Planting density is a major limiting factor for maize yield,and breeding for density tolerance has become an urgent issue.The leaf structure of the maize ear leaf is the main factor that restricts planting density and...Planting density is a major limiting factor for maize yield,and breeding for density tolerance has become an urgent issue.The leaf structure of the maize ear leaf is the main factor that restricts planting density and yield components.In this study,a natural population of 201 maize inbred lines was used for genome-wide association analysis,which identified nine SNPs on chromosomes 2,5,8,9,and 10 that were significantly associated with ear leaf type structure.Further verification through qRT-PCR confirmed the association of five candidate genes with these SNPs,with the Zm00001d008651 gene showing significant differential expression in the compact and flat maize inbred lines.Enrichment analysis using the Kyoto Encyclopedia of Genes and Genomes(KEGG)and Gene Ontology(GO)databasessuggested that this gene is involved in the glycolysis process.An analysis of the basic properties of this gene revealed that it encodes a stable,basic protein consisting of 593 amino acids with some hydrophobic properties.The promoter region contains stress and hormone(abscisic acid(ABA))related elements.The mutant of this gene increased the first ear leaf angle(eLA)and leaf angle of the first leaf below the first ear(bLA)by 4.96 and 0.97°,respectively,compared with normal inbred lines.Overall,this research sheds light on the regulatory mechanism of ear and leaf structures that influence density tolerance and provides solid foundational work for the development of new varieties.展开更多
Light–matter interactions in two-dimensional(2D)materials have been the focus of research since the discovery of graphene.The light–matter interaction length in 2D materials is,however,much shorter than that in bulk...Light–matter interactions in two-dimensional(2D)materials have been the focus of research since the discovery of graphene.The light–matter interaction length in 2D materials is,however,much shorter than that in bulk materials owing to the atomic nature of 2D materials.Plasmonic nanostructures are usually integrated with 2D materials to enhance the light–matter interactions,offering great opportunities for both fundamental research and technological applications.Nanoparticle-on-mirror(NPo M)structures with extremely confined optical fields are highly desired in this aspect.In addition,2D materials provide a good platform for the study of plasmonic fields with subnanometer resolution and quantum plasmonics down to the characteristic length scale of a single atom.A focused and up-to-date review article is highly desired for a timely summary of the progress in this rapidly growing field and to encourage more research efforts in this direction.In this review,we will first introduce the basic concepts of plasmonic modes in NPo M structures.Interactions between plasmons and quasi-particles in 2D materials,e.g.,excitons and phonons,from weak to strong coupling and potential applications will then be described in detail.Related phenomena in subnanometer metallic gaps separated by 2D materials,such as quantum tunneling,will also be touched.We will finally discuss phenomena and physical processes that have not been understood clearly and provide an outlook for future research.We believe that the hybrid systems of2D materials and NPo M structures will be a promising research field in the future.展开更多
Ecological stoichiometry plays an important role in revealing the mechanisms underlying biogeochemical cycles and ecosystem functions.Abiotic factors have strong effects on N-P stoichiometry,yet the impact of plant co...Ecological stoichiometry plays an important role in revealing the mechanisms underlying biogeochemical cycles and ecosystem functions.Abiotic factors have strong effects on N-P stoichiometry,yet the impact of plant community structure,especially in forests,has not been fully elucidated.We investigated 68 plots in larch forests in northern China to explore how plant community structure and environmental factors affect the N-P stoichiometry of soil and leaves.The results showed significant differences in soil and leaf N-P stoichiometry among the three larch forests,P concentration and N:P ratio of leaves were significantly related to those of soil.Except for larch forest type,N-P stoichiometry was also regulated by elevation,climatic factors,and community structure.With increasing age(from 25 to 236 years),soil N and N:P ratio significantly increased,especially in the topsoil.With increasing mean DBH,leaf N concentration and N:P ratio also increased,indicating a shift in nutrient limitations with stand growth.These findings provide evidence that plant community structure and environmental factors regulate soil and leaf N-P stoichiometry,which is critically important for understanding biogeochemical cycles and forest management undergoing natural succession.展开更多
[Objectives]The paper was to analyze the structure of the culturable bacterial communities in healthy areca palms and those affected by yellow leaf disease(YLD).[Methods]The quantification and isolation of culturable ...[Objectives]The paper was to analyze the structure of the culturable bacterial communities in healthy areca palms and those affected by yellow leaf disease(YLD).[Methods]The quantification and isolation of culturable bacteria present in the leaves,roots,and rhizosphere soil of both healthy areca palms and those exhibiting symptoms of YLD within the same orchard were conducted.Furthermore,a differential analysis of the bacterial community structure was conducted.[Results]The bacterial count was observed to be greater in healthy areca palm samples compared to those exhibiting disease symptoms.Furthermore,the diversity of bacterial species in healthy areca palm samples surpassed that found in diseased samples.Notably,the bacterial genera that exhibited significant differences between healthy and diseased areca palms included Bacillus velezensis,Paenibacillus validus,Alcaligenes faecalis,Burkholderia territorii,Pseudomonas aeruginosa,Bacillus amyloliquefaciens,etc.[Conclusions]This study may offer data support and technical guidance for the effective prevention and control of YLD in areca palm in the future.展开更多
Direct-write atom lithography,one of the potential nanofabrication techniques,is restricted by some difficulties in producing optical masks for the deposition of complex structures.In order to make further progress,a ...Direct-write atom lithography,one of the potential nanofabrication techniques,is restricted by some difficulties in producing optical masks for the deposition of complex structures.In order to make further progress,a structured mirror array is developed to transversely collimate the chromium atomic beam in two dimensions.The best collimation is obtained when the laser red detunes by natural line-width of transition 7S3 → 7P40 of the chromium atom.The collimation ratio is 0.45 vertically（in x axis）,and it is 0.55 horizontally（in y axis）.The theoretical model is also simulated,and success of our structured mirror array is achieved.展开更多
