TY  - JOUR
A1  - Schmitt, Clemens Nikolaus Zeno
A1  - Winter, Alette
A1  - Bertinetti, Luca
A1  - Masic, Admir
A1  - Strauch, Peter
A1  - Harrington, Matthew J.
T1  - Mechanical homeostasis of a DOPA-enriched biological coating from mussels in response to metal variation
JF  - Interface : journal of the Royal Society
N2  - Protein metal coordination interactions were recently found to function as crucial mechanical cross-links in certain biological materials. Mussels, for example, use Fe ions from the local environment coordinated to DOPA-rich proteins to stiffen the protective cuticle of their anchoring byssal attachment threads. Bioavailability of metal ions in ocean habitats varies significantly owing to natural and anthropogenic inputs on both short and geological spatio-temporal scales leading to large variations in byssal thread metal composition; however, it is not clear how or if this affects thread performance. Here, we demonstrate that in natural environments mussels can opportunistically replace Fe ions in the DOPA coordination complex with V and Al. In vitro removal of the native DOPA metal complexes with ethylenediaminetetraacetic acid and replacement with either Fe or V does not lead to statistically significant changes in cuticle performance, indicating that each metal ion is equally sufficient as a DOPA cross-linking agent, able to account for nearly 85% of the stiffness and hardness of the material. Notably, replacement with Al ions also leads to full recovery of stiffness, but only 82% recovery of hardness. These findings have important implications for the adaptability of this biological material in a dynamically changing and unpredictable habitat.
KW  - mussel byssus
KW  - DOPA
KW  - metal coordination
KW  - coating
Y1  - 2015
U6  - https://doi.org/10.1098/rsif.2015.0466
SN  - 1742-5689
SN  - 1742-5662
VL  - 12
IS  - 110
PB  - Royal Society
CY  - London
ER  - 
TY  - JOUR
A1  - Wichura, Henry
A1  - Jacobs, Louis L.
A1  - Lin, Andrew
A1  - Polcyn, Michael J.
A1  - Manthi, Fredrick K.
A1  - Winkler, Dale A.
A1  - Strecker, Manfred
A1  - Clemens, Matthew
T1  - A 17-My-old whale constrains onset of uplift and climate change in east Africa
JF  - Proceedings of the National Academy of Sciences of the United States of America
N2  - Timing and magnitude of surface uplift are key to understanding the impact of crustal deformation and topographic growth on atmospheric circulation, environmental conditions, and surface processes. Uplift of the East African Plateau is linked to mantle processes, but paleoaltimetry data are too scarce to constrain plateau evolution and subsequent vertical motions associated with rifting. Here, we assess the paleotopographic implications of a beaked whale fossil (Ziphiidae) from the Turkana region of Kenya found 740 km inland from the present-day coastline of the Indian Ocean at an elevation of 620 m. The specimen is similar to 17 My old and represents the oldest derived beaked whale known, consistent with molecular estimates of the emergence of modern straptoothed whales (Mesoplodon). The whale traveled from the Indian Ocean inland along an eastward-directed drainage system controlled by the Cretaceous Anza Graben and was stranded slightly above sea level. Surface uplift from near sea level coincides with paleoclimatic change from a humid environment to highly variable and much drier conditions, which altered biotic communities and drove evolution in east Africa, including that of primates.
KW  - east Africa
KW  - Ziphiidae
KW  - uplift
KW  - drainage
KW  - paleoenvironment
Y1  - 2015
U6  - https://doi.org/10.1073/pnas.1421502112
SN  - 0027-8424
VL  - 112
IS  - 13
SP  - 3910
EP  - 3915
PB  - National Acad. of Sciences
CY  - Washington
ER  - 
TY  - JOUR
A1  - Armstrong, Michael R.
A1  - Radousky, Harry B.
A1  - Austin, Ryan A.
A1  - Tschauner, Oliver
A1  - Brown, Shaughnessy
A1  - Gleason, Arianna E.
A1  - Goldman, Nir
A1  - Granados, Eduardo
A1  - Grivickas, Paulius
A1  - Holtgrewe, Nicholas
A1  - Kroonblawd, Matthew P.
A1  - Lee, Hae Ja
A1  - Lobanov, Sergey
A1  - Nagler, Bob
A1  - Nam, Inhyuk
A1  - Prakapenka, Vitali
A1  - Prescher, Clemens
A1  - Reed, Evan J.
A1  - Stavrou, Elissaios
A1  - Walter, Peter
A1  - Goncharov, Alexander F.
A1  - Belof, Jonathan L.
T1  - Highly ordered graphite (HOPG) to hexagonal diamond (lonsdaleite) phase transition observed on picosecond time scales using ultrafast x-ray diffraction
JF  - Journal of applied physics
N2  - The response of rapidly compressed highly oriented pyrolytic graphite (HOPG) normal to its basal plane was investigated at a pressure of & SIM;80 GPa. Ultrafast x-ray diffraction using & SIM;100 fs pulses at the Materials Under Extreme Conditions sector of the Linac Coherent Light Source was used to probe the changes in crystal structure resulting from picosecond timescale compression at laser drive energies ranging from 2.5 to 250 mJ. A phase transformation from HOPG to a highly textured hexagonal diamond structure is observed at the highest energy, followed by relaxation to a still highly oriented, but distorted graphite structure following release. We observe the formation of a highly oriented lonsdaleite within 20 ps, subsequent to compression. This suggests that a diffusionless martensitic mechanism may play a fundamental role in phase transition, as speculated in an early work on this system, and more recent static studies of diamonds formed in impact events. Published by AIP Publishing.
Y1  - 2022
U6  - https://doi.org/10.1063/5.0085297
SN  - 0021-8979
SN  - 1089-7550
VL  - 132
IS  - 5
PB  - AIP Publishing
CY  - Melville
ER  -