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Abstract Magnetic toroidicity is an uncommon type of magnetic structure in solid-state materials. Here, we experimentally demonstrate that collinear spins in a material with R-3 lattice symmetry can host a significant magnetic toroidicity, even parallel to the ordered spins. Taking advantage of a single crystal sample of CoTe6O13 with an R-3 space group and a Co2+ triangular sublattice, temperature-dependent magnetic, thermodynamic, and neutron diffraction results reveal A-type antiferromagnetic order below 19.5 K, with magnetic point group -3′ and k = (0,0,0). Our symmetry analysis suggests that the missing mirror symmetry in the lattice could lead to the local spin canting for a toroidal moment along the c axis. Experimentally, we observe a large off-diagonal magnetoelectric coefficient of 41.2 ps/m that evidences the magnetic toroidicity. In addition, the paramagnetic state exhibits a large effective moment per Co2+, indicating that the magnetic moment in CoTe6O13 has a significant orbital contribution. CoTe6O13 embodies an excellent opportunity for the study of next-generation functional magnetoelectric materials.

Plants interact with complex microbial communities in which microorganisms play different roles in plant development and health. While certain microorganisms may cause disease, others promote nutrient uptake and resistance to stresses through a variety of mechanisms. Developing plant protection measures requires a deeper comprehension of the factors that influence multitrophic interactions and the organization of phyllospheric communities. High-throughput sequencing was used in this work to investigate the effects of climate variables and bacterial wildfire disease on the bacterial community’s composition and assembly in the phyllosphere of tobacco (Nicotiana tabacum L.). The samples from June (M1), July (M2), August (M3), and September (M4) formed statistically separate clusters. The assembly of the whole bacterial population was mostly influenced by stochastic processes. PICRUSt2 predictions revealed genes enriched in the M3, a period when the plant wildfire disease index reached climax, were associated with the development of the wildfire disease (secretion of virulence factor), the enhanced metabolic capacity and environmental adaption. The M3 and M4 microbial communities have more intricate molecular ecological networks (MENs), bursting with interconnections within a densely networked bacterial population. The relative abundances of plant-beneficial and antagonistic microbes Clostridiales, Bacillales, Lactobacillales, and Sphingobacteriales, showed significant decrease in severally diseased sample (M3) compared to the pre-diseased samples (M1/M2). Following the results of MENs, we further test if the correlating bacterial pairs within the MEN have the possibility to share functional genes and we have unraveled 139 entries of such horizontal gene transfer (HGT) events, highlighting the significance of HGT in shaping the adaptive traits of plant-associated bacteria across the MENs, particularly in relation to host colonization and pathogenicity.

Abstract Axolotl (Ambystoma mexicanum) is an excellent model for investigating regeneration, the interaction between regenerative and developmental processes, comparative genomics, and evolution. The brain, which serves as the material basis of consciousness, learning, memory, and behavior, is the most complex and advanced organ in axolotl. The modulation of transcription factors is a crucial aspect in determining the function of diverse regions within the brain. There is, however, no comprehensive understanding of the gene regulatory network of axolotl brain regions. Here, we utilized single-cell ATAC sequencing to generate the chromatin accessibility landscapes of 81,199 cells from the olfactory bulb, telencephalon, diencephalon and mesencephalon, hypothalamus and pituitary, and the rhombencephalon. Based on these data, we identified key transcription factors specific to distinct cell types and compared cell type functions across brain regions. Our results provide a foundation for comprehensive analysis of gene regulatory programs, which are valuable for future studies of axolotl brain development, regeneration, and evolution, as well as on the mechanisms underlying cell-type diversity in vertebrate brains.

Abstract The realization of graphene gapped states with large on/off ratios over wide doping ranges remains challenging. Here, we investigate heterostructures based on Bernal-stacked bilayer graphene (BLG) atop few-layered CrOCl, exhibiting an over-1-GΩ-resistance insulating state in a widely accessible gate voltage range. The insulating state could be switched into a metallic state with an on/off ratio up to 107 by applying an in-plane electric field, heating, or gating. We tentatively associate the observed behavior to the formation of a surface state in CrOCl under vertical electric fields, promoting electron–electron (e–e) interactions in BLG via long-range Coulomb coupling. Consequently, at the charge neutrality point, a crossover from single particle insulating behavior to an unconventional correlated insulator is enabled, below an onset temperature. We demonstrate the application of the insulating state for the realization of a logic inverter operating at low temperatures. Our findings pave the way for future engineering of quantum electronic states based on interfacial charge coupling.