Synthetic two-dimensional（2 D） polymers have totally different topology structures compared with traditional linear or branched polymers. The peculiar 2 D structures bring superior properties. Although, from linear ...Synthetic two-dimensional（2 D） polymers have totally different topology structures compared with traditional linear or branched polymers. The peculiar 2 D structures bring superior properties. Although, from linear to 2 D polymers, the study of these new materials is still in its infancy, they already show potential applications especially in optoelectronics, membranes, energy storage and catalysis, etc. In this review, we summarize the recent progress of the 2 D materials from three respects：（1） Chemistry—different types of polymerization reactions or supramolecular assembly to construct the 2 D networks were described;（2） Preparation methods—surface science, crystal engineering approaches and solution synthesis were introduced;（3） Functionalization and some early applications.展开更多
Two-dimensional function photonic crystals, in which the dielectric constants of medium columns are the functions of space coordinates , are proposed and studied numerically. The band gaps structures of the photonic c...Two-dimensional function photonic crystals, in which the dielectric constants of medium columns are the functions of space coordinates , are proposed and studied numerically. The band gaps structures of the photonic crystals for TE and TM waves are different from the two-dimensional conventional photonic crystals. Some absolute band gaps and semiDirac points are found. When the medium column radius and the function form of the dielectric constant are modulated, the numbers, width, and position of band gaps are changed, and the semi-Dirac point can either occur or disappear. Therefore,the special band gaps structures and semi-Dirac points can be achieved through the modulation on the two-dimensional function photonic crystals. The results will provide a new design method of optical devices based on the two-dimensional function photonic crystals.展开更多
The algebraic solitary wave and its associated eigenvalue problem in a deep stratified fluid with a free surface and a shallow upper layer were studied. And its vertical structure was examined. An exact solution for t...The algebraic solitary wave and its associated eigenvalue problem in a deep stratified fluid with a free surface and a shallow upper layer were studied. And its vertical structure was examined. An exact solution for the derived 2D Benjamin-Ono equation was obtained, and physical explanation was given with the corresponding dispersion relation. As a special case, the vertical structure of the weakly nonlinear internal wave for the Holmboe density distribution was numerically investigated, and the propagating mechanism of the internal wave was studied by using the ray theory.展开更多
The leaf structure, content and the storage location of aloin in the leaves of six species of Aloe L. were studied by means of semi-thin section, high performance liquid chromatography (HPLC) and fluorescent microscop...The leaf structure, content and the storage location of aloin in the leaves of six species of Aloe L. were studied by means of semi-thin section, high performance liquid chromatography (HPLC) and fluorescent microscope. Results showed that all leaves consisted of epidermis, chlorenchyma, aquiferous tissue and vascular bundles. The leaves had the xeromorphic characteristics, including thickened epidermal cell wall, thickened cuticle, sunken stomata and well-developed aquiferous tissue. With the exception of thus, there were remarkable differences in leaf structure among the six species. The chlorenchyma cells were similar to palisade tissues in Aloe arborescens Mill. and A. mutabilis Pillans, but isodiametric in A. vera L., A. vera L. var. chinensis Berg., A. saponaria Hawer and A. greenii Bali. A. arborescens, A. mutabilis, A. very and A. vera var. chinensis included large parenchymatous cells at the vascular bundles, whereas no such cells were observed at the vascular bundles of A. saponaria and A. greenii. In A. arborescens, A. mutabilis and A. vera, the aquiferous tissue sheaths were present and composed of a layer of small parenchymatous cells without chloroplasts around the aquiferous tissue. While there were no aquiferous tissue sheaths in A. vera var. chinensis, A. saponaria and A. greenii. The HPLC revealed that the content of aloin was high in A. arborescens, low in A. vera, and very low in A. saponaria among the six species. The fluorescent microscopy showed that the yellow-green globule only appeared in the large parenchymatous cells of vascular bundles, vascular bundle sheath and aquiferous tissue sheath, but not in the chlorenchyma and aquiferous tissue. Consequently, the large parenchymatous cells of vascular bundles, vascular bundle sheath and aquiferous tissue sheath were the storage location of aloin. They were positively correlated with the content of aloin.展开更多
Plants usually suffer drought stress during their growth process. As the photosynthetic activity center of plants, the leaf is the most sensitive organ under drought stress. In order to support the research on drought...Plants usually suffer drought stress during their growth process. As the photosynthetic activity center of plants, the leaf is the most sensitive organ under drought stress. In order to support the research on drought resistance of higher plants, this study reviewed the adaptation response and damage performance of epidermal structure, palisade tissue and spongy tissue, thickness, veins and stomata of plant leaves under drought stress.展开更多
[ Objective] Correlation of microstructure of leaf sheath epidermis and nutrient composition of palm plants with the damage degree of red palm fiber elephant in four kinds of plants in Nanning were analyzed in order t...[ Objective] Correlation of microstructure of leaf sheath epidermis and nutrient composition of palm plants with the damage degree of red palm fiber elephant in four kinds of plants in Nanning were analyzed in order to control the occurrence and damage of this insect in Nanning. [Method] Taken 4 kinds of Palmae plants in Nanning including Ravenea fivulafis, Washingtonia filifera, Phoenix canafiensis, Roystonea regia （HBK.）O. F. Cook as materials, damage situation of the red palm fiber elephant was investigated, microstructure of leaf sheath epidermis and nutrient composition of palm plants were analyzed and determined. [ Result] The results showed that there was direct correlation between the microstructure of leaf sheath epidermis and nutrient composition with the physical resistance of palm plant against red palm fiber elephant. The extend of damage from red palm fiber elephant had negatively relation with the thickness of corneum and leaf epidermis. The damage degree caused by red palm fiber elephant increased with the content of crude protein, crude ash and nitrogen free extract increasing, also increased with the content of rude fiber decreasing. [Condusion] The damage degree of red palm fiber elephant had a relationship with microstructure of leaf sheath epidermis and nutrient composition of palm plants.展开更多
