Small-sized Cd_(x) Zn_(1-x) S solid solution nanomaterial is an important candidate for efficient photocatalytic hydrogen evolution(PHE),but it still suffers from easy agglomeration,severe photo corrosion,and fast pho...Small-sized Cd_(x) Zn_(1-x) S solid solution nanomaterial is an important candidate for efficient photocatalytic hydrogen evolution(PHE),but it still suffers from easy agglomeration,severe photo corrosion,and fast photogenerated electron-hole recombination.To tackle these issues,herein,we propose a new strategy to modify Cd_(x) Zn_(1-x) S nanoreactors by the simultaneous utilization of ionic-liquid-assisted morphology engineering and MXene-incorporating method.That is,we designed and synthesized a novel hierarchi-cal Cd_(0.8) Zn_(0.2) S/Ti_(3) C_(2) Schottky junction composite through the in-situ deposition of ultrathin Cd_(0.8) Zn_(0.2) S nanosheets on unique IL-modified Ti_(3) C_(2) MXenes by a one-pot solvothermal method for efficiently PHE.The unique construction strategy tailors the thickness of ultrathin Cd_(0.8) Zn_(0.2) S nanosheets and prevents them from stacking and agglomeration,and especially,optimizes their charge transfer pathways during the photocatalytic process.Compared with pristine Cd_(0.8) Zn_(0.2) S nanosheets,Cd_(0.8) Zn_(0.2) S/Ti_(3) C_(2) has abun-dant photogenerated electrons available on the Ti_(3) C_(2) surface for proton reduction reaction,owing to the absence of deep-trapped electrons,suppression of electron-hole recombination in Cd_(0.8) Zn_(0.2) S and high-efficiency charge separation at the Cd_(0.8) Zn_(0.2) S/Ti_(3) C_(2) Schottky junction interface.Moreover,the hy-drophilicity,electrical conductivity,visible-light absorption capacity,and surficial hydrogen desorption of Cd_(0.8) Zn_(0.2) S/Ti_(3) C_(2) heterostructure are significantly improved.As a result,the heterostructure exhibits out-standing photocatalytic stability and super high apparent quantum efficiency,being rendered as one of the best noble-metal-free Cd-Zn-S-based photocatalysts.This work illustrates the mechanisms of mor-phology control and heterojunction construction in controlling the catalytic behavior of photocatalysts and highlights the great potential of the IL-assisted route in the synthesis of high-performance MXene-based heterostructures for photocatalytic hydrogen evolution.展开更多
Doping engineering is an effective strategy for graphitic carbon nitride(g-C_(3)N_(4))to improve its photocat-alytic hydrogen evolution reaction(HER)performance.In this work,a novel nitrogen and sulfur co-doped g-C_(3...Doping engineering is an effective strategy for graphitic carbon nitride(g-C_(3)N_(4))to improve its photocat-alytic hydrogen evolution reaction(HER)performance.In this work,a novel nitrogen and sulfur co-doped g-C_(3)N_(4)(N,S-g-C_(3)N_(4))is elaborately designed on the basis of theoretical predictions of first-principle density functional theory(DFT).The calculated Gibbs free energy of adsorbed hydrogen(ΔGH∗)for N,S-g-C_(3)N_(4) at the N-doping active sites is extremely close to zero(0.01 eV).Inspired by the theoretical predictions,the N,S-g-C_(3)N_(4) is successfully fabricated through ammonia-rich pyrolysis synthesis strategy,in which ammonia is in-situ obtained by pyrolyzing melamine.Subsequent characterizations indicate that the N,S-g-C_(3)N_(4) possesses high specific surface area,outstanding light utilization,good hydrophilicity,and efficient carrier transfer efficiency.Consequently,the N,S-g-C_(3)N_(4) displays an extremely high H2 evolution rate of 8269.9μmol g−1 h−1,achieves an apparent quantum efficiency(AQE)of 3.24%,and also possesses outsatnding durability.Theoretical calculations further demonstrate that N and S dopants can not only introduce doping energy level to reduce the band gap,but also induce charge redistribution to facilitate hydrogen adsorption,thus promoting the photocatalytic HER process.Moreover,femtosecond transient absorption(fs-TA)spectroscopy further corroborates the efficient photogenerated carrier transport of N,S-g-C_(3)N_(4).This research highlights a promising and reliable strategy to achieve superior photocatalytic activity,and exhibits significant guidance for precise designing high-efficiency photocatalysts.展开更多
Streptococcus pneumoniae is a known notorious cause of invasive pneumococcal diseases as well as asymptomatic host carriage. Efforts have been made to curb this infectious organism through various vaccine strategies. ...Streptococcus pneumoniae is a known notorious cause of invasive pneumococcal diseases as well as asymptomatic host carriage. Efforts have been made to curb this infectious organism through various vaccine strategies. However, its several strains and serotypes have necessitated various vaccine schedules and updates in the USA and globally. The evolution in pneumococcal vaccine schedules is not without challenges, such as cost, vaccine hesitancy, uptake and global disparities. This narrative review synopsizes the history of the Pneumococcal Vaccine and changes in its schedules in the last two decades based on published data. We focused on the impact of pneumococcal vaccination on invasive pneumococcal diseases, historical limitations, current challenges and future directions. Despite advancements in vaccination against S. pneumoniae infections, some pertinent issues exist that need to be swiftly fixed, to reduce national and thus global burden of pneumococcal diseases.展开更多