Band structure modulation may drive topological phase transitions, but tuning topological phases within the same material is challenging. Here, quantum oscillations are used to map the Berry phase and Dirac bandgap closing and reopening in a strain-induced topological insulator phase transition in ZrTe5.

Abstract Placenta plays essential role in successful pregnancy, as the most important organ connecting and interplaying between mother and fetus. However, the cellular characteristics and molecular interaction of cell populations within the fetomaternal interface is still poorly understood. Here, we surveyed the single-cell transcriptomic landscape of human full-term placenta and revealed the heterogeneity of cytotrophoblast cell (CTB) and stromal cell (STR) with the fetal/maternal origin consecutively localized from fetal section (FS), middle section (Mid_S) to maternal section (Mat_S) of maternal–fetal interface. Then, we highlighted a subpopulation of CTB, named trophoblast progenitor-like cells (TPLCs) existed in the full-term placenta and mainly distributed in Mid_S, with high expression of a pool of putative cell surface markers. Further, we revealed the putative key transcription factor PRDM6 that might promote the differentiation of endovascular extravillous trophoblast cells (enEVT) by inhibiting cell proliferation, and down-regulation of PRDM6 might lead to an abnormal enEVT differentiation process in PE. Together, our study offers important resources for better understanding of human placenta and stem cell-based therapy, and provides new insights on the study of tissue heterogeneity, the clinical prevention and control of PE as well as the maternal–fetal interface.

In this paper, the ultrasonic extraction technology of Forsythia suspensa leaves was optimized based on multi-index components. The contents of forsythioside A, forsythin and rutin were determined by high performance liquid chromatography (HPLC). The ethanol concentration, liquid-solid ratio, extraction time and extraction temperature were taken as the factors. The entropy weight method was used to obtain comprehensive score by calculating the weight coefficient of each index. Subsequently, the comprehensive score was taken as the index. Finally the Box-Behnken response surface methodology was adopted to optimize the extraction process. The optimum extraction conditions of Forsythia suspensa leaves were as follow: Ethanol concentration 50%, liquid to material ratio 28:1 mL/g, extraction temperature 51 ℃, extraction time 25 min. The results of the validation tests showed that under the optimal conditions, the extraction amount of forsythioside A, forsythin and rutin were 69.69, 22.87 and 22.46 mg/g, respectively, the RSD was less than 3% and comprehensive score was 32.18. The extraction technology was stable and feasible, and the extraction quantity of active components was high. It was suitable for the extraction of Forsythia suspensa leaves.

Both biotic and abiotic factors continually affect the phyllospheric ecology of plants. A better understanding of the drivers of phyllospheric community structure and multitrophic interactions is vital for developing plant protection strategies. In this study, 16S rRNA high-throughput sequencing was applied to study how summer climatic factors and bacterial wildfire disease have affected the composition and assembly of the bacterial community of tobacco (Nicotiana tabacum L.) phyllosphere. Our results indicated that three time series groups (T1, T2 and T3) formed significantly distinct clusters. The neutral community model (NCM) and beta nearest taxon index (betaNTI) demonstrated that the overall bacterial community assembly was predominantly driven by stochastic processes. Variance partitioning analysis (VPA) further showed that the complete set of the morbidity and climatic variables together could explain 35.7% of the variation of bacterial communities. The node numbers of the molecular ecological networks (MENs) showed an overall uptrend from T1 to T3. Besides, Pseudomonas is the keystone taxa in the MENs from T1 to T3. PICRUSt2 predictions revealed significantly more abundant genes of osmoprotectant biosynthesis/transport in T2, and more genes for pathogenicity and metabolizing organic substrate in T3. Together, this study provides insights into spatiotemporal patterns, processes and response mechanisms underlying the phyllospheric bacterial community.

