ALBERT

Description: Time-resolved in situ observations using synchrotron radiation X-rays showed that γ nucleation difficulties resulted in a massive transformation from the δ phase to the γ phase. The massive transformation occurred even in high-carbon steel (0.45 mass% C) at a cooling rate of 0.33 K/s or more. A crystallographic relationship in which the close-packed (111) plane of the γ phase tended to coincide with the close-packed (110) plane of the δ phase suggested that the γ phase nucleated in a favorable plane in the δ phase. Observations of the sequence in the initial stage of solidification showed that the induced strain and strain rate in the massive transformation were larger than those expected in peritectic solidification. These observations will help us to understand deformation of solidifying shells and to build a physical model.

Description: The apparent irreversibility of the loss of complex traits in evolution (Dollo’s Law) has been explained either by constraints on generating the lost traits or the complexity of selection required for their return. Distinguishing between these explanations is challenging, however, and little is known about the specific nature of potential...

Description: Analyses of nuclear emulsion detectors that can detect and identify charged particles or radiation as tracks have typically utilized optical microscope systems because the targets have lengths from several μm to more than 1000 μm. For recent new nuclear emulsion detectors that can detect tracks of submicron length or less, the current readout systems are insufficient due to their poor resolution. In this study, we developed a new system and method using an optical microscope system for rough candidate selection and the hard X-ray microscope system at SPring-8 for high-precision analysis with a resolution of better than 70 nm resolution. Furthermore, we demonstrated the analysis of submicron-length tracks with a matching efficiency of more than 99% and position accuracy of better than 5 μm. This system is now running semi-automatically.

Description: In situ observation of deformation in globular Al-Cu samples at a solid fraction of ??50% and a global shear strain rate of 10 -1 s -1 was performed using time-resolved X-ray imaging. The solid particle motion during shear was quantitatively analysed. The force was transmitted though the contacts between solid particles over a long distance parallel to the shear plane (18 mean grain size, d ) after only a 1d increment of the Al 2 O 3 push-plate motion. On the other hand, the distance of transmitted force in the perpendicular direction to the shear plane was restricted to approximately 11d even for a high displacement of the Al 2 O 3 push-plate. A relatively high shear strain rate became localized at the shear domain after a small amount of deformation (a 1d increment). The solid fraction decreased in the region of localized shear strain rate. The shear band width, where the shear strain was localized and the solid fr...

Description: Abstract Pore development in natural porous media, as a result of mineral dissolution in flowing fluid, generates complex microstructures. Although the underlying dynamics of fluid flow and the kinetics of the dissolution reactions have been carefully analyzed in many scenarios, it remains interesting to ask if the preferentially developed flow paths share certain general petrophysical properties. Here we combine in situ X‐ray imaging with network modeling to study pore development in chalk driven by acidic fluid flow under ambient condition. We show that the trajectory of a growing pore correlates with the flow path that minimizes cumulative surface—the overall surface area available to fluid within the residence time—calculated along streamlines. This correlation is not a coincidence because cumulative surface determines conversion of reactant and thus defines the position of dissolution front. Model simulations show that, as fluid channelizes, the growth of the leading pore in the flow direction is guided by migration of the most far‐reaching dissolution front, even in an ever‐changing flow field. In addition, we present a complete tomographic time series of microstructure erosion and show a good accord between the in situ observation and the model simulation. Our results suggest that the microscopic pore development is a deterministic process while being sensitive to stochastic perturbations to the migrating dissolution front.

Description: Time-resolved absorption imaging using synchrotron radiation X-rays allows us to observe solidification of metallic alloys of interest. This paper presents peritectic solidification in Sn-Cd alloy and Fe-C alloys. In unidirectional solidification of Sn-Cd alloy, the formation of a banded structure, in which two phases were alternatively piled up in the growth direction, was clearly observed. Sequence of nucleation or fluctuation of triple junction (primary phase / secondary phase / liquid) resulted in the banded structure. Ease of nucleation for both phases contributed to the banded structure formation. In carbon steel (Fe-0.45mass%C), the transformation from δ phase to γ phase was observed. At lower cooling rates, γ phase was produced in semisolid state of δ phase and liquid, indicating the peritectic reaction occurred during solidification. In contrast, δ phase transformed into γ phase when solidification nearly completed at temperatur...

