The in-plane anisotropy of transition metal trichalcogenides(MX_(3))has a significant impact on the molding of materi-als and MX_(3) is a perfect choice for polarized photodetectors.In this study,the crystal structure...The in-plane anisotropy of transition metal trichalcogenides(MX_(3))has a significant impact on the molding of materi-als and MX_(3) is a perfect choice for polarized photodetectors.In this study,the crystal structure,optical and optoelectronic aniso-tropy of one kind of quasi-one-dimensional(1D)semiconductors,ZrSe_(3),are systematically investigated through experiments and theoretical studies.The ZrSe_(3)-based photodetector shows impressive wide spectral response from ultraviolet(UV)to near in-frared(NIR)and exhibits great optoelectrical properties with photoresponsivity of 11.9 mA·W^(-1) and detectivity of~106 at 532 nm.Moreover,the dichroic ratio of ZrSe_(3)-based polarized photodetector is around 1.1 at 808 nm.This study suggests that ZrSe_(3) has potential in optoelectronic applications and polarization detectors.展开更多
Ti_(0.2)Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2)C-M_(t)C composite ceramic was prepared by hot press sintering,with the Ti_(0.2)Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2)C high-entropy carbide as the main phase.Secondary phase M_(x)C(M...Ti_(0.2)Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2)C-M_(t)C composite ceramic was prepared by hot press sintering,with the Ti_(0.2)Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2)C high-entropy carbide as the main phase.Secondary phase M_(x)C(M=Ti,Zr,Hf,Nb,Ta) was found to be distributed relatively uniform in the composite ceramic.The oxidation behavior of the ceramic was examined after exposure to 923 K and 1173 K.Morphology of the surface and cross sections of all oxidation samples were observed.The characteristics of the oxidation behavior of the high-entropy carbide and the secondary phase M_(x)C were compared and analyzed.The secondary phases(such as Ti-rich carbide or Hf-rich carbide) in the material were seriously oxidized at 923 K and 1173 K,which reflects the superior oxidation performance of the high-entropy carbide.The nano high-entropy oxides with Ti,Zr,Hf,Nb,Ta,and O elements were discovered by oxidation of the composite ceramic.This research will help deepen the understanding of the oxidation mechanism of high-entropy carbide and composite ceramic.展开更多
Twist-angle two-dimensional systems,such as twisted bilayer graphene,twisted bilayer transition metal dichalcogenides,twisted bilayer phosphorene and their multilayer van der Waals heterostructures,exhibit novel and t...Twist-angle two-dimensional systems,such as twisted bilayer graphene,twisted bilayer transition metal dichalcogenides,twisted bilayer phosphorene and their multilayer van der Waals heterostructures,exhibit novel and tunable properties due to the formation of Moirésuperlattice and modulated Moirébands.The review presents a brief venation on the development of"twistronics"and subsequent applications based on band engineering by twisting.Theoretical predictions followed by experimental realization of magic-angle bilayer graphene ignited the flame of investigation on the new freedom degree,twistangle,to adjust(opto)electrical behaviors.Then,the merging of Dirac cones and the presence of flat bands gave rise to enhanced light-matter interaction and gate-dependent electrical phases,respectively,leading to applications in photodetectors and superconductor electronic devices.At the same time,the increasing amount of theoretical simulation on extended twisted 2D materials like TMDs and BPs called for further experimental verification.Finally,recently discovered properties in twisted bilayer h-BN evidenced h-BN could be an ideal candidate for dielectric and ferroelectric devices.Hence,both the predictions and confirmed properties imply twist-angle two-dimensional superlattice is a group of promising candidates for next-generation(opto)electronics.展开更多
In this study,a fast object detection algorithm based on binary deep convolution neural networks(CNNs)is proposed.Convolution kernels of different sizes are used to predict classes and bounding boxes of multi-scale ob...In this study,a fast object detection algorithm based on binary deep convolution neural networks(CNNs)is proposed.Convolution kernels of different sizes are used to predict classes and bounding boxes of multi-scale objects directly in the last feature map of a deep CNN.In this way,rapid object detection with acceptable precision loss is achieved.In addition,binary quantisation for weight values and input data of each layer is used to squeeze the networks for faster object detection.Compared to full-precision convolution,the proposed binary deep CNNs for object detection results in 62 times faster convolutional operations and 32 times memory saving in theory,what’s more,the proposed method is easy to be implemented in embedded computing systems because of the binary operation for convolution and low memory requirement.Experimental results on Pascal VOC2007 validate the effectiveness of the authors’proposed method.展开更多
The immune system plays an essential role in maintaining health,protecting humans from pathogens and preventing the majority of tumors.Immunocompromised individuals are more likely to encounter infectious and neoplast...The immune system plays an essential role in maintaining health,protecting humans from pathogens and preventing the majority of tumors.Immunocompromised individuals are more likely to encounter infectious and neoplastic diseases.Excessive immune responses,which are also involved in the pathogenesis of many diseases,have drawn increasing attention in recent years.^([1])Blood and nervous system manifestations have been reported to be related to some specific viruses,and potential associations of these viruses with autoimmune diseases have come into the spotlight.Certain infections might arouse immune overreaction in susceptible individuals or even cytokine storms that are harmful to organs and tissues.展开更多
We investigate the Kalman filtering problem via wireless sensor networks over fading channels. When part or all of the observation measurements are lost in a random fashion, we obtain the conclusion that the packet dr...We investigate the Kalman filtering problem via wireless sensor networks over fading channels. When part or all of the observation measurements are lost in a random fashion, we obtain the conclusion that the packet dropout probabilities depend upon the time-varying channel gains and the transmission power levels used by the sensors. We develop a satu- rated power controller which trades off sensor energy expenditure versus state estimation accuracy. The latter is measured by the expected value of the future covariance matrices provided by the associated time-varying Kalman filter. We study the statistical convergence properties of the error covariance matrix and pointed out the existence of the admissible packet arrival probability bound.展开更多
