Bacterial community analysis during fermentation of ten representative kinds of kimchi with barcoded pyrosequencing

Kimchi, a food made of fermented vegetables, is densely populated by indigenous microorganisms that originate from the raw ingredients under normal conditions. Most microbiological studies on kimchi have been on the most popular dish, baechu-kimchi (Chinese cabbage kimchi). Therefore, relatively little is known about the various other kinds of kimchi (depending on the region, season, main ingredient, starter culture inoculation and recipe). In this study, we collected 100 samples periodically during the fermentation of ten representative kinds of kimchi (including starter-inoculated kimchi) that were stored in the refrigerator (4 °C) during the 30−35 days fermentation period. The multiplex barcoded pyrosequencing of a hypervariable V1−V3 region of the 16S ribosomal RNA (rRNA) gene tagged with sample-specific barcodes for multiplex identifiers was employed for bacterial community profiling. We found that bacterial communities differed between starter-inoculated and non-inoculated kimchi at the early stages of fermentation, but overall there were no significant differences in the late phases. Also, the diversity and richness of bacterial communities varied depending on the various types of kimchi, and these differences could largely be explained by the major ingredients and the manufacture processes of each types of kimchi. This study provides the comprehensive understanding of the factors influencing the biodiversity of the kimchi ecosystem.     

Characteristics of Al-doped ZnO films grown by atomic layer deposition for silicon nanowire photovoltaic device

We report the structural, electrical, and optical characteristics of Al-doped ZnO (ZnO:Al) films deposited on glass by atomic layer deposition (ALD) with various Al2O3 film contents for use as transparent electrodes. Unlike films fabricated by a sputtering method, the diffraction peak position of the films deposited by ALD progressively moved to a higher angle with increasing Al2O3 film content. This indicates that Zn sites were effectively replaced by Al, due to layer-by-layer growth mechanism of ALD process which is based on alternate self-limiting surface chemical reactions. By adjusting the Al2O3 film content, a ZnO:Al film with low electrical resistivity (9.84 x 10(-4) Omega cm) was obtained at an Al2O3 film content of 3.17%, where the Al concentration, carrier mobility, optical transmittance, and bandgap energy were 2.8 wt%, 11.20 cm2 V(-1) s(-1), 94.23%, and 3.6 eV, respectively. Moreover, the estimated figure of merit value of our best sample was 8.2 m7Omega(-1). These results suggest that ZnO:Al films deposited by ALD could be useful for electronic devices in which especially require 3-dimensional conformal deposition of the transparent electrode and surface passivation.     

On-the-fly dopant redistribution in a silicon nanowire p–n junction

Dopant redistribution in a silicon nanowire (SiNW) p-n junction is found to occur owing to self-heating effects.A SiNW is doped to form back-to-back diodes and is thermally isolated by an oxide layer on its bottom side and by air on the other sides.When a high level of current flows,the inner body temperature is found to increase enough to cause dopant diffusion and even to reach the silicon melting point due to Joule heating.This experimentally observed electrothermal behavior is also validated through numerical simulation.The conductivity change is dependent on the total power density and the change becomes permanent once the device suffers self-heating beyond a threshold point.Finall~ the dopant redistribution is directly visualized using scanning capacitance microscopy for the first time.     

A Multi-channel Scheduling Scheme for Collision-Free High-Rate WPANs

Ultra wide-band (UWB) technologies are being feverishly developed in the technical community. UWB devices are expected to operate at rates of up to 0.5 Gb/s and communicate with other devices at a range of up to 10 m. Thus, UWB technologies are being developed as core technology for high-speed wireless personal area networks. The salient features of UWB networks—high-rate communications, low interference with other radio systems, and low power consumption—bring many benefits to users. Thus, they enable consumers to experience new applications such as wireless universal serial bus for connecting personal computers to their peripherals and the consumer–electronics in people’s living rooms. However, if multiple WiMedia logical link protocol Service Sets (WSSs) coexist in an adjacent area, various conflicts among independent WSSs can occur frequently. In order to solve this problem, we propose a multi-channel scheduling scheme (MCS) for the coexistence of adjacent WSSs. The proposed MCS scheme can scan new idle channel and detect its time offset where a WSS device can transmit a new beacon frame and data frames without conflicts. We also evaluate the performance of the proposed MCS scheme through various simulations in terms of several metrics. Simulation results demonstrate that the MCS scheme can minimize the possibility of data frame collisions by efficiently managing the multiple available channels in a hybrid manner combining proactive and reactive methods.     

Self-Rectifying Effect in Resistive Switching Memory Using Amorphous InGaZnO

Resistance random access memory (ReRAM) has received attention as next-generation memory because of its excellent operating properties and high density integration capability as a crossbar array. However, the application of the existing ReRAM as a crossbar array may lead to crosstalk between adjacent cells due to its symmetric I–V characteristics. In this study, the self-rectifying effect of contact between amorphous In-Ga-Zn-O (a-IGZO) and TaO _x was examined in a Pt/a-IGZO/TaO _x /Al₂O₃/W structure. The experimental results show not only self-rectifying behavior but also forming-free characteristics. During the deposition of a-IGZO on the TaO _x , an oxygen-rich TaO _x interfacial layer was formed. The rectifying effect was observed regardless of the interface formation and is believed to be associated with Schottky contact formation between a-IGZO and TaO _x . The current level remained unchanged despite repeated DC sweep cycles. The low resistance state/high resistance state ratio was about 10¹ at a read voltage of ?0.5 V, and the rectifying ratio was about 10³ at ±2 V.     

