With the development of Internet technology,the explosive growth of Internet information presentation has led to difficulty in filtering effective information.Finding a model with high accuracy for text classification...With the development of Internet technology,the explosive growth of Internet information presentation has led to difficulty in filtering effective information.Finding a model with high accuracy for text classification has become a critical problem to be solved by text filtering,especially for Chinese texts.This paper selected the manually calibrated Douban movie website comment data for research.First,a text filtering model based on the BP neural network has been built;Second,based on the Term Frequency-Inverse Document Frequency(TF-IDF)vector space model and the doc2vec method,the text word frequency vector and the text semantic vector were obtained respectively,and the text word frequency vector was linearly reduced by the Principal Component Analysis(PCA)method.Third,the text word frequency vector after dimensionality reduction and the text semantic vector were combined,add the text value degree,and the text synthesis vector was constructed.Experiments show that the model combined with text word frequency vector degree after dimensionality reduction,text semantic vector,and text value has reached the highest accuracy of 84.67%.展开更多
This paper proposes a novel optimization scheme to support stable and reliable vehicle-to-everything connections in two-tier networks,where the uplink channel of the cellular user is reused by underlay vehicle-to-vehi...This paper proposes a novel optimization scheme to support stable and reliable vehicle-to-everything connections in two-tier networks,where the uplink channel of the cellular user is reused by underlay vehicle-to-vehicle communications.However,considering complex channel fading and high-speed vehicle movement,the cer-tainty assumption is impractical and fails to maintain power control strategy in reality in the traditional statical vehicular networks.Rather than the perfect channel state information assumption,the first-order Gauss-Markov process which is a probabilistic model affected by vehicle speed and fading is introduced to describe imperfect channel gains.Moreover,interference management is a major challenge in reusing communications,especially in uncertain channel environments.Power control is an effective way to realize interference management,and optimal power allocation can ensure that interference of the user meets the communication requirements.In this study,the sum-rate-oriented power control scheme and minimum-rate-oriented power control scheme were implemented to manage interference and satisfy different design objectives.Since both of these schemes are non-convex and intractable,the Bernstein approximation and successive convex approximation methods were adopted to transform the original problems into convex ones.Furthermore,a novel distributed robust power control al-gorithm was developed to determine the optimal solutions.The performance of the algorithm was evaluated through numerical simulations,and the results indicate that the proposed algorithm is effective in vehicular communication networks with uncertain channel environments.展开更多
Remote tracking for mobile targets is one of the most important applications in wireless sensor networks (WSNs). A target tracking protoco–exponential distributed predictive tracking (EDPT) is proposed. To reduce...Remote tracking for mobile targets is one of the most important applications in wireless sensor networks (WSNs). A target tracking protoco–exponential distributed predictive tracking (EDPT) is proposed. To reduce energy waste and response time, an improved predictive algorithm–exponential smoothing predictive algorithm (ESPA) is presented. With the aid of an additive proportion and differential (PD) controller, ESPA decreases the system predictive delay effectively. As a recovery mechanism, an optimal searching radius (OSR) algorithm is applied to calculate the optimal radius of the recovery zone. The simulation results validate that the proposed EDPT protocol performes better in terms of track failed ratio, energy waste ratio and enlarged sensing nodes ratio, respectively.展开更多
The traditional orthogonal multiple access(OMA)is unable to satisfy the needs of large number of smart devices.To increase the transmission rate in the limited spectrum resource,implementation of both non-orthogonal m...The traditional orthogonal multiple access(OMA)is unable to satisfy the needs of large number of smart devices.To increase the transmission rate in the limited spectrum resource,implementation of both non-orthogonal multiple access(NOMA)and successive interference cancelation(SIC)is essential.In this paper,an optimal resource allocation algorithm in NOMA is proposed to maximize the total system rate in a multi-sector multi-subcarrier relay-assisted communication network.Since the original problem is a non-convex problem with mixed integer programming which is non-deterministic polynomial-time(NP)-hard,a three-step solution is proposed to solve the primal problem.Firstly,we determine the optimal power allocation of the outer users by using the approach of monotonic discrimination,and then the optimal user pairing is determined.Secondly,the successive convex approximation(SCA)method is introduced to transform the non-convex problem involving central users into convex one,and the Lagrangian dual method is used to determine the optimal solution.Finally,the standard Hungarian algorithm is utilized to determine the optimal subcarrier matching.The simulation results show that resource allocation algorithm is able to meet the user performance requirements with NOMA,and the total system rate is improved compared to the existing algorithms.展开更多
