Photocatalytic decomposition of sugars is a promising way of providing H_(2),CO,and HCOOH as sus-tainable energy vectors.However,the production of C_(1) chemicals requires the cleavage of robust C−C bonds in sugars wi...Photocatalytic decomposition of sugars is a promising way of providing H_(2),CO,and HCOOH as sus-tainable energy vectors.However,the production of C_(1) chemicals requires the cleavage of robust C−C bonds in sugars with concurrent production of H_(2),which remains challenging.Here,the photo-catalytic activity for glucose decomposition to HCOOH,CO(C_(1) chemicals),and H_(2) on Cu/TiO_(2)was enhanced by nitrogen doping.Owing to nitrogen doping,atomically dispersed and stable Cu sites resistant to light irradiation are formed on Cu/TiO_(2).The electronic interaction between Cu and nitrogen ions originates valence band structure and defect levels composed of N 2p orbit,distinct from undoped Cu/TiO_(2).Therefore,the lifetime of charge carriers is prolonged,resulting in the pro-duction of C_(1) chemicals and H_(2) with productivities 1.7 and 2.1 folds that of Cu/TiO_(2).This work pro-vides a strategy to design coordinatively stable Cu ions for photocatalytic biomass conversion.展开更多
Improving the cycling stability of metal sulfide-based anode materials at high rate is of great significance for advanced sodium ion batteries.However,the sluggish reaction kinetics is a big obstacle for the developme...Improving the cycling stability of metal sulfide-based anode materials at high rate is of great significance for advanced sodium ion batteries.However,the sluggish reaction kinetics is a big obstacle for the development of high-performance sodium storage electrodes.Herein,we have rationally engineered the heterointerface by designing the Fe1?xS/MoS2 heterostructure with abundant“ion reservoir”to endow the electrode with excellent cycling stability and rate capability,which is proved by a series of in and ex situ electrochemical investigations.Density functional theory calculations further reveal that the heterointerface greatly decreases sodium ion diffusion barrier and facilitates charge-transfer kinetics.Our present findings not only provide a deep analysis on the correlation between the structure and performance,but also draw inspiration for rational heterointerface engineering toward the next-generation high-performance energy storage devices.展开更多
Transition metal-N-C materials have considerably been demonstrated as promising catalysts for cathodic oxygen reduction reaction(ORR)in Zn-air batteries.Current efforts mainly focus on tailoring coordination structure...Transition metal-N-C materials have considerably been demonstrated as promising catalysts for cathodic oxygen reduction reaction(ORR)in Zn-air batteries.Current efforts mainly focus on tailoring coordination structure and identifying active sites of metal-N-C materials for ORR,while the mass transport of metal-N-C employed in catalytic layers of working electrodes is seldom engineered.Herein,a Fe-N-C single-atom catalyst featuring high mesoporosity and abundant electrochemically accessible active sites is developed through post-loading Fe species into defective N-doped carbon support.The Fe-N-C single-atom catalyst serving as the air cathode of Zn-air battery delivers a peak power density of 189.9 mW cm^(−2),significantly larger than 114.2 mW cm^(−2) of commercial Pt/C and 162.9 mW cm^(−2) of the Fe-N-C contrast catalyst with low mesoporosity.More importantly,through adding hydrophobic polytetrafluoroethylene(PTFE)nanoparticles in the catalytic layer of air cathode,the peak power density of Fe-N-C single-atom catalyst is further increased to 212.3 mW cm^(−2).The increased peak power density is attributed to the enhancement of O_(2) mass transport,as evidenced by a substantially decreased diffusion layer thickness that is obtained from electrochemical impedance spectroscopy.展开更多
Flexible damping technology considering aseismic materials and aseismic structures seems be a good solution for engineering structures.In this study,a constrained damping structure for underground tunnel lining,using ...Flexible damping technology considering aseismic materials and aseismic structures seems be a good solution for engineering structures.In this study,a constrained damping structure for underground tunnel lining,using a rubber-sand-concrete(RSC)as the aseismic material,is proposed.The aseismic performances of constrained damping structure were investigated by a series of hammer impact tests.The damping layer thickness and shape effects on the aseismic performance such as effective duration and acceleration amplitude of time-domain analysis,composite loss factor and damping ratio of the transfer function analysis,and total vibration level of octave spectrum analysis were discussed.The hammer impact tests revealed that the relationship between the aseismic performance and damping layer thickness was not linear,and that the hollow damping layer had a better aseismic performance than the flat damping layer one.The aseismic performances of constrained damping structure under different seismicity magnitudes and geological conditions were investigated.The effects of the peak ground acceleration(PGA)and tunnel overburden depth on the aseismic performances such as the maximum principal stress and equivalent plastic strain(PEEQ)were discussed.The numerical results show the constrained damping structure proposed in this paper has a good aseismic performance,with PGA in the range(0.2-1.2)g and tunnel overburden depth in the range of 0-300 m.展开更多
Artificial Intelligence(AI)is being increasingly used for diagnosing Vision-Threatening Diabetic Retinopathy(VTDR),which is a leading cause of visual impairment and blindness worldwide.However,previous automated VTDR ...Artificial Intelligence(AI)is being increasingly used for diagnosing Vision-Threatening Diabetic Retinopathy(VTDR),which is a leading cause of visual impairment and blindness worldwide.However,previous automated VTDR detection methods have mainly relied on manual feature extraction and classification,leading to errors.This paper proposes a novel VTDR detection and classification model that combines different models through majority voting.Our proposed methodology involves preprocessing,data augmentation,feature extraction,and classification stages.We use a hybrid convolutional neural network-singular value decomposition(CNN-SVD)model for feature extraction and selection and an improved SVM-RBF with a Decision Tree(DT)and K-Nearest Neighbor(KNN)for classification.We tested our model on the IDRiD dataset and achieved an accuracy of 98.06%,a sensitivity of 83.67%,and a specificity of 100%for DR detection and evaluation tests,respectively.Our proposed approach outperforms baseline techniques and provides a more robust and accurate method for VTDR detection.展开更多
To address the common issues of wrinkling,tearing,and uneven wall thickness in the actual sheet metal stamp-ing process of the outer ring of needle roller bearings,this study analyzes critical technical indicators suc...To address the common issues of wrinkling,tearing,and uneven wall thickness in the actual sheet metal stamp-ing process of the outer ring of needle roller bearings,this study analyzes critical technical indicators such asforming limits,thickness distribution,and principal strains in the forming process in detail.Three-dimensionalmodels of the concave and convex dies were constructed.The effects of different process parameters,includingstamping speed,edge pressure,sheet metal thickness,and friction coefficient,on the quality of the forming partswere investigated by varying these parameters.Subsequently,the orthogonal experimental method was used todetermine an optimal experimental group from multiple sets of experiments.It was found that under the processparameters of a stamping speed of 3000 mm/s,edge pressure of 2000 N,sheet metal thickness of 0.9 mm,andfriction coefficient of 0.125,the forming quality of the outer ring of the bearing is ideal.展开更多
