Continuously tunable electronic structure of transition metal dichalcogenides superlattices

published_or_final_versio

Aqua­(4-nitro­phthalato-κO 1)bis­[2-(1H-pyrazol-3-yl-κN 2)pyridine-κN]­mangan­ese(II) hemihydrate

In the title compound, [Mn(C8H3NO6)(C8H7N3)2(H2O)]·0.5H2O, the Mn2+ ion is octa­hedrally coordinated by two 2-(1H-pyrazol-3-yl)pyridine ligands, one 4-nitro­phthalate ligand and one coordinated water mol­ecule leading to an overall MnN4O2 coordination environment. The two 2-(1H-pyrazol-3-yl)pyridine ligands, which deviate from planarity by 0.0187 (2) and 0.0601 (2) Å, make a dihedral angle of 81.90 (6)°. An intra­molecular N—H⋯O hydrogen bond occurs. Inter­molecular π–π stacking inter­actions with a face-to-face separation of 3.61 (1) Å between the 2-(1H-pyrazol-3-yl)pyridine ligands is observed. Additionally, O—H⋯O hydrogen bonding involving the uncoordinated water (which is situated on an inversion center), coordinated water mol­ecules and 2-(1H-pyrazol-3-yl)pyridine ligands leads to a three-dimensional network in the crystal structure

Topological Dirac states beyond π\pi orbitals for silicene on SiC(0001) surface

The discovery of intriguing properties related to the Dirac states in graphene has spurred huge interest in exploring its two-dimensional group-IV counterparts, such as silicene, germanene, and stanene. However, these materials have to be obtained via synthesizing on substrates with strong interfacial interactions, which usually destroy their intrinsic $\pi$($p_z$)-orbital Dirac states. Here we report a theoretical study on the existence of Dirac states arising from the $p_{x,y}$ orbitals instead of $p_z$ orbitals in silicene on 4H-SiC(0001), which survive in spite of the strong interfacial interactions. We also show that the exchange field together with the spin-orbital coupling give rise to a detectable band gap of 1.3 meV. Berry curvature calculations demonstrate the nontrivial topological nature of such Dirac states with a Chern number $C = 2$, presenting the potential of realizing quantum anomalous Hall effect for silicene on SiC(0001). Finally, we construct a minimal effective model to capture the low-energy physics of this system. This finding is expected to be also applicable to germanene and stanene, and imply great application potentials in nanoelectronics.Comment: 6 Figures , Accepted by Nano Letter

5 GHz TMRT observations of 71 pulsars

We present integrated pulse profiles at 5~GHz for 71 pulsars, including eight millisecond pulsars (MSPs), obtained using the Shanghai Tian Ma Radio Telescope (TMRT). Mean flux densities and pulse widths are measured. For 19 normal pulsars and one MSP, these are the first detections at 5~GHz and for a further 19, including five MPSs, the profiles have a better signal-to-noise ratio than previous observations. Mean flux density spectra between 400~MHz and 9~GHz are presented for 27 pulsars and correlations of power-law spectral index are found with characteristic age, radio pseudo-luminosity and spin-down luminosity. Mode changing was detected in five pulsars. The separation between the main pulse and interpulse is shown to be frequency independent for six pulsars but a frequency dependence of the relative intensity of the main pulse and interpulse is found. The frequency dependence of component separations is investigated for 20 pulsars and three groups are found: in seven cases the separation between the outmost leading and trailing components decreases with frequency, roughly in agreement with radius-to-frequency mapping; in eleven cases the separation is nearly constant; in the remain two cases the separation between the outmost components increases with frequency. We obtain the correlations of pulse widths with pulsar period and estimate the core widths of 23 multi-component profiles and conal widths of 17 multi-component profiles at 5.0~GHz using Gaussian fitting and discuss the width-period relationship at 5~GHz compared with the results at at 1.0~GHz and 8.6~GHz.Comment: 46 pages, 14 figures, 8 Tables, accepted by Ap

Tris(1,10-phenanthroline-κ2 N,N′)zinc(II) chloride 2-phenyl-4-selenazole-5-car­box­yl­ate decahydrate

The asymmetric unit of the title salt, [Zn(C12H8N2)3](C10H6NO2Se)Cl·10H2O, contains a [Zn(phen)3]2+ cation (phen is 1,10-phenanthroline), uncoordinated chloride and 2-phenyl-4-selenazole-5-carboxyl­ate anions and ten uncoord­in­ated water mol­ecules. The central ZnII ion is six-coordinated by six N atoms from three phen ligands in a distorted octa­hedral geometry. An extensive O—H⋯O, O—H⋯N and O—H⋯Cl hydrogen-bonding network stabilizes the crystal structure

Reduced expression of SMAD4 in gliomas correlates with progression and survival of patients

<p>Abstract</p> <p>Background</p> <p>To examine the expression of SMAD4 at gene and protein levels in glioma samples with different WHO grades and its association with survival.</p> <p>Methods</p> <p>Two hundreds fifty-two glioma specimens and 42 normal control tissues were collected. Immunochemistry assay, quantitative real-time PCR and Western blot analysis were carried out to investigate the expression of SMAD4. Kaplan-Meier method and Cox's proportional hazards model were used in survival analysis.</p> <p>Results</p> <p>Immunohistochemistry showed that SMAD4 expression was decreased in glioma. SMAD4 mRNA and protein levels were both lower in glioma compared to control on real-time PCR and Western blot analysis (both P < 0.001). In addition, its expression levels decrease from grade I to grade IV glioma according to the results of real-time PCR, immunohistochemistry analysis and Western blot. Moreover, the survival rate of SMAD4-positive patients was higher than that of SMAD4-negative patients. We further confirmed that the loss of SMAD4 was a significant and independent prognostic indicator in glioma by multivariate analysis.</p> <p>Conclusions</p> <p>Our data provides convincing evidence for the first time that the reduced expression of SMAD4 at gene and protein levels is correlated with poor outcome in patients with glioma. SMAD4 may play an inhibitive role during the development of glioma and may be a potential prognosis predictor of glioma.</p