Reducing the dimensions of metallic nanoparticles to isolated,single atom has attracted considerable attention in heterogeneous catalysis,because it significantly improves atomic utilization and often leads to distinc...Reducing the dimensions of metallic nanoparticles to isolated,single atom has attracted considerable attention in heterogeneous catalysis,because it significantly improves atomic utilization and often leads to distinct catalytic performance.Through extensive research,it has been recognized that the local coordination environment of single atoms has an important influence on their electronic structures and catalytic behaviors.In this review,we summarize a series of representative systems of single-atom catalysts,discussing their preparation,characterization,and structure-property relationship,with an emphasis on the correlation between the coordination spheres of isolated reactive centers and their intrinsic catalytic activities.We also share our perspectives on the current challenges and future research promises in the development of single-atom catalysis.With this article,we aim to highlight the possibility of finely tuning the catalytic performances by engineering the coordination spheres of single-atom sites and provide new insights into the further development for this emerging research field.展开更多
Tissue engineering is promising to meet the increasing need for bone regeneration. Nanostructured calcium phosphate （CAP） biomaterials/scaffolds are of special interest as they share chemical/crystallographic simila...Tissue engineering is promising to meet the increasing need for bone regeneration. Nanostructured calcium phosphate （CAP） biomaterials/scaffolds are of special interest as they share chemical/crystallographic similarities to inorganic components of bone. Three applications of nano-CaP are discussed in this review： nanostructured calcium phosphate cement （CPC）; nano-CaP composites; and nano-CaP coatings. The interactions between stem cells and nano-CaP are highlighted, including cell attachment, orientation/ morphology, differentiation and in vivo bone regeneration. Several trends can be seen： （i） nano-CaP biomaterials support stem cell attachment/proliferation and induce osteogenic differentiation, in some cases even without osteogenic supplements; （ii） the influence of nano-CaP surface patterns on cell alignment is not prominent due to non-uniform distribution of nano-crystals; （iii） nano-CaP can achieve better bone regeneration than conventional CaP biomaterials; （iv） combining stem cells with nano-CaP accelerates bone regeneration, the effect of which can be further enhanced by growth factors; and （v） cell microencapsulation in nano-CaP scaffolds is promising for bone tissue engineering. These understandings would help researchers to further uncover the underlying mechanisms and interactions in nano-CaP stem cell constructs in vitro and in vivo, tailor nano-CaP composite construct design and stem cell type selection to enhance cell function and bone regeneration, and translate laboratory findings to clinical treatments.展开更多
Conductor and suction anchor are the key equipment providing bearing capacity in the field of deep-water drilling or offshore engineering,which have the advantages of high operation efficiency and short construction p...Conductor and suction anchor are the key equipment providing bearing capacity in the field of deep-water drilling or offshore engineering,which have the advantages of high operation efficiency and short construction period.In order to drill a horizontal well in the shallow hydrate reservoir in the deep water,the suction anchor wellhead assembly is employed to undertake the main vertical bearing capacity in the second round of hydrate trial production project,so as to reduce the conductor running depth and heighten the kick-off point position.However,the deformation law of the deep-water suction anchor wellhead assembly under the moving load of the riser is not clear,and it is necessary to understand the lateral bearing characteristics to guide the design of its structural scheme.Based on 3D solid finite element method,the solid finite element model of the suction anchor wellhead assembly is established.In the model,the seabed soil is divided into seven layers,the contact between the wellhead assembly and the soil is simulated,and the vertical load and bending moment are applied to the wellhead node to simulate the riser movement when working in the deep water.The lateral bearing stability of conventional wellhead assembly and suction anchor wellhead assembly under the influence of wellhead load is discussed.The analysis results show that the bending moment is the main factor affecting the lateral deformation of the wellhead string;the anti-bending performance from increasing the outer conductor diameter is better than that from increasing the conductor wall thickness;for the subsea wellhead,the suction anchor obviously improves the lateral bearing capacity and reduces the lateral deformation.The conduct of the suction anchor wellhead assembly still needs to be lowered to a certain depth that below the maximum disturbed depth to ensure the lateral bearing stability,Thus,a method for the minimum conductor running depth for the suction anchor wellhead assembly is developed.The field implementations show that compared with the first round of hydrate trial production project,the conductor running depth is increased by 9.42 m,and there is no risk of wellhead overturning during the trial production.The method for determining the minimum conductor running depth in this paper is feasible and will still play an important role in the subsequent hydrate exploration and development.展开更多
Novel bioengineering functional organoboron polymers were synthesized by 1) amidolysis of poly(acrcylic acid) (PAA) with 2-aminoethyldiphenyl borinate (2-AEPB), 2) esterification of organoboron PAA polymer (PAA-B) wit...Novel bioengineering functional organoboron polymers were synthesized by 1) amidolysis of poly(acrcylic acid) (PAA) with 2-aminoethyldiphenyl borinate (2-AEPB), 2) esterification of organoboron PAA polymer (PAA-B) with a-hydroxy-methoxypoly(ethylene oxide) (PEO) as a compatibilizer and 3) conjugation of organoboron PEO branches (PAA-B-PEO) with folic acid (FA) as a targeting agent. Structure and composition of the synthesized polymers were characterized by FTIR-ATR and 1H (13C) NMR spectroscopy, chemical and physical analysis methods. Anti-tumor activity of organoboron functional polymer and its complex with FA (PAA-B-PEO-F) against cancer and normal cells were evaluated by using different biochemical methods such as cytotoxicity, statistical, apoptotic and necrotic cell indexes, double staining and caspase-3 immune staining, light and fluorescence inverted microscope analyses. It was found that citotoxicity and apoptotic/necrotic effects of polymers significantly depend on the structure and composition of studied polymers, and increase the following raw: PAA << PAA-B < PAA-B-PEO < PAA-B-PEO-F. Among them, PAA-B-PEO-F complex at 400 mg mL–1 concentration as a therapeutic drug exhibits minimal toxicity toward the nor-mal cells, but influential for HeLa cancer cells.展开更多
