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Compared to the three-dimensional (3D) perovskite materials, the Ruddlesden−Popper (R-P) type two-dimensional (2D) organic-inorganic metal halide perovskites have indicated specific unique physical properties that include moisture-stable behaviours, exciton effects, and quantum confinements, making it a solid and potential candidate for optoelectronic applications. Nonetheless, while specific candidates have exhibited visible-blind ultraviolet (UV) photoelectric response, most R-P type 2D materials have been known to be photosensitive to visible light. In this study, an R-P type 2D lead bromide hybrid perovskite (C8H11FN)2PbBr4, (1, where C8H10FN is 4-Fluorophenethylamine) has been analyzed, which contained both inorganic frameworks and organic cations. Moreover, 1 exhibits a relatively wide optical bandgap of 3.30 eV, corresponding to that of the Br-based 2D R-P perovskites expected to exhibit selective photoresponse for the UV light. It is pertinent to note that the photodetectors based on the crystal of 1 exhibit spectral selective photoresponse for UV light with high detectivity up to ∼ 1.6×1011 Jones. Moreover, the trap density of 1 is estimated to be 1.34×1011 cm-3; the trap density of 1 was almost equal to that obtained in the high-quality 3D CH3NH3PbBr3 single crystals. Besides, under external environment, 1 illustrated excellent stability. The figures of merit for its photoconductivity make 1 a potential candidate for the visible-blind UV photodetection. This discovery opens up new vistas for the further development of optoelectric devices based on 2D R-P organic-inorganic hybrid perovskites.

This article introduced a specific design and an effective, low-cost production method of the concentration gradient generator. It can generate different concentration at eight outlets. Deep resear...

An internal transport barrier (ITB) can be formed on EAST in exploring high-parameter operation. Previous studies show that safety factor (q) profiles, Shafranov shift and magnetohydrodynamic behaviors could be helpful in ITB formation by suppressing anomalous transport. Recently, electron density evolution with high resolution demonstrates that fishbone could be dominant in electron density ITB formation and sustainment. The power threshold is low in the fishbone condition and the electron density profile is determined by traits of fishbone. Simulation shows that the low-k ion mode is suppressed by fishbone. Direct measurement of turbulence in the inner region shows that the internal kink mode could sustain an electron temperature ITB by suppressing the trapped electron mode. The multi-scale interaction between the kink mode and turbulence by current could be key in sustaining high-electron-temperature long-pulse operation.

This paper describes a novel design and a simple, low cost fabrication method of concentration gradient generator which can generate the approximate linear and quadratic concentration gradient curves output. The concentration gradient generators were fabricated in polymethyl-methacrylate (PMMA). The gradient curves can be controlled by the flow velocities. The generator is designed and simulated using CAXA and COMSOL multiphysics, and the concentration gradient generated in the simulation and experiment was analyzed through Origin 8.0 software. The generator was fabricated with the CO2 laser processing machine and thermocompressor. We have carried out a deep research on the processing parameters of laser machine and got an ideal microchannel effect and the microchannels are processed using the CO2 laser processing machine on PMMA substrate. In addition, we also proposed a method of multiple bond to bond chip. Finally, the feasibility of simulation was clearly verified by a mixing experiment with blue ink and yellow ink. This simple microfluidic device can help the study of high-throughput concentration gradient applications such as cell biology of chemotaxis or hypotaxis.

In this study, the traditional hot rolling to fabricate Al/Ti laminated metal composites (LMCs) was improved by using a pre-rolling diffusion process. The effect of the pre-rolling diffusion on microstructure and mechanical properties of Al/Ti LMCs were investigated by various methods, such as optical microscope (OM), scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and tensile tests. The results show that, with increasing diffusion temperature, the thickness in diffusion layer was increased and the mechanical properties of LMCs were improved obviously, which was attributed to the optimized interfacial structure after diffusion process. In addition, the formation of TiAl3 intermetallic compounds (IMCs) was detected in the bonding interface, which played an important role in improving the mechanical properties for Al/Ti LMCs. The predicted results of stress-strain curves from rule of mixture (ROM) indicated that, there existed an extra interfacial strengthening in Al/Ti LMCs beside the mechanical properties provided by the contribution of constituent layers. The pre-rolling diffusion process is effective for the optimization of interfacial structure and improvement of mechanical properties in Al/Ti LMCs.

