Analysis of free-carrier optical absorption used for characterization of microcrystalline silicon films

The analysis of free-carrier optical absorption was applied to investigation of electrical properties for doped microcrystalline silicon films formed at 100–180°C by the RF-plasma-enhanced chemical vapor deposition method. The analysis gave in-depth characteristics of the carrier mobility and the carrier density. The electron mobility was 8 cm²/Vs (phosphorous doped) and 6 cm²/Vs (boron doped) at the surface region and it decreased to 1 cm²/Vs at bottom film/substrate interfaces. The carrier mobility and density were much higher than those obtained by Hall effect current measurements. It shows the existence of substantial non-activated and disordered regions among crystalline grains.     

A Freestanding GaN/HfO $_{bf 2}$ Membrane Grown by Molecular Beam Epitaxy for GaN–Si Hybrid MEMS

Combination of GaN light source and Si-microelectromechanical systems (MEMSs) is a promising hybrid structure for optical MEMS. As one of GaN-Si hybrid structures, a freestanding GaN/HfO₂ membrane was fabricated on Si substrate. Unlike conventional GaN membrane on Si substrate, the fabricated membrane had a tensile stress by using the HfO₂ layer. Therefore, the GaN/HfO₂ membrane was flat enough to be useful for several MEMS. The GaN crystal was grown by molecular beam epitaxy on the HfO₂ layer deposited on Si substrate. The surface of the HfO₂ layer was nitrified before GaN crystal growth, and thus, a part of HfO₂ surface was changed to HfN, the lattice of which matched well to that of GaN. The characteristics of the GaN crystal grown on the nitrified HfO₂ layer were also investigated.     

Improvement in the electrical properties of ferroelectric SrBi2Ta2O9 capacitors by electron beam irradiation on precursor films

Abstract

Ferroelectric SrBi₂Ta₂O₉ (SBT) capacitors were fabricated by the Electron-Beam-Induced Patterning process and their electrical properties were evaluated in detail. In this process, the dose of an electron beam irradiated on precursor films had a great influence on the electrical properties of the SBT capacitors. The appropriate electron dose significantly improved the electrical properties of the SBT capacitors although the excess electron dose made severe deterioration in the properties. The SBT capacitors fabricated with the optimum electron dose, 1.5 mC/cm² for Sr:Bi:Ta = 0.8:2.2:2.0 solutions, exhibited excellent ferroelectric properties: a remanent polarization of 11.5 μC/cm², a coercive field of 40 kV/cm, a leakage current of 8×10^?8 A/cm²@ 1V and fatigue-free up to 1010 cycles. It seems that such improvements were caused by the adjustment of Bi contents in the films and the modification or the decompositon of precursors before heat treatment by electron beam irradiation.     

Fabrication of left-handed metal microcoil from spiral vessel of vascular plant

Silver microcoil is fabricated through a biotemplating process combined with electroless plating. Spiral vessels in Lotus root are employed as a biotemplate because of their left-handed coil structure. The silver microcoil exhibits a solenoidal microcoil showing self-inductance in the level of picohenry, which could be applied for electromagnetic-responsive materials in the high-frequency region such as millimeter waves or terahertz waves.     

The Formation of β‐Damascenone in Sweet Potato Shochu

The formation of β‐damascenone during shochu manufacture was investigated by quantifying β‐damascenone at each stage of manufacturing. Steamed sweet potato has a low level of free β‐damascenone (0.02–0.1 μg/g). During fermentation, β‐damascenone was produced in small quantities that were degraded by yeast. Thus, the second mash accumulates little free β‐damascenone (approximately 17 μg/L). The concentration profile in the fractionated distillate showed that β‐damascenone was produced during heating. Most β‐damascenone in shochu was formed during distillation, not during steam heating and fermentation. It is suggested that the level of β‐damascenone in shochu could be increased by reducing the pH of the second mash and prolonging the distillation period. Sweet potato cultivars differed in total free and hydrolyzed β‐damascenone content and there was a strong association between each cultivar and its shochu β‐damascenone content. The selection of the sweet potato cultivar is important for determining the quantity of β‐damascenone in a shochu brew.     

Emerging roles of bioactive peptides on brain health promotion

Cognitive dysfunction is a major debilitating age-related disorder. Natural dietary bioactive compounds with potential neuroprotective and brain health benefits, including the prevention of cognitive impairment and dementia, have received increasing attention. Because cognitive decline is thought to result from dysfunctional synaptic plasticity, the induction of neuroprotective proteins, including neurotrophic factors, protein chaperones, and antioxidant enzymes, by dietary bioactive compounds may help prevent age-related cognitive decline. Phytochemicals and bioactive peptides have been demonstrated to have a preventive effect on cognitive decline in different animal models and in human studies. This review focuses on the in vivo effects of bioactive peptides on brain function and the expression of neuroprotective factors.     

