Processes of water condensation and desublimation on solid surfaces are ubiquitous in nature and essential for various industrial applications, which are crucial for their performance. Despite their significance, these processes are not well understood due to the lack of methods that can provide insight at the nanolevel into the very first stages of phase transitions. Taking advantage of synchrotron grazing-incidence wide-angle X-ray scattering (GIWAXS) and environmental scanning electron microscopy (ESEM), two pathways of the frosting process from supersaturated vapors were studied in real time for substrates with different wettabilities ranging from highly hydrophilic to superhydrophobic.
View Article and Find Full Text PDFThe tear film lipid layer (TFLL) is a unique biological membrane that serves a pivotal role in the maintenance of ocular surface health. Reaching an overarching understanding of the functional principle of the TFLL has been hampered by a lack of insights into the structural and functional roles played by individual lipid classes. To bridge this knowledge gap, we herein focus on studying films formed by principal lipid classes by surface scattering methods.
View Article and Find Full Text PDFMany ionic surfactants, such as sodium dodecyl sulfate (SDS) crystallize out of solution if the temperature falls below the crystallization boundary. The crystallization temperature is impacted by solution properties and can be decreased with the addition of salt. We studied SDS crystallization at liquid/vapor interfaces from solutions at high ionic strength (sodium chloride).
View Article and Find Full Text PDFInterfaces in perovskite solar cells (PSCs) play a pivotal role in determining device performance by influencing charge transport and recombination. Understanding the physical processes at these interfaces is essential for achieving high-power conversion efficiency in PSCs. Particularly, the interfaces involving oxide-based transport layers are susceptible to defects like dangling bonds, excess oxygen, or oxygen deficiency.
View Article and Find Full Text PDFThe SIRIUS beamline of Synchrotron SOLEIL is dedicated to X-ray scattering and spectroscopy of surfaces and interfaces, covering the tender to mid-hard X-ray range (1.1-13 keV). The beamline has hosted a wide range of experiments in the field of soft interfaces and beyond, providing various grazing-incidence techniques such as diffraction and wide-angle scattering (GIXD/GIWAXS), small-angle scattering (GISAXS) and X-ray fluorescence in total reflection (TXRF).
View Article and Find Full Text PDFGrazing incidence wide angle X-ray scattering measurements on aligned titanium oxide nanowires displaying anisotropic optical-electronic properties are carried out. Elemental and thermal analyses provide a chemical composition corresponding to HTiO·HO with ≈ 1 while the crystallographic data indicate a monoclinic cell with a lamellar substructure. Cell parameters are close to those of HTiO notwithstanding a doubling of the lattice in the layer plane.
View Article and Find Full Text PDFThe mechanical properties of a disordered heterogeneous medium depend, in general, on a complex interplay between multiple length scales. Connecting local interactions to macroscopic observables, such as stiffness or fracture, is thus challenging in this type of material. Here, we study the properties of a cohesive granular material composed of glass beads held together by soft polymer bridges.
View Article and Find Full Text PDFHypothesis: Interaction of cellular membranes with biointerfaces is of vital importance for a number of medical devices and implants. Adhesiveness of these surfaces and cells is often regulated by depositing a layer of bovine serum albumin (BSA) or other protein coatings. However, anomalously large separations between phospholipid membranes and the biointerfaces in various conditions and buffers have been observed, which could not be understood using available theoretical arguments.
View Article and Find Full Text PDFJ Colloid Interface Sci
September 2021
The proton pump transmembrane protein bacteriorhodopsin was successfully incorporated into planar floating lipid bilayers in gel and fluid phases, by applying a detergent-mediated incorporation method. The method was optimized on single supported bilayers by using quartz crystal microbalance, atomic force and fluorescence microscopy techniques. Neutron and X-ray reflectometry were used on both single and floating bilayers with the aim of determining the structure and composition of this membrane-protein system before and after protein reconstitution at sub-nanometer resolution.
View Article and Find Full Text PDFWe investigate the interaction between highly charged lipid bilayers in the presence of monovalent counterions. Neutron and X-ray reflectivity experiments show that the water layer between like-charged bilayers is thinner than for zwitterionic lipids, demonstrating the existence of counterintuitive electrostatic attractive interaction between them. Such attraction can be explained by taking into account the correlations between counterions within the Strong Coupling limit, which falls beyond the classical Poisson-Boltzmann theory of electrostatics.
View Article and Find Full Text PDFThere are very few techniques to reconstruct the shape of a cell at nanometric resolution, and those that exist are almost exclusively based on fluorescence, implying limitations due to staining constraints and artifacts. Reflection interference contrast microscopy (RICM), a label-free technique, permits the measurement of nanometric distances between refractive objects. However, its quantitative application to cells has been largely limited due to the complex interferometric pattern caused by multiple reflections on internal or thin structures like lamellipodia.
View Article and Find Full Text PDFWe study experimentally the fracture mechanisms of a model cohesive granular medium consisting of glass beads held together by solidified polymer bridges. The elastic response of this material can be controlled by changing the cross-linking of the polymer phase, for example. Here we show that its fracture toughness can be tuned over an order of magnitude by adjusting the stiffness and size of the polymer bridges.
View Article and Find Full Text PDFBy mixing glass beads with a curable polymer we create a well-defined cohesive granular medium, held together by solidified, and hence elastic, capillary bridges. This material has a geometry similar to a wet packing of beads, but with an additional control over the elasticity of the bonds holding the particles together. We show that its mechanical response can be varied over several orders of magnitude by adjusting the size and stiffness of the bridges, and the size of the particles.
View Article and Find Full Text PDFThe effect of ac electric fields on the elasticity of supported lipid bilayers is investigated at the microscopic level using grazing incidence synchrotron x-ray scattering. A strong decrease in the membrane tension up to 1 mN/m and a dramatic increase of its effective rigidity up to 300 k_{B}T are observed for local electric potentials seen by the membrane ≲1 V. The experimental results are analyzed using detailed electrokinetic modeling and nonlinear Poisson-Boltzmann theory.
View Article and Find Full Text PDFUnderstanding interactions between membranes requires measurements on well-controlled systems close to natural conditions, in which fluctuations play an important role. We have determined, by grazing incidence X-ray scattering, the interaction potential between two lipid bilayers, one adsorbed on a solid surface and the other floating close by. We find that interactions in this highly hydrated model system are two orders of magnitude softer than in previously reported work on multilayer stacks.
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