ALBERT

Description: Characterisation and quantification of tissue structures is limited by sectioning-induced artefacts and by the difficulties of visualising and segmenting 3D volumes. Here we demonstrate that, even in the absence of X-ray contrast agents, X-ray computed microtomography (microCT) and nanotomography (nanoCT) can circumvent these problems by rapidly resolving compositionally discrete 3D tissue regions (such as the collagen-rich adventitia and elastin-rich lamellae in intact rat arteries) which in turn can be segmented due to their different X-ray opacities and morphologies. We then establish, using X-ray tomograms of both unpressurised and pressurised arteries that intra-luminal pressure not only increases lumen cross-sectional area and straightens medial elastic lamellae but also induces profound remodelling of the adventitial layer. Finally we apply microCT to another human organ (skin) to visualise the cell-rich epidermis and extracellular matrix-rich dermis and to show that conventional histological and immunohistochemical staining protocols are compatible with prior X-ray exposure. As a consequence we suggest that microCT could be combined with optical microscopy to characterise the 3D structure and composition of archival paraffin embedded biological materials and of mechanically stressed dynamic tissues such as the heart, lungs and tendons. Scientific Reports 5 doi: 10.1038/srep10074

Description: In situ secondary ion mass spectrometry (SIMS) analyses of δ7Li, Li/Ca, and Mg/Ca were performed on five synthetic aragonite samples precipitated from seawater at 25°C at different rates. The compositions of δ7Li in bulk aragonites and experimental fluids were measured by multicollector inductively coupled plasma–mass spectrometry (MC-ICP-MS). Both techniques yielded similar δ7Li in aragonite when SIMS analyses were corrected to calcium carbonate reference materials. Fractionation factors α7Li/6Li range from 0.9895 to 0.9923, which translates to a fractionation between aragonite and fluid from −10.5‰ to −7.7‰. The within-sample δ7Li range determined by SIMS is up to 27‰, exceeding the difference between bulk δ7Li analyses of different aragonite precipitates. Moreover, the centers of aragonite hemispherical bundles (spherulites) are enriched in Li/Ca and Mg/Ca relative to spherulite fibers by up to factors of 2 and 8, respectively. The Li/Ca and Mg/Ca ratios of spherulite fibers increase with aragonite precipitation rate. These results suggest that precipitation rate is a potentially important consideration when using Li isotopes and elemental ratios in natural carbonates as a proxy for seawater composition and temperature.

Description: Ancient zircons from Western Australia's Jack Hills preserve a record of conditions that prevailed on Earth not long after its formation. Widely considered to have been a uniquely violent period geodynamically, the Hadean Eon [4.5 to 4.0 billion years ago (Ga)] has recently been interpreted by some as far more benign-possibly even characterized by oceans like those of the present day. Knowledge of the crystallization temperatures of the Hadean zircons is key to this debate. A thermometer based on titanium content revealed that these zircons cluster strongly at approximately 700 degrees C, which is indistinguishable from temperatures of granitoid zircon growth today and strongly suggests a regulated mechanism producing zircon-bearing rocks during the Hadean. The temperatures substantiate the existence of wet, minimum-melting conditions within 200 million years of solar system formation. They further suggest that Earth had settled into a pattern of crust formation, erosion, and sediment recycling as early as 4.35 Ga.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Watson, E B -- Harrison, T M -- New York, N.Y. -- Science. 2005 May 6;308(5723):841-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Earth and Environmental Sciences, Rensselaer Polytechnic Institute, Troy, NY 12180, USA. watsoe@rpi.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15879213" target="_blank"〉PubMed〈/a〉

