The synthesis method of propargylamines has always been the focus of research in organic synthetic methodology.A method of alkynylation of tertiary aliphatic amines with alkynes in the presence of copper doped zeolite...The synthesis method of propargylamines has always been the focus of research in organic synthetic methodology.A method of alkynylation of tertiary aliphatic amines with alkynes in the presence of copper doped zeolite Y as a catalyst and oxygen in the air as an oxidant has been developed.The most important feature of this reaction is that copper molecular siolite is used as catalyst,which avoids the intermolecular self-coupling of alkynes,and thus realizes the high efficiency propargylization of alkyl tertiary amines.展开更多
A chromium(II)-catalyzed reduction cross coupling reaction was reported.This reaction utilizes inexpensive and readily available chromium dichloride as a catalyst and 4,4'-di-tert-butyl-bipyridine as a ligand to a...A chromium(II)-catalyzed reduction cross coupling reaction was reported.This reaction utilizes inexpensive and readily available chromium dichloride as a catalyst and 4,4'-di-tert-butyl-bipyridine as a ligand to achieve reduction cross coupling between trifluoromethyl olefins and alkyl bromides under mild conditions,effectively synthesizing difluoroalkene derivatives.This reaction exhibits good substrate universality and is compatible with multiple important functional groups,providing a concise synthetic pathway for constructing conjugated difluoroalkenes containing allyl difluoromethylene structural units.Preliminary mechanistic experiments indicate that alkyl bromides first undergo a reduction process to generate corresponding alkyl radicals,followed by addition to trifluoromethyl olefins.After binding with Cr(II),they undergo aβ-fluorine elimination process to generate difluoroalkenes.展开更多
Chiral carbonyl compounds frequently occur in natural products and pharmaceuticals. Additionally, they serve as important intermediates in organic synthesis. Transition metal-catalyzed asymmetric carbonylative cross-c...Chiral carbonyl compounds frequently occur in natural products and pharmaceuticals. Additionally, they serve as important intermediates in organic synthesis. Transition metal-catalyzed asymmetric carbonylative cross-coupling reactions are among the most straightforward and effective methods for synthesizing chiral carbonyl compounds, including esters, amides, and ketones. The advances in asymmetric carbonylative cross-coupling reactions using various O-, N-, C-, and S-containing nucleophiles or electrophiles over the past decade are summarized.展开更多
Selective defluorinative functionalization of trifluoromethylarenes(ArCF3)to obtain the pharmaceutically commonα,α-difluorobenzylic motif is an attractive and elegant synthetic route.Over the past decade,although C(...Selective defluorinative functionalization of trifluoromethylarenes(ArCF3)to obtain the pharmaceutically commonα,α-difluorobenzylic motif is an attractive and elegant synthetic route.Over the past decade,although C(sp^(3))-F bonds functionalization have been greatly developed,catalytic cross-coupling of trifluoromethylarenes with C-H of terminal alkynes remains a challenge.Here,we report an approach to achieve Sonogashira-type cross-coupling of trifluoromethylarenes with terminal alkynes C(sp)-H bonds via photoredox and Cu/L dual catalysis.Tridentate anionic ligand is pivotal to realize this C-H sp-sp^(3) cross-coupling.Moreover,this unique catalytic system is also suitable for cross-coupling of C(sp^(3))-F bonds with azoles C(sp^(2))-H bonds.A series of trifluoromethylarenes,terminal alkynes and azoles with various functional groups are compatible with this protocol affording a variety of defluoroalkynylation or defluoroazolation products.Preliminary mechanistic studies indicated that deprotonated BINOL involved as a photocatalyst to activate ArCF3 rather than a ligand to the metal.展开更多
In most Suzuki–Miyaura carbon-carbon cross-coupling reactions,the borabicyclo[3.3.1]nonane scaffold(9-BBN)only serves as an auxiliary facilitating the transmetalation step and thus is transformed into by-products.The...In most Suzuki–Miyaura carbon-carbon cross-coupling reactions,the borabicyclo[3.3.1]nonane scaffold(9-BBN)only serves as an auxiliary facilitating the transmetalation step and thus is transformed into by-products.There are rare examples where the 9-BBN derivatives serve as the potentially diverse C8 building blocks in cross-coupling reactions.Herein,we report a cobalt-catalyzed migratory carboncarbon cross-coupling reaction of the in situ formed 9-BBN ate complexes to afford diverse aryl-and alkyl-functionalized cyclooctenes.Preliminary mechanistic studies suggest the oxidation-induced cisbicyclo[3.3.0]oct-1-ylborane is the key intermediate in this migratory cross-coupling reaction,which promotes the development of other diverse migratory cross-coupling of borate complexes.展开更多
The switchable cross-coupling of indoles and pyridotriazoles through carbene insertion at C_(2)-or C_(3)-positon has been developed in this paper.This highly site-selective C-H carbenoid functionalization is determine...The switchable cross-coupling of indoles and pyridotriazoles through carbene insertion at C_(2)-or C_(3)-positon has been developed in this paper.This highly site-selective C-H carbenoid functionalization is determined by both the Rh-catalyst species and auxiliary groups.[Cp∗RhCl_(2)]_(2) and coordinating pyrimidyl group direct the C-H carbenoid functionalization to occur at the C_(2)-position,while Rh2OAc4 and noncoordinating benzyl group lead the reaction to occur at the C_(3)-position of the indoles.This regioselective C−H functionalization strategy is of significant importance for the discovery of indole drugs.展开更多
An N-heterocyclic carbene(NHC)catalyzed enantioselective cyclisation and trifluoromethylation of olefins with cinnamaldehydes via radical relay cross-coupling in the presence of Togni reagent is reported andδ-lactone...An N-heterocyclic carbene(NHC)catalyzed enantioselective cyclisation and trifluoromethylation of olefins with cinnamaldehydes via radical relay cross-coupling in the presence of Togni reagent is reported andδ-lactones tolerated with stereogenic centers atβ-andγ-positions are obtained in moderate to high yields and with high enantioselectivities.Further computational studies explain that the radical crosscoupling step is the key to determining the enantioselectivity.Energy analysis of key transition states and intermediates also provides a reasonable explanation for the difficulty of diastereoselective control.DFT calculations also reveal that the hydrogen-bonding interaction plays a vital role in the promotion of this chemistry.展开更多
