Determination of the binding affinities of OPEs to integrin αvß3 and elucidation of the underlying mechanisms via a competitive binding assay, pharmacophore modeling, molecular docking and QSAR modeling.

Organophosphate esters (OPEs) can cause adverse biological effects through binding to integrin αvß3. However, few studies have focused on the binding activity and mechanism of OPEs to integrin αvß3. Herein, a comprehensive investigation of the mechanisms by which OPEs bind to integrin αvß3 and determination of the binding affinity were conducted by in vitro and in silico approaches: competitive binding assay as well as pharmacophore, molecular docking and QSAR modeling. The results showed that all 18 OPEs exhibited binding activities to integrin αvß3; moreover, hydrogen bonds were identified as crucial intermolecular interactions. In addition, essential factors, including the -P = O structure of OPEs, key amino acid residues and suitable cavity volume of integrin αvß3, were identified to contribute to the formation of hydrogen bonds. Moreover, aryl-OPEs exhibited a lower binding activity with integrin αvß3 than halogenated- and alkyl-OPEs. Ultimately, the QSAR model constructed in this study was effectively used to predict the binding affinity of OPEs to integrin αvß3, and the results suggest that some OPEs might pose potential risks in aquatic environments. The results of this study comprehensively elucidated the binding mechanism of OPEs to integrin αvß3, and supported the environmental risk management of these emerging pollutants.

CO2 electro-reduction reaction via a two-dimensional TM@TAP single-atom catalyst.

In this study, the possibility of using TM atom anchored monolayer TAP as a class of electrocatalysts (TM@TAP, TM = 3d and 4d transition metal) toward carbon dioxide reduction reaction (CO2RR) was systematically investigated using first-principles calculations. During screening potential catalysts, the possibility that H and OH block the active site was considered. Then, the reaction mechanisms of screened catalysts were explored in detail. Interestingly, the different catalysts demonstrated different selectivities. Our results demonstrate that Cr@TAP, Zn@TAP, Mo@TAP, and Cd@TAP are selective toward the HCOOH product with a limiting potential in the range of -0.33 to -0.71 V. Mn@TAP and Rh@TAP promote CO production. The reduction products of Fe@TAP and Co@TAP were CH3OH and HCHO, respectively. Tc@TAP and Ru@TAP can catalyze CO2 to yield the deep reduction product, i.e. CH4. Among these catalysts, Cr@TAP and Rh@TAP are highly active due to their lower limiting potentials of -0.33 V and -0.28 V, respectively, and Fe@TAP can promote the production of the desired CH3OH with a limiting potential of -0.51 V, which allow them to be promising electrocatalysts for the CO2RR. We hope that our study will provide some insights into the rational design of electrocatalysts and useful guidance for experimental researchers.

Spherical Fe7S8@rGO nanoflowers as electrodes with high electrocatalytic performance in dye-sensitized solar cells.

Dye-sensitized solar cells (DSSCs) can directly convert solar energy into electricity, and have aroused great research interest from researchers. Here, the spherical Fe7S8@rGO nanocomposites were expediently fabricated by facile methods, and applied in DSSCs as counter electrodes (CEs). The morphological features show the porous structure of Fe7S8@rGO, and it is beneficial to enhance the permeability of ions. Reduced graphene oxide (rGO) has a large specific surface area and good electrical conductivity, shortening the electron transfer path. The presence of rGO promotes the catalytic reduction of I3- ions to I- ions and reduces the charge transfer resistance (Rct). The experimental findings show that the power conversion efficiency (PCE) of Fe7S8@rGO as CEs for DSSCs can reach 8.40% (20 wt% for rGO), significantly higher than Fe7S8 (7.60%) and Pt (7.69%). Therefore, Fe7S8@rGO nanocomposite is expected to be an efficient and cost-effective CE material for DSSCs.

Partial Linker Substitution Strategy to Construct a Quaternary HKUST-like MOF for Efficient Acetylene Storage and Separation.