Description: Understanding phenomena occurring at the scale of the crystals during the deformation of semi-solid alloys is important for the development of physically-based rheological models. A range of deformation mechanisms have been proposed including agglomeration and disagglomeration, viscoplastic deformation of the solid skeleton, and granular phenomena such as jamming and dilatancy. This paper overviews in-situ experiments that directly image crystal-scale deformation mechanisms in equiaxed Al alloys at solid fractions shortly after the crystals have impinged to form a loose crystal network. Direct evidence is presented for granular deformation mechanisms including shear-induced dilation in both equiaxed-dendritic and globular microstructures. Modelling approaches suitable for capturing this behaviour are then discussed.

Description: The Stardust spacecraft collected thousands of particles from comet 81P/Wild 2 and returned them to Earth for laboratory study. The preliminary examination of these samples shows that the nonvolatile portion of the comet is an unequilibrated assortment of materials that have both presolar and solar system origin. The comet contains an abundance of silicate grains that are much larger than predictions of interstellar grain models, and many of these are high-temperature minerals that appear to have formed in the inner regions of the solar nebula. Their presence in a comet proves that the formation of the solar system included mixing on the grandest scales.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Brownlee, Don -- Tsou, Peter -- Aleon, Jerome -- Alexander, Conel M O'd -- Araki, Tohru -- Bajt, Sasa -- Baratta, Giuseppe A -- Bastien, Ron -- Bland, Phil -- Bleuet, Pierre -- Borg, Janet -- Bradley, John P -- Brearley, Adrian -- Brenker, F -- Brennan, Sean -- Bridges, John C -- Browning, Nigel D -- Brucato, John R -- Bullock, E -- Burchell, Mark J -- Busemann, Henner -- Butterworth, Anna -- Chaussidon, Marc -- Cheuvront, Allan -- Chi, Miaofang -- Cintala, Mark J -- Clark, B C -- Clemett, Simon J -- Cody, George -- Colangeli, Luigi -- Cooper, George -- Cordier, Patrick -- Daghlian, C -- Dai, Zurong -- D'Hendecourt, Louis -- Djouadi, Zahia -- Dominguez, Gerardo -- Duxbury, Tom -- Dworkin, Jason P -- Ebel, Denton S -- Economou, Thanasis E -- Fakra, Sirine -- Fairey, Sam A J -- Fallon, Stewart -- Ferrini, Gianluca -- Ferroir, T -- Fleckenstein, Holger -- Floss, Christine -- Flynn, George -- Franchi, Ian A -- Fries, Marc -- Gainsforth, Z -- Gallien, J-P -- Genge, Matt -- Gilles, Mary K -- Gillet, Philipe -- Gilmour, Jamie -- Glavin, Daniel P -- Gounelle, Matthieu -- Grady, Monica M -- Graham, Giles A -- Grant, P G -- Green, Simon F -- Grossemy, Faustine -- Grossman, Lawrence -- Grossman, Jeffrey N -- Guan, Yunbin -- Hagiya, Kenji -- Harvey, Ralph -- Heck, Philipp -- Herzog, Gregory F -- Hoppe, Peter -- Horz, Friedrich -- Huth, Joachim -- Hutcheon, Ian D -- Ignatyev, Konstantin -- Ishii, Hope -- Ito, Motoo -- Jacob, Damien -- Jacobsen, Chris -- Jacobsen, Stein -- Jones, Steven -- Joswiak, David -- Jurewicz, Amy -- Kearsley, Anton T -- Keller, Lindsay P -- Khodja, H -- Kilcoyne, A L David -- Kissel, Jochen -- Krot, Alexander -- Langenhorst, Falko -- Lanzirotti, Antonio -- Le, Loan -- Leshin, Laurie A -- Leitner, J -- Lemelle, L -- Leroux, Hugues -- Liu, Ming-Chang -- Luening, K -- Lyon, Ian -- Macpherson, Glen -- Marcus, Matthew A -- Marhas, Kuljeet -- Marty, Bernard -- Matrajt, Graciela -- McKeegan, Kevin -- Meibom, Anders -- Mennella, Vito -- Messenger, Keiko -- Messenger, Scott -- Mikouchi, Takashi -- Mostefaoui, Smail -- Nakamura, Tomoki -- Nakano, T -- Newville, M -- Nittler, Larry R -- Ohnishi, Ichiro -- Ohsumi, Kazumasa -- Okudaira, Kyoko -- Papanastassiou, Dimitri A -- Palma, Russ -- Palumbo, Maria E -- Pepin, Robert O -- Perkins, David -- Perronnet, Murielle -- Pianetta, P -- Rao, William -- Rietmeijer, Frans J M -- Robert, Francois -- Rost, D -- Rotundi, Alessandra -- Ryan, Robert -- Sandford, Scott A -- Schwandt, Craig S -- See, Thomas H -- Schlutter, Dennis -- Sheffield-Parker, J -- Simionovici, Alexandre -- Simon, Steven -- Sitnitsky, I -- Snead, Christopher J -- Spencer, Maegan K -- Stadermann, Frank J -- Steele, Andrew -- Stephan, Thomas -- Stroud, Rhonda -- Susini, Jean -- Sutton, S R -- Suzuki, Y -- Taheri, Mitra -- Taylor, Susan -- Teslich, Nick -- Tomeoka, Kazu -- Tomioka, Naotaka -- Toppani, Alice -- Trigo-Rodriguez, Josep M -- Troadec, David -- Tsuchiyama, Akira -- Tuzzolino, Anthony J -- Tyliszczak, Tolek -- Uesugi, K -- Velbel, Michael -- Vellenga, Joe -- Vicenzi, E -- Vincze, L -- Warren, Jack -- Weber, Iris -- Weisberg, Mike -- Westphal, Andrew J -- Wirick, Sue -- Wooden, Diane -- Wopenka, Brigitte -- Wozniakiewicz, Penelope -- Wright, Ian -- Yabuta, Hikaru -- Yano, Hajime -- Young, Edward D -- Zare, Richard N -- Zega, Thomas -- Ziegler, Karen -- Zimmerman, Laurent -- Zinner, Ernst -- Zolensky, Michael -- New York, N.Y. -- Science. 2006 Dec 15;314(5806):1711-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Astronomy, University of Washington, Seattle, WA 98195, USA. brownlee@astro.washington.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17170289" target="_blank"〉PubMed〈/a〉

