Orbital Evolution of Moons in Weakly Accreting Circumplanetary Disks

We investigate the formation of hot and massive circumplanetary disks (CPDs) and the orbital evolution of satellites formed in these disks. Because of the comparatively small size-scale of the sub-disk, quick magnetic diffusion prevents the magnetorotational instability (MRI) from being well-developed at ionization levels that would allow MRI in the parent protoplanetary disk. In the absence of significant angular momentum transport, continuous mass supply from the parental protoplanetary disk leads to the formation of a massive CPD. We have developed an evolutionary model for this scenario and have estimated the orbital evolution of satellites within the disk. We find, in a certain temperature range, that inward migration of a satellite can be stopped by a change in the structure due to the opacity transitions. Moreover, by capturing second and third migrating satellites in mean motion resonances, a compact system in Laplace resonance can be formed in our disk models.Comment: 10 pages, 9 figure

Cosmic-Ray Ionization Rate in Protoplanetary Disks with Sheared Magnetic Fields

We investigate the effects of magnetic-field configurations on the ionization rate by cosmic rays in protoplanetary disks. First, we consider cosmic-ray propagation from the interstellar medium (ISM) to the protoplanetary disks and showed that the cosmic-ray density around the disk should be 2 times lower than the ISM value. Then, we compute the attenuation of cosmic rays in protoplanetary disks. The magnetic fields in the disk are stretched to the azimuthal directions, and cosmic rays need to detour while propagating to the midplane. Our results show that the detouring effectively enhances the column density by about two orders of magnitude. We employ a typical ionization rate by cosmic rays in diffuse ISM, which is considered too high to be consistent with observations of protoplanetary disks, and find that the cosmic rays are significantly shielded at the midplane. In the case of the disk around IM Lup, the midplane ionization rate is very low for r ≲ 100 au, while the value is as large as a diffuse ISM in the outer radii. Our results are consistent with the recent Atacama Large Millimeter/submillimeter Array observation that indicates the radial gradient in the cosmic-ray ionization rate. The high ionization rate in the outer radii of disks may activate the magnetorotational instability that was thought to be suppressed due to ambipolar diffusion. These results will have a strong influence on the dynamical and chemical evolutions of protoplanetary disks

Photoionization-induced pi <-> H site switching dynamics in phenol(+)-Rg (Rg = Ar, Kr) dimers probed by picosecond time-resolved infrared spectroscopy

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.The ionization-induced pi H site switching reaction in phenol(+)-Rg (PhOH+-Rg) dimers with Rg = Ar and Kr is traced in real time by picosecond time-resolved infrared (ps-TRIR) spectroscopy. The ps-TRIR spectra show the prompt appearance of the non-vanishing free OH stretching band upon resonant photoionization of the pi-bound neutral clusters, and the delayed appearance of the hydrogen-bonded (H-bonded) OH stretching band. This result directly proves that the Rg ligand switches from the pi-bound site on the aromatic ring to the H-bonded site at the OH group by ionization. The subsequent H pi back reaction converges the dimer to a pi H equilibrium. This result is in sharp contrast to the single-step pi H forward reaction in the PhOH+-Ar-2 trimer with 100% yield. The reaction mechanism and yield strongly depend on intracluster vibrational energy redistribution. A classical rate equation analysis for the time evolutions of the band intensities of the two vibrations results in similar estimates for the time constants of the pi H forward reaction of tau(+) = 122 and 73 ps and the H pi back reaction of tau_ = 155 and 188 ps for PhOH+-Ar and PhOH+-Kr, respectively. The one order of magnitude slower time constant in comparison to the PhOH+-Ar-2 trimer (tau(+) = 7 ps) is attributed to the decrease in density of states due to the absence of the second Ar in the dimer. The similar time constants for both PhOH+-Rg dimers are well rationalized by a classical interpretation based on the comparable potential energy surfaces, reaction pathways, and density of states arising from their similar intermolecular vibrational frequencies

Removal of Pb(II) from water using keratin colloidal solution obtained from wool

The aim of this study is to investigate the use of keratin colloidal solution, which was obtained from wool, for the removal of Pb(II) from water. The addition of keratin colloidal solution (15 g L-1, 0.30 mL) to a Pb(II) solution (1.0 mM, 0.90 mL, pH 5.0) resulted in the formation and precipitation of a Pb-keratin aggregate. Measurement of the Pb(II) and protein concentrations in the supernatant solution revealed that 88 and 99 % of the Pb(II) and keratin protein were removed from the solution, respectively. The maximum Pb(II) uptake capacity of keratin in the colloidal solution was 43.3 mg g(-1). In addition, the Pb-keratin aggregate was easily decomposed via the addition of nitric acid, which enabled the recovery of Pb(II). However, aggregation did not occur in solutions with Pb(II) concentrations below 0.10 mM. Therefore, we used a keratin colloidal solution encapsulated in a dialysis cellulose tube to remove Pb(II) from 0.10 mM solutions, which enabled the removal of 95 % of the Pb(II). From these results, we conclude that keratin colloidal solution is useful for the treatment of water polluted with Pb(II).ArticleENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH. 20(9):6531-6538 (2013)journal articl

Eco-Benign Orange-Hued Pigment Derived from Aluminum-Enriched Biogenous Iron Oxide Sheaths

Inorganic pigments have been widely used due to their low cost of production, strong hiding power, and chemical resistance; nevertheless, they have limited hue width and chromaticity. To eliminate these disadvantages, we herein propose the use of an ingenious biotemplate technique to produce Al-enriched biogenic iron oxide (BIOX) materials. Spectrophotometric color analysis showed that high levels of Al inclusion on heat-treated BIOX samples produced heightened yellowish hues and lightness. The Al-enriched BIOX sheaths exhibited a stable tubular structure and excellent thermal stability of color tones after heating at high temperatures and repetitive heat treatments. Ultrastructural analysis and mechanical destruction experiments revealed that the highly chromatic orange-hue of these pigments are ascribed probably to an ingenious cylindrical nanocomposite architecture composed of putative Fe-included low crystalline Al oxide regions and hematite particles embedded therein. The present work therefore demonstrates that the bioengineered material can serve as an epochal orange-hued inorganic pigment with low toxicity and marked thermostability that should meet large industrial demand

Impact of Body Mass Index on Survival of Pancreatic Cancer Patients in Japan

The impact of body mass index (BMI) on postoperative survival in Japanese patients with pancreatic cancer is unclear. We examined the relationship between preoperative BMI and the prognosis of Japanese patients who underwent surgery for pancreatic cancer to determine whether BMI affects these patients’ prognosis. Of the patients who underwent pancreatectomy between January 2004 and August 2015 at our institution, 246 were pathologically diagnosed with pancreatic tubular adenocarcinoma; the cancer was located in the pancreatic head (n=161) and in the body and tail (n=85). We classified the patients by BMI: underweight (n=22), normal weight (n=190), and overweight/obese (n=34) groups. We retrospectively analyzed medical records for patient characteristics, lesion location, disease stage, postoperative complications, chemotherapy, and prognosis. Lesion location, disease stage, postoperative complications, and chemotherapy were not significantly different among the BMI groups. The median survival times were as follows (days): all patients, 686; underweight, 485; normal weight, 694; and overweight/obese, 839. In a multivariate analysis, after adjusting for competing risk factors, low BMI was associated with an increased risk of death (normal weight: HR 0.58, p=0.038; overweight/obese: HR 0.54, p=0.059). High BMI was not found to be a postoperative factor for poor prognosis in Japanese pancreatic cancer patients