Direct methanol fuel cells （DMFCs） are very promising power source for stationary and portable miniatureelectric appliances due to its high efficiency and low emissions of pollutants. As the key material, cata-lysts...Direct methanol fuel cells （DMFCs） are very promising power source for stationary and portable miniatureelectric appliances due to its high efficiency and low emissions of pollutants. As the key material, cata-lysts for both cathode and anode face several problems which hinder the commercialization of DMFCs.In this review, we mainly focus on anode catalysts of DMFCs. The process and mechanism of methanolelectrooxidation on Pt and Pt-based catalysts in acidic medium have been introduced. The influences ofsize effect and morphology on electrocatalytic activity are discussed though whether there is a size effectin MOP, catalyst is under debate. Besides, the non Pt catalysts are also listed to emphasize though Pt isstill deemed as the indispensable element in anode catalyst of DMFCs in acidic medium. Different cata-lyst systems are compared to illustrate the level of research at present. ome debates need to be verifiedwith experimental evidences.展开更多
Oligopeptide transporters(OPTs) encode integral membrane-localized proteins and have a broad range of substrate transport capabilities. Here, 28 BrrOPT genes were identified in the turnip. Phylogenetic analyses reveal...Oligopeptide transporters(OPTs) encode integral membrane-localized proteins and have a broad range of substrate transport capabilities. Here, 28 BrrOPT genes were identified in the turnip. Phylogenetic analyses revealed two well-supported clades in the OPT family, containing 15 BrrOPTs and 13 BrrYSLs.The exon/intron structure of OPT clade are conserved but the yellow stripe-like(YSL) clade was different.The exon/intron of the YSL clade possesses structural differences, whereas the YSL class motifs structure are conserved. The OPT genes are distributed unevenly among the chromosomes of the turnip genome.Phylogenetic and chromosomal distribution analyses revealed that the expansion of the OPT gene family is mainly attributable to segmental duplication. For the expression profiles at different developmental stages, a comprehensive analysis provided insights into the possible functional divergence among members of the paralog OPT gene family. Different expression levels under a variety of ion deficiencies also indicated that the OPT family underwent functional divergence during long-term evolution.Furthermore. BrrOPT8.1, BrrYSL1.2, BrrYSL1.3, BrrYSL6 and BrrYSL9 responded to Fe(Ⅱ) treatments and BrrYSL7 responded to calcium treatments, BrrYSL6 responded to multiple treatments in root, suggesting that turnip OPTs may be involved in mediating cross-talk among different ion deficiencies. Our data provide important information for further functional dissection of BrrOPTs, especially in transporting metal ions and nutrient deficiency stress adaptation.展开更多
With reduced dehydrogenation enthalpy change and reduced dehydrogenation temperature compared with its phenol-cyclohexanol pair,sodium phenoxide-cyclohexanolate pair developed recently is promising for large-scale ene...With reduced dehydrogenation enthalpy change and reduced dehydrogenation temperature compared with its phenol-cyclohexanol pair,sodium phenoxide-cyclohexanolate pair developed recently is promising for large-scale energy storage and long-distance hydrogen transportation.In the present work,we investigate the kinetic behavior of the pair in the hydrogenation and dehydrogenation in water over three commercial catalysts.It is shown that 5%Ru/Al2O3 and 5%Pt/C perform well in the hydrogenation and dehydrogenation,respectively.Kinetic analyses show that the hydrogenation of sodium phenoxide is of first-order with respect to H2 pressure and zero-order to the concentration of sodium phenoxide in the presence of Ru/Al2O3 catalyst.>99%conversion of cyclohexanol and>99%selectivity to phenoxide can be achieved in the dehydrogenation catalyzed by Pt/C catalyst and in the presence of Na OH at 100℃,where cyclohexanone was observed as an intermediate.According to the kinetic analysis,the hydrogenation of sodium phenoxide may undergo the hydrolysis and hydrogenation pathway.For the dehydrogenation,an intermediate,i.e.,cyclohexanone,was detected and two possible pathways are proposed accordingly.展开更多
Poly(arylene ether ketone)s with carboxylic groups(PAEK-COOH)is a good membrane fabrication material,a kind of polyacids,while polyethylenimine(PEI)is a weak organic base,a kind of polybases.Those polyacids and polyba...Poly(arylene ether ketone)s with carboxylic groups(PAEK-COOH)is a good membrane fabrication material,a kind of polyacids,while polyethylenimine(PEI)is a weak organic base,a kind of polybases.Those polyacids and polybases would form ionic complexation at the interface of two liquid phases.In this paper,PAEK-COOH/N-methyl pyrrolidone(NMP)/1,4-dioxane(DO)mixture,employed as polymer casting solution and aqueous solution of PEI,used as coagulation bath,respectively.Then ion complexation induced phase inversion process is applied to prepare positively charged nanofiltration membrane with thinner but denser separation skin layer.The complexing reaction at the interface of two liquid phases has great influence on the kinetic aspects of phase inversion process,which in accordance would affect the morphology and performance of the membrane.The obtained membrane,fabricated via the ion complexation induced phase inversion method,is positively charged,has high water permeability,and possesses high rejection towards divalent cations,such as Mg^(2+),Ca^(2+),Pb^(2+)etc.,which could be used for removal of heavy metals from polluted water.At the optimal condition,the pure water flux of the PAEK-COOH-PEI nanofiltration membrane is 24.3 L·m^(-2)·h^(-1),with MgCl_2rejection of 92.2%.展开更多
On-spot observation and field reconnaissance of debris flows have revealed that inflexion points in the longitudinal profile of a movable channel may easily become unstable points that significantly affect their entra...On-spot observation and field reconnaissance of debris flows have revealed that inflexion points in the longitudinal profile of a movable channel may easily become unstable points that significantly affect their entrainment behavior.In this study,small-scale flume experiments were performed to investigate the entrainment characteristics of debris flows over two types of inflexion points,namely,a convex point,which has an upslope gradient that is less than the downslope gradient,and a concave point,which has an upslope gradient that is greater than the downslope gradient.It was observed that when debris flowed over a convex point,the entrainment developed gradually and progressively from the convex point in the downstream direction,and the primary control factors were the slope gradient and friction angle.Conversely,when debris flowed over a concave point,the entrainment was characterized by impacting and impinging erosion rather than traditional hydraulic erosion,and the impingement angle of the flow significantly determined the maximum erosion depth and outflow exit angle.An empirical relationship between the topography change and the control factors was obtained from the experimental data.展开更多
