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Simple hexagonal Coulomb crystals have been observed near a deformed plasma sheath boundary in a dusty plasma. It seems that particle rows, which are found in the direction perpendicular to an electrode in the Coulomb crystal, are formed due to not only Coulomb repulsive forces but also some attractive forces. In this study, experiments using the deformed sheath revealed that the rows were bent along the direction of electric fields and ion flows in a plasma. The result shows that sheath structures and shapes affect Coulomb crystal structures in dusty plasmas. In this paper, the formation of the particle rows are discussed, where balances of forces on particles in a dusty plasma are taken into account under the assumption that wake potentials related to ion flows exist in the sheath region.

As a means of increasing data capacity, the multilayer optical disc is a promising approach. Because the recording layers in multilayer optical discs must have a high transmittance, they are commonly made of transparent oxide films. Moreover, the recording layer must have sufficient long-term reliability for data archival. In this work, a recording material with high transmittance and long-term reliability for use in super-multilayer discs was investigated. This paper clarifies the recording mechanism of GeBi oxide material and proposes a suitable material design that satisfies the abovementioned characteristics. Furthermore, experimental results of recording on super-multilayer discs based on GeBi oxide recording material are presented.

Graphene’s inherent nonselectivity and strong atmospheric doping render most graphene-based sensors unsuitable for atmospheric applications in environmental monitoring of pollutants and breath detection of biomarkers for noninvasive medical diagnosis. Hence, demonstrations of graphene’s gas sensitivity are often in inert environments such as nitrogen, consequently of little practical relevance. Herein, target gas sensing at the graphene–activated carbon interface of a graphene-nanopored activated carbon molecular-sieve sensor obtained via the postlithographic pyrolysis of Novolac resin residues on graphene nanoribbons is shown to simultaneously induce ammonia selectivity and atmospheric passivation of graphene. Consequently, 500 parts per trillion (ppt) ammonia sensitivity in atmospheric air is achieved with a response time of ∼3 s. The similar graphene and a-C workfunctions ensure that the ambipolar and gas-adsorption-induced charge transfer characteristics of pristine graphene are retained. Harnessing the van der Waals bonding memory and electrically tunable charge-transfer characteristics of the adsorbed molecules on the graphene channel, a molecular identification technique (charge neutrality point disparity) is developed and demonstrated to be suitable even at parts per billion (ppb) gas concentrations. The selectivity and atmospheric passivation induced by the graphene–activated carbon interface enable atmospheric applications of graphene sensors in environmental monitoring and noninvasive medical diagnosis.