Micelles formed by the self-assembly of block copolymers in selective solvents have attracted widespread attention and have uses in a wide variety of fields, whereas applications based on their electronic properties are virtually unexplored. Herein we describe studies of solution-processable, low-dispersity, electroactive fibre-like micelles of controlled length from π-conjugated diblock copolymers containing a crystalline regioregular poly(3-hexylthiophene) core and a solubilizing, amorphous regiosymmetric poly(3-hexylthiophene) or polystyrene corona. Tunnelling atomic force microscopy measurements demonstrate that the individual fibres exhibit appreciable conductivity. The fibres were subsequently incorporated as the active layer in field-effect transistors. The resulting charge carrier mobility strongly depends on both the degree of polymerization of the core-forming block and the fibre length, and is independent of corona composition. The use of uniform, colloidally stable electroactive fibre-like micelles based on common π-conjugated block copolymers highlights their significant potential to provide fundamental insight into charge carrier processes in devices, and to enable future electronic applications.
Spider major ampullate silk is often schematically represented as a two-phase material composed of crystalline nanodomains in an amorphous matrix. Here we are interested in revealing its more complex nanoscale organization by probing Argiope bruennichi dragline-type fibers using scanning X-ray nanodiffraction. This allows resolving transversal structural features such as an about 1 μm skin layer composed of around 100 nm diameter nanofibrils serving presumably as an elastic sheath. The core consists of a composite of several nm size crystalline nanodomains with poly(l-alanine) microstructure, embedded in a polypeptide network with short-range order. Stacks of nanodomains separated by less ordered nanosegments form nanofibrils with a periodic axial density modulation which is particularly sensitive to radiation damage. The precipitation of larger β-type nanocrystallites in the outer core-shell is attributed to MaSp1 protein molecules.
Amyloid fibres attract considerable interests due to their biological roles in neurodegenerative diseases and their potentials as functional biomaterials. We describe here a completely new finding about an intrinsic signal of amyloid fibres in the near infrared (NIR) range. When combined with their recently reported blue luminescence, it paves the way toward new blueprints for label-free detections of amyloid deposits within in vitro up to in vivo contexts. The blue luminescence allows for staining-free characterization of amyloid deposits within human samples. The NIR signal offers promising prospects for innovative diagnostic strategies of neurodegenerative diseases; a need to improve medical care and to develop new therapies. As a proof of concept, we demonstrate direct detection of amyloid deposits within brains of living aged "Alzheimer's" mice using non-invasive and contrast agent-free imaging. UV-Vis-NIR optical properties of amyloids opens new research avenues across amyloidoses as well as for next generation biophotonic devices.
One key for understanding the stratification in the deep mantle lies in the determination of the density and structure of matter at high pressures, as well as the density contrast between solid and liquid silicate phases. Indeed, the density contrast is the main control on the entrainment or settlement of matter and is of fundamental importance for understanding the past and present dynamic behavior of the deepest part of the Earth's mantle. Here, we adapted the X-ray absorption method to the small dimensions of the diamond anvil cell, enabling density measurements of amorphous materials to unprecedented conditions of pressure. Our density data for MgSiO 3 glass up to 127 GPa are considerably higher than those previously derived from Brillouin spectroscopy but validate recent ab initio molecular dynamics simulations. A fourth-order Birch-Murnaghan equation of state reproduces our experimental data over the entire pressure regime of the mantle. At the core-mantle boundary (CMB) pressure, the density of MgSiO 3 glass is 5.48 ± 0.18 g/cm 3 , which is only 1.6% lower than that of MgSiO 3 bridgmanite at 5.57 g/cm 3 , i.e., they are the same within the uncertainty. Taking into account the partitioning of iron into the melt, we conclude that melts are denser than the surrounding solid phases in the lowermost mantle and that melts will be trapped above the CMB.silicate glass density | X-ray absorption | basal magma ocean V ariations in seismic velocities observed in the deep mantle could be attributed to melting phenomena (1), accumulation of dense matter (2), core-mantle interactions (3), or even a deep hidden geochemical reservoir that dates from the early differentiation of the Earth (4). Indeed, melting phenomena play a critical role in the formation and evolution of terrestrial planets. In the early Earth's history, large-scale melting events and magma oceans facilitated the segregation of the iron-rich core and the partitioning of elements between the different layers of the Earth (5). Catastrophic events like the moon-forming giant impact may have melted the entire Earth and modified the thermal and chemical state of the planet's interior (6). It has long been thought that the mantle crystallized from the bottom to the top, with crystals being denser than melts (7). However, the formation of a dense basal magma ocean (BMO) at the bottom of the mantle concomitant to the final accretion of the Earth was proposed as a consequence of partial melting (2). The formation of a BMO requires the accumulation of dense iron-rich silicate melts at the core-mantle boundary (CMB). In this scenario, the mantle starts to crystallize at an intermediate depth, and a raft of crystals continues to grow toward both the bottom and top of the mantle. In the modern mantle, seismic observations highlight ultralow velocity zones (ULVZs) near the CMB (8) that may be caused by melting of deep mantle material (9), potentially feeding sources of hot spots. Alternatively, the ULVZs may be dense remnants from an initial BMO (10, 11). Both scenar...
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