scholarly journals The Use of Scattering Data in the Study of the Molecular Organisation of Polymers in the Non-Crystalline State

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2917
Author(s):  
Thomas Gkourmpis ◽  
Geoffrey R. Mitchell
Keyword(s):  
Crystalline State ◽  
Glassy State ◽  
Quantitative Information ◽  
Chain Conformation ◽  
Molecular Organization ◽  
Scattering Data ◽  
Diverse Range ◽  
Recent Developments ◽  
Quantitative Manner ◽  
Level Model

Scattering data for polymers in the non-crystalline state, i.e., the glassy state or the molten state, may appear to contain little information. In this work, we review recent developments in the use of scattering data to evaluate in a quantitative manner the molecular organization of such polymer systems. The focus is on the local structure of chain segments, on the details of the chain conformation and on the imprint the inherent chemical connectivity has on this structure. We show the value of tightly coupling the scattering data to atomistic-level computer models. We show how quantitative information about the details of the chain conformation can be obtained directly using a model built from definitions of relatively few parameters. We show how scattering data may be supplemented with data from specific deuteration sites and used to obtain information hidden in the data. Finally, we show how we can exploit the reverse Monte Carlo approach to use the data to drive the convergence of the scattering calculated from a 3d atomistic-level model with the experimental data. We highlight the importance of the quality of the scattering data and the value in using broad Q scattering data obtained using neutrons. We illustrate these various methods with results drawn from a diverse range of polymers.

Vitamin D

2005 ◽  
Vol 289 (1) ◽  
pp. F8-F28 ◽  
Author(s):  
Adriana S. Dusso ◽  
Alex J. Brown ◽  
Eduardo Slatopolsky
Keyword(s):  
Vitamin D ◽  
Target Genes ◽  
Endocrine System ◽  
Target Cells ◽  
Vitamin D Metabolism ◽  
Diverse Range ◽  
Hydroxyvitamin D ◽  
Dihydroxyvitamin D ◽  
Single Receptor ◽  
Recent Developments

The vitamin D endocrine system plays an essential role in calcium homeostasis and bone metabolism, but research during the past two decades has revealed a diverse range of biological actions that include induction of cell differentiation, inhibition of cell growth, immunomodulation, and control of other hormonal systems. Vitamin D itself is a prohormone that is metabolically converted to the active metabolite, 1,25-dihydroxyvitamin D [1,25(OH)2D]. This vitamin D hormone activates its cellular receptor (vitamin D receptor or VDR), which alters the transcription rates of target genes responsible for the biological responses. This review focuses on several recent developments that extend our understanding of the complexities of vitamin D metabolism and actions: the final step in the activation of vitamin D, conversion of 25-hydroxyvitamin D to 1,25(OH)2D in renal proximal tubules, is now known to involve facilitated uptake and intracellular delivery of the precursor to 1α-hydroxylase. Emerging evidence using mice lacking the VDR and/or 1α-hydroxylase indicates both 1,25(OH)2D3-dependent and -independent actions of the VDR as well as VDR-dependent and -independent actions of 1,25(OH)2D3. Thus the vitamin D system may involve more than a single receptor and ligand. The presence of 1α-hydroxylase in many target cells indicates autocrine/paracrine functions for 1,25(OH)2D3in the control of cell proliferation and differentiation. This local production of 1,25(OH)2D3is dependent on circulating precursor levels, providing a potential explanation for the association of vitamin D deficiency with various cancers and autoimmune diseases.

The enactive approach

2011 ◽  
Vol 19 (1) ◽  
pp. 1-36 ◽  
Author(s):  
Tom Froese ◽  
Ezequiel A. Di Paolo
Keyword(s):  
Social Interaction ◽  
Cultural Values ◽  
Operational Definition ◽  
Diverse Range ◽  
Enactive Approach ◽  
Core Set ◽  
Recent Developments ◽  
Personal Action ◽  
Definition Of ◽  
Novel Applications

There is a small but growing community of researchers spanning a spectrum of disciplines which are united in rejecting the still dominant computationalist paradigm in favor of the enactive approach. The framework of this approach is centered on a core set of ideas, such as autonomy, sense-making, emergence, embodiment, and experience. These concepts are finding novel applications in a diverse range of areas. One hot topic has been the establishment of an enactive approach to social interaction. The main purpose of this paper is to serve as an advanced entry point into these recent developments. It accomplishes this task in a twofold manner: (i) it provides a succinct synthesis of the most important core ideas and arguments in the theoretical framework of the enactive approach, and (ii) it uses this synthesis to refine the current enactive approach to social interaction. A new operational definition of social interaction is proposed which not only emphasizes the cognitive agency of the individuals and the irreducibility of the interaction process itself, but also the need for jointly co-regulated action. It is suggested that this revised conception of ‘socio-cognitive interaction’ may provide the necessary middle ground from which to understand the confluence of biological and cultural values in personal action.

