Genome Sequence Resource of Fusarium proliferatum f. sp. malus domestica MR5, the Causative Agent of Apple Replant Disease.

Apple replant disease (ARD) caused by the fungal pathogen Fusarium proliferatum f. sp. malus domestica (Fpmd) MR5 brings annual losses to apple production within China. However, the genomic information of the pathogen is not yet available. Here, we obtained the whole-genome sequence of the highly virulent Fpmd MR5 using the Illumina PE150 platform. The genome size was 42.76 Mb and consisted of 9,047 genes. The GC content was 48.80%, and several genes potentially associated with pathogenicity were identified, such as carbohydrate-active enzymes, secreted proteins, and secondary metabolite gene clusters. There were 260 specific virulence factor genes, mainly related to fungal vegetative growth and the production of cell wall-degrading enzymes. These data will aid future studies investigating host-pathogen interactions and help us develop suitable disease management strategies.

Lattice distortions and the metal-insulator transition in pure and Ti-substituted Ca3Ru2O7.

We report pair distribution function studies on the relationship between the metal-insulator transition (MIT) and lattice distortions in pure and Ti-substituted bilayer Ca3Ru2O7. Structural refinements performed as a function of temperature, magnetic field and length scale reveal the presence of lattice distortions not only within but also orthogonal to the bilayers. Because of the distortions, the local and average crystal structure differ across a broad temperature region extending from room temperature to temperatures below the MIT. The coexistence of distinct lattice distortions is likely to be behind the marked structural flexibility of Ca3Ru2O7under external stimuli. This observation highlights the ubiquity of lattice distortions in an archetypal Mott system and calls for similar studies on other families of strongly correlated materials.

Superconducting spin smecticity evidencing the Fulde-Ferrell-Larkin-Ovchinnikov state in Sr2RuO4.

Translational symmetry breaking is antagonistic to static fluidity but can be realized in superconductors, which host a quantum-mechanical coherent fluid formed by electron pairs. A peculiar example of such a state is the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state, induced by a time-reversal symmetry-breaking magnetic field applied to spin-singlet superconductors. This state is intrinsically accompanied by the superconducting spin smecticity, spin density-modulated fluidity with spontaneous translational-symmetry breaking. Detection of such spin smecticity provides unambiguous evidence for the FFLO state, but its observation has been challenging. Here, we report the characteristic "double-horn" nuclear magnetic resonance spectrum in the layered superconductor Sr2RuO4 near its upper critical field, indicating the spatial sinusoidal modulation of spin density that is consistent with superconducting spin smecticity. Our work reveals that Sr2RuO4 provides a versatile platform for studying FFLO physics.

Discovery of Fusarium proliferatum f. sp. malus domestica Causing Apple Replant Disease in China.

Apple replant disease (ARD) is the most serious threat facing the apple industry globally. ARD is mainly manifested as decreased plant growth, serious root rot disease, and considerable yield loss. Microbial factors are the dominant factors leading to the occurrence of ARD. Research on soil-borne pathogenic fungi leading to the occurrence of ARD in China is limited. In the present study, we selected 16 replanting orchards from the Northwest Loess region and around the Bohai Gulf. Diseased roots and rhizosphere soil from healthy apple trees and trees showing ARD symptoms were sampled at random. High-throughput sequencing was used to study the fungal communities in the rhizosphere soil, which showed that the composition of the rhizosphere soil fungal community of ARD-symptomatic and healthy apple trees was different. Nectriaceae at the family level and Fusarium at the genus level dominated the rhizosphere soil fungal community in the two regions, while for healthy apple trees, the relative abundance of Mortierella, Minimedusa, Tetracladium, and Chaetomium was higher. Tissue separation and serial dilution were used to separate fungi, and a total of 89 genera and 219 species were obtained, most of which were Fusarium. Fusarium was further confirmed to be the most abundant pathogen species leading to the occurrence of ARD in China through pathogenicity assays. A pathogenicity assay was carried out by the dip-and-cut technique using different host plants. It was found that Fusarium MR5 showed strong aggressiveness to apple rootstocks. Diseased seedlings specifically exhibited chlorosis of the leaves, browning from the edge of the leaf, followed by rolling and yellowing of the leaves, resulting in wilting and eventually death. Strain MR5 was preliminarily identified as F. proliferatum according to the morphological and cultural characteristics. A maximum likelihood analysis of identities based on six gene sequence (ITS, TUB2, IGS, mtSSU, RPB2, and the TEF gene) alignments between the MR5 strain and other strains showed 99 to 100% homology with F. proliferatum. Based on our test results, strain MR5 was identified as F. proliferatum f. sp. malus domestica, which is of great significance for finding new measures to control ARD in China.

