Chromosome-scale genome assembly of Prunus pusilliflora provides novel insights into genome evolution, disease resistance, and dormancy release in Cerasus L.

Prunus pusilliflora is a wild cherry germplasm resource distributed mainly in Southwest China.Despite its ornamental and economic value,a high-quality assembled P.pusilliflora genome is unavailable,hindering our understanding of its genetic background,population diversity,and evolutionary processes.Here,we de novo assembled a chromosome-scale P.pusilliflora genome using Oxford Nanopore,Illumina,and chromosome conformation capture sequencing.The assembled genome size was 309.62 Mb,with 76 scaffolds anchored to eight pseudochromosomes.We predicted 33035 protein-coding genes,functionally annotated 98.27%of them,and identified repetitive sequences covering 49.08%of the genome.We found that P.pusilliflora is closely related to Prunus serrulata and Prunus yedoensis,having diverged from them∼41.8 million years ago.A comparative genomic analysis revealed that P.pusilliflora has 643 expanded and 1128 contracted gene families.Furthermore,we found that P.pusilliflora is more resistant to Colletotrichum viniferum,Phytophthora capsici,and Pseudomonas syringae pv.tomato(Pst)DC3000 infections than cultivated Prunus avium.P.pusilliflora also has considerably more nucleotide-binding site-type resistance gene analogs than P.avium,which explains its stronger disease resistance.The cytochrome P450 and WRKY families of 263 and 61 proteins were divided into 42 and 8 subfamilies respectively in P.pusilliflora.Furthermore,81 MADS-box genes were identified in P.pusilliflora,accompanying expansions of the SVP and AGL15 subfamilies and loss of the TM3 subfamily.Our assembly of a high-quality P.pusilliflora genome will be valuable for further research on cherries and molecular breeding.

Research on encoding and decoding of non-binary polar codes over GF(2m)

Binary Polar Codes (BPCs) have advantages of high-efficiency and capacity-achieving but suffer from large latency due to the Successive-Cancellation List (SCL) decoding. Non-Binary Polar Codes (NBPCs) have been investigated to obtain the performance gains and reduce latency under the implementation of parallel architectures for multi-bit decoding. However, most of the existing works only focus on the Reed-Solomon matrix-based NBPCs and the probability domain-based non-binary polar decoding, which lack flexible structure and have a large computation amount in the decoding process, while little attention has been paid to general non-binary kernel-based NBPCs and Log-Likelihood Ratio (LLR) based decoding methods. In this paper, we consider a scheme of NBPCs with a general structure over GF(2m). Specifically, we pursue a detailed Monte-Carlo simulation implementation to determine the construction for proposed NBPCs. For non-binary polar decoding, an SCL decoding based on LLRs is proposed for NBPCs, which can be implemented with non-binary kernels of arbitrary size. Moreover, we propose a Perfect Polarization-Based SCL (PPB-SCL) algorithm based on LLRs to reduce decoding complexity by deriving a new update function of path metric for NBPCs and eliminating the path splitting process at perfect polarized (i.e., highly reliable) positions. Simulation results show that the bit error rate of the proposed NBPCs significantly outperforms that of BPCs. In addition, the proposed PPB-SCL decoding obtains about a 40% complexity reduction of SCL decoding for NBPCs.

Cenozoic plants from Tibet:An extraordinary decade of discovery,understanding and implications

