Vapochromic films of pi-conjugated polymers based on coordination and desorption at hypervalent tin(iv)-fused azobenzene compounds

We report the synthesis and vapochromic behaviors of film materials consisting of hypervalent tin-containing π-conjugated polymers. We prepared copolymers with brominated tin-fused azobenzenes and modified fluorene having tetraethylene glycol as a side chain. The synthesized polymers showed good film-formability and high affinity with coordinating solvent molecules such as dimethyl sulfoxide (DMSO). In particular, we discovered distinct color changes from blue to purple when exposed to DMSO vapor. It was revealed that color changes should originate from reversible alteration of the coordination-number between five and six of hypervalent tin(IV) in the azobenzene compounds involved in the main-chain conjugation. Moreover, we also observed that binding constants between tin and coordinating solvents could be influenced by two substitutions on the tin atom and subsequently modulated responsivity of vapochromism in films by altering the type of substituent. Furthermore, the color-change behaviors can be estimated by quantum calculations with density functional theory. We demonstrate not only that hypervalent tin can work as a switching unit for modulating the electronic structures of π-conjugated polymers triggered by solvent coordination but also that vapochromic behaviors in films can be predicted by estimating the affinity between hypervalent tin and solvent molecules with theoretical calculations

Evaluation of Quality of Life in Japanese Normal Pregnant Women

To evaluate QOL changes during pregnancy in developed country, we analyzed 159 pregnant Japanese women (67 nulliparous and 92 multiparous) who had no complications during pregnancy. Subjects were asked to complete the Medical Outcomes Study Short Form (SF-36) every 4 weeks up to 24 weeks of gestation, and every 2 weeks from 24 weeks of gestation until delivery. Subscales that reflect "Physical functioning (p?0.001)", "Role-physical (p?0.001)" and "Bodily pain (p?0.001)" showed significant declines throughout the entire pregnancy. On the other hand, subscales that reflect "Vitality," "General health" and "Mental health" did not change substantially with gestational age. Furthermore, subscales that reflect "Physical functioning," "Role physical," "General health" showed no significant differences between nulliparous and multiparous women. Although subscales that reflect "Bodily pain," "Vitality," "Social functioning," "Role emotional" and "Mental health" showed significant differences between nulliparous and multiparous women, these subscales showed significant interactions. Our results suggest that pregnant women need support, regardless of the number of deliveries. Appropriate supports to pregnant women will be available to improve the birth rate in developed countries

Carbon impurities behavior and its impact on ion thermal confinement in high-ion-temperature deuterium discharges on the Large Helical Device

The behavior of carbon impurities in deuterium plasmas and its impact on thermal confinement were investigated in comparison with hydrogen plasmas in the Large Helical Device (LHD). Deuterium plasma experiments have been started in the LHD and high-ion-temperature plasmas with central ion temperature (T i) of 10 keV were successfully obtained. The thermal confinement improvement could be sustained for a longer time compared with hydrogen plasmas. An isotope effect was observed in the time evolution of the carbon density profiles. A transiently peaked profile was observed in the deuterium plasmas due to the smaller carbon convection velocity and diffusivity in the deuterium plasmas compared with the hydrogen plasmas. The peaked carbon density profile was strongly correlated to the ion thermal confinement improvement. The peaking of the carbon density profile will be one of the clues to clarify the unexplained mechanisms for the formations of ion internal transport barrier and impurity hole on LHD. These results could also lead to a better understanding of the isotope effect in the thermal confinement in torus plasma

Current Status of Large Helical Device and Its Prospect for Deuterium Experiment

Achievement of reactor relevant plasma condition in Helical type magnetic devices and exploration in its related plasma physics and fusion engineering are the aim of the Large Helical Device (LHD) project. In the recent experiments on LHD, we have achieved ion-temperature of 8.1 keV at 1 × 1019 m−3 by the optimization of wall conditioning using long pulse discharge by Ion Cyclotron Heating (ICH). The electron temperature of 10 keV at 1.6 × 1019 m−3 was also achieved by the optimization of Electron Cyclotron Heating (ECH). For further improvement in plasma performance, the upgrade of the Large Helical Device (LHD), including the deuterium experiment, is planned. In this paper, the recent achievements on LHD and the upgrade of LHD are described

Transport characteristics of deuterium and hydrogen plasmas with ion internal transport barrier in the Large Helical Device

