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- AFM (1)
- Aquatic grain corrosion (1)
- Biological grain pitting (1)
- Biopitting (1)
- Chemical grain pitting (1)
- Cooperative signaling (1)
- Epoxy (1)
- FRET (1)
- IgG antibodies (1)
- In vivo molecular imaging (1)
Three principally different mechanisms contribute to the wear-down process of mineral aggregates in sedimentary environments: (1) mechanical abrasion by forces of wind and water and by floating or saltating neighbouring grains, (2) chemical attack and dissolution by fluids, and (3) physical bioerosion and chemical biocorrosion. It is however, difficult to attribute the specific surface changes to specific environments and processes. Quartz sand grains from subaerial and subaquatic environments were analysed by atomic force microscopy (AFM) for traces of natural and experimental aeolian, aquatic and biological wear-down processes. Quantitative topographical parameters of surface alterations were extracted from topography data by non-linear methods derived from digital image analysis. These parameters were examined by multivariate statistic, yielding three well-distinguishable groups. Morphological surface alterations dominated by subaerial, subaquatic and by biological impact could be differentiated. The method may also be used for the detection of aeolian, subaquatic, and biological modification of sedimentary grains and rock surfaces in extraterrestrial environments, and for assessment of environmental damage on monuments and buildings.
Boehmite nanoparticles show great potential in improving mechanical properties of fiber reinforced polymers. In order to predict the properties of nanocomposites, knowledge about the material parameters of the constituent phases, including the boehmite particles, is crucial. In this study, the mechanical behavior of boehmite is investigated using Atomic Force Microscopy (AFM) experiments and Molecular Dynamic Finite Element Method (MDFEM) simulations. Young’s modulus of the perfect crystalline boehmite nanoparticles is derived from numerical AFM simulations. Results of AFM experiments on boehmite nanoparticles deviate significantly. Possible causes are identified by experiments on complementary types of boehmite, that is, geological and hydrothermally synthesized samples, and further simulations of imperfect crystals and combined boehmite/epoxy models. Under certain circumstances, the mechanical behavior of boehmite was found to be dominated by inelastic effects that are discussed in detail in the present work.The studies are substantiated with accompanying X-ray diffraction and Raman experiments.
In recent years, much progress has been made in analyzing the molecular origin of many diseases in vivo. For most applications, attention has been devoted to the detection of single molecules only. In this study, we present a proof of concept for the straightforward monitoring of interactions between different molecules via Förster resonance energy transfer (FRET) in an in vivo spectral multiplexing approach using conventional small organic dyes covalently attached to antibodies. Methods: We coupled the fluorophores DY-682 (donor; absorption [abs]/emission [em], 674/712 nm), DY-505 (control donor; abs/em, 498/529 nm), and DY-782 (acceptor; abs/em, 752/795 nm) to the model antibody IgG. The occurrence of FRET between these fluorophores was assessed in vitro for conjugate mixtures adsorbed onto membranes, after accumulation into the phagocytic compartment of macrophages (J774 cells), and in vivo in a mouse edema model using a whole-body animal imaging system with multispectral analysis features. Results: When the free acceptor DY-782 was combined with the DY-682 donor, FRET occurred as a consequence of small dye-to-dye distances, unlike the case for mixtures of the dyes DY-782 and DY-505. Our proof of concept was also transferred to living cells after internalization of the DY-682-IgGDY-782-IgG pair into macrophages and finally to animals, where intermolecular FRET was observed after systemic probe application in vivo in edema-bearing mice. Conclusion: Our simple cooperative-imaging approach enables the noninvasive detection of the presence of two or principally even more neighboring disease-related biomarkers. This finding is of high relevance for the in vivo identification of complex biologic processes requiring strong spatial interrelations of target molecules in key pathologic activation processes such as inflammation, cancer, and neurodegenerative diseases.