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"Robinson, Ian"
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Collaborative school leadership : managing a group of schools
\"Collaborative School Leadership investigates how and why more collaboration is taking place in a wide range of settings in the UK, South Africa, New Zealand, China, the USA, the Seychelles, Tanzania and Greece, and considers the implications for leadership and the overall effectiveness of schools. David Middlewood, Ian Abbott and Sue Robinson explore various models of collaboration, considering their strengths, weaknesses and how they affect school leadership, including: executive leadership, school-to-school collaboration, federations, alliances, academy chains. The supportive structure of each chapter, with bullet point introduction, case studies, points of reflection, further reading and summaries, guides the reader and supports learning. Drawing on research, the authors identify the key areas for consideration, addressing questions such as: Where does leadership reside in collaborating partnerships? Who exactly are the leaders? What impact does this leadership have on others -staff, parents, governors, learners? What kind of leadership development is desirable? They look at the fact that the skills and approaches used by leaders of single schools are not automatically transferable to the leadership of several schools and propose possible ways forward for leadership and consider potential implications for education systems as a whole. They provide both an invaluable insight and also a practical guide for the school leaders of tomorrow\" -- Provided by publisher.
Book
Beyond crystallography: Diffractive imaging using coherent x-ray light sources
X-ray crystallography has been central to the development of many fields of science over the past century. It has now matured to a point that as long as good-quality crystals are available, their atomic structure can be routinely determined in three dimensions. However, many samples in physics, chemistry, materials science, nanoscience, geology, and biology are noncrystalline, and thus their three-dimensional structures are not accessible by traditional x-ray crystallography. Overcoming this hurdle has required the development of new coherent imaging methods to harness new coherent x-ray light sources. Here we review the revolutionary advances that are transforming x-ray sources and imaging in the 21st century.
Journal Article
Coherent X-ray diffraction imaging of strain at the nanoscale
The understanding and management of strain is of fundamental importance in the design and implementation of materials. The strain properties of nanocrystalline materials are different from those of the bulk because of the strong influence of their surfaces and interfaces, which can be used to augment their function and introduce desirable characteristics. Here we explain how new X-ray diffraction techniques, which take advantage of the latest synchrotron radiation sources, can be used to obtain quantitative three-dimensional images of strain. These methods will lead, in the near future, to new knowledge of how nanomaterials behave within active devices and on unprecedented timescales.
Journal Article
The Eagle has landed : 50 years of lunar science fiction
\"In celebration of the 50th anniversary of the Apollo 11 landing, the endlessly-mysterious moon is explored in this reprint short science fiction anthology from award-winning editor and anthologist Neil Clarke ... On July 20, 1969, mankind made what had only years earlier seemed like an impossible leap forward: when Apollo 11 became the first manned mission to land on the moon, and Neil Armstrong the first person to step foot on the lunar surface. While there have only been a handful of new missions since, the fascination with our planet's satellite continues, and generations of writers and artists have imagined the endless possibilities of lunar life. From adventures in the vast gulf of space between the earth and the moon, to journeys across the light face to the dark side, to the establishment of permanent residences on its surface, science fiction has for decades given readers bold and forward-thinking ideas about our nearest interstellar neighbor and what it might mean to humankind, both now and in our future. [This book] collects the best stories written in the fifty years since mankind first stepped foot on the lunar surface, serving as a shining reminder that the moon is and always has been our most visible and constant example of all the infinite possibility of the wider universe\"-- Provided by publisher.
BOOK
Phase retrieval by coherent modulation imaging
Phase retrieval is a long-standing problem in imaging when only the intensity of the wavefield can be recorded. Coherent diffraction imaging is a lensless technique that uses iterative algorithms to recover amplitude and phase contrast images from diffraction intensity data. For general samples, phase retrieval from a single-diffraction pattern has been an algorithmic and experimental challenge. Here we report a method of phase retrieval that uses a known modulation of the sample exit wave. This coherent modulation imaging method removes inherent ambiguities of coherent diffraction imaging and uses a reliable, rapidly converging iterative algorithm involving three planes. It works for extended samples, does not require tight support for convergence and relaxes dynamic range requirements on the detector. Coherent modulation imaging provides a robust method for imaging in materials and biological science, while its single-shot capability will benefit the investigation of dynamical processes with pulsed sources, such as X-ray free-electron lasers.
Robust coherent diffractive imaging generally requires many exposures that may damage samples. Here, the authors develop a single-shot X-ray imaging method applicable to general samples for materials and biological sciences, also enabling imaging of dynamic processes, using a pulsed X-ray laser.
