy for making pendent-type organic polyradical using zigzag graphene nanoribbons backbone is demonstrated. In a computational point of view, a scaling procedure and an optimization of Hartree-Fock exact exchange ratio of a hybrid DFT functional for better prediction of the J of diradicals are discussed. © 2015 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Objective. This study evaluated the potential of interleukin 12 receptor beta 2 and tumor necrosis factor receptor superfamily member 8 as diagnostic biomarkers of oral lichen planus (OLP). Materials and methods. The mRNA expression of IL12RB2 and TNFRSF8 in FFPE OLP samples (OLP group, n = 38) were investigated with quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) analysis and compared to those of chronic non-specific mucositis (Non-OLP group, n = 25) and normal mucosa (Normal group, n = 18). Predictive modeling of the expression of IL12RB2 and TNFRSF8 was constructed using support vector machine (SVM), random forest (RF), linear discriminant analysis (LDA), neural network (NN) and naive Bayes (NB) methods. Results. Normalized expression of IL12RB2 in the OLP group (3.78 ± 1.67) was significantly higher than the Normal group (1.97 ± 1.12), but lower than the Non-OLP group (6.86 ± 1.67). TNFRSF8 gene expression in the OLP group (7.46 ± 1.51) was significantly higher than the Normal group (2.90 ± 1.61), but no significant difference was found between the OLP and Non-OLP groups. The ratio of IL12RB2/TNFRSF8 in the OLP group (0.52 ± 0.23) was significantly lower than the Normal group (0.74 ± 0.39) and the Non-OLP group (1.07 ± 0.38). In the predictive modeling, the area under receiver operating characteristic (ROC) curves (AUC) ranged from 0.83-0.92 and their accuracy was higher than 0.75 in all methods. Conclusions. The IL12RB2/TNFRSF8 ratio can be a useful diagnostic tool for OLP. [ABSTRACT FROM AUTHOR]

This study was performed to examine the chemical and isotopic compositions of groundwater used in open loop GHP systems and natural groundwater around the open loop GHP systems and to evaluate the influence of open loop GHP systems' operation on groundwater chemistry in Korea. The water temperature of groundwater used in open loop GHP systems ranged from 6.0 to 37.1°C and decreased by 6.7 to 11.6°C compared with that of natural groundwater around the open loop GHP systems. The pH, EC, Eh, Fe, and Mn of the groundwater were not significantly affected by open loop GHP systems' operation. The groundwaters used in open loop GHP systems showed various water types, such as Ca-HCO, Ca-Cl, Ca-SO, and Na-HCO· Although HCO and Cl concentrations were slightly influenced by open loop GHP systems at some sites, the groundwater chemistry used in the open loop GHP systems did not significantly change at most sites. In addition, carbonate and silica minerals and minerals containing Mn were in undersaturated condition, which indicates that the precipitation of these minerals will not occur. However, some minerals containing Fe, such as Fe(OH), goethite, and hematite can be precipitated as scale within these system. In the open loop GHP systems selected in this study, the influence of open loop GHP systems on groundwater chemistry is not revealed sufficiently because of short-term monitoring of groundwater chemistry. However, integrated long-term monitoring is necessary to evaluate influence of open loop GHP systems on groundwater chemistry and to improve our understanding of the environmental impacts related to these systems. [ABSTRACT FROM AUTHOR]

Alcohols mediated 7-hydroxyquinoline (7-HQ) complex has received enormous attractions on the issue of proton transfer reaction in the ground and excited states. In the present paper, concentrating on the ground state proton transfer (GSPT), density functional theory (DFT) calculations were carried out to investigate the intrinsic insight into the reaction mechanism. We found that the GSPT is concerted and asynchronous process and can be accelerated by more acidic alcohol. Such GSPT was initiated by the proton transfer from alcohol to keto group of 7-HQ and finished by the proton transfer from nitrogen to alcohol. Our findings were in agreement with experimental conclusions quite well. Our results would be helpful to understand the proton transfer reaction for 7-HQ and related systems. [ABSTRACT FROM AUTHOR]