Deep neural networks(DNNs)are widely adopted in daily life and the security problems of DNNs have drawn attention from both scientific researchers and industrial engineers.Many related works show that DNNs are vulnera...Deep neural networks(DNNs)are widely adopted in daily life and the security problems of DNNs have drawn attention from both scientific researchers and industrial engineers.Many related works show that DNNs are vulnerable to adversarial examples that are generated with subtle perturbation to original images in both digital domain and physical domain.As a most common application of DNNs,face recognition systems are likely to cause serious consequences if they are attacked by the adversarial examples.In this paper,we implement an adversarial attack system for face recognition in both digital domain that generates adversarial face images to fool the recognition system,and physical domain that generates customized glasses to fool the system when a person wears the glasses.Experiments show that our system attacks face recognition systems effectively.Furthermore,our system could misguide the recognition system to identify a person wearing the customized glasses as a certain target.We hope this research could help raise the attention of artificial intelligence security and promote building robust recognition systems.展开更多
Due to the difficulty that excessive feature dimension in fault diagnosis of rolling bearing will lead to the decrease of classification accuracy,a fault diagnosis method based on Xgboost algorithm feature extraction ...Due to the difficulty that excessive feature dimension in fault diagnosis of rolling bearing will lead to the decrease of classification accuracy,a fault diagnosis method based on Xgboost algorithm feature extraction is proposed.When the Xgboost algorithm classifies features,it generates an order of importance of the input features.The time domain features were extracted from the vibration signal of the rolling bearing,the time-frequency features were formed by the singular value of the modal components that were decomposed by the variational mode decomposition.Firstly,the extracted time domain and time-frequency domain features were input into the support vector machine respectively to observe the fault diagnosis accuracy.Then,Xgboost algorithm was used to rank the importance of features and got the accuracy of fault diagnosis.Finally,important features were extracted and the extracted features were input into the support vector machine to observe the fault diagnosis accuracy.The result shows that the fault diagnosis accuracy of rolling bearing is improved after important feature extraction in time domain and time-frequency domain by Xgboost.展开更多
With the widespread attention on hydrogen energy,the operation optimization of the coupling system of hydrogen energy and transportation has become a critical issue.Therefore,this study develops a hydrogen-containing ...With the widespread attention on hydrogen energy,the operation optimization of the coupling system of hydrogen energy and transportation has become a critical issue.Therefore,this study develops a hydrogen-containing energy transportation coupling system for the system collaborative operation framework,operation mode and equipment modelling of the system.Furthermore,a medium-to long-term operation optimization model and a short-term operation optimization model were constructed considering the differences in the operation of coupled systems at different timescales and operating costs as the objective function and power balance and system equipment as constraints.In the medium-and long-term operation optimization model,the planning scenario reduction method is used to reduce the wind power generation scenario.In the short-term operation optimization model,a multivariate uncertainty model is constructed to represent the uncertainty in the coupling system.Subsequently,the solution method of the model is proposed.Finally,a coupled system is simulated to verify the effectiveness of the model.(i)When the initial scene set is 600,the typical scene reduction method using Latin hypercube sampling and the Wasserstein distance can reduce operating costs by 7.60%and 9.49%compared with K-means reduction and K-media reduction methods.(ii)The sensitivity coefficients of hydrogen sales price,electricity sales price and maintenance rate to operating costs are-0.031%,-1.009%and 0.0105%,respectively.(iii)Considering multiple uncertainties can help make optimal decisions based on the overall consideration of disadvantage scenarios,thereby reducing system operating costs.展开更多
Previous constitutive models of granite shear creep have two limitations：（1） although moisture greatly affects granite shear creep behavior, currently there are no constitutive models that include this factor;（2）...Previous constitutive models of granite shear creep have two limitations：（1） although moisture greatly affects granite shear creep behavior, currently there are no constitutive models that include this factor;（2） there are also no models that include an acceleration stage. This paper presents an improved Burgers constitutive model with the addition of a damage parameter to characterize the moisture effect and uses a nonlinear relation equation between stress and strain for inclusion as the acceleration stage. The damage parameter is determined from granite creep experiment under four different moisture contents（0%, 0.22%, 0.49%, and 0.79%）. The nonlinear relation equation is obtained by fitting a dataset of stain versus time under five different loading stages. To verify the presented model, a creep experiment was conducted on other granite samples and the results show that the model agrees well with the experimental observation data.展开更多