Graphene and topological insulators can feature a unique quantum Hall state with a filling factor of ν = 0 that supplies a wealth of information about the nature of the underlying electronic states. Here, we report on the observation of a ν = 0 Hall state in magnetotransport experiments on a 20-nm-thin, (001)-oriented cadmium arsenide film that is tuned by a gate voltage. While cadmium arsenide is a topological semimetal as a bulk material, thin films can host topological insulator phases. At high magnetic fields, we observe a highly resistive ν = 0 Hall state that we attribute to a widening gap between two zeroth Landau levels as the magnetic field is increased. We discuss possible scenarios that could give rise to the lifting of the degeneracy of zeroth Landau levels. Our results are most consistent with a scenario of hybridization of the topological surface states induced by quantum confinement.

Purpose: To report a case of saccadic intrusions in a 9-month-old under the context of non-accidental trauma. Observations: A 9-month-old female presented with the eye finding of intermittent ocular flutter. Upon imaging for neuroblastoma, she was discovered to have bilateral supratentorial subdural hematomas with internal septations, moderate mass effect on adjacent cerebral parenchyma, pachymeningeal and tentorial enhancement, and cortical vein thrombosis. This constellation of findings was concerning for non-accidental trauma. Conclusions and importance: Although an extremely rare occurrence, ocular flutter may be a presenting sign in non-accidental trauma, and imaging should absolutely be considered under such circumstances.

Pediatric vision screening detects children at risk for visual conditions with the goal of connecting those in need with an eye care provider for evaluation and treatment. The primary aim for vision screening in younger children is the detection of those at risk for amblyopia, which can result in irreversible vision loss if left untreated. In older children, screening goals broaden to include the detection of risk for uncorrected refractive error. In the United States, professional organization guidelines and state-mandated requirements for vision screening vary widely across both the timing and components of screening. In this article, we describe the goals and components of pediatric vision screenings, current challenges, novel approaches to providing follow-up services through school-based vision programs, and future directions.

We propose a new type of spontaneous symmetry breaking phase caused by softening of the transverse acoustic phonon modes through electron-phonon coupling. These new phases include the shear density wave and self-twisting wave, which are caused by softening of linearly and circularly polarized acoustic phonon modes, respectively. We propose that two of the topological semimetal systems in the quantum limit, where the electrons only occupy the lowest Landau bands under external magnetic field, will be the perfect systems to realize these new phases. Exotic physical effects will be induced in these new phases, including the 3D quantum Hall effect, chiral standing acoustic wave, magnetoacoustic effects, and chiral phonon correction to the Einstein–de Hass effect.

Mesenchymal stem/stromal cells derived from placenta (PMSCs) are an attractive source for regenerative medicine because of their multidifferentiation potential and immunomodulatory capabilities. However, the cellular and molecular heterogeneity of PMSCs has not been fully characterized. Here, we applied single-cell RNA sequencing (scRNA-seq) and assay for transposase-accessible chromatin sequencing (scATAC-seq) techniques to cultured PMSCs from human full-term placenta. Based on the inferred characteristics of cell clusters, we identify several distinct subsets of PMSCs with specific characteristics, including immunomodulatory-potential and highly proliferative cell states. Furthermore, integrative analysis of gene expression and chromatin accessibility showed a clearer chromatin accessibility signature than those at the transcriptional level on immunomodulatory-related genes. Cell cycle gene-related heterogeneity can be more easily distinguished at the transcriptional than the chromatin accessibility level in PMSCs. We further reveal putative subset-specific cis-regulatory elements regulating the expression of immunomodulatory- and proliferation-related genes in the immunomodulatory-potential and proliferative subpopulations, respectively. Moreover, we infer a novel transcription factor PRDM1, which might play a crucial role in maintaining immunomodulatory capability by activating PRDM1-regulon loop. Collectively, our study first provides a comprehensive and integrative view of the transcriptomic and epigenomic features of PMSCs, which paves the way for a deeper understanding of cellular heterogeneity and offers fundamental biological insight of PMSC subset-based cell therapy.

The existence of a topological bulk-boundary correspondence for Dirac semimetals has remained an open question. Here, Wieder et al. predict one-dimensional hinge states originating from bulk three-dimensional Dirac points in solid-state Dirac semimetals, revealing condensed matter Dirac fermions to be higher-order topological.