The fast solution of linear equations has always been one of the hot spots in scientific computing.A kind of the diagonal matrix splitting iteration methods are provided,which is different from the classical matrix sp...The fast solution of linear equations has always been one of the hot spots in scientific computing.A kind of the diagonal matrix splitting iteration methods are provided,which is different from the classical matrix splitting methods.Taking the decomposition of the diagonal elements for coefficient matrix as the key point,some new preconditioners are constructed.Taking the tri-diagonal coefficient matrix as an example,the convergence domains and optimal relaxation factor of the new method are analyzed theoretically.The presented new iteration methods are applied to solve linear algebraic equations,even 2D and 3D diffusion problems with the fully implicit discretization.The results of numerical experiments are matched with the theoretical analysis,and show that the iteration numbers are reduced greatly.The superiorities of presented iteration methods exceed some classical iteration methods dramatically.展开更多
The Pd-catalyzed Suzuki-Miyaura coupling reaction is a crucial tool for constructing C-C bonds.Currently,the organic solvents employed during reaction may cause serious environmental problems.Moreover,the low solubili...The Pd-catalyzed Suzuki-Miyaura coupling reaction is a crucial tool for constructing C-C bonds.Currently,the organic solvents employed during reaction may cause serious environmental problems.Moreover,the low solubility of inorganic bases in organic solvents leads to enormous mass transfer resistance.To address this issue,the Pickering droplets reactor stabilized by Pd/g-C_(3)N_(4)at substrate-water two-phase interface is reported.Benefiting from the hydrophobic conjugated framework and hydrophilic terminal groups,Pd/g-C_(3)N_(4)can configure stable Pickering emulsion without additional functionalization.The Pd loaded catalysts exhibits excellent performance(TOF=21852 h^(-1))for the Suzuki-Miyaura coupling reaction,which is deriving from unique electronic structure of g-C_(3)N_(4)and high interfacial area of emulsion.Moreover,there is no clear decrease in reactivity after six cycles(conversion>86%).In this study,the organic solvent was replaced by reaction substrate,and the high activity can be achieved for various halogenated aromatic hydrocarbons and their derivatives.展开更多
In this paper,we consider the maximal positive definite solution of the nonlinear matrix equation.By using the idea of Algorithm 2.1 in ZHANG(2013),a new inversion-free method with a stepsize parameter is proposed to ...In this paper,we consider the maximal positive definite solution of the nonlinear matrix equation.By using the idea of Algorithm 2.1 in ZHANG(2013),a new inversion-free method with a stepsize parameter is proposed to obtain the maximal positive definite solution of nonlinear matrix equation X+A^(*)X|^(-α)A=Q with the case 0<α≤1.Based on this method,a new iterative algorithm is developed,and its convergence proof is given.Finally,two numerical examples are provided to show the effectiveness of the proposed method.展开更多
Quick and accurate determination of the optimal synchrophase angle is crucial for synchrophasing control of multi-propeller aircraft with low noise.This paper proposes a novel noise prediction and optimization strateg...Quick and accurate determination of the optimal synchrophase angle is crucial for synchrophasing control of multi-propeller aircraft with low noise.This paper proposes a novel noise prediction and optimization strategy,developing a continuous and accurate noise prediction model and obtaining its minimum by solving the Hessian matrix and Fourier-Frobenius matrix.Firstly,a novel propeller noise prediction method uses acoustic simulation pressure signals and improved propeller signatures theory to accurately estimate noise for all synchrophase angles and receiving points.Secondly,a novel optimization approach is proposed to solve the analytical solution of the minimum propeller noise:(A)A noise objective function is established,and use its first derivatives’zeros and Hessian matrix to determine the function minimum.(B)A novel Euler formula transform method is proposed to convert trigonometric polynomials into algebraic polynomials,changing the zeros of the former into those of the latter.(C)Utilize the Fourier-Frobenius matrix method to solve the zeros of algebraic polynomials.To assess the computation time and accuracy,a turboprop aircraft with two six-bladed propellers was analyzed using the computational fluid dynamics and acoustic analogy method,providing acoustic pressure signals at 20 receivers for noise prediction and optimization.The Durand-Kerner and Fourier-Frobenius matrix methods were compared.Results demonstrate that improved propeller signatures theory is more accurate,and the Hessian matrix+Fourier-Frobenius matrix method is faster and more precise than the Hessian matrix+Durand-Kerner method.展开更多
Driven by advancements in mobile internet technology,images have become a crucial data medium.Ensuring the security of image information during transmission has thus emerged as an urgent challenge.This study proposes ...Driven by advancements in mobile internet technology,images have become a crucial data medium.Ensuring the security of image information during transmission has thus emerged as an urgent challenge.This study proposes a novel image encryption algorithm specifically designed for grayscale image security.This research introduces a new Cantor diagonal matrix permutation method.The proposed permutation method uses row and column index sequences to control the Cantor diagonal matrix,where the row and column index sequences are generated by a spatiotemporal chaotic system named coupled map lattice(CML).The high initial value sensitivity of the CML system makes the permutation method highly sensitive and secure.Additionally,leveraging fractal theory,this study introduces a chaotic fractal matrix and applies this matrix in the diffusion process.This chaotic fractal matrix exhibits selfsimilarity and irregularity.Using the Cantor diagonal matrix and chaotic fractal matrix,this paper introduces a fast image encryption algorithm involving two diffusion steps and one permutation step.Moreover,the algorithm achieves robust security with only a single encryption round,ensuring high operational efficiency.Experimental results show that the proposed algorithm features an expansive key space,robust security,high sensitivity,high efficiency,and superior statistical properties for the ciphered images.Thus,the proposed algorithm not only provides a practical solution for secure image transmission but also bridges fractal theory with image encryption techniques,thereby opening new research avenues in chaotic cryptography and advancing the development of information security technology.展开更多
