Heterogeneous population distribution enhances resistance to wheat lodging by optimizing the light environment

Lodging is still the key factor that limits continuous increases in wheat yields today,because the mechanical strength of culms is reduced due to low-light stress in populations under high-yield cultivation.The mechanical properties of the culm are mainly determined by lignin,which is affected by the light environment.However,little is known about whether the light environment can be sufficiently improved by changing the population distribution to inhibit culm lodging.Therefore,in this study,we used the wheat cultivar“Xinong 979”to establish a low-density homogeneous distribution treatment(LD),high-density homogeneous distribution treatment(HD),and high-density heterogeneous distribution treatment(HD-h)to study the regulatory effects and mechanism responsible for differences in the lodging resistance of wheat culms under different population distributions.Compared with LD,HD significantly reduced the light transmittance in the middle and basal layers of the canopy,the net photosynthetic rate in the middle and lower leaves of plants,the accumulation of lignin in the culm,and the breaking resistance of the culm,and thus the lodging index values increased significantly,with lodging rates of 67.5%in 2020–2021 and 59.3%in 2021–2022.Under HD-h,the light transmittance and other indicators in the middle and basal canopy layers were significantly higher than those under HD,and the lodging index decreased to the point that no lodging occurred.Compared with LD,the activities of phenylalanine ammonia-Lyase(PAL),4-coumarate:coenzyme A ligase(4CL),catechol-O-methyltransferase(COMT),and cinnamyl-alcohol dehydrogenase(CAD)in the lignin synthesis pathway were significantly reduced in the culms under HD during the critical period for culm formation,and the relative expression levels of TaPAL,Ta4CL,TaCOMT,and TaCAD were significantly downregulated.However,the activities of lignin synthesis-related enzymes and their gene expression levels were significantly increased under HD-h compared with HD.A partial least squares path modeling analysis found significant positive effects between the canopy light environment,the photosynthetic capacity of the middle and lower leaves of plants,lignin synthesis and accumulation,and lodging resistance in the culms.Thus,under conventional high-density planting,the risk of wheat lodging was significantly higher.Accordingly,the canopy light environment can be optimized by changing the heterogeneity of the population distribution to improve the photosynthetic capacity of the middle and lower leaves of plants,promote lignin accumulation in the culm,and enhance lodging resistance in wheat.These findings provide a basis for understanding the mechanism responsible for the lower mechanical strength of the culm under high-yield wheat cultivation,and a theoretical basis and for developing technical measures to enhance lodging resistance.

Autogenous inside-out versus standard vein and skeletal muscle-combined grafting for facial nerve repair

BACKGROUND： In the repair of nerve defects, collapse of the venous wall, as a result of vein grafting alone, could impede nerve regeneration. Therefore, vein lumens filled with muscle and nerve segments have been used to bridge nerve defects. OBJECTIVE： To compare the effects of autogenous, inside-out, vein-skeletal, muscle-combined grafting versus standard, vein-skeletal, muscle-combined grafting for the repair of facial nerve defects. DESIGN, TIME AND SETTING： A randomized, controlled, neuroanatomical, animal study was performed at the Animal Experimental Center and Laboratories of the Capital Medical University Xuanwu Hospital and the Peking Union Medical College Hospital from September 2007 to October 2008.MATERIALS： A total of 10 healthy, male, New Zealand rabbits, aged 6 months, were randomly assigned to inside-out, vein-skeletal, muscle-combined grafting and standard, vein-skeletal, muscle-combined grafting groups, with 5 rabbits in each group. METHODS： A 20-mm gap in the buccal branch of the right facial nerve was made in each animal, which was respectively repaired with inside-out, vein-skeletal, muscle-combined grafts or standard vein-skeletal muscle-combined grafts.MAIN OUTCOME MEASURES： At 6 months after implantation, evoked maximal compound muscle action potentials were recorded on bilateral facial nerves using electromyogram. Myelinated nerve fibers of the regenerating nerves were quantified using myelin sheath osmic acid staining. RESULTS： There was no significant difference between the groups in terms of ratios of bilateral amplitude and latency of compound muscle action potential （P 〉 0.05）. Moreover, morphology of regenerating nerves and quantity of myelinated nerve fibers were similar between the groups （P 〉 0.05）. CONCLUTION： Compared with standard vein grafting, the inside-out vein grafting did not significantly improve nerve regeneration. Therefore, it is not necessary to utilize inside-out vein grafting for the repair of nerve defects, in particular with the combined use of autogenous vein and skeletal muscle grafts.

