With rapid development of urbanization and regional interaction and interdependence, regional urban agglomeration planning becomes more and more important in China, in order to promote integrated development of variou...With rapid development of urbanization and regional interaction and interdependence, regional urban agglomeration planning becomes more and more important in China, in order to promote integrated development of various cities with close interrelationship. However, it is still arguable academically on how to define the boundary or which cities to be included for the urban agglomeration of a region. This paper aims to shed lights on how to identify urban spheres of influence scientifically by introducing field modeling method and by practicing a case study on 168 cities in Central China. In our field modeling method, the influence intensities of cities were measured by a compre-ensive index and urban spheres of influence were represented spatially by field intensity. Then, their classification and spatial distribution characteristics of study area in 2007 were identified and explored by using GIS and statistical methods. The result showed that: 1) Wuhan is the absolute dominant city in Central China; 2) the provincial capital cities dominate their own provinces and there are no other lower grade agglomeration centers; and 3) the basic types of organization form of urban sphere of influence are single-polar type, agglomeration type, close-related group type and loose-related group type.展开更多
Slave-particle method is a powerful tool to tackle the correlation effect in quantum many-body physics. Although it has been successfully used to comprehend various intriguing problems, such as Mott metal-insulator tr...Slave-particle method is a powerful tool to tackle the correlation effect in quantum many-body physics. Although it has been successfully used to comprehend various intriguing problems, such as Mott metal-insulator transition and Kondo effect, there is still no convincing theory so far on the availability and limitation of this method. The abuse of slave-particle method may lead to wrong physics. As the simplest slave-particle method, Z2 slave spin, which is widely applied to many strongly correlated problems, is highly accessible and researchable. In this work, we will uncover the nature of the Z2 slave-spin method by studying a two-site Hubbard model. After exploring aspects of properties of this toy model, we make a comparative analysis of the results obtained by three methods:(i) slave-spin method on mean-field level,(ii) slave-spin method with gauge constraint, and(iii) the exact solution as a benchmark. We find that, protected by the particle-hole symmetry, the slave-spin mean-field method can recover the static properties of ground state exactly at half filling. Furthermore, in the parameter space where both U and T are small enough, the slave-spin mean-field method is also reliable in calculating the dynamic and thermal dynamic properties. However, when U or T is considerably large, the mean-field approximation gives ill-defined behaviors, which result from the unphysical states in the enlarged Hilbert space.These findings lead to our conclusion that the accuracy of slave particle can be guaranteed if we can exclude all unphysical states by enforcing gauge constraints. Our work demonstrates the promising prospect of slave-particle method in studying complex strongly correlated models with specific symmetry or in certain parameter space.展开更多
The optical properties of thermally annealed TiO_2 samples depend on their preparation process, and the TiO_2 thin films usually exist in the form of anatase or rutile or a mixture of the two phases. The electronic st...The optical properties of thermally annealed TiO_2 samples depend on their preparation process, and the TiO_2 thin films usually exist in the form of anatase or rutile or a mixture of the two phases. The electronic structures and optical properties of anatase and rutile TiO_2 are calculated by means of a first-principles generalized gradient approximation(GGA) +U approach. By introducing the Coulomb interactions on 3d orbitals of Ti atom(U^d) and 2p orbitals of O atom(U^p), we can reproduce the experimental values of the band gap. The optical properties of anatase and rutile TiO_2 are obtained by means of the GGA+U method, and the results are in good agreement with experiments and other theoretical data. Further, we present the comparison of the electronic structure, birefringence, and anisotropy between the two phases of TiO_2. Finally,the adaptability of the GGA+U approach has been discussed.展开更多
γ-Aminobutyric acid(GABA),plays a key role in all stages of life,also is considered the main inhibitory neurotransmitter.GABA activates two kind of membrane receptors known as GABAA and GABAB,the first one is respo...γ-Aminobutyric acid(GABA),plays a key role in all stages of life,also is considered the main inhibitory neurotransmitter.GABA activates two kind of membrane receptors known as GABAA and GABAB,the first one is responsible to render tonic inhibition by pentameric receptors containing α4-6,β3,δ,or ρ1-3 subunits,they are located at perisynaptic and/or in extrasynaptic regions.The biophysical properties of GABAA tonic inhibition have been related with cellular protection against excitotoxic injury and cell death in presence of excessive excitation.On this basis,GABAA tonic inhibition has been proposed as a potential target for therapeutic intervention of Huntington's disease.Huntington's disease is a neurodegenerative disorder caused by a genetic mutation of the huntingtin protein.For experimental studies of Huntington's disease mouse models have been developed,such as R6/1,R6/2,Hdh Q92,Hdh Q150,as well as YAC128.In all of them,some key experimental reports are focused on neostriatum.The neostriatum is considered as the most important connection between cerebral cortex and basal ganglia structures,its cytology display two pathways called direct and indirect constituted by medium sized spiny neurons expressing dopamine D1 and D2 receptors respectively,they display strong expression of many types of GABAA receptors,including tonic subunits.The studies about of GABAA tonic subunits and Huntington's disease into the neostriatum are rising in recent years,suggesting interesting changes in their expression and localization which can be used as a strategy to delay the cellular damage caused by the imbalance between excitation and inhibition,a hallmark of Huntington's disease.展开更多