Two new A-D-A porphyrin derivatives,denoted as XLP-I and XLP-II,were prepared through extending theπ-conjugation of thienothiophene-porphyrin center with phenylethynyl bridges and electron-deficient ethylrhodanine te...Two new A-D-A porphyrin derivatives,denoted as XLP-I and XLP-II,were prepared through extending theπ-conjugation of thienothiophene-porphyrin center with phenylethynyl bridges and electron-deficient ethylrhodanine terminal units,and varying the structures of alkyl chain(linear vs branched)on peripheral thienothiophene substitutions of porphyrin rings.Both molecules show strong absorption in UV–visible–near-infrared region,good thermal stability,suitable energy levels,and ordered molecular packing in solid state.In organic solar cells,PC71BM was used as electron acceptor,and porphyrin small molecules were used as electron donors.The device based on XLP-I exhibits a power conversion efficiency(PCE)of 8.30%,an open circuit voltage(Voc)of 0.894 eV,and a fill factor(FF)of 62.1%.In contrast,the device based on XLP-II presents an inferior performance with a PCE of 3.14%,a Voc of 0.847 eV,and a FF of 49.3%.The better performance of XLP-I based device is mainly attributed to its optimized film morphology,excellent absorption,and well-balanced charge transport properties.展开更多
Photonic topological insulators with robust boundary states can enable great applications for optical communication and quantum emission,such as unidirectional waveguide and single-mode laser.However,because of the di...Photonic topological insulators with robust boundary states can enable great applications for optical communication and quantum emission,such as unidirectional waveguide and single-mode laser.However,because of the diffraction limit of light,the physical insight of topological resonance remains unexplored in detail,like the dark line that exists with the crys-talline symmetry-protected topological edge state.Here,we experimentally observe the dark line of the Z_(2)photonic topo-logical insulator in the visible range by photoluminescence and specify its location by cathodoluminescence characteriza-tion,and elucidate its mechanism with the p-d orbital electromagnetic field distribution which calculated by numerical sim-ulation.Our investigation provides a deeper understanding of Z_(2)topological edge states and may have great signific-ance to the design of future on-chip topological devices.展开更多
Huanglongbing (HLB) is the most destructive disease of citrus worldwide. The disease is caused by Candidatus Liberibacter spp., which is vectored by the psyllids Diaphorina citri Kuwayama and Trioza erytreae. Secretor...Huanglongbing (HLB) is the most destructive disease of citrus worldwide. The disease is caused by Candidatus Liberibacter spp., which is vectored by the psyllids Diaphorina citri Kuwayama and Trioza erytreae. Secretory proteins are important in bacterial pathogenesis and structure components. Some of them are expressed at a high level. To obtain the highly-expressed secretory protein genes (SPGs) for antiserum preparation, six candidate SPGs were chosen from Candidatus Liberibacter asiaticus by bioinformatic analysis and were further tested by qPCR and RT-qPCR methods, respectively. The result showed that two SPGs, 408 and pap (both are Flp pilus assembly protein genes), have relative high amounts of DNA and RNA transcripts of early HLB-infected green orange leaves. The 408 and pap genes were further constructed into the plant expression vector pCAMBIA1300 (GV1300: GFP) and expressed in tobacco leaf epidermal cells for subcellular localization analysis. The transient expression results indicated that the 408 protein is located in the nuclei and cytoplasm of tobacco leaf cells. However, the pap protein is located in the cytoplasm of tobacco leaf cells, which may help the pathogen invade into plant cells. This research is an important foundation for the preparation of the antiserum against Candidatus Liberibacter asiaticus and the early detection of HLB disease.展开更多
Protein and protein interactions play important roles in many biological processes and are responsible for carrying out the function of biological regulatory network in living organisms. Previous study indicated that ...Protein and protein interactions play important roles in many biological processes and are responsible for carrying out the function of biological regulatory network in living organisms. Previous study indicated that Banana bunchy top virus (BBTV) coat protein (CP) interacted with BBTV nuclear shuttle protein (NSP). However, the protein and protein interaction and the binding affinity of CP and NSP in Babuvirus are remaining unclear. In this study, the CPs and NSPs proteins of BBTV, Abaca bunchy top virus (ABTV) and Cardamom bushy dwarf virus (CBDV) were used for bioinformatic analysis. The binding free energy and the dissociation constant of the possible interaction proteins were tested in PPA-Pred2, and the results confirmed CP interaction with NSP in Babuvirus. The study will help us to understand the interaction between viral protein and viral protein, and the pathogenesis mechanism of Babuvirus in host plants.展开更多
Cathodoluminescence (CL) as a radiative light produced by an electron beam exciting a luminescent material, has beenwidely used in imaging and spectroscopic detection of semiconductor, mineral and biological samples...Cathodoluminescence (CL) as a radiative light produced by an electron beam exciting a luminescent material, has beenwidely used in imaging and spectroscopic detection of semiconductor, mineral and biological samples with an ultrahigh spatial resolution. Conventional CL spectroscopy shows an excellent performance in characterization of traditional mate-rial luminescence, such as spatial composition variations and fluorescent displays. With the development of nanotech-nology, advances of modern microscopy enable CL technique to obtain deep valuable insight of the testing sample, and further extend its applications in the material science, especially for opto-electronic investigations at nanoscale. In this article, we review the study of CL microscopy applied in semiconductor nanostructures for the dislocation, carrier diffu-sion, band structure, doping level and exciton recombination. Then advantages of CL in revealing and manipulating sur-face plasmon resonances of metallic nanoantennas are discussed. Finally, the challenge of CL technology is summa-rized, and potential CL applications for the future opto-electronic study are proposed.展开更多