Amorphous carbons are promising anodes for high-rate potassium-ion batteries.Most low-temperature annealed amorphous carbons display unsatisfactory capacities.Heteroatom-induced defect engineering of amorphous carbons...Amorphous carbons are promising anodes for high-rate potassium-ion batteries.Most low-temperature annealed amorphous carbons display unsatisfactory capacities.Heteroatom-induced defect engineering of amorphous carbons could enhance their reversible capacities.Nevertheless,most lignocellulose biomasses lack heteroatoms,making it a challenge to design highly heteroatom-doped carbons(>10 at%).Herein,we report a new preparation strategy for amorphous carbon anodes.Nitrogen/sulfur co-doped lignin-derived porous carbons(NSLPC)with ultra-high nitrogen doping levels(21.6 at%of N and 0.8 at%of S)from renewable lignin biomacromolecule precursors were prepared through a supramolecule-mediated pyrolysis strategy.This supermolecule/lignin composite decomposes forming a covalently bonded graphitic carbon/amorphous carbon intermediate product,which induces the formation of high heteroatom doping in the obtained NSLPC.This unique pyrolysis chemistry and high heteroatom doping of NSLPC enable abundant defective active sites for the adsorption of K+and improved kinetics.The NSLPC anode delivered a high reversible capacity of 419 mAh g^(-1)and superior cycling stability(capacity retention of 96.6%at 1 A g^(-1)for 1000 cycles).Potassiumion hybrid capacitors assembled by NSLPC anode exhibited excellent cycling stability(91%capacity retention for 2000 cycles)and a high energy density of 71 Wh kg^(-1)at a power density of 92 W kg^(-1).展开更多
Epitaxially grown III-nitride alloys are tightly bonded materials with mixed covalent-ionic bonds.This tight bonding presents tremendous challenges in developing III-nitride membranes,even though semiconductor membran...Epitaxially grown III-nitride alloys are tightly bonded materials with mixed covalent-ionic bonds.This tight bonding presents tremendous challenges in developing III-nitride membranes,even though semiconductor membranes can provide numerous advantages by removing thick,inflexible,and costly substrates.Herein,cavities with various sizes were introduced by overgrowing target layers,such as undoped GaN and green LEDs,on nanoporous templates prepared by electrochemical etching of n-type GaN.The large primary interfacial toughness was effectively reduced according to the design of the cavity density,and the overgrown target layers were then conveniently exfoliated by engineering tensile-stressed Ni layers.The resulting III-nitride membranes maintained high crystal quality even after exfoliation due to the use of GaN-based nanoporous templates with the same lattice constant.The microcavity-assisted crack propagation process developed for the current III-nitride membranes forms a universal process for developing various kinds of large-scale and high-quality semiconductor membranes.展开更多
The development of high-performance organic solar cells(OSCs)with high operational stability is essential to accelerate their commercialization.Unfortunately,our understanding of the origin of instabilities in state-o...The development of high-performance organic solar cells(OSCs)with high operational stability is essential to accelerate their commercialization.Unfortunately,our understanding of the origin of instabilities in state-of-the-art OSCs based on bulk heterojunction(BHJ)featuring non-fullerene acceptors(NFAs)remains limited.Herein,we developed NFA-based OSCs using different charge extraction interlayer materials and studied their storage,thermal,and operational stabilities.Despite the high power conversion efficiency(PCE)of the OSCs(17.54%),we found that cells featuring self-assembled monolayers(SAMs)as hole-extraction interlayers exhibited poor stability.The time required for these OSCs to reach 80%of their initial performance(T_(80))was only 6h under continuous thermal stress at 85℃in a nitrogen atmosphere and 1 h under maximum power point tracking(MPPT)in a vacuum.Inserting MoO_(x)between ITO and SAM enhanced the T_(80)to 50 and~15 h after the thermal and operational stability tests,respectively,while maintaining a PCE of 16.9%.Replacing the organic PDINN electron transport layer with ZnO NPs further enhances the cells'thermal and operational stability,boosting the T_(80)to 1000 and 170 h,respectively.Our work reveals the synergistic roles of charge-selective interlayers and device architecture in developing efficient and stable OSCs.展开更多
The authors regret to inform that the first author should change to Yinao Su,and would like to add an author Haixia Huang to the author list.The correct order of the authors should be Yinao Su,Houliang Dai,Lichun Kuan...The authors regret to inform that the first author should change to Yinao Su,and would like to add an author Haixia Huang to the author list.The correct order of the authors should be Yinao Su,Houliang Dai,Lichun Kuang,Jizhen Liu,Dazhao Gu,Caineng Zou,and Haixia Huang.The authors would like to apologize for any inconvenience caused.展开更多
Diseases and disorders of the central nervous system often require significant interventions to restore lost function due to their com- plexity. Examples of such disorders include Parkinson＇s disease, Alzheimer＇s di...Diseases and disorders of the central nervous system often require significant interventions to restore lost function due to their com- plexity. Examples of such disorders include Parkinson＇s disease, Alzheimer＇s disease, multiple sclerosis, traumatic brain injury, and spinal cord in）ury. These diseases and disorders result trom healthy cells being destroyed, which in turn causes dysfunction in the cen- tral nervous system, The death of these cells can trigger a cascade of events that affect the rest of the body, causing symptoms that become progressively worse over time. Developing strategies for repairing the damage to the central nervous system remains chal- lenging, in part due to its inability to regenerate.展开更多
Human body with curved and soft interfaces requests advanced flexible materials and structures for the interaction with organs and signal collection from targets in applications such as bioengineering and diagnostic d...Human body with curved and soft interfaces requests advanced flexible materials and structures for the interaction with organs and signal collection from targets in applications such as bioengineering and diagnostic devices.Among them,it is highly demanded to achieve creative design in flexible materials and structures with great stretchable capability for required applications.To this end,both inorganic and organic materials could be adopted and designed with assembly and self-assembly methods for flexible electronics and electrodes.Soft or flexible materials and structures inspired by nature can lead to highly conformal contacts between devices and the human body.These approaches hold great potential for applications in flexible electronics,medical imaging technology and portable disease diagnostics.Novel strategy on related sensors/actuator and energy storage/generation devices could overcome certain limitations on flexible materials engineering and thus advance the field as well.All these methods would deliver a profound impact to our future intelligent society.展开更多
Aluminum formwork is a new type of formwork system. The construction application of aluminum formwork can improve the overall quality of concrete forming. Aluminum formwork plays a very important role in custom design...Aluminum formwork is a new type of formwork system. The construction application of aluminum formwork can improve the overall quality of concrete forming. Aluminum formwork plays a very important role in custom design, error measurement, solid assembly, construction acceptance, and concrete construction quality control. In the process of the construction technology needs to consider many aspects, a variety of scheme planning and design. This paper combines the aluminum mold house construction project for analysis and research, and chooses the actual engineering project as the research case, hoping to play a certain role in the control of the large interspersed construction technology.展开更多
