【表面と真空 (Vacuum and Surface Science)】は，2018年4月の日本表面科学会と日本真空学会の合併により設立された公益社団法人 日本表面真空学会が出版する学術論文誌です。設立に先立つ2018年1月に創刊された新しいジャーナルになります。前身誌は日本真空学会の【Journal of the Vacuum Society of Japan】と日本表面科学会の【表面科学】になり，双方の記事種を踏襲し，その上で新たな分野への展開を目指しています。巻号は，歴史のより長い【Journal of the Vacuum Society of Japan】の巻数を引き継ぎ，第61巻からの創刊となります。
Electret or permanent electrical charge is used as a part of mechano-electric energy conversion system for vibrational energy harvesting device. Microscopic capacitors are produced by silicon micromachining or MEMS (microelectromechanical systems) fabrication process, and the surfaces are turned into impurity-rich silicon oxide, which is later processed to make an electret by displacing the impurity ions by the same mechanism as the anodic bonding. The built-in potential of the electret is used to produce electrical current through the electrostatic induction when the movable electrode is periodically shaken by the external vibrations. In this article, the fabrication processes for the electret as well as the MEMS vibrational energy harvester are discussed. The fundamental characteristics of the energy harvesters are reported, along with a demonstration result as an autonomous powerpack for an IoT (internet-of-things) type wireless sensor node.
Soil is defined as a mixture of weathering products of rocks (sand, silt, and clay) and humus (or soil organic matter) derived from plant or animal. World soils are divided into 12 groups and their distribution is not uniform. Soil degradation includes soil acidification in humid region, salinization in arid regions, and loss of soil organic matter in both regions. Minimum tillage or optimized fallow systems can minimize loss of soil organic matter and improve soil fertility. Understanding of complex soil system is required for food supply and human survival.
Digital Annealer developed by Fujitsu is a new architecture to solve “combinatorial optimization problems” at high speed with digital circuit inspired by quantum phenomena. The features are stable operation with digital circuit at room temperature, easy miniaturization, and easy mapping more complex problems with a fully-connected architecture. The Digital Annealer is easy to apply actual problems and contributes to customers in a wide range of businesses, including drug discovery, chemistry, manufacturing, transportation, finance, and logistics. In this article, we explain the fundamental of the Digital Annealer including the speedup technique. We also introduce an application to the material development using the Digital Annealer. The Digital Annealer is used to evaluate the structural similarity of the flavor molecules. We found that the molecules with high structural similarity show a similar flavor. We also extracted the common substructure of molecules having the similar flavor, which is considered to be the key structure of the flavor.
The fundamentals for understanding metal corrosion in aqueous solutions are first explained in terms of thermodynamics and kinetics of electrochemical corrosion reactions, illustrating the validity of a local cell model for the uniform corrosion behavior of iron and stainless steels. Then, the passivation process of stainless steels and the important properties of their passive films are described. Finally, recent studies on the pit initiation mechanism at sulfide inclusions of stainless steels are introduced, which provides a valuable information to develop a next-generation green stainless steel.
Recent progress of the microfabricated field emitter array (FEA) and the planar type electron source is overviewed. The volcano-structured double-gate FEA is promising for obtaining matrix driven and focused electron beams. The beam half angle less than one degree was achieved by using this structure. High current density of more than 25 A/cm2 is also achieved by using nickel-based alloy as an emitter material. A major breakthrough in the field of planar type electron sources is a using graphene as a top electrode in Metal/Oxide/Semiconductor type emitter, which is owing to the development of the direct deposition technique of graphene on insulating material. The emission efficiency of more than 30% is achieved. The graphene/oxide/semiconductor type electron source can emit electrons not only in poor vacuum but also in liquid. This unique feature enables new application, such as hydrogen production using non-electrolyte aqueous solution by injecting low energy electrons.