DNA methylation confers epigenetic regulation on gene expression and thereby on various biological processes.Tomato has emerged as an excellent system to study the function of DNA methylation in plant development.To d...DNA methylation confers epigenetic regulation on gene expression and thereby on various biological processes.Tomato has emerged as an excellent system to study the function of DNA methylation in plant development.To date,regulation and function of DNA methylation maintenance remains unclear in tomato plants.Here,we report the critical function of tomato(Solanum lycopersicum)Methyltransferase 1(Sl MET1)in plant development and DNA methylome and transcriptome regulation.Using CRISPR-Cas9 gene editing,we generated slmet1 mutants and observed severe developmental defects with a frame-shift mutation,including small and curly leaves,defective inflorescence,and parthenocarpy.In leaf tissues,mutations in Sl MET1 caused CG hypomethylation and CHH hypermethylationon a whole-genome scale,leading to a disturbed transcriptome including ectopic expression of many RIN target genes such as ACC2 in leaf tissues,which are normally expressed in fruits.Neither the CG hypomethylation nor CHH hypermethylation in the slmet1 mutants is related to tissue culture.Meanwhile,tissue culture induces non-CG hypomethylation,which occurs more frequently at gene regions than at TE regions.Our results depict Sl MET1-and tissue culture-dependent tomato DNA methylomes,and that Sl MET1 is required for maintaining a normal transcriptome and normal development of tomato.展开更多
Background:Gelatin methacryloyl(GelMA)hydrogels loaded with stem cells have proved to be an effective clinical treatment for wound healing.Advanced glycation end product(AGE),interacting with its particular receptor(A...Background:Gelatin methacryloyl(GelMA)hydrogels loaded with stem cells have proved to be an effective clinical treatment for wound healing.Advanced glycation end product(AGE),interacting with its particular receptor(AGER),gives rise to reactive oxygen species(ROS)and apoptosis.Curcumin(Cur)has excellent antioxidant activity and regulates intracellular ROS production and apoptosis.In this study,we developed a Cur-incorporated 3D-printed GelMA to insert into adiposederived stem cells(ADSCs)and applied it to diabetic wounds.Methods:GelMA hydrogels with Cur were fabricated and their in vitro effects on ADSCs were investigated.We used structural characterization,western blot,ROS and apoptosis assay to evaluate the antioxidant and anti-apoptotic activity,and assessed the wound healing effects to investigate the mechanism underlying regulation of apoptosis by Cur via the AGE/AGER/nuclear factor-κB(NF-κB)p65 pathway.Results:A 10%GelMA scaffold exhibited appropriate mechanical properties and biocompatibility for ADSCs.The circular mesh structure demonstrated printability of 10%GelMA and Cur-GelMA bioinks.The incorporation of Cur into the 10%GelMA hydrogel showed an inhibitory effect on AGEs/AGER/NF-κB p65-induced ROS generation and ADSC apoptosis.Furthermore,Cur-GelMA scaffold promoted cell survival and expedited in vivo diabetic wound healing.Conclusions:The incorporation of Cur improved the antioxidant activity of 3D-printed GelMA hydrogel and mitigated AGE/AGER/p65 axis-induced ROS and apoptosis in ADSCs.The effects of scaffolds on wound healing suggested that Cur/GelMA-ADSC hydrogel could be an effective biological material for accelerating wound healing.展开更多
Two-dimensional anisotropic materials have been widely concerned by researchers because of their great application potential in the field of polarized detector devices and optical elements,which is a very important an...Two-dimensional anisotropic materials have been widely concerned by researchers because of their great application potential in the field of polarized detector devices and optical elements,which is a very important and popular research direction at present.As a IV-V two-dimensional material,silicon phosphide(SiP)has obvious in-plane anisotropy and exhibits excellent optical and electrical anisotropy properties.Herein,the optical anisotropy of SiP is studied by spectrometric ellipsometry measurements and polarization-resolved optical microscopy,and its electrical anisotropy is tested by SiP-based field-effect transistor.In addition,the normal and anisotropic photoelectric performance of SiP is shown by fabricating a photodetector and measuring it.In various measurements,SiP exhibits obvious anisotropy and good photoelectric performance.This work provides basic optical,electrical,and photoelectric performance information of SiP,and lays a foundation for further study of SiP and applications of SiP-based devices.展开更多
Dermal substitutes provide a template for dermal regeneration and reconstruction.They constitutes an ideal clinical treatment for deep skin defects.However,rapid vascularization remains as a major hurdle to the develo...Dermal substitutes provide a template for dermal regeneration and reconstruction.They constitutes an ideal clinical treatment for deep skin defects.However,rapid vascularization remains as a major hurdle to the development and application of dermal substitutes.Several bioactive factors play an important regulatory role in the process of angiogenesis and an understanding of the mechanism of achieving their effective delivery and sustained function is vital.Nanomaterials have great potential for tissue engineering.Effective delivery of bioactive factors(including growth factors,peptides and nucleic acids)by nanomaterials is of increasing research interest.This paper discusses the process of dermal substitute angiogenesis and the roles of related bioactive factors in this process.The application of nanomaterials for the delivery of bioactive factors to enhance angiogenesis and accelerate wound healing is also reviewed.We focus on new systems and approaches for delivering bioactive factors for enhancing angiogenesis in dermal substitutes.展开更多
In eukaryotes,histone acetylation is a major modification on histone N-terminal tails that is tightly connected to transcriptional activation.HDA6 is a histone deacetylase involved in the transcriptional regulation of...In eukaryotes,histone acetylation is a major modification on histone N-terminal tails that is tightly connected to transcriptional activation.HDA6 is a histone deacetylase involved in the transcriptional regulation of genes and transposable elements(TEs)in Arabidopsis thaliana.HDA6 has been shown to participate in several complexes in plants,including a conserved SIN3 complex.Here,we uncover a novel protein complex containing HDA6,several Harbinger transposon-derived proteins(HHP1,SANT1,SANT2,SANT3,and SANT4),and MBD domain-containing proteins(MBD1,MBD2,and MBD4).We show that mutations of all four SANT genes in the sant-null mutant cause increased expression of the flowering repressors FLC,MAF4,and MAF5,resulting in a late flowering phenotype.Transcriptome deep sequencing reveals that while the SANT proteins and HDA6 regulate the expression of largely overlapping sets of genes,TE silencing is unaffected in sant-null mutants.Our global histone H3 acetylation profiling shows that SANT proteins and HDA6 modulate gene expression through deacetylation.Collectively,our findings suggest that Harbinger transposon-derived SANT domain-containing proteins are required for histone deacetylation and flowering time control in plants.展开更多
