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The aim of this cross-sectional survey was to analyze the semen parameters of volunteers from the Human Sperm Bank of Fudan University, as well as the related factors influencing these parameters. From January 2019 to December 2020, semen parameters from a total of 5214 men were included in this survey. The Kruskal–Wallis test was used to detect differences associated with several independent variables. A total of 5214 volunteers were included. The volunteers were registered in 33 provinces, autonomous regions, municipalities (including Macau and Taiwan) and 294 prefecture-level cities. The average age of volunteers was 27.40 years. Overall, 76.50% of the volunteers had a college education or higher. Volunteers with BMI values of 18.5–23.9 kg/m(2) accounted for 60.70% of participants. Semen parameters were significantly different according to season, education level, duration of abstinence, age group and BMI. The basic male fertility phenotypes (semen parameters) showed new trends in the study period, and accurate long-term tracking of male semen parameters will help researchers to better understand the changes in male fertility phenotypes (semen).

Developing highly efficient oxygen evolution reaction (OER) catalyst for the acidic corrosive operating conditions is a challenging task. Herein, we report the synthesis of uniform RuO2 clusters with ∼ 2 nm in size via electrochemical leaching of Sr from SrRuO3 ceramic in acid. The RuO2 clusters exhibit ultrahigh OER activity with overpotential of ∼ 160 mV at 10 mA·cmgeo−2 in 1.0 M HClO4 solution for 30-h testing. The extended X-ray absorption fine structure measurement reveals enlarged Jahn-Teller distortion of RuO octahedra in the RuO2 clusters compared to its bulk counterpart. Density function theory calculations show that the enhanced Jahn-Teller distortion can improve the intrinsic OER activity of RuO2.

Surface characterization of metal nanoparticles is a critical need in nanocatalysis for in-depth understanding of the structure-function relationships. The surface structure of nanoparticles is often different from the subsurface, and it is challenging to separately characterize the surface and the subsurface. In this work, theoretical calculations and extended X-ray absorption fine structure (EXAFS) analysis illustrate that the surface atoms of noble metals (Pt and Pd) are oxidized in the air, while the subsurface atoms are not easily oxidized. Taking advantage of the oxidation properties, we suggest a stepwise reduction-oxidation approach to determine the surface atomic arrangement of noble metal nanoparticles, and confirm the rationality of this approach by identifying the surface structure of typical 2–3 nm Pt and Pd nanoparticles. The reduction-oxidation approach is applied to characterize the surface structure of model Pd-Sb bimetallic catalyst, which illustrates that the surface Pd is well isolated by Sb atoms with short bond distance at 2.70 A, while there are still Pd-Pd bonds in the subsurface. Density functional theory (DFT) calculations and Pd L edge X-ray absorption near edge structure (XANES) indicate that the isolation of surface Pd significantly decreases the adsorption energies of Pd-hydrocarbon, which leads to the high propylene selectivity and turnover frequency Pd-Sb bimetallic catalyst for propane dehydrogenation.

Metal-nitrogen-carbon (M-N-C) single-atom catalysts exhibit desirable electrochemical catalytic properties. However, the replacement of N atoms by heteroatoms (B, P, S, etc.) has been regarded as a useful method for regulating the coordination environment. The structure engineered M-N-C sites via doping heteroatoms play an important role to the adsorption and activation of the oxygen intermediate. Herein, we develop an efficient strategy to construct dual atomic site catalysts via the formation of a Co1-PN and Ni1-PN planar configuration. The developed Co1-PNC/Ni1-PNC catalyst exhibits excellent bifunctional electrocatalytic performance in alkaline solution. Both experimental and theoretical results demonstrated that the N/P coordinated Co/Ni sites moderately reduced the binding interaction of oxygen intermediates. The Co1-PNC/Ni1-PNC endows a rechargeable Zn-air battery with excellent power density and cycling stability as an air-cathode, which is superior to that of the benchmark Pt/C+IrO2. This work paves an avenue for design of dual single-atomic sites and regulation of the atomic configuration on carbon-based materials to achieve high-performance electrocatalysts.

Developing artificial enzymes with the excellent catalytic performance of natural enzymes has been a long-standing goal for chemists. Single-atom catalysts with well-defined atomic structure and electronic coordination environments can effectively mimic natural enzymes. Here, we report an engineered FeN3P-centred single-atom nanozyme (FeN3P-SAzyme) that exhibits comparable peroxidase-like catalytic activity and kinetics to natural enzymes, by controlling the electronic structure of the single-atom iron active centre through the precise coordination of phosphorus and nitrogen. In particular, the engineered FeN3P-SAzyme, with well-defined geometric and electronic structures, displays catalytic performance that is consistent with Michaelis–Menten kinetics. We rationalize the origin of the high enzyme-like activity using density functional theory calculations. Finally, we demonstrate that the developed FeN3P-SAzyme with superior peroxidase-like activity can be used as an effective therapeutic strategy for inhibiting tumour cell growth in vitro and in vivo. Therefore, SAzymes show promising potential for developing artificial enzymes that have the catalytic kinetics of natural enzymes. Nanozymes can provide cost and stability advantages over natural enzymes, but they usually display low catalytic activity and inferior kinetics. Now, a highly active nanozyme is developed that shows comparable kinetics to horseradish peroxidase in the oxidation of a commonly used artificial substrate.