For assembly of trans-scale micro-device capsule fill tube assemblies (CFTA) for inertial confinement fusion (ICF) targets, a high-precision space assembly approach based on micro-vision is proposed in this paper. The approach consists of three modules: (i) a posture alignment module based on a multi-vision monitoring model that is designed to align two trans-scale micro-parts in 5DOF while one micro-part is in ten microns and the other one is in hundreds of microns; (ii) an insertion depth control module based on a proposed local deformation detection method to control micro-part insertion depth; (iii) a glue mass control module based on simulation research that is designed to control glue mass quantitatively and to bond micro-parts together. A series of experiments were conducted and experimental results reveal that attitude alignment control error is less than ±0.3°, position alignment control error is less than ±5 µm, and insertion depth control error is less than ±5 μm. Deviation of glue spot diameter is controlled at less than 15 μm. A CFTA was assembled based on the proposed approach, the position error in 3D space measured by computerized tomography (CT) is less than 5 μm, and glue spot diameter at the joint is 56 μm. Through volume calculation by the cone calculation formula, the glue mass is about 23 PL when the cone height is half the diameter.

The sulfonate compound 2,3-dihydroxypropane-1-sulfonate (DHPS) is one of the most abundant organic sulfur compounds in the biosphere. DHPS derived from dietary intake could be transformed into sulfide by intestinal microbiota and thus impacts human health. However, little is known about its sulfur transformation and subsequent impacts in marine environment. In this study, laboratory-culturing was combined with targeted metabolomic, chemical fluorescence probing, and comparative proteomic methods to examine the bioavailability of chiral DHPS (R and S isomers) for bacteria belonging to the marine Roseobacter clade. The metabolic potential of DHPS in bacteria was further assessed based on genomic analysis. Roseobacter members Ruegeria pomeroyi DSS-3, Dinoroseobacter shibae DFL 12, and Roseobacter denitrificans OCh 114 could utilize chiral DHPS for growth, producing sulfite. They all contained a similar gene cluster for DHPS metabolism but differed in the genes encoding enzymes for desulfonation. There was no significant difference in the growth rate and DHPS consumption rate for R. pomeroyi DSS-3 between R- and S-DHPS cultures, with few proteins expressed differentially were found. Proteomic data suggested that a series of hydrogenases oxidized DHPS, after which desulfonation could proceed via three distinct enzymatic pathways. Strain R. pomeroyi DSS-3 completed the desulfonation via L-cysteate sulfo-lyase, while D. shibae DFL 12 and R. denitrificans OCh 114 primarily utilized sulfolactate sulfo-lyase, and sulfopyruvate decarboxylase followed by sulfoacetaldehyde acetyltransferase, respectively, to complete desulfonation releasing the sulfonate-moiety. The sulfite could be further oxidized or incorporated into sulfate assimilation, indicated by the proteomic data. Furthermore, DHPS metabolic pathways were found primarily in marine bacterial groups, including the majority of sequenced Roseobacter genomes. Our results suggest that chiral DHPS, as a vital reduced sulfur reservoir, could be metabolized by marine bacteria, providing a resource for bacterial growth, rather than acting as a source of toxic sulfide within the marine ecosystem.

Polyphenols have long been used as functional compounds and are beneficial for host immunity and gut health. This three-phased study investigated the function of Ouli fermented juice (OF) in improving the immunity of cyclophosphamide (CTX)-immunosuppressed mice and regulating their intestinal microbiota and mucosal barrier. Lactobacillus plantarum fermentation increased the phenolic content in the OF. OF effectively improved host immunity and the intestinal mucosal barrier, including increasing serum immunoglobulin (Ig)A, IgG, and IgM levels and secreted IgA (sIgA) levels in the colon, and reduced CTX-induced pathological damage to the spleen and jejunum. Importantly, OF effectively increased the abundance of Lachnospiracea, Roseburia, Akkermansia, and butyric acid-producing microbes, subsequently increasing the levels of short chain fatty acids in the colon. OF with polyphenols exhibited better efficacy at altering the intestinal flora, which might affect the host immunity by changing the host-mucosal barrier-microbiota interaction.