Foreign body reactions induced by macrophages often cause delay or failure of wound healing in the application of tissue engineering scaffolds.This study explores the application of nanosilver(NAg)to reduce foreign bo...Foreign body reactions induced by macrophages often cause delay or failure of wound healing in the application of tissue engineering scaffolds.This study explores the application of nanosilver(NAg)to reduce foreign body reactions during scaffold transplantation.An NAg hybrid collagen-chitosan scaffold(NAg-CCS)was prepared using the freeze-drying method.The NAg-CCS was implanted on the back of rats to evaluate the effects on foreign body reactions.Skin tissue samples were collected for histological and immunological evaluation at variable intervals.Miniature pigs were used to assess the effects of NAg on skin wound healing.The wounds were photographed,and tissue samples were collected for molecular biological analysis at different time points post-transplantation.NAg-CCS has a porous structure and the results showed that it could release NAg constantly for two weeks.The NAg-CCS group rarely developed a foreign body reaction,while the blank-CCS group showed granulomas or necrosis in the subcutaneous grafting experiment.Both matrix metalloproteinase-1(MMP-1)and tissue inhibitor of metalloproteinase-1(TIMP-1)were reduced significantly in the NAg-CCS group.The NAg-CCS group had higher interleukin(IL)-10 and lower IL-6 than the blank CCS group.In the wound healing study,M1 macrophage activation and inflammatory-related proteins inducible nitric oxide synthase(iNOS),IL-6,and interferon-(IFN-)were inhibited by NAg.In contrast,M2 macrophage activation and proinflammatory proteins(arginase-1),major histocompatibility complex-II(MHC-II),and found in inflammatory zone-1(FIZZ-1)were promoted,and this was responsible for suppressing the foreign body responses and accelerating wound healing.In conclusion,dermal scaffolds containing NAg suppressed the foreign body reaction by regulating macrophages and the expression of inflammatory cytokines,thereby promoting wound healing.展开更多
High-temperature mechanical properties of medium-entropy carbide ceramics have attracted significant attention.Tailoring the microstructure is an effective way to improve these high-temperature mechanical properties,w...High-temperature mechanical properties of medium-entropy carbide ceramics have attracted significant attention.Tailoring the microstructure is an effective way to improve these high-temperature mechanical properties,which can be affected by the evolution of the enthalpy and entropy,as well as by lattice distortion and sluggish diffusion.In this study,the effects of equiatomic Zr/(Ti,Nb)substitution(Zr content of 10-40 at%)on the microstructure and high-temperature strength of(Ti,Zr,Nb)C medium-entropy ceramics were investigated.The grain size of the(Ti,Zr,Nb)C medium-entropy ceramics was refined from 9.4±3.7 to 1.1±0.4μm with an increase in the Zr content from 10.0 to 33.3 at%.A further increase in the Zr content to 40 at%resulted in a slight increase in the grain size.At 1900℃,the(Ti,Zr,Nb)C medium-entropy ceramics with the Zr contents of 33.3 and 40 at%exhibited ultra-high flexural strengths of 875±43 and 843±71 MPa,respectively,which were higher than those of the transition metal carbides previously reported under similar conditions.Furthermore,relatively smooth grain boundaries,which were detected at a test temperature of 1000℃,transformed into curved and serrated boundaries as the temperature increased to 1900℃,which may be considered the primary reason for the improved high-temperature flexural strength.The associated mechanism was analyzed and discussed in detail.展开更多
In this study,the direct intercalation of gemini ionic liquids(ILs)with different alkyl chains into the bentonite(BT)interlayer as a high-performance lubricating additive for base oil 500SN was investigated.The purpos...In this study,the direct intercalation of gemini ionic liquids(ILs)with different alkyl chains into the bentonite(BT)interlayer as a high-performance lubricating additive for base oil 500SN was investigated.The purpose of modifying BT with an IL is to improve the dispersion stability and lubricity of BT in lubricating oil.The dispersibility and tribological properties of IL–BT as oil-based additives for 500SN depend on the increase in interlamellar space in BT and improve as the chain length is increased.More importantly,the IL–BT nanomaterial outperforms individual BT in improving wear resistance,owing to its sheet layers were deformed and sprawled in furrows along the metal surface,thereby resulting in low surface adhesion.Because of its excellent lubrication performance,IL-modified BT is a potential candidate for the main component of drilling fluid.It can be used as a lubricating additive in oil drilling and oil well construction to reduce equipment damage and ensure the normal operation of equipments.展开更多
基金financially supported by the National Key Research and Development Program of China (Grant No.2017YFA0207500)the National Natural Science Foundation of China (Grant No. 62125404, 12004375, 62004193,62174155)+1 种基金the CAS-JSPS Cooperative Research Project (No.GJHZ2021131)the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDB43000000)
文摘The in-plane anisotropy of transition metal trichalcogenides(MX_(3))has a significant impact on the molding of materi-als and MX_(3) is a perfect choice for polarized photodetectors.In this study,the crystal structure,optical and optoelectronic aniso-tropy of one kind of quasi-one-dimensional(1D)semiconductors,ZrSe_(3),are systematically investigated through experiments and theoretical studies.The ZrSe_(3)-based photodetector shows impressive wide spectral response from ultraviolet(UV)to near in-frared(NIR)and exhibits great optoelectrical properties with photoresponsivity of 11.9 mA·W^(-1) and detectivity of~106 at 532 nm.Moreover,the dichroic ratio of ZrSe_(3)-based polarized photodetector is around 1.1 at 808 nm.This study suggests that ZrSe_(3) has potential in optoelectronic applications and polarization detectors.