Eurya has an excellent fossil record in Europe, but it has only a few fossil occurrences in East Asia though this vast area houses the highest modern diversity of the genus. In this study, three-dimensionally preserve...Eurya has an excellent fossil record in Europe, but it has only a few fossil occurrences in East Asia though this vast area houses the highest modern diversity of the genus. In this study, three-dimensionally preserved fossil seeds of Eurya stigrnosa （Ludwig） Mai from the late Pliocene of northwestern Yunnan, southwestern China are described. The seeds are compressed and flattened, slightly campylotropous, and nearly circular to slightly angular in shape. The surface of the seeds is sculptured by a distinctive foveolate pattern, consisting of funnel-shaped and finely pitted cells. Each seed valve contains a reniform or horseshoe-shaped embryo cavity, a characteristic condyle structure and an internal raphe. These fossil seeds represent one of the few fossil records of Eurya in East Asia. This new finding therefore largely extends the distributional ranges of Eurya during Neogene. Fossil records summarized here show that Eurya persisted in Europe until the early Pleistocene, but disappeared thereafter. The genus might have first appeared in East Asia no later than the late Oligocene, and dispersed widely in regions such as Japan, Nepal, and southwestern China.展开更多
Previous studies revealed that the error of pole coordinate prediction will significantly increase for a prediction period longer than 100 days, and this is mainly caused by short period oscillations. Empirical mode d...Previous studies revealed that the error of pole coordinate prediction will significantly increase for a prediction period longer than 100 days, and this is mainly caused by short period oscillations. Empirical mode decomposition （EMD）, which is increasingly popular and has advantages over classical wavelet decomposition, can be used to remove short period variations from observed time series of pole co- ordinates. A hybrid model combing EMD and extreme learning machine （ELM）, where high frequency signals are removed and processed time series is then modeled and predicted, is summarized in this paper. The prediction performance of the hybrid model is compared with that of the ELM-only method created from original time series. The results show that the proposed hybrid model outperforms the pure ELM method for both short-term and long-term prediction of pole coordinates. The improvement of prediction accuracy up to 360 days in the future is found to be 24.91% and 26.79% on average in terms of mean absolute error （MAE） for the xp and yp components of pole coordinates, respectively.展开更多
Glandular trichomes of plants produce a wide variety of secondary metabolites which are considered as major defensive chemicals. The capitate glandular trichomes of Oenothera glazioviana(Onagraceae) were collected wit...Glandular trichomes of plants produce a wide variety of secondary metabolites which are considered as major defensive chemicals. The capitate glandular trichomes of Oenothera glazioviana(Onagraceae) were collected with laser microdissection and analyzed by gas chromatography-mass spectrometry. The volatile compound 4-hydroxy-4-methylpentan-2-one(1) was identified. We found that compound 1 displays antimicrobial, insecticidal, and phytotoxic activities. These results suggest that compound 1 might function as a defensive compound in the capitate glandular trichomes of O. glazioviana against pathogens, insect herbivores, and presumably competitive plants as well.展开更多
In the present paper, multi-walled carbon nanotubes（MWCNTs） are successfully assembled on graphite felt（GF） using sucrose pyrolysis method for the first time. The in situ formed pyrolytic carbon is chosen as the b...In the present paper, multi-walled carbon nanotubes（MWCNTs） are successfully assembled on graphite felt（GF） using sucrose pyrolysis method for the first time. The in situ formed pyrolytic carbon is chosen as the binder because it is essentially carbon materials as well as CNTs and GF which has a natural tendency to achieve high bonding strength and low contact resistance. The MWCNTs/GF electrode is demonstrated to increase surface area, reduce polarization, lower charge transfer resistance and improve energy conversion efficiency comparing with GF. This excellent electrochemical performance is mainly ascribed to the high electro-catalytic activity of MWCNTs and increasing surface area.展开更多
Flexible supercapacitors are promising energy storage devices in wearable smart electronics. Exploring cost-efficient electrodes with high capacitance would promote the wide-scale application of such capacitors. Herei...Flexible supercapacitors are promising energy storage devices in wearable smart electronics. Exploring cost-efficient electrodes with high capacitance would promote the wide-scale application of such capacitors. Herein, in order to explore a methodology for preparing low cost, flexible, tough, and up-scalable supercapacitor electrodes, silk textile is directly carbonized to make a conductive free-standing textile substrate. Through mildly baking the surfactant-free TiCTflakes suspension loaded on the carbonized silk cloth, a uniform and adhesive coating consisting of nanometer-thick TiCTflakes is well established on the conductive fabric support, forming a MXene-coated flexible textile electrode. The fabricated electrode exhibits a high areal capacitance of 362 m F/cm~2 with excellent cyclability and flexibility. Moreover,capacitance changes neglegibly under the bending deformation mode. This study elucidates the feasibility of using silk-derived carbon cloth from biomss for MXene-based flexible supercapacitor.展开更多
Recently, binary metal oxides have been considerably researched for energy storage since it can provide higher electrical conductivity and electrochemical activity than single components. Besides, rational arrays stru...Recently, binary metal oxides have been considerably researched for energy storage since it can provide higher electrical conductivity and electrochemical activity than single components. Besides, rational arrays structure design can effectively enhance the utilization of active material. In this article, we synthesis a porous NiCo_2O_4 nanowires arrays, which were intimate contact with flexible carbon cloth（CC）by a facile hydrothermal reaction and calcination treatment. The rational array structures of NiCo_2O_4 facilitate the diffusion of electrolyte and effectively increase the utilization of active material. The asobtained NiCo_2O_4@CC electrode exhibits a high capacitance of 1183 mF cm^（-2） and an outstanding capacitance retention of 90.4% after 3000 cycles. Furthermore, a flexible asymmetric supercapacitor（ASC）using NiCo_2O_4@CC as positive electrode and activated carbon cloth（ACC） as negative electrode was fabricated, which delivers a large capacitance of 750 mF cm^（-2）（12.5 F cm^（-3））, a high energy density of 0.24 mWh cm^（-2）（3.91 mWh cm^（-3））, as well as excellent cycle stability under different bending states.These remarkable results suggest that as-assembled NiCo_2O_4@CC//ACC ASC is a promising candidate in flexible energy storage applications.展开更多
