We design and demonstrate a microsystem powered by Vorticella. This research has been conducted in four steps: 1) actuation properties of a stalk and cilium have been characterized; 2) methods to integrate Vorticella with a microsystem have been developed; 3) a control system for Vorticella actuator has been developed; 4) a micromixer powered by cilia and a microvalve driven by a stalk are proposed, and their feasibility is confirmed. We showed fundamental principles of the devices. The proposed device will open a door to a new field of microsystems and be extended to a controllable biomicrosystem. Cell-based autonomous microsystem will be possible in the future by integrating cells with MEMS.
Heterotopic transplantation of a bioengineered liver tissue represents an attractive alternative to orthotopic liver transplantation. Important issues in heterotopic liver tissue engineering field fall into three major factors: (1) vascularization in the bioengineered tissue, (2) selection of an appropriate site for the growth and reconstruction of the liver tissue, and (3) availability of sufficient mass of hepatocytes. Herein, we showed solutions to these issues. In addition, we described a transplantation methodology of bioengineered liver tissues onto the mesentery as a typical example of the heterotopic transplantation.
Efficient systems for catalytic asymmetric syntheses in aqueous media have been developed by using amphiphilic-resin-supported hydrophobic peptides having terminal prolyl groups. The supported peptide catalysts can be easily synthesized through the conventional solid-phase method, and have some merits such as reusability, applicability to sequential reactions, and facility for optimizing peptide sequences. The catalytic systems in aqueous media with the supported peptides are expected to provide the efficient procedures for the production of chiral fine chemicals.
Incorporations of unnatural amino acids in proteins are a useful technique in medical and industrial fields. For practical usages, misacylation caused by engineered aminoacyl-tRNA synthetases can be one of the issues lowering the purity of the generated proteins. Since acceptor stems of tRNAs are known to possess identity elements specific for each amino acid, the misacylation is probably caused by non-specificity of the acceptor stems in tRNAs. In this paper, we modified an acceptor stem of tRNATyr, and tested aminoacylation of over 100 modified tRNAs. Finally, we found the acceptor stem sequence for the tRNA with less misacylation for both tyrosine and tyrosine derivative unnatural amino acids.
In this review paper, we introduce recent progress in theoretical immunology, especially focusing on studies toward quantitative experiments for cell population growth and their mathematical models. We also show that, among mathematical models which have been independently developed by different authors, there exist similarities in terms of mathematical structure and underlying implicit assumptions.
All-electron calculations of protein using various exchange-correlations functional and basis sets were carried out. Based on these results, we have evaluated the dependencies of fundamental physical properties on theoretical model and basis set. In the quantum calculations of large molecule such as proteins, the easy way of precise theoretical method and large basis set makes explosive high computational costs. In this report, we present a model chemistry which gives good chemical properties and economical computational costs for all-electron calculation for proteins.
Nanowires have attracted much attention for many years because they are most attractive from the point of view of high sensitivity and surface-modifying for various sensors. Recently, silicon nanowires (SiNWs) are widely applied for biosensors. But the method of SiNW fabrication is hard to say suited to mass production because conventional top-down fabrication method needs nano-lithography processes. From these back grounds, we fabricated silicon nanowires from Silicon-on-Insulator (SOI) wafer with conventional only micro-fabrication processes and we showed that the resulting devices exhibited FET behavior after ion implantation allowing us to detect pH and a protein binding. But a few attempts were made so far to control their temperature although this parameter has been shown to be crucial when dealing with biochemical reactions. We also present the results of temperature control of silicon nanowires by using fluorescence thermometry. The resistive heating on nanowires was carried out with applying voltage potential of 6~12V in air condition, and the temperature at the central line along SiNWs increasing from 30 degrees to 35~70 degree was observed.
We analyze photothermal excitation of a single-crystalline silicon cantilever. The cantilever is bent by thermal stress generated by thermal diffusion in the direction perpendicular to the cantilever surface. Because the cantilever is made of a homogeneous material, thermal diffusion in the longitudinal direction does not generate thermal stress. Therefore, the higher vibration modes having small spatially periodic mode shapes are easily and effectively excited. We compared the excitation efficiency of two optical wavelengths, 405 and 780 nm. The 405-nm laser-diode beam was found to be 2.3 to 4.2 times more effective in exciting the second flexural mode compared with the 780-nm beam. These differences in excitation efficiency are attributed to the absorbance characteristics of silicon and were confirmed by measuring the transmitted light power (lost power) against the incident light power.
To reveal what kind of mental model enables an agent to learn altruistic behavior from trial-and-error experiences, a series of computer simulation experiments were performed. We found that high probability of mutual cooperation is achieved by the agents that choose actions based on estimated internal states of others, compared to those that choose actions based of predicted action of others. Mutual cooperation is further promoted by introducing recursive estimation structure of others and reciprocal embedding structures.
In this paper, correlation between surface Electromyogram (EMG) signal and lateral acceleration of the car was studied to examine the possibility of EMG as an indicator of ride comfort. The EMG measuring experiments are conducted with a normal car and its modified car. Two different cars make a driving slalom in the test course, and a subject sat in a rear seat. Surface EMG signals of Sternocleidomastoid muscles on both sides of the neck are measured. It is found that the values of EMG signals of opposite sides to the direction of car acceleration are growing. In addition, the results show a tendency that root mean square (RMS) value of EMG gets smaller when the acceleration is smaller.
The aim of the present study is to develop the computational model for the electromechanical behaviors of dielectric elastomer actuators. In particular, the general validity of the present model over a wide range of stress and deformation states including uniaxial and multiaxial loading conditions has been demonstrated by using ANSYS.