A novel two-step etching to suppress the charging damages duringmetal etching employing helicon wave plasma

A two-step etching has been performed to eliminate the plasma charging damages during helicon-wave plasma metal etching without selectivity loss. This technique utilized a normal etching recipe to remove the Al film followed by an optimized etching recipe for the overetching step. By increasing the bias power and decreasing the source power, the optimum etching recipe can target the plasma more directionally and reduce the Al charging damages. Eventually, the damage mechanism was also reported     

Expression of the retinoblastoma (RB) tumor suppressor gene inhibits tumor cell invasion in vitro

To determine if replacement of the retinoblastoma (RB) tumor suppressor gene could inhibit invasion of RB-defective tumor cells, the capacity of tumor cells to migrate or invade was quantitated by the Boyden chamber assay. The studies were done in a diverse group of stable RB-reconstituted human tumor cell lines, including those derived from the osteosarcoma and carcinomas of the lung, breast and bladder. The expression of the exogenous wild-type RB protein in these tumor cell lines was driven by either a constitutively active promoter or an inducible promoter. It was found that significantly more tumor cells from the parental RB-defective cell lines and the RB revertants than from the RB-reconstituted RB+ cell lines penetrated through the Matrigel (P<0.001, two-tailed t-test), although both RB+ and RB- cells migrated at approximately the same rate on uncoated polycarbonate filters in the Boyden chambers. Of note, the inhibition of invasiveness of various RB-defective tumor cells by RB replacement was apparently well correlated with suppression of their tumorigenicity in vivo. In contrast, although either functional RB or p53 re-expression effectively suppressed tumor formation in nude mice of the RB-/p53null osteosarcoma cell line, Saos-2, replacement of the wild-type p53 gene had much less impact on their invasiveness as compared to the RB gene. These studies provided an insight into the broader biological basis of the RB-mediated tumor suppression in RB-defective tumor cells.     

New peracid-type polymeric initiator for radical polymerization

In this study, a radiation-induced copolymer, namely polyethylene-g-acrylic acid powder, was used, whose carboxyl groups can be oxidized to form a highly reactive polymer initiator. The activation energy for its decomposition is 22.4 kcal/mol. It was found that the peracid-type polymeric powder was effective as an initiator for radical polymerization. It had high reactivity toward 2-hydroxyethyl methacrylate (HEMA), which could be easily grafted onto the polymeric powder; also, the homopolymer could be obtained. The kinetic investigation indicated that this polymerization proceeded by a radial mechanism, and the overall activation energy of homopolymerization was 18.67 kcal/mol and the overall activation energy of bigraft polymerization was 17.35 kcal/mol. By using the peracid-type polymeric powder as initiator for the copolymerization of methyl methacrylate with styrene, it was confirmed that the polymerization initiated by the peracid-type polymeric powder was a radical reaction.     

Defect engineering of ZnO: Review on oxygen and zinc vacancies

ZnO is an important material which has been widely applied in photodetector, catalyst, gas sensor, field emitter, etc. Yet, its inability to absorb visible light, poor charge transport, and low conductivity limit the application of these devices. Recently, it was discovered that introduction of defects such as oxygen and zinc vacancies into ZnO can effectively improve the existing properties or lead to new and unexpected yet highly desirable characteristics. Herein, we present a systematic review on the available approaches to synthesize oxygen- and/or zinc-deficient ZnO with emphasis on their chemical, structural, and electrical particularities. Furthermore, applications of defective ZnO in various nanoscale devices are discussed in terms of their functionality, reliability, and performance. Finally, we summarize major challenges and offer perspectives for further research in this field. We hope that this review would make a valuable contribution to broaden the knowledge of defective ZnO.     

Design of the PID Controller for Hydro-turbines Based on Optimization Algorithms

In this study, multiple objective particle swarm optimization (MOPSO), genetic algorithm, bees, and reinforcement learning (RL) are used to calculate the rise time (tr), integral square-error, integral of time-multiplied-squared-error, integral absolute error, and integral of time multiplied by absolute error of the system transfer function and then we use a fuzzy algorithm on MOPSO, GA, bees, and RL based on the frequency sensitivity margin of a water turbine governor to optimize the proportional gain (kp) and integral gain (ki) and calculate the relative collapsing frequency response values. The MOPSO algorithm returned the optimal result. The radial basis function (RBF) neural network curve is obtained from the MOPSO algorithm with three variables (i.e., kp, ki, kd = 0.6 and grid frequency deviations values), and finally we identify and predict three variable values near the RBF neural network curve through deep learning. The result of the grid frequency deviation is close to 0, and the gain response time is better for damping the frequency oscillations in different operating conditions.