We calculate the exclusive charmonium photo-production in the framework of color glass condensate.To obtain a good description of the vector meson production experimental data at HERA,we introduce a vector meson mass ...We calculate the exclusive charmonium photo-production in the framework of color glass condensate.To obtain a good description of the vector meson production experimental data at HERA,we introduce a vector meson mass dependent skewness factor into the skewness effect.Then we extend the skewness improved model to the LHC energies.The numerical results of our model are in good agreement with theΨ/Ψ and Ψ(2S)data in ultraperipheral proton-proton collisions at LHC,which show the significance of the vector meson mass-dependent skewness factor.A prediction of the exclusive charmonium photo-production in ultra-peripheral nucleus-nucleus collisions is performed since it can provide a good way to test the effectiveness of the color glass condensate.展开更多
Using an extended slave-boson method,we draw a global phase diagram summarizing both magnetic phases and paramagnetic(PM) topological insulators(TIs) in a three-dimensional topological Kondo insulator(TKI). By i...Using an extended slave-boson method,we draw a global phase diagram summarizing both magnetic phases and paramagnetic(PM) topological insulators(TIs) in a three-dimensional topological Kondo insulator(TKI). By including electron hopping(EH) up to the third neighbors, we identify four strong TI(STI) phases and two weak TI(WTI) phases. Then, the PM phase diagrams characterizing topological transitions between these TIs are depicted as functions of EH,f-electron energy level,and hybridization constant. We also find an insulator-metal transition from an STI phase that has surface Fermi rings and spin textures in qualitative agreement with the TKI candidate SmBs. In the weak hybridization regime, antiferromagnetic(AF) order naturally arises in the phase diagrams. Depending on how the magnetic boundary crosses the PM topological transition lines,AF phases are classified into the AF topological insulator(AFTI) and the non-topological AF insulator, according to their Z2 indices. In two small regions of parameter space, two distinct topological transition processes between AF phases occur, leading to two types of AFTIs showing distinguishable surface dispersions around their Dirac points.展开更多
Owing to the bistable character of the single molecular magnet (SMM), it can generate 100% spin-polarized currents even connected with normal (N) leads. In this work, we study the phonon-assisted spin current in N...Owing to the bistable character of the single molecular magnet (SMM), it can generate 100% spin-polarized currents even connected with normal (N) leads. In this work, we study the phonon-assisted spin current in N- SMM-N systems. We mainly focus on the interplay of SMM's bistable character and electron-phonon coupling. It is found that when SMM is trapped in one of the lowest bistable states, it can generate phonon-assisted spin- polarized currents. At the up-spin transport channel, it is accompanied by a phonon-assisted up-spin current, while at the down-spin transport channel, it is accompanied by a phonon-assisted down-spin current.展开更多
From an evolutionary point of view, reproduction timing is an important adaptation which enables the transfer of genetic properties, thus enabling species continuation. Rodents inhabiting arid environments need reliab...From an evolutionary point of view, reproduction timing is an important adaptation which enables the transfer of genetic properties, thus enabling species continuation. Rodents inhabiting arid environments need reliable cues for triggering their reproduction. Results of previous studies showed that increased dietary salinity plays an important role as an ultimate regulator for desert adapted rodents' reproductive system. The authors aimed discovering pathways by which high salinity can affect the reproductive system and metabolic status of desert adapted common spiny mice, Acomys cahirinus. Mice were challenged with osmotic stress, water source salinity increased gradually from 0.9% - 5% NaCI under short days (SD) and long days (LD). The authors assessed leptin and free fatty acid (FFA) levels using ELISA while, SYBR green technology was used for relative receptor expression (RQ) of target genes. Results revealed that serum levels of the hormone leptin were significantly (P 〈 0.05) reduced in salinity treated (ST) mice. Levels of FFA were significantly (P 〈 0.05) increased in LD- and SD-ST-males. In ST-SD females a significant increase (P 〈 0.05) in expression levels of leptin (Ob-Rt) mRNA receptor gene, in ovaries was noted. Aldosteron (Nr3c2) and vasopressin (AVP) mRNA receptor expression genes levels were significantly (P 〈 0.05) increased in both LD- and SD- ST- males.展开更多
We performed joint analysis of five cosmological models invoked to explain the accelerating expansion of the Universe.We used the data from strong gravitational lensing systems,locations of cosmic microwave background...We performed joint analysis of five cosmological models invoked to explain the accelerating expansion of the Universe.We used the data from strong gravitational lensing systems,locations of cosmic microwave background acoustic peaks and baryon acoustic oscillation data in combination with supernova Ia data(Union2 compilation).The observables we used came from both standard rulers and standard candles,so they had different parameter degeneracies and different restrictive powers in the parameter spaces of cosmological models.The best fits we obtained for the model parameters in joint analysis turned out to prefer cases effectively equivalent to the ΛCDM model.They were also in agreement with other combined studies performed by other authors on different sets of diagnostic probes.Information theoretic methods used to assess which model is most supported by the data lead to the conclusion that the concordance model ΛCDM is clearly preferred in joint analysis.The quintessence(both having constant or time varying equation of state) and Chaplygin gas get considerably less support from the data while the brane world(DGP) scenario is practically ruled out.展开更多
The phase diagram of HfO_2–TiO_2 system shows that when Ti content is less than 33.0 mol%, HfO_2–TiO_2 system is monoclinic; when Ti content increases from 33.0 mol% to 52.0 mol%, it is orthorhombic; when Ti content...The phase diagram of HfO_2–TiO_2 system shows that when Ti content is less than 33.0 mol%, HfO_2–TiO_2 system is monoclinic; when Ti content increases from 33.0 mol% to 52.0 mol%, it is orthorhombic; when Ti content reaches more than 52.0 mol%, it presents rutile phase. So, we choose the three phases of HfO_2–TiO_2 alloys with different Ti content values. The electronic structures and optical properties of monoclinic, orthorhombic and rutile phases of HfO_2–TiO_2 alloys are obtained by the first-principles generalized gradient approximation(GGA) +U approach, and the effects of Ti content and crystal structure on the electronic structures and optical properties of HfO_2–TiO_2 alloys are investigated. By introducing the Coulomb interactions of 5 d orbitals on Hf atom(U_1~d), those of 3 d orbitals on Ti atom(U_2~d), and those of 2 p orbitals on O atom(Up) simultaneously, we can improve the calculation values of the band gaps, where U_1~d, U_2~d, and Up values are 8.0 eV, 7.0 eV, and 6.0 eV for both the monoclinic phase and orthorhombic phase, and 8.0 eV, 7.0 eV, and 3.5 eV for the rutile phase. The electronic structures and optical properties of the HfO_2–TiO_2 alloys calculated by GGA +U_1~d(U_1~d= 8.0 eV) +U_2~d(U_2~d= 7.0 eV) +U^p(U^p= 6.0 eV or 3.5 eV) are compared with available experimental results.展开更多
