As a form of discrete representation learning,Vector Quantized Variational Autoencoders(VQ-VAE)have increasingly been applied to generative and multimodal tasks due to their ease of embedding and representative capaci...As a form of discrete representation learning,Vector Quantized Variational Autoencoders(VQ-VAE)have increasingly been applied to generative and multimodal tasks due to their ease of embedding and representative capacity.However,existing VQ-VAEs often perform quantization in the spatial domain,ignoring global structural information and potentially suffering from codebook collapse and information coupling issues.This paper proposes a frequency quantized variational autoencoder(FQ-VAE)to address these issues.The proposed method transforms image features into linear combinations in the frequency domain using a 2D fast Fourier transform(2D-FFT)and performs adaptive quantization on these frequency components to preserve image’s global relationships.The codebook is dynamically optimized to avoid collapse and information coupling issue by considering the usage frequency and dependency of code vectors.Furthermore,we introduce a post-processing module based on graph convolutional networks to further improve reconstruction quality.Experimental results on four public datasets demonstrate that the proposed method outperforms state-of-the-art approaches in terms of Structural Similarity Index(SSIM),Learned Perceptual Image Patch Similarity(LPIPS),and Reconstruction Fréchet Inception Distance(rFID).In the experiments on the CIFAR-10 dataset,compared to the baselinemethod VQ-VAE,the proposedmethod improves the abovemetrics by 4.9%,36.4%,and 52.8%,respectively.展开更多
Silicon nitride photonics has emerged as a promising integrated optical platform due to its broad transparency window,low optical loss,and mature fabrication technology.However,the inherent centrosymmetric crystal str...Silicon nitride photonics has emerged as a promising integrated optical platform due to its broad transparency window,low optical loss,and mature fabrication technology.However,the inherent centrosymmetric crystal structure of silicon nitride fundamentally restricts its applications in second-order nonlinear optical processes.Monolayer transition metal dichalcogenides,particularly tungsten disulfide(WS_(2)),exhibit strong second-order nonlinear responses,making them ideal candidates for nonlinear photonic applications.Herein,we demonstrate a heterogeneously integrated platform combining silicon nitride waveguides with chemical vapor deposition(CVD)-grown monolayer WS_(2),enabling second harmonic generation.A specially designed silica cladding featuring gentle-slope profile on silicon nitride strip waveguides facilitates the integration of centimeter-scale WS_(2)film with photonic circuits.This approach provides a robust solution for incorporating second-order nonlinearity into silicon nitride photonic systems.The demonstrated platform holds significant potential for advancing quantum networks,visible-light lasers,and integrated optical modulation/detection systems.展开更多
Piezocatalytic hydrogen peroxide(H_(2)O_(2))generation is a promising synthesis method that has received increasing attention;however,the reaction pathway requires further investigation.Here,Bi_(5)Ti_(3)FeO_(15)nanofi...Piezocatalytic hydrogen peroxide(H_(2)O_(2))generation is a promising synthesis method that has received increasing attention;however,the reaction pathway requires further investigation.Here,Bi_(5)Ti_(3)FeO_(15)nanofibers are used to generate H_(2)O_(2)by harvesting mechanical energy,and the reaction pathways are investigated.The H_(2)O_(2)yield over Bi_(5)Ti_(3)FeO_(15)nanofibers steadily increases from 331μmol g1 h1 in the first cycle to 746μmol g1 h1 in the tenth cycle in pure water without a sacrificial agent.Reliable reaction pathways are revealed by monitoring the pH value changes in the reaction solution during the H_(2)O_(2)generation process.In the H_(2)O_(2)generation process,the water oxidation reaction(WOR)provides a large amount of H+in the reaction solution,which promotes the oxygen reduction reaction(ORR)for H_(2)O_(2)generation.Therefore,an efficient synergistic effect between ORR and WOR achieves dual-pathway H_(2)O_(2)generation,contributing to the excellent piezocatalytic performance of Bi_(5)Ti_(3)FeO_(15)nanofibers.Furthermore,mechanistic studies indicate that the piezocatalytic H_(2)O_(2)generation follows the energy band theory.This work not only demonstrates Bi_(5)Ti_(3)FeO_(15)nanofibers as efficient piezocatalysts for H_(2)O_(2)generation but also provides a simple and effective approach to elucidate reaction pathways.This approach can be applied in photocatalytic,tribocatalytic,and electrocatalytic H_(2)O_(2)generation.展开更多
CO_(2)-to-formate electrosynthesis with high selectivity and stability has been a long-sought objective.Unfortunately,most catalysts undergo structural and valence state changes due to surface oxidation during operati...CO_(2)-to-formate electrosynthesis with high selectivity and stability has been a long-sought objective.Unfortunately,most catalysts undergo structural and valence state changes due to surface oxidation during operation or storage,resulting in decreased catalytic performance.Herein,we report a efficient and stable BiIn@Cu-foam electrode through the in-situ regeneration of Bi^(0) active sites to renew the surface activation.The electronic structure of Bi site can be regulated by introducing In,thereby enhancing the adsorption strength of*OCHO.The optimized electrode exhibits over 90%FE_(formate)at a wide potential window(-0.9–-2.2 V),and formation rate for 3.15 mM cm^(-1)h^(-1).Especially,the electrode can maintain the high performance at continuously electrolysis for more than 300 h,or for more than 50 cycles,even repeated operation and storage for more than 2 years.This work provides a promising candidate and new insight to construct industrially viable stable Bi-based catalyst for formate electrosynthesis.展开更多
The supercritical CO_(2) Brayton cycle is considered a promising energy conversion system for Generation IV reactors for its simple layout,compact structure,and high cycle efficiency.Mathematical models of four Brayto...The supercritical CO_(2) Brayton cycle is considered a promising energy conversion system for Generation IV reactors for its simple layout,compact structure,and high cycle efficiency.Mathematical models of four Brayton cycle layouts are developed in this study for different reactors to reduce the cost and increase the thermohydraulic performance of nuclear power generation to promote the commercialization of nuclear energy.Parametric analysis,multi-objective optimizations,and four decision-making methods are applied to obtain each Brayton scheme’s optimal thermohydraulic and economic indexes.Results show that for the same design thermal power scale of reactors,the higher the core’s exit temperature,the better the Brayton cycle’s thermo-economic performance.Among the four-cycle layouts,the recompression cycle(RC)has the best overall performance,followed by the simple recuperation cycle(SR)and the intercooling cycle(IC),and the worst is the reheating cycle(RH).However,RH has the lowest total cost of investment(C_(tot))of$1619.85 million,and IC has the lowest levelized cost of energy(LCOE)of 0.012$/(kWh).The nuclear Brayton cycle system’s overall performance has been improved due to optimization.The performance of the molten salt reactor combined with the intercooling cycle(MSR-IC)scheme has the greatest improvement,with the net output power(W_(net)),thermal efficiencyη_(t),and exergy efficiency(η_(e))improved by 8.58%,8.58%,and 11.21%,respectively.The performance of the lead-cooled fast reactor combined with the simple recuperation cycle scheme was optimized to increase C_(tot) by 27.78%.In comparison,the internal rate of return(IRR)increased by only 7.8%,which is not friendly to investors with limited funds.For the nuclear Brayton cycle,the molten salt reactor combined with the recompression cycle scheme should receive priority,and the gas-cooled fast reactor combined with the reheating cycle scheme should be considered carefully.展开更多
