Electrical properties of Sr2InV3O11

The electrical conductivity (T) and thermoelectric power S(T) measurements of Sr2InV3O11 showed the insulating state and the change of sign of thermopower from p to n at Tnp = 400 K. The I–V characteristics provided the evidence of symmetrical and non-linear behaviour typical of strong emission of charge carriers induced by temperature and voltage. Relative dielectric permittivity "r as well as loss tangent (tan ) strongly depend both on the temperature in the range of 295–400 K and the frequency in the range of 5 102 to 1 106 Hz, showing the broad maximum at 320 K. These effects are considered as a relaxation process like in the Maxwell–Wagner or Jonscher model as well as the conduction of electric current, as determined by the Joule–Lenz law[…

Action of Molecular Switches in GPCRs - Theoretical and Experimental Studies

G protein coupled receptors (GPCRs), also called 7TM receptors, form a huge superfamily of membrane proteins that, upon activation by extracellular agonists, pass the signal to the cell interior. Ligands can bind either to extracellular N-terminus and loops (e.g. glutamate receptors) or to the binding site within transmembrane helices (Rhodopsin-like family). They are all activated by agonists although a spontaneous auto-activation of an empty receptor can also be observed. Biochemical and crystallographic methods together with molecular dynamics simulations and other theoretical techniques provided models of the receptor activation based on the action of so-called “molecular switches” buried in the receptor structure. They are changed by agonists but also by inverse agonists evoking an ensemble of activation states leading toward different activation pathways. Switches discovered so far include the ionic lock switch, the 3-7 lock switch, the tyrosine toggle switch linked with the nPxxy motif in TM7, and the transmission switch. The latter one was proposed instead of the tryptophan rotamer toggle switch because no change of the rotamer was observed in structures of activated receptors. The global toggle switch suggested earlier consisting of a vertical rigid motion of TM6, seems also to be implausible based on the recent crystal structures of GPCRs with agonists. Theoretical and experimental methods (crystallography, NMR, specific spectroscopic methods like FRET/BRET but also single-molecule-force-spectroscopy) are currently used to study the effect of ligands on the receptor structure, location of stable structural segments/domains of GPCRs, and to answer the still open question on how ligands are binding: either via ensemble of conformational receptor states or rather via induced fit mechanisms. On the other hand the structural investigations of homo- and heterodimers and higher oligomers revealed the mechanism of allosteric signal transmission and receptor activation that could lead to design highly effective and selective allosteric or ago-allosteric drugs

Addressing Joshua Fishman’s Ideological Clarification: Working With Pre-service Teachers

The drastic and tragic loss of Indigenous languages in Canada is of grave concern, as about half of the approximately 50 languages are either endangered or close to extinction (Canada, 2002). Reversing language shift ([RLS) (Fishman, 2001) involves many considerations, including the value and social status of language in homes and communities. This paper explains how a found poetry exercise that 52 pre-service teachers completed has implications for RLS through a movement towards ideological clarification. The poems demonstrate the essence of both Indigenous identity and language, and the classroom-teacher-to-be impressions of that, in rather moving and powerful expressions. These found poems not only speak to the profound loss of languages, but also demonstrate how the activity itself promoted both a personal and a collective understanding of what language obsolescence means to them and their culture. Potentially, they can work as well towards activating goodwill towards Indigenous languages among those who read and reflect on them ---- La perte drastique et tragique des langues autochtones au Canada est profondément préoccupante, car environ la moitié des quelque 50 langues sont en danger ou en voie de disparition. Inverser le changement de langue (Reversing language shift, RLS; Fishman, 2001) demande de considérer plusieurs facteurs, y compris la valeur et le statut social de la langue dans les foyers et dans les communautés. Cet article décrit comment un exercice de « poésie trouvée » complété par 52 enseignants pré-emplois peut avoir des implications pour le RLS au moyen d’un mouvement vers une clarification idéologique. Les poèmes exhibent l’essence même de l’identité et de la langue autochtone pour les futurs enseignants, de façon émouvante et puissante. Ces poèmes trouvés parlent non seulement de la perte profonde de la langue, mais démontrent également comment l’activité elle-même a promu une compréhension à la fois personnelle et collective de ce que l’obsolescence de langue signifie, pour eux et pour leur culture. Potentiellement, ils pourront d’ailleurs travailler pour l’activation de la bonne volonté envers les langues autochtones parmi ceux qui liront et réfléchiront là-dessus

