Rare-earth hexaborides(REB_(6))are vital raw materials for cathode materials and high temperature structural ceramics that are widely applied as high-frequency electron tubes and ceramics adaptive for extreme environm...Rare-earth hexaborides(REB_(6))are vital raw materials for cathode materials and high temperature structural ceramics that are widely applied as high-frequency electron tubes and ceramics adaptive for extreme environment,respectively.In this work,single phase substitutional solid solution REB_(6)(LaB_(6),La_(0.75)Ce_(0.25)B_(6).La_(0.5)Ce_(0.5)B_(6),La_(0.25)Ce_(0.75)B_(6) and CeB_(6))powders were prepared with the raw materials of La_(2)O_(3),CeO_(2),B_(4)C and Al powders,after calcining at 1773 K for 4 h and the following alkaline leaching.All substitutional solid solution products have homogeneous distributions of La and Ce in particles.Through microscopic morphology analysis,it is discovered that the formation of solid solution is beneficial for reducing the particle size of product,relative to LaB_(6) and CeB_(6).Moreover,Al flux plays an important role in decarbonizing reaction,and C contents of all products are below 0.4 wt%.展开更多
This paper reviews recent research on ductility improvement of B-undoped Ni_3Al alloys.Ni_3Al binary alloys with hypostoichiometric compositions show appreciable ductility at room temperature when the samples are prep...This paper reviews recent research on ductility improvement of B-undoped Ni_3Al alloys.Ni_3Al binary alloys with hypostoichiometric compositions show appreciable ductility at room temperature when the samples are prepared by recrystallization annealing after cold pressing,although the alloys with stoichiometric and hyperstoichiometric compositions remain brittle.Melt-spun ribbons with hypostoichiometric compositions contain fine anti-phase domains (APDs),while no APD can be seen in melt-spun ribbons with a hyperstoichiometric composition.The ductility in hypostoichiometric Ni_3Al alloys is associated with low ordering energy of the alloys.The addition of ternary elements,which have been classified as γ formers such as Pd,Pt,Cu,Co and Ag.improves ductility of Ni_3Al alloys.Correspondingly,the microstructure of the melt-spun ribbons consists of fine APDs.The addition of γ' formers such as Si,Ti,Zr,V,Nb and Ta leads to brittle intergranular frac- ture.No APD was observed in the melt-spun ribbons of these ternary alloys.展开更多
Based on ab initio calculations,it is found that the donor center of substitutional sulfur(S)in diamond with C2v symmetry is more stable than that with C3vsymmetry,which is different from previous reports in literatur...Based on ab initio calculations,it is found that the donor center of substitutional sulfur(S)in diamond with C2v symmetry is more stable than that with C3vsymmetry,which is different from previous reports in literature.The energy difference of C2vand C3vstructures is qualitatively affected by the supercell size,and the 216-atom supercell could be proposed as the minimum to obtain stable configuration of substitutional S in diamond.Using supercells of up to 512 atoms,the donor level of substitutional S with C2vsymmetry is deep.展开更多
A model for describing solute segregation at grain boundaries has been developed for substitutional solid solution alloys,which integrates multiple factors from atomic to microstructural scales.A concept of mo-lar Gib...A model for describing solute segregation at grain boundaries has been developed for substitutional solid solution alloys,which integrates multiple factors from atomic to microstructural scales.A concept of mo-lar Gibbs free energy of segregation was introduced to evaluate the segregating capability of the solute elements in a closed system,through which the influences of grain boundary structure,grain size,ma-terial composition,and external conditions were described.Based on the evaluation of various energy forms related to solute segregation and grain growth processes,the nature of the thermal stabilization of nanograin structures by solute segregation was disclosed.A criterion for the destabilization of nanostruc-tures,which is determined by the competition of the change rates between the molar Gibbs free energy of segregation and the total energy of grain boundaries with grain size,has been proposed.This study provided guideline to achieve high-temperature stability of nanograin structures of solid solution alloys even for the weakly segregating nanocrystalline systems.展开更多
Using first-principles calculations based on density functional theory,we show that the ground state of zigzag-edged graphene nanoribbons(ZGNRs)can be transformed from antiferromagnetic(AFM)order to ferromagnetic(FM)o...Using first-principles calculations based on density functional theory,we show that the ground state of zigzag-edged graphene nanoribbons(ZGNRs)can be transformed from antiferromagnetic(AFM)order to ferromagnetic(FM)order by changing the substitutional sites of N or B dopants.This AFM–FM transition induced by substitutional sites is found to be a consequence of the competition between the edge and bulk states.The energy sequence of the edge and bulk states near the Fermi level is reversed in the AFM and FM configurations.When the dopant is substituted near the edge of the ribbon,the extra charge from the dopant is energetically favorable to occupy the edge states in AFM configuration.When the dopant is substituted near the center,the extra charge is energetically favorable to occupy the bulk states in FM configuration.Proper substrate with weak interaction is necessary to maintain the magnetic properties of the doped ZGNRs.Our study can serve as a guide to synthesize graphene nanostructures with stable FM order for future applications to spintronic devices.展开更多
Transition metal dichalcogenides(TMDs)are a promising class of layered materials in the post-graphene era,with extensive research attention due to their diverse alternative elements and fascinating semiconductor behav...Transition metal dichalcogenides(TMDs)are a promising class of layered materials in the post-graphene era,with extensive research attention due to their diverse alternative elements and fascinating semiconductor behavior.Binary MX2 layers with different metal and/or chalcogen elements have similar structural parameters but varied optoelectronic properties,providing opportunities for atomically substitutional engineering via partial alteration of metal or/and chalcogenide atoms to produce ternary or quaternary TMDs.The resulting multinary TMD layers still maintain structural integrity and homogeneity while achieving tunable(opto)electronic properties across a full range of composition with arbitrary ratios of introduced metal or chalcogen to original counterparts(0–100%).Atomic substitution in TMD layers offers new adjustable degrees of freedom for tailoring crystal phase,band alignment/structure,carrier density,and surface reactive activity,enabling novel and promising applications.This review comprehensively elaborates on atomically substitutional engineering in TMD layers,including theoretical foundations,synthetic strategies,tailored properties,and superior applications.The emerging type of ternary TMDs,Janus TMDs,is presented specifically to highlight their typical compounds,fabrication methods,and potential applications.Finally,opportunities and challenges for further development of multinary TMDs are envisioned to expedite the evolution of this pivotal field.展开更多