Plant fossils play an important role in understanding landscape evolution across the Tibetan Region,as well as plant diversity across wider eastern Asia.Within the last decade or so,paleobotanical investigations within the Tibet Region have led to a paradigm shift in our understanding of how the present plateau formed and how this affected the regional climate and biota.This is because:(1)Numerous new taxa have been reported.Of all the Cenozoic records of new plant fossil species reported from the Tibet(Xizang)Autonomous Region 45 out of 63(70%)were documented after 2010.Among these,many represent the earliest records from Asia,or in some cases worldwide,at the genus or family level.(2)These fossils show that during the Paleogene,the region now occupied by the Tibetan Plateau was a globally significant floristic exchange hub.Based on paleobiogeographic studies,grounded by fossil evidence,there are four models of regional floristic migration and exchange,i.e.,into Tibet,out of Tibet,out of India and into/out of Africa.(3)Plant fossils evidence the asynchronous formation histories for different parts of the Tibetan Plateau.During most of the Paleogene,there was a wide east-west trending valley with a subtropical climate in central Tibet bounded by high(>4 km)mountain systems,but that by the early Oligocene the modern high plateau had begun to form by the rise of the valley floor.Paleoelevation reconstructions using radiometrically-dated plant fossil assemblages in southeastern Tibet show that by the earliest Oligocene southeastern Tibet(including the Hengduan Mountains)had reached its present elevation.(4)The coevolution between vegetation,landform and paleoenvironment is evidenced by fossil records from what is now the central Tibetan Plateau.From the Paleocene to Pliocene,plant diversity transformed from that of tropical,to subtropical forests,through warm to cool temperate woodland and eventually to deciduous shrubland in response to landscape evolution from a seasonally humid lowland valley,to a high and dry plateau.(5)Advanced multidisciplinary technologies and novel ideas applied to paleobotanical material and paleoenvironmental reconstructions,e.g.,fluorescence microscopy and paleoclimatic models,have been essential for interpreting Cenozoic floras on the Tibetan Region.However,despite significant progress investigating Cenozoic floras of the Tibetan Region,fossil records across this large region remain sparse,and for a better understanding of regional ecosystem dynamics and management more paleobotanical discoveries and multidisciplinary studies are required.

Experimental study and simulation on the creep characteristics of machineharvested seed cotton

In view of the unclear understanding of the basic scientific problems such as the rheological mechanism of seed cotton,especially the lack of research on the creep characteristics of seed cotton,the machine-harvested seed cotton in the Xinjiang region was taken as the research object to find out the compression creep characteristics.The universal material testing machine was used to carry out a one-factor creep test,taking moisture content,feed quality,compression times,and trash content as test factors and instantaneous elastic modulus,hysteretic elastic modulus,viscosity coefficient,and delay time as test indicators.The ANOVA and correlation were analyzed by SPSS,and the creep process of the seed cotton was simulated by ADAMS.Results show that moisture content significantly affects the instantaneous elastic modulus,hysteretic elastic modulus,and viscosity coefficient(p<0.01).In addition,each value of which decreases with the increase in moisture content.Feed quality significantly affects the hysteretic elastic modulus and viscosity coefficient(p<0.05).Moreover,the hysteretic elastic modulus and viscosity coefficient increase with the increase in feed quality.The compression times significantly influence the instantaneous elastic modulus,hysteretic elastic modulus,and viscosity coefficient(p<0.01),each value of which increases with the increase of compression times.Furthermore,the trash content significantly influenced the hysteretic elastic modulus and viscosity coefficient(p<0.05).The absolute error between the simulated and experimental values ek is within−0.011-0.030 mm,and the relative errorφk is less than 7%.The experimental results can provide theoretical and data support for the study of rheological characteristics of machine-harvested seed cotton,the design of seed cotton packing devices,and the molding quality of cotton bale(mold).

Pliocene flora and paleoenvironment of Zanda Basin, Tibet, China

This paper describes a plant megafossil assemblage from the Pliocene strata of Xiangzi, Zanda Basin in the western Qinghai-Tibet Plateau. Twenty-one species belonging to 12 genera and 10 families were identified. Studies show that the Pliocene vegetation in Zanda Basin was mostly deciduous shrub composed of Cotoneaster, Spiraea, Caragana, Hippophae,Rhododendron, Potentilla fruticosa, etc. Leaf sizes of these taxa were generally small. Paleoclimate reconstruction using Coexistence Analysis and CLAMP showed that this area had higher temperature and precipitation in the Pliocene than today, and distinct seasonal precipitation variability was established. The reconstructed paleoelevation of Zanda Basin in the Pliocene was similar to modern times. In the context of central Asian aridification, the gradual drought in the area beginning in the late Cenozoic caused vegetation to transition from shrub to desert, and the flora composition also changed.