The synthesis and properties of the phases obtained by solid-solid reactions

The presented work encompasses the subject of the studies and the results obtained over the last years by the research workers of the Department of Inorganic Chemistry. They include mainly the studies on the reactivity of metal oxides, searching for new phases in binary and ternary systems of metal oxides as well as describing phase relations establishing in such systems. They also encompass works on the extensive characteristics of physico-chemical properties of the newly obtained compounds

Aquaporin–graphene interface: relevance to point-of-care device for renal cell carcinoma and desalination

© 2018 The Author(s) Published by the Royal Society. All rights reserved. The aquaporin superfamily of hydrophobic integral membrane proteins constitutes water channels essential to the movement of water across the cell membrane, maintaining homeostatic equilibrium. During the passage of water between the extracellular and intracellular sides of the cell, aquaporins act as ultra-sensitive filters. Owing to their hydrophobic nature, aquaporins self-assemble in phospholipids. If a proper choice of lipids is made then the aquaporin biomimetic membrane can be used in the design of an artificial kidney. In combination with graphene, the aquaporin biomimetic membrane finds practical application in desalination and water recycling using mostly Escherichia coli AqpZ. Recently, human aquaporin 1 has emerged as an important biomarker in renal cell carcinoma. At present, the ultra-sensitive sensing of renal cell carcinoma is cumbersome. Hence, we discuss the use of epitopes from monoclonal antibodies as a probe for a point-of-care device for sensing renal cell carcinoma. This device works by immobilizing the antibody on the surface of a single-layer graphene, that is, as a microfluidic device for sensing renal cell carcinoma

British Association for Biological Anthropology and Osteoarchaeology: Equality, Diversity and Inclusion Race Equality Review

Racism continues to be widespread, subtle and often ignored or selectively attended to within organisations. This review sought to evaluate the British Association for Biological Anthropology and Osteoarchaeology (BABAO)’s existing race equality practices, to further support its movement towards becoming an antiracist organisation. The review arose from a commitment by BABAO to interrogate its current structures and redress problematic cultures within the organisation, following a member of colour expressing concerns. In itself, this provides an encouraging example both of the reflexivity of the organisation and the power of a single voice. Through focus groups and surveys, insights were gained with regards to the organisational culture and in response to issues concerning equality, diversity and inclusion (EDI), particularly regarding the need for BABAO to become a more racially literate organisation. The review attempted to glean members’ understanding of anti-racism and how some cultures within the organisation may be racially exclusive or marginalising. In addition to this, the reviewers engaged with stakeholders about where areas could be improved within BABAO in continuing their work towards becoming a racially cognizant organisation. Responses gleaned from the focus groups and survey questionnaire distributed to members revealed that BABAO as an organisation has made some tentative first steps towards race equality, but has some way to go. The paucity of Black, Asian and Minority Ethnic members made gaining perspectives a challenge in relation to experiences of racial discrimination. In itself, this is an indicator that inclusion is an area for growth and reflection. Other key findings included issues with reporting structures and governance processes, with a need for strong and courageous leadership to drive forward conversations around race and racism; a need for training and work to improve racial literacy of the organisation and its members; and a lack of engagement and participation from current members in EDI issues. Nevertheless, the review also indicated that the organisation has made significant strides towards establishing anti-racist practices and are working diligently to engage all members in this endeavour. To this end, the conclusions and recommendations provided aim to enhance current action and further enable BABAO to achieve an anti-racist, inclusive organisational culture.Based on the considerations outlined throughout the report, there were twenty-seven recommendations made. They reflect the need to build a foundation of awareness, understanding and safety upon which to develop a culture of learning, reflection and shared, collective action. High-level recommendations are synthesised below, with further detail in the body of the report