Two-dimensional(2D)van der Waals transition metal dichalcogenides(TMDs)are a new class of electronic materials offering tremendous opportunities for advanced technologies and fundamental studies.Similar to conventiona...Two-dimensional(2D)van der Waals transition metal dichalcogenides(TMDs)are a new class of electronic materials offering tremendous opportunities for advanced technologies and fundamental studies.Similar to conventional semiconductors,substitutional doping is key to tailoring their electronic properties and enabling their device applications.Here,we review recent progress in doping methods and understanding of doping effects in group 6 TMDs(MX2,M=Mo,W;X=S,Se,Te),which are the most widely studied model 2D semiconductor system.Experimental and theoretical studies have shown that a number of different elements can substitute either M or X atoms in these materials and act as n-or p-type dopants.This review will survey the impact of substitutional doping on the electrical and optical properties of these materials,discuss open questions,and provide an outlook for further studies.展开更多
Substitutional atomic doping of transition metal dichalcogenides(TMDs)in the chemical vapor deposition(CVD)process is a promising and effective strategy for modifying their physicochemical properties.However,the conve...Substitutional atomic doping of transition metal dichalcogenides(TMDs)in the chemical vapor deposition(CVD)process is a promising and effective strategy for modifying their physicochemical properties.However,the conventional CVD method only allows narrow-range modulation of the dopant concentration owing to the low reactivity of the precursors.Moreover,the growth of wafer-scale monolayer TMD films with high dopant concentrations is much more challenging.Herein,we report a facile doping approach based on liquid precursor-mediated CVD process for achieving high vanadium(V)doping in the MoS_(2)lattice with excellent doping uniformity and stability.The lateral growth of the host MoS_(2)lattice and the reactivity of the V precursor were simultaneously improved by introducing an alkali metal halide as a reaction promoter.The metal halide promoter enabled the wafer-scale synthesis of V-incorporated MoS_(2)monolayer film with excessively high doping concentrations.The excellent wafer-scale uniformity of the highly V-doped MoS_(2)film was confirmed through a series of microscopic,spectroscopic,and electrical analyses.展开更多
Neutron-transmutation doping(NTD)has been demonstrated for the first time in this work for substitutional introduction of tin(Sn)shallow donors into two-dimensional(2D)layered indium selenide(InSe)to manipulate electr...Neutron-transmutation doping(NTD)has been demonstrated for the first time in this work for substitutional introduction of tin(Sn)shallow donors into two-dimensional(2D)layered indium selenide(InSe)to manipulate electron transfer and charge carrier dynamics.Multidisciplinary study including density functional theory,transient optical absorption,and FET devices have been carried out to reveal that the field effect electron mobility of the fabricated phototransistor is increased 100-fold due to the smaller electron effective mass and longer electron life time in the Sn-doped InSe.The responsivity of the Sn-doped InSe based phototransistor is accordingly enhanced by about 50 times,being as high as 397 A/W.The results show that NTD is a highly effective and controllable doping method,possessing good compatibility with the semiconductor manufacturing process,even after device fabrication,and can be carried out without introducing any contamination,which is radically different from traditional doping methods.展开更多
Photofragmentation study of metal fullerides C60Mx (M=Sm, Pt, Ni and Rh) by excimer laser ablation-TOF mass spectrometry shows that metallofullerenes C2nM and C2n+1M formed in both the positive and negative ionic mode...Photofragmentation study of metal fullerides C60Mx (M=Sm, Pt, Ni and Rh) by excimer laser ablation-TOF mass spectrometry shows that metallofullerenes C2nM and C2n+1M formed in both the positive and negative ionic modes. The isotopic distributions of the metallofullerenes C2nM and C2n+1M are consistent with the calculated spectra based on the natural abundance of isotopes of C and M, confirming the formation of metallofullerenes. The metal atom is sup-posed to be incorporated into the network of the fullerene cage to replace one carbon atom of the cage forming substi-tutional metallofullerene. Odd-numbered high carbon clusters are observed in our laser ablation study of all the metal fullerides in the negative ion channel. Evolution of mass spectrum with irradiation laser shots shows that the formation of the substitutionally doped fullerenes is closely related to the production of metal carbide (MC). The structures, as well as formation mechanism, of metallofullerenes C2n+1M and C2nM with even and odd展开更多
On account of the integral behavior of dislocations and the interaction between solute atoms and dislocations, a model describing the serrated yielding (i.e. the PL effect) in substitutional alloys is proposed. Accord...On account of the integral behavior of dislocations and the interaction between solute atoms and dislocations, a model describing the serrated yielding (i.e. the PL effect) in substitutional alloys is proposed. According to this model, the serrated yielding occurring in a certain strain rate-temperature range will disappear when the strain exceeds a proper value under certain conditions. The model has been confirmed by tensile tests and rapid changing strain rate tests on a commercial Cu-32wt.％ Zn alloy. Experimental results agree well with the predicted effects of temperature and strain rate on the critical strain for the appearance and disappearance of serrations.展开更多
Elliptic curve(EC)based cryptosystems gained more attention due to enhanced security than the existing public key cryptosystems.A substitution box(S-box)plays a vital role in securing modern symmetric key cryptosystem...Elliptic curve(EC)based cryptosystems gained more attention due to enhanced security than the existing public key cryptosystems.A substitution box(S-box)plays a vital role in securing modern symmetric key cryptosystems.However,the recently developed EC based algorithms usually trade off between computational efficiency and security,necessitating the design of a new algorithm with the desired cryptographic strength.To address these shortcomings,this paper proposes a new scheme based onMordell elliptic curve(MEC)over the complex field for generating distinct,dynamic,and highly uncorrelated S-boxes.Furthermore,we count the exact number of the obtained S-boxes,and demonstrate that the permuted version of the presented S-box is statistically optimal.The nonsingularity of the presented algorithm and the injectivity of the resultant output are explored.Rigorous theoretical analysis and experimental results demonstrate that the proposedmethod is highly effective in generating a large number of dynamic S-boxes with adequate cryptographic properties,surpassing current state-of-the-art S-box generation algorithms in terms of security.Apart fromthis,the generated S-box is benchmarked using side-channel attacks,and its performance is compared with highly nonlinear S-boxes,demonstrating comparable results.In addition,we present an application of our proposed S-box generator by incorporating it into an image encryption technique.The encrypted and decrypted images are tested by employing extensive standard security metrics,including the Number of Pixel Change Rate,the Unified Average Changing Intensity,information entropy,correlation coefficient,and histogram analysis.Moreover,the analysis is extended beyond conventional metrics to validate the new method using advanced tests,such as the NIST statistical test suite,robustness analysis,and noise and cropping attacks.Experimental outcomes show that the presented algorithm strengthens the existing encryption scheme against various well-known cryptographic attacks.展开更多
