There were two reasons that induced me to plan and to organize this book, the first was the lack of a text entirely devoted to the subject of gas sensors, notwithstanding some books devoted to the various kind of chemical sensors have recently been published. The second reason was the need of introducing the basic topics of gas detection mechanisms to a growing number of researchers active in research and development laboratories of industries and uni versities. The field of chemical sensors is indeed in fast and consistent growth, as it is proved by the increased number of participants to the congresses that were recently held on this subject, namely the Third Meeting on Chemical Sensors (September 24 - 26, 1990, Cleveland), Transducers' 91 (June 24 - 27, 1991, S. Francisco) and EUROSENSORS V (September 30 - October 3, 1991, Rome). Therefore, this book is mainly intended as a reference text for researchers with a MS degree in physics, chemistry and electrical engineering; it reports the last progresses in the R. & D. and in the technology of gas sensors. I choose to deal specifically with the topic of gas sensors because these devices show a very large number of applications in the domestic and industrial field and they are characterized by a great effort of research and development.

Polymer composites represent materials of great and of continuously growing importance. Their potential for application appears to be limitless. They have been the subject of numerous studies both at academic and industrial levels. Much progress has been made in the incisive formulation of composites; sophisticated methods of property evaluation have been developed in the past decade and many, largely empirical solutions have been proposed to resolve the problem of their long-term performance under typical conditions of use (i. e. the use of silane or titane coupling agents to enhance adhesion within composite materials). Assuredly one of the most essential factors in the performance of these systems is the condition of the interface and interphase among the constituents of a given system. It has become clear that it is the interface/interphase, and the interactions which take place in this part of a system, which determine to a significant degree the initial properties of the material. In order to achieve leadership in the formulation and application of polymer composites, it is evident that in depth understanding of interfacial and interphase phenomena becomes a prerequisite.

Recently, attention has been called to the role that microvascular organization plays in the functional morphology of all organs and tissues, both in normal and pathological conditions. Since its development by Murakami, the corrosion cast method for scanning electron microscopy has come to be considered one of the most efficient means in clarifying the three-dimensional features of the microcirculation of organs and tissues. Scanning Electron Microscopy of Vascular Casts: Methods and Applications was planned to supply fundamental and new information regarding microcirculation studies to general biologists, anatomists, pathologists and clinicians. The contributions to this volume, contain original findings and excellent electron micrographs obtained by using recently improved corrosion cast methods. The rich variety of papers in this book will be useful to many, and will provide both the basic and clinically oriented readers with good ideas, suggestions, and original and worthwhile information.

The potential of supercritical fluid methods is presented in a comprehensive way. On the basis of a careful discussion of physical and chemical principles, the application of this method in process technology is demonstrated.

This book is t~e fifth in aseries of scientific textbooks designed to cover advances in selected research fields from a basic and general view point. The reader is taken carefully but rapidly through the introductory material in order that t~e significance of recent developments can be understood with only limited initial knowledge. The inclusion in the Appendix of the abstracts of many of the more important papers in the field provides further assistance for the non-specialist, and acts as aspringboard to supplementary reading for those who wish to consult the original liter ature. Surface analysis has been the subject of numerous books and review articles, and the fundamental scientific principles of t~e more popular techniques are now reasonably weIl established. This book is concerned with the very powerful techniques of Auger electron and X-ray photoelectron spectroscopy (AES and XPS), with an emphasis on how they may be performed as part of a modern analytical facility. Since the development of AES and XPS in the late 1960s and early 1970s there have been great strides forward in the sensitivities and resolutions of the instrumentation. Simultaneously, these spectroscopies have undergone a veritable explosion, both in their acceptance alongside more routine ana1ytical techniques and in the range of problems and materials to which they are applied. As a result, many researchers in industry and in academia now come into contact with AES and XPS not as specialists, but as users.

Contributed by leading authorities in the field from around the world, this text provides a comprehensive insight into buckling and postbuckling. Basic theory, methods of buckling analysis and their application, the effect of external variables such as temperature and humidity on the buckling response and buckling tests are all covered.

