Growth of thin plates of Bi12SiO20 single crystals

Thin plates of Bi₁₂SiO₂₀ (BSO) single crystal were grown by the EFG method. In this experiment, three different kinds of dies with planar, angular-concave, and concave top geometries were used. The experiment proved that it is possible to achieve stable growth of cm-sized thin plates of BSO single crystals using a die with a concave die-top geometry. The effect of die-top geometry on growth stability is qualitatively explained according to the meniscuc model developed by V. A. Tatarchenko.     

The new chirp-Wigner higher order spectra for transient signals with any known nonlinear frequency variation

The new chirp-Wigner higher order spectra (CWHOS) are proposed for transient signals with any known nonlinear polynomial variation of instantaneous frequency. The proposed technique is effective for nonlinearity detection for transient signals with nonlinear polynomial time variation of the instantaneous frequency.     

Racemization of l-lactic acid in pH-swing open fermentation of kitchen refuse by selective proliferation of Lactobacillus plantarum

We have shown that stable lactic acid fermentation of model kitchen refuse occurs with intermittent pH adjustment under nonsterilized conditions. Nonetheless, the optical activity of the accumulated lactic acid was low, which is disadvantageous for the production of high-quality poly-l-lactic acid. Here, we attempt to increase optical purity by introducing l-lactic acid-producing strains under nonsterilized conditions and demonstrate that the inoculation of Lactobacillus rhamnosus or Lactococcus lactis, both of which are l-lactic acid producers, is partially effective in the early fermentation stage, but does not improve the final optical purity of the accumulated lactic acid. We confirmed by fluorescence in situ hybridization using group-specific and species-specific 16S rDNA probes that this is due to the selective proliferation of naturally existing L. plantarum. L. plantarum KY-1, which is isolated from model kitchen refuse, showing lactic acid racemase activity, as well as d-lactate dehydrogenase activity, in its membrane fraction. We conclude that racemase activity associated with L. plantarum is the main cause of decreased optical purity in the accumulated lactic acid.     

Optimal design method with thermomagnetic field coupling analysis for miniaturization of permanent magnet synchronous motor

A straightforward solution for minimizing the cost of major materials used in motors, such as permanent magnets and silicon steel sheets, is to reduce the motor size as far as possible. However, there is a trade‐off between the motor size and temperature rise in the motor that should be taken into account while reducing the motor size. For achieving this, we have been developing an optimal design method based on a combination of a thermomagnetic field coupling analysis and a direct search algorithm. This paper reports the details of this design method. A multipole permanent magnet synchronous motor of an outer rotor is the test motor. The results of the torque‐density‐maximization problem involving constraints on the terminal voltage, coil‐temperature rise, and demagnetization of the permanent magnet are shown. The usefulness of our method is also demonstrated. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 183(2): 29–38, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22346     

An example of fault site localization on a 0.18 μm CMOS device with combination of front and backside techniques

This paper describes a failure analysis on a 0.18 μm CMOS device. To find out fault mechanism, combination of several fault localization techniques that are both front and backside were utilized. Fault mechanism is discussed, including the relation between the results of these techniques and physical layout with circuit information. In this case, the failure device had these features: multi-metallization process with dummy fill metals, low supply voltage, and non-function with high I_DD leakage. These features made verifying the fault mechanism very difficult. We provide an approach of voltage contrast method with FIB milling techniques. This approach enabled to probe inner nodes in the multi-metallization device and to verify the fault mechanism. We also discuss the verification with circuit simulation and the root cause in detail.     

Thin film poly-Si formation for solar cells by Flux method and Cat-CVD method

Two methods were examined for the formation of poly-Si films. One is flux method and the other is Cat-CVD method. Flux method was used for forming poly-Si seed films on glass substrates covered with rear electrode. Poly-Si films of a few μm grain size and of mainly (1 1 1) crystalline orientation were obtained at less than 600°C. To make the seed films function as BSF layer for solar cell, boron doping was applied and carrier concentration of 2×10¹⁹/cm³ was obtained which is suitable for highly efficient solar cells. Cat (catalytic)-CVD method was examined for forming poly-Si photo-active layers on the seed films. The films showed deposition gas pressure-dependent crystalline orientations and there was no amorphous incubation layer in (1 1 1) oriented films by Cat-CVD method when deposited on (1 1 1) oriented seed films prepared by Flux method. The electrical properties of the film are insufficient at present, may be due to high defect density and the film structure which allows impurity contaminations of oxygen and carbon after film deposition. Although the film quality needs to be improved, poly-Si films whose crystal fraction is more than 85% were obtained at deposition rate of up to around 40 Å/s. This result indicates high potential of Cat-CVD method for high throughput photo-active formation process necessary for low production cost thin film silicon solar cells.     

Generation of a large area thermal induction plasma by applying a 50 kHz magnetic field

Inductively coupled radio frequency plasmas are gradually becoming an important source of high-temperature and high-reactivity plasmas for processing new functional materials or for removal of unwanted substances. Spatially wider plasmas are required for higher rate, more uniform processing in the future. Although low MHz frequencies have been usually used for induction plasmas, an attempt to expand the high temperature plasma fields was made by superimposing lower frequency 50-kHz magnetic fields on the DC plasma discharge to obtain a small source plasma. Because the penetration depth in such a low frequency field is as long as a few hundred mm, a larger radius plasma can be expected. As a first step, we have investigated the operating conditions under which a stable low frequency plasma is generated, based on theoretical calculations that include the time dependent rate equations for heat transfer and fluid flow in conjunction with the Maxwell electro-magnetic equations. Results showed that the minimum necessary power for expanding a small DC plasma to a wider plasma 100 mm in diameter by applying a 50-kHz magnetic field, is about 130 kW at 0. 1-MPa pressure. This power level is recognized to be within the available range in existing high-power oscillator systems. Measurements were carried out of the time variation of the spectral emission from the plasma immediately after superimposing the 50-kHz magnetic field upon a small area plasma generated with DC power of 1.5 kW at a pressure of 0.01 MPa in Ar gas. At a low power level of about 60 kW, the small plasma starts to expand in the radial direction, and finally, converges to a new wider plasma with 100 mm diameter. FFT analysis of the oscillograph showed that during the transient state, a period fluctuation in light emission occurs at a few tens of Hz reflecting the thermal time constant of a few tens of ms, besides the power frequency of 41.7 kHz. The plasma temperature was estimated by using the spectroscopic line intensities from neutral Ar atoms, as between 8,000 and 11,000 K. A uniformly distributed temperature field was successfully produced by applying the 50-kHz magnetic field, as expected. © 1998 Scripta Technica, Electr Eng Jpn, 123 (4): 48–57, 1998     

PIXE analysis of trace elements in northern fur seal teeth

Trace elements in teeth of northern fur seal Collorhinus ursinus were analyzed by PIXE and micro-PIXE (μ-PIXE). Trace elements such as Mn, Fe, Zn, Cu, As, Br, Sr, and Pb were detected in the teeth, which were composed of hydroxyapatite crystals. Among these elements, the concentrations of Fe and Zn were relatively higher in winter and lower in summer and also Zn varied along with growth of individuals. These elemental fluctuation seems to correspond to the life history of the northern fur seal. It suggests that the PIXE analysis will make a powerful tool to reconstruct the life history.     

Consumption of lily bulb modulates fecal ratios of firmicutes and bacteroidetes phyla in rats fed a high-fat diet

Food Science and Biotechnology - Different ascorbic acid (AA) concentrations of 0.16, 0.20, and 0.24% (w/v) were added to pear juice from the new cultivar Pyrus pyrifolia Nakai cv....