The propagation of slow compressional waves in air-saturated permeable solids was studied by experimental means between 10 and 500 kHz. The velocity and attenuation coefficient were measured as functions of frequency from the insertion delay and loss of airborne ultrasonic waves transmitted through thin slabs of 1-5 mm in thickness. Porous ceramics of 2-70 Darcy and natural rocks of 200-700 mDa...

The study described herein was undertaken to determine the role of proteins, in general, and collagen, in particular, in the observed absorption and speed of ultrasound in biological tissues. It had earlier been observed that ultrasonic absorption in tissues occurs at the macromolecular level, •'z though an additional contribution to attenuation arises from tissue structural features. a Each of...

In this paper procedures for estimating the sound absorption coefficient when the specimen has inherently low absorption are discussed. Examples of this include the measurement of the absorption coefficient of pavements, closed cell foams and other barrier materials whose absorption coefficient is nevertheless required, and the measurement of sound absorption of muffler components such as perfo...

The aim of this paper was twofold: first, to present a virtual instrument for characterization of the cataract severity in the lens of the eye, based on the indirect measurements of ultrasound attenuation coefficient, second, to evaluate the instrument in vitro by assessment of measurement errors in case of the four different phantoms with a priory known characteristics (pure water, castor oil,...

Abstract Introduction: Recent studies have shown that the use of high-density nanoparticles (NPs) in concrete composition improves its radiation shielding properties. In present study, linear attenuation coefficients and photon scattering properties newly developed Nano-concretes been calculated using MCNPX Monte Carlo code. Material methods: The containing 10%, 20%, 30% weight percentage Osmiu...

The formation of burn-scar tissue in human skin profoundly alters, among other things, the structure of the dermis. We present a method to characterize dermal scar tissue by the measurement of the near-infrared attenuation coefficient using optical coherence tomography (OCT). To generate accurate en face parametric images of attenuation, we found it critical to first identify (using speckle dec...

Introduction: The heavyweight concretes have been widely used for constructing medical or industrial radiation facilities with photon sources. Materials and Methods: In this study, heavy concretes containing galena (PbS) and several borated minerals are proposed as suitable materials against photons. The shielding properties of 21 galena concretes containing seven borated minerals with three m...

The performance requirements of the concrete of containment structures are mainly radiological protection, structural integrity and durability, etc. For this purpose, highperformance heavy density concrete with special attributes can be used. The aggregate of concrete plays an essential role in modifying concrete properties and the physico-mechanical properties of the concrete affect significan...

Cataract is very frequent disease of human eye and the diagnosis of this disease is not difficult. However, it is important to describe it quantitatively, but it is difficult using only the slit lamp. Ultrasound examinations are widely used in ophthalmology. Piezoelectric crystals generate ultrasound waves of 5–50 MHz. Short pulses of 2 to 3 cycles are sent from transducer into the eye. These p...

BACKGROUND This study describes a series of experimental work completed towards characterizing candidate materials for fabricating brain and muscle tissue mimicking phantoms. METHODS The acoustic speed, attenuation, impedance, thermal diffusivity, specific heat and thermal conductivity were measured. RESULTS The resulting brain (2% w/v agar-1.2% w/v Silica Dioxide-25%v/v evaporated milk) an...