A Catalytic Copper/Cobalt Oxide Interface for Efficient Hydrogen Generation

Metal nanoparticles and metal oxides promisingly provide different catalytic active sites at their interfaces.Constructing high-density interfaces is essential to maximize synergies.Herein,a Cu-Co_(3)O_(4) nanoparticles interfacial structure produced via pyrolysis and moderate oxidation from metal-organic frameworks has been designed to boost the intrinsic activity.The Cu-Co_(3)O_(4) nanoparticles composites exhibit a turnover frequency of 57.5 min−1 for ammonia borane hydrolysis,far higher than those of monometallic Cu and Co_(3)O_(4) nanoparticles,showing the synergistic effect of Cu and Co_(3)O_(4) nanoparticles at their interface.Density functional theory calculations and in situ Raman spectroscopy reveal the catalytic mechanism of dual active sites,in which Co_(3)O_(4) nanoparticles at Cu-Co_(3)O_(4) interface efficiently bind and activate water molecules and Cu nanoparticles easily activate NH3BH3 molecules.This study opens up a new pathway for achieving high-efficiency noble metal-free catalysts for hydrogen generation and other heterogeneous catalysis.

Effects of the Solution Treatment on Microstructural Evolution, Mechanical Properties, and Fracture Mechanism of Nickel-Based GH4099 Superalloy

Grain growth, mechanical properties, and fracture mechanism of nickel-based GH4099 superalloy are investigated using heat treatments, tensile tests, optical microscopy (OM), and scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS). The OM observation shows that the matrix grains (γ-grains) undergo an apparent growth during the solution treatment. The grain size diameter increases from 100 to 174 μm when the solution temperature rises from 1100℃ to 1160℃ for 30 min. When the holding time increases from 15 to 60 min at 1140℃, the grain size diameter increases from 140 to 176 μm, indicating that the γ-grain growth is more sensitive to temperature than time. Standard deviation, Sv, and the grain size distribution are utilized to characterize the microstructural uniformity. To predict the grain size more accurately, we develop the grain growth kinetics and find that the growth index is close to 5. The yield strength (Rp0.2), tensile strength (Rm), and ductility (Af) are also measured. It is found that the effect decreases in the order cooling rate, solution temperature, time. Rp0.2 reduces by 47% with the increase in the cooling rate from 1℃ to 8000℃/min, while both strength and ductility exhibit little changes with time. The SEM results show that the fracture surfaces have typical mixed brittle and ductile characteristics when specimens are subjected to water quenching and air cooling. However, a complete brittle fracture occurs under furnace cooling conditions. The EDS analysis indicates that the brittle γ' (Ni3Ti) phase precipitates around the γ-grain boundary during the slow cooling process, which is the main factor yielding the complete brittle fracture. Finally, the optimal solution treatment scheme for the GH4099 superalloy is proposed—a temperature of 1140℃ for 30 min followed by air cooling.

GNP6,a novel allele of MOC1,regulates panicle and tiller development in rice

The yield of rice is mostly affected by three factors,namely,panicle number,grain number and grain weight.Variation in panicle and grain numbers is mainly caused by tiller and panicle branches generated from axillary meristems(AMs).MOC1 encodes a putative GRAS family nuclear protein that regulates AM formation.Although several alleles of MOC1 have been identified,its variation in germplasm resources remains unclear.In the present study we characterized a novel mocl allele named gnp6 which has a thymine insertion in the coding sequence of the SAW motif in the GRAS domain.This mutation causes arrested branch formation.The SAW motif is necessary for nuclear localization of GNP6/MOC1 where it functions as a transcription factor or co-regulator.Haplotype analysis showed that the coding region of GNP6/MOC1 was conserved without any non-synonymous mutations in 240 rice accessions.However,variation in the promoter region might affect the expression of it and its downstream genes.Joint haplotype analysis of GNP6/MOC1 and MOC3 showed that haplotype combinations H9,H10 and H11,namely MOC1-Hap1 in combination with MOC3-Hap3,MOC3-Hap4 or MOC3-Hap5 could be bred to promote branch formation.These findings will enrich the genetic resources available for rice breeders.

Genetic control of panicle architecture in rice

Rice panicle architecture affects grain number per panicle and thereby grain yield.Many genes involved in control of panicle architecture have been identified in the past decades.According to their effect on phenotype,these genes are divided into three categories:panicle branch and lateral spikelets,multifloret spikelets,and panicle type.We review these genes,describe their genetic regulatory network,and propose a strategy for using them in rice breeding.These findings on rice panicle architecture may facilitate related studies in other crops.

