[en] Size-controlled gold nanoparticles (AuNPs) covered with DNA are synthesized by using a pulse driven gas-liquid interfacial discharge plasma (GLIDP) to reduce an aqueous solution of chloroauric acid trihydrate with DNA. The size and the assembly of the AuNPs are found to be easily controlled by changing the DNA concentration in the aqueous solution. The synthesized AuNP-DNA conjugates are forced to be encapsulated into double-walled carbon nanotubes (DWNTs) by superimposing a positive DC voltage on the pulse voltage. The AuNP-DNA-conjugate encapsulated DWNTs can be utilized in drug delivery systems when DNA is used as a drug molecule.

[en] Atmospheric pressure plasma (APP) technology, enabling to convert air molecules into multi-functional reactive oxygen and nitrogen species (RONS), has been of great interest and extensively investigated. In particular, air APP devices, working only with air and electricity, can potentially allow for ubiquitous supply of RONS, which can be applied in a wide range of fields such as medical, agricultural, environmental, and biomaterial fields [1-4]. Recently, we have developed a new composite air APP device consisting low and high temperature plasma reactors, enabling to supply RONS [dinitrogen pentoxide (N₂O₅), ozone (O₃), nitric oxides (NO_x), ...] with fine control and good reproducibility [5]. In addition, the APP device can utilize room air and renewable energy sources, such as a solar cell, and thus can realize sustainable and ubiquitous RONS supply. Among the RONS synthesized by the air APP device, N₂O₅ is well known as a powerful oxidizing and nitrating agent and can potentially be bioactive. Since the air APP devices can easily supply N₂O₅ to biomaterials (e.g., amiNO_xacid, protein, cells, virus, bacteria, …), we are exploring the inactivation effects of N₂O₅ exposure on pathogen and virus, modification of amiNO_xacid, and activation effects of plant immunity by the APP synthesized N₂O₅gas (APP-N₂O_5gas). First, we have investigated the inactivation effects on C. gloeosporioides (strawberry pathogen) and Qβ phage (RNA virus). The APP-N₂O₅ exposure significantly increased the inactivation effect, which was not only due to pH decrease by HNO_xtransfer into the droplet from N₂O₅. This indicates that N₂O_5ag, [NO₂⁺][NO₃^-]_ag, or NO₂⁺_ag may contribute to the inactivation [1]. Second, we conducted experiments on the modification of amiNO_xacids such as tyrosine by APP-N₂O₅. Tyrosine solution was treated by N₂O_5gas together with several reactive species such as O or NO_x, and it is found that dopachrome and nitrotyrosine were generated by the modification of tyrosine [5]. Interestingly, dopachrome generation rate in N₂O_5gas with excess O was most high, and the dopachrome generation was correlated with O density. Third, activation effects of plant immunity were found in pathogen inoculation test using Arabidopsis thaliana, exposed to APP-N₂O_5gas [6]. Gene expression analysis with RNA-seq and qRT-PCR showed that the N₂O_5gas exposure activated the signaling pathways for jasmonic acid (JA) and ethylene (ET), which are important phytohormones for plant immunity. These results indicate that N₂O_5gas can be used as a plant activator and also indicates that those N₂O_5gas effects were pronounced when the plants were placed in high humidity conditions. In the presentation, the details of the various biomaterial APP processes and APP-N₂O_5gas reaction pathway in the gas and liquid phase will be discussed.

[en] Due to the unique properties of ionic liquids such as their extremely low vapor pressure and high heat capacity, we succeed in creating the reactive gas (plasmas)--liquid (ionic liquids) interfacial field under a low gas pressure condition, where the plasma ion behavior can be controlled. The effects of the plasma ion irradiation on the liquid medium are quantitatively revealed for the first time. In connection with the plasma ion irradiation, the potential structure and optical emission properties of the gas-liquid interfacial plasma are investigated by changing a polarity of the electrode in the liquid to evaluate the plasma-liquid interactions. These results would contribute to synthesizing the metal nanoparticles with carbon nanotubes as a template in the ionic liquid. It is found that the high density, mono-dispersed, and isolated metal nanoparticles are synthesized between or inside the carbon nanotubes by controlling the gas-liquid interfacial plasmas. Furthermore, we can form novel nano-bio composite materials, such as DNA encapsulated carbon nanotubes using the plasma ion irradiation method in an electrolyte plasma with DNA, and demonstrate modifications of the electrical properties of the carbon nanotubes depending on the kinds of encapsulated DNA for the first time.