Exogenous abscisic acid coordinating leaf senescence and transport of assimilates into wheat grains under drought stress by regulating hormones homeostasis

Drought at the grain filling stage of wheat will cause premature leaf senescence, thus leading to considerable loss of wheat yield. Therefore, this paper aims to establish a cultivation technology for strong drought resistance, delayed senescence, and yield improvement based on the analysis of hormones homeostasis obtained by applying chemical control substances. Experiments were conducted with two genotypes of wheat. Four water irrigation treatments were applied to impose the water deficit, including well-watered control treatment(WW), mild water deficit(MiWD), moderate water deficit(MoWD), and severe water deficit(SWD). Exogenous abscisic acid(ABA) was sprayed on the plants at the anthesis stage of the wheat. As a result, exogenous ABA reduced initial senescence rate(r0), total duration of chlorophyll(Chltotal), rapid senescence phase(Chlloss), and the accumulated temperature at an inflection point(M) but improved the persistence phase(Chlper) of flag leaves under all of the four treatments. However, exogenous ABA produced inconsistent effects on photoassimilate relocation and grain weight under different treatments. It produced positive regulatory effects on grain weight under WW, MiWD, and MoWD treatments. On the one hand, spraying ABA during the persistence phase of flag leaves reduced the ratios of zeatin to gibberellin(Z/GA3), spermine to spermidine(Spm/Spd), and salicylic acid to ABA(SA/ABA),which prolonged active photosynthesis by stimulating high level of proline(Pro) and increased the activities of antioxidant enzymes, such as superoxide dismutase(SOD), peroxidase(POD), catalase(CAT), and ascorbate peroxidase(APX). Therefore, drought tolerance was enhanced, and more photosynthetic assimilates were accumulated. On the other hand, the rapid senescence phase and the transport rate of assimilates into grains were accelerated, resulting in higher grain weight, yield, and water use efficiency(WUE). However, under SWD treatment, exogenous ABA improved the ratio of SA/ABA, leading to low Pro content and low antioxidant enzyme activity of flag leaves in the rapid loss phase. Meanwhile,drought resistance declined and the transport duration of assimilates into grains was shortened, thus making photosynthetic assimilates redundant. Therefore, exogenous ABA can lead to the reduction in grain weight, yield, and WUE of wheat under SWD treatment.

Effects of exogenous ABA application on post-anthesis dry matter redistribution and grain starch accumulation of winter wheat with different staygreen characteristics

The objective of this study was to investigate whether and how exogenous abscisic acid(ABA)is involved in mediating starch accumulation in the grain and redistribution of carbohydrates during grain filling of two wheat cultivars with different staygreen characteristics.At blooming stage,plants of Wennong 6(a staygreen cultivar)and Jimai 20(control)were sprayed with10 mg L-1abscisic acid(ABA)for 3 days.The application of ABA significantly(P<0.05)increased grain filling rate,starch accumulation rate and content,remobilization of dry matters to kernels,and 1000-grain weight of the two cultivars.Exogenous ABA markedly(P<0.05)increased grain yield at maturity,and Wennong 6 and Jiami 20 showed 14.14%and 4.86%higher compared yield than the control.Dry matter accumulation after anthesis of Wennong 6 was also significantly(P<0.05)influenced by exogenous ABA,whereas that of Jimai 20 was unchanged.Application of ABA increased endogenous zeatin riboside(ZR)content 7 days after anthesis(DAA),and spraying ABA significantly increased endogenous indole-3-acetic acid(IAA)and ABA contents from 7 to 21 DAA and decreased gibberellin(GA3)content at 14 DAA,but increased GA3content from 21 to 35 DAA.The results suggested that increased yield of staygreen was due to greater starch assimilation owing to a higher filling rate and longer grain-filling duration.