Computer simulations of electrodiffusion problems based on Nernst-Planck and Poisson equations

A numerical procedure based on the method of lines for time-dependent electrodiffusion transport has been developed. Two types of boundary conditions (Neumann and Dirichlet) are considered. Finite difference space discretization with suitably selected weights based on a non-uniform grid is applied. Consistency of this method and the method put forward by Brumleve and Buck are analysed and compared. The resulting stiff system of ordinary differential equations is effectively solved using the RADAU5, RODAS and SEULEX integrators. The applications to selected electrochemical systems: liquid junction, bi-ionic case, ion selective electrodes and electrochemical impedance spectroscopy have been demonstrated. In the paper we promote the use of the full form of the Nernst-Planck and Poisson (NPP) equations, that is including explicitly the electric field as an unknown variable with no simplifications like electroneutrality or constant field assumptions. An effective method of the numerical solution of the NPP problem for arbitrary number of ionic species and valence numbers either for a steady state or a transient state is shown. The presented formulae - numerical solutions to the NPP problem - are ready to be implemented by anyone. Moreover, we make the resulting software freely available to anybody interested in using it. (C) 2012 Elsevier B.V. All rights reserved

Modeling Non Equilibrium Potentiometry to Understand and Control Selectivity and Detection Limit

The majority of present theoretical interpretations of ion-sensor response focus on phase boundary potentials. They assume electroneutrality and equilibrium or steady-state, thus ignoring electrochemical migration and time-dependent effects, respectively. These theoretical approaches, owing to their idealizations, make theorizing on ion distributions and electrical potentials in space and time domains impossible. Moreover, they are in conflict with recent experimental reports on ion-sensors, in which both kinetic (time-dependent) discrimination of ions to improve selectivity, and non-equilibrium transmembrane ion-transport for lowering detection limits, are deliberately used.For the above reasons, the Nernst-Planck-Poisson (NPP) equations are employed here to model the non-equilibrium response in a mathematically congruent manner. In the NPP model, electroneutrality and steady-state/equilibrium assumptions are abandoned. Consequently, directly predicting and visualizing the selectivity and the low detection limit variability over time, as well as the influence of other parameters, i.e. ion diffusibility, membrane thickness and permittivity, and primary to interfering ion concentration ratios on ion-sensor responses, are possible. Additionally, the NPP allows for solving the inverse problem i.e. searching for optimal sensor properties and measurement conditions via target functions and hierarchical modeling. The conditions under which experimentally measured selectivity coefficients are true (unbiased) and detection limits are optimized are demonstrated, and practical conclusions relevant to clinical measurements and bioassays are derived

3D Brain Segmentation Using Dual-Front Active Contours with Optional User Interaction

Important attributes of 3D brain cortex segmentation algorithms include robustness, accuracy, computational efficiency, and facilitation of user interaction, yet few algorithms incorporate all of these traits. Manual segmentation is highly accurate but tedious and laborious. Most automatic techniques, while less demanding on the user, are much less accurate. It would be useful to employ a fast automatic segmentation procedure to do most of the work but still allow an expert user to interactively guide the segmentation to ensure an accurate final result. We propose a novel 3D brain cortex segmentation procedure utilizing dual-front active contours which minimize image-based energies in a manner that yields flexibly global minimizers based on active regions. Region-based information and boundary-based information may be combined flexibly in the evolution potentials for accurate segmentation results. The resulting scheme is not only more robust but much faster and allows the user to guide the final segmentation through simple mouse clicks which add extra seed points. Due to the flexibly global nature of the dual-front evolution model, single mouse clicks yield corrections to the segmentation that extend far beyond their initial locations, thus minimizing the user effort. Results on 15 simulated and 20 real 3D brain images demonstrate the robustness, accuracy, and speed of our scheme compared with other methods