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In this paper, Al-7%Si-0.6%Mg-X%Ce (X = 0, 0.1 and 0.2) casting alloys were prepared by vacuum induction furnace. Using optical microscopy (OM), x-ray diffractometer (XRD), scanning electron microscopy (SEM), energy spectrometry (EDS), differential scanning calorimetry (DSC) and transmission electron microscopy (TEM), the microstructures of the experimental alloys were studied, and the mechanism of refinement and modification of the alloy were discussed. Results show that for Al-Si alloy, AlCeSi _2 is formed by adding cerium element into aluminum alloy. Furthermore, with the increase of cerium addition, α - Al dendrite arms decrease, the AlCeSi _2 was formed, and the growth of iron-rich phase was hindered, respectively. Also, the areas of eutectic of α -Al + Si were decreased, due to the supercooling increasing of the alloys. In addition, the α -Al grains were refined, because existing of heterogeneous nucleation core supplied by AlCeSi _2 , and component supercooling caused by cerium adding. Moreover, the formation of AlCeSi _2 consumed to some silicon elements, which leaded to size and amount reduction of eutectic silicon. The formation of high-density stacking fault can induce silicon modified, and the formed high-density stacking fault was produced by cerium as impurity element into silicon.

With the increasing demand for the application of electronic technology, high performance, multi-function and intelligent control have been the main developing trend of smart material. In this paper, a novel thermal-induced epoxy shape memory polymer (ESMP) is developed and utilized as substrate material for smart flexible electronic device. Owing to the advantage of thermal-induced ESMP, circuit substrate can be rigid-flexible controllable at different working temperature. Firstly, the ESMP samples are prepared and then the mechanical and shape memory characteristics are studied respectively. Secondly, the mechanical behaviors are analysed based on thin plate deflection theory and finite element simulation software on the engineering application. Meanwhile, corresponding experimental tests are designed and performed to corroborate the theory and simulation results. At last, ESMP based test circuit board is designed and manufactured. The electrical signals under large deformation are also measured and compared with typical circuit board. The results show that the prepared ESMP, as a smart material, has good reliability, flexibility and great application prospects in the field of intelligent devices.

Several reports reveal that high level of C-reactive protein (CRP) in serum enhances venture of diabetes. In this article, we presented a platform which blended Zr(IV)-organic framework with 2,5-thiophenedicarboxylate ligand (Zr-tdc) and ionic liquid (IL) to form a steady composite membrane on the carbon paste electrode (CPE). The platform was applied to CRP and glucose biosensors which were connected with diabetes and displayed well performances. Firstly, a sensitive immunosensor for label-free and direct detection of CRP was developed at Zr-tdc/IL modified electrode. Under optimal conditions, differential pulse voltammetry (DPV) response showed the low detection limit of CRP was 0.2 ng/mL. Secondly, the glucose biosensor immobilized glucose oxidase (GOX) was constructed and studied by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and amperometric response. TheMichaelis-Menten constant (KM) of immobilized GOX was 0.16 mM, and the detection limit was 2.7 µMfor glucose. Two novel biosensors displayed well selectivity, stability and lower detection limit. This work improved the performance of electrochemical sensing and expand the utilization of the material by carrying on the effective immobilization of enzyme and antibody. [ABSTRACT FROM AUTHOR]

novel Pd/SnO2-TiO2/multiwalled carbon nanotube (MWCNT) catalyst was synthesized using a facile and controllable in situ chemical method. Pretreated TiOi was anchored to a functional MWCNT template, which was used as a support material to enhance the stability and electrical conductivity of the Pd nanoparticles. The Sn(ll) ions adsorbed on the surface of the TiO2 precursor acted as reducing agents and ensured that Pd reduction only occurred on the precursor surface. The physicochemical properties of the catalyst were determined by transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The results showed that small metallic Pd nanoparticles were evenly dispersed over the catalyst surface. Cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy were used to evaluate the electrocatalytic properties of the Pd/SnO2-TiO2/MWCNT catalyst in an alkaline solution containing 0.5 M NaOH and 1.0 M ethylene glycol. The high dispersion of the metallic Pd nanoparticles caused by the presence of the SnO2-TiO2 precursor significantly enhanced the electrocatalytic activity and tolerance of the catalyst to the accumulation of carbonaceous species. This new Pd/SnO2-TiO2/MWCNT catalyst is a promising candidate for use in the oxidation of ethylene glycol under alkaline conditions. [ABSTRACT FROM AUTHOR]

Ruthenium (Ru) chemical mechanical planarization (CMP) with a slurry using sodium periodate (NaIO4) as an oxidizer was carried out as a function of pH. The Ru polishing rate was highest at pH 7 and decreased as the pH decreased or increased. In addition, a similar trend in the corrosion current density as a function of pH was found. Two equivalent circuit models were proposed to explain the electrochemical impedance spectroscopy (EIS) results of Ru in NaIO4 solution as a function of pH. From results of EIS, we found that the Ru film had a lowest charge transfer resistance in a neutral region than that in an acidic or alkaline region. This different charge transfer resistance of the Ru film as a function of pH resulted from the different surface composition of Ru oxide species, which was analyzed with X-ray photoelectron spectroscopy. Finally, we briefly derived a series of reaction equations between Ru and NaIO4 on the basis of the above results and discussion. [ABSTRACT FROM AUTHOR]

We investigated the chemical mechanical planarization (CMP) mechanism of nitrogen-doped polycrystalline Ge2Sb2Te5 (pc-GST) using nitric acid slurry without or with 1.0 wt % hydrogen peroxide (H2O2). Without H2O2, the pc-GST film surface undergoes selective corrosion of Ge and Sb, resulting in pitting corrosion. Otherwise, with H2O2, the pc-GST film surface produces a Ge, Sb, Te oxide layer, thereby introducing a cyclic polishing process such as chemical oxidation, chemical and mechanical polishing, and sequential chemical oxidation. As a result, the polishing rate increased up to ~1000 Å/min and the surface roughness decreased to 0.858 nm. [ABSTRACT FROM AUTHOR]

