bluuebunny/crossref_metadata_2025 huggingface dataset:
Technology and Development
Authors: Murphy James T.
Published: March 2017

Technologies are multifaceted phenomena which include material artifacts, codified forms of knowledge, and intangible or tacit skills and understandings. Technology's role in development was traditionally viewed as being universally positive and progressive through its ability to contribute in a unidirectional manner to growth and modernization. As technologies' failures and limitations became increasingly evident in the 1960s, critical perspectives emerged and prompted studies that contextualized technology development and diffusion processes in order to understand the power relations and contingencies that shape their outcomes. Such studies reveal the influence that institutional, historical, social, and political circumstances play in shaping technological priorities, the design of artifacts, and spatial diffusion processes; dynamics that often result in the marginalization or exclusion of less empowered members of society. An understanding of the role of geographical context and power relations is thus essential in order to assess critically the appropriateness and efficacy of technologies as tools for more just and distributive forms of development.
Urban Mosaic
Authors: Greene Richard P.
Published: March 2017

The establishment of multiple racial and ethnic groups in cities often results in a patchwork of neighborhoods that form an urban mosaic. The urban processes that lead to an urban mosaic were described as far back as the Chicago School of sociology, particularly in their discussion of how immigrant groups carve out unique niches within the city. The phrase “urban mosaic” was the title of a book in the mid‐1970s, but 20 years prior to that the quantification of city patterns had begun to reveal neighborhood patchworks using the techniques embodied in social area analysis. Social area analysis became known as factorial ecology, which attempted to describe and explain ethnic clusters within cities. Today the urban mosaic pattern persists in cities but much of the discussion is embedded within the racial segregation literature, with debates ranging from those who see a rise of multi‐ethnic neighborhoods to those who suggest that segregation of racial and ethnic groups persist.
Urban Regimes
Authors: Wilson David
Published: March 2017

Urban regimes and its conceptual partner, urban regime theory, has been a dominant perspective in urban geography, political geography, and the social sciences for more than three decades. This work identifies urban regimes as amalgams of city‐based institutions that construct, manage, and regulate the social, political, and spatial domains of cities. Such regimes – city governments, builders, developers, realtors, businesses, corporations, chambers of commerce – are seen to operate as semi‐monolithic political entities in order to advance goals and plans. More recently, regime theory has deepened to incorporate the realities of how city regimes must be responsive to political struggles, changing political and cultural conditions, and contradictions in local, regional, and national economic formations. As poststructuralist and postmodern sensibilities have suffused urban studies since the turn of the twenty‐first century, regime theory has seamlessly incorporated these concerns.
Geomorphic Hazards
Authors: Marston Richard A. , Butler William D. , Patch Nicholas L.
Published: March 2017

Geomorphic hazards are those that originate at or near Earth's surface and include expansive soils, soil erosion, slope failures, ground subsidence and karst, river channel changes, glaciers, and coastal erosion. Geomorphic hazards are natural processes until they intersect with human activities and settlements. Geomorphic hazards can be natural or be caused/exacerbated by human activities to some degree. Expansive soils involve Vertisols with certain clay minerals or soils with a high gypsum content. They experience shrink‐and‐swell and deep cracking, which damages structures built on them. Soil erosion has been a hazard since the advent of agriculture. Soils are eroded by rainsplash, sheetwash, rills, gullies, and piping. Wind erosion can be important locally. Dust storms are controlled by wind turbulence, aridity, supply of silt‐sized particles, fetch, and land use/land cover. The variables that control slope failures differ from place to place, and from time to time in the same place. Subsidence is a type of mass movement that involves the downward displacement of surface material caused by natural or artificial removal of underlying support (collapse) or by compression of soils (consolidation). Sudden collapse of the ground, forming sinkholes, is more common in karst terrain. Rivers channels change location by meander cutoffs, meander migration, and by avulsion. These changes can occur in the absence of human activities but can be exacerbated by humans through direct manipulation of the channel or through land‐use/land‐cover changes upstream. Glaciers can create hazards for humans in at least five ways. Coastal hazards include erosion and sedimentation by waves and longshore currents. The types of hazards depend on the geomorphic type of coastline: sandy beaches, cliff coasts, deltas, or coral reefs. All geomorphic hazards can be affected by climate change.
Mediterranean‐Type Ecosystems
Authors: Malanson George P.
Published: March 2017

Mediterranean‐type ecosystems are biomes that are composed of plant and associated animal species adapted to warm, dry summers and mild, wet winters. These biomes are found in small areas around the Mediterranean Sea, in western Australia, on the southern tip of Africa, in Chile, and in California, USA, and Baja California, Mexico. The vegetation is dominated by evergreen sclerophyllous shrubs. Fire is a common ecological disturbance to which plant species have adapted. Mediterranean‐type ecosystems face the global change challenge of many biomes but the interacting effects of climate change and land‐use change with a changing fire regime are significant.
Climate Change and Permafrost
Authors: Salzmann Nadine , Gärtner‐Roer Isabelle
Published: March 2017

