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@PHDTHESIS{Timmermann:604431,
      author       = {Timmermann, Sonja},
      othercontributors = {Gutt, Christian and Perakis, Foivos},
      title        = {{E}ffects of {X}-ray radiation on structure and dynamics of
                      egg white protein gels},
      school       = {Universität Siegen},
      type         = {Dissertation},
      publisher    = {Universitätsbibliothek Siegen},
      reportid     = {PUBDB-2024-01093},
      pages        = {155},
      year         = {2023},
      note         = {Dissertation, Universität Siegen, 2024},
      abstract     = {The investigation of proteins is highly relevant due to
                      their various functions in living organisms mand their
                      importance in nutrition. A technique that can access the
                      collective dynamics of proteins in solution is X-ray photon
                      correlation spectroscopy ($XPCS$). Using the high coherent
                      fluxes provided by modern X-ray facilities, $XPCS$ can
                      resolve dynamics down to the molecular length scale.
                      However, the proteins' sensitivity to X-ray radiation poses
                      a serious challenge. This thesis uses $XPCS$ at a
                      synchrotron source to systematically investigate the effects
                      of the X-ray dose and the X-ray dose rate on structure and
                      dynamics of protein gels. The protein gels are hen egg
                      whites cooked at thirteen temperatures between 50 and 85
                      °C. At these temperatures, the egg white proteins unfold
                      and interconnect, leading to the formation of a gel network
                      at temperatures ≥ 60 °C. Among these egg white gel
                      networks, we observe differences in the susceptibility to
                      radiation damage. The gels prepared between 63 °C and 70°C
                      are more sensitive to radiation effects, and the gel
                      structure is broken up by X-ray doses of 2 kGy to 8 kGy
                      causing an acceleration of the sample dynamics. The egg
                      white gel networks prepared above 73 °C are strengthened by
                      the denaturated ovalbumin, which increases the dose
                      thresholds for structure and dynamics by one order of
                      magnitude. Like other gels, the cooked egg white gels
                      display ballistic motion where single relaxation events in
                      the network cause directional shifts in the surrounding
                      sites. From the $XPCS$ results, we derive the velocity of
                      this ballistic motion as a function of ten different
                      fluences, revealing a linear dependency of this velocity on
                      the fluence. From this we calculate fluence thresholds above
                      which radiation-induced effects dominate the observed
                      dynamics and find $Φ$$^∗$ = (3$±$2)$×$10$^{−3}$
                      phs$^{−1}$ nm$^{−2}$ for the radiation-sensitive gels
                      prepared at $≤$ 70 °C and $Φ$$^∗$ = (0.9 $±$ 0.3) ph
                      s$^{−1}$ nm$^{−2}$ for those prepared above 70 °C. A
                      comparison to other sample systems suggests a connection
                      between the samples' viscoelasticity and their sensitivity
                      to X-ray radiation effects. This thesis demonstrates how to
                      determine a window of opportunity in terms of dose and dose
                      rate where intrinsic dynamical and structural properties can
                      be measured with $XPCS$. These insights can be used to
                      evaluate new measurement schemes and make use of the
                      improved coherent flux at the next generation of X-ray
                      facilities, which will perspectively also enable $XPCS$
                      measurements on medically highly relevant protein systems.},
      keywords     = {530 Physik (Other) / X-ray photon correlation spectroscopy
                      (Other) / Radiation damage (Other) / Ultra-small angle x-ray
                      scattering (Other) / Protein gels (Other) /
                      Röntgenphotonen-Korrelationsspektroskopie (Other) /
                      Strahlungsschäden (Other) /
                      Ultrakleinwinkel-Röntgenstreuung (Other) / Protein-Gele
                      (Other)},
      cin          = {DOOR ; HAS-User},
      cid          = {I:(DE-H253)HAS-User-20120731},
      pnm          = {6G3 - PETRA III (DESY) (POF4-6G3) / FS-Proposal:
                      II-20210008 (II-20210008) / FS-Proposal: I-20211600
                      (I-20211600) / FS-Proposal: I-20210097 (I-20210097) /
                      05K20PSA - Verbundprojekt 05K2020 - 2019-06075 Protein-Dyn:
                      Dynamik von Proteinen in Lösungen auf multiplen Längen und
                      Zeitskalen (Teilprojekt 1) (BMBF-05K20PSA)},
      pid          = {G:(DE-HGF)POF4-6G3 / G:(DE-H253)II-20210008 /
                      G:(DE-H253)I-20211600 / G:(DE-H253)I-20210097 /
                      G:(DE-Ds200)BMBF-05K20PSA},
      experiment   = {EXP:(DE-H253)P-P10-20150101},
      typ          = {PUB:(DE-HGF)11},
      urn          = {urn:nbn:de:hbz:467-26839},
      doi          = {10.25819/UBSI/10471},
      url          = {https://bib-pubdb1.desy.de/record/604431},
}