Photothermal catalytic CO_(2) conversion provides an effective solution targeting carbon neutrality by synergistic utilization of photon and heat.However,the C-C coupling initiated by photothermal catalysis is still a...Photothermal catalytic CO_(2) conversion provides an effective solution targeting carbon neutrality by synergistic utilization of photon and heat.However,the C-C coupling initiated by photothermal catalysis is still a big challenge.Herein,a three-dimensional(3D)hierarchical W_(18)O_(49)/WTe_(2) hollow nanosphere is constructed through in-situ embodying of oxygen vacancy and tellurium on the scaffold of WO_(3).The light absorption towards near-infrared spectral region and CO_(2) adsorption are enhanced by the formation of half-metal WTe_(2) and the unique hierarchical hollow architecture.Combining with the generation of oxygen vacancy with strengthened CO_(2) capture,the photothermal effect on the samples can be sufficiently exploited for activating the CO_(2) molecules.In particular,the close contact between W_(18)O_(49)and WTe_(2) largely promotes the photoinduced charge separation and mass transfer,and thus the~*CHO intermediate formation and fixedness are facilitated.As a result,the C-C coupling can be evoked between tungsten and tellurium atoms on WTe_(2).The ethylene production by optimized W_(18)O_(49)/WTe_(2) reaches 147.6μmol g^(-1)with the selectivity of 80%.The in-situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)and density functional theory(DFT)calculations are performed to unveil the presence and significance of aldehyde intermediate groups in C-C coupling.The half-metallic WTe_(2) cocatalyst proposes a new approach for efficient CO_(2) conversion with solar energy,and may especially create a new platform for the generation of multi-carbon products.展开更多
Low-temperature processed electron transport layer(ETL)of TiO_(2)that is widely used in planar perovskite solar cells(PSCs)has inherent low carrier mobility,resulting in insufficient photogenerated elec-tron transport...Low-temperature processed electron transport layer(ETL)of TiO_(2)that is widely used in planar perovskite solar cells(PSCs)has inherent low carrier mobility,resulting in insufficient photogenerated elec-tron transport and thus recombination loss at buried interface.Herein,we demonstrate an effective strategy of laser embedding of p-n homojunctions in the TiO_(2)ETL to accelerate electron transport in PSCs,through localized build-in electric fields that enables boosted electron mobility by two orders of magnitude.Such embedding is found significantly helpful for not only the enhanced crystallization quality of TiO_(2)ETL,but the fabrication of perovskite films with larger-grain and the less-trap-states.The embedded p-n homojunction enables also the modulation of interfacial energy level between perovskite layers and ETLs,favoring for the reduced voltage deficit of PSCs.Benefiting from these merits,the formamidinium lead iodide(FAPbI_(3))PSCs employing such ETLs deliver a champion efficiency of 25.50%,along with much-improved device stability under harsh conditions,i.e.,maintain over 95%of their initial efficiency after operation at maximum power point under continuous heat and illumination for 500 h,as well as mixed-cation PSCs with a champion efficiency of 22.02%and over 3000 h of ambient storage under humidity stability of 40%.Present study offers new possibilities of regulating charge transport layers via p-n homojunction embedding for high performance optoelectronics.展开更多
In practical applications,noble metal doping is often used to prepare high performance gas sensors,but more noble metal doping will lead to higher preparation costs.In this study,CeO_(2)/ZnO-Pd with low palladium cont...In practical applications,noble metal doping is often used to prepare high performance gas sensors,but more noble metal doping will lead to higher preparation costs.In this study,CeO_(2)/ZnO-Pd with low palladium content was prepared by ultrasonic method with fast response and high selectivity for acetone sensing.With the same amount of palladium added,the selectivity coefficient of CeO_(2)/ZnO-Pd is 1.88 times higher than that of the stirred sensor.Compared with the pure PdO-doped CeO_(2)/ZnO-PdO material,the content of Pd in CeO_(2)/ZnO-PdO is about 30%of that in CeO_(2)/ZnO-PdO,but the selectivity coefficient for acetone is 2.56 times higher.The CeO_(2)/ZnO-Pd sensor has a higher response(22.54)to 50×10^(−6) acetone at 300℃and the selectivity coefficient is 2.57 times that of the CeO_(2)/ZnO sensor.The sensor has a sub-second response time(0.6 s)and still has a 2.36 response to 330×10^(−9) of acetone.Ultrasonic doping makes Pd particles smaller and increases the contact area with gas.Meanwhile,the composition of n-p-n heterojunction and the synergistic effect of Pd/PdO improve the sensor performance.It shows that ultrasonic Pd doping provides a way to improve the utilization rate of doped metals and prepare highly selective gas sensors.展开更多
Water content and primary fractures can change the mechanical characteristics of rock,making it easy to induce geological disasters.Therefore,direct shear tests of red sandstone under the action of water-fracture were...Water content and primary fractures can change the mechanical characteristics of rock,making it easy to induce geological disasters.Therefore,direct shear tests of red sandstone under the action of water-fracture were carried out in this paper.The results show that shear strength of rock samples with fractures is less than that of intact rock samples.With the increase of primary fracture dip angle,shear strength and macroscopic crushing area of the rock sample increases first and then decreases with 20°as the boundary.It shows that the primary fractures weaken the shear mechanical properties and change the macroscopic failure mode.The shear performance of water-bearing rock samples is weaker than that of intact rock samples,and the weakening degree of water-saturated on shear performance of rock samples is lower than that of unsaturated water state.The fracture surfaces of rock samples are divided into‘shortest path single through type’,‘longest path single through type’and‘cross path through type’.The failured rock samples are divided into‘single through type’and‘cross through type’.The research results can provide reference for geological disaster management under relevant conditions.展开更多
The quest to increase the performance of production systems that have become complex leads to the transfer to the maintenance function of the responsibility of guaranteeing the availability of such systems. Also, we w...The quest to increase the performance of production systems that have become complex leads to the transfer to the maintenance function of the responsibility of guaranteeing the availability of such systems. Also, we will never stop saying that maintenance must integrate into all of the company’s initiatives, to affirm its role, which is to ensure greater availability and sustainability of the means of production. The objective of this paper is to evaluate the reliability and availability of a system without knowing the distribution law of the operating times. Among the methods for evaluating dependability criteria (Fault Trees, Petri Nets, etc.), we are interested in queues that have the advantage of taking into account functional dependencies, thus allowing a quantified optimization of maintenance. Indeed, queues make it possible to model parallel or sequential processes, implementing operations taking place at the same time or one after the other, meeting the needs of modeling production systems. The main result of this paper is the study of the influence of availability on the reliability of a multi-state production system.展开更多