Macrophage-mediated tumor-targeted delivery of engineered Salmonella typhimurium VNP20009 in anti-PD1 therapy against melanoma

Bacterial antitumor therapy has great application potential given its unique characteristics,including genetic manipulation, tumor targeting specificity and immune system modulation. However,the nonnegligible side effects and limited efficacy of clinical treatment limit their biomedical applications. Engineered bacteria for therapeutic applications ideally need to avoid their accumulation in normal organs and possess potent antitumor activity. Here, we show that macrophage-mediated tumor-targeted delivery of Salmonella typhimurium VNP20009 can effectively reduce the toxicity caused by administrating VNP20009 alone in a melanoma mouse model. This benefits from tumor-induced chemotaxis for macrophages combined with their slow release of loaded strains. Inspired by changes in the tumor microenvironment, including a decrease in intratumoral dysfunctional CD8+T cells and an increase in PDL1 on the tumor cell surface, macrophages were loaded with the engineered strain VNP-PD1nb, which can express and secrete anti-PD1 nanoantibodies after they are released from macrophages. This novel triple-combined immunotherapy significantly inhibited melanoma tumors by reactivating the tumor microenvironment by increasing immune cell infiltration, inhibiting tumor cell proliferation, remodeling TAMs to an M1-like phenotype and prominently activating CD8+T cells. These data suggest that novel combination immunotherapy is expected to be a breakthrough relative to single immunotherapy.

Late Eocene sclerophyllous oak from Markam Basin, Tibet, and its biogeographic implications

Sclerophyllous evergreen broad-leaved forests,mainly made up of sclerophyllous oak,Quercus section Heterobalanus(Øerst.)Menitsky,Fagaceae,represent the most typical forest type in the Hengduan Mountains.Their distribution pattern is closely related to the growth and formation of the Qinghai-Tibetan Plateau(QTP).The oldest fossil record of Quercus sect.Heterobalanus so far discovered is from the middle Miocene of the Gazhacun Formation in Namling County,southern Tibet.However,our recent discovery of leaf fossils from the upper Eocene of Lawula Formation in Markam Basin,southeastern Tibet,illustrates that their origin is nearly 20 Myr older than previously assumed.By integrating the results from geometric morphometrics,geographical range expansion,and ecological niche shifts of this section in what is now the QTP and the Hengduan Mountains,we infer that the leaves of Quercus sect.Heterobalanus were already adapted to cool and dry conditions in some local regions no later than in the late Eocene.Then,with the growth of the QTP and late Cenozoic global cooling,the expansion of cooler and drier habitats benefited the spread and development of this section and their leaves exhibited morphological stasis through stabilizing selection.Based on published fossil records and recent discoveries,we argue that Quercus sect.Heterobalanus appeared in the subtropical evergreen and deciduous broad-leaved mixed forests of the southeastern margin of what is now the QTP no later than in the late Eocene.Some taxa spread westwards along the Gangdese Mountains and later the Himalaya,and others spread eastwards and southeastwards,gradually becoming a dominant group of species in the Hengduan Mountains.This dispersal route is contrary to the previous“northwards hypothesis”of this section,and further supports the hypothesis of an East Asian origin for Quercus section Ilex Loudon.

The Paleogene to Neogene climate evolution and driving factors on the Qinghai-Tibetan Plateau

The growth of the Qinghai-Tibetan Plateau(QTP)during the Cenozoic drove dramatic climate and environmental change in this region.However,there has been limited comprehensive research into evolution of climate during this interval.Here we present a quantitative reconstruction using Bioclimatic Analysis(BA)and Joint Probability Density Functions(JPDFs)based on data available for 48 fossil floras,including macrofossils and palynological fossils collected in the QTP area from the Paleogene to Neogene(66–2.58 Ma).Both methods indicate that there was an overall decline in temperature and precipitation.Paleoclimatic simulations using Hadley Centre Coupled Model version3(HadCM3)show that the most prominent climate change was very likely driven by QTP orographic evolution from the late Eocene,which was accompanied by a shift in temperature from a latitudinal distribution to a topographically controlled pattern.In addition,with the growth of the QTP,temperature and precipitation decreased gradually in the northeastern part of the plateau.Different sources of evidence,including plant fossil records,climate simulations and other proxies,indicate that the topographic evolution of the QTP and other geological events,in conjunction with global cooling,may have been the main factors driving climate change in this region.This research can provide insights into Cenozoic environmental change and ecosystem evolution.