To predict disease outcome in muscle-invasive bladder cancer (MIBC), we constructed a prognostic autophagy-related (PAR) lncRNA signature. Comprehensive bioinformatics analyses were performed using data from TCGA and GTEx databases. Univariate Cox, and least absolute shrinkage and selection operator regression analyses were also performed, based on differentially expressed genes, to identify PAR-related lncRNAs to establish the signature. Furthermore, the Kaplan–Meier OS curve and receiver operating characteristic curve analyses were performed and a nomogram was constructed, all of which together confirmed the strong predictive ability of the constructed signature. Patients with MIBC were then divided into high- and low-risk groups. Gene enrichment and immune infiltration analyses revealed the potential mechanisms in MIBC. We also further evaluated the signature of molecules related to immune checkpoints and the sensitivity toward chemotherapeutic agents and antitumor-targeted drugs to find better treatment prescriptions. We identified a number of PAR-related lncRNA signatures, including HCP5, AC024060.1, NEAT1, AC105942.1, XIST, MAFG-DT, and NR2F1-AS1, which could be valuable prognostic tools to develop more efficient, individualized drug therapies for MIBC patients.

Regulating the selectivity of catalysts in selective hydrogenation reactions at the atomic level is highly desirable but remains a grand challenge. Here we report a simple and practical strategy to synthesize a monolithic single-atom catalyst (SAC) with isolated Pd atoms supported on bulk nitrogen-doped carbon foams (Pd-SAs/CNF). Moreover, we demonstrate that the single-atom Pd sites with unique electronic structure endow Pd-SAs/CNF with an isolated site effect, leading to excellent activity and selectivity in 4-nitrophenylacetylene semi-hydrogenation reaction. In addition, benefiting from the great integrity and excellent mechanical strength, monolithic Pd-SAs/CNF catalyst is easy to separate from the reaction system for conducting the subsequent recycling. The cyclic test demonstrates the excellent reusability and stability of monolithic Pd-SAs/CNF catalyst. The discovery of isolated site effect provides a new approach to design highly selective catalysts. And the development of monolithic SACs provides new opportunities to advance the practical applications of single-atom catalysts.

The oxidation of hydrocarbons to produce high value-added compounds (ketones or alcohols) using oxygen in air as the only oxidant is an efficient synthetic strategy from both environmental and economic views. Herein, we successfully synthesized cobalt single atom site catalysts (Co SACs) with high metal loading of 23.58 wt.% supported on carbon nitride (CN), which showed excellent catalytic properties for oxidation of ethylbenzene in air. Moreover, Co SACs show a much higher turn-over frequency (19.6 h−1) than other reported non-noble catalysts under the same condition. Comparatively, the as-obtained nanosized or homogenous Co catalysts are inert to this reaction. Co SACs also exhibit high selectivity (97%) and stability (unchanged after five runs) in this reaction. DFT calculations reveal that Co SACs show a low energy barrier in the first elementary step and a high resistance to water, which result in the robust catalytic performance for this reaction.

Decorating semi-conducting metal oxide with noble metal has been recognized as a viable approach to improve the sensitivity of gas sensor. However, conventional method which relys on noble metal nanoparticles is confronted with drawback of significantly increased cost. To maximize the atom efficiency and reduce the cost for practical industrial application, designing sensor material with noble metal isolated single atom sites (ISAS) doping is a desired option. Here, we report an atomically dispersed platinum on one-dimensional arranged porous γ-Fe2O3 nanoparticle composites as highly efficient ethanol gas sensor. The optimized sample (Pt1-Fe2O3-ox) exhibited a high response (Ra/Rg = 102.4) and good selectivity to ethanol gas. It is demonstrated only the Pt single atom sites with high valance can effectively promote the adsorption capacity to ethanol and consequently enhance the sensitivity of sensing process by changing the electrical structure of Fe2O3 support. This work indicates the single atom sites could play a vital role in improving the performance of conventional metal oxides gas sensors and pave way for the exploration of ISAS-enhanced gas sensor for other volatile organic compounds (VOCs).