Permafrost is a thermal phenomenon of the lithosphere and applies to ground that remains at or below 0°C for at least two consecutive years. Permafrost is coupled to atmospheric conditions and as such is sensitive to climatic changes. Thawing of permafrost can lead to destabilization of steep slopes or infrastructure, and a major concern is the release of radiative active forcing gases such as methane stored in permafrost ground. Projections of permafrost changes suggest further degradation in both high altitudes and high latitudes.
Snow Cover
Authors: Robinson David A.
Published: March 2017

Snow covers approximately 30% of the earth's land surface on a seasonal basis, with additional coverage over alpine glaciers, polar ice sheets, and sea ice. The physical characteristics of a snow‐covered landscape, including its influence on surface reflectance, result in snow playing a critical role in the climate system. The water content of a snowpack is important to the hydrologic regime in many locations, whether serving as a reservoir or as a flood threat. Snow extent is an important climate variable to monitor when assessing climate change, as it is closely associated with temperature, moisture, and atmospheric circulation. Snow cover, or the lack thereof, is of considerable importance for decision‐makers in transportation, recreation, utility, and other sectors of local and global economies.
Agroclimatology
Authors: Niyogi Dev
Published: March 2017

Agroclimatology combines knowledge from agricultural and climatological disciplines to develop an understanding of how crops, soils, livestock, and the environment are interlinked and influence one another. Agroclimatological information is primarily used to understand and provide guidance regarding how climate (both in the short term, e.g., weeks to months, and longer term, e.g., years to decades) can affect agricultural activities, crop productivity, and sustainability. In recent years, agroclimatological information has also been used to understand the impact of agriculture on climate and the role of agriculture as a component of the climate system (via changes in regional land surface emissivity and albedo, land use, humidity, and temperature, as well as greenhouse gas emissions), and develop decisions ranging from farm‐scale sustainability to the global food security challenge.
Climatology
Authors: Winkler Julie A.
Published: March 2017

Climatology, defined simply as the study of climate, has a long history. The emphasis of climatology in different eras of its development has fluctuated between the spatial distribution and the temporal variations of climate. Climatologists employ multiple data sources and methods to study climate, and climate models are a particularly important tool. Climatology can be divided into subfields based on differences in analytical perspective or thematic focus. Applied climatology cuts across these analytical and thematic dimensions, and increasingly involves both natural and social scientists. Interest in climatology has increased dramatically, partly in response to concerns about natural and anthropogenic climate change. The terminology “climate science” has grown in popularity, and appears to be replacing “climatology” as the umbrella term for the study of climate.
Paleoclimatology
Authors: Pisaric Michael F.J.
Published: March 2017

The Earth's climate has constantly evolved and changed throughout its 4.8 billion‐year history. During most of the Earth's history, climate has been characterized as hyperthermal, punctuated by cool periods during the Neoproterozoic, late Ordovician, early Permian, late Jurassic, and from the early Eocene to the present. These broad changes in climate occurred in response to a number of internal and external‐forcing mechanisms, including changes in solar output, changes in Earth's orbital geometry, meteor impacts, orogenesis and tectonic processes, and the variable concentrations of greenhouse gases in the atmosphere. Paleoclimatology is the science that studies these changes in climate throughout the entire history of Earth. The relevancy of paleoclimatology has grown in recent decades in response to anthropogenic climate change and the need to understand natural climate variability.
Aquifers
Authors: Luzzadder‐Beach Sheryl
Published: March 2017

Aquifers are underground, saturated, water‐bearing geologic formations. The top of the water table defines the division between the phreatic zone and the overlying vadose zone. Water at or below the water table in an aquifer is referred to as groundwater. Water above the water table in the vadose zone is commonly referred to as soil water. Aquifers are composed of a wide variety of geologic units or matrices, and are created by numerous geologic and geomorphic processes over time. Groundwater enters an aquifer through percolation. Groundwater flow in aquifers is often defined in terms of economic quantities. Groundwater may be recharged in aquifers through the hydrologic cycle, but withdrawing groundwater by pumping at a rate unsustainable by recharge is considered water mining. Some aquifers contain water accrued during past wetter climate regimes and are no longer recharged; this is considered fossil water.
Water Banking
Authors: Luzzadder‐Beach Sheryl , Flood Jonathan M.
Published: March 2017

Water banking is a water conservation strategy that, like currency, takes physical and/or virtual forms. Water banking varies geographically with the temporal and spatial availability of accessible fresh water. Water banking therefore tracks the water budget closely, considering both supply and demand, and can be thought of as an enhancement of the budget's storage component. As the budgetary and banking language implies, there may also be trade or water economics components to this practice, in addition to the simple concept of saving water for a nonrainy day.
Corporate Environmental Responsibility
Authors: Hilson Abigail Efua
Published: March 2017

Corporate environmental responsibility (CER), a voluntary endeavor by corporations to measure and minimize the ecological impacts of their business activities, is now widespread practice. CER is part and parcel of corporate social responsibility – the idea that organizations must account for the social and environmental impacts of their business activities in formulating their business strategies. CER has become a very important concept in modern times as a result of the changes affecting the natural environment. Critical issues such as climate change and biodiversity loss have necessitated that all businesses take into account the impacts of their activities on the natural environment in their planning. This entry traces the origins of CER, evaluates its current practice, and offers a brief snapshot of its future trajectory.
Landforms and Physiography
Authors: Butler David R. , Marston Richard A.
Published: March 2017