The assessment of crack initiation and/or propagation has been the subject of many past discussions on fracture mechanics. Depending on how the chosen failure criterion is combined with the solution of a particular theory of continuum mechanics, the outcome could vary over a wide range. Mod elling of the material damage process could be elusive if the scale level of observation is left undefined. The specification of physical dimension alone is not sufficient because time and temperature also play an intimate role. It is only when the latter two variables are fixed that failure predictions can be simplified. The sudden fracture of material with a pre-existing crack is a case in point. Barring changes in the local temperature,* the energy released to create a unit surface area of an existing crack can be obtained by considering the change in elastic energy of the system before and after crack extension. Such a quantity has been referred to as the critical energy release rate, G e, or stress intensity factor, K Ie. Other parameters, such as the crack opening displacement (COD), path-independent J-integral, etc. , have been proposed; their relation to the fracture process is also based on the energy release concept. These one-parameter approaches, however, are unable simultaneously to account for the failure process of crack initiation, propagation and onset of rapid fracture. A review on the use of G, K I, COD, J, etc. , has been made by Sih [1,2].

Foams are gas filled integral structures in which the gas is finely dispersed throughout acontinuouslyconnected solid phase. The bulk density is usually substantially lower than that of the solid component, and for the foams which form the focus for this book the volume fraction of the gas phase is considerably greater than 0.5 and in most instances in excess of 0.9. Many ofthe materials encountered in every day experience, such as bread, plants and trees, structural materials for buildings, comfort materials for domestic and automotive seating, shock absorbers or car bumpers and materials for noise control, have one thing in common - the cellular nature of their physical structure. Whyare thesestructuressoimportantin the naturaland man-made world? The reasons are both technical and commercial. From a technical viewpoint cellular materials offer: 1. high specific stiffness and strength - making them suitable for structural applications; 2. closeto idealenergymanagement - hencetheir useinthermalandacoustic insulation, vibration damping, acoustic absorption and shock mitigation; and 3. comfort - hence their use for domestic and automotive seating.

Resin Transfer Moulding and other similar 'liquid moulding' manufacturing methods have been used to make non-structural composites for the last 35 years. However, in the last eight years these methods have become the subject of enormous interest by aerospace manufacturing companies. Resin Transfer Moulding for Aerospace Structures describes all aspects of Resin Transfer Moulding (RTM) for aerospace structures. Written by an international team of experts, from both industry and academia, it is a comprehensive work providing complete and detailed information on the process of RTM from theoretical modelling to practical experience. With subjects including manufacturing, tooling, fabric design and flow modelling all covered, this book is an invaluable up-to-the-minute reference source which provides the reader with a good understanding of RTM and its possible uses, especially for high performance applications. Resin Transfer Moulding for Aerospace Structures is an ideal guide for those in the aerospace and related industries, who want to understand and utilize RTM, as well as those directly involved in the RTM industry.

The microanalytical technique of atom probe tomography (APT) permits the spatial coordinates and elemental identities of the individual atoms within a small volume to be determined with near atomic resolution. Therefore, atom probe tomography provides a technique for acquiring atomic resolution three dimensional images of the solute distribution within the microstructures of materials. This monograph is designed to provide researchers and students the necessary information to plan and experimentally conduct an atom probe tomography experiment. The techniques required to visualize and to analyze the resulting three-dimensional data are also described. The monograph is organized into chapters each covering a specific aspect of the technique. The development of this powerful microanalytical technique from the origins offield ion microscopy in 1951, through the first three-dimensional atom probe prototype built in 1986 to today's commercial state-of-the-art three dimensional atom probe is documented in chapter 1. A general introduction to atom probe tomography is also presented in chapter 1. The various methods to fabricate suitable needle-shaped specimens are presented in chapter 2. The procedure to form field ion images of the needle-shaped specimen is described in chapter 3. In addition, the appearance of microstructural features and the information that may be estimated from field ion microscopy are summarized. A brief account of the theoretical basis for processes of field ionization and field evaporation is also included.