The demand for high-performance non-precious-metal electrocatalysts to replace the noble metal-based catalysts for oxygen reduction reaction (ORR) is intensively increasing. Herein, single-atomic copper sites supported on N-doped three-dimensional hierarchically porous carbon catalyst (Cu1/NC) was prepared by coordination pyrolysis strategy. Remarkably, the Cu1/NC-900 catalyst not only exhibits excellent ORR performance with a half-wave potential of 0.894 V (vs. RHE) in alkaline media, outperforming those of commercial Pt/C (0.851 V) and Cu nanoparticles anchored on N-doped porous carbon (CuNPs/NC-900), but also demonstrates high stability and methanol tolerance. Moreover, the Cu1/NC-900 based Zn-air battery exhibits higher power density, rechargeability and cyclic stability than the one based on Pt/C. Both experimental and theoretical investigations demonstrated that the excellent performance of the as-obtained Cui/NC-900 could be attributed to the synergistic effect between copper coordinated by three N atoms active sites and the neighbouring carbon defect, resulting in elevated Cu d-band centers of Cu atoms and facilitating intermediate desorption for ORR process. This study may lead towards the development of highly efficient non-noble metal catalysts for applications in electrochemical energy conversion.

The design of non-noble metal heterogeneous catalyst with superior performance for selective hydrogenation or transfer hydrogenation of nitroarenes to amines is significant but challenging. Herein, a single-atom Fe supported by nitrogen-doped carbon (Fe1/N-C) catalyst is reported. The Fe1/N-C sample shows superior performances for the selective hydrogenation and transfer hydrogenation of nitrobenzene to aniline at different temperatures. Density functional theory (DFT) calculations show that the superior catalytic activity for the selective hydrogenation at lower temperatures could be attributed to the effective activation of the reactant and intermediates by the Fe1/N-C. Moreover, the excellent performance of Fe1/N-C for the selective transfer hydrogenation could be attributed to that the reaction energy barrier for dehydrogenation of isopropanol can be overcome by elevated temperatures.

Coal fly ash (FA) is one of the main byproducts of coal burning. Nearly half of FA cannot be reused or recycled. The potential environmental leaching of trace elements in FA may limit its application. Microbially induced carbonate precipitation (MICP) is a promising technology to improve soil properties. This study was to investigate the effect of fly ash in MICP-stabilized soil on its mechanical and environmental impacts. Two kinds of fly ash were considered: FA1 was Class-F fly ash, FA2 was off-specific fly ash. The 0% (sand only), 3%, 6% and 9% content of FA were introduced to FA-sand mixtures to perform MICP process. Triaxial compression test was performed to evaluate the effect of FA content on the development of strength. The triaxial test results indicated that with 3% addition of FA, the peak deviator stress increased significantly. When MICP-treated sand mixed with 3% FA1, the deviator stress increased to 1,959 kPa compared to that of MICP-treated sand only samples of 800 kPa. The peak deviator stress increased by 154% and 115% when the additions of FA1 were 6% and 9%, respectively. The stress increase was caused by the bonding of precipitated CaCO3 in MICP However, higher content of FA1 (9% or higher) could restrict the activity of bacteria by reducing the void spaces. MICP-treated samples with the addition of FA2 presented a better enhancement in peak stress for its higher CaO content which could lead to additional cementation besides MICP. Leaching tests by toxicity characteristic leaching procedure (TCLP) and sequential extraction tests indicated that there was no potential risk to introduce fly ash into the MICP process during the soil improvement. MICP process resulted to the fraction change of trace metals which could make trace metal more stable. Microscale images at scale of 10 µm, 100 µm and 200 µm have clearly presented the precipitated CaCO3. It showed that large amount of precipitated CaCO3 coated the particle surfaces and filled the void spaces. Small particles were buried and formed aggregates. There was a highly cemented phases produced between soil particle matrix. XRD analysis also confirmed the presence of CaCO3 crystal after the MICP process.

In recent decades, the environmental protection and long-term sustainability have become the focus of attention due to the increasing pollution generated by the intense industrialization. To overcome these issues, environmental catalysis has increasingly been used to solve the negative impact of pollutants emission on the global environment and human health. Supported platinum-metal-group (PGM) materials are commonly utilized as the state-of-the-art catalysts to eliminate gaseous pollutants but large quantities of PGMs are required. By comparison, single-atom site catalysts (SACs) have attracted much attention in catalysis owing to their 100% atom efficiency and unique catalytic performances towards various reactions. Over the past decade, we have witnessed burgeoning interests of SACs in heterogeneous catalysis. However, to the best of our knowledge, the systematic summary and analysis of SACs in catalytic elimination of environmental pollutants has not yet been reported. In this paper, we summarize and discuss the environmental catalysis applications of SACs. Particular focus was paid to automotive and stationary emission control, including model reaction (CO oxidation, NO reduction and hydrocarbon oxidation), overall reaction (three-way catalytic and diesel oxidation reaction), elimination of volatile organic compounds (formaldehyde, benzene, and toluene), and removal/decomposition of other pollutants (Hg0 and SO3). Perspectives related to further challenges, directions and design strategies of single-atom site catalysts in environmental catalysis were also provided.