Chronic epididymitis and varicocele are frequently observed genital disorders in men consulting for couple infertility, but their impact on semen characteristics at the time of infertility consultation is still a matt...Chronic epididymitis and varicocele are frequently observed genital disorders in men consulting for couple infertility, but their impact on semen characteristics at the time of infertility consultation is still a matter of debate. We investigated 652 male partners of couples who had their first infertility consultation between 1999 and 2015 in Argentina. Men with chronic epididymitis (n = 253), Grade III varicocele (n = 106), and both conditions (n = 125) were compared with a control group (n = 168) composed of men without these disorders or any other recognized causes of male infertility. We showed that men who presented isolated chronic epididymitis were more likely to have high percentages of low sperm motility and abnormal sperm morphology as well as a high number of white blood cells. Men with isolated Grade III varicocele had low sperm production and motility and an increased percentage of abnormal sperm morphology. Finally, men who simultaneously presented chronic epididymitis with Grade III varicocele had a low sperm motility and increased percentage of abnormal sperm morphology as well as a high number of white blood cells. Physical examination of the genital organs may identify common disorders, potentially involved as causal factors of patient's infertility. These disorders are associated with specific seminal profiles that should help in identifying the best treatment from the available therapeutic options, effectiveness, safety, and allowing as much as possible natural conception.展开更多
Background:Tomato is the second most important vegetable around the world.The processing of the fruit generates waste such as damaged tomatoes,pulp,skin,seeds,and tomato-derived products that contain valuable biomolec...Background:Tomato is the second most important vegetable around the world.The processing of the fruit generates waste such as damaged tomatoes,pulp,skin,seeds,and tomato-derived products that contain valuable biomolecules with functional and technological applications.Tomato fruit extracts,mainly from waste,possess bioactive molecules,such as lycopene,with important biological applications in some industries.Scope and approach:The objective of this review is to analyze,discuss and synthesize the technologies that have been used for the extraction and recovery of the main lycopene present in tomato waste.The revised methodologies expose valuable results in the number of carotenoids recovered through the application of solvents,microwave-assisted,ultrasound-assisted,enzymatic-assisted,extraction at high pressure,and supercritical fluids.However,the challenges continue concerning the quality of extracted compounds,economic accessibility,industrial reproducibility,and environmental safety.Key findings and conclusions:The tomato waste contains important bioactive molecules,which are of interest in the food,pharmacological,biotechnological,and cosmetic industries.The information revised in this contribution pretends to support new research lines concerning the formulation of novel tomato waste bio-based functional foods.However,it is necessary to further analyze the new extraction and recovery conditions to keep the functional properties of this by-product.展开更多
The electronic structures and optical properties of the monoclinic ZrO2 (m-ZrO2) are investigated by means of first-principles local density approximation (LDA) + U approach.Without on-site Coulomb interactions,the ba...The electronic structures and optical properties of the monoclinic ZrO2 (m-ZrO2) are investigated by means of first-principles local density approximation (LDA) + U approach.Without on-site Coulomb interactions,the band gap of m-ZrO2 is 3.60 eV,much lower than the experimental value (5.8 eV).By introducing the Coulomb interactions of 4d orbitals on Zr atom (Ud) and of 2p orbitals on O atom (Up),we can reproduce the experimental value of the band gap.The calculated dielectric function of m-ZrO2 exhibits a small shoulder at the edge of the band gap in its imaginary part,while in the tetragonal ZrO2 and cubic ZrO2 it is absent,which is consistent with the experimental observations.The origin of the shoulder is attributed to the difference of electronic structures near the edge of the valence and conduction bands.展开更多
The periodic Anderson model (PAM), where local electron orbitals interplay with itinerant electronic carriers, plays an essential role in our understanding of heavy fermion materials. Motivated by recent proposals f...The periodic Anderson model (PAM), where local electron orbitals interplay with itinerant electronic carriers, plays an essential role in our understanding of heavy fermion materials. Motivated by recent proposals for simulating the Kondo lattice model (KLM) in terms of alkaline-earth metal atoms, we take another step toward the simulation of PAM, which includes the crucial charge/valence fluctuation of local f-electrons beyond purely low-energy spin fluctuation in the KLM. To realize PAM, a transition induced by a suitable laser between the electronic excited and ground state of alkaline-earth metal atoms (^1S0←→^3P0) is introduced. This leads to effective hybridization between local electrons and conduction electrons in PAM. Generally, the SU(N) version of PAM can be realized by our proposal, which gives a unique opportunity to detect large-N physics without complexity in realistic materials. In the present work, high-temperature physical features of standard [SU(2)] PAM with harmonic trapping potential are analyzed by quantum Monte Carlo and dynamic mean-field theory, where the Mott/orbital-selective Mott state was found to coexist with metallic states. Indications for near-future experiments are provided. We expect our theoretical proposal and (hopefully) forthcoming experiments will deepen our understanding of heavy fermion systems. At the same time, we hope these will trigger further studies on related Mott physics, quantum criticality, and non-trivial topology in both the inhomogeneous and nonequilibrium realms.展开更多