A remarkable extension of the high-ion-temperature (high-Ti) regime was obtained in deuterium plasma experiments in the Large Helical Device. In order to clarify transport characteristics in the ion internal transport barrier (ITB) formation with an isotope effect, a dataset of pure deuterium (nD/ne  >  0.8) and pure hydrogen (nH/ne  >  0.8) plasmas in the high-Ti regime were analyzed, and two mechanisms of transport improvement were characterized. A significant reduction of ion heat transport in the core of both deuterium and hydrogen plasmas was observed, indicating ion ITB formation. The dependence of the ion heat diffusivity on temperature ratio (Te/Ti) and normalized Ti-gradient (R/LTi  =  −(R/Ti)(dTi/dr)) was investigated in the core region, in which gyrokinetic simulations with the GKV code predict the destabilization of ion temperature gradient (ITG) modes. The Te/Ti dependence shows ITG-like property, while a significant deviation from the ITG-like property is found in the R/ dependence, indicating suppression of the ITG mode in the large R/ regime and resultant ion ITB formation. In the comparison between deuterium plasma and hydrogen plasma, the lower transport in the deuterium plasma is observed in both ion and electron heat diffusivities, indicating a significant isotope effect. It was found with the nonlinear turbulent transport simulation with GKV that the zonal flow enhancement contributes to the ITG suppression in the deuterium plasma

Impurity emission characteristics of long pulse discharges in Large Helical Device

Line spectra from intrinsic impurity ions have been monitored during the three kinds of long-pulse discharges (ICH, ECH, NBI). Constant emission from the iron impurity shows no preferential accumulation of iron ion during the long-pulse operations. Stable Doppler ion temperature has been also measured from Fe XX, C V and C III spectra

Isotope effects on energy, particle transport and turbulence in electron cyclotron resonant heating plasma of the Large Helical Device

Positive isotope effects have been found in electron cyclotron resonant heating plasma of the Large Helical Device (LHD). The global energy confinement time (τE) in deuterium (D) plasma is 16% better than in hydrogen (H) plasma for the same line-averaged density and absorption power. The power balance analyses showed a clear reduction in ion energy transport, while electron energy transport does not change dramatically. The global particle confinement time (τp) is degraded in D plasma; τp in D plasma is 20% worse than in H plasma for the same line-averaged density and absorption power. The difference in the density profile was not due to the neutral or impurity sources, but rather was due to the difference in the transport. Ion scale turbulence levels show isotope effects. The core turbulence (ρ  =  0.5–0.8) level is higher in D plasma than in H plasma in the low collisionality regime and is lower in D plasma than in H plasma. The density gradient and collisionality play a role in the core turbulence level

The isotope effect on impurities and bulk ion particle transport in the Large Helical Device

The isotope effect on impurities and bulk ion particle transport is investigated by using the deuterium, hydrogen, and isotope mixture plasma in the Large Helical Device (LHD). A clear isotope effect is observed in the impurity transport but not the bulk ion transport. The isotope effects on impurity transport and ion heat transport are observed as a primary and a secondary effect, respectively, in the plasma with an internal transport barrier (ITB). In the LHD, an ion ITB is always transient because the impurity hole triggered by the increase of ion temperature gradient causes the enhancement of ion heat transport and gradually terminates the ion ITB. The formation of an impurity hole becomes slower in the deuterium (D) plasma than the hydrogen (H) plasma. This primary isotope effect on impurity transport contributes the longer sustainment of the ion ITB state because the low ion thermal diffusivity can be sustained as long as the normalized carbon impurity gradient R/Ln,c, where , is above the critical value (~−5). Therefore, the longer sustainment of the ITB state in the deuterium plasma is considered to be a secondary isotope effect due to the mitigation of the impurity hole. The radial profile of H and D ion density is measured using bulk charge exchange spectroscopy inside the isotope mixture plasma. The decay time of H ion density after the H-pellet injection and the decay time of D ion density after D-pellet injection are almost identical, which demonstrates that there is no significant isotope effect on ion particle transport

Recent Results from LHD Experiment with Emphasis on Relation to Theory from Experimentalist’s View

he Large Helical Device (LHD) has been extending an operational regime of net-current free plasmas towardsthe fusion relevant condition with taking advantage of a net current-free heliotron concept and employing a superconducting coil system. Heating capability has exceeded 10 MW and the central ion and electron temperatureshave reached 7 and 10 keV, respectively. The maximum value of β and pulse length have been extended to 3.2% and 150 s, respectively. Many encouraging physical findings have been obtained. Topics from recent experiments, which should be emphasized from the aspect of theoretical approaches, are reviewed. Those are (1) Prominent features in the inward shifted configuration, i.e., mitigation of an ideal interchange mode in the configuration with magnetic hill, and confinement improvement due to suppression of both anomalous and neoclassical transport, (2) Demonstration ofbifurcation of radial electric field and associated formation of an internal transport barrier, and (3) Dynamics of magnetic islands and clarification of the role of separatrix