Evidence of the predominance of passive symplastic phloem loading and sugar transport with leaf ageing in Camellia oleifera

Phloem loading and transport of sugar from leaves to sink tissues such as fruits are crucial for yield formation.Camellia oleifera is an evergreen horticultural crop with high value;however,its low production limits the development of the C.oleifera industry.In this study,using a combination of ultrastructural observation,fluorescence loss in photobleaching(FLIP)and inhibitor treatment,we revealed that C.oleifera leaves mainly adopt a symplastic loading route from mesophyll cells to the surrounding vascular bundle cells in minor veins.HPLC assays showed that sucrose is the main sugar transported and only a small amount of raffinose or stachyose was detected in petioles,supporting a passive symplastic loading route in C.oleifera leaves.Compared to leaves grown this year(LT),the carbohydrate synthesis capacity in leaves grown last year(LL)was decreased while LL retained more soluble sugar,suggesting a decrease in transport capacity with leaf ageing.TEM and tissue staining showed that a reduction in plasmodesmata density leads to a decline in the degree of cellular coupling and is responsible for the weakening transport capacity in older leaves.RNA-seq revealed several differentially expressed genes(DEGs)including CoPDCB1-1,CoSUT1 and CoSWEET12,which are likely involved in the regulation of phloem loading and sugar transport.An expression correlation network is constructed between PD-callose binding protein genes,sugar transporter genes and senescence-associated genes.Collectively,this study provides the evidence of the passive symplastic phloem loading pathway in C.oleifera leaves and constructs the correlation between sugar transport and leaf ageing.

Oxygen vacancies with localized electrons direct a functionalized separator toward dendrite-free and high loading LiFePO_(4)for lithium metal batteries

The pursuit of high energy density has promoted the development of high-performance lithium metal batteries(LMBs).However,the underestimated but non-negligible dendrites of Li anode have been observed to shorten battery lifespan.Herein,a composite separator(TiO_(2-x)@PP),in which TiO_(2)with electron-localized oxygen vacancies(TiO_(2-x))is coated on a commercial PP separator,is fabricated to homogenize lithium ion transport and stabilize the lithium anode interface.With the utilization of TiO_(2-x)@PP separators,the symmetric lithium metal battery displays enhanced cycle stability over 800 h under a high current density of 8 m A cm^(-2).Moreover,the LMBs assembled with high-loading LiFePO_(4)(9.24 mg cm^(-2))deliver a stable cycling performance over 900 cycles at a rate of 0.5 C.Comprehensive theoretical studies based on density functional theory(DFT)further unveil the mechanism.The favorable TiO_(2-x)is beneficial for facilitating fast Li+migration and impeding anions transfer.In addressing the Li dendrite issues,the use of TiO_(2-x)@PP separator potentially provides a facile and attractive strategy for designing well-performing LMBs,which are expected to meet the application requirements of rechargeable batteries.

An asymmetric bilayer polymer-ceramic solid electrolyte for highperformance sodium metal batteries

Manufacturing an excellent solid electrolyte compatible with a high-voltage cathode is viewed as a critical tactic for improving the energy density of solid-state sodium-ion batteries(SSIBs).A novel asymmetric bilayer solid electrolyte of the PEO-SN-NaClO_(4)|NZSP-NSO with an anti-reduction PEO-SN-NaClO_(4)layer close to the Na side is constructed by solution casting.The ionic conductivity is enhanced by using succinonitrile(SN)in polyethylene oxide(PEO)polymer electrolyte.The anti-oxidation layer of Na_(3)Zr_(2)Si_(2)PO_(12)with Na_(2)SiO_(3)(NZSP-NSO)is served as the support of the membrane on the cathode,which could improve the interface compatibility and electrochemical performance of SSIBs.The asymmetric bilayer solid electrolyte simultaneously features a wide electrochemical stability window(4.65 V vs.Na+/Na)and a high conductivity(2.68×10^(-4) S cm^(-1)).Furthermore,the solid electrolyte demonstrates stable Na plating/stripping over 700 h and remarkably improves cycling stability in Na/Na_(3) V_(2)(PO_(4))_(3) batteries with an ultra-high capacity retention of 99.6%after 100 cycles at 50℃and 0.5 C.This study provides an effective strategy for designing asymmetric high sodium ion conductivity solid-state electrolytes for high-performance SSIBs.