Violet phosphorus,a recently explored layered elemental semiconductor,has attracted much attention due to its unique photoelectric,mechanical properties,and high hole mobility.Herein,violet arsenic phosphorus has for ...Violet phosphorus,a recently explored layered elemental semiconductor,has attracted much attention due to its unique photoelectric,mechanical properties,and high hole mobility.Herein,violet arsenic phosphorus has for the first time been synthesized by a molten lead method.The crystal structure of violet arsenic phosphorus(P^(83.4)As_(0.6),CSD-2408761)was determined by single crystal X-ray diffraction to have similar structure as that of violet phosphorus,where P12 is occupied by arsenic/phosphorus(As/P)atoms as mixed occupancy sites As1/P12.The arsenic substitution has been demonstrated to tune the band structure of violet phosphorus,switching p-type of violet phosphorus to high-performance n-type violet arsenic phosphorus.The effective electron mass along the<010>direction is significantly reduced from 1.792 to 0.515 m_(0)by arsenic substitution,resulting in an extremely high electron mobility of 2622.503 cm^(2)V^(-1)s^(-1).The field effect transistor built with P_(83.4)As_(0.6)nanosheets was measured to have a high electron mobility(137.06 cm^(2)V^(-1)s^(-1),61.2 nm),even under ambient conditions for 5 h,much higher than the hole mobility of violet phosphorene nanosheets(4.07 cm^(2)V^(-1)s^(-1),73.3 nm).This work provides a new idea for designing phosphorus-based materials for field effect transistors,giving significant potential in complementary metal-oxide-semiconductor applications.展开更多
Thinopyrum ponticum(2n=10×=70),a wild relative of common wheat(Triticum aestivum L.),is considered an invaluable genetic resource for wheat improvement due to its abundance of genes conferring resistance to bioti...Thinopyrum ponticum(2n=10×=70),a wild relative of common wheat(Triticum aestivum L.),is considered an invaluable genetic resource for wheat improvement due to its abundance of genes conferring resistance to biotic and abiotic stresses.This study focused on the CH97 line,derived from the BC1F7 progeny of a cross between wheat cv.7182 and Th.ponticum.Cytological evidence showed that CH97 has 42 chromosomes,forming 21 bivalents at meiotic metaphase I,with the bivalents subsequently separating and moving to opposite poles during meiotic anaphase I.Through a combination of fluorescence in situ hybridization(FISH),genomic in situ hybridization(GISH),multicolor GISH(mc-GISH),and liquid array analysis,it was determined that CH97 comprises 40 wheat chromosomes and two alien chromosomes from the Ee genome of Th.ponticum,featuring the absence of a pair of 5D chromosomes and variations in 1B,6B,and 7B chromosomes.These findings confirm that CH97 is a stable wheat-Th.ponticum 5E(5D)alien disomic substitution line.Inoculation experiments revealed that CH97 exhibits high resistance to wheat powdery mildew and stripe rust throughout the growth period,in contrast to the highly susceptible common wheat parent 7182.Compared to 7182,CH97 displayed improvements in thousand-kernel weight and kernel length.Additionally,utilizing specific-locus amplified fragment sequencing(SLAF-seq)technology,chromosome 5E-specific molecular markers were developed and validated,achieving a 33.3% success rate,facilitating marker-assisted selection for disease resistance in wheat.Overall,the CH97 substitution line,with its resistance to diseases and improved agronomic traits,represents valuable new germplasm for wheat chromosome engineering and breeding.展开更多
Background:The phenomenon of multimorbidity in chronic diseases among the elderly is prevalent,and its significant association with depression poses a serious threat to the physical and mental health of older adults.C...Background:The phenomenon of multimorbidity in chronic diseases among the elderly is prevalent,and its significant association with depression poses a serious threat to the physical and mental health of older adults.Current research on the associations between 24-hour movement behaviors(including physical activity,sedentary behavior,and sleep)and depression has largely been confined to examining the effects of single behaviors,overlooking the intrinsic compositional nature and interrelationships among these behaviors.Therefore,it is necessary to investigate the integrated effects of 24-hour movement behaviors on depression in older adults with multimorbidity from a holistic,compositional perspective.Methods:From November 2024 to April 2025,a total of 226 older adult patients with multimorbidity were recruited from a tertiary hospital in Changzhou City.Data were collected using a general information questionnaire,the International Physical Activity Questionnaire–Short Form(IPAQ-SF),the Pittsburgh Sleep Quality Index(PSQI),and the Patient Health Questionnaire-9(PHQ-9).Compositional data analysis and isotemporal substitution models were employed for statistical analysis.Results:The mean daily durations of Light-Intensity Physical Activity(LPA),Moderate-to-Vigorous Physical Activity(MVPA),Sedentary Behavior(SB),and Sleep(SLP)in older adults with multimorbidity were 402.48 min,12.04 min,511.52 min,and 458.68 min,respectively.The prevalence of depressive symptoms was 37.6%.Compositional data analysis revealed that SB was positively associated with depression(βSB=1.005,P=0.006),while SLP was negatively associated with depression(βSLP=−1.736,P<0.001).No statistically significant associations were found between MVPA or LPA and depression(P>0.05).In the 10-minute isotemporal substitution model,replacing SB with any other behavioral component was associated with a decrease in depression scores.Conversely,substituting SLP with either LPA or SB resulted in an increase in depression scores,while substituting SLP with MVPA led to a decrease in depression scores.The dose-response analysis revealed that,among the isotemporal substitution effects,replacing SB with SLP and replacing SLP with MVPA were the substitution pathways associated with the most rapid decline in depression scores,representing the greatest beneficial health effects.Conclusion:The prevalence of depression is notably high among older adults with multimorbidity.Reducing daily sedentary behavior(SB),maintaining adequate sleep(SLP),and increasing moderate-to-vigorous physical activity(MVPA)can improve depressive symptoms and enhance overall health in this population.展开更多