The industrial anthraquinone method for H_(2)O_(2)production has the serious flaws,such as high pollution and energy consumption.Piezocatalytic H2O2 evolution has been proven as a promising strategy,but its progress i...The industrial anthraquinone method for H_(2)O_(2)production has the serious flaws,such as high pollution and energy consumption.Piezocatalytic H2O2 evolution has been proven as a promising strategy,but its progress is hindered by unsatisfied energy conversion efficiency.Hence,we report the efficient piezocatalytic H_(2)O_(2)generation in pure water over oxygen vacancies mediated ultrathin Bi_(4)O_(5)Br_(2)nanosheets(~5 nm).Oxygen vacancies and thin nanostructure not only enhance the piezoelectric properties of Bi_(4)O_(5)Br_(2),but also advance the separation and transfer of piezoinduced charges.Moreover,density functional theory(DFT)calculations also prove that the introduction of oxygen vacancies enhances the O_(2)adsorption and activation ability with largely decreased Gibbs free energy of the reaction pathway.Profiting from these advantages,ultrathin Bi_(4)O_(5)Br_(2)nanosheets optimized by oxygen vacancies exhibit a prominent H_(2)O_(2)evolution rate of 620μmol g^-(1)h^(-1)in pure water and 2700μmol g^-(1)h^(-1)in sacrificial system,dominated by a two-step single electron reaction,which exceeds most of reported piezocatalysts.This work demonstrates that oxygen vacancies and ultrathin structure can synergistically enhance the piezocatalytic performance,which presents perspectives into exploring the strategies of defects and nanostructure fabrication for promoting piezocatalytic activity.展开更多
China possesses abundant heavy oil resources,yet faces challenges such as high viscosity,underdeveloped production technologies,and elevated development cost.Although the in-situ catalytic viscosity-reduction technolo...China possesses abundant heavy oil resources,yet faces challenges such as high viscosity,underdeveloped production technologies,and elevated development cost.Although the in-situ catalytic viscosity-reduction technology can address certain technical,environmental,and cost problems during the extraction process,the catalysts often suffer from poor stability and low catalytic efficiency.In this study,a green and simple room-temperature stirring method was employed to synthesize a class of highly efficient and stable 2D MOF catalysts,which possess the capability to conduct in-situ catalytic pyrolysis of heavy oil and reduce the viscosity.Under the condition of 160℃,a catalyst concentration of 0.5 wt%,and a hydrogen donor(tetralin)concentration of 2 wt%,the viscosity-reduction rate of Fe-MOF is as high as 89.09%,and it can decrease the asphaltene content by 8.42%.In addition,through the structural identification and analysis of crude oil asphaltenes,the causes for the high viscosity of heavy oil are explained at the molecular level.Through the analysis of catalytic products and molecular dynamics simulation,the catalytic mechanism is studied.It is discovered that Fe-MOF can interact with heavy oil macromolecules via coordination and pore-channel effects,facilitating their cracking and dispersal.Furthermore,synergistic interactions between Fe-MOF and the hydrogen donor facilitates hydrogenation reactions and enhances the viscosity-reducing effect.This study provides a novel strategy for boosting heavy oil recovery and underscores the potential of 2D MOFs in catalytic pyrolysis applications.展开更多
A novel mechanical stirring-assisted double-melt in-situ reaction casting process was developed to prepare Cu-1TiB2(wt%)composites.The effects of preparation parameters(melting reaction temperature,stirring rate and s...A novel mechanical stirring-assisted double-melt in-situ reaction casting process was developed to prepare Cu-1TiB2(wt%)composites.The effects of preparation parameters(melting reaction temperature,stirring rate and stirring time)on the microstructure and properties of Cu-1TiB2 composites were investigated.The melt viscosity and particle motion during stirring process were analyzed.The strong turbulence and shear effects generated by mechanical stirring in the melt not only significantly improve the particle distribution but also contribute to adequate in-situ reactions and precise control of the chemical composition.The optimal preparation parameters were 1200℃,a stirring rate of 100 r·min^(−1) and a stirring time of 1 min.Combined with the cold rolling process,the tensile strength,elongation and electrical conductivity of the composite reached 475 MPa,6.0%and 88.4%IACS,respectively,which were significantly better than the composite prepared by manual stirring.The good plasticity is attributed to the uniform distribution of TiB_(2) particles,effectively retarding the crack propagation.The dispersion of particles promotes heterogeneous nucleation of Cu matrix and inhibits grain growth.On the other hand,dispersed particles contribute to grain shear fracture and dislocation multiplication during cold deformation.Therefore,the composite achieves higher dislocation strengthening and grain boundary strengthening.展开更多
Halide perovskite-based heterojunctions have emerged as promising candidates for solar energy conversion and storage due to their unique photophysical properties.However,the current bottleneck lies in the insufficient...Halide perovskite-based heterojunctions have emerged as promising candidates for solar energy conversion and storage due to their unique photophysical properties.However,the current bottleneck lies in the insufficient separation of photogenerated carriers at the interface,primarily due to challenges in the controllable growth of perovskite on the substrate.Herein,we present a growth strategy for depositing lead-free Cs_(3)Sb_(2)Br_(9)perovskite nanocrystals onto the surface of Co_(3)O_(4)with the assistance of polyacrylic acid(PAA),generating a step-scheme(S-scheme)heterojunction denoted as Co_(3)O_(4)-Cs_(3)Sb_(2)Br_(9).The utilization of PAA as a template can effectively regulate the nucleation and growth of Cs_(3)Sb_(2)Br_(9),thereby significantly enhancing the charge separation efficiency of the Co_(3)O_(4)-Cs_(3)Sb_(2)Br_(9)heterojunction compared to its counterpart formed without PAA assistance.Under simulated solar light irradiation(100 mW·cm^(-2)),the cerium-doped Co_(3)O_(4)-Cs_(3)Sb_(2)Br_(9)heterojunction exhibits excellent photocatalytic CO_(2)reduction activity without the need for any sacrificial agent.Specifically,the CO yield reaches up to 700.7μmol·g^(-1)·h^(-1),marking a 2.8-fold increase over the sample synthesized without PAA mediation.This polymer-assisted in-situ growth strategy should open up a new avenue for designing and developing more efficient photocatalytic materials based on halide perovskites.展开更多
Selective reduction of N_(2)O by CO under excess O_(2) was effectively catalyzed by Fe(0.9 wt%)-exchangedβzeolite(Fe0.9β)in the temperature range of 250–500°C.Kinetic experiments showed that the apparent activ...Selective reduction of N_(2)O by CO under excess O_(2) was effectively catalyzed by Fe(0.9 wt%)-exchangedβzeolite(Fe0.9β)in the temperature range of 250–500°C.Kinetic experiments showed that the apparent activation energy for N_(2)O reduction with CO was lower than that for the direct N_(2)O decomposition,and the rate of N_(2)O reduction with CO at 300℃ was 16 times higher than that for direct N_(2)O decomposition.Reaction order analyses showed that CO and N_(2)O were involved in the kinetically important step,while O_(2) was not involved in the important step.At 300℃,the rate of CO oxidation with 0.1%N_(2)O was two times higher than that of CO oxidation with 10%O_(2).This quantitatively demonstrates the preferential oxidation of CO by N_(2)O under excess O_(2) over Fe0.9β.Operando/in-situ diffuse reflectance ultraviolet-visible spectroscopy showed a redox-based catalytic cycle;α-Fe-O species are reduced by CO to give CO_(2) and reduced Fe species,which are then re-oxidized by N_(2)O to regenerate theα-Fe-O species.The initial rate for the regeneration ofα-Fe-O species under 0.1%N_(2)O was four times higher than that under 10%O_(2).This result shows quantitative evidence on the higher reactivity of N_(2)O than O_(2) for the regeneration ofα-Fe-O intermediates,providing a fundamental reason why the Fe0.9βcatalyst selectively promotes the CO+N_(2)O reaction under excess O_(2) rather than the undesired side reaction of CO+O_(2).The mechanistic model was verified by the results of in-situ Fe K-edge X-ray absorption spectroscopy.展开更多