Journal Article
Origin of structural degradation in Li-rich layered oxide cathode
Li- and Mn-rich (LMR) cathode materials that utilize both cation and anion redox can yield substantial increases in battery energy density
1
–
3
. However, although voltage decay issues cause continuous energy loss and impede commercialization, the prerequisite driving force for this phenomenon remains a mystery
3
–
6
Here, with in situ nanoscale sensitive coherent X-ray diffraction imaging techniques, we reveal that nanostrain and lattice displacement accumulate continuously during operation of the cell. Evidence shows that this effect is the driving force for both structure degradation and oxygen loss, which trigger the well-known rapid voltage decay in LMR cathodes. By carrying out micro- to macro-length characterizations that span atomic structure, the primary particle, multiparticle and electrode levels, we demonstrate that the heterogeneous nature of LMR cathodes inevitably causes pernicious phase displacement/strain, which cannot be eliminated by conventional doping or coating methods. We therefore propose mesostructural design as a strategy to mitigate lattice displacement and inhomogeneous electrochemical/structural evolutions, thereby achieving stable voltage and capacity profiles. These findings highlight the significance of lattice strain/displacement in causing voltage decay and will inspire a wave of efforts to unlock the potential of the broad-scale commercialization of LMR cathode materials.
Diffractive imaging of an important class of battery electrodes during cycling shows that lattice strain is a crucial yet overlooked factor that contributes to voltage fade over time.
Journal Article
Three-dimensional imaging of dislocation propagation during crystal growth and dissolution
It is demonstrated that Bragg coherent diffraction imaging can be used to visualize dislocation propagation in three dimensions during the repeated growth and dissolution of calcite crystals.
Atomic-level defects such as dislocations play key roles in determining the macroscopic properties of crystalline materials
1
,
2
. Their effects range from increased chemical reactivity
3
,
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to enhanced mechanical properties
5
,
6
. Dislocations have been widely studied using traditional techniques such as X-ray diffraction and optical imaging. Recent advances have enabled atomic force microscopy to study single dislocations
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in two dimensions, while transmission electron microscopy (TEM) can now visualize strain fields in three dimensions with near-atomic resolution
8
,
9
,
10
. However, these techniques cannot offer three-dimensional imaging of the formation or movement of dislocations during dynamic processes. Here, we describe how Bragg coherent diffraction imaging (BCDI; refs
11
,
12
) can be used to visualize in three dimensions, the entire network of dislocations present within an individual calcite crystal during repeated growth and dissolution cycles. These investigations demonstrate the potential of BCDI for studying the mechanisms underlying the response of crystalline materials to external stimuli.
Journal Article
Complex imaging of phase domains by deep neural networks
The reconstruction of a single-particle image from the modulus of its Fourier transform, by phase-retrieval methods, has been extensively applied in X-ray structural science. Particularly for strong-phase objects, such as the phase domains found inside crystals by Bragg coherent diffraction imaging (BCDI), conventional iteration methods are time consuming and sensitive to their initial guess because of their iterative nature. Here, a deep-neural-network model is presented which gives a fast and accurate estimate of the complex single-particle image in the form of a universal approximator learned from synthetic data. A way to combine the deep-neural-network model with conventional iterative methods is then presented to refine the accuracy of the reconstructed results from the proposed deep-neural-network model. Improved convergence is also demonstrated with experimental BCDI data.
Journal Article
3D lattice distortions and defect structures in ion-implanted nano-crystals
Focussed Ion Beam (FIB) milling is a mainstay of nano-scale machining. By manipulating a tightly focussed beam of energetic ions, often gallium (Ga
+
), FIB can sculpt nanostructures via localised sputtering. This ability to cut solid matter on the nano-scale revolutionised sample preparation across the life, earth and materials sciences. Despite its widespread usage, detailed understanding of the FIB-induced structural damage, intrinsic to the technique, remains elusive. Here we examine the defects caused by FIB in initially pristine objects. Using Bragg Coherent X-ray Diffraction Imaging (BCDI), we are able to spatially-resolve the full lattice strain tensor in FIB-milled gold nano-crystals. We find that
every
use of FIB causes large lattice distortions. Even very low ion doses, typical of FIB imaging and previously thought negligible, have a dramatic effect. Our results are consistent with a damage microstructure dominated by vacancies, highlighting the importance of free-surfaces in determining which defects are retained. At larger ion fluences, used during FIB-milling, we observe an extended dislocation network that causes stresses far beyond the bulk tensile strength of gold. These observations provide new fundamental insight into the nature of the damage created and the defects that lead to a surprisingly inhomogeneous morphology.
Journal Article