Abstract: Systems and methods in accordance with embodiments of the invention determine the effective toughness of a given material, and also implement materials possessing improved effective toughness values. In one embodiment, a method of determining the effective toughness of a material includes: causing a crack to propagate through the material; where the relative constant velocity and the relative overall direction are prescribed and maintained for the duration of the propagation of the crack through the material; measuring the energy release rate of the crack as it propagates through the material; and defining the effective toughness of the material as the maximum value of the measured energy release rate.

Abstract: Methods for measuring the effective fracture toughness in a material are described. A rail and roller system are used to apply a gradual force to a specimen. The time-dependent force creates a steady fracture development that allows a camera to record the progressive fracture in the material. Mathematical methods can then be used to analyze the fracture progression and determine the effective fracture toughness.

Abstract: Methods for measuring the effective fracture toughness in a material are described. A rail and roller system are used to apply a gradual force to a specimen. The time-dependent force creates a steady fracture development that allows a camera to record the progressive fracture in the material. Mathematical methods can then be used to analyze the fracture progression and determine the effective fracture toughness.

Abstract: Systems and methods in accordance with embodiments of the invention determine the effective toughness of a given material, and also implement materials possessing improved effective toughness values. In one embodiment, a method of determining the effective toughness of a material includes: causing a crack to propagate through the material; where the relative constant velocity and the relative overall direction are prescribed and maintained for the duration of the propagation of the crack through the material; measuring the energy release rate of the crack as it propagates through the material; and defining the effective toughness of the material as the maximum value of the measured energy release rate.

Abstract: An apparatus for simultaneously measuring longitudinal and shear wave speeds in materials under load via echo or transmission is described. The apparatus comprises a housing with an open end, a closed end opposite the open end with a hole in the closed end, and a housing exit port. A spacer resides inside the housing, the spacer having a spacer specimen side and a spacer transducer side. A load transferring body having a transducer hole fits inside the housing and contacts an interior surface of the housing. An ultrasonic transducer fits inside the transducer hole of the load transferring body. A transducer depressing mechanism secures the ultrasonic transducer against the spacer transducer side, whereby users can simultaneously measure longitudinal and shear wave speeds of specimens inserted into the hole in the closed end of the housing and contacting the spacer.

Abstract: An adhesive system with material and structural heterogeneity is described. The adhesive system comprises a tape having a spatially heterogeneous physical property, the spatially heterogeneous physical property is configured to enhance the adhesive strength of the adhesive system when the adhesive system is in contact with a substrate and/or attain adhesion directionality. The spatially heterogeneous physical property can include a bending stiffness. Heterogeneous variations in the bending stiffness can be achieved by variations in the tape's thickness, elastic modulus and/or Poisson's ratio. Heterogeneity in thickness can be attained by mold pressing and/or patterned laminated structures. Elastic modulus heterogeneity can be achieved by masked irradiation of the tape, where the tape is made of an irradiation-sensitive material. Also described is an adhesive system with a patterned film that exhibits adhesion directionality when the adhesive system is in contact with a substrate.

Abstract: An implantable prosthetic valve that is transformable from a first helical pre-implantation configuration to a second valvular functional configuration, and methods of delivery.

Abstract: The present invention relates to the field measuring the mechanical response of micro-electro-mechanical systems. More specifically, the present invention pertains to a method and apparatus that allows the direct control of the load applied to a Micro-Electro-Mechanical System in order to measure the mechanical response. The system comprises a loading sub-system, a displacement measurement sub-system, and an optional observation sub-system.

Abstract: Systems and methods for manipulating light with tunable ferroelectric photonic devices. Devices having tunable properties that exhibit photonic bandgap behavior are fabricated from ferroelectric materials. Apparatus is provided to apply tuning signals to the ferroelectric material using one or more of electric fields, mechanical forces, optical fields, and thermal fields. Control circuitry is provided to generate the control signals needed to apply the tuning signals. Input and output ports are provided to allow input signals to be received and to provide output signals. In some cases, a feedback loop is provided to use a portion of the output signal as a diagnostic signal for control of the operation of the device within an acceptable range. It is expected that ferroelectric photonic devices operating according to principles of the invention will be useful for a wide variety of applications, including optical switching, optical modulation, optical computing, and performing logic optically.

Abstract: An implantable prosthetic valve that is transformable from a first helical pre-implantation configuration to a second valvular functional configuration, and methods of delivery.

Abstract: Systems and methods for manipulating light with tunable ferroelectric photonic devices. Devices having tunable properties that exhibit photonic bandgap behavior are fabricated from ferroelectric materials. Apparatus is provided to apply tuning signals to the ferroelectric material using one or more of electric fields, mechanical forces, optical fields, and thermal fields. Control circuitry is provided to generate the control signals needed to apply the tuning signals. Input and output ports are provided to allow input signals to be received and to provide output signals. In some cases, a feedback loop is provided to use a portion of the output signal as a diagnostic signal for control of the operation of the device within an acceptable range. It is expected that ferroelectric photonic devices operating according to principles of the invention will be useful for a wide variety of applications, including optical switching, optical modulation, optical computing, and performing logic optically.

Abstract: Apparatus tests the durability of a peripheral artery medical device based upon anatomical loading conditions. A peripheral artery medical device is mounted to a support element, typically a hollow tube, having first and second end portions. End holding elements are mounted to a base and are secured to the first and second end portions. The apparatus further comprises means for applying a plurality of cycles of at least one of the following loading conditions to the medical device support element at the location of the peripheral artery medical device: torsion, tension/compression, bending and pinching. In some embodiments the apparatus comprises an environmental chamber housing at least the support element so to mimic the service temperature environment of the medical device. A method for testing the durability of a peripheral artery medical device based upon anatomical loading conditions is also disclosed.

Abstract: An implantable prosthetic valve that is transformable from a first helical pre-implantation configuration to a second valvular functional configuration, and methods of delivery.

Abstract: A coiled endoluminal prosthesis system may include means for rotating a delivery catheter while axially releasing a coiled endoluminal prosthesis from the delivery catheter. A release element may be retracted simultaneously with rotation of the delivery catheter. The coiled endoluminal prosthesis may have a first direction of spiral in a first rotational direction. The delivery catheter may be rotated in a second rotational direction while axially releasing the coiled endoluminal prosthesis from the delivery catheter. The endoluminal prosthesis may be configured to reduce or eliminate any difference between the length of the endoluminal prosthesis when in the reduced diameter state and when in the expanded diameter state.

Abstract: A coiled ladder stent comprises first and second rails and rungs connecting the rails. At least one rung has lower strength portion or is an enhanced flexibility rung, or both. The lower strength portion is positioned at a reduced strength fracture location along the rung so to promote any fracture of the ladder stent at the fracture location along the rung to help prevent fracture of a rail. One way to make the lower strength portion is to make the cross-sectional area of the lower strength portion less than the average cross-sectional area of the rung. The enhanced flexibility aspect helps to accommodate relative movement between the first and second rails. Doing so helps to prevent fracture of the rails and rungs. In some embodiments of the invention the enhanced flexibility rung comprises one or more nonlinear, such as generally S-shaped or generally U-shaped, portions.

Abstract: The present invention relates to the field measuring the mechanical response of micro-electro-mechanical systems. More specifically, the present invention pertains to a method and apparatus that allows the direct control of the load applied to a Micro-Electro-Mechanical System in order to measure the mechanical response. The system comprises a loading sub-system, a displacement measurement sub-system, and an optional observation sub-system.