An idea hits us that in-situ synthesizing ceramic phase at intergranular regions of RE-Fe-B alloys should be beneficial to the performance of the materials against corrosion,and in this work a new nanoscale(Zr,Ti)B_(2...An idea hits us that in-situ synthesizing ceramic phase at intergranular regions of RE-Fe-B alloys should be beneficial to the performance of the materials against corrosion,and in this work a new nanoscale(Zr,Ti)B_(2)with space and point groups of P6/mmm and Fmmm,respectively,was successfully synthesized in NdCeFeB sintered magnets.The hcp-structured(Zr,Ti)B_(2)phases are present in a stripe-like shape.Some of(Zr,Ti)B_(2)are developed at interfaces,and the others exist inside grain boundary phase.They coexist with REFe_(2)and RE-rich phases at intergranular regions.When proximity to RE2Fe14B grains,their orientation relationships obey[001]_(Nd_(2)Fe_(14)B)‖[110](Zr,Ti)B_(2).The formation of(Zr,Ti)B_(2)generates significant local compressive stress,being 8.48 GPa,and plenty of reliefs are developed inside the RE2Fe14B grains.The in-situ formed(Zr,Ti)B_(2)modifies the magnet microstructure,lessens the favorable sites for absorption reaction,narrows reaction channels,and reduces the potential difference between intergranular phase and main phase.Such favorable factors greatly enhance the corrosion resistance with an icorrdecrement by 70%in comparison to the unmodified magnet.These new discoveries are thought to be able to provide an insight into the method of potentially improving properties of magnets.展开更多
In-situ TiB_(2)/Al–Cu composite was processed by multidirectional forging(MDF)for six passes.The microstructure evolution of the forged workpiece was examined across various regions.The mechanical properties of the a...In-situ TiB_(2)/Al–Cu composite was processed by multidirectional forging(MDF)for six passes.The microstructure evolution of the forged workpiece was examined across various regions.The mechanical properties of the as-cast and MDFed composites were compared,and their strengthening mechanisms were analyzed.Results indicate that the grain refinement achieved through the MDF process is mainly due to the subdivision of the original grains through mechanical geometric fragmentation and the occurrence of dynamic recrystallization(DRX).DRX grains are formed through discontinuous DRX,continuous DRX,and recrystallization induced by particle-stimulated nucleation.A rise in accumulated equivalent strain(Σ?ε)results in finerα-Al grains and a more uniform distribution of TiB_(2)particles,which enhance the Vickers hardness of the composite.In addition,the tensile properties of the MDFed composite significantly improve compared with those of the as-cast composites,with ultimate tensile strength and yield strength increasing by 51.2%and 54%,respectively.This enhancement is primarily due to grain refinement strengthening and dislocation strengthening achieved by the MDF process.展开更多
Cr_(2)AlC,a representative MAX phase,gains increasing attention for the excellent oxidation tolerance and corrosion resistance used in harsh high temperature and strong radiation environments.However,the lack of the p...Cr_(2)AlC,a representative MAX phase,gains increasing attention for the excellent oxidation tolerance and corrosion resistance used in harsh high temperature and strong radiation environments.However,the lack of the phase formation mechanism has become the key bottleneck to the practical applications for Cr_(2)AlC synthesis with high purity at low temperatures.In this work,we fabricated the amorphous Cr-Al-C coating by a hybrid magnetron sputtering/cathodic arc deposition technique,in which the in-situ heating transmission electron microscopy(TEM)was conducted in a temperature range of 25-650℃ to address the real-time phase transformation for Cr_(2)AlC coating.The results demonstrated that increas-ing the temperature from 25 to 370℃ led to the structural transformation from amorphous Cr-Al-C to the crystalline Cr_(2)Al interphases.However,the high-purity Cr_(2)AlC MAX phase was distinctly formed at 500℃,accompanied by the diminished amorphous feature.With the further increase of temperature to 650℃,the decomposition of Cr_(2)AlC to Cr_(7)C_(3)impurities was observed.Similar phase evolution was also evidenced by the Ab-initio molecular dynamics calculations,where the bond energy of Cr-Cr,Cr-Al,and Cr-C played the key role in the formed crystalline stability during the heating process.The observa-tions not only provide fundamental insight into the phase formation mechanism for high-purity Cr_(2)AlC coatings but also offer a promising strategy to manipulate the advanced MAX phase materials with high tolerance to high-temperature oxidation and heavy ion radiations.展开更多
To convert carbon dioxide into high-value-added liquid products such as formate with renewable electricity(CO_(2)RR)is a promising strategy of CO_(2) resource utilization.The key is to find a highly efficient and sele...To convert carbon dioxide into high-value-added liquid products such as formate with renewable electricity(CO_(2)RR)is a promising strategy of CO_(2) resource utilization.The key is to find a highly efficient and selective electrocatalyst for CO_(2)RR.Herein,clustered Bi_(28)O_(32)(SO_(4))_(10) was found to show a high formate Faradaic efficiency(FE_(formate))of 96.2%at–1.1 V_(RHE) and FE_(formate) above 90%in a wide potential range from–0.9 to–1.3 V_(RHE) in H-type cell,surpassing the corresponding layered Bi_(2)O_(2)SO_(4)(85.6%FE_(formate) at–1.1 V_(RHE)).The advantageous CO_(2)RR performance of Bi_(28)O_(32)(SO_(4))_(10) over Bi_(2)O_(2)SO_(4) was ascribed to a special two-step in-situ reconstruction process,consisting of Bi_(28)O_(32)(SO_(4))_(10)→Bi_(-2.1)/Bi_(2)O_(2)CO_(3)→Bi_(-2.1)/Bi_(-0.6) during CO_(2)RR.It gave metallic Bi_(-2.1) with lattice distortion of–2.1%at the first step and metallic Bi_(-0.6) with lattice distortion of–0.6%at the second step.In contrast,the usual layered Bi_(2)O_(2)SO_(4) only formed metallic Bi_(-0.6) with weaker lattice strain.The metallic Bi_(-2.1) revealed higher efficiency in stabilizing*CO_(2) intermediate and reducing the energy barrier of CO_(2)RR,while suppressing hydrogen evolution reaction and CO formation.This work delivers a high-performance cluster-type Bi_(28)O_(32)(SO_(4))_(10) electrocatalyst for CO_(2)RR,and elucidates the origin of superior performance of clustered Bi_(28)O_(32)(SO_(4))_(10) electrocatalysts compared with layered Bi_(2)O_(2)SO_(4).展开更多
Application of transition metal boride(TMB) catalysts towards hydrolysis of NaBH_(4) holds great significance to help relieve the energy crisis. Herein, we present a facile and versatile metal-organic framework(MOF) a...Application of transition metal boride(TMB) catalysts towards hydrolysis of NaBH_(4) holds great significance to help relieve the energy crisis. Herein, we present a facile and versatile metal-organic framework(MOF) assisted strategy to prepare Co_(2)B-CoPO_x with massive boron vacancies by introducing phytic acid(PA) cross-linked Co complexes that are acquired from reaction of PA and ZIF-67 into cobalt boride. The PA etching effectively breaks down the structure of ZIF-67 to create more vacancies, favoring the maximal exposure of active sites and elevation of catalytic activity. Experimental results demonstrate a drastic electronic interaction between Co and the dopant phosphorous(P), thereby the robustly electronegative P induces electron redistribution around the metal species, which facilitates the dissociation of B-H bond and the adsorption of H_(2)O molecules. The vacancy-rich Co_(2)B-CoPO_x catalyst exhibits scalable performance, characterized by a high hydrogen generation rate(HGR) of 7716.7 m L min^(-1)g^(-1) and a low activation energy(Ea) of 44.9 k J/mol, rivaling state-of-the-art catalysts. This work provides valuable insights for the development of advanced catalysts through P doping and boron vacancy engineering and the design of efficient and sustainable energy conversion systems.展开更多