[Objective] This study aimed to investigate the effects of PP333 and ex- ogenous ABA on the growth and development of Armeniaca vulgaris ＇Luntaibaixing＇ so as to provide a theoretical basis for the growth regulation...[Objective] This study aimed to investigate the effects of PP333 and ex- ogenous ABA on the growth and development of Armeniaca vulgaris ＇Luntaibaixing＇ so as to provide a theoretical basis for the growth regulation of Luntaibaixing in cultivation and management. [Method} Different concentrations of PP333 and ABA were sprayed to Luntaibaixing during the rapid growth period of fresh treetops. The technology of paraffin section was used to measure the thickness of leaf, upper epidermis, lower epidermis, palisade tissue and sponge tissue. The thickness ratio of palisade tissue to sponge tissue, tightness degree of leaf tissue structure （CTR） and loose degree of leaf tissue structure （SR） were calculated and the differences in leaf tissue structure were analyzed. [Result] The thickness of leaf and palisade tissue both increased significantly after treated by PP333. At the treatment concen- tration of 1 000 mg/L, the thickness ratio of palisade tissue to sponge tissue and the value of CTR were highest, while the thickness of sponge tissue and the value of SR were lowest. The thickness of leaf and palisade tissue also increased after treated by ABA, and it increased most greatly at the ABA concentration of 60 mg/L compared with CK. At the treatment concentration of 60 rag/L, the thickness ratio of palisade tissue to sponge tissue and the value of CTR were the highest, while the thickness of sponge tissue and the value of SR were the lowest. [Conclusion] ABA and PP333 treatment increased the leaf thickness, palisade tissue thickness, pal- isade tissue to sponge tissue thickness ratio and CRT value, but reduced the sponge tissue thickness and SR value of Luntaibaixing.展开更多
[Objective] This study aimed to investigate the leaf anatomical structures of P. tunicoides populations under water-limited conditions. [Method] 2-year-old seedlings of herbaceous perennial P. tunicoides that was intr...[Objective] This study aimed to investigate the leaf anatomical structures of P. tunicoides populations under water-limited conditions. [Method] 2-year-old seedlings of herbaceous perennial P. tunicoides that was introduced into the experi- mental field were selected as the research objects. Under the well-watered and wa- ter-limited conditions, we conducted the comparative observation of leaf anatomical structure and stomatal characteristics of two populations by using paraffin slice method and imprinting method. [Result] The result showed that the upper cuticle of P. tunicoides leaves were thickened, the palisade tissue/spongy tissue ratio, vascular bundle diameter and number of xylem vessels in main vein had increased, the stomatal opening became smaller and the stomatal density had increased in winter- spring drought period under water-limited conditions. The plasticity of above traits could be regarded as the important indicators for detecting the responses of P. tunicoides populations to water-limited conditions. Meanwhile, variation amplitudes of these indicators were different among populations. Leaf anatomical structure and stomatal characteristics in Lijiang Axi population under water-limited conditions varied significantly, which might cause the stronger adaptability of this population to drought conditions. [Conclusion] This research provided a reference for the selection of drought-resistant P. tunicoides germplasm and exploration of the adaptive differentia- tion of P. tunicoides populations under natural drought conditions.展开更多
The leaf development of Podocarpus macrophyllus var.maki Endl.started from the leaf primordium formed by the cell division in shoot apical meristem.During the leaf development,three resin canals from the inferior part...The leaf development of Podocarpus macrophyllus var.maki Endl.started from the leaf primordium formed by the cell division in shoot apical meristem.During the leaf development,three resin canals from the inferior part of vascular bundles firstly began to differentiate,then protoxylem in vascular bundles differentiated from adaxial side to abaxial side.Meanwhile,a layer of parenchyma cells from the inferior part of protoderm developed into the sclerenchyma,which played an important role in supporting young leaves.When xylem became mature basically,transfusion tissue,phloem and accessory transfusion tissue began to differentiate,so mesophyll tissue finally differentiated into developmental palisade cells and sponge cells.The thicker cuticle was formed in the lateral side of epidermal cells at the same time of differentiation and development for the inner structure of leaves.Therefore,the developmental palisade cells and the cuticle in the leaf structure of Podocarpus macrophyllus var.maki Endl.is greatly significant for photosynthesis and transpiration when it grows in arid and cold regions.展开更多
The electronic structure,magnetic,and optical properties of two-dimensional(2D)GaSe doped with rare earth elements X(X=Sc,Y,La,Ce,Eu)were calculated using the first-principles plane wave method based on den-sity funct...The electronic structure,magnetic,and optical properties of two-dimensional(2D)GaSe doped with rare earth elements X(X=Sc,Y,La,Ce,Eu)were calculated using the first-principles plane wave method based on den-sity functional theory.The results show that intrinsic 2D GaSe is a p-type nonmagnetic semiconductor with an indi-rect bandgap of 2.6611 eV.The spin-up and spin-down channels of Sc-,Y-,and La-doped 2D GaSe are symmetric,they are non-magnetic semiconductors.The magnetic moments of Ce-and Eu-doped 2D GaSe are 0.908μ_(B)and 7.163μ_(B),which are magnetic semiconductors.Impurity energy levels appear in both spin-up and spin-down chan-nels of Eu-doped 2D GaSe,which enhances the probability of electron transition.Compared with intrinsic 2D GaSe,the static dielectric constant of the doped 2D GaSe increases,and the polarization ability is strengthened.The ab-sorption spectrum of the doped 2D GaSe shifts in the low-energy direction,and the red-shift phenomenon occurs,which extends the absorption spectral range.The optical reflection coefficient of the doped 2D GaSe is improved in the low energy region,and the improvement of Eu-doped 2D GaSe is the most obvious.展开更多
Background Dietary bamboo leaf flavonoids(BLFs)are rarely used in poultry production,and it is unknown whether they influence meat texture profile,perceived color,or microstructure.Results A total of 720 one-day-old A...Background Dietary bamboo leaf flavonoids(BLFs)are rarely used in poultry production,and it is unknown whether they influence meat texture profile,perceived color,or microstructure.Results A total of 720 one-day-old Arbor Acres broilers were supplemented with a basal diet with 20 mg bacitracin/kg,50 mg BLFs/kg,or 250 mg BLFs/kg or without additions.Data showed that the dietary BLFs significantly(P<0.05)changed growth performance and the texture profile.In particular,BLFs increased birds’average daily gain and average daily feed intake,decreased the feed:gain ratio and mortality rate,improved elasticity of breast meat,enhanced the gumminess of breast and leg meat,and decreased the hardness of breast meat.Moreover,a significant(P<0.05)increase in redness(a*)and chroma(c*)of breast meat and c*and water-holding capacity of leg meat was found in BLF-supplemented broilers compared with control broilers.In addition,BLFs supplementation significantly decreased(P<0.05)theβ-sheet ratio and serum malondialdehyde and increased theβ-turn ratio of protein secondary structure,superoxide dismutase,and glutathione peroxidase of breast meat and total antioxidant capacity and catalase of serum.Based on the analysis of untargeted metabolome,BLFs treatment considerably altered 14 metabolites of the breast meat,including flavonoids,amino acids,and organic acids,as well as phenolic and aromatic compounds.Conclusions Dietary BLFs supplementation could play a beneficial role in improving meat quality and sensory color in the poultry industry by changing protein secondary structures and modulating metabolites.展开更多