Coupled electronic and magnetic relaxation in Fe1+yTe: direct evidence for the interaction between itinerant carriers and local moments.

Iron chalcogenides are of particular interests among iron-based superconductors due to their distinct properties such as high-Tcon FeSe monolayer and competing magnetic correlations in Fe1+yTe. Here we report unusual transport properties observed near the critical composition of Fe1+yTe (y∼ 0.09) where competing magnetic correlations exist. The resistivity exhibits surprising temperature-dependent relaxation behavior belowTN, resulting in the increase of resistivity with time for 35 K

Spin-valley locking and bulk quantum Hall effect in a noncentrosymmetric Dirac semimetal BaMnSb2.

Spin-valley locking in monolayer transition metal dichalcogenides has attracted enormous interest, since it offers potential for valleytronic and optoelectronic applications. Such an exotic electronic state has sparsely been seen in bulk materials. Here, we report spin-valley locking in a Dirac semimetal BaMnSb2. This is revealed by comprehensive studies using first principles calculations, tight-binding and effective model analyses, angle-resolved photoemission spectroscopy measurements. Moreover, this material also exhibits a stacked quantum Hall effect (QHE). The spin-valley degeneracy extracted from the QHE is close to 2. This result, together with the Landau level spin splitting, further confirms the spin-valley locking picture. In the extreme quantum limit, we also observed a plateau in the z-axis resistance, suggestive of a two-dimensional chiral surface state present in the quantum Hall state. These findings establish BaMnSb2 as a rare platform for exploring coupled spin and valley physics in bulk single crystals and accessing 3D interacting topological states.

Reduction of the Spin Susceptibility in the Superconducting State of Sr_{2}RuO_{4} Observed by Polarized Neutron Scattering.

Recent observations [A. Pustogow et al., Nature (London) 574, 72 (2019).NATUAS0028-083610.1038/s41586-019-1596-2] of a drop of the ^{17}O nuclear magnetic resonance (NMR) Knight shift in the superconducting state of Sr_{2}RuO_{4} challenged the popular picture of a chiral odd-parity paired state in this compound. Here we use polarized neutron scattering (PNS) to show that there is a 34±6% drop in the magnetic susceptibility at the Ru site below the superconducting transition temperature. We measure at lower fields H∼1/3H_{c2} than a previous PNS study allowing the suppression to be observed. The PNS measurements show a smaller susceptibility suppression than NMR measurements performed at similar field and temperature. Our results rule out the chiral odd-parity d=z[over ^](k_{x}±ik_{y}) state and are consistent with several recent proposals for the order parameter including even-parity B_{1g} and odd-parity helical states.

Directional massless Dirac fermions in a layered van der Waals material with one-dimensional long-range order.

