Single-Cycle Terahertz Pulse Generation from OH1 Crystal via Cherenkov Phase Matching

OH1 crystal is an organic nonlinear optical crystal with a large nonlinear optical constant. However, it has dispersion of refractive indices in the terahertz (THz) frequency. This limits the frequencies that satisfy the phase matching conditions for THz wave generation. In this study, we addressed the phase matching conditions for THz wave generation by combining an OH1 crystal with prism-coupled Cherenkov phase matching. We observed the generation of single-cycle THz pulses with a spectrum covering a frequency range of 3 THz. These results prove that combining prism-coupled Cherenkov phase matching with nonlinear optical crystals yields a THz wave generation method that is insusceptible to crystal dispersion.     

Ferulic Acid Production in the Brewing of Rice Wine (Sake)

The traditional Japanese alcoholic beverage sake is produced by fermentation of rice by Saccharomyces cerevisiae and Aspergillus oryzae. A. oryzae releases ferulic acid, an antioxidant, from steamed rice during the fermentation process. The concentration of ferulic acid increased with time during fermentation and the production rate peaked 9–12 days post inoculation. Analysis of the fermentation cultures of Aspergillus oryzae, by high‐performance liquid chromatography (HPLC), revealed that p‐coumaric acid induced an 18.9‐fold increase in the level of ferulic acid. Furthermore, SDS‐PAGE analysis revealed an increase or decrease in the level of specific proteins after the addition of p‐coumaric acid to fermentation cultures of Aspergillus oryzae. Ferulate esterase (FAE) activity was observed in the fermented sake ten days following the start of the fermentation process. These results suggest that the level of ferulic acid is regulated by the enzymes synthesized by A. oryzae during the sake brewing process.     

Production of odd chain polyunsaturated fatty acids byMortierella fungi

A soil isolate,Mortierella alpina 1S-4, was found to show high production of odd chain polyunsaturated fatty acids (PUFAs) among various arachidonic acid-producingMortierella strains tested. The fungus mainly accumulated 5,8,11,M-cis-nonadecatetraenoic acid. With 5%n-hepta-decane and 1% yeast extract as growth substrates, the amount of C_19:4:4 acid accumulated reached 44.4 mg/g dry mycelia (0.68 mg/mL of culture broth). This value accounted for 11.2% of the total fatty acids in the extracted lipids from mycelia, and odd chain fatty acids comprised over 95% of the total mycelial fatty acids. The addition of sesamin, a specific inhibitor of A5 desaturation, caused an increase in C_19:3 acid and an accompanying decrease in C_19:4 acid. On the other hand, species ofMortierella that could not produce C-20 PUFAs accumulated C-17 acids, but no C-19 PUFAs, when grown with fatty substrates with an odd chain skeleton. The odd chain PUFAs were distributed in both neutral and polar lipids. The biosynthetic route to C_19:4 acid was presumed to mimic the n-6 route to arachidonic acid as follows: C_17:0 → C_17:1→ C_17:2→ C_17:3 → C_19:3 → C_19:4 acids. On leave from Suntory Ltd.     

Concept of feedback‐controlled differential evolution and its realization

This paper first proposes a novel concept of differential evolution (DE) with an automatic parameter adjustment that controls its search situation to be a promising situation by the error feedback. It is called feedback‐controlled differential evolution (FCDE), whose adjustment mechanism consists of three parts: Evaluator, Referencer, and Controller. Evaluator calculates an evaluation index which measures the search situation. Referencer generates a reference index being a target of the evaluation index which corresponds to a promising situation. Controller operates the parameters to make the evaluation index follow the reference index using its error feedback. Further, this paper realizes a method in FCDE for a typical DE called “DE/best/1/bin" by designing the three parts. The effectiveness of the proposed method is confirmed through various computational experiments from the viewpoints of controllability and performance. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Encapsulation of hemoglobin in mesoporous silica (FSM)-enhanced thermal stability and resistance to denaturants