基金Project supported by the Doctoral Research Fund of Southwest University of Science and Technology(Grant No.20zx7104)the Sichuan Science and Technology Program(Grant No.2020ZYD055)the National Natural Science Foundation of China(Grant Nos.11905206 and 12075194)。
文摘Ti_(0.2)Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2)C-M_(t)C composite ceramic was prepared by hot press sintering,with the Ti_(0.2)Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2)C high-entropy carbide as the main phase.Secondary phase M_(x)C(M=Ti,Zr,Hf,Nb,Ta) was found to be distributed relatively uniform in the composite ceramic.The oxidation behavior of the ceramic was examined after exposure to 923 K and 1173 K.Morphology of the surface and cross sections of all oxidation samples were observed.The characteristics of the oxidation behavior of the high-entropy carbide and the secondary phase M_(x)C were compared and analyzed.The secondary phases(such as Ti-rich carbide or Hf-rich carbide) in the material were seriously oxidized at 923 K and 1173 K,which reflects the superior oxidation performance of the high-entropy carbide.The nano high-entropy oxides with Ti,Zr,Hf,Nb,Ta,and O elements were discovered by oxidation of the composite ceramic.This research will help deepen the understanding of the oxidation mechanism of high-entropy carbide and composite ceramic.
基金financially supported by the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB43000000)the CAS-JSPS Cooperative Research Project(No.GJHZ2021131)。
文摘Twist-angle two-dimensional systems,such as twisted bilayer graphene,twisted bilayer transition metal dichalcogenides,twisted bilayer phosphorene and their multilayer van der Waals heterostructures,exhibit novel and tunable properties due to the formation of Moirésuperlattice and modulated Moirébands.The review presents a brief venation on the development of"twistronics"and subsequent applications based on band engineering by twisting.Theoretical predictions followed by experimental realization of magic-angle bilayer graphene ignited the flame of investigation on the new freedom degree,twistangle,to adjust(opto)electrical behaviors.Then,the merging of Dirac cones and the presence of flat bands gave rise to enhanced light-matter interaction and gate-dependent electrical phases,respectively,leading to applications in photodetectors and superconductor electronic devices.At the same time,the increasing amount of theoretical simulation on extended twisted 2D materials like TMDs and BPs called for further experimental verification.Finally,recently discovered properties in twisted bilayer h-BN evidenced h-BN could be an ideal candidate for dielectric and ferroelectric devices.Hence,both the predictions and confirmed properties imply twist-angle two-dimensional superlattice is a group of promising candidates for next-generation(opto)electronics.
基金supported in part by the National Natural Science Foundation of China under grant nos.61573349,61703398 and 61673376in part by the National High Technology Research and Development Program of China(863 Program)under grant no.2015AA042308.
文摘In this study,a fast object detection algorithm based on binary deep convolution neural networks(CNNs)is proposed.Convolution kernels of different sizes are used to predict classes and bounding boxes of multi-scale objects directly in the last feature map of a deep CNN.In this way,rapid object detection with acceptable precision loss is achieved.In addition,binary quantisation for weight values and input data of each layer is used to squeeze the networks for faster object detection.Compared to full-precision convolution,the proposed binary deep CNNs for object detection results in 62 times faster convolutional operations and 32 times memory saving in theory,what’s more,the proposed method is easy to be implemented in embedded computing systems because of the binary operation for convolution and low memory requirement.Experimental results on Pascal VOC2007 validate the effectiveness of the authors’proposed method.
基金supported by Zhejiang Basic Public Welfare Research Program (LGF20H190004)。
文摘The immune system plays an essential role in maintaining health,protecting humans from pathogens and preventing the majority of tumors.Immunocompromised individuals are more likely to encounter infectious and neoplastic diseases.Excessive immune responses,which are also involved in the pathogenesis of many diseases,have drawn increasing attention in recent years.^([1])Blood and nervous system manifestations have been reported to be related to some specific viruses,and potential associations of these viruses with autoimmune diseases have come into the spotlight.Certain infections might arouse immune overreaction in susceptible individuals or even cytokine storms that are harmful to organs and tissues.
文摘We investigate the Kalman filtering problem via wireless sensor networks over fading channels. When part or all of the observation measurements are lost in a random fashion, we obtain the conclusion that the packet dropout probabilities depend upon the time-varying channel gains and the transmission power levels used by the sensors. We develop a satu- rated power controller which trades off sensor energy expenditure versus state estimation accuracy. The latter is measured by the expected value of the future covariance matrices provided by the associated time-varying Kalman filter. We study the statistical convergence properties of the error covariance matrix and pointed out the existence of the admissible packet arrival probability bound.
