{"query": "How do intrinsic and extrinsic factors impact A42 aggregation, and why is drug development challenging for this process?", "pos": "indeed, it has been shown that the dominant mechanism for catalyzing the formation of toxic a42 species is surface-catalyzed secondary nucleation. in other words, once a small but critical concentration of a42 aggregates has been generated through primary nucleation of monomers, surface-catalyzed secondary nucleation becomes the dominant process where the surface of the existing fibrils serve as catalytic sites for the generation of toxic oligomeric species [ 54, 57 ]. furthermore, the role of intrinsic and extrinsic factors on the aggregation process of a42 has been partly unveiled and a great effort has been focused on drug development against a42 aggregation, which has proven to be very difficult [ 100, 101 ]."}
{"query": "Excitons transfer energy and can jump to a higher state, then lose energy quickly, causing them to vanish.", "pos": "this process occurs at high excitation densities when one exciton transfers its energy to another exciton and brings it to a higher-energy excited state. the higher-energy excited state relaxes rapidly, and overall an exciton is lost. in so far as quenching occurs throughout the volume of the sample, this measurement resembles volume quenching, but with excitons acting as their own quenchers. in these experiments, typically high light intensities are used, far higher than used under solar illumination conditions, and the consequences of this have to be taken into account when analyzing the data."}
{"query": "Causes of artifacts?", "pos": "however, a limiting step in the measurements of the intrinsic young s modulus of amyloid fibrillar aggregates on a surface is the correct evaluation of the cross-sectional moment of inertia i. recently, it was presented a general approach based on theory of elasticity and an innovative calculation of the polymorphic fibrillar aggregates cross-sectional moment of inertia i in order to evaluate correctly the nanomechanical properties of amyloids. this method enables to calculate bending rigidities b and matching the measured experimental values of young s modulus of amyloid fibrils [ 149, 165 ]. however, fibril imaging by afm requires deposition on a surface and drying, which can potentially lead to artifacts in the evaluation of the persistence length and bending rigidity."}
