JOURNAL OF ACOUSTICAL ENGINEERING SOCIETY OF IRAN
Year:2017 | Volume:5 | Issue:1 |Papers Count:7

Considering the use of mechanical stimulation such as low-intensity ultrasound for proliferation and differentiation of stem cells, it is essential to understand the physical and acoustical mechanisms of acoustic waves in vitro. In this study, modeling of the mechanical index (MI) was applied to provide treatment protocol and to understand the effective physical processes on reproducibility of stem cells. The acoustic pressure and mechanical index equations are modeled and solved to estimate optimal mechanical index for kHz and MHz frequencies for continuous exposure mode, transducer and the culture environment area in cylindrical coordinates. Based on the results of the axial and radial pressure distributions, regions with 0. 7 mechanical index (cavitation threshold), more and less than threshold of induced cavitation were identified for extracting of radiation arrangement to cell medium. In order to validate the results of the modeling, the acoustic pressure in the water and near field depth was measured by a piston hydrophone. Results of modeling and experiments show that the model is consistent with the experimental results of those having correlation coefficients of 0. 91 and 0. 90 (p<0. 05) for 1 MHz and 40 kHz transducer, respectively.

Acoustic remote sensing techniques is a useful tool for seabed sediment classification in hydrography, that in this method, seabed sediments estimated using send and receive sound waves and analysis of the backscatter data. Backscatter data from sediment has several features that can be made by extracting them, sediment separating and classification. in this paper, is provided laboratory conditions to investigate the acoustic properties of sediments. Echo receive from sediment in 4 Frequency (55, 60, 65, 73 khz) is processed using acoustic devices and Insert 4 type of sediment in the aquarium bed. Feature were extracted, including statistical moment (energy, time-spread, skewness and kurtosis), spectral moment (standard deviation, the order of the moment, spectral skewness, spectral kurtosis and power spectral density) and the fractal dimension (Hausdorff (. In this experiment, energy parameter, standard deviation and average power (from power spectral density) well able to distinguish sediments.

In this paper, the acoustic behavior of automotive cavity components is Investigated. For this purpose, by the aid of numerical simulation, the effects of using porous layer insulation in different parts of the cavity are studied. The numerical simulation is based on Statistical Energy Analysis; therefore, at the first stage the governing equations for the Statistical Energy Analysis are presented. Then, all internal and external components of the car body are divided into small subsystems. Herewith, the internal and external cavities of the car body have been identified. In the following, considering that the method of Statistical Energy Analysis is based on energy storage and transmission, connections between all components of the model are created. Then, with applying all the sound sources into the model, the effects of using porous materials on sound transmission loss in some of the main components of the car body, including the roof, floor and dashboard panels are investigated. The results show that using of sound insulations in different parts of the car, especially on the roof, improves the noise reduction to the cavity.

Today, sounds in the environment are a stressor and can damage different systems of the body. Neuronal messages are controlled and regulated by enzymes. Among these enzymes, acetylcholine esterase enzyme is more important in memory and learning. The aim of this study is to investigate the effect of mechanical waves on cholinergic system in rat behaviors in stressful environments. In this study, 10 adult male rats were used. The rats were exposed to 528 Hz and 100 dB 2 hr per day for 21 days. The activity of acetylcholinesterase enzyme was measured. The plus maze test was used to measure anxiety behavior. The results showed that the sound increases the activity of acetylcholinesterase enzyme, which causes memory impairment. The percentage of time in the open arm decreases, in addition, the percentage of enter into the open arm decreases, which indicate an increase in anxiety. Moreover, corticosterone level has increased. Results reveal that sound changes memory and anxiety behaviors by distrupting the cholinesterase enzyme activity and neurotransmitter secretion.

The drugs that usually are applied as anticancer are toxins. These toxines are inorganic or organic molecules which harm normal cells as much as cancer cells. Resently, researchers are trying to find ways to develop targeted drugs (molecules) which kill cancer cells exclusively. Different methods have been developed for killing cancer cells. e. g. heating the toxic drugs by electromagnetic field or activate the drug locally by sound or heat waves. These methods are non-invasive. In this research, two physical techniques were used to kill cancer cells, 528 Hz sound waves and Fe2O3 nanoparticles magnetic field. Nanoparticles were synthesized and cells were cultured. The viability of cells was conducted by MMT test. It was evident that the nanoparticles interacting with the cells membrane and the magnetic field applied on the sample changed the membrane structure. Considering the possibility of frequency and intensity change sound wavw is more applicables in short time.

In this Paper, at first a band structure of a two-dimensional phonon crystal with square lattice including polymetheyl methacrylate cylinders, in air matrix, waz considered. By accounting for the band gap range of this structure, a sound waveguide was simulated. The expected result was observed. Then, another structure with a hexagonal lattice, including aluminum cylinders in tungsten matrix material was studied. By utilizing a finite element, computational method and COMSOL software and Matlab bandwidth structure was calculated. Also, the effect of symmetry on the width of the gap was investigated. By detecting the band gap, the simulation of an audio waveguide in the frequency range of 0. 59 and 0. 61 kHz was performed.

Ultrasound is sound whose frequency is too high for humans to hear which is in the frequency range of 20 Hz– 20 kHz, and the frequency of ultrasound waves is above 20 kHz. The aim of this study was to observe the effect of ultrasound and sonication (20 kHz prob) on heat and chemical stability of α-lactalbumin. The interaction of anionic surfactant, SDS, and cationic surfactant, DTAB, with α-lactalbumin in the absence and presence of ultrasound has been investigated using UV and fluorescence spectroscopy. α-lactalbumin was denatured in a 2-state process. Using UV spectroscopy, the stability of α-lactalbumin ) ( was the least upon treatment with SDS in the absence of ultrasound (7. 483 kJ. mol-1) and this amount increases after 20 minutes of sonication time (8. 691 kJ. mol-1). Also, the stability of α-lactalbumin ) ( was the least upon treatment with DTAB in the absence of ultrasound (8. 817 kJ. mol-1) and this amount increases after 20 minutes of sonication time (11. 210 kJ. mol-1). Thermodynamic parameters ( Hm, Cp, Tm and G0(H20)) were determined for the thermal denaturation of bovine α-lactalbumin in the absence and presence of ultrasound using UV spectroscopy. Results shows that ultrasound increases the heat stability and Tm of α-lactalbumin and decreases the Hm and Cp, m.