Center for Hierarchical Manufacturing

In this letter an experimental method is introduced that allows detection of terahertz (THz) radiation from arrays of joule-heated Single-Walled Carbon Nanotubes (SWCNTs), by coupling this radiation through integrated antennas and a silicon lens. The radiation forms a diffraction-limited beam with a total maximum radiated power of 450 nW, significantly greater than the power estimated from Nyquist thermal noise (8 nW). The physical radiation process is unknown at this stage, but possible explanations for the high radiated power are discussed briefly. The emission has a typical bandwidth of 1.2 THz and can be tuned to different frequencies by changing the dimensions of the antennas. Arrays of the devices could be integrated in CMOS integrated circuits, and find application in THz systems, such as in near-range medical imaging.

The fabrication of nanotechnology enabled devices requires not only the creation and functionalization of well defined nanostructures, but also practical routes for the two and three dimensional integration of these structures with components and systems across multiple length scales. Approaches for the use of self-assembled block copolymer templates to achieve these goals for sub-10 nm elements using either Si wafer or roll to roll processing platforms will be discussed. While the potential for these materials for patterning precision electronics, including high density data storage is an area of active study and great promise, less work has been carried out to adapt these strategies for lower cost per function devices, including solar energy applications and flexible electronics. For example, use of self assembly in roll to roll processes to achieve these goals requires the development of versatile, low cost templates. Recently we reported that nanostructured templates with sub-10 nm domains can be easily obtained through the blending of disordered polymer surfactants containing poly(ethylene oxide) (PEO) as the hydrophilic block with homopolymers including poly (acrylic acid), poly (4-vinyl phenol) and poly (styrene sulfonate) that selectively associate with the PEO block through hydrogen bonding. These inexpensive blends are strongly segregated, yielding well ordered domains. Moreover, the functionalities imparted by the homopolymers provide convenient handles for binding active materials such as nanoparticles and for promoting in situ, phase selective reactions to produce hierarchical metal oxide polymer composites. We have now extended our approach to demonstrate that ordering can likewise be induced by small molecule additives that can undergo multi-point hydrogen bonding with the surfactants. The use of small molecule additives offers additional structural, chemical and functional diversity. The behavior of the template systems and their use for the fabrication of well ordered polymer/nanoparticle, metal oxide/polymer, and metal oxide/polymer/nanoparticle composites will be discussed.

A tcnica de espectroscopia por Ressonncia Magntica Nuclear (NMR) de alta resoluo foi utilizada para estudos estruturais em duas biomolculas: a protena HPr da bactria Staphylococcus aureus, e o peptdeo-C da insulina humana. Ambas esto relacionadas com a regulao da absoro de glicose pelas clulas, no primeiro caso em procariontes, e no segundo em organismos superiores