Landforms are recognizable topographic features on the surface of Earth with a distinct shape and position in the landscape, local relief, geologic composition, age, and processes of formation, maintenance, and change. During the early twentieth century, the term “physiography” was coined as a contraction of the words “physical geography,” and soon came to mean regional geomorphology. A number of textbooks on physiography dominated the literature and teachings in geomorphology for the first half of the twentieth century. The mapping of landforms has changed from paper mapping, through computer mapping, to virtual reality. The availability of digital elevation models (
DEMs
) has led to an area of research known as geomorphometry. Ecoregion mapping has extended the concept of physiography to truly include the elements of the landscape interacting with landforms.
Data Model, Object‐Oriented
Authors: Bian Ling
Published: March 2017

Because the computing environment is finite and discrete, a geographic space must be divided into a finite number of discrete pieces before it can be represented in computers. Spatial data models focus on the design of the discretization and the relationships between the discretized pieces. The representation of space involves three levels of abstraction, including conceptual models, spatial data models, and implementation models. Spatial phenomena can be conceptualized as spatial objects, spatial regions, and fields. Five characteristics, namely spatial scale, presence of boundary, spatial variation of attributes, spatial variation of processes, and mobility, allow these objects, regions, and fields to be represented by five typical types of conceptual models: individuals, masses of individuals, regions of individuals, continuous mass, and regions in mass. The two classical data models, vector and raster, can help formalize these conceptual models but can do so only to various degrees. The compatibility between the characteristics of conceptual models and the design principle of the data models, along with their object‐oriented implementations determine the appropriate choice of data models. Such a choice is critical for the outcome of the intended geographic study. This entry gives an overview of spatial data models, the main approaches to account for objects, regions, and fields, and object‐oriented implementations.
Qualitative
GIS
Authors: Pavlovskaya Marianna
Published: March 2017

In less than a decade, qualitative GIS became widely used not only in geography but across social sciences and humanities. Following critical GIS debates and feminist GIS interventions, qualitative GIS has emerged as a field that pioneered ways to map new types of data derived from qualitative interviews, historical archives, literary texts, and, more recently, social media, neogeography, and artistic visions of place. It also advanced integration of qualitative research methods with geospatial analysis in order to account for nonquantifiable, uncounted, and conceptually marginalized but important experiences and socioeconomic practices. Qualitative GIS, therefore, constructs new imaginaries of place and space that can contribute to inclusive citizenship. Advancing the fusion of this scholarship with new spatially oriented and digital research in social sciences and humanities would help to realize better this critical potential of qualitative GIS.
Representation:
3‐D
Authors: Zlatanova Sisi
Published: March 2017

3‐D modeling has been the subject of increased attention in the last two decades. Technology has been developed to such a degree that large datasets can be collected, processed, analyzed, managed, and visualized in reasonable time. Domain applications are looking with much interest at 3‐D representations, acknowledging the increased possibilities for display and analysis of data. The tendency of using 3‐D data from different domains in one application is growing, and this poses many challenges. Developed independently through the years, 3‐D applications involve various representations (vector, raster, freeform curves, and surfaces), levels of detail, appearance, semantics, and topology. Representing the real world in 3‐D differs significantly from representation in 2‐D. Technology and approaches for data collection (detect vertical elements of objects, overhanging sections – as sheds, bridges, and roofs), data processing, data structures, data models, and visualization have to be adapted, extended, and/or improved to deal with vertical and overhanging elements as well as objects located inside, above or below each other. Many of the well‐known approaches in 2‐D GIS are not readily applicable to 3‐D representation. This requires investigation of new possibilities for representation, structuring, and visualization of data. This entry outlines the most commonly used 3‐D geometric representations in terms of their geometry, resolution, topology, and semantics, elaborates on their use in a wide range of applications, and discusses some of the challenges in research and development.
Urban Resilience
Authors: Friend Richard
Published: March 2017

Urban resilience has come to play a central role in the new urban policy agenda, as well as in the academic literature on cities, urbanization, and links with disasters and climate change. It is a concept that draws on a range of academic disciplines and theoretical backgrounds, each with its own strengths and weaknesses in application. More importantly, urban resilience represents a new discourse, with a whole set of metaphors, story lines, and narratives that contribute to framing problems and courses of action. This entry examines the theoretical roots of urban resilience, and considers the implications of its application.
Landscape Ecology
Authors: Christensen Andreas Aagaard , Brandt Jesper , Svenningsen Stig Roar
Published: March 2017