Coal is a common porous sedimentary rock whose microstructure and mechanical behavior are often affected by high temperature.In order to deeply investigate the effect of high temperature on the structure and mechanica...Coal is a common porous sedimentary rock whose microstructure and mechanical behavior are often affected by high temperature.In order to deeply investigate the effect of high temperature on the structure and mechanical properties of coal,six groups of coal samples with different heating temperatures were prepared.Various testing methods,including ultrasonic test,scanning electron microscopy,nuclear magnetic resonance and uniaxial compression test,were used in this study.The results showed that the physical and chemical change processes of coal samples under high temperature can be divided into two stages:the stage of drying and degassing and the stage of pyrolysis of the coal matrix.With the increase of heating temperature,the total porosity of coal samples increases,while the integrity and the deformation resistance of coal samples decrease.In addition,the elastic modulus and uniaxial compressive strength of the coal sample decrease with the increase of heating temperature.The Poisson’s ratio decreases firstly and then increases with the increase of heating temperature.展开更多
Carbonate rocks are important reservoirs for global petroleum exploration.The largest oilfield in the South China Sea,Liuhua 11-1,is distributed in the massive carbonate reef area of the Zhujiang(Pearl)River Mouth Bas...Carbonate rocks are important reservoirs for global petroleum exploration.The largest oilfield in the South China Sea,Liuhua 11-1,is distributed in the massive carbonate reef area of the Zhujiang(Pearl)River Mouth Basin.Previous studies showed that one 802.17-m-long core from well Xichen-1 in the South China Sea mainly consisted of white and light gray-white organic reefs.Recently,a Miocene whole core(161.9 m long)of well Xiyong-2,near well Xichen-1,was found to contain six layers of yellowish brown,light yellowish gray,iron black,or light yellowish gray-white organic reefs.Scanning electron microscope images of these layers reveal a typical ferroan dolomite rich in Fe(up to 29%),with the high concentrations of Mn,Cu,W,Zn,Cr,Ni,and Co.Systematic X-ray powder diffraction analysis yields a 1.9–6.1 match in phase ratio with ankerite,5.4–26.9 with dolomite,and zero with calcite,which indicate that the samples can be classified as ferroan dolomite.The iron and heavy metals are inferred to be originated from multiple volcanic eruptions of Gaojianshi Island in the Dongdao Atoll during the middle-late Miocene.These elements were dissolved in seawater,likely as a sol,and carried to Yongxing Island in the Xuande Atoll by sea currents and tides enhanced by prevailing winds,and deposited as a part of the sedimentation process in the study area.The ferroan dolomite has Sr content of (125–285)×10^(-6),which is lower than the accepted Sr boundary value of dolomite.This finding suggests that dolomitization occurred during large-scale global glacial regression in the late Miocene.The isolated Xisha carbonate platform,exposed to air,underwent freshwater leaching and dolomitization induced by mixed water,and caused the extensive Fe-Mg exchange along the organic reef profile to form ankerite and ferroan dolomite.These results may help to understand paleoceanographic environmental changes in the South China Sea during the Miocene.展开更多
This study experimentally analyzes the nonlinear flow characteristics and channelization of fluid through rough-walled fractures during the shear process using a shear-flow-visualization apparatus.A series of fluid fl...This study experimentally analyzes the nonlinear flow characteristics and channelization of fluid through rough-walled fractures during the shear process using a shear-flow-visualization apparatus.A series of fluid flow and visualization tests is performed on four transparent fracture specimens with various shear displacements of 1 mm,3 mm,5 mm,7 mm and 10 mm under a normal stress of 0.5 MPa.Four granite fractures with different roughnesses are selected and quantified using variogram fractal dimensions.The obtained results show that the critical Reynolds number tends to increase with increasing shear displacement but decrease with increasing roughness of fracture surface.The flow paths are more tortuous at the beginning of shear because of the wide distribution of small contact spots.As the shear displacement continues to increase,preferential flow paths are more distinctly observed due to the decrease in the number of contact spots caused by shear dilation;yet the area of single contacts in-creases.Based on the experimental results,an empirical mathematical equation is proposed to quantify the critical Reynolds number using the contact area ratio and fractal dimension.展开更多
By designing and fabricating thin film electronic devices on a flexible substrate instead of more commonly used rigid substrate, flexible electronics produced has opened a field of special applications. In this articl...By designing and fabricating thin film electronic devices on a flexible substrate instead of more commonly used rigid substrate, flexible electronics produced has opened a field of special applications. In this article, we first reviewed available products that may be used as flexible substrates, their characteristics and unique advantages as supporting material for flexible electronic devices. Secondly, flexible perovskite solar cell is examined in detail, with special focus on its potential large-scale fabrication processes. In particular, a comprehensive review is provided on low cost solution printing techniques that is viewed highly as a viable tool for potential commercialization of the perovskite solar cells. Furthermore, a summary is given on green processing for the solution printing production of flexible perovskite devices.展开更多
The on-line diameter measurement of larger axis workpieces is hard to achieve high precision detection, because of the bad environment of locale, the problem to amend the measuring error by non-uniform temperature fie...The on-line diameter measurement of larger axis workpieces is hard to achieve high precision detection, because of the bad environment of locale, the problem to amend the measuring error by non-uniform temperature field, and the difficulty to collimate and locate by usual method. By improving the measurement accuracy of larger axis accessories, it is useful to raise axis and hole＇s industry produce level. Because of the influence of complex environment in locale and some influential factors which are hard excluded from the large diameter measurement with multi-rolling-wheels method, the measurement results may not support or even contradict each other. To the situation, this paper puts forward a mutual support deviation distinguish data fusion method, including mutual support deviation detection and weight data fusion. The mutual support deviation detection part can effectively remove or weaken the unexpected impact on the measurement results and the weight data fusion part can get more accurate estimate result to the detected data. So the method can further improve the reliability of measurement results and increase the accuracy of the measurement system. By using the weight data fusion based on the mutual support （DFMS） to the simulation and experiment data, both simulation results and experiment results show that the method can effectively distinguish the data influenced by unexpected impact and improve the stability and reliability of measurement results. The new provided mutual support deviation distinguish method can be used to single sensor measurement and multi-sensor measurement, and can be used as a reference in the data distinguish of other area. The DFMS is helpful to realize the diameter measurement expanded uncertainty in 5 ×10^-6D or even higher when the measured axis workpiece＇s diameter is 1-5 m （ 1 m ≤ D ≤5 m ）.展开更多