Remarkable mechanochromism and force-induced thermally activated delayed fluorescence enhancement from white-light-emitting organic luminogens with aggregation-induced emission

The development of organic materials with white-light emission and thermally activated delayed fluorescence(TADF)properties in the solid state remain a challenge.Herein,a series of white-light-emitting organic luminogens have been developed and are found to show aggregation-induced delayed fluorescence(AIDF)characteristics.The AIDF emitters present dual-emission consisted of prompt fluorescence and TADF in the crystalline state.Their white-light emissions can be easily tuned by altering the chemical structure and connecting position of the heterocyclic aromatic substituent.Under the stimuli of mechanical force and solvent vapor,the compounds exhibit remarkable and reversible mechanochromism,in which their emission colors are switchable between white and yellow.Upon grinding,they also display linearly tunable luminescence colors,as well as force-induced TADF enhancement,which may be associated with the more compact molecular packing and the restriction of intramolecular motions.The results from time-resolved emission scanning and theoretical calculation suggest that the dual-emission of the AIDF luminogens likely results from the twisted intramolecular charge transfer transitions of the molecules,and the reversible mechanochromism properties probably stem from the interconversion of the quasi-axial and the quasi-equatorial conformations.

新生代青藏高原生长对东亚水循环及生态系统的影响

新生代青藏高原生长和全球温度变化驱动东亚气候和生态系统发生了剧烈变化.本文综述了前人的相关研究成果,基于前期的数值模拟工作,进一步探讨了青藏高原地形地貌演变对东亚水循环及生态系统的影响.目前,关于青藏高原新生代以来地形地貌的演化还存在争议,但近年来不同学科的证据一致认为,青藏高原生长过程具有区域差异性.最新的古气候数值模拟表明,青藏高原北部抬升显著改变了亚洲气候系统,促使东亚降水显著增加,尤其是中国南方冬季降水增加更为明显,地表径流也相应增加,对东亚水系格局产生了重要影响;土壤含水量也随之增加,冬季深层土壤含水量增加尤为显著,导致中国东部植被从干旱、半干旱转变为湿润、半湿润植被类型,造就了现今东亚植被和生物多样性格局.目前,关于青藏高原生长对东亚降水的影响,科学界已有深入认识,但是还有若干关键问题亟待解决,包括:对青藏高原地形地貌演化的进一步限定、对气候转型期高精度的古气候数值模拟,以及进一步解析新生代东亚水循环和生态系统的耦合关系.理解这些关键问题对预测未来全球气候急剧变化背景下的生态系统响应及其演变趋势具有重要的参考意义.

Interface regulation strategy of Al-CNTs composite induced by Al-Si eutectic reaction and its strengthening mechanism

Carbon nanotubes(CNTs)reinforced aluminum matrix composites(AMCs)show broad application prospects in the fields of aerospace and transportation because of their lightweight,high specific strength and specific modulus.A new alloying strategy in this study is proposed to regulate its weak intrinsic interface and uncontrollable interfacial reaction.Our results show that Si element could hinder the dissolution and diffusion of carbon atoms in Al matrix,inhibiting Al-CNTs interface reaction.Grain refinement and dislocation increment induced by the reinforcements promote the contributions to the strength of AMCs.The wettability and interface bonding of Al-CNTs could be effectively improved by Al/Si/CNTs composite interface,the formed discontinuous strong interface is advantageous to coordinate the plastic deformation of AMCs.Si particles can also firmly fix CNTs through pinning effect during deformation,which leads to a better load transfer.Therefore,the tensile strength of Al-5Si-0.5CNTs composite can be enhanced up to 391 MPa while maintaining an acceptable plasticity of 7.5%.It brings the strengthening effect of CNTs into full play in AMCs and achieves the strengthening effect of 1+1>2 under the comprehensive effect of grain refinement strengthening,dislocation strengthening,dispersion strengthening of Si particles and load transfer to CNTs。

