激光焊接及焊后热处理K439B合金的显微组织与力学性能

对应用于发动机涡轮上的新型镍基合金K439B进行激光焊接实验,研究焊后热处理对接头显微组织和力学性能的影响。半定量分析结果表明,热处理后接头各区域γ′相均发生长大,一次γ′相和二次γ′相半径分别约为25和150 nm。力学性能测试结果表明,焊后热处理可使焊缝区硬度提高约HV 100,由γ′相提供的临界恢复剪应力从4.8 MPa提高到92 MPa;另一方面,热处理后接头的抗拉强度和屈服强度与母材的相当,大量碳化物的存在导致接头在拉伸过程中优先断裂于母材处。

新媒体在文旅品牌营销中的应用研究

随着互联网和移动设备的普及,新媒体已成为吸引用户注意力、提升品牌知名度和推动销售增长的强有力工具,在文旅品牌营销中扮演着重要角色。文章以实际项目为研究基础,充分探讨了新媒体在文旅品牌营销中的优势与不足,以期形成一套可复制与推广的营销经验与模式。研究目的是探讨新媒体在文旅品牌营销中的应用,重点关注其UGC式社交化、个性化定制和超时空传播性的特点,文旅品牌营销模式和应用方式。本研究采用文献综述和案例分析法,通过深入研究分析相关文献和“抖出正能量”真实案例,得出新媒体在文旅品牌营销中的应用模式和特点,及对品牌传播和营销效果的影响。研究结果表明,新媒体在文旅品牌营销中的应用模式多样,包括打造“文旅+”新媒体矩阵、深耕内容创新表达和积极培育网红等。其中,“文旅+”新媒体矩阵可以最大化挖掘平台流量,深耕内容创新表达能引爆网络,培育网红可提升沉浸式体验。此外,研究还发现新媒体营销存在的局限性,如信息过载和内容同质化等问题。本研究能为文旅行业提供新媒体营销的理论指导和实践建议,促进行业可持续发展。

Recent research progress in the mechanism and suppression of fusion welding-induced liquation cracking of nickel based superalloys

Nickel-based superalloys are extensively used in the crucial hot-section components of industrial gas turbines,aeronautics,and astronautics because of their excellent mechanical properties and corrosion resistance at high temperatures.Fusion welding serves as an effective means for joining and repairing these alloys;however,fusion welding-induced liquation cracking has been a challenging issue.This paper comprehensively reviewed recent liquation cracking,discussing the formation mechanisms,cracking criteria,and remedies.In recent investigations,regulating material composition,changing the preweld heat treatment of the base metal,optimizing the welding process parameters,and applying auxiliary control methods are effective strategies for mitigating cracks.To promote the application of nickel-based superalloys,further research on the combination impact of multiple elements on cracking prevention and specific quantitative criteria for liquation cracking is necessary.

铜氢催化不饱和烃与醛、酮的亲核加成反应

金属有机试剂(如:有机锂试剂、格氏试剂、有机铜试剂及有机铝试剂)对醛、酮的加成反应是有机化学中的重要反应,也是最经典的构建C―C键的方法之一。然而上述金属有机试剂存在官能团兼容性较差、对水和空气敏感及不易存储等缺陷,不可避免地限制了其广泛应用。近年来,利用稳定、易得的不饱和烃为原料替代金属有机试剂参与各种化学转化受到了人们高度关注。本文主要介绍在铜氢催化条件下,通过把不饱和烃现场转化为催化量有机铜中间体替代传统化学计量金属有机试剂的策略,实现其对醛、酮的加成反应,从而避免了传统方法的缺点。对于上述反应的介绍,能够丰富和拓展基础教学过程中亲核加成知识点的内容,开阔学生的视野与思维,有利于学生了解学科前沿领域的发展现状,激发学生的兴趣。

Bioinspired Multifunctional Self-Sensing Actuated Gradient Hydrogel for Soft-Hard Robot Remote Interaction