Interactions between cytokinin and nitrogen contribute to grain mass in wheat cultivars by regulating the flag leaf senescence process

Premature senescence after anthesis reduces crop yields.Delaying leaf senescence could maintain photosynthetic activity for a longer period and lead to a higher photosynthetic rate.Recent studies have provided some insights into the interaction between cytokinin and nitrogen(N)in the regulation of plant development.In the present study,foliar application of exogenous 6-benzylaminopurine(6-BA)and lovastatin,an inhibitor of cytokinin synthesis,was combined with three N rates[0 kg ha^(-1)(low nitrogen,LN),240 kg ha^(-1)(normal nitrogen,NN),and 360 kg ha^(-1)(high nitrogen,HN)]in two wheat cultivars,Wennong 6(with a staygreen phenotype)and Jimai 20(with a non-staygreen phenotype).Flag leaf senescence was assessed using a Gompertz growth curve.Grain mass,dry matter accumulation and distribution,total N of flag leaf,and concentrations of zeatin riboside(ZR)and abscisic acid(ABA)were also used to evaluate the functional characteristics of flag leaves.Grain mass was negatively correlated with initial senescence rate(r_0)and duration of rapid chlorophyll loss(Chl_(loss)),whereas it was positively correlated with maximum senescence rate(r_(max)),average senescence rate(r_(aver)),persistence phase(Chl_(per)),total duration of flag leaf(Chl_(total))and inflection point cumulative temperature(M).Compared to Jimai 20,Wennong 6 had larger r_(aver),Chl_(per),and Chl_(total).The concentration of ZR was highest under the 6-BA×NN treatment,followed by the 6-BA×HN and 6-BA×LN treatments.However,the concentration of ABA showed the opposite trend.It was concluded that the staygreen phenotype Wennong 6 was associated with greater grain mass and altered cytokinin metabolism and could be classified as a functional staygreen type.Foliar application of 6-BA interacting with N at the NN level(240 kg ha^(-1))may be a beneficial strategy for improving grain yield of wheat by regulating endogenous hormones and the flag leaf senescence process.Increasing endogenous cytokinin promoted the transport of dry matter to grain.

Quantum photonics based on metasurfaces

From metamaterials to metasurfaces,optical nano-structure has been widely investigated for novel and high efficiency functionalities.Apart from the intrisinsic properties of composite material,rich capabilities can be derived from the judi-cious design of metasurfaces,which enable more excellent and highly integrated optical devices than traditional bulk op-tical elements.In the meantime,the abundant manipulation abilites of light in the classical domain can be carried over in-to quantum domain.In this review,we highlight recent development of quantum optics based on metasurfaces,ranging from quantum plasmonics,generation,manipulation and appplication of quantum light to quantum vaccum engineering etc.Finally,some promising avenues for quantum optics with the help of optical metasurface are presented.

Variation of high-molecular-weight glutenin subunits and glutenin macropolymer particle distribution in wheat grains produced under different water regimes

The components and contents of high-molecular-weight glutenin subunits(HMW-GS) in wheat grains affect glutenin macropolymer(GMP) size, which is considered an important flour quality trait in wheat. Four wheat cultivars(Shiluan 02-1, Yannong 24, Jinan 17 and Lumai 21) with different end-use qualities were used to investigate the HMW-GS and GMP contents, and the GMP particle distributions in grain produced under irrigated and rainfed conditions. The percent volume of GMP particles and the contents of HMW-GS and GMP were affected by genotype and soil water. Genotype × soil water interaction was significant only for GMP particles <12 μm and >100 μm in the growing season of 2010–2011. Irrigated and rainfed conditions had different influences on the GMP particle distribution in the four cultivars. Compared to irrigated treatment, the rainfed treatment had higher accumulations of HMW-GS and GMP, especially in cultivars Yannong 24, Jinan 17 and Lumai 21. Rainfed conditions also increased the proportion of large size particles of GMP, indicating that different water regimes had an effect on grain quality. According to correlation coefficients(r), the contents of HMW-GS and GMP in grains were negatively correlated with the volume of <12 μm GMP particles, but positively correlated with GMP particles >100 μm.