Synchronously achieving morphological and electronic engineering control is crucial but challenging for enhancing the oxygen evolution reaction(OER)performance of nickel-iron based catalysts.Herein,a ruthenium and sul...Synchronously achieving morphological and electronic engineering control is crucial but challenging for enhancing the oxygen evolution reaction(OER)performance of nickel-iron based catalysts.Herein,a ruthenium and sulfur co-modified nickel-iron hydroxide(S_(A)Ru_(T)-FeNiOH_(x)-5h)was synthesized by a distributed room-temperature impregnation method.It was found that the solubility product difference between ruthenium and nickel-iron hydroxide can promote the rapid nucleation of the catalyst and form finer nanosheet structures,thereby increasing 1.25 times for the contact area between the catalyst and the electrolyte.Meanwhile,the subsequent deposition of sulfur can act as an electronic modulator,promoting the transfer of surface charge at nickel sites and increasing the oxidation state of nickel.Theoretical calculations indicate that the combination of ruthenium and sulfur can effectively optimize the OER reaction pathway and lower the activation energy barrier of the rate-determining step,endowing S_(A)Ru_(T)-FeNiOH_(x)-5h an excellent OER performance with a low overpotential of 253 mV at 1000 mA/cm^(2) and long-term stability(500 h).In the future,it is hoped that this strategy of synergistic control of morphology and electronic structure can be applied to the development of other highly active catalysts.展开更多
Detecting Alzheimer’s disease is essential for patient care,as an accurate diagnosis influences treatment options.Classifying dementia from non-dementia in brain MRIs is challenging due to features such as hippocampa...Detecting Alzheimer’s disease is essential for patient care,as an accurate diagnosis influences treatment options.Classifying dementia from non-dementia in brain MRIs is challenging due to features such as hippocampal atrophy,while manual diagnosis is susceptible to error.Optimal computer-aided diagnosis(CAD)systems are essential for improving accuracy and reducing misclassification risks.This study proposes an optimized ensemble method(CEOE-Net)that initiates with the selection of pre-trained models,including DenseNet121,ResNet50V2,and ResNet152V2 for unique feature extraction.Each selected model is enhanced with the inclusion of a channel attention(CA)block to improve the feature extraction process.In addition,this study employs the Short Time Fourier transform(STFT)technique with each individual model for hierarchical feature extraction before making final predictions in classifying MRI images of dementia and non-demented individuals,considering them as backbone models for building the ensemble method.STFT highlights subtle differences in brain structure and activity,particularly when combined with CA mechanisms that emphasize relevant features by converting spatial data into the frequency domain.The predictions generated from these models are then processed by the Chaotic Evolution Optimization(CEO)algorithm,which determines the optimal weightage set for each backbone model to maximize their contribution.The CEO optimizer explores weight distribution to ensure the most effective combination of model predictions for enhancing classification accuracy,thus significantly improving overall ensemble performance.This study utilized three datasets for validation:two private clinical brain MRI datasets(OSASIS and ADNI)to test the proposed model’s effectiveness.Image augmentation techniques were also employed to enhance dataset diversity and improve classification performance.The proposed CEOE-Net outperforms conventional baseline models and existing methods by showing its effectiveness as a clinical tool for the accurate classification of dementia and non-dementia MRI brain images,as well as autistic and non-autistic facial features.It achieved consistent accuracies of 93.44%on OSASIS and 81.94%on ADNI.展开更多
Functionalization has emerged as a pivotal endeavor to tailor the surface properties of photocatalysts.We propose a facile amine functionalization strategy to establish a Cu−In−Zn−S(CIZS)/NiSx hybrid with covalent bon...Functionalization has emerged as a pivotal endeavor to tailor the surface properties of photocatalysts.We propose a facile amine functionalization strategy to establish a Cu−In−Zn−S(CIZS)/NiSx hybrid with covalent bonds using individual ethylenediamine(EDA)molecules.Our approach witnesses a remarkable photocatalytic hydrogen evolution(PHE)competence of 65.93 mmol g^(−1)h^(−1)driven by visible light,the highest value yielded by CIZS to date.X-ray absorption spectra of CIZS and density functional theory(DFT)calculations confirm the crucial amine N→Cu coordination after amine functionalization.The new emerging coordination via lone-pair electron donation profitably accesses the regulation of the coordination environment,electronic structures,and carrier behavior.Moreover,individual EDA molecule with two-terminal−NH2 group serves as a molecular bridge to hybrid CIZS and NiS_(x)cocatalyst via N→Cu and N→Ni coordination,favorably promoting efficient charge transport.This study provides advances in practical functionalizing photocatalysts.展开更多
Constructing S-scheme heterojunctions preserves the intrinsic redox capabilities of both semiconductors while promoting the separation of photogenerated electrons and holes,making it a promising approach for enhancing...Constructing S-scheme heterojunctions preserves the intrinsic redox capabilities of both semiconductors while promoting the separation of photogenerated electrons and holes,making it a promising approach for enhancing the properties of semiconductors.In this study,an S-scheme Cd_(0.8)Zn_(0.2)S-CeO_(2)(CZS-CeO_(2))heterojunction was successfully fabricated via the in-situ growth of CZS nanowires on CeO_(2)nanocubes.The S-scheme charge-transfer mechanism of the CZS-CeO_(2)composites during photocatalytic reactions was confirmed through in-situ X-ray photoelectron spectroscopy and density functional theory calculations.These results demonstrate that the interfacial electric field(IEF)significantly facilitates charge separation and transport within the heterojunction.Consequently,the CZS-CeO_(2)composites exhibited excellent photocatalytic hydrogen production performance under simulated sunlight irradiation,surpassing that of blank CZS.Particularly,the optimal photocatalytic hydrogen generation rate for CZS-15%CeO_(2)reached 58 mmol·g^(-1)·h^(-1),approximately 8.8 times higher than that of blank CZS.After five consecutive cycles of testing,CZS-15%CeO_(2)retained a relatively high level of activity.This enhanced stability can be attributed to the fabrication of S-scheme heterojunctions,which effectively suppressed hole-induced photocorrosion of CZS.This investigation provides a beneficial reference for the rational design of S-scheme heterojunction photocatalysts for efficient and stable photocatalytic hydrogen production.展开更多
