Preparation of polyacrylic dyes

Polyacrylic chloride was reacted with aminonaphthol sulfonic acid to give a polymeric intermediate, from which the corresponding dyestuff was prepared by coupling with an aromatic diazonium salt. The water-solubility of the polymeric azo dye was found to depend mainly on the number of sulfonic groups in the molecular chain, and the colouring of dye was comparatively rich in variety. A copolymer of acrylic chloride with methyl methacrylate was directly reacted with a dyestuff containing amino groups to give a polymeric dye. In the molecular chain of those polymeric dyes, the functional structure of the dyestuff was kept by its incorporation to the acrylic polymer chain.     

Theory of magnetically polarizable superconductors

Superconductors containing a magnetically polarizable medium under an applied magnetic field are discussed theoretically. It is shown that instead of the Pauli limiting field found by Chandrasekhar and Clogston for nonmagnetic superconductors, the maximum critical field is limited by the effect of the susceptibility X_f due to the polarizable medium and is greatly reduced as X_f increases, indicating the appearance of the first-order phase transition from the superconducting to the normal state. The magnetic behavior of the ferromagnet superconductor ErRh₄B₄ under applied fields is analyzed in terms of this idea.     

Comparative electron temperature measurements of Thomson scattering and electron cyclotron emission diagnostics in TCABR plasmas

We present the first simultaneous measurements of the Thomson scattering and electron cyclotron emission radiometer diagnostics performed at TCABR tokamak with Alfve?n wave heating. The Thomson scattering diagnostic is an upgraded version of the one previously installed at the ISTTOK tokamak, while the electron cyclotron emission radiometer employs a heterodyne sweeping radiometer. For purely Ohmic discharges, the electron temperature measurements from both diagnostics are in good agreement. Additional Alfve?n wave heating does not affect the capability of the Thomson scattering diagnostic to measure the instantaneous electron temperature, whereas measurements from the electron cyclotron emission radiometer become underestimates of the actual temperature values.     

Durable Ultraflexible Organic Photovoltaics with Novel Metal‐Oxide‐Free Cathode

Flexible and stretchable organic photovoltaics (OPVs) are promising as a power source for wearable devices with multifunctions ranging from sensing to locomotion. Achieving mechanical robustness and high power conversion efficiency for ultraflexible OPVs is essential for their successful application. However, it is challenging to simultaneously achieve these features by the difficulty to maintain stable performance under a microscale bending radius. Ultraflexible OPVs are proposed by employing a novel metal‐oxide‐free cathode that consists of a printed ultrathin metallic transparent electrode and an organic electron transport layer to achieve high electron‐collecting capabilities and mechanical robustness. In fact, the proposed ultraflexible OPV achieves a power conversion efficiency of 9.7% and durability with 74% efficiency retention after 500 cycles of deformation at 37% compression through buckling. The proposed approach can be applied to active layers with different morphologies, thus suggesting its universality and potential for high‐performance ultraflexible OPV devices.     

Integration of individual nanoscale structures into devices using dynamic nanostenciling

We succeeded in integrating individual, pre-existing nanostructures into functional devices using ultrahigh vacuum dynamic nanostenciling and show working devices based on single-walled carbon nanotubes, a benchmark nanomaterial, and porphyrin J-aggregates, a "soft" supramolecular nanomaterial. Nanostructures are first located via atomic force microscopy, while device elements are added step by step, with an achieved positional accuracy of 20 nm, using a shadow mask assembly that moves while being exposed to evaporated material. Electronic transport, potentiometry, and scanning Kelvin probe were used for control at any fabrication stage and were available in situ. Such complex fabrication/characterization capabilities, applicable repeatedly, reliably, and nondestructively, pave the way for dynamic nanostenciling instrumentation to establish itself as a viable tool for easy integration and prototyping of fragile nanostructures synthesized through a wide range of processes.     

Dynamical Instability of Coreless Vortices in F=2 Spinor Bose-Einstein Condensates

We theoretically investigate the low-lying excitation spectra of coreless vortex states in Bose-Einstein condensates (BECs) with F=2 hyperfine spin degrees of freedom. Here, we extend the previous work in F=1 spinor BEC. In addition to the dynamical instabilities in F=1 coreless vortex states, we find an another set of dynamical instabilities due to different hyperfine spin interaction. The calculation is carried out in the possible parameter space of the F=2 ⁸⁷Rb atom. This study assists interpretation of experimental data and presents a general characteristics of the dynamical instability of F=2 hyperfine spin system. whether the ground state of the spin interaction is in the cyclic or polar phase. Our study can encourages the experiments to examine our results.     

Electrochemical doping of pure single-walled carbon nanotubes used as supercapacitor electrodes

Pure single-walled carbon nanotubes (SWCNTs) with little bundling show an excellent capacitor performance attributable to the intrinsic nature of the SWCNTs, and possess unusual electrochemical properties characterized by a butterfly shaped cyclic voltammogram which differs from those for conventional activated carbon electrodes. Electrochemical doping in semi-conductor nanotubes occurred at the interface between the electrolyte and the SWCNT surface. In situ measurements showed a remarkable increase of electric conductivity with the polarization from the flat band potential. Because of the potential dependence, the capacitance of the SWCNT electrodes was higher at the higher charging potentials.     

Mechanisms of hydrogen sulfide removal with steel making slag

In the present study, we experimentally investigated the removal of hydrogen sulfide using steel-making slag (SMS) and clarified the mechanism of hydrogen sulfide removal with the SMS. The results proved that SMS is able to remove hydrogen sulfide dissolved in water, and the maximum removal amount of hydrogen sulfide per unit weight of the SMS for 8 days was estimated to be 37.5 mg S/g. The removal processes of hydrogen sulfide were not only adsorption onto the SMS, but oxidation and precipitation as sulfur. The chemical forms of sulfide adsorbed onto the SMS were estimated to be sulfur and manganese sulfide in the ratio of 81% and 19%, respectively. It is demonstrated here that the SMS is a promising material to remediate organically enriched coastal sediments in terms of removal of hydrogen sulfide. Furthermore, using SMS is expected to contribute to development of a recycling-oriented society.