Objectives To estimate the loss in quality-adjusted life-years (QALYs) in Korean adults due to 13 noncommunicable diseases (NCDs) in 2010 and predict changes in QALY loss through to the year 2040. Methods Thirteen NCDs (hypertension, diabetes mellitus, hyperlipidemia, stroke, myocardial infarction, angina, arthritis, osteoporosis, asthma, allergic rhinitis, atopic dermatitis, cataract, and depression) were selected from the Korean Community Health Survey 2010. The EuroQol five-dimensional questionnaire index from the Korean Community Health Survey 2010 and the Korean valuation set were used to estimate utility weights according to sex, age, and disease. Morbidity data were also obtained from the Korean Community Health Survey 2010. Mortality data according to disease and life expectancy were retrieved from the Korean Statistical Information Service. To predict future QALY loss, future population projection data from the Korean Statistical Information Service were used as substitutes for 2010 population size. Results Among the assessed 13 NCDs, the largest total QALY loss was for hypertension (513,113 QALYs; units are omitted hereafter), followed by arthritis (509,317) and stroke (431,049). The largest QALY loss due to mortality was stroke (306,733), whereas the largest QALY loss due to morbidity was arthritis (502,513). By applying the middle estimate of future population, the largest increase in total QALY loss between 2010 and 2040 was for hypertension (840,582), followed by stroke (719,076) and diabetes mellitus (474,607). Conclusions Hypertension, arthritis, and stroke are important in terms of total QALY loss, which will continuous to increase because of aging. These results could be used to develop cost-effective interventions that reduce the burden of NCDs. [ABSTRACT FROM AUTHOR]

In the present study, density function theory ( DFT) calculations were carried out regarding the electric field effect on the trans-p-hydroxybenzylideneimidazolidinone ( HBDI), which represents the green fluorescent protein ( GFP) chromophore. Structures in the absence or presence of electric fields were fully optimized with the CAM-B3LYP functional, and the corresponding absorption properties were obtained by the time-dependent DFT method. It was found that electric field parallel to the x-axis ( Fx) has the strongest effect on the charge distribution, and, hence the structure and dipole moment, of the ground state. Furthermore, the absorption energy of the neutral and anionic HBDI monomer was significantly affected by Fx. [ABSTRACT FROM AUTHOR]

• Graphyne nanotubes with sp-B doping showed excellent catalytic activity for nitrogen reduction reaction. • Δ G *NNH has a good volcano relationship with the limiting potential. • Curvature effect induces the synergistic effect of p-orbital and positive charge enhancement on sp-B dopants to enhance N 2 fixation. Developing novel, metal-free materials as efficient catalysts for the electrochemical nitrogen reduction reaction (NRR) to replace the Haber-Bosch process remains a significant challenge. Herein, γ-graphyne nanotubes (γGyNTs) doped with single sp2-B or sp-B were developed as electrocatalysts. The NRR activity of the doped γGyNTs was studied by intensive density functional theory (DFT) calculations. The results reveal that the curvature effect significantly enhances the catalytic activity of sp-B-doped γGyNTs, in contrast with that achieved via sp2-B doping. The limiting potential of sp-B-doped (2, 0)-γGyNT is predicted to be −0.071 V, which is significantly superior to that of previously reported metal-free catalysts (MFCs). Moreover, the competing hydrogen evolution reaction (HER) is suppressed by sp-B-doped (2, 0)-γGyNT. Analysis of the catalytic mechanism revealed that the enhanced NRR activity of the sp-B doped γGyNTs mainly originates from the synergistic effects of the enhanced exposure of the p-orbital and positive charge on the sp-B dopants induced by the curvature effect, which can alter the interactions with intermediates. The present findings are insightful and suggest a new strategy for designing graphyne-related materials as high-performance non-metallic NRR catalysts. [Display omitted] [ABSTRACT FROM AUTHOR]