The development of bioinspired gradient hydrogels with self-sensing actuated capabilities for remote interaction with soft-hard robots remains a challenging endeavor. Here, we propose a novel multifunctional self-sensing actuated gradient hydrogel that combines ultrafast actuation and high sensitivity for remote interaction with robotic hand. The gradient network structure, achieved through a wettability difference method involving the rapid precipitation of MoO_(2) nanosheets, introduces hydrophilic disparities between two sides within hydrogel. This distinctive approach bestows the hydrogel with ultrafast thermo-responsive actuation(21° s^(-1)) and enhanced photothermal efficiency(increase by 3.7 ℃ s^(-1) under 808 nm near-infrared). Moreover, the local cross-linking of sodium alginate with Ca^(2+) endows the hydrogel with programmable deformability and information display capabilities. Additionally, the hydrogel exhibits high sensitivity(gauge factor 3.94 within a wide strain range of 600%), fast response times(140 ms) and good cycling stability. Leveraging these exceptional properties, we incorporate the hydrogel into various soft actuators, including soft gripper, artificial iris, and bioinspired jellyfish, as well as wearable electronics capable of precise human motion and physiological signal detection. Furthermore, through the synergistic combination of remarkable actuation and sensitivity, we realize a self-sensing touch bioinspired tongue. Notably, by employing quantitative analysis of actuation-sensing, we realize remote interaction between soft-hard robot via the Internet of Things. The multifunctional self-sensing actuated gradient hydrogel presented in this study provides a new insight for advanced somatosensory materials, self-feedback intelligent soft robots and human–machine interactions.

北京2022年冬奥会六足冰壶机器人机构设计与运动规划

When a curling rock slides on an ice sheet with an initial rotation,a lateral movement occurs,which is known as the curling phenomenon.The force of friction between the curling rock and the ice sheet changes continually with changes in the environment;thus,the sport of curling requires great skill and experience.The throwing of the curling rock is a great challenge in robot design and control,and existing curling robots usually adopt a combination scheme of a wheel chassis and gripper that differs significantly from human throwing movements.A hexapod curling robot that imitates human kicking,sliding,pushing,and curling rock rotating was designed and manufactured by our group,and completed a perfect show during the Beijing 2022 Winter Olympics Games.Smooth switching between the walking and throwing tasks is realized by the robot’s morphology transformation based on leg configuration switching.The robot’s controlling parameters,which include the kicking velocity v_(k),pushing velocity v_(p),orientation angle θc,and rotation velocityω,are determined by aiming and sliding models according to the estimated equivalent friction coefficientμ_(equ)and ratio e of the front and back frictions.The stable errors between the target and actual stopping points converge to 0.2 and 1.105 m in the simulations and experiments,respectively,and the error shown in the experiments is close to that of a well-trained wheelchair curling athlete.This robot holds promise for helping ice-makers rectify ice sheet friction or assisting in athlete training.

Molecular phylogeny and taxonomy of Phlomoides(Lamiaceae subfamily Lamioideae)in China:Insights from molecular and morphological data

Phlomoides,with 150-170 species,is the second largest and perhaps most taxonomically challenging genus within the subfamily Lamioideae(Lamiaceae).With about 60 species,China is one of three major biodiversity centers of Phlomoides.Although some Phlomoides species from China have been included in previous molecular phylogenetic studies,a robust and broad phylogeny of this lineage has yet to be completed.Moreover,given the myriad new additions to the genus,the existing infrageneric classification needs to be evaluated and revised.Here,we combine molecular and morphological data to investigate relationships within Phlomoides,with a focus on Chinese species.We observed that plastid DNA sequences can resolve relationships within Phlomoides better than nuclear ribosomal internal and external transcribed spacer regions(nrITS and nrETS).Molecular phylogenetic analyses confirm the monophyly of Phlomoides,but most previously defined infrageneric groups are not monophyletic.In addition,morphological analysis demonstrates the significant taxonomic value of eight characters to the genus.Based on our molecular phylogenetic analyses and morphological data,we establish a novel section Notochaete within Phlomoides,and propose three new combinations as well as three new synonyms.This study presents the first molecular phylogenetic analyses of Phlomoides in which taxa representative of the entire genus are included,and highlights the phylogenetic and taxonomic value of several morphological characters from species of Phlomoides from China.Our study suggests that a taxonomic revision and reclassification for the entire genus is necessary in the future.