In this paper, a cache-enabled wireless network with circuit power consumption is considered, and the strategy of joint transmission and local caching is studied. The optimization problem of energy consumption minimization is formulated, where the optimized variables include the transmission rate and the local caching rate. The constraint conditions contain the maximum data departure curve, the minimum data departure curve, and the range of the local caching rate. The original problem is intractable and is transformed into a two-layer optimization one by variable substitution. Under given caching policy, the sufficient and necessary conditions for the optimal offline transmission strategy are deduced by using the transmission characteristics. Then, an energy-efficient offline transmission strategy is proposed, and its optimality is proved. The simulation results are provided to verify the performance of the proposed strategy. The simulation results reveal the impact of the cache capacity and the file popularity on energy consumption. Under the same conditions, the performance of the proposed strategy is better than that of the other known algorithms. The proposed strategy to energy-efficient communication is helpful for future green communication.

In this paper, the secure energy-efficient transmission problem for an artificial-noise (AN)-aided simultaneous wireless information and power transfer (SWIPT) and vehicle-to-infrastructure (V2I) communication system with the imperfect channel state information (CSI) is studied. The secure energy efficiency problem is formulated with the imperfect CSI, where the constraints contain the minimum secrecy rate request of the legitimate vehicle (LV), the minimum energy harvesting (EH) request, the maximum transmit power, and the power splitting (PS) value. By exploiting the maximum ratio transmission (MRT) scheme and the norm-bounded matrix theory, we convert the original intractable problem to a fractional optimization one with three variables. Then, a two-level optimization algorithm is presented for the nonconvex fractional optimization problem. By introducing an auxiliary slack variable, the first level problem can be solved via one-dimensional optimization algorithm. The second level fractional optimization problem was furhther converted into an integer optimization one by the Dinkelbach method, and the closed-form solutions of the transmit power and the AN power are provided. Simulation results are given to verify the performance of our presented algorithm.

Rechargeable zinc-ion batteries are promising energy storage devices but suffer from the limited choice of positive electrodes. Here Niu and co-workers show a design with sodium vanadate hydrate as cathode, allowing simultaneous proton and zinc-ion insertion/extraction and enhanced performance.

To understand the anomalous electronic transport properties of ZrTe5 remains an elusive puzzle. Here, Zhang et al. report direct electronic evidence to the origin of the resistivity anomaly and temperature induced Lifshitz transition in ZrTe5, indicating it being a weak topological insulator.

In asthma, mucus hypersecretion is thought to be a prominent pathological feature associated with widespread mucus plugging. However, the current treatments for mucus hypersecretion are often ineffective or temporary. The potential therapeutic targets of mucus hypersecretion in asthma remain unknown. Here, we show that Lyn is a central effector of endoplasmic reticulum stress (ER stress) and mucous hypersecretion in asthma. In Lyn-transgenic mice (Lyn-TG) and wild-type (WT) C57BL/6J mice exposed to ovalbumin (OVA), Lyn overexpression attenuates mucus hypersecretion and ER stress. Interleukin 13 (IL-13) induced MUC5AC expression by enhancing ER stress in vitro. Lyn serves as a negative regulator of IL-13-induced ER stress and MUC5AC expression. We further find that an inhibitor of ER stress, which is likely involved in the PI3K p85α/Akt pathway and NFκB activity, blocked MUC5AC expression in Lyn-knockdown cells. Furthermore, PI3K/Akt signaling is required for IL-13-induced ER stress and MUC5AC expression in airway epithelial cells. The ER stress regulation of MUC5AC expression depends on NFκB in Lyn-knockdown airway epithelial cells. Our studies indicate not only a concept of mucus hypersecretion in asthma that involves Lyn kinase but also an important therapeutic candidate for asthma.

Honokiol is a natural compound with small molecular structure and extracted from bark of magnolia trees. The biological activities of honokiol include anti-oxidation, anti-inflammation as well as anti-tumor. However, their mechanism remains unknown. In this study, A549 cell line and EGFR-mutant cell line PC-9 with higher expression level of Lyn than A549 cells were used to assess the anti-tumor effects of honokiol. As shown in this study, honokiol is an effective drug on inhibiting proliferation and inducing apoptosis depended on Lyn and EGFR signal pathway regulated by Lyn, and its efficacy is stronger in PC-9 cells than A549 cells. In addition, this anti-tumor effect in PC-9 cells was weakened by Lyn-knockdown. Taken together, this study indicated the mechanism of honokiol on lung adenocarcinoma and provides a possibility of honokiol as an effective anti-tumor medicine.

