A guided wave propagation method for delamination detection in fiber-metal laminates.

This study aimed to assess the delamination detection in FMLs via the finite element (FE) simulations of Lamb wave propagation. An FE model of an FML specimen with [Al/90/Al/90/Al] layup was developed. Delamination damage of 10 and 25 mm diameters was induced between different layers of the FML specimen.

The assessment of implant shape-dependent failure mechanisms in primary total hip arthroplasty using finite element analysis.

The three mechanisms known to be responsible for the failure of uncemented femoral stems in primary total hip arthroplasty (THA) are the stress shielding, excessive bone-implant interface stress, and excessive initial micromotion. Since implant designers usually have to sacrifice two mechanisms to improve the other one, the aim of this study was to assess which of them plays a more important role in the failure of uncemented stems. Two hip implant stems which are widely used in the primary THA and their mid-term clinical outcomes are available, were selected.

Prediction of Mechanical Properties of Artificially Weathered Wood by Color Change and Machine Learning.

Color parameters were used in this study to develop a machine learning model for predicting the mechanical properties of artificially weathered fir, alder, oak, and poplar wood. A CIELAB color measuring system was employed to study the color changes in wood samples. The color parameters were fed into a decision tree model for predicting the MOE and MOR values of the wood samples.

Quantitative ultrasound and machine learning for assessment of steatohepatitis in a rat model.

Objectives: To develop a machine learning model based on quantitative ultrasound (QUS) parameters to improve classification of steatohepatitis with shear wave elastography in rats by using histopathology scoring as the reference standard.

Methods: This study received approval from the institutional animal care committee. Sixty male Sprague-Dawley rats were either fed a standard chow or a methionine- and choline-deficient diet.

Acoustic radiation force induced resonance elastography of coagulating blood: theoretical viscoelasticity modeling and ex-vivo experimentation.

Deep vein thrombosis is a common vascular disease that can lead to pulmonary embolism and death. The early diagnosis and clot age staging are important parameters for reliable therapy planning. This article presents an acoustic radiation force induced resonance elastography method for the viscoelastic characterization of clotting blood.

A Frequency-Shift Method to Measure Shear-Wave Attenuation in Soft Tissues.

In vivo quantification of shear-wave attenuation in soft tissues may help to better understand human tissue rheology and lead to new diagnostic strategies. Attenuation is difficult to measure in acoustic radiation force elastography because the shear-wave amplitude decreases due to a combination of diffraction and viscous attenuation. Diffraction correction requires assuming a cylindrical wavefront and an isotropic propagation medium, which may not be the case in some applications.

A Flow Perfusion Bioreactor System for Vocal Fold Tissue Engineering Applications.

The human vocal folds (VFs) undergo complex biomechanical stimulation during phonation. The aim of the present study was to develop and validate a phono-mimetic VF flow perfusion bioreactor, which mimics the mechanical microenvironment of the human VFs in vitro. The bioreactor uses airflow-induced self-oscillations, which have been shown to produce mechanical loading and contact forces that are representative of human phonation.

Detection of Steatohepatitis in a Rat Model by Using Spectroscopic Shear-Wave US Elastography.

Purpose To compare low- versus high-frequency ultrasonographic (US) elastography for detection of steatohepatitis in rats by using histopathologic findings as the reference standard. Materials and Methods Between March and September 2014, after receiving approval from the institutional animal care committee, 60 male Sprague-Dawley rats were fed either a standard chow for 4 weeks or a methionine- and choline-deficient diet for 1, 4, 8, or 12 weeks to induce a continuum of steatohepatitis severity. Liver shear stiffness was assessed in vivo by using US elastography at low (40-130-Hz) and high (130-220-Hz) frequencies.

Ultrasound Shear Wave Viscoelastography: Model-Independent Quantification of the Complex Shear Modulus.

Ultrasound shear wave elastography methods are commonly used for estimation of mechanical properties of soft biological tissues in diagnostic medicine. A limitation of most currently used elastography methods is that they yield only the shear storage modulus ( G ) but not the loss modulus ( G ). Therefore, no information on viscosity or loss tangent (tan δ) is provided.