     

Illumination system for wire bonding inspection

A novel lighting system was devised for 3D defect inspection in the wire bonding process. Gold wires of 20 microm in diameter were bonded to connect the integrated circuit (IC) chip with the substrate. Bonding wire defects can be classified as 2D type and 3D type. The 2D-type defects include missed, shifted, or shorted wires. These defects can be inspected from a 2D top-view image of the wire. The 3D-type bonding wire defects are sagging wires, and are difficult to inspect from a 2D top-view image. A structured lighting system was designed and developed to facilitate all 2D-type and 3D-type defect inspection. The devised lighting system can be programmed to turn the structured LEDs on or off independently. Experiments show that the devised illumination system is effective for wire bonding inspection and will be valuable for further applications.     

Organic nanowire-templated fabrication of alumina nanotubes by atomic layer deposition

Alumina nanotubes were fabricated by a template method. Tris-(8-hydroxyquinoline) gallium (GaQ3) organic nanowires were used as a soft template for coating with alumina using an atomic layer deposition technique. The deposition was conducted at 25 degrees C by using trimethylaluminum and distilled water as the precursors of Al2O3. Amorphous alumina nanotubes were obtained after removing the GaQ3 by dissolving in toluene or by heat treatment at 350 degrees C. The amorphous nanotubes could be crystallized by heating at 900 degrees C for 1 h in vacuum.     

Effect of interstitial boron and carbon on the hydrogenation properties of Ti25V35Cr40 alloy

Doping of interstitial elements B or C into a BCC-type Ti₂₅V₃₅Cr₄₀ alloy to raise effective desorption hydrogenation capacity was investigated. Ti₂₅V₃₅Cr₄₀M_x alloys (M = B or C and x = 0, 0.1, 1, or 5) were prepared by arc-melting followed by homogenization treatment. X-ray diffraction shows that the as-cast specimens have a BCC structure, but they contain some amount of precipitates that increases with the doping concentration of B and C. Doping-induced precipitates can be greatly eliminated by annealing treatment at 1200 °C, indicating that B or C might have been partially dissolved into the interstitial sites in the BCC lattice of matrix phase of specimens. With the doping of C, the second plateau pressure of annealed specimens in the PCI curves at T = 30 °C significantly increases with the amount of C, but the maximum hydrogenation capacity is reduced. On the other hand, the second plateau pressure and maximum hydrogenation capacity are only slightly affected by the B doping. Under optimum doping conditions, the effective hydrogen desorption capacities are increased from 0.80 H/M of the sample without doping to 0.86 H/M and 0.87 H/M for Ti₂₅V₃₅Cr₄₀B₁ and Ti₂₅V₃₅Cr₄₀C_0.1, respectively. The improvement might be ascribed to the increase in second plateau pressure caused by less stable hydrogen atoms at the lattice sites of Ti₂₅V₃₅Cr₄₀ containing interstitial B or C.     

Numerical predictions of a PEM fuel cell performance enhancement by a rectangular cylinder installed transversely in the flow channel

This paper numerically investigates the installation of the transverse rectangular cylinder along the gas diffusion layer (GDL) in the flow channel for the cell performance enhancement of a proton exchange membrane fuel cell (PEMFC). The effects of the blockage at various gap sizes and the width of the cylinder on the cell performance enhancement have been studied with changing the gap ratios λ = 0.05–0.3, for the same cylinder) and the width-to-height ratios (WR = 0.66–1.66, for the same cylinder height and gap ratio). The results show that the transverse installation of a rectangular cylinder in the fuel flow channel effectively enhances the cell performance of a PEMFC. In addition, the influence of the width of the cylinder on the cell performance is obvious, and the best cell performance enhancement occurs at the gap ratio 0.2 among the gap ratios of 0.05, 0.1, 0.2, and 0.3.