Atomic non-noble metal materials show the potential to substitute noble metals in catalysis. Herein, melamine formaldehyde resin is developed to synthesize atomic iron on mesoporous nitrogen-doped carbon. The triazine units with abundant nitrogen content and cavity can realize effectively anchoring of single metal atoms. The atomic iron with unique charge and coordination characteristics shows superior catalytic performance in dehydrogenation reaction. Various N-heterocycles compounds and amines can be efficiently dehydrogenated into the corresponding products at room temperature, which is the mildest of all reported reaction conditions even when noble metal catalysts are considered. Therefore, development of atomic non-noble metal catalysts with mesoporous structure may provide an effective way to realize the substitution for noble metals in heterogeneous catalysis.

Mesocrystals, the non-classical crystals with highly ordered nanoparticle superstructures, have shown great potential in many applications because of their newly collective properties. However, there is still a lack of a facile and general synthesis strategy to organize and integrate distinct components into complex mesocrystals, and of reported application for them in industrial catalytic reactions. Herein we report a general bottom-up synthesis of CuO-based trimetallic oxide mesocrystals (denoted as CuO-M1Ox-M2Oy, where M1 and M2 = Zn, In, Fe, Ni, Mn, and Co) using a simple precipitation method followed by a hydrothermal treatment and a topotactic transformation via calcination. When these mesocrystals were used as the catalyst to produce trichlorosilane (TCS) via Si hydrochlorination reaction, they exhibited excellent catalytic performance with much increased Si conversion and TCS selectivity. In particular, the TCS yield was increased 19-fold than that of the catalyst-free process. The latter is the current industrial process. The efficiently catalytic property of these mesocrystals is attributed to the formation of well-defined nanoscale heterointerfaces that can effectively facilitate the charge transfer, and the generation of the compressive and tensile strain on CuO near the interfaces among different metal oxides. The synthetic approach developed here could be applicable to fabricate versatile complicated metal oxide mesocrystals as novel catalysts for various industrial chemical reactions.

Single-atom site (SA) catalysts on N-doped carbon (CN) materials exhibit prominent performance for their active sites being M-Nx. Due to the commonly random doping behaviors of N species in these CN, it is a tough issue to finely regulate their doping types and clarify their effect on the catalytic property of such catalysts. Herein, we report that the N-doping type in CN can be dominated as pyrrolic-N and pyridinic-N respectively through compounding with different metal oxides. It is found that the proportion of distinct doped N species in CN depends on the acidity and basicity of compounded metal oxide host. Owing to the coordination by pyrrolic-N, the SA Cu catalyst displays an enhanced activity (two-fold) for transfer hydrogenation of quinoline to access the valuable molecule tetrahydroquinoline with a good selectivity (99%) under mild conditions. The higher electron density of SA Cu species induced by the predominate pyrrolic-N coordination benefits the hydrogen transfer process and reduces the energy barrier of the hydrogenation pathway, which accounts for the improved catalytic effeciency.

A caisson can be suspended in the river during its settlement construction. The water flows induces the local scour of sediments under the caisson, which increases the settlement difficulty and threatens the safety of construction. A numerical model using computational fluid dynamics (CFD) was introduced to simulate the local scour process around the caisson. The numerical model was validated with a set of experimental tests, which were conducted to investigate the local scour for a square caisson model with different clearances under steady flow. The evolutions and characteristics of local scour pits as a function of clearance were investigated based on the experimental and numerical results. The effect of grain size of sediment and the scour mechanism for suspended caisson were discussed as well. The main findings include: 1) the minimum inflow velocity for the scour of sediment depends on the clearance between the caisson bottom and sediment; 2) the numerical model provides reasonable evolution of local scour pit and flow field around the caisson; and 3) the scour depth of suspended caisson can be as high as 70% of that for the settled caisson and deserves attention for the safe settlement of caisson.

Single-atom catalysts not only maximize metal atom efficiency, they also display properties that are considerably different to their more conventional nanoparticle equivalents, making them a promising family of materials to investigate. Herein we developed a general host–guest strategy to fabricate various metal single-atom catalysts on nitrogen-doped carbon (M1/CN, M = Pt, Ir, Pd, Ru, Mo, Ga, Cu, Ni, Mn). The iridium variant Ir1/CN electrocatalyses the formic acid oxidation reaction with a mass activity of 12.9 $${{{\rm{A}}\,{\rm{mg}}^{-1}_{{\rm{Ir}}}}}$$ whereas an Ir/C nanoparticle catalyst is almost inert (~4.8 × 10−3 $${{{\rm{A}}\,{\rm{mg}}^{-1}_{{\rm{Ir}}}}}$$). The activity of Ir1/CN is also 16 and 19 times greater than those of Pd/C and Pt/C, respectively. Furthermore, Ir1/CN displays high tolerance to CO poisoning. First-principle density functional theory reveals that the properties of Ir1/CN stem from the spatial isolation of iridium sites and from the modified electronic structure of iridium with respect to a conventional nanoparticle catalyst. Single-atom catalysts maximize metal atom efficiency and exhibit properties that can be considerably different to their nanoparticle equivalent. Now a general host–guest strategy to make various single-atom catalysts on nitrogen-doped carbon has been developed; the iridium variant electrocatalyses the formic acid oxidation reaction with high mass activity and displays high tolerance to CO poisoning.