Effective separation of bulk phase and surface charges is crucial for maximizing charge utilization in the process of photocatalytic energy conversion.In this study,SnS_(2) nanoflowers and twinned Mn_(0.5) Cd_(0.5) S ...Effective separation of bulk phase and surface charges is crucial for maximizing charge utilization in the process of photocatalytic energy conversion.In this study,SnS_(2) nanoflowers and twinned Mn_(0.5) Cd_(0.5) S solid solution(T-MCS)nanoparticles were fabricated by a one-step solvothermal method respectively,fol-lowed by the formation of SnS_(2)/T-MCS nanohybrids through a facile physical solvent evaporation process for high-efficiency photocatalytic hydrogen(H_(2))production.The T-MCS crystal structure consists of alter-nating wurtzite Mn_(0.5) Cd_(0.5) S(WZ-MCS)and zinc blende Mn_(0.5) Cd_(0.5) S(ZB-MCS),forming a twin structure within the semiconductor.The charge migration mechanism between WZ-MCS and ZB-MCS follows the S-scheme pathway owing to slight differences in energy levels within their respective crystal structures,resulting in exceptional bulk phase charge separation capacity of T-MCS.Additionally,SnS_(2) enhances the electrochemical performance of the catalysts by providing more active sites,reducing charge transfer re-sistance and H_(2) production overpotential,thereby facilitating faster reaction kinetics.The photoelectro-chemical tests,radical trapping experiments,density functional theory(DFT),and electron paramagnetic resonance spectroscopy(EPR)confirm that the charge transfer path between SnS_(2) and T-MCS follows an S-type route that accelerates interfacial photo-induced electrons and holes separation while preserving useful charges.The synergistic impact of twinned homojunction and S-type heterojunction in 10 wt.%SnS_(2)/T-MCS composite contributes to a remarkable H_(2) production rate of 182.82 mmol h^(-1) g^(-1),which is 761.8 times higher than that achieved with SnS_(2) alone(0.24 mmol h^(-1) g^(-1)),as well as 5.8 times higher than that achieved with T-MCS alone(31.54 mmol h^(-1) g^(-1)).This study offers novel insights into design-ing highly efficient sulfide photocatalysts specifically targeting solar-driven H_(2) evolution through a dual S-scheme transfer pathway.展开更多
MgO has been shown to facilitate the precipitation of MgO-rich crystalline phases within the MgO-CaO-Al_(2)O_(3)-SiO_(2)(MCAS)glassy inclusion system,which possesses a high liquidus temperature and a significant Young...MgO has been shown to facilitate the precipitation of MgO-rich crystalline phases within the MgO-CaO-Al_(2)O_(3)-SiO_(2)(MCAS)glassy inclusion system,which possesses a high liquidus temperature and a significant Young’s modulus.The underlying linkage between the structural evolution and the crystallization characteristics of the MCAS system was systematically investigated using molecular dynamics simulation and thermodynamic calculation.The results revealed that Mg^(2+) ions played a dual role,constructing networks through the formation of tricluster oxygens while consuming bridging oxygens(BOs)in a mechanism similar to Ca^(2+) ions.However,despite this dual role,the network connectivity was still decreased with the increase in MgO/(MgO+Al_(2)O_(3))(M/(M+A))and CaO/(CaO+SiO_(2))(C/(C+S))ratios,primarily due to the reduction in BOs.This microscopic structural evolution resulted in a reduction in viscosity and an enhancement of crystallization ability.Furthermore,the remarkable diffusion capability of Mg^(2+) ions,coupled with the increased proportion of 6-coordinated Mg^(2+)ions,unveiled the mechanism underlying the precipitation of MgSiO_(3) and Mg_(2)SiO_(4) crystals,which exhibited high Young’s moduli of 165.23 and 196.67 GPa,respectively.To prevent the precipitation of MgO-rich crystalline phases,it was crucial to maintain the M/(M+A)ratio below 0.42 and the C/(C+S)ratio below 0.16 within the MCAS system.展开更多
[Objective]The aim was to prove that the mitochondrial genes of Cyt b and 12S rRNA with different evolutional rates have effects on the topological structures of phylogenetic trees.[Method]The complete sequences of Cy...[Objective]The aim was to prove that the mitochondrial genes of Cyt b and 12S rRNA with different evolutional rates have effects on the topological structures of phylogenetic trees.[Method]The complete sequences of Cyt b and 12S rRNA from 15 species in 12 families of snakes were downloaded and extracted from GenBank,while their molecular phylogenetic trees were constructed by Maximum Likelihood（ML） method with GTR ＋I ＋G substitute model based on PAUP4.0 software.[Result]With the same software,methods and species,the difference in topological structures of phylogenetic trees was mainly due to different evolutional rates of Cyt b and 12S rRNA genes.[Conclusion]In studies on phylogenetic trees,aimed to different research species and purposes,phylogenetic trees should be constructed by choosing the correct and appropriate genes.展开更多
In this work,we designed and prepared the novel TiO2@ZnIn2 S4 nano-sized hollow structure via templating method assisted by hydrothermal synthesis process.Its unique hollow structure and type-II heterojunction between...In this work,we designed and prepared the novel TiO2@ZnIn2 S4 nano-sized hollow structure via templating method assisted by hydrothermal synthesis process.Its unique hollow structure and type-II heterojunction between TiO2 hollow nanospheres and ZnIn2 S4 nanosheet can provide enough interior cavities and transfer paths for the light absorption and charge quick migration.The crystal structure,morphology and charges separation property were measured.The characterization results show that the hollow-structured Ti O2@ZnIn2 S4 was successfully prepared,and the optimal sample exhibited excellent photocatalytic hydrogen generation compared with TiO2/ZnIn2 S4 cluster exceeding by a factor of 1.1 under overall light irradiation.Specially,the detailed mechanism of the photocatalytic H2 evolution and charge carrier migration for the as-prepared TiO2@ZnIn2 S4 hollow nanosphere was also studied.展开更多
