A facile and powerful method to form micropatterns, based on nanosphere lithography and layer-by-layer self-assembly, is described in this paper. A monolayer of hexagon close-packed polystyrene (PS) spheres (av 600 nm) was employed as the template. A positively charged polyelectrolyte of poly(diallydimethylammonium) chloride was used as adhesive to absorb oppositely charged spherical Au (av 17 nm) and spherical Ag (av 12 nm), respectively. Both the PS and substrates were coated by colloidal nanoparticles. After removal of the PS template, a micropatterning surface was obtained. Scanning electron microscopy and atomic force microscopy were used to characterize the morphologies. These resulting patterns can be used as good surface-enhanced Raman scattering (SERS) substrates. The enhancement factor is calculated to be 104 ∼ 105. This is a simple and facile technique for surface modification of metal micropatterns with SERS analytical application.
Discrete Cosine Transform (DCT) plays an important role in the image and video compression, and it has been widely used in JPEG, MPEG, H.26x. DCT being implemented by hardware is crucial to improve the speed of image compression. This paper presents a method that 2-D DCT is implemented by FPGA, which is based on the algorithm of row-column decomposition, and the parallel structure is used to achieve high throughput. The design is achieved by top-down design methodology and described with Verilog HDL in RTL level. The hardware of 2-D DCT is implemented by the FPGA EP2C35F672C8 made by ALTERA. The experiment results show that the delay time is as low as 15 ns, and the clock frequency as high as 138.35 MHz, which can satisfy the requirements of the real-time video image compression.
Metal film/elastomer-based strain sensors usually exhibit small rupture strain (<5%) because of the strain localization and necking effect of the metal film under tension. To achieve both high stretchability and wide linear region is still challenging for metal film-based strain sensors. Here, we propose a low-cost yet effective strategy for fabricating ultrathin, breathable, and skin-mountable strain sensors with high sensitivity (gauge factor from 7.2 to 474.8), high stretchability (up to 140%), and good linearity by regulating the surface strain delocalization in the metal film on elastomer substrate. On the basis of this phenomenon of strain delocalization, the sensitivity and linearity are further enhanced based on a novel diffraction-induced Au film with gradient thickness. Meanwhile, by means of the strain redistribution and Poisson effect, a novel biaxial strain sensor is designed for recognition of complex human motion. On the basis of the enhanced stretchability, linearity, skin-mountable, and breathable properties, the low-cost metal film-based strain sensors can be broadened as disposable wearables for human motion detection, emotional expression recognition, human interaction, and virtual reality.
AgBr nanoparticles supported on graphitic-C3N4-decorated nitrogen-doped graphene intercorrelated ternary superhybrid composites (ACNNG-x) acting as a novel visible-light driven photocatalyst are reported. Because of the fast interfacial charge separation and photoelectrochemical performance, the representative of ACNNG-50 superhybrid structure achieves high efficiency and stable photocatalytic capability for organic contaminant degradation and CO2 reduction.
Abstract The achievable functionalities of metasurfaces are mainly determined by the capability of their unit cells to control the local electromagnetic responses. To realize full control over light, it is highly desired to find a kind of unit cell that can achieve complete control of the phase, amplitude, and polarization, which remains a big challenge and cannot be fully replaced with iteration algorithms. Here, such control is achieved by exploiting interference in a dielectric unit cell composed of multiple meta‐atoms, namely, a meta‐molecule. This strategy provides sufficient effective geometric degrees of freedom within the meta‐molecule to enable full control over its optical properties, as is demonstrated here with a complete meta‐molecule database. As a proof‐of‐concept demonstration, polarization‐independent, polarization‐dependent, and vectorial meta‐holograms are proposed and experimentally characterized. High imaging quality is achieved in both the measured intensity and phase distributions. This is allowed by the ability of the meta‐molecules to fully record the information of the target images. This strategy opens a direct way toward optical devices with various desirable functionalities.
A novel, xylanolytic, anaerobic, moderately thermophilic bacterium, strain PML14T, was isolated from the sludge of a thermophilic anaerobic digester treating municipal solid waste and sewage in Beijing, China. The strain was a Gram-positive, spore-forming and motile rod. Growth of the novel strain was observed at 25–67 °C (optimum 60 °C) and pH 5.8–9.3 (optimum pH 8.5). Strain PML14T grew on a number of carbohydrates, including xylan, xylose, glucose and cellobiose, and a variety of proteinaceous compounds, including peptone, tryptone, Casamino acids, yeast extract, beef extract, casein hydrolysate, l-cysteine, l-serine, l-lysine, l-glycine, l-threonine, l-methionine and pyruvate. The fermentation products from glucose included acetate, ethanol, butyrate, hydrogen and carbon dioxide. Propionate was produced from xylan in addition to other compounds. Fe(III), 9,10-anthraquinone 2,6-disulfonate and thiosulfate were reduced with peptone as the electron donor. NH3 was produced. Indole was not produced. Gelatin was not hydrolysed. The DNA G+C content of strain PML14T was 36.2±0.8 mol% (T m). Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain PML14T was related to the members of cluster XII of the clostridia, most closely to Tepidimicrobium ferriphilum SB91T with 93.8 % 16S rRNA gene sequence similarity. On the basis of polyphasic evidence from this study, it is suggested that strain PML14T (=CGMCC 1.5080T=JCM 15035T) represents a novel species of the genus Tepidimicrobium, for which the name Tepidimicrobium xylanilyticum sp. nov., is proposed. An emended description of the genus Tepidimicrobium is also provided.
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