Jahn-Teller-driven Phase Segregation in Mnx_{x}Co3−x_{3-x}O4_{4} Spinel Thin Films

Transition metal spinel oxides comprised of Earth-abundant Mn and Co have long been explored for their use in catalytic reactions and energy storage. However, understanding of functional properties can be challenging due to differences in sample preparation and the ultimate structural properties of the materials. Epitaxial thin film synthesis provides a novel means of producing precisely-controlled materials to explore the variations reported in the literature. In this work, Mn$_{x}$Co$_{3-x}$O$_{4}$ samples from x = 0 to x = 1.28 were synthesized through molecular beam epitaxy and characterized to develop a material properties map as a function of stoichiometry. Films were characterized via in situ X-ray photoelectron spectroscopy, X-ray diffraction, scanning transmission electron microscopy, and polarized K-edge X-ray absorption spectroscopy. Mn cations within this range were found to be octahedrally coordinated, in line with an inverse spinel structure. Samples largely show mixed Mn$^{3+}$ and Mn$^{4+}$ character with evidence of phase segregation tendencies with increasing Mn content and increasing Mn$^{3+}$ formal charge. Phase segregation may occur due to structural incompatibility between cubic and tetragonal crystal structures associated with Mn$^{4+}$ and Jahn-Teller active Mn$^{3+}$ octahedra, respectively. Our results help to explain the reported differences across samples in these promising materials for renewable energy technologies.Comment: 25 pages, 8 figures; Supplemental info and figures, 9 page

Synergistic inhibition of prostate cancer cell lines by a 19- nor hexafluoride vitamin D3 analogue and anti-activator protein 1 retinoid

The secosteroid hormones, all- trans- and 9- cis -retinoic acid and vitamin D3, have demonstrated significant capacity to control proliferation in itro of many solid tumour cell lines. Cooperative synergistic effects by these two ligands have been reported, and it is, therefore, possible that greater therapeutic effects could be achieved if these compounds were administered together. The role of retinoid-dependent anti-activator protein 1 (anti-AP-1) effects in controlling cancer cell proliferation appears significant. We have utilized an anti- AP-1 retinoid [2-(4,4-dimethyl-3,4-dihydro-2H-1 benzopyran-6-yl)carbonyl-2-(4-carboxyphenyl)-1,3,-dithiane; SR11238], which does not transactivate through a retinoic acid response element (RARE), and a potent vitamin D3analogue [1α,25(OH)2-16-ene-23-yne-26,27-F6-19-nor -D3, code name LH] together at low, physiologically safer doses against a panel of prostate cancer cell lines that represent progressively more transformed phenotypes. The LNCaP (least transformed) and PC-3 (intermediately transformed) cell lines were synergistically inhibited in their clonal growth by the combination of LH and SR11238, whereas SR11238 alone was essentially inactive. DU-145 cells (most transformed) were completely insensitive to these analogues. LNCaP cells, but neither PC-3 nor DU-145, underwent apoptosis in the presence of LH and SR11238. Transactivation of the human osteocalcin vitamin D response element (VDRE) by LH was not enhanced in the presence of SR11238, although the expression of E-cadherin in these cells was additively up-regulated in the presence of both compounds. These data suggest the anti-AP-1 retinoid and the vitamin D3 analogue may naturally act synergistically to control cell proliferation, a process that is interrupted during transformation, and that this combination may form the basis for treatment of some androgen-independent prostate cancer. © 1999 Cancer Research Campaig

Vocational knowledge: regions and recontextualisation capability

This paper focuses on the constitution of vocational knowledge, and the development of an analytical framework that seeks to identify and characterise how that knowledge is constituted. Bernstein’s concept of a 'region' is outlined as a socio-epistemic entity into which various aspects of disciplinary knowledge are ‘recontextualised’ to meet the requirements of practice. This leads to a discussion of both the ‘internal’ social relations that exist between organisations involved in recontextualisation, and the ‘external’ factors that influence the character of regions, including relations between occupations and the broader macro-context pertinent to vocational practice. Issues of ‘recontextualisation capability’ are considered particularly important for understanding the nature of regions. While it is possible to conceive this capability at a variety of 'levels' or in relation to various activities, how knowledge achieves validity in the vocational community and provides a basis for a curriculum is particularly foregrounded here. The discussion is bolstered with examples of regions and recontextualisation processes taken from recent studies of higher apprenticeships in England between 2012-4. In addition, there is some brief engagement with comparative research into vocational education and training systems in order to better understand how differing national contexts and policy-driven change may (re) orientate regions and their capacity to recontextualise