A Possible Quantum Spin Liquid Phase in the Kitaev–Hubbard Model

The quantum spin liquid(QSL) state of Kitaev-like materials, such as iridium oxides A_(2)IrO_(3) and α-RuCl_(3),has been explored in depth. The half-filled Kitaev–Hubbard model with bond-dependent hopping terms is used to describe the Kitaev-like materials, which is calculated using the state-of-the-art fermionic projected entangled pair states method. We find a QSL phase near the Mott insulator transition, which has a strong first-order transition to the semi-metal phase with the decrease of Hubbard U. We suggest that a promising approach to finding QSL states is by finding iridium oxides that are near the Mott insulator transition.

Lipolysaccharide-Induced Neuroinflammation Is Associated with Alzheimer-Like Amyloidogenic Axonal Pathology and Dendritic Degeneration in Rats

Chronic neuroinflammation is thought to play an etiological role in Alzheimer’s disease (AD) which is characterized pathologically by amyloid and tau formation, as well as neuritic dystrophy and synaptic degeneration. The causal relationship between these pathological events is a topic of ongoing research and discussion. Recent data from transgenic AD models point to a tight spatio-temporal link between neuritic and amyloid pathology, with the obligatory enzyme for β-amyloid (Aβ) production, namely β-secretase-1 (BACE1), being overexpressed in axon terminals undergoing dystrophic change. However, the axonal pathology inherent with BACE1 elevation seen in transgenic AD mice may be secondary to increased soluble Aβ in these genetically modified animals. Further, it is unclear whether the inflammation seen in AD is the result of , or the cause of neuritic dystrophy. Here we explored the occurrence of AD-like axonal and dendritic pathology in adult rat brains affected by LPS-induced chronic neuroinflammation. Unilateral intracerebral LPS injection induced prominent inflammatory response in glial cells in the ipsilateral cortex and hippocampal formation. BACE1 protein levels were elevated in the ipsilateral hippocampal lysates in the LPS-treated animals relative to controls. BACE1 immunoreactive dystrophic axons appeared in the LPS-treated ipsilateral cortex and hippocampal formation, colocalizing with increased β-amyloid precursor protein and Aβ antibody (4G8) immunolabeling. Quantitative Golgi studies revealed reduction of dendritic branching points and spine density on cortical layer III and hippocampal CA3 pyramidal neurons in the LPS-treated ipsilateral cerebrum. These findings suggest that Alzheimer-like amyloidogenic axonal pathology and dendritic degeneration occur in wildtype mammalian brain in partnership with neuroinflammation following LPS injection.

Attosecond spectroscopy for filming the ultrafast movies of atoms,molecules and solids

Three decades ago,a highly nonlinear nonpertubative phenomenon,now well-known as the high harmonic generation(HHG),was discovered when intense laser irradiates gaseous atoms.As the HHG produces broadband coherent radiation,it becomes the most promising source to obtain attosecond pulses.The door to the attosecond science was opened ever since.In this review,we will revisit the incredible adventure to the attoworld.Firstly,the progress of attosecond pulse generation is outlined.Then,we introduce the efforts on imaging the structures or filming the ultrafast dynamics of nuclei and electrons with unprecedented attosecond temporal and Angstrom spatial resolutions,utilizing the obtained attosecond pulses as well as the high harmonic spectrum itself.

Peculiar diffusion behavior of AlCl_(4) intercalated in graphite from nanosecond-long molecular dynamics simulations

The diffusion property of the intercalated species in the graphite materials is at the heart of the rate performance of graphite-based metal-ion secondary battery.Here we study the diffusion process of a AlCl_(4) molecule within graphite—a key component of a recently reported aluminum ion battery with excellent performance—via molecular dynamics(MD)simulations.Both ab-initio MD(AIMD)and semiempirical tight-binding MD simulations show that the diffusion process of the intercalated AlCl_(4) molecule becomes rather inhomogeneous,when the simulation time exceeds approximately 100 picoseconds.Specifically,during its migration in between graphene layers,the intercalated AlCl_(4) molecule may become stagnant occasionally,and then recovers its normal(fast)diffusion behavior after halting for a while.When this phenomenon occurs,the linear relationship of the mean squared displacement(MSD)versus the duration time is not fulfilled.We interpret this peculiar behavior as a manifestation of inadequate sampling of rare event(the stagnation of the molecule),which does not yet appear in short-time MD simulations.We further check the influence of strains present in graphite intercalated compounds(GIC)on the diffusion properties of AlCl_(4),and find that their presence in general slows down the diffusion of the intercalated molecule,and is detrimental to the rate performance of the GIC-based battery.