Frontiers in Magnetism of Reduced Dimension Systems presents a definitive statement of our current knowledge and the state of the art in a field that has yet to achieve maturity, even though there are a number of potential applications of thin magnetic films and multilayers, such as magnetic sensors, data storage/retrieval media, actuators, etc. The book is organized into 13 chapters, each including a lecture and contributed papers on a similar subject. Five chapters deal with theoretical descriptions of electron transport phenomena, relaxation processes, nonlinear paramagnetic interactions, phase transitions and macroscopic quantum effects in magnetic films and particles. The description of different characterization techniques occupies an important place in the book. Separate chapters are dedicated to magnetic resonances (FMR, SWR, NMR), magneto-optical spectroscopy, controlling chaos, magnetoelastic phenomena and magnetic resonance force microscopy. A further chapter gives a detailed review, spread over a number of papers, of materials in current use in information storage devices.

Good old Gutenberg could not have imagined that his revolutionary printing concept which so greatly contributed to dissemination of knowledge and thus today 's wealth, would have been a source of inspiration five hundred years later. Now, it seems intuitive that a simple way to produce a large number of replicates is using a mold to emboss pattern you need, but at the nanoscale nothing is simple: the devil is in the detail. And this book is about the "devil." In the following 17 chapters, the authors-all of them well recognized and active actors in this emerging field-describe the state-of-the-art, today 's technological bottlenecks and the prospects for micro-contact printing and nanoimprint lithography. Many results of this book originate from projects funded by the European Com mission through its "Nanotechnology Information Devices" (NID) initiative. NID was launched with the objective to develop nanoscale devices for the time when the red brick scenario of the ITRS roadmap would be reached. It became soon clear however, that there was no point to investigate only alternative devices to CMOS, but what was really needed was an integrated approach that took into account more facets of this difficult undertaking. Technologically speaking, this meant to have a coherent strategy to develop novel devices, nanofabrication tools and circuit & system architectures at the same time."

The book addresses the most recent developments in structural and functional proteomics underlying the recent contributions given in these areas by our laboratory to the instrumentations, the methods and the procedures as mutuated from the nanoscale sciences and technologies. These developments introduced in the last few years make now possible protein massive identification (mass spectrometry and biomolecular arrays down to nanoamounts) and protein structural characterization in solution and in crystals down to the atomic scale to an extent and to a degree so far unmatched. Emphasis is placed in the growth by nanobiofilm template of protein crystals of any type and size from millimeter to micron, leading in combination with microfocus synchrotron technology and atomic force microscopy to the definition of a new field called nanocrystallography. The few useful examples being shown, concerning yet structurally unsolved proteins, point this very promising approach nanotechnology-based in structural proteomics using highly focused X-rays. This has not to be confused with the important study of nanocrystals, both organic and inorganic, and novel diamond like nanocomposite materials and devices having 3D protein crystals as matrices to be equilibrated with nanoparticles/gold/silver to be utilized in the most diversified electronic applications here also summarized. vii Acknowledgments We are particularly grateful to Giuseppe Zanotti at the University of Padova for his fundamental collaboration during all the crystallographic studies.

P. S. HOPE and M. J. FOLKES Mixing two or more polymers together to produce blends or alloys is a well-established strategy for achieving a specified portfolio of physical proper ties, without the need to synthesise specialised polymer systems. The subject is vast and has been the focus of much work, both theoretical and experimental. Much ofthe earlier work in this field was necessarily empirical and many ofthe blends produced were of academic rather than commercial interest. The manner in which two (or more) polymers are compounded together is of vital importance in controlling the properties of blends. Moreover, particular ly through detailed rheological studies, it is becoming apparent that process ing can provide a wide range of blend microstructures. In an extreme, this is exemplified by the in situ formation of fibres resulting from the imposition of predetermined flow fields on blends, when in the solution or melt state. The microstructures produced in this case transform the blend into a true fibre composite; this parallels earlier work on the deformation of metal alloys. This type of processing-structure-property correlation opens up many new possi bilities for innovative applications; for example, the production of stiff fibre composites and blends having anisotropic transport properties, such as novel membranes. This book serves a dual purpose."