According to the data of banana transcriptome sequencing, an E3 ubiquitin-protein ligase gene was cloned by RT-PCR method using the cDNA sample of banana leaves. The complete ORF of E3 ubiquitin-protein ligase is 681 ...According to the data of banana transcriptome sequencing, an E3 ubiquitin-protein ligase gene was cloned by RT-PCR method using the cDNA sample of banana leaves. The complete ORF of E3 ubiquitin-protein ligase is 681 bp long and its encoded protein showed 100% sequence identity to homologue RING-H2 finger protein (XP_009407047.1) of Musa_acuminata. Bioinformatic analysis indicated that E3 ubiquitin-protein ligase contains the Ring finger domain in C terminus and eight cross-brace motifs are found in the domain. The target gene was digested by EcoR V and EcoR I, and was inserted into prokaryotic expression vector pET-32a of the same digestions to obtain the plasmid pET32a-E3 ubiquitin-protein ligase. The recombinant plasmid was introduced into Escherichia coli strain BL21 (DE3), and induced at 25°C with 0.4 mmol/L IPTG for 6 hours. The soluble fusion protein was expressed and high purity fusion protein was obtained by Ni<sup>2+</sup>-NTA agarose affinity chromatography purification. The fusion protein was injected into mice 3 times to prepare the antiserum. Western blot analysis showed a specific protein band was detected in total protein sample of banana leaves, but not for the samples of wild-type Nicotiana benthamiana (N.B.) and wild-type Arabidopsis thaliana (A.T.), implying the antiserum was specific to banana E3 ubiquitin-protein ligase.展开更多
Redox-active organic materials are capturing growing attention as cathode materials for sustainable alkaline metal ion batteries.However,the storage of Na+in most organic materials-based cathodes is plagued by low cap...Redox-active organic materials are capturing growing attention as cathode materials for sustainable alkaline metal ion batteries.However,the storage of Na+in most organic materials-based cathodes is plagued by low capacity and unsatisfying rate performance due to their low active site densities and limited exposed active sites.Herein,two polyimide-linked covalent organic frameworks(COFs),namely HATN-PD-COF and HATN-TAB-COF,were fabricated from hydrothermal synthesis with redoxactive triphenylene-2,3,6,7,10,11-hexacarboxylic acid and aromatic amines as starting materials.Powder X-ray diffraction and electron microscopy analysis indicate the high crystalline nature of these COFs with AA stacking configuration and orderly mesoporous tunnel.N_(2) sorption measurement discloses the permanent porosity of these two COFs with a Brunauer-EmmettTeller surface area of 1,065-1,200 m^(2)g^(-1)and a large pore size of 2.0-3.1 nm.Galvanostatic intermittent titration technique and density functional theory calculations reveal the facile Na+ion diffusion along the mesoporous tunnel of these COFs with a small energy barrier of 0.13-0.40 e V.In particular,the as-prepared COFs based-cathodes show ultrafast and stable Na+storage associated with their conjugated electronic structure,highly ordered mesoporous tunnel,robust structure,and redox-active C=N/C=O-rich framework as exemplified by the high reversible capacity of 210 m A h g^(-1)at 200 m A g^(-1),record-high rate performance(195 m A h g^(-1)at a high current density of 10,000 m A g^(-1))among organic electrodes and the capacity retention of nearly 91%at 10,000 m A g^(-1)after 7,000 cycles for HATN-PD-COF.展开更多
In this paper,we investigate the distributed estimation problem of continuous-time stochastic dynamic systems over sensor networks when both the system order and parameters are unknown.We propose a local information c...In this paper,we investigate the distributed estimation problem of continuous-time stochastic dynamic systems over sensor networks when both the system order and parameters are unknown.We propose a local information criterion(LIC)based on the L_(0)penalty term.By minimizing LIC at the diffusion time instant and utilizing the continuous-time diffusion least squares algorithm,we obtain a distributed estimation algorithm to simultaneously estimate the unknown order and the parameters of the system.By dealing with the effect of the system noises and the coupling relationship between estimation of system orders and parameters,we establish the almost sure convergence results of the proposed distributed estimation algorithm.Furthermore,we give a simulation example to verify the effectiveness of the distributed algorithm in estimating the system order and parameters.展开更多
Chemical sensor arrays can obtain more comprehensive analyte information through high-dimensional data.It is of great significance in the analysis of multi-component complex samples.This review summarizes the developm...Chemical sensor arrays can obtain more comprehensive analyte information through high-dimensional data.It is of great significance in the analysis of multi-component complex samples.This review summarizes the development and status of chemical sensor arrays.We focused on the design of chemical sensor arrays based on various sensing materials.In addition,several pattern recognition methods in chemometrics are introduced.And applications of chemical sensor arrays in food monitoring,medical diagnosis,and environmental monitoring are illustrated.Based on the analysis of the limitations of current sensor array technology,the direction of the array is also predicted.This review aims to help the broad readership understand the research state of chemical sensor arrays and their development prospects.展开更多
Allogeneic red blood cell(RBC)transfusion is commonly performed in medical practice because of its efficacy and low-risk level.However,pre-transfusion tests are susceptible to monoclonal antibody(mAb)interference.1 Cu...Allogeneic red blood cell(RBC)transfusion is commonly performed in medical practice because of its efficacy and low-risk level.However,pre-transfusion tests are susceptible to monoclonal antibody(mAb)interference.1 Currently,mAb therapies are being developed to treat many diseases,such as cancer.However,certain mAbs,such as anti-CD38mAb and anti-CD47mAb,can bind to RBC membranes;this binding interferes with pre-transfusion tests.2 CD47 has gained considerable attention in recent years because of its potential as a therapeutic target for hematologic malignancies and solid tumors.3 The binding of anti-CD47mAb to RBCs may lead to false-positive results in pan-agglutination tests and cause delays and risks in establishing compatible RBCs for transfusion.展开更多