Ultrasound viscoelasticity assessment using an adaptive torsional shear wave propagation method.

Purpose: Different approaches have been used in dynamic elastography to assess mechanical properties of biological tissues. Most techniques are based on a simple inversion based on the measurement of the shear wave speed to assess elasticity, whereas some recent strategies use more elaborated analytical or finite element method (FEM) models. In this study, a new method is proposed for the quantification of both shear storage and loss moduli of confined lesions, in the context of breast imaging, using adaptive torsional shear waves (ATSWs) generated remotely with radiation pressure.

Association among diameter and volume of follicles, oocyte maturity, and competence in intracytoplasmic sperm injection cycles.

Aim: The follicular size has been considered for years as an index for oocyte maturity in stimulated ovulation cycles so that the time of initiating human chorionic gonadotropin (HCG) has been formerly determined by the ultrasonography measurement of larger follicles. The other studies have demonstrated that there was no significant difference between fertility of oocytes aspirated from follicles with various sizes. The objective of this study to explore the associations among the size and volume of extracted follicles at the time of oocyte collection with the rate of collection, oocyte maturity, and oocyte competence in the intracytoplasmic sperm injection (ICSI) therapeutic cycles.

Frequency adaptation for enhanced radiation force amplitude in dynamic elastography.

In remote dynamic elastography, the amplitude of the generated displacement field is directly related to the amplitude of the radiation force. Therefore, displacement improvement for better tissue characterization requires the optimization of the radiation force amplitude by increasing the push duration and/or the excitation amplitude applied on the transducer. The main problem of these approaches is that the Food and Drug Administration (FDA) thresholds for medical applications and transducer limitations may be easily exceeded.

Viscoelasticity of hyaluronic acid-gelatin hydrogels for vocal fold tissue engineering.

Crosslinked injectable hyaluronic acid (HA)-gelatin (Ge) hydrogels have remarkable viscoelastic and biological properties for vocal fold tissue engineering. Patient-specific tuning of the viscoelastic properties of this injectable biomaterial could improve tissue regeneration. The frequency-dependent viscoelasticity of crosslinked HA-Ge hydrogels was measured as a function of the concentration of HA, Ge, and crosslinker.

Non-invasive in vivo measurement of the shear modulus of human vocal fold tissue.

Voice is the essential part of singing and speech communication. Voice disorders significantly affect the quality of life. The viscoelastic mechanical properties of the vocal fold mucosa determine the characteristics of the vocal folds oscillations, and thereby voice quality.

Rayleigh wave propagation method for the characterization of a thin layer of biomaterials.

An experimental method based on Rayleigh wave propagation was developed for quantifying the frequency-dependent viscoelastic properties of a small volume of expensive biomaterials over a broad frequency range. Synthetic silicone rubber and gelatin materials were fabricated and tested to evaluate the proposed method. Planar harmonic Rayleigh waves at different frequencies, from 80 to 4000 Hz, were launched on the surface of a sample composed of a substrate with known material properties coated with a thin layer of the soft material to be characterized.

Experimental methods for the characterization of the frequency-dependent viscoelastic properties of soft materials.

A characterization method based on Rayleigh wave propagation was developed for the quantification of the frequency-dependent viscoelastic properties of soft materials at high frequencies; i.e., up to 4 kHz.

The effects of fetal gender on serum human chorionic gonadotropin and testosterone in normotensive and preeclamptic pregnancies.

Introduction: The aim of the present study was to evaluate the effects of fetal sex on serum human chorionic gonadotropin (hCG) and testosterone in normotensive and preeclamptic pregnancies.

Materials And Methods: This is a cross-sectional study and 139 women with singleton pregnancies in the third trimester were studied. Seventy-one pregnancies were uncomplicated; among those were 35 male and 36 female fetuses.

Robotic assisted reduction of femoral shaft fractures using Stewart platform.

A robotic system with 6 DOF mobility was proposed for reduction of femoral shaft fractures based on Stewart platform. A plan for implementing the platform on bone fragments was introduced and a step by step strategy for performing the reduction procedure, based on the system's inverse kinematic solution, was proposed. The efficacy of the system was evaluated in some case studies and it was shown that it can be locked to act as an external fixator.