To correct spectral peak drift and obtain more reliable net counts,this study proposes a long short-term memory(LSTM)model fused with a convolutional neural network(CNN)to accurately estimate the relevant parameters o...To correct spectral peak drift and obtain more reliable net counts,this study proposes a long short-term memory(LSTM)model fused with a convolutional neural network(CNN)to accurately estimate the relevant parameters of a nuclear pulse signal by learning of samples.A predefined mathematical model was used to train the CNN-LSTM model and generate a dataset composed of distorted pulse sequences.The trained model was validated using simulated pulses.The relative errors in the amplitude estimation of pulse sequences with different degrees of distortion were obtained using triangular shaping,CNN-LSTM,and LSTM models.As a result,for severely distorted pulses,the relative error of the CNN-LSTM model in estimating the pulse parameters was reduced by 14.35%compared with that of the triangular shaping algorithm.For slightly distorted pulses,the relative error of the CNN-LSTM model was reduced by 0.33%compared with that of the triangular shaping algorithm.The model was then evaluated considering two performance indicators,the correction ratio and the efficiency ratio,which represent the proportion of the increase in peak area of the two characteristic peak regions of interest(ROIs)to the peak area of the corrected characteristic peak ROI and the proportion of the increase in peak area of the two characteristic peak ROIs to the peak areas of the two shadow peak ROI,respectively.Ten measurement results of the iron ore samples indicate that approximately 86.27%of the decreased peak area of the shadow peak ROI was corrected to the characteristic peak ROI,and the proportion of the corrected peak area to the peak area of the characteristic peak ROI was approximately 1.72%.The proposed CNN-LSTM model can be applied to X-ray energy spectrum correction,which is of great significance for X-ray spectroscopy and elemental content analyses.展开更多
In this work,a covalent organic framework(COF),which is constructed by the building blocks of[5,10,15,20-tetrakis(4-aminophenyl)porphinato]copper(Ⅱ)(CuTAPP)and p-benzaldehyde,is employed to integrate with TiO_(2) for...In this work,a covalent organic framework(COF),which is constructed by the building blocks of[5,10,15,20-tetrakis(4-aminophenyl)porphinato]copper(Ⅱ)(CuTAPP)and p-benzaldehyde,is employed to integrate with TiO_(2) for the purpose of establishing a Z-scheme hybrid.Within the system,isonicotinic acid performs the role of a bridge that connects the two components through a coordination bond.Further photocatalytic application reveals the hybrid framework is able to catalyze CO_(2) conversion under simulated solar light,resulting in CO production rate of 50.5 μmol g^(-1)·h^(-1),about 9.9 and 24.5 times that of COF and pristine TiO_(2),respectively.The ameliorated catalytic performance owes much to the por-phyrin block acting as photosensitizer that augments the light absorbance,and the establishment of Z-scheme system between the inorganic and orga nic comp on ents that enhances the separati on of the carriers.In addition,the chemical bridge also ensures a steady usage and stable charge delivery in the catalysis.Our study sheds light on the development of versatile approaches to covalently in corporate COFs with inorga nic semic on ductors.展开更多
Creep aging forming(CAF) is a potential process used to manufacture large integral components of magnesium(Mg) alloys. The selected stress plays a crucial role in creep aging processes but the mechanism by which stres...Creep aging forming(CAF) is a potential process used to manufacture large integral components of magnesium(Mg) alloys. The selected stress plays a crucial role in creep aging processes but the mechanism by which stress loading method affects creep aging of Mg alloys is still unclear. In this paper, the microstructural evolution of precipitated phases and precipitation-free zones(PFZ) at grain boundaries with different stress loading modes(unstressed, unidirectional tensile stress, and cyclic stress) at 250 ℃ were investigated along with changes in mechanical properties. The results showed that the addition of stress during aging effectively promoted the precipitation of precipitated phases, while unaffecting grain size. Unidirectional tensile stress caused directional growth of β phase([1010]), as well as rotation of weave towards the basal plane texture, resulting in namely stress orientation effect. Solute atoms diffused in the direction of tensile stress while vacancies moved perpendicular to the direction of tensile stress, resulting in PFZ at grain boundaries(157.06 nm). By contrast, cyclic stresses led to the growth of β phase in three directions([1010], [1100] and [0110]). The solute atoms and vacancies were uniformly distributed in the Mg matrix instead of directional diffusion, effectively reducing the width of PFZ(112.39 nm) at the grain boundary. These features significantly improved the mechanical properties of alloy specimens after cyclic stress creep aging when compared to unidirectional stress creep aging, with yield strength(YS), ultimate tensile strength(UTS), and elongation(EL) enhanced from 171.6 MPa, 305.5 MPa, and 4.4%to 174.8 MPa, 326.3 MPa, and 6.9%, respectively.展开更多
Mercury(Hg)ions can lead to a serious impact on the environment;therefore,it was necessary to find an effective method for absorbing these toxic Hg ions.Here,the adsorbent(Zn-AHMT)was synthesized from zinc nitrate and...Mercury(Hg)ions can lead to a serious impact on the environment;therefore,it was necessary to find an effective method for absorbing these toxic Hg ions.Here,the adsorbent(Zn-AHMT)was synthesized from zinc nitrate and 4-amino 3-hydrazine-5 mercapto-1,2,4-triazole(AHMT)by one-step method and,characterized the microstruc-ture and absorption performance by fourier transform infrared spectroscopy(FTIR),field emission scanning electron microscopy(FESEM),X-ray diffraction(XRD),Brunauer-Emmett Teller(BET),Thermal Gravimetric Analyzer(TGA)and X-ray photoelectron spectroscopy(XPS).Through a plethora of measurements,we found that the maximum adsorption capacity was 802.8 mg/g when the optimal pH of Zn-AHMT was 3.0.The isothermal and kinetic experiments confirm that the reaction process of Zn-AHMT was chemisorption,while the adsorption process conforms to the Hill model and pseudo second order kinetic model.Thermodynamic experiments showed that the adsorption process was spontaneous and exothermic.Selective experiments were performed in the simulated wastewater containing Mn,Mg,Cr,Al,Co,Ni,Hg ions.Our results showed that the Zn-AHMT has a stronger affinity for Hg ions.The removal rate of Zn-AHMT remained above 98%,indicating that the Zn-AHMT had a good stability validated by three adsorption-desorption repeatable tests.According to the XPS results,the adsorption reaction of Zn-AHMT was mainly attributed to the chelation and ion exchange.This was further explained by both density functional theory(DFT)calculation and frontier molecular orbital theory.We therefore propose the adsorption mechanism of Zn-AHMT.The adsorption reaction facilitates via the synergistic action of S and N atoms.Moreover,the bonding between the adsorbent and the N atom has been proved to be more stable.Our study demonstrated that Zn-AHMT had a promising application prospect in mercury removal.展开更多
文摘Photocatalytic decomposition of sugars is a promising way of providing H_(2),CO,and HCOOH as sus-tainable energy vectors.However,the production of C_(1) chemicals requires the cleavage of robust C−C bonds in sugars with concurrent production of H_(2),which remains challenging.Here,the photo-catalytic activity for glucose decomposition to HCOOH,CO(C_(1) chemicals),and H_(2) on Cu/TiO_(2)was enhanced by nitrogen doping.Owing to nitrogen doping,atomically dispersed and stable Cu sites resistant to light irradiation are formed on Cu/TiO_(2).The electronic interaction between Cu and nitrogen ions originates valence band structure and defect levels composed of N 2p orbit,distinct from undoped Cu/TiO_(2).Therefore,the lifetime of charge carriers is prolonged,resulting in the pro-duction of C_(1) chemicals and H_(2) with productivities 1.7 and 2.1 folds that of Cu/TiO_(2).This work pro-vides a strategy to design coordinatively stable Cu ions for photocatalytic biomass conversion.