In recent years, mteracting topological insulators have emerged as new frontiers in condensed matter physics, and the hotly studied topological Kondo insulator (TKI) is one of such prototypes. Although its zero-temper...In recent years, mteracting topological insulators have emerged as new frontiers in condensed matter physics, and the hotly studied topological Kondo insulator (TKI) is one of such prototypes. Although its zero-temperature ground-state has been widely investigated, the finite temperature physics on TKI is largely unknown. Here, we explore the finite temperature properties in a simplified model for TKI. namely the one-dimensional p-wave periodic Anderson model, with numerically exact determinant quantum Monte Carlo simulation. It is found that the topological Haldane phase established for groimdstate is still stable against small thermal fluctuation and its characteristic edge magnetization develops at low temperature. Such facts emphasize the robustness of (symmetry-protected) topological order against temperature effect, which always exists at real physical world. Moreover, we use the saturated low-T spin structure factor and the 1/T-law of susceptibility to detect the free edge spin moment, interestingly the low-temperature upturn behaxior of the latter one is similar to experimental finding in SniBg at T < 50 K. It implies that similar physical mechanism may work both for idealized models and realistic correlated electron materials.We have also identified an emergent energy scale Tcr. which signals a crossover into interesting low-T regime and seems to be the expected Ruderman-Kittel- Kasuya Yosida coupling. Finally, the collective Kondo screening effect has been examined and it is heavily reduced at boundary which may give a fruitful playground for novel physics beyond the wellestablished Haldane phase and topological band insulators.展开更多
One challenge in contemporary condensed matter physics is to understand unconventional electronic physics beyond the paradigm of Landau Fermi-liquid theory. Here, we present a perspective that posits that most such ex...One challenge in contemporary condensed matter physics is to understand unconventional electronic physics beyond the paradigm of Landau Fermi-liquid theory. Here, we present a perspective that posits that most such examples of unconventional electronic physics stem from restrictions on the degrees of freedom of quantum electrons in Landau Fermi liquids. Since the degrees of freedom are deeply connected to the system's symmetries and topology, these restrictions can thus be realized by external constraints or by interaction-driven processes via the following mechanisms: (i) symmetry breaking, (ii) new emergent symmetries, and (iii) nontrivial topology. Various examples of unconventionM elec- tronic physics beyond the reach of traditional Landau Fermi liquid theory are extensively investigated from this point of view. Our perspective yields basic pathways to study the breakdown of Landau Fermi liquids and also provides a guiding principle in the search for novel electronic systems and devices.展开更多
Motivated by a recent London penetration depth measurement [H. Kim, et al., Phys. Rev. Lett. 114, 027003 (2015)] and novel composite pairing scenario [O. Erten, R. Flint, and P. Coleman, Phys. Rev. Lett. 114, 027002...Motivated by a recent London penetration depth measurement [H. Kim, et al., Phys. Rev. Lett. 114, 027003 (2015)] and novel composite pairing scenario [O. Erten, R. Flint, and P. Coleman, Phys. Rev. Lett. 114, 027002 (2015)] of the Yb-doped heavy fermion superconductor CeCoIns, we revisit the issue of superfluid response in the microscopic heavy fermion lattice model. However, from the literature, an explicit expression for the superfluid response function in heavy fermion superconductors is rare. In this paper, we investigate the superfiuid density response function in the celebrated Kondo- Heisenberg model. To be specific, we derive the corresponding formalism from an effective fermionic large-N mean-field pairing Hamiltonian whose pairing interaction is assumed to originate from the effective local antiferromagnetic exchange interaction. Interestingly, we find that the physically correct, temperature-dependent superfiuid density formula can only be obtained if the external electromagnetic field is directly coupled to the heavy fermion quasi-particle rather than the bare conduction electron or local moment. Such a unique feature emphasizes the key role of the Kondo-screening-renormalized heavy quasi-particle for low-temperature/energy thermodynamics and transport behaviors. As an important application, the theoretical result is compared to an experimental measurement in heavy fermion superconductors CeCoIn5 and Yb-doped Ce1-xYbxCoIn5 with fairly good agreement and the transition of the pairing symmetry in the latter material is explained as a simple doping effect. In addition, the requisite formalism for the commonly encountered nonmagnetic impurity and non-local electrodynamic effect are developed. Inspired by the success in explaining classic 115-series heavy fermion superconductors, we expect the present theory will be applied to understand other heavy fermion superconductors such as CeCu2Si2 and more generic multi-band superconductors.展开更多
This paper reports the classification of 90 sample pavilions in Shanghai World Expo. An artificial intelligence based nonlinear clustering method known as Self-Organizing Map(SOM) has been used to classify expo pavili...This paper reports the classification of 90 sample pavilions in Shanghai World Expo. An artificial intelligence based nonlinear clustering method known as Self-Organizing Map(SOM) has been used to classify expo pavilions. SOM is an efficient tool for visualization of multidimensional data. To conduct the classification, four characteristics namely Hurst exponent for queue length, Hurst exponent for waiting time, mean queue length and mean waiting time have been applied. The classification results show that Shanghai World Expo pavilions can be optimally classified into four classes. This result will shed light on further studies that how to manage the queue of World Expo pavilions in the future.展开更多
基金Under the auspices of National Natural Science Foundation of China (No. 40971102)Knowledge Innovation Programs of Chinese Academy of Sciences (No. KZCX2-YW-322)Special Grant for Postgraduates' Scientific Innovation and Social Practice in 2008