Characteristic odour compounds in shochu derived from rice koji

Shochu, a traditional Japanese distilled liquor, makes use of rice koji, which is koji mould grown on rice grain. Rice koji is an essential ingredient of Japanese liquors such as shochu, and it plays a role as a source of the enzyme to degrade starch. However, there has been no research on the effect of rice koji on the flavour of shochu. Therefore, in this study, the volatile compounds in shochu derived from rice koji were investigated. Two shochu samples were prepared to assess the contribution of rice koji to the flavour. One shochu sample was prepared from rice koji, yeast and water (rice koji‐shochu). The other shochu sample was obtained from steamed rice and various enzymes instead of rice koji (enzyme‐shochu), along with yeast and water. The volatile compounds were analysed by gas chromatography–mass spectrometry (GC‐MS) and GC‐MS/olfactometry with aroma extract dilution analysis. The results showed that enzyme‐shochu had a higher flavour dilution value of dimethyl trisulphide and hexanal, whereas rice koji‐shochu had a higher flavour dilution value of some ester compounds that imparted aromatic odours such as fruity. Some unknown peaks representing compounds that impart characteristic odours such as soda, potato, lavender, and tea‐like were specifically detected in rice koji‐shochu. The concentrations and calculated odour active values of 14 compounds were measured. These results showed that isovaleraldehyde, ethyl caprylate, ethyl caproate and ethyl 2‐methylbutyrate played an important role in imparting the specific odour of rice koji‐shochu. Copyright © 2016 The Institute of Brewing & Distilling     

Studies on the ATP3 gene of Saccharomyces cerevisiae: presence of two closely linked copies,ATP3a and ATP3b,on the right arm of chromosome II

In this paper, we present evidence that there are two closely linked copies of the ATP3 gene coding for the gamma subunit of the F(1)F(0)-ATPase complex (EC3.6.1.34) in four laboratory strains of Saccharomyces cerevisiae, even though the yeast genome project has reported that ATP3 is a single-copy gene on chromosome II. We previously reported that the gene dosage (three copies) of ATP1 and ATP2 is coincident with the subunit number of F(1)-alpha and F(1)-beta, but that the gene dosage of ATP3 was not consistent with the subunit stoichiometry of F(1)F(0)-ATPase. By applying long PCR and gene walking analyses, we estimated that the two copies of ATP3 were approximately 20 kb apart, and we designated that which is proximal to the centromere ATP3a, while we named that which is distal ATP3b. The nucleotide sequences of the two copies of ATP3 were identical to the reported sequence in the W303-1A, W303-1B and LL20 strains, while only the DC5 strain had a single base substitution in its ATP3a. With the exception of this substitution, the other nucleotide sequences were identical to the upstream 860 bp and the downstream 150 bp. The differences between ATP3 with the single base substitution (Ser(308) to Phe) and ATP3 without the substitution on the complementation of the ATP3 disruptant and on the maintenance of the mitochondrial DNA were observed, suggesting that Atp3ap and Atp3bp in the DC5 strain might have different functions. However, it should not always be necessary for yeast cells to carry different types of ATP3 because the other three strains carry the same type of ATP3. It was also demonstrated that the disruption of the ATP3 genes basically leads to a loss of wild-type mtDNA, but the stability of the mtDNA is not dependent on the ATP3 alone.     

Analysis of Volatile Compounds in Shochu Koji,Sake Koji,and Steamed Rice by Gas Chromatography‐Mass Spectrometry

The volatile compounds in three types of koji (yellow, white, and black) and steamed rice were investigated using gas chromatography‐mass spectrometry. The objective of this study was to characterize each koji type based on its profile of volatile compounds. From the steamed rice and rice koji samples examined, a total of 29 volatile compounds were identified. Butanal, hexanal, dimethyl trisulfide and cyclohexyl isothiocyanate were detected only in steamed rice. The volatile profile of yellow koji (sake koji) was distinct from those of white and black kojis (shochu koji). On the basis of relative peak areas, alcohols and aldehydes were identified as being more abundant in yellow koji. White and black kojis had similar volatile profiles, and had a greater abundance of furans than yellow koji. We assume that the different suites of volatile compounds identified in shochu and sake kojis impart the respective characteristic flavours to shochu and sake.