Distribution of Dislocations in Germanium Single Crystals during Plastic Deformation

Dislocation configurations in germanium single crystals developed during tensile deformation at 600℃ were frozen in by the rapid cooling of deformed crystals under load and investigated with etch pit technique. Distribution patterns of dislocation etch pits at various deformation stages were observed on two kinds of surfaces which were cut out parallel to the cross slip plane (111) and to the primary slip plane (111). Peculiar distribution patterns of etch pits were developed during stage I, namely, the stripe on the (111) surface and the dense zone on the (111) surface. Stripe patterns of dislocation etch pits were also observed on the surfaces cut out parallel to the critical slip plane (111) and to the conjugate slip plane (111). It was found that the stripes on (111), (111), and (111) surfaces and the dense zone on (111) surface were interrelated each other. Characteristics of the distribution pattern of etch pits were compared with those observed on f.c.c. metals

Strain-Rate and Temperature Dependence of Mechanical Behaviour in Germanium Crystals

The stress-strain characteristics and the development of the dislocation structure in germanium crystals are investigated as dependent on the strain rate and the temperature. The results are interpreted in the light of the dislocation behaviour which has been clarified by the foregoing paper. The shape of the stress-strain curve is similar for any set of the strain rate and the temperature chosen. It is concluded that the higher density or the higher velocity of moving dislocations in crystals results in the higher flow stress and the larger strain in each deformation stage. The essential difference between stage I and stage II lies in the difference in the dislocation arrangement and not in the dislocation density. The mobile fraction of dislocations at lower yield point is estimated to be of the order of several percent. It is found that, once forest dislocations begin to be active, stage I is never restored by any choice of the strain rate or the temperature in the subsequent deformation

Dynamical State of Dislocations in Germanium Crystals during Deformation(Physics)

Experimental results in the strain-rate change tests on germanium single crystals done in a previous paper are analysed with the use of new velocity data for isolated dislocations. An equilibrium stationary state of moving dislocations appears in the deformation stage beyond the middle of stage 0 of the stress-strain curve. The velocity v and the density N_m of moving dislocations in the equilibrium state are observed to depend on the strain rate [ε] as v∝[ε]^ and N_m∝[ε]^, respectively, at 600℃. Transition of the state of dislocation motion from one equilibrium state to another by a sudden change of the strain rate during deformation is also investigated. It is concluded that the values of v and N_m in the equilibrium state at a certain temperature are determined completely by the strain rate and do not depend on the density of total dislocations in the crystal nor on the values of v and N_m which the crystal has assumed previously. A transient stage of about 0.5% in strain is found to exist when the state of dislocations motion is transferred from one equilibrium state to another by the change of strain rate

Microdynamics of Dislocations in Plastic Deformation of Germanium Crystals

The state of dislocation motion in germanium crystals during deformation is investigated by means of the strain-rate change and the temperature change tests with use of the velocity equation for isolated dislocations. It is shown that the steady state in the dislocation transport is realized in stage I and in stage II. Namely, the velocity and the density of moving dislocations are kept constant against the strain in each deformation stage. Both the velocity and the density of moving dislocations in the steady state depend strongly on the strain rate and the temperature. Only a few percent of the total dislocations move in stage I while almost all dislocations existing move in stage II. Work-hardening takes place through the increase in the magnitude of the long-range interaction stress for the moving dislocations. The interaction stress is shown to be constant with respect to the location of the moving dislocations

Rb-Sr age of an impact event recorded in Yamato-791088 H chondrite

The age of the impact event is recorded in Yamato(Y)-791088,a high-iron type chondrite and has been dated using the Rb-Sr chronometer. A brief mineralogical characterization was made of the chondrite as well. The obtained impact age is 1024±47Ma. When Y-791088 recorded the impact event, it might not have been on the surface of the parent body, but rather deep. Therefore, some sulfide was not vaporized and Rb was not lost during the impact. Metal phases were once homogenized and plessite, consisting of two phases, is really scarce. After the impact, the parental body could not have lasted long before separating into pieces

The crystal structure of the plant small GTPase OsRac1 reveals its mode of binding to NADPH oxidase

This research was originally published in Journal of Biological Chemistry. Ken-ichi Kosami, Izuru Ohki, Minoru Nagano, Kyoko Furuita, Toshihiko Sugiki, Yoji Kawano, Tsutomu Kawasaki, Toshimichi Fujiwara, Atsushi Nakagawa, Ko Shimamoto and Chojiro Kojima. The crystal structure of the plant small GTPase OsRac1 reveals its mode of binding to NADPH oxidase. Journal of Biological Chemistry. 2014; 289, 28569-28578. © the American Society for Biochemistry and Molecular Biology