文摘With rapid development of urbanization and regional interaction and interdependence, regional urban agglomeration planning becomes more and more important in China, in order to promote integrated development of various cities with close interrelationship. However, it is still arguable academically on how to define the boundary or which cities to be included for the urban agglomeration of a region. This paper aims to shed lights on how to identify urban spheres of influence scientifically by introducing field modeling method and by practicing a case study on 168 cities in Central China. In our field modeling method, the influence intensities of cities were measured by a compre-ensive index and urban spheres of influence were represented spatially by field intensity. Then, their classification and spatial distribution characteristics of study area in 2007 were identified and explored by using GIS and statistical methods. The result showed that: 1) Wuhan is the absolute dominant city in Central China; 2) the provincial capital cities dominate their own provinces and there are no other lower grade agglomeration centers; and 3) the basic types of organization form of urban sphere of influence are single-polar type, agglomeration type, close-related group type and loose-related group type.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11674139,11704166,and 11834005)the Fundamental Research Funds for the Central Universities,ChinaProgram for Changjiang Scholars and Innovative Research Team in University,China(Grant No.IRT-16R35)
文摘Slave-particle method is a powerful tool to tackle the correlation effect in quantum many-body physics. Although it has been successfully used to comprehend various intriguing problems, such as Mott metal-insulator transition and Kondo effect, there is still no convincing theory so far on the availability and limitation of this method. The abuse of slave-particle method may lead to wrong physics. As the simplest slave-particle method, Z2 slave spin, which is widely applied to many strongly correlated problems, is highly accessible and researchable. In this work, we will uncover the nature of the Z2 slave-spin method by studying a two-site Hubbard model. After exploring aspects of properties of this toy model, we make a comparative analysis of the results obtained by three methods:(i) slave-spin method on mean-field level,(ii) slave-spin method with gauge constraint, and(iii) the exact solution as a benchmark. We find that, protected by the particle-hole symmetry, the slave-spin mean-field method can recover the static properties of ground state exactly at half filling. Furthermore, in the parameter space where both U and T are small enough, the slave-spin mean-field method is also reliable in calculating the dynamic and thermal dynamic properties. However, when U or T is considerably large, the mean-field approximation gives ill-defined behaviors, which result from the unphysical states in the enlarged Hilbert space.These findings lead to our conclusion that the accuracy of slave particle can be guaranteed if we can exclude all unphysical states by enforcing gauge constraints. Our work demonstrates the promising prospect of slave-particle method in studying complex strongly correlated models with specific symmetry or in certain parameter space.
基金supported by the National Natural Science Foundation of China(Grant Nos.11672087,11272107,and 11402252)
文摘The optical properties of thermally annealed TiO_2 samples depend on their preparation process, and the TiO_2 thin films usually exist in the form of anatase or rutile or a mixture of the two phases. The electronic structures and optical properties of anatase and rutile TiO_2 are calculated by means of a first-principles generalized gradient approximation(GGA) +U approach. By introducing the Coulomb interactions on 3d orbitals of Ti atom(U^d) and 2p orbitals of O atom(U^p), we can reproduce the experimental values of the band gap. The optical properties of anatase and rutile TiO_2 are obtained by means of the GGA+U method, and the results are in good agreement with experiments and other theoretical data. Further, we present the comparison of the electronic structure, birefringence, and anisotropy between the two phases of TiO_2. Finally,the adaptability of the GGA+U approach has been discussed.
基金the programs for the postdoctoral fellowships-Chilean CONICYT-FONDECYT#3140218,Mexican CONACYT#164978 and DID-UACh S-2015-81Sistema Nacional de Investigadores#58512 to Abraham Rosas-Arellano+2 种基金supported by USACH PhD fellowshipsupported with a PhD fellowship from CONACYT(#299627)FONDECYT grants 1151206 and 1110571 to Maite A.Castro
文摘γ-Aminobutyric acid(GABA),plays a key role in all stages of life,also is considered the main inhibitory neurotransmitter.GABA activates two kind of membrane receptors known as GABAA and GABAB,the first one is responsible to render tonic inhibition by pentameric receptors containing α4-6,β3,δ,or ρ1-3 subunits,they are located at perisynaptic and/or in extrasynaptic regions.The biophysical properties of GABAA tonic inhibition have been related with cellular protection against excitotoxic injury and cell death in presence of excessive excitation.On this basis,GABAA tonic inhibition has been proposed as a potential target for therapeutic intervention of Huntington's disease.Huntington's disease is a neurodegenerative disorder caused by a genetic mutation of the huntingtin protein.For experimental studies of Huntington's disease mouse models have been developed,such as R6/1,R6/2,Hdh Q92,Hdh Q150,as well as YAC128.In all of them,some key experimental reports are focused on neostriatum.The neostriatum is considered as the most important connection between cerebral cortex and basal ganglia structures,its cytology display two pathways called direct and indirect constituted by medium sized spiny neurons expressing dopamine D1 and D2 receptors respectively,they display strong expression of many types of GABAA receptors,including tonic subunits.The studies about of GABAA tonic subunits and Huntington's disease into the neostriatum are rising in recent years,suggesting interesting changes in their expression and localization which can be used as a strategy to delay the cellular damage caused by the imbalance between excitation and inhibition,a hallmark of Huntington's disease.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11765005,11305040,IRG11521064,11775097 and 11465021the Fund of Science and Technology Department of Guizhou Province under Grant No[2015]2114the Education Department of Guizhou Province under Grant No.KY[2017]004
