The initial step of the thermal unfolding of 3-isopropylmalate dehydrogenase detected by the temperature-jump Laue method

A temperature-jump (T-jump) time-resolved X-ray crystallographictechnique using the Laue method was developed to detect small,localized structural changes of proteins in crystals exposedto a temperature increase induced by laser irradiation. In achimeric protein between thermophilic and mesophilic 3-isopropylmalatedehydrogenases (2T2M6T), the initial structural change uponT-jump to a denaturing temperature (~90°C) was found tobe localized at a region which includes a ß-turn and aloop located between the two domains of the enzyme. A mutant,2T2M6T-E110P/S111G/S113E, having amino acid replacements inthis ß-turn region with the corresponding residues ofthe thermophilic enzyme, showed greater stability than the originalchimera (increase of T_m by ~10°C) and no T-jump-inducedstructural change in this region was detected by our method.These results indicate that thermal unfolding of the originalchimeric enzyme, 2T2M6T, is triggered in this ß-turn region.     

Indoor and outdoor concentrations of Japanese cedar pollens and total suspended particulates: A case study at a kindergarten in Japan

Japanese cedar pollinosis (JCP) caused by allergenic cedar and cypress pollens is one of major economic and health issues in Japan. The present study reported here aimed to provide basic data to understand the status of early life exposures to airborne cedar and cypress pollens in school settings. In particular, the study investigated relationships between indoor and outdoor concentrations of airborne cedar and cypress pollens and total suspended particulates (TSP) in a kindergarten in Japan. Overall, outdoor concentrations of the airborne pollens and TSP were higher than the indoor concentrations, i.e., indoor to outdoor (I/O) ratios of 0.043–0.055 and 0.545 for the airborne pollens and TSP, respectively. The smaller I/O ratios for the pollens were expected because the larger pollen grains (20–30 μm in diameter) were less likely penetrated to indoor environment than for smaller airborne particulates. The present study also found increased TSP concentrations during the pollen season was likely attributed to increased airborne pollen concentrations. By understanding the status of indoor and outdoor concentrations of airborne cedar and cypress pollens in school settings, early life exposures to these allergenic pollens should be effectively minimized to prevent subsequent progression to JCP symptoms.     

Mechanical and physical characteristics of cellulose‐fiber‐filled polyacetal composites

We investigated the mechanical and physical characteristics of composites composed of polyacetal [alternatively called polyoxymethylene (POM)] and cellulose fiber (CelF) derived from wood pulp [10–52 wt % (9.3–50.1 vol %)] without any fiber surface treatment. The modulus, deflection temperature under load, and thermal conduction coefficient of the POM/CelF composites were effectively enhanced with increasing CelF content, and the composites had an advantage of specific modulus compared to glass fiber (GF)‐filled POM. The flexural modulus of POM/CelF 40 wt % (38.2 vol %) was measured to be about 6 GPa, which was comparable to that of POM/GF 20 wt % (12.1 vol %). In the composites, the CelFs were distributed randomly as monofilaments, and the debonding of the interface between the fibers and POM matrices in the fracture faces was confirmed as less by scanning electron microscopy observation. The POM/CelF composites possessed lower specific wear rates than the POM/GF composites, and they had damping behaviors near that of neat POM. No clear dependence of the melt flow index of the base POM on these characteristics was observed, except on Charpy impact strength. The composites studied here were unique in their performance and ability to be designed in accordance with specific demands, and they could be potential replacements for mineral‐filled and GF‐filled POM composites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Control of Snow Falling Flow around NACA0015 Blade using a Plasma Electrode with Weather Resistant Design

The plasma actuation (PA) effect on the snow falling flow was investigated using a plasma electrode with weather resistant design and the natural snow wind facility of the Hokkaido University of Science. NACA0015 test blade with chord length c of 300 mm was used. Wind tunnel tests were carried out under the angle of the attack of the blade was fixed at 15 degrees, and the main flow velocity is U=5 m/s. PIV (Particle image velocimetry) measurements were conducted on various PA conditions using natural dry snowflakes as a tracer. When the actuator was driven under the condition of the fundamental frequency of F=50 kHz, and the pulsed modulated frequency f of fc/U=1 and Duty ratio (Ratio of plasma ON time to pulse duration time) =1%, movement of snowflakes was controlled the most effectively tested. It was clarified that the fundamental frequency of PA also affects the control of snow flow. Under snowfall conditions, the weather resistant designed plasma electrode has suffered no damage and operated successfully.     

