An organic nonvolatile memory using space charge polarization of a gate dielectric

We realize a nonvolatile and rewritable memory effect in an organic field-effect transistor (OFET) structure using polymethylmethacryrate (PMMA) dispersed with 10-methyl-9-phenylacridinium perchlorate (MPA⁺ClO₄⁻) as a gate dielectric. Applying a voltage between a top source-drain electrode and a bottom gate electrode induces electrophoresis of two ions of MPA⁺ and ClO₄⁻ towards the corresponding electrodes in the memory devices. The drain currents of the memory devices markedly increase from 10^− 9 A to 10^− 2 A under no gate voltage condition due to the strong space charge polarization effect. Our memory devices have excellent electrical bistability and retention characteristics, i.e. the memory on/off ratio reached 10⁷ and the drain current maintained 40% of the initial value after 10⁴ s.     

Simple fabrication of hollow poly-lactic acid microspheres using uniform microbubbles as templates

A simple method was developed that uses microbubbles as templates to fabricate hollow microspheres covered with a biodegradable polymer. By stably keeping microbubbles with the diameter of about 2 µm inside a solvent droplet dissolving a biodegradable polymer and then slowly drying the solvent, hollow microspheres that had an average inner diameter of about 2 µm and a shell thickness of about 500 nm were obtained. This simple method was successfully used to easily fabricate uniform hollow microspheres covered with poly-lactic acid (PLA) by using uniform 2-µm-diameter bubbles as templates.     

Establishment of Intestinal Organoid from Rousettus leschenaultii and the Susceptibility to Bat-Associated Viruses,SARS-CoV-2 and Pteropine Orthoreovirus

Various pathogens, such as Ebola virus, Marburg virus, Nipah virus, Hendra virus, Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV), Middle East Respiratory Syndrome Coronavirus (MERS-CoV), and SARS-CoV-2, are threatening human health worldwide. The natural hosts of these pathogens are thought to be bats. The rousette bat, a megabat, is thought to be a natural reservoir of filoviruses, including Ebola and Marburg viruses. Additionally, the rousette bat showed a transient infection in the experimental inoculation of SARS-CoV-2. In the current study, we established and characterized intestinal organoids from Leschenault’s rousette, Rousettus leschenaultii. The established organoids successfully recapitulated the characteristics of intestinal epithelial structure and morphology, and the appropriate supplements necessary for long-term stable culture were identified. The organoid showed susceptibility to Pteropine orthoreovirus (PRV) but not to SARS-CoV-2 in experimental inoculation. This is the first report of the establishment of an expandable organoid culture system of the rousette bat intestinal organoid and its sensitivity to bat-associated viruses, PRV and SARS-CoV-2. This organoid is a useful tool for the elucidation of tolerance mechanisms of the emerging rousette bat-associated viruses such as Ebola and Marburg virus.     

Optimization of Electric Power Leveling Systems by Taper‐Off‐Reflectance Particle Swarm Optimization

It has become desirable to develop energy control technologies for environmental issues such as global warming and exhaustion of fossil fuel. Power fluctuations in large power consumer facilities may cause instability of electric power systems and increase the cost of the electric power facilities and electricity charges. Developing electric power leveling systems (EPLS) to compensate power fluctuations is necessary for future electric power systems. EPLS with an SMES has been proposed as one countermeasure for use in electric power quality improvement. SMES is superior to other energy storage devices in response and storage efficiency. The authors have proposed EPLS based on fuzzy control with SMES. For this practical implementation, optimizing the control gain and SMES capacity is an important issue. This paper proposes a new method for optimization of the EPLS. The proposed algorithm is a novel particle swarm optimization based on taper‐off reflectance (TRPSO). The proposed TRPSO optimizes the design variables of the EPLS efficiently and effectively. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 186(3): 10–18, 2014; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.22472     