Multicomponent metal-organic frameworks (MOFs) have received much attention as emerging materials capable of precisely programing exquisite structures and specific functions. Here, we applied a partial linker substitution strategy to compile an HKUST-1-like quaternary MOF by introducing a bifunctional ligand into the well-known HKUST-1 structure. FUT-1, a new HKUST-like tbo topology MOF, was assembled with paddlewheel [Cu2(COO)4], triangular metallocycle pyrazole cluster Cu3(µ3-OH) (NN)3 building blocks, and two distinct linkers. FUT-1 exhibited good mechanical stability, water stability, and chemical stability (pH = 3-12) in aqueous solutions. Moreover, the porous environments created by this multicomponent primitive endow FUT-1 with high C2H2 storage and significantly selective separation performance of C2H2/CO2. Dynamic breakthrough experiments and ideal adsorbed solution theory calculations further demonstrate that FUT-1 can selectively capture C2H2 from C2H2/CO2 mixtures under ambient conditions. Based on grand canonical Monte Carlo simulations, the high C2H2 separation performance of FUT-1 is attributed to the π-complex formed between the C2H2 molecule and the trinuclear metallocycle clusters on the wall, which provides stronger affinity for C2H2 recognition than the CO2 molecule.

Study on SO2 and Cl2 sensor application of 2D PbSe based on first principles calculations.

In this paper, we use 2D PbSe to design a gas sensor to monitor the presence of SO2 and Cl2. We use first principles to verify the feasibility of this material, such as atomic structure, band gap, differential charge density and Bader charge. The results show that 2D PbSe can distinctly adsorb SO2 and Cl2. Furthermore, the adsorption of SO2 and Cl2 will affect the electronic structure of 2D PbSe, and some electrons in the PbSe are transferred to gas atoms. The band gap of the system after adsorption is smaller than that of the PbSe before adsorption. The band gap of single layer PbSe decreases by 41.92% after SO2 adsorption and 60.61% after Cl2 adsorption. The band gap of multi-layer PbSe decreases by 72.97% after SO2 adsorption and 43.24% after Cl2 adsorption. This shows that single layer PbSe is more sensitive to Cl2 and multi-layer PbSe is more sensitive to SO2. It provides a potential possibility for designing gas sensors for SO2 and Cl2 based on 2D PbSe.

Synthesis Strategy of Metal Oxide Quantum Wires via a Nanoparticle-Induced Graphene Oxide Rolling Procedure.

The efficient synthesis of quantum materials is becoming a research hotspot as it determines their successful application in the fields of biomedicine, illumination, energy, sensors, information, and communication. Among the quantum materials, it is still a challenge to synthesize quantum wires (QWs) with surfactants due to the inevitable radial growth of QWs in the soft template method. In this paper, amphipathic graphene oxide (GO) was adopted as a macromolecular surfactant to limit the radial growth instead of the commonly used surfactant. GO could roll up under its electrostatic interaction with a cuprous oxide (Cu2O) quantum dot (QD) and then form a tubular template for the growth of the Cu2O QW, which was named herein as the nanoparticle-induced graphene oxide rolling (NIGOR) procedure. The NIGOR procedure was confirmed by the molecular dynamics results by simulating systems consisting of GO and Cu2O nanoparticles. An intermediate with a necklace morphology corresponding to the simulation result was also observed experimentally during the formation of the QW. Meanwhile, the formation mechanism of the QW was demonstrated rationally. Furthermore, increasing the dosage of the reactant, reaction time, and temperature altered the diameter of the QW from 2 to 4 nm and also changed the morphology of the final products from a QD to a QW and then to a bundle of QWs. This was attributed to the aggregation of materials for the lowest surface energy in the system. Additionally, the universality of NIGOR was manifested via the synthesis of other metal oxides as well. The NIGOR strategy provided an alternative, convenient, and mass production method for synthesizing QWs.

Misfit Relaxation Mechanisms and Domain Ordering in Anisotropically Strained Manganite Thin Films.

The evolution of anisotropic strain in epitaxial Pr0.5Sr0.5MnO3 films grown on (LaAlO3)0.3(SrAl0.5Ta0.5O3)0.7(110) substrates has been characterized by off-specular X-ray reciprocal space mappings on the (130), (310), (222), and (222̅) reflections in the scattering zone containing the [110] axis. We demonstrate that a multistage hierarchical structural evolution (single-domain-like structure, domain ordering, twin domains, and/or periodic structural modulations) occurs as the film thickness increases, and the structural modulation between the two transverse in-plane [11̅0] and [001] directions is quite different due to the monoclinic distortion of the film. We then show the relationship between the distribution of diffraction spots in reciprocal space and their corresponding domain configurations in real space under various thicknesses, which is closely correlated with thickness-dependent magnetic and magnetotransport properties. More importantly, the distribution and annihilation dynamics of the domain ordering are imaged utilizing home-built magnetic force microscope, revealing that the structural domains tilted toward either the [001] or [001̅] direction are arranged along the [11̅1] and [1̅11] crystal orientations. The direct visualization and dynamics of anisotropic-strain-related domain ordering will open a new path toward the control and manipulation of domain engineering in strongly correlated perovskite oxide films.