滇东南普阳盆地含煤地层孢粉组合特征及其年代

云南地处青藏高原东南缘,生物多样性丰富,季风气候特征明显。新生代剧烈的构造活动形成了众多山间盆地,其间保存了大量精美的植物化石,是探讨新生代以来植被、植物多样性和地球环境演变的理想地区。但是长期以来,由于地层年代学证据的缺乏,这些新生代沉积盆地的地质年代还存在很大争议。本研究通过对滇东南地区富宁县普阳盆地的含煤地层开展深入的孢粉学研究,探讨盆地含煤地层年代及其古气候演化过程。剖面下部煤层孢粉组合以杉粉属(Taxodiaceaepollenites)为主,指示以杉科为主的湿润沼泽森林,冬春季相对湿润;剖面上部孢粉组合指示以常绿栎类为主的亚热带常绿-落叶阔叶混交林,生长山核桃粉属(Caryapollenites)、冬青粉属(Ilexpollenites)、胡桃粉属(Juglanspollenites)、枫香粉属(Liquidambarpollenites)等亚热带常见树种,气候温暖湿润,季节分明。结合新发现的哺乳动物化石证据和周边地区不同地质时代的孢粉组合,普阳盆地含煤地层的沉积时代应为晚始新世;同时,孢粉组合也表明滇东南地区植被现代化面貌至少在晚始新世就已经开始出现。

我国西南植物区系的分异:椿榆属和臭椿属化石的启示

滇西北-西藏和滇东南-桂西是我国西南植物区系中两个面貌和谱系年龄差异最为鲜明的区域,分别以区系年轻、草本植物和区系古老、木本植物为特征。其中一个饶为有趣的问题是这两个地区的区系分异现象是如何演变形成的?古植物学研究能为回答这一问题提供重要证据。本文报道分别发现于滇西北-西藏和滇东南-桂西的椿榆属(Cedrelospermum)和臭椿属(Ailanthus)化石新纪录。结合已有研究,这两个类群在我国西南的化石历史为:椿榆属见于西藏中始新世至晚渐新世(西藏椿榆C.tibetica)及滇东南晚始新世(亚洲椿榆C.asiaticum)地层,而臭椿属化石见于西藏中始新世至晚始新世(大果臭椿A.maximus)及滇东南晚始新世至早渐新世(古臭椿A.confucii)地层。以上古近纪滇西北-西藏和滇东南-桂西植物区系在属级水平上的相似性表明这两个地区之间曾经存在区系交流、类群组成相近。然而,在种级水平上,自晚始新世以来其椿榆属和臭椿属植物又各不相同,暗示着以上两个区系可能在晚始新世或更早已经由于环境分异等因素而向着不同的方向发展。现在椿榆属和臭椿属都已经从西藏消失了,取而代之的是总体上更为年轻的草本植物区系。与此不同,臭椿属在滇东南-桂西延续到了现在,体现了该地区区系的古老性。本研究为滇西北-西藏和滇东南-桂西植物区系在地质历史时期的相似性及其分异的形成提供了化石证据。

儿童近视进展与眼底血流及脉络膜厚度的关系

目的: 探讨儿童近视进展过程中眼底血流及脉络膜厚度的变化。方法: 前瞻性研究。招募2018年7—9月就诊于温州医科大学附属眼视光医院的低中度近视儿童, 随访观察其1年的屈光度数及眼轴长度(AL)变化, 以评估其近视进展。同期采用扫频源光学相干断层扫描血流成像(SS-OCTA)技术进行黄斑区3 mm×3 mm扫描。采用扫频光学相干断层成像(SS-OCT)技术进行黄斑区6 mm×6 mm放射状扫描, 并采集随访观察1年前后受检者右眼黄斑中心凹, 中心凹上、下、鼻、颞侧的脉络膜厚度以及浅层和深层视网膜及脉络膜毛细血管层的血流密度。取受检者右眼数据进行统计分析。采用配对t检验、Pearson相关性及简单线性回归进行统计学分析。结果: 共纳入47例(47眼)受检儿童, 男21例, 女26例, 年龄为(11.1±1.3)岁。1年后随访, 平均等效球镜度(SE)由(-2.59±0.93)D增至(-3.09±0.96)D(t=11.12, P<0.001);AL由(24.75±0.86)mm增长至(24.91±0.84)mm(t=12.25, P<0.001);脉络膜厚度由(238±54)μm减小至(231±55)μm(t=2.67, P=0.011);视网膜浅层、深层及脉络膜毛细血管层血流密度均出现明显下降(t=6.66, P<0.001;t=3.38, P=0.002;t=3.18, P=0.003)。视网膜浅层、深层血流密度变化量与近视度数增加量之间存在线性相关(r=0.35, P=0.02;r=0.37, P=0.01)。结论: 近视儿童在近视进展过程中, 脉络膜厚度变薄, 视网膜及脉络膜血流密度降低, 推测此类眼底变化可能在近视进展过程中起到一定作用。