During the last two decades, the production of polymers and plastics has been increasing rapidly. In spite of developing new polymers and polymeric materials, only 40 60 are used commercially on a large scale. It has been estimated that half of the annual production of polymers is employed outdoors. The photochemical instability of most polymers limits their outdoor application as they are photodegraded quickly over periods from months to a few years. To the despair of technologists and consumers alike, photodegradation and environmental ageing of polymers occur much faster than can be expected from knowledge collected in laboratories. In order to improve polymer photostability there has been a very big effort during the last 30 years to understand the mechanisms involved in photodegradation and environmental ageing. This book represents the author's attempt, based on his 25 years' experience in research on photodegradation and photo stabilization, to collect and generalize a number of available data on the photodegradation of polymers. The space limitation and the tremendous number of publications in the past two decades have made a detailed presentation of all important results and data difficult. The author apologizes to those whose work has not been quoted or widely presented in this book. Because many published results are very often contradictory, it has been difficult to present a fully critical review of collected knowledge, without antagonizing authors. For that reason, all available theories, mechanisms and different suggestions have been presented together, and only practice can evaluate which of them are valid.

The present book is devoted to a rapidly developing field of science which studies the behavior of viscoelastic materials under the influence of deformation~the rheology of polymers. Rheology has long been treated as the theoretical foundation of polymer processing, and from this standpoint it is difficult to overesti mate its importance in practice. Rheology plays an important role in developing our ideas on the nature of viscoelastic behavior in connection with the structural features of polymers and composites based on them. This expands the possibilities of employing rheological methods to characterize a variety of materials and greatly magnifies the interest in this field of research. The rheological properties of polymer systems are studied experimen tally, chiefly under conditions of shear and tensile strains. One explana tion is that many aspects of polymer material processing are associated with the stretching of melts or a combination of shear and tensile strains. In scientific investigations, either periodic or continuous conditions of shear deformation are employed. Each mode provides widespread infor mation. In periodic deformation, most attention is generally given to conditions with low deformation amplitudes that do not alter the structure of the polymer system during an experiment (the region of linear deformation conditions). Here the viscoelastic parameters are generally determined with respect to the frequency. Continuous deforma tion involves considerable strains, and may be attended by significant reversible and irreversible changes in the structure of a polymer.

Rubber Toughened Engineering Plastics covers the main physical principles involved in optimum toughening in high temperature engineering plastics and speciality plastics and describes the synthetic strategies used to obtain satisfactorily toughened grades in these materials by control of microstructure. This book will act as a focus for current thought on the principles of rubber toughening and the methods employed for the rubber toughening of major engineering and speciality plastics.

Stuart Wolf This book originated as a series of lectures that were given as part of a Summer School on Spintronics in the end of August, 1998 at Lake Tahoe, Nevada. It has taken some time to get these lectures in a form suitable for this book and so the process has been an iterative one to provide current information on the topics that are covered. There are some topics that have developed in the intervening years and we have tried to at least alert the readers to them in the Introduction where a rather complete set of references is provided to the current state of the art. The field of magnetism, once thought to be dead or dying, has seen a remarkable rebirth in the last decade and promises to get even more important as we enter the new millennium. This rebirth is due to some very new insight into how the spin degree of freedom of both electrons and nucleons can play a role in a new type of electronics that utilizes the spin in addition to or in place of the charge. For this new field to mature and prosper, it is important that students and postdoctoral fellows have access to the appropriate literature that can give them a sound basis in the funda mentals of this new field and I hope that this book is a very good start in this direction.