To investigate the evolution of load-bearing characteristics of pre-stressed beams throughout their service life and to provide a basis for accurately assessing the actual working state of damaged pre-stressed concret...To investigate the evolution of load-bearing characteristics of pre-stressed beams throughout their service life and to provide a basis for accurately assessing the actual working state of damaged pre-stressed concrete T-beams,destructive tests were conducted on full-scale pre-stressed concrete beams.Based on the measurement and ana-lysis of beam deflection,strain,and crack development under various loading levels during the research tests,combined with the verification coefficient indicators specified in the codes,the verification coefficients of bridges at different stages of damage can be examined.The results indicate that the T-beams experience complete,incom-plete linear,and non-linear stages during the destructive test process.In the complete linear elastic stage,both the deflection and bottom strain verification coefficients comply with the specifications,indicating a good structural load-bearing capacity no longer adheres to the code’s requirements.In the non-linear stage,both coefficients exhi-bit a sharp increase,resulting in a further decrease in the structure’s load-bearing capacity.According to the pro-visions of the current code,the beam can be in the incomplete linear stage when both values fall within the code’s specified range.The strain verification coefficient sourced from the compression zone at the bottom of theflange is not recommended for assessing the bridge’s load-bearing capacity.展开更多
Because of actual requirement,shield machine always excavates with an inclined angle in longitudinal direction.Since many previous studies mainly focus on the face stability of the horizontal shield tunnel,the effects...Because of actual requirement,shield machine always excavates with an inclined angle in longitudinal direction.Since many previous studies mainly focus on the face stability of the horizontal shield tunnel,the effects of tensile strength cut-off and pore water pressure on the face stability of the longitudinally inclined shield tunnel are not well investigated.A failure mechanism of a longitudinally inclined shield tunnel face is constructed based on the spatial discretization technique and the tensile strength cut-off criterion is introduced to modify the constructed failure mechanism.The pore water pressure is introduced as an external force into the equation of virtual work and the objective function of the chamber pressure of the shield machine is obtained.Moreover,the critical chamber pressure of the longitudinally inclined shield tunnel is computed by optimal calculation.Parametric analysis indicates that both tensile strength cut-off and pore water pressure have a significant impact on the chamber pressure and the range of the collapse block.Finally,the theoretical results are compared with the numerical results calculated by FLAC3D software which proves that the proposed approach is effective.展开更多
1.Background Crop diseases diminish potential yields by over 20%annually worldwide[1],driving a century-long quest to understand and harness genetic resistance in plants.The genetic basis of disease resistance was fir...1.Background Crop diseases diminish potential yields by over 20%annually worldwide[1],driving a century-long quest to understand and harness genetic resistance in plants.The genetic basis of disease resistance was first recognized in the early 1900s,when Biffen(1905)demonstrated that resistance to stripe rust in wheat(Triticum aestivum)followed Mendelian rules of inheritance[2].This foundational insight was later expanded by Flor(1942),who formulated the“gene-for-gene”model describing the genetic interplay between host resistance(R)genes and pathogen avirulence(Avr)genes[3].展开更多
Currently, animal and clinical research on biomaterials, such as surgical sutures, are mainly performed by removing them from the experiment targets and observing them by microscopy. However, traditional microscopy is...Currently, animal and clinical research on biomaterials, such as surgical sutures, are mainly performed by removing them from the experiment targets and observing them by microscopy. However, traditional microscopy is not able to observe the internal structure, and there is a risk of sacrificing animals to remove the suture and damaging the materials. Therefore, we introduced optical coherence tomography (OCT) to observe and evaluate four different kinds of surgical sutures in vivo (monofilament absorbable and nonabsorbable sutures and braided absorbable and nonabsorbable sutures). As a result, while the monofilament nonabsorbable sutures showed almost no change over time, the absorbable sutures had color fading and it was also confirmed that the internal structure became chaotic due to decomposition, which improved the OCT signal intensity. For the braided sutures, both absorbable and nonabsorbable, we found that the reflection signal improved from week 0 because blood got among the filaments of sutures and dried during recovery which increased OCT signal from week 0 to week 1. We also confirmed that the braided sutures untwisted over time. All four kinds of sutures were pulled due to the movement of rats during recovery. It is expected that OCT technology will be of great help in in vivo experiments on biomaterials such as sutures.展开更多
As urban areas expand and water demand intensifies,the need for efficient and reliable water distribution systems becomes increasingly critical.A widely used infrastructure management approach involves partitioning wa...As urban areas expand and water demand intensifies,the need for efficient and reliable water distribution systems becomes increasingly critical.A widely used infrastructure management approach involves partitioning water distribution networks(WDNs)into district metered areas(DMAs).However,suboptimal designs of DMA partitioning can lead to inefficiencies and increased costs.This study presents a core-peripheryinformed approach for DMA design that explicitly utilises the natural division between a densely connected core and a sparsely connected periphery.Incorporating this structural framework enhances network resilience,improves water pressure stability,and optimises boundary device placement.The proposed core-periphery-informed DMA design integrates hydraulic and topological analyses to identify central and peripheral network areas,applies a community structure detection algorithm conditioned by these areas,and uses an optimisation model to determine the optimal placement of boundary devices,enhancing network resilience and reducing costs.When applied to the Modena WDN in Italy,this approach demonstrates improved pressure stability and significant cost reductions compared to traditional methods.Overall,the findings highlight the practical benefits of the core-periphery-based DMA design,offering a scalable and data-driven solution for urban water distribution systems.展开更多
