1,390 research outputs found
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
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