Benzoic acid containing fluorine atom at ortho-,meta-,and para-position are employed as self-assembled monolayers to modify the buried interface in perovskite solar cells(PSCs).It is demonstrated that the position of ...Benzoic acid containing fluorine atom at ortho-,meta-,and para-position are employed as self-assembled monolayers to modify the buried interface in perovskite solar cells(PSCs).It is demonstrated that the position of fluorine atom influences the passivation effect and para-fluorinated one provided the most substantial performance enhancement mainly originating from ameliorated contact and energy band alignment between NiOx and perovskite,improved perovskite quality and defect healing.Resultantly,PSC with a power conversion efficiency of 24%can be achieved.Meanwhile,which can maintain 96.8%of the initial PCE after a 1000 h storage,presenting enhanced durability.This work highlights the critical role of molecular functionality and conformation in the buried interface modification of PSCs,providing valuable insights for future developments.展开更多
Heteroatom substitution has been investigated to be a feasible way to optimize microwave absorption properties of core-shell structural nanocapsules at gigahertz.Although dielectric capacity has been increased at spec...Heteroatom substitution has been investigated to be a feasible way to optimize microwave absorption properties of core-shell structural nanocapsules at gigahertz.Although dielectric capacity has been increased at specific frequency with substituted absorbents,its broadband absorption performance is still relatively poor ascribed to the low dipole oscillation amplitude of single substituted heteroatom.In this study we demonstrate that sulfur and oxygen co-substituted heterostructure leads to high microwave absorption property of core-shell structural Fe@C nanocapsules at broadened frequency range,comparable to the single sulfur substitutional Fe@C nanocapsules.Experimental characterizations coupled with first-principles calculations reveal that the microwave absorption enhancement is triggered by the sulfur-oxygen co-substitution,which results in the serious symmetry breaking and thus leads to the charge separation at the co-substituted area.In particular,the nanocapsules exhibt the minimum reflection loss capcacity R(d B)of-52 d B at 6.8 GHz and the bandwith for R(d B)<-20 dB is in the frequency range of 3.1-12.7 GHz.The present study not only offers a deep insight into the relationship between heteroatom and microwave absorption property,but also puts forward a mentality for further designing microwave absorbents.展开更多
A medical image encryption is proposed based on the Fisher-Yates scrambling,filter diffusion and S-box substitution.First,chaotic sequence associated with the plaintext is generated by logistic-sine-cosine system,whic...A medical image encryption is proposed based on the Fisher-Yates scrambling,filter diffusion and S-box substitution.First,chaotic sequence associated with the plaintext is generated by logistic-sine-cosine system,which is used for the scrambling,substitution and diffusion processes.The three-dimensional Fisher-Yates scrambling,S-box substitution and diffusion are employed for the first round of encryption.The chaotic sequence is adopted for secondary encryption to scramble the ciphertext obtained in the first round.Then,three-dimensional filter is applied to diffusion for further useful information hiding.The key to the algorithm is generated by the combination of hash value of plaintext image and the input parameters.It improves resisting ability of plaintext attacks.The security analysis shows that the algorithm is effective and efficient.It can resist common attacks.In addition,the good diffusion effect shows that the scheme can solve the differential attacks encountered in the transmission of medical images and has positive implications for future research.展开更多
The practical application of aqueous zinc-ion batteries(AZIBs)is primarily constrained by issues such as corrosion,zinc dendrite formation,and the hydrogen evolution reaction occurring at the zinc metal anode.To overc...The practical application of aqueous zinc-ion batteries(AZIBs)is primarily constrained by issues such as corrosion,zinc dendrite formation,and the hydrogen evolution reaction occurring at the zinc metal anode.To overcome these challenges,strategies for optimizing the electrolyte are crucial for enhancing the stability of the zinc anode.Inspired by the role of hemoglobin in blood cells,which facilitates oxygen transport during human respiration,an innovative inorganic colloidal electrolyte has been developed:calcium silicate-ZnSO_(4)(denoted as CS-ZSO).This electrolyte operates in weak acidic environment and releases calcium ions,which participate in homotopic substitution with zinc ions,while the solvation environment of hydrated zinc ions in the electrolyte is regulated.The reduced energy barrier for the transfer of zinc ions and the energy barrier for the desolvation of hydrated ions imply faster ion transfer kinetics and accelerated desolvation processes,thus favoring the mass transfer process.Furthermore,the silicate colloidal particles act as lubricants,improving the transfer of zinc ions.Together,these factors contribute to the more uniform concentration of zinc ions at the electrode/electrolyte interface,effectively inhibiting zinc dendrite formation and reducing by-product accumulation.The Zn//CS-ZSO//Zn symmetric cell demonstrates stable operation for over 5000 h at 1 mA cm^(-2),representing 29-fold improvement compared to the Zn//ZSO//Zn symmetric cell,which lasts only 170 h.Additionally,the Zn//CS-ZSO//Cu asymmetric cell shows stable average Coulombic efficiency(CE)exceeding 99.6%over2400 cycles,significantly surpassing the performance of the ZSO electrolyte.This modification strategy for electrolytes not only addresses key limitations associated with zinc anodes but also provides valuable insights into stabilizing anodes for the advancement of high-performance aqueous zinc-ion energy storage systems.展开更多
基金financially supported by State Key Laboratory of Advanced Metallurgy,University of Science and Technology Beijing,China。
文摘Rare-earth hexaborides(REB_(6))are vital raw materials for cathode materials and high temperature structural ceramics that are widely applied as high-frequency electron tubes and ceramics adaptive for extreme environment,respectively.In this work,single phase substitutional solid solution REB_(6)(LaB_(6),La_(0.75)Ce_(0.25)B_(6).La_(0.5)Ce_(0.5)B_(6),La_(0.25)Ce_(0.75)B_(6) and CeB_(6))powders were prepared with the raw materials of La_(2)O_(3),CeO_(2),B_(4)C and Al powders,after calcining at 1773 K for 4 h and the following alkaline leaching.All substitutional solid solution products have homogeneous distributions of La and Ce in particles.Through microscopic morphology analysis,it is discovered that the formation of solid solution is beneficial for reducing the particle size of product,relative to LaB_(6) and CeB_(6).Moreover,Al flux plays an important role in decarbonizing reaction,and C contents of all products are below 0.4 wt%.