The main mission of the process industries is to process resourc-es and energies into a form that can be utilized in other industriesand throughout society. In this sense, process industries cover a vastterritory, enc...The main mission of the process industries is to process resourc-es and energies into a form that can be utilized in other industriesand throughout society. In this sense, process industries cover a vastterritory, encompassing the chemical/biochemical, material, mining,metallurgical, power, food, and even pharmaceutical industries; inaddition, they are closely related to mechanical, civil, electrical, andelectronic industries, as well as to emerging fields such as biotech-nology, nanotechnology, and information technologies.展开更多
The Ni-based K417G superalloy is extensively applied as aeroengine components for its low cost and good mid-temperature （600-900 ~C） properties. Since used in as-cast state, the comprehensive under-standing on its m...The Ni-based K417G superalloy is extensively applied as aeroengine components for its low cost and good mid-temperature （600-900 ~C） properties. Since used in as-cast state, the comprehensive under-standing on its mechanical properties and microstructure evolution is necessary. In the present research, the tensile, creep behavior and microstructure evolution of the as-cast K417G superalloy under differ-ent conditions were investigated. The results exhibit that tensile cracks tend to initiate at MC carbide and γ＇/γ＇ eutectic structure and then propagate along grain boundary. As the temperature for tensile tests increases from 21 ℃ to 700 ℃, the yield strength and ultimate tensile strength of K417G superalloy decreases slightly, while the elongation to failure decreases greatly because of the intermediate tem- perature embrittlement. When the temperature rises to 900 ℃, the yield strength and ultimate tensile strength would decrease significantly. The creep deformation mechanism varies under different test-ing conditions. At 760 ℃/645 MPa, the creep cracks initiate at MC carbides and γ/γ＇ eutectic structures, and propagate transgranularly. While at 900℃/315 MPa and 950℃/235 MPa, the creep cracks initiate at grain boundary and propagate intergranularly. As the creep condition changes from 760 ℃/645 MPa to 900 ℃/315 MPa and 950 ℃/235 MPa, the γ＇ phase starts to raft, which reduces the creep deformation resistance and increases the steady-state deformation rate.展开更多
Based on the field measurements in Barrow, Alaska within the period of April-May 2015, we investigate the sources and variations of elemental carbon(EC) and organic carbon(OC) in the surface layer of snowpack on sea i...Based on the field measurements in Barrow, Alaska within the period of April-May 2015, we investigate the sources and variations of elemental carbon(EC) and organic carbon(OC) in the surface layer of snowpack on sea ice, and estimate their effects on the sea ice albedo. Results show that the snow OC in Barrow are from natural sources(e.g. terrestrial higher plants and micro-organisms) mainly, as well as biomass burning(e.g. forest fires and straw combustion) as an important part. Both EC and OC can accumulate at the snow surface with snow melt. The variations in EC and OC and liquid water content in the snow layer are well consistent during the snow-melting period. A higher rate of snow melt implied a more efficient enrichment of EC and OC. In the last phase of snow melt, the concentration increased to a maximum of 16.2 ng/g for EC and 128 ng/g for OC, which is ~10 times larger than those before snow melt onset. Except for the dominant influence of melt amplification mechanism, the variation in concentrations of EC and OC could be disturbed by the air temperature fluctuation and snowfall. Our study indicates that the lightabsorbing impurities contributed 1.6%-5.1% to the reduction in sea ice albedo with melt during the measurement period. The significant period oflight-absorbing impurities influencing on sea ice albedo begins with the rapid melting of overlying snow and ends before the melt ponds formed widely, which lasted for about 10 days in Barrow, 2015.展开更多
Two new compounds, namely taenialactam C and globorin A（1 and 2）, as well as six known compounds,cornoside（3）, 2-phenylethyl-b-D-glucoside（4）, 3-isopropyl-5-acetoxycyclohexene-2-one-1（5）, 4-methyl-phenol（6）,...Two new compounds, namely taenialactam C and globorin A（1 and 2）, as well as six known compounds,cornoside（3）, 2-phenylethyl-b-D-glucoside（4）, 3-isopropyl-5-acetoxycyclohexene-2-one-1（5）, 4-methyl-phenol（6）, 5-[（2S）-2-aminobutyl]-2-methyl-phenol（7）, and 1-（4-methylphenyl）-1-propanone（8） were isolated from wild Phaeocystis globosa. The structures of the new compounds were established by detailed spectroscopic analysis and by comparison with spectral data of related known compounds.The structures of the known compounds were identified by comparing their spectroscopic data with those reported in the literature. This paper also reports toxicity properties of the eight compounds against the brine shrimp Artemia salina and juvenile Epinephelus akaara fish. Some of these compounds showed significant lethality on the brine shrimp A. salina and the juvenile E. akaara fish.展开更多
Nine heterogeneous reactions （uptake of H2O2, HNO3, HO2, N2O5, NO2, NO3, O3, OH and SO2 on mineral aerosol surfaces） are incorporated into a Regional Air Quality Model System （RAQMS） to investigate their impacts o...Nine heterogeneous reactions （uptake of H2O2, HNO3, HO2, N2O5, NO2, NO3, O3, OH and SO2 on mineral aerosol surfaces） are incorporated into a Regional Air Quality Model System （RAQMS） to investigate their impacts on tropospheric chemistry in East Asia during the dust storm period in March 2006. Comparison with observations shows the model system well represents the behaviors of the gaseous and aerosol species. Most of the reaction probability γvalues used for this study are the best estimation specifically for dust samples from deserts of China, derived from analysis of a number of recent laboratory studies. There are large variations in gas and aerosol concentrations while taking heterogeneous reactions on mineral aerosol surface into account, especially during dust storm events. The domain-averaged monthly mean percentage changes in SO2, NO2, O3, HNO3, NH3, total sulfate, total nitrate and total ammonium concentrations are -4.4%, -3.8%, -2.1%, -22.0%, 12.7%, 6.6%, 26.1%, and -9.5%, respectively below 3 km. These changes indicate the considerable perturbation of heterogeneous reactions on mineral aerosol surface to tropospheric chemical system and components. The strength of heterogeneous reactions is determined by both reaction probability and gas precursor concentration. Among the nine reactions, dust uptakes of HNO3, SO2, and N2O5 exert relatively large influences on the other chemical components, whereas the reactions regarding H2O2, HO2, and OH have little impacts.展开更多