[en] The effects of ion flow velocity shears parallel and perpendicular to the magnetic-field lines, which are precisely controlled by a segmented electrode, are investigated in open-ended magnetized plasmas. The perpendicular flow velocity shears are demonstrated to suppress drift-wave, flute, and ion-cyclotron instabilities. On the other hand, parallel flow velocity shears are observed to destabilize D'Angelo mode, drift-wave, and ion-cyclotron instabilities depending on the sign of the parallel shear. The combined effects of the parallel and perpendicular flow shears will be important for controlling instabilities in magnetized plasmas. (author)

[en] Present status of radiographic CT diagnosis in diseases of the salivary gland, especially tumor of the parotid gland was surveyed. Although having its limitation, this method could be very useful for comprehensive diagnosis in combination with other methods. Particularly, it seemed possible for obtained many CT images to reveal a three-dimensional structure of tumor. (Ueda, J.)

[en] The traditional Q machine has been modified in accordance with the evolution of experimental methodologies ranging from modern plasma physics to extreme nanoscience. A special emphasis is placed on physics of sheared-flow related electron-temperature-gradient modes and nano-quantum physics or electronics based on fullerene and carbon nanotubes.

[en] Plasma potential formation is investigated in a fully ionized collisionless plasma flow in the presence of an electron cyclotron resonance (ECR) point under simple mirror configurations of magnetic field. When ECR takes place at the magnetic-well bottom, a potential structure is observed to consist of a negative potential depression around the ECR point and a subsequent positive potential peak. This potential structure gradually collapses in the timescale determined by the ion-flow speed. In the case of a converging magnetic field, such a potential structure is observed to persist in the steady state, when ECR point is located in the region of good magnetic-field curvature. However, this structure is formed only transiently when the ECR point is located in the region of bad magnetic-field curvature. When ECR takes place in a diverging magnetic field, on the other hand, there appears a strong potential drop along the field lines, which results from a field -aligned electron acceleration, being accompanied by an effective ion acceleration. (Author)

[en] The external and independent control of parallel and perpendicular flow shears in collisionless magnetized plasmas are realized using two newly-developed plasma sources. The ion flow velocity shears parallel to the magnetic-field lines are then observed to destabilize not only the D'Angelo mode but also the drift-wave instability depending on the sign of the parallel shear in the absence of field-aligned electron drift flow in laboratory experiments. On the other hand, perpendicular ion flow velocity shears are demonstrated to suppress the drift-wave and the ion-cyclotron instabilities, and furthermore, these suppressions are found to take place independently of the sign of the perpendicular shear. (author)

[en] The polarization reversal from a left-hand (LHPW) to a right-hand polarized wave (RHPW) and the resultant electron cyclotron damping of the LHPW are experimentally observed for the first time. Our experimental results indicate that the polarization reversal arises simultaneously with the conversion of the propagation angle of the wave, in which finite-plasma boundary conditions are considered to be inherent. (author)

[en] The significance of basic experiments on field-aligned plasma-potential structure formed by local electron cyclotron resonance (ECR) is claimed based on the historical development of the investigation on electric double layer and electrostatic potential confinement of open-ended fusion-oriented plasmas. In the presence of a single ECR point in simple mirror-type configurations of magnetic field, a potential dip (thermal barrier) appears around this point, being followed by a subsequent potential hump (plug potential) along a collisionless plasma flow. The observed phenomenon gives a clear-cut physics to the formation of field-aligned plug potential with thermal barrier, which is closely related to the double layer formation triggered by a negative dip. (author)