基金This work is supported in part by the National Natural Science Foundation of China under Grant 61902082,U1636215the Guangdong Province Key research and Development Plan under Grant 2019B010136003.
文摘Deep neural networks(DNNs)are widely adopted in daily life and the security problems of DNNs have drawn attention from both scientific researchers and industrial engineers.Many related works show that DNNs are vulnerable to adversarial examples that are generated with subtle perturbation to original images in both digital domain and physical domain.As a most common application of DNNs,face recognition systems are likely to cause serious consequences if they are attacked by the adversarial examples.In this paper,we implement an adversarial attack system for face recognition in both digital domain that generates adversarial face images to fool the recognition system,and physical domain that generates customized glasses to fool the system when a person wears the glasses.Experiments show that our system attacks face recognition systems effectively.Furthermore,our system could misguide the recognition system to identify a person wearing the customized glasses as a certain target.We hope this research could help raise the attention of artificial intelligence security and promote building robust recognition systems.
基金This work was supported by The National Natural Science Foundation of China(No.51475086)Fundamental Research Funds for the Central Universities of China(No.N162312001)CAST-BISEE Foundation(No.CAST-BISEE2019-019).
文摘Due to the difficulty that excessive feature dimension in fault diagnosis of rolling bearing will lead to the decrease of classification accuracy,a fault diagnosis method based on Xgboost algorithm feature extraction is proposed.When the Xgboost algorithm classifies features,it generates an order of importance of the input features.The time domain features were extracted from the vibration signal of the rolling bearing,the time-frequency features were formed by the singular value of the modal components that were decomposed by the variational mode decomposition.Firstly,the extracted time domain and time-frequency domain features were input into the support vector machine respectively to observe the fault diagnosis accuracy.Then,Xgboost algorithm was used to rank the importance of features and got the accuracy of fault diagnosis.Finally,important features were extracted and the extracted features were input into the support vector machine to observe the fault diagnosis accuracy.The result shows that the fault diagnosis accuracy of rolling bearing is improved after important feature extraction in time domain and time-frequency domain by Xgboost.
基金supported by the State Grid Xinjiang Electric Power Co.,Ltd.Technology Project,‘Analysis model of the impact of multi-dimensional and different proportion penetration of new energy on the incremental cost of the system’(project number SGXJ0000FCJS2310224).
文摘With the widespread attention on hydrogen energy,the operation optimization of the coupling system of hydrogen energy and transportation has become a critical issue.Therefore,this study develops a hydrogen-containing energy transportation coupling system for the system collaborative operation framework,operation mode and equipment modelling of the system.Furthermore,a medium-to long-term operation optimization model and a short-term operation optimization model were constructed considering the differences in the operation of coupled systems at different timescales and operating costs as the objective function and power balance and system equipment as constraints.In the medium-and long-term operation optimization model,the planning scenario reduction method is used to reduce the wind power generation scenario.In the short-term operation optimization model,a multivariate uncertainty model is constructed to represent the uncertainty in the coupling system.Subsequently,the solution method of the model is proposed.Finally,a coupled system is simulated to verify the effectiveness of the model.(i)When the initial scene set is 600,the typical scene reduction method using Latin hypercube sampling and the Wasserstein distance can reduce operating costs by 7.60%and 9.49%compared with K-means reduction and K-media reduction methods.(ii)The sensitivity coefficients of hydrogen sales price,electricity sales price and maintenance rate to operating costs are-0.031%,-1.009%and 0.0105%,respectively.(iii)Considering multiple uncertainties can help make optimal decisions based on the overall consideration of disadvantage scenarios,thereby reducing system operating costs.
基金supported by the National Natural Science Foundation of China (No. 41172281)the National Basic Research Program of China (No. 2011CB710604)the Opening Foundation of the State Key Laboratory of Continental Dynamics, Northwest University (No. 201210126)
文摘Previous constitutive models of granite shear creep have two limitations：（1） although moisture greatly affects granite shear creep behavior, currently there are no constitutive models that include this factor;（2） there are also no models that include an acceleration stage. This paper presents an improved Burgers constitutive model with the addition of a damage parameter to characterize the moisture effect and uses a nonlinear relation equation between stress and strain for inclusion as the acceleration stage. The damage parameter is determined from granite creep experiment under four different moisture contents（0%, 0.22%, 0.49%, and 0.79%）. The nonlinear relation equation is obtained by fitting a dataset of stain versus time under five different loading stages. To verify the presented model, a creep experiment was conducted on other granite samples and the results show that the model agrees well with the experimental observation data.
基金supported by the Chinese Academy of Sciences and by the Thousand Talents Program for Young Scientists,China
文摘DNA methylation confers epigenetic regulation on gene expression and thereby on various biological processes.Tomato has emerged as an excellent system to study the function of DNA methylation in plant development.To date,regulation and function of DNA methylation maintenance remains unclear in tomato plants.Here,we report the critical function of tomato(Solanum lycopersicum)Methyltransferase 1(Sl MET1)in plant development and DNA methylome and transcriptome regulation.Using CRISPR-Cas9 gene editing,we generated slmet1 mutants and observed severe developmental defects with a frame-shift mutation,including small and curly leaves,defective inflorescence,and parthenocarpy.In leaf tissues,mutations in Sl MET1 caused CG hypomethylation and CHH hypermethylationon a whole-genome scale,leading to a disturbed transcriptome including ectopic expression of many RIN target genes such as ACC2 in leaf tissues,which are normally expressed in fruits.Neither the CG hypomethylation nor CHH hypermethylation in the slmet1 mutants is related to tissue culture.Meanwhile,tissue culture induces non-CG hypomethylation,which occurs more frequently at gene regions than at TE regions.Our results depict Sl MET1-and tissue culture-dependent tomato DNA methylomes,and that Sl MET1 is required for maintaining a normal transcriptome and normal development of tomato.