The combination of solid materials of different structural dimensionality with atomic or molecular guest species via intercalation processes represents a unique and widely variable low temperature synthesis strategy for the design of solids with particular composition, structure and physical properties. In the last decade this field has experienced a rapid development and represents now an established specific domain of solid state research and materials science. Substantial progress has been made with respect to an understanding of the complex relationship between structure, bonding, physical properties and chemical reactivity since the first volume on the subject appeared in this series in 1979 (Intercalated Layered Materials, F. Levy, ed.). The purpose of this volume is to present a survey on progress and per spectives based on the treatment of a series of major areas of activities in this field. By the very nature of its subject this monograph has an interdisciplinary character and addresses itself to chemists, physicists and materials scien tists interested in intercalation research and related aspects such as design and characterization of complex materials, low temperature synthesis, solid state reaction mechanisms, electronic/ionic conductivity, control of electronic properties of solids with different structural dimensionality and application of intercalation systems. Several chapters have been devoted to specific groups of host lattices.

In September 1985, in an attempt to simulate the chemistry in a carbon star, Harry Kroto, Bob Curl and Richard Smalley set up a mass spectrometry experiment to study the plasma produced by focusing a pulsed laser on solid graphite. Serendipitously, a dominant 720 amu mass peak corresponding to a C60 species was revealed in the time-of-flight mass spectrum of the resulting carbon clusters. It was proposed that this C60 cluster had the closed cage structure of a truncated icosahedron (a soccerball) and was named Buckminsterfullerene because geodesic dome concepts, pioneered by the architect Buckminster Fuller, played an important part in arriving at this solution. The signal for a C70 species (840 amu) , proposed to have the ellipsoidal shape of a rugbyball, was also prominent in the early experiments. Five years later, the seminal work of the Sussex! Rice collaboration was triumphantly confirmed as Wolfgang Krlitschmer and Donald Huffman succeeded in producing, and separating, bulk crystalline samples of fullerene material from arc-processed (in an inert gas atmosphere) carbon deposits. From then onwards, fullerene research continued, and still proceeds, at an exhilarating pace. The materials excited the imagination of many diverse classes of scientists, resulting in a truly interdisciplinary field. Many of our old, seemingly well-founded, preconceptions in carbon science had to be radically altered or totally abandoned, as a new round world of chemistry, physics and materials science began to unfold.

Liquid metal technology has been the subject of an impetuous development in the recent decades, mainly due to the application of liquid met als in nuclear techniques. The technological development has been supported by studies of the basic physical-chemical properties of liquid metals: One major concern is the material behaviour in contact with the liquid metals, corrosion and the possible deterioration of metallic and ceramic materials which are in use as constructional or functional materials in such systems. Since the corrosion is in many cases not only a simple dissolution process, the chemical background of such processes had to be studied. Such studies included the determination of solubilities of metals and non-metals in liquid metals, the measurement of thermodynamic data of dissolved materials and of chemical equilibria. Several formerly unknown chemical compounds are formed in liquid metal~ lnd are only stable in this environment. The research and deve\opment devoted to the fission reactor techniques were more or less completed in several countries, further work is in progress in some countries in which the interest in fast breeder reactors arose recently. Even the worldwide program on fusion reactor technology is related to liquid metals, and severallaboratories are now contributing to this new technology.

Significant experimental work is devoted to the preparation of one and zero dimensional semiconductor structures in view of future electronic and optical devices which involve quantum effects. The aim is good control in the realisation of nanometer structures both in vertical and lateral direction. Conventional processing techniques based on lithography face inherent problems such as limited resolution and surface defects caused by reactive ion etching. During the last few years several research groups started working on direct syntheses of semiconductor nanostructures by combining epitaxial growth techniques such as molecular beam epitaxy and chemical vapour deposition with pre patterning of the substrate wafers. Another idea is based on island formation in strained layer heteroepitaxy. Zero and one dimensional structures with dimensions down to a few atomic distances have been realised this way. An important point is that the size of the quantum structures is controlled within the epitaxial deposition in a self-adjusting process. The main subjects of the book are: Theoretical aspects of epitaxial growth, selfassembling nanostructures and cluster formation, epitaxial growth in tilted and non-(001) surfaces, cleaved edge overgrowth, nanostructure growth on patterned silicon substrates, nanostructures prepared by selective area epitaxy or growth on patterned substrates, in-situ etching and device applications based on epitaxial regrowth on patterned substrates. The experimental work mainly concentrated on GaAs/A1GaAs, GaAs/InGaAs, InGaP/InP and Si/SiGe based semiconductor heterostructures. Growth related problems received special attention. The different concepts for preparation of low dimensional structures are presented to allow direct comparison and to identify new concepts for future research work.

