Melatonin enhances salt tolerance by promoting MYB108A-mediated ethylene biosynthesis in grapevines

The signal molecules melatonin and ethylene play key roles in abiotic stress tolerance.The interplay between melatonin and ethylene in regulating salt tolerance and the underlying molecular mechanism of this interplay remain unclear.Here,we found that both melatonin and 1-aminocyclopropane-1-carboxylic acid(ACC,a precursor of ethylene)enhanced the tolerance of grapevine to NaCl;additionally,ethylene participated in melatonin-induced salt tolerance.Further experiments indicated that exogenous treatment and endogenous induction of melatonin increased the ACC content and ethylene production in grapevine and tobacco plants,respectively.The expression of MYB108A and ACS1,which function as a transcription factor and a key gene involved in ethylene production,respectively,was strongly induced by melatonin treatment.Additionally,MYB108A directly bound to the promoter of ACS1 and activated its transcription.MYB108A expression promoted ACC synthesis and ethylene production by activating ACS1 expression in response to melatonin treatment.The suppression of MYB108A expression partially limited the effect of melatonin on the induction of ethylene production and reduced melatonin-induced salt tolerance.Collectively,melatonin promotes ethylene biosynthesis and salt tolerance through the regulation of ACS1 by MYB108A.

One-pot degradation of cellulose into carbon dots and organic acids in its homogeneous aqueous solution

As the abundant biopolymer, cellulose can be used as a feedstock for chemicals and materials. Effective conversion of cellulose by simple processes is a key point. Degradation of cellulose in its homogeneous solution is attractive for the molecular chains are free and spread. Here,microcrystalline cellulose was first dissolved in aqueous solution of Na OH and urea, and then hydrothermal reaction was carried out at various temperature and time. Fluorescence carbon dots(CDs) were generated accompanied with six organic acids: oxalic acid, formic acid, malonic acid, lactic acid, acetic acid, and fumaric acid. The yields of all organic acids and CDs, and the fluorescence quantum yield(QY) of CDs were studied at different reaction conditions. It was found that the maximum yield of organic acids and CDs are 80.1% and 6.03%, respectively, and the highest QY of the CDs is 10.9%. Fluorescence studies reveal that the as-prepared CDs has efficient selectivity and sensitivity toward iron ions in acidic condition, indicating it is a potential fluorescent sensor to the detection of Fe3+. Importantly, it provides a panorama to summary the degradation routes of cellulose in its homogeneous aqueous solution with both organic molecules and CDs as products.

MicroRNA-449a suppresses hepatocellular carcinoma cell growth via G1 phase arrest and the HGF/MET c-Met pathway

Background: Accumulating evidence demonstrates that microRNAs(miRNAs) play essential roles in tumorigenesis and cancer progression of hepatocellular carcinoma(HCC). Average targets of a miRNA were more than 100. And one miRNA may act in tumor via regulating several targets. The present study aimed to explore more potential targets of miR-449a by proteomics technology and further uncover the role of miR-449a in HCC tumorigenesis.Methods: Technologies such as i TRAQ-based quantitative proteomic were used to investigate the effect of miR-449a on HCC. The expression of c-Met and miR-449a was detected by q RT-PCR in HCC samples.Gain-and loss-of-function experiments were performed to identify the function and potential target of miR-449a in HCC cells.Results: In HCC, miR-449a was significantly downregulated, while c-Met was upregulated concurrently.Quantitative proteomics and luciferase reporter assay identified c-Met as a direct target of miR-449a.Moreover, miR-449a inhibited HCC growth not only by targeting CDK6 but also by suppressing cMet/Ras/Raf/ERK signaling pathway. Furthermore, the inhibition of c-Met expression with a specific siRNA significantly inhibited cells growth and deregulated the ERK pathway in HCC.Conclusion: The tumor suppressor miR-449a suppresses HCC tumorigenesis by repressing the c-Met/ERK pathway.

