40Ar/39Ar and zircon U-Pb geochronological and whole-rock geochemical analyses for the Laozanggou intermediate-acidic volcanic rocks from the western Qinling orogenic belt,Central China,constrain their petrogenesis an...40Ar/39Ar and zircon U-Pb geochronological and whole-rock geochemical analyses for the Laozanggou intermediate-acidic volcanic rocks from the western Qinling orogenic belt,Central China,constrain their petrogenesis and the nature of the Late Mesozoic lithospheric mantle.These volcanic rocks yield hornblende or whole-rock 40Ar/39Ar plateau ages of 128.3-129.7 Ma and zircon U-Pb age of131.3±1.3 Ma.They exhibit SiO2 of 56.86-66.86 wt.%,K2 O of 0.99-2.46 wt.%and MgO of 1.03-4.47 wt.%,with Mg#of 42-56.They are characterized by arc-like geochemical signatures with significant enrichment in LILE and LREE and depletion in HFSE.All the samples have enriched Sr-Nd isotopic compositions with initial 87Sr/86Sr ratios ranging from 0.7112 to 0.7149 andεNd(t)values from 10.2 to 6.3.Such geochemical signatures suggest that these volcanic rocks were derived from enriched lithospherederived magma followed by the assimilation and fractional crystallization(AFC)process.The generation of the enriched lithospheric mantle is likely related to the modification of sediment-derived fluid in response to the Triassic subduction/collision event in Qinling orogenic belt.The early Cretaceous detachment of the lithospheric root provides a reasonable mechanism for understanding the petrogenesis of the Laozanggou volcanic sequence in the western Qinling orogenic belt.展开更多
Percutaneous coronary intervention for the treatment of coronary artery disease is most commonly performed in the UK through the radial artery,as this is considered to be safer than the femoral approach.However,despit...Percutaneous coronary intervention for the treatment of coronary artery disease is most commonly performed in the UK through the radial artery,as this is considered to be safer than the femoral approach.However,despite improvements in technology and techniques,complications can occur.The most common complication,arterial spasm,can cause intense pain and,in some cases,procedural failure.The incidence of spasm is dependent on several variables,including operator experience,artery size,and equipment used.An antispasmolytic cocktail can be applied to reduce spasm,which usually includes an exogenous nitric oxide(NO)donor(glyceryl trinitrate).NO is an endogenous local vasodilator and therefore is a potential target for anti-spasm intervention.However,systemic administration can result in unwanted side-effects,such as hypotension.A method that adopts local delivery of NO might be advantageous.This review article describes the mechanisms involved in radial artery spasm,discusses the advantages and disadvantages of current strategies to reduce spasm,and highlight the potential of NO-loaded nanoporous materials for use in this setting.展开更多
Each neuronal subtype is distinct in how it develops,responds to environmental cues,and whether it is capable of mounting a regenerative response following injury.Although the adult central nervous system（CNS） does ...Each neuronal subtype is distinct in how it develops,responds to environmental cues,and whether it is capable of mounting a regenerative response following injury.Although the adult central nervous system（CNS） does not regenerate,several experimental interventions have been trialled with successful albeit limited instances of axonal repair.We highlight here some of these approaches including extracellular matrix（ECM） modification,cellular grafting,gene therapy-induced replacement of proteins,as well as application of biomaterials.We also review the recent report demonstrating the failure of axonal localization and transport of growth-promoting receptors within certain classes of mature neurons.More specifically,we discuss an inability of integrin receptors to localize within the axonal compartment of mature motor neurons such as in the corticospinal and rubrospinal tracts,whereas in immature neurons of those pathways and in mature sensory tracts such as in the optic nerve and dorsal column pathways these receptors readily localize within axons.Furthermore we assert that this failure of axonal localization contributes to the intrinsic inability of axonal regeneration.We conclude by highlighting the necessity for both combined therapies as well as a targeted approach specific to both age and neuronal subtype will be required to induce substantial CNS repair.展开更多
As part of a collaborative study between the 3rd Institute of Oceanography, Xiamen, and the U-K. Universities of East Anglia and St. Andrews, a 4-day experiment was conducted on a ridge- and -runnel beach of north Nor...As part of a collaborative study between the 3rd Institute of Oceanography, Xiamen, and the U-K. Universities of East Anglia and St. Andrews, a 4-day experiment was conducted on a ridge- and -runnel beach of north Norfolk on the North Sea coast- Detailed surveys were made of every low water of an area 10m by 30m and electromagnetic current meters were used to measure wave- induced currents over the ridge and in the runnel- The locations of bedform fields were noted, fluorescent sand was used to follow the sand movement and, at the end of the experiment, lacquer peels were taken of the top 0-2 m of a vertical section through the ridge- and- runnel-During the 4 days 0-75 m3 of sand per metre width of beach accreted in the runnel and a similar volume was eroded from the upper foreshore. The dominant shoreward transport, identified qualitatively by the movement of the fluorescent sand, suggests the ridge- and- runnel system migrated shorewards up the general beach slope of 1 by 2 - 3 m. The wave orbital展开更多
