Probing Orientations and Conformations of Peptides and Proteins at Buried Interfaces

2021 ◽  
pp. 10144-10155
Author(s):  
Wen Guo ◽  
Tieyi Lu ◽  
Zahra Gandhi ◽  
Zhan Chen
Keyword(s):  
Buried Interfaces

Direct Measurement of Charge Reversal on Lipid Bilayers using Heterodyne-Detected Second Harmonic Generation Spectroscopy

2019 ◽  
Author(s):  
HanByul Chang ◽  
Paul Ohno ◽  
Yangdongling Liu ◽  
Franz Geiger
Keyword(s):  
Lipid Bilayers ◽  
Surface Potential ◽  
Second Harmonic ◽  
Fluid Phase ◽  
Cationic Polyelectrolyte ◽  
Charge Reversal ◽  
Buried Interfaces ◽  
Phase Transition Temperatures ◽  
Complementary Techniques ◽  
Order Susceptibility

We report the detection of charge reversal induced by the adsorption of a cationic polyelectrolyte, poly(allylamine) hydrochloride (PAH), to buried supported lipid bilayers (SLBs), used as idealized model biological membranes. We observe changes in the surface potential in isolation from other contributors to the total SHG response by extracting the phase-shifted potential-dependent third-order susceptibility from the overall SHG signal. We demonstrate the utility of this technique in detecting both the sign of the surface potential and the point of charge reversal at buried interfaces without any prior information or complementary techniques<i>.</i>Furthermore, isolation of the second-order susceptibility contribution from the overall SHG response allows us to directly monitor changes in the Stern Layer. Finally, we characterize the Stern and Diffuse Layers over single-component SLBs formed from three different zwitterionic lipids of different gel-to-fluid phase transition temperatures (T<sub>m</sub>s). We determine whether the surface potential changes with the physical phase state (gel, transitioning, or fluid) of the SLB and incorporate 20 percent of negatively charged lipids to the zwitterionic SLB to investigate how the surface potential changes with surface charge.

scholarly journals The Force Cone Method Applied to Explain Hidden Whirls in Tribology

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3894
Author(s):  
Claus Mattheck ◽  
Christian Greiner ◽  
Klaus Bethge ◽  
Iwiza Tesari ◽  
Karlheinz Weber
Keyword(s):  
Finite Element ◽  
Free Surface ◽  
Simple Model ◽  
Alternative Explanation ◽  
Model Experiments ◽  
Complex Processes ◽  
Buried Interfaces ◽  
Internal Structures ◽  
Ideal Tool ◽  
Acting Force

In tribologically loaded materials, folding instabilities and vortices lead to the formation of complex internal structures. This is true for geological as well as nanoscopic contacts. Classically, these structures have been described by Kelvin–Helmholtz instabilities or shear localization. We here introduce an alternative explanation based on an intuitive approach referred to as the force cone method. It is considered how whirls are situated near forces acting on a free surface of an elastic or elastoplastic solid. The force cone results are supplemented by finite element simulations. Depending on the direction of the acting force, one or two whirls are predicted by the simplified force cone method. In 3D, there is always a ring shaped whirl present. These modelling findings were tested in simple model experiments. The results qualitatively match the predictions and whirl formation was found. The force cone method and the experiments may seem trivial, but they are an ideal tool to intuitively understand the presence of whirls within a solid under a tribological load. The position of these whirls was found at the predicted places and the force cone method allows a direct approach to understand the complex processes in the otherwise buried interfaces of tribologically loaded materials.

Study of buried interfaces in Fe/Si multilayer by hard x‐ray emission spectroscopy

2021 ◽  
Author(s):  
Hina Verma ◽  
Karine Le Guen ◽  
Renaud Delaunay ◽  
Iyas Ismail ◽  
Vita Ilakovac ◽  
...  
Keyword(s):  
Emission Spectroscopy ◽  
X Ray ◽  
Buried Interfaces

Element-specific structural analysis of Si/B4C using resonant X-ray reflectivity

2015 ◽  
Vol 48 (3) ◽  
pp. 786-796 ◽  
Author(s):  
Maheswar Nayak ◽  
P. C. Pradhan ◽  
G. S. Lodha
Keyword(s):  
Thin Film ◽  
Spatial Distribution ◽  
Structural Analysis ◽  
Chemical Changes ◽  
X Ray ◽  
Buried Interfaces ◽  
Smooth Interface ◽  
Specific Composition ◽  
Applied Fields ◽  
Spatial Modulations

Element-specific structural analysis at the buried interface of a low electron density contrast system is important in many applied fields. The analysis of nanoscaled Si/B4C buried interfaces is demonstrated using resonant X-ray reflectivity. This technique combines information about spatial modulations of charges provided by scattering, which is further enhanced near the resonance, with the sensitivity to electronic structure provided by spectroscopy. Si/B4C thin-film structures are studied by varying the position of B4C in Si layers. Measured values of near-edge optical properties are correlated with the resonant reflectivity profile to quantify the element-specific composition. It is observed that, although Si/B4C forms a smooth interface, there are chemical changes in the sputtered B4C layer. Nondestructive quantification of the chemical changes and the spatial distribution of the constituents is reported.

An access to buried interfaces: the X-ray reflectivity set-up of BL9 at DELTA

2008 ◽  
Vol 15 (6) ◽  
pp. 600-605 ◽  
Author(s):  
Michael Paulus ◽  
Daniela Lietz ◽  
Christian Sternemann ◽  
Kaveh Shokuie ◽  
Florian Evers ◽  
...  
Keyword(s):  
X Ray ◽  
Buried Interfaces ◽  
Set Up

scholarly journals Probing nanoscale behavior of magnetic materials with soft X-ray spectromicroscopy

2012 ◽  
Vol 1 (1) ◽  
pp. 5-15 ◽  
Author(s):  
Peter Fischer ◽  
Charles S. Fadley
Keyword(s):  
Magnetic Properties ◽  
Magnetic Materials ◽  
Spin Dynamics ◽  
Magnetic Nanostructures ◽  
Magnetic Behavior ◽  
Research Area ◽  
X Ray ◽  
Spatially Resolved ◽  
Buried Interfaces ◽  
Analytical Tools

AbstractThe magnetic properties of matter continue to be a vibrant research area driven both by scientific curiosity to unravel the basic physical processes which govern magnetism and the vast and diverse utilization of magnetic materials in current and future devices, e.g., in information and sensor technologies. Relevant length and time scales approach fundamental limits of magnetism and with state-of-the-art synthesis approaches we are able to create and tailor unprecedented properties. Novel analytical tools are required to match these advances and soft X-ray probes are among the most promising ones. Strong and element-specific magnetic X-ray dichroism effects as well as the nanometer wavelength of photons and the availability of fsec short and intense X-ray pulses at upcoming X-ray sources enable unique experimental opportunities for the study of magnetic behavior. This article provides an overview of recent achievements and future perspectives in magnetic soft X-ray spectromicroscopies which permit us to gain spatially resolved insight into the ultrafast spin dynamics and the magnetic properties of buried interfaces of advanced magnetic nanostructures.

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