Tropical variability simulated in ICON-A with a spectral cumulus parameterization

We implemented a spectral cumulus parameterization based on a cloud-resolving model (SC scheme) in the icosahedral nonhydrostatic atmospheric model (ICON-A). We compared the resulting simulated climatology and tropical variability with results from the standard version of ICON-A using a variant of the Tiedtke-Nordeng scheme (TK scheme) using observational and reanalysis data. The climatological errors of the SC scheme were similar to those of the TK scheme, but several biases, such as properties of meridional winds and precipitation pattern in the western Pacific, were much improved. For tropical variability, we found that the SC scheme improved the interannual response of the precipitation in the western Pacific and was able to simulate Madden-Julian oscillation (MJO) features much better than the TK scheme. We investigated the reason for the better simulation of the MJO using composite analysis and column process analysis for moisture. Our results suggest that the entrainment parameterization of the SC scheme is necessary to reproduce the MJO; however, spectral representation and improved convective closure are also found to contribute for better MJO simulation. These parameterizations improved moisture supply from low-level clouds and cloud mass flux which were needed to sustain the MJO. © 2019. The Authors

Solar cells of metal-free phthalocyanine dispersed in polyvinyl carbazole. 1: Effects of the recrystallization of H2PC on cell characteristics

The development of an organic semiconductor solar cell and the effects of the recrystallization of metal free phthalocyanine (H2PC) on the characteristics of NESA/H2PC-PVK/Au sandwich cells were investigated. Alfa-H2PC sandwich cells showed photovoltage and photocurrent in a two direction opposite to that shown y as supplied H2PC cells, which consists mainly of beta-H2PC. Some difference was observed in the response times of the two cells. It is suggested that photocharacteristics change with the specific resistance of the H2PC, which is related to its crystal forms. In the cells with low resistance H2PC carriers are generated in H2PC by illumination, while in high resistance H2PC cells, carriers are generated in PVK which is sensitized with H2PC

Structure and decay pattern of linear-chain state in 14C

The linear-chain states of $^{14}$C are theoretically investigated by using the antisymmetrized molecular dynamics. The calculated excitation energies and the $\alpha$ decay widths of the linear-chain states were compared with the observed data reported by the recent experiments. The properties of the positive-parity linear-chain states reasonably agree with the observation, that convinces us of the linear-chain formation in the positive-parity states. On the other hand, in the negative-parity states, it is found that the linear-chain configuration is fragmented into many states and do not form a single rotational band. As a further evidence of the linear-chain formation, we focus on the $\alpha$ decay pattern. It is shown that the linear-chain states decay to the excited states of daughter nucleus $^{10}{\rm Be}$ as well as to the ground state, while other cluster states dominantly decay into the ground state. Hence, we regard that this characteristic decay pattern is a strong signature of the linear-chain formation

Destruction of star clusters due to the radial migration in spiral galaxies

Most stars in galactic disks are believed to be born as a member of star clusters or associations. Star clusters formed in disks are disrupted due to the tidal stripping and the evolution of star clusters themselves, and as a results new stars are supplied to the galactic disks. We performed $N$-body simulations of star clusters in galactic disks, in which both star clusters and galactic disks are modeled as $N$-body ("live") systems, and as a consequence the disks form transient and recurrent spiral arms. In such non-steady spiral arms, star clusters migrate radially due to the interaction with spiral arms. We found that the migration timescale is a few hundreds Myr and that the angular momentum changes of star clusters are at most $\sim 50$% in 1 Gyr. Radial migration of star clusters to the inner region of galaxies results in a fast disruption of the star clusters because of a stronger tidal field in the inner region of the galaxy. This effect is not negligible for the disruption timescale of star clusters in galactic disks. Stars stripped from clusters form tidal tails which spread over 1--2 kpc. While the spatial distribution of tidal tails change in a complicated way due to the non-steady spiral arms, the velocity distribution conserve well even if the tidal tails are located at a few kpc from their parent clusters. Tidal tails of clusters in galactic disks might be detected using velocity plots.Comment: 5 pages, 4 figures, accepted for MNRA

3alpha clustering in the excited states of 16C

The alpha cluster states of 16C are investigated by using the antisymmetrized molecular dynamics. It is shown that two different types of alpha cluster states exist: triangular and linear-chain states. The former has an approximate isosceles triangular configuration of alpha particles surrounded by four valence neutrons occupying sd-shell, while the latter has the linearly aligned alpha particles with two sd-shell neutrons and two pf-shell neutrons. It is found that the structure of the linear-chain state is qualitatively understood in terms of the 3/2 pi- and 1/2 sigma- molecular orbit as predicted by molecular-orbital model, but there exists non-negligible Be+alpha+2n correlation. The band-head energies of the triangular and linear-chain rotational bands are 8.0 and 15.5 MeV, and the latter is close to the He+Be threshold energy. It is also shown that the linear-chain state becomes the yrast sstate at J=10 with excitation energy 27.8 MeV owing to its very large moment-of-inertia comparable with hyperdeformation.Comment: 7 pages, 5 figure

Straightforward synthesis of functionalized cyclic polymers in high yield via RAFT and thiolactone-disulfide chemistry

An efficient synthetic pathway toward cyclic polymers based on the combination of thiolactone and disulfide chemistry has been developed. First, heterotelechelic linear polystyrene (PS) containing an alpha-thiolactone (TLa) and an omega-dithiobenzoate group was synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization, employing a newly designed TLa-bearing chain transfer agent (CTA). The subsequent reaction of this heterotelechelic polymer with an amine, which acts as a nucleophile for both the TLa and dithiobenzoate units, generated the alpha,omega-thiol-telechelic PS under ambient conditions without the need for any catalyst or other additives. The arrangement of thiols under a high dilution afforded single cyclic PS (c-PS) through an oxidative disulfide linkage. The cyclic PS (c-PS) disulfide ring formation was evidenced by SEC, MALDI-TOF MS and H-1-NMR characterization. Moreover, we demonstrated a controlled ring opening via either disulfide reduction or thiol-disulfide exchange to enable easy and clean topology transformation. Furthermore, to illustrate the broad utility of this synthetic methodology, different amines including functional ones were employed, allowing for the one-step preparation of functionalized cyclic polymers with high yields

Molecular Dynamics Simulation of Sympathetic Crystallization of Molecular Ions

It is shown that the translational degrees of freedom of a large variety of molecules, from light diatomic to heavy organic ones, can be cooled sympathetically and brought to rest (crystallized) in a linear Paul trap. The method relies on endowing the molecules with an appropriate positive charge, storage in a linear radiofrequency trap, and sympathetic cooling. Two well--known atomic coolant species, ${}^9{\hbox{Be}}^+$ and ${}^{137}{\hbox{Ba}}^+$, are sufficient for cooling the molecular mass range from 2 to 20,000 amu. The large molecular charge required for simultaneous trapping of heavy molecules and of the coolant ions can easily be produced using electrospray ionization. Crystallized molecular ions offer vast opportunities for novel studies.Comment: Accepted for publication in Phys. Rev.