We explore degeneracies in strong lensing model so to make time delay data consistent with the WMAP （Wilkinson Microwave Anisotropy Probe） cosmology. Previous models using a singular isothermal lens often yield a ti...We explore degeneracies in strong lensing model so to make time delay data consistent with the WMAP （Wilkinson Microwave Anisotropy Probe） cosmology. Previous models using a singular isothermal lens often yield a time delay between the observed multiple images too small than the observed value if we ＂hardwire＂ the now widely quoted post-WMAP ＂high＂ value of the Hubble constant （Ho ～71 ± 4km s^-1 Mpc^-1）. Alternatively, the lens density profile （star plus dark matter） is required to be locally steeper than r-2 （isothermal） profile near the Einstein radius （of the order 3 kpc） to fit the time delays; a naive extrapolation of a very steep profile to large radius would imply a lens halo with a scale length of the order only 3 kpc, too compact to be consistent with CDM. We explore more sophisticated, mathematically smooth, positive lens mass density profiles which are consistent with a large halo and the post-WMAP H0. Thanks to the spherical monopole degeneracy, the ＂reshuffling＂ of the mass in a lens model does not affect the quality of the fit to the image positions, amplifications, and image time delays. Even better, unlike the better-known mass sheet degeneracy, the stellar mass-to-light and the H0 value are not affected either. We apply this monopole degeneracy to the quadruple imaged time-delay system PG 1115＋080. Finally we discuss the implications of the time delay data on the newly proposed relativistic MOND theory.展开更多
Based on a variety of geometric observations for location of solutions, a general and unified region analysis framework for developing constructive solvability of nonlinear operator equations are proposed. Within this...Based on a variety of geometric observations for location of solutions, a general and unified region analysis framework for developing constructive solvability of nonlinear operator equations are proposed. Within this framework, the methods including interval, ball and ellipsoid methods can be studied in a unified way. The ball algorithm, as a typical example, is in particular analysed.展开更多
A hybrid epoxy resin with intrinsic self healing properties has been prepared from a bifunctional Diels-Alder (DA) adduct. The obtained network, based on conventional Diglycidyl ether of BisphenolA (DGEBA) and DA epox...A hybrid epoxy resin with intrinsic self healing properties has been prepared from a bifunctional Diels-Alder (DA) adduct. The obtained network, based on conventional Diglycidyl ether of BisphenolA (DGEBA) and DA epoxy, leads to simultaneous tuning of physical-chemical properties and healing capability. The self-repairing behavior has been verified by means of scratch recovery observation and micromechanical analysis. A satisfactory morphological and mechanical recovery has been achieved by thermal stimulus, leading to very promising application in the field of adhesives and structural applications.展开更多
Axon regeneration in the CNS is largely unsuccessful due to excess inhibitory extrinsic factors within lesion sites together with an intrinsic inability of neurons to regrow following injury. Recent work demonstrates ...Axon regeneration in the CNS is largely unsuccessful due to excess inhibitory extrinsic factors within lesion sites together with an intrinsic inability of neurons to regrow following injury. Recent work demonstrates that forced expression of certain neuronal transmembrane receptors can recapitulate neuronal growth resulting in successful growth within and through inhibitory lesion environments. More specifically, neuronal expression of integrin receptors such as alpha9beta1 integrin which binds the extracellular matrix glycoprotein tenascin-C, trk receptors such as trk B which binds the neurotrophic factor BDNF, and receptor PTPσ which binds chondroitin sulphate proteoglycans, have all been show to significantly enhance regeneration of injured axons. We discuss how reintroduction of these receptors in damaged neurons facilitates signalling from the internal environment of the cell with the external environment of the lesion milieu, effectively resulting in growth and repair following injury. In summary, we suggest an appropriate balance of intrinsic and extrinsic factors are required to obtain substantial axon regeneration.展开更多
GaN-based light-emitting devices(LEDs)with different electron blocking layers are theoretically studied and compared by using the advanced physical models of a semiconductor device simulation program.It is found that ...GaN-based light-emitting devices(LEDs)with different electron blocking layers are theoretically studied and compared by using the advanced physical models of a semiconductor device simulation program.It is found that the structure with an AlInN electron blocking layer shows improved light output power,lower current leakage and efficiency droop.Based on numerical simulation and analysis,these improvements of the electrical and optical characteristics are mainly accounted for by efficient electron blocking.It can be concluded that Auger recombination is responsible for the dominant origin of the efficiency droop of a GaN-based LED as current increases.展开更多
