Diverse features of dust particles and their aggregates inferred from experimental nanoparticles

Nanometre- to micrometre-sized solid dust particles play a vital role in star and planet formations. Despite of their importance, however, our understanding of physical and chemical properties of dust particles is still provisional. We have conducted a condensation experiment of the vapour generated from a solid starting material having nearly cosmic proportions in elements. A laser flash heating and subsequent cooling has produced a diverse type of nanoparticles simultaneously. Here we introduce four types of nanoparticles as potential dust particles in space: amorphous silicate nanoparticles (type S); core/mantle nanoparticles with iron or hydrogenised-iron core and amorphous silicate mantle (type IS); silicon oxycarbide nanoparticles and hydrogenised silicon oxycarbide nanoparticles (type SiOC); and carbon nanoparticles (type C), all produced in a single heating-cooling event. Type IS and SiOC nanoparticles are new for potential astrophysical dust. The nanoparticles are aggregated to a wide variety of structures, from compact, fluffy, and networked. A simultaneous formation of nanoparticles, which are diverse in chemistry, shape, and structure, prompts a re-evaluation of astrophysical dust particlesComment: 9 pages, 3 figure

Pure iron grains are rare in the universe

The abundant forms in which the major elements in the universe exist have been determined from numerous astronomical observations and meteoritic analyses. Iron (Fe) is an exception, in that only depletion of gaseous Fe has been detected in the interstellar medium, suggesting that Fe is condensed into a solid, possibly the astronomically invisible metal. To determine the primary form of Fe, we replicated the formation of Fe grains in gaseous ejecta of evolved stars by means of microgravity experiments. We found that the sticking probability for formation of Fe grains is extremely small; only several atoms will stick per hundred thousand collisions, so that homogeneous nucleation of metallic Fe grains is highly ineffective, even in the Fe-rich ejecta of Type Ia supernovae. This implies that most Fe is locked up as grains of Fe compounds or as impurities accreted onto other grains in the interstellar medium

Ubiquitous preferential water adsorption to electrodes in water/1-propanol mixtures detected by electrochemical impedance spectroscopy

The electric double layer is an important structure that appears at charged liquid interfaces, and it determines the performance of various electrochemical devices such as supercapacitors and electrokinetic energy converters. Here the double-layer capacitance of the interface between aluminum electrodes and water/1-propanol electrolyte solutions is investigated using electrochemical impedance spectroscopy. The double-layer capacitances of mixture solvents are almost the same as those of water-only electrolyte solutions, and the double-layer capacitance of 1-propanol-only solutions are significantly smaller than those of other volume fractions of water. The qualitative variation of the double-layer capacitances with the water volume fraction is independent of the electrolyte types and their concentrations. Therefore, these results can be explained by ubiquitous preferential water adsorption caused by the hydrophilicity of the electrode surface.Comment: 7 pages, 5 figure

Serum free fatty acids levels not associated with normal tension glaucoma

Kenya Yuki, Itaru Kimura, Kazuo TsubotaDepartment of Ophthalmology, Keio University School of Medicine, Tokyo, JapanPurpose: To determine the free fatty acid levels in the sera of patients with normal-tension glaucoma and compare it with that of normal controls.Methods: Forty-four consecutive patients with newly diagnosed normal-tension glaucoma and forty-four age and gender matched controls were evaluated. The type and level of fatty acids in the sera were measured by gas chromatography (Model GC17A; Shimazu, Kyoto, Japan). Twenty-four fatty acids were identified from 12:0 to 24:1. The values were compared between the normal-tension glaucoma and control groups by Mann–Whitney U tests.Results: No statistically significant difference was found in the levels of any free fatty acids between the normal-tension glaucoma group and control group.Conclusion: No significant association was found in the serum free fatty acids levels including docosahexaenoic acid and eicosapentaenoic acid between normal-tension glaucoma patients and controls.Keywords: free fatty acid, docosahexaenoic acid, eicosapentaenoic acid, normal tension glaucom

すばる望遠鏡 Hyper Suprime-Cam の多色深観測による低光度活動銀河核の可視光度変光の性質に関する研究

Tohoku University秋山正幸課

すばる望遠鏡 Hyper Suprime-Cam の多色深観測による低光度活動銀河核の可視光度変光の性質に関する研究

Tohoku University秋山正幸課

岩礁性潮間帯に生息する半陸上生活魚類タネギンポの生態学的研究

内容の要約広島大学(Hiroshima University)博士(農学)Doctor of Agriculturedoctora