Yue Li

This Element introduces the exotic wave phenomena arising from the extremely small optical refractive index, and sheds light on the underlying mechanisms, with a primary focus on the basic concepts and fundamental wave physics. The authors reveal the exciting applications of ENZ metamaterials, which have profound impacts over a wide range of fields of science and technology. The sections are organized as follows: in Section 2, the authors demonstrate the extraordinary wave properties in ENZ metamaterials, analyzing the unique wave dynamics and the resulting effects. Section 3 is dedicated to introducing various realization methods of the ENZ metamaterials with periodic and non-periodic styles. The applications of ENZ metamaterials are discussed in Sections 4 and 5, from the perspectives of microwave engineering, optics, and quantum physics. The authors close in Section 6 by presenting an outlook on the development of ENZ metamaterials and discussing the key challenges addressed in future works.

Hierarchical Micro/Nanostructured Materials: Fabrication, Properties, and Applications presents the latest fabrication, properties, and applications of hierarchical micro/nanostructured materials in two sections—powders and arrays. After a general introduction to hierarchical micro/nanostructured materials, the first section begins with a detailed discussion of the methods of mass production for hierarchical micro/nanostructured powders, including structure-directed solvothermal routes, template-etching strategies, and electrospinning technologies. It then proceeds to address structurally enhanced adsorption and photocatalytic performances. The second section describes strategies for the fabrication of hierarchical micro/nanostructured object arrays and their devices, such as modified colloidal lithographies-based solution and electrodeposition. It also examines the structure-dependent properties and performances of the micro/nanostructured arrays, including surface wettability, optical properties, surface-enhanced Raman scattering (SERS) effects, and gas-sensing performances. In its cutting-edge coverage, Hierarchical Micro/Nanostructured Materials: Fabrication, Properties, and Applications explores the use of hierarchical micro/nanostructured materials in environmental remediation and detection devices, commenting on future trends and applications in catalysis, integrated nanophotonics, optical devices, super-high density storage media, sensors, nanobiotechnology, SERS substrates, and more.

Hierarchical Micro/Nanostructured Materials: Fabrication, Properties, and Applications presents the latest fabrication, properties, and applications of hierarchical micro/nanostructured materials in two sections—powders and arrays. After a general introduction to hierarchical micro/nanostructured materials, the first section begins with a detailed discussion of the methods of mass production for hierarchical micro/nanostructured powders, including structure-directed solvothermal routes, template-etching strategies, and electrospinning technologies. It then proceeds to address structurally enhanced adsorption and photocatalytic performances. The second section describes strategies for the fabrication of hierarchical micro/nanostructured object arrays and their devices, such as modified colloidal lithographies-based solution and electrodeposition. It also examines the structure-dependent properties and performances of the micro/nanostructured arrays, including surface wettability, optical properties, surface-enhanced Raman scattering (SERS) effects, and gas-sensing performances. In its cutting-edge coverage, Hierarchical Micro/Nanostructured Materials: Fabrication, Properties, and Applications explores the use of hierarchical micro/nanostructured materials in environmental remediation and detection devices, commenting on future trends and applications in catalysis, integrated nanophotonics, optical devices, super-high density storage media, sensors, nanobiotechnology, SERS substrates, and more.

Perianal Crohn’s Disease: Diagnosis and Treatment includes the latest knowledge, concepts, first-hand theoretical views and clinical experience of clinical front-line experts in the field of inflammatory bowel disease. It systematically describes the disease phenotypes, clinical features, examination methods, diagnosis and treatment. The book takes a scientific, practical and systematic account of both the common and rare conditions associated with Perianal Crohn’s Disease. It offers informative content, clinical case information, cutting-edge viewpoints and current authoritative research findings. The book contains a depth of current clinical experience, including the use of photographs to support examples of conditions, methods and techniques are included in the book. Provides clear ideas and a wealth of clinical information for the clinical diagnosis and management of perianal Crohn's disease.

This report introduces the first global, geolocated database of physical infrastructure assets and a framework to guide investment priorities. Comparing social returns with borrowing costs reveals widespread underinvestment across energy, transport, and digital sectors, with especially high returns to transport in developing countries.

Institutional weaknesses limit the capacity of local governments to support efficient urbanization in developing countries. They also lead to the emergence of large developers with the clout to build entire cities. This paper analyzes the urbanization process when local governments are weak and large developers are powerful. Results from a non-cooperative game setting with minimal assumptions show that multiple equilibria can emerge depending on key institutional parameters of the model and the nature of the game, but all of them are inefficient. In this simple setting, increasing the capacity of the local government may not lead to better outcomes, because it may crowd out urban land development by the more effective private investor. Subsidizing the large investor can ensure efficiency, but it makes the rest of society worse off. Selling the rights to the city can be Pareto efficient, but only provided that the price at which the rights are sold are sufficiently high. However, more analytical and empirical work is needed before these analyses can be deemed relevant in practice. Competition among jurisdictions, time consistency challenges, and the social implications of private cities deserve special attention.

By using state-of-the-art modeling techniques, this study simulates population, housing, economic activity, commuting times, transport and trade across the 266 unions that constitute Great Dhaka, taking into account flood vulnerability, traffic congestion and other location conditions.