Leaf pigments are critical indicators of plant photosynthesis,stress,and physiological conditions.Inversion of radiative transfer models(RTMs)is a promising method for robustly retrieving leaf biochem-ical traits from...Leaf pigments are critical indicators of plant photosynthesis,stress,and physiological conditions.Inversion of radiative transfer models(RTMs)is a promising method for robustly retrieving leaf biochem-ical traits from canopy observations,and adding prior information has been effective in alleviating the“ill-posed”problem,a major challenge in model inversion.Canopy structure parameters,such as leaf area index(LAI)and average leaf inclination angle(ALA),can serve as prior information for leaf pigment retrie-val.Using canopy spectra simulated from the PROSAIL model,we estimated the effects of uncertainty in LAI and ALA used as prior information for lookup table-based inversions of leaf chlorophyll(C _(ab))and car-otenoid(C_(ar)).The retrieval accuracies of the two pigments were increased by use of the priors of LAI(RMSE of C_(ab) from 7.67 to 6.32μg cm^(-2),C_(ar) from 2.41 to 2.28μg cm^(-2))and ALA(RMSE of C_(ab) from 7.67 to 5.72μg cm^(-2),C_(ar) from 2.41 to 2.23μg cm^(-2)).However,this improvement deteriorated with an increase of additive and multiplicative uncertainties,and when 40% and 20% noise was added to LAI and ALA respectively,these priors ceased to increase retrieval accuracy.Validation using an experimental winter wheat dataset also showed that compared with C_(ar),the estimation accuracy of C_(ab) increased more or deteriorated less with uncertainty in prior canopy structure.This study demonstrates possible limita-tions of using prior information in RTM inversions for retrieval of leaf biochemistry,when large uncer-tainties are present.展开更多
The first-principles calculations are performed to examine structural,mechanical,and electronic properties at large strain for a monolayer C_(4)N_(4),which has been predicted as an anchoring promising material to atte...The first-principles calculations are performed to examine structural,mechanical,and electronic properties at large strain for a monolayer C_(4)N_(4),which has been predicted as an anchoring promising material to attenuate shuttle effect in Li–S batteries stemming from its large absorption energy and low diffusion energy barrier.Our results show that the ideal strengths of C_(4)N_(4)under tension and pure shear deformation conditions reach 13.9 GPa and 12.5 GPa when the strains are 0.07 and 0.28,respectively.The folded five-membered rings and diverse bonding modes between carbon and nitrogen atoms enhance the ability to resist plastic deformation of C_(4)N_(4).The orderly bond-rearranging behaviors under the weak tensile loading path along the[100]direction cause the impressive semiconductor–metal transition and inverse semiconductor–metal transition.The present results enrich the knowledge of the structure and electronic properties of C_(4)N_(4)under deformations and shed light on exploring other two-dimensional materials under diverse loading conditions.展开更多
One of the most important objectives for breeders is to develop high-yield cultivars.The increase in crop yield has met with bottlenecks after the first green revolution,and more recent efforts have been focusing on a...One of the most important objectives for breeders is to develop high-yield cultivars.The increase in crop yield has met with bottlenecks after the first green revolution,and more recent efforts have been focusing on achieving high photosynthetic efficiency traits in order to enhance the yield.Leaf shape is a significant agronomic trait of upland cotton that affects plant and canopy architecture,yield,and other production attributes.The major leaf shape types,including normal,sub-okra,okra,and super-okra,with varying levels of lobe severity,are controlled by a multiple allelic series of the D-genome locus L-D_(1).To analyze the effects of L-D_(1)alleles on leaf morphology,photosynthetic related traits and yield of cotton,two sets of near isogenic lines(NILs)with different alleles were constructed in Lumianyan 22(LMY22)and Lumianyan 28(LMY28)backgrounds.The analysis of morphological parameters and the results of virus-induced gene silencing(VIGS)showed that the regulation of leaf shape by L-D_(1)alleles was similar to a gene-dosage effect.Compared with the normal leaf,deeper lobes of the sub-okra leaf improved plant canopy structure by decreasing the leaf area index(LAI)and increasing the light transmittance rate(LTR),and the mid-range LAI of sub-okra leaf also guaranteed the accumulation of cotton biomass.Although the chlorophyll content(SPAD)of sub-okra leaf was lower than those of the other two leaf shapes,the net photosynthetic rate(Pn)of sub-okra leaf was higher than those of okra leaf and normal leaf at most stages.Thus,the improvements in canopy structure,as well as photosynthetic and physiological characteristics,contributed to optimizing the light environment,thereby increasing the total biomass and yield in the lines with a sub-okra leaf shape.Our results suggest that the sub-okra leaf may have practical application in cultivating varieties,and could enhance sustainable and profitable cotton production.展开更多
基金supported by the Key Research and Development Project of Heilongjiang Province,China(2022ZX02B01)。
文摘Planting density is a major limiting factor for maize yield,and breeding for density tolerance has become an urgent issue.The leaf structure of the maize ear leaf is the main factor that restricts planting density and yield components.In this study,a natural population of 201 maize inbred lines was used for genome-wide association analysis,which identified nine SNPs on chromosomes 2,5,8,9,and 10 that were significantly associated with ear leaf type structure.Further verification through qRT-PCR confirmed the association of five candidate genes with these SNPs,with the Zm00001d008651 gene showing significant differential expression in the compact and flat maize inbred lines.Enrichment analysis using the Kyoto Encyclopedia of Genes and Genomes(KEGG)and Gene Ontology(GO)databasessuggested that this gene is involved in the glycolysis process.An analysis of the basic properties of this gene revealed that it encodes a stable,basic protein consisting of 593 amino acids with some hydrophobic properties.The promoter region contains stress and hormone(abscisic acid(ABA))related elements.The mutant of this gene increased the first ear leaf angle(eLA)and leaf angle of the first leaf below the first ear(bLA)by 4.96 and 0.97°,respectively,compared with normal inbred lines.Overall,this research sheds light on the regulatory mechanism of ear and leaf structures that influence density tolerance and provides solid foundational work for the development of new varieties.
