Elastomeric carbon nanotube circuits for local strain sensing

We use elastomeric polydimethylsiloxane substrates to strain single-walled carbon nanotubes and modulate their electronic properties, with the aim of developing flexible materials that can sense local strain. We demonstrate micron-scale nanotube devices that can be cycled repeatedly through strains as high as 20% while providing reproducible local strain transduction by via the device resistance. We also compress individual nanotubes, and find they undergo an undulatory distortion with a characteristic spatial period of 100-200 nm. The observed period can be understood by the mechanical properties of nanotubes and the substrate in conjunction with continuum elasticity theory. These could potentially be used to create superlattices within individual nanotubes, enabling novel devices and applications

Cultural Competence: New Conceptual Insights into its Limits and Potential for Addressing Health Disparities

The increasing interest in the role of racism and racialization in health disparities, calls for exploring new paradigms in addressing and eliminating health disparities related to race/ethnicity. Cultural competence is conceptualized as one of the keys ways to address racial/ethnic disparities in public health and healthcare. However, for cultural competence to fulfill this role, it requires a critical understanding of the underlying socio-political and economic processes of power, privilege and institutional racism that create, support and maintain existing health disparities. This paper outlines how the concept of cultural competence can be made more robust, by incorporating concepts such as Public Health Critical Race praxis (PHCR) and cultural humility, to more fully tackle the impact of structural inequities on health disparities

Tomonaga-Luttinger-Liquid Theory of Metallic Carbon Nanotubes with Open Boundaries

Tomonaga-Luttinger-liquid theory is formulated for metallic carbon nanotubes with open boundaries. Both cases of single- and multi-wall nanotubes are discussed. Based on this theory, spatial variation of the charge density from an edge is investigated with taking account of the shift of the chemical potential which expresses the carrier injection to the nanotube. The charge density has the spatially independent part and the oscillatory component. Roles of Coulomb interaction on the amplitude of the oscillation, the wavenumbers of it and the uniform component of the charge density are clarified.Comment: 14 pages, 4 figures, to be published in J. Phys. Soc. Jpn. Vol. 71 (2002) No.1

Novel nano-biosensors for life science systems and their applications in early, accurate, and non-invasive melanoma and other types of cancer detection

Melanoma (the 5th and 6th most common cancer in Caucasian males and females, respectively), is the most severe form of skin cancer, which is often fatal if recognized in its advanced stage. Melanoma is the tumor that originates from melanocytes (the cells that make the pigment melanin), and may develop from a nevus (commonly named "mole"). Clinically, it is very difficult to correctly differentiate nevi with atypical features or dysplastic nevi, and nevi of special sites from melanoma. Clearly, new, more powerful, less invasive, time consuming and expensive tools are needed for an early and accurate detection of melanoma. In order to address this need, we propose a development of a new set of tools, namely, carbon-nanotube-based biosensors for the early and accurate detection of melanoma. Once successful, we will modify and apply this new technology to early and accurately detect other types of cancer

Transport spectroscopy of chemical nanostructures: the case of metallic single-walled carbon nanotubes

Transport spectroscopy, a technique based on current-voltage measurements of individual nanostructures in a three-terminal transistor geometry, has emerged as a powerful new tool to investigate the electronic properties of chemically derived nanostructures. In this review, we discuss the utility of this approach using the recent studies of single-nanotube transistors as an example. Specifically, we discuss how transport measurements can be used to gain detailed insight into the electronic motion in metallic single-walled carbon nanotubes in several distinct regimes, depending on the coupling strength of the contacts to the nanotubes. Measurements of nanotube devices in these different conductance regimes have enabled a detailed analysis of the transport properties, including the experimental determination of all Hartree-Fock parameters that govern the electronic structure of metallic nanotubes and the demonstration of Fabry-Perot resonators based on the interference of electron waves

Shell Filling and Exchange Coupling in Metallic Single-Walled Carbon Nanotubes

We report the characterization of electronic shell filling in metallic single-walled carbon nanotubes by low-temperature transport measurements. Nanotube quantum dots with average conductance ∼(1–2)e^2/h exhibit a distinct four-electron periodicity for electron addition as well as signatures of Kondo and inelastic cotunneling. The Hartree-Fock parameters that govern the electronic structure of metallic nanotubes are determined from the analysis of transport data using a shell-filling model that incorporates the nanotube band structure and Coulomb and exchange interactions

Thermal resistance of the nanoscale constrictions between carbon nanotubes and solid substrates

We have determined the thermal resistance for transferring heat between individual single-walled carbon nanotube devices and solid substrates. Using sapphire and comparing our results to previous results obtained from SiO2, we find that the resistance is dominated by interfacial resistance rather than the spreading resistance of heat for diffusing into the substrate. Our results are in agreement to a recent model for the thermal resistance of nanoscale constrictions. Our results suggest that relatively short contact lengths (~10–30 nm) to a typical solid should be sufficient to transfer heat efficiently into carbon nanotubes, underscoring the potential of carbon nanotubes for nanoscale thermal management

Aharonov-Bohm effect in circular carbon nanotubes

We study the interference of interacting electrons in toroidal single-wall carbon nanotubes coupled to metallic electrodes by tunnel junctions. The dc conductance shows resonant features as a function of the gate voltage and the magnetic field. The conductance pattern is determined by the interaction parameter, which in turn can be cross-checked against the exponents governing the transport at high temperatures. The coordinate dependence of the conductance reflects electron correlations in one-dimensional space.Comment: 2 pages, contributed paper to LT-22, style file phbauth.cls is include