Creep behavior of AJ62 Magnesium-Aluminum-Strontium alloy

Creep tests were conducted in uniaxial compression to evaluate the creep behavior of magnesium-aluminum-strontium alloy at temperatures from 373 to 673 K.Stress dependencies of the creep rate over the whole interval of temperatures and stresses can be well described phenomenologically by the Garofalo sine hyperbolic equation modified by the inclusion of a threshold stress.The threshold stress increases with decreasing temperature.Creep data normalized by a diffusion coefficient and shear modulus clearly reveal the existence of two different regions.Possible mechanisms by which plastic deformation takes place have been identified in both regions.The critical stress at which dislocations break away from the cloud of foreign atoms agrees well with the value determined by data normalization.At low stresses,a value of the stress exponent of n≈=3 is consistent with the model of deformation that takes place through dislocation glide controlled by dragging of solute atoms.At high stresses,the multiple regression yields the activation energy which agrees with that for prismatic glide.

Cytokinins regulate spatially specific ethylene production to control root growth in Arabidopsis

Two principal growth regulators,cytokinins and ethylene,are known to interact in the regulation of plant growth.However,information about the underlying molecular mechanism and positional specificity of cytokinin/ethylene crosstalk in the control of root growth is scarce.We have identified the spatial specificity of cytokinin-regulated root elongation and root apical meristem(RAM)size,both of which we demonstrate to be dependent on ethylene biosynthesis.Upregulation of the cytokinin biosynthetic gene ISOPENTENYLTRANSFERASE(IPT)in proximal and peripheral tissues leads to both root and RAM shortening.By contrast,IPT activation in distal and inner tissues reduces RAM size while leaving the root length comparable to that of mock-treated controls.We show that cytokinins regulate two steps specific to ethylene biosynthesis:production of the ethylene precursor 1-aminocyclopropane-1-carboxylate(ACC)by ACC SYNTHASEs(ACSs)and its conversion to ethylene by ACC OXIDASEs(ACOs).We describe cytokinin-and ethylene-specific regulation controlling the activity of ACSs and ACOs that are spatially discrete along both proximo/distal and radial root axes.Using direct ethylene measurements,we identify ACO2,ACO3,and ACO4 as being responsible for ethylene biosynthesis and ethylene-regulated root and RAM shortening in cytokinin-treated Arabidopsis.Direct interaction between ARABIDOPSIS RESPONSE REGULATOR 2(ARR2),a member of the multistep phosphorelay cascade,and the C-terminal portion of ETHYLENE INSENSITIVE 2(EIN2-C),a key regulator of canonical ethylene signaling,is involved in the cytokinin-induced,ethylene-mediated control of ACO4.We propose tight cooperation between cytokinin and ethylene signaling in the spatially specific regulation of ethylene biosynthesis as a key aspect of the hormonal control of root growth.

High temperature increases centromeremediated genome elimination frequency and enhances haploid induction in Arabidopsis

Double haploid production is the most effective way to create true-breeding lines in a single generation.In Arabidopsis,haploid induction via mutation of the centromere-specific histone H3(cenH3)has been shown when the mutant is outcrossed to the wild-type,and the wild-type genome remains in the haploid progeny.However,factors that affect haploid induction are still poorly understood.Here,we report that a mutant of the cenH3 assembly factor Kinetochore Null2(KNL2)can be used as a haploid inducer when pollinated by the wild-type.We discovered that short-term temperature stress of the knl2 mutant increased the efficiency of haploid induction 10-fold.We also demonstrated that a point mutation in the CENPC-k motif of KNL2 is sufficient to generate haploid-inducing lines,suggesting that haploidinducing lines in crops can be identified in a naturally occurring or chemically induced mutant population,avoiding the generic modification(GM)approach at any stage.Furthermore,a cenh3-4 mutant functioned as a haploid inducer in response to short-term heat stress,even though it did not induce haploids under standard conditions.Thus,we identified KNL2 as a new target gene for the generation of haploid-inducer lines and showed that exposure of centromeric protein mutants to high temperature strongly increases their haploid induction efficiency.

