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Sea cucumbers possess high-value and bioactive components that have been used for human food and pharmaceuticals in treating a wide number of ailments. Most of the sea cucumber products on the market are dehydrated due to the immediate autolysis that occurs upon removal of the sea cucumber from seawater. Rehydration of the dried products is necessary to obtain sea cucumbers with the highest water content. In this study, a rapid and non-invasive NMR and MRI method was introduced to analyze the rehydration process for dried sea cucumber. The spin-spin relaxation time (T 2 ) weighted NMR signal, obtained by a CPMG pulse sequence and processed by the chemometric method, was used to identify lightly dried and salted dried sea cucumber. The water uptake and distribution during the rehydration process was monitored by NMR 1 H T 2 . Structural changes were analyzed by MRI with T 1 and T 2 weighted imaging. The results indicated that the proper presoaking and rehydration time was 24 and 96 h, respectively, for lightly dried sea cucumber. Good linear correlation during the rehydration process was observed between the NMR parameters and texture profile analysis parameters including the hardness, chewiness, and rehydration ratio of lightly dried sea cucumbers. The NMR and MRI method has the potential to noninvasively analyze the rehydration process of dried sea cucumber.

The influence of liquid conductivity on electrical breakdown and hydrogen peroxide (H2O2) production in a nanosecond pulsed filamentary discharge generated in a water film plasma reactor was investigated over the liquid conductivity range from 0.01 mS cm−1 to 36 mS cm−1 by adding KCl to deionized (DI) water and using helium and argon as carrier gases. The plasma properties, including electron density, gas temperature, and plasma volume, the H2O2 production rate and energy yield, and the energy dissipation into the liquid were determined at different liquid conductivity. The energy dissipation into the bulk liquid increased as the liquid conductivity increased causing the total input energy to increase and resulting in a small decrease in H2O2 energy yield. In addition, the production rate of H2O2 did not change significantly with conductivity for the helium plasma but decreased about 13 percent in the argon plasma. The energy deposited in the helium plasma did not change with conductivity, thereby causing the H2O2 energy yield based upon energy in the plasma to be constant with conductivity. A model based upon the electrical circuit was used to predict the breakdown voltage for a range of liquid conductivity up to 36 mS cm−1. This model also showed that decreasing the rise time of the applied voltage (i.e. faster rising rate) significantly increased the breakdown voltage, and therefore improved the liquid conductivity tolerance of the plasma system allowing it to function at near sea-water conductivity.

A continuously flowing liquid film reactor driven by a variable nanosecond pulsed power supply, where plasma channels generated in argon propagate along the water film, was utilized to assess the effects of output voltage setting, pulse frequency, and gas/liquid flow rate on the generation of H 2 O 2 . Increasing the voltage significantly impacted the discharge current, resulting in hotter/denser plasma channels that increased the production rate of hydrogen peroxide but lowered the energy yield. Variation in pulse frequency and gas/liquid flow rates had little impact on electrical and plasma properties, however, the production of H 2 O 2 per pulse decreased with increasing pulse frequency and was shown to be linked to insufficient chemical and/or thermal dissipation of the gas phase between pulses. K E Y W O R D Sgas/liquid interface, hydrogen peroxide, nanosecond pulsed plasma, non-thermal plasma, plasma properties

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Optical emission spectroscopy was used to characterize an electrical discharge plasma reactor with a liquid H 2 O film contacting different carrier gases. The plasma gas temperatures for Ar, He, and 1% N 2 in Ar were 1000-1200 K and did not vary significantly with liquid flow rate. Increasing solution conductivity by adding KCl to deionized water in the Ar case lowered the temperature by 13%, increased the discharge power and lowered the H 2 O 2 formation rates. The temperature was highest in the case of air (2400 K), and in the case of Ar the temperature increased with the addition of O 2 . The temperatures for this reactor are comparable to previous studies with discharges in humid gases, while the effects of liquid conductivity were similar to those reported with direct discharge in the liquid phase.

The influence of carrier gas (argon and helium) on the properties of a nanosecond pulsed filamentary discharge propagating along the water surface in a water film plasma reactor, and the effects of plasma properties on the formation of hydrogen peroxide (H 2 O 2 ) are investigated. The plasma properties, including electron density, gas temperature, and plasma volume, and the hydrogen peroxide production rate and energy yield were measured and compared in both argon and helium discharges. The results show that helium plasma is more diffusive compared with the argon plasma, and it has lower electron density and gas temperature but larger volume. The production rates and energy yields of hydrogen peroxide are only slightly higher in the helium plasma although the electron density is much lower. A simple mathematical model with time-dependent fast radical and electron quenching in a small film surrounding the plasma core and with lumped reaction kinetics for H 2 O 2 formation and degradation suggests that the hydroxyl radical (•OH) concentration is approximately two times higher in the argon discharge, but the larger volume of the helium leads to about two times more total •OH in the helium with correspondingly higher energy yields. The experimental data and model imply that the H 2 O 2 energy yield may increase at lower power (or specific energy density) for both carrier gases.

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