Experimental results about concrete under sulfate attack are summarized, which include the variation of mass density of samples and velocity of ultrasonic wave propagating in samples. The evolution damage is analyzed ...Experimental results about concrete under sulfate attack are summarized, which include the variation of mass density of samples and velocity of ultrasonic wave propagating in samples. The evolution damage is analyzed in terms of the experimental results, and close attention is paid to the effect of damage evolution on Poisson＇s ratio. This study shows that Poisson＇s ratio is significantly affected by the concentration of solution and water-cement ratio. Poisson＇s ratio of concrete changes very little when the water-cement ratio is selected as 0.6 or 0.8, so that such change may be neglected. If water-cement is 0.4, however, the Poisson＇s ratio of the sample significantly changes. When the concrete sample of 0.4 water-cement ratio is immersed in sodium sulfate solution of 8% concentration for 285 days, Poisson＇s ratio increase 10.14% compared with its initial value. There exist a sensitive region and a non-sensitive region for the change rate of Poisson＇s ratio with respect to corrosion time. The change rate of Poisson＇s ratio monotonously decreases with corrosion time in the sensitive region; in the non-sensitive region, the change rate of Poisson＇s ratio is almost equal to zero.展开更多
Two-dimensional mesoporous ultrathin Cd0.5Zn0.5S nanosheets with a thickness of~1.5 nm were fabricated using a multistep chemical transformation strategy involving inorganic–organic hybrid ZnS-ethylenediamine(denoted...Two-dimensional mesoporous ultrathin Cd0.5Zn0.5S nanosheets with a thickness of~1.5 nm were fabricated using a multistep chemical transformation strategy involving inorganic–organic hybrid ZnS-ethylenediamine(denoted as ZnS(en)0.5)as a hard template.Inorganic–organic hybrid ZnS(en)0.5,Cd0.5Zn0.5S(en)x,and Cd0.5Zn0.5S nanosheets were sequentially fabricated,and their transformation processes were analyzed in detail.The fabricated Cd0.5Zn0.5S nanosheets exhibited high photocatalytic hydrogen evolution reaction activity in the presence of a sacrificial agent.The Cd0.5Zn0.5S nanosheets exhibited remarkably high H2 production activity of~1395μmol∙h^−1∙g^−1 in pure water with no co-catalyst,which is the highest value reported thus far for bare photocatalysts,to the best of our knowledge.The high activity of these nanosheets is attributed to their distinct nanostructure(e.g.,short transfer distance of photoinduced charge carriers,large number of unsaturated surface atoms,and large surface area).Moreover,ternary NiCo2S4 nanoparticles were employed to facilitate the charge separation and enhance the surface kinetics of H2 evolution.The H2 production rate reached~62.2 and~2436μmol∙h^−1∙g^−1 in triethanolamine and pure water,respectively,over the NiCo2S4/Cd0.5Zn0.5S heterojunctions.The result indicated that the Schottky junction was critical to the enhanced activity.The proposed method can be used for fabricating other highly efficient CdZnS-based photocatalysts for solar-energy conversion or other applications.展开更多
The evolution of precipitates of S31042 steel during 700 ℃ aging was investigated by using a scanning elec- tron microscope, a transmission electron microscope, and electron energy spectrum technology. The various co...The evolution of precipitates of S31042 steel during 700 ℃ aging was investigated by using a scanning elec- tron microscope, a transmission electron microscope, and electron energy spectrum technology. The various combi nations of M23C6, MX, NbCrN, and σ and G phases in the steel were found at different aging states. In the begin ning of aging, M23C6 precipitates swiftly along the grain boundaries. When the aging time exceeds 6 000 h, precipita- ted M23C6 carbides along the grain boundaries turn to be granular. It was found that Si element segregates to grain boundaries during above process, which may enhance the granular shape of M23C6 carbides and its transformation to and G phases. When the aging time exceeds 10 000 h, various shaped a phase and granular G phase appear along the grain boundaries and there are no continuous M23C6 carbides along the grain boundaries. Meanwhile, a large quantity of granular M23C6 carbides and a minor amount of G phase precipitate near the grain boundaries. Based on the segre- gation of silicon to the grain boundaries, a precipitation evolution model during aging was concluded.展开更多
Designing highly active and stable electrocata-lysts for hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)is a challenge for energy con-version and storage technology.In this work,a S and N co-doped g...Designing highly active and stable electrocata-lysts for hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)is a challenge for energy con-version and storage technology.In this work,a S and N co-doped graphene supported cobalt–nickel sulfide composite catalyst(rGO@SN-CoNi_(2)S_(4))was synthesized simply via a one-step hydrothermal method.The as-synthesized CoNi_(2)S_(4)particles grew in a mosaic manner inside GO lamellae and were encapsulated with graphene.As a bifunctional catalyst,the r GO@SN-CoNi_(2)S_(4)exhibits excellent electrocatalytic performance under alkaline con-ditions,which only required the overpotential of 142.6 mV(vs.RHE)and 310 m V(vs.RHE)to deliver a current density of 10 mA·cm^(-2) for HER and OER,respectively.The good hydrophilicity of the r GO@SN,the pure phase of bimetallic structure,and the chemical coupling/interaction between the CoNi_(2)S_(4)and the rGO@SN are attributable to be the possible reasons responsible for the higher HER and OER catalytic activities.Additionally,the rGO@SN-CoNi_(2)S_(4)also shows a great potential for serving as an excellent cathode and anode electrolyzer during the water splitting process.展开更多
基金financial supports pro-vided by the National Natural Science Foundation of China(No.21905279)the Natural Science Foundation of Fujian Province(No.2020J05086).