Recent developments in small-angle X-ray scattering and hybrid method approaches for biomacromolecular solutions

2018 ◽  
Vol 2 (1) ◽  
pp. 69-79 ◽  
Author(s):  
Martin A. Schroer ◽  
Dmitri I. Svergun
Keyword(s):  
Small Angle ◽  
Scattering Data ◽  
Quality Data ◽  
Biological Macromolecules ◽  
Ambient Conditions ◽  
X Ray ◽  
X Ray Scattering ◽  
Analysis Methods ◽  
Recent Developments ◽  
Ray Scattering

Small-angle X-ray scattering (SAXS) has become a streamline method to characterize biological macromolecules, from small peptides to supramolecular complexes, in near-native solutions. Modern SAXS requires limited amounts of purified material, without the need for labelling, crystallization, or freezing. Dedicated beamlines at modern synchrotron sources yield high-quality data within or below several milliseconds of exposure time and are highly automated, allowing for rapid structural screening under different solutions and ambient conditions but also for time-resolved studies of biological processes. The advanced data analysis methods allow one to meaningfully interpret the scattering data from monodisperse systems, from transient complexes as well as flexible and heterogeneous systems in terms of structural models. Especially powerful are hybrid approaches utilizing SAXS with high-resolution structural techniques, but also with biochemical, biophysical, and computational methods. Here, we review the recent developments in the experimental SAXS practice and in analysis methods with a specific focus on the joint use of SAXS with complementary methods.

scholarly journals Comparison of Multiscale Imaging Methods for Brain Research

Cells ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 1377
Author(s):  
Jessica Tröger ◽  
Christian Hoischen ◽  
Birgit Perner ◽  
Shamci Monajembashi ◽  
Aurélien Barbotin ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
Brain Research ◽  
Super Resolution ◽  
Synaptic Proteins ◽  
Physiological Status ◽  
Basic Set ◽  
Recent Developments ◽  
Quantitative Manner ◽  
The Impact ◽  
The Brain

A major challenge in neuroscience is how to study structural alterations in the brain. Even small changes in synaptic composition could have severe outcomes for body functions. Many neuropathological diseases are attributable to disorganization of particular synaptic proteins. Yet, to detect and comprehensively describe and evaluate such often rather subtle deviations from the normal physiological status in a detailed and quantitative manner is very challenging. Here, we have compared side-by-side several commercially available light microscopes for their suitability in visualizing synaptic components in larger parts of the brain at low resolution, at extended resolution as well as at super-resolution. Microscopic technologies included stereo, widefield, deconvolution, confocal, and super-resolution set-ups. We also analyzed the impact of adaptive optics, a motorized objective correction collar and CUDA graphics card technology on imaging quality and acquisition speed. Our observations evaluate a basic set of techniques, which allow for multi-color brain imaging from centimeter to nanometer scales. The comparative multi-modal strategy we established can be used as a guide for researchers to select the most appropriate light microscopy method in addressing specific questions in brain research, and we also give insights into recent developments such as optical aberration corrections.

scholarly journals Uniqueness of models from small-angle scattering data: the impact of a hydration shell and complementary NMR restraints

2015 ◽  
Vol 71 (1) ◽  
pp. 57-66 ◽  
Author(s):  
Henry S. Kim ◽  
Frank Gabel
Keyword(s):  
Small Angle ◽  
Hydration Shell ◽  
Small Angle Scattering ◽  
Conformational Space ◽  
Scattering Data ◽  
Body System ◽  
Angle Scattering ◽  
Recent Developments ◽  
The Impact ◽  
Nmr Restraints

Small-angle scattering (SAS) has witnessed a breathtaking renaissance and expansion over the past 15 years regarding the determination of biomacromolecular structures in solution. While important issues such as sample quality, good experimental practice and guidelines for data analysis, interpretation, presentation, publication and deposition are increasingly being recognized, crucial topics such as the uniqueness, precision and accuracy of the structural models obtained by SAS are still only poorly understood and addressed. The present article provides an overview of recent developments in these fields with a focus on the influence of complementary NMR restraints and of a hydration shell on the uniqueness of biomacromolecular models. As a first topic, the impact of incorporating NMR orientational restraints in addition to SAS distance restraints is discussed using a quantitative visual representation that illustrates how the possible conformational space of a two-body system is reduced as a function of the available data. As a second topic, the impact of a hydration shell on modelling parameters of a two-body system is illustrated, in particular on its inter-body distance. Finally, practical recommendations are provided to take both effects into account and promising future perspectives of SAS approaches are discussed.

