In Situ Reversible Ionic Control for Nonvolatile Magnetic Phases in a Donor/Acceptor Metal‐Organic Framework

Reversible magnetic control by electrical means, which is highly desired from the viewpoint of fundamentals and technological applications such as data storage devices, has been a challenging topic. In this study, the authors demonstrate in situ magnetic phase switching between the ferrimagnetic and paramagnetic states of an electron‐donor/‐acceptor metal‐organic framework (D/A‐MOF) using band‐filling control mediated by the Li⁺‐ion migration that accompanies redox reactions, i.e., “magneto‐ionic control”. By taking advantage of the rechargeability of lithium‐ion battery systems, in which Li⁺‐ions and electrons are simultaneously inserted into/extracted from a cathode material, the reversible control of nonvolatile magnetic phases in a D/A‐MOF has been achieved. This result demonstrates that the combination of a redox‐active MOF with porous flexibility and ion‐migration capability enables the creation of new pathways toward magneto‐electric coupling devices in the field of ionics.     

An improved Feynman-α analysis with a moving–bunching technique

The bunching technique has been widely utilized in Feynman-α neutron correlation analysis to synthesize neutron counts within longer gate widths by bunching time-sequence neutron counts stored in multichannel scaler channels. An alternative technique referred to as “moving–bunching technique” was proposed to reduce a statistical scatter of variance-to-mean ratio of neutron counts. The conventional bunching technique has no overlap of adjacent bunches, while the present technique makes adjacent bunches overlap as long as possible similarly to the moving average technique. A Feynman-α experiment was performed in the UTR-KINKI, to confirm the advantage of the proposed bunching technique. When a neutron detector was placed far from the core, a Feynman-α analysis with the conventional bunching technique led to a scattered variance-to-mean ratio from which the prompt-neutron decay constant was never determinable. However, another analysis with the proposed technique remarkably reduced the above scatter and enabled the determination of the decay constant. For a neutron detector close to the core, the proposed technique also reduced statistical error of the decay constant.     

Aerobic oxidation of alcohols over novel crystalline MoVO oxide

Novel crystalline MoVO oxide was employed as the catalyst in the aerobic oxidation of alcohols to the corresponding carbonyl compounds. Reactions were mainly conducted at 353 K in pure oxygen or air (1 atm). The selectivities for benzaldehydes were more than 95% in all cases. The conversions of benzyl alcohols varied from 10% to 99% depending on the substituent. A Hammett plot gave a moderate ρ-value of −0.249 (r² = 0.98), suggesting that the reaction processes may involve hydride abstraction. The oxidation of primary alkanols afforded aldehydes, and secondary alcohols were mainly dehydrated to olefins. It was found that the conversion of linear alkanols decreased with the length of alkanols. Kinetic analysis showed that catalytic reaction rate was first-order dependent on the concentrations of substrate and of catalyst. The apparent activation energy was estimated to be 45.7 kJ mol⁻¹. Catalytic reactions took place on the 6- or 7-member rings on the a–b basal plane, where highly dense unsaturated metal cation centers and oxygen anion might serve as catalytic active sites.     

All-plastic organic dye laser with distributed feedback resonator structure

We demonstrated an all-plastic waveguide organic dye laser with distributed feedback (DFB) resonator. We fabricated DFB structure on a surface of SU-8 2002 photoresist polymer using the interference of two beams of a frequency-tripled Nd:YAG pulse laser at 355 nm. The typical grating pitch of fabricated DFB structure was 190, 380 and 570 nm, corresponding to the number of mode m, and each corresponding grating amplitude was ca. 1, 4-5, and 25 nm, respectively. Shallow amplitude of 1 or 4-5 nm is ascribed to the wide incidence angle of the interference beams. Threshold of lasing for m = 3 is lower than that for m = 1 or m = 2 depending on the emission wavelength. DFB structure with the smaller amplitude of gratings at m = 1 and 2 is required for the higher threshold of laser emission. By controlling the grating pitch with nanometer scale, we can tune the wavelength of laser emission with 40 to 60 nm tunability. Effective energy transfer via nonradiative Förster transfer mechanism assists in lowering the threshold of laser emission.     

Fast and precise positioning using sequential adaptive feedforward compensation for disturbance

This paper presents a performance improvement for trajectory tracking for fast‐response and high‐precision positioning using sequential adaptive compensation for disturbances. A mathematical disturbance model formulated and parametrized by an iterative learning process can estimate the actual disturbance, and the model can be sequentially adapted using the recursive least squares method so that it shows adaptivity to disturbance variations. The proposed positioning control approach involving disturbance modeling and compensation has been verified by experiments using a linear motor‐driven table system. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 184(4): 52–63, 2013; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.22280     

Chemical solution processing and properties of tungsten bronze (ba,la)nb2o6 thin films

Abstract

Highly oriented (Ba,La)Nb₂O₆ thin films have been synthesized by a chemical solution deposition method. A homogeneous and stable (Ba_0.75La_0.167)Nb₂O₆ (BLN) precursor solution was prepared by controlling the reaction of metal alkoxides. BLN precursor films crystallized in the tetragonal tungsten bronze phase at 700°C. BLN thin films on MgO(100) and Pt(100)/MgO(100) substrates showed the prominent c-axis preferred orientation. BLN thin films on Pt(100)/MgO(100) exhibited the diffuse phase transition depending upon the frequency.     