High-resolution characterization of hexagonal boron nitride coatings exposed to aqueous and air oxidative environments

Hexagonal boron nitride （h-BN） is believed to offer better passivation to metallic surfaces than graphene owing to its insulating nature, which facilitates blocking the flow of electrons, thereby preventing the occurrence of galvanic reactions. Nevertheless, this may not be the case when an h-BN-protected material is exposed to aqueous environments. In this work, we analyzed the stability of mono and multilayer h-BN stacks exposed to H202 and atmospheric conditions. Our experiments revealed that monolayer h-BN is as inefficient as graphene as a protective coating when exposed to H202. Multilayer h-BN offered a good degree of protection. Monolayer h-BN was found to be ineffective in an air atmosphere as well. Even a 10-15 layers-thick h-BN stack could not completely protect the surface of the metal under consideration. By combining Auger electron spectroscopy and secondary ion mass spectrometry techniques, we observed that oxygen could diffuse through the grain boundaries of the h-BN stack to reach the metallic substrate. Fortunately, because of the diffusive nature of the process, the oxidized area did not increase with time once a saturated state was reached. This makes multflayer （not monolayer） h-BN a suitable long-term oxidation barrier. Oxygen infiltration could not be observed by X-ray photoelectron spectroscopy. This technique cannot assess the chemical composition of the deeper layers of a material. Hence, the previous reports, which relied on XPS to analyze the passivating properties of h-BN and graphene, may have ignored some important subsurface phenomena. The results obtained in this study provide new insights into the passivating properties of mono and multilayer h-BN in aqueous media and the degradation kinetics of h-BN-coated metals exposed to an air environment.

Osmotic Stress Modulates the Balance between Exocytosis and Clathrin-Mediated Endocytosis in Arabidopsis thaliana

The sessile life style of plants creates the need to deal with an often adverse environment, in which water availability can change on a daily basis, challenging the cellular physiology and integrity. Changes in os- motic conditions disrupt the equilibrium of the plasma membrane： hypoosmotic conditions increase and hyperosmotic environment decrease the cell volume. Here, we show that short-term extracellular osmotic treatments are closely followed by a shift in the balance between endocytosis and exocytosis in root mer- istem cells. Acute hyperosmotic treatments （ionic and nonionic） enhance clathrin-mediated endocytosis simultaneously attenuating exocytosis, whereas hypoosmotic treatments have the opposite effects. In addition to clathrin recruitment to the plasma membrane, components of early endocytic trafficking are essential during hyperosmotic stress responses. Consequently, growth of seedlings defective in elements of clathrin or early endocytic machinery is more sensitive to hyperosmotic treatments. We also found that the endocytotic response to a change of osmotic status in the environment is dominant over the presum- ably evolutionary more recent regulatory effect of plant hormones, such as auxin. These results imply that osmotic perturbation influences the balance between endocytosis and exocytosis acting through clathrin- mediated endocytosis. We propose that tension on the plasma membrane determines the addition or removal of membranes at the cell surface, thus preserving cell integrity.

A sensing mechanism for the detection of carbon nanotubes using selective photoluminescent probes based on ionic complexes with organic dyes

The multifunctional properties of carbon nanotubes(CNTs)make them a powerful platform for unprecedented innovations in a variety of practical applications.As a result of the surging growth of nanotechnology,nanotubes present a potential problem as an environmental pollutant,and as such,an efficient method for their rapid detection must be established.Here,we propose a novel type of ionic sensor complex for detecting CNTs–an organic dye that responds sensitively and selectively to CNTs with a photoluminescent signal.The complexes are formed through Coulomb attractions between dye molecules with uncompensated charges and CNTs covered with an ionic surfactant in water.We demonstrate that the photoluminescent excitation of the dye can be transferred to the nanotubes,resulting in selective and strong amplification(up to a factor of 6)of the light emission from the excitonic levels of CNTs in the near-infrared spectral range,as experimentally observed via excitation-emission photoluminescence(PL)mapping.The chirality of the nanotubes and the type of ionic surfactant used to disperse the nanotubes both strongly affect the amplification;thus,the complexation provides sensing selectivity towards specific CNTs.Additionally,neither similar uncharged dyes nor CNTs covered with neutral surfactant form such complexes.As model organic molecules,we use a family of polymethine dyes with an easily tailorable molecular structure and,consequently,tunable absorbance and PL characteristics.This provides us with a versatile tool for the controllable photonic and electronic engineering of an efficient probe for CNT detection.