基金the support from the Thousand Young Talents Program of Chinathe National Natural Science Foundation of China(Nos.51602200,61874074,21603192)+3 种基金Science and Technology Project of Shenzhen(JCYJ20170817101100705,JCYJ20170817100111548,ZDSYS201707271014468)the(Key)Project of Department of Education of Guangdong Province(No.2016KZDXM008)supported by Shenzhen Peacock Plan(No.KQTD2016053112042971)Singapore Ministry of Education Academic Research Fund Tier 2(MOE2018-T2-2-178).
文摘Improving the cycling stability of metal sulfide-based anode materials at high rate is of great significance for advanced sodium ion batteries.However,the sluggish reaction kinetics is a big obstacle for the development of high-performance sodium storage electrodes.Herein,we have rationally engineered the heterointerface by designing the Fe1?xS/MoS2 heterostructure with abundant“ion reservoir”to endow the electrode with excellent cycling stability and rate capability,which is proved by a series of in and ex situ electrochemical investigations.Density functional theory calculations further reveal that the heterointerface greatly decreases sodium ion diffusion barrier and facilitates charge-transfer kinetics.Our present findings not only provide a deep analysis on the correlation between the structure and performance,but also draw inspiration for rational heterointerface engineering toward the next-generation high-performance energy storage devices.
基金supported by the National Natural Science Foundation of China(21838003,91834301,21978278,21978087)the Shanghai Scientific and Technological Innovation Project(18JC1410500,19JC1410400)the Fundamental Research Funds for the Central Universities(222201718002)。
文摘Transition metal-N-C materials have considerably been demonstrated as promising catalysts for cathodic oxygen reduction reaction(ORR)in Zn-air batteries.Current efforts mainly focus on tailoring coordination structure and identifying active sites of metal-N-C materials for ORR,while the mass transport of metal-N-C employed in catalytic layers of working electrodes is seldom engineered.Herein,a Fe-N-C single-atom catalyst featuring high mesoporosity and abundant electrochemically accessible active sites is developed through post-loading Fe species into defective N-doped carbon support.The Fe-N-C single-atom catalyst serving as the air cathode of Zn-air battery delivers a peak power density of 189.9 mW cm^(−2),significantly larger than 114.2 mW cm^(−2) of commercial Pt/C and 162.9 mW cm^(−2) of the Fe-N-C contrast catalyst with low mesoporosity.More importantly,through adding hydrophobic polytetrafluoroethylene(PTFE)nanoparticles in the catalytic layer of air cathode,the peak power density of Fe-N-C single-atom catalyst is further increased to 212.3 mW cm^(−2).The increased peak power density is attributed to the enhancement of O_(2) mass transport,as evidenced by a substantially decreased diffusion layer thickness that is obtained from electrochemical impedance spectroscopy.
基金supported by the National Natural Science Foundation of China(No.52079133)CRSRI Open Research Program(Program SN:CKWV2019746/KY)+1 种基金the project of Key Laboratory of Water Grid Project and Regulation of Ministry of Water Resources(QTKS0034W23291)the Youth Innovation Promotion Association CAS.
文摘Flexible damping technology considering aseismic materials and aseismic structures seems be a good solution for engineering structures.In this study,a constrained damping structure for underground tunnel lining,using a rubber-sand-concrete(RSC)as the aseismic material,is proposed.The aseismic performances of constrained damping structure were investigated by a series of hammer impact tests.The damping layer thickness and shape effects on the aseismic performance such as effective duration and acceleration amplitude of time-domain analysis,composite loss factor and damping ratio of the transfer function analysis,and total vibration level of octave spectrum analysis were discussed.The hammer impact tests revealed that the relationship between the aseismic performance and damping layer thickness was not linear,and that the hollow damping layer had a better aseismic performance than the flat damping layer one.The aseismic performances of constrained damping structure under different seismicity magnitudes and geological conditions were investigated.The effects of the peak ground acceleration(PGA)and tunnel overburden depth on the aseismic performances such as the maximum principal stress and equivalent plastic strain(PEEQ)were discussed.The numerical results show the constrained damping structure proposed in this paper has a good aseismic performance,with PGA in the range(0.2-1.2)g and tunnel overburden depth in the range of 0-300 m.
基金This research was funded by the National Natural Science Foundation of China(Nos.71762010,62262019,62162025,61966013,12162012)the Hainan Provincial Natural Science Foundation of China(Nos.823RC488,623RC481,620RC603,621QN241,620RC602,121RC536)+1 种基金the Haikou Science and Technology Plan Project of China(No.2022-016)the Project supported by the Education Department of Hainan Province,No.Hnky2021-23.
文摘Artificial Intelligence(AI)is being increasingly used for diagnosing Vision-Threatening Diabetic Retinopathy(VTDR),which is a leading cause of visual impairment and blindness worldwide.However,previous automated VTDR detection methods have mainly relied on manual feature extraction and classification,leading to errors.This paper proposes a novel VTDR detection and classification model that combines different models through majority voting.Our proposed methodology involves preprocessing,data augmentation,feature extraction,and classification stages.We use a hybrid convolutional neural network-singular value decomposition(CNN-SVD)model for feature extraction and selection and an improved SVM-RBF with a Decision Tree(DT)and K-Nearest Neighbor(KNN)for classification.We tested our model on the IDRiD dataset and achieved an accuracy of 98.06%,a sensitivity of 83.67%,and a specificity of 100%for DR detection and evaluation tests,respectively.Our proposed approach outperforms baseline techniques and provides a more robust and accurate method for VTDR detection.
基金supported by the China Postdoctoral Science Foundation(Grant No.2022M721395)the National Natural Science Foundation of China(Grant No.72072089).
文摘To address the common issues of wrinkling,tearing,and uneven wall thickness in the actual sheet metal stamp-ing process of the outer ring of needle roller bearings,this study analyzes critical technical indicators such asforming limits,thickness distribution,and principal strains in the forming process in detail.Three-dimensionalmodels of the concave and convex dies were constructed.The effects of different process parameters,includingstamping speed,edge pressure,sheet metal thickness,and friction coefficient,on the quality of the forming partswere investigated by varying these parameters.Subsequently,the orthogonal experimental method was used todetermine an optimal experimental group from multiple sets of experiments.It was found that under the processparameters of a stamping speed of 3000 mm/s,edge pressure of 2000 N,sheet metal thickness of 0.9 mm,andfriction coefficient of 0.125,the forming quality of the outer ring of the bearing is ideal.