The rational design of efficient single-atomic (SA) catalysts is essential and highly desirable but impeded by the lack of sufficient acknowledge between structure and property. To this end, it is critical to clarify the effect of the coordination structure of active metal centers on the catalytic activities for the design of such catalysts. Here, we report that different coordination structures of SA Pt catalysts can dramatically influence their activities for anti-Markovnikov hydroboration of alkenes. Compared with the other two coordination structures (Pt-N4 and Pt-O2), the SA Pt species coordinated with three O atoms (Pt-O3) display the highest turnover number value of 3288 for the hydroboration reaction to access the important alkylboronic esters. Density functional theory calculations reveal that a superior catalytic activity can be expected for alkene hydroboration over the three O coordinated Pt species due to the lowest reaction energy (Δ G ) limiting step from the reaction phase diagram.

With high energy density and low material cost, lithium-sulfur batteries (LSBs) emerge quite expeditiously as a fascinating energy storage system over the past decade. Broad applications of LSBs ranging from electric vehicles to stationary grid storage seem rather bright in recent literatures. However, there still exist many pressing challenges to be addressed because we do not yet fully understand and control the electrode-electrolyte interface chemistries during battery operation, such as polysulfide shuttling and poor utilization of active sulfur. Single-atom catalysts (SACs) pave new possibilities of tackling the tough issues due to their decent applicability in the atomic-level identification of structure-activity relationships and reaction mechanism, as well as their structural tunability with atomic precision. This review comprehensively summarizes the very recent advances in utilization of highly active SACs for LSBs by stating and discussing the related publications, which involves catalyst synthesis routes, battery performance, catalytic mechanisms, optimization strategies, and promises to achieve long-life, high-energy LSBs. We see that endeavors to employ SACs to modify sulfur cathode have allowed efficient polysulfide conversion and confinement, leading to the minimization of shuttle effect. Parallel efforts are being devoted to extending the scope of SACs to cell separator and lithium metal anode in order to unlock the full potential of LSBs. We also obtain mechanistic insights into battery chemistries and nature of SACs in their strong interactions with polysulfides through advanced in situ characterizations documented. Overall, acceleration in the development of LSBs by introducing SACs is noticeable, and this cutting edge needs more attentions to further promoting the design of better LSBs.

To meet the requirements of potential applications, it is of great importance to explore new catalysts for formic acid oxidation that have both ultra-high mass activity and CO resistance. Here, we successfully synthesize atomically dispersed Rh on N-doped carbon (SA-Rh/CN) and discover that SA-Rh/CN exhibits promising electrocatalytic properties for formic acid oxidation. The mass activity shows 28- and 67-fold enhancements compared with state-of-the-art Pd/C and Pt/C, respectively, despite the low activity of Rh/C. Interestingly, SA-Rh/CN exhibits greatly enhanced tolerance to CO poisoning, and Rh atoms in SA-Rh/CN resist sintering after long-term testing, resulting in excellent catalytic stability. Density functional theory calculations suggest that the formate route is more favourable on SA-Rh/CN. According to calculations, the high barrier to produce CO, together with the relatively unfavourable binding with CO, contribute to its CO tolerance. Atomically dispersed Rh on N-doped carbon exhibits 28- and 67-fold enhancements compared with state-of-the-art Pd/C and Pt/C, despite the low activity of Rh/C. The Rh single atoms exhibit high tolerance to CO poisoning compared to Rh nanoparticles.

The local coordination environment of catalysts has been investigated for an extended period to obtain enhanced catalytic performance. Especially with the advancement of single-atom catalysts (SACs), research on the coordination environment has been advanced to the atomic level. The surrounding coordination atoms of central metal atoms play important roles in their catalytic activity, selectivity and stability. In recent years, remarkable improvements of the catalytic performance of SACs have been achieved by the tailoring of coordination atoms, coordination numbers and second- or higher-coordination shells, which provided new opportunities for the further development of SACs. In this review, the characterization of coordination environment, tailoring of the local coordination environment, and their related adjustable catalytic performance will be discussed. We hope this review will provide new insights on further research of SACs.

This study aims to investigate the magnitude and distribution of welding residual stresses in orthotropic steel decks stiffened with U-shaped ribs. Numerical simulation of the welding residual stresses is performed using the thermal elastic–plastic finite element method. The residual stresses are subsequently measured using the hole-drilling strain-gage method. Based on the results of this study, it can be determined that: (1) The longitudinal welding residual stresses (σz) in the weld zones are tensile stresses, where the peak value exceeds the minimum yield strength (fyl); however, relatively low compressive stresses exist in the areas located far away from the welds; (2) The stress gradient in the weld zone is steep, and the widths of the areas experiencing tensile stress are narrow; (3) In the case of the upper surface of the deck, the weld that is first deposited has the highest peak stress, while similar stresses are determined for the remaining welds. In the case of the lower surface of the deck, the peak stress in the weld zones is greater than that on the upper surface; (4) In the case of the weld zone of the U-shaped ribs, the tensile stresses reach up to 1.15fyl; however, at locations a short distance away from the welds, the σz varies from tensile to compressive, and finally transforms into a small tensile stress at the base of the U-shaped ribs. In addition, the simulated and measured σz are compared, and the deviation between them is analyzed.