Despite the rapid efficiency increase,tin halide perovskite solar cells are significantly behind their lead-based counterpart,with the highest reported efficiency of 15.38%.The main reason for this large difference is...Despite the rapid efficiency increase,tin halide perovskite solar cells are significantly behind their lead-based counterpart,with the highest reported efficiency of 15.38%.The main reason for this large difference is attributed to the instability of Sn^(2+),which easily oxidizes to Sn^(4+),creating Sn vacancies and increasing the open-circuit voltage loss.In this work,we implemented tin thiocyanate(Sn(SCN)_(2))as an additive for passivating the bulk defects of a germanium-doped tin halide perovskite film.Adding Sn^(2+)and SCN-ions reduces the Sn and iodine vacancies,limiting non-radiative recombination and favoring longer charge-carrier dynamics.Moreover,the addition of Sn(SCN)_(2) induces a higher film crystallinity and preferential orientation of the(l00)planes parallel to the substrate.The passivated devices showed improved photovoltaic parameters with the best open-circuit voltage of 0.716 V and the best efficiency of 12.22%,compared to 0.647 V and 10.2%for the reference device.In addition,the passivated solar cell retains 88.7%of its initial efficiency after 80 min of illumination under 100 mW cm^(-2) and is substantially better than the control device,which reaches 82.6%of its initial power conversion efficiency only after 30 min.This work demonstrates the passivation potential of tin-based additives,which combined with different counterions give a relatively large space of choices for passivation of Sn-based perovskites.展开更多
The deep seabed is known for its abundant reserves of various mineral resources.Notably,the Clarion Clipperton(C-C)mining area in the northeast Pacific Ocean,where China holds exploration rights,is particularly rich i...The deep seabed is known for its abundant reserves of various mineral resources.Notably,the Clarion Clipperton(C-C)mining area in the northeast Pacific Ocean,where China holds exploration rights,is particularly rich in deep-sea polymetallic nodules.These nodules,which are nodular and unevenly distributed in seafloor sediments,have significant industrial exploitation value.Over the decades,the deep-sea mining industry has increasingly adopted systems that combine rigid and flexible risers supported by large surface mining vessels.However,current systems face economic and structural stability challenges,hindering the development of deep-sea mining technology.This paper proposes a new structural design for a deep-sea mining system based on flexible risers,validated through numerical simulations and experimental research.The system composition,function and operational characteristics are comprehensively introduced.Detailed calculations determine the production capacity of the deep-sea mining system and the dimensions of the seabed mining subsystem.Finite element numerical simulations analyze the morphological changes of flexible risers and the stress conditions at key connection points under different ocean current incident angles.Experimental research verifies the feasibility of collaborative movement between two tethered underwater devices.The proposed deep-sea mining system,utilizing flexible risers,significantly advances the establishment of a commercial deep-sea mining system.The production calculations and parameter determinations provide essential references for the system’s future detailed design.Furthermore,the finite element simulation model established in this paper provides a research basis,and the method established in this paper offers a foundation for subsequent research under more complex ocean conditions.The control strategy for the collaborative movement between two tethered underwater devices provides an effective solution for deep-sea mining control systems.展开更多
Urban traffic prediction with high precision is always the unremitting pursuit of intelligent transportation systems and is instrumental in bringing smart cities into reality.The fundamental challenges for traffic pre...Urban traffic prediction with high precision is always the unremitting pursuit of intelligent transportation systems and is instrumental in bringing smart cities into reality.The fundamental challenges for traffic prediction lie in the accurate modelling of spatial and temporal traffic dynamics.Existing approaches mainly focus on modelling the traffic data itself,but do not explore the traffic correlations implicit in origin-destination(OD)data.In this paper,we propose STOD-Net,a dynamic spatial-temporal OD feature-enhanced deep network,to simultaneously predict the in-traffic and out-traffic for each and every region of a city.We model the OD data as dynamic graphs and adopt graph neural networks in STOD-Net to learn a low-dimensional representation for each region.As per the region feature,we design a gating mechanism and operate it on the traffic feature learning to explicitly capture spatial correlations.To further capture the complicated spatial and temporal dependencies among different regions,we propose a novel joint feature,learning block in STOD-Net and transfer the hybrid OD features to each block to make the learning process spatiotemporal-aware.We evaluate the effectiveness of STOD-Net on two benchmark datasets,and experimental results demonstrate that it outperforms the state-of-the-art by approximately 5%in terms of prediction accuracy and considerably improves prediction stability up to 80%in terms of standard deviation.展开更多
The freeze-thaw process is crucial for forming soil macropore structure to promote movement of water and salt downward by preferential flow in seasonally frozen regions.However,the freeze-thaw process of soil is hinde...The freeze-thaw process is crucial for forming soil macropore structure to promote movement of water and salt downward by preferential flow in seasonally frozen regions.However,the freeze-thaw process of soil is hindered by the snowpack,and the effects of the snowpack on the soil macropore structure and its implications on the formation of preferential flow are not well understood.This study collected soil samples from Da’an City,Northeast China,on July 15 and 16,2022,and conducted an indoor soil column snowpack-freeze-thaw tracing experiment on October 10 to 30,2022,to reveal the impact of snowpack and freeze-thaw cycles(FTC)on the forma-tion of preferential flow.The experiments were carried out with three levels of initial moisture content(IMC)of the soil column,the times of freeze-thaw cycles(T-FTC),and the snowpack thickness(SPT).Results show that increases in both IMC and SPT decreased the max infiltration depth(MID)of preferential flow.Greater T-FTC increased the MID and non-uniformity of the wet front trace and promoted the creation of preferential flow.The T-FTC and IMC both increased the overall variability of preferential flow,but this vari-ability decreased with greater SPT.The length index(LI)had the most significant impact on the preferential flow index(PFI)with an entropy weight of 0.2340,while the height difference of the multifractal spectrum(Δf(α))had the most negligible impact with a weight of 0.0753.Finally,results of redundancy analysis(RDA)and structural equation model(SEM)show that multifractal characteristic in-dicators have a much stronger ability to reflect the degree of preferential flow than developmental characteristic indicators.The T-FTC was the most important factor driving the formation of preferential flow in snowpack-freeze-thaw cycles.Therefore,conducting re-search on preferential flow in cold and arid regions is greatly significant for the utilization of regional water resources and the improve-ment of soil ecological environments.展开更多
基金This work is supported by NSFC(21773242,21935010)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB20000000)+1 种基金National Key Research and Development Program of China(2018YFA0208600)King Abdullah University of Science and Technology.J.Dong acknowledges financial support from Youth Innovation Promotion Association of Chinese Academy of Sciences(2018017).
