Carbon nanotubes have unprecedented mechanical properties as defect-free nanoscale building blocks, but their potential has not been fully realized in composite materials due to weakness at the interfaces. Here we demonstrate that through load-transfer-favored three-dimensional architecture and molecular level couplings with polymer chains, true potential of CNTs can be realized in composites as initially envisioned. Composite fibers with reticulate nanotube architectures show order of magnitude improvement in strength compared to randomly dispersed short CNT reinforced composites reported before. The molecular level couplings between nanotubes and polymer chains results in drastic differences in the properties of thermoset and thermoplastic composite fibers, which indicate that conventional macroscopic composite theory fails to explain the overall hybrid behavior at nanoscale.To build composites with superior strength and flawtolerance, nanoscale reinforcements have natural advantages than their micrometer-sized counterparts because of their paucity of structural defects and high aspect ratio.1 However, a huge challenge still lies in the manufacturing of a highperformance nanocomposite because of the agglomeration tendency of the nanometer-sized fillers and poor load transfer efficiency between the matrix and reinforcements. A good example is carbon nanotube (CNT) reinforced composites. Although individual CNTs have Young's modulus of 1 TPa and strength over 60 GPa, 2,3 to date CNT reinforced polymer composites fabricated by mixing polymers and nanotubes have shown only moderate enhancement in modulus and even more limited improvements in strength. 4 Even in the cases where CNTs are optimally dispersed at high volume fraction, their moduli and strengths are at least 2 orders of magnitude lower than what was theoretically predicted by composite theory. [5][6][7] Essentially, the mechanical performance of CNT reinforced composites relies on the load-bearing status of the CNTs in the matrix. However, two inherent problems of CNTs shadow their promise as efficient load-bearers. One is their waviness. A multiwalled carbon nanotube with a diameter of 10 nm is 10 12 times easier to be bent than a

Ion beams are relevant for radiobiological studies and for tumor therapy. In contrast to conventional accelerators, laser-driven ion acceleration offers a potentially more compact and cost-effective means of delivering ions for radiotherapy. Here, we show that by combining advanced acceleration using nanometer thin targets and beam transport, truly nanosecond quasi-monoenergetic proton bunches can be generated with a table-top laser system, delivering single shot doses up to 7 Gy to living cells. Although in their infancy, laser-ion accelerators allow studying fast radiobiological processes as demonstrated here by measurements of the relative biological effectiveness of nanosecond proton bunches in human tumor cells.

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