Intercalation‐Induced Tunable Stimuli‐Responsive Color‐Change Properties of Crystalline Organic Layered Compound

Layered structures accommodate guest molecules and ions in the interlayer space through intercalation. Organic layered compounds, such as layered polymers, have both intercalation and dynamic properties. Here intercalation‐induced tunable temperature‐ and mechanical‐stress‐responsive color‐change properties of crystalline layered polydiacetylene (PDA) as an organic layered compound are reported. In general, organic materials with stimuli responsivity are developed by molecular design and synthesis. In the present work, intercalation of guest metal cations in the layered PDA directs tuning of the stimuli‐responsive color‐change properties, such as color, responsivity, and reversibility. Whereas PDA without intercalation of metal ions distinctly changes the color from blue to red at the threshold temperature, the PDA with intercalation of the divalent metal ions (PDA‐M²⁺) shows a variety of color‐change properties. The present study indicates that intercalation has versatile potentials for functionalization of organic layered compounds.     

Terahertz Frequency-Domain Spectroscopy of Low-Pressure Acetonitrile Gas by a Photomixing Terahertz Synthesizer Referenced to Dual Optical Frequency Combs

A terahertz (THz) frequency synthesizer based on photomixing of two near-infrared lasers with a sub-THz to THz frequency offset is a powerful tool for spectroscopy of polar gas molecules due to its broad spectral coverage; however, its frequency accuracy and resolution are relatively low. To tune the output frequency continuously and widely while maintaining its traceability to a frequency standard, we developed a photomixing THz synthesizer phase-locked to dual optical frequency combs (OFCs). While the phase-locking to dual OFCs ensured continuous tuning within a spectral range of 120 GHz, in addition to the traceability to the frequency standard, use of a broadband uni-traveling carrier photodiode for photomixing enabled the generation of CW-THz radiation within a frequency range from 0.2 to 1.5 THz. We demonstrated THz frequency-domain spectroscopy of gas-phase acetonitrile CH₃CN and its isotope CH₃ ¹³CN in the frequency range of 0.600–0.720 THz using this THz synthesizer. Their rotational transitions were assigned with a frequency accuracy of 8.42?×?10^?8 and a frequency resolution of 520 kHz. Furthermore, the concentration of the CH₃CN gas at 20 Pa was determined to be (5.41?±?0.05)?×?10¹⁴ molecules/cm³ by curve fitting analysis of the measured absorbance spectrum, and the mixture ratio of the mixed CH₃CN/CH₃ ¹³CN gas was determined to be 1:2.26 with a gas concentration of 10¹⁴–10¹⁵ molecules/cm³. The developed THz synthesizer is highly promising for high-precision THz-FDS of low-pressure molecular gases and will enable the qualitative and quantitative analyses of multiple gases.     

Numerical analysis of interaction between solute atom and extended dislocation using force multipoles

The interaction between a solute atom and an extended dislocation was investigated using a continuum approximation method with force multipoles. The dislocation core structure of extended dislocation was modeled with the Peierls-Nabarro model discretized with a number of infinitesimal Volterra dislocations. The interaction energy and force between a nickel solute atom and perfect and extended dislocation in copper were successfully calculated using the force multipoles. The results clearly show that the core structure of extended dislocation weakens the interaction with solute atoms. The interaction energy and force for extended dislocations are almost the half of those for perfect dislocations.     

Novel approach to recover copper ions using poly(ethylene imine) based layer-by-layer coatings on icosane particles

The low-density materials are developed for the wastewater treatment, the particles could be easily recovered when floating upon water surface and be recycling of a large fraction. Simultaneously, we selected the low melting point of material, which is possible to separate easily the compounds after usage. We chose icosane as a core material with layer-by-layer (LbL) films as an adsorbent for wastewater containing copper ions. The icosane particles were coated by poly(ethylene imine) (PEI) as positively charged layer and either poly(acrylic acid) (PAA) or poly(styrene sulfonate) as counterpart. Glutaraldehyde was introduced as a crosslinking agent to create multilayered shells with various active sites as scavenger. The copper adsorption abilities of PEI-PAA-coated particles were examined by inductively coupled plasma mass spectrometry. Interestingly, the adsorption amount of copper ions on PEI/PAA coated particles (16.5 mg) was optimized at 82 μg/L after 5 min of elution time, which shows a good potential of our material in the field of application. With the facile and consistent separation of the core and LbL coating, the thermal properties were revealed a stable melting temperature at around 38°C.     

Effect of medium condition change on green body density during casting and drying

The present study examined whether the optimum slurry conditions in which the green body with the highest packing fraction was fabricated were the same regardless of whether tape or slip casting methods were used. Additionally, we investigated the optimum slurry evaluation method to predict the packing fraction of each green body. Specifically, aqueous dense alumina slurries, whose particle dispersion state was changed by varying pH and the amount of dispersant additive, were prepared. After changing the pH, the optimum slurry conditions were achieved regardless of the casting method. The most suitable amount of additive dispersant differed due to the changing solution conditions during the casting and drying process; the medium of the slurry permeated into the plaster during slip casting and dried on the substrate during tape casting. Thus, in slip casting, non-adsorbed polymers could also be permeated. Hence, it is crucial for slurry evaluation to predict the packing fraction of the slip cast body. A sedimentation test, which involved particle condensation as well as casting, was valid for the green sheet. Conversely, it was experimentally shown that the constant pressure filtration test, which involved the permeation of the medium in addition to particle condensation, was suitable for slip casting.     