文摘Reducing the dimensions of metallic nanoparticles to isolated,single atom has attracted considerable attention in heterogeneous catalysis,because it significantly improves atomic utilization and often leads to distinct catalytic performance.Through extensive research,it has been recognized that the local coordination environment of single atoms has an important influence on their electronic structures and catalytic behaviors.In this review,we summarize a series of representative systems of single-atom catalysts,discussing their preparation,characterization,and structure-property relationship,with an emphasis on the correlation between the coordination spheres of isolated reactive centers and their intrinsic catalytic activities.We also share our perspectives on the current challenges and future research promises in the development of single-atom catalysis.With this article,we aim to highlight the possibility of finely tuning the catalytic performances by engineering the coordination spheres of single-atom sites and provide new insights into the further development for this emerging research field.
基金supported by NIH R01 DE14190 and R21 DE22625 (HX)National Science Foundation of China 31100695 and 31328008 (LZ), 81401794 (PW)Maryland Stem Cell Research Fund and University of Maryland School of Dentistry
文摘Tissue engineering is promising to meet the increasing need for bone regeneration. Nanostructured calcium phosphate （CAP） biomaterials/scaffolds are of special interest as they share chemical/crystallographic similarities to inorganic components of bone. Three applications of nano-CaP are discussed in this review： nanostructured calcium phosphate cement （CPC）; nano-CaP composites; and nano-CaP coatings. The interactions between stem cells and nano-CaP are highlighted, including cell attachment, orientation/ morphology, differentiation and in vivo bone regeneration. Several trends can be seen： （i） nano-CaP biomaterials support stem cell attachment/proliferation and induce osteogenic differentiation, in some cases even without osteogenic supplements; （ii） the influence of nano-CaP surface patterns on cell alignment is not prominent due to non-uniform distribution of nano-crystals; （iii） nano-CaP can achieve better bone regeneration than conventional CaP biomaterials; （iv） combining stem cells with nano-CaP accelerates bone regeneration, the effect of which can be further enhanced by growth factors; and （v） cell microencapsulation in nano-CaP scaffolds is promising for bone tissue engineering. These understandings would help researchers to further uncover the underlying mechanisms and interactions in nano-CaP stem cell constructs in vitro and in vivo, tailor nano-CaP composite construct design and stem cell type selection to enhance cell function and bone regeneration, and translate laboratory findings to clinical treatments.
基金This research was jointly supported by the National Key R&D Program of China(2021YFC2800801)the Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(GML2019ZD0501)+3 种基金the Guangzhou Basic and Applied Basic Foundation(202102020611)the project of Guangzhou Marine Geological Survey of the China Geology Survey(DD20221700)the Key-Area Research and Development Program of Guangdong Province(2020B1111030003)the High-tech Ship Research Project of the Ministry of Industry and Information Technology(CJ05N20).
文摘Conductor and suction anchor are the key equipment providing bearing capacity in the field of deep-water drilling or offshore engineering,which have the advantages of high operation efficiency and short construction period.In order to drill a horizontal well in the shallow hydrate reservoir in the deep water,the suction anchor wellhead assembly is employed to undertake the main vertical bearing capacity in the second round of hydrate trial production project,so as to reduce the conductor running depth and heighten the kick-off point position.However,the deformation law of the deep-water suction anchor wellhead assembly under the moving load of the riser is not clear,and it is necessary to understand the lateral bearing characteristics to guide the design of its structural scheme.Based on 3D solid finite element method,the solid finite element model of the suction anchor wellhead assembly is established.In the model,the seabed soil is divided into seven layers,the contact between the wellhead assembly and the soil is simulated,and the vertical load and bending moment are applied to the wellhead node to simulate the riser movement when working in the deep water.The lateral bearing stability of conventional wellhead assembly and suction anchor wellhead assembly under the influence of wellhead load is discussed.The analysis results show that the bending moment is the main factor affecting the lateral deformation of the wellhead string;the anti-bending performance from increasing the outer conductor diameter is better than that from increasing the conductor wall thickness;for the subsea wellhead,the suction anchor obviously improves the lateral bearing capacity and reduces the lateral deformation.The conduct of the suction anchor wellhead assembly still needs to be lowered to a certain depth that below the maximum disturbed depth to ensure the lateral bearing stability,Thus,a method for the minimum conductor running depth for the suction anchor wellhead assembly is developed.The field implementations show that compared with the first round of hydrate trial production project,the conductor running depth is increased by 9.42 m,and there is no risk of wellhead overturning during the trial production.The method for determining the minimum conductor running depth in this paper is feasible and will still play an important role in the subsequent hydrate exploration and development.
文摘Novel bioengineering functional organoboron polymers were synthesized by 1) amidolysis of poly(acrcylic acid) (PAA) with 2-aminoethyldiphenyl borinate (2-AEPB), 2) esterification of organoboron PAA polymer (PAA-B) with a-hydroxy-methoxypoly(ethylene oxide) (PEO) as a compatibilizer and 3) conjugation of organoboron PEO branches (PAA-B-PEO) with folic acid (FA) as a targeting agent. Structure and composition of the synthesized polymers were characterized by FTIR-ATR and 1H (13C) NMR spectroscopy, chemical and physical analysis methods. Anti-tumor activity of organoboron functional polymer and its complex with FA (PAA-B-PEO-F) against cancer and normal cells were evaluated by using different biochemical methods such as cytotoxicity, statistical, apoptotic and necrotic cell indexes, double staining and caspase-3 immune staining, light and fluorescence inverted microscope analyses. It was found that citotoxicity and apoptotic/necrotic effects of polymers significantly depend on the structure and composition of studied polymers, and increase the following raw: PAA << PAA-B < PAA-B-PEO < PAA-B-PEO-F. Among them, PAA-B-PEO-F complex at 400 mg mL–1 concentration as a therapeutic drug exhibits minimal toxicity toward the nor-mal cells, but influential for HeLa cancer cells.