Extreme ultraviolet (EUV) spectra emitted from low-Z impurity ions in the wavelength range of 10–500 Å were observed in Experimental Advanced Superconducting Tokamak (EAST) discharges. Several spectral lines from K- and L-shell partially ionized ions were successfully observed with sufficient spectral intensities and resolutions for helium, lithium, boron, carbon, oxygen, neon, silicon and argon using two fast-time-response EUV spectrometers of which the spectral intensities are absolutely calibrated based on the intensity comparison method between visible and EUV bremsstrahlung continua. The wavelength is carefully calibrated using well-known spectra. The lithium, boron and silicon are individually introduced for the wall coating of the EAST vacuum vessel to suppress mainly the hydrogen and oxygen influxes from the vacuum wall, while the carbon and oxygen intrinsically exist in the plasma. The helium is frequently used as the working gas as well as the deuterium. The neon and argon are also often used for the radiation cooling of edge plasma to reduce the heat flux onto the divertor plate. The measured spectra were analyzed mainly based on the database of National Institute of Standards and Technology. As a result, spectral lines of He II, Li II–III, B IV–V, C III–VI, O III–VIII, Ne II–X, Si V–XII, and Ar X–XVI are identified in EAST plasmas of which the central electron temperature and chord-averaged electron density range in T e0 = 0.6–2.8 keV and n e = (0.5–6.0) × 1019 m−3, respectively. The wavelengths and transitions of EUV lines identified here are summarized and listed in a table for each impurity species as the database for EUV spectroscopy using fusion plasmas.

Titanium dioxide (TiO2) aerogels were prepared with sol–gel ambient pressure drying method by using titanium tetrachloride (TiCl4) as precursor and tetraethoxysilane as modifier, calcinated at different temperature and characterized by X-ray diffraction, transmission electron microscopy and small angle X-ray scattering. The results showed that the TiO2 aerogels remained amorphous under 500 °C, changed to anatase from 600 °C and further changed to rutile from 900 °C. Between 60 °C and 500 °C, the primary particles within the samples concentrated mainly upon small sizes, enlarged and diverged remarkably above 600 °C. The crystalline grains grew and agglomerated with the rise of the calcination temperature. The TiO2 aerogels at a temperature higher than 800 °C have better stability than anatase because of the formation of partial Ti―O―Si bonds. Copyright © 2016 John Wiley & Sons, Ltd.

Understanding the relationship between the changes in the axonal transport of the optic nerve (ON) and lamina cribrosa (LC) deformation will be helpful to estimate the degree of axonal transport block by measuring the LC deformation in vivo. First, the changes in the axonal transport of the ON were studied using an acute high intraocular pressure (IOP) model, which was established by perfusing saline water into the anterior chamber of cats. The IOP of cat was unilaterally elevated to and maintained at 30, 40, and 50[Formula: see text]mmHg. The axonal transport of the ON was examined by confocal laser scanning microscope. Then the deformations and stress distributions of the LC and ON were calculated using a three-dimensional finite element model of the LC microstructure including ON. The results showed axonal transport changes of ON increased with elevation of the IOPs. While Young’s modulus of the LC and ON were assumed as 0.1[Formula: see text]MPa and 0.03[Formula: see text]MPa, the numerical simulation results showed that LC had displacements of 0.02, 0.03, and 0.04[Formula: see text]mm backward at the IOPs of 30, 40, and 50[Formula: see text]mmHg, respectively. The calculated compressive strain applied to the ON were 0.0425, 0.0567, and 0.0709 under 30, 40, and 50[Formula: see text]mmHg IOP, respectively. The results of strain and stress analysis of LC and ON showed that the deformation of LC would compress the ON. The axonal transport abnormalities could be inferred by measuring the LC deformation in vivo.

We report on current profile evolution in EAST NBI driven plasmas where two neutral beams are injected, one during the current ramp phase and the second during flattop. At the end of the current ramp phase, it is found that a flat q profile with q 0 ~ 1 is achieved with low magnetic shear in the core. It is observed that plasma current and density both relax much faster than resistive time, even in the absence of sawtooth activity when H–L transition occurs. Density fluctuations associated with magnetic perturbations (3/2) as a precursor to the H–L transition are observed. It is likely that these modes play a role in fast current transport.

Increasing the density in a tokamak is limited by the so-called density limit, which is generally performed as an appearance of disruption causing loss of plasma confinement, or a degradation of high confinement mode which could further lead to a H → L transition. The L-mode and H-mode density limit has been investigated in EAST tokamak. Experimental results suggest that density limits could be triggered by either edge cooling or excessive central radiation. The L-mode density limit disruption is generally triggered by edge cooling, which leads to the current profile shrinkage and then destabilizes a 2/1 tearing mode, ultimately resulting in a disruption. The L-mode density limit scaling agrees well with the Greenwald limit in EAST. The observed H-mode density limit in EAST is an operational-space limit with a value of . High density H-mode heated by neutral beam injection (NBI) and lower hybrid current drive (LHCD) are analyzed, respectively. The constancy of the edge density gradients in H-mode indicates a critical limit caused perhaps by e.g. ballooning induced transport. The maximum density is accessed at the H → L transition which is generally caused by the excessive core radiation due to high Z impurities (Fe, Cu). Operating at a high density () is favorable for suppressing the beam shine through NBI. High density H-mode up to could be sustained by 2 MW 4.6 GHz LHCD alone, and its current drive efficiency is studied. Statistics show that good control of impurities and recycling facilitate high density operation. With careful control of these factors, high density up to 0.93 stable H-mode operation was carried out heated by 1.7 MW LHCD and 1.9 MW ion cyclotron resonance heating with supersonic molecular beam injection fueling.