Description: We measured the elemental compositions of material from 23 particles in aerogel and from residue in seven craters in aluminum foil that was collected during passage of the Stardust spacecraft through the coma of comet 81P/Wild 2. These particles are chemically heterogeneous at the largest size scale analyzed ( approximately 180 ng). The mean elemental composition of this Wild 2 material is consistent with the CI meteorite composition, which is thought to represent the bulk composition of the solar system, for the elements Mg, Si, Mn, Fe, and Ni to 35%, and for Ca and Ti to 60%. The elements Cu, Zn, and Ga appear enriched in this Wild 2 material, which suggests that the CI meteorites may not represent the solar system composition for these moderately volatile minor elements.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Flynn, George J -- Bleuet, Pierre -- Borg, Janet -- Bradley, John P -- Brenker, Frank E -- Brennan, Sean -- Bridges, John -- Brownlee, Don E -- Bullock, Emma S -- Burghammer, Manfred -- Clark, Benton C -- Dai, Zu Rong -- Daghlian, Charles P -- Djouadi, Zahia -- Fakra, Sirine -- Ferroir, Tristan -- Floss, Christine -- Franchi, Ian A -- Gainsforth, Zack -- Gallien, Jean-Paul -- Gillet, Philippe -- Grant, Patrick G -- Graham, Giles A -- Green, Simon F -- Grossemy, Faustine -- Heck, Philipp R -- Herzog, Gregory F -- Hoppe, Peter -- Horz, Friedrich -- Huth, Joachim -- Ignatyev, Konstantin -- Ishii, Hope A -- Janssens, Koen -- Joswiak, David -- Kearsley, Anton T -- Khodja, Hicham -- Lanzirotti, Antonio -- Leitner, Jan -- Lemelle, Laurence -- Leroux, Hugues -- Luening, Katharina -- Macpherson, Glenn J -- Marhas, Kuljeet K -- Marcus, Matthew A -- Matrajt, Graciela -- Nakamura, Tomoki -- Nakamura-Messenger, Keiko -- Nakano, Tsukasa -- Newville, Matthew -- Papanastassiou, Dimitri A -- Pianetta, Piero -- Rao, William -- Riekel, Christian -- Rietmeijer, Frans J M -- Rost, Detlef -- Schwandt, Craig S -- See, Thomas H -- Sheffield-Parker, Julie -- Simionovici, Alexandre -- Sitnitsky, Ilona -- Snead, Christopher J -- Stadermann, Frank J -- Stephan, Thomas -- Stroud, Rhonda M -- Susini, Jean -- Suzuki, Yoshio -- Sutton, Stephen R -- Taylor, Susan -- Teslich, Nick -- Troadec, D -- Tsou, Peter -- Tsuchiyama, Akira -- Uesugi, Kentaro -- Vekemans, Bart -- Vicenzi, Edward P -- Vincze, Laszlo -- Westphal, Andrew J -- Wozniakiewicz, Penelope -- Zinner, Ernst -- Zolensky, Michael E -- New York, N.Y. -- Science. 2006 Dec 15;314(5806):1731-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physics, State University of New York at Plattsburgh, 101 Broad Street, Plattsburgh, NY 12901, USA. george.flynn@plattsburgh.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17170294" target="_blank"〉PubMed〈/a〉

