Band structure by design in 2D layered semiconductors is highly desirable, with the goal to acquire the electronic properties of interest through the engineering of chemical composition, structure, ...defect, stacking, or doping. For atomically thin transition metal dichalcogenides, substitutional doping with more than one single type of transition metals is the task for which no feasible approach is proposed. Here, the growth of WS2 monolayer is shown codoped with multiple kinds of transition metal impurities via chemical vapor deposition controlled in a diffusion‐limited mode. Multielement embedment of Cr, Fe, Nb, and Mo into the host lattice is exemplified. Abundant impurity states thus generate in the bandgap of the resultant WS2 and provide a robust switch of charging/discharging states upon sweep of an electric filed. A profound memory window exists in the transfer curves of doped WS2 field‐effect transistors, forming the basis of binary states for robust nonvolatile memory. The doping technique presented in this work brings one step closer to the rational design of 2D semiconductors with desired electronic properties.
Multielement codoped monolayer WS2 is synthesized using chemical vapor deposition. No dopant clustering and phase segregation occur and WS2 retains n‐type semiconducting properties. Substantial and stable impurities states are introduced near the conduction band minimum. Through the charging/discharging of the impurity states, the doped WS2 functions as a nonvolatile memory with long charge‐retention time.
In this study, AlCrSiNbZr nitride thin films were deposited on Si substrate by reactive radio frequency magnetron sputtering under the substrate bias from 0 V to −100 V at room temperature. The ...effect of substrate bias on structure, morphology, hardness and resistivity of the films was investigated. The results show that (111) preferred orientation was dominant phases for samples under bias of 0 V, −25 V, −50 V and − 75 V whereas amorphous-like feature was observed for samples under the bias of −100 V. In addition, crystallinity of film was enhanced when the substrate bias increased from 0 V to −50 V, but decreased when substrate bias further increased from −50 V to −100 V, suggesting that the optimized crystallinity of films was achieved under the substrate bias of −50 V. The oxygen contents of the thin films decreased significantly when the substrate bias was higher than −25 V. The hardness of the films was divided into two regions and samples under bias of −75 V and −100 V possessed higher hardness than those under bias of 0 V, −25 V and −50 V, which was mainly attributed to less oxynitride phases for samples under bias of −75 V and −100 V. The resistivity of thin films decreased as the substrate bias increased, which was mainly affected by the concentration of oxygen in films. The optimized substrate bias was −75 V with the maximum hardness and lowest resistivity.
•(AlCrSiNbZr)N thin films fabricated by reactive RF magnetron sputtering•Effect of substrate bias on structure and properties of film was studied.•Amorphous and FCC structures can be achieved by adjusting substrate bias.•Optimized substrate bias is −75 V with the maximum hardness and low resistivity.
Summary
Grain size is one of the essential determinants of rice yield. Our previous studies revealed that ethylene plays an important role in grain‐size control; however, the precise mechanism ...remains to be determined. Here, we report that the ethylene response factor OsERF115 functions as a key downstream regulator for ethylene‐mediated grain development. OsERF115 encodes an AP2/ERF‐type transcriptional factor that is specifically expressed in young spikelets and developing caryopses. Overexpression of OsERF115 significantly increases grain length, width, thickness and weight by promoting longitudinal elongation and transverse division of spikelet hull cells, as well as enhancing grain‐filling activity, whereas its knockout mutations lead to the opposite effects, suggesting that OsERF115 positively regulates grain size and weight. OsERF115 transcription is strongly induced by ethylene, and OsEIL1 directly binds to the promoter to activate its expression. OsERF115 acts as a transcriptional repressor to directly or indirectly modulate a set of grain‐size genes during spikelet growth and endosperm development. Importantly, haplotype analysis reveals that the SNP variations in the EIN3‐binding sites of OsERF115 promoter are significantly associated with the OsERF115 expression levels and grain weight, suggesting that natural variations in the OsERF115 promoter contribute to grain‐size diversity. In addition, the OsERF115 orthologues are identified only in grass species, implying a conserved and unique role in the grain development of cereal crops. Our results provide insights into the molecular mechanism of ethylene‐mediated grain‐size control and a potential strategy based on the OsEIL1‐OsERF115‐target gene regulatory module for genetic improvement of rice yield.
The transcriptional induction of OsERF115 by ethylene depends on OsEIL1 directly activating its expression. OsERF115 regulates the downstream genes to enhance cells proliferation and expansion, ultimately leading to an increase in grain size in rice.