Carbon dots(CDs)have been widely studied since their discovery because of simple preparation,low toxicity and excellent luminescence properties.With the deepening of research,the luminescence properties of CDs are not...Carbon dots(CDs)have been widely studied since their discovery because of simple preparation,low toxicity and excellent luminescence properties.With the deepening of research,the luminescence properties of CDs are not only limited to fluorescence,but also their afterglow properties have been widely studied.Many excellent results have been reported for afterglow CDs.Researchers have found that various organic matrixes(OMs)can fix the emission properties of CDs and provide a rigid environment,and the interaction between OMs and CDs can inhibit the non-radiative transition of triplet excitons,which can effectively activate the afterglow performance of CDs.In this review,we provide a detailed introduction to the research progress on afterglow CDs in OMs.The preparation of afterglow CDs and their related properties were analyzed and summarized based on organic polymer matrixes and organic small molecule matrixes.Organic polymer matrixes from synthetic polymers and natural polymers have been introduced.Then,the mechanism of solid and liquid afterglow of CDs by OMs is analyzed,and their applications in the fields of anti-counterfeiting,information encryption,phosphorescence detection,fingerprint recognition,lighting and so on are summarized.Finally,the challenges facing afterglow CDs in OMs are summarized,and future research is proposed.展开更多
Generative steganography uses generative stego images to transmit secret message.It also effectively defends against statistical steganalysis.However,most existing methods focus primarily on matching the feature distr...Generative steganography uses generative stego images to transmit secret message.It also effectively defends against statistical steganalysis.However,most existing methods focus primarily on matching the feature distribution of training data,often neglecting the sequential continuity between moves in the game.This oversight can result in unnatural patterns that deviate from real user behavior,thereby reducing the security of the hidden communication.To address this issue,we design a Gomoku agent based on the AlphaZero algorithm.The model engages in self-play to generate a sequence of plausible moves.These moves formthe basis of the stego images.We then apply an attractionmatrix at each step.It guides themove selection so that themoves appearmore natural.Thismethod helps maintain logical flow between moves.It also extends the game length,which increases the embedding capacity.Next,we filter and prioritize the generated moves.The selected moves are embedded into a move pool.Secret message is mapped to thesemoves.It is then embedded step by step as the game progresses.The finalmove sequence constitutes a complete steganographic game record.The receiver can extract the secret message using this record and a predefined mapping rule.Experiments show that our method reaches a maximum embedding capacity of 223 bits per carrier.Detection accuracy is 0.500 under XuNet and 0.498 under YeNet.These results are equal to random guessing,showing strong imperceptibility.The proposed method demonstrates superior concealment,higher embedding capacity,and greater robustness against common image distortions and steganalysis attacks.展开更多
Traditional nerve repair methods,such as autologous nerve grafting and allogeneic nerve grafting,face issues such as donor shortage,functional loss,and immune rejection.Decellularized extracellular matrix-based grafts...Traditional nerve repair methods,such as autologous nerve grafting and allogeneic nerve grafting,face issues such as donor shortage,functional loss,and immune rejection.Decellularized extracellular matrix-based grafts have emerged as highly promising alternatives,capable of uniquely recreating the natural neural mic roenvironment,promoting host cell remodeling,and ultimately enhancing functional neural regeneration.This review comprehensively analyzes the key mechanisms of peripheral nerve injury and regeneration,focusing on contemporary therapeutic strategies for key aspects such as axonal apoptosis inhibition,enhanced intrinsic regenerative capacity,construction of regenerative microenvironment,and prevention of target organ atrophy.Findings from this review has shown that decellularized extra cellular matrix grafts can promote the migration,prolife ration,and differentiation of nerve cells by providing physical suppo rt,chemical signals,and mechanical stability.Decellularized extracellular matrix grafts are mainly used as ne rve conduits,scaffolds,hydrogels,and3D printing inks.Decellularized extra cellular matrix grafts have demonstrated significant advantages in promoting nerve regeneration by regulating the prolife ration and differentiation of Schwann cells,improving the neural microenvironment,reducing inflammato ry responses,and promoting angiogenesis.Additionally,decellularized extracellular matrix grafts can se rve as drug carrie rs,enabling the controlled release of growth factors,which further enhances nerve regeneration.However,these grafts also have some limitations,including the presence of immunogenic residues,inadequate mechanical prope rties,inter-batch variability,and uncontrollable degradation rates.Future research should focus on optimizing the decellularization process,enhancing the mechanical prope rties of decellularized extracellular matrix grafts,reducing immunogenicity,improving biocompatibility and safety,and developing new composite mate rials.Furthermore,exploring their application potential in complex nerve injuries,such as diabetic neuropathy,is crucial to meet the needs of peripheral nerve regeneration and repair.展开更多