Language transfer is one of the most significant aspects of cross-linguistic influ-ence.It can be divided into two types:positive and negative,the beneficial and det-rimental use of one language's acquired charact...Language transfer is one of the most significant aspects of cross-linguistic influ-ence.It can be divided into two types:positive and negative,the beneficial and det-rimental use of one language's acquired characteristics in another.This study aims to investigate the L1(Chinese)influence on Hong Kong ESL learners'acquisition of conjunctions and whether the use of L1 has an impact on this influence.An online questionnaire combining questions about students'English learning experience and a grammatical judgement task was sent to a government-funded secondary school in Hong Kong and completed by 79 students.Evidence of both positive and negative transfer from Chinese to English was found by testing six conjunctions or conjunc-tion pairs:although...but,because...so,not only...but also,either...or,neither...nor,.and despite.The results suggest that Chinese is likely to have an impact on students'acquisition of conjunctions,and the use of Chinese in English classes can worsen negative transfer and boost positive transfer.The degree of transfer might increase when more Chinese is used in class.To alleviate the impact of Chinese transfer and to provide more effective L2 teaching,monitoring the use of L1 and regular evalua-tion might be useful.Teachers can also adjust the amount of Chinese used according to the students'English proficiency level.展开更多
We have designed and synthesized NaGdF4：Nd^3＋, Yb^3＋, Tm^3＋. magnetic nano- phosphors with combined dual-mode downconversion （DC） and upconversion （UC） photoluminescence upon 800 run excitation. Hexagonal-phas...We have designed and synthesized NaGdF4：Nd^3＋, Yb^3＋, Tm^3＋. magnetic nano- phosphors with combined dual-mode downconversion （DC） and upconversion （UC） photoluminescence upon 800 run excitation. Hexagonal-phase NaGdF4：Nd^3＋, Yb^3＋, Tm^3＋ nanocrystals （NCs） with an average size of 21 nm were synthesized using a solvothermal approach. Nd^3＋, Yb^3＋, Tm^3＋ triple-doped NaGdF4 NCs exhibit a broad range of photoluminescence peaks covering a near infrared first/second window （860-900, 1,000, and 1,060 nm）, and visible emission including blue （475 nm）, green （520 and 542 nm） and yellow （587 nm） after excitation at 800 nm. A mechanism involving circulation of energy over Gd^3＋ sublattices as bridge ions and final trapping by the initial activator ions （Nd^3＋） has been proposed. Penetration depth studies indicate that NIR emission is easily detected even at a large tissue thickness of 10 mm. These paramagnetic nanophosphors demonstrate a large magnetization value of 1.88 emu/g at 20 kOe and longitudinal relaxivity value of 1.2537 mM-1.S-1 as a Tl-weighted magnetic resonance imaging contrast agent. These NaGdF4：Nd^3＋, Yb^3＋ Tm^3＋ NCs are promising for applications in biological and magnetic resonance imaging.展开更多
Anatase TiO2 microspheres with exposed dominant {001} facets were doped with interstitial boron to have a concentration gradient with the maximum concentration at the surface. They were then further doped with substit...Anatase TiO2 microspheres with exposed dominant {001} facets were doped with interstitial boron to have a concentration gradient with the maximum concentration at the surface. They were then further doped with substitutional nitrogen by heating in an ammonia atmosphere at different temperatures from 440 to 560℃ to give surface N concentrations ranging from 7.03 to 15.47 at%. The optical absorption, atomic and electronic structures and visible-light photoelectrochemical water oxidation activity of these materials were investigated. The maximum activity of the doped TiO2 was achieved at a nitrogen doping temperature of 520℃ that gave a high absorbance over the whole visible light region but with no defect-related background absorption.展开更多
The realization of a mixed-phase microstructure in strained BiFeO_(3)(BFO)thin films has led to numerous novel effects derived from the coexistence of the tetragonal-like monoclinic phase(T phase)and rhombohedral-like...The realization of a mixed-phase microstructure in strained BiFeO_(3)(BFO)thin films has led to numerous novel effects derived from the coexistence of the tetragonal-like monoclinic phase(T phase)and rhombohedral-like monoclinic phase(R phase).Strong strain and polarization diiferences between the phases should result in a high level of transformation plasticity,which enables the continuous alteration of the relative proportion of R and T states in response to external forces.Although the potential for utilizing such plasticity to control mixed-phase populations under external stimuli is evident,direct experi・mental evidence backed by equilibrium predictions has not yet been fully demonstrated.Here we demonstrate deterministic control of mixed-phase populations in an epitaxially strained BFO thin film through the application of localized stresses and electric fields in a reversible manne匚The results illustrate and rationalize deterministic control of mixed phases in strained BFO films,which could be crucial in tuning their functional properties.The findings also highlight a new multiparametric technique in the scanning probe lithography toolbox based on tip-assisted electric and strain field manipulation of functional properties that might find application beyond the ferroelectric domain and structural phase lithography.展开更多
