The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST, also called the Guo Shou Jing Telescope) is a special reflecting Schmidt telescope. LAMOST's special design allows both a large aperture (effective aperture of 3.6 m-4.9 m) and a wide field of view (FOV) (5 • ). It has an innovative active reflecting Schmidt configuration which continuously changes the mirror's surface that adjusts during the observation process and combines thin deformable mirror active optics with segmented active optics. Its primary mirror (6.67 m×6.05 m) and active Schmidt mirror (5.74 m×4.40 m) are both segmented, and composed of 37 and 24 hexagonal sub-mirrors respectively. By using a parallel controllable fiber positioning technique, the focal surface of 1.75 m in diameter can accommodate 4000 optical fibers. Also, LAMOST has 16 spectrographs with 32 CCD cameras. LAMOST will be the telescope with the highest rate of spectral acquisition. As a national large scientific project, the LAMOST project was formally proposed in 1996, and approved by the Chinese government in 1997. The construction started in 2001, was completed in 2008 and passed the official acceptance in June 2009. The LAMOST pilot survey was started in October 2011 and the spectroscopic survey will launch in September 2012. Up to now, LAMOST has released more than 480 000 spectra of objects. LAMOST will make an important contribution to the study of the large-scale structure of the Universe, structure and evolution of the Galaxy, and cross-identification of multiwaveband properties in celestial objects.

The Large sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) general survey is a spectroscopic survey that will eventually cover approximately half of the celestial sphere and collect 10 million spectra of stars, galaxies and QSOs. Objects in both the pilot survey and the first year regular survey are included in the LAMOST DR1. The pilot survey started in October 2011 and ended in June 2012, and the data have been released to the public as the LAMOST Pilot Data Release in August 2012. The regular survey started in September 2012, and completed its first year of operation in June 2013. The LAMOST DR1 includes a total of 1202 plates containing 2 955 336 spectra, of which 1 790 879 spectra have observed signalto-noise ratio (SNR) ≥ 10. All data with SNR ≥ 2 are formally released as LAMOST DR1 under the LAMOST data policy. This data release contains a total of 2 204 696 spectra, of which 1 944 329 are stellar spectra, 12 082 are galaxy spectra and 5017 are quasars. The DR1 not only includes spectra, but also three stellar catalogs with measured parameters: late A,FGK-type stars with high quality spectra (1 061 918 entries), A-type stars (100 073 entries), and M-type stars (121 522 entries). This paper introduces the survey design, the observational and instrumental limitations, data reduction and analysis, and some caveats. A description of the FITS structure of spectral files and parameter catalogs is also provided.

Massive efforts have been devoted to enhancing performances of Li–S batteries to meet the requirements of practical applications. However, problems remain in enhancing the energy density and improving the cycle life. We present a free-standing structure of walnut-shaped VS4 nanosites combine with carbon nanotubes (NTs) as cathodes. In this framework, NT arrays provide high surface area and conductivity for high sulfur loadings, and VS4 nanosites facilitate trapping and catalytic conversions of lithium polysulfides. The synergistic effects of free-standing NT arrays and VS4 nanosites have enabled high rate capability up to 6 C and long-term cycling with a low decay rate of 0.037% up to 1200 cycles at 2 C. Moreover, the designed cathode can achieve high areal capacities up to ∼13 mAh·cm–2 and estimated gravimetric energy density of 243.4 Wh·kg–1 at a system level, demonstrating great potential in practical applications of Li–S batteries.

This paper describes the data release of the LAMOST pilot survey, which includes data reduction, calibration, spectral analysis, data products and data access. The accuracy of the released data and the information about the FITS headers of spectra are also introduced. The released data set includes 319 000 spectra and a catalog of these objects.

HIGHLIGHTS• The tunable mechanisms of lateral heterostructures on both homogeneous junctions and heterogeneous junctions are summarized.• Electronic and photoelectronic devices with lateral heterostructures have been discussed.• Different types of contacts of 2D lateral heterostructures are classified. • Recent developments in synthesis and nanofabrication technologies of 2D lateral heterostructures are reviewed. ABSTRACT Recent developments in synthesis and nanofabrication technologies offer the tantalizing prospect of realizing various applications from twodimensional (2D) materials. A revolutionary development is to flexibly construct many different kinds of heterostructures with a diversity of 2D materials. These 2D heterostructures play an important role in semiconductor and condensed matter physics studies and are promising candidates for new device designs in the fields of integrated circuits and quantum sciences. Theoretical and experimental studies have focused on both vertical and lateral 2D heterostructures; the lateral heterostructures are considered to be easier for planner integration and exhibit unique electronic and photoelectronic properties. In this review, we give a summary of the properties of lateral heterostructures with homogeneous junction and heterogeneous junction, where the homogeneous junctions have the same host materials and the heterogeneous junctions are combined with different materials. Afterward, we discuss the applications and experimental synthesis of lateral 2D heterostructures. Moreover, a perspective on lateral 2D heterostructures is given at the end.

Carbon nitride compounds have emerged recently as a prominent member of 2D materials beyond graphene. The experimental realizations of 2D graphitic carbon nitride g-C 3 N 4 , nitrogenated holey grahpene C 2 N, polyaniline C 3 N have shown their promising potential in energy and environmental applications. In this work, we predict a new type of carbon nitride network with a C 9 N 4 stoichiometry from first principle calculations. Unlike common C-N compounds and covalent organic frameworks (COFs), which are typically insulating, surprisingly C 9 N 4 is found to be a 2D nodal-line semimetal (NLSM). The nodal line in C 9 N 4 forms a closed ring centered at  point, which originates from the p z orbitals of both C and N. The linear crossing happens right at Fermi level contributed by two sets of dispersive Kagome 2 and Dirac bands, which is robust due to negligible spin-orbital-coupling (SOC) in C and N. Besides, it is revealed that the formation of nodal ring is of accidental band degeneracy in nature induced by the chemical potential difference of C and N, as validated by a single orbital tight-binding model, rather than protected by crystal in-plane mirror symmetry or band topology. Interestingly, a new structure of nodal line, i.e., nodal-cylinder, is found in momentum space for AA-stacking C 9 N 4 . Our results imply possible functionalization for a novel metal-free C-N covalent network with interesting semimetallic properties.

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