One or a few layers of van der Waals (vdW) materials are promising for applications in nanoscale electronics. Established properties include high mobility in graphene, a large direct gap in monolayer MoS2, the quantum spin Hall effect in monolayer WTe2 and so on. These exciting properties arise from electron quantum confinement in the two-dimensional limit. Here, we use angle-resolved photoemission spectroscopy to reveal directional massless Dirac fermions due to one-dimensional confinement of carriers in the layered vdW material NbSi0.45Te2. The one-dimensional directional massless Dirac fermions are protected by non-symmorphic symmetry, and emerge from a stripe-like structural modulation with long-range translational symmetry only along the stripe direction as we show using scanning tunnelling microscopy. Our work not only provides a playground for investigating further the properties of directional massless Dirac fermions, but also introduces a unique component with one-dimensional long-range order for engineering nano-electronic devices based on heterostructures of vdW materials.

Emergence of intrinsic superconductivity below 1.178 K in the topologically non-trivial semimetal state of CaSn3.

Topological materials which are also superconducting are of great current interest, since they may exhibit a non-trivial topologically-mediated superconducting phase. Although there have been many reports of pressure-tuned or chemical-doping-induced superconductivity in a variety of topological materials, there have been few examples of intrinsic, ambient pressure superconductivity in a topological system having a stoichiometric composition. Here, we report that the pure intermetallic CaSn3 not only exhibits topological fermion properties, but also has a superconducting phase at ~1.178 K under ambient pressure. The topological fermion properties, including the nearly zero quasi-particle mass and the non-trivial Berry phase accumulated in cyclotron motions, were revealed from the de Haas-van Alphen (dHvA) quantum oscillation studies of this material. Although CaSn3 was previously reported to be superconducting with T c = 4.2 K, our studies show that the T c = 4.2 K superconductivity is extrinsic and caused by Sn on the degraded surface, whereas its intrinsic bulk superconducting transition occurs at 1.178 K. These findings make CaSn3 a promising candidate for exploring new exotic states arising from the interplay between non-trivial band topology and superconductivity, e.g. topological superconductivity (TSC).

Insulator-metal transition induced by electric voltage in a ruthenate Mott insulator.

We report the observation of electric-voltage induced insulator-metal phase transition in a ruthenate Mott insulator Ca3(Ru0.9Ti0.1)2O7. We show that the electric field effect dominates and leads to a sharp phase transition at measurement temperatures far below the Mott transition, whereas the thermal effect becomes more significant and broadens the phase transition as the measurement temperature approaches the insulator-metal transition. The electric field induced insulator-metal transition is presumably attributed to the avalanche breakdown of the correlated insulating state when driven out of equilibrium. This work highlights the strategy of using electric voltage to control the phase transition of this system in addition to other nonthermal parameters such as magnetic field and pressure reported previously.

Spin Fluctuations in Sr_{2}RuO_{4} from Polarized Neutron Scattering: Implications for Superconductivity.

Triplet pairing in Sr_{2}RuO_{4} was initially suggested based on the hypothesis of strong ferromagnetic spin fluctuations. Using polarized inelastic neutron scattering, we accurately determine the full spectrum of spin fluctuations in Sr_{2}RuO_{4}. Besides the well-studied incommensurate magnetic fluctuations, we do find a sizable quasiferromagnetic signal, quantitatively consistent with all macroscopic and microscopic probes. We use this result to address the possibility of magnetically driven triplet superconductivity in Sr_{2}RuO_{4}. We conclude that, even though the quasiferromagnetic signal is stronger and sharper than previously anticipated, spin fluctuations alone are not enough to generate a triplet state strengthening the need for additional interactions or an alternative pairing scenario.

Thickness evolution of transport properties in exfoliated Fe1+y Te nanoflakes.

We report the evolution of transport properties in exfoliated Fe1+y Te (y = 0.04) nanoflakes of various thickness. In contrast to the sharp semiconducting-to-metallic phase transition observed in both bulk and thicker flakes, this transition becomes broadened for flakes with an intermediate thickness followed by the appearance of a superconducting-like feature upon further cooling. With the thickness further decreased, the flakes exhibit insulating transport behavior with significantly enhanced positive magnetoresistance, which can be explained using a variable range hopping mechanism, suggesting the nature of a highly disordered 2D system.

