Phase-transitions in spin-crossover thin films probed by graphene transport measurements

Future multi-functional hybrid devices might combine switchable molecules and 2D material-based devices. Spin-crossover compounds are of particular interest in this context since they exhibit bistability and memory effects at room temperature while responding to numerous external stimuli. Atomically-thin 2D materials such as graphene attract a lot of attention for their fascinating electrical, optical, and mechanical properties, but also for their reliability for room-temperature operations. Here, we demonstrate that thermally-induced spin-state switching of spin-crossover nanoparticle thin films can be monitored through the electrical transport properties of graphene lying underneath the films. Model calculations indicate that the charge carrier scattering mechanism in graphene is sensitive to the spin-state dependence of the relative dielectric constants of the spin-crossover nanoparticles. This graphene sensor approach can be applied to a wide class of (molecular) systems with tunable electronic polarizabilities.Comment: main text: 13 pages, 5 figures ; SI: 14 pages, 12 figure

Phase transitions between single- and double-layered smectic structures in binary mixtures of cyano-mesogens

Binary mixtures of mesogens which exhibit respectively single-layered (A 1), double layered (A2) and partially double layered (A d) smectic phases show abrupt A2-A1 or A2-Ad transitions as a function of concentration. Double layered structures imply the formation of dimerized entities and the possibility of dimerization is discussed in terms of the amphiphilic nature of the molecules in the binary mixture (symmetrical and dissymmetrical polar mesogens). The results are analysed with respect to the thermal stability of the A 2 phase when defects are introduced in the polar interface by adding non-polar symmetrical mesogens.Des mélanges binaires de mésogènes présentant respectivement des phases smectiques monocouches (A1), bicouches (A2) et partiellement bicouches (Ad) permettent de mettre en évidence en fonction de la concentration des transitions brusques A2-A1 ou A 2-Ad. La structure bicouche implique un processus de dimérisation des entités mésogènes qui est discuté en fonction du caractère amphipathique des molécules (molécules polaires symétriques et dissymétriques). La stabilité de la phase bicouche est également analysée lorsque l'on introduit une perturbation au niveau de l'interface polaire par adjonction de molécules non polaires

Structure bicouche des mésophases SA et SB du 4-cyanobutoxybenzylidene-4-octylaniline

In order to analyze the mesomorphic behavior of molecules containing a highly dipolar endgroup mechanically decoupled from the rigid moiety, the 4-cyanobutoxybenzylidene-4-octylaniline was synthesized. The first observations made (polarizing microscopy, differential scanning calorimetry, and X-ray diffraction) suggest the présence of two smectic mesophases, of B and A type respectively. The structure of these would correspond to double layers : in each sub-layer, the molecular arrangement would be of the ferro-type, and the stacking of the sub-layers would be of the antiferro-type. However, it is impossible to definitely specify the spatial extension of the order described, on the basis of the experimental data obtained so far.Pour analyser le comportement mésomorphe de molécules contenant un groupe fortement dipolaire découplé mécaniquement du tronçon rigide, nous avons synthétisé le 4-cyanobutoxybenzylidène-4-octylaniline. Les premières observations (microscope polarisant, enthalpimétrie différentielle, diffraction des rayons X) indiquent la présence de deux mésophases smectiques, l'une de type B et l'autre de type A. Celles-ci auraient une structure bicouche : dans chaque sous-couche, les molécules seraient arrangées de manière ferro- et les sous-couches, elles-mêmes, seraient superposées de manière antiferro- . Cependant, les données expérimentales obtenues ne permettent pas encore de se prononcer définitivement sur l'étendue spatiale de ce type d'ordre

Performativity, fabrication and trust: exploring computer-mediated moderation

Based on research conducted in an English secondary school, this paper explores computer mediated moderation as a performative tool. The Module Assessment Meeting (MAM) was the moderation approach under investigation. I mobilise ethnographic data generated by a key informant, and triangulated with that from other actors in the setting, in order to examine some of the meanings underpinning moderation within a performative environment. Drawing on the work of Ball (2003), Lyotard (1979) and Foucault (1977, 1979), I argue that in this particular case performativity has become entrenched in teachers’ day-to-day practices, and not only affects those practices but also teachers’ sense of self. I suggest that MAM represented performative and fabricated conditions and (re)defined what the key participant experienced as a vital constituent of her educational identities - trust. From examining the case in point, I hope to have illustrated for those interested in teachers’ work some of the implications of the interface between technology and performativity

Making sense of variety in place leadership: the case of England’s smart cities

Making sense of variety in place leadership: the case of England’s smart cities. Regional Studies. There is rising interest in cities becoming ‘smart’ knowledge-oriented economies by prioritizing more digitally enabled modes of production and service delivery. Whilst the prevalence of these new organizational forms is well understood, the way that leadership agency is exercised (i.e., the actors involved and their modalities of action) is not. Drawing on new empirical data and sense-making methodology, the paper reveals discursive patterns in how public agencies, private firms and communities ‘see’ and ‘do’ leadership within these place-based contexts, and concludes that success in exploiting the social and spatial dynamics of ‘smart’ development lies in understanding actors’ assumptions about commercial and social gain

The food superstore revolution: changing times, changing research agendas in the UK