Hundreds of millions of people around the world have been affected by Type 2 diabetes (T2D) which is a metabolic disorder. Clinical research has revealed T2D as a possible risk factor for Alzheimer's disease (AD) development (and vice versa). Amyloid-β (Aβ) and human islet amyloid polypeptide are the main pathological species in AD and T2D, respectively. However, the mechanisms by which these two amyloidogenic peptides co-aggregate are largely uninvestigated. Herein, for the first time, we present the cross-seeding between Amylin1-37 and Aβ40 considering the particular effect of the histidine tautomerism at atomic resolution applying the all-atom molecular dynamics (MD) simulations for heterodimeric complexes. The results via random seed MD simulations indicated that the Aβ40(δδδ) isomer in cross-talking with Islet(ε) and Islet(δ) isomers could retain or increase the β-sheet content in its structure that may make it more prone to further aggregation and exhibit higher toxicity. The other tautomeric isomers which initially did not have a β-sheet structure in their monomeric forms did not show any generated β-sheet, except for one seed of the Islet(ε) and Aβ40(εεε) heterodimers complex that displayed a small amount of formed β-sheet. This computational research may provide a different point of view to examine all possible parameters that may contribute to the development of AD and T2D and provide a better understanding of the pathological link between these two severe diseases. [ABSTRACT FROM AUTHOR]

Single‐atom catalysts (SACs) exhibit intriguing performance in electrocatalysis owing to their maximized atom utilizations and unique electronic structures, but effective anchoring metal atoms with defined coordination structure on hierarchical integrated electrode remain a challenge. Herein, a fast and facial flame‐assisted strategy is developed to construct oxygen‐coordinated SACs on integrated carbon nanotube (CNT) arrays with promising applications in electrocatalysis. Density functional theory calculations show that oxygen in carbon substrate imparts homogeneous sites for the efficient anchoring of metal atoms, thereby enabling SACs to disperse uniformly and firmly and thus bringing optimized activities. Moreover, the integrated CNT array with abundant oxygen‐containing groups is constructed and has been used as an efficient matrix for anchoring metal atoms (CNT‐O@M) via a flame‐assisted method. The as‐prepared CNT‐O@M (M = Co and Pt as typical examples) shows excellent activities in electrocatalytic oxygen reduction reaction and hydrogen evolution reaction with utilization of active site as high as 75.7%, which is superior to the reported SACs. Particularly, the performance of CNT‐O@M can maintain stably under various harsh conditions, showing a promising prospect in the long‐time applications. The methodology and concept proposed in this work could be extended to the synthesis of a variety of integrated SACs for efficient electrocatalysis. [ABSTRACT FROM AUTHOR]

The intrinsic origin of amyloid aggregation has been pursued as a new pathogenesis for Alzheimer's disease (AD). The aggregation mechanisms influenced by histidine tautomerism were previously investigated in Aβ40 and Aβ42 monomers. In the present study, we focus on the structural properties of Aβ40 heterodimer under the influence of histidine. The results of molecular dynamics simulation detected different aggregation trends were detected in different heterodimers formed by the εεε isomer and other isomers. In the (εεε:δδδ) dimer, the highest β‐sheet content was obtained in the δδδ chain, which is in agreement with our previous studies that δδδ monomer is the most easily formed β‐sheet secondary structure in the monomer. Further analysis confirmed that (εεε:δδδ) dimers more easily aggregate into fibrils in comparison with other heterodimers. This research will help in understanding the tautomeric effect on Aβ heterodimers, thereby helping to figure out the pathogenesis of AD. [ABSTRACT FROM AUTHOR]

The intramolecular magnetic couplingconstant (J) values of sets of diradicals linkedto bis-DTDA, OVER, and NN radicals(DTDA, OVER, and NN groups) through an aromatic coupler were studiedby unrestricted density functional theory calculations (UB3LYP/6-311++G(d,p)).Among 15 aromatic couplers, 9 compounds with an odd number of carbonatoms along its spin coupling path were found to interact ferromagneticallyupon coupling with bisradicals while the other 6 couplers with aneven number of carbon atoms along its spin coupling path give riseto antiferromagnetic coupling. The overall trends in the strengthof magnetic interactions of aromatic couplers were preserved for DTDA,OVER, and NN groups so that the trend can be utilized as an indexfor the magnetic strength of a given coupler. It was found that thedifferences in the nucleus-independent chemical shift (NICS), bondorder of connecting bonds, and Mulliken atomic spin density at connectedatoms between triplet and BS states are closely related to the intramolecularmagnetic behavior. 2,4- and 2,5-phosphole couplers exhibit the strongestintramolecular ferromagnetic and antiferromagnetic interactions among15 aromatic couplers when linked to diverse bisradicals. [ABSTRACT FROM AUTHOR]