This edition of Thermodynamics is a thoroughly revised, streamlined, and cor rected version of the book of the same title, first published in 1975. It is intended for students, practicing engineers, and specialists in materials sciences, metallur gical engineering, chemical engineering, chemistry, electrochemistry, and related fields. The present edition contains many additional numerical examples and prob lems. Greater emphasis is put on the application of thermodynamics to chemical, materials, and metallurgical problems. The SI system has been used through out the textbook. In addition, a floppy disk for chemical equilibrium calculations is enclosed inside the back cover. It contains the data for the elements, oxides, halides, sulfides, and other inorganic compounds. The subject material presented in chapters III to XIV formed the basis of a thermodynamics course offered by one of the authors (R.G. Reddy) for the last 14 years at the University of Nevada, Reno. The subject matter in this book is based on a minimum number of laws, axioms, and postulates. This procedure avoids unnecessary repetitions, often encountered in books based on historical sequence of development in thermodynamics. For example, the Clapeyron equation, the van't Hoff equation, and the Nernst distribution law all refer to the Gibbs energy changes of relevant processes, and they need not be presented as radically different relationships.

Few scientific developments in recent years have captured the popular imagination like the subject of'biodegradable' plastics. The reasons for this are complex and lie deep in the human subconscious. Discarded plastics are an intrusion on the sea shore and in the countryside. The fact that nature's litter abounds in the sea and on land is acceptable because it is biodegradable - even though it may take many years to be bioassimilated into the ecosystem. Plastics litter is not seen to be biodegradable and is aesthetically unacceptable because it does not blend into the natural environment. To the environmentally aware but often scientifically naive, biodegradation is seen to be the ecologically acceptable solution to the problem of plastic packaging waste and litter and some packaging manufacturers have exploited the 'green' consumer with exaggerated claims to 'environmentally friendly' biodegradable packaging materials. The principles underlying environmental degradation are not understood even by some manufacturers of 'biodegradable' materials and the claims made for them have been categorized as 'deceptive' by USA legislative authorities. This has set back the acceptance of plastics with controlled biodegradability as part of the overall waste and litter control strategy. At the opposite end of the commercial spectrum, the polymer manufactur ing industries, through their trade associations, have been at pains to discount the role of degradable materials in waste and litter management. This negative campaign has concentrated on the supposed incompatibility of degradable plastics with aspects of waste management strategy, notably materials recycling."

The integration of top-down lithographic techniques with synthetic organic and inorganic technologies is a key challenge for the development of effective nanosca1e devices. In terms of assembly, nanoparticles provide an excellent tool for bridging the gap between the resolution of electron beam lithography (-60 nm) and the molecular level. Nanoparticles possess an array of unique properties associated with their core materials, including distinctive magnetic, photonic and electronic behavior. This behavior can be controlled and applied through monolayer functionalization and assembly strategies, making nanoparticles both scaffolds and building blocks for nanotechnology. The diverse structures and properties of nanoparticles makes them useful tools for both fundamental studies and pragmatic applications in a range of disciplines. This volume is intended to provide an integrated overview of the synthesis and assembly of nanoparticles, and their applications in chemistry, biology, and materials science. The first three chapters focus on the creation and intrinsic properties of nanoparticles, covering some of the myriad core materials and shapes that have been created. The remaining chapters of the book discuss the assembly of nanoparticles, and applications of both discrete particles and particle assemblies in a wide range of fields, including device and sensor fabrication, catalysis, biology, and nanosca1e electronic and magnetic systems.