The Tibetan Plateau is home to the largest aggregate of glaciers outside the Polar Regions and is a source of fresh water to 1.4 billion people. Yet little is known about the transportation and cycling of Hg in high-e...The Tibetan Plateau is home to the largest aggregate of glaciers outside the Polar Regions and is a source of fresh water to 1.4 billion people. Yet little is known about the transportation and cycling of Hg in high-elevation glacier basins on Tibetan Plateau. In this study, surface snow,glacier melting stream water and lake water samples were collected from the Qiangyong Glacier Basin. The spatiotemporal distribution and transportation of Hg from glacier to lake were investigated. Significant diurnal variations of dissolved Hg（DHg） concentrations were observed in the river water, with low concentrations in the morning（8：00 am–14：00 pm） and high concentrations in the afternoon（16：00 pm–20：00 pm）. The DHg concentrations were exponentially correlated with runoff, which indicated that runoff was the dominant factor affecting DHg concentrations in the river water. Moreover, significant decreases of Hg were observed during transportation from glacier to lake. DHg adsorption onto particulates followed by the sedimentation of particulate-bound Hg（PHg） could be possible as an important Hg removal mechanism during the transportation process. Significant decreases in Hg concentrations were observed downstream of Xiao Qiangyong Lake, which indicated that the high-elevation lake system could significantly affect the distribution and transportation of Hg in the Qiangyong Glacier Basin.展开更多
We suggest a new family of Co[Ni-based materials that may host unconventional high temperature superconductivity （high-To）. These materials carry layered square lattices with each layer being formed by vertex-shared...We suggest a new family of Co[Ni-based materials that may host unconventional high temperature superconductivity （high-To）. These materials carry layered square lattices with each layer being formed by vertex-shared transition metal tetrahedra cation-anion complexes. The electronic physics in these materials is determined by the two dimensional layer and is fully attributed to the three near degenerated t2g d-orbitals close to a d7 filling configuration in the d-shell of CoJNi atoms. The electronic structure meets the necessary criteria for unconventional high Tc materials proposed recently by us to unify the two known high-Tc families, cuprates and iron-based superconductors. We predict that they host superconducting states with a d-wave pairing symmetry with Tc potentially higher than those of iron-based superconductors. These materials, if realized, can be a fertile new ground to study strongly correlated electronic Physics and provide decisive evidence for superconducting pairing mechanism.展开更多
In this study, the flow characteristics of Geldart A particles in a bobbling fluidized bed with and without perforated plates were simulated by the multiphase particle-in-cell （MP-PlC）-based Eolerian-Lagrangian meth...In this study, the flow characteristics of Geldart A particles in a bobbling fluidized bed with and without perforated plates were simulated by the multiphase particle-in-cell （MP-PlC）-based Eolerian-Lagrangian method. A modified structure-based drag model was developed based on our previous work. Other drag models including the Parker and Wen-Yo-Ergon drag models were also employed to investigate the effects of drag models on the simulation results. Although the modified structure-based drag model better predicts the gas-solid flow dynamics of a baffle-free bubbling fluidized bed in comparison with the experimental data, none of these drag models predict the gas-solid flow in a baffled bobbling floidized bed sufficiently well because of the treatment of baffles in the Barracuda software. To improve the simulation accuracy, future versions of Barracuda should address the challenges of incorporating the bed height and the baffles.展开更多
La Ni3.8Al1.0Mn0.2 alloy was prepared by vacuum induction melting and melt-spinning.The effects of different preparation techniques of the as-cast,cast then annealed,as-spun and spun then annealed alloys on the micros...La Ni3.8Al1.0Mn0.2 alloy was prepared by vacuum induction melting and melt-spinning.The effects of different preparation techniques of the as-cast,cast then annealed,as-spun and spun then annealed alloys on the microstructure and hydrogen storage properties were investigated.The results indicated that the non-Ca Cu5 phases in the alloy became tinier and more dispersive after annealing or melt-spinning compared to those of the as-cast one.But in the spun then annealed alloy,the non-Ca Cu5 phases disappeared and only a single-phase with Ca Cu5 type structure was found.For all the alloys,the cell volume was increased in an order of as-cast 〈 spun then annealed 〈 cast then annealed 〈 as-spun,and the change of plateau pressure showed the opposite trend with that of the cell volume.The plateau could be flattened after melt-spinning or annealing,and the spun then annealed alloy showed the minimum plateau slope.The absorption kinetics of the alloy was promoted after melt-spinning or annealing.It is suggested that the change in cell volume and compositional homogeneity resulting from different preparation techniques contribute to the difference of the hydrogen storage properties of the investigated alloys.展开更多
基金supported by the National Natural Science Foundation of China (21633008,21673221)the Jilin Province Science and Technology Development Program (20160622037JC,20170203003SF,and 20170520150JH)+1 种基金the Hundred Talents Program of the Chinese Academy of Sciencesthe Recruitment Program of Foreign Experts (WQ20122200077)
文摘Direct methanol fuel cells （DMFCs） are very promising power source for stationary and portable miniatureelectric appliances due to its high efficiency and low emissions of pollutants. As the key material, cata-lysts for both cathode and anode face several problems which hinder the commercialization of DMFCs.In this review, we mainly focus on anode catalysts of DMFCs. The process and mechanism of methanolelectrooxidation on Pt and Pt-based catalysts in acidic medium have been introduced. The influences ofsize effect and morphology on electrocatalytic activity are discussed though whether there is a size effectin MOP, catalyst is under debate. Besides, the non Pt catalysts are also listed to emphasize though Pt isstill deemed as the indispensable element in anode catalyst of DMFCs in acidic medium. Different cata-lyst systems are compared to illustrate the level of research at present. ome debates need to be verifiedwith experimental evidences.