Electrocatalytic synthesis of urea from CO_(2)and NO_(3)^(-)under ambient conditions provides an appealing alternative to the traditional energy-intensive urea synthetic protocol.Highly active and selective electrocat...Electrocatalytic synthesis of urea from CO_(2)and NO_(3)^(-)under ambient conditions provides an appealing alternative to the traditional energy-intensive urea synthetic protocol.Highly active and selective electrocatalysts for efficient urea production are therefore urgently desired owing to the unsatisfactory performance of the thus far reported catalysts.Herein,a phthalocyaninebased(Pc-based)covalent organic framework(COF),namely Co Pc-COF,fabricated from the nucleophilic substitution reaction of hexadecafluorophthalocyaninato cobalt with octahydroxylphthalocyanine cobalt,in situ grew on the surface of multilayered Ti O_(2)nanotubes(NTs),generating the Co Pc-COF@Ti O_(2)NTs composite.Powder X-ray diffraction analysis in combination with electron microscopy measurements discloses the uniform coating of crystalline Co Pc-COF on the multilayered Ti O_(2)NTs in Co Pc-COF@Ti O_(2)NTs.Remarkably,electrochemical tests reveal the superior electrocatalytic activity of Co Pc-COF@Ti O_(2)NTs towards urea production from CO_(2)and NO3-with a record-high yield of 1,205μg h^(-1)cm^(-2)and an outstanding Faraday efficiency of 49%at-0.6 V versus reversible hydrogen electrode due to the significant synergistic catalysis effect.In situ attenuated total reflection infrared spectroscopic investigation and theoretical calculations unveil the efficient C–N coupling reaction between*CO intermediate derived from CO_(2)on Co Pc moieties and*NH2intermediate formed from NO_(3)^(-)on Ti O_(2)NTs during the urea formation process over Co Pc-COF@Ti O_(2)NTs.This work should be helpful towards designing and fabricating high-performance electrocatalysts for sustainable synthesis of urea through efficient synergistic effect of multiactive centers.展开更多
Plants contain a large number of cell types and exhibit complex regulatory mechanisms.Studies at the single-cell level have gradually become more common in plant science.Single-cell transcriptomics,spatial transcripto...Plants contain a large number of cell types and exhibit complex regulatory mechanisms.Studies at the single-cell level have gradually become more common in plant science.Single-cell transcriptomics,spatial transcriptomics,and spatial metabolomics techniques have been combined to analyze plant development.These techniques have been used to study the transcriptomes and metabolomes of plant tissues at the single-cell level,enabling the systematic investigation of gene expression and metabolism in specific tissues and cell types during defined developmental stages.In this review,we present an overview of significant breakthroughs in spatial multi-omics in plants,and we discuss how these approaches may soon play essential roles in plant research.展开更多
With the development of tyrosine kinase inhibitor(TKI)resistance,finding the novel effective chemotherapeutic agent is of seminal importance for chronic myelogenous leukemia(CML)treatment.This study aims to find the e...With the development of tyrosine kinase inhibitor(TKI)resistance,finding the novel effective chemotherapeutic agent is of seminal importance for chronic myelogenous leukemia(CML)treatment.This study aims to find the effective anti-leukemic candidates and investigate the possible underlying mechanism.We synthesized the novel coumarin derivatives and evaluated their anti-leukemic activity.Cell viability assay revealed that compound DBH2 exhibited the potent inhibitory activity on the proliferation of CML K562 cells and TKI resistant K562 cells.Morphological observation and flow cytometry confirmed that DBH2 could selectively induce cell apoptosis and cell cycle arrest at G2/M phase of the K562 cells,which was further confirmed on the bone marrow cells from CML transgenic model mice and CD34+bone marrow leukemic cells from CML patients.Treatments of DBH2 in combination with imatinib could prolong the survival rate of SCL-tTA-BCR/ABL transgenic model mice significantly.Quantitative RT-PCR revealed that DBH2 inhibited the expression of STAT3 and STAT5 in K562 cells,and caspase-3 knockout alleviated the DBH2 induced apoptosis.Furthermore,DBH2 could induce the expression of PARP1 and ROCK1 in K562 cells,which may play the important role in caspase-dependent apoptosis.Our results concluded that coumarin derivative DBH2 serves as a promising candidate for the CML treatment,especially in the combination with imatinib for the TKI resistant CML,and STAT/caspase-3 pathway was involved in the molecular mechanism of anti-leukemic activity of DBH2.展开更多
The manipulation of polarization states beyond the optical limit presents advantages in various applications.Considerable progress has been made in the design of meta-waveplates for on-demand polarization transformati...The manipulation of polarization states beyond the optical limit presents advantages in various applications.Considerable progress has been made in the design of meta-waveplates for on-demand polarization transformation,realized by numerical simulations and parameter sweep methodologies.However,due to the limited freedom in these classical strategies,particular challenges arise from the emerging requirement for multiplex optical devices and multidimensional manipulation of light,which urge for a large number of different nanostructures with great polarization control capability.Here,we demonstrate a set of self-designed arbitrary wave plates with a high polarization conversion efficiency.We combine Bayesian optimization and deep neural networks to design perfect halfand quarter-waveplates based on metallic nanostructures,which experimentally demonstrate excellent polarization control functionalities with the conversion ratios of 85%and 90%.More broadly,we develop a comprehensive wave plate database consisting of various metallic nanostructures with high polarization conversion efficiency,accompanying a flexible tuning of phase shifts(0-2π)and group delays(0-10 fs),and construct an achromatic metalens based on this database.Owing to the versatility and excellent performance,our self-designed wave plates can promote the performance of multiplexed broadband metasurfaces and find potential applications in compact optical devices and polarization division multiplexing optical communications.展开更多
基金Supported by the Sichuan Science and Technology Program (2021YFQ0003).