Review:Chromatic Dispersion Manipulation Based on Optical Metasurfaces

Metasurfaces are densely arrayed two⁃dimensional(2D)artificial planar metamaterials,which can manipulate the polarization,distribution,and amplitude of light by accurately controlling the phase of the scattering light.The flat metasurface has the potential to substantially reduce the thickness and complexity of the structures and allows ease of fabrication and integration into devices.However,the inherent chromatic aberration of the metasurface originating from the resonant dispersion of the antennas and the intrinsic chromatic dispersion limit their quality.How to effectively suppress or manipulate the chromatic aberration of metalenses has attracted worldwide attention in the last few years,leading to a variety of excellent achievements.Furthermore,utilizing the chromatic dispersion of metasurface to realize special functionalities is also of significant importance.In this review,the most promising recent examples of chromatic dispersion manipulation based on optical metasurface materials are highlighted and put into perspective.

A perspective on regression and Bayesian approaches for system identification of pattern formation dynamics

We present two approaches to system identification, i.e. the identification of partial differentialequations (PDEs) from measurement data. The first is a regression-based variational systemidentification procedure that is advantageous in not requiring repeated forward model solves andhas good scalability to large number of differential operators. However it has strict data typerequirements needing the ability to directly represent the operators through the available data.The second is a Bayesian inference framework highly valuable for providing uncertaintyquantification, and flexible for accommodating sparse and noisy data that may also be indirectquantities of interest. However, it also requires repeated forward solutions of the PDE modelswhich is expensive and hinders scalability. We provide illustrations of results on a model problemfor pattern formation dynamics, and discuss merits of the presented methods.

Broadband Sheet Parametric Oscillator for x^((2)) Optical Frequency Comb Generation via Cavity Phase Matching

We demonstrate a broadband optical parametric oscillation,using a sheet cavity,via cavity phase-matching.A21.2 THz broad comb-like spectrum is achieved,with a uniform line spacing of 133.0 GHz,despite a relatively large dispersion of 275.4 fs^(2)/mm around 1064 nm.With 22.6% high slope efficiency,and 14.9 kW peak power handling,this sheet optical parametric oscillator can be further developed for x^((2)) comb.

Passively stable 0.7-octave microcombs in thin-film lithium niobate microresonators

The optical frequency comb based on microresonators(microcombs)is an integrated coherent light source and has the potential to promise a high-precision frequency standard;self-reference and a long-term stable microcomb are the keys to this realization.Here,we demonstrated a 0.7-octave spectrum Kerr comb via dispersion engineering in a thin-film lithium niobate microresonator,and the single-soliton state can be accessed passively with long-term stability over 3 h.With such a robust broadband coherent comb source using thin-film lithium niobate,a fully stabilized microcomb can be expected for massive practical applications.

Enhanced Fatigue Properties of 2219 Al Alloy Joints via Bobbin Tool Friction Stir Welding

In the present study,2219-T87 Al alloy plates,4 mm in thickness,were subjected to bobbin tool friction stir welding(BTFSW)under relatively high welding speeds of 200 and 400 mm/min,with the aim to analyze the effect of welding speeds on fatigue properties of the joints.The results showed that the tension–tension high-cycle fatigue performance of the BT-FSW joints at room temperature was significantly enhanced compared to that of other joints of 2xxx series Al alloys counterparts.Particularly at a high welding speed of 400 mm/min,the fatigue strength of the joint reached 78%of the base material together with a high tensile strength of 311 MPa.It was found that the joint line remnants had no effects on the fatigue properties of the BT-FSW joints due to the elimination of root flaws under the action of the lower shoulder.Most of the samples with the welding speed of 200 mm/min failed at the thermo-mechanical zone(TMAZ)during fatigue tests,attributable to the coarsened grains and precipitates,but all of the samples with high welding speed of 400 mm/min randomly failed at the nugget zone due to the improved hardness value in the TMAZ.