基金the National Natural Science Foundation of China(51303083)the National Natural Science Foundation of China for Excellent Young Scholars(51922050)+1 种基金the Natural Science Foundation of Jiangsu Province(BK20191293)the Fundamental Research Funds for the Central Universities(30920021123)。
文摘Photothermal catalytic CO_(2) conversion provides an effective solution targeting carbon neutrality by synergistic utilization of photon and heat.However,the C-C coupling initiated by photothermal catalysis is still a big challenge.Herein,a three-dimensional(3D)hierarchical W_(18)O_(49)/WTe_(2) hollow nanosphere is constructed through in-situ embodying of oxygen vacancy and tellurium on the scaffold of WO_(3).The light absorption towards near-infrared spectral region and CO_(2) adsorption are enhanced by the formation of half-metal WTe_(2) and the unique hierarchical hollow architecture.Combining with the generation of oxygen vacancy with strengthened CO_(2) capture,the photothermal effect on the samples can be sufficiently exploited for activating the CO_(2) molecules.In particular,the close contact between W_(18)O_(49)and WTe_(2) largely promotes the photoinduced charge separation and mass transfer,and thus the~*CHO intermediate formation and fixedness are facilitated.As a result,the C-C coupling can be evoked between tungsten and tellurium atoms on WTe_(2).The ethylene production by optimized W_(18)O_(49)/WTe_(2) reaches 147.6μmol g^(-1)with the selectivity of 80%.The in-situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)and density functional theory(DFT)calculations are performed to unveil the presence and significance of aldehyde intermediate groups in C-C coupling.The half-metallic WTe_(2) cocatalyst proposes a new approach for efficient CO_(2) conversion with solar energy,and may especially create a new platform for the generation of multi-carbon products.
基金financially supported by the project of the National Natural Science Foundation of China(52202115 and 52172101)the China Postdoctoral Science Foundation(2022M722586)+2 种基金the Natural Science Foundation of Chongqing,China(CSTB2022NSCQ-MSX1085)the Shaanxi Science and Technology Innovation Team(2023-CX-TD-44)the Fundamental Research Funds for the Central Universities(3102019JC005 and G2022KY0604)。
文摘Low-temperature processed electron transport layer(ETL)of TiO_(2)that is widely used in planar perovskite solar cells(PSCs)has inherent low carrier mobility,resulting in insufficient photogenerated elec-tron transport and thus recombination loss at buried interface.Herein,we demonstrate an effective strategy of laser embedding of p-n homojunctions in the TiO_(2)ETL to accelerate electron transport in PSCs,through localized build-in electric fields that enables boosted electron mobility by two orders of magnitude.Such embedding is found significantly helpful for not only the enhanced crystallization quality of TiO_(2)ETL,but the fabrication of perovskite films with larger-grain and the less-trap-states.The embedded p-n homojunction enables also the modulation of interfacial energy level between perovskite layers and ETLs,favoring for the reduced voltage deficit of PSCs.Benefiting from these merits,the formamidinium lead iodide(FAPbI_(3))PSCs employing such ETLs deliver a champion efficiency of 25.50%,along with much-improved device stability under harsh conditions,i.e.,maintain over 95%of their initial efficiency after operation at maximum power point under continuous heat and illumination for 500 h,as well as mixed-cation PSCs with a champion efficiency of 22.02%and over 3000 h of ambient storage under humidity stability of 40%.Present study offers new possibilities of regulating charge transport layers via p-n homojunction embedding for high performance optoelectronics.
基金Project(2023JJ10005)supported by the Natural Science Foundation of Hunan Province,ChinaProjects(51772082,51804106)supported by the National Natural Science Foundation of China。
文摘In practical applications,noble metal doping is often used to prepare high performance gas sensors,but more noble metal doping will lead to higher preparation costs.In this study,CeO_(2)/ZnO-Pd with low palladium content was prepared by ultrasonic method with fast response and high selectivity for acetone sensing.With the same amount of palladium added,the selectivity coefficient of CeO_(2)/ZnO-Pd is 1.88 times higher than that of the stirred sensor.Compared with the pure PdO-doped CeO_(2)/ZnO-PdO material,the content of Pd in CeO_(2)/ZnO-PdO is about 30%of that in CeO_(2)/ZnO-PdO,but the selectivity coefficient for acetone is 2.56 times higher.The CeO_(2)/ZnO-Pd sensor has a higher response(22.54)to 50×10^(−6) acetone at 300℃and the selectivity coefficient is 2.57 times that of the CeO_(2)/ZnO sensor.The sensor has a sub-second response time(0.6 s)and still has a 2.36 response to 330×10^(−9) of acetone.Ultrasonic doping makes Pd particles smaller and increases the contact area with gas.Meanwhile,the composition of n-p-n heterojunction and the synergistic effect of Pd/PdO improve the sensor performance.It shows that ultrasonic Pd doping provides a way to improve the utilization rate of doped metals and prepare highly selective gas sensors.
基金supported by the National Natural Science Foundation of China(52004147,51974173)Natural Science Foundation of Shandong Province(ZR2020QE129).
文摘Water content and primary fractures can change the mechanical characteristics of rock,making it easy to induce geological disasters.Therefore,direct shear tests of red sandstone under the action of water-fracture were carried out in this paper.The results show that shear strength of rock samples with fractures is less than that of intact rock samples.With the increase of primary fracture dip angle,shear strength and macroscopic crushing area of the rock sample increases first and then decreases with 20°as the boundary.It shows that the primary fractures weaken the shear mechanical properties and change the macroscopic failure mode.The shear performance of water-bearing rock samples is weaker than that of intact rock samples,and the weakening degree of water-saturated on shear performance of rock samples is lower than that of unsaturated water state.The fracture surfaces of rock samples are divided into‘shortest path single through type’,‘longest path single through type’and‘cross path through type’.The failured rock samples are divided into‘single through type’and‘cross through type’.The research results can provide reference for geological disaster management under relevant conditions.
文摘The quest to increase the performance of production systems that have become complex leads to the transfer to the maintenance function of the responsibility of guaranteeing the availability of such systems. Also, we will never stop saying that maintenance must integrate into all of the company’s initiatives, to affirm its role, which is to ensure greater availability and sustainability of the means of production. The objective of this paper is to evaluate the reliability and availability of a system without knowing the distribution law of the operating times. Among the methods for evaluating dependability criteria (Fault Trees, Petri Nets, etc.), we are interested in queues that have the advantage of taking into account functional dependencies, thus allowing a quantified optimization of maintenance. Indeed, queues make it possible to model parallel or sequential processes, implementing operations taking place at the same time or one after the other, meeting the needs of modeling production systems. The main result of this paper is the study of the influence of availability on the reliability of a multi-state production system.
基金supported by the Natural Science Research Project of the Education Department of Henan Province(No.2010A44002)the National Natural Science Foundation of China(No.51904101)Open Research Fund Program of Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring(Central South University),Ministry of Education(No.2017YSJS14).
文摘Coal is a common porous sedimentary rock whose microstructure and mechanical behavior are often affected by high temperature.In order to deeply investigate the effect of high temperature on the structure and mechanical properties of coal,six groups of coal samples with different heating temperatures were prepared.Various testing methods,including ultrasonic test,scanning electron microscopy,nuclear magnetic resonance and uniaxial compression test,were used in this study.The results showed that the physical and chemical change processes of coal samples under high temperature can be divided into two stages:the stage of drying and degassing and the stage of pyrolysis of the coal matrix.With the increase of heating temperature,the total porosity of coal samples increases,while the integrity and the deformation resistance of coal samples decrease.In addition,the elastic modulus and uniaxial compressive strength of the coal sample decrease with the increase of heating temperature.The Poisson’s ratio decreases firstly and then increases with the increase of heating temperature.