Natural variation in MORE GRAINS 1 regulates grain number and grain weight in rice

Grain yield is determined mainly by grain number and grain weight.In this study,we identified and characterized MORE GRAINS1(MOG1),a gene associated with grain number and grain weight in rice(Oryza sativa L.),through map-based cloning.Overexpression of MOG1 increased grain yield by 18.6%-22.3%under field conditions.We determined that MOG1,a bHLH transcription factor,interacts with OsbHLH107 and directly activates the expression of LONELY GUY(LOG),which encodes a cytokinin-activating enzyme and the cell expansion gene EXPANSIN-LIKE1(EXPLA1),positively regulating grain number per panicle and grain weight.Natural variations in the promoter and coding regions of MOG1 between Hap-LNW and Hap-HNW alleles resulted in changes in MOG1 expression level and transcriptional activation,leading to functional differences.Haplotype analysis revealed that Hap-HNW,which results in a greater number and heavier grains,has undergone strong selection but has been poorly utilized in modern lowland rice breeding.In summary,the MOG1-OsbHLH107 complex activates LOG and EXPLA1 expression to promote cell expansion and division of young panicles through the cytokinin pathway,thereby increasing grain number and grain weight.These findings suggest that Hap-HNW could be used in strategies to breed high-yielding temperate japonica lowland rice.

First-principles study of the relationship between the formation of single atom catalysts and lattice thermal conductivity

Single atom catalysts(SACs)have been in the forefront of catalysts research because of their high efficiency and low cost and provide new ideas for development of renewable energy conversion and storage technologies.However,the relationship between the intrinsic properties of materials such as lattice thermal conductivity and catalysis remains to be explored.In this work,the lattice thermal conductivity of BN and graphene was calculated by Sheng BTE.In addition,the adsorption properties of 3d-TM(TM=V,Cr,Mn,Fe,Co,Ni)on BN and graphene were investigated using first-principles methods,and it was found that Ni atom can form relatively stable SACs compared to other TMs.The molecular dynamics(MD)simulation and migration barrier of Ni loaded on BN and graphene were calculated.Our study found that graphene has higher thermal conductivity and is easier to form SACs than BN,but the SACs formed on BN surface have higher thermodynamic stability.

Variations in OsSPL10 confer drought tolerance by directly regulating OsNAC2 expression and ROS production in rice

Drought is a major factor restricting the production of rice(Oryza sativa L.).The identification of natural variants for drought stress-related genes is an important step toward developing genetically improved rice varieties.Here,we characterized a member of the SQUAMOSA PROMOTER BINDING PROTEIN-LIKE(SPL)family,OsSPL10,as a transcription factor involved in the regulation of drought tolerance in rice.OsSPL10 appears to play a vital role in drought tolerance by controlling reactive oxygen species(ROS)production and stomatal movements.Haplotype and allele frequency analyses of OsSPL10 indicated that most upland rice and improved lowland rice varieties harbor the OsSPL10Hap1allele,whereas the OsSPL10Hap2allele was mainly present in lowland and landrace rice varieties.Importantly,we demonstrated that the varieties with the OsSPL10Hap1allele showed low expression levels of OsSPL10 and its downstream gene,OsNAC2,which decreases the expression of OsAP37 and increases the expression of OsCOX11,thus preventing ROS accumulation and programmed cell death(PCD).Furthermore,the knockdown or knockout of OsSPL10 induced fast stomatal closure and prevented water loss,thereby improving drought tolerance in rice.Based on these observations,we propose that OsSPL10 confers drought tolerance by regulating OsNAC2 expression and that OsSPL10Hap1could be a valuable haplotype for the genetic improvement of drought tolerance in rice.

Core-shell TiO_(2)/ZnO nanorod array films on FTO:Two-step synthesis and improved ethanol sensing performance

In this work,highly regular TiO_(2)nanorod array films were synthesized in situ on FTO by a facile hydrothermal method,and then ZnO shell layers were grown on the surface of the nanorods to form a coreshell structure via an ion-layer adsorption-reaction way.Compared to the TiO_(2)nanorods,the prepared TiO_(2)/ZnO nanocomposites exhibited enhanced ethanol sensing performances,including a low working temperature,higher sensitivity,and faster response capability.The optimum sensor based on 2c-TiO_(2)/ZnO exhibited the maximum response value of 30.85 toward 50×10^(-6)C_(2)H_(5)OH at 340℃,which was almost 4.15 times higher than that of the TiO_(2)sensor.The improved ethanol sensing mechanism was discussed in relation to the unique nanorod array structure and the heterojunctions between TiO_(2)and ZnO.

