Electrochemical study and application on rutin at chitosan/graphene films modified glassy carbon electrode

Graphene（G） was dispersed into 0.5% chitosan（Chit） solution,then the composite films were coated on glassy carbon electrode（GCE）,the electrochemical behavior of rutin on a Chit/G modified GCE was investigated and the electrochemical parameters of rutin were calculated.Rutin effectively accumulated on the Chit/G/GCE and caused a pair of redox peaks at around 408 mV and 482 mV（vs.SCE） in 0.1M phosphate buffer solution（pH 4.0）.Under optimized conditions,the anodic peak current was linear to the rutin concentration in the range of 5×107-1.04×105M.The regression equation was：y 9.9219x-0.0025,r=0.9958.The proposed method was successfully used for the determination of rutin content in tablet samples with satisfactory results.

A reference-grade genome of the xerophyte Ammopiptanthus mongolicus sheds light on its evolution history in legumes and droughttolerance mechanisms

Plants that grow in extreme environments represent unique sources of stress-resistance genes and mechanisms.Ammopiptanthus mongolicus(Leguminosae)is a xerophytic evergreen broadleaf shrub native to semi-arid and desert regions;however,its drought-tolerance mechanisms remain poorly understood.Here,we report the assembly of a reference-grade genome for A.mongolicus,describe its evolutionary history within the legume family,and examine its drought-tolerance mechanisms.The assembled genome is 843.07 Mb in length,with 98.7%of the sequences successfully anchored to the nine chromosomes of A.mongolicus.The genome is predicted to contain 47611 protein-coding genes,and 70.71%of the genome is composed of repetitive sequences;these are dominated by transposable elements,particularly longterminal-repeat retrotransposons.Evolutionary analyses revealed two whole-genome duplication(WGD)events at 130 and 58 million years ago(mya)that are shared by the genus Ammopiptanthus and other legumes,but no species-specific WGDs were found within this genus.Ancestral genome reconstruction revealed that the A.mongolicus genome has undergone fewer rearrangements than other genomes in the legume family,confirming its status as a"relict plant".Transcriptomic analyses demonstrated that genes involved in cuticular wax biosynthesis and transport are highly expressed,both under normal conditions and in response to polyethylene glycol-induced dehydration.Significant induction of genes related to ethylene biosynthesis and signaling was also observed in leaves under dehydration stress,suggesting that enhanced ethylene response and formation of thick waxy cuticles are two major mechanisms of drought tolerance in A.mongolicus.Ectopic expression of AmERF2,an ethylene response factor unique to A.mongolicus,can markedly increase the drought tolerance of transgenic Arabidopsis thaliana plants,demonstrating the potential for application of A.mongolicus genes in crop improvement.

Enhanced energy storage properties and good stability of novel(1-x)Na_(0.5)Bi_(0.5)TiO_(3)-xCa(Mg_(1/3)Nb_(2/3))O_(3) relaxor ferroelectric ceramics prepared by chemical modification

The increase in energy consumption and its collateral damage on the environment has encouraged the development of environment-friendly ceramic materials with good energy storage properties.In this work,(1-x)Na_(0.5)Bi_(0.5)TiO_(3)-xCa(Mg_(1/3)Nb_(2/3))O_(3) ceramics were synthesized by the solid-state reaction method.The 0.88Na_(0.5)Bi_(0.5)TiO_(3)-0.12Ca(Mg_(1/3)Nb_(2/3))O_(3) ceramic exhibited a high recoverable energy storage density of 8.1 J/cm3 and energy storage efficiency of 82.4% at 550 kV/cm.The introduction of Ca(Mg_(1/3)Nb_(2/3))O_(3) reduced the grain size and increased the band gap,thereby enhancing the breakdown field strength of the ceramic materials.The method also resulted in good temperature stability(20–140℃),frequency stability(1–200 Hz),and fatigue stability over 106 cycles.In addition,an ultrahigh power density of 187 MW/cm^(3) and a fast charge-discharge rate(t0.9=57.2 ns)can be obtained simultaneously.Finite element method analysis revealed that the decrease of grain size was beneficial to the increase of breakdown field strength.Therefore,the 0.88Na_(0.5)Bi_(0.5)TiO_(3)-0.12Ca(Mg_(1/3)Nb_(2/3))O_(3) ceramics resulted in high energy storage properties with good stability and were promising environment-friendly materials for advanced pulsed power systems applications.