Elastic interaction between inclusions and tunable periodicity of superlattice structure in nanowires

The elastic stress distribution and the variation of the elastic energy with spacing between two inclusions of arbitrary sizes in an infinite isotropic cylindrical rod are obtained by an analytical approach and the phase field microelasticity(PFM)simulation.The results show a near-attraction and far-repulsion elastic interaction between two inclusions with hydrostatic dilatation.The critical spacing,at which the interaction changes from attraction to repulsion,is on the order of the radius of the rod,dependent on the length and Poisson’s ratio of inclusions.Furthermore,the elastic energy calculations and PFM simulation results indicate that applying the local radial stress on the rod surface can modulate the elastic interaction between inclusions and adjust the periodicity of the superlattice nanowire structure.This can provide some guidelines for the tunable construction of superlattice nanowire structures.

Phase-field simulation of the coupled evolutions of grain and twin boundaries in nanotwinned polycrystals

Nanotwinned polycrystals exhibit an excellent strength-ductility combination due to nanoscale twins and grains. However, nanotwin-assisted grain coarsening under mechanical loading reported in recent experiments may result in strength drop based on the Hall-Petch law. In this paper, a phase-field model is developed to investigate the effect of coupled evolutions of twin and grain boundaries on nanotwin-assisted grain growth. The simulation result demonstrates that there are three pathways for coupled motions of twin and grain boundaries in a bicrystal under the applied loading, dependent on the amplitude of applied loading and misorientation of the bicrystal. It reveals that a large misorientation angle and a large applied stress promote the twinning-driven grain boundary migration. The resultant twin-assisted grain coarsening is confirmed in the simulations for the microstructural evolutions in twinned and un-twinned polycrystals under a high applied stress.

Pentagon-Containing Doublet Graphene Fragments with Edge-Dependent Spin/Charge Distribution

The synthesis of stable open-shell hydrocarbon system comprising of pentagon defects and zigzag edges remains unexplored,which can be considered as model compounds for unraveling the spin-localized states in graphene edges.With concise synthetic approaches,twoπ-extended fluorenyl radicals were synthesized and isolated in their crystalline state.X-ray crystallographic analysis and studies on the magnetic,optical and electrochemical properties of neutral and charged species have revealed an interesting edge-dependence of the spin/charge distribution,that is,the spin and charge distribution shifted from the pentagon defects to the zigzag edges with the elongation of conjugation.Such phenomenon was unprecedented for hydrocarbon radicals and can be rationalized by the recovery of Clar Sextets in the dominant resonance structures.Remarkably,one of the radicals exhibited exceptional stability in air-saturated solutions with the half-life time up to 260 d,thus providing opportunities for the applications as electronic materials.

GIANT ANHYSTERETIC RESPONSE OF FERROELECTRIC SOLID SOLUTIONS WITH MORPHOTROPIC BOUNDARIES: THE ROLE OF POLAR ANISOTROPY

Computer modeling and simulation for the Pb（Zr1-x Tix ）O3 （PZT） system reveal the role of polar anisotropy on the giant anhysteretic response and structural properties of morphotropic phase boundary （MPB） ferroelectrics. It is shown that a drastic reduction of the compositiondependent polar anisotropy near the MPB flattens energy surfaces and thus facilitates reversible polarization rotation. It is further shown that the polar anisotropy favors formation of polar domains, promotes phase decomposition and results in a two-phase multidomain state, which response to applied electric field is anhysteretic when the polar domain reorientation is only caused by polarization rotation other than polar domain wall movement. This is the case for the decomposing ferroelectrics under a poling electric field with the formation of a two-phase multidomain microstructure, wherein most domain walls are pinned at the two-phase boundaries. Indication of the microstructure dependence of the anhysteretic strain response opens new avenues to improve the piezoelectric properties of these materials through the microstructure engineering.