Natural Variation in OsPRR37 Regulates Heading Date and Contributes to Rice Cultivation at a Wide Range of Latitudes

Heading date and photoperiod sensitivity are fundamental traits that determine rice adaptation to a wide range of geographic environments. By quantitative trait locus （QTL） mapping and candidate gene analysis using whole- genome re-sequencing, we found that Oryza sativa Pseudo-Response Regulator37 （OsPRR37; hereafter PRR37） is respon- sible for the Early heading7-2 （EH7-2）/Heading date2 （Hd2） QTL which was identified from a cross of late-heading rice ＇Milyang23 （M23）＇ and early-heading rice ＇H143＇. H143 contains a missense mutation of an invariantly conserved amino acid in the CCT （CONSTANS, CO-like, and TOC1） domain of PRR37 protein. In the world rice collection, different types of nonfunctional PRR37 alleles were found in many European and Asian rice cultivars. Notably, the japonica varieties harboring nonfunctional alleles of both Ghd7/Hd4 and PRR37/Hd2 flower extremely early under natural long-day condi- tions, and are adapted to the northernmost regions of rice cultivation, up to 53~ N latitude. Genetic analysis revealed that the effects of PRR37 and Ghd7 alleles on heading date are additive, and PRR37 down-regulates Hd3a expression to suppress flowering under long-day conditions. Our results demonstrate that natural variations in PRR37/Hd2 and GhdT/ Hd4 have contributed to the expansion of rice cultivation to temperate and cooler regions.

Rice SPL10 positively regulates trichome development through expression of HL6 and auxin-related genes

Trichomes function in plant defenses against biotic and abiotic stresses;examination of glabrous lines,which lack trichomes,has revealed key aspects of trichome development and function.Tests of allelism in 51 glabrous rice(Oryza sativa)accessions collected worldwide identified OsSPL10 and OsWOX3B as regulators of trichome development in rice.Here,we report that OsSPL10 acts as a transcriptional regulator controlling trichome development.Haplotype and transient expression analyses revealed that variation in the approximately 700-bp OsSPL10 promoter region is the primary cause of the glabrous phenotype in the indica cultivar WD-17993.Disruption of OsSPL10 by genome editing decreased leaf trichome density and length in the NIL-HL6 background.Plants with genotype OsSPL10^(WD-17993)/HL6 generated by crossing WD-17993 with NIL-HL6 also had fewer trichomes in the glumes.HAIRY LEAF6(HL6)encodes another transcription factor that regulates trichome initiation and elongation,and OsSPL10 directly binds to the HL6 promoter to regulate its expression.Moreover,the transcript levels of auxin-related genes,such as OsYUCCA5 and OsPIN-FORMED1b,were altered in OsSPL10 overexpression and RNAi transgenic lines.Feeding tests using locusts(Locusta migratoria)demonstrated that non-glandular trichomes affect feeding by this herbivore.Our findings provide a molecular framework for trichome development and an ecological perspective on trichome functions.

Improved triethylamine sensing properties of fish-scale-like porous SnO_(2) nanosheets by decorating with Ag nanoparticles

Three dimensional(3D)porous nanostructures assembled by low-dimensional nanomaterials are widely applied in gas sensor according to porous structure which can facilitate the transport of gas molecules.In this work,fish-scale-like porous SnO 2 nanomaterials assembled from ultrathin nanosheets with thick-ness of 16.8 nm were synthesized by a facile hydrothermal route.Then Ag nanoparticles were decorated on the surface of SnO_(2) nanosheets via one-step method to improve their gas-sensing performances.The sensing properties of pristine SnO_(2) and Ag/SnO_(2) nanosheets were investigated intensively.After deco-rating with Ag nanoparticles,the characteristics of SnO_(2) based sensor for triethylamine detection were significantly improved.Especially,the Ag/SnO_(2) based sensor with Ag content of 2 at%exhibited the highest triethylamine sensing sensitivity at optimum work temperature of 170?C.The improved sensing properties of Ag/SnO_(2) sensors were attributed to the sensitizing actions of Ag nanoparticles as well as the unique hierarchical porous architecture.