Metal isolated single atomic sites catalysts have attracted intensive attention in recent years owing to their maximized atom utilization and unique structure. Despite the success of single atom catalyst synthesis, directly anchoring metal single atoms on three-dimensional (3D) macro support, which is promising to achieve the heterogenization of homogeneous catalysis, remains a challenge and a blank in this field. Herein, we successfully fabricate metal single atoms (Pd, Pt, Ru, Au) on porous carbon nitride/reduced graphene oxide (C3N4/rGO) foam as highly efficient catalysts with convenient recyclability. C3N4/rGO foam features two-dimensional microstructures with abundant N chelating sites for the stabilization of metal single atoms and vertically-aligned hierarchical mesostructure that benefits the mass diffusion. The obtained Pd1/C3N4/rGO monolith catalyst exhibits much enhanced activity over its nanoparticle counterpart for Suzuki-Miyaura reaction. Moreover, the Pd1/C3N4/rGO monolith catalyst can be readily assembled in a flow reactor to achieve the highly efficient continuous production of 4-nitro-1,1′-biphenyl through Suzuki-Miyaura coupling.

The Synthetic Jet (SJ) control on the propulsion behavior of a foil in plunge-pitch motion is examined in this work by numerical simulations. An elliptic foil with ratio of 8 performs the plunge and pitch motions synchronously. A pair of SJs with the same frequency and strength is integrated into the upper and lower surfaces of the foil. As a result, the local flow field around the foil could be obviously modified by the SJs. At the Reynolds number of 200, the effects of the inclined angle between the jet direction and the chord line, the phase angle between the SJs and the flapping motion as well as the location of SJ on the propulsion performance are systematically investigated. Compared with the pure plunging and pitching foil, it is indicated that the enhancement of mean thrust and propulsive efficiency can be obtained by the SJs with suitable working parameters. Based on the numerical analysis, it is found that the jet flow on the foil surfaces, which changes the local pressure distribution to increase the pressure difference between upper and lower surfaces, can benefit the propulsion behavior of the flapping foil.

Heterojunctions modulated internal electric field (IEF) usually result in suboptimal efficiencies in carrier separation and utilization because of the narrow IEF distribution and long migration paths of photocarriers. In this work, we report distinctive bismuth oxyhydroxide compound nanorods (denoted as BOH NRs) featuring surface-exposed open channels and a simple chemical composition; by simply modifying the bulk anion layers to overcome the limitations of heterojunctions, the bulk IEF could be readily modulated. Benefiting from the unique crystal structure and the localization of valence electrons, the bulk IEF intensity increases with the atomic number of introduced halide anions. Therefore, A low exchange ratio (~10%) with halide anions (I–, Br–, Cl–) gives rise to a prominent elevation in carrier separation efficiency and better photocatalytic performance for benzylamine coupling oxidation. Here, our work offers new insights into the design and optimization of semiconductor photocatalysts., Research on the bulk internal electric field (IEF) regulation is significant for designing high-efficiency photocatalysts. Here, the authors report distinctive bismuth oxyhydroxide nanorods photocatalyst and increase the bulk IEF intensity by halogen ions exchange.

The facility location of a competing firm in a market has great importance in supply chain management. The two-stage competitive location model formulates the decision process of an entrant firm facing both location and price competition. In this paper, we incorporated the facility quantity as a decision variable into a two-stage competitive location model with the objective of maximized profit. Sequential location mode and simultaneous location mode were applied to simulate different location behavior. We developed an approximate branch and bound method to accelerate optimal location searching speed under the premise of accuracy. Greedy algorithm and approximate branch and bound method were used in two location modes. From algorithm evaluation, we found that the approximate branch and bound method is an ideal supplement of the traditional branch and bound method, especially for location problems with large-scale potential locations. Compare the results of the two modes, we found when a new firm is going to enter a market with both price and location competition, sequential location mode is an advantage strategy, since it can gain more profit than simultaneous location mode.

For electrocatalytic reduction of CO2 to CO, the stabilization of intermediate COOH* and the desorption of CO* are two key steps. Pd can easily stabilize COOH*, whereas the strong CO* binding to Pd surface results in severe poisoning, thus lowering catalytic activity and stability for CO2 reduction. On Ag surface, CO* desorbs readily, while COOH* requires a relatively high formation energy, leading to a high overpotential. In light of the above issues, we successfully designed the PdAg bimetallic catalyst to circumvent the drawbacks of sole Pd and Ag. The PdAg catalyst with Ag-terminated surface not only shows a much lower overpotential (-0.55 V with CO current density of 1 mA/cm2) than Ag (−0.76 V), but also delivers a CO/H2 ratio 18 times as high as that for Pd at the potential of -0.75 V vs. RHE. The issue of CO poisoning is significantly alleviated on Ag-terminated PdAg surface, with the stability well retained after 4 h electrolysis at -0.75 V vs. RHE. Density functional theory (DFT) calculations reveal that the Ag-terminated PdAg surface features a lowered formation energy for COOH* and weakened adsorption for CO*, which both contribute to the enhanced performance for CO2 reduction.

