In situ identification of microorganisms in biofilm communities

Diverse microorganisms form complex microbial communities and usually exist in biofilm communities in both natural environments and engineered systems such as a wastewater treatment process. However, the conventional approach to investigate microbial ecology has not contributed to the understanding and clarification of the structure and function of biofilm communities. Some effective methods have been developed to investigate phylogenetic affiliations, metabolic activities and genetic activities in biofilm communities at the single-cell level. These techniques have been contributing to a better understanding of the spatial organization of biofilm communities and activities in engineered systems. However, further effort is needed to set out the general rules governing community development in biofilm communities and to advance the process performance of engineered systems. This review describes advances and limitations in methodology, particularly focusing on fluorescence in situ hybridization (FISH) and related techniques and the application of these methods to nitrifying biofilms in wastewater treatment processes.     

Fundamental experiments for the development of high-performance cold plates in a feasability study on space solar power system

To realize a concept of solar power satellite with high power generation, it is a promising method to transfer the power by laser beam using active mirror type amplifiers where cooling of the laser material accepting highly condensed sunray is inevitable. To remove high heat flux density from a large area, a structure of cold plate consisted of two parallel plates is devised and the effective liquid supply directly to the bottom of flattened bubbles due to nucleate boiling is realized by the auxiliary liquid feeder. The critical heat flux is increased by more than 1.5 times from that without the additional liquid supply. The technology can be applied not only to space but widely to the development of high-performance cold plates employed on ground.     

Investigation on force transmission of direct-drive thorax unit with four ultrasonic motors for a flapping microaerial vehicle

We fabricated a trial version of a thorax unit with four ultrasonic motors (USMs) to simulate a dragonfly-scale flapping micro aerial vehicle (MAV). Each wing was directly driven by a two-degree-of-freedom (2-DOF) transmission. An in-house tiny standing-wave USM capable of bidirectional rotation, which weighs just 0.13 g, was employed on trial. The transmission of the thorax unit converts the two USM rotations into strokes and flip motions of the wing. By implementing two 70-mm-long wings, we fabricated a prototype of a 4-DOF MAV and tested its performance. In a lift-compensated situation, upward, forward, and backward movements of the MAV were obtained. The flapping angular velocity was discussed based on quasi-static wing aerodynamics and was accountable for the motor power. Although the power of the USM should be improved, the quick wing drivability, adequate power transmission on the thorax unit, and potential of a 0.2 W motor power in a unidirectional-type USM promise the viability of a direct-drive multi-DOF dragonfly-scale MAV.     

Silicon Analogues of the RXR‐Selective Retinoid Agonist SR11237 (BMS649): Chemistry and Biology

C/Si switch : Twofold sila‐substitution (C/Si exchange) in the RXR‐selective retinoids 4 a (SR11237) and 5 a leads to 4 b (disila‐SR11237) and 5 b , respectively. Chemistry and biology of the C/Si pairs are reported.

     

An application of cathodoluminescence to optimize the shallow trench isolation process

Cathodoluminescence (CL) spectroscopy was applied to optimize the shallow trench isolation (STI) process. The analysis of dislocations with CL spectroscopy could be performed during STI process steps. Then, the result of CL analysis was associated with the failure of a junction leakage current. Moreover, the analysis contributed to identifying the failure, including the root cause. As the result of CL analysis, nitride film thickness used as a mask layer of patterning was controlled at 190 nm or less. The dislocation analysis with CL spectroscopy can reduce the cycle time from 50 to 5 days.     

Fuzzy differential equations and the extension principle

We study the Cauchy problem for differential equations, considering its parameters and/or initial conditions given by fuzzy sets. These fuzzy differential equations are approached in two different ways: (a) by using a family of differential inclusions; and (b) the Zadeh extension principle for the solution of the model. We conclude that the solutions of the Cauchy problem obtained by both are the same. We also provide some illustrative examples.     

A time-dependent threshold condition to determine the onset of AIDS

This study first considers the effects of “uninfectious” HIV-1 due to fatal mutations, and then analysis reveals that AIDS develops when the number of HIV-1 strains, i.e., antigenic diversity, is above a “time-dependent” threshold. This result is interesting because it suggests the possibility that the onset of AIDS could be dynamically determined. This dynamic behavior of the threshold may make the prediction of AIDS development difficult.     

Epidemic models and a self-repairing network with a simple lattice

We have proposed a self-repairing network where nodes are capable of repairing neighboring nodes by mutually copying. A critical point where faulty nodes can be eliminated has been investigated. This paper further studies the dynamics of eradicating faulty nodes by comparing the self-repairing network with mathematical epidemic models such as SIS models. It is shown that the self-repairing network, which is a probabilistic cellular automaton, can be regarded as an epidemic model in some restricted situations. This work was presented in part at the 12th International Symposium on Artificial Life and Robotics. Oita, Japan, January 25–27, 2007     

Small-angle X-ray scattering from sodium hyaluronate in aqueous sodium chloride

Summary Four narrow-distribution samples of sodium hyaluronate with weight-average molecular weights M _w of 3.8 × 10³ to 1.1 × 10⁴ in 0.02 and 0.1 M aqueous NaCl at 25°C have been studied by small-angle X-ray scattering. Data for their z-average radii of gyration <S²>_z ^1/2 and particle scattering functions P(θ), together with previous <S²>_z data from light scattering for high molecular weights, are compared with relevant theories for the wormlike chain with or without excluded volume, using the parameters estimated previously from intrinsic viscosity ([η]) data. It is shown that for M _w lower than 1.1 × 10⁴, <S²>_z, P(θ), and [η] of the polysaccharide in the aqueous salts are all consistently explained by this model without excluded volume. Received: 8 December 1997/Accepted: 26 December 1997     

Thermal stabilization of penicillolysin, a thermolabile 19 kDa Zn2+-protease, obtained by site-directed mutagenesis

Penicillolysin is a member of the clan MX and the family of M35 proteases. The enzyme is a thermolabile Zn(2+)- protease from Penicillium citrinum with a unique substrate profile. We expressed recombinant penicillolysin in Aspergillus oryzae and generated several site-directed mutants, R33E/E60R, A167E and T81P, with the intention of exploring thermal stabilization of this protein. We based our choice of mutations on the structures of homologous thermally stable enzymes, deuterolysin (EC 3.4.24.39) from A.oryzae and a peptidyl-Lys metallopeptidase (GfMEP) from the edible mushroom Grifora frondsa. The resulting mutant proteins exhibited comparable catalytic efficiency to the wild-type enzyme and some showed a higher tolerance to temperature.