We demonstrate that the imidazole-based ligand 1 efficiently produces a coordination polymer gel by simple mixing with Co2+ ion. When the molar ratio of CoCl2 to ligand 1 was less < 1, a red sol was obtained, indicating the formation of an octahedral ( Oh) complex species as occurs with Co(NO3)2. In contrast to G1, when the amount of CoCl2 employed was more than 1 equiv., the color of the gel changed from red to blue ( G2), indicating the formation of mainly a tetrahedral ( Td) complex species. The ionochromic and the piezochromic effects of imidazole-based suprmolecular gel with Co2+ were investigated. These effects of supramolecular gel were controlled by various anions of cobalt, which are due to coordination geometric change of gels. Interestingly, the ionochromic and piezochromic effects of G1 act as AND and OR logic gates in the solid and the gel state. [ABSTRACT FROM AUTHOR]

Objectives This study evaluated implant stability and clinical outcomes obtained with magnesium-incorporated oxidised implants ( Mg titanate) and compared them to those blasted magnesium-incorporated oxidised implants (blasted Mg titanate). Patients and methods Mg titanate was manufactured using the microarc oxidation ( MAO) process. To obtain blasted Mg titanate, the MAO process was performed after blasting with Ti O2 particles. The 15-month, randomised, double -blind clinical trial was conducted on 54 implants in 40 patients ( Mg titanate, 27 implants in 18 subjects; blasted Mg titanate, 27 implants in 22 subjects), in whom 4.0 mm × 10 mm implants were placed to restore the unilateral loss of one or two molars in the mandible. The final prosthesis was attached 3 months postoperatively. Implant stability was measured by the implant stability quotient ( ISQ) and periotest value ( PTV) at the time of implant insertion, and 2, 3, and 15 months postoperatively. Marginal bone loss was evaluated at 2, 6, and 15 months postoperatively. Soft tissue analysis was performed at 15 months postoperatively. Results Both implant systems showed high stability at all time points (>71). Mean marginal bone loss was 0.71 ± 0.65 mm and 0.75 ± 0.73 after 15 months in Mg titanate and blasted Mg titanate, respectively. There were no significant differences between the two implant surfaces with respect to ISQ( P = 0.988), PTV( P = 0.935), and marginal bone loss( P = 0.807) after 15 months. Conclusion The success rate after 1 year of follow-up was 100% for both magnesium-incorporated oxidised implants. There were no significant differences in the clinical outcomes between the two surfaces at 15 months follow-up. [ABSTRACT FROM AUTHOR]

Highlights: [•] Numerical method to delineate hyporheic zone depth using CAD analysis was proposed. [•] To evaluate adequacy of the proposed method, sensitivity analysis was performed. [•] The hyporheic zone depth was little influenced by hyporheic water flux shapes. [•] Estimated hyporheic zone depth of the method is comparable with that of tracer test. [•] The proposed method has an advantage even when hyporheic flux shape is ambiguous. [Copyright &y& Elsevier]

There is an ongoing need for explosive detection strategies to uncover threats to human security including illegal transport and terrorist activities. The widespread military use of the explosive trinitrotoluene (TNT) for landmines poses another particular threat to human health in the form of contamination of the surrounding environment and groundwater. The detection of explosives, particularly at low picogram levels, by using a molecular sensor is seen as an important challenge. Herein, we report on the use of a fluorescent metal-organic framework hydrogel that exhibits a higher detection capability for TNT in the gel state compared with that in the solution state. A portable sensor prepared from filter paper coated by the hydrogel was able to detect TNT at the picogram level with a detection limit of 1.82 ppt (parts per trillon). Our results present a simple and new means to provide selective detection of TNT on a surface or in aqueous solution, as afforded by the unique molecular packing through the metal-organic framework structure in the gel formation and the associated photophysical properties. Furthermore, the rheological properties of the MOF-based gel were similar to those of a typical hydrogel. [ABSTRACT FROM AUTHOR]