文摘This paper reviews recent research on ductility improvement of B-undoped Ni_3Al alloys.Ni_3Al binary alloys with hypostoichiometric compositions show appreciable ductility at room temperature when the samples are prepared by recrystallization annealing after cold pressing,although the alloys with stoichiometric and hyperstoichiometric compositions remain brittle.Melt-spun ribbons with hypostoichiometric compositions contain fine anti-phase domains (APDs),while no APD can be seen in melt-spun ribbons with a hyperstoichiometric composition.The ductility in hypostoichiometric Ni_3Al alloys is associated with low ordering energy of the alloys.The addition of ternary elements,which have been classified as γ formers such as Pd,Pt,Cu,Co and Ag.improves ductility of Ni_3Al alloys.Correspondingly,the microstructure of the melt-spun ribbons consists of fine APDs.The addition of γ' formers such as Si,Ti,Zr,V,Nb and Ta leads to brittle intergranular frac- ture.No APD was observed in the melt-spun ribbons of these ternary alloys.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11704143,51672102,51632002,and 11604023)the National Key Research and Development Program of China(Grant Nos.2018YFA0305900 and 2016YFB0201204)the Program for Changjiang Scholars and Innovative Research Team in University(Grant No.IRT-15R23)
文摘Based on ab initio calculations,it is found that the donor center of substitutional sulfur(S)in diamond with C2v symmetry is more stable than that with C3vsymmetry,which is different from previous reports in literature.The energy difference of C2vand C3vstructures is qualitatively affected by the supercell size,and the 216-atom supercell could be proposed as the minimum to obtain stable configuration of substitutional S in diamond.Using supercells of up to 512 atoms,the donor level of substitutional S with C2vsymmetry is deep.
基金supported by the Beijing Natural Science Foun-dation(No.2214067)the National Key R&D Program of China(Nos.2021YFB3501502 and 2021YFB3501504)the National Natural Science Foundation of China(No.92163107).
文摘A model for describing solute segregation at grain boundaries has been developed for substitutional solid solution alloys,which integrates multiple factors from atomic to microstructural scales.A concept of mo-lar Gibbs free energy of segregation was introduced to evaluate the segregating capability of the solute elements in a closed system,through which the influences of grain boundary structure,grain size,ma-terial composition,and external conditions were described.Based on the evaluation of various energy forms related to solute segregation and grain growth processes,the nature of the thermal stabilization of nanograin structures by solute segregation was disclosed.A criterion for the destabilization of nanostruc-tures,which is determined by the competition of the change rates between the molar Gibbs free energy of segregation and the total energy of grain boundaries with grain size,has been proposed.This study provided guideline to achieve high-temperature stability of nanograin structures of solid solution alloys even for the weakly segregating nanocrystalline systems.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11474274 and 61427901)the National Basic Research Program of China(Grant No.2014CB643902)
文摘Using first-principles calculations based on density functional theory,we show that the ground state of zigzag-edged graphene nanoribbons(ZGNRs)can be transformed from antiferromagnetic(AFM)order to ferromagnetic(FM)order by changing the substitutional sites of N or B dopants.This AFM–FM transition induced by substitutional sites is found to be a consequence of the competition between the edge and bulk states.The energy sequence of the edge and bulk states near the Fermi level is reversed in the AFM and FM configurations.When the dopant is substituted near the edge of the ribbon,the extra charge from the dopant is energetically favorable to occupy the edge states in AFM configuration.When the dopant is substituted near the center,the extra charge is energetically favorable to occupy the bulk states in FM configuration.Proper substrate with weak interaction is necessary to maintain the magnetic properties of the doped ZGNRs.Our study can serve as a guide to synthesize graphene nanostructures with stable FM order for future applications to spintronic devices.
基金This work was supported by National Key R&D Program of China(2021YFF1200200)Peiyang Talents Project of Tianjin University.
文摘Transition metal dichalcogenides(TMDs)are a promising class of layered materials in the post-graphene era,with extensive research attention due to their diverse alternative elements and fascinating semiconductor behavior.Binary MX2 layers with different metal and/or chalcogen elements have similar structural parameters but varied optoelectronic properties,providing opportunities for atomically substitutional engineering via partial alteration of metal or/and chalcogenide atoms to produce ternary or quaternary TMDs.The resulting multinary TMD layers still maintain structural integrity and homogeneity while achieving tunable(opto)electronic properties across a full range of composition with arbitrary ratios of introduced metal or chalcogen to original counterparts(0–100%).Atomic substitution in TMD layers offers new adjustable degrees of freedom for tailoring crystal phase,band alignment/structure,carrier density,and surface reactive activity,enabling novel and promising applications.This review comprehensively elaborates on atomically substitutional engineering in TMD layers,including theoretical foundations,synthetic strategies,tailored properties,and superior applications.The emerging type of ternary TMDs,Janus TMDs,is presented specifically to highlight their typical compounds,fabrication methods,and potential applications.Finally,opportunities and challenges for further development of multinary TMDs are envisioned to expedite the evolution of this pivotal field.