Smart Gait:A Gait Optimization Framework for Hexapod Robots

The current gait planning for legged robots is mostly based on human presets,which cannot match the flexible characteristics of natural mammals.This paper proposes a gait optimization framework for hexapod robots called Smart Gait.Smart Gait contains three modules:swing leg trajectory optimization,gait period&duty optimization,and gait sequence optimization.The full dynamics of a single leg,and the centroid dynamics of the overall robot are considered in the respective modules.The Smart Gait not only helps the robot to decrease the energy consumption when in locomotion,mostly,it enables the hexapod robot to determine its gait pattern transitions based on its current state,instead of repeating the formalistic clock-set step cycles.Our Smart Gait framework allows the hexapod robot to behave nimbly as a living animal when in 3D movements for the first time.The Smart Gait framework combines offline and online optimizations without any fussy data-driven training procedures,and it can run efficiently on board in real-time after deployment.Various experiments are carried out on the hexapod robot LittleStrong.The results show that the energy consumption is reduced by 15.9%when in locomotion.Adaptive gait patterns can be generated spontaneously both in regular and challenge environments,and when facing external interferences.

Camellia sinensis CsMYB4a participates in regulation of stamen growth by interaction with auxin signaling transduction repressor CsAUX/IAA4

Subgroup 4(Sg4)members of the R2R3-MYB are generally known as negative regulators of the phenylpropanoid pathway in plants.Our previous research showed that a R2R3-MYB Sg4 member from Camellia sinensis(CsMYB4a)inhibits expression of some genes in the phenylpropanoid pathway,but its physiological function in the tea plant remained unknown.Here,CsMYB4a was found to be highly expressed in anther and filaments,and participated in regulating filament growth.Transcriptome analysis and exogenous auxin treatment showed that the target of CsMYB4a might be the auxin signal pathway.Auxin/indole-3-acetic acid 4(AUX/IAA4),a repressor in auxin signal transduction,was detected from a yeast two-hybrid screen using CsMYB4a as bait.Gene silencing assays showed that both CsIAA4 and CsMYB4a regulate filament growth.Tobacco plants overexpressing CsIAA4 were insensitive to exogenous a-NAA,consistent with overexpression of CsMYB4a.Protein-protein interaction experiments revealed that CsMYB4a interacts with N-terminal of CsIAA4 to prevent CsIAA4 degradation.Knock out of the endogenous NtIAA4 gene,a CsIAA4 homolog,in tobacco alleviated filament growth inhibition and a-NAA insensitivity in plants overexpressing CsMYB4a.All results strongly suggest that CsMYB4a works synergistically with CsIAA4 and participates in regulation of the auxin pathway in stamen.

High-visibility ghost imaging with phase-controlled discrete classical light sources

We take phase modulation to create discrete phase-controlled sources and realize the super-bunching effect by a phasecorrelated method. From theoretical and numerical simulations, we find the space translation invariance of the bunching effect is a key point for the ghost imaging realization. Experimentally, we create the orderly phase-correlated discrete sources which can realize high-visibility second-order ghost imaging than the result with chaotic sources. Moreover, some factors affecting the visibility of ghost image are discussed in detail.

Prediction of favorable geological storage areas based on sedimentary characteristics:A case study on the northeastern Ordos Basin,China

The Ordos Basin is a large cratonic basin with stable deposition in Northwest China.Given its mostly stable subsidence background and the urgent need for saline water disposal and carbon dioxide storage in the coal mining and coal chemical industries,the Ordos Basin has been chosen as a pilot demonstration site for carbon dioxide and saline water storage in China.However,few studies have been made to evaluate the sedimentary and sequence stratigraphy characteristics of this region,as well as their influence on carbon dioxide and saline water storage potential.To address this research gap,we conducted a sedimentary study of the Lower Triassic Liujiagou Formation in the northeastern Ordos Basin utilizing the stratigraphy theory,laboratory test analysis,and pilot project demonstration,to evaluate the area's viability for the deep geological storage of gas and liquid waste.We studied the tectonic setting,petrological features,and sedimentary characteristics of the favorable strata and predicted favorable areas based on sequence stratigraphy theory.The lithology predominantly consists of feldspathic graywacke,with a fine grain size and mostly fine-to-medium-grained sandstone.The distribution of thick-grained sandstone and fine-grained sediment was identified by dividing the sequence,and a favorable reservoir-cap assemblage configuration was formed.It's concluded that the Lower Triassic Liujiagou Formation exhibits suitable characteristics for the deep geological storage of carbon dioxide and saline water.This study demonstrates the importance of basic theory in guiding practical applications and provides a reference for the scientific selection of favorable areas for deep basin storage.

