Wide‐Range‐Tunable p‐Type Conductivity of Transparent CuI1−xBrx Alloy

Transparent p‐type semiconductors with wide‐range tunability of the hole density are rare. Developing such materials is a challenge in the field of transparent electronics that utilize invisible electric circuits. In this paper, a CuI–CuBr alloy (CuI_1?xBr_x) is proposed as a hole‐density‐tunable p‐type transparent semiconductor that can be fabricated at room temperature. First‐principles calculations predict that the acceptor state originating from copper vacancies in CuBr is deeper than that in CuI, leading to the hypothesis that the hole density in CuI_1?xBr_x can be tuned over a wide range by varying x between 0 and 1. The experimental results support this hypothesis. The hole density in CuI_1?xBr_x polycrystalline alloy layers can be tuned by over three orders of magnitude (10¹⁷–10²⁰ cm^?3) by varying x. In other words, the p‐type conductivity of the CuI_1?xBr_x alloy shows metallic and semiconducting properties. Such alloy layers can be prepared at room temperature without sacrificing transparency. Furthermore, CuI_1?xBr_x forms transparent p–n diodes with n‐type amorphous In–Ga–Zn–O layers, and these diodes have satisfactory rectification performance. Therefore, CuI_1?xBr_x alloy is an excellent p‐type transparent semiconductor for which the p‐type conductivity can be tailored in a wide range.     

Development of assembly system with quick and low-cost installation

ABSTRACT

Cell production systems for assembly operations generally require tool changes using several hands and a customized work table. The initial setting and resetting of the assembly system are costly. We implemented a system comprising the use of only two hands and without the requirement of tool changers. In addition, multiple sensors are used to perform tasks robustly to avoid errors. The peg-in-hole task is performed robustly against errors without the precise positioning of objects. The objective is to develop a system that is lean and agile and can be set up quickly. We evaluate this system based on the task-board and assembly tasks during the assembly challenge in the industrial robotics category of the World Robot Summit 2018.     

Investigating effects of interactive signage–based stimulation for promoting behavior change

In recent years, many types of research and developments on behavior change have been conducted. The purpose of behavior change is to improve people's lifestyle pattern or to maintain the improvement for a long time with the aim to achieve a goal such as promoting health condition improvement. To achieve the foundation of a new lifestyle, it is necessary to recognize the daily life patterns of users and give triggers for behavior change to users in their daily life. To realize this, in our research, we develop an interactive signage which is able to identify and actively talk to the passing user and try to induce behavior change by sending visual and auditory stimulation. Then, we record users' reactions and upload them to the server. In this paper, we report the investigation result on users' reactions and feelings to the developed interactive signage. As a survey experiment, we set up four interactive signs on a floor of our university and asked 15 participants to carry a name tag with a Bluetooth Low Energy beacon during their daily life. Five kinds of tasks based on dialogue scenarios are posted to the approaching participants. Participants can respond to these tasks through a touchscreen. The period of the experiment was three weeks. To get the data in an ideal environment, during the first week, we asked all the participants to respond to the utterance from the interactive signage whenever they hear the voice message. During the next two weeks, participants were not asked to respond to the task definitely to get the data in the real environment. The result of the experiment showed that our proposed interactive signage could induce behavior change effectively. Based on the result of experiment, we updated our interactive signage system by adding response time (the time passed from showing contents until user respond), record function, and voice feedback function. Furthermore, to collect the data of response time that is considered as a part of users' reactions, we conducted an additional experiment with the same participants in previous experiment (except for one missing participant) for one week after updating the system. In the additional experiment, the participants were not asked to respond to the utterance definitely. As a result, it is shown that the behavior change by the proposed signage is still effectively induced. We also analyzed the relationship between the day passed and the response rate of each task type. The result shows that the number of ignorance of personal task and check task does not rise even as the time passes.     

Synthesis of 0.4Pb(Mg1/3Nb2/3)O3–0.3Pb(Mg1/2W1/2)O3–0.3PbTiO3 Ceramics by Metal Alkoxide Method, and Its Dielectric Properties

0.4Pb(Mg_1/3Nb_2/3)O₃–0.3Pb(Mg_1/2W_1/2)O₃–0.3PbTiO₃+ x MgO ( x = 0 to 0.04) were prepared by a metal alkoxide method. The percent of perovskite phase of the calcined powders increased with increased calcination temperatures. About 89% of perovskite phase was obtained at 1050°C. The dielectric constant of the pellets fired at 1100°C was increased by the addition of 10 wt% excess Mg(OC₂H₅)₂ and had a maximum value of 7532 at 1 kHz.     

Fabrication of UV range light guide plate

The light guide plate, as part of the backlight unit in a cellular phone or liquid crystal display, has evolved to meet market demands for low power consumption, high-luminance and high-quality displays. Along with the advance of the light guide plate, LEDs have undergone development as light source for light guide plates. Surpassing the limitations of LED emission in the visible light range, LEDs that emit UV light have been developed. In recent years, the UV light are used as a source of light of the air cleaner, and it is used as a source of light to activate the titanium oxide which is photocatalyst. But common UV light sources are either line or point light sources. We study surface illuminators that incorporate diffusers in the visible light range. Applying our existing technology, we constructed an unprecedented UV surface illuminator (surface light source) and measured it using a photocatalyst. The experiment results are presented in this report.     