Intra- and interspecific variation in plant and insect traits can alter the strength and direction of insect-plant interactions, with outcomes modified by soil biotic and abiotic conditions. We used the potato aphid ...Intra- and interspecific variation in plant and insect traits can alter the strength and direction of insect-plant interactions, with outcomes modified by soil biotic and abiotic conditions. We used the potato aphid （Macrosiphum euphorbiae Thomas） feeding on cultivated Solanum tuberosum and wild Solanurn berthaulti to study the impact of water availability and plant mutualistic arbuscular mycorrhizal （AM） fungi on aphid performance and susceptibility to a parasitoid wasp （Aphidius ervi Haliday）. Plants were grown under glass with live or sterile AM fungal spores and supplied with sufficient or reduced water supply. Plants were infested with 1 of 3 genotypes ofM. euphorbiae or maintained as aphidfree controls; aphid abundance was scored after 1 week, after which aphid susceptibility to A. ervi was assayed explanta. Solarium tuberosum accumulated c. 20% more dry mass than S. berthaultii, and root mass of S. berthaultii was smallest under reduced water supply in the presence of AM fungi. Aphid abundance was lowest on S. berthaultii and highest for genotype ＂2＂ aphids; genotype ＂1＂ aphid density was particularly reduced on S. berthaultii. Aphid genotype ＂1＂ exhibited low susceptibility to parasitism and was attacked less frequently than the other two more susceptible aphid genotypes. Neither AM fungi nor water availability affected insect performance. Our study suggests a fitness trade-offin M. euphorbiae between parasitism resistance and aphid performance on poor quality Solarium hosts that warrants further exploration, and indicates the importance of accounting for genotype identity in determining the outcome of multitrophic interactions.展开更多
Hydrogen is expected to play an important role in future transportation as a promising alternative clean energy source to carbon-based fuels. One of the key challenges to commercialize hydrogen energy is to develop ap...Hydrogen is expected to play an important role in future transportation as a promising alternative clean energy source to carbon-based fuels. One of the key challenges to commercialize hydrogen energy is to develop appropriate onboard hydrogen storage systems, capable of charging and discharging large quantities of hydrogen with fast enough kinetics to meet commercial requirements. Metal organic framework （MOF） is a new type of inorganic and organic hybrid nanoporous particulate materials. Its diverse networks can enhance hydrogen storage through tuning the structure and property of MOFs. The MOF materials so far developed adsorb hydrogen through weak dispersion interactions, which allow significant quantity of hydrogen to be stored at cryogenic temperatures with fast kinetics. Novel MOFs are being developed to strengthen the interactions between hydrogen and MOFs in order to store hydrogen under ambient conditions. This review surveys the development of such candidate materials, their performance and future research needs.展开更多
The present study investigates the influence of international oil prices on China＇s stock market returns across 29 different industries. The paper attempts to account for any structural breaks and nonlinearity in thi...The present study investigates the influence of international oil prices on China＇s stock market returns across 29 different industries. The paper attempts to account for any structural breaks and nonlinearity in this relationship. The results reveal that the effect of changes in the international price of oil on stock returns differs substantially across industries. The stock returns of the coal chemical mining and oil industries are found to be positively affected by crude oil price movements. Conversely, electronics, food manufacturing, general equipment, pharmaceuticals, retail rubber and vehicle industries are found to be negatively affected by movements in the price of crude oil. The results of the estimations also suggest that the majority of Chinese industries have been significantly affected by oil prices since 2004. The influence of international oil prices on Chinese stocks also has a stronger effect in the presence of high volatility but the effect varies across industries.展开更多
A number of laser facilities coming online all over the world promise the capability of high-power laser experiments with shot repetition rates between 1 and 10 Hz. Target availability and technical issues related to ...A number of laser facilities coming online all over the world promise the capability of high-power laser experiments with shot repetition rates between 1 and 10 Hz. Target availability and technical issues related to the interaction environment could become a bottleneck for the exploitation of such facilities. In this paper, we report on target needs for three different classes of experiments: dynamic compression physics, electron transport and isochoric heating, and laser-driven particle and radiation sources. We also review some of the most challenging issues in target fabrication and high repetition rate operation. Finally, we discuss current target supply strategies and future perspectives to establish a sustainable target provision infrastructure for advanced laser facilities.展开更多
This review offers the first synthesis of the research on mixed-species groupings of arthropods and highlights the behavioral and evolutionary questions raised by such behavior.Mixed-species groups are commonly found ...This review offers the first synthesis of the research on mixed-species groupings of arthropods and highlights the behavioral and evolutionary questions raised by such behavior.Mixed-species groups are commonly found in mammals and birds.Such groups are also observed in a large range of arthropod taxa independent of their level of sociality. Several examples are presented to highlight the mechanisms underlying such groupings, particularly the evidence for phylogenetie proximity between members that promotes cross-species recognition.The advantages offered by such aggregates are described and discussed.These advantages can be attributed to the increase in group size and could be identical to those of nonmixed groupings,but competition-cooperation dynamics might also be involved,and such effects may differ between homo-and heterospecific groups.We discuss three extreme cases of interspecific recognition that are likely involved in mixed-species groups as vectors for cross-species aggregation:tolerance behavior between two social species,one-way mechanism in which one species is attractive to others and two-way mechanism of mutual attraction.As shown in this review,the study of mixed-species groups offers biologists an interesting way to explore the frontiers of cooperation-competition, including the process of sympatric speciation.展开更多