Axially N-Embedded Quasi-Carbon Nanohoops with Multioxidation States

The incorporation of heteroatoms into carbon nanohoops can significantly overcome aromatic stabilization energy and enrich their physicochemical properties depending on the positions and numbers of the doped atoms.Utilizing a V-shaped dipyreneo[c,e]dihydrophenazine as the building block,herein we report a novel kind of axially N-embedded quasi-carbon nanohoops by integratingπ-extended dihydropyrazine and para-phenylene subunits.Singlecrystal X-ray diffraction analyses revealed that their geometrical structures varied from droplet-shaped geometry for DPP-M and suppressed elliptical cross-section configuration for DPP-D to triangularly prismatic configuration for DPP-T.Spectroscopic measurements confirmed rich electronic properties,especially multioxidation behaviors due to the embedding of graphitic-N atoms,which are not observed in carbonaceous nanohoops and other analogs.Further investigations,including electron spin resonance spectroscopy,theoretical calculations,and single-crystal structure analyses,on the oxidized species of both DPP-D and DPP-T demonstrated their tunable open-shell ground states for the dications.This work provides a new synthetic strategy to axially N-embedded quasi-carbon nanohoops and gives insights into the design of structure-precise segments of graphitic-N-doped single-walled carbon nanotubes.

Emergent antisymmetric wrinkling patterns in films on ridged substrates

We report the formation of antisymmetric wrinkling patterns in films on ridged substrates induced by the buckling instability of the substrates via finite element simulations and experiments.Our simulated results reveal that the uniaxial compression along the ridge can trigger both the wrinkling instability of the film and the lateral buckling instability of the ridge.The latter could change the wrinkles from a symmetric pattern to an antisymmetric pattern in a range of film-substrate modulus ratio and aspect ratio of the ridge profile,as validated by the experimental observations.A three-dimensional phase diagram with four buckling patterns,i.e.,sole ridge buckling pattern,antisymmetric wrinkling pattern with different wavelengths from ridge buckling,symmetric wrinkling pattern without ridge buckling,and antisymmetric wrinkling pattern with the same wavelength as ridge buckling,is built with respect to the uniaxial compression,modulus ratio,and aspect ratio.The results not only elucidate how and when the interplay between the wrinkling instability and the ridge instability results in the formation of the antisymmetric wrinkling pattern but also offer a way to generate controllable complex wrinkling patterns.

基底上薄膜结构的非线性屈曲力学进展

基底上薄膜结构中的过大残余压应力常常通过屈曲不稳定性诱发薄膜结构和功能的失效.屈曲不稳定性、演化与斑图形成是近年来非线性力学研究的热点.此类屈曲不稳定性受薄膜-基底的力学性质以及界面相互作用影响,进而呈现出复杂的屈曲模式如褶皱、翘曲和折痕等.论文简要综述褶皱、翘曲和折痕等屈曲模式的形成机制、影响因素和后屈曲形貌相关方面的进展.褶皱部分,重点介绍了褶皱的形成、多级褶皱结构、局域化的褶皱、各向异性褶皱和曲面上的褶皱.翘曲部分,介绍了翘曲结构包括一维翘曲结构、＂电话线＂屈曲泡、网络状屈曲泡等的形成与生长过程,并讨论了曲面几何、界面滑移、开裂等因素的影响.折痕及其它复杂屈曲模式部分,介绍了折痕、叠痕及隆起失稳的形成机制与临界条件.

