The book gives an overview of the current state-of-the-art concerning the activation and dissolution of cellulose in a broad variety of solvents. Research on this topic can lead to new pathways for the utilization of the most abundant terrestrial biomolecule and may therefore be the basis for new green strategies towards advanced materials. Leading scientists in the field show different conceptions for the solubilization of cellulose. The long history and groundbreaking developments in the field of polymer chemistry, which are related to this subject, have lead to timely alternatives to already established methods. In addition to discussing attempts for the optimization of known dissolving procedures, this book also details new solvent systems. New solvents include inorganic and organic salt melts (ionic liquids), new aqueous media, multi-component organic solvents and the dissolution under partial derivatization of the polysaccharide. The opportunities and the limitations of the solvents are demonstrated, with a particular emphasis on the stability of the solutions and a possible recycling of the solvent components.
This book illustrates that the new procedures for cellulose dissolution can lead to a huge number of unconventional superstructures of regenerated cellulose material, such as fibers and polymer layers with a thickness in the nanometer range or aerogels, i.e. regenerates with a highly porous character and a large surface. Moreover, cellulose blends can be generated via solutions. The book also contains chapters that show the amazing potential of solvents for defined modification reactions on the cellulose backbone. On one hand, it is possible to synthesize known cellulose derivatives with new substitution patterns both on the basis of the repeating unit and along the polymer chain. On the other hand, completely new derivatives are presented which are hardly accessible via heterogeneous reactions. Consequently, the book is intended to give a comprehensive overview of procedures for dissolution of cellulose. It is of interest for scientists new in the field but is also a timely summary of trends for experts who are looking for new approaches for problems related to cellulose shaping or chemical modification.

The attacks and blockade on Yemen by the Saudi-led multinational coalition have killed thousands and triggered humanitarian disaster. The longstanding conflict in the country between the Huthi rebels and (until December 2017) Salih militias on the one side and those loyal to the internationally recognized government and many other groups fighting for their interests on the other are said to have evolved into a proxy war between Saudi Arabia and Iran. In 2011, however, thousands of Yemenis had taken to the streets to protest for a better future for their country. When President Ali Abdullah Salih signed over power in the aftermath of these protests, there were hopes that this would signal the beginning of a new period of transition. Yemen and the Search for Stability focuses on the aspirations that inspired revolutionary action, and analyzes what went wrong in the years that followed. It examines the different groups involved in the protests - Salih supporters, Muslim Brothers, Salafis, Huthis, secessionists, women, youth, artists and intellectuals- in terms of their competing visions for the country's future as well as their internal struggles. This book traces the impact of the 2011 upheavals on these groups' ideas for a `new Yemen' and on their strategies for self-empowerment. In so doing, Yemen and the Search for Stability examines the mistakes committed in the country's post-2011 transition process but also points towards prospects for stability and positive change.

Optimization problems subject to constraints governed by partial differential equations (PDEs) are among the most challenging problems in the context of industrial, economical and medical applications. Almost the entire range of problems in this field of research was studied and further explored as part of the Deutsche Forschungsgemeinschaft (DFG) priority program 1253 on "Optimization with Partial Differential Equations" from 2006 to 2013. The investigations were motivated by the fascinating potential applications and challenging mathematical problems that arise in the field of PDE constrained optimization. New analytic and algorithmic paradigms have been developed, implemented and validated in the context of real-world applications. In this special volume, contributions from more than fifteen German universities combine the results of this interdisciplinary program with a focus on applied mathematics. The book is divided into five sections on "Constrained Optimization, Identification and Control", "Shape and Topology Optimization", "Adaptivity and Model Reduction", "Discretization: Concepts and Analysis" and "Applications". Peer-reviewed research articles present the most recent results in the field of PDE constrained optimization and control problems. Informative survey articles give an overview of topics that set sustainable trends for future research. This makes this special volume interesting not only for mathematicians, but also for engineers and for natural and medical scientists working on processes that can be modeled by PDEs.

Simulation based on mathematical models plays a major role in computer aided design of integrated circuits (ICs). Decreasing structure sizes, increasing packing densities and driving frequencies require the use of refined mathematical models, and to take into account secondary, parasitic effects. This leads to very high dimensional problems which nowadays require simulation times too large for the short time-to-market demands in industry. Modern Model Order Reduction (MOR) techniques present a way out of this dilemma in providing surrogate models which keep the main characteristics of the device while requiring a significantly lower simulation time than the full model. With Model Reduction for Circuit Simulation we survey the state of the art in the challenging research field of MOR for ICs, and also address its future research directions. Special emphasis is taken on aspects stemming from miniturisations to the nano scale. Contributions cover complexity reduction using e.g., balanced truncation, Krylov-techniques or POD approaches. For semiconductor applications a focus is on generalising current techniques to differential-algebraic equations, on including design parameters, on preserving stability, and on including nonlinearity by means of piecewise linearisations along solution trajectories (TPWL) and interpolation techniques for nonlinear parts. Furthermore the influence of interconnects and power grids on the physical properties of the device is considered, and also top-down system design approaches in which detailed block descriptions are combined with behavioral models. Further topics consider MOR and the combination of approaches from optimisation and statistics, and the inclusion of PDE models with emphasis on MOR for the resulting partial differential algebraic systems. The methods which currently are being developed have also relevance in other application areas such as mechanical multibody systems, and systems arising in chemistry and to biology. The current number of books in the area of MOR for ICs is very limited, so that this volume helps to fill a gap in providing the state of the art material, and to stimulate further research in this area of MOR. Model Reduction for Circuit Simulation also reflects and documents the vivid interaction between three active research projects in this area, namely the EU-Marie Curie Action ToK project O-MOORE-NICE (members in Belgium, The Netherlands and Germany), the EU-Marie Curie Action RTN-project COMSON (members in The Netherlands, Italy, Germany, and Romania), and the German federal project System reduction in nano-electronics (SyreNe).