基金financially supported by National Natural Science Foundation of China(Grant Nos.41421002,41302176 and 41872236)National Basic Research Program of China(Grant No.2014CB440901)+1 种基金Foundation of Shaanxi Educational committee(14JK1760)P.A.Cawood acknowledges support from Australian Research Council(GrantFL160100168)
文摘40Ar/39Ar and zircon U-Pb geochronological and whole-rock geochemical analyses for the Laozanggou intermediate-acidic volcanic rocks from the western Qinling orogenic belt,Central China,constrain their petrogenesis and the nature of the Late Mesozoic lithospheric mantle.These volcanic rocks yield hornblende or whole-rock 40Ar/39Ar plateau ages of 128.3-129.7 Ma and zircon U-Pb age of131.3±1.3 Ma.They exhibit SiO2 of 56.86-66.86 wt.%,K2 O of 0.99-2.46 wt.%and MgO of 1.03-4.47 wt.%,with Mg#of 42-56.They are characterized by arc-like geochemical signatures with significant enrichment in LILE and LREE and depletion in HFSE.All the samples have enriched Sr-Nd isotopic compositions with initial 87Sr/86Sr ratios ranging from 0.7112 to 0.7149 andεNd(t)values from 10.2 to 6.3.Such geochemical signatures suggest that these volcanic rocks were derived from enriched lithospherederived magma followed by the assimilation and fractional crystallization(AFC)process.The generation of the enriched lithospheric mantle is likely related to the modification of sediment-derived fluid in response to the Triassic subduction/collision event in Qinling orogenic belt.The early Cretaceous detachment of the lithospheric root provides a reasonable mechanism for understanding the petrogenesis of the Laozanggou volcanic sequence in the western Qinling orogenic belt.
基金Supported by the European Social Fund and Scottish Funding Council as part of Developing Scotland’s Workforce in the Scotland 2014-2020 European Structural and Investment Fund Programme
文摘Percutaneous coronary intervention for the treatment of coronary artery disease is most commonly performed in the UK through the radial artery,as this is considered to be safer than the femoral approach.However,despite improvements in technology and techniques,complications can occur.The most common complication,arterial spasm,can cause intense pain and,in some cases,procedural failure.The incidence of spasm is dependent on several variables,including operator experience,artery size,and equipment used.An antispasmolytic cocktail can be applied to reduce spasm,which usually includes an exogenous nitric oxide(NO)donor(glyceryl trinitrate).NO is an endogenous local vasodilator and therefore is a potential target for anti-spasm intervention.However,systemic administration can result in unwanted side-effects,such as hypotension.A method that adopts local delivery of NO might be advantageous.This review article describes the mechanisms involved in radial artery spasm,discusses the advantages and disadvantages of current strategies to reduce spasm,and highlight the potential of NO-loaded nanoporous materials for use in this setting.
基金support from the Morton Cure Paralysis Fund and Royal Society Research grant
文摘Each neuronal subtype is distinct in how it develops,responds to environmental cues,and whether it is capable of mounting a regenerative response following injury.Although the adult central nervous system（CNS） does not regenerate,several experimental interventions have been trialled with successful albeit limited instances of axonal repair.We highlight here some of these approaches including extracellular matrix（ECM） modification,cellular grafting,gene therapy-induced replacement of proteins,as well as application of biomaterials.We also review the recent report demonstrating the failure of axonal localization and transport of growth-promoting receptors within certain classes of mature neurons.More specifically,we discuss an inability of integrin receptors to localize within the axonal compartment of mature motor neurons such as in the corticospinal and rubrospinal tracts,whereas in immature neurons of those pathways and in mature sensory tracts such as in the optic nerve and dorsal column pathways these receptors readily localize within axons.Furthermore we assert that this failure of axonal localization contributes to the intrinsic inability of axonal regeneration.We conclude by highlighting the necessity for both combined therapies as well as a targeted approach specific to both age and neuronal subtype will be required to induce substantial CNS repair.
文摘As part of a collaborative study between the 3rd Institute of Oceanography, Xiamen, and the U-K. Universities of East Anglia and St. Andrews, a 4-day experiment was conducted on a ridge- and -runnel beach of north Norfolk on the North Sea coast- Detailed surveys were made of every low water of an area 10m by 30m and electromagnetic current meters were used to measure wave- induced currents over the ridge and in the runnel- The locations of bedform fields were noted, fluorescent sand was used to follow the sand movement and, at the end of the experiment, lacquer peels were taken of the top 0-2 m of a vertical section through the ridge- and- runnel-During the 4 days 0-75 m3 of sand per metre width of beach accreted in the runnel and a similar volume was eroded from the upper foreshore. The dominant shoreward transport, identified qualitatively by the movement of the fluorescent sand, suggests the ridge- and- runnel system migrated shorewards up the general beach slope of 1 by 2 - 3 m. The wave orbital
基金Supported by the National Natural Science Foundation of China.