基金the financial support from the National Natural Science Foundation of China(22108044,22208061)the Research and Development Program in Key Fields of Guangdong Province(2020B1111380002)+1 种基金the Basic Research and Applicable Basic Research in Guangzhou City(202201010290)the financial support from the Guangdong Provincial Key Laboratory of Plant Resources Biorefinery(2021GDKLPRB07)。
文摘Amorphous carbons are promising anodes for high-rate potassium-ion batteries.Most low-temperature annealed amorphous carbons display unsatisfactory capacities.Heteroatom-induced defect engineering of amorphous carbons could enhance their reversible capacities.Nevertheless,most lignocellulose biomasses lack heteroatoms,making it a challenge to design highly heteroatom-doped carbons(>10 at%).Herein,we report a new preparation strategy for amorphous carbon anodes.Nitrogen/sulfur co-doped lignin-derived porous carbons(NSLPC)with ultra-high nitrogen doping levels(21.6 at%of N and 0.8 at%of S)from renewable lignin biomacromolecule precursors were prepared through a supramolecule-mediated pyrolysis strategy.This supermolecule/lignin composite decomposes forming a covalently bonded graphitic carbon/amorphous carbon intermediate product,which induces the formation of high heteroatom doping in the obtained NSLPC.This unique pyrolysis chemistry and high heteroatom doping of NSLPC enable abundant defective active sites for the adsorption of K+and improved kinetics.The NSLPC anode delivered a high reversible capacity of 419 mAh g^(-1)and superior cycling stability(capacity retention of 96.6%at 1 A g^(-1)for 1000 cycles).Potassiumion hybrid capacitors assembled by NSLPC anode exhibited excellent cycling stability(91%capacity retention for 2000 cycles)and a high energy density of 71 Wh kg^(-1)at a power density of 92 W kg^(-1).
基金The work was supported by King Abdullah University of Science and Technology(KAUST)baseline funding BAS/1/1614-01-01 and King Abdulaziz City for Science and Technology(Grant No.KACST TIC R2-FP-008)This work was also supported by Korea Photonics Technology Institute(Project No.193300029).
文摘Epitaxially grown III-nitride alloys are tightly bonded materials with mixed covalent-ionic bonds.This tight bonding presents tremendous challenges in developing III-nitride membranes,even though semiconductor membranes can provide numerous advantages by removing thick,inflexible,and costly substrates.Herein,cavities with various sizes were introduced by overgrowing target layers,such as undoped GaN and green LEDs,on nanoporous templates prepared by electrochemical etching of n-type GaN.The large primary interfacial toughness was effectively reduced according to the design of the cavity density,and the overgrown target layers were then conveniently exfoliated by engineering tensile-stressed Ni layers.The resulting III-nitride membranes maintained high crystal quality even after exfoliation due to the use of GaN-based nanoporous templates with the same lattice constant.The microcavity-assisted crack propagation process developed for the current III-nitride membranes forms a universal process for developing various kinds of large-scale and high-quality semiconductor membranes.
基金supported by the King Abdul ah University of Science and Technology(KAUST)office of Research Administration(ORA)under award No:OSR-CCF-3079 and OSR-2016-CRG5-3029the National Research Foundation of Korea(2019R1A6A1A11044070)
文摘The development of high-performance organic solar cells(OSCs)with high operational stability is essential to accelerate their commercialization.Unfortunately,our understanding of the origin of instabilities in state-of-the-art OSCs based on bulk heterojunction(BHJ)featuring non-fullerene acceptors(NFAs)remains limited.Herein,we developed NFA-based OSCs using different charge extraction interlayer materials and studied their storage,thermal,and operational stabilities.Despite the high power conversion efficiency(PCE)of the OSCs(17.54%),we found that cells featuring self-assembled monolayers(SAMs)as hole-extraction interlayers exhibited poor stability.The time required for these OSCs to reach 80%of their initial performance(T_(80))was only 6h under continuous thermal stress at 85℃in a nitrogen atmosphere and 1 h under maximum power point tracking(MPPT)in a vacuum.Inserting MoO_(x)between ITO and SAM enhanced the T_(80)to 50 and~15 h after the thermal and operational stability tests,respectively,while maintaining a PCE of 16.9%.Replacing the organic PDINN electron transport layer with ZnO NPs further enhances the cells'thermal and operational stability,boosting the T_(80)to 1000 and 170 h,respectively.Our work reveals the synergistic roles of charge-selective interlayers and device architecture in developing efficient and stable OSCs.
文摘The authors regret to inform that the first author should change to Yinao Su,and would like to add an author Haixia Huang to the author list.The correct order of the authors should be Yinao Su,Houliang Dai,Lichun Kuang,Jizhen Liu,Dazhao Gu,Caineng Zou,and Haixia Huang.The authors would like to apologize for any inconvenience caused.
基金supported by grants from the Canada Research Chairs programthe NSERC Engage and Engage Plus program
文摘Diseases and disorders of the central nervous system often require significant interventions to restore lost function due to their com- plexity. Examples of such disorders include Parkinson＇s disease, Alzheimer＇s disease, multiple sclerosis, traumatic brain injury, and spinal cord in）ury. These diseases and disorders result trom healthy cells being destroyed, which in turn causes dysfunction in the cen- tral nervous system, The death of these cells can trigger a cascade of events that affect the rest of the body, causing symptoms that become progressively worse over time. Developing strategies for repairing the damage to the central nervous system remains chal- lenging, in part due to its inability to regenerate.
文摘Human body with curved and soft interfaces requests advanced flexible materials and structures for the interaction with organs and signal collection from targets in applications such as bioengineering and diagnostic devices.Among them,it is highly demanded to achieve creative design in flexible materials and structures with great stretchable capability for required applications.To this end,both inorganic and organic materials could be adopted and designed with assembly and self-assembly methods for flexible electronics and electrodes.Soft or flexible materials and structures inspired by nature can lead to highly conformal contacts between devices and the human body.These approaches hold great potential for applications in flexible electronics,medical imaging technology and portable disease diagnostics.Novel strategy on related sensors/actuator and energy storage/generation devices could overcome certain limitations on flexible materials engineering and thus advance the field as well.All these methods would deliver a profound impact to our future intelligent society.