Open-Environment Robotic Acoustic Perception for Object Recognition.

Object recognition in containers is extremely difficult for robots. Dynamic audio signals are more responsive to an object's internal property. Therefore, we adopt the dynamic contact method to collect acoustic signals in the container and recognize objects in containers. Traditional machine learning is to recognize objects in a closed environment, which is not in line with practical applications. In real life, exploring objects is dynamically changing, so it is necessary to develop methods that can recognize all classes of objects in an open environment. A framework for recognizing objects in containers using acoustic signals in an open environment is proposed, and then the kernel k nearest neighbor algorithm in an open environment (OSKKNN) is set. An acoustic dataset is collected, and the feasibility of the method is verified on the dataset, which greatly promotes the recognition of objects in an open environment. And it also proves that the use of acoustic to recognize objects in containers has good value.

Modulation of Phosphorene for Optimal Hydrogen Evolution Reaction.

Economical and highly effective catalysts are crucial to the electrocatalytic hydrogen evolution reaction (HER), and few-layer black phosphorus (phosphorene) is a promising candidate because of the high carrier mobility, large specific surface area, and tunable physicochemical characteristics. However, the HER activity of phosphorene is limited by the weak hydrogen adsorption ability on the basal plane. In this work, optimal active sites are created to modulate the electronic structure of phosphorene to improve the HER activity and the effectiveness is investigated theoretically by density-functional theory calculation and verified experimentally. The edges and defects affect the electronic density of states, and a linear relationship between the HER activity and lowest unoccupied states (εLUS) is discovered. The medium εLUS value corresponds to the suitable hydrogen adsorption strength. Experiments are designed and performed to verify the prediction, and our results show that a smaller phosphorene moiety with more edges and defects exhibits better HER activity and surface doping with metal adatoms improves the catalytic performance. The results suggest that modified phosphorene has large potential in efficient HER and provides a convenient standard to explore ideal electrocatalysts.

Sulfur in Mesoporous Tungsten Nitride Foam Blocks: A Rational Lithium Polysulfide Confinement Experimental Design Strategy Augmented by Theoretical Predictions.

To enhance the utilization of sulfur in lithium-sulfur batteries, three-dimensional tungsten nitride (WN) mesoporous foam blocks are designed to spatially localize the soluble Li2S6 and Li2S4 within the pore spaces. Meanwhile, the chemisorption behaviors of polysulfides and the capability of WN as an effective confiner are systematically investigated through density functional theory calculations and experimental studies. The theoretical calculations reveal a decrease in chemisorption strength between WN and the soluble polysulfides (Li2S8 > Li2S6 > Li2S4), while the interactions between WN and the insoluble Li2S2/Li2S show a high chemisorption strength of ca. 3 eV. Validating theoretical insights through electrochemical measurements further manifest that the assembled battery configurations with sulfur cathode confined in the thickest WN blocks exhibit the best rate capabilities (1090 and 510 mAh g-1 at 0.5C and 5C, respectively) with the highest initial Coulombic efficiency of 90.5%. Moreover, a reversible capacity of 358 mAh g-1 is maintained with a high Coulombic efficiency approaching to 100%, even after 500 cycles at 2C. As guided by in silico design, this work not only provides an effective strategy to improve the retentivity of polysulfides but also underpins that properly architectured WN can be effective retainers of polysulfides.

Interfacial Engineering of Ferromagnetism in Epitaxial Manganite/Ruthenate Superlattices via Interlayer Chemical Doping.

Interfacial charge transfer and structural proximity effects are the two essential routes to trigger and tune numerous functionalities of perovskite oxide heterostructures. However, the cooperation and competition of these two interfacial effects in one epitaxial system have not been fully understood. Herein, we fabricate a series of La0.67Ca0.33MnO3/CaRuO3 superlattices and introduce various chemical doping in the nonmagnetic CaRuO3 interlayers. We found that Ti, Sr, and La doping in the CaRuO3 layer can effectively tune the interfacial charge transfer and octahedral rotation, thus modulating the ferromagnetism of the superlattices. Specifically, the B-site Ti doping depletes the Ru 4d band and suppresses the interfacial charge transfer, leading to a decay of ferromagnetic Curie temperature ( TC). In contrast, the A-site Sr doping maintains a sizable charge transfer and meanwhile suppresses the octahedral rotation, which facilitates ferromagnetism and significantly enhances the TC up to 291 K. The La doping turns out to localize the itinerant electrons in the CaRuO3 layer, which suppresses both the interfacial charge transfer and ferromagnetism. The observed intriguing interfacial engineering of magnetism would pave a new way to understand the collective effects of interfacial charge transfer and structural proximity on the physical properties of oxide heterostructures.