Description: Magmatic outgassing of volatiles from Earth's interior probably played a critical part in determining the composition of the earliest atmosphere, more than 4,000 million years (Myr) ago. Given an elemental inventory of hydrogen, carbon, nitrogen, oxygen and sulphur, the identity of molecular species in gaseous volcanic emanations depends critically on the pressure (fugacity) of oxygen. Reduced melts having oxygen fugacities close to that defined by the iron-wustite buffer would yield volatile species such as CH(4), H(2), H(2)S, NH(3) and CO, whereas melts close to the fayalite-magnetite-quartz buffer would be similar to present-day conditions and would be dominated by H(2)O, CO(2), SO(2) and N(2) (refs 1-4). Direct constraints on the oxidation state of terrestrial magmas before 3,850 Myr before present (that is, the Hadean eon) are tenuous because the rock record is sparse or absent. Samples from this earliest period of Earth's history are limited to igneous detrital zircons that pre-date the known rock record, with ages approaching approximately 4,400 Myr (refs 5-8). Here we report a redox-sensitive calibration to determine the oxidation state of Hadean magmatic melts that is based on the incorporation of cerium into zircon crystals. We find that the melts have average oxygen fugacities that are consistent with an oxidation state defined by the fayalite-magnetite-quartz buffer, similar to present-day conditions. Moreover, selected Hadean zircons (having chemical characteristics consistent with crystallization specifically from mantle-derived melts) suggest oxygen fugacities similar to those of Archaean and present-day mantle-derived lavas as early as approximately 4,350 Myr before present. These results suggest that outgassing of Earth's interior later than approximately 200 Myr into the history of Solar System formation would not have resulted in a reducing atmosphere.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Trail, Dustin -- Watson, E Bruce -- Tailby, Nicholas D -- England -- Nature. 2011 Nov 30;480(7375):79-82. doi: 10.1038/nature10655.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Earth and Environmental Sciences, Rensselaer Polytechnic Institute, Troy, New York 12180, USA. traild@rpi.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22129728" target="_blank"〉PubMed〈/a〉

Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Gleick, P H -- Adams, R M -- Amasino, R M -- Anders, E -- Anderson, D J -- Anderson, W W -- Anselin, L E -- Arroyo, M K -- Asfaw, B -- Ayala, F J -- Bax, A -- Bebbington, A J -- Bell, G -- Bennett, M V L -- Bennetzen, J L -- Berenbaum, M R -- Berlin, O B -- Bjorkman, P J -- Blackburn, E -- Blamont, J E -- Botchan, M R -- Boyer, J S -- Boyle, E A -- Branton, D -- Briggs, S P -- Briggs, W R -- Brill, W J -- Britten, R J -- Broecker, W S -- Brown, J H -- Brown, P O -- Brunger, A T -- Cairns, J Jr -- Canfield, D E -- Carpenter, S R -- Carrington, J C -- Cashmore, A R -- Castilla, J C -- Cazenave, A -- Chapin, F S 3rd -- Ciechanover, A J -- Clapham, D E -- Clark, W C -- Clayton, R N -- Coe, M D -- Conwell, E M -- Cowling, E B -- Cowling, R M -- Cox, C S -- Croteau, R B -- Crothers, D M -- Crutzen, P J -- Daily, G C -- Dalrymple, G B -- Dangl, J L -- Darst, S A -- Davies, D R -- Davis, M B -- De Camilli, P V -- Dean, C -- DeFries, R S -- Deisenhofer, J -- Delmer, D P -- DeLong, E F -- DeRosier, D J -- Diener, T O -- Dirzo, R -- Dixon, J E -- Donoghue, M J -- Doolittle, R F -- Dunne, T -- Ehrlich, P R -- Eisenstadt, S N -- Eisner, T -- Emanuel, K A -- Englander, S W -- Ernst, W G -- Falkowski, P G -- Feher, G -- Ferejohn, J A -- Fersht, A -- Fischer, E H -- Fischer, R -- Flannery, K V -- Frank, J -- Frey, P A -- Fridovich, I -- Frieden, C -- Futuyma, D J -- Gardner, W R -- Garrett, C J R -- Gilbert, W -- Goldberg, R B -- Goodenough, W H -- Goodman, C S -- Goodman, M -- Greengard, P -- Hake, S -- Hammel, G -- Hanson, S -- Harrison, S C -- Hart, S R -- Hartl, D L -- Haselkorn, R -- Hawkes, K -- Hayes, J M -- Hille, B -- Hokfelt, T -- House, J S -- Hout, M -- Hunten, D M -- Izquierdo, I A -- Jagendorf, A T -- Janzen, D H -- Jeanloz, R -- Jencks, C S -- Jury, W A -- Kaback, H R -- Kailath, T -- Kay, P -- Kay, S A -- Kennedy, D -- Kerr, A -- Kessler, R C -- Khush, G S -- Kieffer, S W -- Kirch, P V -- Kirk, K -- Kivelson, M G -- Klinman, J P -- Klug, A -- Knopoff, L -- Kornberg, H -- Kutzbach, J E -- Lagarias, J C -- Lambeck, K -- Landy, A -- Langmuir, C H -- Larkins, B A -- Le Pichon, X T -- Lenski, R E -- Leopold, E B -- Levin, S A -- Levitt, M -- Likens, G E -- Lippincott-Schwartz, J -- Lorand, L -- Lovejoy, C O -- Lynch, M -- Mabogunje, A L -- Malone, T F -- Manabe, S -- Marcus, J -- Massey, D S -- McWilliams, J C -- Medina, E -- Melosh, H J -- Meltzer, D J -- Michener, C D -- Miles, E L -- Mooney, H A -- Moore, P B -- Morel, F M M -- Mosley-Thompson, E S -- Moss, B -- Munk, W H -- Myers, N -- Nair, G B -- Nathans, J -- Nester, E W -- Nicoll, R A -- Novick, R P -- O'Connell, J F -- Olsen, P E -- Opdyke, N D -- Oster, G F -- Ostrom, E -- Pace, N R -- Paine, R T -- Palmiter, R D -- Pedlosky, J -- Petsko, G A -- Pettengill, G H -- Philander, S G -- Piperno, D R -- Pollard, T D -- Price, P B Jr -- Reichard, P A -- Reskin, B F -- Ricklefs, R E -- Rivest, R L -- Roberts, J D -- Romney, A K -- Rossmann, M G -- Russell, D W -- Rutter, W J -- Sabloff, J A -- Sagdeev, R Z -- Sahlins, M D -- Salmond, A -- Sanes, J R -- Schekman, R -- Schellnhuber, J -- Schindler, D W -- Schmitt, J -- Schneider, S H -- Schramm, V L -- Sederoff, R R -- Shatz, C J -- Sherman, F -- Sidman, R L -- Sieh, K -- Simons, E L -- Singer, B H -- Singer, M F -- Skyrms, B -- Sleep, N H -- Smith, B D -- Snyder, S H -- Sokal, R R -- Spencer, C S -- Steitz, T A -- Strier, K B -- Sudhof, T C -- Taylor, S S -- Terborgh, J -- Thomas, D H -- Thompson, L G -- Tjian, R T -- Turner, M G -- Uyeda, S -- Valentine, J W -- Valentine, J S -- Van Etten, J L -- van Holde, K E -- Vaughan, M -- Verba, S -- von Hippel, P H -- Wake, D B -- Walker, A -- Walker, J E -- Watson, E B -- Watson, P J -- Weigel, D -- Wessler, S R -- West-Eberhard, M J -- White, T D -- Wilson, W J -- Wolfenden, R V -- Wood, J A -- Woodwell, G M -- Wright, H E Jr -- Wu, C -- Wunsch, C -- Zoback, M L -- Howard Hughes Medical Institute/ -- New York, N.Y. -- Science. 2010 May 7;328(5979):689-90. doi: 10.1126/science.328.5979.689.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20448167" target="_blank"〉PubMed〈/a〉

Description: The intrinsic self-diffusion coefficient (D) for cesium-134 in a granitic melt containing 6.1 to 6.3 percent (by weight) of dissolved H(2)O is three to four orders of magnitude higher than the values reported for chemically similar but dry granitic glass. For the temperature interval 700 degrees to 800 degrees C and a confining pressure of 2 kilobars, cesium diffusivity is given by D = 7.19 x 10(-5) exp (- 19.52 x 10(3)/RT), where R is the gas constant and T is the absolute temperature; the activation energy of about 20 kilocalories per mole is less than half the value for H(2)O-free glass. The observed increase in ionic mobility that accompanies solution of H(2)O implies sharply reduced equilibration times for chemical processes that occur in H(2)2O-bearing silicate melts.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Watson, E B -- New York, N.Y. -- Science. 1979 Sep 21;205(4412):1259-60.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17750147" target="_blank"〉PubMed〈/a〉

Description: Author Posting. © American Geophysical Union, 2006. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 7 (2006): Q11004, doi:10.1029/2005GC001216.

