Edge shear flow and its effect on regulating turbulent transport have long been suspected to play an important role in plasmas operating near the Greenwald density limit n G . In this study, equilibrium profiles as well as the turbulent particle flux and Reynolds stress across the separatrix in the HL-2A tokamak are examined as n G is approached in ohmic L-mode discharges. As the normalized line-averaged densityn e /n G is raised, the shearing rate of the mean poloidal flow ω sh drops, and the turbulent drive for the low-frequency zonal flow (the Reynolds power P Re ) collapses. Correspondingly, the turbulent particle transport increases drastically with increasing collision rates. The geodesic acoustic modes (GAMs) gain more energy from the ambient turbulence at higher densities, but have smaller shearing rate than low-frequency zonal flows. The increased density also introduces decreased adiabaticity which not only enhances the particle transport but is also related to reduction in the eddy-tilting and the Reynolds power. Both effects may lead to cooling of edge plasmas and therefore the onset of MHD instabilities that limit the plasma density.1
The DArk Matter Particle Explorer (DAMPE) satellite has been successfully launched on the 17th December 2015. It is a powerful space detector designed for the identification of possible Dark Matter signatures thanks to its capability to detect electrons and photons with an unprecedented energy resolution in an energy range going from few GeV up to 10 TeV. Moreover, the DAMPE satellite will contribute to a better understanding of the propagation mechanisms of high energy cosmic rays measuring the nuclei flux up to 100 TeV. DAMPE is composed of four sub-detectors: a plastic strip scintillator, a silicon-tungsten tracker-converter (STK), a BGO imaging calorimeter and a neutron detector. The STK is made of twelve layers of single-sided AC-coupled silicon micro-strip detectors for a total silicon area of about 7 m 2 . To promote the conversion of incident photons into electron-positron pairs, tungsten foils are inserted into the supporting structure. In this document, a detailed description of the STK construction and its performance on orbit are reported.
information, the ability to encrypt information has more important significance in information security. Nowadays, many scientists focus on the development of latemodel anti-counterfeiting materials, and corresponding strategies, [1][2][3][4] including bar code, two-dimensional code, holograms, luminous materials, and so on. Among them, luminous materials can be one of the best candidates for anti-counterfeiting due to their responsiveness to UV light, [5,6] the diversity of vivid colors [7,8] as well as various luminescence modes. [9,10] Given the excellent modifiability, containment and unique stimulus-responsiveness of polymeric hydrogels, [11][12][13][14] the combination of luminescence materials and intelligent hydrogels can make the stored information dynamic and improve security level. Up to now, a large number of studies have focused on information storage or information encryption [15][16][17][18] on the basis of fluorescent hydrogels. For example, Ji's group [19] fabricated a self-assemble hydrogel with polyvinyl alcohol (PVA) hydrogel doping three kinds of aggregation induced emission (AIE) fluorescent monomers. The prepared multi fluorescent hydrogel could store a large amount of information by introducing 1D barcodes or 2D codes and arraying the fluorescent blocks. Saunders and coworkers [20] employed microgels (MG) as As one of the severe global problems, counterfeiting information has brought a huge negative impact on every aspect of human society. Though various anticounterfeiting strategies, including fluorescent materials, are widely developed for dealing with the above problem, the information security level needs to be further improved due to sophisticated hacking techniques. In this study, an organohydrogel is designed by constructing interpenetrating organohydrogel networks, in which naphthalimide moieties (DEAN, greenyellow emission) are introduced in hydrophilic poly(N,N-dimethylacrylamide) (PDMA) hydrogel network and anthracene units (blue emission) are copolymerized in hydrophobic polystearate methacrylate (PSMA) organogel network. Triggered by UV light of 365 nm, the unimer-dimer transition occurs and leads the fluorescent color of organohydrogel to change from blue to faint yellow, making secret information be stored with the assistance of photomasks. Furthermore, by combining crystallization-induced shape memory performance, dual encryption can be achieved. This fluorescent organohydrogel provides a new idea for fabricating smart materials with the ability of encryption-decryption, which is of great significance in information security protection.
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