文摘With the development of Internet technology,the explosive growth of Internet information presentation has led to difficulty in filtering effective information.Finding a model with high accuracy for text classification has become a critical problem to be solved by text filtering,especially for Chinese texts.This paper selected the manually calibrated Douban movie website comment data for research.First,a text filtering model based on the BP neural network has been built;Second,based on the Term Frequency-Inverse Document Frequency(TF-IDF)vector space model and the doc2vec method,the text word frequency vector and the text semantic vector were obtained respectively,and the text word frequency vector was linearly reduced by the Principal Component Analysis(PCA)method.Third,the text word frequency vector after dimensionality reduction and the text semantic vector were combined,add the text value degree,and the text synthesis vector was constructed.Experiments show that the model combined with text word frequency vector degree after dimensionality reduction,text semantic vector,and text value has reached the highest accuracy of 84.67%.
基金supported by National Natural Science Foundation of China under grant 61873223,61803328the Natural Science Foundation of Hebei Province under grant F2019203095Beijing Natural Science Foundation under grant L201002.
文摘This paper proposes a novel optimization scheme to support stable and reliable vehicle-to-everything connections in two-tier networks,where the uplink channel of the cellular user is reused by underlay vehicle-to-vehicle communications.However,considering complex channel fading and high-speed vehicle movement,the cer-tainty assumption is impractical and fails to maintain power control strategy in reality in the traditional statical vehicular networks.Rather than the perfect channel state information assumption,the first-order Gauss-Markov process which is a probabilistic model affected by vehicle speed and fading is introduced to describe imperfect channel gains.Moreover,interference management is a major challenge in reusing communications,especially in uncertain channel environments.Power control is an effective way to realize interference management,and optimal power allocation can ensure that interference of the user meets the communication requirements.In this study,the sum-rate-oriented power control scheme and minimum-rate-oriented power control scheme were implemented to manage interference and satisfy different design objectives.Since both of these schemes are non-convex and intractable,the Bernstein approximation and successive convex approximation methods were adopted to transform the original problems into convex ones.Furthermore,a novel distributed robust power control al-gorithm was developed to determine the optimal solutions.The performance of the algorithm was evaluated through numerical simulations,and the results indicate that the proposed algorithm is effective in vehicular communication networks with uncertain channel environments.
基金supported by the National Basic Research Program of China (973 Program) (2010CB731800)the National Natural Science Foundation of China (60934003+2 种基金 60974123 60804010)the Hebei Provincial Educational Foundation of China (2008147)
文摘Remote tracking for mobile targets is one of the most important applications in wireless sensor networks (WSNs). A target tracking protoco–exponential distributed predictive tracking (EDPT) is proposed. To reduce energy waste and response time, an improved predictive algorithm–exponential smoothing predictive algorithm (ESPA) is presented. With the aid of an additive proportion and differential (PD) controller, ESPA decreases the system predictive delay effectively. As a recovery mechanism, an optimal searching radius (OSR) algorithm is applied to calculate the optimal radius of the recovery zone. The simulation results validate that the proposed EDPT protocol performes better in terms of track failed ratio, energy waste ratio and enlarged sensing nodes ratio, respectively.
基金This work was partly supported by the Natural Science Foundation of Hebei Province(F2019203095)the National Natural Science Foundation of China(61873223,61803328)the National Key R&D Program of China(2018YFB1702100)。
文摘The traditional orthogonal multiple access(OMA)is unable to satisfy the needs of large number of smart devices.To increase the transmission rate in the limited spectrum resource,implementation of both non-orthogonal multiple access(NOMA)and successive interference cancelation(SIC)is essential.In this paper,an optimal resource allocation algorithm in NOMA is proposed to maximize the total system rate in a multi-sector multi-subcarrier relay-assisted communication network.Since the original problem is a non-convex problem with mixed integer programming which is non-deterministic polynomial-time(NP)-hard,a three-step solution is proposed to solve the primal problem.Firstly,we determine the optimal power allocation of the outer users by using the approach of monotonic discrimination,and then the optimal user pairing is determined.Secondly,the successive convex approximation(SCA)method is introduced to transform the non-convex problem involving central users into convex one,and the Lagrangian dual method is used to determine the optimal solution.Finally,the standard Hungarian algorithm is utilized to determine the optimal subcarrier matching.The simulation results show that resource allocation algorithm is able to meet the user performance requirements with NOMA,and the total system rate is improved compared to the existing algorithms.
基金the national key R&D program for international collaboration(No.2021YFE0191500)the National Natural Science Foundation of China(No.51473053)+3 种基金the Natural Science Foundation of Hunan Province(No.2019JJ50603)the Peacock Team Project funding from Shenzhen Science and Technology Innovation Committee(No.KQTD2015033110182370)the Fundamental Research Project funding from Shenzhen Science and Technology Innovation Committee(No.JCYJ 20190809150213448).X.Zhu thanks the financial support from Hong Kong Research Grants Council(HKBU 12304320).