基金Supported by the National Basic Research Program of China(973 Program)(No.2012CB956004)the Science and Technology Basic Resources Investigation Program of China(No.2017FY201407)+1 种基金the National Oil and Gas Major Projects of China(No.2011ZX05025-002)the National Natural Science Foundation of China(NSFC)(No.41106064)
文摘Carbonate rocks are important reservoirs for global petroleum exploration.The largest oilfield in the South China Sea,Liuhua 11-1,is distributed in the massive carbonate reef area of the Zhujiang(Pearl)River Mouth Basin.Previous studies showed that one 802.17-m-long core from well Xichen-1 in the South China Sea mainly consisted of white and light gray-white organic reefs.Recently,a Miocene whole core(161.9 m long)of well Xiyong-2,near well Xichen-1,was found to contain six layers of yellowish brown,light yellowish gray,iron black,or light yellowish gray-white organic reefs.Scanning electron microscope images of these layers reveal a typical ferroan dolomite rich in Fe(up to 29%),with the high concentrations of Mn,Cu,W,Zn,Cr,Ni,and Co.Systematic X-ray powder diffraction analysis yields a 1.9–6.1 match in phase ratio with ankerite,5.4–26.9 with dolomite,and zero with calcite,which indicate that the samples can be classified as ferroan dolomite.The iron and heavy metals are inferred to be originated from multiple volcanic eruptions of Gaojianshi Island in the Dongdao Atoll during the middle-late Miocene.These elements were dissolved in seawater,likely as a sol,and carried to Yongxing Island in the Xuande Atoll by sea currents and tides enhanced by prevailing winds,and deposited as a part of the sedimentation process in the study area.The ferroan dolomite has Sr content of (125–285)×10^(-6),which is lower than the accepted Sr boundary value of dolomite.This finding suggests that dolomitization occurred during large-scale global glacial regression in the late Miocene.The isolated Xisha carbonate platform,exposed to air,underwent freshwater leaching and dolomitization induced by mixed water,and caused the extensive Fe-Mg exchange along the organic reef profile to form ankerite and ferroan dolomite.These results may help to understand paleoceanographic environmental changes in the South China Sea during the Miocene.
基金This study has been partially funded by National Key Research and Development Program of China(Grant No.2020YFA0711800)the National Natural Science Foundation of China(Grant No.51979272)the Natural Science Foundation of Shandong Province,China(Grant No.ZR2021QE069).
文摘This study experimentally analyzes the nonlinear flow characteristics and channelization of fluid through rough-walled fractures during the shear process using a shear-flow-visualization apparatus.A series of fluid flow and visualization tests is performed on four transparent fracture specimens with various shear displacements of 1 mm,3 mm,5 mm,7 mm and 10 mm under a normal stress of 0.5 MPa.Four granite fractures with different roughnesses are selected and quantified using variogram fractal dimensions.The obtained results show that the critical Reynolds number tends to increase with increasing shear displacement but decrease with increasing roughness of fracture surface.The flow paths are more tortuous at the beginning of shear because of the wide distribution of small contact spots.As the shear displacement continues to increase,preferential flow paths are more distinctly observed due to the decrease in the number of contact spots caused by shear dilation;yet the area of single contacts in-creases.Based on the experimental results,an empirical mathematical equation is proposed to quantify the critical Reynolds number using the contact area ratio and fractal dimension.
基金the financial support of the National Key Research and Development Project funding from the Ministry of Science and Technology of China(Grants Nos.2016YFA0202400and 2016YFA0202404)the Peacock Team Project funding from Shenzhen Science and Technology Innovation Committee(Grant No.KQTD2015033110182370)
文摘By designing and fabricating thin film electronic devices on a flexible substrate instead of more commonly used rigid substrate, flexible electronics produced has opened a field of special applications. In this article, we first reviewed available products that may be used as flexible substrates, their characteristics and unique advantages as supporting material for flexible electronic devices. Secondly, flexible perovskite solar cell is examined in detail, with special focus on its potential large-scale fabrication processes. In particular, a comprehensive review is provided on low cost solution printing techniques that is viewed highly as a viable tool for potential commercialization of the perovskite solar cells. Furthermore, a summary is given on green processing for the solution printing production of flexible perovskite devices.
基金supported by Focus of the Funding Item of Metrology of Military Industry in National Defense of China in "Tenth-five-year" Project (Grant No. 60104208)
文摘The on-line diameter measurement of larger axis workpieces is hard to achieve high precision detection, because of the bad environment of locale, the problem to amend the measuring error by non-uniform temperature field, and the difficulty to collimate and locate by usual method. By improving the measurement accuracy of larger axis accessories, it is useful to raise axis and hole＇s industry produce level. Because of the influence of complex environment in locale and some influential factors which are hard excluded from the large diameter measurement with multi-rolling-wheels method, the measurement results may not support or even contradict each other. To the situation, this paper puts forward a mutual support deviation distinguish data fusion method, including mutual support deviation detection and weight data fusion. The mutual support deviation detection part can effectively remove or weaken the unexpected impact on the measurement results and the weight data fusion part can get more accurate estimate result to the detected data. So the method can further improve the reliability of measurement results and increase the accuracy of the measurement system. By using the weight data fusion based on the mutual support （DFMS） to the simulation and experiment data, both simulation results and experiment results show that the method can effectively distinguish the data influenced by unexpected impact and improve the stability and reliability of measurement results. The new provided mutual support deviation distinguish method can be used to single sensor measurement and multi-sensor measurement, and can be used as a reference in the data distinguish of other area. The DFMS is helpful to realize the diameter measurement expanded uncertainty in 5 ×10^-6D or even higher when the measured axis workpiece＇s diameter is 1-5 m （ 1 m ≤ D ≤5 m ）.
基金This work was supported by the Open Project of the Guangxi Key Laboratory of Nuclear Physics and Nuclear Technology(No.NLK2022-05)Central Government Guidance Funds for Local Scientific and Technological Development,China(No.Guike ZY22096024)+3 种基金Sichuan Natural Science Youth Fund Project(No.2023NSFSC1366)Open Research Fund of the National Engineering Research Center for Agro-Ecological Big Data Analysis&Application,Anhui University(No.AE202209)Research Fund of Guangxi Key Lab of Multi-source Information Mining&Security(MIMS22-04)National Natural Science Youth Foundation of China(No.12305214).
