Measurements of acoustic properties of biomacromolecules using bio-ultrasonic micro-spectroscopy

利用生物超声波谱系统测量了聚酯膜作为生物大分子模型在60~220 MHz频率范围内的声速、衰减、阻抗和密度等声学参数。在频率范围内观察到了速度和衰减的频率依赖性。在20-26℃的温度范围内，还测量了聚酯薄膜声学参数的温度依赖性。衰减随温度升高而增大，速度随温度升高而减小。为了测量具有速度色散的样品的速度频率特性，采用复数模式进行速度测量。以水为液体材料，聚酯薄膜为固体材料，在100~200 MHz频率范围内用复数模式进行速度测量。在水中没有观察到速度弥散，而聚酯薄膜的速度弥散为0.02(m/S)/MHz，我们建议用衰减系数的频率指数作为表征参数。研究了频率指数与弛豫参数之间的关系。为了进行数值计算，采用了单一松弛过程的模型。例如，根据测量的25%葡萄糖水溶液在20至700 MHz的频率范围内的衰减系数，确定了松弛时间和参数。

The acoustic parameters of velocity, attenuation, impedance, and density of polyester film as a model for biomacromolecules were measured in the frequency range 60 to 220 MHz using the bioultrasonic spectroscopy system. Frequency dependences of velocity and attenuation in the frequency range were observed. The temperature dependence of the acoustic parameters of polyester film is also measured in the temperature range 20-26℃. Attenuation increases and velocity decreases as temperature increases.In order to measure the frequency characteristics of velocity for a sample with velocity dispersion, velocity measurement using a complex mode was introduced. Water as liquid material and polyester film as solid material were taken and velocity measurements using the complex mode were performed in the frequency range 100 to 200 MHz. Velocity dispersion was not observed for water and the dispersion of 0.02(m/s)/MHz was measured for polyester film.We proposed using the exponent on frequency of the attenuation coefficient as a characterizing parameter. The relation between the exponent on frequency and the relaxation parameters was investigated. In order to carry out numerical calculations, a model for a single relaxation process was employed. For example, from the measured attenuation coefficients of a 25% aqueous solution of glucose in the frequency range 20 to 700 MHz, the relaxation time and the parameter were determined.