文摘Aluminum formwork is a new type of formwork system. The construction application of aluminum formwork can improve the overall quality of concrete forming. Aluminum formwork plays a very important role in custom design, error measurement, solid assembly, construction acceptance, and concrete construction quality control. In the process of the construction technology needs to consider many aspects, a variety of scheme planning and design. This paper combines the aluminum mold house construction project for analysis and research, and chooses the actual engineering project as the research case, hoping to play a certain role in the control of the large interspersed construction technology.
文摘To investigate the evolution of load-bearing characteristics of pre-stressed beams throughout their service life and to provide a basis for accurately assessing the actual working state of damaged pre-stressed concrete T-beams,destructive tests were conducted on full-scale pre-stressed concrete beams.Based on the measurement and ana-lysis of beam deflection,strain,and crack development under various loading levels during the research tests,combined with the verification coefficient indicators specified in the codes,the verification coefficients of bridges at different stages of damage can be examined.The results indicate that the T-beams experience complete,incom-plete linear,and non-linear stages during the destructive test process.In the complete linear elastic stage,both the deflection and bottom strain verification coefficients comply with the specifications,indicating a good structural load-bearing capacity no longer adheres to the code’s requirements.In the non-linear stage,both coefficients exhi-bit a sharp increase,resulting in a further decrease in the structure’s load-bearing capacity.According to the pro-visions of the current code,the beam can be in the incomplete linear stage when both values fall within the code’s specified range.The strain verification coefficient sourced from the compression zone at the bottom of theflange is not recommended for assessing the bridge’s load-bearing capacity.
基金Projects(52278395,52208409) supported by the National Natural Science Foundation of ChinaProject(2022JJ40531) supported by the Natural Science Foundation of Hunan Province,China。
文摘Because of actual requirement,shield machine always excavates with an inclined angle in longitudinal direction.Since many previous studies mainly focus on the face stability of the horizontal shield tunnel,the effects of tensile strength cut-off and pore water pressure on the face stability of the longitudinally inclined shield tunnel are not well investigated.A failure mechanism of a longitudinally inclined shield tunnel face is constructed based on the spatial discretization technique and the tensile strength cut-off criterion is introduced to modify the constructed failure mechanism.The pore water pressure is introduced as an external force into the equation of virtual work and the objective function of the chamber pressure of the shield machine is obtained.Moreover,the critical chamber pressure of the longitudinally inclined shield tunnel is computed by optimal calculation.Parametric analysis indicates that both tensile strength cut-off and pore water pressure have a significant impact on the chamber pressure and the range of the collapse block.Finally,the theoretical results are compared with the numerical results calculated by FLAC3D software which proves that the proposed approach is effective.
基金supported by the National Natural Science Foundation of China (U21A20224)the Key Research and Development Program of Ministry of Science and Technology of China(2023YFD1200402) to Zhiyong Liuby funding from King Abdullah University of Science and Technology to Brande B.H.Wulff
文摘1.Background Crop diseases diminish potential yields by over 20%annually worldwide[1],driving a century-long quest to understand and harness genetic resistance in plants.The genetic basis of disease resistance was first recognized in the early 1900s,when Biffen(1905)demonstrated that resistance to stripe rust in wheat(Triticum aestivum)followed Mendelian rules of inheritance[2].This foundational insight was later expanded by Flor(1942),who formulated the“gene-for-gene”model describing the genetic interplay between host resistance(R)genes and pathogen avirulence(Avr)genes[3].
文摘Currently, animal and clinical research on biomaterials, such as surgical sutures, are mainly performed by removing them from the experiment targets and observing them by microscopy. However, traditional microscopy is not able to observe the internal structure, and there is a risk of sacrificing animals to remove the suture and damaging the materials. Therefore, we introduced optical coherence tomography (OCT) to observe and evaluate four different kinds of surgical sutures in vivo (monofilament absorbable and nonabsorbable sutures and braided absorbable and nonabsorbable sutures). As a result, while the monofilament nonabsorbable sutures showed almost no change over time, the absorbable sutures had color fading and it was also confirmed that the internal structure became chaotic due to decomposition, which improved the OCT signal intensity. For the braided sutures, both absorbable and nonabsorbable, we found that the reflection signal improved from week 0 because blood got among the filaments of sutures and dried during recovery which increased OCT signal from week 0 to week 1. We also confirmed that the braided sutures untwisted over time. All four kinds of sutures were pulled due to the movement of rats during recovery. It is expected that OCT technology will be of great help in in vivo experiments on biomaterials such as sutures.
文摘As urban areas expand and water demand intensifies,the need for efficient and reliable water distribution systems becomes increasingly critical.A widely used infrastructure management approach involves partitioning water distribution networks(WDNs)into district metered areas(DMAs).However,suboptimal designs of DMA partitioning can lead to inefficiencies and increased costs.This study presents a core-peripheryinformed approach for DMA design that explicitly utilises the natural division between a densely connected core and a sparsely connected periphery.Incorporating this structural framework enhances network resilience,improves water pressure stability,and optimises boundary device placement.The proposed core-periphery-informed DMA design integrates hydraulic and topological analyses to identify central and peripheral network areas,applies a community structure detection algorithm conditioned by these areas,and uses an optimisation model to determine the optimal placement of boundary devices,enhancing network resilience and reducing costs.When applied to the Modena WDN in Italy,this approach demonstrates improved pressure stability and significant cost reductions compared to traditional methods.Overall,the findings highlight the practical benefits of the core-periphery-based DMA design,offering a scalable and data-driven solution for urban water distribution systems.
基金support from the Focus Group‘Next Generation Organic Photovoltaics’participating with the Dutch Institute for Fundamental Energy Research(DIFFER)(FOM130)Advanced Materials research program of the Zernike National Research Centre under the Bonus Incentive Scheme(BIS)of the Dutch Ministry for Education,Culture and Science.
