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Power dissipation in electronic devices is projected to increase over the next 10 years to the range of 150-250 W per chip for high performance applications. One of the primary obstacles to the thermal management of devices operating at such high powers is the thermal resistance between the device and the heat spreader or heat sink that it is attached to. Typically the in situ thermal conductivity of interface materials is in the range of 1-4 W/mK, even though the bulk thermal conductivity of the material may be significantly higher. In an attempt to improve the effective in situ thermal conductivity of interface materials nanoparticles and nanotubes are being considered as a possible addition to such interfaces. This paper presents the results of a numerical study of transport in a thermal interface material that is enhanced with carbon nanotubes. The results from the numerical solution are in excellent agreement with an analytical model (Desai, A., Geer, J., and Sammakia, B., 'Models of Steady Heat Conduction in Multiple Cylindrical Domains,' J. Electron. Packaging (to be published)) of the same geometry. Wide ranges of parametric studies were conducted to examine the effects of the thermal conductivity of the different materials, the geometry, and the size of the nanotubes. An estimate of the effective thermal conductivity of the carbon nanotubes was used, obtained from a molecular dynamics analysis (Mahajan, S., Subbarayan, G., Sammakia, B. G., and Jones, W., 2003, Proceedings of the 2003 ASME International Mechanical Engineering Congress and Exposition, Washington, D.C., Nov. 15-21). The numerical analysis was used to estimate the impact of imperfections in the nanotubes upon the overall system performance. Overall the nanotubes are found to significantly improve the thermal performance of the thermal interface material. The results show that varying the diameter of the nanotube and the percentage of area occupied by the nanotubes does not have any significant effect on the total temperature drop. [DOI: 10.1115/1.2161231] Keywords: thermal management, carbon nanotubes, thermal interface material (TIM), numerical modeling, analytical modeling, molecular dynamic simulations

Fluorescence quenching in solutions of a pendant-functionalized conjugated polymer chemosensor (ttp-PPETE) is evaluated in the presence of a variety of transition metal cations, including Ni(super 2+), Co(super 2+), Cu(super 2+), Fe(super 2+), and Cr(super 6+) is presented. Photophysical characterization for ttp-PPETE includes absorbance, emission, and single-photon counting lifetimes in the absence and presence of varying concentrations of the analytes.

Many organisms exploit highly variable food supplies and, as an adaptation to such conditions, show elevated growth during recovery from starvation. In some species this response enables starved and re-fed individuals to outpace those growing continuously. The main engine of compensatory growth is a relative increase in food ingestion as a reaction to poor nutritional condition. We use a series of mathematical energy-budget models to investigate the interaction between the mechanisms that control such hyperphagia and those that control internal allocation, with the aim of identifying those strategies that permit overcompensation. We find that hyperphagia alone normally produces weak compensation and can never result in overcompensation. When combined with internal allocation, which routes a fixed fraction of net production to reserves, a strong compensatory response becomes the norm, and overcompensation is frequent. Key words: compensatory growth; energy-budget models; hyperphagia; juvenile growth; overcompensation; resource allocation; starvation recovery.

Research has been conducted on ruthenium(II) bipyridyl complexes. The study of the concentration-dependent red shift of the emission and absorption spectra of these complexes has been carried out and the results of NMR experiments demonstrate that this shift is caused by the compounds' equilibration with the aquo complex.

Executive Summary This article presents research findings from a dissertation study that sought to expand the level of knowledge regarding the issue of trust in leadership relationships. Specifically, the research […]

Research has been conducted on the free-base and Zn-porphyrin polymers with the macrocycles separated by the oligo(phenylene vinylene) units of different lengths. The investigation of these polymers via the high-resolution X-ray photoelectron spectroscopy has been carried out and the results are reported.