Theoretical prediction of HfB2 monolayer, a two-dimensional Dirac cone material with remarkable Fermi velocity.

Searching for new two-dimensional (2D) Dirac cone materials has been popular since the discovery of graphene with a Dirac cone structure. Based on density functional theory (DFT) calculations, we theoretically designed a HfB2 monolayer as a new 2D Dirac material by introducing the transition metal Hf into a graphene-like boron framework. This newly predicted HfB2 monolayer has pronounced thermal and kinetic stabilities along with a Dirac cone with a massless Dirac fermion and Fermi velocities (3.59 × 105 and 6.15 × 105 m s-1) comparable to that of graphene (8.2 × 105 m s-1). This study enriches the diversity and promotes the application of 2D Dirac cone materials.

Functional Group Effects on the Photoelectronic Properties of MXene (Sc2CT2, T = O, F, OH) and Their Possible Photocatalytic Activities.

In view of the diverse functional groups left on the MXene during the etching process, we computationally investigated the effects of surface-group types on the structural, electronic and optical properties of Sc2CT2 (T = -O, -OH, -F) MXenes. For all geometries of the Sc2CT2 MXenes, the geometry I of Sc2CT2, which has the functional groups locating above the opposite-side Sc atoms, are lowest-energy structure. Accordingly, the energetically favorable Sc2CF2-I, Sc2CO2-I and Sc2C(OH)2-I were selected for further evaluation of the photocatalytic activities. We found that the Sc2CO2-I is metallic, while Sc2CF2-I and Sc2C(OH)2 are semiconductors with visible-light absorptions and promising carrier mobilities. Compared with the Sc2C(OH)2-I, the Sc2CF2-I has not only more suitable band gap (1.91 eV), but also the higher redox capability of photo-activated carriers, which should have better photocatalytic performance.

Efficient NiSe-Ni3Se2/Graphene Electrocatalyst in Dye-Sensitized Solar Cells: The Role of Hollow Hybrid Nanostructure.

Hollow and hybrid nanomaterials are excellent electrocatalysts on account of their novel electrocatalytic properties compared with homogeneous solid nanostructures. In this report, NiSe-Ni3Se2 hybrid nanostructure with morphology of hollow hexagonal nanodisk was synthesized in situ on graphene. A series of NiSe-Ni3Se2/RGO with different phase constitutions and nanostructures were obtained by controlling the durations of solvothermal treatment. Because of their unique hollow and hybrid structure, NiSe-Ni3Se2/RGO hollow nanodisks exhibited higher electrocatalytic performance than NiSe/RGO and solid NiSe-Ni3Se2/RGO nanostructure for reducing I3(-) as counter cell (CE) of dye-sensitized solar cells (DSSCs). Additionally, NiSe-Ni3Se2/RGO hollow nanodisks achieved much lower charge transfer resistance (Rct = 0.68 Ω) and higher power conversion efficiency (PCE) (7.87%) than those of Pt (Rct = 1.41 Ω, PCE = 7.28%).

Nanocomposite of tin sulfide nanoparticles with reduced graphene oxide in high-efficiency dye-sensitized solar cells.

A nanocomposite of SnS2 nanoparticles with reduced graphene oxide (SnS2@RGO) had been successfully synthesized as a substitute conventional Pt counter electrode (CE) in a dye-sensitized solar cell (DSSC) system. The SnS2 nanoparticles were uniformly dispersed onto graphene sheets, which formed a nanosized composite system. The effectiveness of this nanocomposite exhibited remarkable electrocatalytic properties upon reducing the triiodide, owning to synergistic effects of SnS2 nanoparticles dispersed on graphene sheet and improved conductivity. Consequently, the DSSC equipped with SnS2@RGO nanocomposite CE achieved power conversion efficiency (PCE) of 7.12%, which was higher than those of SnS2 nanoparticles (5.58%) or graphene sheet alone (3.73%) as CEs and also comparable to the value (6.79%) obtained with pure Pt CE as a reference.