The design, fabrication and characterization testing of a high-performance micromechanical resonant electrostatic field sensor at low driving voltages is presented. Structures including sensing electrodes, shielding electrodes and suspension beam design are discussed. The electromechanical behavior around the resonant frequency is described by an equivalent electric circuit to predict the output characterization of the sensors. The device is fabricated by a surface micromachining process. With low driving voltages compared with other reported devices, the electrostatic field sensors (EFS) have a resolution of 200 V m−1, the best reported figure for a MEMS-based device used in ambient air at room temperature. A nonlinearity of 1.8% (end-point-straight-line) in a measurement range of 0–10 kV m−1 is achieved. We have also achieved an uncertainty of 4.62% for the measurement data.

A 98 d experiment was conducted to compare the growth performance, protein turnover and energy budget between green and white color morphs of the sea cucumber Apostichopus japonicus. During the experiment, sea cucumbers were fed a single natural diet of Sargassum thunbergii and a premixed artificial diet. Results showed that there was no significant interaction of diet, species or experimental time on growth performance and feed utilization of A. japonicus. Specific growth rate (SGR) of green sea cucumber was significantly higher than that of white sea cucumber. Green sea cucumber fed S. thunbergii exhibited much higher food conversion efficiency (FCE) and protein efficiency ratio (PER) compared to those on the artificial diet, indicating preferential absorption of S. thunbergii. There were also significant discrepancies in body wall production rate (BWPR), crude protein and ash content between green and white sea cucumber. The observed δ 15 N values gradually increased owing to the assimilation of the diets containing higher nitrogen stable isotope ratios. Green sea cucumber reflected and approached δ 15 N values of the experimental diets much more quickly and with shorter half-lives than white sea cucumber. The relatively constant metabolic contributions in intestine (71 to 78%) and body wall (46 to 52%) of sea cucumber indicated a stable bioenergetic distribution strategy of tissue. According to the time-based turnover model, the estimated fractionation (Δ 15 N) ranged from 2.37 to 3.30 ‰. The average formulas of energy allocation for green and white sea cucumber were: 100C = 7.8G + 53.1F + 6.2U + 32.8R, 100C = 6.3G + 57.9F + 8.9U + 27.0R, respectively. Taken together, our results suggest that white sea cucumber may have higher dietary quality requirements for growth and metabolism than green sea cucumber.KEY WORDS: Apostichopus japonicus · Growth · Nitrogen stable isotope · Protein turnover · Energy allocation OPEN PEN ACCESS CCESSA comparative study on growth, protein turnover and energy budget of green and white color morphs of sea cucumber Apostichopus japonicus (Selenka)

Conventional SPICE-like simulators are not adequate for the noise simulation of the chopper amplifier, which typically has no DC operating point. This paper discusses the noise properties of the chopper amplifier in both time domain and frequency domain and presents a method of simulating chopper amplifier noise behavior with the RF simulatorSpectreRF. The simulation results for a designed circuit are given. A comparison between the simulation and the calculation results shows effectiveness and efficiency of this method in dealing with chopper amplifier noise simulation.