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Thermal conductivity of nanocrystalline silicon by direct molecular dynamics simulation J. Appl. Phys. 112, 064305 (2012) Electrical and heat conduction mechanisms of GeTe alloy for phase change memory application J. Appl. Phys. 112, 053712 (2012) Thermal rectification and phonon scattering in silicon nanofilm with cone cavity J. Appl. Phys. 112, 054312 (2012) Analysis of the "3-Omega" method for substrates and thick films of anisotropic thermal conductivity This work describes an experimental study of thermal conductance across multiwalled carbon nanotube ͑CNT͒ array interfaces, one sided ͑Si-CNT-Ag͒ and two sided ͑Si-CNT-CNT-Cu͒, using a photoacoustic technique ͑PA͒. Well-anchored, dense, and vertically oriented multiwalled CNT arrays have been directly synthesized on Si wafers and pure Cu sheets using plasma-enhanced chemical vapor deposition. With the PA technique, the small interface resistances of the highly conductive CNT interfaces can be measured with accuracy and precision. In addition, the PA technique can resolve the one-sided CNT interface component resistances ͑Si-CNT and CNT-Ag͒ and the two-sided CNT interface component resistances ͑Si-CNT, CNT-CNT, and CNT-Cu͒ and can estimate the thermal diffusivity of the CNT layers. The thermal contact resistances of the one-and two-sided CNT interfaces measured using the PA technique are 15.8± 0.9 and 4.0± 0.4 mm 2 K/W, respectively, at moderate pressure. These results compare favorably with those obtained using a steady state, one-dimensional reference bar method; however, the uncertainty range is much narrower. The one-sided CNT thermal interface resistance is dominated by the resistance between the free CNT array tips and their opposing substrate ͑CNT-Ag͒, which is measured to be 14.0± 0.9 mm 2 K / W. The two-sided CNT thermal interface resistance is dominated by the resistance between the free tips of the mating CNT arrays ͑CNT-CNT͒, which is estimated to be 2.1± 0.4 mm 2 K/W.

The rapid development of miniaturized electronic devices has led to a growing need for rechargeable micropower sources with high performance. Among different sources, electrochemical microcapacitors or microsupercapacitors provide higher power density than their counterparts and are gaining increased interest from the research and engineering communities. To date, little work has appeared on the integration of microsupercapacitors onto a chip or flexible substrates. This review provides an overview of research on microsupercapacitors, with particular emphasis on state‐of‐the‐art graphene‐based electrodes and solid‐state devices on both flexible and rigid substrates. The advantages, disadvantages, and performance of graphene‐based microsupercapacitors are summarized and new trends in materials, fabrication and packaging are identified.

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The creation of a sustainable energy generation, storage, and distribution infrastructure represents a global grand challenge that requires massive transnational investments in the research and development of energy technologies that will provide the amount of energy needed on a sufficient scale and timeframe with minimal impact on the environment and have limited economic and societal disruption during implementation. In this opinion paper, we focus on an important set of solar, thermal, and electrochemical energy conversion, storage, and conservation technologies specifically related to recent and prospective advances in nanoscale science and technology that offer high potential in addressing the energy challenge. We approach this task from a two-fold perspective: analyzing the fundamental physicochemical principles and engineering aspects of these energy technologies and identifying unique opportunities enabled by nanoscale design of materials, processes, and systems in order to improve performance and reduce costs. Our principal goal is to establish a roadmap for research and development activities in nanoscale science and technology that would significantly advance and accelerate the implementation of renewable energy technologies. In all cases we make specific recommendations for research needs in the near-term (2-5 years), mid-term (5-10 years) and long-term (>10 years), as well as projecting a timeline for maturation of each technological solution. We also identify a number of priority themes in basic energy science that cut across the entire spectrum Broader contextA major scientific and societal challenge of the 21st century is the conversion from a fossil-fuel-based energy economy to one that is sustainable. The energy challenge before us differs in three ways from past large scale challenges: the first is the large magnitude and relatively short time scale of the transition (a predicted doubling of energy demand by mid-century and a tripling by the end of the century); the second is the need to develop CO 2 -neutral, renewable energy sources; and the third is the cost-competitive aspect of the transition (insofar as the cost of energy to the consumer must be competitive with the fossil fuel energy supply being replaced). What is clear is that the science and engineering research communities working with industry, and policy makers (government, economists, social scientists) will have to educate the citizenry and get them to function collaboratively and globally to enhance the quality of life and to preserve the environment of our planet for future generations. Our team has prepared a technical article on the role of nanotechnology in our energy future aimed at guiding both our own community of scientists and engineers and our policy makers who interface with the public. This journal is ª The Royal Society of Chemistry 2009Energy Environ. Sci., 2009, 2, 559-588 | 559 ANALYSIS www.rsc.org/ees | Energy & Environmental Science of energy conversion, storage, and conservation technologies. We anticipate t...

Networks of single-walled carbon nanotubes (SWCNTs) decorated with Au-coated Pd (Au/Pd) nanocubes are employed as electrochemical biosensors that exhibit excellent sensitivity (2.6 mA mM(-1) cm(-2)) and a low estimated detection limit (2.3 nM) at a signal-to-noise ratio of 3 (S/N = 3) in the amperometric sensing of hydrogen peroxide. Biofunctionalization of the Au/Pd nanocube-SWCNT biosensor is demonstrated with the selective immobilization of fluorescently labeled streptavidin on the nanocube surfaces via thiol linking. Similarly, glucose oxidase (GOx) is linked to the surface of the nanocubes for amperometric glucose sensing. The exhibited glucose detection limit of 1.3 muM (S/N = 3) and linear range spanning from 10 muM to 50 mM substantially surpass similar CNT-based biosensors. These results, combined with the structure's compatibility with a wide range of biofunctionalization procedures, would make the nanocube-SWCNT biosensor exceptionally useful for glucose detection in diabetic patients and well suited for a wide range of amperometric detection schemes for clinically important biomarkers.

A hyperbolically patterned 3D graphene metamaterial (GM) with negative Poisson's ratio and superelasticity is highlighted. It is synthesized by a modified hydrothermal approach and subsequent oriented freeze-casting strategy. GM presents a tunable Poisson's ratio by adjusting the structural porosity, macroscopic aspect ratio (L/D), and freeze-casting conditions. Such a GM suggests promising applications as soft actuators, sensors, robust shock absorbers, and environmental remediation.

An atomistic Green’s function method is developed to simulate phonon transport across a strained germanium (or silicon) thin film between two semi-infinite silicon (or germa-nium) contacts. A plane-wave formulation is employed to handle the translational sym-metry in directions parallel to the interfaces. The phonon transmission function and thermal conductance across the thin film are evaluated for various atomic configurations. The contributions from lattice straining and material heterogeneity are evaluated sepa-rately, and their relative magnitudes are characterized. The dependence of thermal con-ductance on film thickness is also calculated, verifying that the thermal conductance reaches an asymptotic value for very thick films. The thermal boundary resistance of a single Si/Ge interface is computed and agrees well with analytical model predictions. Multiple-interface effects on thermal resistance are investigated, and the results indicate that the first few interfaces have the most significant effect on the overall thermal resistance. DOI: 10.1115/1.270965