The Experts below are selected from a list of 180 Experts worldwide ranked by ideXlab platform

Michael A. Greminger - One of the best experts on this subject based on the ideXlab platform.

  • Investigating protein structure change in the zona pellucida with a microrobotic system
    International Journal of Robotics Research, 2005
    Co-Authors: Yu Sun, Bradley J. Nelson, Michael A. Greminger
    Abstract:

    In this paper we present a microrobotic system that integrates micro- scope vision and microforce feedback for characterizing biomem- brane mechanical properties. We describe robust visual tracking of deformable biomembrane contours using physics-based models. A multi-axis microelectromechanical systems based force sensor is used to determine applied forces on biomembranes and to de- velopanovelbiomembranemechanical model.Byvisually extracting biomembrane deformations during Loading, Geometry changes can be used to estimate applied forces using a biomembrane mechanical model and the determined elastic modulus.Forces on a biomembrane can be visually observed and controlled, thus creating a framework for vision and force assimilated cell manipulation. The experimental results quantitatively describe a stiffness increase seen in the mouse zona pellucida (ZP) after fertilization. Understanding this stiffness increase, referred to as “zona hardening”, helps provide an under- standing of ZP protein structure development, i.e., an increase in the number of cross links of protein ZP1 between ZP2 and ZP3 units that is conjectured to be responsible for zona hardening. Furthermore, the system, technique, and model presented in this paper can be ap- plied to investigating mechanical properties of other biomembranes and other cell types, which has the potential to facilitate many bio- logical studies, such as cell injury and recovery where biomembrane mechanical property changes need to be monitored.

  • Investigating protein structure with a microrobotic system
    IEEE International Conference on Robotics and Automation 2004. Proceedings. ICRA '04. 2004, 2004
    Co-Authors: Michael A. Greminger, Bradley J. Nelson
    Abstract:

    This paper presents a microrobotic system integrating microscope vision and microforce feedback for characterizing biomembrane mechanical properties. Robust visual tracking of deformable biomembrane contour using physics-based models is described. A multi-axis MEMS-based force sensor is used to determine applied forces on biomembranes and develop a novel biomembrane mechanical model. By visually extracting Geometry changes on a biomembrane during Loading, Geometry changes can be used to estimate applied forces using the biomembrane mechanical model and the determined elastic modulus. Forces on a biomembrane can be visually observed and controlled, thus creating a framework for vision and force assimilated cell manipulation. The experimental results quantitatively describe mouse zona pellucida (ZP) stiffness increase during ZP hardening and provide an understanding of ZP protein structure development, i.e., an increase in the number of cross links of protein ZP1 between ZP2-ZP3 units that is conjectured to be responsible for ZP stiffness increase. Furthermore, the system, technique, and model presented in this paper can be applied to investigating mechanical properties of other biomembranes and other cell types, which has the potential to facilitate many biological studies, such as cell injury and recovery where biomembrane mechanical property changes need to be monitored.

Peter Pointner - One of the best experts on this subject based on the ideXlab platform.

Bradley J. Nelson - One of the best experts on this subject based on the ideXlab platform.

  • Investigating protein structure change in the zona pellucida with a microrobotic system
    International Journal of Robotics Research, 2005
    Co-Authors: Yu Sun, Bradley J. Nelson, Michael A. Greminger
    Abstract:

    In this paper we present a microrobotic system that integrates micro- scope vision and microforce feedback for characterizing biomem- brane mechanical properties. We describe robust visual tracking of deformable biomembrane contours using physics-based models. A multi-axis microelectromechanical systems based force sensor is used to determine applied forces on biomembranes and to de- velopanovelbiomembranemechanical model.Byvisually extracting biomembrane deformations during Loading, Geometry changes can be used to estimate applied forces using a biomembrane mechanical model and the determined elastic modulus.Forces on a biomembrane can be visually observed and controlled, thus creating a framework for vision and force assimilated cell manipulation. The experimental results quantitatively describe a stiffness increase seen in the mouse zona pellucida (ZP) after fertilization. Understanding this stiffness increase, referred to as “zona hardening”, helps provide an under- standing of ZP protein structure development, i.e., an increase in the number of cross links of protein ZP1 between ZP2 and ZP3 units that is conjectured to be responsible for zona hardening. Furthermore, the system, technique, and model presented in this paper can be ap- plied to investigating mechanical properties of other biomembranes and other cell types, which has the potential to facilitate many bio- logical studies, such as cell injury and recovery where biomembrane mechanical property changes need to be monitored.

  • Investigating protein structure with a microrobotic system
    IEEE International Conference on Robotics and Automation 2004. Proceedings. ICRA '04. 2004, 2004
    Co-Authors: Michael A. Greminger, Bradley J. Nelson
    Abstract:

    This paper presents a microrobotic system integrating microscope vision and microforce feedback for characterizing biomembrane mechanical properties. Robust visual tracking of deformable biomembrane contour using physics-based models is described. A multi-axis MEMS-based force sensor is used to determine applied forces on biomembranes and develop a novel biomembrane mechanical model. By visually extracting Geometry changes on a biomembrane during Loading, Geometry changes can be used to estimate applied forces using the biomembrane mechanical model and the determined elastic modulus. Forces on a biomembrane can be visually observed and controlled, thus creating a framework for vision and force assimilated cell manipulation. The experimental results quantitatively describe mouse zona pellucida (ZP) stiffness increase during ZP hardening and provide an understanding of ZP protein structure development, i.e., an increase in the number of cross links of protein ZP1 between ZP2-ZP3 units that is conjectured to be responsible for ZP stiffness increase. Furthermore, the system, technique, and model presented in this paper can be applied to investigating mechanical properties of other biomembranes and other cell types, which has the potential to facilitate many biological studies, such as cell injury and recovery where biomembrane mechanical property changes need to be monitored.