文摘Despite the rapid efficiency increase,tin halide perovskite solar cells are significantly behind their lead-based counterpart,with the highest reported efficiency of 15.38%.The main reason for this large difference is attributed to the instability of Sn^(2+),which easily oxidizes to Sn^(4+),creating Sn vacancies and increasing the open-circuit voltage loss.In this work,we implemented tin thiocyanate(Sn(SCN)_(2))as an additive for passivating the bulk defects of a germanium-doped tin halide perovskite film.Adding Sn^(2+)and SCN-ions reduces the Sn and iodine vacancies,limiting non-radiative recombination and favoring longer charge-carrier dynamics.Moreover,the addition of Sn(SCN)_(2) induces a higher film crystallinity and preferential orientation of the(l00)planes parallel to the substrate.The passivated devices showed improved photovoltaic parameters with the best open-circuit voltage of 0.716 V and the best efficiency of 12.22%,compared to 0.647 V and 10.2%for the reference device.In addition,the passivated solar cell retains 88.7%of its initial efficiency after 80 min of illumination under 100 mW cm^(-2) and is substantially better than the control device,which reaches 82.6%of its initial power conversion efficiency only after 30 min.This work demonstrates the passivation potential of tin-based additives,which combined with different counterions give a relatively large space of choices for passivation of Sn-based perovskites.
基金Supported by Finance Science and Technology Project of Hainan Province under Grant No.ZDKJ2021027the National Natural Science Foundation of China under Grant No.52231012.
文摘The deep seabed is known for its abundant reserves of various mineral resources.Notably,the Clarion Clipperton(C-C)mining area in the northeast Pacific Ocean,where China holds exploration rights,is particularly rich in deep-sea polymetallic nodules.These nodules,which are nodular and unevenly distributed in seafloor sediments,have significant industrial exploitation value.Over the decades,the deep-sea mining industry has increasingly adopted systems that combine rigid and flexible risers supported by large surface mining vessels.However,current systems face economic and structural stability challenges,hindering the development of deep-sea mining technology.This paper proposes a new structural design for a deep-sea mining system based on flexible risers,validated through numerical simulations and experimental research.The system composition,function and operational characteristics are comprehensively introduced.Detailed calculations determine the production capacity of the deep-sea mining system and the dimensions of the seabed mining subsystem.Finite element numerical simulations analyze the morphological changes of flexible risers and the stress conditions at key connection points under different ocean current incident angles.Experimental research verifies the feasibility of collaborative movement between two tethered underwater devices.The proposed deep-sea mining system,utilizing flexible risers,significantly advances the establishment of a commercial deep-sea mining system.The production calculations and parameter determinations provide essential references for the system’s future detailed design.Furthermore,the finite element simulation model established in this paper provides a research basis,and the method established in this paper offers a foundation for subsequent research under more complex ocean conditions.The control strategy for the collaborative movement between two tethered underwater devices provides an effective solution for deep-sea mining control systems.
基金supported by the National Natural Science Foundation of China,Grant/Award Number:62401338by the Shandong Province Excellent Youth Science Fund Project(Overseas),Grant/Award Number:2024HWYQ-028by the Fundamental Research Funds of Shandong University.
文摘Urban traffic prediction with high precision is always the unremitting pursuit of intelligent transportation systems and is instrumental in bringing smart cities into reality.The fundamental challenges for traffic prediction lie in the accurate modelling of spatial and temporal traffic dynamics.Existing approaches mainly focus on modelling the traffic data itself,but do not explore the traffic correlations implicit in origin-destination(OD)data.In this paper,we propose STOD-Net,a dynamic spatial-temporal OD feature-enhanced deep network,to simultaneously predict the in-traffic and out-traffic for each and every region of a city.We model the OD data as dynamic graphs and adopt graph neural networks in STOD-Net to learn a low-dimensional representation for each region.As per the region feature,we design a gating mechanism and operate it on the traffic feature learning to explicitly capture spatial correlations.To further capture the complicated spatial and temporal dependencies among different regions,we propose a novel joint feature,learning block in STOD-Net and transfer the hybrid OD features to each block to make the learning process spatiotemporal-aware.We evaluate the effectiveness of STOD-Net on two benchmark datasets,and experimental results demonstrate that it outperforms the state-of-the-art by approximately 5%in terms of prediction accuracy and considerably improves prediction stability up to 80%in terms of standard deviation.
基金Under the auspices of the Natural Science Foundation of China(No.42272299)The Key Projects of Jilin Provincial Department of Science and Technology(No.20240203004NC)+1 种基金National Key Research and Development Program of China(No.2022YFD1500500)Graduate Innovation Fund of Jilin University(No.2024CX111)。
文摘The freeze-thaw process is crucial for forming soil macropore structure to promote movement of water and salt downward by preferential flow in seasonally frozen regions.However,the freeze-thaw process of soil is hindered by the snowpack,and the effects of the snowpack on the soil macropore structure and its implications on the formation of preferential flow are not well understood.This study collected soil samples from Da’an City,Northeast China,on July 15 and 16,2022,and conducted an indoor soil column snowpack-freeze-thaw tracing experiment on October 10 to 30,2022,to reveal the impact of snowpack and freeze-thaw cycles(FTC)on the forma-tion of preferential flow.The experiments were carried out with three levels of initial moisture content(IMC)of the soil column,the times of freeze-thaw cycles(T-FTC),and the snowpack thickness(SPT).Results show that increases in both IMC and SPT decreased the max infiltration depth(MID)of preferential flow.Greater T-FTC increased the MID and non-uniformity of the wet front trace and promoted the creation of preferential flow.The T-FTC and IMC both increased the overall variability of preferential flow,but this vari-ability decreased with greater SPT.The length index(LI)had the most significant impact on the preferential flow index(PFI)with an entropy weight of 0.2340,while the height difference of the multifractal spectrum(Δf(α))had the most negligible impact with a weight of 0.0753.Finally,results of redundancy analysis(RDA)and structural equation model(SEM)show that multifractal characteristic in-dicators have a much stronger ability to reflect the degree of preferential flow than developmental characteristic indicators.The T-FTC was the most important factor driving the formation of preferential flow in snowpack-freeze-thaw cycles.Therefore,conducting re-search on preferential flow in cold and arid regions is greatly significant for the utilization of regional water resources and the improve-ment of soil ecological environments.