Description: Regolith particles on the asteroid Itokawa were recovered by the Hayabusa mission. Their three-dimensional (3D) structure and other properties, revealed by x-ray microtomography, provide information on regolith formation. Modal abundances of minerals, bulk density (3.4 grams per cubic centimeter), and the 3D textures indicate that the particles represent a mixture of equilibrated and less-equilibrated LL chondrite materials. Evidence for melting was not seen on any of the particles. Some particles have rounded edges. Overall, the particles' size and shape are different from those seen in particles from the lunar regolith. These features suggest that meteoroid impacts on the asteroid surface primarily form much of the regolith particle, and that seismic-induced grain motion in the smooth terrain abrades them over time.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Tsuchiyama, Akira -- Uesugi, Masayuki -- Matsushima, Takashi -- Michikami, Tatsuhiro -- Kadono, Toshihiko -- Nakamura, Tomoki -- Uesugi, Kentaro -- Nakano, Tsukasa -- Sandford, Scott A -- Noguchi, Ryo -- Matsumoto, Toru -- Matsuno, Junya -- Nagano, Takashi -- Imai, Yuta -- Takeuchi, Akihisa -- Suzuki, Yoshio -- Ogami, Toshihiro -- Katagiri, Jun -- Ebihara, Mitsuru -- Ireland, Trevor R -- Kitajima, Fumio -- Nagao, Keisuke -- Naraoka, Hiroshi -- Noguchi, Takaaki -- Okazaki, Ryuji -- Yurimoto, Hisayoshi -- Zolensky, Michael E -- Mukai, Toshifumi -- Abe, Masanao -- Yada, Toru -- Fujimura, Akio -- Yoshikawa, Makoto -- Kawaguchi, Junichiro -- New York, N.Y. -- Science. 2011 Aug 26;333(6046):1125-8. doi: 10.1126/science.1207807.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Earth and Space Science, Osaka University, Toyonaka, 560-0043, Japan. akira@ess.sci.osaka-u.ac.jp〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21868671" target="_blank"〉PubMed〈/a〉