基金supported by the National Natural Science Foundation of China(62205183)the Research Grants Council of Hong Kong(ANR/RGC,Ref.No.A-CUHK404/21).
文摘Light–matter interactions in two-dimensional(2D)materials have been the focus of research since the discovery of graphene.The light–matter interaction length in 2D materials is,however,much shorter than that in bulk materials owing to the atomic nature of 2D materials.Plasmonic nanostructures are usually integrated with 2D materials to enhance the light–matter interactions,offering great opportunities for both fundamental research and technological applications.Nanoparticle-on-mirror(NPo M)structures with extremely confined optical fields are highly desired in this aspect.In addition,2D materials provide a good platform for the study of plasmonic fields with subnanometer resolution and quantum plasmonics down to the characteristic length scale of a single atom.A focused and up-to-date review article is highly desired for a timely summary of the progress in this rapidly growing field and to encourage more research efforts in this direction.In this review,we will first introduce the basic concepts of plasmonic modes in NPo M structures.Interactions between plasmons and quasi-particles in 2D materials,e.g.,excitons and phonons,from weak to strong coupling and potential applications will then be described in detail.Related phenomena in subnanometer metallic gaps separated by 2D materials,such as quantum tunneling,will also be touched.We will finally discuss phenomena and physical processes that have not been understood clearly and provide an outlook for future research.We believe that the hybrid systems of2D materials and NPo M structures will be a promising research field in the future.
基金supported by the National Natural Science Foundation of China(No.32201426,No.31988102)the Major Program for Basic Research Project of Yunnan Province(No.202101BC070002)the Key Research and Development Program of Yunnan Provin ce(No.202303AC100009).
文摘Ecological stoichiometry plays an important role in revealing the mechanisms underlying biogeochemical cycles and ecosystem functions.Abiotic factors have strong effects on N-P stoichiometry,yet the impact of plant community structure,especially in forests,has not been fully elucidated.We investigated 68 plots in larch forests in northern China to explore how plant community structure and environmental factors affect the N-P stoichiometry of soil and leaves.The results showed significant differences in soil and leaf N-P stoichiometry among the three larch forests,P concentration and N:P ratio of leaves were significantly related to those of soil.Except for larch forest type,N-P stoichiometry was also regulated by elevation,climatic factors,and community structure.With increasing age(from 25 to 236 years),soil N and N:P ratio significantly increased,especially in the topsoil.With increasing mean DBH,leaf N concentration and N:P ratio also increased,indicating a shift in nutrient limitations with stand growth.These findings provide evidence that plant community structure and environmental factors regulate soil and leaf N-P stoichiometry,which is critically important for understanding biogeochemical cycles and forest management undergoing natural succession.
基金Supported by the Specific Research Fund of the Innovation Platform for Academicians of Hainan Province(YSPTZX202151).
文摘[Objectives]The paper was to analyze the structure of the culturable bacterial communities in healthy areca palms and those affected by yellow leaf disease(YLD).[Methods]The quantification and isolation of culturable bacteria present in the leaves,roots,and rhizosphere soil of both healthy areca palms and those exhibiting symptoms of YLD within the same orchard were conducted.Furthermore,a differential analysis of the bacterial community structure was conducted.[Results]The bacterial count was observed to be greater in healthy areca palm samples compared to those exhibiting disease symptoms.Furthermore,the diversity of bacterial species in healthy areca palm samples surpassed that found in diseased samples.Notably,the bacterial genera that exhibited significant differences between healthy and diseased areca palms included Bacillus velezensis,Paenibacillus validus,Alcaligenes faecalis,Burkholderia territorii,Pseudomonas aeruginosa,Bacillus amyloliquefaciens,etc.[Conclusions]This study may offer data support and technical guidance for the effective prevention and control of YLD in areca palm in the future.
基金Project supported by the Shanghai Nanoscience Foundation,China (Grant Nos. 0852nm07000 and 0952nm07000)the National Natural Science Foundation of China (Grant Nos. 10804084 and 91123022)+1 种基金the National Key Technology R & D Program,China (Grant No. 2006BAF06B08)the Specialized Research Fund for the Doctoral Program of Ministry of High Education of China (Grant No. 200802471008)
文摘Direct-write atom lithography,one of the potential nanofabrication techniques,is restricted by some difficulties in producing optical masks for the deposition of complex structures.In order to make further progress,a structured mirror array is developed to transversely collimate the chromium atomic beam in two dimensions.The best collimation is obtained when the laser red detunes by natural line-width of transition 7S3 → 7P40 of the chromium atom.The collimation ratio is 0.45 vertically（in x axis）,and it is 0.55 horizontally（in y axis）.The theoretical model is also simulated,and success of our structured mirror array is achieved.