基金supported financially by the Major Projects of National Natural Science Foundation of China(No. 31590823)the National Natural Science Foundation of China (No. 31601999)
文摘Oligopeptide transporters(OPTs) encode integral membrane-localized proteins and have a broad range of substrate transport capabilities. Here, 28 BrrOPT genes were identified in the turnip. Phylogenetic analyses revealed two well-supported clades in the OPT family, containing 15 BrrOPTs and 13 BrrYSLs.The exon/intron structure of OPT clade are conserved but the yellow stripe-like(YSL) clade was different.The exon/intron of the YSL clade possesses structural differences, whereas the YSL class motifs structure are conserved. The OPT genes are distributed unevenly among the chromosomes of the turnip genome.Phylogenetic and chromosomal distribution analyses revealed that the expansion of the OPT gene family is mainly attributable to segmental duplication. For the expression profiles at different developmental stages, a comprehensive analysis provided insights into the possible functional divergence among members of the paralog OPT gene family. Different expression levels under a variety of ion deficiencies also indicated that the OPT family underwent functional divergence during long-term evolution.Furthermore. BrrOPT8.1, BrrYSL1.2, BrrYSL1.3, BrrYSL6 and BrrYSL9 responded to Fe(Ⅱ) treatments and BrrYSL7 responded to calcium treatments, BrrYSL6 responded to multiple treatments in root, suggesting that turnip OPTs may be involved in mediating cross-talk among different ion deficiencies. Our data provide important information for further functional dissection of BrrOPTs, especially in transporting metal ions and nutrient deficiency stress adaptation.
基金financial support from the project of the National Natural Science Foundation of China(51671178,21875246)the project from DICP(DICP ZZBS201616)the support from Sino-Japanese Research Cooperative Program of Ministry of Science and Technology(2016YFE0118300) and iChEM·2011
文摘With reduced dehydrogenation enthalpy change and reduced dehydrogenation temperature compared with its phenol-cyclohexanol pair,sodium phenoxide-cyclohexanolate pair developed recently is promising for large-scale energy storage and long-distance hydrogen transportation.In the present work,we investigate the kinetic behavior of the pair in the hydrogenation and dehydrogenation in water over three commercial catalysts.It is shown that 5%Ru/Al2O3 and 5%Pt/C perform well in the hydrogenation and dehydrogenation,respectively.Kinetic analyses show that the hydrogenation of sodium phenoxide is of first-order with respect to H2 pressure and zero-order to the concentration of sodium phenoxide in the presence of Ru/Al2O3 catalyst.>99%conversion of cyclohexanol and>99%selectivity to phenoxide can be achieved in the dehydrogenation catalyzed by Pt/C catalyst and in the presence of Na OH at 100℃,where cyclohexanone was observed as an intermediate.According to the kinetic analysis,the hydrogenation of sodium phenoxide may undergo the hydrolysis and hydrogenation pathway.For the dehydrogenation,an intermediate,i.e.,cyclohexanone,was detected and two possible pathways are proposed accordingly.
基金Supported by the National Basic Research Program of China(2015CB655302)the National Science Foundation of China(51133008,51473163 and 51503199)the Development of Scientific and Technological Project of the Jilin Province(20160101316JC)
文摘Poly(arylene ether ketone)s with carboxylic groups(PAEK-COOH)is a good membrane fabrication material,a kind of polyacids,while polyethylenimine(PEI)is a weak organic base,a kind of polybases.Those polyacids and polybases would form ionic complexation at the interface of two liquid phases.In this paper,PAEK-COOH/N-methyl pyrrolidone(NMP)/1,4-dioxane(DO)mixture,employed as polymer casting solution and aqueous solution of PEI,used as coagulation bath,respectively.Then ion complexation induced phase inversion process is applied to prepare positively charged nanofiltration membrane with thinner but denser separation skin layer.The complexing reaction at the interface of two liquid phases has great influence on the kinetic aspects of phase inversion process,which in accordance would affect the morphology and performance of the membrane.The obtained membrane,fabricated via the ion complexation induced phase inversion method,is positively charged,has high water permeability,and possesses high rejection towards divalent cations,such as Mg^(2+),Ca^(2+),Pb^(2+)etc.,which could be used for removal of heavy metals from polluted water.At the optimal condition,the pure water flux of the PAEK-COOH-PEI nanofiltration membrane is 24.3 L·m^(-2)·h^(-1),with MgCl_2rejection of 92.2%.
基金funded by the Key Research Program of the Chinese Academy of Sciences (Grant No.KZZD-EW-05-01)the National Natural Science Foundation of China (Grant No.41371039)the Open Foundation of State Key Laboratory of Hydraulics and Mountain River Engineering,Sichuan University (Grant No.SKHL1426)
文摘On-spot observation and field reconnaissance of debris flows have revealed that inflexion points in the longitudinal profile of a movable channel may easily become unstable points that significantly affect their entrainment behavior.In this study,small-scale flume experiments were performed to investigate the entrainment characteristics of debris flows over two types of inflexion points,namely,a convex point,which has an upslope gradient that is less than the downslope gradient,and a concave point,which has an upslope gradient that is greater than the downslope gradient.It was observed that when debris flowed over a convex point,the entrainment developed gradually and progressively from the convex point in the downstream direction,and the primary control factors were the slope gradient and friction angle.Conversely,when debris flowed over a concave point,the entrainment was characterized by impacting and impinging erosion rather than traditional hydraulic erosion,and the impingement angle of the flow significantly determined the maximum erosion depth and outflow exit angle.An empirical relationship between the topography change and the control factors was obtained from the experimental data.