We previously reported that methylmercury induces brain-specific upregulation of a chemokine gene, the CCL4 gene. In this study, we investigated the changes in gene expression levels of all chemokines in various tissues (cerebellum, cerebrum, kidney, liver, and spleen) of methylmercury-treated mice. We found that methylmercury induced upregulation of the CCL4 gene and the CCL3 gene, in a brain-specific manner. This finding suggests that upregulation of these two chemokine genes mediates selective damage by methylmercury in the central nervous system. [ABSTRACT FROM AUTHOR]

Detailsof the reaction mechanism for the Ru–PNN pincer complex catalyzedamidation from an alcohol and an amine proposed by Milstein et al.was elucidated using M06 density functional theory calculations. Inaddition, the bifunctional double hydrogen transfer (BDHT) mechanismfor the dehydrogenative oxidation step was investigated for comparison.Finally, the BDHT mechanism was found to be preferred over the β-Helimination pathway that was proposed by Milstein et al. On the basisof the analysis of NBO charges and orbital interactions of intermediatesand transition states, we designed a new catalyst with the additionof an electron-donating substituent (−NEt2), whichprovided much reduced energy barriers and a lower potential energysurface along both mechanisms. [ABSTRACT FROM AUTHOR]

Electroluminescence efficiency and operating stability of solution‐processed perovskite light‐emitting diodes (PeLEDs) are limited by luminescence quenching induced by indium or tin released from indium tin oxide (ITO) electrode upon deposition of highly acidic conventional hole injection layer (HIL) (i.e., poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS)) and inefficient hole injection into perovskite emitting layer. Here, a synergistic molecular strategy to develop a neutralized gradient HIL, which possesses low acidity and high work function (WF) simultaneously, is proposed. First, it is shown that aniline with relatively low basicity and dipole moment efficiently neutralizes HIL while maintaining its original confirmation and high WF. Both acidity‐neutralizing aniline and WF‐modifying agent (perfluorinated ionomer) are incorporated into PEDOT:PSS to achieve high pH ≈ 6 and WF > 5.8 eV, which suppresses etching of underlying ITO and luminescence quenching while maintaining efficient hole injection into perovskite emitting layer. With this synergetic molecular engineering, high current efficiency = 52.55 cd A−1 with extended operating lifetime is achieved in PeLEDs that use colloidal formamidinium lead bromide nanoparticle films. This result provides a simple and efficient way to develop efficient and stable PeLEDs in industrial displays and solid‐state lighting. [ABSTRACT FROM AUTHOR]

Density functional theory calculations have been performed to study the adsorption behavior of ionic liquids (ILs) on 15th group nanosheets including phosphorene (BP), arsenene (As), and antimonene (Sb). Three ILs based on 1‐ethyl‐3‐methylimidazolium ([EMIM]+), tetramethylammonium ([TMA]+), and N‐methylpyridinium ([MPI]+) cations paired with tetrafluoroborate ([BF4]−) anion were selected as adsorbates on different 2D nanosheets to explore the interfacial behavior. The calculated structural, energy, charge transfer, and electronic properties of the adsorption systems for ILs/nanosheets exhibit combination by non‐covalent interaction. Adsorption of ILs induces a very small reduction of band gap for BP, As, and Sb nanosheets, and the electronic properties of nanosheets are nearly unchanged. These results increase understanding of the experimental mechanism for IL dispersion 2D materials and suggest that ILs can be used to functionalize elemental 15th group nanosheets for further applications in various fields. [ABSTRACT FROM AUTHOR]

The epidemiological characteristics of women living with human immunodeficiency virus (HIV) infection have gained little attention as the numbers are small compared with men living with HIV in the Republic of Korea. However, these data are important to achieve effective HIV infection control and to consider the influence of socioeconomic status on HIV transmission. This study utilized the claims database of the Korean National Health Insurance system to analyze women with a newly diagnosed HIV infection during the period 2009–2016. Adherence to antiretroviral agents was calculated using the medication possession ratio. Among 677 women with a newly diagnosed HIV infection, 219 (32.4%) were over 50 years of age; 291 (43.0%) were identified as having acquired immune deficiency syndrome (AIDS). A total of 99 women (14.6%) were National Medical Aid beneficiaries. Optimal medical adherence >95% was found in 62.2% of subjects. Teenage years (odds ratio(OR) 14.9, 95% confidence interval (95CI) 4.9-44.8), AIDS (OR 1.7, 95CI 1.2-2.3), and low economic status requiring National Medical Aid (OR 3.0, 95CI 2.0-4.6) were associated to adherence. Diagnosis prior to 2012 was also associated with poor adherence. In women, particularly young patients with low economic status, extra attention is required to enhance adherence to prescribed medication. [ABSTRACT FROM AUTHOR]