Transparent biosensor with micro channel array for optical and electrophysiological detection of luciferin–luciferase reaction

This paper describes a transparent biosensor that was designed to detect both the optical and electrophysiological signals of the luciferin–luciferase reaction. By using microelectromechanical system (MEMS) technologies, we have studied and developed a ‘Micro Channel Array’ (MCA) integrated with suction holes and electrodes as planar patch‐clamp biosensors. A transparent biosensor was developed as an advanced MCA. The developed transparent biosensor employs an SU‐8‐based MCA structure for simultaneous multipoint sensing of optical and electrophysiological signals. In this study, we tested the newly developed biosensor using the mPer1‐luc slice culture, which has circadian rhythms and is a typical example of cells in which a luciferin–luciferase reaction occurs. We could measure the optical and electrophysiological signals of the mPer1‐luc slice culture. Here we describe the experimental results of this study, and describe the design and fabrication of the transparent biosensor with MCA. Copyright © 2007 Institute of Electrical Engineers of Japan© 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Tracking the Oxygen Status in the Cell Nucleus with a Hoechst‐Tagged Phosphorescent Ruthenium Complex

Molecular oxygen in living cells is distributed and consumed inhomogeneously, depending on the activity of each organelle. Therefore, tractable methods that can be used to monitor the oxygen status in each organelle are needed to understand cellular function. Here we report the design of a new oxygen‐sensing probe for use in the cell nucleus. We prepared “Ru‐Hoechsts”, each consisting of a phosphorescent ruthenium complex linked to a Hoechst 33258 moiety, and characterized their properties as oxygen sensors. The Hoechst unit shows strong DNA‐binding properties in the nucleus, and the ruthenium complex shows oxygen‐dependent phosphorescence. Thus, Ru‐Hoechsts accumulated in the cell nucleus and showed oxygen‐dependent signals that could be monitored. Of the Ru‐Hoechsts prepared in this study, Ru‐Hoechst b , in which the ruthenium complex and the Hoechst unit were linked through a hexyl chain, showed the most suitable properties for monitoring the oxygen status. Ru‐Hoechsts are probes with high potential for visualizing oxygen fluctuations in the nucleus.     

Macromolecular recognition by cyclodextrins. Interaction of cyclodextrins with poly(N-acryloyl-amino acids)

The interactions of cyclodextrins (CDs) with poly(N-acryloyl-amino acids) (pAXaa) were investigated by ¹H NMR and two dimensional nuclear Overhauser effect spectroscopy (2D NOESY) to elucidate the effect of attachment of amino acid residues to the polymer chain. Using the ¹H NMR data measured at varying pAXaa concentrations, apparent association constants (K) were roughly estimated for the CDs/pAXaa systems. These apparent K values indicated that α-CD interacted with poly(N-acryloylphenylalanine) and with poly(N-acryloyltyrosine) and β-CD and γ-CD interacted with poly(N-acryloyltryptophan). Comparison of these apparent K values with those for the model compounds, i.e., amino acid sodium salts, revealed that the effect of attachment of amino acid residues to the polymer chain was stronger for a smaller amino acid residue.     

The use of change detection as a method of objectively evaluating labels

This study introduces the use of change detection, a technique used in cognitive psychology to measure attentional scan paths, as a way to objectively evaluate the prominence of varied label elements. There are two major objectives related to this work: (a) to develop change detection software and methodology for label use; and (b) to compare the relative prominence of different label elements on a beverage container. Six label elements (i.e. treatments) were analysed, namely: the manufacturer name, the product name and a warning dot with text in three colours. Study results suggest that experimental set‐up can significantly impact results, specifically the position of the change (p = 0.0078) and the order of appearance (p = 0.069). This is not only important from an experimental design perspective, but also could lead to insights regarding the attentive behaviours of people as they purchase, select and use products. With regard to the elements of the labels tested, we identified a significant difference on time to detect a change (p < 0.0001). Time required for the manufacturer's name, Asahi Breweries, was significantly longer than for any of the other label elements (p < 0.0001). Pairwise comparisons indicated that for the warning dot, red text was located marginally faster than the warning printed in black (p = 0.0566). Change detection offers the promise to objectively evaluate the relative prominence of a label (or a scene) but is quicker and cheaper than other methods, such as eye tracking, that are currently utilized for this purpose. Copyright © 2010 John Wiley & Sons, Ltd.