Synthesis of a Coumarin-Based PPARγ Fluorescence Probe for Competitive Binding Assay

Peroxisome proliferator-activated receptor γ (PPARγ) is a molecular target of metabolic syndrome and inflammatory disease. PPARγ is an important nuclear receptor and numerous PPARγ ligands were developed to date; thus, efficient assay methods are important. Here, we investigated the incorporation of 7-diethylamino coumarin into the PPARγ agonist rosiglitazone and used the compound in a binding assay for PPARγ. PPARγ-ligand-incorporated 7-methoxycoumarin, 1, showed weak fluorescence intensity in a previous report. We synthesized PPARγ-ligand-incorporating coumarin, 2, in this report, and it enhanced the fluorescence intensity. The PPARγ ligand 2 maintained the rosiglitazone activity. The obtained partial agonist 6 appeared to act through a novel mechanism. The fluorescence intensity of 2 and 6 increased by binding to the ligand binding domain (LBD) of PPARγ and the affinity of reported PPARγ ligands were evaluated using the probe.     

Investigation of PdCuSi metallic glass film for hysteresis-free and fast response capacitive MEMS hydrogen sensors

In this study, we investigated PdCuSi metallic glass (MG) as a sensing material for capacitive MEMS hydrogen sensors. We first confirmed by film analysis that the fabricated PdCuSi film was MG and that it had a trigonal prism cluster. The measured pressure-composition-temperature curve of PdCuSi MG exhibited no hysteresis during hydrogen absorption and desorption. The response time was found to become faster by two orders of magnitudes compared with that of Pd polycrystal. These properties were attributed to the trigonal prism clusters. Strain was evaluated in the low hydrogen concentration regime of 0.05 vol% to 4.0 vol%, and the strain of PdCuSi MG was found to follow Sieverts' law well, indicating that hydrogen is present in the MG in a diffuse state. The hydrogen-concentration dependence of a capacitive MEMS hydrogen sensor was measured and hysteresis-free characteristics were obtained, implying advantages in hydrogen leak detection applications.     

Chemical surface modification of aluminum oxide nanoparticles with graft copolymer of aluminum oxide and poly(isobutyl vinyl ether) mechanochemically synthesized in vacuum at low temperature

Chemical surface modification of aluminum oxide (AO) nanoparticles with graft copolymer of AO and poly(isobutyl vinyl ether) (PIBVE) (AO-graft-PIBVE) was carried out by ball milling of AO nanoparticles with IBVE in vacuum at low temperature. The AO-graft-PIBVE was evidenced by FT-IR and ¹H NMR spectra. The surface modified AO nanoparticles with mono-dispersed particle diameter exhibited structural blue color which was evidenced by photograph, optical spectroscopy (UV-Vis-NIR) and SEM image. The key atoms for the mechanochemical reactions were assigned by the net charge and the distribution of the HOMO and/or LUMO at each atom estimated by molecular orbital calculations. The reaction scheme is proposed; naked Al cations of AO (AO-Al⁺) were produced by ionic scission of aluminum-oxygen bond by ball milling and trapped at the surface of AO nanoparticles. The AO-Al⁺ reacted with IBVE, formed a novel bond between the Al-atom of AO-Al⁺ and the C-atom of IBVE, and resulted in AO-Al-IBVE⁺. The AO-Al-IBVE⁺ sequentially reacted to the C-atom of IBVE, and finally resulted in AO-graft-PIBVE. The PIBVE homopolymer was simultaneously produced by the ball milling of AO with IBVE in vacuum at low temperature. The key atoms for the reactions were assigned by the molecular orbital calculations.     

Control of Uninterrupted Switching Using a Virtual Synchronous Generator Between Stand‐Alone and Grid‐Connected Operation of a Distributed Generation System for Houses

The home applications of distributed generations facilities such as photovoltaic and gas engine cogeneration systems are growing and many distributed generations are connected to a grid by a DC/AC inverter. The DC/AC inverter is controlled by a phase‐locked loop (PLL) in order to be synchronized with the power system frequency. However, the control scheme of stand‐alone operation uses voltage control, and the PLL is unnecessary. Therefore, it is hard to realize uninterrupted change between stand‐alone and grid‐connected operation. In this paper, we propose a virtual synchronous generator control scheme in order to use the same control scheme in stand‐alone and grid‐connected operation. We carried out experiments to demonstrate the control characteristics.     

Robust Object Detection in Severe Imaging Conditions using Co-Occurrence Background Model

In this study, a spatial-dependent background model for detecting objects is used in severe imaging conditions. It is robust in the cases of sudden illumination fluctuation and burst motion background. More importantly, it is quite sensitive under the cases of underexposure, low-illumination, and narrow dynamic range, all of which are very common phenomenon using a surveillance camera. The background model maintains statistical models in the form of multiple pixel pairs with few parameters. Experiments using several challenging datasets (Heavy Fog, PETS-2001, AIST-INDOOR, and a real surveillance application) confirm the robust performance in various imaging conditions.