Model studies for molecular recognition of carbonic anhydrase and carboxypeptidase

Model studies using Zn(2+) complexes of various derivatives of macrocyclic triamines ([12]aneN(3)) and tetraamines (cyclen) have been found to be useful in elucidating and understanding the intrinsic properties of substrate or inhibitor recognition by zinc ions at the active centers of carbonic anhydrase and carboxypeptidase.     

A new algorithm for packet routing problems using chaotic neurodynamics and its surrogate analysis

We propose a new algorithm for routing packets which effectively avoids packet congestion in computer networks. The algorithm involves chaotic neurodynamics. To realize effective packet routing, we first composed a basic method by a neural network, which routes packets with shortest path information between two nodes in the computer network. When the computer network has an irregular topology, the basic routing method does not work well, because most of packets cannot be transmitted to their destinations due to packet congestion in the computer network. To avoid such an undesirable problem, we employed chaotic neurodynamics to extend the basic method. Numerical experiments show that our proposed method exhibits good performance for scale-free networks. We also analyze why the proposed routing method is effective, comparing the proposed method with several stochastic methods. We introduced the method of surrogate data, a statistical hypothesis testing which is often used in the field of nonlinear time-series analysis. Analysis of the proposed method by the method of surrogate data reveals that the chaotic neurodynamics is most effective to decentralize the packet congestion in the computer network.     

Dynamic Capturing Strategy for a 2-D Stick-Shaped Object Based on Friction Independent Collision

This paper proposes dynamic capturing strategies where a 2D stick-shaped object with both translational and rotational velocity is completely stopped by two robotic fingers. We first show the fingertip position and the object orientation for generating a desired velocity of the object under the friction independent collision. Once the object results in a pure translational motion whose direction is perpendicular to the longitudinal axis of object, it is guaranteed that two fingers can always capture the object irrespective of friction coefficient. By using this nature, we show both 2-step and 3-step capturing strategies for a 2D stick-shaped object whose width is negligibly small. The 3-step capturing strategy can guide the object in an arbitrary direction, while the 2-step one can do it only in a particular direction. The proposed strategies are demonstrated by experiments for verifying our idea.     

Anisotropic proton-conducting membranes prepared from swift heavy ion-beam irradiated ETFE films

Poly(ethylene-co-tetrafluoroethylene) (ETFE) films were irradiated by swift heavy ion-beams of ¹²⁹Xe²³⁺ with fluences of 0, 3 × 10⁶, 3 × 10⁷, 3 × 10⁸ and 3 × 10⁹ ions/cm², followed by γ-ray pre-irradiation for radiation grafting of styrene onto the ETFE films and sulfonation of the grafted ETFE films to prepare highly anisotropic proton-conducting membranes. The fluence of Xe ions and the addition of water in the grafting solvent were examined to determine their effect on the proton conductivity of the resultant membranes. It was found that the polymer electrolyte membrane prepared by grafting the styrene monomer in a mixture of 67% isopropanol and 33% water to the ETFE film with an ion-beam irradiation fluence of 3.0 × 10⁶ ions/cm² was a highly anisotropic proton-conducting material, as the proton conductivity was three or more times higher in the thickness direction than in the surface direction of the membrane.     

Impact of ultrashallow junction on hot carrier degradation ofsub-0.25-μm nMOSFETs

We have investigated the hot carrier (HC) reliability of nMOSFETs with an ultrashallow source/drain (S/D) extension, and found that lightly doped drain (LDD)-type HC degradation is accelerated. The lifetime strongly depends on the extension implantation dose or the implantation angle. A reduced overlap region between the gate electrode and drain diffusion seemed to exaggerate the LDD-type HC degradation. Angled implantation at over 10° effectively suppressed the degradation     

Feasibility study on cellular network analysis with patterned cell culture microdevice

In order to realize cellular network analysis on a chip-based system, our group has been developing a patterned cell culture microdevice with pillars in an array for tapping cells into space surrounded by the pillars. The pillar structures has advantages to trap both adhesive and non-adhesive cells and to precisely control positions of cells and distances between cells for understanding effects of various cell patterns on functions of a cellular network such as cell proliferation, differentiation, and network formation. In this paper, HeLa cell cultivation with the patterned cell culture microdevice having a pillar array fabricated by dry film of thick negative photoresist SU-8 on a glass substrate was executed as a feasibility study on a cellular network analysis. The results revealed that the device performance was found to be enough to culture HeLa cells for more than 48 h. In addition, relative extensibility of blocks of multiple cells compared with single cells tapped on the device was observed. Thus, the patterned cell culture microdevice proposed here could be applicable to analysis of cellular functions.     

PACS and patient data management systems.

It is important for a PACS to have access to the patient data, as well as to the images themselves, for the purpose of sophisticated image archiving, retrieving, viewing and interpretation. There are many kinds of patient data concerning image examinations (i.e., patient name, ID, age, examination date and time, examined regions, methods, findings on images, diagnoses or diagnostic impressions, etc.). Some of them are acquired from image examination apparatus, some are supplied by diagnostic radiologists, while some need be retrieved from the radiology and hospital information systems. To facilitate this data exchange, a PACS-RIS-HIS coupling is required. The author has constructed at Tokyo University Hospital a small PACS called TRACS, which adopts one of the possible PACS-RIS-HIS coupling configurations.     

Preparation of amorphous Ni-Pd-P particles by melt ejection into stirred water and their hardness and thermal stability

Amorphous spherical particles with diameters of 0.5 to 1.4 mm have been prepared by melt ejecting Ni-rich Ni-Pd-P alloys into stirred cold water with 1 vol pct surfactive agent. The sphericity of the amorphous particles defined by the difference in diameter was better than 98 pct. Particle diameters (d) are 2 to 3 times larger than the orifice diameter (2r) of the quartz nozzle. The size ratio has been interpreted by the Raplace’s relation (d = 4r) derived from the assumption that an internal pressure of molten alloy is equal between cylindrical stream and spherical droplet. From the result that no spherical amorphous particles are formed in the cold water without surfactive agent, a significant decrease in the surface tension of coolant by the addition of surfactive agent is essential in the formation of spherical liquid particles from the ejected melt stream. The amorphous particles with diameters below about 1.0 mm exhibit hardness, crystallization temperature, and heat of crys-tallization similar to those from the amorphous ribbon with about 40 μm thickness. However, the onset temperature and heat of relaxation are lower by 16 K (4.2 pct) and larger by 130 J/mol (13 pct), respectively, for the particles. It is thus concluded that the amorphous spherical particles have the same thermal stability as that of the amorphous ribbon and its structure is in a more disordered state as compared with the ribbon sample.     

Microstructure development in Sb2O3-doped ZnO

The microstructure development in Sb₂O₃-doped ZnO was studied at doping levels up to 2.0 mol%. Dopant Sb₂O₃ reacted with ZnO to form inclusion particles,α-Zn₇Sb₂O₁₂, and inhibited the grain growth of ZnO. With increasing doping level of Sb₂O₃, the growth rate of ZnO decreased whereas that of inclusion particles increased. Some inclusion particles were trapped in ZnO grains at low doping levels of Sb₂O₃, but the volume fraction of trapped inclusion particles decreased with increasing doping level. Stereological analysis of the size and number ratios of ZnO grains and inclusion particles indicated that a compatible assumption is needed to evaluate Zener effect in two-phase sintering.