基金Acknowledgments We thank Lin-Bo Jia from Kunming Institute of Botany, Chinese Academy of Sciences, for help with fossil collection and the editor and two anonymous reviewers for improving the manuscript. Fossil examinations with the 3D Super Depth Digital Microscope and SEM were performed in the Central Lab of Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences and examination of the extant seeds with the SEM was performed in the Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences. Extant seeds of Eurya were provided by the Herbarium of Kunming Institute of Botany, Chinese Academy of Sciences. This study was supported by the National Natural Science Foundation of China （No. U1502231, 31300187）. This study is a contribution to NECLIME （Neogene Climate of Eurasia）.
文摘Eurya has an excellent fossil record in Europe, but it has only a few fossil occurrences in East Asia though this vast area houses the highest modern diversity of the genus. In this study, three-dimensionally preserved fossil seeds of Eurya stigrnosa （Ludwig） Mai from the late Pliocene of northwestern Yunnan, southwestern China are described. The seeds are compressed and flattened, slightly campylotropous, and nearly circular to slightly angular in shape. The surface of the seeds is sculptured by a distinctive foveolate pattern, consisting of funnel-shaped and finely pitted cells. Each seed valve contains a reniform or horseshoe-shaped embryo cavity, a characteristic condyle structure and an internal raphe. These fossil seeds represent one of the few fossil records of Eurya in East Asia. This new finding therefore largely extends the distributional ranges of Eurya during Neogene. Fossil records summarized here show that Eurya persisted in Europe until the early Pleistocene, but disappeared thereafter. The genus might have first appeared in East Asia no later than the late Oligocene, and dispersed widely in regions such as Japan, Nepal, and southwestern China.
基金supported by Chinese Academy of Sciences(No.201491)“Light of West China” Program(201491)
文摘Previous studies revealed that the error of pole coordinate prediction will significantly increase for a prediction period longer than 100 days, and this is mainly caused by short period oscillations. Empirical mode decomposition （EMD）, which is increasingly popular and has advantages over classical wavelet decomposition, can be used to remove short period variations from observed time series of pole co- ordinates. A hybrid model combing EMD and extreme learning machine （ELM）, where high frequency signals are removed and processed time series is then modeled and predicted, is summarized in this paper. The prediction performance of the hybrid model is compared with that of the ELM-only method created from original time series. The results show that the proposed hybrid model outperforms the pure ELM method for both short-term and long-term prediction of pole coordinates. The improvement of prediction accuracy up to 360 days in the future is found to be 24.91% and 26.79% on average in terms of mean absolute error （MAE） for the xp and yp components of pole coordinates, respectively.
基金supported financially by the National Science Fund for Distinguished Young Scholars(31525005)the NSFC-Yunnan Joint Fund (U1202263)+1 种基金the National Basic Research Program of China (973 Program) on Biological Control of Key Crop Pathogenic Nematodes (2013CB127505)the "Hundred Talents Program" of the Chinese Academy of Sciences (awarded to S.-H. Li)
文摘Glandular trichomes of plants produce a wide variety of secondary metabolites which are considered as major defensive chemicals. The capitate glandular trichomes of Oenothera glazioviana(Onagraceae) were collected with laser microdissection and analyzed by gas chromatography-mass spectrometry. The volatile compound 4-hydroxy-4-methylpentan-2-one(1) was identified. We found that compound 1 displays antimicrobial, insecticidal, and phytotoxic activities. These results suggest that compound 1 might function as a defensive compound in the capitate glandular trichomes of O. glazioviana against pathogens, insect herbivores, and presumably competitive plants as well.
基金financial support of the National Natural Science Foundation of China (project no. 51504231, 51504232, 51774262 and 21325628)Open Project of State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization (project no. CNMRCUKF1704)
文摘In the present paper, multi-walled carbon nanotubes（MWCNTs） are successfully assembled on graphite felt（GF） using sucrose pyrolysis method for the first time. The in situ formed pyrolytic carbon is chosen as the binder because it is essentially carbon materials as well as CNTs and GF which has a natural tendency to achieve high bonding strength and low contact resistance. The MWCNTs/GF electrode is demonstrated to increase surface area, reduce polarization, lower charge transfer resistance and improve energy conversion efficiency comparing with GF. This excellent electrochemical performance is mainly ascribed to the high electro-catalytic activity of MWCNTs and increasing surface area.
基金supported by the Youth Innovation Promotion Association,Chinese Academy of Sciences(CAS)under grant no.2011152Shenyang National Laboratory for Materials Science,Institute of Metal Research,CAS,under grant no.2017RP06
文摘Flexible supercapacitors are promising energy storage devices in wearable smart electronics. Exploring cost-efficient electrodes with high capacitance would promote the wide-scale application of such capacitors. Herein, in order to explore a methodology for preparing low cost, flexible, tough, and up-scalable supercapacitor electrodes, silk textile is directly carbonized to make a conductive free-standing textile substrate. Through mildly baking the surfactant-free TiCTflakes suspension loaded on the carbonized silk cloth, a uniform and adhesive coating consisting of nanometer-thick TiCTflakes is well established on the conductive fabric support, forming a MXene-coated flexible textile electrode. The fabricated electrode exhibits a high areal capacitance of 362 m F/cm~2 with excellent cyclability and flexibility. Moreover,capacitance changes neglegibly under the bending deformation mode. This study elucidates the feasibility of using silk-derived carbon cloth from biomss for MXene-based flexible supercapacitor.