We read with the great interest the study by Ababneh et al in which inducedmesenchymal stem cell-derived exosomes were shown to exhibit a stronger andmore sustained anti-proliferative effect by inducing a senescence-l...We read with the great interest the study by Ababneh et al in which inducedmesenchymal stem cell-derived exosomes were shown to exhibit a stronger andmore sustained anti-proliferative effect by inducing a senescence-like state withoutapoptosis.The results obtained by the authors highlight the features of theeffects of senescent drift induction in surrounding tissues.In the light of thesefindings,the role of the properties of extracellular matrix and cellular glycocalyxin responses of human tumors to therapy remain uninvestigated.These extracellularbarriers appear to be significant obstacles to effective cancer therapy,especiallyin relation to the use of unique properties of tumor microenvironment forthe immunotherapy-resistant cancer treatment.展开更多
The effect of adding hydroxycinnamic acids(caffeic acid,sinapic acid,p-coumaric acid and chlorogenic acid)in Cabernet Sauvignon dry red wine before and after fermentation was investigated,taking into account the color...The effect of adding hydroxycinnamic acids(caffeic acid,sinapic acid,p-coumaric acid and chlorogenic acid)in Cabernet Sauvignon dry red wine before and after fermentation was investigated,taking into account the color parameters,anthocyanin content,and overall polyphenol levels in the wine samples.The copigmentation effect of malvidin-3-Oglucoside and sinapic acid was further explored in model solution and through theoretical calculations.The results indicated that the addition of hydroxycinnamic acids significantly enhanced the wine's color with sinapic acid(before the fermentation)showing the most pronounced color protection effect.Compared to control samples,the addition of hydroxycinnamic acids resulted in a 36%increase in total phenolic content and a 28% increase in total anthocyanin content.Thermodynamic analysis revealed that the interaction between sinapic acid and malvidin-3-O-glucoside was spontaneous and exothermic.Theoretical studies identified hydrogen bonding(HB)and dispersion forces as the main primary stabilizing forces,with the carboxyl group of sinapic acid playing a critical role while the anthocyanin backbone also influenced the interaction.展开更多
With the rapid advancement of electromagnetic launch technology,enhancing the structural stability and thermal resistance of armatures has become essential for improving the overall efficiency and reliability of railg...With the rapid advancement of electromagnetic launch technology,enhancing the structural stability and thermal resistance of armatures has become essential for improving the overall efficiency and reliability of railgun systems.Traditional aluminum alloy armatures often suffer from severe ablation,deformation,and uneven current distribution under high pulsed currents,which limit their performance and service life.To address these challenges,this study employs the Johnson–Cook constitutive model and the finite element method to develop armature models of aluminum matrix composites with varying heterogeneous graphene volume fractions.The temperature,stress,and strain of the armatures during operation were analyzed to investigate the effects of different graphene volume fractions on the deformation and damage behavior of aluminum matrix composite armatures under the multi-field coupling of electromagnetic,thermal,and structural interactions.The results indicate that,compared to the 6061 aluminum alloy matrix,the graphene-reinforced aluminum matrix composite armature significantly suppresses ablation damage at the tail and throat edges.The incorporation of graphene notably reduces the temperature rise during the armature emission process,increases the muzzle velocity under identical current excitation,and mitigates directional deformation of the armature.The 1 wt.% graphene-reinforced aluminum matrix composite armature demonstrates better agreement with experimental results at a strain rate of 2000 s^(-1),while simultaneously improving stress-strain response,reducing temperature rise,and improving velocity performance.展开更多
Let R be a reduced ring,and k,n be integers with 1≤k≤n.We construct a special subring Tk,n(R),relative to endomorphisms of R,of the upper triangular matrix ring Tn(R)over R and show that Tk,n(R)is semicommutative an...Let R be a reduced ring,and k,n be integers with 1≤k≤n.We construct a special subring Tk,n(R),relative to endomorphisms of R,of the upper triangular matrix ring Tn(R)over R and show that Tk,n(R)is semicommutative and Armendariz.Our results yield more examples of semicommutative and Armendariz rings.Also,the maximality of Tk,n(R)in some rings are discussed.展开更多
Efficient implementation of fundamental matrix operations on quantum computers,such as matrix products and Hadamard operations,holds significant potential for accelerating machine learning algorithms.A critical prereq...Efficient implementation of fundamental matrix operations on quantum computers,such as matrix products and Hadamard operations,holds significant potential for accelerating machine learning algorithms.A critical prerequisite for quantum implementations is the effective encoding of classical data into quantum states.We propose two quantum computing frameworks for preparing the distinct encoded states corresponding to matrix operations,including the matrix product,matrix sum,matrix Hadamard product and division.Quantum algorithms based on the digital encoding computing framework are capable of implementing the matrix Hadamard operation with a time complexity of O(poly log(mn/ε))and the matrix product with a time complexity of O(poly log(mnl/ε)),achieving an exponential speedup in contrast to the classical methods of O(mn)and O(mnl).Quantum algorithms based on the analog-encoding framework are capable of implementing the matrix Hadamard operation with a time complexity of O(k_(1)√mn·poly log(mn/ε))and the matrix product with a time complexity of O(k_(2)√1·poly log(mnl/ε)),where k_(1)and k_(2)are coefficients correlated with the elements of the matrix,achieving a square speedup in contrast to the classical counterparts.As applications,we construct an oracle that can access the trace of a matrix within logarithmic time,and propose several algorithms to respectively estimate the trace of a matrix,the trace of the product of two matrices,and the trace inner product of two matrices within logarithmic time.展开更多
文摘The synthesis method of propargylamines has always been the focus of research in organic synthetic methodology.A method of alkynylation of tertiary aliphatic amines with alkynes in the presence of copper doped zeolite Y as a catalyst and oxygen in the air as an oxidant has been developed.The most important feature of this reaction is that copper molecular siolite is used as catalyst,which avoids the intermolecular self-coupling of alkynes,and thus realizes the high efficiency propargylization of alkyl tertiary amines.
