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Soft matter has historically been an unlikely candidate for investigation by electron microscopy techniques due to damage by the electron beam as well as inherent instability under a high vacuum environment. Characterization of soft matter has often relied on ensemble-scattering techniques. The recent development of cryogenic transmission electron microscopy (cryo-TEM) provides the soft matter community with an exciting opportunity to probe the structure of soft materials in real space. Cryo-TEM reduces beam damage and allows for characterization in a native, frozen-hydrated state, providing direct visual representation of soft structure. This article reviews cryo-TEM in soft materials characterization and illustrates how it has provided unique insights not possible by traditional ensemble techniques. Soft matter systems that have benefited from the use of cryo-TEM include biological-based “soft” nanoparticles (e.g., viruses and conjugates), synthetic polymers, supramolecular materials as well as the organic–inorganic interface of colloidal nanoparticles. Many challenges remain, such as combining structural and chemical analyses; however, the opportunity for soft matter research to leverage newly developed cryo-TEM techniques continues to excite.
This article focuses on the finite element modeling of toroidal microinductors, employing first-of-its-kind nanocomposite magnetic core material and superparamagnetic iron nanoparticles covalently cross-linked in an epoxy network. Energy loss mechanisms in existing inductor core materials are covered as well as discussions on how this novel core material eliminates them providing a path toward realizing these low form factor devices. Designs for both a 2 μH output and a 500 nH input microinductor are created via the model for a high-performance buck converter. Both modeled inductors have 50 wire turns, less than 1 cm3 form factors, less than 1 Ω AC resistance, and quality factors, Q’s, of 27 at 1 MHz. In addition, the output microinductor is calculated to have an average output power of 7 W and a power density of 3.9 kW/in3 by modeling with the 1st generation iron nanocomposite core material.
Significant reductions recently seen in the size of wide-bandgap power electronics have not been accompanied by a relative decrease in the size of the corresponding magnetic components. To achieve this, a new generation of materials with high magnetic saturation and permeability are needed. Here, we develop gram-scale syntheses of superparamagnetic Fe/FexOy core–shell nanoparticles and incorporate them as the magnetic component in a strongly magnetic nanocomposite. Nanocomposites are typically formed by the organization of nanoparticles within a polymeric matrix. However, this approach can lead to high organic fractions and phase separation; reducing the performance of the resulting material. Here, we form aminated nanoparticles that are then cross-linked using epoxy chemistry. The result is a magnetic nanoparticle component that is covalently linked and well separated. By using this ‘matrix-free’ approach, we can substantially increase the magnetic nanoparticle fraction, while still maintaining good separation, leading to a superparamagnetic nanocomposite with strong magnetic properties.
There are multiple recent reports of an association between anxious/depressed (A/D) symptomatology and the rate of cerebral cortical thickness maturation in typically developing youths. We investigated the degree to which anxious/depressed symptoms are tied to age-related microstructural changes in cerebral fiber pathways. The participants were part of the NIH MRI Study of Normal Brain Development. Child Behavior Checklist A/D scores and diffusion imaging were available for 175 youths (84 males, 91 females; 241 magnetic resonance imagings) at up to three visits. The participants ranged from 5.7 to 18.4 years of age at the time of the scan. Alignment of fractional anisotropy data was implemented using FSL/Tract-Based Spatial Statistics, and linear mixed model regression was carried out using SPSS. Child Behavior Checklist A/D was associated with the rate of microstructural development in several white matter pathways, including the bilateral anterior thalamic radiation, bilateral inferior longitudinal fasciculus, left superior longitudinal fasciculus, and right cingulum. Across these pathways, greater age-related fractional anisotropy increases were observed at lower levels of A/D. The results suggest that subclinical A/D symptoms are associated with the rate of microstructural development within several white matter pathways that have been implicated in affect regulation, as well as mood and anxiety psychopathology.
How did the kings of England and France govern their kingdoms? This volume, the product of a ten-year international project, brings together specialists in late medieval England and France to explore the multiple mechanisms by which monarchs exercised their power in the final centuries of the Middle Ages. Collaborative chapters, mostly co-written by experts on each kingdom, cover topics ranging from courts, military networks and public finance; office, justice and the men of the church; to political representation, petitioning, cultural conceptions of political society; and the role of those excluded from formal involvement in politics. The result is a richly detailed and innovative comparison of the nature of government and political life, seen from the point of view of how the king ruled his kingdom, but bringing to bear the methods of social, cultural and economic history to understand the underlying armature of royal power.
This chapter relates to the work of Jenny Wormald in two rather different ways. First of all, the choice of ‘Renaissance England’ in the title picks up Jenny's invocation of ‘Renaissance Scotland’ – the title for the first part of Court, Kirk and Community, and a characteristically daring one, conjuring a world of Latinate learning, eloquent persuasion, courtly exuberance and contact with Europe in a period then still seen in ‘thud-and-blunder’ terms; or, as Jenny put it, ‘fallow’, ‘dreary’, ‘the bread and butter between two layers of jam’. Jenny showed that the kingdom of Scotland in the period 1470‒1542 had a particular kind of identity and dynamic, and I hope, in the following pages, to suggest the same for the kingdom south of the Border in the period when John Skelton was writing, from the late 1480s to the mid-1520s.
The second connection is more personal and parochial: happy memories of my first experience of Oxford Further Subject teaching in the late 1990s, in classes on ‘Literature and Politics in Early Modern England’, sitting alongside Jenny in the faded grandeur of the Lady Brodie Room at St Hilda's College, Oxford. Having established her right to smoke with a silencing glare at the undergraduates, Jenny would lead the discussion with a series of shrewd and pithy observations, while I, like any tyro, would run on verbosely about the three or four things I knew. The series of classes started with a bang – More's Utopia and some of his other writings – but, before the students could embark on the delights of Sidney, Spenser and Shakespeare, there were the Tudor court poets to get through, and here things tended to slow down. While Thomas Wyatt normally elicited some animated responses, and the earl of Surrey could be despatched more quickly than Henry VIII managed, the class began with Skelton – difficult, inelegant, and very foreign to students who wanted to study a sixteenth century lit up by Italy, not blasted from Norfolk. Things would dip, and the students would look nervous, as, for once, Jenny and I would disagree. My great mistake, it seemed, was to take Skelton seriously and to see him as important, and – now with more reading behind me – I want to persist with that line of argument.