文摘To correct spectral peak drift and obtain more reliable net counts,this study proposes a long short-term memory(LSTM)model fused with a convolutional neural network(CNN)to accurately estimate the relevant parameters of a nuclear pulse signal by learning of samples.A predefined mathematical model was used to train the CNN-LSTM model and generate a dataset composed of distorted pulse sequences.The trained model was validated using simulated pulses.The relative errors in the amplitude estimation of pulse sequences with different degrees of distortion were obtained using triangular shaping,CNN-LSTM,and LSTM models.As a result,for severely distorted pulses,the relative error of the CNN-LSTM model in estimating the pulse parameters was reduced by 14.35%compared with that of the triangular shaping algorithm.For slightly distorted pulses,the relative error of the CNN-LSTM model was reduced by 0.33%compared with that of the triangular shaping algorithm.The model was then evaluated considering two performance indicators,the correction ratio and the efficiency ratio,which represent the proportion of the increase in peak area of the two characteristic peak regions of interest(ROIs)to the peak area of the corrected characteristic peak ROI and the proportion of the increase in peak area of the two characteristic peak ROIs to the peak areas of the two shadow peak ROI,respectively.Ten measurement results of the iron ore samples indicate that approximately 86.27%of the decreased peak area of the shadow peak ROI was corrected to the characteristic peak ROI,and the proportion of the corrected peak area to the peak area of the characteristic peak ROI was approximately 1.72%.The proposed CNN-LSTM model can be applied to X-ray energy spectrum correction,which is of great significance for X-ray spectroscopy and elemental content analyses.
基金financially supported by the National Natural Science Foundation of China (21663027 and 21808189)the Key Science and Technology Foundation of Gansu Province (20YF3GA021)+2 种基金the Innovation funding program of Universities of Gansu province (2020B-091)the Opening Project of Key Laboratory of Green Chemistry of Sichuan Institutes of Higher Education (LYJ18205)the Promotion Project of Young-Teacher Researchcapacity of Northwest Normal University (NWNU-LKQN-18-5).
文摘In this work,a covalent organic framework(COF),which is constructed by the building blocks of[5,10,15,20-tetrakis(4-aminophenyl)porphinato]copper(Ⅱ)(CuTAPP)and p-benzaldehyde,is employed to integrate with TiO_(2) for the purpose of establishing a Z-scheme hybrid.Within the system,isonicotinic acid performs the role of a bridge that connects the two components through a coordination bond.Further photocatalytic application reveals the hybrid framework is able to catalyze CO_(2) conversion under simulated solar light,resulting in CO production rate of 50.5 μmol g^(-1)·h^(-1),about 9.9 and 24.5 times that of COF and pristine TiO_(2),respectively.The ameliorated catalytic performance owes much to the por-phyrin block acting as photosensitizer that augments the light absorbance,and the establishment of Z-scheme system between the inorganic and orga nic comp on ents that enhances the separati on of the carriers.In addition,the chemical bridge also ensures a steady usage and stable charge delivery in the catalysis.Our study sheds light on the development of versatile approaches to covalently in corporate COFs with inorga nic semic on ductors.
基金supported by Natural Science Foundation of Shanxi province (20210302123135,20210302123163)Science and Technology Major Project of Shanxi province (20191102008)+6 种基金Scientific and Technological Achievements Transformation Guidance Special Project of Shanxi province (202104021301022)The Ministry of Science and Higher Education of the Russian Federation for financial support under the Megagrant (No.075-15-2022-1133)the National Research Foundation (NRF) grant funded by the Ministry of Science and ICT (2015R1A2A1A01006795) of Korea through the Research Institute of Advanced MaterialsThe central government guided local science and technology development projects (YDZJSX2021A010)China Postdoctoral Science Foundation (2022M710541)the projects of International Cooperation in Shanxi (201803D421086)Research Project Supported by Shanxi Scholarship Council of China (2022- 038)。
文摘Creep aging forming(CAF) is a potential process used to manufacture large integral components of magnesium(Mg) alloys. The selected stress plays a crucial role in creep aging processes but the mechanism by which stress loading method affects creep aging of Mg alloys is still unclear. In this paper, the microstructural evolution of precipitated phases and precipitation-free zones(PFZ) at grain boundaries with different stress loading modes(unstressed, unidirectional tensile stress, and cyclic stress) at 250 ℃ were investigated along with changes in mechanical properties. The results showed that the addition of stress during aging effectively promoted the precipitation of precipitated phases, while unaffecting grain size. Unidirectional tensile stress caused directional growth of β phase([1010]), as well as rotation of weave towards the basal plane texture, resulting in namely stress orientation effect. Solute atoms diffused in the direction of tensile stress while vacancies moved perpendicular to the direction of tensile stress, resulting in PFZ at grain boundaries(157.06 nm). By contrast, cyclic stresses led to the growth of β phase in three directions([1010], [1100] and [0110]). The solute atoms and vacancies were uniformly distributed in the Mg matrix instead of directional diffusion, effectively reducing the width of PFZ(112.39 nm) at the grain boundary. These features significantly improved the mechanical properties of alloy specimens after cyclic stress creep aging when compared to unidirectional stress creep aging, with yield strength(YS), ultimate tensile strength(UTS), and elongation(EL) enhanced from 171.6 MPa, 305.5 MPa, and 4.4%to 174.8 MPa, 326.3 MPa, and 6.9%, respectively.
基金the Hubei Provincial Department of Education Science and Technology Research Program Young Talent Project(Q20201102)the National Natural Science Foundation of China(51864042 and 51804220).
文摘Mercury(Hg)ions can lead to a serious impact on the environment;therefore,it was necessary to find an effective method for absorbing these toxic Hg ions.Here,the adsorbent(Zn-AHMT)was synthesized from zinc nitrate and 4-amino 3-hydrazine-5 mercapto-1,2,4-triazole(AHMT)by one-step method and,characterized the microstruc-ture and absorption performance by fourier transform infrared spectroscopy(FTIR),field emission scanning electron microscopy(FESEM),X-ray diffraction(XRD),Brunauer-Emmett Teller(BET),Thermal Gravimetric Analyzer(TGA)and X-ray photoelectron spectroscopy(XPS).Through a plethora of measurements,we found that the maximum adsorption capacity was 802.8 mg/g when the optimal pH of Zn-AHMT was 3.0.The isothermal and kinetic experiments confirm that the reaction process of Zn-AHMT was chemisorption,while the adsorption process conforms to the Hill model and pseudo second order kinetic model.Thermodynamic experiments showed that the adsorption process was spontaneous and exothermic.Selective experiments were performed in the simulated wastewater containing Mn,Mg,Cr,Al,Co,Ni,Hg ions.Our results showed that the Zn-AHMT has a stronger affinity for Hg ions.The removal rate of Zn-AHMT remained above 98%,indicating that the Zn-AHMT had a good stability validated by three adsorption-desorption repeatable tests.According to the XPS results,the adsorption reaction of Zn-AHMT was mainly attributed to the chelation and ion exchange.This was further explained by both density functional theory(DFT)calculation and frontier molecular orbital theory.We therefore propose the adsorption mechanism of Zn-AHMT.The adsorption reaction facilitates via the synergistic action of S and N atoms.Moreover,the bonding between the adsorbent and the N atom has been proved to be more stable.Our study demonstrated that Zn-AHMT had a promising application prospect in mercury removal.