文摘A chromium(II)-catalyzed reduction cross coupling reaction was reported.This reaction utilizes inexpensive and readily available chromium dichloride as a catalyst and 4,4'-di-tert-butyl-bipyridine as a ligand to achieve reduction cross coupling between trifluoromethyl olefins and alkyl bromides under mild conditions,effectively synthesizing difluoroalkene derivatives.This reaction exhibits good substrate universality and is compatible with multiple important functional groups,providing a concise synthetic pathway for constructing conjugated difluoroalkenes containing allyl difluoromethylene structural units.Preliminary mechanistic experiments indicate that alkyl bromides first undergo a reduction process to generate corresponding alkyl radicals,followed by addition to trifluoromethyl olefins.After binding with Cr(II),they undergo aβ-fluorine elimination process to generate difluoroalkenes.
文摘Chiral carbonyl compounds frequently occur in natural products and pharmaceuticals. Additionally, they serve as important intermediates in organic synthesis. Transition metal-catalyzed asymmetric carbonylative cross-coupling reactions are among the most straightforward and effective methods for synthesizing chiral carbonyl compounds, including esters, amides, and ketones. The advances in asymmetric carbonylative cross-coupling reactions using various O-, N-, C-, and S-containing nucleophiles or electrophiles over the past decade are summarized.
基金support of this work by the National Natural Science Foundation of China(Nos.22371307,21971267)the program for Guangdong Introducing Innovative and Entrepreneurial Teams(No.2017ZT07C069).
文摘Selective defluorinative functionalization of trifluoromethylarenes(ArCF3)to obtain the pharmaceutically commonα,α-difluorobenzylic motif is an attractive and elegant synthetic route.Over the past decade,although C(sp^(3))-F bonds functionalization have been greatly developed,catalytic cross-coupling of trifluoromethylarenes with C-H of terminal alkynes remains a challenge.Here,we report an approach to achieve Sonogashira-type cross-coupling of trifluoromethylarenes with terminal alkynes C(sp)-H bonds via photoredox and Cu/L dual catalysis.Tridentate anionic ligand is pivotal to realize this C-H sp-sp^(3) cross-coupling.Moreover,this unique catalytic system is also suitable for cross-coupling of C(sp^(3))-F bonds with azoles C(sp^(2))-H bonds.A series of trifluoromethylarenes,terminal alkynes and azoles with various functional groups are compatible with this protocol affording a variety of defluoroalkynylation or defluoroazolation products.Preliminary mechanistic studies indicated that deprotonated BINOL involved as a photocatalyst to activate ArCF3 rather than a ligand to the metal.
基金supported by the National Natural Science Foundation of China(No.22171046)the Hundred-Talent Project of Fujian(No.50021113)Fuzhou University(No.0480-00489503)。
文摘In most Suzuki–Miyaura carbon-carbon cross-coupling reactions,the borabicyclo[3.3.1]nonane scaffold(9-BBN)only serves as an auxiliary facilitating the transmetalation step and thus is transformed into by-products.There are rare examples where the 9-BBN derivatives serve as the potentially diverse C8 building blocks in cross-coupling reactions.Herein,we report a cobalt-catalyzed migratory carboncarbon cross-coupling reaction of the in situ formed 9-BBN ate complexes to afford diverse aryl-and alkyl-functionalized cyclooctenes.Preliminary mechanistic studies suggest the oxidation-induced cisbicyclo[3.3.0]oct-1-ylborane is the key intermediate in this migratory cross-coupling reaction,which promotes the development of other diverse migratory cross-coupling of borate complexes.
基金CAMS Innovation Fund for Medical Sciences(CIFMS)(Nos.2022-I2M-1-013,2022-I2M-1-014,2022-I2M-2-002).
文摘The switchable cross-coupling of indoles and pyridotriazoles through carbene insertion at C_(2)-or C_(3)-positon has been developed in this paper.This highly site-selective C-H carbenoid functionalization is determined by both the Rh-catalyst species and auxiliary groups.[Cp∗RhCl_(2)]_(2) and coordinating pyrimidyl group direct the C-H carbenoid functionalization to occur at the C_(2)-position,while Rh2OAc4 and noncoordinating benzyl group lead the reaction to occur at the C_(3)-position of the indoles.This regioselective C−H functionalization strategy is of significant importance for the discovery of indole drugs.
基金financial supports for this work are provided by the National Natural Science Foundation of China(Nos.21871160,21672121,22071130)。
文摘An N-heterocyclic carbene(NHC)catalyzed enantioselective cyclisation and trifluoromethylation of olefins with cinnamaldehydes via radical relay cross-coupling in the presence of Togni reagent is reported andδ-lactones tolerated with stereogenic centers atβ-andγ-positions are obtained in moderate to high yields and with high enantioselectivities.Further computational studies explain that the radical crosscoupling step is the key to determining the enantioselectivity.Energy analysis of key transition states and intermediates also provides a reasonable explanation for the difficulty of diastereoselective control.DFT calculations also reveal that the hydrogen-bonding interaction plays a vital role in the promotion of this chemistry.