高居里温度铋层状结构铌酸铋钙(CaBi_(2)Nb_(2)O_(9))压电陶瓷

压电材料是一类重要的功能材料,在国民经济的多个领域有着重要应用.在能源、航空航天、国防工业等高端技术领域,压电材料的应用已经从常规使用转向极端环境下的服役,这要求压电材料和压电传感器能够在更高的温度下工作.作为高温压电材料,Aurivillius型铋层状结构铁电体由于其特殊的层状结构和较高的居里温度(Tc)引起了研究人员的广泛关注.铌酸铋钙(CaBi_(2)Nb_(2)O_(9))是一种典型的铋层状结构铁电体.由于具有较高的居里温度(Tc~940℃),近年来铌酸铋钙作为高温压电传感器材料受到了广泛的关注.本文主要介绍高居里温度铌酸铋钙压电陶瓷的研究进展.通过组分优化,铌酸铋钙的压电性能可得到显著提高.研究发现,A位离子取代比B位离子取代更有助于提高铌酸铋钙的压电性能,同时A位离子和B位离子共取代能够显著提高铌酸铋钙的压电性能.模板晶粒生长、放电等离子体烧结等织构化技术可进一步提高铌酸铋钙的压电性能.最新研究显示,性能优化的铌酸铋钙压电陶瓷的压电系数d33可达20 pC/N,同时居里温度Tc高达900℃,铌酸铋钙陶瓷是适合于压电传感器应用的一类高温压电材料.本文最后对提高铌酸铋钙压电性能提出了展望.

Boosting energy storage performance of low-temperature sputtered CaBi_(2)Nb_(2)O_(9) thin film capacitors via rapid thermal annealing

CaBi_(2)Nb_(2)O_(9) thin film capacitors were fabricated on SrRuO_(3)-buffered Pt(111)/Ti/Si(100)substrates by adopting a two-step fabrication process.This process combines a low-temperature sputtering deposition with a rapid thermal annealing(RTA)to inhibit the grain growth,for the purposes of delaying the polarization saturation and reducing the ferroelectric hysteresis.By using this method,CaBi_(2)Nb_(2)O_(9) thin films with uniformly distributed nanograins were obtained,which display a large recyclable energy density Wrec≈69 J/cm^(3) and a high energy efficiencyη≈82.4%.A superior fatigue-resistance(negligible energy performance degradation after 10^(9) charge-discharge cycles)and a good thermal stability(from-170 to 150℃)have also been achieved.This two-step method can be used to prepare other bismuth layer-structured ferroelectric film capacitors with enhanced energy storage performances.

Genotyping the Heading Date of Male-Sterile Rice Line II-32A

II-32A, an elite male-sterile line of rice （Oryza sativa L.）, has been widely used for the production of hybrid rice seed In China. Heading date In most combinations using II-32A shows transgressive Inheritance or similarity to the latter parent, but the genotype of II-32A with respect to major genes for heading time Is unknown. This limits the further exploitation of this sterile line In breeding and hybrid seed production. Using a number of major gene heading date Isogenlc lines and heading date QTL near-lsogenic lines, we genetically analyzed II-32B under both long- and short-day conditions. We show that II-32B carries two photoperlod-sensltlve genes, E1 and E3, a recessive late-heading gene, ef-l, and a photoperlod-sensltlve allele, Se-1^u. In addition we Identified In II- 32B a recessive Inhibitor for E1 or Se-1^n and other modified photoperlod-sensltlve genes. The heading-date constitution of II-32A was determined to be E1e2E3Se-1^uef-li-Se-1.

Reoxidation process and corrosion behavior of TA15 alloy by laser ablation

The thermal oxide layer formed of TA15 alloy has poor corrosion resistance.In this paper,the changes of the elements and components on the surface after laser ablation with different energy densities(E) were researched.The formation process and corrosion behavior of laser-generated oxide layer were clarified.As E increases,the oxygen content decreases from 8.52% to 5.43% and then increases to 11.89%.The surface oxide layer changes from TiO_(2)(R)(i.e.,rutile) to Ti_(2) O_(3)+TiO_(2)(R) and finally becomes TiO_(2)(R)+TiO_(2)(A)(i.e.,anatase).The TiO_(2)(R) gasification was confirmed by calculating the surface temperature rise.The surface reoxidation process was illustrated by a thermodynamically calculated ΔGT(i.e.,the Gibbs free energy changes with temperature).When E≥17.5 J·cm^(-2),the oxide layer exhibits an agitated morphology,and oxide falls off at the bottom.As E increases,the corrosion rate decreases first and then increases.With energy density of 8.75 J·cm^(-2),the surface corrosion rate was 20.43 times slower than that of the untreated sample.The impedance spectrum and equivalent resistance results also prove the best corrosion resistance at 8.75 J·cm^(-2).The corrosion behavior of the oxide layer is analyzed from the properties of the oxide layer components and the reaction products with the electrolyte.