文摘We calculate the exclusive charmonium photo-production in the framework of color glass condensate.To obtain a good description of the vector meson production experimental data at HERA,we introduce a vector meson mass dependent skewness factor into the skewness effect.Then we extend the skewness improved model to the LHC energies.The numerical results of our model are in good agreement with theΨ/Ψ and Ψ(2S)data in ultraperipheral proton-proton collisions at LHC,which show the significance of the vector meson mass-dependent skewness factor.A prediction of the exclusive charmonium photo-production in ultra-peripheral nucleus-nucleus collisions is performed since it can provide a good way to test the effectiveness of the color glass condensate.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11764010,11504061,11564008,11704084,and 11704166the Natural Science Foundation of Guangxi Province under Grant Nos 2017GXNSFAA198169 and 2017GXNSFBA198115the SPC-Lab Research Fund under Grant No XKFZ201605
文摘Using an extended slave-boson method,we draw a global phase diagram summarizing both magnetic phases and paramagnetic(PM) topological insulators(TIs) in a three-dimensional topological Kondo insulator(TKI). By including electron hopping(EH) up to the third neighbors, we identify four strong TI(STI) phases and two weak TI(WTI) phases. Then, the PM phase diagrams characterizing topological transitions between these TIs are depicted as functions of EH,f-electron energy level,and hybridization constant. We also find an insulator-metal transition from an STI phase that has surface Fermi rings and spin textures in qualitative agreement with the TKI candidate SmBs. In the weak hybridization regime, antiferromagnetic(AF) order naturally arises in the phase diagrams. Depending on how the magnetic boundary crosses the PM topological transition lines,AF phases are classified into the AF topological insulator(AFTI) and the non-topological AF insulator, according to their Z2 indices. In two small regions of parameter space, two distinct topological transition processes between AF phases occur, leading to two types of AFTIs showing distinguishable surface dispersions around their Dirac points.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11504210,11504211,11504212,11274207,11274208,11174115 and 11325417the Key Program of the Ministry of Education of China under Grant No 212018+2 种基金Shanxi Provincial Scientific and Technological Project(2015031002-2)Shanxi Provincial Natural Science Foundation under Grant Nos2013011007-2 and 2013021010-5Outstanding Innovative Teams of Higher Learning Institutions of Shanxi Province
文摘Owing to the bistable character of the single molecular magnet (SMM), it can generate 100% spin-polarized currents even connected with normal (N) leads. In this work, we study the phonon-assisted spin current in N- SMM-N systems. We mainly focus on the interplay of SMM's bistable character and electron-phonon coupling. It is found that when SMM is trapped in one of the lowest bistable states, it can generate phonon-assisted spin- polarized currents. At the up-spin transport channel, it is accompanied by a phonon-assisted up-spin current, while at the down-spin transport channel, it is accompanied by a phonon-assisted down-spin current.
文摘From an evolutionary point of view, reproduction timing is an important adaptation which enables the transfer of genetic properties, thus enabling species continuation. Rodents inhabiting arid environments need reliable cues for triggering their reproduction. Results of previous studies showed that increased dietary salinity plays an important role as an ultimate regulator for desert adapted rodents' reproductive system. The authors aimed discovering pathways by which high salinity can affect the reproductive system and metabolic status of desert adapted common spiny mice, Acomys cahirinus. Mice were challenged with osmotic stress, water source salinity increased gradually from 0.9% - 5% NaCI under short days (SD) and long days (LD). The authors assessed leptin and free fatty acid (FFA) levels using ELISA while, SYBR green technology was used for relative receptor expression (RQ) of target genes. Results revealed that serum levels of the hormone leptin were significantly (P 〈 0.05) reduced in salinity treated (ST) mice. Levels of FFA were significantly (P 〈 0.05) increased in LD- and SD-ST-males. In ST-SD females a significant increase (P 〈 0.05) in expression levels of leptin (Ob-Rt) mRNA receptor gene, in ovaries was noted. Aldosteron (Nr3c2) and vasopressin (AVP) mRNA receptor expression genes levels were significantly (P 〈 0.05) increased in both LD- and SD- ST- males.
基金supported by the Polish Ministry of Science Grant No. N N203390034
文摘We performed joint analysis of five cosmological models invoked to explain the accelerating expansion of the Universe.We used the data from strong gravitational lensing systems,locations of cosmic microwave background acoustic peaks and baryon acoustic oscillation data in combination with supernova Ia data(Union2 compilation).The observables we used came from both standard rulers and standard candles,so they had different parameter degeneracies and different restrictive powers in the parameter spaces of cosmological models.The best fits we obtained for the model parameters in joint analysis turned out to prefer cases effectively equivalent to the ΛCDM model.They were also in agreement with other combined studies performed by other authors on different sets of diagnostic probes.Information theoretic methods used to assess which model is most supported by the data lead to the conclusion that the concordance model ΛCDM is clearly preferred in joint analysis.The quintessence(both having constant or time varying equation of state) and Chaplygin gas get considerably less support from the data while the brane world(DGP) scenario is practically ruled out.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11672087,11502058,and 11402252)
文摘The phase diagram of HfO_2–TiO_2 system shows that when Ti content is less than 33.0 mol%, HfO_2–TiO_2 system is monoclinic; when Ti content increases from 33.0 mol% to 52.0 mol%, it is orthorhombic; when Ti content reaches more than 52.0 mol%, it presents rutile phase. So, we choose the three phases of HfO_2–TiO_2 alloys with different Ti content values. The electronic structures and optical properties of monoclinic, orthorhombic and rutile phases of HfO_2–TiO_2 alloys are obtained by the first-principles generalized gradient approximation(GGA) +U approach, and the effects of Ti content and crystal structure on the electronic structures and optical properties of HfO_2–TiO_2 alloys are investigated. By introducing the Coulomb interactions of 5 d orbitals on Hf atom(U_1~d), those of 3 d orbitals on Ti atom(U_2~d), and those of 2 p orbitals on O atom(Up) simultaneously, we can improve the calculation values of the band gaps, where U_1~d, U_2~d, and Up values are 8.0 eV, 7.0 eV, and 6.0 eV for both the monoclinic phase and orthorhombic phase, and 8.0 eV, 7.0 eV, and 3.5 eV for the rutile phase. The electronic structures and optical properties of the HfO_2–TiO_2 alloys calculated by GGA +U_1~d(U_1~d= 8.0 eV) +U_2~d(U_2~d= 7.0 eV) +U^p(U^p= 6.0 eV or 3.5 eV) are compared with available experimental results.