文摘Two new A-D-A porphyrin derivatives,denoted as XLP-I and XLP-II,were prepared through extending theπ-conjugation of thienothiophene-porphyrin center with phenylethynyl bridges and electron-deficient ethylrhodanine terminal units,and varying the structures of alkyl chain(linear vs branched)on peripheral thienothiophene substitutions of porphyrin rings.Both molecules show strong absorption in UV–visible–near-infrared region,good thermal stability,suitable energy levels,and ordered molecular packing in solid state.In organic solar cells,PC71BM was used as electron acceptor,and porphyrin small molecules were used as electron donors.The device based on XLP-I exhibits a power conversion efficiency(PCE)of 8.30%,an open circuit voltage(Voc)of 0.894 eV,and a fill factor(FF)of 62.1%.In contrast,the device based on XLP-II presents an inferior performance with a PCE of 3.14%,a Voc of 0.847 eV,and a FF of 49.3%.The better performance of XLP-I based device is mainly attributed to its optimized film morphology,excellent absorption,and well-balanced charge transport properties.
基金supported by the National Key Research and Development Program of China (grant no.2017YFA0206000)Beijing Natural Science Foundation (grant nos. Z180011)+3 种基金the National Key Research and Development Program of China (grant nos. 2020YFA0211300, 2017YFA0205700, 2019YFA0210203,2018YFA0306200)National Science Foundation of China (grant nos. 12027807, 61521004, 21790364 and 11625418)PKUBaidu Fund Project (grant no.2020BD023)High-performance Computing Platform of Peking University
文摘Photonic topological insulators with robust boundary states can enable great applications for optical communication and quantum emission,such as unidirectional waveguide and single-mode laser.However,because of the diffraction limit of light,the physical insight of topological resonance remains unexplored in detail,like the dark line that exists with the crys-talline symmetry-protected topological edge state.Here,we experimentally observe the dark line of the Z_(2)photonic topo-logical insulator in the visible range by photoluminescence and specify its location by cathodoluminescence characteriza-tion,and elucidate its mechanism with the p-d orbital electromagnetic field distribution which calculated by numerical sim-ulation.Our investigation provides a deeper understanding of Z_(2)topological edge states and may have great signific-ance to the design of future on-chip topological devices.
文摘Huanglongbing (HLB) is the most destructive disease of citrus worldwide. The disease is caused by Candidatus Liberibacter spp., which is vectored by the psyllids Diaphorina citri Kuwayama and Trioza erytreae. Secretory proteins are important in bacterial pathogenesis and structure components. Some of them are expressed at a high level. To obtain the highly-expressed secretory protein genes (SPGs) for antiserum preparation, six candidate SPGs were chosen from Candidatus Liberibacter asiaticus by bioinformatic analysis and were further tested by qPCR and RT-qPCR methods, respectively. The result showed that two SPGs, 408 and pap (both are Flp pilus assembly protein genes), have relative high amounts of DNA and RNA transcripts of early HLB-infected green orange leaves. The 408 and pap genes were further constructed into the plant expression vector pCAMBIA1300 (GV1300: GFP) and expressed in tobacco leaf epidermal cells for subcellular localization analysis. The transient expression results indicated that the 408 protein is located in the nuclei and cytoplasm of tobacco leaf cells. However, the pap protein is located in the cytoplasm of tobacco leaf cells, which may help the pathogen invade into plant cells. This research is an important foundation for the preparation of the antiserum against Candidatus Liberibacter asiaticus and the early detection of HLB disease.
文摘Protein and protein interactions play important roles in many biological processes and are responsible for carrying out the function of biological regulatory network in living organisms. Previous study indicated that Banana bunchy top virus (BBTV) coat protein (CP) interacted with BBTV nuclear shuttle protein (NSP). However, the protein and protein interaction and the binding affinity of CP and NSP in Babuvirus are remaining unclear. In this study, the CPs and NSPs proteins of BBTV, Abaca bunchy top virus (ABTV) and Cardamom bushy dwarf virus (CBDV) were used for bioinformatic analysis. The binding free energy and the dissociation constant of the possible interaction proteins were tested in PPA-Pred2, and the results confirmed CP interaction with NSP in Babuvirus. The study will help us to understand the interaction between viral protein and viral protein, and the pathogenesis mechanism of Babuvirus in host plants.
文摘Cathodoluminescence (CL) as a radiative light produced by an electron beam exciting a luminescent material, has beenwidely used in imaging and spectroscopic detection of semiconductor, mineral and biological samples with an ultrahigh spatial resolution. Conventional CL spectroscopy shows an excellent performance in characterization of traditional mate-rial luminescence, such as spatial composition variations and fluorescent displays. With the development of nanotech-nology, advances of modern microscopy enable CL technique to obtain deep valuable insight of the testing sample, and further extend its applications in the material science, especially for opto-electronic investigations at nanoscale. In this article, we review the study of CL microscopy applied in semiconductor nanostructures for the dislocation, carrier diffu-sion, band structure, doping level and exciton recombination. Then advantages of CL in revealing and manipulating sur-face plasmon resonances of metallic nanoantennas are discussed. Finally, the challenge of CL technology is summa-rized, and potential CL applications for the future opto-electronic study are proposed.