基金financially supported by the National Natural Science Foundation of China(No.21604046)the National Young Thousand Talents Program,Shandong Provincial Natural Science Foundation,China(No.ZR2016XJ004)
文摘Synthetic two-dimensional（2 D） polymers have totally different topology structures compared with traditional linear or branched polymers. The peculiar 2 D structures bring superior properties. Although, from linear to 2 D polymers, the study of these new materials is still in its infancy, they already show potential applications especially in optoelectronics, membranes, energy storage and catalysis, etc. In this review, we summarize the recent progress of the 2 D materials from three respects：（1） Chemistry—different types of polymerization reactions or supramolecular assembly to construct the 2 D networks were described;（2） Preparation methods—surface science, crystal engineering approaches and solution synthesis were introduced;（3） Functionalization and some early applications.
基金Project supported by the National Natural Science Foundations of China(Grant No.61275047)the Research Project of Chinese Ministry of Education(Grant No.213009A)the Scientific and Technological Development Foundation of Jilin Province,China(Grant No.20130101031JC)
文摘Two-dimensional function photonic crystals, in which the dielectric constants of medium columns are the functions of space coordinates , are proposed and studied numerically. The band gaps structures of the photonic crystals for TE and TM waves are different from the two-dimensional conventional photonic crystals. Some absolute band gaps and semiDirac points are found. When the medium column radius and the function form of the dielectric constant are modulated, the numbers, width, and position of band gaps are changed, and the semi-Dirac point can either occur or disappear. Therefore,the special band gaps structures and semi-Dirac points can be achieved through the modulation on the two-dimensional function photonic crystals. The results will provide a new design method of optical devices based on the two-dimensional function photonic crystals.
文摘The algebraic solitary wave and its associated eigenvalue problem in a deep stratified fluid with a free surface and a shallow upper layer were studied. And its vertical structure was examined. An exact solution for the derived 2D Benjamin-Ono equation was obtained, and physical explanation was given with the corresponding dispersion relation. As a special case, the vertical structure of the weakly nonlinear internal wave for the Holmboe density distribution was numerically investigated, and the propagating mechanism of the internal wave was studied by using the ray theory.
文摘The leaf structure, content and the storage location of aloin in the leaves of six species of Aloe L. were studied by means of semi-thin section, high performance liquid chromatography (HPLC) and fluorescent microscope. Results showed that all leaves consisted of epidermis, chlorenchyma, aquiferous tissue and vascular bundles. The leaves had the xeromorphic characteristics, including thickened epidermal cell wall, thickened cuticle, sunken stomata and well-developed aquiferous tissue. With the exception of thus, there were remarkable differences in leaf structure among the six species. The chlorenchyma cells were similar to palisade tissues in Aloe arborescens Mill. and A. mutabilis Pillans, but isodiametric in A. vera L., A. vera L. var. chinensis Berg., A. saponaria Hawer and A. greenii Bali. A. arborescens, A. mutabilis, A. very and A. vera var. chinensis included large parenchymatous cells at the vascular bundles, whereas no such cells were observed at the vascular bundles of A. saponaria and A. greenii. In A. arborescens, A. mutabilis and A. vera, the aquiferous tissue sheaths were present and composed of a layer of small parenchymatous cells without chloroplasts around the aquiferous tissue. While there were no aquiferous tissue sheaths in A. vera var. chinensis, A. saponaria and A. greenii. The HPLC revealed that the content of aloin was high in A. arborescens, low in A. vera, and very low in A. saponaria among the six species. The fluorescent microscopy showed that the yellow-green globule only appeared in the large parenchymatous cells of vascular bundles, vascular bundle sheath and aquiferous tissue sheath, but not in the chlorenchyma and aquiferous tissue. Consequently, the large parenchymatous cells of vascular bundles, vascular bundle sheath and aquiferous tissue sheath were the storage location of aloin. They were positively correlated with the content of aloin.
基金Supported by the Scientific Research Innovation Fund for the Youth of Hunan Academy of Forestry(2013LQJ13)~~
文摘Plants usually suffer drought stress during their growth process. As the photosynthetic activity center of plants, the leaf is the most sensitive organ under drought stress. In order to support the research on drought resistance of higher plants, this study reviewed the adaptation response and damage performance of epidermal structure, palisade tissue and spongy tissue, thickness, veins and stomata of plant leaves under drought stress.
基金Supported by Guangxi Agricultural College Science Topics(B070206)~~
文摘[ Objective] Correlation of microstructure of leaf sheath epidermis and nutrient composition of palm plants with the damage degree of red palm fiber elephant in four kinds of plants in Nanning were analyzed in order to control the occurrence and damage of this insect in Nanning. [Method] Taken 4 kinds of Palmae plants in Nanning including Ravenea fivulafis, Washingtonia filifera, Phoenix canafiensis, Roystonea regia （HBK.）O. F. Cook as materials, damage situation of the red palm fiber elephant was investigated, microstructure of leaf sheath epidermis and nutrient composition of palm plants were analyzed and determined. [ Result] The results showed that there was direct correlation between the microstructure of leaf sheath epidermis and nutrient composition with the physical resistance of palm plant against red palm fiber elephant. The extend of damage from red palm fiber elephant had negatively relation with the thickness of corneum and leaf epidermis. The damage degree caused by red palm fiber elephant increased with the content of crude protein, crude ash and nitrogen free extract increasing, also increased with the content of rude fiber decreasing. [Condusion] The damage degree of red palm fiber elephant had a relationship with microstructure of leaf sheath epidermis and nutrient composition of palm plants.