HIF-1α-induced expression of m6A reader YTHDF1 drives hypoxia-induced autophagy and malignancy of hepatocellular carcinoma by promoting ATG2A and ATG14 translation

N6-methyladenosine(m6A),and its reader protein YTHDF1,play a pivotal role in human tumorigenesis by affecting nearly everystage of RNA metabolism.Autophagy activation is one of the ways by which cancer cells survive hypoxia.However,the possibleinvolvement of m6A modification of mRNA in hypoxia-induced autophagy was unexplored in human hepatocellular carcinoma(HCO).In this study,specific variations in YTHDF1 expression were detected in YTHDF1-overexpressing,knockout,and-knockdownHCC cells,HCC organoids,and HCC patient-derived xenograft(PDX)murine models.YTHDF1 expression and hypoxia inducedautophagy were significantly correlated in vitro;signifhcant overexpression of YTHDF1 in HCC tissues was associated with poorprognosis,Multivariate cox regression analysis identihed YTHDF1 expression as an independent prognostic factor in patients withHCC.Multiple HC models conhrmed that YTHDF1 deficiency inhibited HCC autophagy,growth,and metastasis.Luciferase reporterassays and chromatin immunoprecipitation demonstrated that HlIF-1a regulated YTHDF1 transcription by directly binding to itspromoter region under hypoxia.The results of methylated RNA immunoprecipitation sequencing,proteomics,and polysomeprofling indicated that YTHDF1 contibuted to the translation of autophagy-related genes ATG2A and ATG14 by binding to m6A-modifhed ATG2A and ATG14 mRNA,thus facilitating autophagy and autophagy-related malignancy of HCC.Taken together,HlE-1d-induced YTHDF1 expression was associated with hypoxia-induced autophagy and autophagy-related HCC progression via promoting translation of autophagy-related genes ATG2A and ATG14 in a m6A-dependent manner.Our fndings suggest thatYTHDF1 is a potential prognostic biomarker and therapeutic target for patients with HCC.

Catalytic oxidation of benzene over Ce-Mn oxides synthesized by flame spray pyrolysis

Flame spray pyrolysis （FSP） was utilized to synthesize Ce-Mn oxides in one step for catalytic oxidation of benzene. Cerium acetate and manganese acetate were used as precursors. The materials synthesized were characterized using X-ray diffraction （XRD）, N2 adsorption, X-ray photoelectron spectroscopy （XPS）, transmission electron microscopy （TEM）, Raman spectroscopy, and H2-temperature programmed reduc- tion （H2-TPR） and their benzene catalytic oxidation behavior was evaluated. Mn ions were evidenced in multiple chemical states. Crystalline Ce-Mn oxides consist of particles with size 〈40 nm and specific sur- face areas （SSA） of 20-50 m2/g. Raman spectrums and H2-TPR results indicated the interaction between cerium and manganese oxides. Flame-made 12.5%-Ce-Mn oxide exhibited excellent catalytic activity at relatively low temperatures （T95 about 260℃） compared to other Ce-Mn oxides with different cerium- to-manganese ratios, Redox mechanism and strong interaction conform to structure analysis that Ce-Mn strong interaction formed during the high temperature flame process and the results were used to explain catalytic oxidation of benzene.

Variation in spatial and temporal kinematics of level, vertical and inverted locomotion on a stinkbug Erthesina fullo

In the learning of locomotion behavior of a stinkbug Erthesina fullo, the seeked principle of its locomotion can be an important inspiration on the design of six-legged robot. To achieve this goal, in this paper, locomotion behavior of stinkbugs on glass and plastic foam are recorded. Hereby, variation in spatial and temporal kinematics of level, vertical and inverted locomotion is analyzed. Differential leg function and adhesive mechanism as well as the advantage of non-isometric legs of insects are presented. With increasing stride frequency, the speed of level, vertical and inverted locomotion can be higher without adjusting stride length. Variation in gait characteristics between level and vertical locomotion is very little, but lower speed and larger duty factor of inverted locomotion can be occurred while climbing on glass. On the surface of vertical and inverted plastic foam, stinkbugs cannot walk steady and agilely due to its adhesive mechanism.