基金The National Natural Science Foundations of China (12202219)the Natural Science Foundations of Ningxia (2024AAC02009, 2023AAC05001)the Ningxia Youth Top Talents Training Project。
文摘The fast solution of linear equations has always been one of the hot spots in scientific computing.A kind of the diagonal matrix splitting iteration methods are provided,which is different from the classical matrix splitting methods.Taking the decomposition of the diagonal elements for coefficient matrix as the key point,some new preconditioners are constructed.Taking the tri-diagonal coefficient matrix as an example,the convergence domains and optimal relaxation factor of the new method are analyzed theoretically.The presented new iteration methods are applied to solve linear algebraic equations,even 2D and 3D diffusion problems with the fully implicit discretization.The results of numerical experiments are matched with the theoretical analysis,and show that the iteration numbers are reduced greatly.The superiorities of presented iteration methods exceed some classical iteration methods dramatically.
基金the National Natural Science Foundation of China(22178243).
文摘The Pd-catalyzed Suzuki-Miyaura coupling reaction is a crucial tool for constructing C-C bonds.Currently,the organic solvents employed during reaction may cause serious environmental problems.Moreover,the low solubility of inorganic bases in organic solvents leads to enormous mass transfer resistance.To address this issue,the Pickering droplets reactor stabilized by Pd/g-C_(3)N_(4)at substrate-water two-phase interface is reported.Benefiting from the hydrophobic conjugated framework and hydrophilic terminal groups,Pd/g-C_(3)N_(4)can configure stable Pickering emulsion without additional functionalization.The Pd loaded catalysts exhibits excellent performance(TOF=21852 h^(-1))for the Suzuki-Miyaura coupling reaction,which is deriving from unique electronic structure of g-C_(3)N_(4)and high interfacial area of emulsion.Moreover,there is no clear decrease in reactivity after six cycles(conversion>86%).In this study,the organic solvent was replaced by reaction substrate,and the high activity can be achieved for various halogenated aromatic hydrocarbons and their derivatives.
基金Supported in part by Natural Science Foundation of Guangxi(2023GXNSFAA026246)in part by the Central Government's Guide to Local Science and Technology Development Fund(GuikeZY23055044)in part by the National Natural Science Foundation of China(62363003)。
文摘In this paper,we consider the maximal positive definite solution of the nonlinear matrix equation.By using the idea of Algorithm 2.1 in ZHANG(2013),a new inversion-free method with a stepsize parameter is proposed to obtain the maximal positive definite solution of nonlinear matrix equation X+A^(*)X|^(-α)A=Q with the case 0<α≤1.Based on this method,a new iterative algorithm is developed,and its convergence proof is given.Finally,two numerical examples are provided to show the effectiveness of the proposed method.
基金supported by the National Natural Science Foundation of China(Nos.51576097,51976089)the Funding for Outstanding Doctoral Dissertation in Nanjing University of Aeronautics and Astronautics,China(No.BCXJ24-05)the Aeronautical Science Foundation of China(No.2023L060052001).
文摘Quick and accurate determination of the optimal synchrophase angle is crucial for synchrophasing control of multi-propeller aircraft with low noise.This paper proposes a novel noise prediction and optimization strategy,developing a continuous and accurate noise prediction model and obtaining its minimum by solving the Hessian matrix and Fourier-Frobenius matrix.Firstly,a novel propeller noise prediction method uses acoustic simulation pressure signals and improved propeller signatures theory to accurately estimate noise for all synchrophase angles and receiving points.Secondly,a novel optimization approach is proposed to solve the analytical solution of the minimum propeller noise:(A)A noise objective function is established,and use its first derivatives’zeros and Hessian matrix to determine the function minimum.(B)A novel Euler formula transform method is proposed to convert trigonometric polynomials into algebraic polynomials,changing the zeros of the former into those of the latter.(C)Utilize the Fourier-Frobenius matrix method to solve the zeros of algebraic polynomials.To assess the computation time and accuracy,a turboprop aircraft with two six-bladed propellers was analyzed using the computational fluid dynamics and acoustic analogy method,providing acoustic pressure signals at 20 receivers for noise prediction and optimization.The Durand-Kerner and Fourier-Frobenius matrix methods were compared.Results demonstrate that improved propeller signatures theory is more accurate,and the Hessian matrix+Fourier-Frobenius matrix method is faster and more precise than the Hessian matrix+Durand-Kerner method.
基金supported by the National Natural Science Foundation of China(62376106)The Science and Technology Development Plan of Jilin Province(20250102212JC).
文摘Driven by advancements in mobile internet technology,images have become a crucial data medium.Ensuring the security of image information during transmission has thus emerged as an urgent challenge.This study proposes a novel image encryption algorithm specifically designed for grayscale image security.This research introduces a new Cantor diagonal matrix permutation method.The proposed permutation method uses row and column index sequences to control the Cantor diagonal matrix,where the row and column index sequences are generated by a spatiotemporal chaotic system named coupled map lattice(CML).The high initial value sensitivity of the CML system makes the permutation method highly sensitive and secure.Additionally,leveraging fractal theory,this study introduces a chaotic fractal matrix and applies this matrix in the diffusion process.This chaotic fractal matrix exhibits selfsimilarity and irregularity.Using the Cantor diagonal matrix and chaotic fractal matrix,this paper introduces a fast image encryption algorithm involving two diffusion steps and one permutation step.Moreover,the algorithm achieves robust security with only a single encryption round,ensuring high operational efficiency.Experimental results show that the proposed algorithm features an expansive key space,robust security,high sensitivity,high efficiency,and superior statistical properties for the ciphered images.Thus,the proposed algorithm not only provides a practical solution for secure image transmission but also bridges fractal theory with image encryption techniques,thereby opening new research avenues in chaotic cryptography and advancing the development of information security technology.