For phase-change memory beyond the 30 nm design rule, chemical mechanical planarization (CMP) performing at a high polishing rate, reasonable selectivity, and no corrosion-induced pits is essential for planarizing nitrogen-doped polycrystalline Ge2Sb2Te5 (OST) deposited on the confined memory cell structure. We develop a new alkaline slurry added with KMnO4 used as an oxidizer. The alkaline slurry added with 0.3 wt % KMnO4 has a polycrystalline OST film polishing rate of 5200 Å/min, a polishing rate selectivity between polycrystalline GST and SiO2 film of 100:1, and no corrosion-induced pit. In addition, poly- crystalline GST film CMP using the alkaline slurry added with KMnO4 is observed to follow a cyclic reaction polishing mechanism. [ABSTRACT FROM AUTHOR]

Using chemical mechanical polishing (CMP) slurry for multiselectivity among SiO2, Si3N4, and poly-Si films is essential for NAND flash memory cells beyond 32 nm to reduce the dependency of the polishing rate on the pattern density in a chip. The polishing rate selectivity is controlled with an anionic surfactant [poly(acrylic acid) (PAA)] at the beginning of the CMP process and is controlled by a nonionic surfactant [poly(vinyl pyrrolidone) (PVP)] for continuous CMP. The selective absorption of PAA on a Si3N4 film surface suppresses the polishing rate of the Si3N4 film, whereas the selective absorption of PVP on a poly-Si film surface suppresses the polishing rate of the poly-Si film. We achieved multiselectivity among SiO2, Si3N4, and poly-Si films of ∼65: ∼ 15:1 in a nanoceria-based slurry with a PAA concentration of 0.05 wt % and a PVP concentration of 0.2 wt %. [ABSTRACT FROM AUTHOR]

In this research, we sought to determine the optimal size of the current blocking layer (CBL) in a vertical light-emitting diode (V-LED) for maximized output power. As the area of the CBL increased, the amount of light generated from the active region in the V-LED decreased due to the increase in local current density in the active region; at the same time, the amount of light extracted from the V-LED chip increased due to minimized obstruction from the n-electrode. The total output power (product of the light generated from the active region and the light extracted from the chip) of a V-LED was calculated as the size of the CBL was varied and was found to be maximized when the size of the CBL was larger than that of the n-electrode. In a circular n-electrode with a diameter of 120 μm, the optimal size (diameter) of the CBL was found to be 220 μm; in a 3 × 3 mesh type n-electrode with a 20 μm stripe width, the optimal CBL was found to be 40 μm stripe width. [ABSTRACT FROM AUTHOR]

In the fabrication of cross-point phase-change-memory-cells through atomic-layer-deposition of Ge-doped SbTe (Ge-ST) film followed by chemical-mechanical-polarization (CMP), a remarkable surface tensile stress was generated, originating from the surface stress induced by the pad down force and the surface structure tensile stress in a confined memory-cell structure. It was maximized at the position of the Si3N4-film spacer where the curvature becomes zero. The maximized surface tensile stress produced polishing induced voids via the generation mechanism of the stress corrosion cracking. The generation frequency and nanoscale size of the polishing induced voids rapidly increased at the maximum surface tensile stress during CMP. Then, they slightly decreased and saturated when the surface tensile stress reduced during further CMP. A design of a spacer using a SiO2-film spacer rather a Si3N4-film spacer could prevent the generation of the polishing induced voids, confirming that the generation mechanism of the polishing induced voids is associated with the stress corrosion cracking. [ABSTRACT FROM AUTHOR]

Bird flight is a remarkable adaption that has allowed thousands of species to colonize all terrestrial habitats. A golden eagle has impressive flying abilities, such as hovering, perching, preying and attacking. To reveal the flying abilities, avian geometry of a golden eagle was extracted based on noncontact surface measurements using a ROMBER three-dimensional laser scanner. Distributions of a camber line, thickness and a secondary feather line of the extracted point cloud were fitted using convenient analytical expressions. A traditional airfoil was established with the camber line and thickness, then a combined airfoil was constructed by combining the traditional airfoil with a secondary feather. Oscillations of an airfoil as well as rapid pitch up were simplified as a sine wave around the quarter chord axis. Thereafter, both steady and unsteady aerodynamic performances of the airfoil are computed, the influences of the secondary feather on the steady and unsteady aerodynamics were further studied. [ABSTRACT FROM AUTHOR]

Bimetallic nanoparticles (NPs) often exhibit improved catalytic performance due to the electronic and spatial structure changes. Herein, a novel green biosynthesis method for Pd–Pt alloy NPs using Shewanella oneidensis MR-1 was proposed. The morphology, size and crystal structure of Pd–Pt alloy NPs were studied by a suite of characterization techniques. Results showed Pd–Pt alloy NPs were successfully synthesized inside and outside the cell. The biosynthesized Pd–Pt alloy NPs were polycrystalline and face-centered-cubic structure with the particle size ranged from 3–40 nm. Furthermore, the catalytic experiment demonstrated that the Pd–Pt alloy NPs exhibited the highest performance for the catalytic reduction of nitrophenol and azo dyes compared with the as-synthesized Pd and Pt monometallic NPs. This enlarged catalytic activity resulted from the synergistic effect of Pd and Pt element. Thereby, this paper provided a simple biosynthesis method for producing bimetallic alloy nanocatalyst with superior activity for contaminant degradation. [ABSTRACT FROM AUTHOR]