Stress-mediated lithiation in nanoscale phase transformation electrodes

Development of high-performance phase transformation electrodes in lithium ion batteries requires comprehensive studies on stress-mediated lithiation involving migration of the phase interface. It brings out many counter-intuitive phenomena, especially in nanoscale electrodes, such as the slowing down migration of phase interface, the vanishing of miscibility gap under high charge rate, and the formation of surface crack during lithiation. However, it is still a challenge to simulate the evolution of stress in arbitrarily-shaped nanoscale electrodes, accompanied with phase transformation and concurrent plastic deformation. This article gives a brief review of our efforts devoted to address these issues by developing phase field model and simulation. We demonstrate that the miscibility gap of two-phase state is affected not only by stress but also by surface reaction rate and particle size. In addition, the migration of phase interface slows down due to stress. It reveals that the plastic deformation generates large radial expansion, which is responsible for the transition from surface hoop compression to surface hoop tension that may induce surface crack during lithiation. We hope our effort can make a contribution to the understanding of stress-coupled kinetics in phase transformation electrodes.

Improved phase field model of dislocation intersections

Revealing the long-range elastic interaction and short-range core reaction between intersecting dislocations is crucial to the understanding of dislocation-based strain hardening mechanisms in crystalline solids.Phase field model has shown great potential in modeling dislocation dynamics by both employing the continuum microelasticity theory to describe the elastic interactions and incorporating theγ-surface into the crystalline energy to enable the core reactions.Since the crystalline energy is approximately formulated by linear superposition of interplanar potential of each slip plane in the previous phase field model,it does not fully account for the reactions between dislocations gliding in intersecting slip planes.In this study,an improved phase field model of dislocation intersections is proposed through updating the crystalline energy by coupling the potential of two intersecting planes,and then applied to study the collinear interaction followed by comparison with the previous simulation result using discrete dislocation dynamics.Collinear annihilation captured only in the improved phase field model is found to strongly affect the junction formation and plastic flow in multislip systems.The results indicate that the improvement is essential for phase field model of dislocation intersections.

Moisture-triggered actuator and detector with high-performance: interface engineering of graphene oxide/ethyl cellulose

Actuators that can directly convert other forms of environmental energy into mechanical work offer great application prospects in intriguing energy applications and smart devices. But to-date, low cohesion strength of the interface and humidity responsive actuators primarily limit their applications. Herein, by experimentally optimizing interface of bimorph structure, we build graphene oxide/ethyl cellulose bidirectional bending actuators — a case of bimorphs with fast and reversible shape changes in response to environmental humidity gradients. Meanwhile, we employ the actuator as the engine to drive piezoelectric detector. In this case, graphene oxide and ethyl cellulose are combined with chemical bonds, successfully building a bimorph with binary synergy strengthening and toughening. The excellent hygroscopicity of graphene oxide accompanied with huge volume expansion triggers giant moisture responsiveness greater than 90 degrees. Moreover, the open circuit voltage of piezoelectric detector holds a peak value around 0.1 V and exhibits excellent reversibility. We anticipate that humidity-responsive actuator and detector hold promise for the application and expansion of smart devices in varieties of multifunctional nanosystems.

Oxidation of furfural to maleic acid and fumaric acid in deep eutectic solvent(DES)under vanadium pentoxide catalysis

Furfural is an alternative feedstock and has been used for the production of maleic acid(MA)and fumaric acid(FA)by an oxidation process.Deep eutectic solvents(DESs)were used as the green solvents while sodium chlorate was used as an oxidant and vanadium pentoxide was used as the catalyst at 70-90°C under atmospheric pressure.It was found that several acidic DESs are valid,such as acetic acid/choline chloride(AA/ChCl)and propionic acid/choline chloride(PA/ChCl),and AA/ChCl DES was selected as the solvent for the conversion.The optimal DES is AA/ChCl,and the effect of the amount of oxidant,time,and temperature on the yield of the MA and FA has been systematically studied,and the conversion of furfural can reach 100%while the yield of the MA and FA reached 66.5%under reaction temperature of 80℃ for 12 h,which provides a new green route to synthesis valuable monomers from furfural.