基金supported by the National Natural Science Foundation of China(Grant nos.51402324,51402325,51302281)
文摘Recently, binary metal oxides have been considerably researched for energy storage since it can provide higher electrical conductivity and electrochemical activity than single components. Besides, rational arrays structure design can effectively enhance the utilization of active material. In this article, we synthesis a porous NiCo_2O_4 nanowires arrays, which were intimate contact with flexible carbon cloth（CC）by a facile hydrothermal reaction and calcination treatment. The rational array structures of NiCo_2O_4 facilitate the diffusion of electrolyte and effectively increase the utilization of active material. The asobtained NiCo_2O_4@CC electrode exhibits a high capacitance of 1183 mF cm^（-2） and an outstanding capacitance retention of 90.4% after 3000 cycles. Furthermore, a flexible asymmetric supercapacitor（ASC）using NiCo_2O_4@CC as positive electrode and activated carbon cloth（ACC） as negative electrode was fabricated, which delivers a large capacitance of 750 mF cm^（-2）（12.5 F cm^（-3））, a high energy density of 0.24 mWh cm^（-2）（3.91 mWh cm^（-3））, as well as excellent cycle stability under different bending states.These remarkable results suggest that as-assembled NiCo_2O_4@CC//ACC ASC is a promising candidate in flexible energy storage applications.
文摘The main mission of the process industries is to process resourc-es and energies into a form that can be utilized in other industriesand throughout society. In this sense, process industries cover a vastterritory, encompassing the chemical/biochemical, material, mining,metallurgical, power, food, and even pharmaceutical industries; inaddition, they are closely related to mechanical, civil, electrical, andelectronic industries, as well as to emerging fields such as biotech-nology, nanotechnology, and information technologies.
基金the Shenzhen Technology Innovation Plan(CXZZ20140731091722497 and CXZZ20140419114548507)the Shenzhen Basic Research Project(JCYJ20150529162228734,JCYJ20160407090231002,JCYJ20150625155931806 and JCYJ20160427100211076)
文摘The Ni-based K417G superalloy is extensively applied as aeroengine components for its low cost and good mid-temperature （600-900 ~C） properties. Since used in as-cast state, the comprehensive under-standing on its mechanical properties and microstructure evolution is necessary. In the present research, the tensile, creep behavior and microstructure evolution of the as-cast K417G superalloy under differ-ent conditions were investigated. The results exhibit that tensile cracks tend to initiate at MC carbide and γ＇/γ＇ eutectic structure and then propagate along grain boundary. As the temperature for tensile tests increases from 21 ℃ to 700 ℃, the yield strength and ultimate tensile strength of K417G superalloy decreases slightly, while the elongation to failure decreases greatly because of the intermediate tem- perature embrittlement. When the temperature rises to 900 ℃, the yield strength and ultimate tensile strength would decrease significantly. The creep deformation mechanism varies under different test-ing conditions. At 760 ℃/645 MPa, the creep cracks initiate at MC carbides and γ/γ＇ eutectic structures, and propagate transgranularly. While at 900℃/315 MPa and 950℃/235 MPa, the creep cracks initiate at grain boundary and propagate intergranularly. As the creep condition changes from 760 ℃/645 MPa to 900 ℃/315 MPa and 950 ℃/235 MPa, the γ＇ phase starts to raft, which reduces the creep deformation resistance and increases the steady-state deformation rate.
基金supported by the Ministry of Science and Technology of China(MOST, 2013CBA01804)the National Nature Science Foundation of China (41425003,41401079, 41476164 and 41625014)+2 种基金the key project of CAMS:Research on the Key Processes of Cryospheric Rapid Changes (KJZD-EW-G03)the Opening Founding of State Key Laboratory of Cryospheric Sciences(SKLCSOP-2016-03)the State Key Laboratory of Cryospheric Sciences (SKLCS-ZZ-2017)
文摘Based on the field measurements in Barrow, Alaska within the period of April-May 2015, we investigate the sources and variations of elemental carbon(EC) and organic carbon(OC) in the surface layer of snowpack on sea ice, and estimate their effects on the sea ice albedo. Results show that the snow OC in Barrow are from natural sources(e.g. terrestrial higher plants and micro-organisms) mainly, as well as biomass burning(e.g. forest fires and straw combustion) as an important part. Both EC and OC can accumulate at the snow surface with snow melt. The variations in EC and OC and liquid water content in the snow layer are well consistent during the snow-melting period. A higher rate of snow melt implied a more efficient enrichment of EC and OC. In the last phase of snow melt, the concentration increased to a maximum of 16.2 ng/g for EC and 128 ng/g for OC, which is ~10 times larger than those before snow melt onset. Except for the dominant influence of melt amplification mechanism, the variation in concentrations of EC and OC could be disturbed by the air temperature fluctuation and snowfall. Our study indicates that the lightabsorbing impurities contributed 1.6%-5.1% to the reduction in sea ice albedo with melt during the measurement period. The significant period oflight-absorbing impurities influencing on sea ice albedo begins with the rapid melting of overlying snow and ends before the melt ponds formed widely, which lasted for about 10 days in Barrow, 2015.
基金supported by grants from National Natural Science Foundation of China (No. 31100260, 81260480, and 41566004)National Natural Science Foundation of Guangxi (No. 2011GXNSFE018002)+1 种基金Guangxi Key Laboratory of Marine Environmental Science, Guangxi Academy of Sciences (No. GXKLHY13-06)Foundation of Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences (No. 201210ZS)
文摘Two new compounds, namely taenialactam C and globorin A（1 and 2）, as well as six known compounds,cornoside（3）, 2-phenylethyl-b-D-glucoside（4）, 3-isopropyl-5-acetoxycyclohexene-2-one-1（5）, 4-methyl-phenol（6）, 5-[（2S）-2-aminobutyl]-2-methyl-phenol（7）, and 1-（4-methylphenyl）-1-propanone（8） were isolated from wild Phaeocystis globosa. The structures of the new compounds were established by detailed spectroscopic analysis and by comparison with spectral data of related known compounds.The structures of the known compounds were identified by comparing their spectroscopic data with those reported in the literature. This paper also reports toxicity properties of the eight compounds against the brine shrimp Artemia salina and juvenile Epinephelus akaara fish. Some of these compounds showed significant lethality on the brine shrimp A. salina and the juvenile E. akaara fish.