Temperature- and field-driven spin reorientations in triple-layer ruthenate Sr4Ru3O10.

Sr4Ru3O10, the n = 3 member of the Ruddlesden-Popper type ruthenate Srn+1Ru n O3n+1, is known to exhibit a peculiar metamagnetic transition in an in-plane magnetic field. However, the nature of both the temperature- and field-dependent phase transitions remains as a topic of debate. Here, we have investigated the magnetic transitions of Sr4Ru3O10 via single-crystal neutron diffraction measurements. At zero field, we find that the system undergoes a ferromagnetic transition with both in-plane and out-of-plane magnetic components at Tc ≈ 100 K. Below T * = 50 K, the magnetic moments incline continuously toward the out-of-plane direction. At T = 1.5 K, where the spins are nearly aligned along the c axis, a spin reorientation occurs above a critical field Bc, giving rise to a spin component perpendicular to the plane defined by the field direction and the c axis. We suggest that both the temperature- and field-driven spin reorientations are associated with a change in the magnetocrystalline anisotropy, which is strongly coupled to the lattice degrees of freedom. This study elucidates the long-standing puzzles on the zero-field magnetic orders of Sr4Ru3O10 and provides new insights into the nature of the field-induced metamagnetic transition.

Field-induced magnetic phase transitions and memory effect in bilayer ruthenate Ca3Ru2O7 with Fe substitution.

Bilayer ruthenate Ca3(Ru1-x Fe x )2O7 (x = 0.05) exhibits an incommensurate magnetic soliton lattice driven by the Dzyaloshinskii-Moriya interaction. Here we report complex field-induced magnetic phase transitions and memory effect in this system via single-crystal neutron diffraction and magnetotransport measurements. We observe first-order incommensurate-to-commensurate magnetic transitions upon applying the magnetic field both along and perpendicular to the propagation axis of the incommensurate spin structure. Furthermore, we find that the metastable states formed upon decreasing the magnetic field depend on the temperature and the applied field orientation. We suggest that the observed field-induced metastability may be ascribable to the quenched kinetics at low temperature.

Unusual interlayer quantum transport behavior caused by the zeroth Landau level in YbMnBi2.

Relativistic fermions in topological quantum materials are characterized by linear energy-momentum dispersion near band crossing points. Under magnetic fields, relativistic fermions acquire Berry phase of π in cyclotron motion, leading to a zeroth Landau level (LL) at the crossing point, a signature unique to relativistic fermions. Here we report the unusual interlayer quantum transport behavior resulting from the zeroth LL mode observed in the time reversal symmetry breaking type II Weyl semimetal YbMnBi2. The interlayer magnetoresistivity and Hall conductivity of this material are found to exhibit surprising angular dependences under high fields, which can be well fitted by a model, which considers the interlayer quantum tunneling transport of the zeroth LL's Weyl fermions. Our results shed light on the unusual role of zeroth LLl mode in transport.The transport behavior of the carriers residing in the lowest Landau level is hard to observe in most topological materials. Here, Liu et al. report a surprising angular dependence of the interlayer magnetoresistivity and Hall conductivity arising from the lowest Landau level under high magnetic field in type II Weyl semimetal YbMnBi2.

A magnetic topological semimetal Sr1-yMn1-zSb2 (y, z < 0.1).

Weyl (WSMs) evolve from Dirac semimetals in the presence of broken time-reversal symmetry (TRS) or space-inversion symmetry. The WSM phases in TaAs-class materials and photonic crystals are due to the loss of space-inversion symmetry. For TRS-breaking WSMs, despite numerous theoretical and experimental efforts, few examples have been reported. In this Article, we report a new type of magnetic semimetal Sr1-yMn1-zSb2 (y, z < 0.1) with nearly massless relativistic fermion behaviour (m∗ =  0.04 - 0.05m0, where m0 is the free-electron mass). This material exhibits a ferromagnetic order for 304 K  <  T  <  565 K, but a canted antiferromagnetic order with a ferromagnetic component for T  <  304 K. The combination of relativistic fermion behaviour and ferromagnetism in Sr1-yMn1-zSb2 offers a rare opportunity to investigate the interplay between relativistic fermions and spontaneous TRS breaking.

