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Since the discovery of graphene, layered materials have attracted extensive interest owing to their unique electronic and optical characteristics. Among them, Dirac semimetals, one of the most appealing categories, have been a long-sought objective in layered systems beyond graphene. Recently, layered pentatelluride ZrTe 5 was found to host signatures of a Dirac semimetal. However, the low Fermi level in ZrTe 5 strongly hinders a comprehensive understanding of the whole picture of electronic states through photoemission measurements, especially in the conduction band. Here, we report the observation of Dirac fermions in ZrTe 5 through magneto-optics and magneto-transport. By applying a magnetic field, we observe a ffiffiffiffi B p dependence of the inter-Landau-level resonance and Shubnikov-de Haas (SdH) oscillations with a nontrivial Berry phase, both of which are hallmarks of Dirac fermions. The angle-dependent SdH oscillations show a clear quasi-two-dimensional feature with a highly anisotropic Fermi surface and band topology, in stark contrast to the three-dimensional (3D) Dirac semimetal such as Cd 3 As 2 . This is further confirmed by the angle-dependent Berry phase measurements and the observation of bulk quantum Hall effect (QHE) plateaus. The unique band dispersion is theoretically understood: the system is at the critical point between a 3D Dirac semimetal and a topological insulator phase. With the confined interlayer dispersion and reducible dimensionality, our work establishes ZrTe 5 as an ideal platform for exploring the exotic physical phenomena of Dirac fermions. NPG Asia Materials (2016) 8, e325; doi:10.1038/am.2016.166; published online 11 November 2016 INTRODUCTION Layered materials, formed by stacking strongly bonded layers with weak interlayer coupling, 1-10 have drawn immense attention in fundamental studies and device applications owing to their tunability in band structures and Fermi energy. 3,4,[11][12][13] Unlike other layered materials such as MoS 2 and BN, graphene stands out as an appealing candidate, as it is featured with a linear energy dispersion and low-energy relativistic quasi-particles. 9,14,15 Many exotic phenomena, such as a half-integer quantum Hall effect (QHE) 1,2 and Klein tunneling, 16 have been realized in graphene. Along this line, extensive efforts were also devoted to exploring new Dirac semimetal states in other layered systems beyond graphene. 5,6 Pentatelluride ZrTe 5 with a layered orthorhombic structure has been widely studied since the 1980s for its resistivity anomaly [17][18][19] and large thermopower. 20,21 For a long time, ZrTe 5 was considered to be a semimetal or degenerated semiconductor with a parabolic energy dispersion. 10,22 However, a recent study 7 revealed a linear dispersion in ZrTe 5 bulk states along with a chiral magnetic effect, hosting the signatures of a Dirac semimetal. Nevertheless, owing to the relatively

From a device application point of view, the extreme mechanical strength of graphene is highly desirable. However, the unavoidable polycrystalline nature of graphene films produced by chemical vapor deposition (CVD) leads to significant fluctuations in mechanical properties. Although the effects of atomic defects or grain boundaries (GBs) on mechanical strength have been widely studied and some modifications have been applied to enhance the stiffness of graphene, the problems of fragility as well as significantly reduced breaking strength arise. Here we report a systematic study on the effect of elastic modulus and breaking strength of CVD-derived graphene films with a controlled density and distribution of GBs. We find that graphene films become much stronger by hugely increasing the density of GBs without triple junctions (TJs) formed inside, in analogy to the two-dimensional (2D) plum pudding structures. The comprehensive performance with a 2D Young's modulus of 436 N/m (∼1.3 TPa) and 2D breaking strength of 43 N/m (∼128 GPa) can be achieved with the average grain size of 20 nm. Moreover, the existence of TJs will slightly reduce the strength in these GB structures. Due to defect types, the graphene films will show various tearing behaviors after indentation. All these mechanical studies of GBs provide a guideline to obtain the optimal performance of 2D materials through GB structure engineering.