Green hydrogen is urgently required for sustainable development of human beings and rational construction of heterostructures holds great promising for photocatalytic hydrogen generation.Herein,2D/2D WSe_(2)/ZnIn_(2)S...Green hydrogen is urgently required for sustainable development of human beings and rational construction of heterostructures holds great promising for photocatalytic hydrogen generation.Herein,2D/2D WSe_(2)/ZnIn_(2)S_(4) heterostructures with strong hetero-interface interaction and abundant contact were constructed via an impregnation-annealing strategy.Efficient charge transfer from ZnIn_(2)S_(4) to WSe_(2)was evidenced by transient absorption spectroscopy in crafted heterostructures owing to the tight and2D face-to-face contact.As a result,the prepared WSe_(2)/ZnIn_(2)S_(4) heterostructures exhibited boosted photocatalytic performance and a highest hydrogen evolution rate of 3.377 mmol/(g h)was achieved with an apparent quantum yield of 45.7%at 420 nm.The work not only provides new strategies to achieve efficient 2D/2D heterostructures but also paves the way for the development of green hydrogen in the future.展开更多
With the expansion of the Internet market,the traditional software development method has been difficult to meet the market demand due to the problems of long development cycle,tedious work,and difficult system mainte...With the expansion of the Internet market,the traditional software development method has been difficult to meet the market demand due to the problems of long development cycle,tedious work,and difficult system maintenance.Therefore,to improve software development efficiency,this study uses residual networks and bidirectional long short-term memory(BLSTM)networks to improve the Pix2code model.The experiment results show that after improving the visual module of the Pix2code model using residual networks,the accuracy of the training set improves from 0.92 to 0.96,and the convergence time is shortened from 3 hours to 2 hours.After using a BLSTM network to improve the language module and decoding layer,the accuracy and convergence speed of the model have also been improved.The accuracy of the training set grew from 0.88 to 0.92,and the convergence time was shortened by 0.5 hours.However,models improved by BLSTM networks might exhibit overfitting,and thus this study uses Dropout and Xavier normal distribution to improve the memory network.The results validate that the training set accuracy of the optimized BLSTM network remains around 0.92,but the accuracy of the test set has improved to a maximum of 85%.Dropout and Xavier normal distributions can effectively improve the overfitting problem of BLSTM networks.Although they can also decrease the model’s stability,their gain is higher.The training and testing accuracy of the Pix2code improved by residual network and BLSTM network are 0.95 and 0.82,respectively,while the code generation accuracy of the original Pix2code is only 0.77.The above data indicate that the improved Pix2code model has improved the accuracy and stability of code automatic generation.展开更多
In this work,the gold nanoparticles（Au-NPs）were in-situ generated on the surface of MnO2nanosheets to form MnO2/Au-NPs nanocomposite in a simple and cost-effective way.Multiple experiments were carried out to optimi...In this work,the gold nanoparticles（Au-NPs）were in-situ generated on the surface of MnO2nanosheets to form MnO2/Au-NPs nanocomposite in a simple and cost-effective way.Multiple experiments were carried out to optimize the oxidation of basic dye（Methylene Blue（MB））,including the molar ratio of MnO2to chloroauric acid（HAu Cl4）,the p H of the solution and the effect of initial material.Under the optimal condition,the highest degradation efficiency for MB achieved to 98.9%within 60 min,which was obviously better than commercial MnO2powders（4.3%）and MnO2nanosheets（74.2%）.The enhanced oxidative degradation might attribute to the in-situ generation of ultra-small and highly-dispersed Au-NPs which enlarged the synergistic effect and/or interfacial effect between MnO2nanosheets and Au-NPs and facilitated the uptake of electrons by MnO2from MB during the oxidation,thus validating the application of MnO2/Au-NPs nanocomposite for direct removal of organic dyes from wastewater in a simple and convenient fashion.展开更多
The growth, development and consumption of successive three generations of cotton bollworm, Helicoverpa armigera （Htibner）, fed on cotton bolls grown under elevated CO2 （double-ambient vs. ambient） in open-top cha...The growth, development and consumption of successive three generations of cotton bollworm, Helicoverpa armigera （Htibner）, fed on cotton bolls grown under elevated CO2 （double-ambient vs. ambient） in open-top chambers were examined. Significant decreases in protein, total amino acid, water and nitrogen content and increases in free fatty acid were observed in cotton bolls. Changes in quality of cotton bolls affected the growth, development and food utilization of H. armigera. Significantly longer larval development duration in three successive generations and lower pupal weight of the second and third generations were observed in cotton bollworm fed on cotton bolls grown under elevated CO2. Significantly lower fecundity was also found in successive three generations of H. armigera fed on cotton bolls grown under elevated CO2. The consumption per larva occurred significant increase in successive three generations and frass per larva were also significantly increased during the second and third generations under elevated CO2. Significantly lower relative growth rate, efficiency of conversion of ingested food and significant higher relative consumption rate in successive three generations were observed in cotton bollworm fed on cotton bolls grown under elevated CO2. Significantly lower potential female fecundity, larval numbers and population consumption were found in the second and third generations of cotton bollworm fed on cotton bolls grown under elevated CO2. The integrative effect of higher larval mortality rate and lower adult fecundity resulted in significant decreases in potential population consumption in the latter two generations. The results show that elevated CO2 adversely affects cotton bolls quality, which indicates the potential population dynamics and potential population consumption of cotton bollworm will alleviate the harm to the plants in the future rising CO2 atmosphere.展开更多
The existence and risk of emerging organic contaminants(EOCs)have been under consideration and paid much effort to degrade these pollutants.Fenton system is one of the most widely used technologies to solve this probl...The existence and risk of emerging organic contaminants(EOCs)have been under consideration and paid much effort to degrade these pollutants.Fenton system is one of the most widely used technologies to solve this problem.The original Fenton system relies on the hydroxyl radicals produced by Fe(Ⅱ)/H_(2)O_(2) to oxidize the organic contaminants.However,the application of the Fenton system is limited by its low iron cycling efficiency and the high risks of hydrogen peroxide transportation and storage.The introduction of external energy(including light and electricity etc.)can effectively promote the Fe(Ⅲ)/Fe(Ⅱ)cycle and the reduction of oxygen to produce hydrogen peroxide in situ.This review introduces three in-situ Fenton systems,which are electro-Fenton,Photo-Fenton,and chemical reaction.The mechanism,influencing factors,and catalysts of these three in-situ Fenton systems in degrading EOCs are discussed systematically.This review strengthens the understanding of Fenton and in-situ Fenton systems in degradation,offering further insight into the real application of the in-situ Fenton system in the removal of EOCs.展开更多
基金supported by the Interdisciplinary project of Dalian University DLUXK-2023-ZD-001.