Landscape ecology is an interdisciplinary field of research and practice that deals with the mutual association between the spatial configuration and ecological functioning of landscapes, exploring and describing processes involved in the differentiation of spaces within landscapes, and the ecological significance of the patterns which are generated by such processes. In landscape ecology, perspectives drawn from existing academic disciplines are integrated based on a common, spatially explicit mode of analysis developed from classical holistic geography, emphasizing spatial and landscape pattern analysis and ecological interaction of land units. The landscape is seen as a holon: an assemblage of interrelated phenomena, both cultural and biophysical, that together form a complex whole. Enduring challenges to landscape ecology include the need to develop a systematic approach able to translate positivist readings of the environment and hermeneutical perspectives on socioecological interaction into a common framework or terminology.
Geographical Imagination
Authors: Gieseking Jen Jack
Published: March 2017

Geographers attach multiple definitions to the term “geographical imagination,” many of which can be traced back to the work of Hugh Prince, David Harvey, and Derek Gregory. The term is most often used in relation to understandings of the landscape, the power of maps, studies of identity and oppression, and/or meanings of large territories as they relate to everyday lives such as the city, nature, or the nation‐state. At its best, the geographical imagination affords the user ways to pry open the power of assumptions, stereotypes, and expectations associated with space and place, and to delve into how and why they are linked.
Leisure Geographies
Authors: Duncan Tara
Published: March 2017

Leisure has long been a contested term and while it has a long history of engagement by geographers it remains an underrepresented research field in geography. There is, however, a growing body of literature looking to the activities of leisure, including barriers to participation. Leisure geographies now incorporate innovative methods and interdisciplinary theory.
Women in Geography
Authors: Peake Linda J.
Published: March 2017

Although women have a long history in the discipline of geography, dating from the nineteenth century, they did not move into it in significant numbers until the 1980s. Questions about the representation of women in the discipline are starting to move from a concern with overall numbers vis‐à‐vis men to the chronic underrepresentation of women of color. Institutions representing women started to emerge in the 1970s, and a number of types of organization now serve the professional interests of women and promote gender‐based and feminist research. Their presence is geographically uneven and replicates that of women in the discipline, being well established in the Anglo‐American heartlands and more sporadic elsewhere. While the future for some women in Anglo‐America – those who are white, middle‐class, able‐bodied, and English‐speaking – seems certain, the possibility of a future of women in geography being racialized is much more uncertain. For those women outside Anglo‐America, issues of English‐language hegemony also dominate.
Peace
Authors: Koopman Sara
Published: March 2017

Peace is never clearly distinct from war. War is inside peace, and peace is inside war. Peace is not a separate end point to achieve in time or space, but a precarious sociospatial process that is remade every day. Peace means different things at different scales, as well as to different groups and at different times and places. It is shaped by the spaces in which it is made, as it too shapes those spaces. Peace is not the same everywhere any more than war is. When peace is portrayed as a mythical singular, it can more easily be used to justify violence and oppression.
Urban Geography
Authors: Anderson Matthew B.
Published: March 2017

The principal focus of urban geography has been and continues to be the city, and how political, economic, and social forces and human–environmental relations flow and reverberate through urban landscapes. Urban geography is one of the largest subfields within human geography. Through the twentieth and twenty‐first centuries, urban geographers have used a range of philosophical and epistemological approaches to examine and understand the city, such as positivism, urban political economy, postmodernism, and beyond. It is, however, the
spatial perspective
emphasized by urban geographers that links the diverse discipline together.
Fluvial Erosional Processes and Landforms
Authors: Martin Ross H.
Published: March 2017

Fluvial erosional processes begin with understanding how flowing water interacts with the landscape. As certain thresholds are met, water begins to entrain sediment. The removal and transport of sediment result in erosional landforms. Fluvial erosional landforms exist at a range of scales from upland rill formation, to tortuously sinuous meandering rivers that stretch for miles. Describing how water mobilizes sediment and the interaction of the flow with the landscape yields understanding of how fluvial processes create and maintain landforms.
Quaternary Geomorphology and Landscapes
Authors: Goff Paepin
Published: March 2017

During the most recent 2.6 million years of Earth's history, the climate oscillated between glacial and interglacial states. This period, called the Quaternary, produced a variety of landscapes, which are the result of glacial erosion and deposition. The Quaternary also caused widespread expansion of periglacial activity on the margins of these glacial environments. Additionally, the history of Quaternary vegetation distribution offers a view into global and regional climate change through the range, abundance, and composition of species. The study of these landforms and vegetation changes allows geomorphologists and paleoclimatologists to reconstruct Earth's Quaternary history and better understand the climate system.
Resilience and Human Geography
Authors: Wilson Geoff A.
Published: March 2017

The notion of “resilience” has begun to influence research by human geographers, and human geographers, in turn, have begun to shape thinking about the meaning and significance of resilience. This entry outlines the scientific genesis of the concept, and then focuses specifically on contributions to resilience research by social scientists and human geographers. The entry demonstrates that resilience – much like “sustainability” – remains a relatively ill‐defined and elusive term, and that different disciplines and subdisciplines use the word in often different and contradictory ways. The entry concludes by suggesting that human geographers are particularly well placed to contribute to both further clarification and improved practical application of the term.
Lead‐Free Ceramics with High Energy Density and Reduced Losses for High Temperature Applications
Authors: Correia Tatiana , Stewart Mark , Ellmore Angela , Albertsen Knuth
Published: March 2017