基金the Youth Talent Program Startup Foundation of Qufu Normal University(No.602601)the Natural Science Foundation of Rizhao(No.RZ2021ZR37)the Natural Science Foundation of Shandong(No.ZR2022MB047)。
文摘Carbon dots(CDs)have been widely studied since their discovery because of simple preparation,low toxicity and excellent luminescence properties.With the deepening of research,the luminescence properties of CDs are not only limited to fluorescence,but also their afterglow properties have been widely studied.Many excellent results have been reported for afterglow CDs.Researchers have found that various organic matrixes(OMs)can fix the emission properties of CDs and provide a rigid environment,and the interaction between OMs and CDs can inhibit the non-radiative transition of triplet excitons,which can effectively activate the afterglow performance of CDs.In this review,we provide a detailed introduction to the research progress on afterglow CDs in OMs.The preparation of afterglow CDs and their related properties were analyzed and summarized based on organic polymer matrixes and organic small molecule matrixes.Organic polymer matrixes from synthetic polymers and natural polymers have been introduced.Then,the mechanism of solid and liquid afterglow of CDs by OMs is analyzed,and their applications in the fields of anti-counterfeiting,information encryption,phosphorescence detection,fingerprint recognition,lighting and so on are summarized.Finally,the challenges facing afterglow CDs in OMs are summarized,and future research is proposed.
基金funded by theWuxi“Taihu Light”Science and Technology Key Project(Basic Research)(K20241046)the National Natural Science Foundation of China(Grant Nos.62102189,62122032,42305158)+1 种基金the Open Project of the National Engineering Research Center for Sensor Networks(2024YJZXKFKT02)Wuxi University Research Start-up Fund for High-Level Talents(No.2022r043).
文摘Generative steganography uses generative stego images to transmit secret message.It also effectively defends against statistical steganalysis.However,most existing methods focus primarily on matching the feature distribution of training data,often neglecting the sequential continuity between moves in the game.This oversight can result in unnatural patterns that deviate from real user behavior,thereby reducing the security of the hidden communication.To address this issue,we design a Gomoku agent based on the AlphaZero algorithm.The model engages in self-play to generate a sequence of plausible moves.These moves formthe basis of the stego images.We then apply an attractionmatrix at each step.It guides themove selection so that themoves appearmore natural.Thismethod helps maintain logical flow between moves.It also extends the game length,which increases the embedding capacity.Next,we filter and prioritize the generated moves.The selected moves are embedded into a move pool.Secret message is mapped to thesemoves.It is then embedded step by step as the game progresses.The finalmove sequence constitutes a complete steganographic game record.The receiver can extract the secret message using this record and a predefined mapping rule.Experiments show that our method reaches a maximum embedding capacity of 223 bits per carrier.Detection accuracy is 0.500 under XuNet and 0.498 under YeNet.These results are equal to random guessing,showing strong imperceptibility.The proposed method demonstrates superior concealment,higher embedding capacity,and greater robustness against common image distortions and steganalysis attacks.
基金National Natural Science Foundation of China,No.32130060,No.81901256Jiangsu College Students Innovation and En trepreneurship Training Program,No.202310304120Y,No.202313993004Y2024 Medical Research Project by the Jiangsu Commission of Health,No.M2024009。
文摘Traditional nerve repair methods,such as autologous nerve grafting and allogeneic nerve grafting,face issues such as donor shortage,functional loss,and immune rejection.Decellularized extracellular matrix-based grafts have emerged as highly promising alternatives,capable of uniquely recreating the natural neural mic roenvironment,promoting host cell remodeling,and ultimately enhancing functional neural regeneration.This review comprehensively analyzes the key mechanisms of peripheral nerve injury and regeneration,focusing on contemporary therapeutic strategies for key aspects such as axonal apoptosis inhibition,enhanced intrinsic regenerative capacity,construction of regenerative microenvironment,and prevention of target organ atrophy.Findings from this review has shown that decellularized extra cellular matrix grafts can promote the migration,prolife ration,and differentiation of nerve cells by providing physical suppo rt,chemical signals,and mechanical stability.Decellularized extracellular matrix grafts are mainly used as ne rve conduits,scaffolds,hydrogels,and3D printing inks.Decellularized extra cellular matrix grafts have demonstrated significant advantages in promoting nerve regeneration by regulating the prolife ration and differentiation of Schwann cells,improving the neural microenvironment,reducing inflammato ry responses,and promoting angiogenesis.Additionally,decellularized extracellular matrix grafts can se rve as drug carrie rs,enabling the controlled release of growth factors,which further enhances nerve regeneration.However,these grafts also have some limitations,including the presence of immunogenic residues,inadequate mechanical prope rties,inter-batch variability,and uncontrollable degradation rates.Future research should focus on optimizing the decellularization process,enhancing the mechanical prope rties of decellularized extracellular matrix grafts,reducing immunogenicity,improving biocompatibility and safety,and developing new composite mate rials.Furthermore,exploring their application potential in complex nerve injuries,such as diabetic neuropathy,is crucial to meet the needs of peripheral nerve regeneration and repair.
