Weyl semi-metal is the three dimensional analog of graphene. According to the 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 first experimental evidence for the long-anticipated negative magneto-resistance generated by the chiral anomaly in a newly predicted time-reversal invariant Weyl semi-metal material TaAs. Clear Shubnikov de Haas oscillations (SdH) have been detected starting from very weak magnetic field. Analysis of the SdH peaks gives the Berry phase accumulated along the cyclotron orbits to be π, indicating the existence of Weyl points.When two non-degenerate bands cross in three dimensional momentum space, the crossing points are called Weyl points, which can be viewed as magnetic monopoles(1) or topological defects (2) in band structure, like "knots" on a rope. Near Weyl points, the low energy physics can be described by Weyl equations (3) with distinct chirality (either left-or right-handed), which mimics the relativistic field theory in particle physics. On lattice system, Weyl points always appear in pairs with opposite chirality and are topologically stable against perturbations that keep translational symmetry (4-7). If two weyl points with opposite chirality meet in the momentum space, they will generally annihilate each other, but may also be stabilized as 3D Dirac points by additional (such as crystalline) symmetry (8-11). For materials withWeyl points located near the Fermi level, called as Weyl semi-metals (WSMs), exotic low energy physics will be expected, such as the Fermi arcs on the surfaces (5,6), and the chiral-anomaly induced quantum transport (12)(13)(14)(15). Recently, 3D Dirac semimetals, Na 3 Bi and Cd 3 As 2 , have been theoretically predicted (9,10) and experimentally confirmed (16)(17)(18)(19)(20), while WSM are still waiting for its experimental verification in spite of various theoretical proposals (5,6,(21)(22)(23)(24)(25).The anomalous DC transport properties are important consequence of the topological band structure (14,26,27). In topological insulators (TI), the transport properties are dominated by the topological surfaces states (SS), where the lack of back scattering caused by the unique spin structure of the SS leads to the weak anti-localization (WAL) behavior. While in Weyl semi-metals, the bulk states are semi-metallic and dominate the DC transport. In relativistic field theory, for a continue system described by Weyl equation, chiral anomaly can be understood as the non-conservation of the particle number with given chirality, which only happens under the presence of

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Symmetry, dimensionality, and interaction are crucial ingredients for phase transitions and quantum states of matter. As a prominent example, the integer quantum Hall effect (QHE) represents a topological phase generally regarded as characteristic for two-dimensional (2D) electronic systems, and its many aspects can be understood without invoking electron-electron interaction. The intriguing possibility of generalizing QHE to three-dimensional (3D) systems was proposed decades ago, yet it remains elusive experimentally. Here, we report for the first time clear experimental evidence for the 3D QHE, observed in bulk ZrTe5 crystals. Owing to the extremely high sample quality, the extreme quantum limit with only the lowest Landau level occupied can be achieved by an applied magnetic field as low as 1.5 T. Remarkably, in this regime, we observe a dissipationless longitudinal resistivity ≅ accompanied with a well-developed Hall resistivity plateau = ( ± . ) ( , ) , where , is the Fermi wavelength along the field direction ( axis). This striking result strongly suggests a Fermi surface instability driven by the enhanced interaction effects in the extreme quantum limit. In addition, with further increasing magnetic field, both and increase dramatically and display an interesting metal-insulator transition, representing another magnetic field driven quantum phase transition. Our findings not only unambiguously reveal a novel quantum state of matter resulting from an intricate interplay among dimensionality, interaction, and symmetry breaking, but also provide a promising platform for further exploration of more exotic quantum phases and transitions in 3D systems.Since its discovery in 1980, the QHE has been established and well understood in a variety of 2D electron systems, including the traditional 2D electron gas 1,2 , and 2D materials like graphene 3,4 , etc. The hallmark of QHE is that the Hall conductivity takes precisely quantized values as 2 /ℎ while the longitudinal conductivity vanishes 1,2 . Here, the prefactor is the filling factor which counts the number of filled Landau levels, is the elementary charge, and ℎ is Plank's constant. Soon after its

We present multi-element data on the super-highorganic-sulfur (SHOS; 5.19 % on average) coals of Late Permian age from Guiding, in Guizhou Province, China. The coals, formed on restricted carbonate platforms, are all highly enriched in S, U, Se, Mo, Re, V, and Cr, and, to a lesser extent, Ni and Cd. Although the Guiding coals were subjected to seawater influence, boron is very low and mainly occurs in tourmaline and mixed-layer illite/smectite. Uranium, Mo, and V in the coal are mainly associated with the organic matter. In addition, a small proportion of the U occurs in coffinite and brannerite. The major carrier of Se is pyrite rather than marcasite. Rhenium probably occurs in secondary sulfate and carbonate minerals. The U-bearing coal deposits have the following characteristics: the formation age is limited to Late Permian; concentrations of sulfur and rare metals (U, Se, Mo, Re, V, and in some cases, rare earth elements and Y) are highly elevated; the U-bearing coal beds are intercalated with marine carbonate rocks; organic sulfur and rare metals are uniformly distributed within the coal seams; and the combustion products (e.g., fly and bottom ash) derived from the coal deposits may have potential economic significance for rare metals: U, Se, Mo, Re, V, rare earth elements, and Y.

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N 6 -methyladenosine (m 6 A) is a commonly present modification of mammalian mRNAs and plays key roles in various cellular processes. m 6 A modifiers catalyze this reversible modification. However, the underlying mechanisms by which these m 6 A modifiers are regulated remain elusive. Here we show that expression of m 6 A demethylase ALKBH5 is regulated by chromatin state alteration during leukemogenesis of human acute myeloid leukemia (AML), and ALKBH5 is required for maintaining leukemia stem cell (LSC) function but is dispensable for normal hematopoiesis. Mechanistically, KDM4C regulates ALKBH5 expression via increasing chromatin accessibility of ALKBH5 locus, by reducing H3K9me3 levels and promoting recruitment of MYB and Pol II. Moreover, ALKBH5 affects mRNA stability of receptor tyrosine kinase AXL in an m 6 Adependent way. Thus, our findings link chromatin state dynamics with expression regulation of m 6 A modifiers and uncover a selective and critical role of ALKBH5 in AML that might act as a therapeutic target of specific targeting LSCs.

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