文摘Small-sized Cd_(x) Zn_(1-x) S solid solution nanomaterial is an important candidate for efficient photocatalytic hydrogen evolution(PHE),but it still suffers from easy agglomeration,severe photo corrosion,and fast photogenerated electron-hole recombination.To tackle these issues,herein,we propose a new strategy to modify Cd_(x) Zn_(1-x) S nanoreactors by the simultaneous utilization of ionic-liquid-assisted morphology engineering and MXene-incorporating method.That is,we designed and synthesized a novel hierarchi-cal Cd_(0.8) Zn_(0.2) S/Ti_(3) C_(2) Schottky junction composite through the in-situ deposition of ultrathin Cd_(0.8) Zn_(0.2) S nanosheets on unique IL-modified Ti_(3) C_(2) MXenes by a one-pot solvothermal method for efficiently PHE.The unique construction strategy tailors the thickness of ultrathin Cd_(0.8) Zn_(0.2) S nanosheets and prevents them from stacking and agglomeration,and especially,optimizes their charge transfer pathways during the photocatalytic process.Compared with pristine Cd_(0.8) Zn_(0.2) S nanosheets,Cd_(0.8) Zn_(0.2) S/Ti_(3) C_(2) has abun-dant photogenerated electrons available on the Ti_(3) C_(2) surface for proton reduction reaction,owing to the absence of deep-trapped electrons,suppression of electron-hole recombination in Cd_(0.8) Zn_(0.2) S and high-efficiency charge separation at the Cd_(0.8) Zn_(0.2) S/Ti_(3) C_(2) Schottky junction interface.Moreover,the hy-drophilicity,electrical conductivity,visible-light absorption capacity,and surficial hydrogen desorption of Cd_(0.8) Zn_(0.2) S/Ti_(3) C_(2) heterostructure are significantly improved.As a result,the heterostructure exhibits out-standing photocatalytic stability and super high apparent quantum efficiency,being rendered as one of the best noble-metal-free Cd-Zn-S-based photocatalysts.This work illustrates the mechanisms of mor-phology control and heterojunction construction in controlling the catalytic behavior of photocatalysts and highlights the great potential of the IL-assisted route in the synthesis of high-performance MXene-based heterostructures for photocatalytic hydrogen evolution.
基金supported by the National Natural Science Foun-dation of China(No.62004143)the Key R&D Program of Hubei Province(No.2022BAA084)the Natural Science Foundation of Hubei Province(No.2021CFB133).
文摘Doping engineering is an effective strategy for graphitic carbon nitride(g-C_(3)N_(4))to improve its photocat-alytic hydrogen evolution reaction(HER)performance.In this work,a novel nitrogen and sulfur co-doped g-C_(3)N_(4)(N,S-g-C_(3)N_(4))is elaborately designed on the basis of theoretical predictions of first-principle density functional theory(DFT).The calculated Gibbs free energy of adsorbed hydrogen(ΔGH∗)for N,S-g-C_(3)N_(4) at the N-doping active sites is extremely close to zero(0.01 eV).Inspired by the theoretical predictions,the N,S-g-C_(3)N_(4) is successfully fabricated through ammonia-rich pyrolysis synthesis strategy,in which ammonia is in-situ obtained by pyrolyzing melamine.Subsequent characterizations indicate that the N,S-g-C_(3)N_(4) possesses high specific surface area,outstanding light utilization,good hydrophilicity,and efficient carrier transfer efficiency.Consequently,the N,S-g-C_(3)N_(4) displays an extremely high H2 evolution rate of 8269.9μmol g−1 h−1,achieves an apparent quantum efficiency(AQE)of 3.24%,and also possesses outsatnding durability.Theoretical calculations further demonstrate that N and S dopants can not only introduce doping energy level to reduce the band gap,but also induce charge redistribution to facilitate hydrogen adsorption,thus promoting the photocatalytic HER process.Moreover,femtosecond transient absorption(fs-TA)spectroscopy further corroborates the efficient photogenerated carrier transport of N,S-g-C_(3)N_(4).This research highlights a promising and reliable strategy to achieve superior photocatalytic activity,and exhibits significant guidance for precise designing high-efficiency photocatalysts.
文摘Streptococcus pneumoniae is a known notorious cause of invasive pneumococcal diseases as well as asymptomatic host carriage. Efforts have been made to curb this infectious organism through various vaccine strategies. However, its several strains and serotypes have necessitated various vaccine schedules and updates in the USA and globally. The evolution in pneumococcal vaccine schedules is not without challenges, such as cost, vaccine hesitancy, uptake and global disparities. This narrative review synopsizes the history of the Pneumococcal Vaccine and changes in its schedules in the last two decades based on published data. We focused on the impact of pneumococcal vaccination on invasive pneumococcal diseases, historical limitations, current challenges and future directions. Despite advancements in vaccination against S. pneumoniae infections, some pertinent issues exist that need to be swiftly fixed, to reduce national and thus global burden of pneumococcal diseases.
基金financially supported by Shandong Provincial Natural Science Foundation(No.ZR2024QB021)Qingdao Natural Science Foundation(No.24–4-4-zrjj-21-jch)National Natural Science Foundation of China(Nos.62204098,62304124,22309107)。
文摘Synchronously achieving morphological and electronic engineering control is crucial but challenging for enhancing the oxygen evolution reaction(OER)performance of nickel-iron based catalysts.Herein,a ruthenium and sulfur co-modified nickel-iron hydroxide(S_(A)Ru_(T)-FeNiOH_(x)-5h)was synthesized by a distributed room-temperature impregnation method.It was found that the solubility product difference between ruthenium and nickel-iron hydroxide can promote the rapid nucleation of the catalyst and form finer nanosheet structures,thereby increasing 1.25 times for the contact area between the catalyst and the electrolyte.Meanwhile,the subsequent deposition of sulfur can act as an electronic modulator,promoting the transfer of surface charge at nickel sites and increasing the oxidation state of nickel.Theoretical calculations indicate that the combination of ruthenium and sulfur can effectively optimize the OER reaction pathway and lower the activation energy barrier of the rate-determining step,endowing S_(A)Ru_(T)-FeNiOH_(x)-5h an excellent OER performance with a low overpotential of 253 mV at 1000 mA/cm^(2) and long-term stability(500 h).In the future,it is hoped that this strategy of synergistic control of morphology and electronic structure can be applied to the development of other highly active catalysts.