The major limiting factors for the use of ceramic capacitors in power electronics are size and temperature stability. Ferroelectric ceramics very often exhibit high energy density, but fail to provide stable and efficient performance at high temperatures. Here, the authors report on a lead‐free BiFeO3‐SrTiO3 ceramic capacitor exhibiting unprecedented low dielectric loss and high thermal stability, while maintaining high energy density and fast discharge rates up to 200 °C. These unique properties clearly outperform other state of the art ceramics and potentially create significant new markets for high capacity ceramic capacitors at high frequencies and high temperature operations.
Interface Control of Ferroelectricity in an SrRuO3/BaTiO3/SrRuO3 Capacitor and its Critical Thickness
Authors: Shin Yeong Jae , Kim Yoonkoo , Kang Sung‐Jin , Nahm Ho‐Hyun , Murugavel Pattukkannu , Kim Jeong Rae , Cho Myung Rae , Wang Lingfei , Yang Sang Mo , Yoon Jong‐Gul , Chung Jin‐Seok , Kim Miyoung , Zhou Hua , Chang Seo Hyoung , Noh Tae Won
Published: March 2017

The atomic‐scale synthesis of artificial oxide heterostructures offers new opportunities to create novel states that do not occur in nature. The main challenge related to synthesizing these structures is obtaining atomically sharp interfaces with designed termination sequences. In this study, it is demonstrated that the oxygen pressure during growth plays an important role in controlling the interfacial terminations of SrRuO3/BaTiO3/SrRuO3 (SRO/BTO/SRO) ferroelectric (FE) capacitors. The SRO/BTO/SRO heterostructures are grown by a pulsed laser deposition method. The top SRO/BTO interface, grown at high (around 150 mTorr), usually exhibits a mixture of RuO2–BaO and SrO–TiO2 terminations. By reducing , the authors obtain atomically sharp SRO/BTO top interfaces with uniform SrO–TiO2 termination. Using capacitor devices with symmetric and uniform interfacial termination, it is demonstrated for the first time that the FE critical thickness can reach the theoretical limit of 3.5 unit cells.
The Light‐Induced Field‐Effect Solar Cell Concept – Perovskite Nanoparticle Coating Introduces Polarization Enhancing Silicon Cell Efficiency
Authors: Wang Yusheng , Xia Zhouhui , Liu Lijia , Xu Weidong , Yuan Zhongcheng , Zhang Yupeng , Sirringhaus Henning , Lifshitz Yeshayahu , Lee Shui‐Tong , Bao Qiaoliang , Sun Baoquan
Published: March 2017

Solar cell generates electrical energy from light one via pulling excited carrier away under built‐in asymmetry. Doped semiconductor with antireflection layer is general strategy to achieve this including crystalline silicon (c‐Si) solar cell. However, loss of extra energy beyond band gap and light reflection in particular wavelength range is known to hinder the efficiency of c‐Si cell. Here, it is found that part of short wavelength sunlight can be converted into polarization electrical field, which strengthens asymmetry in organic‐c‐Si heterojunction solar cell through molecule alignment process. The light harvested by organometal trihalide perovskite nanoparticles (NPs) induces molecular alignment on a conducting polymer, which generates positive electrical surface field. Furthermore, a “field‐effect solar cell” is successfully developed and implemented by combining perovskite NPs with organic/c‐Si heterojunction associating with light‐induced molecule alignment, which achieves an efficiency of 14.3%. In comparison, the device with the analogous structure without perovskite NPs only exhibits an efficiency of 12.7%. This finding provides a novel concept to design solar cell by sacrificing part of sunlight to provide “extra” asymmetrical field continuously as to drive photogenerated carrier toward respective contacts under direct sunlight. Moreover, it also points out a method to combine promising perovskite material with c‐Si solar cell.
Quantum‐Dot Light‐Emitting Diodes for Large‐Area Displays: Towards the Dawn of Commercialization
Authors: Dai Xingliang , Deng Yunzhou , Peng Xiaogang , Jin Yizheng
Published: March 2017

Quantum dots are a unique class of emitters with size‐tunable emission wavelengths, saturated emission colors, near‐unity luminance efficiency, inherent photo‐ and thermal‐ stability and excellent solution processability. Quantum dots have been used as down‐converters for back‐lighting in liquid‐crystal displays to improve color gamut, leading to the booming of quantum‐dot televisions in consumer market. In the past few years, efficiency and lifetime of electroluminescence devices based on quantum dots achieved tremendous progress. These encouraging facts foreshadow the commercialization of quantum‐dot light‐emitting diodes (QLEDs), which promises an unprecedented generation of cost‐effective, large‐area, energy‐saving, wide‐color‐gamut, ultra‐thin and flexible displays. Here we provide a Progress Report, covering interdisciplinary aspects including material chemistry of quantum dots and charge‐transporting layers, optimization and mechanism studies of prototype devices and processing techniques to produce large‐area and high‐resolution red‐green‐blue pixel arrays. We also identify a few key challenges facing the development of active‐matrix QLED displays.
Toward High‐Quality Epitaxial LiNbO3 and LiTaO3 Thin Films for Acoustic and Optical Applications
Authors: Bartasyte Ausrine , Margueron Samuel , Baron Thomas , Oliveri Stefania , Boulet Pascal
Published: March 2017