文摘As a form of discrete representation learning,Vector Quantized Variational Autoencoders(VQ-VAE)have increasingly been applied to generative and multimodal tasks due to their ease of embedding and representative capacity.However,existing VQ-VAEs often perform quantization in the spatial domain,ignoring global structural information and potentially suffering from codebook collapse and information coupling issues.This paper proposes a frequency quantized variational autoencoder(FQ-VAE)to address these issues.The proposed method transforms image features into linear combinations in the frequency domain using a 2D fast Fourier transform(2D-FFT)and performs adaptive quantization on these frequency components to preserve image’s global relationships.The codebook is dynamically optimized to avoid collapse and information coupling issue by considering the usage frequency and dependency of code vectors.Furthermore,we introduce a post-processing module based on graph convolutional networks to further improve reconstruction quality.Experimental results on four public datasets demonstrate that the proposed method outperforms state-of-the-art approaches in terms of Structural Similarity Index(SSIM),Learned Perceptual Image Patch Similarity(LPIPS),and Reconstruction Fréchet Inception Distance(rFID).In the experiments on the CIFAR-10 dataset,compared to the baselinemethod VQ-VAE,the proposedmethod improves the abovemetrics by 4.9%,36.4%,and 52.8%,respectively.
基金Project supported by the National Innovative Training Program for College Students of China(Grant No.2023069)the University Research and Innovation Project of the National University of Defense Technology。
文摘Silicon nitride photonics has emerged as a promising integrated optical platform due to its broad transparency window,low optical loss,and mature fabrication technology.However,the inherent centrosymmetric crystal structure of silicon nitride fundamentally restricts its applications in second-order nonlinear optical processes.Monolayer transition metal dichalcogenides,particularly tungsten disulfide(WS_(2)),exhibit strong second-order nonlinear responses,making them ideal candidates for nonlinear photonic applications.Herein,we demonstrate a heterogeneously integrated platform combining silicon nitride waveguides with chemical vapor deposition(CVD)-grown monolayer WS_(2),enabling second harmonic generation.A specially designed silica cladding featuring gentle-slope profile on silicon nitride strip waveguides facilitates the integration of centimeter-scale WS_(2)film with photonic circuits.This approach provides a robust solution for incorporating second-order nonlinearity into silicon nitride photonic systems.The demonstrated platform holds significant potential for advancing quantum networks,visible-light lasers,and integrated optical modulation/detection systems.
文摘Piezocatalytic hydrogen peroxide(H_(2)O_(2))generation is a promising synthesis method that has received increasing attention;however,the reaction pathway requires further investigation.Here,Bi_(5)Ti_(3)FeO_(15)nanofibers are used to generate H_(2)O_(2)by harvesting mechanical energy,and the reaction pathways are investigated.The H_(2)O_(2)yield over Bi_(5)Ti_(3)FeO_(15)nanofibers steadily increases from 331μmol g1 h1 in the first cycle to 746μmol g1 h1 in the tenth cycle in pure water without a sacrificial agent.Reliable reaction pathways are revealed by monitoring the pH value changes in the reaction solution during the H_(2)O_(2)generation process.In the H_(2)O_(2)generation process,the water oxidation reaction(WOR)provides a large amount of H+in the reaction solution,which promotes the oxygen reduction reaction(ORR)for H_(2)O_(2)generation.Therefore,an efficient synergistic effect between ORR and WOR achieves dual-pathway H_(2)O_(2)generation,contributing to the excellent piezocatalytic performance of Bi_(5)Ti_(3)FeO_(15)nanofibers.Furthermore,mechanistic studies indicate that the piezocatalytic H_(2)O_(2)generation follows the energy band theory.This work not only demonstrates Bi_(5)Ti_(3)FeO_(15)nanofibers as efficient piezocatalysts for H_(2)O_(2)generation but also provides a simple and effective approach to elucidate reaction pathways.This approach can be applied in photocatalytic,tribocatalytic,and electrocatalytic H_(2)O_(2)generation.
基金supported by the National Natural Science Foundation of China(22238013 and 22178393)Postdoctoral Science Foundation of Central South University(320808)+1 种基金Natural Science Foundation of Hunan Province(2023JJ40706)the High Performance Computing Center of Central South University。
文摘CO_(2)-to-formate electrosynthesis with high selectivity and stability has been a long-sought objective.Unfortunately,most catalysts undergo structural and valence state changes due to surface oxidation during operation or storage,resulting in decreased catalytic performance.Herein,we report a efficient and stable BiIn@Cu-foam electrode through the in-situ regeneration of Bi^(0) active sites to renew the surface activation.The electronic structure of Bi site can be regulated by introducing In,thereby enhancing the adsorption strength of*OCHO.The optimized electrode exhibits over 90%FE_(formate)at a wide potential window(-0.9–-2.2 V),and formation rate for 3.15 mM cm^(-1)h^(-1).Especially,the electrode can maintain the high performance at continuously electrolysis for more than 300 h,or for more than 50 cycles,even repeated operation and storage for more than 2 years.This work provides a promising candidate and new insight to construct industrially viable stable Bi-based catalyst for formate electrosynthesis.
基金This work was supported of National Natural Science Foundation of China Fund(No.52306033)State Key Laboratory of Engines Fund(No.SKLE-K2022-07)the Jiangxi Provincial Postgraduate Innovation Special Fund(No.YC2022-s513).
文摘The supercritical CO_(2) Brayton cycle is considered a promising energy conversion system for Generation IV reactors for its simple layout,compact structure,and high cycle efficiency.Mathematical models of four Brayton cycle layouts are developed in this study for different reactors to reduce the cost and increase the thermohydraulic performance of nuclear power generation to promote the commercialization of nuclear energy.Parametric analysis,multi-objective optimizations,and four decision-making methods are applied to obtain each Brayton scheme’s optimal thermohydraulic and economic indexes.Results show that for the same design thermal power scale of reactors,the higher the core’s exit temperature,the better the Brayton cycle’s thermo-economic performance.Among the four-cycle layouts,the recompression cycle(RC)has the best overall performance,followed by the simple recuperation cycle(SR)and the intercooling cycle(IC),and the worst is the reheating cycle(RH).However,RH has the lowest total cost of investment(C_(tot))of$1619.85 million,and IC has the lowest levelized cost of energy(LCOE)of 0.012$/(kWh).The nuclear Brayton cycle system’s overall performance has been improved due to optimization.The performance of the molten salt reactor combined with the intercooling cycle(MSR-IC)scheme has the greatest improvement,with the net output power(W_(net)),thermal efficiencyη_(t),and exergy efficiency(η_(e))improved by 8.58%,8.58%,and 11.21%,respectively.The performance of the lead-cooled fast reactor combined with the simple recuperation cycle scheme was optimized to increase C_(tot) by 27.78%.In comparison,the internal rate of return(IRR)increased by only 7.8%,which is not friendly to investors with limited funds.For the nuclear Brayton cycle,the molten salt reactor combined with the recompression cycle scheme should receive priority,and the gas-cooled fast reactor combined with the reheating cycle scheme should be considered carefully.