基金supported in part by the Science and Technology Major Special Project Fund of Changsha(No.kh2401010)in part by the High-Performance Computing Center of Central South University+3 种基金supported by the National Natural Science Foundation of China(Grants Nos.82022024,31970572)The Science and Technology Innovation Program of Hunan Province(2021RC4018,2021RC5027)Innovation-Driven Project of Central South University(Grant No.2020CX003)NIH grants U01 MH122591,1U01MH116489,1R01MH110920,R01MH126459.
文摘Detecting Alzheimer’s disease is essential for patient care,as an accurate diagnosis influences treatment options.Classifying dementia from non-dementia in brain MRIs is challenging due to features such as hippocampal atrophy,while manual diagnosis is susceptible to error.Optimal computer-aided diagnosis(CAD)systems are essential for improving accuracy and reducing misclassification risks.This study proposes an optimized ensemble method(CEOE-Net)that initiates with the selection of pre-trained models,including DenseNet121,ResNet50V2,and ResNet152V2 for unique feature extraction.Each selected model is enhanced with the inclusion of a channel attention(CA)block to improve the feature extraction process.In addition,this study employs the Short Time Fourier transform(STFT)technique with each individual model for hierarchical feature extraction before making final predictions in classifying MRI images of dementia and non-demented individuals,considering them as backbone models for building the ensemble method.STFT highlights subtle differences in brain structure and activity,particularly when combined with CA mechanisms that emphasize relevant features by converting spatial data into the frequency domain.The predictions generated from these models are then processed by the Chaotic Evolution Optimization(CEO)algorithm,which determines the optimal weightage set for each backbone model to maximize their contribution.The CEO optimizer explores weight distribution to ensure the most effective combination of model predictions for enhancing classification accuracy,thus significantly improving overall ensemble performance.This study utilized three datasets for validation:two private clinical brain MRI datasets(OSASIS and ADNI)to test the proposed model’s effectiveness.Image augmentation techniques were also employed to enhance dataset diversity and improve classification performance.The proposed CEOE-Net outperforms conventional baseline models and existing methods by showing its effectiveness as a clinical tool for the accurate classification of dementia and non-dementia MRI brain images,as well as autistic and non-autistic facial features.It achieved consistent accuracies of 93.44%on OSASIS and 81.94%on ADNI.
基金supported by the National Natural Science Foundation of China(No.62304219)the Strategic Priority Research Program of theChinese Academy of Sciences(No.XDB43000000)+1 种基金the CAS Project for Young Scientists in Basic Research(YSBR−090)the National Natural ScienceFoundation of China(Nos.21975245,U20A20206,and 51972300)。
文摘Functionalization has emerged as a pivotal endeavor to tailor the surface properties of photocatalysts.We propose a facile amine functionalization strategy to establish a Cu−In−Zn−S(CIZS)/NiSx hybrid with covalent bonds using individual ethylenediamine(EDA)molecules.Our approach witnesses a remarkable photocatalytic hydrogen evolution(PHE)competence of 65.93 mmol g^(−1)h^(−1)driven by visible light,the highest value yielded by CIZS to date.X-ray absorption spectra of CIZS and density functional theory(DFT)calculations confirm the crucial amine N→Cu coordination after amine functionalization.The new emerging coordination via lone-pair electron donation profitably accesses the regulation of the coordination environment,electronic structures,and carrier behavior.Moreover,individual EDA molecule with two-terminal−NH2 group serves as a molecular bridge to hybrid CIZS and NiS_(x)cocatalyst via N→Cu and N→Ni coordination,favorably promoting efficient charge transport.This study provides advances in practical functionalizing photocatalysts.
文摘Constructing S-scheme heterojunctions preserves the intrinsic redox capabilities of both semiconductors while promoting the separation of photogenerated electrons and holes,making it a promising approach for enhancing the properties of semiconductors.In this study,an S-scheme Cd_(0.8)Zn_(0.2)S-CeO_(2)(CZS-CeO_(2))heterojunction was successfully fabricated via the in-situ growth of CZS nanowires on CeO_(2)nanocubes.The S-scheme charge-transfer mechanism of the CZS-CeO_(2)composites during photocatalytic reactions was confirmed through in-situ X-ray photoelectron spectroscopy and density functional theory calculations.These results demonstrate that the interfacial electric field(IEF)significantly facilitates charge separation and transport within the heterojunction.Consequently,the CZS-CeO_(2)composites exhibited excellent photocatalytic hydrogen production performance under simulated sunlight irradiation,surpassing that of blank CZS.Particularly,the optimal photocatalytic hydrogen generation rate for CZS-15%CeO_(2)reached 58 mmol·g^(-1)·h^(-1),approximately 8.8 times higher than that of blank CZS.After five consecutive cycles of testing,CZS-15%CeO_(2)retained a relatively high level of activity.This enhanced stability can be attributed to the fabrication of S-scheme heterojunctions,which effectively suppressed hole-induced photocorrosion of CZS.This investigation provides a beneficial reference for the rational design of S-scheme heterojunction photocatalysts for efficient and stable photocatalytic hydrogen production.