Haplotype-resolved and chromosome-scale genomes provide insights into co-adaptation between the Amur tiger and Amur leopard

DEAR EDITOR,Big cats,such as Amur tigers(Panthera tigris altaica)and Amur leopards(P.pardus orientalis),are apex predator and have evolved specialized traits for hunting and carnivory(Moya et al.,2022),thus playing a crucial role in maintaining biodiversity and ecosystem integrity by regulating prey-predator dynamics.However,human-induced pressures,habitat fragmentation,and environmental alterations have restricted these species in small and isolated populations.Currently,all extant big cats are categorized as endangered or threatened according to their conservation status.Amur tigers and Amur leopards share overlapping geographic ranges,habitats,and certain prey species in the forests of Northeast Asia(Jiang et al.,2015).To reduce interspecies conflict,these carnivores exhibit differentiated dietary and temporal niches.Amur tigers predominantly prey on large ungulates,while Amur leopards hunt small to medium-sized animals(Sugimoto et al.,2016).Additionally,they occupy different temporal niches,with tigers being active at night and leopards more active during the day.Despite spatial and temporal niche partitioning,interspecific competition between these two species is inevitable.Tigers,benefiting from their greater size,have a competitive advantage over leopards,which can manifest in occasional leopard predation by tigers and declines in leopard populations with increasing tiger density(Jiang et al.,2015).Tigers also displace leopards from marginal habitats in nature reserves where they coexist.

城市更新背景下老旧小区改造的困境与对策研究

老旧小区改造是城市更新的重要组成部分,是提高居民生活质量、提升城市整体形象的重要抓手。针对当前老旧小区改造存在的现实困境,提出其在城市更新总体框架下的治理路径,结合昆明市呈贡老县城老旧小区改造项目,剖析其在资金筹集机制、构建居民参与途径、制定特色化改造内容、完善小区管理机制及运维体系等方面的具体实施策略,为其他城市制定老旧小区改造方案和策略提供参考与借鉴。

一起220kV断路器拒绝分闸故障的分析与处理

针对一起220 kV弹簧操动机构断路器拒绝分闸故障,分析了断路器拒绝分闸的常见原因,例如脱扣机构卡涩、分闸线圈损坏、操作板故障、二次端子接触不良等。结合现场检查和试验结果,最终确定该故障与断路器脱扣机构润滑不良、分闸线圈存在质量问题有关,并对故障断路器进行了处理。最后提出了相应的整改措施,以减少此类故障发生的概率。

理想流体中多孔球形粒子的声辐射力的研究

主要根据Biot-Stoll多孔介质理论,推导了平面波入射到理想流体中多孔球形粒子的声散射系数以及所受声辐射力表达式,通过数值模拟分析了开孔和闭孔情况下多孔球形粒子在不同体孔隙率、不同面孔隙率以及不同药物材料下所受的声辐射力大小,并利用有限元仿真对理论结果进行了验证.从结果可以看出体孔隙率越大,多孔粒子所受的声辐射力越大,对于不同的药物粒子,由于各类性质不同,所以相对而言所受的声辐射力的波动较大.研究为流体中粒子的声操控提供了理论基础,有助于从药物材料、孔隙率等方面改善和发展用于医学相关领域的药物操控.

Green,Sustainable Architectural Bamboo with High Light Transmission and Excellent Electromagnetic Shielding as a Candidate for Energy-Saving Buildings