Progress and perspective of high strain NBT-based lead-free piezoceramics and multilayer actuators

In this review,the evolution of high strain Na_(0.5)Bi_(0.5)TiO_(3)-based lead-free piezoceramics and their multilayer actuators has been explored.First,in terms of Na_(0.5)Bi_(0.5)TiO_(3)-based ceramic materials,the origin of high strain,the typical chemical modification methods of obtaining large strain and extrinsic factors affecting the large strain are discussed.Then it briefly summarizes the problems existing in Na_(0.5)Bi_(0.5)TiO_(3)-based ceramics for multilayer actuator applications.Strategies to optimize strain performance by means of microstructure control and phase structure design are also discussed.Thereafter,in terms of multilayer actuator,we describe its characteristics,applications and preparation process systematically,as well as the recent development of Na_(0.5)Bi_(0.5)TiO_(3)-based multilayer actuator.At last,perspectives on directions of following work and promising fields for the applications of the materials and their devices are presented.

ABP1： Finally Docking

Auxin, one of the plant hormones, is a key regulator of plant growth and development. At the cellular level, it controls different processes, such as cell expansion, division, and differentiation that are reflected by its regulatory role in a plethora of developmental mechanisms. An important feature of the auxin action is its differential distribution within tissues mediated by the polar auxin transport machinery, which can be dynamically regulated in response to internal and external stimuli. Receptors at the cell surface or cell interior are needed to sense and interpret fluctuations in the auxin distribution.

Enquiry into the Topology of Plasma Membrane- Localized PIN Auxin Transport Components

Auxin directs plant ontogenesis via differential accumulation within tissues depending largely on the activity of PIN proteins that mediate auxin efflux from cells and its directional cell-to-cell transport. Regard- less of the developmental importance of PINs, the structure of these transporters is poorly characterized. Here, we present experimental data concerning protein topology of plasma membrane-localized PINs. Utilizing approaches based on pH-dependent quenching of fluorescent reporters combined with immuno- localization techniques, we mapped the membrane topology of PINs and further cross-validated our results using available topology modeling software. We delineated the topology of PIN1 with two transmembrane （TM） bundles of five m-helices linked by a large intracellular loop and a C-terminus positioned outside the cytoplasm. Using constraints derived from our experimental data, we also provide an updated position of helical regions generating a verisimilitude model of PIN1. Since the canonical long PINs show a high degree of conservation in TM domains and auxin transport capacity has been demonstrated for Arabidopsis representatives of this group, this empirically enhanced topological model of PIN1 will be an important starting point for further studies on PIN structure-function relationships. In addition, we have established protocols that can be used to probe the topology of other plasma membrane proteins in plants.

Retromer Subunits VPS35A and VPS29 Mediate Prevacuolar Compartment （PVC） Function in Arabidopsis

Intracellular protein routing is mediated by vesicular transport which is tightly regulated in eukaryotes. The protein and lipid homeostasis depends on coordinated delivery of de novo synthesized or recycled cargoes to the plasma membrane by exocytosis and their subsequent removal by rerouting them for recycling or degradation. Here, we report the characterization of protein affected trafficking 3 （pat3） mutant that we identified by an epifluorescence-based for- ward genetic screen for mutants defective in subcellular distribution of Arabidopsis auxin transporter PIN1-GFR While pat3 displays largely normal plant morphology and development in nutrient-rich conditions, it shows strong ectopic intracellular accumulations of different plasma membrane cargoes in structures that resemble prevacuolar compart- ments （PVC） with an aberrant morphology. Genetic mapping revealed that pat3 is defective in vacuolar protein sorting 35A （VPS35A）, a putative subunit of the retromer complex that mediates retrograde trafficking between the PVC and trans-Golgi network. Similarly, a mutant defective in another retromer subunit, vps29, shows comparable subcellular defects in PVC morphology and protein accumulation. Thus, our data provide evidence that the retromer components VPS35A and VPS29 are essential for normal PVC morphology and normal trafficking of plasma membrane proteins in plants. In addition, we show that, out of the three VPS35 retromer subunits present in Arabidopsis thaliana genome, the VPS35 homolog A plays a prevailing role in trafficking to the lyric vacuole, presenting another level of complexity in the retromer-dependent vacuolar sorting.

Small P values may not yield robust findings:an example using REST-meta-PD

Thousands of resting state functional magnetic resonance imaging(RS-f MRI)articles have been published on brain disorders.For precise localization of abnormal brain activity,a voxel-level comparison is needed.Because of the large number of voxels in the brain,multiple comparison correction(MCC)must be performed to reduce false positive rates,and a smaller P value(usually including either liberal or stringent MCC)is widely recommended[1].