The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform

Sun Kyu Park - One of the best experts on this subject based on the ideXlab platform.

  • a novel indirect tensile test method to measure the biaxial tensile strength of concretes and other quasibrittle materials
    Cement and Concrete Research, 2008
    Co-Authors: Sun Kyu Park
    Abstract:

    A novel indirect tensile test method, the biaxial flexure test (BFT) method, has been developed to measure the biaxial tensile strength of concretes. The classical modulus of rupture (MOR) test has been generalized to three dimensions. In this method, we use a circular plate as the new test specimen. This plate is supported by an annular ring. We apply an external load to this specimen through a circular edge. The centers of the specimen, the Loading Device and the support are identical. The biaxial tensile strength measured by this new method is about 19% greater than the uniaxial tensile strength obtained from the classical modulus of rupture test as reported by other researchers. However, at the same time, we also found that the stochastic deviation of the biaxial tensile strength is about 63% greater than the uniaxial strength.

Shougo Minagi - One of the best experts on this subject based on the ideXlab platform.

  • a new method for evaluating the threshold of periodontal ligament mechanoreceptor by slow speed mechanical stimulation
    Journal of Periodontal Research, 2003
    Co-Authors: Mai Hamanaka, Taro Arima, Shuhei Takahashi, Kouichi Hasegawa, Shougo Minagi
    Abstract:

    Objectives:  This study aimed to establish a reliable method for detecting the threshold for perception of force applied to tooth and to report the basic properties of force threshold in the normal dentition subjects. Background:  The perception of mechanical stimulation exerted to tooth is formed by input from periodontal ligament mechanoreceptors and intradental mechanoreceptors. Periodontal ligament mechanoreceptors respond to a wide range speed of stimulus, whereas intradental mechanoreceptors are activated only by a rapid stimulation. Reliable properties of perception have not been reported because of the difficulties to regulate velocity and degree of the stimulus. Methods:  Eighteen healthy subjects were observed in this study (mean age: 27.2 ± 5.7 years). A Loading Device to generate slow speed Loading was fabricated and measured as follows: (i) the fluctuation of the force threshold within a day, (ii) day-to-day fluctuation, (iii) changes in the force threshold by a transient mechanical Loading. Results:  In the normal dentition, it was observed that the fluctuation within a day and day to day of the pressure sense showed no significant differences; however, a transient mechanical Loading caused the sensitivity of the periodontal ligament to decrease significantly. Conclusions:  The Device examining the force threshold resulted from periodontal ligament mechanoreceptors was useful in evaluating the sensitivity of the periodontal ligament.

Alan J Grodzinsky - One of the best experts on this subject based on the ideXlab platform.

  • a versatile shear and compression apparatus for mechanical stimulation of tissue culture explants
    Journal of Biomechanics, 2000
    Co-Authors: Eliot H Frank, Andreas M Loening, Marc E Levenston, Alan J Grodzinsky
    Abstract:

    Abstract We have developed an incubator housed, biaxial-tissue-Loading Device capable of applying axial deformations as small as 1 μm and sinusoidal rotations as small as 0.01°. Axial resolution is 50 nm for applying sinewaves as low as 10 μm (or 1% based on a 1 mm thickness) or as large as 100 μm . Rotational resolution is 0.0005°. The machine is small enough ( 30 cm high ×25 cm ×20 cm ) to be placed in a standard incubator for long-term tissue culture Loading studies. In metabolic studies described here, application of sinusoidal macroscopic shear deformation to articular cartilage explants resulted in a significant increase in the synthesis of proteoglycan and proteins (uptake of 35S-sulfate and 3H-proline) over controls held at the same static offset compression.

Kay C Dee - One of the best experts on this subject based on the ideXlab platform.

  • a Device for long term in vitro Loading of three dimensional natural and engineered tissues
    Annals of Biomedical Engineering, 2003
    Co-Authors: Daniel A Shimko, Kyle K White, Eric A Nauman, Kay C Dee
    Abstract:

    In vitro studies of mechanical loads applied to three-dimensional tissue constructs are important to the design and production of functional, engineered bone tissue. This study reports the development and characterization of a mechanical Device capable of subjecting a three-dimensional section of natural or engineered tissue to precise, reproducible four-point bending deformations over a range of programmable magnitudes and frequencies. To test the biological and mechanical capabilities of the system, a low-cycle (360 cycles/day), medium-range strain (2500 microstrain), long-term (16 day) Loading regime was applied to rat bone marrow stromal cells cultured in porous DL-polylactic acid scaffolds. Cells proliferated in culture throughout the experiment, and with time showed an increase in alkaline phosphatase expression per cell. Calcium and phosphorus mineral deposition by the unloaded group was significantly greater (p < 0.05) than that deposited by the loaded group. The molar ratio of calcium to phosphorus in the unloaded group (0.94:1) was significantly greater (p < 0.05) than that of the loaded group (0.41:1). The Loading Device presented here is a tool which can be used to help elucidate contributions of mechanical Loading/fatigue on biodegradable materials, as well as study the effects of mechanical Loading on natural or engineered tissues in vitro. © 2003 Biomedical Engineering Society.

Lang Huang - One of the best experts on this subject based on the ideXlab platform.

  • model of time dependent and stress dependent chloride penetration of concrete under sustained axial pressure in the marine environment
    Construction and Building Materials, 2018
    Co-Authors: Jie Zhao, Lang Huang
    Abstract:

    Abstract The effect of sustained compressive Loading on the chloride penetration of concrete was investigated and a self-monitoring Loading Device was developed. A series of prisms were loaded under five different sustained axial stress levels and four different numbers of wet/dry chloride cycles. Both the apparent chloride diffusion coefficient D a and the surface chloride concentration C s values were time and stress dependent with a sudden change threshold value of approximately 0.3 f c . A model was proposed to predict the chloride penetration profiles of concrete under sustained axial pressure, taking both the time-dependent and the stress-dependent characteristics of D a and C s into account.