基金the Ministry of Education(MOE),Singapore,under AcRF Tier 3(MOE2018-T3-1-005)the Singapore National Research Foundation for funding the research under medium-sized centre programme.M.B.acknowledges support from MOE’s AcRF Tier 1(R-284-000-179-133).
文摘Two-dimensional(2D)van der Waals transition metal dichalcogenides(TMDs)are a new class of electronic materials offering tremendous opportunities for advanced technologies and fundamental studies.Similar to conventional semiconductors,substitutional doping is key to tailoring their electronic properties and enabling their device applications.Here,we review recent progress in doping methods and understanding of doping effects in group 6 TMDs(MX2,M=Mo,W;X=S,Se,Te),which are the most widely studied model 2D semiconductor system.Experimental and theoretical studies have shown that a number of different elements can substitute either M or X atoms in these materials and act as n-or p-type dopants.This review will survey the impact of substitutional doping on the electrical and optical properties of these materials,discuss open questions,and provide an outlook for further studies.
基金supported by Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Korea government(MSIT)(Nos.2019R1A2C1009025 and 2022R1A4A2000823)2022 research Fund(No.1.220024.01)of Ulsan National Institute of Science&Technology(UNIST).
文摘Substitutional atomic doping of transition metal dichalcogenides(TMDs)in the chemical vapor deposition(CVD)process is a promising and effective strategy for modifying their physicochemical properties.However,the conventional CVD method only allows narrow-range modulation of the dopant concentration owing to the low reactivity of the precursors.Moreover,the growth of wafer-scale monolayer TMD films with high dopant concentrations is much more challenging.Herein,we report a facile doping approach based on liquid precursor-mediated CVD process for achieving high vanadium(V)doping in the MoS_(2)lattice with excellent doping uniformity and stability.The lateral growth of the host MoS_(2)lattice and the reactivity of the V precursor were simultaneously improved by introducing an alkali metal halide as a reaction promoter.The metal halide promoter enabled the wafer-scale synthesis of V-incorporated MoS_(2)monolayer film with excessively high doping concentrations.The excellent wafer-scale uniformity of the highly V-doped MoS_(2)film was confirmed through a series of microscopic,spectroscopic,and electrical analyses.
基金State Key Research Development Program of China(Grant No.2019YFB2203503)National Natural Science Fund(Grant Nos.61875138,61961136001,62104153,62105211 and U1801254)+2 种基金Natural Science Foundation of Guangdong Province(2018B030306038 and 2020A1515110373)Science and Technology Innovation Commission of Shenzhen(JCYJ20180507182047316 and 20200805132016001)Postdoctoral Science Foundation of China(No.2021M702237)。
文摘Neutron-transmutation doping(NTD)has been demonstrated for the first time in this work for substitutional introduction of tin(Sn)shallow donors into two-dimensional(2D)layered indium selenide(InSe)to manipulate electron transfer and charge carrier dynamics.Multidisciplinary study including density functional theory,transient optical absorption,and FET devices have been carried out to reveal that the field effect electron mobility of the fabricated phototransistor is increased 100-fold due to the smaller electron effective mass and longer electron life time in the Sn-doped InSe.The responsivity of the Sn-doped InSe based phototransistor is accordingly enhanced by about 50 times,being as high as 397 A/W.The results show that NTD is a highly effective and controllable doping method,possessing good compatibility with the semiconductor manufacturing process,even after device fabrication,and can be carried out without introducing any contamination,which is radically different from traditional doping methods.
基金This work was supported by the National Natural Science Foundation of China (Grant No. Project 29890216).
文摘Photofragmentation study of metal fullerides C60Mx (M=Sm, Pt, Ni and Rh) by excimer laser ablation-TOF mass spectrometry shows that metallofullerenes C2nM and C2n+1M formed in both the positive and negative ionic modes. The isotopic distributions of the metallofullerenes C2nM and C2n+1M are consistent with the calculated spectra based on the natural abundance of isotopes of C and M, confirming the formation of metallofullerenes. The metal atom is sup-posed to be incorporated into the network of the fullerene cage to replace one carbon atom of the cage forming substi-tutional metallofullerene. Odd-numbered high carbon clusters are observed in our laser ablation study of all the metal fullerides in the negative ion channel. Evolution of mass spectrum with irradiation laser shots shows that the formation of the substitutionally doped fullerenes is closely related to the production of metal carbide (MC). The structures, as well as formation mechanism, of metallofullerenes C2n+1M and C2nM with even and odd
基金Project supported by the National Natural Science Foundation of China and the Natural Science Fund of Fujian, China.
文摘On account of the integral behavior of dislocations and the interaction between solute atoms and dislocations, a model describing the serrated yielding (i.e. the PL effect) in substitutional alloys is proposed. According to this model, the serrated yielding occurring in a certain strain rate-temperature range will disappear when the strain exceeds a proper value under certain conditions. The model has been confirmed by tensile tests and rapid changing strain rate tests on a commercial Cu-32wt.％ Zn alloy. Experimental results agree well with the predicted effects of temperature and strain rate on the critical strain for the appearance and disappearance of serrations.