Structural differences between the closely related RNA helicases, UAP56 and URH49, fashion distinct functional apo-complexes

mRNAを核から細胞質へ輸送するバルクmRNA輸送体の構成因子を解明 がんの早期発見や予後の予測に役立つ可能性のある研究成果. 京都大学プレスリリース. 2024-01-16.mRNA export is an essential pathway for the regulation of gene expression. In humans, closely related RNA helicases, UAP56 and URH49, shape selective mRNA export pathways through the formation of distinct complexes, known as apo-TREX and apo-AREX complexes, and their subsequent remodeling into similar ATP-bound complexes. Therefore, defining the unidentified components of the apo-AREX complex and elucidating the molecular mechanisms underlying the formation of distinct apo-complexes is key to understanding their functional divergence. In this study, we identify additional apo-AREX components physically and functionally associated with URH49. Furthermore, by comparing the structures of UAP56 and URH49 and performing an integrated analysis of their chimeric mutants, we exhibit unique structural features that would contribute to the formation of their respective complexes. This study provides insights into the specific structural and functional diversification of these two helicases that diverged from the common ancestral gene Sub2

Th17 cells differentiated with mycelial membranes of Candida albicans prevent oral candidiasis

Candida albicans is a human commensal that causes opportunistic infections. Th17 cells provide resistance against mucosal infection with C. albicans; however, the T cell antigens remain little known. Our final goal is to find effective T cell antigens of C. albicans that are responsible for immunotherapy against candidiasis. Here, we prepared fractions including cytosol, membrane and cell wall from yeast and mycelial cells. Proteins derived from a membrane fraction of mycelial cells effectively induced differentiation of CD4+ T cells into IL-17A-producing Th17 cells. To confirm the immunological response in vivo of proteins from mycelial membrane, we performed adoptive transfer experiments using ex vivo stimulated CD4+ T cells from IL-17A-GFP reporter mice. Mycelial membrane-differentiated CD4+ Th17 cells adoptively transferred intravenously prevented oral candidiasis by oral infection of C. albicans, compared with control anti-CD3-stimulated CD4+ T cells. This was confirmed by the clinical score and the number of neutrophils on the infected tissues. These data suggest that effective T cell antigens against candidiasis could be present in the membrane protein fraction of mycelial cells. The design of novel vaccination strategies against candidiasis will be our next step.福岡歯科大学2017年

Large Population of ALMA Galaxies at z>6 with Very High [OIII]88um to [CII]158um Flux Ratios: Evidence of Extremely High Ionization Parameter or PDR Deficit?

We present our new ALMA observations targeting [OIII]88um, [CII]158um, [NII]122um, and dust continuum emission for three Lyman break galaxies at z=6.0293-6.2037 identified in the Subaru/Hyper Suprime-Cam survey. We clearly detect [OIII] and [CII] lines from all of the galaxies at 4.3-11.8sigma levels, and identify multi-band dust continuum emission in two of the three galaxies, allowing us to estimate infrared luminosities and dust temperatures simultaneously. In conjunction with previous ALMA observations for six galaxies at z>6, we confirm that all the nine z=6-9 galaxies have high [OIII]/[CII] ratios of L[OIII]/L[CII]~3-20, ~10 times higher than z~0 galaxies. We also find a positive correlation between the [OIII]/[CII] ratio and the Lya equivalent width (EW) at the ~90% confidence level. We carefully investigate physical origins of the high [OIII]/[CII] ratios at z=6-9 using Cloudy, and find that high density of the interstellar medium, low C/O abundance ratio, and the cosmic microwave background attenuation are responsible to only a part of the z=6-9 galaxies. Instead, the observed high [OIII]/[CII] ratios are explained by 10-100 times higher ionization parameters or low photodissociation region (PDR) covering fractions of 0-10%, both of which are consistent with our [NII] observations. The latter scenario can be reproduced with a density bounded nebula with PDR deficit, which would enhance the Lya, Lyman continuum, and C+ ionizing photons escape from galaxies, consistent with the [OIII]/[CII]-Lya EW correlation we find.Comment: 20 pages, 18 figures, Accepted for publication in Ap

CHH with Early-Onset CAD

The patient with congenital hypogonadotropic hypogonadism (HH) shows low serum levels of androgen, which is a group of sex hormones including testosterone, caused by the decreased gonadotropin release in the hypothalamus. Recent reports showed androgens exert protective effects against insulin resistance or atherosclerotic diseases, such as diabetes mellitus or coronary artery disease. However, whether the juvenile hypogonadism affects the diabetes or cardiovascular disease is unclear. We report a case of a middle-aged man with congenital HH who had severe coronary artery disease complicated with metabolic disorders