文摘Chronic epididymitis and varicocele are frequently observed genital disorders in men consulting for couple infertility, but their impact on semen characteristics at the time of infertility consultation is still a matter of debate. We investigated 652 male partners of couples who had their first infertility consultation between 1999 and 2015 in Argentina. Men with chronic epididymitis (n = 253), Grade III varicocele (n = 106), and both conditions (n = 125) were compared with a control group (n = 168) composed of men without these disorders or any other recognized causes of male infertility. We showed that men who presented isolated chronic epididymitis were more likely to have high percentages of low sperm motility and abnormal sperm morphology as well as a high number of white blood cells. Men with isolated Grade III varicocele had low sperm production and motility and an increased percentage of abnormal sperm morphology. Finally, men who simultaneously presented chronic epididymitis with Grade III varicocele had a low sperm motility and increased percentage of abnormal sperm morphology as well as a high number of white blood cells. Physical examination of the genital organs may identify common disorders, potentially involved as causal factors of patient's infertility. These disorders are associated with specific seminal profiles that should help in identifying the best treatment from the available therapeutic options, effectiveness, safety, and allowing as much as possible natural conception.
文摘Background:Tomato is the second most important vegetable around the world.The processing of the fruit generates waste such as damaged tomatoes,pulp,skin,seeds,and tomato-derived products that contain valuable biomolecules with functional and technological applications.Tomato fruit extracts,mainly from waste,possess bioactive molecules,such as lycopene,with important biological applications in some industries.Scope and approach:The objective of this review is to analyze,discuss and synthesize the technologies that have been used for the extraction and recovery of the main lycopene present in tomato waste.The revised methodologies expose valuable results in the number of carotenoids recovered through the application of solvents,microwave-assisted,ultrasound-assisted,enzymatic-assisted,extraction at high pressure,and supercritical fluids.However,the challenges continue concerning the quality of extracted compounds,economic accessibility,industrial reproducibility,and environmental safety.Key findings and conclusions:The tomato waste contains important bioactive molecules,which are of interest in the food,pharmacological,biotechnological,and cosmetic industries.The information revised in this contribution pretends to support new research lines concerning the formulation of novel tomato waste bio-based functional foods.However,it is necessary to further analyze the new extraction and recovery conditions to keep the functional properties of this by-product.
基金the National Natural Science Foundation of China,the Strategic Programs for Innovative Research,the Computational Materials Science Initiative,the Yukawa International Program for Quark-Hadron Sciences at YITP,Kyoto University
文摘The electronic structures and optical properties of the monoclinic ZrO2 (m-ZrO2) are investigated by means of first-principles local density approximation (LDA) + U approach.Without on-site Coulomb interactions,the band gap of m-ZrO2 is 3.60 eV,much lower than the experimental value (5.8 eV).By introducing the Coulomb interactions of 4d orbitals on Zr atom (Ud) and of 2p orbitals on O atom (Up),we can reproduce the experimental value of the band gap.The calculated dielectric function of m-ZrO2 exhibits a small shoulder at the edge of the band gap in its imaginary part,while in the tetragonal ZrO2 and cubic ZrO2 it is absent,which is consistent with the experimental observations.The origin of the shoulder is attributed to the difference of electronic structures near the edge of the valence and conduction bands.
基金Acknowledgements We thank Congjun Wu for helpful discussion on SU(N) physics, and Ren Zhang for discussions about orbital Feshbach Resonance. This research was supported in part by the National Natural Science Foundation of China under Grant Nos. 11325417, 11674139, and 11504061, the China Postdoctoral Science Foundation, and the Foundation of LCP.
文摘The periodic Anderson model (PAM), where local electron orbitals interplay with itinerant electronic carriers, plays an essential role in our understanding of heavy fermion materials. Motivated by recent proposals for simulating the Kondo lattice model (KLM) in terms of alkaline-earth metal atoms, we take another step toward the simulation of PAM, which includes the crucial charge/valence fluctuation of local f-electrons beyond purely low-energy spin fluctuation in the KLM. To realize PAM, a transition induced by a suitable laser between the electronic excited and ground state of alkaline-earth metal atoms (^1S0←→^3P0) is introduced. This leads to effective hybridization between local electrons and conduction electrons in PAM. Generally, the SU(N) version of PAM can be realized by our proposal, which gives a unique opportunity to detect large-N physics without complexity in realistic materials. In the present work, high-temperature physical features of standard [SU(2)] PAM with harmonic trapping potential are analyzed by quantum Monte Carlo and dynamic mean-field theory, where the Mott/orbital-selective Mott state was found to coexist with metallic states. Indications for near-future experiments are provided. We expect our theoretical proposal and (hopefully) forthcoming experiments will deepen our understanding of heavy fermion systems. At the same time, we hope these will trigger further studies on related Mott physics, quantum criticality, and non-trivial topology in both the inhomogeneous and nonequilibrium realms.