We study the electronic structures and topological properties of (M+N)-layer twisted graphene systems. We consider the generic situation that N-layer graphene is placed on top of the other M-layer graphene and is twisted with respect to each other by an angle θ. In such twisted multilayer graphene systems, we find that there exist two low-energy flat bands for each valley emerging from the interface between the M layers and the N layers. These two low-energy bands in the twisted multilayer graphene system possess valley Chern numbers that are dependent on both the number of layers and the stacking chiralities. In particular, when the stacking chiralities of the M layers and N layers are opposite, the total Chern number of the two low-energy bands for each valley equals ±(M+N-2) (per spin). If the stacking chiralities of the M layers and the N layers are the same, then the total Chern number of the two low-energy bands for each valley is ±(M-N) (per spin). The valley Chern numbers of the low-energy bands are associated with large, valley-contrasting orbital magnetizations, suggesting the possible existence of orbital ferromagnetism and anomalous Hall effect once the valley degeneracy is lifted either externally by a weak magnetic field or internally by Coulomb interaction through spontaneous symmetry breaking. Such an orbital ferromagnetic state is characterized by chiral current loops circulating around the AA region of the moiré pattern, which can be experimentally detected.

Charge transport of topological semimetals is the focus of intensive investigations because of their nontrivial band topology. Heat transport of these materials, on the other hand, is largely unexplored and remains elusive. Here, we report on an observation of unprecedented, giant magnetic quantum oscillations of thermal conductivity in the prototypical Weyl semimetal TaAs. The oscillations are antiphase with the quantum oscillating electronic density of states of a Weyl pocket, and their amplitudes amount to 2 orders of magnitude of the estimation based on the Wiedemann-Franz law. Our analyses show that all the conventional heat-transport mechanisms through diffusions of propagating electrons, phonons, and electron-hole bipolar excitations are far inadequate to account for these phenomena. Taking further experimental facts that the parallel field configuration favors much-higher magnetothermal conductivity, we propose that the newly proposed chiral zero sound provides a reasonable explanation to these exotic phenomena. More work focusing on other topological semimetals along the same line is badly called for.

Quasiparticles and collective modes are two fundamental aspects that characterize quantum matter in addition to its ground-state features. For example, the low-energy physics for Fermi-liquid phase in He-III is featured not only by fermionic quasiparticles near the chemical potential but also by fruitful collective modes in the long-wave limit, including several different sound waves that can propagate through it under different circumstances. On the other hand, it is very difficult for sound waves to be carried by electron liquid in ordinary metals due to the fact that long-range Coulomb interaction among electrons will generate a plasmon gap for ordinary electron density oscillation and thus prohibits the propagation of sound waves through it. In the present paper, we propose a unique type of acoustic collective mode in Weyl semimetals under magnetic field called chiral zero sound. Chiral zero sound can be stabilized under the so-called “chiral limit,” where the intravalley scattering time is much shorter than the intervalley one and propagates only along an external magnetic field for Weyl semimetals with multiple pairs of Weyl points. The sound velocity of chiral zero sound is proportional to the field strength in the weak field limit, whereas it oscillates dramatically in the strong field limit, generating an entirely new mechanism for quantum oscillations through the dynamics of neutral bosonic excitation, which may manifest itself in the thermal conductivity measurements under magnetic field.

In topological insulators doped with magnetic ions, spin-orbit coupling and ferromagnetism give rise to the quantum anomalous Hall effect. Here, we show that in s-wave superconductors with strong spin-orbit coupling, magnetic impurity ions can generate topological vortices in the absence of external magnetic fields. Such vortices, dubbed quantum anomalous vortices, support robust Majorana zero-energy modes when superconductivity is induced in the topological surface states. We demonstrate that the zero-energy bound states observed in Fe(Te,Se) superconductors are possible realizations of the Majorana zero modes in quantum anomalous vortices produced by the interstitial magnetic Fe. The quantum anomalous vortex matter not only advances fundamental understandings of topological defect excitations of Cooper pairing but also provides new and advantageous platforms for manipulating Majorana zero modes in quantum computing.