基金supported by Grants from Zhejiang Provincial Basic PublicWelfare Research Program(LGF19H150008)the Natural Science Foundation of Zhejiang province(LGF20H150004).
文摘Background:Gelatin methacryloyl(GelMA)hydrogels loaded with stem cells have proved to be an effective clinical treatment for wound healing.Advanced glycation end product(AGE),interacting with its particular receptor(AGER),gives rise to reactive oxygen species(ROS)and apoptosis.Curcumin(Cur)has excellent antioxidant activity and regulates intracellular ROS production and apoptosis.In this study,we developed a Cur-incorporated 3D-printed GelMA to insert into adiposederived stem cells(ADSCs)and applied it to diabetic wounds.Methods:GelMA hydrogels with Cur were fabricated and their in vitro effects on ADSCs were investigated.We used structural characterization,western blot,ROS and apoptosis assay to evaluate the antioxidant and anti-apoptotic activity,and assessed the wound healing effects to investigate the mechanism underlying regulation of apoptosis by Cur via the AGE/AGER/nuclear factor-κB(NF-κB)p65 pathway.Results:A 10%GelMA scaffold exhibited appropriate mechanical properties and biocompatibility for ADSCs.The circular mesh structure demonstrated printability of 10%GelMA and Cur-GelMA bioinks.The incorporation of Cur into the 10%GelMA hydrogel showed an inhibitory effect on AGEs/AGER/NF-κB p65-induced ROS generation and ADSC apoptosis.Furthermore,Cur-GelMA scaffold promoted cell survival and expedited in vivo diabetic wound healing.Conclusions:The incorporation of Cur improved the antioxidant activity of 3D-printed GelMA hydrogel and mitigated AGE/AGER/p65 axis-induced ROS and apoptosis in ADSCs.The effects of scaffolds on wound healing suggested that Cur/GelMA-ADSC hydrogel could be an effective biological material for accelerating wound healing.
基金the National Natural Science Foundation of China(Nos.62125404,62174155,62004193,12004375,and 51727809)the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDB43000000)the CAS-JSPS Cooperative Research Project(No.GJHZ2021131)the Youth Innovation Promotion Association of CAS(No.2022112).
文摘Two-dimensional anisotropic materials have been widely concerned by researchers because of their great application potential in the field of polarized detector devices and optical elements,which is a very important and popular research direction at present.As a IV-V two-dimensional material,silicon phosphide(SiP)has obvious in-plane anisotropy and exhibits excellent optical and electrical anisotropy properties.Herein,the optical anisotropy of SiP is studied by spectrometric ellipsometry measurements and polarization-resolved optical microscopy,and its electrical anisotropy is tested by SiP-based field-effect transistor.In addition,the normal and anisotropic photoelectric performance of SiP is shown by fabricating a photodetector and measuring it.In various measurements,SiP exhibits obvious anisotropy and good photoelectric performance.This work provides basic optical,electrical,and photoelectric performance information of SiP,and lays a foundation for further study of SiP and applications of SiP-based devices.
基金supported by the National key research and development project(2016YFC1100800,2016YFC1100803)the National Natural Science Foundation of China(81772069,81401591,81801911)the Zhejiang Provincial Basic Public Welfare Research Program(LGF19H150008).
文摘Dermal substitutes provide a template for dermal regeneration and reconstruction.They constitutes an ideal clinical treatment for deep skin defects.However,rapid vascularization remains as a major hurdle to the development and application of dermal substitutes.Several bioactive factors play an important regulatory role in the process of angiogenesis and an understanding of the mechanism of achieving their effective delivery and sustained function is vital.Nanomaterials have great potential for tissue engineering.Effective delivery of bioactive factors(including growth factors,peptides and nucleic acids)by nanomaterials is of increasing research interest.This paper discusses the process of dermal substitute angiogenesis and the roles of related bioactive factors in this process.The application of nanomaterials for the delivery of bioactive factors to enhance angiogenesis and accelerate wound healing is also reviewed.We focus on new systems and approaches for delivering bioactive factors for enhancing angiogenesis in dermal substitutes.
基金This work was supported by grants from the National Key Research and Development Program of China(2020YFE0202300)the Central Public-interest Scientific Institution Basal Research Fund,the BBSRC under the Grant Reference BB/P008569/1 to J.G.C.N.V.and E.dL.,and an Erasmus plus training award to L.G.
文摘In eukaryotes,histone acetylation is a major modification on histone N-terminal tails that is tightly connected to transcriptional activation.HDA6 is a histone deacetylase involved in the transcriptional regulation of genes and transposable elements(TEs)in Arabidopsis thaliana.HDA6 has been shown to participate in several complexes in plants,including a conserved SIN3 complex.Here,we uncover a novel protein complex containing HDA6,several Harbinger transposon-derived proteins(HHP1,SANT1,SANT2,SANT3,and SANT4),and MBD domain-containing proteins(MBD1,MBD2,and MBD4).We show that mutations of all four SANT genes in the sant-null mutant cause increased expression of the flowering repressors FLC,MAF4,and MAF5,resulting in a late flowering phenotype.Transcriptome deep sequencing reveals that while the SANT proteins and HDA6 regulate the expression of largely overlapping sets of genes,TE silencing is unaffected in sant-null mutants.Our global histone H3 acetylation profiling shows that SANT proteins and HDA6 modulate gene expression through deacetylation.Collectively,our findings suggest that Harbinger transposon-derived SANT domain-containing proteins are required for histone deacetylation and flowering time control in plants.