Purification, characterization, and steady-state kinetics of a meta-cleavage compound hydrolase from Pseudomonas fluorescens IPO1

2-Hydroxy-6-oxo-7-methylocta-2,4-dienoate (6-isopropyl-HODA) hydrolase (CumD), an enzyme of the cumene biodegradation pathway encoded by the cumD gene of Pseudomonas fluorescens IP01, was purified to homogeneity from an overexpressing Escherichia coli strain. SDS-polyacrylamide gel electrophoresis and gel filtration demonstrated that it is a dimeric enzyme with a subunit molecular mass of 32 kDa. The pH optima for activity and stability were 8.0 and 7.0-9.0, respectively. The enzyme exhibited a biphasic Arrhenius plot of catalysis with two characteristic energies of activation with a break point at 20 degrees C. The enzyme has a K(m) of 7.3 microM and a k(cat) of 21 s(-1) for 6-isopropyl-HODA (150 mM phosphate, pH 7.5, 25 degrees C), and its substrate specificity covers larger C6 substituents compared with another monoalkylbenzene hydrolase, TodR Unlike TodF, CumD could slightly hydrolyze 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoate (6-phenyl-HODA). A mutant enzyme as to a putative active site residue, S103A, had 10(5)-fold lower activity than that of the wild-type enzyme.     

Hydrogen atom absorption in hydrogen-covered Pd(110) (1 × 2) missing-row surface

The absorption of H atom in H-covered Pd(110) (1 × 2) missing-row surface is investigated using density functional theory based calculations. For 1.5 monolayer H coverage, interaction among the adsorbed H atoms is found to be negligible and was verified by analyzing the electronic structure of the system and by comparing the calculated binding energies with low H coverage case. Neither the monoatomic absorption of H nor the assistance from the initially adsorbed H atom explains the experimentally observed presence of subsurface H in Pd(110) at high H coverage. Instead, H absorption is realized through the assistance of incoming H atoms from vacuum. The absorption of H in the H-covered surface is non-activated while the dissociation of H₂ is the rate-limiting process. Dissociation on ridge site is energetically more preferred than on trough site and the difference in the activation barrier is elucidated by investigating the electronic structures of the system.     

Return Link Systems for Wireless Mobile Camera Using 42 GHz-Band with Frequency and Space Diversity Techniques

In this paper, return link systems for wireless mobile camera using 42 GHz-band in multipath fading environments are proposed. The return link systems for wireless mobile camera require wireless transmission with high reliability as same as the conventional wired camera systems. The proposed return link systems achieve transmission with high reliability by taking into consideration frequency and space diversity techniques. The proposed systems can be classified as 3 three types of return link systems according to diversity techniques： FD （frequency diversity） systems, SD （space diversity） systems and FD＋SD system （frequency and space diversity）. Computer simulations are carried out in order to confirm the effectiveness of the proposed return link systems. It is confirmed that the proposed three types of return link systems have an advantage about BER performances and effectively exploit frequency and space resources.     

Enhancement of C2C12 differentiation by perfluorocarbon-mediated oxygen delivery

We have studied the effect of enhanced oxygen delivery by perfluorocarbons on the differentiation of C2C12 cells. The extent of differentiation was assessed by means of phase contrast/fluorescence microscopy, active tension measurement and the glucose consumption/lactate production rates. We found that enhanced oxygen delivery is suitable for full differentiation of C2C12 cells.     

Quantitative coherent anti-Stokes Raman scattering microspectroscopy using a nanosecond supercontinuum light source

We describe and characterize a multiplex CARS microspectroscopic system that uses a nanosecond supercontinuum generated from a photonic crystal fiber and a sub-nanosecond pulse laser. This system has a high spectral resolution (<0.1 cm^?1) and an ultrabroadband spectral coverage (>2500 cm^?1). The estimated spatial resolutions are 0.45 μm (lateral) and 4.5 μm (axial), respectively. This system enables us to obtain CARS spectra and corresponding images in the fingerprint region as well in the CH stretch region. Using this system, we have successfully obtained label-free and multi-mode vibrational images of a yeast cell.