TY  - JOUR
A1  - Schröter, M. -A.
A1  - Meyer, S.
A1  - Hahn, M. B.
A1  - Solomun, T.
A1  - Sturm, H.
A1  - Kunte, H. J.
T1  - Ectoine protects DNA from damage by ionizing radiation
JF  - Scientific reports
N2  - Ectoine plays an important role in protecting biomolecules and entire cells against environmental stressors such as salinity, freezing, drying and high temperatures. Recent studies revealed that ectoine also provides effective protection for human skin cells from damage caused by UV-A radiation. These protective properties make ectoine a valuable compound and it is applied as an active ingredient in numerous pharmaceutical devices and cosmetics. Interestingly, the underlying mechanism resulting in protecting cells from radiation is not yet fully understood. Here we present a study on ectoine and its protective influence on DNA during electron irradiation. Applying gel electrophoresis and atomic force microscopy, we demonstrate for the first time that ectoine prevents DNA strand breaks caused by ionizing electron radiation. The results presented here point to future applications of ectoine for instance in cancer radiation therapy.
Y1  - 2017
U6  - https://doi.org/10.1038/s41598-017-15512-4
SN  - 2045-2322
VL  - 7
PB  - Nature Publ. Group
CY  - London
ER  - 
TY  - JOUR
A1  - Schroeter, M-A
A1  - Ritter, M.
A1  - Holschneider, Matthias
A1  - Sturm, H.
T1  - Enhanced DySEM imaging of cantilever motion using artificial structures patterned by focused ion beam techniques
JF  - Journal of micromechanics and microengineering
N2  - We use a dynamic scanning electron microscope (DySEM) to map the spatial distribution of the vibration of a cantilever beam. The DySEM measurements are based on variations of the local secondary electron signal within the imaging electron beam diameter during an oscillation period of the cantilever. For this reason, the surface of a cantilever without topography or material variation does not allow any conclusions about the spatial distribution of vibration due to a lack of dynamic contrast. In order to overcome this limitation, artificial structures were added at defined positions on the cantilever surface using focused ion beam lithography patterning. The DySEM signal of such high-contrast structures is strongly improved, hence information about the surface vibration becomes accessible. Simulations of images of the vibrating cantilever have also been performed. The results of the simulation are in good agreement with the experimental images.
KW  - FIB patterning
KW  - structured cantilever
KW  - AFM
KW  - modal analysis
KW  - DySEM
Y1  - 2016
U6  - https://doi.org/10.1088/0960-1317/26/3/035010
SN  - 0960-1317
SN  - 1361-6439
VL  - 26
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Schröter, M-A
A1  - Holschneider, Matthias
A1  - Sturm, H.
T1  - Analytical and numerical analysis of imaging mechanism of dynamic scanning electron microscopy
JF  - Nanotechnology
N2  - The direct observation of small oscillating structures with the help of a scanning electron beam is a new approach to study the vibrational dynamics of cantilevers and microelectromechanical systems. In the scanning electron microscope, the conventional signal of secondary electrons (SE, dc part) is separated from the signal response of the SE detector, which is correlated to the respective excitation frequency for vibration by means of a lock-in amplifier. The dynamic response is separated either into images of amplitude and phase shift or into real and imaginary parts. Spatial resolution is limited to the diameter of the electron beam. The sensitivity limit to vibrational motion is estimated to be sub-nanometer for high integration times. Due to complex imaging mechanisms, a theoretical model was developed for the interpretation of the obtained measurements, relating cantilever shapes to interaction processes consisting of incident electron beam, electron-lever interaction, emitted electrons and detector response. Conclusions drawn from this new model are compared with numerical results based on the Euler-Bernoulli equation.
Y1  - 2012
U6  - https://doi.org/10.1088/0957-4484/23/43/435501
SN  - 0957-4484
VL  - 23
IS  - 43
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Schröter, M-A
A1  - Sturm, H.
A1  - Holschneider, Matthias
T1  - Phase and amplitude patterns in DySEM mappings of vibrating microstructures
JF  - Nanotechnology
N2  - We use a dynamic scanning electron microscope (DySEM) to analyze the movement of oscillating micromechanical structures. A dynamic secondary electron (SE) signal is recorded and correlated to the oscillatory excitation of scanning force microscope (SFM) cantilever by means of lock-in amplifiers. We show, how the relative phase of the oscillations modulate the resulting real part and phase pictures of the DySEM mapping. This can be used to obtain information about the underlying oscillatory dynamics. We apply the theory to the case of a cantilever in oscillation, driven at different flexural and torsional resonance modes. This is an extension of a recent work (Schroter et al 2012 Nanotechnology 23 435501), where we reported on a general methodology to distinguish nonlinear features caused by the imaging process from those caused by cantilever motion.
Y1  - 2013
U6  - https://doi.org/10.1088/0957-4484/24/21/215701
SN  - 0957-4484
VL  - 24
IS  - 21
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  -