A periodic DFT study on adsorption of small molecules(CH4,CO,H2O,H2S,NH3)on the WO3(001) surface-supported Au

Gas molecules(such as CH4,CO,H2O,H2S,NH_3)adsorption on the pure and Au-doped WO3(001)surface have been studied by Density functional theory calculations with generalized gradient approximation.Based on the the calculation of adsorption energy,we found the most stable adsorption site for gas molecules by comparing the adsorption energies of different gas molecules on the WO3(001)surface.We have also compared the adsorption energy of five different gas molecules on the WO3(001)surface,our calculation results show that when the five kinds of gases are adsorbed on the pure WO3(001)surface,the order of the surface adsorption energy is CO>H2S>CH4>H2O>NH3.And the results show that NH3 is the most easily adsorbed gas among the other four gases adsorbed on the surface of pure WO3(001)surface.We also calculated the five different gases on the Au-doped WO3(001)surface.The order of adsorption energy was found to be different from the previous calculation:CO>CH4>H2S>H2O>NH3.These results provide a new route for the potential applications of Au-doped WO3 in gas molecules adsorption.

Dual-selective detection of CO and CH_(4) based on hierarchical porous In_(2)O_(3) nanoflowers with Pd modification

The timely and effective detection of CO and CH_(4) is critical as the explosion and poisoning of them can bring serious potential risks to coal mining.In this study,combining metal oxide semiconductors with noble metals offers a promising route to achieve this target.Hierarchical porous Pd modified In_(2)O_(3) nanoflowers were prepared via two-step hydrothermal method and exhibited dual detection of CO and CH_(4) at different temperatures.The material has been characterized by a number of advanced techniques and the results indicate that Pd modified In_(2)O_(3) are hierarchical porous nanoflowers structure consisting of pores of approximately 1.8 nm in size.The sensing properties results show that the Pd modified In_(2)O_(3) based sensor exhibits temperature-dependent dual selectivity detection of CO at 280℃ and CH_(4) at 340℃.In addition,the Pd modified In_(2)O_(3) sensor display higher sensing response of CO(5.824 for 100 ppm)and CH_(4)(1.162 for 1000 ppm),fast response and recovery time,as well as good repeatability,which demonstrating the great potential for practical application.Such good gas-sensing performance are mainly attributed to the unique flower-like structure,the presence of porosity on the sample surface,and the catalytic effect of Pd.

The rapid detection for methane of ZnO porous nanoflakes with the decoration of Ag nanoparticles

Realizing the real-time detection of CH4 is important for the safety of human life.A facile hydrothermal method was used to synthesize Ag nanoparticlesdecorated ZnO porous nanoflakes(PNFs)in this study.The characterization results confirmed that Ag nanoparticles had been decorated in ZnO nanoflakes with the thickness of~10 nm.The gas-sensing properties of Ag-decorated ZnO nanoflakes were also investigated.While the gas-sensing performances of ZnO were remarkably improved by decorating Ag nanoparticles on the surface of ZnO nanoflakes,the response of the Agdecorated ZnO sensor to 3000 ppm CH4 is almost 1.3 times as high as that of pristine ZnO sensor.The obtained Ag/ZnO sensor exhibits better long-term stability and shorter response recovery time(5/38 s)in the comparison with pristine ZnO,demonstrating the possibility for the actual detection of CH4.The enhanced CH4 sensing performance can be attributed to the synergism between the unique hierarchical porous structure and the sensitizing actions utilized by the Ag nanoparticles.

Construction of hierarchical In_(2)O_(3)/In_(2)S_(3) microsphere heterostructures for TEA detection

Construction of heterojunction has been considered as an efficient strategy to enhance the gas-sensing performances of metal oxide semiconductors.On this basis,hierarchical In_(2)O_(3)/In_(2)S_(3) microsphere heterostructures were synthesized by partial oxidation of In_(2)S_(3) precursors which were obtained via a facile hydrothermal method.Besides,gas sensors based on the acquired materials were fabricated to investigate their sensing performances toward triethylamine(TEA).The results reveal that the gas sensor based on In_(2)O_(3)/In_(2)S_(3) exhibits a high response of 37 at 300℃ toward 0.45 mg/L TEA,which is 3.7 times higher than that of bare In_(2)O_(3).Meanwhile,it also possesses fast response/recovery time(19 s/154 s),good repeatability,selectivity and long-term stability.The excellent sensing performances toward TEA are mainly attributed to the massive oxygen vacancy defects and heterojunction formed between In_(2)O_(3) and In_(2)S_(3).This work provides a facile temperature-dependent route to controllably synthesize hierarchical In_(2)O_(3)/In_(2)S_(3) microsphere heterostructures,and the In_(2)O_(3)/In_(2)S_(3) sensor shows great application prospects in TEA detection.