Here, we successfully developed nanostructured PtNi particles supported on nitrogen-doped carbon (NC), which were obtained by carbonization of metal-organic frameworks under different temperatures, forming the nano-PtNi/NC-600, nano-PtNi/NC-800, nano-PtNi/NC-900 and nano-PtNi/NC-1000 catalysts. For hydrosilylation of 1-octene, we found that the nano-PtNi/NC-1000 catalyst exhibits higher activity for anti-Markovnikov hydrosilylation of 1-octene than those of nano-PtNi/NC-600, nano-PtNi/NC-800, nano-PtNi/NC-900 catalysts. Experiments have verified that benefiting from obvious charge transfer from nano-PtNi particles to NC support carbonized at 1,000 °C, the nano-PtNi/NC-1000 catalyst achieved almost complete conversion and produce exclusive adduct for anti-Markovnikov hydrosilylation of 1-octene. Importantly, the nano-PtNi/NC-1000 catalyst exhibited good reusability for the hydrosilylation reaction. This work provides a new path to optimize electronic structure of catalysts by support modification to enhance electron transfer between metal active species and supports for highly catalytic performance.

With the increasingly widespread researches of wireless passive sensing technology based on LC sensors in the field of intracranial pressure (ICP) monitoring and other biomedical applications, the importance of sensor optimization has become increasingly prominent. This paper presents an optimization method of LC sensor enabling wireless passive ICP monitoring. The LC sensor is a resonant tank formed by a pressure-sensitive capacitor and a fixed inductor. The parameters of the capacitor and the inductor are optimized based on four optimization criteria: maximizing sensitivity, setting anodic bonding voltage less than pull-in voltage, maximizing quality factor and setting an upper limit of resonant frequency. Among them, the pull-in voltage is a critical value when pull-in effect occurs during anodic bonding, a key step in the process of capacitor fabrication. To analytically calculate the pull-in voltage, a pull-in effect model is built, and its effectiveness is verified by simulation and experiment. Based on the above-mentioned optimization criteria, the LC sensor is optimized, fabricated and characterized. The experimental results show that the optimized sensor achieves competitive sensitivity, quality factor and resonant frequency compared with the previous reports, and illustrate the effectiveness of the optimization method enabling ICP monitoring.

Bimetallic nanocrystals (BMNCs) with distinguished electronic and chemical properties from those of their parent metals, offer the opportunity to obtain new catalysts with enhanced selectivity, activity, and stability. Here we describe the facile synthesis of rhodium-copper bimetallic system with different compositions and uniform morphology for chemo selective hydrogenation of functionalized quinolines. Our findings demonstrate that Rh-Cu BMNCs exhibited composition dependent activity and selectivity. BMNCs with rhodium to copper ratio 3:1 surpassed individual Rh and Cu and other compositions both in activity and selectivity for quinolines hydrogenation and performed even better than Rh/C with same amount of Rh. Rh3Cu1 catalyst displayed excellent tolerance for synthetically significant functional groups such as −OH, NH2, F, particularly for aldehyde group which is very reactive towards reduction. These results suggested that the coexistence of rhodium and copper metals play important role in the enhancement of catalytic activity due to synergistic effects and revealed that bimetallic nanocrystals can be promising as practical catalysts for selective hydrogenation of quinoline and other substrates.

Photocatalytic oxidation has been widely employed in organic synthesis, by virtue of the green, mild and simple reaction conditions as well as high selectivity. Introducing oxygen vacancies (OVs) with proper concentrations into the photocatalysts has been proven as an effective strategy to boost the catalytic performances. However, the currently used treatment method under high temperature at reducing atmosphere inevitably introduces a large number of OVs at the interior of the catalyst and serving as the recombination centers of carriers. To address this issue, here we develop a facile solvothermal process to prepare ultrathin BiOBr nanosheets with rich surface OVs. This method effectively decreases the bulk of the material and the ratio of interior OVs, rendering most of the OVs exposed on the surfaces which act as exposed catalytic sites and enhance the separation of carriers, therefore significantly elevates the photocatalytic performances. For the photo-oxidation reaction of secondary amines, under the conditions of visible light, ambient temperature and atmosphere, the BiOBr nanosheets featuring rich surface OVs deliver a doubled conversion compared to those with low OV concentrations, and a high selectivity of 99%, a high stability as the performance shows no reduction after 5 times of circular reaction.

