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InSeBr-Type monolayers, ternary In(Se,S)(Br,Cl) compounds, are typical two-dimensional (2D) Janus materials and can be exfoliated from their bulk crystals. The structural stability, electronic properties, mechanical flexibility, and intrinsic piezoelectricity of these InSeBr-type 2D Janus monolayers are comprehensively investigated by first-principles calculations. Our calculations show that the stable InSeBr-type monolayers exhibit ultrahigh mechanical flexibility with low Young's moduli. Due to the amazing flexibility of the InSeBr monolayer with an ultra-low Young's modulus of 0.81 N m

The fruit of Terminalia chebula Retz., or Tibet Olive, is widely used as a food supplement in China. It possesses some natural antimicrobial properties; however, its chemical composition and antivirulence effects have not been identified. In this work, 29 compounds were identified from the peel of T. chebula fruit by ultra-high-performance liquid chromatography-tandem quadrupole time-of-flight mass spectrometry. Both the extract of T. chebula and its phenolic acid, corilagin, showed antivirulent activity against Staphylococcus aureus. Specifically, they inhibited biofilm formation. The half maximal inhibitory concentration was 0.13 and 3.18 µg/mL for the extract and corilagin, respectively, whereas for α-hemolysin secretion, the respective concentrations were 30 and 10 µg/mL. Its mechanism of action may be due to reducing the transcription of genes related to quorum sensing. These genes included staphylococcal accessory regulator A, intercellular adhesion accessory gene regulator A, and RNAIII. These findings provide evidence that this food supplement could be an effective antivirulent with corilagin as its active ingredient. PRACTICAL APPLICATION: Corilagin from the fruit of Terminalia chebula Retz. may be used as an antibacterial for its antivirulent activity against Staphylococcus aureus.

Giant liposome is an important lipid structure widely used in biological and medical fields. In its main preparation method, electroformation, many influencing factors must be optimized for good effect. How to collect the desired giant liposomes is another major issue. In this work, a microchip with a reactor chamber array was used to study the influences of multiple parameters, and a suitable condition could be achieved rapidly and efficiently. A tailor-made collection chamber was also integrated on the chip. Based on the multifactor and multilevel orthogonal experiment, optimal conditions of the lipid solution, buffer solution, and electric signal were achieved with high efficiency. More than one thousand giant liposomes could be formed in each microscale reactor chamber, and most of them were unilamellar. The on-chip collection ratio of giant liposome carriers could also approximate to 40%.

The helicon plasma source, which generates high thrust and high impulse, is of vital importance for magnetoplasma rocket engines. In this work, a multi-component, two-dimensional, axisymmetric fluid model coupled with an electromagnetic field was developed to model the helicon discharge. The simulation results demonstrate that: (i) the discharge mode changes twice—each conversion is accompanied by a plasma density jump and an electron temperature peak in the discharge; (ii) when the input current increases, the plasma density increases, and ionization occurs faster; (iii) the background magnetic field clearly enhances the discharge; (iv) the plasma density may be smaller if the discharge has not entered the wave mode.

Ion transport in nanofluidic devices and biological ion channels are highly dependent on the local environmental conditions in the electrolyte solution. Many life processes in living systems are in dynamic electrolyte solutions, and many of them are self-oscillated. Tuning ion transport through a nanofluidic diode by the self-oscillating chemical reactions is demonstrated by modeling the electrokinetic ion transport process with a validated continuum model, which includes the time-dependent Poisson-Nernst-Planck equations for the ionic mass transport of multiple ionic species with both volumetric and surface chemical reactions, and Stokes equations for the flow field. A pH oscillator caused by oscillating chemical reactions (i.e., bromate-sulfite-ferrocyanide system) is added at the tip side of the nanopore to periodically change its surface charge properties, consequently tuning the ion selectivity and ion transport through the nanopore. Results show that both the surface charge density of the nanopore and the electrokinetic ion transport phenomena oscillate simultaneously with the pH oscillation generated by the self-oscillating chemical reactions. The numerical results obtained by our model qualitatively agree with the published experimental observations.

Particle separation is important in chemical and biomedical analysis. Among all particle separation approaches, microstructure filtration which based particles size difference has turned into one of the most commonly methods. By controlling the movement of particles, dielectrophoresis has also been widely adopted in particle separation. This work presents a microfluidic device which combines the advantages of microfilters and dielectrophoresis to separate micro-particles and cells. A three-dimensional (3D) model was developed to calculate the distributions of the electric field gradient at the two filter stages. Polystyrene particles with three different sizes were separated by micropillar array structure by applying a 35-Vpp AC voltage at 10 KHz. The blocked particles were pushed off the filters under the negative dielectrophoretic force and drag force. A mixture of Haematococcus pluvialis cells and Bracteacoccus engadinensis cells with different sizes were also successfully separated by this device, which proved that the device can separate both biological samples and polystyrene particles.