Formicary-like carbon nanotube/copper hybrid nanostructures for carbon fiber-reinforced composites by electrophoretic deposition

An electrophoretic deposition process has been applied to produce unique carbon nanotube (CNT)/copper nanostructures on the carbon fiber surfaces. During the deposition process, ionized copper and positively charged CNTs are accelerated towards the carbon fiber under applied electric fields. An interconnected formicary-like network of nanotubes and nanoparticles is formed where copper nucleation and growth occurs predominantly at nanotube crossing and edge-contact locations. When embedded in a structural composite the CNT/copper structures create a highly conductive and strongly bonded network shown by significant enhancements in both electrical conductivity and interlaminar shear strength as compared to composites without the CNT/copper nanostructures.     

Characteristics of polysilicon thin-film transistor with thin-gatedielectric grown by electron cyclotron resonance nitrous oxide plasma

Polysilicon thin-film transistors (poly-Si TFT's) with thin-gate oxide grown by electron cyclotron resonance (ECR) nitrous oxide (N₂ O)-plasma oxidation is presented. ECR N₂O-plasma oxidation successfully incorporates nitrogen atoms at the SiO₂/poly-Si interface, consequently forms a nitrogen-rich layer with Si≡N bonds at a binding energy of 397.8 eV. ECR N₂ O-plasma oxide grown on poly-Si films shows higher breakdown fields than thermal oxide. The fabricated poly-Si TFT's with N₂ O-plasma oxide show better performance than those with ECR O₂ -plasma oxide, which results not only from the smooth interface but also oxygen- and nitrogen-plasma passivation     

Highly reliable polysilicon oxide grown by electron cyclotronresonance nitrous oxide plasma

Highly reliable inter-polysilicon oxide (polyoxide) for nonvolatile memory applications has been achieved using electron cyclotron resonance (ECR) N₂O-plasma. It is demonstrated that the N₂O-plasma polyoxide grown on doped poly-Si has a low leakage current and high breakdown field due to a smooth polyoxide/poly-Si interface and nitrogen incorporation during oxidation. Moreover, the polyoxide has much less electron trapping and over one order larger charge-to-breakdown (Q_bd) up to 10 C/cm² than thermal polyoxide. The N₂O-plasma polyoxide can be a good choice for the interpoly dielectric of nonvolatile memories     

Mechanisms and Kinetics of Static Spheroidization of Hot-Worked Ti-6Al-2Sn-4Zr-2Mo-0.1Si with a Lamellar Microstructure

The effect of imposed strain ε, annealing temperature T _A, and annealing time τ on the static spheroidization behavior of Ti-6Al-2Sn-4Zr-2Mo-0.1Si having an initial lamellar microstructure was investigated. For this purpose, the samples were compressed isothermally at 1173 K (900 °C) to ε = 1.0 and subsequently annealed at 1228 K (955 °C) ≤ T _A ≤ 1253 K (980 °C) for 10 minutes ≤ τ ≤ 24 hours. For each test condition, metallography was performed to evaluate the change in aspect ratio (AR) and thus quantify the structural evolution from a lamellar to an equiaxed morphology. The average AR decreased rapidly during short annealing times as a result of sub-boundary–induced boundary splitting, but it decreased at a considerably slower rate during subsequent long-time, diffusion-controlled termination migration. The overall time to complete the static globularization was thus governed largely by termination migration. To model the observations, a kinetic equation describing the static spheroidization of two-phase titanium alloys was developed. A comparison of experimental results and predictions showed that the model can provide a reasonable prediction of the time required to complete diffusion-controlled migration of the edges of thin lamellar fragments that are circular or elliptical in shape.     

Efficient work measurement system of manufacturing cells using speech recognition and digital image processing technology

Work measurement methods previously proposed require considerable time and effort by time study analysts because they have to measure the required time through direct observations. In this study, however, we propose a method which efficiently measures the standard times without involving human analysts by using speech recognition and digital image processing techniques. First, we implement a prototype system which can acquire the status of manufacturing cells through a speech recognition system. Second, using image processing, we suggest a method which consists of two main steps: motion representation and cycle segmentation. In the motion representation step, we first detect the motion of any object distinct from its background by differencing two consecutive images separated by a constant time interval. The images thus obtained then pass through an edge detector filter. Finally, the mean values of coordinates of significant pixels of the edge image are obtained. Through these processes, the motions of the observed worker are represented by two time series of data of worker location in horizontal and vertical axes. In the cycle segmentation step, we extract the frames which have maximum or minimum coordinates in one cycle, store them in a stack, and calculate each cycle time using these frames. In this step we also consider methods for detecting work delays due to unexpected events such as an operator’s movement out of the work area, or interruptions. To conclude, the experimental results show that the proposed method is very cost-effective and useful for measuring time standards for various work environments.