Currently,light-transmitting,energy-saving,and electromagnetic shielding materials are essential for reducing indoor energy consumption and improving the electromagnetic environment.Here,we developed a cellulose composite with excellent optical transmittance that retained the natural shape and fiber structure of bamboo.The modified whole bamboo possessed an impressive optical transmittance of approximately 60%at 6.23 mm,illuminance of 1000 luminance(lux),water absorption stability(mass change rate less than 4%),longitudinal tensile strength(46.40 MPa),and surface properties(80.2 HD).These were attributed to not only the retention of the natural circular hollow structure of the bamboo rod on the macro,but also the complete bamboo fiber skeleton template impregnated with UV resin on the micro.Moreover,a multilayered device consisting of translucent whole bamboo,transparent bamboo sheets,and electromagnetic shielding film exhibited remarkable heat insulation and heat preservation performance as well as an electromagnetic shielding performance of 46.3 dB.The impressive optical transmittance,mechanical properties,thermal performance,and electromagnetic shielding abilities combined with the renewable and sustainable nature,as well as the fast and efficient manufacturing process,make this bamboo composite material suitable for effective application in transparent,energy-saving,and electromagnetic shielding buildings.

视网膜中央动脉阻塞伴急性黄斑旁中心中层视网膜病变的黄斑区微血管研究

目的:探讨视网膜中央动脉阻塞(CRAO)伴急性黄斑旁中心中层视网膜病变(PAMM)患眼的黄斑区微血管变化情况。方法:回顾性研究。选取2020-01/2021-12于我院确诊为CRAO-PAMM组患者27例27眼,不伴PAMM的CRAO组患者29例29眼。选取于我院健康体检者33例33眼作为对照组。应用光学相干断层扫描血管成像(OCTA)测量黄斑区3mm×3mm范围内视网膜血流和厚度参数,分析CRAO-PAMM组患者黄斑区视网膜血流密度、视网膜厚度、中心凹无血管区(FAZ)面积和周长、非圆度指数(AI)及拱环周围300μm范围内全层血流密度(FD-300)与病灶区面积、最佳矫正视力(BCVA)的相关性。结果:三组受检者视网膜浅层毛细血管层(SCP)、深层毛细血管层(DCP)的总体、旁中心凹血流密度、视网膜中心凹厚度、FAZ面积、周长、AI、FD-300均有差异(均P<0.05)。在CRAO-PAMM组中,病灶区面积与DCP总体血流密度、旁中心凹血流密度呈负相关(r=-0.569,P=0.002;r=-0.543,P=0.004),与视网膜旁中心凹厚度呈正相关(r=0.606,P=0.001);BCVA(LogMAR)与DCP中心凹和旁中心凹血流密度呈负相关(r=-0.433,P=0.024;r=-0.515,P=0.006),与FAZ面积、周长和病灶区面积呈正相关(r=0.484,P=0.011;r=0.531,P=0.004;r=0.417,P=0.030)。结论:伴发PAMM的CRAO患眼黄斑区血流密度更低、黄斑区水肿程度更重且视力更差,患者BCVA可能受到病灶区面积和FAZ面积共同的影响。

Variability of Raindrop Size Distribution during a Regional Freezing Rain Event in the Jianghan Plain of Central China

The characteristics of the raindrop size distribution(DSD)during regional freezing rain(FR)events that occur throughout the phase change(from liquid to solid)are poorly understood due to limited observations.We investigate the evolution of microphysical parameters and the key formation mechanisms of regional FR using the DSDs from five disdrometer sites in January 2018 in the Jianghan Plain(JHP)of Central China.FR is identified via the size and velocity distribution measured from a disdrometer,the discrete Fréchet distancemethod,surface temperature,human observations,and sounding data.With the persistence of precipitation,the emergence of graupel or snowflakes significantly reduces the proportion of FR.The enhancement of this regional FR event is mainly dominated by the increase in the number concentration of raindrops but weakly affected by the diameters.To improve the accuracy of quantitative precipitation estimation for the FR event,a modified second-degree polynomial relation between the shapeμand slopeΛof gamma DSDs is derived,and a new Z-R(radar reflectivity to rain rate)relationship is developed.The mean values of mass-weighted mean diameters(D_(m))and generalized intercepts(lgN_(w))in FR are close to the stratiform results in the northern region of China.Both the melting of tiny-rimed graupels and large-dry snowflakes are a response to the formation of this regional FR process in the JHP,dominated by the joint influence of the physical mechanism of warm rain,vapor deposition,and aggregation/riming coupled with the effect of weak convective motion in some periods.