高温胁迫对植物光合作用的影响研究进展

随着人为活动产生的大气CO_(2)浓度的增加,全球气候持续变暖。过去5年是自有温度记录以来最热的5年。高温胁迫已经成为影响植物生长发育的主要逆境因子之一。光合作用是地球生命活动的基础,对环境波动高度敏感。解析植物在高温环境下光合作用的响应特性,可为探索植物抵御高温的生理生态机制、培育抗高温新品种以及采取合理措施适应未来极端气候提供科学依据。该文论述了高温胁迫对植物光合电子传递及碳固定过程的影响,从光质和光强角度综合分析了光照对高温胁迫下光合作用的影响;从植物自身及外源缓解物质等方面阐述了植物增强抗高温胁迫的途径和机制。同时,对植物光合作用响应高温胁迫的研究方向及多组学联合分析在揭示植物抵御高温胁迫机制中的应用进行了展望。

Interfacial engineering of perfluoroalkyl functionalized covalent organic framework achieved ultra-long cycled and dendrite-free lithium anodes

The finite lithium-ion utilization,short cycling life,and lower capacity retention caused by irreversible dendrite growth become the maximum dilemma in lithium metal batteries’(LMBs’)commercialization.Herein,a perfluoroalkyl-functionalized covalent organic framework(COF-F6)equipped with high stability and supernal proton conduction is introduced as an artificial solid electrolyte interface to stable the lithium metal anode.Benefiting from the strong electron-withdrawing effect of perfluoroalkyl,Li^(+)will be freed more by the competition of electronegative fluorine(F)and bis(trifluoromethanesulphonyl)imide anion(TFSI^(-)).The dissociation of LiTFSI and process of Li^(+)desolvation are easier to achieve.In addition,high electronegative fluorine can also regulate local electron-cloud density to induce the fast immigration of Li^(+).All the above roles contribute to improving the Li^(+)transfer number(0.7)and achieving the goal of inhibiting Li dendrite.As a result,the perfluoroalkyl COF-F6 modified LMB presents outstanding cycling stability.The symmetric batteries accomplish an overlong life-span of more than 5000 h with a lower hysteresis voltage(11 mV)at 5 mA·cm^(-2).Also,no dendrites are observed when using an in-situ optical microscope to learn the process of Li deposition.Therefore,this dendrite-free protection tactic holds broad prospects for the practical application of Li metal anodes.

Recent advances in flexible batteries:From materials to applications

Along with the rapid development of flexible and wearable electronic devices,there have been a strong demand for flexible power sources,which has in turn triggered considerable efforts on the research and development of flexible batteries.An ideal flexible battery would have not only just high electrochemical performance but also excellent mechanical deformabilities.Therefore,battery constituent components,chemistry systems,device configurations,and practical applications are all pivotal aspects that should be thoroughly considered.Herein,we systematically and comprehensively review the fundamentals and recent progresses of flexible batteries in terms of these important aspects.Specifically,we first discuss the requirements for constituent components,including the current collector,electrolyte,and separator,in flexible batteries.We then elucidate battery chemistry systems that have been studied for various flexible batteries,including lithium-ion batteries,non-lithium-ion batteries,and high-energy metal batteries.This is followed by discussions on the device configurations for flexible batteries,including onedimensional fiber-shaped,two-dimensional film-shaped,and three-dimensional structural batteries.Finally,we summarize recent efforts in exploring practical applications for flexible batteries.Current challenges and future opportunities for the research and development of flexible batteries are also discussed.