The electromagnetic sail, a new space propulsion system without propellant, which propels a spacecraft by deflecting solar wind with an electromagnetic field, is proposed. The thrust mechanism and the performance variations of the electromagnetic sail are analyzed with both particles in cell and magnetohydrodynamic models, and the interaction between the incoming plasma fluid and the electromagnetic field is investigated by tests on the ground experimental system. The simulation results demonstrate that a magnetosphere is created in front of the sail and its area increases with magnetic field intensity; with appropriate dipole moment, the thrust of the electromagnetic sail is higher than a pure magnetic sail or a pure electric sail. In test experiments, the plume structure of a helicon plasma source changes obviously with coil current and metal mesh voltage, which verifies the repulsion of the magnetic field and electric field to the incoming plasma. These results indicate that the combination of the magnetic sail and electric sail can increase the utilization efficiency of solar wind, which means the electromagnetic sail is a feasible propulsion system.

Arc plasma can be applied in hazardous solid waste disposal for higher temperature than common heating methods, but some practical issues exist in practical engineering application. In this study, an air arc plasma torch with double chambers and magnetic controlling is designed to realize wide variable power and long electrode life. The detailed characteristics and laws of the air arc are studied. The condition parameters of arc current (I), air flow rate (G) and the structure parameters of inlet area ratios and electrode diameters influence both the arc voltage and arc root positions. The arc rotating driven by magnetic field effectively lengthens the electrode life. The gasification process and product of organic wastes by air plasma are influenced largely by the waste compositions and the air flow rate. A furnace structure with more even atmosphere and longer residence time should be considered for better gasification. Oxygen-deficient environment is important to suppress NO x formation during the application of air plasma. Inorganic solid wastes can be melt by the air plasma and cooled down to form compact vitreous structures in which heavy metals can be locked and the leaching rates significantly decrease down.

Liquid crystal (LC) droplets have been widely used in the detection of chemical and biological species due to their large surface area-to-volume ratio and stimuli-responsive configuration transitions. However, the wide size distribution and high mobility of LC droplets in current LC droplet-based platforms have limited their real-time and quantitative detection applications. Here, we report a novel monodisperse LC droplet-based polydimethylsiloxane (PDMS) microchip, in which monodisperse LC droplets are in situ generated and trapped on a single microfluidic device. A flow-focusing element and a hydrodynamic-based microstructure are designed for the generation and entrapment of monodisperse LC droplets, respectively. This miniatured monodisperse LC droplet-based microchip containing a fixed number of monodisperse LC droplets allows us to quantitatively and rapidly (

Large size of air plasma at near atmospheric pressure has specific effects in aerospace applications. In this paper, a two dimensional multi-fluid model coupled with Monte Carlo (MC) model is established, and some experiments were carried out to investigate the characteristics of electron beam air plasma at pressure of 100-170 Torr. Based on the model, the properties of electron beam air plasma are acquired. The electron density is of the order of 1016 m−3 and the longitudinal size can exceed 1.2 m. The profiles of charged particles demonstrate that the oxygen molecule is very important for air plasma and its elementary processes play a key role in plasma equilibrium processes. The potential is almost negative and a very low potential belt is observed at the edge of plasma acting as a protection shell. A series of experiments were carried out in a low pressure vacuum facility and the beam plasma densities were diagnosed. The experimental results demonstrate that electron density increased with the electron beam energy, and the relatively low pressure was favorable for gaining high density plasma. Hence in order to achieve high density and large size plasma, it requires the researchers to choose proper discharge parameters.

A fast two-step marker-controlled watershed image segmentation method in CIELAB color space is presented in this paper. We choose a number of seed points distributed nearly uniformly as the makers to perform the first marker watershed segmentation step, and obtain superpixels of the input image. These markers have the minimal gradient in a 3 ×3 neighborhood, which is able to avoid placing them at an edge and to reduce the chances of choosing a noise pixel. After superpixels segmentation, we do not adopt the traditional region merging strategies based on the different features of the adjacent regions, but cluster the superpixels in a 5-D space composed of Lab color vector and the position coordinates of the superpixels to resolve the over-segmentation problem, which saves a lot of computation time. Experiments on various types of images demonstrate that our algorithm is faster than many other segmentation algorithms and very suitable for real-time applications.