We report unique observations from drilling and hydraulic stimulation at a depth of approximately 4.3 km in two Enhanced Geothermal System (EGS) wells at the Pohang EGS site, South Korea. We surveyed drilling logs and hydraulic stimulation data, simulated pore pressure diffusion around the fault delineated by seismic and drilling log analyses, conducted acoustic image logging through the EGS wells, observed significant water level drops (740 m) in one of the two EGS wells, and obtained hydrochemical and isotopic variation data in conjunction with the microbial community characteristics of the two EGS wells. We discuss the hydraulic and hydrochemical responses of formation pore water to a few key seismic events near the hypocenter. We focused on how the geochemistry of water that flowed back from the geothermal wells changed in association with key seismic events. These were (1) a swarm of small earthquakes that occurred when a significant circulation mud loss occurred during well drilling, (2) the MW 3.2 earthquake during hydraulic stimulation, and (3) the MW 5.5 main shock two months after the end of hydraulic stimulation. This study highlights the value of real-time monitoring and water chemistry analysis, in addition to seismic monitoring during EGS operation. [ABSTRACT FROM AUTHOR]

Observation of novel linear relationship between Δ G OOH and Δ E H suggests Δ E H as a simple descriptor for rational design of HER/ORR bifunctional graphyne materials. [Display omitted] The high cost and relative scarcity of platinum (Pt) restrict large-scale commercialization of fuel cells, which has spurred researchers to develop low-cost alternatives integrating with high hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR) catalytic activity. Herein, we performed density functional theory (DFT) calculations to explore the electrocatalytic activity of graphyne nanotubes (GyNTs). Several GyNTs were found to be potential metal-free electrocatalysts, with both HER and ORR activity superior to Pt. Moreover, we revealed a linear relationship between the Gibbs free energy change of O 2 adsorption (Δ G OOH) and binding energy of H adsorption (Δ E H), which could be attributed to the fact that both the C O bond of OOH adsorption and the C H bond of H adsorption are single bonds. Therefore, Δ E H is proposed as a general descriptor for the rational design of bifunctional graphyne materials toward HERs and ORRs. Our findings provide a simple strategy for the rational design of bifunctional materials. [ABSTRACT FROM AUTHOR]

Sufficiently strong molecular magnets are used in small modern electronic and spintronic devices. Diradical organic magnetic molecules (OMMs) are promising options due to their lightness, flexibility, and the low energy required for their synthesis. In this field, the coupler is a dominating component, though acetylene, the shortest coupler, has not been studied for this use. In this study, we conceptualize several model systems using an acetylene link to couple different monoradicals. We simulated their magnetic strength using the broken symmetry method via density functional theory calculations. Our results show that the acetylene (–C≡C–) coupler gives much larger J values than the ethylene (–C＝C–) coupler. Acetylene coupling a phenoxyl (PO) and a nitronyl nitroxide (NN) diradical is the strongest ferromagnetic diradical OMM, and acetylene coupling a PO bisradical is the strongest anti-ferromagnetic diradical OMM. Moreover, we found that the magnetic strength is dependent on the coupler length and torsion, but is independent of the bending. Since only a very small energy barrier is needed, it is feasible to use torsion to tune a diradical OMM's magnetic strength. Our results are also beneficial for the rational design and synthesis of diradical OMMs. [ABSTRACT FROM AUTHOR]