文摘According to the data of banana transcriptome sequencing, an E3 ubiquitin-protein ligase gene was cloned by RT-PCR method using the cDNA sample of banana leaves. The complete ORF of E3 ubiquitin-protein ligase is 681 bp long and its encoded protein showed 100% sequence identity to homologue RING-H2 finger protein (XP_009407047.1) of Musa_acuminata. Bioinformatic analysis indicated that E3 ubiquitin-protein ligase contains the Ring finger domain in C terminus and eight cross-brace motifs are found in the domain. The target gene was digested by EcoR V and EcoR I, and was inserted into prokaryotic expression vector pET-32a of the same digestions to obtain the plasmid pET32a-E3 ubiquitin-protein ligase. The recombinant plasmid was introduced into Escherichia coli strain BL21 (DE3), and induced at 25°C with 0.4 mmol/L IPTG for 6 hours. The soluble fusion protein was expressed and high purity fusion protein was obtained by Ni<sup>2+</sup>-NTA agarose affinity chromatography purification. The fusion protein was injected into mice 3 times to prepare the antiserum. Western blot analysis showed a specific protein band was detected in total protein sample of banana leaves, but not for the samples of wild-type Nicotiana benthamiana (N.B.) and wild-type Arabidopsis thaliana (A.T.), implying the antiserum was specific to banana E3 ubiquitin-protein ligase.
基金supported by the National Natural Science Foundation of China(22235001,22175020)。
文摘Redox-active organic materials are capturing growing attention as cathode materials for sustainable alkaline metal ion batteries.However,the storage of Na+in most organic materials-based cathodes is plagued by low capacity and unsatisfying rate performance due to their low active site densities and limited exposed active sites.Herein,two polyimide-linked covalent organic frameworks(COFs),namely HATN-PD-COF and HATN-TAB-COF,were fabricated from hydrothermal synthesis with redoxactive triphenylene-2,3,6,7,10,11-hexacarboxylic acid and aromatic amines as starting materials.Powder X-ray diffraction and electron microscopy analysis indicate the high crystalline nature of these COFs with AA stacking configuration and orderly mesoporous tunnel.N_(2) sorption measurement discloses the permanent porosity of these two COFs with a Brunauer-EmmettTeller surface area of 1,065-1,200 m^(2)g^(-1)and a large pore size of 2.0-3.1 nm.Galvanostatic intermittent titration technique and density functional theory calculations reveal the facile Na+ion diffusion along the mesoporous tunnel of these COFs with a small energy barrier of 0.13-0.40 e V.In particular,the as-prepared COFs based-cathodes show ultrafast and stable Na+storage associated with their conjugated electronic structure,highly ordered mesoporous tunnel,robust structure,and redox-active C=N/C=O-rich framework as exemplified by the high reversible capacity of 210 m A h g^(-1)at 200 m A g^(-1),record-high rate performance(195 m A h g^(-1)at a high current density of 10,000 m A g^(-1))among organic electrodes and the capacity retention of nearly 91%at 10,000 m A g^(-1)after 7,000 cycles for HATN-PD-COF.
基金supported by the National Key R&D Program of China(No.2018YFA0703800)the Natural Science Foundation of China(No.T2293770)+1 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA27000000)the National Science Foundation of Shandong Province(No.ZR2020ZD26).
文摘In this paper,we investigate the distributed estimation problem of continuous-time stochastic dynamic systems over sensor networks when both the system order and parameters are unknown.We propose a local information criterion(LIC)based on the L_(0)penalty term.By minimizing LIC at the diffusion time instant and utilizing the continuous-time diffusion least squares algorithm,we obtain a distributed estimation algorithm to simultaneously estimate the unknown order and the parameters of the system.By dealing with the effect of the system noises and the coupling relationship between estimation of system orders and parameters,we establish the almost sure convergence results of the proposed distributed estimation algorithm.Furthermore,we give a simulation example to verify the effectiveness of the distributed algorithm in estimating the system order and parameters.
基金funded by Natural Science Foundation of Heilongjiang Province(No.LH2022B004)Fundamental Research Funds for the Central Universities(No.2572022DJ01)+1 种基金111 Project(No.B20088)Heilongjiang Touyan Innovation Team Program(Tree Genetics and Breeding Innovation Team)。
文摘Chemical sensor arrays can obtain more comprehensive analyte information through high-dimensional data.It is of great significance in the analysis of multi-component complex samples.This review summarizes the development and status of chemical sensor arrays.We focused on the design of chemical sensor arrays based on various sensing materials.In addition,several pattern recognition methods in chemometrics are introduced.And applications of chemical sensor arrays in food monitoring,medical diagnosis,and environmental monitoring are illustrated.Based on the analysis of the limitations of current sensor array technology,the direction of the array is also predicted.This review aims to help the broad readership understand the research state of chemical sensor arrays and their development prospects.
文摘Allogeneic red blood cell(RBC)transfusion is commonly performed in medical practice because of its efficacy and low-risk level.However,pre-transfusion tests are susceptible to monoclonal antibody(mAb)interference.1 Currently,mAb therapies are being developed to treat many diseases,such as cancer.However,certain mAbs,such as anti-CD38mAb and anti-CD47mAb,can bind to RBC membranes;this binding interferes with pre-transfusion tests.2 CD47 has gained considerable attention in recent years because of its potential as a therapeutic target for hematologic malignancies and solid tumors.3 The binding of anti-CD47mAb to RBCs may lead to false-positive results in pan-agglutination tests and cause delays and risks in establishing compatible RBCs for transfusion.