Questioning the implementation of smart specialisation: Regional innovation policy and semi-autonomous regions

2017 ◽  
Vol 36 (3) ◽  
pp. 530-547 ◽  
Author(s):  
Rhiannon Pugh
Keyword(s):  
Innovation Policy ◽  
Innovation System ◽  
Regional Innovation ◽  
Diverse Range ◽  
Border Regions ◽  
Regional Innovation Policy ◽  
Smart Specialisation ◽  
Recent Developments ◽  
The Uk

This paper considers the recent developments in regional innovation policy pertaining to the smart specialisation agenda from the perspective of a peripheral and semi-autonomous region – Wales in the UK. Through a case study of innovation policy developments in Wales over the past 20 years, and also a consideration of extant literature pertaining to regional innovation policy and smart specialisation, this paper finds a number of issues or shortcomings in the current predominant smart specialisation approach. These are traced back to the strong regional innovation system logic existing in European policy; a number of unresolved theoretical problems that could undermine the efficacy of innovation policy are identified. Both conceptual and rhetorical issues with the concept of the region are highlighted, and questions are asked about the applicability and tenability of smart specialisation approaches in semi-autonomous, cross-border regions, and for policymakers operating in circumstances of multi-level governance. This paper illustrates how such regions provide us with a lens or alternative perspective through which to reconsider our predominant theoretical and practical policy approaches, and highlights a number of potential problems with smart specialisation as it is applied in a diverse range of regional settings.

From singular to over-crowded region: Curriculum change in senior secondary school music in New Zealand

2012 ◽  
Vol 29 (3) ◽  
pp. 317-330 ◽  
Author(s):  
Graham McPhail
Keyword(s):  
New Zealand ◽  
Music Curriculum ◽  
Music Learning ◽  
Diverse Range ◽  
Informal Music Learning ◽  
School Music ◽  
Recent Developments ◽  
Curriculum Construction ◽  
Senior Secondary ◽  
The Relationship

This paper discusses recent developments in the senior music curriculum in New Zealand. I suggest that school music is in transition from its clearly defined origins to its ‘regionalisation’ by new content and knowledge. The concepts of knowledge differentiation and verticality are considered in relation to the subject's now diverse range of curriculum segments, and I argue that the varied progression requirements of these segments combined with an ‘emptying out’ of significant aspects of knowledge within an outcomes-based curriculum presents significant challenges for curriculum construction and pedagogy. Also vying for space within the curriculum are elements of informal music learning. These challenges need to be carefully considered in light of recent social realist critiques which highlight the significance of the relationship between knowledge structures, curriculum, pedagogy and student access to powerful knowledge.

Progress in the Development of a Mechanical Properties Microprobe

MRS Bulletin ◽  
1986 ◽  
Vol 11 (5) ◽  
pp. 15-21 ◽  
Author(s):  
W. C. Oliver
Keyword(s):  
Mechanical Properties ◽  
Mechanical Response ◽  
Quantitative Information ◽  
General Term ◽  
Strength Properties ◽  
Physical Measurements ◽  
Wide Range ◽  
The Matrix ◽  
Recent Developments ◽  
Skilled Practitioner

A mechanical properties microprobe is an exciting concept. A system with the ability to evaluate the mechanical response of a sample with submicron spacial resolution would have an extremely wide range of applications. Recent developments in hardware and understanding have placed this goal within our grasp.In 1971, J.J.Gilman wrote the following in his article, “Hardness—A Strength Microprobe”:“Hardness measurements are at once among the most maligned and the most magnificent of physical measurements. Maligned because they are often misinterpreted by the uninitiated, and magnificent because they are so efficient in generating information for the skilled practitioner. They can quickly yield quantitative information about the elastic, anelastic, plastic, viscous, and fracture properties of a great variety of both isotropic and anisotropic solids. The tools that are used are simple and the sample sizes that are needed are typically small, sometimes submicroscopic. This makes it unnecessary to have large specimens in order to measure strength properties and makes it possible to measure the properties of various microscopic particles within the matrix phase of a polyphase metal, mineral, or ceramic material. This is why hardness may be considered to be a strength microprobe.”These statements are worth repeating for two reasons. First, they point out the largely untapped potential for microin-dentation tests to improve our understanding of the mechanical properties of materials. Second, it is the first mention of hardness tests in the context of a strength microprobe. In this article the more general term of microindentation tests will be used, since hardness is only one of many properties that can be measured with such tests. In addition, the term mechanical properties microprobe (MPM) will be used rather than strength microprobe-again, to note the wide variety of properties that can be measured.

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