Hydrogenation behaviors and characteristics of bulk Ti-6Al-4V alloy at different isothermal temperatures

The bulk Ti-6Al-4V alloy was hydrogenated at the temperature range of 723-973 K,and the hydrogen absorption characteristics and hydrogen absorption kinetics were investigated.The results show that there are two types of hydrogen absorption characteristics at different temperatures.The hydrogen content decreases,and the time reaching reaction equilibrium is shorten with the isothermal hydrogenation temperature increasing.Meanwhile,the mechanism of the hydrogen absorption kinetics is different at different temperatures.The incubation period exists at the initial hydrogen absorption stage below 823 K,and K(a2)(the reaction rate constant of Stage 2)>>K(a1)(the reaction rate constant of Stage 1).And there is no incubation period over 823 K,K(a1)>>K(a2).

Effect of Water Deficit on Self-thinning Line in Spring Wheat （Triticum aestivum L.） Populations

Monocultures of spring wheat （Triticum aestivum L.） were grown at overcrowded densities （10 000 and 3 000 plants per m^2） under well-watered and water-stressed conditions to investigate the effects of water deficits on self-thinning. The results showed that density reduction in water-stressed populations was delayed compared with that In well-watered populations. Populations grown In well-watered conditions conformed to the -3/2- power law. Compared with the well-watered condition, there was no significant decrease of the self-thinning line under water-stressed conditions In this experiment, although the rate of average shoot blomass accumulatlon decreased. This result Implied that the exponent of the -3/2-power equation Is not as sensitive as the rate of average shoot blomass accumulation to water stress. Further analysis indicated that, In each density treatment, the lines of the height versus shoot blomass relationships did not differ significantly between the two water conditions. However, the Intercepts of the height versus shoot blomass relationships were greater In the higher-density populations （10 000/m^2） than those In the lower-density populations （3 000/m^2）. These results showed that water deficit did not change plant geometry In this experiment. That Is to say, shoot competition for light remains constant at a given blomass, although root competition for water becomes more serious In water deficit conditions. Based on these results and previous reports we propose that, to affect the thinning line slope, changes In symmetric competition are not as efficient as changes In asymmetric competition.

Reproductive Allocation Patterns in Different Density Populations of Spring Wheat

The effects of increased intraspecific competition on size hierarchies （size inequality） and reproductive allocation were investigated in populations of the annual plant, spring wheat （Triticurn aestivurn）. A series of densities （100, 300, 1 000, 3 000 and 10 000 plants/m^2） along a gradient of competition intensity were designed in this experiment. The results showed that average shoot biomass decreased with increased density. Reproductive allocation was negatively correlated to Gini coefficient （R^2 = 0.927）, which suggested that reproductive allocation is inclined to decrease as size inequality increases. These results suggest that both vegetative and reproductive structures were significantly affected by intensive competition. However, results also indicated that there were different relationships between plant size and reproductive allocation pattern in different densities. In the lowest density population, lacking competition （100 plants/m^2）, individual reproductive allocation was size independent but, in high density populations （300, 1 000, 3 000 and 10 000 plants/m^2）, where competition occurred, individual reproductive allocation was size dependent： the small proportion of larger individuals were winners in competition and got higher reproductive allocation （lower marginal reproductive allocation; MRA）, and the larger proportion of smaller individuals were suppressed and got lower reproductive allocation （higher MRA）. In conclusion, our results support the prediction that elevated intraspecific competition would result in higher levels of size inequality and decreased reproductive allocation （with a negative relationship between them）. However, deeper analysis indicated that these frequency- and size-dependent reproductive strategies were not evolutionarily stable strategies.

Effects of metallic microstructures on fatigue fracture of Q345 steel

Effects of high-frequency cyclic loading on the banded ferrite-pearlite steel were analyzed through crack initiation and propagation. Interfaces of ferrite and pearlite colony with a small angle deviation from the loading axis were verified to be the most potential sites to fabricate the microcracks caused by the high strain gradient. The initial crack extension inside ferrite grain was driven by shear stress in model II along the direction with a 45° angle to the loading axis. Banded pearlite colony and the high-angle grain boundaries were considered as the dominant factors that promote the fatigue resistance of the material through arousing crack deflection in short crack propagation range and crack branching in long crack propagation range to reduce the crack propagation driving force in the crack tip. P-S-N curves were used to quantify the dispersion of fatigue lifetimes and evaluate the effect of elevated volume content of pearlite colony on the fatigue performance of the material.