Over the past five decades, LiNbO3 and LiTaO3 single crystals and thin films have been studied intensively for their exceptional acoustic, electro‐optical, and pyroelectric and ferroelectric properties. Today, LiNbO3 single crystals in electro‐optics are equivalent to silicon in electronics, and about 70% of radio‐frequency (RF) filters, based on surface acoustic waves, are fabricated on these single crystals. These materials in the form of thin films are needed urgently for the development of the next‐generation of high‐frequency and/or wide‐band RF filters or tuneable frequency filters adapted to the fifth generation of infrastructures/networks/communications. The integration of LiNbO3 films in guided nanophotonic devices will allow higher operational frequencies, wider bandwidth, and miniaturized optical devices in line with improved electronic conversion. Here, the challenges and the achievements in the epitaxial growth of LiTaO3 and LiNbO3 thin films and their integration with silicon technology and to acoustic and guided nanophotonic devices are discussed in detail. The systematic representation and classification of all epitaxial relationships reported in the literature have been carried out in order to help the prediction of the epitaxial orientations in the new heterostructures. Future prospects of potential applications and the expected performances of thin film devices are overviewed, as well.
Facile Synthesis of 3D Anode Assembly with Si Nanoparticles Sealed in Highly Pure Few Layer Graphene Deposited on Porous Current Collector for Long Life Li‐Ion Battery
Authors: Shelke Manjusha V. , Gullapalli Hemtej , Kalaga Kaushik , Rodrigues Marco‐Tulio F. , Devarapalli Rami Reddy , Vajtai Robert , Ajayan Pulickel M.
Published: March 2017

With its exceptional theoretical charge capacity, silicon holds great promise as an anode material for realization of high energy density Li‐ion batteries. However, extensive volume expansion and poor cycle stability of silicon compromise its actual use. In an effort to tame volume expansion and structural disintegration during cycling, an innovative 3D electrode assembly is fabricated involving continuous layer of graphene coated on porous current collector and Si nanoparticles sealed in as an active material. Graphene deposition and pore formation in metal current collector is achieved in a unique single step synthesis. All the active components like current collector, reacting material, and conducting material are manipulated in a way to produce synergistic architecture in a chemical vapor deposition process. Highly pure graphene deposited in this process enables efficient electron transfer from allover of the surface of silicon nanoparticles and prevents continuous solid electrolyte interphase layer formation. This binder free anode assembly shows extremely stable lithium storage performance for over 1000 cycles with 88% of initial capacity retention and 100% Coulombic efficiency.
Lithographically Defined Graphene Patterns
Authors: Zheng Yiqun , Wang Hua , Hou Shifeng , Xia Deying
Published: March 2017

With the maturation and development of graphene synthesis and deposition, the next challenge is to produce graphene patterns to advance the practical applications of graphene in areas related to energy, the environment, sensors, and health care. In recent years, lithographically defined graphene patterns have arisen and received considerable attention. The patterns generated by lithographical methods exhibit greater positional accuracy, nanoscale features, and better uniformity, in addition to producing ready‐to‐use final devices. Here, recent lithographical nanofabrication methods for the preparation of graphene nanopatterns, such as graphene nanoribbons and graphene nanomeshes, and their applications are reviewed. Fabrication techniques for graphene patterning are discussed, including electron‐beam lithography, nanoimprint lithography, nanosphere lithography, interferometric lithography, and ion beam lithography. Finally, future perspectives in the field are discussed.
Strategies Based on Nitride Materials Chemistry to Stabilize Li Metal Anode
Authors: Zhu Yizhou , He Xingfeng , Mo Yifei
Published: March 2017

Lithium metal battery is a promising candidate for high‐energy‐density energy storage. Unfortunately, the strongly reducing nature of lithium metal has been an outstanding challenge causing poor stability and low coulombic efficiency in lithium batteries. For decades, there are significant research efforts to stabilize lithium metal anode. However, such efforts are greatly impeded by the lack of knowledge about lithium‐stable materials chemistry. So far, only a few materials are known to be stable against Li metal. To resolve this outstanding challenge, lithium‐stable materials have been uncovered out of chemistry across the periodic table using first‐principles calculations based on large materials database. It is found that most oxides, sulfides, and halides, commonly studied as protection materials, are reduced by lithium metal due to the reduction of metal cations. It is discovered that nitride anion chemistry exhibits unique stability against Li metal, which is either thermodynamically intrinsic or a result of stable passivation. The results here establish essential guidelines for selecting, designing, and discovering materials for lithium metal protection, and propose multiple novel strategies of using nitride materials and high nitrogen doping to form stable solid‐electrolyte‐interphase for lithium metal anode, paving the way for high‐energy rechargeable lithium batteries.
A General Electrode Design Strategy for Flexible Fiber Micro‐Pseudocapacitors Combining Ultrahigh Energy and Power Delivery
Authors: Li Ping , Li Jing , Zhao Zhe , Fang Zhengsong , Yang Meijia , Yuan Zhongke , Zhang You , Zhang Qiang , Hong Wei , Chen Xudong , Yu Dingshan
Published: March 2017

