The present invention provides a thermoplastic resin sheet having a thermoplastic resin expanded layer of which expansion ratio is in the range of 3 to 40 times, and cell wall density ratio is in the range of 2 to 20, said thermoplastic resin sheet having excellent thermal insulation property, and a container being formed from the thermoplastic resin sheet. The device may also include a numerical controlled oscillator to correct any Doppler-caused phase rotation associated with the received signal. The apparatus further comprises a pressurization source, preferably a positive displacement pump or connection to a positive displacement pump for pressurizing the sample.