The kagome lattice provides a fertile platform to explore novel symmetry-breaking states. Charge-density wave (CDW) instabilities have been recently discovered in a new kagome metal family, commonly considered to arise from Fermi-surface instabilities. Here we report the observation of Raman-active CDW amplitude modes in CsV3Sb5, which are collective excitations typically thought to emerge out of frozen soft phonons, although phonon softening is elusive experimentally. The amplitude modes strongly hybridize with other superlattice modes, imparting them with clear temperature-dependent frequency shift and broadening, rarely seen in other known CDW materials. Both the mode mixing and the large amplitude mode frequencies suggest that the CDW exhibits the character of strong electron-phonon coupling, a regime in which phonon softening can cease to exist. Our work highlights the importance of the lattice degree of freedom in the CDW formation and points to the complex nature of the mechanism.

Manganese porphyrin (MnTMPyP)-dsDNA complex was reported as an excellent mimicking enzyme of peroxidase. It possessed high catalytic activity and much quicker catalytic kinetics and better stability with exposure to light irradiation and high temperature than both horseradish peroxidase and hemin/G-quadruplex DNAzyme. The groove binding of MnTMPyP to the dsDNA scaffold efficiently maintained the catalytic activity of the MnTMPyP center and improved its stability. By combining with an isothermal hybridization chain reaction (HCR) and in situ formation of MnTMPyP-dsDNA, a highly efficient chemiluminescent (CL) immunosensing method was proposed. After a sandwich immunoreaction, a biotinylated DNA strand, which was bound to biotinylated signal antibody by streptavidin, triggered the HCR and growth of MnTMPyP-dsDNA on the immunocomplex. The in situ, HCR-assisted enzyme formation brought numerous enzymatic catalytic centers, MnTMPyP, on the immunocomplex, resulting in significant CL signal amplification and highly sensitive CL detection. Using carcinoembryonic antigen as the model target, the proposed CL immunoassay method showed a wide linear range from 10 pg/mL to 100 ng/mL with a detection limit of 6.8 pg/mL. The new MnTMPyP-dsDNA complex could be conveniently synthesized, functionalized, and combined with DNA amplification strategies, showing a promising potential in bioanalysis and other relative fields.

This review summarizes the sources and characteristics of various natural products that can be extracted from mangrove-associated microbes with a focus on bioactivity, highlighting the unique chemical diversity of these metabolic products.

Background: Tribendimidine is a new anthelmintic agent synthesized by Chinese scientists. It is a broad spectrum agent with high activity against parasites. However, its disposition and metabolism remain unknown.Objective: To investigate the metabolism, disposition, and metabolites of tribendimidine in healthy human volunteers.Methods: Twelve healthy Chinese volunteers were chosen after clinical assessment of health status and laboratory tests. They received single oral doses of tribendimidine 400mg enteric-coated tablets. Blood and urine samples were collected at scheduled timepoints. Samples were qualitatively and quantitatively analyzed by liquid chromatography-mass spectrometric (LC-MS) and high performance liquid chromatography (HPLC) methods, respectively.Results: Tribendimidine was rapidly and completely broken down to p-(1-dimethylamino ethylimino) aniline (dADT) and terephthalaldehyde (TPAL). Furthermore, dADT was partially transformed to acetylated dADT, and TPAL completely transformed to terephalic acid (TPAC). The main pharmacokinetic parameters (± SD) of dADT were as follows: elimination half life (t1/2) 4.74 ± 1.80 h; elimination rate constant (Ke) 0.16 ± 0.06 h−1; apparent volume of distribution (Vd/F) 12.23 ± 8.69L • kg−1; apparent total clearance of the drug from plasma (CL/F) 1.63 ± 0.58L • h−1 • kg−1; area under the plasma concentration-time curve (AUC) from time 0 to time 24 hours (AUC24) 4.29 ± 1.88 μg • mL−1 • h; AUC from time zero to infinity (AUC∞) 4.45 ± 1.81 μg • mL−1 • h; maximum plasma drug concentration (Cmax) 0.64 ± 0.27 μg • mL−1; and time to Cmax (tmax) 4.20 ± 0.71 h. A total of 35.28% dADT and 28.50% TPAC were excreted through the urine within 24 hours after tribendimidine administration.Conclusion: These results reveal the disposition, metabolism, and main metabolites of tribendimidine in healthy Chinese volunteers.