文摘The industrial anthraquinone method for H_(2)O_(2)production has the serious flaws,such as high pollution and energy consumption.Piezocatalytic H2O2 evolution has been proven as a promising strategy,but its progress is hindered by unsatisfied energy conversion efficiency.Hence,we report the efficient piezocatalytic H_(2)O_(2)generation in pure water over oxygen vacancies mediated ultrathin Bi_(4)O_(5)Br_(2)nanosheets(~5 nm).Oxygen vacancies and thin nanostructure not only enhance the piezoelectric properties of Bi_(4)O_(5)Br_(2),but also advance the separation and transfer of piezoinduced charges.Moreover,density functional theory(DFT)calculations also prove that the introduction of oxygen vacancies enhances the O_(2)adsorption and activation ability with largely decreased Gibbs free energy of the reaction pathway.Profiting from these advantages,ultrathin Bi_(4)O_(5)Br_(2)nanosheets optimized by oxygen vacancies exhibit a prominent H_(2)O_(2)evolution rate of 620μmol g^-(1)h^(-1)in pure water and 2700μmol g^-(1)h^(-1)in sacrificial system,dominated by a two-step single electron reaction,which exceeds most of reported piezocatalysts.This work demonstrates that oxygen vacancies and ultrathin structure can synergistically enhance the piezocatalytic performance,which presents perspectives into exploring the strategies of defects and nanostructure fabrication for promoting piezocatalytic activity.
基金supported by the National Natural Science Foundation of China(52174047)Sinopec Project(No.P23138).
文摘China possesses abundant heavy oil resources,yet faces challenges such as high viscosity,underdeveloped production technologies,and elevated development cost.Although the in-situ catalytic viscosity-reduction technology can address certain technical,environmental,and cost problems during the extraction process,the catalysts often suffer from poor stability and low catalytic efficiency.In this study,a green and simple room-temperature stirring method was employed to synthesize a class of highly efficient and stable 2D MOF catalysts,which possess the capability to conduct in-situ catalytic pyrolysis of heavy oil and reduce the viscosity.Under the condition of 160℃,a catalyst concentration of 0.5 wt%,and a hydrogen donor(tetralin)concentration of 2 wt%,the viscosity-reduction rate of Fe-MOF is as high as 89.09%,and it can decrease the asphaltene content by 8.42%.In addition,through the structural identification and analysis of crude oil asphaltenes,the causes for the high viscosity of heavy oil are explained at the molecular level.Through the analysis of catalytic products and molecular dynamics simulation,the catalytic mechanism is studied.It is discovered that Fe-MOF can interact with heavy oil macromolecules via coordination and pore-channel effects,facilitating their cracking and dispersal.Furthermore,synergistic interactions between Fe-MOF and the hydrogen donor facilitates hydrogenation reactions and enhances the viscosity-reducing effect.This study provides a novel strategy for boosting heavy oil recovery and underscores the potential of 2D MOFs in catalytic pyrolysis applications.
基金supported by the National Natural Science Foundation of China(Nos.U2202255 and 52371038)the Science and Technology Innovation Program of Hunan Province(No.2023RC1019).
文摘A novel mechanical stirring-assisted double-melt in-situ reaction casting process was developed to prepare Cu-1TiB2(wt%)composites.The effects of preparation parameters(melting reaction temperature,stirring rate and stirring time)on the microstructure and properties of Cu-1TiB2 composites were investigated.The melt viscosity and particle motion during stirring process were analyzed.The strong turbulence and shear effects generated by mechanical stirring in the melt not only significantly improve the particle distribution but also contribute to adequate in-situ reactions and precise control of the chemical composition.The optimal preparation parameters were 1200℃,a stirring rate of 100 r·min^(−1) and a stirring time of 1 min.Combined with the cold rolling process,the tensile strength,elongation and electrical conductivity of the composite reached 475 MPa,6.0%and 88.4%IACS,respectively,which were significantly better than the composite prepared by manual stirring.The good plasticity is attributed to the uniform distribution of TiB_(2) particles,effectively retarding the crack propagation.The dispersion of particles promotes heterogeneous nucleation of Cu matrix and inhibits grain growth.On the other hand,dispersed particles contribute to grain shear fracture and dislocation multiplication during cold deformation.Therefore,the composite achieves higher dislocation strengthening and grain boundary strengthening.
基金supported by the National Key R&D Program of China(No.2022YFA1502902)the National Natural Science Foundation of China(Nos.U21A20286 and 22475152)+2 种基金the Natural Science Foundation of Tianjin City(No.17JCJQJC43800)the Programme of Introducing Talents of Discipline to Universities(111 Project)Tianjin Research Innovation Project for Postgraduate Students(No.2022BKY156).
文摘Halide perovskite-based heterojunctions have emerged as promising candidates for solar energy conversion and storage due to their unique photophysical properties.However,the current bottleneck lies in the insufficient separation of photogenerated carriers at the interface,primarily due to challenges in the controllable growth of perovskite on the substrate.Herein,we present a growth strategy for depositing lead-free Cs_(3)Sb_(2)Br_(9)perovskite nanocrystals onto the surface of Co_(3)O_(4)with the assistance of polyacrylic acid(PAA),generating a step-scheme(S-scheme)heterojunction denoted as Co_(3)O_(4)-Cs_(3)Sb_(2)Br_(9).The utilization of PAA as a template can effectively regulate the nucleation and growth of Cs_(3)Sb_(2)Br_(9),thereby significantly enhancing the charge separation efficiency of the Co_(3)O_(4)-Cs_(3)Sb_(2)Br_(9)heterojunction compared to its counterpart formed without PAA assistance.Under simulated solar light irradiation(100 mW·cm^(-2)),the cerium-doped Co_(3)O_(4)-Cs_(3)Sb_(2)Br_(9)heterojunction exhibits excellent photocatalytic CO_(2)reduction activity without the need for any sacrificial agent.Specifically,the CO yield reaches up to 700.7μmol·g^(-1)·h^(-1),marking a 2.8-fold increase over the sample synthesized without PAA mediation.This polymer-assisted in-situ growth strategy should open up a new avenue for designing and developing more efficient photocatalytic materials based on halide perovskites.
文摘Selective reduction of N_(2)O by CO under excess O_(2) was effectively catalyzed by Fe(0.9 wt%)-exchangedβzeolite(Fe0.9β)in the temperature range of 250–500°C.Kinetic experiments showed that the apparent activation energy for N_(2)O reduction with CO was lower than that for the direct N_(2)O decomposition,and the rate of N_(2)O reduction with CO at 300℃ was 16 times higher than that for direct N_(2)O decomposition.Reaction order analyses showed that CO and N_(2)O were involved in the kinetically important step,while O_(2) was not involved in the important step.At 300℃,the rate of CO oxidation with 0.1%N_(2)O was two times higher than that of CO oxidation with 10%O_(2).This quantitatively demonstrates the preferential oxidation of CO by N_(2)O under excess O_(2) over Fe0.9β.Operando/in-situ diffuse reflectance ultraviolet-visible spectroscopy showed a redox-based catalytic cycle;α-Fe-O species are reduced by CO to give CO_(2) and reduced Fe species,which are then re-oxidized by N_(2)O to regenerate theα-Fe-O species.The initial rate for the regeneration ofα-Fe-O species under 0.1%N_(2)O was four times higher than that under 10%O_(2).This result shows quantitative evidence on the higher reactivity of N_(2)O than O_(2) for the regeneration ofα-Fe-O intermediates,providing a fundamental reason why the Fe0.9βcatalyst selectively promotes the CO+N_(2)O reaction under excess O_(2) rather than the undesired side reaction of CO+O_(2).The mechanistic model was verified by the results of in-situ Fe K-edge X-ray absorption spectroscopy.
