Magnetocaloric effect, thermal conductivity, and magnetostriction of epoxy-bonded La(Fe0.88Si0.12)13 hydrides

金沢大学理工研究域数物科学系Magnetic materials with large magnetocaloric effect are significantly important for magnetic refrigeration. La(Fe0.88Si0.12)13 compounds are one of the promising magnetocaloric materials that have a first order magnetic phase transition. Transition temperature of hydrogenated La(Fe0.88Si0.12)13 increased up to room temperature region while keeping metamagnetic transition properties. From view point of practical usage, bonded composite are very attractive and their properties are important. We made epoxy bonded La(Fe0.88Si0.12)13 hydrides. Magnetocaloric effect was studied by measuring specific heat, magnetization, and temperature change in adiabatic demagnetization. The composite had about 20% smaller entropy change from the hydrogenated La(Fe0.88Si0.12)13 powder in 2 T. Thermal conductivity of the composite was several times smaller than La(Fe,Si)13. The small thermal conductivity was explained due to the small thermal conductivity of epoxy. Thermal conductivity was observed to be insensitive to magnetic field in 2 T. Thermal expansion and magnetostriction of the composite material were measured. The composite expanded about 0.25% when it entered into ferromagnetic phase. Magnetostriction of the composite in ferromagnetic phase was about 0.2% in 5 T and much larger than that in paramagnetic phase. The composite didn\u27t break after about 100 times magnetic field changes in adiabatic demagnetization experiment even though it has magnetostriction. © Published under licence by IOP Publishing Ltd

思春期女性のボディ・イメージと体型に関する縦断的研究

思春期の自己のボディ・イメージ(身体像)とローレル指数について縦断的調査を行い両者の関連を検討した。 対象は医科大学に在学中の女子看護学生108名で、二次性徴の出現時期や、小学校低学年・高学年・ 中学生・高校生の時に自分の体型をいかに感じていたかを記憶に基づきアンケート調査した。更に6～ 18歳まで1年毎の学校での身体計測値からローレル指数を算出し、ボディ・イメージや二次性徴との関 連を検討した。 対象の各年齢群別ローレル指数は自己のボディ・イメージと有意の相関を示したが、普通と認識するローレル指数と全国平均ローレル指数の差は加齢と共に拡大し、16～18で最大となった。初経発来年齢 別のボディイメージの比較でも、早発群は体型を「やや大っている」と認識し、普通群、遅発群は初経前後から自己のホディ・イメージが太っている方へと変動する傾向を認めた。性成熟と共により痩せた体型を普通の体型と捉える傾向が明らかになった。思春期女性の体脂肪量の増加は生理的な変化であり、思春期前から二次性徴の出現と体脂肪の増加、体型変化について正しい教育を行っていくことが重要である

Surgeons and suture zones: Hybridization among four surgeonfish species in the Indo-Pacific with variable evolutionary outcomes.

Closely related species can provide valuable insights into evolutionary processes through comparison of their ecology, geographic distribution and the history recorded in their genomes. In the Indo-Pacific, many reef fishes are divided into sister species that come into secondary contact at biogeographic borders, most prominently where Indian Ocean and Pacific Ocean faunas meet. It is unclear whether hybridization in this contact zone represents incomplete speciation, secondary contact, an evolutionary dead-end (for hybrids) or some combination of the above. To address these issues, we conducted comprehensive surveys of two widely-distributed surgeonfish species, Acanthurus leucosternon (N = 141) and A. nigricans (N = 412), with mtDNA cytochrome b sequences and ten microsatellite loci. These surgeonfishes are found primarily in the Indian and Pacific Oceans, respectively, but overlap at the Christmas and Cocos-Keeling Islands hybrid zone in the eastern Indian Ocean. We also sampled the two other Pacific members of this species complex, A. achilles (N = 54) and A. japonicus (N = 49), which are known to hybridize with A. nigricans where their ranges overlap. Our results indicate separation between the four species that range from the recent Pleistocene to late Pliocene (235,000–2.25 million years ago). The Pacific A. achilles is the most divergent (and possibly ancestral) species with mtDNA dcorr ≈ 0.04, whereas the other two Pacific species (A. japonicus and A. nigricans) are distinguishable only at a population or subspecies level (ΦST = 0.6533, P < 0.001). Little population structure was observed within species, with evidence of recent population expansion across all four geographic ranges. We detected sharing of mtDNA haplotypes between species and extensive hybridization based on microsatellites, consistent with later generation hybrids but also the effects of allele homoplasy. Despite extensive introgression, 98% of specimens had concordance between mtDNA lineage and species identification based on external morphology, indicating that species integrity may not be eroding. The A. nigricans complex demonstrates a range of outcomes from incomplete speciation to secondary contact to decreasing hybridization with increasing evolutionary depth

Reef fish hybridization: lessons learnt from butterflyfishes (genus Chaetodon)

Natural hybridization is widespread among coral reef fishes. However, the ecological promoters and evolutionary consequences of reef fish hybridization have not been thoroughly evaluated. Butterflyfishes form a high number of hybrids and represent an appropriate group to investigate hybridization in reef fishes. This study provides a rare test of terrestrially derived hybridization theory in the marine environment by examining hybridization between Chaetodon trifasciatus and C. lunulatus at Christmas Island. Overlapping spatial and dietary ecologies enable heterospecific encounters. Nonassortative mating and local rarity of both parent species appear to permit heterospecific breeding pair formation. Microsatellite loci and mtDNA confirmed the status of hybrids, which displayed the lowest genetic diversity in the sample and used a reduced suite of resources, suggesting decreased adaptability. Maternal contribution to hybridization was unidirectional, and no introgression was detected, suggesting limited, localized evolutionary consequences of hybridization

Cryptic Diversity in Indo-Pacific Coral-Reef Fishes Revealed by DNA-Barcoding Provides New Support to the Centre-of-Overlap Hypothesis

Diversity in coral reef fishes is not evenly distributed and tends to accumulate in the Indo-Malay-Philippines Archipelago (IMPA). The comprehension of the mechanisms that initiated this pattern is in its infancy despite its importance for the conservation of coral reefs. Considering the IMPA either as an area of overlap or a cradle of marine biodiversity, the hypotheses proposed to account for this pattern rely on extant knowledge about taxonomy and species range distribution. The recent large-scale use of standard molecular data (DNA barcoding), however, has revealed the importance of taking into account cryptic diversity when assessing tropical biodiversity. We DNA barcoded 2276 specimens belonging to 668 coral reef fish species through a collaborative effort conducted concomitantly in both Indian and Pacific oceans to appraise the importance of cryptic diversity in species with an Indo-Pacific distribution range. Of the 141 species sampled on each side of the IMPA, 62 presented no spatial structure whereas 67 exhibited divergent lineages on each side of the IMPA with K2P distances ranging between 1% and 12%, and 12 presented several lineages with K2P distances ranging between 3% and 22%. Thus, from this initial pool of 141 nominal species with Indo-Pacific distribution, 79 dissolved into 165 biological units among which 162 were found in a single ocean. This result is consistent with the view that the IMPA accumulates diversity as a consequence of its geological history, its location on the junction between the two main tropical oceans and the presence of a land bridge during glacial times in the IMPA that fostered allopatric divergence and secondary contacts between the Indian and Pacific oceans