[A multicenter randomized controlled study of Saccharomyces boulardii in the prevention of antibiotic-associated diarrhea in infants and young children].

Objective: To evaluate the efficacy and safety of Saccharomyces boulardii in the prevention of antibiotic-associated diarrhea (AAD) in infants and young children. Method: From November 2012 to September 2013, ten research units of large teaching hospitals or children's hospitals participated in this multicenter randomized controlled clinical trial. Hospitalized young children aged between 1 month and 3 years (nongastrointestinal infection and antibiotic therapy required)were involved in our study. The children were randomly divided into control group and prevention group by means of block random allocation method. The control group received antibiotic therapy and other conventional treatment. The prevention group was given additional Saccharomyces boulardii (250 mg/d) orally. Diarrhea rates of two groups were compared both during the usage of antibiotics and within 14 days after the antibiotics withdrawal. The adverse reactions of Saccharomyces boulardii were observed all through this study. The results were analyzed by χ(2) test or Kruskal-Wallis test or t test. Result: Totally 408 cases (213 cases in prevention group and 195 cases in control group) were enrolled. The age ranged from 1 month to 3 years, with an average age of 1.14 years. The basic diseases were parenteral infections: 368 cases with different kinds of respiratory tract infections or pneumonia, 10 cases of bacterial meningitis, 9 cases with septicemia or sepsis, 6 cases with pertussis or pertussis like syndrome, 5 cases with urinary infection, 5 cases with skin or subcutaneous tissue infections, 3 cases of Kawasaki disease, one with scarlet fever and one with congenital syphilis. During the administration of antibiotics, the incidence of AAD in prevention group was 10.3% (22 cases), which was significantly lower than that of control group (57 cases, 29.2%, χ(2)=23.296, P<0.05). Within 14 days after the discontinuation of antibiotics, the percent of new diarrhea cases in prevention group (2.4%, 5/213) was also significantly lower than that in control group (16.4%, 32/195, χ(2)=23.4, P<0.05). Further analysis revealed that the rate of AAD in children less than or equal to 1 year old (25.1%, 52/207) was significantly higher than that of over 1 year old (13.4%, 27/201, χ(2)=8.922, P<0.05). The incidence of AAD in children treated with antibiotics for more than 5 days was 22.2%(60/270), which was significantly higher than that of less than or equal to 5 days (13.8%, 19/138, χ(2)=4.180, P<0.05). Although no significant difference was observed, the AAD rate of patients with combined use of two antibiotics was higher than that of using one. During the antibiotic therapy, compared with the control group, the risk of AAD in children under 1 year old was reduced by 52% (χ(2)=9.217, P<0.05), and 91% (χ(2)=20.35, P<0.05) in the children over 1 year old in prevention group. The risk of AAD of prevention group decreased by 66% (χ(2)=13.67, P<0.05) in patients treated with one antibiotics, and 65% in children with combined use of antibiotics (χ(2)=10.57, P<0.05). In patients treated with antibiotics for less than or equal to 5 days, the risk of AAD decreased by 74% in prevention group (χ(2)=7.38, P<0.05); and 63% if the course lasted for over 5 days (χ(2)=16.87, P<0.05). Within 14 days after the withdrawal of antibiotics, compared with the control group, the risk of diarrhea in the prevention group decreased by 82% (χ(2)=13.35, P<0.05) in infants (≤1 year old) and 93% (χ(2)=12.00, P<0.05) in children (>1 year old); the risk of diarrhea was reduced by 86% (χ(2)=9.57, P<0.05) and 87% (χ(2)=17.71, P<0.05) respectively in prevention group with single and combined use of antibiotics. In patients treated with antibiotics for more than 5 days, the risk of diarrhea in prevention group was reduced by 63% (χ(2)=22.79, P<0.05), while there was no significant difference if the antibiotics course was less than or equal to 5 days (χ(2)=2.97, P>0.05). No adverse effects related with Saccharomyces boulardii were observed in our study. Conclusion:Saccharomyces boulardii is effective and safe to prevent AAD of infants and young children both during the usage of antibiotics and up to 14 days after drug discontinuance. It can be one of the drugs of for choice prevention of AAD in infants and young children. Trial registration Chinese Clinical Trial Tegister, ChiECRCT-2012-25.