Relaxin-encapsulated polymeric metformin nanoparticles remodel tumor immune microenvironment by reducing CAFs for efficient triple-negative breast cancer immunotherapy

Cancer-associated fibroblasts(CAFs)are one of the most abundant stromal cells in the tumor microenvironment which mediate desmoplastic response and are the primary driver for an immunosuppressive microenvironment,leading to the failure of triple-negative breast cancer(TNBC)immunotherapy.Therefore,depleting CAFs may enhance the effect of immunotherapy(such as PD-L1 antibody).Relaxin(RLN)has been demonstrated to significantly improve transforming growth factor-β(TGF-β)induced CAFs activation and tumor immunosuppressive microenvironment.However,the short half-life and systemic vasodilation of RLN limit its in vivo efficacy.Here,plasmid encoding relaxin(pRLN)to locally express RLN was delivered with a new positively charged polymer named polymeric metformin(PolyMet),which could increase gene transfer efficiency significantly and have low toxicity that have been certified by our lab before.In order to improve the stability of pRLN in vivo,this complex was further formed lipid poly-γ-glutamic acid(PGA)/PolyMetpRLN nanoparticle(LPPR).The particle size of LPPR was 205.5±2.9 nm,and the zeta potential was+55.4±1.6 mV.LPPR displayed excellent tumor penetrating efficacy and weaken proliferation of CAFs in 4T1luc/CAFs tumor spheres in vitro.In vivo,it could reverse aberrantly activated CAFs by decreasing the expression of profibrogenic cytokine and remove the physical barrier to reshape the tumor stromal microenvironment,which enabled a 2.2-fold increase in cytotoxic T cell infiltration within the tumor and a decrease in immunosuppressive cells infiltration.Thus,LPPR was observed retarded tumor growth by itself in the 4T1 tumor bearing-mouse,and the reshaped immune microenvironment further led to facilitate antitumor effect when it combined with PD-L1 antibody(aPD-L1).Altogether,this study presented a novel therapeutic approach against tumor stroma using LPPR to achieve a combination regimen with immune checkpoint blockade therapy against the desmoplastic TNBC model.

黄斑中心凹旁血流密度对BRVO患者玻璃体腔内康柏西普注射次数的预测作用评价

目的:研究非缺血型视网膜分支静脉阻塞(BRVO)合并黄斑水肿(ME)患者的光学相干断层扫描血管成像(OCTA)中围绕黄斑无血管区(FAZ)区域300μm宽度内的血流密度(FD-300),探讨并评估该参数对眼内注药次数的预测作用。方法:回顾性研究,选取2021-01/2022-03于南京医科大学眼科医院诊断为非缺血型BRVO合并ME并接受了玻璃体腔内康柏西普注射(IVC)的患者50例50眼,采用3+PRN治疗方案。将眼内注药治疗≤5次的患眼列为B组(25例25眼);眼内注药治疗>5次的患眼列为C组(25例25眼),另外随机选取对侧眼作为对照组A组(25例25眼)。采用OCTA对所有患眼行黄斑区3mm×3mm范围模式扫描采集视网膜血流图像,获取黄斑中心凹下视网膜厚度(CMT)及FD-300值。比较各组基线时及第3针注射后1、3、6、12mo时的CMT、BCVA(LogMAR)、FD-300。结果:B组和C组受试者治疗后1、3、6、12mo时的患眼BCVA(LogMAR)较基线均明显改善(均P<0.05);CMT较基线均明显降低(均P<0.05);FD-300较基线降低(均P<0.05)。Pearson相关分析显示,BCVA(LogMAR)变化量与基线FD-300、CMT呈显著正相关(B组:r=0.77、0.70,均P<0.01;C组:r=0.89、0.78,均P<0.01)。眼内注药次数与基线FD-300呈显著负相关(B组:r=-0.63,P<0.01;C组:r=-0.71,P<0.01)。Logistic回归分析显示,治疗前FD-300参数是影响眼内注药次数的因素。结论:玻璃体腔注射康柏西普治疗非缺血型BRVO合并ME患者能有效减轻患眼黄斑水肿,提高患者视力,降低FD-300。基线BCVA越差以及基线FD-300越低的患眼可能需要更多的注射次数。使用OCTA观察黄斑区FD-300,可在治疗前更好地预测非缺血型BRVO合并ME患者的最终视力恢复。