基金supported by the National Natural Science Foundation of China(Nos.22378326,11974276,and 22078261)the Northwest University Graduate Student Innovation Project(No.CX2023155)+3 种基金the Natural Science Basic Research Program of Shaanxi Province(No.2023-JC-YB-115)the Shaanxi Key Science and Technology Innovation Team Project(No.2022TD-33)Qin Chuangyuan project of Shaanxi Province(No.QCYRCXM-2022-213)The Key Research and Development Program of Shaanxi Province(No.2024GX-YBXM-449).
文摘Effective separation of bulk phase and surface charges is crucial for maximizing charge utilization in the process of photocatalytic energy conversion.In this study,SnS_(2) nanoflowers and twinned Mn_(0.5) Cd_(0.5) S solid solution(T-MCS)nanoparticles were fabricated by a one-step solvothermal method respectively,fol-lowed by the formation of SnS_(2)/T-MCS nanohybrids through a facile physical solvent evaporation process for high-efficiency photocatalytic hydrogen(H_(2))production.The T-MCS crystal structure consists of alter-nating wurtzite Mn_(0.5) Cd_(0.5) S(WZ-MCS)and zinc blende Mn_(0.5) Cd_(0.5) S(ZB-MCS),forming a twin structure within the semiconductor.The charge migration mechanism between WZ-MCS and ZB-MCS follows the S-scheme pathway owing to slight differences in energy levels within their respective crystal structures,resulting in exceptional bulk phase charge separation capacity of T-MCS.Additionally,SnS_(2) enhances the electrochemical performance of the catalysts by providing more active sites,reducing charge transfer re-sistance and H_(2) production overpotential,thereby facilitating faster reaction kinetics.The photoelectro-chemical tests,radical trapping experiments,density functional theory(DFT),and electron paramagnetic resonance spectroscopy(EPR)confirm that the charge transfer path between SnS_(2) and T-MCS follows an S-type route that accelerates interfacial photo-induced electrons and holes separation while preserving useful charges.The synergistic impact of twinned homojunction and S-type heterojunction in 10 wt.%SnS_(2)/T-MCS composite contributes to a remarkable H_(2) production rate of 182.82 mmol h^(-1) g^(-1),which is 761.8 times higher than that achieved with SnS_(2) alone(0.24 mmol h^(-1) g^(-1)),as well as 5.8 times higher than that achieved with T-MCS alone(31.54 mmol h^(-1) g^(-1)).This study offers novel insights into design-ing highly efficient sulfide photocatalysts specifically targeting solar-driven H_(2) evolution through a dual S-scheme transfer pathway.
基金support from the National Key R&D Program of China(Grant Nos.2023YFB3709900 and 2023YFB3709903)the National Natural Science Foundation of China(Grant Nos.52174293 and U22A20171)+1 种基金the High Steel Center(HSC)at North China University of TechnologyUniversity of Science and Technology Beijing(USTB).
文摘MgO has been shown to facilitate the precipitation of MgO-rich crystalline phases within the MgO-CaO-Al_(2)O_(3)-SiO_(2)(MCAS)glassy inclusion system,which possesses a high liquidus temperature and a significant Young’s modulus.The underlying linkage between the structural evolution and the crystallization characteristics of the MCAS system was systematically investigated using molecular dynamics simulation and thermodynamic calculation.The results revealed that Mg^(2+) ions played a dual role,constructing networks through the formation of tricluster oxygens while consuming bridging oxygens(BOs)in a mechanism similar to Ca^(2+) ions.However,despite this dual role,the network connectivity was still decreased with the increase in MgO/(MgO+Al_(2)O_(3))(M/(M+A))and CaO/(CaO+SiO_(2))(C/(C+S))ratios,primarily due to the reduction in BOs.This microscopic structural evolution resulted in a reduction in viscosity and an enhancement of crystallization ability.Furthermore,the remarkable diffusion capability of Mg^(2+) ions,coupled with the increased proportion of 6-coordinated Mg^(2+)ions,unveiled the mechanism underlying the precipitation of MgSiO_(3) and Mg_(2)SiO_(4) crystals,which exhibited high Young’s moduli of 165.23 and 196.67 GPa,respectively.To prevent the precipitation of MgO-rich crystalline phases,it was crucial to maintain the M/(M+A)ratio below 0.42 and the C/(C+S)ratio below 0.16 within the MCAS system.
基金Supported by Natural Science Fund in Guangdong(915102600100-0003)Project for Excellent Young Scientists and Engineers in Guangdong Academy of Sciences(200804)Fund of Open Laboratory for Protection and Utilization of Wildlife in Guangdong(200901)~~
文摘[Objective]The aim was to prove that the mitochondrial genes of Cyt b and 12S rRNA with different evolutional rates have effects on the topological structures of phylogenetic trees.[Method]The complete sequences of Cyt b and 12S rRNA from 15 species in 12 families of snakes were downloaded and extracted from GenBank,while their molecular phylogenetic trees were constructed by Maximum Likelihood（ML） method with GTR ＋I ＋G substitute model based on PAUP4.0 software.[Result]With the same software,methods and species,the difference in topological structures of phylogenetic trees was mainly due to different evolutional rates of Cyt b and 12S rRNA genes.[Conclusion]In studies on phylogenetic trees,aimed to different research species and purposes,phylogenetic trees should be constructed by choosing the correct and appropriate genes.
