Metallic quantum clusters belonging to intermediate size regime between two and few hundred of atoms, represent unique building blocks of new materials. Nonlinear optical (NLO) characteristics of liganded silver and gold quantum clusters reveal remarkable features which can be tuned by size, structure and composition. The two-photon absorption cross sections of liganded noble metal quantum clusters are several orders of magnitude larger than that of commercially-available dyes. Therefore, the fundamental photophysical understanding of those two-photon processes in liganded clusters with few metal atoms deserve special attention, in particularly in context of finding the mechanisms responsible for these properties. A broad range of state-of-the-art experimental methods to determine nonlinear optical properties (i.e. two-photon absorption, two-photon excited fluorescence and second harmonic generation) of quantum clusters are presented. The experimental setup and underlying physical concepts are described.
Furthermore, the theoretical models and corresponding approaches are used allowing to explain the experimental observations and simultaneously offering the possibility to deduce the key factors necessary to design new classes of nanoclusters with large NLO properties. Additionally, selected studied cases of liganded silver and gold quantum clusters with focus on their NLO properties will be presented as promising candidates for applications in imaging techniques such as fluorescence microscopy or Second-Harmonic Generation microscopy.
Sustainable development has become a great concern in modern society. The authors of this brief describe how one strategy to reach this objective is to replace oil-based materials with bio-based materials. They emphasize the great efforts that have been made to synthesize new bio-based polymers or additives or to replace glass fibers by natural fibers in composites. Flame retardancy is one of the most desired properties for many applications in wires and cables, building, transport, electric and electronic devices. The authors of this fascinating and timely brief summarize this important field in three parts. The flame retardancy of biobased polymers, the flame retardancy of natural fibers composites, and the synthesis and efficiency of biobased flame retardants.
This book provides a comprehensive introduction to the thermal issues in photovoltaics. It also offers an extensive overview of the physics involved and insights into possible thermal optimizations of the different photovoltaic device technologies.In general, temperature negatively affects the efficiency of photovoltaic devices. The first chapter describes the temperature-induced losses in photovoltaic devices and reviews the strategies to overcome them. The second chapter introduces the concept of temperature coefficient, the underlying physics and some guidelines for reducing their negative impacts. Subsequent chapters offer a comprehensive and general thermal model of photovoltaic devices, and review how current and emerging technologies, mainly solar cells but also thermophotovoltaic devices, can benefit from thermal optimizations.Throughout the book, the authors argue that the energy yield of photovoltaic devices can be optimized by taking their thermal behavior and operating conditions into consideration in their design.
CRISPR/Cas is a recently described defense system that protects bacteria and archaea against invasion by mobile genetic elements such as viruses and plasmids. A wide spectrum of distinct CRISPR/Cas systems has been identified in at least half of the available prokaryotic genomes. On-going structural and functional analyses have resulted in a far greater insight into the functions and possible applications of these systems, although many secrets remain to be discovered. In this book, experts summarize the state of the art in this exciting field.
This book describes the interaction of living matter with photons, neutrons, charged particles, electrons and ions. The authors are specialists in the field of radiation protection. The book synthesizes many years of experiments with external radiation exposure in the fields of dosimetry and radiation shielding in medical, industrial and research fields. It presents the basic physical concepts including dosimetry and offers a number of tools to be used by students, engineers and technicians to assess the radiological risk and the means to avoid them by calculating the appropriate shields. The theory of radiation interaction in matter is presented together with empirical formulas and abacus. Numerous numerical applications are treated to illustrate the different topics. The state of the art in radiation protection and dosimetry is presented in detail, especially in the field of simulation codes for external exposure to radiation, medical projects and advanced research. Moreover, important data spread in different up to date references are presented in this book. The book deals also with accelerators, X-rays facilities, sealed sources, dosimetry, Monte Carlo simulation and radiation regulation. Each chapter is split in two parts depending on the level of details the readers want to focus on. The first part, accessible to a large public, provides a lot of simple examples to help understanding the physics concepts under radiation external exposure. The second part, called "Additional Information" is not mandatory; it aims on explaining topics more deeply, often using mathematical formulations. The book treats fundamental radiometric and dosimetric quantities to describe the interaction in materials under the aspects of absorbed dose processes in tissues. Definitions and applications on limited and operational radiation protection quantities are given. An important aspect are practical engineering tools in industrial, medical and research domains. Source characterization and shielding design are addressed. Also more "exotic" topics, such as ultra intense laser and new generation accelerators, are treated. The state of the art is presented to help the reader to work with the book in a self-consistent way. The basic knowledge necessary to apply Monte Carlo methods in the field of radiation protection and dosimetry for external radiation exposure is provided. Coverage of topics such as variance reduction, pseudo-random number generation and statistic estimators make the book useful even to experienced Monte Carlo practitioners. Solved problems help the reader to understand the Monte Carlo process. The book is meant to be used by researchers, engineers and medical physicist. It is also valuable to technicians and students.