The fields of nanoscience and nanotechnology are now growing very rapidly. The properties of nanostructures are different to those of the bulk material, due to the high surface area to volume ratio and possible appearance of quantum effects at the nanoscale. The study of size and shape effects upon material properties has therefore attracted enormous attention.This book describes the size effect upon thermal, electrical, magnetic, optical and mechanical properties. It provides a clear overview of size as being a new parameter that permits the tuning of material properties. The book is divided into three parts. The first presents a general overview of the nanoworld. The second describes the synthesis of nanoparticles and how material properties are modified at the nanoscale. The third part concerns the application of nanotechnology in the real world; as nanostructured solar cells and light-emitting diodes. This work comprises 11 chapters written by experts in their respective fields. Chapter 1, by Wautelet, is an introduction to the nanoworld. In Chapter 2, Pan et al. update recent progress made in dealing with coordination-resolved energetic and dynamic behavior of bonds in low-dimensional systems, with consideration of the combined effect of temperature and pressure. In chapter 3, Rodriguez et al. discuss size effect and shape stability of nanoparticles. In Chapter 4, Guisbiers describes how to obtain quantitative information on nanomaterials using thermodynamics. In Chapter 5, Ganguli considers the size effect in disordered nanoparticles. In Chapter 6, Delogu et al. describe how to synthesize nanostructures. In Chapter 7, Yang et al. consider the size effect upon the optical properties of semiconductor nanocrystals. In Chapter 8, Erb discusses the size effect on mechanical properties. In Chapter 9, Zhao et al. examine the size effect on thermal

properties. The last two chapters, by Nanda and Vigil cover applications of nanotechnology; in particular, light-emitting diodes and nanostructured solar cells.This book will be useful to undergraduate as well as graduate students as well as experienced researchers in materials science, physics, chemistry and engineering.