A Resource for Inactivation of MicroRNAs Using Short Tandem Target Mimic Technology in Model and Crop Plants

microRNAs (miRNAs)are endogenous small non-coding RNAs that bind to mRNAs and target them for cleavage and/or translational repression,leading to gene silencing.We previously developed short tandem target mimic (STTM)technology to deactivate endogenous miRNAs in Arabidopsis.Here,we created hundreds of STTMs that target both conserved and species-specific miRNAs in Arabidopsis,tomato,rice,and maize,providing a resource for the functional interrogation of miRNAs.We not only revealed the functions of several miRNAs in plant development,but also demonstrated that tissue-specific inactivation of a few miRNAs in rice leads to an increase in grain size without adversely affecting overall plant growth and development.RNA-seq and small RNAseq analyses of STTM156/157 and STTM165/166 transgenic plants revealed the roles of these miRNAs in plant hormone biosynthesis and activation,secondary metabolism,and ion-channel activity-associated electrophysiology,demonstrating that STTM technology is an effective approach for studying miRNA functions.To facilitate the study and application of STTM transgenic plants and to provide a useful platform for storing and sharing of information about miRNA-regulated gene networks,we have established an online Genome Browser (https://blossom.ffr.mtu.edu/designindex2.php) to display the transcriptomic and miRNAomic changes in STTMinduced miRNA knockdown plants.

Integrating the optical tweezers and spanner onto an individual single-layer metasurface

Optical tweezers(OTs)and optical spanners(OSs)are powerful tools of optical manipulation,which are responsible for particle trapping and rotation,respectively.Conventionally,the OT and OS are built using bulky three-dimensional devices,such as microscope objectives and spatial light modulators.Recently,metasurfaces are proposed for setting up them on a microscale platform,which greatly miniaturizes the systems.However,the realization of both OT and OS with one identical metasurface is posing a challenge.Here,we offer a metasurface-based solution to integrate the OT and OS.Using the prevailing approach based on geometric and dynamic phases,we show that it is possible to construct an output field,which promises a high-numerical-aperture focal spot,accompanied with a coaxial vortex.Optical trapping and rotation are numerically demonstrated by estimating the mechanical effects on a particle probe.Moreover,we demonstrate an on-demand control of the OT-to-OS distance and the topological charge possessed by the OS.By revealing the OT–OS metasurfaces,our results may empower advanced applications in on-chip particle manipulation.

Chromatic dispersion manipulation based on metasurface devices in the mid-infrared region

The chromatic aberration of metasurfaces limits their application. How to cancel or utilize the large chromatic dispersion of metasurfaces becomes an important issue. Here, we design Si-based metasurfaces to realize flexible chromatic dispersion manipulation in mid-infrared region. We demonstrate the broadband achromatic metalens and achromatic gradient metasurface to cancel the chromatic aberration over a continuous bandwidth(8–12 μm). In contrast, the metalens and gradient metasurface with enhanced chromatic dispersion have also been realized, where the focal length and deflection angle with different wavelengths vary more significantly than the conventional devices designed with geometric phase. These demonstrations indicate promising potential applications.