基金supported by the Zhejiang Province Key Research and Development Program(No.2019C03083)the Zhejiang Provincial Basic Public Welfare Research Program(No.LGF19H150008)the National Natural Science Foundation of China(Nos.81601681 and 81871558).
文摘Foreign body reactions induced by macrophages often cause delay or failure of wound healing in the application of tissue engineering scaffolds.This study explores the application of nanosilver(NAg)to reduce foreign body reactions during scaffold transplantation.An NAg hybrid collagen-chitosan scaffold(NAg-CCS)was prepared using the freeze-drying method.The NAg-CCS was implanted on the back of rats to evaluate the effects on foreign body reactions.Skin tissue samples were collected for histological and immunological evaluation at variable intervals.Miniature pigs were used to assess the effects of NAg on skin wound healing.The wounds were photographed,and tissue samples were collected for molecular biological analysis at different time points post-transplantation.NAg-CCS has a porous structure and the results showed that it could release NAg constantly for two weeks.The NAg-CCS group rarely developed a foreign body reaction,while the blank-CCS group showed granulomas or necrosis in the subcutaneous grafting experiment.Both matrix metalloproteinase-1(MMP-1)and tissue inhibitor of metalloproteinase-1(TIMP-1)were reduced significantly in the NAg-CCS group.The NAg-CCS group had higher interleukin(IL)-10 and lower IL-6 than the blank CCS group.In the wound healing study,M1 macrophage activation and inflammatory-related proteins inducible nitric oxide synthase(iNOS),IL-6,and interferon-(IFN-)were inhibited by NAg.In contrast,M2 macrophage activation and proinflammatory proteins(arginase-1),major histocompatibility complex-II(MHC-II),and found in inflammatory zone-1(FIZZ-1)were promoted,and this was responsible for suppressing the foreign body responses and accelerating wound healing.In conclusion,dermal scaffolds containing NAg suppressed the foreign body reaction by regulating macrophages and the expression of inflammatory cytokines,thereby promoting wound healing.
基金Financial supports from the National Natural Science Foundation of China(Nos.52172076,52032001,11575275,and 52102081)the State Key Laboratory of High Performance Ceramics and Superfine Microstructure are greatly appreciated.
文摘High-temperature mechanical properties of medium-entropy carbide ceramics have attracted significant attention.Tailoring the microstructure is an effective way to improve these high-temperature mechanical properties,which can be affected by the evolution of the enthalpy and entropy,as well as by lattice distortion and sluggish diffusion.In this study,the effects of equiatomic Zr/(Ti,Nb)substitution(Zr content of 10-40 at%)on the microstructure and high-temperature strength of(Ti,Zr,Nb)C medium-entropy ceramics were investigated.The grain size of the(Ti,Zr,Nb)C medium-entropy ceramics was refined from 9.4±3.7 to 1.1±0.4μm with an increase in the Zr content from 10.0 to 33.3 at%.A further increase in the Zr content to 40 at%resulted in a slight increase in the grain size.At 1900℃,the(Ti,Zr,Nb)C medium-entropy ceramics with the Zr contents of 33.3 and 40 at%exhibited ultra-high flexural strengths of 875±43 and 843±71 MPa,respectively,which were higher than those of the transition metal carbides previously reported under similar conditions.Furthermore,relatively smooth grain boundaries,which were detected at a test temperature of 1000℃,transformed into curved and serrated boundaries as the temperature increased to 1900℃,which may be considered the primary reason for the improved high-temperature flexural strength.The associated mechanism was analyzed and discussed in detail.
基金the funding support of the National Natural Science Foundation of China(Nos.52075524,21972153,and U21A20280)Youth Innovation Promotion Association,Chinese Academy of Scieneces(Nos.2022429 and 2018454)+2 种基金Gansu Province Science and Technology Plan(Nos.20JR10RA060 and 20JR10RA048)the Lanzhou Institute of Chemical Physics(LICP)Cooperation Foundation for Young Scholars(No.HZJJ21-06)Key Research Projects of Frontier Science of Chinese Academy of Sciences(No.QYZDY-SSW-JSC013).
文摘In this study,the direct intercalation of gemini ionic liquids(ILs)with different alkyl chains into the bentonite(BT)interlayer as a high-performance lubricating additive for base oil 500SN was investigated.The purpose of modifying BT with an IL is to improve the dispersion stability and lubricity of BT in lubricating oil.The dispersibility and tribological properties of IL–BT as oil-based additives for 500SN depend on the increase in interlamellar space in BT and improve as the chain length is increased.More importantly,the IL–BT nanomaterial outperforms individual BT in improving wear resistance,owing to its sheet layers were deformed and sprawled in furrows along the metal surface,thereby resulting in low surface adhesion.Because of its excellent lubrication performance,IL-modified BT is a potential candidate for the main component of drilling fluid.It can be used as a lubricating additive in oil drilling and oil well construction to reduce equipment damage and ensure the normal operation of equipments.