文摘[Objective] This study aimed to investigate the effects of PP333 and ex- ogenous ABA on the growth and development of Armeniaca vulgaris ＇Luntaibaixing＇ so as to provide a theoretical basis for the growth regulation of Luntaibaixing in cultivation and management. [Method} Different concentrations of PP333 and ABA were sprayed to Luntaibaixing during the rapid growth period of fresh treetops. The technology of paraffin section was used to measure the thickness of leaf, upper epidermis, lower epidermis, palisade tissue and sponge tissue. The thickness ratio of palisade tissue to sponge tissue, tightness degree of leaf tissue structure （CTR） and loose degree of leaf tissue structure （SR） were calculated and the differences in leaf tissue structure were analyzed. [Result] The thickness of leaf and palisade tissue both increased significantly after treated by PP333. At the treatment concen- tration of 1 000 mg/L, the thickness ratio of palisade tissue to sponge tissue and the value of CTR were highest, while the thickness of sponge tissue and the value of SR were lowest. The thickness of leaf and palisade tissue also increased after treated by ABA, and it increased most greatly at the ABA concentration of 60 mg/L compared with CK. At the treatment concentration of 60 rag/L, the thickness ratio of palisade tissue to sponge tissue and the value of CTR were the highest, while the thickness of sponge tissue and the value of SR were the lowest. [Conclusion] ABA and PP333 treatment increased the leaf thickness, palisade tissue thickness, pal- isade tissue to sponge tissue thickness ratio and CRT value, but reduced the sponge tissue thickness and SR value of Luntaibaixing.
基金Supported by National Natural Science Foundation of China(30370156)Yunnan Provincial Key Discipline of Ornamental Plants and Horticulture of Southwest Forestry University,Key Laboratories and School Laboratories Sharing Platform of Provincial Colleges~~
文摘[Objective] This study aimed to investigate the leaf anatomical structures of P. tunicoides populations under water-limited conditions. [Method] 2-year-old seedlings of herbaceous perennial P. tunicoides that was introduced into the experi- mental field were selected as the research objects. Under the well-watered and wa- ter-limited conditions, we conducted the comparative observation of leaf anatomical structure and stomatal characteristics of two populations by using paraffin slice method and imprinting method. [Result] The result showed that the upper cuticle of P. tunicoides leaves were thickened, the palisade tissue/spongy tissue ratio, vascular bundle diameter and number of xylem vessels in main vein had increased, the stomatal opening became smaller and the stomatal density had increased in winter- spring drought period under water-limited conditions. The plasticity of above traits could be regarded as the important indicators for detecting the responses of P. tunicoides populations to water-limited conditions. Meanwhile, variation amplitudes of these indicators were different among populations. Leaf anatomical structure and stomatal characteristics in Lijiang Axi population under water-limited conditions varied significantly, which might cause the stronger adaptability of this population to drought conditions. [Conclusion] This research provided a reference for the selection of drought-resistant P. tunicoides germplasm and exploration of the adaptive differentia- tion of P. tunicoides populations under natural drought conditions.
基金Supported by Natural Basic Research Program of Universities in Jiangsu(06KJD180201)~~
文摘The leaf development of Podocarpus macrophyllus var.maki Endl.started from the leaf primordium formed by the cell division in shoot apical meristem.During the leaf development,three resin canals from the inferior part of vascular bundles firstly began to differentiate,then protoxylem in vascular bundles differentiated from adaxial side to abaxial side.Meanwhile,a layer of parenchyma cells from the inferior part of protoderm developed into the sclerenchyma,which played an important role in supporting young leaves.When xylem became mature basically,transfusion tissue,phloem and accessory transfusion tissue began to differentiate,so mesophyll tissue finally differentiated into developmental palisade cells and sponge cells.The thicker cuticle was formed in the lateral side of epidermal cells at the same time of differentiation and development for the inner structure of leaves.Therefore,the developmental palisade cells and the cuticle in the leaf structure of Podocarpus macrophyllus var.maki Endl.is greatly significant for photosynthesis and transpiration when it grows in arid and cold regions.
文摘The electronic structure,magnetic,and optical properties of two-dimensional(2D)GaSe doped with rare earth elements X(X=Sc,Y,La,Ce,Eu)were calculated using the first-principles plane wave method based on den-sity functional theory.The results show that intrinsic 2D GaSe is a p-type nonmagnetic semiconductor with an indi-rect bandgap of 2.6611 eV.The spin-up and spin-down channels of Sc-,Y-,and La-doped 2D GaSe are symmetric,they are non-magnetic semiconductors.The magnetic moments of Ce-and Eu-doped 2D GaSe are 0.908μ_(B)and 7.163μ_(B),which are magnetic semiconductors.Impurity energy levels appear in both spin-up and spin-down chan-nels of Eu-doped 2D GaSe,which enhances the probability of electron transition.Compared with intrinsic 2D GaSe,the static dielectric constant of the doped 2D GaSe increases,and the polarization ability is strengthened.The ab-sorption spectrum of the doped 2D GaSe shifts in the low-energy direction,and the red-shift phenomenon occurs,which extends the absorption spectral range.The optical reflection coefficient of the doped 2D GaSe is improved in the low energy region,and the improvement of Eu-doped 2D GaSe is the most obvious.