Herein, a general strategy is proposed to boost the energy storage capability of pseudocapacitive materials (i.e., MnO2) to their theoretical limits in unconventional 1D fiber configuration by rationally designing bicontinuous porous Ni skeleton@metal wire “sheath–core” metallic scaffold as a versatile host. As a proof of concept, the 1D metallic scaffold supported‐MnO2 fiber electrode is demonstrated. The proposed “sheath” design not only affords large electrode surface area with ordered macropores for large electrolyte‐ion accessibility and high electroactive material loading, but also renders interconnected porous metallic skeleton for efficient electronic and ionic transport, while the metallic “core” functions as an extra current collector to promote long‐distance electron transport and electron collection. Benefiting from all these merits, the optimized fiber electrode yields unprecedented specific areal capacitance of 1303.6 mF cm−2 (1278 F g−1 based on MnO2, approaching the theoretical value of 1370 F g−1) in liquid KOH and 847.22 mF cm−2 in polyvinyl alcohol (PVA)/KOH gel electrolyte, 2–350 times of previously reported fiber electrodes. The solid‐state fiber micro‐pseudocapacitors simultaneously achieve remarkable areal energy and power densities of 18.83 µWh cm−2 and 16.33 mW cm−2, greatly exceeding the existing symmetric fiber supercapacitors, together with long cycle life and high rate capability.
Unprotected Aziridines: A Synthetic Overview
Authors: Sabir Shekh , Kumar Ganesh , Jat Jawahar L.
Published: March 2017

Unprotected (N−H) aziridines are the key components in several biologically active natural products and important building blocks in organic synthesis. However, the synthesis of unprotected aziridines is much more difficult than their oxygen counterparts (epoxides). Therefore, the development of efficient routes for their synthesis represents an attractive task for organic chemists and, as a result, a variety of methods have been developed. In this Focus Review, we have described the various approaches that have been reported for the synthesis of NH‐aziridines.
Preparation and antimicrobial activity of sulfopropyl chitosan in an ionic liquid aqueous solution
Authors: Wang Zhaodong , Zheng Liuchun , Li Chuncheng , Wu Shaohua , Xiao Yaonan
Published: March 2017

To improve the solubility and antibacterial activity of chitosan and expand its applications, we synthesized sulfopropyl chitosan (SP‐CS) with various degrees of substitution (DSs) under mild and green reaction conditions in the aqueous solution of an ionic liquid by a green process. The chemical structures of the polymers were verified by Fourier transform infrared spectroscopy and1H‐NMR, and the thermal stability was studied by thermogravimetric analysis. After modification, the water solubility of chitosan was improved significantly, and SP‐CS showed excellent solubility in water at neutral pH. The antibacterial activities of the SP‐CSs with various DSs were systematically studied for the first time by the Oxford cup method and optical density method. The results suggest that the antimicrobial properties of SP‐CS were enhanced by the introduction of sulfopropyl and increased with increasing DS. The application of chitosan could be expanded, and SP‐CS has the potential to be used as a water‐soluble antimicrobial. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2017,134, 44989.
Impact of acute fat mobilisation on the pharmacokinetics of the highly fat distributed compound TAK‐357, investigated by physiologically based pharmacokinetic (PBPK) modeling and simulation
Authors: Goto Akihiko , Tagawa Yoshihiko , Moriya Yuu , Sato Sho , Furukawa Yoshiyuki , Wakabayashi Takeshi , Tsukamoto Tetsuya , DeJongh Joost , van Steeg Tamara J. , Moriwaki Toshiya , Asahi Satoru
Published: March 2017

In a dog toxicokinetic study, an unusual plasma concentration increase of the highly lipophilic compound TAK‐357 was observed 2 weeks after termination of a 2‐week repeated dosing in one dog with acute body weight loss. The present study investigates the cause of this increase. A physiologically based pharmacokinetic (PBPK) model was constructed using the rat and dog pharmacokinetic data. Using the constructed model, the TAK‐357 concentration profile in the case of body weight change was simulated. The PBPK model‐derived simulation suggested that redistribution from adipose tissues to plasma due to a loss of body fat caused the observed concentration increase of TAK‐357 in dog plasma. The analysis demonstrates that the disposition of a highly lipophilic and fat‐distributed compound can be affected by acute changes in adipose tissue mass. PBPK modeling and simulation proved to be efficient tools for the quantitative hypothesis testing of apparently atypical PK phenomena resulting from acute physiological changes.
Exploratory Studies on the in Vitro Anti‐inflammatory Potential of Two Herbal Teas (Annona muricata L. and Jasminum grandiflorum L.), and Relation with Their Phenolic Composition
Authors: Oliveira Andreia P. , Sá Ivone , Pereira David M. , Gonçalves Rui F. , Andrade Paula B. , Valentão Patrícia
Published: March 2017