Windowless solid hydrogen target

A windowless solid hydrogen target has been successfully developed for RI-beam-induced nuclear reactions in the RIKEN RI Beam Facility. Hydrogen crystals of high quality were grown reproducibly in a cell bored in a 10 mm thick pure copper plate which was in direct contact with a liquid helium reservoir. Normal hydrogen gas was crystallized directly on the cell wall between 4.7 and 7.3 K. The diameter of the crystal was 25 mm and the thickness was chosen to be either 5 or 10 mm. After crystallization, sidewalls of the cell were separated from both the crystal and cell plate, and removed to a remote position inside a cryostat. Thus, the crystal was self-supported in the cell without any extra material in its neighborhood. No damage was observed in the separating process. The observed hydrogen pressure indicated the crystal temperature of 4.3 K, when the liquid helium reservoir was at 4.2 K, in agreement with the temperature estimated from the heat balance in the crystal. It shows that we can put the crystal temperature close to the reservoir temperature, though we could not confirm the crystal temperature when the reservoir temperature was reduced to 3 K. Hydrogen sublimation rate was calculated from the vapor pressure and pumping condition. The sublimation loss is negligibly small if the crystal is held at 3 K.     

Roles of the Ser146, Tyr159, and Lys163 residues in the catalytic action of 7alpha-hydroxysteroid dehydrogenase from Escherichia coli

Adhesion to collagens by most cell types is mediated by the integrins alpha1beta1 and alpha2beta1. Both integrin alpha subunits belong to a group which is characterized by the presence of an I domain in the N-terminal half of the molecule, and this domain has been implicated in the ligand recognition. Since purified alpha1beta1 and alpha2beta1 differ in their binding to collagens I and IV and recognize different sites within the major cell binding domain of collagen IV, we investigated the potential role of the alpha1 and alpha2 I domains in specific collagen adhesion. We find that introducing the alpha2 I domain into alpha1 results in surface expression of a functional collagen receptor. The adhesion mediated by this chimeric receptor (alpha1-2-1beta1) is similar to the adhesion profile conferred by alpha2beta1, not alpha1beta1. The presence of alpha2 or alpha1-2-1 results in preferential binding to collagen I, whereas alpha1 expressing cells bind better to collagen IV. In addition, alpha1 containing cells bind to low amounts of a tryptic fragment of collagen IV, whereas alpha2 or alpha1-2-1 bearing cells adhere only to high concentrations of this substrate. We also find that collagen adhesion of NIH-3T3 mediated by alpha2beta1 or alpha1-2-1beta1, but not by alpha1, requires the presence of Mn2+ ions. This ion requirement was not found in CHO cells, implicating the I domain in cell type-specific activation of integrins.     

Effects of boric acid on hydrogen evolution and internal stress in films deposited from a nickel sulfamate bath

The effects of boric acid additions on the pH close to the electrode surface, on the hydrogen evolution reaction and on the internal stress in the plated films were studied for the high speed electroplating of nickel from a nickel sulfamate bath at a current density close to the nickel ion limiting current density. The study was carried out at 50 °C and pH 4.0 using a 1.55 M nickel sulfamate plating bath containing boric acid at concentrations ranging from 0 to 0.81 mol L^–1. The variation of the internal strain in the plated nickel films was determined in situ using a resistance wire-type strain gauge fitted to the reverse side of the copper electrode substrate. The solution pH at a distance of 0.1 mm from the depositing nickel film was measured in situ using a miniature pH sensor assembly consisting of a thin wire-type antimony electrode and a Ag/AgCl/sat. KCl electrode housed in a thin Luggin capillary. The addition of boric acid was shown to effectively suppress the hydrogen evolution reaction at nickel electrodeposition rates (18.0 A dm^–2) close to the limiting current density (~20 A dm^–2). Consequently, the solution pH adjacent to the plating metal surface was maintained at a value close to that in the bulk solution and the development of high internal stresses in the deposited nickel films was avoided.