基金supported by the National Natural Science Foundation of China(No.32002195)Zhejiang Provincial Leading Innovation and Entrepreneurship Team Project(No.2020R01015)+1 种基金“Leading Geese”Research and Development Plan of Zhejiang Province(No.2022C02059)Key R&D Projects of Zhejiang Province(No.2021C02013)。
文摘Background Dietary bamboo leaf flavonoids(BLFs)are rarely used in poultry production,and it is unknown whether they influence meat texture profile,perceived color,or microstructure.Results A total of 720 one-day-old Arbor Acres broilers were supplemented with a basal diet with 20 mg bacitracin/kg,50 mg BLFs/kg,or 250 mg BLFs/kg or without additions.Data showed that the dietary BLFs significantly(P<0.05)changed growth performance and the texture profile.In particular,BLFs increased birds’average daily gain and average daily feed intake,decreased the feed:gain ratio and mortality rate,improved elasticity of breast meat,enhanced the gumminess of breast and leg meat,and decreased the hardness of breast meat.Moreover,a significant(P<0.05)increase in redness(a*)and chroma(c*)of breast meat and c*and water-holding capacity of leg meat was found in BLF-supplemented broilers compared with control broilers.In addition,BLFs supplementation significantly decreased(P<0.05)theβ-sheet ratio and serum malondialdehyde and increased theβ-turn ratio of protein secondary structure,superoxide dismutase,and glutathione peroxidase of breast meat and total antioxidant capacity and catalase of serum.Based on the analysis of untargeted metabolome,BLFs treatment considerably altered 14 metabolites of the breast meat,including flavonoids,amino acids,and organic acids,as well as phenolic and aromatic compounds.Conclusions Dietary BLFs supplementation could play a beneficial role in improving meat quality and sensory color in the poultry industry by changing protein secondary structures and modulating metabolites.
基金supported by the National Natural Science Foundation of China (41975044)the Open Research Fund of the State Laboratory of Information Engineering in Surveying,Mapping,Remote Sensing,Wuhan University (20R02)+2 种基金the Fundamental Research Funds for the Central Universities,China University of Geosciences (Wuhan)(111-G1323520290)funded by SNSA (Dnr 96/16)the EU-Aid funded CASSECS Project。
文摘Leaf pigments are critical indicators of plant photosynthesis,stress,and physiological conditions.Inversion of radiative transfer models(RTMs)is a promising method for robustly retrieving leaf biochem-ical traits from canopy observations,and adding prior information has been effective in alleviating the“ill-posed”problem,a major challenge in model inversion.Canopy structure parameters,such as leaf area index(LAI)and average leaf inclination angle(ALA),can serve as prior information for leaf pigment retrie-val.Using canopy spectra simulated from the PROSAIL model,we estimated the effects of uncertainty in LAI and ALA used as prior information for lookup table-based inversions of leaf chlorophyll(C _(ab))and car-otenoid(C_(ar)).The retrieval accuracies of the two pigments were increased by use of the priors of LAI(RMSE of C_(ab) from 7.67 to 6.32μg cm^(-2),C_(ar) from 2.41 to 2.28μg cm^(-2))and ALA(RMSE of C_(ab) from 7.67 to 5.72μg cm^(-2),C_(ar) from 2.41 to 2.23μg cm^(-2)).However,this improvement deteriorated with an increase of additive and multiplicative uncertainties,and when 40% and 20% noise was added to LAI and ALA respectively,these priors ceased to increase retrieval accuracy.Validation using an experimental winter wheat dataset also showed that compared with C_(ar),the estimation accuracy of C_(ab) increased more or deteriorated less with uncertainty in prior canopy structure.This study demonstrates possible limita-tions of using prior information in RTM inversions for retrieval of leaf biochemistry,when large uncer-tainties are present.
基金Project support by the National Natural Science Foundation of China(Grant Nos.11704044 and 12074140)。
文摘The first-principles calculations are performed to examine structural,mechanical,and electronic properties at large strain for a monolayer C_(4)N_(4),which has been predicted as an anchoring promising material to attenuate shuttle effect in Li–S batteries stemming from its large absorption energy and low diffusion energy barrier.Our results show that the ideal strengths of C_(4)N_(4)under tension and pure shear deformation conditions reach 13.9 GPa and 12.5 GPa when the strains are 0.07 and 0.28,respectively.The folded five-membered rings and diverse bonding modes between carbon and nitrogen atoms enhance the ability to resist plastic deformation of C_(4)N_(4).The orderly bond-rearranging behaviors under the weak tensile loading path along the[100]direction cause the impressive semiconductor–metal transition and inverse semiconductor–metal transition.The present results enrich the knowledge of the structure and electronic properties of C_(4)N_(4)under deformations and shed light on exploring other two-dimensional materials under diverse loading conditions.
基金supported by the State Key Laboratory of Cotton Biology Open Fund,China(CB2021A18)the Youth Scientific Research Foundation of Shandong Academy of Agricultural Sciences,China(2016YQN09)+1 种基金the Improved Variety Project of Shandong Province,China(2020LZGC002)the China Agriculture Research System of MOF and MARA(CARS-15-05).
文摘One of the most important objectives for breeders is to develop high-yield cultivars.The increase in crop yield has met with bottlenecks after the first green revolution,and more recent efforts have been focusing on achieving high photosynthetic efficiency traits in order to enhance the yield.Leaf shape is a significant agronomic trait of upland cotton that affects plant and canopy architecture,yield,and other production attributes.The major leaf shape types,including normal,sub-okra,okra,and super-okra,with varying levels of lobe severity,are controlled by a multiple allelic series of the D-genome locus L-D_(1).To analyze the effects of L-D_(1)alleles on leaf morphology,photosynthetic related traits and yield of cotton,two sets of near isogenic lines(NILs)with different alleles were constructed in Lumianyan 22(LMY22)and Lumianyan 28(LMY28)backgrounds.The analysis of morphological parameters and the results of virus-induced gene silencing(VIGS)showed that the regulation of leaf shape by L-D_(1)alleles was similar to a gene-dosage effect.Compared with the normal leaf,deeper lobes of the sub-okra leaf improved plant canopy structure by decreasing the leaf area index(LAI)and increasing the light transmittance rate(LTR),and the mid-range LAI of sub-okra leaf also guaranteed the accumulation of cotton biomass.Although the chlorophyll content(SPAD)of sub-okra leaf was lower than those of the other two leaf shapes,the net photosynthetic rate(Pn)of sub-okra leaf was higher than those of okra leaf and normal leaf at most stages.Thus,the improvements in canopy structure,as well as photosynthetic and physiological characteristics,contributed to optimizing the light environment,thereby increasing the total biomass and yield in the lines with a sub-okra leaf shape.Our results suggest that the sub-okra leaf may have practical application in cultivating varieties,and could enhance sustainable and profitable cotton production.