Elevation of Chemosensitivity of Lung Adenocarcinoma A549 Spheroid Cells by Claudin-2 Knockdown through Activation of Glucose Transport and Inhibition of Nrf2 Signal

Claudin-2 (CLDN2), a tight junctional protein, is involved in the chemoresistance in a three-dimensional spheroid culture model of human lung adenocarcinoma A549 cells. However, the mechanism has not been fully clarified. We found that the knockdown of CLDN2 expression by siRNA in the spheroid reduces the expression of glucose transporters and metabolic enzymes. In a two-dimensional culture model, the expression of these proteins was increased by glucose deprivation or fasentin, an inhibitor of glucose transporter. In addition, the expression levels of nuclear factor erythroid 2-related factor 2 (Nrf2) and antioxidant enzymes including heme oxygenase-1, NAD(P)H:quinone oxidoreductase-1, and a glutamate–cysteine ligase modifier subunit were increased by fasentin. The fluorescence intensities of JC-1, a probe of mitochondrial membrane potential, and MitoROS 580, a probe of mitochondrial superoxide production, were increased by fasentin. These results suggest that mitochondrial production of reactive oxygen species is increased by glucose deficiency. The knockdown of CLDN2 enhanced the flux of 2-deoxy-2-[(7-nitro-2,1,3-benzoxadiazol-4-yl)amino]-D-glucose (2-NBDG), a fluorescent deoxyglucose derivative, in a transwell assay, and the accumulation of glucose and 2-NBDG in spheroid cells. The expression of Nrf2 was decreased by CLDN2 knockdown, which was inhibited by fasentin and sulforaphane, a typical Nrf2 activator, in spheroid cells. The sensitivity of spheroid cells to doxorubicin, an anthracycline antitumor antibiotic, was enhanced by CLDN2 knockdown, which was inhibited by fasentin and sulforaphane. We suggest that CLDN2 induces chemoresistance in spheroid cells mediated through the inhibition of glucose transport and activation of the Nrf2 signal.     

Organic–inorganic hybrid solar cells based on conducting polymer and SnO2 nanoparticles chemically modified with a fullerene derivative

Organic–inorganic hybrid solid solar cells were fabricated by using a conjugated polymer (MDMO-PPV) and SnO₂ nanoparticles chemically modified with C₆₀C(COOH)₂. The cell performance was improved by the chemical modification, suggesting that the modification with photoelectrochemically active organic materials is useful for establishing good electronic junction at the organic–inorganic interface. The short-circuit current density J_SC increased with increasing thickness of MDMO-PPV up to 40 nm, and then decreased gradually. This thickness dependence was explained by the fluorescence quenching of MDMO-PPV by Au electrode and the film resistance of MDMO-PPV.     

Simple purification and selective enrichment of metallic SWCNTs produced using the arc-discharge method

Purified single-walled carbon nanotubes (SWCNTs) were produced using the arc-discharge method with a combination of air oxidation and dispersion–centrifugation processes in a tetrahydrofuran solution containing an amine as a dispersant. Subsequently, SWCNT samples were analyzed using thermo gravimetric analysis, vis-near infrared absorption spectroscopy, scanning electron microscopy, and Raman spectroscopy. Results revealed that metallic SWCNTs were enriched in a supernatant through the dispersion–centrifugation process.     

Synthesis of polymer particles with specific lysozyme recognition sites by a molecular imprinting technique

To prepare silica beads covered with a lysozyme‐imprinted polymer layer, we polymerized acrylamide and acrylic acid or acrylamide and N,N‐dimethylaminopropylacrylamide with (NH₄)₂S₂O₈ in a phosphate buffer containing the lysozyme, surface‐modified silica beads, and crosslinkers; the result was the formation of a polymer layer with a lysozyme recognition site on the silica‐bead surface. By quantitative analysis of the supernatant of the solution containing the silica beads, we confirmed that modified silica beads, in contrast to unmodified silica beads, can selectively adsorb lysozymes. The process of binding and releasing the lysozyme to and from the modified silica beads can be repeated several times without degradation of the rebinding ability. A quartz‐crystal microbalance sensor fabricated with a molecularly imprinted polymer layer with a lysozyme recognition site was prepared. When a lysozyme aqueous solution was added to the solution in which the sensor was immersed, a high level of sensitivity and response was observed. High selectivity was also demonstrated by tests with other protein solutions. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3378–3387, 2001     

Effect of gas composition on metal surface cleaning using atmospheric pressure microwave plasma

A microwave excited atmospheric pressure plasma source was manufactured and a cleaning experiment involving a stainless steel plate contaminated with organic oil was conducted, while considering the radical density in the Ar, Ar-O₂, and Ar-H₂O plasma. The most notable cleaning effect was confirmed when the plasma contained water molecules. While the existence of a unique spatial distribution of OH radical was demonstrated, the relevance of the cleaning effect and radical density was confirmed. The radical density distribution was examined by numerical computation using the experimentally obtained plasma parameter.