基金Project supported by the National Natural Science Foundation of China(52174346)Natural Science Foundation of Shandong Province(ZR2021ME031,ZR2022QE115)Innovation Capability Enhancement Project for Technology Oriented Small and Medium Sized Enterprises of Shandong Province(2022TSGC2586)。
文摘An idea hits us that in-situ synthesizing ceramic phase at intergranular regions of RE-Fe-B alloys should be beneficial to the performance of the materials against corrosion,and in this work a new nanoscale(Zr,Ti)B_(2)with space and point groups of P6/mmm and Fmmm,respectively,was successfully synthesized in NdCeFeB sintered magnets.The hcp-structured(Zr,Ti)B_(2)phases are present in a stripe-like shape.Some of(Zr,Ti)B_(2)are developed at interfaces,and the others exist inside grain boundary phase.They coexist with REFe_(2)and RE-rich phases at intergranular regions.When proximity to RE2Fe14B grains,their orientation relationships obey[001]_(Nd_(2)Fe_(14)B)‖[110](Zr,Ti)B_(2).The formation of(Zr,Ti)B_(2)generates significant local compressive stress,being 8.48 GPa,and plenty of reliefs are developed inside the RE2Fe14B grains.The in-situ formed(Zr,Ti)B_(2)modifies the magnet microstructure,lessens the favorable sites for absorption reaction,narrows reaction channels,and reduces the potential difference between intergranular phase and main phase.Such favorable factors greatly enhance the corrosion resistance with an icorrdecrement by 70%in comparison to the unmodified magnet.These new discoveries are thought to be able to provide an insight into the method of potentially improving properties of magnets.
基金supported by the Key Program for International Cooperation of the Ministry of Science and Technology,China(No.ZCGX2022001L)。
文摘In-situ TiB_(2)/Al–Cu composite was processed by multidirectional forging(MDF)for six passes.The microstructure evolution of the forged workpiece was examined across various regions.The mechanical properties of the as-cast and MDFed composites were compared,and their strengthening mechanisms were analyzed.Results indicate that the grain refinement achieved through the MDF process is mainly due to the subdivision of the original grains through mechanical geometric fragmentation and the occurrence of dynamic recrystallization(DRX).DRX grains are formed through discontinuous DRX,continuous DRX,and recrystallization induced by particle-stimulated nucleation.A rise in accumulated equivalent strain(Σ?ε)results in finerα-Al grains and a more uniform distribution of TiB_(2)particles,which enhance the Vickers hardness of the composite.In addition,the tensile properties of the MDFed composite significantly improve compared with those of the as-cast composites,with ultimate tensile strength and yield strength increasing by 51.2%and 54%,respectively.This enhancement is primarily due to grain refinement strengthening and dislocation strengthening achieved by the MDF process.
基金supported by the financial support of the National Science Fund for Distinguished Young Scholars of China(No.52025014)the National Natural Science Foundation of China(Nos.52101109 and 52171090)+1 种基金the Zhejiang Provincial Natural Science Foundation of China(No.LD24E010003 and LZJWY23E090001)the Natural Science Foundation of Ningbo(Nos.2023J410).
文摘Cr_(2)AlC,a representative MAX phase,gains increasing attention for the excellent oxidation tolerance and corrosion resistance used in harsh high temperature and strong radiation environments.However,the lack of the phase formation mechanism has become the key bottleneck to the practical applications for Cr_(2)AlC synthesis with high purity at low temperatures.In this work,we fabricated the amorphous Cr-Al-C coating by a hybrid magnetron sputtering/cathodic arc deposition technique,in which the in-situ heating transmission electron microscopy(TEM)was conducted in a temperature range of 25-650℃ to address the real-time phase transformation for Cr_(2)AlC coating.The results demonstrated that increas-ing the temperature from 25 to 370℃ led to the structural transformation from amorphous Cr-Al-C to the crystalline Cr_(2)Al interphases.However,the high-purity Cr_(2)AlC MAX phase was distinctly formed at 500℃,accompanied by the diminished amorphous feature.With the further increase of temperature to 650℃,the decomposition of Cr_(2)AlC to Cr_(7)C_(3)impurities was observed.Similar phase evolution was also evidenced by the Ab-initio molecular dynamics calculations,where the bond energy of Cr-Cr,Cr-Al,and Cr-C played the key role in the formed crystalline stability during the heating process.The observa-tions not only provide fundamental insight into the phase formation mechanism for high-purity Cr_(2)AlC coatings but also offer a promising strategy to manipulate the advanced MAX phase materials with high tolerance to high-temperature oxidation and heavy ion radiations.
文摘To convert carbon dioxide into high-value-added liquid products such as formate with renewable electricity(CO_(2)RR)is a promising strategy of CO_(2) resource utilization.The key is to find a highly efficient and selective electrocatalyst for CO_(2)RR.Herein,clustered Bi_(28)O_(32)(SO_(4))_(10) was found to show a high formate Faradaic efficiency(FE_(formate))of 96.2%at–1.1 V_(RHE) and FE_(formate) above 90%in a wide potential range from–0.9 to–1.3 V_(RHE) in H-type cell,surpassing the corresponding layered Bi_(2)O_(2)SO_(4)(85.6%FE_(formate) at–1.1 V_(RHE)).The advantageous CO_(2)RR performance of Bi_(28)O_(32)(SO_(4))_(10) over Bi_(2)O_(2)SO_(4) was ascribed to a special two-step in-situ reconstruction process,consisting of Bi_(28)O_(32)(SO_(4))_(10)→Bi_(-2.1)/Bi_(2)O_(2)CO_(3)→Bi_(-2.1)/Bi_(-0.6) during CO_(2)RR.It gave metallic Bi_(-2.1) with lattice distortion of–2.1%at the first step and metallic Bi_(-0.6) with lattice distortion of–0.6%at the second step.In contrast,the usual layered Bi_(2)O_(2)SO_(4) only formed metallic Bi_(-0.6) with weaker lattice strain.The metallic Bi_(-2.1) revealed higher efficiency in stabilizing*CO_(2) intermediate and reducing the energy barrier of CO_(2)RR,while suppressing hydrogen evolution reaction and CO formation.This work delivers a high-performance cluster-type Bi_(28)O_(32)(SO_(4))_(10) electrocatalyst for CO_(2)RR,and elucidates the origin of superior performance of clustered Bi_(28)O_(32)(SO_(4))_(10) electrocatalysts compared with layered Bi_(2)O_(2)SO_(4).
基金supported by the National Natural Science Foundation of China (No.21965005)Natural Science Foundation of Guangxi Province (No.2021GXNSFAA076001)+1 种基金Guangxi Technology Base and Talent Subject (Nos.GUIKE AD18126001, GUIKE AD20297039)Innovation Project of Guangxi Graduate Education (Nos.YCSW2023140, YCBZ2023062)。
文摘Application of transition metal boride(TMB) catalysts towards hydrolysis of NaBH_(4) holds great significance to help relieve the energy crisis. Herein, we present a facile and versatile metal-organic framework(MOF) assisted strategy to prepare Co_(2)B-CoPO_x with massive boron vacancies by introducing phytic acid(PA) cross-linked Co complexes that are acquired from reaction of PA and ZIF-67 into cobalt boride. The PA etching effectively breaks down the structure of ZIF-67 to create more vacancies, favoring the maximal exposure of active sites and elevation of catalytic activity. Experimental results demonstrate a drastic electronic interaction between Co and the dopant phosphorous(P), thereby the robustly electronegative P induces electron redistribution around the metal species, which facilitates the dissociation of B-H bond and the adsorption of H_(2)O molecules. The vacancy-rich Co_(2)B-CoPO_x catalyst exhibits scalable performance, characterized by a high hydrogen generation rate(HGR) of 7716.7 m L min^(-1)g^(-1) and a low activation energy(Ea) of 44.9 k J/mol, rivaling state-of-the-art catalysts. This work provides valuable insights for the development of advanced catalysts through P doping and boron vacancy engineering and the design of efficient and sustainable energy conversion systems.