文摘Elliptic curve(EC)based cryptosystems gained more attention due to enhanced security than the existing public key cryptosystems.A substitution box(S-box)plays a vital role in securing modern symmetric key cryptosystems.However,the recently developed EC based algorithms usually trade off between computational efficiency and security,necessitating the design of a new algorithm with the desired cryptographic strength.To address these shortcomings,this paper proposes a new scheme based onMordell elliptic curve(MEC)over the complex field for generating distinct,dynamic,and highly uncorrelated S-boxes.Furthermore,we count the exact number of the obtained S-boxes,and demonstrate that the permuted version of the presented S-box is statistically optimal.The nonsingularity of the presented algorithm and the injectivity of the resultant output are explored.Rigorous theoretical analysis and experimental results demonstrate that the proposedmethod is highly effective in generating a large number of dynamic S-boxes with adequate cryptographic properties,surpassing current state-of-the-art S-box generation algorithms in terms of security.Apart fromthis,the generated S-box is benchmarked using side-channel attacks,and its performance is compared with highly nonlinear S-boxes,demonstrating comparable results.In addition,we present an application of our proposed S-box generator by incorporating it into an image encryption technique.The encrypted and decrypted images are tested by employing extensive standard security metrics,including the Number of Pixel Change Rate,the Unified Average Changing Intensity,information entropy,correlation coefficient,and histogram analysis.Moreover,the analysis is extended beyond conventional metrics to validate the new method using advanced tests,such as the NIST statistical test suite,robustness analysis,and noise and cropping attacks.Experimental outcomes show that the presented algorithm strengthens the existing encryption scheme against various well-known cryptographic attacks.
基金supported by the National Natural Science Foundation of China(Grant No.22175136)the State Key Laboratory of Electrical Insulation and Power Equipment(Grant No.EIPE23127)the Fundamental Research Funds for the Central Universities(xtr052024009,xtr052025002).
文摘Violet phosphorus,a recently explored layered elemental semiconductor,has attracted much attention due to its unique photoelectric,mechanical properties,and high hole mobility.Herein,violet arsenic phosphorus has for the first time been synthesized by a molten lead method.The crystal structure of violet arsenic phosphorus(P^(83.4)As_(0.6),CSD-2408761)was determined by single crystal X-ray diffraction to have similar structure as that of violet phosphorus,where P12 is occupied by arsenic/phosphorus(As/P)atoms as mixed occupancy sites As1/P12.The arsenic substitution has been demonstrated to tune the band structure of violet phosphorus,switching p-type of violet phosphorus to high-performance n-type violet arsenic phosphorus.The effective electron mass along the<010>direction is significantly reduced from 1.792 to 0.515 m_(0)by arsenic substitution,resulting in an extremely high electron mobility of 2622.503 cm^(2)V^(-1)s^(-1).The field effect transistor built with P_(83.4)As_(0.6)nanosheets was measured to have a high electron mobility(137.06 cm^(2)V^(-1)s^(-1),61.2 nm),even under ambient conditions for 5 h,much higher than the hole mobility of violet phosphorene nanosheets(4.07 cm^(2)V^(-1)s^(-1),73.3 nm).This work provides a new idea for designing phosphorus-based materials for field effect transistors,giving significant potential in complementary metal-oxide-semiconductor applications.
基金funded by the Key R&D Program of Yangling Seed Industry Innovation,China(Ylzy-xm-02)the Young Elite Scientists Sponsorship Program by China Association for Science and Technology(2021QNRC001)。
文摘Thinopyrum ponticum(2n=10×=70),a wild relative of common wheat(Triticum aestivum L.),is considered an invaluable genetic resource for wheat improvement due to its abundance of genes conferring resistance to biotic and abiotic stresses.This study focused on the CH97 line,derived from the BC1F7 progeny of a cross between wheat cv.7182 and Th.ponticum.Cytological evidence showed that CH97 has 42 chromosomes,forming 21 bivalents at meiotic metaphase I,with the bivalents subsequently separating and moving to opposite poles during meiotic anaphase I.Through a combination of fluorescence in situ hybridization(FISH),genomic in situ hybridization(GISH),multicolor GISH(mc-GISH),and liquid array analysis,it was determined that CH97 comprises 40 wheat chromosomes and two alien chromosomes from the Ee genome of Th.ponticum,featuring the absence of a pair of 5D chromosomes and variations in 1B,6B,and 7B chromosomes.These findings confirm that CH97 is a stable wheat-Th.ponticum 5E(5D)alien disomic substitution line.Inoculation experiments revealed that CH97 exhibits high resistance to wheat powdery mildew and stripe rust throughout the growth period,in contrast to the highly susceptible common wheat parent 7182.Compared to 7182,CH97 displayed improvements in thousand-kernel weight and kernel length.Additionally,utilizing specific-locus amplified fragment sequencing(SLAF-seq)technology,chromosome 5E-specific molecular markers were developed and validated,achieving a 33.3% success rate,facilitating marker-assisted selection for disease resistance in wheat.Overall,the CH97 substitution line,with its resistance to diseases and improved agronomic traits,represents valuable new germplasm for wheat chromosome engineering and breeding.
基金supported by the 2025 Jiangsu Province Graduate Student Practice Innovation Program(No.SJCX25_1696)the 2024 Changzhou University Educational Research Project(No.GJY2024009).
文摘Background:The phenomenon of multimorbidity in chronic diseases among the elderly is prevalent,and its significant association with depression poses a serious threat to the physical and mental health of older adults.Current research on the associations between 24-hour movement behaviors(including physical activity,sedentary behavior,and sleep)and depression has largely been confined to examining the effects of single behaviors,overlooking the intrinsic compositional nature and interrelationships among these behaviors.Therefore,it is necessary to investigate the integrated effects of 24-hour movement behaviors on depression in older adults with multimorbidity from a holistic,compositional perspective.Methods:From November 2024 to April 2025,a total of 226 older adult patients with multimorbidity were recruited from a tertiary hospital in Changzhou City.Data were collected using a general information questionnaire,the International Physical Activity Questionnaire–Short Form(IPAQ-SF),the Pittsburgh Sleep Quality Index(PSQI),and the Patient Health Questionnaire-9(PHQ-9).Compositional data analysis and isotemporal substitution models were employed for statistical analysis.Results:The mean daily durations of Light-Intensity Physical Activity(LPA),Moderate-to-Vigorous Physical Activity(MVPA),Sedentary Behavior(SB),and Sleep(SLP)in older adults with multimorbidity were 402.48 min,12.04 min,511.52 min,and 458.68 min,respectively.The prevalence of depressive symptoms was 37.6%.Compositional data analysis revealed that SB was positively associated with depression(βSB=1.005,P=0.006),while SLP was negatively associated with depression(βSLP=−1.736,P<0.001).No statistically significant associations were found between MVPA or LPA and depression(P>0.05).In the 10-minute isotemporal substitution model,replacing SB with any other behavioral component was associated with a decrease in depression scores.Conversely,substituting SLP with either LPA or SB resulted in an increase in depression scores,while substituting SLP with MVPA led to a decrease in depression scores.The dose-response analysis revealed that,among the isotemporal substitution effects,replacing SB with SLP and replacing SLP with MVPA were the substitution pathways associated with the most rapid decline in depression scores,representing the greatest beneficial health effects.Conclusion:The prevalence of depression is notably high among older adults with multimorbidity.Reducing daily sedentary behavior(SB),maintaining adequate sleep(SLP),and increasing moderate-to-vigorous physical activity(MVPA)can improve depressive symptoms and enhance overall health in this population.