In this paper, we propose a novel framework of building extraction from high resolution satellite remote sensing images. This approach combines regional information with edge features, which could avoid the limitations of traditional methods. Firstly, the irrelevant regions are filtered out from large images by extracting texture features, leaving buildings distributed in the remaining urban areas. Secondly, boundaries of objects are extracted and all the contours are tracked through the chain code method we developed. Finally, the short straight lines are linked to construct contours and extract rectangular building rooftops. Experiments show that this extraction strategy is robust and effective.

An algorithm of airfield runway detection from high resolution synthetic aperture radar image is proposed. Runways are identified by using Hough transform technique, followed by a series of speckle suppression and region of interest (ROI) segmentation. First, speckle suppression based on edge preserving is described. Then, constant false alarm rate detector with probability iteration is used for ROI segmentation. Finally, peak values detected from Hough transform domain determine the edge location of runway. High resolution images are used to illustrate the algorithm, and experimental results show that performance is satisfactory.

Cell size is an important parameter for cell analysis and manipulation. Cell sample with similar size distribution can improve the performance in cell screening, cell electroporation and electrofusion. One approach for cell purification is to utilize constriction structures such as dams to trap cells in microfluidics. This paper presents a centrifugation and negative-dielectrophoresis assisted size-based cell separation method. The goal is to separate cell sample and get purified cells by size-based screening. We designed and fabricated a microfluidic chip with five octagon-shape screening-dams within a flow-through channel network. The radius of the octagon was from 10mm to 26mm, and the array space was 4 mm. The octagon-shape screening-dam contained hundreds of micro-filter and micro-dam structures. Each micro-filter was composed by two micro-dam structures. The width of filter between two adjacent micro-dams is 40, 30, 20, 15, 10 mm, respectively. After loaded cell sample into the central reservoir, the microfluidic chip was revolved in high speed. Cells with big size were immobilized and captured into micro-filter under centrifugal force. To avoid too much cells are concentrated into micro-filters and blocked these structures, negative-dielectrophoresis was applied per 2 minutes, to push cell leave to filter and move into independent chamber between two adjacent octagon-shape screening-dam arrays. In the end, purified cells with similar size were separated and collected into each independent chambers.

Using high-energy electron beams to ionize air is an effective way to produce a large-size plasma in the atmosphere. In particular, with a steady-state high power generator, some unique phenomena can be achieved, including natural convection of the plasma. The characteristics of this convection are studied both experimentally and numerically. The results show that an asymmetrical temperature field develops with magnitudes that vary from 295 K to 389 K at a pressure of 100 Torr. Natural convection is greatly enhanced under 760 Torr. Nevertheless, plasma transport is negligible in this convection flow field and only the plasma core tends to move upward. Parameter analysis is performed to discern influencing factors on this phenomenon. The beam current, reflecting the Rayleigh number Ra effect, correlates with convection intensity, which indicates that energy deposition is the underlying key factor in determining such convections. Finally, natural convection is concluded to be an intrinsic property of the electron beam when focused into dense air, and can be achieved by carefully adjusting equipment operations parameters.

To extract circular array targets from high-spatial resolution optical satellite images, we propose an efficient two-step detection framework. In the first stage, we propose a multiscale histogram contrast (MHC) saliency evaluation model to detect salient objects. This saliency model is able to highlight all salient areas with well-defined boundaries and effectively suppress the obvious background textures. Moreover, the generated saliency map can be used to find the locations of potential targets most likely causing visual attention, which greatly decreases the computation cost in later processes. In the second stage, we extract task-related targets from these salient objects by removing the irrelevant salient areas according to the special properties of the targets. In this paper, we present a circular array targets-detection method based on the saliency map produced by the proposed saliency detector. First we extract the circular objects from the saliency map using simple shape features, which are then clustered through a graph-based approach to locate the target areas. To evaluate the performance of our saliency model and targets extraction scheme, we carried out many experiments on large-field, high-spatial resolution remote-sensing images and achieved promising results both in efficiency and precision.

A self-consistent, diffusion-drift approximated fluid model including ion and electron continuity equations and an electron energy equation is presented for simulating the nonequilibrium characteristics during breakdown of argon rf glow discharge. The nonlinear partial differential equations of the model are solved numerically by using a so-called finite volume method. The numerical results indicate that there exist two different phases on the breakdown curves, i.e., the low p⋅d phase and high p⋅d phase. The breakdown voltage, analyzed for three different gaps, varies little in low p⋅d phase while in the high p⋅d phase, it increases linearly with pressure increase. Time evolution of Ohmic heating and energy loss during breakdown are presented in detail. Analysis yields that the heating mechanisms are the dominant factors in breakdown. Moreover, the steady discharge characteristics are also studied specifically under breakdown voltage of 10Torr. The charged particle densities are on the order of 1015∕m3 an...