基金the National Natural Science Foundation of China under Grant Nos. 11325417, 11674139, and 11704166the Fundamental Research Funds for the Central Universities, Science Challenge Project under Grant No. JCKY2016212A502, SPC-Lab Research Fund (NO. XKFZ201605)the Foundation of LCP.
文摘In recent years, mteracting topological insulators have emerged as new frontiers in condensed matter physics, and the hotly studied topological Kondo insulator (TKI) is one of such prototypes. Although its zero-temperature ground-state has been widely investigated, the finite temperature physics on TKI is largely unknown. Here, we explore the finite temperature properties in a simplified model for TKI. namely the one-dimensional p-wave periodic Anderson model, with numerically exact determinant quantum Monte Carlo simulation. It is found that the topological Haldane phase established for groimdstate is still stable against small thermal fluctuation and its characteristic edge magnetization develops at low temperature. Such facts emphasize the robustness of (symmetry-protected) topological order against temperature effect, which always exists at real physical world. Moreover, we use the saturated low-T spin structure factor and the 1/T-law of susceptibility to detect the free edge spin moment, interestingly the low-temperature upturn behaxior of the latter one is similar to experimental finding in SniBg at T < 50 K. It implies that similar physical mechanism may work both for idealized models and realistic correlated electron materials.We have also identified an emergent energy scale Tcr. which signals a crossover into interesting low-T regime and seems to be the expected Ruderman-Kittel- Kasuya Yosida coupling. Finally, the collective Kondo screening effect has been examined and it is heavily reduced at boundary which may give a fruitful playground for novel physics beyond the wellestablished Haldane phase and topological band insulators.
基金We thank Tao Li and Yin Zhong for help- ful discussions. H. T. Lu acknowledges the support of the National Natural Science Foundation of China (Grant No. 11474136). Y. H. Su was partially supported by the Natural Science Foundation of China (Grant No. 11774299) and the Natural Science Foundation of Shandong Province (Grant No. ZR2017MA033).
文摘One challenge in contemporary condensed matter physics is to understand unconventional electronic physics beyond the paradigm of Landau Fermi-liquid theory. Here, we present a perspective that posits that most such examples of unconventional electronic physics stem from restrictions on the degrees of freedom of quantum electrons in Landau Fermi liquids. Since the degrees of freedom are deeply connected to the system's symmetries and topology, these restrictions can thus be realized by external constraints or by interaction-driven processes via the following mechanisms: (i) symmetry breaking, (ii) new emergent symmetries, and (iii) nontrivial topology. Various examples of unconventionM elec- tronic physics beyond the reach of traditional Landau Fermi liquid theory are extensively investigated from this point of view. Our perspective yields basic pathways to study the breakdown of Landau Fermi liquids and also provides a guiding principle in the search for novel electronic systems and devices.
文摘Motivated by a recent London penetration depth measurement [H. Kim, et al., Phys. Rev. Lett. 114, 027003 (2015)] and novel composite pairing scenario [O. Erten, R. Flint, and P. Coleman, Phys. Rev. Lett. 114, 027002 (2015)] of the Yb-doped heavy fermion superconductor CeCoIns, we revisit the issue of superfluid response in the microscopic heavy fermion lattice model. However, from the literature, an explicit expression for the superfluid response function in heavy fermion superconductors is rare. In this paper, we investigate the superfiuid density response function in the celebrated Kondo- Heisenberg model. To be specific, we derive the corresponding formalism from an effective fermionic large-N mean-field pairing Hamiltonian whose pairing interaction is assumed to originate from the effective local antiferromagnetic exchange interaction. Interestingly, we find that the physically correct, temperature-dependent superfiuid density formula can only be obtained if the external electromagnetic field is directly coupled to the heavy fermion quasi-particle rather than the bare conduction electron or local moment. Such a unique feature emphasizes the key role of the Kondo-screening-renormalized heavy quasi-particle for low-temperature/energy thermodynamics and transport behaviors. As an important application, the theoretical result is compared to an experimental measurement in heavy fermion superconductors CeCoIn5 and Yb-doped Ce1-xYbxCoIn5 with fairly good agreement and the transition of the pairing symmetry in the latter material is explained as a simple doping effect. In addition, the requisite formalism for the commonly encountered nonmagnetic impurity and non-local electrodynamic effect are developed. Inspired by the success in explaining classic 115-series heavy fermion superconductors, we expect the present theory will be applied to understand other heavy fermion superconductors such as CeCu2Si2 and more generic multi-band superconductors.
基金supported by 973 Research Program under Grant No.2010CB731500the National Natural Science Foundation of China under Grant Nos.71403262,91024010,91324009+1 种基金Innovative Team Program under Grant No.GH13041Major Program of Institute of Policy and Management,Chinese Academy of Sciences under Grant No.Y201201Z06
文摘This paper reports the classification of 90 sample pavilions in Shanghai World Expo. An artificial intelligence based nonlinear clustering method known as Self-Organizing Map(SOM) has been used to classify expo pavilions. SOM is an efficient tool for visualization of multidimensional data. To conduct the classification, four characteristics namely Hurst exponent for queue length, Hurst exponent for waiting time, mean queue length and mean waiting time have been applied. The classification results show that Shanghai World Expo pavilions can be optimally classified into four classes. This result will shed light on further studies that how to manage the queue of World Expo pavilions in the future.