基金the Key project of Nature Science Foundation of Tianjin(22JCZDJC00120)the 111 Project(B16027)for financial support.
文摘Benzoic acid containing fluorine atom at ortho-,meta-,and para-position are employed as self-assembled monolayers to modify the buried interface in perovskite solar cells(PSCs).It is demonstrated that the position of fluorine atom influences the passivation effect and para-fluorinated one provided the most substantial performance enhancement mainly originating from ameliorated contact and energy band alignment between NiOx and perovskite,improved perovskite quality and defect healing.Resultantly,PSC with a power conversion efficiency of 24%can be achieved.Meanwhile,which can maintain 96.8%of the initial PCE after a 1000 h storage,presenting enhanced durability.This work highlights the critical role of molecular functionality and conformation in the buried interface modification of PSCs,providing valuable insights for future developments.
基金supported by the National Natural Science Foundation of China(U1704253,U1908220)the Fundamental Research Funds for the Central Universities(N160208001,N180206001)+2 种基金the Zhejiang Provincial Natural Science Foundation(LR18E010001)the National 1000-Plan for Young Scholarsthe Start-Up Funding Supported from the Northeastern University of China。
文摘Heteroatom substitution has been investigated to be a feasible way to optimize microwave absorption properties of core-shell structural nanocapsules at gigahertz.Although dielectric capacity has been increased at specific frequency with substituted absorbents,its broadband absorption performance is still relatively poor ascribed to the low dipole oscillation amplitude of single substituted heteroatom.In this study we demonstrate that sulfur and oxygen co-substituted heterostructure leads to high microwave absorption property of core-shell structural Fe@C nanocapsules at broadened frequency range,comparable to the single sulfur substitutional Fe@C nanocapsules.Experimental characterizations coupled with first-principles calculations reveal that the microwave absorption enhancement is triggered by the sulfur-oxygen co-substitution,which results in the serious symmetry breaking and thus leads to the charge separation at the co-substituted area.In particular,the nanocapsules exhibt the minimum reflection loss capcacity R(d B)of-52 d B at 6.8 GHz and the bandwith for R(d B)<-20 dB is in the frequency range of 3.1-12.7 GHz.The present study not only offers a deep insight into the relationship between heteroatom and microwave absorption property,but also puts forward a mentality for further designing microwave absorbents.
文摘A medical image encryption is proposed based on the Fisher-Yates scrambling,filter diffusion and S-box substitution.First,chaotic sequence associated with the plaintext is generated by logistic-sine-cosine system,which is used for the scrambling,substitution and diffusion processes.The three-dimensional Fisher-Yates scrambling,S-box substitution and diffusion are employed for the first round of encryption.The chaotic sequence is adopted for secondary encryption to scramble the ciphertext obtained in the first round.Then,three-dimensional filter is applied to diffusion for further useful information hiding.The key to the algorithm is generated by the combination of hash value of plaintext image and the input parameters.It improves resisting ability of plaintext attacks.The security analysis shows that the algorithm is effective and efficient.It can resist common attacks.In addition,the good diffusion effect shows that the scheme can solve the differential attacks encountered in the transmission of medical images and has positive implications for future research.
基金the Doctoral Research Start-up Fund of Hubei University of Science and Technology(BK202504)the Natural Science Foundation of Liaoning Province(2023-MS-115)。
文摘The practical application of aqueous zinc-ion batteries(AZIBs)is primarily constrained by issues such as corrosion,zinc dendrite formation,and the hydrogen evolution reaction occurring at the zinc metal anode.To overcome these challenges,strategies for optimizing the electrolyte are crucial for enhancing the stability of the zinc anode.Inspired by the role of hemoglobin in blood cells,which facilitates oxygen transport during human respiration,an innovative inorganic colloidal electrolyte has been developed:calcium silicate-ZnSO_(4)(denoted as CS-ZSO).This electrolyte operates in weak acidic environment and releases calcium ions,which participate in homotopic substitution with zinc ions,while the solvation environment of hydrated zinc ions in the electrolyte is regulated.The reduced energy barrier for the transfer of zinc ions and the energy barrier for the desolvation of hydrated ions imply faster ion transfer kinetics and accelerated desolvation processes,thus favoring the mass transfer process.Furthermore,the silicate colloidal particles act as lubricants,improving the transfer of zinc ions.Together,these factors contribute to the more uniform concentration of zinc ions at the electrode/electrolyte interface,effectively inhibiting zinc dendrite formation and reducing by-product accumulation.The Zn//CS-ZSO//Zn symmetric cell demonstrates stable operation for over 5000 h at 1 mA cm^(-2),representing 29-fold improvement compared to the Zn//ZSO//Zn symmetric cell,which lasts only 170 h.Additionally,the Zn//CS-ZSO//Cu asymmetric cell shows stable average Coulombic efficiency(CE)exceeding 99.6%over2400 cycles,significantly surpassing the performance of the ZSO electrolyte.This modification strategy for electrolytes not only addresses key limitations associated with zinc anodes but also provides valuable insights into stabilizing anodes for the advancement of high-performance aqueous zinc-ion energy storage systems.