文摘We explore degeneracies in strong lensing model so to make time delay data consistent with the WMAP （Wilkinson Microwave Anisotropy Probe） cosmology. Previous models using a singular isothermal lens often yield a time delay between the observed multiple images too small than the observed value if we ＂hardwire＂ the now widely quoted post-WMAP ＂high＂ value of the Hubble constant （Ho ～71 ± 4km s^-1 Mpc^-1）. Alternatively, the lens density profile （star plus dark matter） is required to be locally steeper than r-2 （isothermal） profile near the Einstein radius （of the order 3 kpc） to fit the time delays; a naive extrapolation of a very steep profile to large radius would imply a lens halo with a scale length of the order only 3 kpc, too compact to be consistent with CDM. We explore more sophisticated, mathematically smooth, positive lens mass density profiles which are consistent with a large halo and the post-WMAP H0. Thanks to the spherical monopole degeneracy, the ＂reshuffling＂ of the mass in a lens model does not affect the quality of the fit to the image positions, amplifications, and image time delays. Even better, unlike the better-known mass sheet degeneracy, the stellar mass-to-light and the H0 value are not affected either. We apply this monopole degeneracy to the quadruple imaged time-delay system PG 1115＋080. Finally we discuss the implications of the time delay data on the newly proposed relativistic MOND theory.
文摘Based on a variety of geometric observations for location of solutions, a general and unified region analysis framework for developing constructive solvability of nonlinear operator equations are proposed. Within this framework, the methods including interval, ball and ellipsoid methods can be studied in a unified way. The ball algorithm, as a typical example, is in particular analysed.
文摘A hybrid epoxy resin with intrinsic self healing properties has been prepared from a bifunctional Diels-Alder (DA) adduct. The obtained network, based on conventional Diglycidyl ether of BisphenolA (DGEBA) and DA epoxy, leads to simultaneous tuning of physical-chemical properties and healing capability. The self-repairing behavior has been verified by means of scratch recovery observation and micromechanical analysis. A satisfactory morphological and mechanical recovery has been achieved by thermal stimulus, leading to very promising application in the field of adhesives and structural applications.
文摘Axon regeneration in the CNS is largely unsuccessful due to excess inhibitory extrinsic factors within lesion sites together with an intrinsic inability of neurons to regrow following injury. Recent work demonstrates that forced expression of certain neuronal transmembrane receptors can recapitulate neuronal growth resulting in successful growth within and through inhibitory lesion environments. More specifically, neuronal expression of integrin receptors such as alpha9beta1 integrin which binds the extracellular matrix glycoprotein tenascin-C, trk receptors such as trk B which binds the neurotrophic factor BDNF, and receptor PTPσ which binds chondroitin sulphate proteoglycans, have all been show to significantly enhance regeneration of injured axons. We discuss how reintroduction of these receptors in damaged neurons facilitates signalling from the internal environment of the cell with the external environment of the lesion milieu, effectively resulting in growth and repair following injury. In summary, we suggest an appropriate balance of intrinsic and extrinsic factors are required to obtain substantial axon regeneration.
基金Supported by the National Natural Science Foundation of China under Grant No 61078046the Natural Science Foundation of Guangdong Province under Grant No 10151063101000009the Scientific and Technological Plan Project of Guangdong Province under Grant No 2010B010600030.
文摘GaN-based light-emitting devices(LEDs)with different electron blocking layers are theoretically studied and compared by using the advanced physical models of a semiconductor device simulation program.It is found that the structure with an AlInN electron blocking layer shows improved light output power,lower current leakage and efficiency droop.Based on numerical simulation and analysis,these improvements of the electrical and optical characteristics are mainly accounted for by efficient electron blocking.It can be concluded that Auger recombination is responsible for the dominant origin of the efficiency droop of a GaN-based LED as current increases.
文摘Language transfer is one of the most significant aspects of cross-linguistic influ-ence.It can be divided into two types:positive and negative,the beneficial and det-rimental use of one language's acquired characteristics in another.This study aims to investigate the L1(Chinese)influence on Hong Kong ESL learners'acquisition of conjunctions and whether the use of L1 has an impact on this influence.An online questionnaire combining questions about students'English learning experience and a grammatical judgement task was sent to a government-funded secondary school in Hong Kong and completed by 79 students.Evidence of both positive and negative transfer from Chinese to English was found by testing six conjunctions or conjunc-tion pairs:although...but,because...so,not only...but also,either...or,neither...nor,.and despite.The results suggest that Chinese is likely to have an impact on students'acquisition of conjunctions,and the use of Chinese in English classes can worsen negative transfer and boost positive transfer.The degree of transfer might increase when more Chinese is used in class.To alleviate the impact of Chinese transfer and to provide more effective L2 teaching,monitoring the use of L1 and regular evalua-tion might be useful.Teachers can also adjust the amount of Chinese used according to the students'English proficiency level.
