Surface temperature of Pd/C catalyst under microwave irradiation in dechlorination process of PCBs

In recent years, a new effective method of processing for polychlorinated biphenyls (PCBs) has been developed: It enables PCBs to become harmless by dechlorinating them using a 2.45 GHz microwave (MW). Compared with conventional thermal heating, MW processing hardly produces any harmful byproduct materials, and has high reaction velocity. To investigate such promotion of chemical reaction by MW irradiation, the surface temperature of the catalyst is measured by an infrared camera just after the irradiation by MW. It is recognized that there are some heated regions on the catalyst and the temperature is not uniform. It is natural to say that chemical reaction is promoted well on such a heated region. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Dielectrics loss of PCBs leading to microwave heating

A new effective processing for polychlorinated biphenyls (PCBs) has been recently developed. PCBs become harmless by dechlorination using 2.45 GHz-microwave (MW). To investigate such chemical reaction by MW irradiation, the dielectric loss of pure PCBs solutions and an isomer mixture in MW band is measured. Some PCBs and isopropyl alchol, added as a source of hydrogen supply have high dielectric loss in MW band. This suggests that MW heats PCBs and isopropyl alchol, and then the temperature of the solvent consisting mainly of insulating oil rises by the thermal conduction. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Size dependence of THz region dielectric properties for barium titanate fine particles

Barium titanate (BaTiO₃) crystallites with various particle sizes from 22 to 500 nm were prepared by the two-step thermal decomposition method of barium titanyl oxalate. Various characterizations revealed that these particles were impurity-free, defect-free, dense BaTiO₃ particles. The powder dielectric measurement clarified that the dielectric constant of BaTiO₃ particles with a size of around 58 nm exhibited a maximum of over 15,000. To explain this size dependence, the THz region dielectric properties of BaTiO₃ fine particles, especially Slater mode frequency, were measured using the far infrared (FIR) reflection method. As the result, the lowest Slater mode frequency was obtained at 58 nm. This tendency was completely consistent with particle size dependence of the dielectric constant.     

Improvement of the Nelder-Mead method using Direct Inversion in Iterative Subspace

Optimization and Engineering - The Nelder-Mead (NM) method is a popular derivative-free optimization algorithm owing to its fast convergence and robustness. However, it is known that the method...     

Characterization of Acetylxylan Esterase from White-Rot Fungus Irpex lacteus

The carbohydrate esterase family 1 (CE1) in CAZy contains acetylxylan esterases (AXEs) and feruloyl esterases (FAEs). Here we cloned a gene coding for an AXE belonging to CE1 from Irpex lacteus (IlAXE1). IlAXE1 was heterologously expressed in Pichia pastoris, and the recombinant enzyme was purified and characterized. IlAXE1 hydrolyzed p-nitrophenyl acetate, α-naphthyl acetate and 4-methylumbelliferyl acetate, however, it did not show any activity on ethyl ferulate and methyl p-coumarate. We also examined the activity on partially acetylated and feruloylated xylan extracted from corncob by hydrothermal reaction. Similarly, ferulic and p-coumaric acids were not liberated, and acetic acid was only detected in the reaction mixture. The results indicated that IlAXE1 is an acetylxylan esterase actually reacted to acetyl xylan. However, since IlAXE1 was unable to completely release acetic acid esterifying xylopyranosyl residues, it is assumed that acetyl groups exhibiting resistance to deacetylation by IlAXE1 are present in corn cob xylan.     

Reduction of frequency noise and frequency shift by phase shifting elements in frequency modulation atomic force microscopy

We recently reported the analysis of the frequency noise in the frequency modulation atomic force microscopy (FM-AFM) both in high-Q and low-Q environments [Rev. Sci. Instrum. 80, 043708 (2009)]. We showed in the paper that the oscillator noise, the frequency fluctuation of the oscillator, becomes prominent in the modulation frequency lower than f(0)∕2Q, where f(0) and Q are the resonance frequency and Q-factor. The magnitude of the oscillator noise is determined by the slope of the phase versus frequency curve of the cantilever at f(0). However, in actual FM-AFM in liquids, the phase versus frequency curve may not be always ideal because of the existence of various phase shifting elements (PSEs). For example, the spurious resonance peaks caused by the acoustic excitation and a band-pass filter in the self-oscillation loop increase the slope of the phase versus frequency curve. Due to those PSEs, the effective Q-factor is often increased from the intrinsic Q-factor of the cantilever. In this article, the frequency noise in the FM-AFM system with the PSEs in the self-oscillation loop is analyzed to show that the oscillator noise is reduced by the increase of the effective Q-factor. It is also shown that the oscillation frequency deviates from the resonance frequency due to the increase of the effective Q-factor, thereby causing the reduction in the frequency shift signal with the same factor. Therefore the increase of the effective Q-factor does not affect the signal-to-noise ratio in the frequency shift measurement, but it does affect the quantitativeness of the measured force in the FM-AFM. Furthermore, the reduction of the frequency noise and frequency shift by the increase of the effective Q-factor were confirmed by the experiments.     

A differentially pumped low-energy ion beam system for an ultrahigh-vacuum atom-probe field-ion microscope

An ultrahigh-vacuum (UHV) differentially pumped low-energy (50-3000 eV) ion beam system for the in situ irradiation of specimens in a UHV atom-probe field-ion microscope (FIM) was designed and constructed. The ion beam system consisted of a Finkelstein-type ion source, an Einzel lens, and a magnetic mass analyzer. The ion source was connected to the analyzer chamber by small apertures which resulted in differential pumping between the ion source and the analyzer chamber; during a typical in situ irradiation of a specimen in the atom-probe FIM the total pressure was maintained at approximately 10(-7) Torr. In the case of helium ion irradiation the optimum ion-current density was approximately 0.5 microA cm(-2) for 300-eV He+ ions at the atom-probe FIM specimen. After the completion of a helium ion irradiation the pumpdown time from 5 x 10(-7) to approximately 3 x 10(-10) Torr in the atom-probe FIM chamber was 0.5 h.     

Solid-state pH sensor prototype for real-time monitoring of the rumen pH value of Japanese cows

Microsystem Technologies - During the growth of Japanese cows, the ruminal pH value is an important physiological parameter, which remarkably affects their nutritional status. To monitor the health...     

Enrichment of arachidonic acid: Selective hydrolysis of a single-cell oil fromMortierella withCandida cylindracea lipase

Three lipases, isolated previously in our laboratory, and a known lipase fromCandida cylindracea were screened for the enrichment of arachidonic acid (AA). The enzyme fromC. cylindracea was the most effective for the production of oil with high concentration of AA. When a single-cell oil fromMortierella alpina, containing 25% AA, was hydrolyzed with this lipase for 16 h at 35°C, the resulting glycerides contained 50% AA at 52% hydrolysis. After this, no further hydrolysis occurred, even with additional lipase. However, when the glycerides were extracted from the hydrolyzate and were hydrolyzed again with new lipase, the resulting oil contained 60% AA, with a recovery of 75% of its initial AA content. Triglycerides were the main components of the resulting oil. The release of each fatty acid from the oil depended on the hydrolysis rate of its ester. The fatty acid, whose ester is the poorest substrate for the enzyme, is concentrated in the glycerides.