基金supported by the National 973 Project of China(2006CB403703,2010CB428503)the Knowledge Innovation Program of the Chinese Academy of Sciences(Grant Nos:KZCX2-YW-Q11-03,KZCX2-YW-Q1-02)the Hundred Talents Program of the Chinese Academy of Sciences
文摘Nine heterogeneous reactions （uptake of H2O2, HNO3, HO2, N2O5, NO2, NO3, O3, OH and SO2 on mineral aerosol surfaces） are incorporated into a Regional Air Quality Model System （RAQMS） to investigate their impacts on tropospheric chemistry in East Asia during the dust storm period in March 2006. Comparison with observations shows the model system well represents the behaviors of the gaseous and aerosol species. Most of the reaction probability γvalues used for this study are the best estimation specifically for dust samples from deserts of China, derived from analysis of a number of recent laboratory studies. There are large variations in gas and aerosol concentrations while taking heterogeneous reactions on mineral aerosol surface into account, especially during dust storm events. The domain-averaged monthly mean percentage changes in SO2, NO2, O3, HNO3, NH3, total sulfate, total nitrate and total ammonium concentrations are -4.4%, -3.8%, -2.1%, -22.0%, 12.7%, 6.6%, 26.1%, and -9.5%, respectively below 3 km. These changes indicate the considerable perturbation of heterogeneous reactions on mineral aerosol surface to tropospheric chemical system and components. The strength of heterogeneous reactions is determined by both reaction probability and gas precursor concentration. Among the nine reactions, dust uptakes of HNO3, SO2, and N2O5 exert relatively large influences on the other chemical components, whereas the reactions regarding H2O2, HO2, and OH have little impacts.
基金supported by the National Natural Science Foundation of China (Nos. 41121001, 41225002, 41571073)the Strategic Priority Research Program (B) of the Chinese Academy of Sciences (No. XDB03030504)
文摘The Tibetan Plateau is home to the largest aggregate of glaciers outside the Polar Regions and is a source of fresh water to 1.4 billion people. Yet little is known about the transportation and cycling of Hg in high-elevation glacier basins on Tibetan Plateau. In this study, surface snow,glacier melting stream water and lake water samples were collected from the Qiangyong Glacier Basin. The spatiotemporal distribution and transportation of Hg from glacier to lake were investigated. Significant diurnal variations of dissolved Hg（DHg） concentrations were observed in the river water, with low concentrations in the morning（8：00 am–14：00 pm） and high concentrations in the afternoon（16：00 pm–20：00 pm）. The DHg concentrations were exponentially correlated with runoff, which indicated that runoff was the dominant factor affecting DHg concentrations in the river water. Moreover, significant decreases of Hg were observed during transportation from glacier to lake. DHg adsorption onto particulates followed by the sedimentation of particulate-bound Hg（PHg） could be possible as an important Hg removal mechanism during the transportation process. Significant decreases in Hg concentrations were observed downstream of Xiao Qiangyong Lake, which indicated that the high-elevation lake system could significantly affect the distribution and transportation of Hg in the Qiangyong Glacier Basin.
基金supported by the National Basic Research Program of China (973 Program) (2015CB921300)the National Natural Science Foundation of China (11334012)the Strategic Priority Research Program of Chinese Academy of Sciences (XDB07000000)
文摘We suggest a new family of Co[Ni-based materials that may host unconventional high temperature superconductivity （high-To）. These materials carry layered square lattices with each layer being formed by vertex-shared transition metal tetrahedra cation-anion complexes. The electronic physics in these materials is determined by the two dimensional layer and is fully attributed to the three near degenerated t2g d-orbitals close to a d7 filling configuration in the d-shell of CoJNi atoms. The electronic structure meets the necessary criteria for unconventional high Tc materials proposed recently by us to unify the two known high-Tc families, cuprates and iron-based superconductors. We predict that they host superconducting states with a d-wave pairing symmetry with Tc potentially higher than those of iron-based superconductors. These materials, if realized, can be a fertile new ground to study strongly correlated electronic Physics and provide decisive evidence for superconducting pairing mechanism.
文摘In this study, the flow characteristics of Geldart A particles in a bobbling fluidized bed with and without perforated plates were simulated by the multiphase particle-in-cell （MP-PlC）-based Eolerian-Lagrangian method. A modified structure-based drag model was developed based on our previous work. Other drag models including the Parker and Wen-Yo-Ergon drag models were also employed to investigate the effects of drag models on the simulation results. Although the modified structure-based drag model better predicts the gas-solid flow dynamics of a baffle-free bubbling fluidized bed in comparison with the experimental data, none of these drag models predict the gas-solid flow in a baffled bobbling floidized bed sufficiently well because of the treatment of baffles in the Barracuda software. To improve the simulation accuracy, future versions of Barracuda should address the challenges of incorporating the bed height and the baffles.
基金supported by the National Natural Science Foundation of China(No.51271176)National Basic Research Program of China(No.2010CB631305)
文摘La Ni3.8Al1.0Mn0.2 alloy was prepared by vacuum induction melting and melt-spinning.The effects of different preparation techniques of the as-cast,cast then annealed,as-spun and spun then annealed alloys on the microstructure and hydrogen storage properties were investigated.The results indicated that the non-Ca Cu5 phases in the alloy became tinier and more dispersive after annealing or melt-spinning compared to those of the as-cast one.But in the spun then annealed alloy,the non-Ca Cu5 phases disappeared and only a single-phase with Ca Cu5 type structure was found.For all the alloys,the cell volume was increased in an order of as-cast 〈 spun then annealed 〈 cast then annealed 〈 as-spun,and the change of plateau pressure showed the opposite trend with that of the cell volume.The plateau could be flattened after melt-spinning or annealing,and the spun then annealed alloy showed the minimum plateau slope.The absorption kinetics of the alloy was promoted after melt-spinning or annealing.It is suggested that the change in cell volume and compositional homogeneity resulting from different preparation techniques contribute to the difference of the hydrogen storage properties of the investigated alloys.