文摘We have designed and synthesized NaGdF4：Nd^3＋, Yb^3＋, Tm^3＋. magnetic nano- phosphors with combined dual-mode downconversion （DC） and upconversion （UC） photoluminescence upon 800 run excitation. Hexagonal-phase NaGdF4：Nd^3＋, Yb^3＋, Tm^3＋ nanocrystals （NCs） with an average size of 21 nm were synthesized using a solvothermal approach. Nd^3＋, Yb^3＋, Tm^3＋ triple-doped NaGdF4 NCs exhibit a broad range of photoluminescence peaks covering a near infrared first/second window （860-900, 1,000, and 1,060 nm）, and visible emission including blue （475 nm）, green （520 and 542 nm） and yellow （587 nm） after excitation at 800 nm. A mechanism involving circulation of energy over Gd^3＋ sublattices as bridge ions and final trapping by the initial activator ions （Nd^3＋） has been proposed. Penetration depth studies indicate that NIR emission is easily detected even at a large tissue thickness of 10 mm. These paramagnetic nanophosphors demonstrate a large magnetization value of 1.88 emu/g at 20 kOe and longitudinal relaxivity value of 1.2537 mM-1.S-1 as a Tl-weighted magnetic resonance imaging contrast agent. These NaGdF4：Nd^3＋, Yb^3＋ Tm^3＋ NCs are promising for applications in biological and magnetic resonance imaging.
基金supported by the Major Basic Research Program, Ministry of Science and Technology of China (2014CB239401)the National Natural Science Fundation of China (51422210, 21633009, 51629201 and 51521091)the Key Research Program of Frontier Sciences CAS (QYZDB-SSW-JSC039)
文摘Anatase TiO2 microspheres with exposed dominant {001} facets were doped with interstitial boron to have a concentration gradient with the maximum concentration at the surface. They were then further doped with substitutional nitrogen by heating in an ammonia atmosphere at different temperatures from 440 to 560℃ to give surface N concentrations ranging from 7.03 to 15.47 at%. The optical absorption, atomic and electronic structures and visible-light photoelectrochemical water oxidation activity of these materials were investigated. The maximum activity of the doped TiO2 was achieved at a nitrogen doping temperature of 520℃ that gave a high absorbance over the whole visible light region but with no defect-related background absorption.
基金UK Research and Innovation,MR/T043172/1Raymond G.P.McQuaid+4 种基金Department for Employment and Learning,Northern Ireland,USI-082Amit KumarEngineering and Physical Sciences Research Council,EP/S037179/1Amit KumarEP/LO15323/01,Nathan Black.
文摘The realization of a mixed-phase microstructure in strained BiFeO_(3)(BFO)thin films has led to numerous novel effects derived from the coexistence of the tetragonal-like monoclinic phase(T phase)and rhombohedral-like monoclinic phase(R phase).Strong strain and polarization diiferences between the phases should result in a high level of transformation plasticity,which enables the continuous alteration of the relative proportion of R and T states in response to external forces.Although the potential for utilizing such plasticity to control mixed-phase populations under external stimuli is evident,direct experi・mental evidence backed by equilibrium predictions has not yet been fully demonstrated.Here we demonstrate deterministic control of mixed-phase populations in an epitaxially strained BFO thin film through the application of localized stresses and electric fields in a reversible manne匚The results illustrate and rationalize deterministic control of mixed phases in strained BFO films,which could be crucial in tuning their functional properties.The findings also highlight a new multiparametric technique in the scanning probe lithography toolbox based on tip-assisted electric and strain field manipulation of functional properties that might find application beyond the ferroelectric domain and structural phase lithography.
文摘Intra- and interspecific variation in plant and insect traits can alter the strength and direction of insect-plant interactions, with outcomes modified by soil biotic and abiotic conditions. We used the potato aphid （Macrosiphum euphorbiae Thomas） feeding on cultivated Solanum tuberosum and wild Solanurn berthaulti to study the impact of water availability and plant mutualistic arbuscular mycorrhizal （AM） fungi on aphid performance and susceptibility to a parasitoid wasp （Aphidius ervi Haliday）. Plants were grown under glass with live or sterile AM fungal spores and supplied with sufficient or reduced water supply. Plants were infested with 1 of 3 genotypes ofM. euphorbiae or maintained as aphidfree controls; aphid abundance was scored after 1 week, after which aphid susceptibility to A. ervi was assayed explanta. Solarium tuberosum accumulated c. 20% more dry mass than S. berthaultii, and root mass of S. berthaultii was smallest under reduced water supply in the presence of AM fungi. Aphid abundance was lowest on S. berthaultii and highest for genotype ＂2＂ aphids; genotype ＂1＂ aphid density was particularly reduced on S. berthaultii. Aphid genotype ＂1＂ exhibited low susceptibility to parasitism and was attacked less frequently than the other two more susceptible aphid genotypes. Neither AM fungi nor water availability affected insect performance. Our study suggests a fitness trade-offin M. euphorbiae between parasitism resistance and aphid performance on poor quality Solarium hosts that warrants further exploration, and indicates the importance of accounting for genotype identity in determining the outcome of multitrophic interactions.