Addis Kidane - One of the best experts on this subject based on the ideXlab platform.

  • effect of filler Loading Geometry dispersion and temperature on thermal conductivity of polymer nanocomposites
    Polymer Testing, 2017
    Co-Authors: Addis Tessema, Dan Zhao, Joseph Moll, Shanshan Xu, Ronggui Yang, Chen Li, Sanat K Kumar, Addis Kidane
    Abstract:

    Abstract Using a unidirectional heat transfer apparatus, the roles of nanoparticle Geometry, Loading, dispersion and temperature on the thermal conductivity of polymer nanocomposites are investigated. The polymer nanocomposites (PNC) consist of epoxy matrices filled with silica nanopowder and carbon nanotubes, respectively, as well as poly (2-vinylpyridine) (P2VP) matrices loaded with silica nanoparticles. First, it is shown that thermal conductivity generally increases with nanofiller Loading. These results are also reasonably described by the three phase Lewis-Nielsen or Halpin-Tsai analytical models. More importantly, it has been also demonstrated that the thermal conductivity of the polymer nanocomposites greatly depends on the dispersion state of the nanofillers. Furthermore, the effect of temperature on the thermal behavior of PNCs is briefly discussed. These results emphasize the important role of nanoparticles content and dispersion state on the thermal characteristics of polymer nanocomposites, which can be used to design composite materials with tunable thermal behavior.

R.k. Pandey - One of the best experts on this subject based on the ideXlab platform.

  • A composite crack profile model for CTOD determination—II. An experimental application to a small scale yielding situation
    Engineering Fracture Mechanics, 2003
    Co-Authors: C.r. Pratap, R.k. Pandey
    Abstract:

    Abstract An analytical model namely the “Composite Crack Profile (CCP) model” has been presented earlier for the evaluation of crack tip opening displacement (CTOD) from the measured crack mouth opening displacements (CMODs). The model has been applied in the present work for the small scale yielding situation under the conditions of different specimens and Loading geometries (SEN tension, SEN bending, CT). The CTOD evaluated by the model has been compared with the CTOD obtained by the methods prescribed in [A. A. Wells, Symp. Crack Propagation, Paper B4, College of Aeronautics, Cranfield (1961), and T. Hollstein and J. Blanel, Int. J. Fracture13, 385 (1977).] It is sufficient that whereas the model does not necessitate the use of rotational factor for the evaluation of CTOD, it is more versatile in that it can be used with different Loading geometries. The effect of thickness, a/w ratio and the Loading Geometry on the CTOD at crack initiation (CTODi) has also been presented and discussed.

  • Significance of rotational factor r in CTOD determination and the effect of material and Loading Geometry on r
    Engineering Fracture Mechanics, 2003
    Co-Authors: R.k. Pandey, C.r. Pratap, R Chinadurai
    Abstract:

    The CTOD evaluation from the measured CMOD values using a SEN bending Geometry is well standardized in literature. The knowledge of the rotational factor, r, is essential for the conversion from CMOD to CTOD. It has not been possible to determine r for different Loading and specimen geometries other than for the SEN bending, thus making the CTOD evaluation difficult for other geometries. In the present investigation a “Composite Crack Profile” (CCP) model has been used for the evaluation of CTOD. This approach has facilitated the determination of r in other Loading geometries (i.e. SEN tension, CT), thus also making CTOD evaluation possible for them. The effect of the aw ratio, specimen thickness and yield strength on r has also been investigated in addition to the Loading Geometry. The results obtained from the CCP model have been compared with the ones by the BS 5762 method, and the empirical approaches of Robinson and Tetelman, and Hollstein and Blauel. The significant effect of specimen and Loading Geometry on the rotational factor is noted from the present investigation.

  • Studies of constraint factors in K-CTOD and K-R relationships: Effect of specimen, Loading Geometry and material
    Engineering Fracture Mechanics, 2003
    Co-Authors: C.r. Pratap, R.k. Pandey
    Abstract:

    Abstract The crack tip constraints m' and me in the K-CTOD relationships and the K-R (plastic zone) relationship respectively have been evaluated and compared as a function of specimen thickness, a w ratio and the Loading Geometry (namely SEN tension, SEN bending and the CT Geometry). The interrelation between m' and me has also been discussed. The effect of constraints on the crack initiation toughness has been studied and results have been discussed for a structural steel.

  • Composite crack profile model for CTOD determination III: An experimental application to elastic-plastic crack growth situations
    Engineering Fracture Mechanics, 2003
    Co-Authors: C.r. Pratap, R.k. Pandey
    Abstract:

    Abstract A composite crack profile (CCP) model has been applied for the evaluation of CTOD in the elastic-plastic crack growth situations prevailing in a structural steel. The results have been compared with the ones obtained by conventional method (using plastic hinge model such as Wells etc.) The CTOD-Resistance Curves (δR-curves) have also been obtained as a function of specimen thickness, a/w ratio and the Loading Geometry by using the CCP model. The significance of crack initiation CTOD (δi) and the maximum load CTOD (δm) has been discussed in relation to various geometrical parameters (i.e. thickness, a/w ratio and Loading Geometry).