Microstructure,Phase Transformation,Precipitation Behavior and Mechanical Properties of P/M Cu40Zn-1.0 wt%Ti Brass Alloy via Spark Plasma Sintering and Hot Extrusion

The effect of titanium addition on the microstructure and mechanical properties of brass Cu4OZn has been studied via the powder metallurgy （P/M） route. The water-atomized Cu4OZn-1.0 wt% Ti alloy powder was consolidated at different temperatures in the range of 400-600℃ using spark plasma sintering （SPS） and hot extrusion subsequently. Results show that the super-saturated solid solution titanium element in rapidly cooled brass Cu4OZn powder created high chemical potential for a precipitate reaction, showing significant grain refinement effects on the consolidated Cu4OZn matrix. Consequently, excellent mechanical properties were obtained by precipitation hardening and work hardening after sintering and extrusion, with yield strength of 390 MPa, ultimate tensile strength of 617 MPa, and Vickers micro-hardness of 192 HV, which are 28.7%, 23.4%, and 23.9% higher values than those of extruded Cu4OZn brass, respectively.

Microstructure and mechanical properties of ZrO_2(Y_2O_3)-Al_2O_3 nanocomposites prepared by spark plasma sintering

Zirconia （yttria）-alumina ceramic nanocomposites were fabricated from different powders by spark plasma sintering （SPS）. One powder was a commercially available nanocomposite powder TZP-3Y2OA, consisting of 3 mol% yttria-stabilized zirconia （3-YSZ） reinforced with 20wt% alumina, and the other, used as a comparison, was a conventional mechanically mixed powder 3YSZ-2OA, a blend made of 3 mol% yttria-stabilized zirconia powder ZrO2 （3Y） and 20 wt% ,x-alumina powder. The effect of the sintering temperature on the densification, the sintering behavior, the mechanical properties and the microstructure of the composites was investigated. The results showed that the density increased with increasing sintering temperature, and thus, the mechanical properties were strengthened because of the increased densification. The nanocomposite powder TZP-3Y20A was easily sintered, and good mechanical properties were achieved as compared with the powder from the conventional mechanically mixed method, the maximum flexural strength and fracture toughness of which were 967 MPa and 5.27 MPa m 1/2, respectively.

Vegetation changes across the Eocene-Oligocene transition:Global signals vs.regional development

The Eocene-Oligocene transition(EOT)marked a rapid global cooling event,often considered as the beginning of the modern icehouse world.Influenced by various factors,including tectonic activity and paleogeographic settings,the terrestrial records indicate a diverse response of fauna and vegetation to this global event.We examined nine macrofossil assemblages from seven fossil localities on the southeastern margin of the Tibetan Plateau and from the mid-latitudinal Europe ranging from the latest Bartonian and Priabonian(37.71-33.9 Ma)to the Rupelian(33.9-27.82 Ma).Our aims were to trace and compare the vegetation history of both regions in the late Eocene and early Oligocene.The results show that both regions experienced changes in vegetation composition in response to climate change,characterized by a decrease in the percentages of broad-leaved evergreen elements and distinctive changes in general vegetation types.A general change in the overall vegetation type from subtropical broad-leaved evergreen forests in the late Eocene to temperate broad-leaved mixed deciduous evergreen forests,or mixed mesophytic forests,in the early Oligocene is recognized in both regions.The results indicate a clear change in leaf architecture,leaf margin states,and secondary venation types in the mid-latitudinal Europe,while the results from the southeastern margin of the Tibetan Plateau show a distinct reduction in leaf size.Our data suggest that both global and regional factors played key roles in shaping the vegetation in the two regions.