The need of new anti‐inflammatory drugs has led to the search for safer and more potent molecules in distinct sources, such as natural products. This work aimed to explore the anti‐inflammatory potential of aqueous extracts from two herbal teas (Annona muricata L. and Jasminum grandiflorum L.) in RAW 264.7 macrophages cells and in cell‐free assays. Furthermore, the phenolic composition of both extracts and of their hydrolysates was characterized by HPLC‐DAD, in order to establish possible relationships with the biological activity. In a general way, A. muricata displayed a stronger capacity to inhibit nitric oxide (NO) production and the activity of phospholipase A2 (PLA2), displaying an IC50 value of 142 μg/ml against this enzyme. A deeper look at phenolic compounds revealed that aglycones had more capacity to inhibit NO and PLA2 than their corresponding glycosides, quercetin being clearly the most potent one (IC50 = 7.47 and 1.36 μm, respectively). In addition, 5‐O‐caffeoylquinic acid, at 1.56 μm, could also inhibit PLA2 (ca. 35%). Our findings suggest that the consumption of both herbal teas may be a preventive approach to inflammatory disorders.
Protein NMR Studies of Substrate Binding to Human Blood Group A and B Glycosyltransferases
Authors: Grimm Lena Lisbeth , Weissbach Sophie , Flügge Friedemann , Begemann Nora , Palcic Monica M. , Peters Thomas
Published: March 2017

Donor and acceptor substrate binding to human blood group A and B glycosyltransferases (GTA, GTB) has been studied by a variety of protein NMR experiments. Prior crystallographic studies had shown these enzymes to adopt an open conformation in the absence of substrates. Binding either of the donor substrate UDP‐Gal or of UDP induces a semiclosed conformation. In the presence of both donor and acceptor substrates, the enzymes shift towards a closed conformation with ordering of an internal loop and the C‐terminal residues, which then completely cover the donor‐binding pocket. Chemical‐shift titrations of uniformly 2H,15N‐labeled GTA or GTB with UDP affected about 20 % of all crosspeaks in 1H,15N TROSY‐HSQC spectra, reflecting substantial plasticity of the enzymes. On the other hand, it is this conformational flexibility that impedes NH backbone assignments. Chemical‐shift‐perturbation experiments with δ1‐[13C]methyl‐Ile‐labeled samples revealed two Ile residues—Ile123 at the bottom of the UDP binding pocket, and Ile192 as part of the internal loop—that were significantly disturbed upon stepwise addition of UDP and H‐disaccharide, also revealing long‐range perturbations. Finally, methyl TROSY‐based relaxation dispersion experiments do not reveal micro‐ to millisecond timescale motions. Although this study reveals substantial conformational plasticity of GTA and GTB, the matter of how binding of substrates shifts the enzymes into catalytically competent states remains enigmatic.
Semiconducting Self‐Assembled Nanofibers Prepared from Photostable Octafluorinated Bisanthene Derivatives
Authors: Hayashi Hironobu , Aratani Naoki , Yamada Hiroko
Published: March 2017

Bisanthene is an important class of small two‐dimensional polycyclic aromatic hydrocarbons with a zigzag‐edged graphene nanoribbon character. Therefore, the functionalization and deep understanding of the structure–property relationship of bisanthene would provide an effective design for small organic molecular devices. In this study, octa‐ and tetrafluorinated bisanthene derivatives were synthesized for investigating the effect of electronegative fluorine substitution on the structure and physical property of bisanthene. Firstly, the octafluorinated bisanthene derivative has a twisted structure due to the steric repulsion of fluorine atoms at the bay region. Secondly, the absorption and fluorescence peak maxima are blueshifted with an increase in the degree of fluorine substitution. Notably, a triisopropylsilylethynyl‐substituted octafluorinated derivative (F8) exhibited strong fluorescence at 657 nm with high fluorescence quantum yield (84 %). Additionally, cyclic voltammograms indicate the positive effect of fluorine substitution on the high highest occupied molecular orbital energy level of the molecules; thus, F8 molecule exhibited a remarkably increased photostability. Finally, the self‐assembled behavior of fluorinated compounds was investigated by scanning electron microscopy and X‐ray diffraction analysis. Specifically, F8 self‐assembled to form bundles of long semicrystalline nanofibers exhibiting hole‐transporting properties (3.4×10−3 cm2 V−1 s−1).
Divalent Naphthalene Diimide Ligands Display High Selectivity for the Human Telomeric G‐quadruplex in K+ Buffer
Authors: Street Steven T. G. , Chin Donovan N. , Hollingworth Gregory J. , Berry Monica , Morales Juan C. , Galan M. Carmen
Published: March 2017

Selective G‐quadruplex ligands offer great promise for the development of anti‐cancer therapies. A novel series of divalent cationic naphthalene diimide ligands that selectively bind to the hybrid form of the human telomeric G‐quadruplex in K+ buffer are described herein. We demonstrate that an imidazolium‐bearing mannoside‐conjugate is the most selective ligand to date for this quadruplex against several other quadruplex and duplex structures. We also show that a similarly selective methylpiperazine‐bearing ligand was more toxic to HeLa cancer cells than doxorubicin, whilst exhibiting three times less toxicity towards fetal lung fibroblasts WI‐38.