Polymer Nanocomposite Materials Based on Carbon Nanotubes

(Invited Book Chapter

Thermal Transport in Micro- and Nanoscale Systems

Small-scale (micro-/nanoscale) heat transfer has broad and exciting range of applications. Heat transfer at small scale quite naturally is influenced – sometimes dramatically – with high surface area-to-volume ratios. This in effect means that heat transfer in small-scale devices and systems is influenced by surface treatment and surface morphology. Importantly, interfacial dynamic effects are at least non-negligible, and there is a strong potential to engineer the performance of such devices using the progress in micro- and nanomanufacturing technologies. With this motivation, the emphasis here is on heat conduction and convection. The chapter starts with a broad introduction to Boltzmann transport equation which captures the physics of small-scale heat transport, while also outlining the differences between small-scale transport and classical macroscale heat transport. Among applications, examples are thermoelectric and thermal interface materials where micro- and nanofabrication have led to impressive figure of merits and thermal management performance. Basic of phonon transport and its manipulation through nanostructuring materials are discussed in detail. Small-scale single-phase convection and the crucial role it has played in developing the thermal management solutions for the next generation of electronics and energy-harvesting devices are discussed as the next topic. Features of microcooling platforms and physics of optimized thermal transport using microchannel manifold heat sinks are discussed in detail along with a discussion of how such systems also facilitate use of low-grade, waste heat from data centers and photovoltaic modules. Phase change process and their control using surface micro-/nanostructure are discussed next. Among the feature considered, the first are microscale heat pipes where capillary effects play an important role. Next the role of nanostructures in controlling nucleation and mobility of the discrete phase in two-phase processes, such as boiling, condensation, and icing is explained in great detail. Special emphasis is placed on the limitations of current surface and device manufacture technologies while also outlining the potential ways to overcome them. Lastly, the chapter is concluded with a summary and perspective on future trends and, more importantly, the opportunities for new research and applications in this exciting field

Analyst information precision and small earnings surprises

This study proposes and tests an alternative to the extant earnings management explanation for zero and small positive earnings surprises (i.e., analyst forecast errors). We argue that analysts’ ability to strategically induce slight pessimism in earnings forecasts varies with the precision of their information. Accordingly, we predict that the probability that a firm reports a small positive instead of a small negative earnings surprise is negatively related to earnings forecast uncertainty, and we present evidence consistent with this prediction. Our findings have important implications for the earnings management interpretation of the asymmetry around zero in the frequency distribution of earnings surprises. We demonstrate how empirically controlling for earnings forecast uncertainty can materially change inferences in studies that employ the incidence of zero and small positive earnings surprises to categorize firms as suspected of managing earnings

Nanocomposites Derived from Molybdenum Disulfide and an Organoiron Dendrimer

In the quest for new materials, intercalated nanocomposites consisting of molybdenum disulfide (MoS2) and an organometallic dendrimer were synthesized by exploiting the exfoliating/restacking properties of lithiated MoS2 (LiMoS2). By changing the molar ratio of the dendrimer to the LiMoS2, the amount of dendrimer intercalated within the restacked MoS2 was controlled. The molar ratio of the dendrimer to the LiMoS2 influenced the interlayer spacing of the intercalated material. For instance, we found an increase in the interlayer spacing of the nanocomposite when the mole ratio of dendrimer to LiMoS2 in the reaction mixture was changed from 1:1 to 2:1. In addition, the average size of the crystallite decreased as the mole ratio of the dendrimer to LiMoS2 was increased. Specifically, a change from 1: 2 to 2: 1 resulted in a noticeable decrease from 313 to 175 A. The reported nanocomposites are unique being the first system derived from MoS2 and an organometallic dendrimer