基金financially supported by the National Natural Science Foundation of China (No.52106259)the Fundamental Research Funds for the Central Universities (2024MS013)Key Research and Development Program of Shaanxi (Program No.2022LL-JB-08)。
文摘Green hydrogen is urgently required for sustainable development of human beings and rational construction of heterostructures holds great promising for photocatalytic hydrogen generation.Herein,2D/2D WSe_(2)/ZnIn_(2)S_(4) heterostructures with strong hetero-interface interaction and abundant contact were constructed via an impregnation-annealing strategy.Efficient charge transfer from ZnIn_(2)S_(4) to WSe_(2)was evidenced by transient absorption spectroscopy in crafted heterostructures owing to the tight and2D face-to-face contact.As a result,the prepared WSe_(2)/ZnIn_(2)S_(4) heterostructures exhibited boosted photocatalytic performance and a highest hydrogen evolution rate of 3.377 mmol/(g h)was achieved with an apparent quantum yield of 45.7%at 420 nm.The work not only provides new strategies to achieve efficient 2D/2D heterostructures but also paves the way for the development of green hydrogen in the future.
基金supported by National Natural Science Foundation of China(No.62062063)the Science and Technology Research Project of Jiangxi Provincial Department of Education,China(No.GJJ202310)the Jiangxi Provincial Natural Science Foundation,China(No.20224BAB202022).
文摘With the expansion of the Internet market,the traditional software development method has been difficult to meet the market demand due to the problems of long development cycle,tedious work,and difficult system maintenance.Therefore,to improve software development efficiency,this study uses residual networks and bidirectional long short-term memory(BLSTM)networks to improve the Pix2code model.The experiment results show that after improving the visual module of the Pix2code model using residual networks,the accuracy of the training set improves from 0.92 to 0.96,and the convergence time is shortened from 3 hours to 2 hours.After using a BLSTM network to improve the language module and decoding layer,the accuracy and convergence speed of the model have also been improved.The accuracy of the training set grew from 0.88 to 0.92,and the convergence time was shortened by 0.5 hours.However,models improved by BLSTM networks might exhibit overfitting,and thus this study uses Dropout and Xavier normal distribution to improve the memory network.The results validate that the training set accuracy of the optimized BLSTM network remains around 0.92,but the accuracy of the test set has improved to a maximum of 85%.Dropout and Xavier normal distributions can effectively improve the overfitting problem of BLSTM networks.Although they can also decrease the model’s stability,their gain is higher.The training and testing accuracy of the Pix2code improved by residual network and BLSTM network are 0.95 and 0.82,respectively,while the code generation accuracy of the original Pix2code is only 0.77.The above data indicate that the improved Pix2code model has improved the accuracy and stability of code automatic generation.
基金supported by the National Natural Science Foundation of China (Nos. 21277048 and 21505046)the China Postdoctoral Science Foundation (No. 2016 M590336)+1 种基金the "Chenguang Program" funded by Shanghai Education Development FoundationShanghai Municipal Education Commission (No. 15CG21)
文摘In this work,the gold nanoparticles（Au-NPs）were in-situ generated on the surface of MnO2nanosheets to form MnO2/Au-NPs nanocomposite in a simple and cost-effective way.Multiple experiments were carried out to optimize the oxidation of basic dye（Methylene Blue（MB））,including the molar ratio of MnO2to chloroauric acid（HAu Cl4）,the p H of the solution and the effect of initial material.Under the optimal condition,the highest degradation efficiency for MB achieved to 98.9%within 60 min,which was obviously better than commercial MnO2powders（4.3%）and MnO2nanosheets（74.2%）.The enhanced oxidative degradation might attribute to the in-situ generation of ultra-small and highly-dispersed Au-NPs which enlarged the synergistic effect and/or interfacial effect between MnO2nanosheets and Au-NPs and facilitated the uptake of electrons by MnO2from MB during the oxidation,thus validating the application of MnO2/Au-NPs nanocomposite for direct removal of organic dyes from wastewater in a simple and convenient fashion.
基金Project supported by the National Basic Research Program(973)of China(No.2006CB102002)the Pilot Project of Knowledge Innovation Program of Chinese Academy of Sciences(No.KSCX2-YW-N-006)National Natural Science Foundation of China(No.30571253,30621003)
文摘The growth, development and consumption of successive three generations of cotton bollworm, Helicoverpa armigera （Htibner）, fed on cotton bolls grown under elevated CO2 （double-ambient vs. ambient） in open-top chambers were examined. Significant decreases in protein, total amino acid, water and nitrogen content and increases in free fatty acid were observed in cotton bolls. Changes in quality of cotton bolls affected the growth, development and food utilization of H. armigera. Significantly longer larval development duration in three successive generations and lower pupal weight of the second and third generations were observed in cotton bollworm fed on cotton bolls grown under elevated CO2. Significantly lower fecundity was also found in successive three generations of H. armigera fed on cotton bolls grown under elevated CO2. The consumption per larva occurred significant increase in successive three generations and frass per larva were also significantly increased during the second and third generations under elevated CO2. Significantly lower relative growth rate, efficiency of conversion of ingested food and significant higher relative consumption rate in successive three generations were observed in cotton bollworm fed on cotton bolls grown under elevated CO2. Significantly lower potential female fecundity, larval numbers and population consumption were found in the second and third generations of cotton bollworm fed on cotton bolls grown under elevated CO2. The integrative effect of higher larval mortality rate and lower adult fecundity resulted in significant decreases in potential population consumption in the latter two generations. The results show that elevated CO2 adversely affects cotton bolls quality, which indicates the potential population dynamics and potential population consumption of cotton bollworm will alleviate the harm to the plants in the future rising CO2 atmosphere.
基金supported by the National Natural Science Foundation of China(No.21906056No.22176060)+2 种基金the Undergraduate Training Program on Innovation and Entrepreneurship(S202110251087)the Science and Technology Commission of Shanghai Municipality(22ZR1418600)Shanghai Municipal Science and Technology(No.20DZ2250400).
文摘The existence and risk of emerging organic contaminants(EOCs)have been under consideration and paid much effort to degrade these pollutants.Fenton system is one of the most widely used technologies to solve this problem.The original Fenton system relies on the hydroxyl radicals produced by Fe(Ⅱ)/H_(2)O_(2) to oxidize the organic contaminants.However,the application of the Fenton system is limited by its low iron cycling efficiency and the high risks of hydrogen peroxide transportation and storage.The introduction of external energy(including light and electricity etc.)can effectively promote the Fe(Ⅲ)/Fe(Ⅱ)cycle and the reduction of oxygen to produce hydrogen peroxide in situ.This review introduces three in-situ Fenton systems,which are electro-Fenton,Photo-Fenton,and chemical reaction.The mechanism,influencing factors,and catalysts of these three in-situ Fenton systems in degrading EOCs are discussed systematically.This review strengthens the understanding of Fenton and in-situ Fenton systems in degradation,offering further insight into the real application of the in-situ Fenton system in the removal of EOCs.