Intermetallic IrGa-IrO_(x) core-shell electrocatalysts for oxygen evolution Hide Author's Information

The development of high-performance Ir-based catalyst for electrocatalysis of oxygen evolution reaction(OER)in acidic media plays a critical role in realizing the commercialization of polymer electrolyte membrane-based water electrolyzer technology.Here we report a low-Ir core–shell OER electrocatalyst consisting of an intermetallic IrGa(IrGa-IMC)core and a partially oxidized Ir(IrOx)shell.In acidic electrolytes,the IrGa-IMC@IrOx core–shell catalysts exhibit a low overpotential of 272 mV at 10 mA·cm^(−2) with Ir loading of~20µg·cm^(−2) and a mass activity of 841 A·gIr^(−1) at 1.52 V,which is 3.6 times greater than that of commercial Ir/C(232 A·gIr^(−1))catalyst.We understand by the density functional theory(DFT)calculations that the enhanced OER activity of the IrGa-IMC@IrO_(x) catalysts is ascribed to the lifted degeneracy of Ir 5d electron of surface IrO_(x) sites induced by the intermetallic IrGa core,which increases the adsorption capacity of IrO_(x) layer for O and OH binding and eventually lowers the energy barrier of the OER rate-determining steps.

Attosecond probing and control of charge migration in carbon-chain molecule

In quantum mechanics,when an electron is quickly ripped off from a molecule,a superposition of new eigenstates of the cation creates an electron wave packet that governs the charge flow inside,which has been called charge migration(CM).Experimentally,extracting such dynamics at its natural(attosecond)timescale is quite difficult.We report the first such experiment in a linear carbon-chain molecule,butadiyne(C_(4)H_(2)),via high-harmonic spectroscopy(HHS).By employing advanced theoretical and computational tools,we showed that the wave packet and the CM of a single molecule are reconstructed from the harmonic spectra for each fixed-in-space angle of the molecule.For this onedimensional molecule,we calculate the center of charge <x>(t) to obtain v_(cm),to quantify the migration speed and how it depends on the orientation angle.The findings also uncover how the electron dynamics at the first few tens to hundreds of attoseconds depends on molecular structure.The method can be extended to other molecules where the HHS technique can be employed.

Measurement of molecular alignment with deep learningbased M-XFROG technique [Invited]

We demonstrate a deep-learning neural network(DNN) method for the measurement of molecular alignment by using the molecular-alignment-based cross-correlation polarization-gating frequency resolved optical gating(M-XFROG) technique.Our network has the capacity for direct measurement of molecular alignment from the FROG traces. In a proof-of-principle experiment, we have demonstrated our method in O^(2) molecules. With our method, the molecular alignment factor<cos^(2)θ>(t) of O_(2), impulsively excited by a pump pulse, was directly reconstructed. The accuracy and validity of the reconstruction have been verified by comparison with the simulations based on experimental parameters.

Characteristic research of regeneration process of particulate filter medium in vibrated fluidized bed

The vibrational fluidized bed is innovatively adopted to regenerate the particulate filter medium for the purification of crude syn-thesis gas from the coal gasification process.Characteristic research of vibrated fluidized beds during dust-containing particulate filter medium regeneration has been carried out.The ideal transport model of particulate filter medium on the distributor is estab-lished and verified by using experiments.The mean residence time of the particulate filter medium can be reduced by 72%from 5.5 to 1.5 min with an increase in the working frequency from 50 to 60 Hz.The thickness of the bed layer is linearly increased with the feeding rate of the particulate filter medium under ideal working conditions.The resistance models of the fluidizing air are built up and validated,and they can be used to calculate the pressure drop of the static bed layer of the particulate filter medium on the flu-idizing air distributor,which is the maximum value of the dynamic bed layer with the same thickness.The fluidizing air makes the mean residence time of the particulate filter medium decrease by 50%and reduces the difference in the particulate mean residence time under different feeding-rate conditions.The regeneration effect of dust-containing filter medium particles in a vibrated fluidized bed is evaluated.Fluidizing air with superficial velocity ranging from 0 to 0.6~0.9 m·s-1 makes the regeneration efficiency increase from 29.41%to 70.59~88.24%.This article provides a reference for the industrial application of a vibrated fluidized bed for the par-ticulate filter medium recycling system.

