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PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
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UID:UW-Physics-Event-2344
DTSTART:20120316T203000Z
DURATION:PT1H0M0S
DTSTAMP:20260412T041532Z
LAST-MODIFIED:20120312T144746Z
LOCATION:2241 Chamberlin Hall (coffee at 4:30 pm)
SUMMARY:Kelvin\, Pascal\, and mollusk shells\, Physics Department Coll
 oquium\, Pupa Gilbert\, University of Wisconsin-Madison
DESCRIPTION:NacreaEuro"or mother-of-pearlaEuro"the tough\, iridescent 
 biomineral lining the inner side of some mollusk shells\, is composed 
 of aragonite (CaCO3) tablet layers alternating with organic sheets. Ne
 w Polarization-dependent Imaging Contrast (PIC) maps revealed that nac
 re tablets are not co-oriented\, but have a broad distribution of angu
 lar orientations\, as shown by the Gilbert group (1) and subsequently 
 by many others. The angle spread is the full-width of this distributio
 n\, and was found to vary across different species\, and different she
 ll growth environments. Most interestingly\, we found strong correlati
 on between nacre tablet angle spread and environmental temperature (2)
 \, and this has far-reaching consequences: nacre angle spread could be
  used as a thermometer. Analysis of one shell with well-established st
 able oxygen isotope analysis and PIC-mapping validates the nacre therm
 ometer in one modern shell. Once validated on more shells\, modern and
  ancient\, nacre-paleothermometry could be established as the first en
 tirely-physical\, as opposed to chemical\, proxy for temperature (3). 
 But the implications of this finding are more profound: if T is the te
 mperature at which the nacre formed and AS is the measured angle sprea
 d\, then the equation T=26.826+0.051 AS links environment and bio-stru
 cture. This equation suggests that one could predict a biological stru
 cture based on the environment in which the organism forms it.<br>
\n<
 br>
\n1.	RA Metzler\, M Abrecht\, RM Olabisi\, D Ariosa\, CJ Johnson\,
  BH Frazer\, SN Coppersmith\, PUPA Gilbert. Architecture of columnar n
 acre\, and implications for its formation mechanism. Phys. Rev. Lett. 
  98\, 268102\, 2007.<br>
\n2.	IC Olson\, R Kozdon\, JW Valley\, PUPA G
 ilbert. Mollusk shell nacre ultrastructure correlates with environment
 al temperature and pressure. J Am Chem Soc  in press\, 2012.<br>
\n3.	
 IC Olson\, PUPA Gilbert. Nacre as a temperature proxy. RSC Faraday Dis
 cussions  submitted\, 2012.<br>
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URL:https://www.physics.wisc.edu/events/?id=2344
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