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SUMMARY:WW Kolloquium: On Structural and Compositional Gradients in Mi
 neralized Tissues
UID:497f-e193-2164-20180881@www.fau.de
DESCRIPTION:Prof. Dr. Derk Joester Materials Science and Engineering D
 epartment\, Northwestern University\, Evanston\, IL\, USA “On Struct
 ural and Compositional Gradients in Mineralized Tissues” Mineralized
  tissues are paradigmatic hierarchical materials that reap synergy fro
 m structural and compositional gradients at multiple length scales in 
 ways that are challenging to reproduce by conventional means. My labor
 atory studies the formation\, functional properties\, and degradation 
 of mineralized tissues. We use model systems ranging from single cryst
 alline endoskeletal elements deposited by single cells to the formatio
 n of dental tissues that comprise nanocrystalline and amorphous minera
 ls deposited in complex organic matrices. Applications include the dev
 elopment of bio-inspired materials\, sequestration of 90Sr from nuclea
 r waste\, and improving prophylaxis and minimally invasive interventio
 n in dental care. Herein\, I will focus on dental tissues that are opt
 imized to withstand the forces of mastication and the challenging chem
 ical environment of the oral cavity. For example\, the radula teeth of
  the chiton are capped with a composite made of magnetite (Fe3O4) and 
 a nano-fibrous chitin that allows them to excavate rock. Self-sharpeni
 ng sea urchin teeth use magnesian calcite (CaCO3) at compositions very
  far from equilibrium to maintain an edge. Human tooth enamel is compo
 sed of hydroxylapatite (Ca5(PO4)3OH) crystallites\, thousands of which
  are bundled into rods that are organized in a three-dimensional weave
 \; this provides great fracture resistance and a much-enhanced fatigue
  life but leaves our teeth vulnerable to erosive tooth wear and tooth 
 decay (caries). I will discuss how chemical imaging using UV-laser pul
 sed atom probe tomography (APT)\, electron microscopy\, and synchrotro
 n X-ray techniques has provided deep new insights into the chemistry o
 f nanoscale organic/inorganic interfaces\, presence of amorphous inter
 granular phases\, and complex dopant gradients that are
DTSTART:20250114T160000Z
DTEND:20250114T180000Z
LOCATION:H14 / Zoom
DTSTAMP:20260521T125746Z
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