文摘Hydrogen is expected to play an important role in future transportation as a promising alternative clean energy source to carbon-based fuels. One of the key challenges to commercialize hydrogen energy is to develop appropriate onboard hydrogen storage systems, capable of charging and discharging large quantities of hydrogen with fast enough kinetics to meet commercial requirements. Metal organic framework （MOF） is a new type of inorganic and organic hybrid nanoporous particulate materials. Its diverse networks can enhance hydrogen storage through tuning the structure and property of MOFs. The MOF materials so far developed adsorb hydrogen through weak dispersion interactions, which allow significant quantity of hydrogen to be stored at cryogenic temperatures with fast kinetics. Novel MOFs are being developed to strengthen the interactions between hydrogen and MOFs in order to store hydrogen under ambient conditions. This review surveys the development of such candidate materials, their performance and future research needs.
基金The authors acknowledge the financial support of the National Natural Science Foundation of China （No. 71173088）.
文摘The present study investigates the influence of international oil prices on China＇s stock market returns across 29 different industries. The paper attempts to account for any structural breaks and nonlinearity in this relationship. The results reveal that the effect of changes in the international price of oil on stock returns differs substantially across industries. The stock returns of the coal chemical mining and oil industries are found to be positively affected by crude oil price movements. Conversely, electronics, food manufacturing, general equipment, pharmaceuticals, retail rubber and vehicle industries are found to be negatively affected by movements in the price of crude oil. The results of the estimations also suggest that the majority of Chinese industries have been significantly affected by oil prices since 2004. The influence of international oil prices on Chinese stocks also has a stronger effect in the presence of high volatility but the effect varies across industries.
基金support from the European Cluster of Advanced Laser Light Sources(EUCALL)project which has received funding from the European Union’s Horizon 2020 research and innovation programme under agreement No 654220support of the ELI-NP team and from ELI-NP PhaseⅡ,a project co-financed by the Romanian Government and European Union through the European Regional Development Fund–the Competitiveness Operational Programme(1/07.07.2016,COP,ID 1334)+5 种基金support of the ELI-Beamlines project,mainly sponsored by the project ELI–Extreme Light Infrastructure–Phase 2(CZ.02.1.01/0.0/0.0/15–008/0000162)through the European Regional Development Fundsupport of Planet Dive,a project that has received funding from the European Research Council(ERC)under the European Union’s Horizon 2020 research and innovation programme(grant agreement N.637748)supported by the Helmholtz Association under VHNG-1141support of the European Research Council Consolidator Grant ENSURE(ERC-2014CoG No.647554)Support by the Nanofabrication Facilities Rossendorfthe Institute of Ion Beam Physics and Materials Research,HZDR
文摘A number of laser facilities coming online all over the world promise the capability of high-power laser experiments with shot repetition rates between 1 and 10 Hz. Target availability and technical issues related to the interaction environment could become a bottleneck for the exploitation of such facilities. In this paper, we report on target needs for three different classes of experiments: dynamic compression physics, electron transport and isochoric heating, and laser-driven particle and radiation sources. We also review some of the most challenging issues in target fabrication and high repetition rate operation. Finally, we discuss current target supply strategies and future perspectives to establish a sustainable target provision infrastructure for advanced laser facilities.
文摘This review offers the first synthesis of the research on mixed-species groupings of arthropods and highlights the behavioral and evolutionary questions raised by such behavior.Mixed-species groups are commonly found in mammals and birds.Such groups are also observed in a large range of arthropod taxa independent of their level of sociality. Several examples are presented to highlight the mechanisms underlying such groupings, particularly the evidence for phylogenetie proximity between members that promotes cross-species recognition.The advantages offered by such aggregates are described and discussed.These advantages can be attributed to the increase in group size and could be identical to those of nonmixed groupings,but competition-cooperation dynamics might also be involved,and such effects may differ between homo-and heterospecific groups.We discuss three extreme cases of interspecific recognition that are likely involved in mixed-species groups as vectors for cross-species aggregation:tolerance behavior between two social species,one-way mechanism in which one species is attractive to others and two-way mechanism of mutual attraction.As shown in this review,the study of mixed-species groups offers biologists an interesting way to explore the frontiers of cooperation-competition, including the process of sympatric speciation.
