Yousuke Suzuki

Ion implantation into collagen for the substrate of small diameter artificial grafts

Abstract Ion implantation into collagen coated inner surface of the test tube with a diameter of 2 and 3 mm, length of 50 mm was performed to develop the hybrid type small diameter artificial vascular grafts. Substrates used were polystyrene tubes with a inner diameter of 2 mm and polytetrafluoroethylene (ePTFE) tubes with a inner diameter of 3 mm. Ne + ion implantation at an energy of 150 keV with a fluence of 3 × 10 15 ions/cm 2 was performed as a pre-treatment of protein coating. Ion implanted test tubes were coated with collagen (type I). He + , Ne + and Kr + ion implantation into inner surface of collagen coated tubes were performed at an energy of 150 keV with a fluence of 1 × 10 14 ions/cm 2 . Grafts were exposed to blood for one hour up to 120 days. He + ion implanted collagen coated specimens exhibit cell attachment and inhibition of platelet adhesion. Replaced He + ion implanted collagen coated grafts with carotid artery demonstrated 100% patency for 120 days. In contrast, Ne + and Kr + ion implanted grafts were occluded. He + ion broke the ligand which corresponds to platelet and the ligands corresponding to endothelial cell were still existent after ion implantation. Ion implantation technology into inner surface of the collagen coated test tube may develop a new small diameter artificial vascular grafts.

Plasma protein adsorption onto cell attachment controlled ion implanted collagen

Abstract Ion implantation into collagen (Type I) coated inner surfaces of test tubes with a length of 50 mm and inner diameter of 2 and 3 mm were performed to develop hybrid type small-diameter artificial vascular grafts. He+ ion implanted collagen coated grafts with a fluence of 1×10 14 ions / cm 2 replacing femoral arteries exhibited excellent graft patency. To obtain information about the relationship between plasma protein adsorption and antithrombogenicity of ion implanted collagen surfaces, protein adsorption measurements, platelet adhesion test, and animal study were performed. The amount of fibrinogen, fibronectin and albumin showed minimum value at a fluence of 1×10 14 ions / cm 2 . The adsorption of fibrinogen and fibronectin to surfaces is known to promote the adhesion of platelets. The results indicated that antithrombogenicity of He+ ion-implanted collagen with a fluence of 1×10 14 ions / cm 2 was caused by the reduction of the amount of adsorbed proteins.

Soft sensor suits as man-machine interface for wearable power amplifier

The authors have developed innovative soft sensor suits embedded with electromyogram (EMG) and a variety of sensors for measuring human muscle activities. The sensor suits serve as a man-machine interface for human power amplification. This paper focuses on the EMG part of the sensor suits to study the fundamental issue of torque estimation based on the sensor readings. An innovative auto-calibration system is developed in this study based on multi-regression analysis and neural networks, where an universal database, rather than individual database for each operator, is proposed and as a result, the calibration time is dramatically decreased. The calibration system can also compensate for sensor positioning errors. In the end, the sensor suits are applied as a man-machine interface for a soft power amplifier composed of artificial muscles. The artificial muscles are successfully controlled using the torque information estimated by the EMG sensor suits. The relation between torque estimation errors on sensor suits and maneuverability of power amplifier is experimentally verified.

Hydrogen contents and related properties of a-C:H formed with unbalanced magnetron sputtering

Hydrogenated amorphous carbon (a-C:H) coatings have been deposited on titanium substrate with an unbalanced magnetron sputtering apparatus. The hydrogen contents of the coatings were adjusted by introducing hydrogen-containing gases such as hydrogen, methane, and acetylene. The hydrogen contents of the coatings are determined using elastic recoil detection. The effects of the hydrogen contents on the related properties such as hardness, Raman spectra, contact angle, and adsorption of human serum albumin have been discussed.

Efficient host excitation in thiosilicate phosphors of lanthanide(III)-doped Y4(SiS4)3

Lanthanide (Ln)-doped yttrium thiosilicate (Y1−x Ln x )4(SiS4)3 is synthesized, and its optical properties are studied. In (Y1−x Tb x )4(SiS4)3, the green photoluminescence band corresponding to the intra 4f transition of 5D4 → 7F5 appears at 545 nm and becomes the maximum for x = 0.2 in the range x = 0.01 to 1. The internal quantum efficiency is higher (11% for x = 0.01) for the thiosilicate host excitation (360 nm) than for the direct excitation (1.6%) of the intra 4f transition of 5D4 ← 7F6 (489 nm). A time-resolved photoluminescence study shows that the luminescence of defect states of thiosilicate hosts decays faster (typically 10–30 ns) for higher Tb3+ concentration x. In addition, the rise time of Tb3+ photoluminescence is shorter (10–40 ns) for greater x. Energy transfer from the thiosilicate host to Tb3+ is discussed using these results. For all of (Y1−x Ln x )4(SiS4)3 (x = 0.01, Ln = Pr, Nd, Dy, Er or Tm), the internal quantum efficiency is higher for the host excitation (11–21%) than for the direct excitation of intra 4f transitions (1.1–12%). A photoluminescence excitation study reveals broad host absorption in 300–400 nm for Ln luminescence. These results show the promising characteristics of the host absorption of (Y1−x Ln x )4(SiS4)3 phosphors and their optical properties.

Auto-calibration system of EMG sensor suit

Biogenic measurement has been studied as a robots interface. We have studied the wearable sensor suit as a robots interface. Some kinds of sensor disks are embedded the sensor suit to the wet suit-like material. The sensor suit measures a wearing persons joint, and muscular activity. In this report, we aim to establish an auto-calibration system for measuring joint torques by using EMG sensors based on neural network and sensor disks of a lattice. The Torque presumption was performed using the share neural network, which learned the data that formed the whole subjects teacher data. Additional training of the share neural network was carried out using the individual teaching data. As a result, that was able to do the neural network training in short time, high probability and high accuracy to training of initial neural network. Moreover, high-presumed accuracy was able to be acquired by this method Next, Sensor disks of a lattice was developed. EMG is measurable, checking the state of an electrode by that can measure biogenic impedance. That was able to measure EMG by sensor disks which has low impedance We measured EMG and joint torque by trial production sensor suit and torque measuring instrument. The predominancy of the torque presumption using the share neural network was check. We proposed Measurement system, which consists sensor disk of lattice. Experimental results show the proposed method is effective for the auto-calibration.