文摘We read with the great interest the study by Ababneh et al in which inducedmesenchymal stem cell-derived exosomes were shown to exhibit a stronger andmore sustained anti-proliferative effect by inducing a senescence-like state withoutapoptosis.The results obtained by the authors highlight the features of theeffects of senescent drift induction in surrounding tissues.In the light of thesefindings,the role of the properties of extracellular matrix and cellular glycocalyxin responses of human tumors to therapy remain uninvestigated.These extracellularbarriers appear to be significant obstacles to effective cancer therapy,especiallyin relation to the use of unique properties of tumor microenvironment forthe immunotherapy-resistant cancer treatment.
基金supported by the Key R&D Program of Shaanxi Province,China(2024NC-YBXM-146)the Xi’an Agricultural Technology Research and Development Project,China(24NYGG0048)+1 种基金the Key R&D Program of Xianyang,China(L2024-ZDYF-ZDYF-NY-0028)the National Foreign Expert Project of China(G2023172002L)。
文摘The effect of adding hydroxycinnamic acids(caffeic acid,sinapic acid,p-coumaric acid and chlorogenic acid)in Cabernet Sauvignon dry red wine before and after fermentation was investigated,taking into account the color parameters,anthocyanin content,and overall polyphenol levels in the wine samples.The copigmentation effect of malvidin-3-Oglucoside and sinapic acid was further explored in model solution and through theoretical calculations.The results indicated that the addition of hydroxycinnamic acids significantly enhanced the wine's color with sinapic acid(before the fermentation)showing the most pronounced color protection effect.Compared to control samples,the addition of hydroxycinnamic acids resulted in a 36%increase in total phenolic content and a 28% increase in total anthocyanin content.Thermodynamic analysis revealed that the interaction between sinapic acid and malvidin-3-O-glucoside was spontaneous and exothermic.Theoretical studies identified hydrogen bonding(HB)and dispersion forces as the main primary stabilizing forces,with the carboxyl group of sinapic acid playing a critical role while the anthocyanin backbone also influenced the interaction.
基金funded Basic Research Projects of Higher Education Institutions in Liaoning Province(JYTZD20230004)Future Industry Frontier Technology Project in Liaoning Province in 2025(2025JH2/101330141)Key Research and Development Program of Liaoning Province in 2025.
文摘With the rapid advancement of electromagnetic launch technology,enhancing the structural stability and thermal resistance of armatures has become essential for improving the overall efficiency and reliability of railgun systems.Traditional aluminum alloy armatures often suffer from severe ablation,deformation,and uneven current distribution under high pulsed currents,which limit their performance and service life.To address these challenges,this study employs the Johnson–Cook constitutive model and the finite element method to develop armature models of aluminum matrix composites with varying heterogeneous graphene volume fractions.The temperature,stress,and strain of the armatures during operation were analyzed to investigate the effects of different graphene volume fractions on the deformation and damage behavior of aluminum matrix composite armatures under the multi-field coupling of electromagnetic,thermal,and structural interactions.The results indicate that,compared to the 6061 aluminum alloy matrix,the graphene-reinforced aluminum matrix composite armature significantly suppresses ablation damage at the tail and throat edges.The incorporation of graphene notably reduces the temperature rise during the armature emission process,increases the muzzle velocity under identical current excitation,and mitigates directional deformation of the armature.The 1 wt.% graphene-reinforced aluminum matrix composite armature demonstrates better agreement with experimental results at a strain rate of 2000 s^(-1),while simultaneously improving stress-strain response,reducing temperature rise,and improving velocity performance.
基金Supported by the National Natural Science Foundation of China(Grant Nos.12161049,12361008).
文摘Let R be a reduced ring,and k,n be integers with 1≤k≤n.We construct a special subring Tk,n(R),relative to endomorphisms of R,of the upper triangular matrix ring Tn(R)over R and show that Tk,n(R)is semicommutative and Armendariz.Our results yield more examples of semicommutative and Armendariz rings.Also,the maximality of Tk,n(R)in some rings are discussed.
基金Project supported by the National Natural Science Foundation of China(Grant No.61573266)the Natural Science Basic Research Program of Shaanxi(Grant No.2021JM-133)the Fundamental Research Funds for the Central Universities and the Innovation Fund of Xidian University(Grant No.YJSJ25009)。
文摘Efficient implementation of fundamental matrix operations on quantum computers,such as matrix products and Hadamard operations,holds significant potential for accelerating machine learning algorithms.A critical prerequisite for quantum implementations is the effective encoding of classical data into quantum states.We propose two quantum computing frameworks for preparing the distinct encoded states corresponding to matrix operations,including the matrix product,matrix sum,matrix Hadamard product and division.Quantum algorithms based on the digital encoding computing framework are capable of implementing the matrix Hadamard operation with a time complexity of O(poly log(mn/ε))and the matrix product with a time complexity of O(poly log(mnl/ε)),achieving an exponential speedup in contrast to the classical methods of O(mn)and O(mnl).Quantum algorithms based on the analog-encoding framework are capable of implementing the matrix Hadamard operation with a time complexity of O(k_(1)√mn·poly log(mn/ε))and the matrix product with a time complexity of O(k_(2)√1·poly log(mnl/ε)),where k_(1)and k_(2)are coefficients correlated with the elements of the matrix,achieving a square speedup in contrast to the classical counterparts.As applications,we construct an oracle that can access the trace of a matrix within logarithmic time,and propose several algorithms to respectively estimate the trace of a matrix,the trace of the product of two matrices,and the trace inner product of two matrices within logarithmic time.
