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

Psychological treatment for family members of children with cancer: A systematic review and meta‐analysis

Acceso RestringidoObjective: This meta‐analytical study examined the effects of psychological treat- ments applied to family members of children and adolescents with cancer, as well as the characteristics of the studies that can be associated with their effects. Methods: Four databases were searched between January 1980 and January 2017; the references of the located studies were reviewed, and emails were sent to experts in this topic. Forty articles fulfilled the selection criteria. The standardized mean pretest‐posttest (or pretest–follow‐up) change was used as the effect‐size index for the treatment and control groups. Results: The 40 articles included 40 treatment groups and 21 control groups. When treatment and control pretest‐posttest mean effects were compared, psychological interventions revealed positive, statistically significant results for anxiety (dadj = 0.339) and problem‐solving skills (dadj = 0.385) and, to a lesser extent, for posttraumatic stress (dadj = 0.224). No statistically significant differences were found for mood (dadj = 0.147), acute stress (dadj = −0.010), coping skills (dadj = 0.123), social support (dadj = 0.245), or quality of life (dadj = 0.538). Conclusions: Positive effects of mild to moderate magnitude were found in the posttests for some outcome measures. Behavioral interventions seem to be the most promising. Interventions achieved the best results when they were long in duration and low in intensity and when they were applied to family members with young chil- dren who were undergoing medical treatment. At follow‐up, the intervention benefits were diminished. The application of psychological interventions is recommended to mitigate the negative psychological repercussions in this population