Description: The Sr/Ca ratio of biogenic carbonate is widely used as a proxy for paleotemperature. This application is supported by empirical calibrations of Sr/Ca as a function of temperature, but it is also known that Sr uptake in calcite gauged by KdSr=(Sr/Ca)calcite/(Sr/Ca)solution is affected by other variables, including bulk precipitation rate (Kd Sr increases with increasing precipitation rate). There are no data from controlled experiments specifically addressing the effect of radial growth rate of individual crystals on Kd Sr. For this reason, we conducted two series of experiments to explore Sr partitioning at varying growth rates: (1) growth from a CaCl2–NH4Cl–SrCl2 solution by diffusion of CO2 from an ammonium carbonate source (“drift” experiments) and (2) “drip” precipitation of calcite on a substrate, using a steady flow of CaCl2–SrCl2 and Na2CO3 solutions, mixed just before passage through a tube and dripped onto a glass slide precoated with calcite (“cave-type” experiments). The growth rates of individual crystals were determined by periodic monitoring of crystal size through time or, roughly, by comparison of the final size with the duration of the experiment. Electron microprobe analyses across sectioned crystals grown in the drift experiments show that the concentration of Sr is high in the center (where radial growth rates are highest) and decreases systematically toward the edge. The center-to-edge drop in Sr concentration is a consequence of the slowing radial growth rate as individual crystals become larger. In general, high crystal growth rate (V) enhances Sr uptake in calcite due to a type of kinetic disequilibrium we refer to as “growth entrapment.” The apparent Kd Sr ranges from 0.12 to 0.35 as V increases from 0.01 nm/s to 1 μm/s at 25°C.

Description: This work was supported by the National Science Foundation through grants EAR-9804794 and EAR-0337481 to E. B. Watson.

Description: Author Posting. © American Geophysical Union, 2011. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 12 (2011): Q03001, doi:10.1029/2010GC003322.

Description: In situ secondary ion mass spectrometry (SIMS) analyses of δ7Li, Li/Ca, and Mg/Ca were performed on five synthetic aragonite samples precipitated from seawater at 25°C at different rates. The compositions of δ7Li in bulk aragonites and experimental fluids were measured by multicollector inductively coupled plasma–mass spectrometry (MC-ICP-MS). Both techniques yielded similar δ7Li in aragonite when SIMS analyses were corrected to calcium carbonate reference materials. Fractionation factors α7Li/6Li range from 0.9895 to 0.9923, which translates to a fractionation between aragonite and fluid from −10.5‰ to −7.7‰. The within-sample δ7Li range determined by SIMS is up to 27‰, exceeding the difference between bulk δ7Li analyses of different aragonite precipitates. Moreover, the centers of aragonite hemispherical bundles (spherulites) are enriched in Li/Ca and Mg/Ca relative to spherulite fibers by up to factors of 2 and 8, respectively. The Li/Ca and Mg/Ca ratios of spherulite fibers increase with aragonite precipitation rate. These results suggest that precipitation rate is a potentially important consideration when using Li isotopes and elemental ratios in natural carbonates as a proxy for seawater composition and temperature.

Description: SIMS analyses were supported by U.S. NSF, EAR, Instrumentation and Facilities Program. The development of the method for bulk d7Li analysis and the MC‐ICP‐MS measurements were covered by NSF grant EAR/IF‐0318137. Precipitation experiments were supported by NSF through grants OCE‐0402728, OCE‐0527350, and OCE‐0823527 to Glenn Gaetani and Anne Cohen and through grant EAR‐0337481 to Bruce Watson.