A Class of Hybrid DG/FV Methods for Conservation Laws III:Two-Dimensional Euler Equations

A concept of"static reconstruction"and"dynamic reconstruction"was introduced for higher-order(third-order or more)numerical methods in our previous work.Based on this concept,a class of hybrid DG/FV methods had been developed for one-dimensional conservation law using a"hybrid reconstruction"approach,and extended to two-dimensional scalar equations on triangular and Cartesian/triangular hybrid grids.In the hybrid DG/FV schemes,the lower-order derivatives of the piecewise polynomial are computed locally in a cell by the traditional DG method(called as"dynamic reconstruction"),while the higher-order derivatives are re-constructed by the"static reconstruction"of the FV method,using the known lower-order derivatives in the cell itself and in its adjacent neighboring cells.In this paper,the hybrid DG/FV schemes are extended to two-dimensional Euler equations on triangular and Cartesian/triangular hybrid grids.Some typical test cases are presented to demonstrate the performance of the hybrid DG/FV methods,including the standard vortex evolution problem with exact solution,isentropic vortex/weak shock wave interaction,subsonic flows past a circular cylinder and a three-element airfoil(30P30N),transonic flow past a NACA0012 airfoil.The accuracy study shows that the hybrid DG/FV method achieves the desired third-order accuracy,and the applications demonstrate that they can capture the flow structure accurately,and can reduce the CPU time and memory requirement greatly than the traditional DG method with the same order of accuracy.

Design and characteristic analysis of vibration feeding system for coal-gas dust-removal medium

A vibration feeder is a piece of equipment for rationing and conveying powder,particle and block materials.In order to test the regeneration performance of de-dusting medium for high-temperature coal gas,a set of de-dusting medium-feeding systems was designed quantitatively.The de-dusting medium-feeding system is used in the gasification process for cleaning coal gas.The system is mainly composed of a hopper unit,control unit and feeding unit.In order to optimize the feeding stability of the coal-gas dust-removal medium vibration feeding system,the setting and scope of the following design factors and operating factors are investigated.Specifically,it includes the influence of gate-valve-opening adjustment of the control unit on the feeding stability of a vibrating feeding system;the influence of the gap size of the dipleg of the control unit on the feeding sensitivity of the vibration system;the influence of the particle size of the de-dusting medium on the operating range of the vibrating feeding system;the influence of the digitization of the working-current indicator of electromagnetic vibrating feeders on measurement variation and the process variation of a vibration feeding system.This vibration feeding system can realize the function of precise and quantitative feeding of the de-dusting medium,which can meet the design requirements of subsequent experimental research.

High-throughput computation and structure prototype analysis for two-dimensional ferromagnetic materials

We perform high-throughput first-principles computations to search the high Curie temperature (T_(C)) two-dimensional ferromagnetic (2DFM) materials.We identify 79 2DFM materials and calculate their T_(C),in which Co_(2)F_(2) has the highest T_(C) = 541 K,well above the room temperature.The 79 2DFM materials are classified into different structural prototypes according to their structural similarity.We perform sure independence screening and sparsifying operator (SISSO) analysis to explore the relation between T_(C) and the material structures.The results suggest that the 2DFM materials with shorter distance between the magnetic atoms,larger local magnetic moments and more neighboring magnetic atoms are more likely to have higher T_(C).

CPFD simulation on particle behaviour in an entrained-flow gasifier

A computational particle fluid dynamics simulation model for entrained-flow gasification was established in this study.The simulation results agree with the experimental data.The detailed particle information and residence-time distribution were obtained by injecting particle tracers in the simulation.The results show that the particles in the gasifier can be classified into three flowing zones,i.e.a fast-flowing zone,a recirculation zone and a spreading zone.The criterion for this classification was also provided.The rapid gas expansion caused by the fast reactions plays a significant role in forming the particle stream into these three zones.It accelerates the particles in the centre of the gasifier while pushing the particles near the expansion edge into the gas recirculation.Also,the concentrated oxygen distribution in the gasifier results in the formation of high-and low-temperature regions.The particles in the fast-flowing zone flow directly through the high-temperature region and most of these particles in this zone were fully reacted with a short residence time.Since particles in the recirculation zone are in a relatively low-temperature region,most of these particles are not fully gasified,although with a long residence time.The rest of particles in the spreading zone show moderate properties between the above two zones.