基金supported by the National Natural Science Foundation of China(22235001,22175020,21871024)the Interdisciplinary Research Project for Young Teachers of USTB(FRFIDRY-21-028)。
文摘Electrocatalytic synthesis of urea from CO_(2)and NO_(3)^(-)under ambient conditions provides an appealing alternative to the traditional energy-intensive urea synthetic protocol.Highly active and selective electrocatalysts for efficient urea production are therefore urgently desired owing to the unsatisfactory performance of the thus far reported catalysts.Herein,a phthalocyaninebased(Pc-based)covalent organic framework(COF),namely Co Pc-COF,fabricated from the nucleophilic substitution reaction of hexadecafluorophthalocyaninato cobalt with octahydroxylphthalocyanine cobalt,in situ grew on the surface of multilayered Ti O_(2)nanotubes(NTs),generating the Co Pc-COF@Ti O_(2)NTs composite.Powder X-ray diffraction analysis in combination with electron microscopy measurements discloses the uniform coating of crystalline Co Pc-COF on the multilayered Ti O_(2)NTs in Co Pc-COF@Ti O_(2)NTs.Remarkably,electrochemical tests reveal the superior electrocatalytic activity of Co Pc-COF@Ti O_(2)NTs towards urea production from CO_(2)and NO3-with a record-high yield of 1,205μg h^(-1)cm^(-2)and an outstanding Faraday efficiency of 49%at-0.6 V versus reversible hydrogen electrode due to the significant synergistic catalysis effect.In situ attenuated total reflection infrared spectroscopic investigation and theoretical calculations unveil the efficient C–N coupling reaction between*CO intermediate derived from CO_(2)on Co Pc moieties and*NH2intermediate formed from NO_(3)^(-)on Ti O_(2)NTs during the urea formation process over Co Pc-COF@Ti O_(2)NTs.This work should be helpful towards designing and fabricating high-performance electrocatalysts for sustainable synthesis of urea through efficient synergistic effect of multiactive centers.
基金supported by the National Key Research and Development Program of China(no.2022YFD120030)the National Natural Science Foundation of China(31670233).
文摘Plants contain a large number of cell types and exhibit complex regulatory mechanisms.Studies at the single-cell level have gradually become more common in plant science.Single-cell transcriptomics,spatial transcriptomics,and spatial metabolomics techniques have been combined to analyze plant development.These techniques have been used to study the transcriptomes and metabolomes of plant tissues at the single-cell level,enabling the systematic investigation of gene expression and metabolism in specific tissues and cell types during defined developmental stages.In this review,we present an overview of significant breakthroughs in spatial multi-omics in plants,and we discuss how these approaches may soon play essential roles in plant research.
基金This project was reviewed and approved by the ethical committee of Tangdu Hospital,Air Force Medical University(No.201903-87).
文摘With the development of tyrosine kinase inhibitor(TKI)resistance,finding the novel effective chemotherapeutic agent is of seminal importance for chronic myelogenous leukemia(CML)treatment.This study aims to find the effective anti-leukemic candidates and investigate the possible underlying mechanism.We synthesized the novel coumarin derivatives and evaluated their anti-leukemic activity.Cell viability assay revealed that compound DBH2 exhibited the potent inhibitory activity on the proliferation of CML K562 cells and TKI resistant K562 cells.Morphological observation and flow cytometry confirmed that DBH2 could selectively induce cell apoptosis and cell cycle arrest at G2/M phase of the K562 cells,which was further confirmed on the bone marrow cells from CML transgenic model mice and CD34+bone marrow leukemic cells from CML patients.Treatments of DBH2 in combination with imatinib could prolong the survival rate of SCL-tTA-BCR/ABL transgenic model mice significantly.Quantitative RT-PCR revealed that DBH2 inhibited the expression of STAT3 and STAT5 in K562 cells,and caspase-3 knockout alleviated the DBH2 induced apoptosis.Furthermore,DBH2 could induce the expression of PARP1 and ROCK1 in K562 cells,which may play the important role in caspase-dependent apoptosis.Our results concluded that coumarin derivative DBH2 serves as a promising candidate for the CML treatment,especially in the combination with imatinib for the TKI resistant CML,and STAT/caspase-3 pathway was involved in the molecular mechanism of anti-leukemic activity of DBH2.
基金National Key Research and Development Program of China(2020YFA0211300)National Natural Science Foundation of China(12027807,62225501)+1 种基金PKU-Baidu Fund Project(2020BD023)High-performance Computing Platform of Peking University。
文摘The manipulation of polarization states beyond the optical limit presents advantages in various applications.Considerable progress has been made in the design of meta-waveplates for on-demand polarization transformation,realized by numerical simulations and parameter sweep methodologies.However,due to the limited freedom in these classical strategies,particular challenges arise from the emerging requirement for multiplex optical devices and multidimensional manipulation of light,which urge for a large number of different nanostructures with great polarization control capability.Here,we demonstrate a set of self-designed arbitrary wave plates with a high polarization conversion efficiency.We combine Bayesian optimization and deep neural networks to design perfect halfand quarter-waveplates based on metallic nanostructures,which experimentally demonstrate excellent polarization control functionalities with the conversion ratios of 85%and 90%.More broadly,we develop a comprehensive wave plate database consisting of various metallic nanostructures with high polarization conversion efficiency,accompanying a flexible tuning of phase shifts(0-2π)and group delays(0-10 fs),and construct an achromatic metalens based on this database.Owing to the versatility and excellent performance,our self-designed wave plates can promote the performance of multiplexed broadband metasurfaces and find potential applications in compact optical devices and polarization division multiplexing optical communications.