二维sp^(2)碳连接共价有机框架作为无枝晶锂金属电池的人工SEI膜

锂金属负极(LMA)具有前所未有的理论比容量和超低的氧化还原电位,因此锂金属电池(LMBs)得到了广泛的研究.然而,不可控的锂枝晶生长和易碎的固体电解质界面相(SEI)严重阻碍了LMBs的实际商业应用.本文制备了二维sp^(2)碳连接的共价有机框架sp^(2)c-COF,并在LMA表面构建了人工SEI膜,以抑制锂枝晶的形成,并调节界面稳定性.sp^(2)c-COF被设计成沿x和y方向全π共轭的高导电性的结构,从而起到降低界面阻抗、促进Li^(+)通量均匀分布的作用.因此,sp^(2)c-COF改性的对称电池Li^(+)迁移数高达0.85,并且在5mA cm^(-2)电流密度下具有较长的循环寿命(4000 h)和极低的过电位(10 mV).此外还利用原位光学显微镜研究了锂沉积行为,结果表明sp^(2)c-COF能显著提高LMA的界面稳定性.该策略对抑制锂枝晶的形成具有重要的应用价值,可促进COF人工SEI膜的发展.

Understanding a Single-Li-Ion COF Conductor for Being Dendrite Free in a Li-Organic Battery

In addition to improving ion conductivity and the transference number,single-Li-ion conductors(SLCs)also enable the elimination of interfacial side reactions and concentration difference polarization.Therefore,the SLCs can achieve high performance in solid-state batteries with Li metal as anode and organic molecule as cathode.Covalent organic frameworks(COFs)are leading candidates for constructing SLCs because of the excellent 1D channels and accurate chemical-modification skeleton.Herein,various contents of lithium-sulfonated covalently anchored COFs(denoted as LiO,S-COF1 and LiO,S-COF2)are controllably synthesized as SLCs.Due to the directional ion channels,high Li contents,and single-ion frameworks,LiO,SCOF2 shows exceptional Li-ion conductivity of 5.47×10^(-5)S.cm^(-1),high transference number of 0.93,and low activation energy of 0.15eV at room temperature.Such preeminent Li-ion-transported properties of LiO_(3)S-F2 permit stable Li+plating/stripping in a symmetric lithium metal battery,effectively impeding the Li dendrite growth in a liquid cell.Moreover,the designed quasi-solid-state cell(organic anthraquinone(AQ)as cathode,Li metal as anode,and LiO_(3)S-COF2 as electrolyte)shows high-capacity retention and rate behavior.Consequently,LiO_(3)S-COF2 implies a potential value restraining the dissolution of small organic molecules and Li dendrite growth.

碱性盐胁迫对葡萄种间杂交育种F1代光系统活性的影响

以左山一葡萄(Vitis amurensis cv.‘Zuoshan1’)为母本、SO4为父本杂交的4个子代株系(A11、A14、A15和A17)为实验材料,以砧木1103Paulsen(1103P,耐碱性较强)以及欧亚栽培品种Crimson(V.vinifera cv.‘Crimson’)(Crimson的耐碱性强于砧木1103P)为参照,通过测定葡萄叶片PSI及PSⅡ荧光参数,分析葡萄种间杂交砧木育种F_1代光系统活性对100mmol·L^(–1 )NaHCO_3的响应。结果表明,Na HCO_3胁迫下,随着处理时间的延长,Crimson、A15和A14的最大光化学效率(F_v/F_m)、光化学淬灭系数(qP)、光下最大光化学效率(F_v'/F_m')及最大P700荧光产量(P_m)降低幅度较小,非调节性能量耗散(Y(NO))升高幅度也较小,调节性能量耗散(Y(NPQ))升高幅度较大;而A11、A17与砧木1103P各荧光参数变化相近,其F_v/F_m、q P、F_v'/F_m'及P_m的值降低幅度与Y(NO)升高幅度均较大。进一步分析显示,Na HCO_3胁迫8天后,A15和A14的环式电子传递速率(ETR(I)–ETR(Ⅱ))维持在较高水平,缓解了碱性盐胁迫对光系统活性的抑制。各荧光参数指标的主成分分析结果表明,A15的耐碱性较强,A14与Crimson的耐碱性中等,A11、A17与1103P的耐碱性较弱,耐性分级结果与前期依据生物量所得分级结果一致。