An objective method was developed to analyze longwave and shortwave trough lines in wind field data using different methods, given that these trough lines were researched in different ways. Longwave trough lines were analyzed by locating the cyclonic center and filtering candidate trough points simultaneously; the candidate longwave trough points were then traced based on distance and angle conditions. Next, candidate shortwave trough points were determined based on angular deflection and vorticity data, which were clustered and fitted to a curve for extraction. This method was applied to wind field data from the National Center for Environmental Prediction (NCEP) to analyze trough lines in East Asia and South Asia. The experimental results show that our method can effectively identify trough lines by comparing them with manual analysis results. The statistical results indicate that the method more precisely identifies longwave trough lines than shortwave trough lines, and that trough lines during the fall and winter are more accurately and effectively identified than those during the spring and summer.

A new type of topological state in strongly correlated condensed matter systems, the heavy Weyl fermion state, has been found in a heavy fermion material, CeRu_{4}Sn_{6}, which has no inversion symmetry. Two different types of Weyl points, types I and II, can be found in the quasiparticle band structure obtained by the LDA+Gutzwiller calculations, which can treat the strong correlation effects among the f electrons from cerium atoms. The surface calculations indicate that the topologically protected Fermi arc states exist on the (010) but not on the (001) surface.

Zirconium pentatelluride ZrTe _5 , a fascinating topological material platform, hosts exotic chiral fermions in its highly anisotropic three-dimensional Dirac band and holds great promise advancing the next-generation information technology. However, the origin underlying its anomalous resistivity peak has been under debate for decades. Here we provide transport evidence substantiating the anomaly to be a direct manifestation of a Lifshitz transition in the Dirac band with an ultrahigh carrier mobility exceeding 3 × 10 ^5 cm ^2 V ^−1 s ^−1 . We demonstrate that the Lifshitz transition is readily controllable by means of carrier doping, which sets the anomaly peak temperature T _p . T _p is found to scale approximately as ${n}_{{\rm{H}}}^{0.27},$ where the Hall carrier concentration n _H is linked with the Fermi level by ε _F ∝ ${n}_{{\rm{H}}}^{1/3}$ in a linearly dispersed Dirac band. This relation indicates T _p monotonically increases with ε _F , which serves as an effective knob for fine tuning transport properties in pentatelluride-based Dirac semimetals.

Weyl semimetal is the three-dimensional analog of graphene. According to quantum field theory, the appearance of Weyl points near the Fermi level will cause novel transport phenomena related to chiral anomaly. In the present paper, we report the experimental evidence for the long-anticipated negative magnetoresistance generated by the chiral anomaly in a newly predicted time-reversal-invariant Weyl semimetal material TaAs. Clear Shubnikov de Haas (SdH) oscillations have been detected starting from a very weak magnetic field. Analysis of the SdH peaks gives the Berry phase accumulated along the cyclotron orbits as π, indicating the existence of Weyl points.

Based on first-principle calculations, we show that a family of nonmagnetic materials including TaAs, TaP, NbAs, and NbP are Weyl semimetals (WSM) without inversion centers. We find twelve pairs of Weyl points in the whole Brillouin zone (BZ) for each of them. In the absence of spin-orbit coupling (SOC), band inversions in mirror-invariant planes lead to gapless nodal rings in the energy-momentum dispersion. The strong SOC in these materials then opens full gaps in the mirror planes, generating nonzero mirror Chern numbers and Weyl points off the mirror planes. The resulting surface-state Fermi arc structures on both (001) and (100) surfaces are also obtained, and they show interesting shapes, pointing to fascinating playgrounds for future experimental studies.

Starting from the k·p method in combination with first-principles calculations, we systematically derive the effective Hamiltonians that capture the low energy quasi-particle structures of the recently discovered topological Kondo insulator SmB _6 . Using these effective Hamiltonians we can obtain both the energy dispersion and the spin texture of the topological surface states, which can be detected by further experiments.

Quantum spin Hall (QSH) insulators, a new class of quantum matter, can support topologically protected helical edge modes inside a bulk insulating gap, which can lead to dissipationless transport. A major obstacle to reaching a wide application of QSH is the lack of suitable QSH compounds, which should be easily fabricated and have a large bulk gap. Here, we predict that single-layer ZrTe_{5} and HfTe_{5} are the most promising candidates for large-gap insulators, with a bulk direct (indirect) band gap as large as 0.4 eV (0.1 eV) and which are robust against external strains. The three-dimensional crystals of these two materials are good layered compounds with very weak interlayer bonding, and they are located near the phase boundary between weak and strong topological insulators, paving a new way for future experimental studies on both the QSH effect and topological phase transitions.