This paper considers the changing scope of research into UK food superstores over a 30-year period. Rather than catalogue changing market shares by format, we seek instead to show how change links to national policy agendas. Academic research has evolved to address the growing complexities of the social, technological, economic and political impacts of the superstore format. We exemplify this by tracing the progression of retail change in Portsmouth, Hampshire, over 30 years. We discover that academic research can conflict with the preconceptions of some public policymakers. The position is exacerbated by a progressive decline in public information – and a commensurate rise in factual data held by commercial data companies – that leaves policymakers with a choice of which data to believe. This casts a shadow over the objectivity of macro-policy as currently formulated. Concerns currently arise because the UK Competition Commission (2008 but ongoing) starts each inquiry afresh with a search for recent data. Furthermore, it has recently called for changes to retail planning – the very arena in which UK superstore research commenced

Elite discourse and institutional innovation: making the hybrid happen in English public services

This paper focuses on the strategic role of elites in managing institutional and organizational change within English public services, framed by the wider ideological and political context of neo-liberalism and its pervasive impact on the social and economic order over recent decades. It also highlights the unintended consequences of this elite-driven programme of institutional reform as realized in the emergence of hybridized regimes of ‘polyarchic governance’ and the innovative discursive and organizational technologies on which they depend. Within the latter, ‘leaderism’ is identified as a hegemonic ‘discursive imaginary’ that has the potential to connect selected marketization and market control elements of new public management (NPM), network governance, and visionary and shared leadership practices that ‘make the hybrid happen’ in public services reform

Role of transglutaminase 2 in PAC1 receptor mediated protection against hypoxia-induced cell death and neurite outgrowth in differentiating N2a neuroblastoma cells

The PAC1 receptor and tissue transglutaminase (TG2) play important roles in neurite outgrowth and modulation of neuronal cell survival. In this study, we investigated the regulation of TG2 activity by the PAC1 receptor in retinoic acid-induced differentiating N2a neuroblastoma cells. TG2 transamidase activity was determined using an amine incorporation and a peptide cross linking assay. In situ TG2 activity was assessed by visualising the incorporation of biotin-X-cadaverine using confocal microscopy. TG2 phosphorylation was monitored via immunoprecipitation and Western blotting. The role of TG2 in PAC1 receptor-induced cytoprotection and neurite outgrowth was investigated by monitoring hypoxia-induced cell death and appearance of axonal-like processes, respectively. The amine incorporation and protein crosslinking activity of TG2 increased in a time and concentration-dependent manner following stimulation with pituitary adenylate cyclase-activating polypeptide-27 (PACAP-27). PACAP-27 mediated increases in TG2 activity were abolished by the TG2 inhibitors Z-DON and R283 and by pharmacological inhibition of protein kinase A (KT 5720 and Rp-cAMPs), protein kinase C (Ro 31-8220), MEK1/2 (PD 98059), and removal of extracellular Ca2+. Fluorescence microscopy demonstrated PACAP-27 induced in situ TG2 activity. TG2 inhibition blocked PACAP-27 induced attenuation of hypoxia-induced cell death and outgrowth of axon-like processes. TG2 activation and cytoprotection were also observed in human SH-SY5Y cells. Together, these results demonstrate that TG2 activity was stimulated downstream of the PAC1 receptor via a multi protein kinase dependent pathway. Furthermore, PAC1 receptor-induced cytoprotection and neurite outgrowth are dependent upon TG2. These results highlight the importance of TG2 in the cellular functions of the PAC1 receptor

Single ion magnets based on lanthanoid polyoxomolybdate complexes

Polyoxometalate (POM) chemistry has recently offered excellent examples of single ion magnets (SIMs) and molecular spin qubits. Compared with conventional coordination compounds, POMs provide rigid and highly symmetric coordination sites. However, all POM-based SIMs reported to date exhibit a very limited range of possibilities for chemical processability. We present herein two new families of POM-based SIMs which are soluble in organic solvents: [Ln(β-Mo8O26)2]5− {LnIII = Tb, Dy, Ho, Er, Tm and Yb} and the functionalised POMs [Ln{Mo5O13(OMe)4NNC6H4-p-NO2}2]3− {LnIII = Tb, Dy, Ho, Er, Yb and Nd}. In addition, these two families represent the first SIMs based on polyoxomolybdates. A magneto-structural analysis of these families is presented, which is based on an effective crystal field model, and compared with the results reported in analogous lanthanoid SIMs based on polyoxotungstates.ERC-2014-CoG/ 647301CM1203CA15128MAT2014-56143-RCTQ2014-52758-PMDM-2015-0538Polyoxometalate (POM) chemistry has recently offered excellent examples of single ion magnets (SIMs) and molecular spin qubits. Compared with conventional coordination compounds, POMs provide rigid and highly symmetric coordination sites. However, all POM-based SIMs reported to date exhibit a very limited range of possibilities for chemical processability. We present herein two new families of POM-based SIMs which are soluble in organic solvents: [Ln(β-Mo8O26)2]5− {LnIII = Tb, Dy, Ho, Er, Tm and Yb} and the functionalised POMs [Ln{Mo5O13(OMe)4NNC6H4-p-NO2}2]3− {LnIII = Tb, Dy, Ho, Er, Yb and Nd}. In addition, these two families represent the first SIMs based on polyoxomolybdates. A magneto-structural analysis of these families is presented, which is based on an effective crystal field model, and compared with the results reported in analogous lanthanoid SIMs based on polyoxotungstates