Absence of a Large Superconductivity-Induced Gap in Magnetic Fluctuations of Sr_{2}RuO_{4}.

Inelastic neutron scattering experiments on Sr_{2}RuO_{4} determine the spectral weight of the nesting induced magnetic fluctuations across the superconducting transition. There is no observable change at the superconducting transition down to an energy of ∼0.35 meV, which is well below the 2Δ values reported in several tunneling experiments. At this and higher energies magnetic fluctuations clearly persist in the superconducting state. Only at energies below ∼0.3 meV can evidence for partial suppression of spectral weight in the superconducting state be observed. This strongly suggests that the one-dimensional bands with the associated nesting fluctuations do not form the active, highly gapped bands in the superconducting pairing in Sr_{2}RuO_{4}.

Role of microRNAs in the treatment of type 2 diabetes mellitus with Roux-en-Y gastric bypass.

The aim of this study was to investigate the effect of Roux-en-Y gastric bypass (RYGB) on the peripheral blood microRNAs (miRNAs) of patients with type 2 diabetes mellitus (T2DM). miRNAs are small 20- to 22-nucleotide (nt) noncoding RNAs. They constitute a novel class of gene regulators that negatively regulate gene expression at the post-transcriptional level. miRNAs play an important role in several biological processes. Twelve patients with T2DM who were scheduled to undergo laparoscopic RYGB surgery were separated into two groups, using a body mass index of 30 kg/m2 as a cut-off point. Venous blood was collected before operation and 12 months after operation. A significant change was observed in the peripheral blood miRNA expression profile of both groups after RYGB surgery compared with those before operation. The expression levels of hsa-miR-29a-3p, hsa-miR-122-5p, hsa-miR-124-3p, and hsa-miR-320a were downregulated. The methylation state of the CpG sites within an approximately 400-bp genomic DNA fragment of each of the four miRNA genes, including about 200 bp upstream and 100 bp downstream of the pre-miRNA, did not vary after RYGB surgery. With remission of T2DM in both groups, RYGB could modulate the expression level of many peripheral blood miRNAs associated with lipid metabolism, insulin secretion, beta-cell function, and insulin resistance. The expression level of peripheral blood diabetes-related miRNA varied in patients with T2DM after receiving RYGB surgery, laying a strong foundation for future studies on this subject. The molecular mechanisms underlying RYGB surgery that can cause aberrant expression of miRNA remains to be determined.

Colossal Magnetoresistance in a Mott Insulator via Magnetic Field-Driven Insulator-Metal Transition.

We present a new type of colossal magnetoresistance (CMR) arising from an anomalous collapse of the Mott insulating state via a modest magnetic field in a bilayer ruthenate, Ti-doped Ca_{3}Ru_{2}O_{7}. Such an insulator-metal transition is accompanied by changes in both lattice and magnetic structures. Our findings have important implications because a magnetic field usually stabilizes the insulating ground state in a Mott-Hubbard system, thus calling for a deeper theoretical study to reexamine the magnetic field tuning of Mott systems with magnetic and electronic instabilities and spin-lattice-charge coupling. This study further provides a model approach to search for CMR systems other than manganites, such as Mott insulators in the vicinity of the boundary between competing phases.