基金financially supported by the National Natural Science Foundation of China (No. U1862105)the Natural Science Basic Research Plan in Shaanxi Province of China (Nos. 2017JZ001 and 2018KJXX-008)+2 种基金the Fundamental Research Funds for the Central Universities (No. cxtd2017004)the Science and Technology Project of Henan Province (No. 182106000029)he Key Research and Development Program of Shaanxi Province (No. 2018ZDCXL-SF-02-04)
文摘In this work,we designed and prepared the novel TiO2@ZnIn2 S4 nano-sized hollow structure via templating method assisted by hydrothermal synthesis process.Its unique hollow structure and type-II heterojunction between TiO2 hollow nanospheres and ZnIn2 S4 nanosheet can provide enough interior cavities and transfer paths for the light absorption and charge quick migration.The crystal structure,morphology and charges separation property were measured.The characterization results show that the hollow-structured Ti O2@ZnIn2 S4 was successfully prepared,and the optimal sample exhibited excellent photocatalytic hydrogen generation compared with TiO2/ZnIn2 S4 cluster exceeding by a factor of 1.1 under overall light irradiation.Specially,the detailed mechanism of the photocatalytic H2 evolution and charge carrier migration for the as-prepared TiO2@ZnIn2 S4 hollow nanosphere was also studied.
基金Project supported by the National Natural Science Foundation of China (Nos. 10932001,51079069 and 10572064)the National Basic Program of China (973 Program,2009CB623203)+1 种基金Ministry of Education of China (20103305110001)K.C. Wong Magna Fund in Ningbo University
文摘Experimental results about concrete under sulfate attack are summarized, which include the variation of mass density of samples and velocity of ultrasonic wave propagating in samples. The evolution damage is analyzed in terms of the experimental results, and close attention is paid to the effect of damage evolution on Poisson＇s ratio. This study shows that Poisson＇s ratio is significantly affected by the concentration of solution and water-cement ratio. Poisson＇s ratio of concrete changes very little when the water-cement ratio is selected as 0.6 or 0.8, so that such change may be neglected. If water-cement is 0.4, however, the Poisson＇s ratio of the sample significantly changes. When the concrete sample of 0.4 water-cement ratio is immersed in sodium sulfate solution of 8% concentration for 285 days, Poisson＇s ratio increase 10.14% compared with its initial value. There exist a sensitive region and a non-sensitive region for the change rate of Poisson＇s ratio with respect to corrosion time. The change rate of Poisson＇s ratio monotonously decreases with corrosion time in the sensitive region; in the non-sensitive region, the change rate of Poisson＇s ratio is almost equal to zero.
文摘Two-dimensional mesoporous ultrathin Cd0.5Zn0.5S nanosheets with a thickness of~1.5 nm were fabricated using a multistep chemical transformation strategy involving inorganic–organic hybrid ZnS-ethylenediamine(denoted as ZnS(en)0.5)as a hard template.Inorganic–organic hybrid ZnS(en)0.5,Cd0.5Zn0.5S(en)x,and Cd0.5Zn0.5S nanosheets were sequentially fabricated,and their transformation processes were analyzed in detail.The fabricated Cd0.5Zn0.5S nanosheets exhibited high photocatalytic hydrogen evolution reaction activity in the presence of a sacrificial agent.The Cd0.5Zn0.5S nanosheets exhibited remarkably high H2 production activity of~1395μmol∙h^−1∙g^−1 in pure water with no co-catalyst,which is the highest value reported thus far for bare photocatalysts,to the best of our knowledge.The high activity of these nanosheets is attributed to their distinct nanostructure(e.g.,short transfer distance of photoinduced charge carriers,large number of unsaturated surface atoms,and large surface area).Moreover,ternary NiCo2S4 nanoparticles were employed to facilitate the charge separation and enhance the surface kinetics of H2 evolution.The H2 production rate reached~62.2 and~2436μmol∙h^−1∙g^−1 in triethanolamine and pure water,respectively,over the NiCo2S4/Cd0.5Zn0.5S heterojunctions.The result indicated that the Schottky junction was critical to the enhanced activity.The proposed method can be used for fabricating other highly efficient CdZnS-based photocatalysts for solar-energy conversion or other applications.
文摘The evolution of precipitates of S31042 steel during 700 ℃ aging was investigated by using a scanning elec- tron microscope, a transmission electron microscope, and electron energy spectrum technology. The various combi nations of M23C6, MX, NbCrN, and σ and G phases in the steel were found at different aging states. In the begin ning of aging, M23C6 precipitates swiftly along the grain boundaries. When the aging time exceeds 6 000 h, precipita- ted M23C6 carbides along the grain boundaries turn to be granular. It was found that Si element segregates to grain boundaries during above process, which may enhance the granular shape of M23C6 carbides and its transformation to and G phases. When the aging time exceeds 10 000 h, various shaped a phase and granular G phase appear along the grain boundaries and there are no continuous M23C6 carbides along the grain boundaries. Meanwhile, a large quantity of granular M23C6 carbides and a minor amount of G phase precipitate near the grain boundaries. Based on the segre- gation of silicon to the grain boundaries, a precipitation evolution model during aging was concluded.
基金financially supported by Guangdong Basic and Applied Basic Research Foundation (Nos. 2020A1515110473 and 2019A1515110528)。
文摘Designing highly active and stable electrocata-lysts for hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)is a challenge for energy con-version and storage technology.In this work,a S and N co-doped graphene supported cobalt–nickel sulfide composite catalyst(rGO@SN-CoNi_(2)S_(4))was synthesized simply via a one-step hydrothermal method.The as-synthesized CoNi_(2)S_(4)particles grew in a mosaic manner inside GO lamellae and were encapsulated with graphene.As a bifunctional catalyst,the r GO@SN-CoNi_(2)S_(4)exhibits excellent electrocatalytic performance under alkaline con-ditions,which only required the overpotential of 142.6 mV(vs.RHE)and 310 m V(vs.RHE)to deliver a current density of 10 mA·cm^(-2) for HER and OER,respectively.The good hydrophilicity of the r GO@SN,the pure phase of bimetallic structure,and the chemical coupling/interaction between the CoNi_(2)S_(4)and the rGO@SN are attributable to be the possible reasons responsible for the higher HER and OER catalytic activities.Additionally,the rGO@SN-CoNi_(2)S_(4)also shows a great potential for serving as an excellent cathode and anode electrolyzer during the water splitting process.