Dynamic cache partitioning based on hot page migration

Static cache partitioning can reduce inter- application cache interference and improve the composite performance of a cache-polluted application and a cache- sensitive application when they run on cores that share the last level cache in the same multi-core processor. In a virtu- alized system, since different applications might run on dif- ferent virtual machines （VMs） in different time, it is inappli- cable to partition the cache statically in advance. This paper proposes a dynamic cache partitioning scheme that makes use of hot page detection and page migration to improve the com- posite performance of co-hosted virtual machines dynami- cally according to prior knowledge of cache-sensitive appli- cations. Experimental results show that the overhead of our page migration scheme is low, while in most cases, the com- posite performance is an improvement over free composition.

A Mechanically Tunable Plasmonic Structure Composed of a Monolayer Array of Metal-Capped Colloidal Spheres on an Elastomeric Substrate

A highly stretchable plasmonic structure composed of a monolayer array of metal-capped colloidal spheres on an elastomeric substrate has been fabricated using simple and inexpensive self-assembly and transfer-printing techniques.This composite structure supports coupled surface plasmons whose wavelengths are sensitive to the arrangement of the metal-capped colloidal spheres.Upon stretching,the lattice of metal-capped colloidal spheres will be deformed,leading to a large wavelength shift of surface plasmon resonances and simultaneously an obvious color change.This stretchable plasmonic structure offers a promising approach to tune surface plasmon resonances and might be exploited in realizing flexible plasmonic devices with tunability of mechanical strain.

Huge Page Friendly Virtualized Memory Management

With the rapid increase of memory consumption by applications running on cloud data centers,we need more efficient memory management in a virtualized environment.Exploiting huge pages becomes more critical for a virtual machine's performance when it runs large working set size programs.Programs with large working set sizes are more sensitive to memory allocation,which requires us to quickly adjust the virtual machine's memory to accommodate memory phase changes.It would be much more efficient if we could adjust virtual machines'memory at the granularity of huge pages.However,existing virtual machine memory reallocation techniques,such as ballooning,do not support huge pages.In addition,in order to drive effective memory reallocation,we need to predict the actual memory demand of a virtual machine.We find that traditional memory demand estimation methods designed for regular pages cannot be simply ported to a system adopting huge pages.How to adjust the memory of virtual machines timely and effectively according to the periodic change of memory demand is another challenge we face.This paper proposes a dynamic huge page based memory balancing system(HPMBS)for efficient memory management in a virtualized environment.We first rebuild the ballooning mechanism in order to dispatch memory in the granularity of huge pages.We then design and implement a huge page working set size estimation mechanism which can accurately estimate a virtual machine's memory demand in huge pages environments.Combining these two mechanisms,we finally use an algorithm based on dynamic programming to achieve dynamic memory balancing.Experiments show that our system saves memory and improves overall system performance with low overhead.

Robust second-order correlation of twin parametric beams generated by amplified spontaneous parametric down-conversion

We report an observation of the second-order correlation between twin beams generated by amplified spontaneous parametric down-conversion operating above threshold with kilowatt-level peak power, from a periodically poled Li Ta O3 crystal via a single-pass scheme. Photocurrent correlation was measured because of the bright photon streams, with raw visibility of 37.9% or 97.3% after electronic filtering. As expected in our theory, this correlation is robust and insensitive to parametric gain and detection loss, enabling important applications in optical communications, precision measurement, and nonlocal imaging.

Humidity sensor and ultraviolet photodetector based on carrier trapping effect and negative photoconductivity in graphene quantum dots

We report on the experimental realization of a graphene quantum dots （GQD）-based htunidity sensor and ultraviolet （UV） photodetector. We demonstrate that the conductance of the GQD increases linearly with increasing relative humidity （RH） of the surrounding environment due to the carrier trapping effect, which forms the basis of a humidity sensor. When the sensor is operated in the dark state, the sensitivity can reach as high as 0.48 nS RH-^1. The GQD are also found to exhibit light intensity dependent negative photoconductivity under the UV irradiation, which can be exploited for UV detection. As a result of these carrier trapping and de-trapping processes, the performance of the photodetector can be significantly improved with the increasing RH, and the photoresponsivity can reach a high value of-418.1 μA W^-1 in the high humid state of RH=90%.