Herbaspirillum sp. WT00C is a tea-plant-specific endophytic bacterium. A genomic survey revealed an intact pathway for selenocompound metabolism in the genome of this bacterium. When it was cultured with sodium selenate, Herbaspirillum sp. WT00C was able to turn the culture medium to red. Electron microscopy and energy-dispersive X-ray spectroscopy confirmed that Herbaspirillum sp. WT00C reduced selenite (Se6+) to elemental selenium (Se0), and selenium nanoparticles (SeNPs) were secreted outside bacterial cells and grew increasingly larger to form Se-nanospheres and finally crystallized to form selenoflowers. Biochemical assays showed that selenospheres contained proteins but not carbohydrates or lipids. The improvement of selenium enrichment of tea plants by Herbaspirillum sp. WT00C was also tested. After Herbaspirillum sp. WT00C was inoculated into tea seedlings via needle injection and soaking tea-cutting methods, this endophytic bacterium markedly enhanced selenium enrichment of tea. When the tea seedlings inoculated by soaking tea-cutting mode were cultivated in the selenium-containing soils, selenium contents of tea leaves in three experimental groups were more than twofold compared to those of control groups. Our study demonstrates that the endophytic bacterium Herbaspirillum sp. WT00C has the ability to reduce selenate and improve selenium enrichment of tea.

Single-atom precious metal catalysts hold the promise of perfect atom utilization, yet control of their activity and stability remains challenging. Here we show that engineering the electronic structure of atomically dispersed Ru1 on metal supports via compressive strain boosts the kinetically sluggish electrocatalytic oxygen evolution reaction (OER), and mitigates the degradation of Ru-based electrocatalysts in an acidic electrolyte. We construct a series of alloy-supported Ru1 using different PtCu alloys through sequential acid etching and electrochemical leaching, and find a volcano relation between OER activity and the lattice constant of the PtCu alloys. Our best catalyst, Ru1–Pt3Cu, delivers 90 mV lower overpotential to reach a current density of 10 mA cm−2, and an order of magnitude longer lifetime over that of commercial RuO2. Density functional theory investigations reveal that the compressive strain of the Ptskin shell engineers the electronic structure of the Ru1, allowing optimized binding of oxygen species and better resistance to over-oxidation and dissolution. While Ru-based electrocatalysts are among the most active for acidic water oxidation, they suffer from severe deactivation. Now, Yuen Wu, Wei-Xue Li and co-workers report a core–shell Ru1–Pt3Cu catalyst with surface-dispersed Ru atoms for a highly active and stable oxygen evolution reaction in acid electrolyte.

The electrochemical reduction of CO2 could play an important role in addressing climate-change issues and global energy demands as part of a carbon-neutral energy cycle. Single-atom catalysts can display outstanding electrocatalytic performance; however, given their single-site nature they are usually only amenable to reactions that involve single molecules. For processes that involve multiple molecules, improved catalytic properties could be achieved through the development of atomically dispersed catalysts with higher complexities. Here we report a catalyst that features two adjacent copper atoms, which we call an ‘atom-pair catalyst’, that work together to carry out the critical bimolecular step in CO2 reduction. The atom-pair catalyst features stable Cu10–Cu1x+ pair structures, with Cu1x+ adsorbing H2O and the neighbouring Cu10 adsorbing CO2, which thereby promotes CO2 activation. This results in a Faradaic efficiency for CO generation above 92%, with the competing hydrogen evolution reaction almost completely suppressed. Experimental characterization and density functional theory revealed that the adsorption configuration reduces the activation energy, which generates high selectivity, activity and stability under relatively low potentials. Anchored single-atom catalysts have recently been shown to be very active for various processes, however, a catalyst that features two adjacent copper atoms—which we call an atom-pair catalyst—is now reported. The Cu10–Cu1x+ pair structures work together to carry out the critical bimolecular step in CO2 reduction.

TiO2-based varistor–capacitor ceramics co-doped with fixed Nb2O5, MnO2, Sm2O3 and various content of Sb2O3 are prepared, and then the effect of Sb2O3 on electrical properties of TiO2 varistor–capacitor ceramics is investigated. The results indicate that addition of Sb2O3 effectively decreases breakdown voltage (E1mA), while having less impact on the nonlinear coefficient (α). E1mA initially increases and then decreases with Sb2O3 increasing; contrarily, relative dielectric constant (er) decreases first and then increases. It is found that composition of 98.3%TiO2-0.8%Nb2O5-0.3%MnO2-0.3%Sm2O3-0.3%Sb2O3 is obtained with a low breakdown voltage of 2.3 V/mm, nonlinear coefficient of 2.0, high relative dielectric constant of 7.6 × 104 and low dissipation factor of 0.25, which is consistent with the narrowest grain boundary barriers in the composition. The nonlinear coefficient initially increases and then decreases with increase of Sb2O3; it reaches a maximum value of 2.9 at 0.2 mol.% Sb2O3, which is consistent with the highest grain boundary barriers in the composition. In order to explain the nonlinear current–voltage characteristics, a grain boundary defect barrier model was introduced.