Hemoblogin (Hb), which is a typical oligomeric protein, was introduced into the pores of mesoporous silica (FSM: folded-sheet mesoporous material) that had a diameter of 7.5 nm. Soret CD spectra of Hb-FSM-7.5 conjugates showed a peak that was identical to that of free Hb. This suggests that Hb retained its highly ordered structure in the mesoporous silica. In addition, the UV-visible absorption spectrum showed that Hb had an increased resistance to heat denaturation in the silica. Even after heat treatment at 85 degrees C, Hb-FSM-7.5 retained its ligand-binding activity. The stability of Hb-FSM-7.5 was examined further by measuring its peroxidase-like activity. Encapsulation of Hb resulted in the retention of activity in the presence of high NaCl or Gdn-HCl levels. This suggests that encapsulation prevented dissociation and denaturing. Thus, it seems that the mesopores created a favorable environment for the oligomeric protein to perform its function, even under harsh conditions.     

A fast acoustic field mapping approach based on fabry–perot sensor with high‐speed camera

A Fabry–Perot (FP) interferometer‐based ultrasound sensor provides an inherently broadband response and excellent detection sensitivity compared to piezoelectric zirconate titanate (PZT) or polyvinylidene difluoride (PVDF) transducers. It is therefore expected to be used for medical ultrasound imaging and photoacoustic imaging. However, at present, mapping acoustic fields takes much time for scanning, which hinders real‐time measurement. We propose a new approach that utilizes a high‐speed camera (HSC) to map acoustic fields without mechanical scanning and to sample signals of acoustic waves with the shutter of the HSC. Experimental results indicate that acoustic field at the focus of a pulsed 1‐MHz PZT ultrasound transducer can be detected and mapped by using the FP sensor with the HSC. By improving the uniformity of the FP sensor and the exposure time, the frame rate of HSC can be further developed, and this approach should be able to provide a fast acoustic field mapping for high‐resolution biomedical photoacoustic and other ultrasonic imaging. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

A cytoplasmic xylanase (XynX) of Aeromonas caviae ME-1 is released from the cytoplasm to the periplasm by osmotic downshock

Aeromonas caviae ME-1 is a multiple xylanase-producing gram-negative bacterium which was isolated from the gut contents of a wild silkworm, Samia cynthia pryeri. One of the xylanases produced by A. caviae ME-1, XynX (38 kDa, family 10 xylanase), hydrolyzes xylan to xylobiose and xylotetraose as final degradation products. Generally, xylanases are extracellular or cell surface enzymes. However, XynX is not exported to the extracellular fluid by A. caviae ME-1 and an Escherichia coli transformant harboring the xynX gene. In this study, we investigated the intracellular localization of XynX in A. caviae ME-1 and an E. coli transformant. XynX was found in the cytoplasm when the cells were grown under normal culture conditions. However, XynX was released from the cytoplasm to the periplasm during osmotic downshock. This release of XynX in the E. coli transformant was blocked in the presence of gadolinium chloride, which has been reported to be an inhibitor of bacterial mechanosensitive channels.     

Enhancement of heat transfer in hydrogen storage tank with hydrogen absorbing alloy (optimum fin layout)

Optimization of the fin layout in a metal hydride (MH) bed has been sought to enhance poor heat transmission in a hydrogen storage tank, and to obtain a maximum hydrogen absorption rate with a smaller volume of fins. Two different fin configurations, radial and circular fins, in a vertical cylindrical reactor vessel were tested with a La‐Ni‐based AB5 type hydrogen storage alloy. A two‐dimensional transient heat conduction analysis, coupled with predicted temperature and concentration of absorbed hydrogen in the bed for the exothermic hydride reaction, was used to evaluate enhancement of the hydrogen absorption time. The estimated temperature and concentration agreed within 6 K and 8.5%, respectively, with our experimental results. The effect of thickness and the spacing and shape of fins on the hydrogen absorption time were analytically evaluated, so that the optimum range of the each fin layout was obtained by the trade off between absorption time and reduction in the MH volume due to the volume occupied by fins. The hydrogen absorption time for the recommended layout of circular fins was reduced to approximately one‐third of that without fins. © 2008 Wiley Periodicals, Inc. Heat Trans Asian Res, 37(3): 165–183, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20195