Non-Destructive Inspection of Concrete Structures Using an Acceleration Pickup
The present paper proposes a method for detecting cracks or honeycombs in concrete structures using an acceleration pickup. The sensor on the concrete surface observes the stationary waves which are generated inside the structures depending on the depth of the crack (if there is a crack) or the bottom of the structure (if there are no cracks or honeycombs). The method measures the depths of the reflection planes (such as cracks or honeycombs) accurately by modeling the sensor output as an output of a linear dynamic system with unknown parameters and by applying a maximum likelihood method. The method is shown to be quite effectively applied to measure the depths of cracks and honeycombs
Fabrication of the micro-gripper with a force sensor for manipulating a cell
A novel micro-gripper has been designed and fabricated to manipulate the small object like a cell. In order to gripping the cell, it should be no restriction to use the micro-gripper in the water. Since the mechanical type micro-gripper is little affected by a surrounding so as to use freely in any environment, compared with other type micro-grippers, it is suitable to treat the cell. In addition, it can reduce the deformation of the cell and control the gripping force flexibly. A point to be considered to manipulate the cell is the force working on the cell and the deformation of the cell according to the applied force. On the gripper a piezo-resistive sensor is integrated for sensing the gripping force. Using the fabricated micro-gripper, micro-glass beads can be successfully manipulated in the water. The resistor of the piezoresistive sensor is successfully changed according to the force on the micro-gripper. If on-going feedback experiment in the gripper system is finished successfully, the proposed micro-gripper can be utilized for manipulating the cell
Diversity of Electrospinning Approach for Vascular Implants: Multilayered Tubular Scaffolds
Abstract The biomimetics of biological structures found in nature remains one of the most promising approaches to engineer functional tissues from natural or synthetic biocompatible materials for the replacement of damaged or injured parts of the human body. Recently, medical therapeutic regimes have advanced into a new era, overcoming the known mechanical and biological variances that occur when using autologous or synthetic grafts. Basically, the core concept of tissue biofabrication, commonly referred to as tissue engineering, is to find out the favorable cellular microenvironments to grow a living tissue prior to clinical uses. In fact, the ability of stem cells to regenerate is controlled via signaling pathways (growth factors) and supporting materials (scaffolds) that guide the cellular activities. After the first successful experiments to fabricate polymer fibers from their solutions, Cooley proposed the use of an electric field a century ago (Cooley (US 692:631, 1902 ). The electrospinning technique has been continually developed as a fruitful polymer processing technique to draw ultrafine nonwoven fibers. Electrospun polymer fibers have been used for a wide range of technical and biotechnical applications such as filtration, organic solar cells, tissue engineering, and drug releasing implants. In this regard, this review begins with an overview about the various spinning approaches for the fabrication of polymer fibers as well as the basic principles of electrospinning process. In addition, this review will highlight vascular bypass surgery and, in particular, the needs for vascular tissue engineering. Finally, the review includes some of the latest attempts to improve the mechanical and biological properties of electrospun polymeric fibers and summarizes the challenges and prospects for the future. Lay Summary However, vascular defects are treated successfully via bypass surgical bypass grafting using autologous or synthetic vessels. The small-diameter vessels (less than 6) are often associated with high failure rate. This review reports some of the recent features that should be highlighted to fabricate an ideal graft for small-diameter vascular grafts. The review introduces multilayered conduits as an alternative approach to overcome the known mechanical and biological mismatches of single layered vascular grafts of electrospun polymers.