Herein, we aim to develop a facile method for the fabrication of mechanical metamaterials from templated polymerization of thermosets including phenolic and epoxy resins using self-assembled block ...copolymer, polystyrene–polydimethylsiloxane with tripod network (gyroid), and tetrapod network (diamond) structures, as templates. Nanoindentation studies on the nanonetwork thermosets fabricated reveal enhanced energy dissipation from intrinsic brittle thermosets due to the deliberate structuring; the calculated energy dissipation for gyroid phenolic resins is 0.23 nJ whereas the one with diamond structure gives a value of 0.33 nJ. Consistently, the gyroid-structured epoxy gives a high energy dissipation value of 0.57 nJ, and the one with diamond structure could reach 0.78 nJ. These enhanced properties are attributed to the isotropic periodicity of the nanonetwork texture with plastic deformation, and the higher number of struts in the tetrapod diamond network in contrast to tripod gyroid, as confirmed by the finite element analysis.
Wild relatives of crops are an important source of genetic diversity for agriculture, but their gene repertoire remains largely unexplored. We report the establishment and analysis of a pan-genome of ...Glycine soja, the wild relative of cultivated soybean Glycine max, by sequencing and de novo assembly of seven phylogenetically and geographically representative accessions. Intergenomic comparisons identified lineage-specific genes and genes with copy number variation or large-effect mutations, some of which show evidence of positive selection and may contribute to variation of agronomic traits such as biotic resistance, seed composition, flowering and maturity time, organ size and final biomass. Approximately 80% of the pan-genome was present in all seven accessions (core), whereas the rest was dispensable and exhibited greater variation than the core genome, perhaps reflecting a role in adaptation to diverse environments. This work will facilitate the harnessing of untapped genetic diversity from wild soybean for enhancement of elite cultivars.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The deformation behavior of materials at high temperatures determines the structural stability of mechanical structures under high-temperature service conditions. In this work, we prepare helical ...springs from 304 stainless-steel wires and study creep-recovery deformation of the helical springs under small forces at temperatures of 475–575 °C. In contrast to most methods reported in the literature, we use Kelvin representation of the Burgers model with a nonlinear dashpot in series connection to analyze the creep-recovery deformation of the helical springs and suggest the deformation mechanisms of the diffusion of interstitial atoms and dislocation generation/annihilation in transient creep and recovery of the helical springs under small forces. For the creep deformation, the stress exponent and activation energy for the plastic flow of the nonlinear dashpot are 2 and 57.8 kJ/mol, respectively, and the activation energy for the deformation flow of the linear dashpot is 41.8 kJ/mol. The nonlinear dashpot does not play any role in the recovery deformation, and the formation energy of defects for the recovery deformation of the helical springs is 51.4 kJ/mol. The approach used in this work provides a simple method to use a phenomenological model with a nonlinear dashpot to capture the power-law creep deformation of metallic materials.
•Creep-recovery deformation of coiled stainless springs is studied under low forces.•Kelvin representation of nonlinear Burgers model describes well the creep-recovery.•Diffusion of interstitial atoms contributes to the transient creep and recovery.•Dislocation generation/annihilation contributes to the transient creep and recovery.•Maxwell representation of nonlinear Burgers model is invalid for the creep-recovery.
To develop strong refractory high-entropy alloys for use at elevated temperatures as well as to overcome grain-boundary brittleness, an equimolar HfMoNbTaTiZr alloy was prepared, and a minor amount ...of boron (0.1 at.%) was added into the alloy. The microstructures of the alloys were characterized, and their macro-to-microscale mechanical properties were measured. The microstructural observations indicated that the matrices of both the alloys were composed of a body-centered cubic solid-solution structure, and the added boron induced the precipitation of hexagonal close-packed borides (most likely the (Hf, Zr)B2) at the grain boundaries. The modulus and hardness of differently oriented grains were about equivalent, suggesting a diminished anisotropy, and many small slips occurred on multiple {110} planes. While the hardness of the matrix was not increased, the intergranular precipitation of the borides markedly raised the hardness of the grain boundaries. Owing to the enhanced grain boundary cohesion, the work hardenability and ductility were effectively improved with the addition of boron.
•Novel evaluations of stability based on DFT for adlayer hydroxides are presented.•Galvanic corrosion on B2 matrix is due to the lower stability of adlayer hydroxide.•The quality of Cr rich hydroxide ...dominates the corrosion behavior around Ecorr.•The stable ipass is related to lower ksp values of Co(OH)3, Fe(OH)3, and Cr(OH)3.•The annealing enhances the uniformity and corrosion resistance of passive film.
This work investigates the corrosion mechanism of annealed equiatomic AlCoCrFeNi tri-phase alloy in 0.5 M H2SO4 aerated aqueous solution. Experimental results indicate that the B2 matrix is preferentially corroded away while grain-boundary FCC and labyrinth-like BCC endure, consistent with the tendency of formation energy for monolayer hydroxide on the (001) plane of three phases calculated by the first principle based on density function theory. Furthermore, the stable passive current density is related to lower ksp values of Co(OH)3, Fe(OH)3, and Cr(OH)3, while the annealing effect on enhancing corrosion resistance is owing to the more uniformity of passive hydroxide film.
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