Organic semiconductors to date having cofacial stacking motif are scarce compared to those having herringbone motif. Recently, Ahmed and co-workers have reported a series of novel n-type bisindenoanthrazolines (BIDAs) [Chem. Mater. 2010, 22, 5786], among which DADF and DADK adopt different slipped cofacial arrangements exhibiting distinct electron transport abilities. Here, we performed computational studies to understand the relationship between charge transport and molecular packing for these BIDAs molecules. This work focuses on the intrinsic molecular factors required for efficient and long-range charge transfer. Unlike the previous studies only focusing the charge injection barriers or the carrier mobilities, herein, we present the notion that lower electron injection barrier and higher intrinsic electron mobility should be both satisfied to achieve better n-type OFETs. We also note that the actual mobility can be significantly underestimated due to the limitation of the space-charge limited current method. Through computational modeling, we rationalized the superior electron conductivity of DADK and also shed light on the favorable or undesirable properties for efficient charge transport of BIDAs. Another key finding is that the intrinsic electron and hole mobilities are quite deviated from each other rather than comparable in current mobility calculations. [ABSTRACT FROM AUTHOR]

Density functional theory (DFT) calculations were performed using a MPWB1K functional to interpret the charge transport (CT) properties of stacked annelated β-trithiophene molecules. The goal was to help understand how the chemical composition, face-to-face stacking, intra- and intermolecular correlations, and the applied electric field affect the CT properties of this organic semiconductor compared with those of the edge-to-face "herringbone" motif. The variations in the frontier molecular orbitals, energy gap, nonadiabatic electron attachment energies (EAE), and vertical detachment energies (VDE) were investigated under an external electric field as a function of the number of stacked layers (n). Two possible CT pathways, monomer-to-monomer (MM) and dimer-to-dimer (DD) transports, were postulated to determine the charge carrier conductivities of these molecules. The results highlight that the intermolecular electronic couplings and electrostatic interactions can significantly affect the stacking geometry, even in more extended structures; displaced stacks with smaller interlayer spacing resulted in more compact stacking and, thus, higher CT efficiency; face-to-face stacking geometries can help to reduce the energy gap and VDE. Despite the fact that common thiophene-based oligomers adopting edge-to-face herringbone motifs exhibited p-type (hole-transporting) characters, the face-to-face stacked models based on annelated β-trithiophenes exhibited remarkably increased n-type (electron-transporting) performances. The electric field in the z-direction produced a small influence on the DD charge transport, whereas both electron and hole mobilities decreased dramatically in the MM case. More importantly, in MM charge transport, the electric field increases the hole mobility so that it is higher than that of the electron. [ABSTRACT FROM AUTHOR]

Widespread climate change can impact on groundwater conditions. We evaluated the groundwater data for 1996-2008 obtained from the National Groundwater Monitoring Stations (NGMS), in the context of the global warming effect. Indications of air temperature and sea level rises were evident in the period. The groundwater levels were generally decreasing and most of this decrease was attributed to increased pumping nationwide, but no indication for any effect of sea level rise on groundwater level in coastal aquifers was found. The electrical conductivity (EC) values of groundwaters were very high in metropolitan and industrial areas, which were indicative of anthropogenic groundwater contamination and progressive groundwater quality deterioration. A systematic EC rise in coastal groundwaters, as a possible result of the sea level rise, was not observed. The groundwater temperature variation was the most striking. The majority of the monitored shallow and deep groundwaters exhibited increasing trends at mean rates of 0.04-0.09 °C/yr. The widespread and prevailing increase in groundwater temperature nationwide, with increasing air temperature, is strongly indicative of the effect of global warming. The increasing trend became more distinctive every year. However, these significant conclusions require further groundwater monitoring and re-evaluation. [ABSTRACT FROM AUTHOR]

Summary: The Korean Ministry of Construction and Transportation (MOCT) and the Korean Ministry of Environment (MOE) manage the National Groundwater Monitoring Stations (NGMS) and the Groundwater Quality Monitoring Stations (GQMS) under Article 17 of the Groundwater Act. Under the same legislation, local government will install or designate an additional 10,000 monitoring wells as Subsidiary Groundwater Monitoring Stations (SGMS) by 2011. However, a standard for the installation and management of the SGMSs has not yet been developed. This study focuses on the development of a model for the determination of optimal monitoring frequencies during the manual measurement of the SGMSs. The groundwater level time series for the 81 deep and shallow monitoring wells making up the NGMSs were analyzed using an AR(p) model, and a harmonic series model was then made for the determination of groundwater level sampling frequency in the SGMSs. The result showed that the average sampling frequency necessary for groundwater level monitoring is about once every 8.9 days. Moreover, it indicates that water level sampling needs to be performed more frequently in steeply inclined sites, deep wells, and in monitoring wells belonging to an AR(2) rather than an AR(1) model. [Copyright &y& Elsevier]

