Highly diverse communities of bacteria inhabiting soybean rhizospheres play pivotal roles in plant growth and crop production; however, little is known about the changes that occur in these communities during growth. We used both culture-dependent physiological profiling and culture independent DNA-based approaches to characterize the bacterial communities of the soybean rhizosphere during growth in the field. The physiological properties of the bacterial communities were analyzed by a community-level substrate utilization assay with BioLog Eco plates, and the composition of the communities was assessed by gene pyrosequencing. Higher metabolic capabilities were found in rhizosphere soil than in bulk soil during all stages of the BioLog assay. Pyrosequencing analysis revealed that differences between the bacterial communities of rhizosphere and bulk soils at the phylum level; i.e., Proteobacteria were increased, while Acidobacteria and Firmicutes were decreased in rhizosphere soil during growth. Analysis of operational taxonomic units showed that the bacterial communities of the rhizosphere changed significantly during growth, with a higher abundance of potential plant growth promoting rhizobacteria, including Bacillus, Bradyrhizobium, and Rhizobium, in a stage-specific manner. These findings demonstrated that rhizosphere bacterial communities were changed during soybean growth in the field.

Background: Multipoint observations of plasma waves are essential for separating spatial and temporal variations of a plasma turbulence. Miniaturization and high environmental (temperature and radiation) robustness are key requirements for scientific instrument design toward a sensor network consisting of palm-sized probes. With increasing these demands, a preamplifier for the 3-axis loop antenna of an electromagnetic sensor probe has been developed by using application-specific integrated circuit (ASIC) technology with a 0.25-μm complementary metal-oxide-semiconductor process. Findings: In the present study, a new temperature compensation method is proposed by using the open-loop gain of the ASIC preamplifier with a bandgap reference (BGR) circuit. Usually, the gain is characterized by the closed-loop gain, which is governed by the accuracy of the polysilicon resistances in a chip. The open-loop gain is characterized by the effective transconductance of the ASIC preamplifier, which often has a negative temperature dependence. The temperature dependence of the gain can be dramatically improved by using the temperature-compensated BGR circuit to cancel out the negative dependence of the transconductance. The temperature dependence of the gain was about −0.01 dB/ • C in the frequency range within the closed-loop bandwidth. On the other hand, the temperature dependence of the gain at 60 kHz operating with the open-loop gain was improved from −39 × 10 −3 to −2.6 × 10 −3 dB/ • C by using the temperature-compensated BGR circuit. Moreover, the radiation robustness for the total ionizing dose (TID) level is evaluated by irradiation with gamma rays from cobalt-60. The ASIC preamplifier is not sensitive to TID effects when a thin gate oxide is used. The ASIC preamplifier showed a high radiation tolerance to at least a total ionizing dose level of 400 krad(Si). Finally, the effectiveness of the ASIC preamplifier is evaluated on the basis of a virtual sounding rocket experiment using theoretical calculations of LF standard electromagnetic waves. Conclusions: Fundamental issues (miniaturization, low-noise performance, and high environmental robustness) are solved by the presented ASIC preamplifier. The success in developing the high robustness ASIC preamplifier leads to a future mission using a lot of palm-sized probes in space.

Abstract. Plasma waves are important observational targets for scientific missions investigating space plasma phenomena. Conventional fast Fourier transform (FFT)-based spectrum plasma wave receivers have the disadvantages of a large size and a narrow dynamic range. This paper proposes a new type of FFT-based spectrum plasma wave receiver that overcomes the disadvantages of conventional receivers. The receiver measures and calculates the whole spectrum by dividing the observation frequency range into three bands: bands 1, 2, and 3, which span 1 Hz to 1 kHz, 1 to 10 kHz, and 10 to 100 kHz, respectively. To reduce the size of the receiver, its analog section was realized using application-specific integrated circuit (ASIC) technology, and an ASIC chip was successfully developed. The dimensions of the analog circuits were 4.21 mm  ×  1.16 mm. To confirm the performance of the ASIC, a test system for the receiver was developed using the ASIC, an analog-to-digital converter, and a personal computer. The frequency resolutions for bands 1, 2, and 3 were 3.2, 32, and 320 Hz, respectively, and the average time resolution was 384 ms. These frequency and time resolutions are superior to those of conventional FFT-based receivers.

The electrochemical performance of ultrafine bubble (UFB) water , is reported herein. Recently, UFB has found applications in various fields, However, the detailed mechanism underlying the performance of UFB is not known, although the relevance of ions (proton and hydroxide ion) in solution has been discussed. Therefore, we investigated UFB through electrochemical measurements. First, we conducted a preliminary experiment in an ultrafine bubble generator (BUVITAS HYK-32-D, KYOWA KISETSU) and a measuring device for the concentration of microparticles (NANOSIGHT LM-10, Quantum Design, Inc.) . We also measured the electrical conductivity (S230, Mettler Toledo) and pH (LAQUA F-73, Horiba co. Ltd.) and found that the amount of flowing gas and the gas species did not influence the UFB concentration.

Background: Since conventional one-point observations of plasma phenomena in space cannot distinguish between time and spatial variations, the missions on the basis of multiple-point observations have become the trend. We propose a new system for multiple-point observation referred to as the monitor system for space electromagnetic environments (MSEE). Findings: The MSEE consists of small sensor probes that have a capability to measure electromagnetic waves and transfer received data to the central station through wireless communication. We developed the prototype model of the MSEE sensor probe. The sensor probe includes a plasma wave receiver, the microcontroller, the wireless communication module, and the battery in the 75-mm cubic housing. In addition, loop antennas, dipole antennas, and actuators that are used for expanding dipole antennas are attached on the housing. The whole mass of the sensor probe is 692 g, and the total power consumption is 462 mW. The sensor probe can work with both inner battery and external power supply. The maximum continuous operation time on battery power is more than 6 h. We verified the total performance for electric field measurements by inputting signal to preamplifier. In this test, we found that analog components had enough characteristics to measure electric fields, and the A/D conversion and the wireless transmission worked correctly. In the whole performance for electric fields, the sensor probe has equivalent noise level of −135 dBV=m= ffiffiffiffiffi Hz p .