Background: Healthcare quality assessment is being conducted in many countries. Although improving health equity is one of the major objectives of medical quality assessment, it is not clear whether different socio-economic statuses show the same health outcomes even in the same medical quality hospitals. No study has directly compared the health outcomes of different socio-economic statuses in the same hospitals nationwide.Objective: To determine whether the mortality rate of acute stroke patients differs according to socioeconomic status.Methods: This study was a retrospective, observational study of patients who were subject to acute stroke quality assessment in 2013. A total of 10 399 stroke cases were included in the study. When evaluating the mortality rate, the researchers analysed 10 228 cases, after excluding 171 cases that were measured twice for the same person. The levels of socio-economic status were divided according to the use of medical benefits, either National Health Insurance (NHI) for general population or Medical Aid (MA) for the vulnerable. The primary outcomes measured according to socio-economic status were in-hospital mortality rate and 1-year follow-up mortality rate of stroke patients. The secondary outcome was the composite performance score.Results: MA recipients had a higher in-hospital mortality rate (12.5 vs. 8.3%, P < 0.001) and 1-year follow-up mortality rate (14.9 vs. 10.8%, P < 0.001) than NHI subscribers. MA recipients had slightly lower scores than NHI subscribers (83.2 vs. 84.4, P = 0.02). In hospitals of the same grade, MA recipients had lower performance scores than NHI subscribers, although the difference was not statistically significant.Conclusions: There is a difference in mortality and healthcare performance according to socio-economic status in stroke patients in Korea. Efforts to improve equity are needed, including the development and monitoring of equality indicators and developing policies for healthcare equity. [ABSTRACT FROM AUTHOR]

The development of efficient electrocatalysts for the CO2 reduction reaction (CO2RR) remains a challenge. Demonstrated here is a NiSn atomic‐pair electrocatalyst (NiSn‐APC) on a hierarchical integrated electrode, which exhibits a synergistic effect in simultaneously promoting the activity and selectivity of the CO2RR to formate. The NiSn atomic pair consists of adjacent Ni and Sn, each coordinated with four nitrogen atoms (N4‐Ni‐Sn‐N4). The as‐prepared NiSn‐APC displays exceptional activity for the CO2RR to formate with a turnover frequency of 4752 h−1, a formate productivity of 36.7 mol h−1 gSn−1 and an utilization degree of active sites (57.9 %), which are superior to previously reported single‐atomic catalysts. Both experimental data and density‐functional theory calculations verify the electron redistribution of Sn imposed by adjacent Ni, which reduces the energy barrier of the *OCHO intermediate and makes this potential‐determining step thermodynamically spontaneous. This synergistic catalysis provides a successful paradigm for rational design and preparation of atomic‐pair electrocatalysts with enhanced performance. [ABSTRACT FROM AUTHOR]

The development of efficient electrocatalysts for the CO2 reduction reaction (CO2RR) remains a challenge. Demonstrated here is a NiSn atomic‐pair electrocatalyst (NiSn‐APC) on a hierarchical integrated electrode, which exhibits a synergistic effect in simultaneously promoting the activity and selectivity of the CO2RR to formate. The NiSn atomic pair consists of adjacent Ni and Sn, each coordinated with four nitrogen atoms (N4‐Ni‐Sn‐N4). The as‐prepared NiSn‐APC displays exceptional activity for the CO2RR to formate with a turnover frequency of 4752 h−1, a formate productivity of 36.7 mol h−1 gSn−1 and an utilization degree of active sites (57.9 %), which are superior to previously reported single‐atomic catalysts. Both experimental data and density‐functional theory calculations verify the electron redistribution of Sn imposed by adjacent Ni, which reduces the energy barrier of the *OCHO intermediate and makes this potential‐determining step thermodynamically spontaneous. This synergistic catalysis provides a successful paradigm for rational design and preparation of atomic‐pair electrocatalysts with enhanced performance. [ABSTRACT FROM AUTHOR]