Cofinement, entropy, and single-particle dynamics of equilibrium hard-sphere mixtures

We use discontinuous molecular dynamics and grand-canonical transition-matrix Monte Carlo simulations to explore how confinement between parallel hard walls modifies the relationships between packing fraction, self-diffusivity, partial molar excess entropy, and total excess entropy for binary hard-sphere mixtures. To accomplish this, we introduce an efficient algorithm to calculate partial molar excess entropies from the transition-matrix Monte Carlo simulation data. We find that the species-dependent self-diffusivities of confined fluids are very similar to those of the bulk mixture if compared at the same, appropriately defined, packing fraction up to intermediate values, but then deviate negatively from the bulk behavior at higher packing fractions. On the other hand, the relationships between self-diffusivity and partial molar excess entropy (or total excess entropy) observed in the bulk fluid are preserved under confinement even at relatively high packing fractions and for different mixture compositions. This suggests that the partial molar excess entropy, calculable from classical density functional theories of inhomogeneous fluids, can be used to predict some of the nontrivial dynamical behaviors of fluid mixtures in confined environments.Comment: submitted to JC

Novel Characteristics of Valveless Pumping

This study investigates the occurrence of valveless pumping in a fluidfilled system consisting of two open tanks connected by an elastic tube. We show that directional flow can be achieved by introducing a periodic pinching applied at an asymmetrical location along the tube, and that the flow direction depends on the pumping frequency. We propose a relation between wave propagation velocity, tube length, and resonance frequencies associated with shifts in the pumping direction using numerical simulations. The eigenfrequencies of the system are estimated from the linearized system, and we show that these eigenfrequencies constitute the resonance frequencies and the horizontal slope frequencies of the system; 'horizontal slope frequency' being a new concept. A simple model is suggested, explaining the effect of the gravity driven part of the oscillation observed in response to the tank and tube diameter changes. Results are partly compared with experimental findings.Art. no. 22450

Broadcasting graphic war violence: the moral face of Channel 4

Drawing on empirical data from Channel 4 (C4) regarding the broadcasting of violent war imagery, and positioned within Goffman’s notion of the interaction ritual (1959, 1967), this article investigates how C4 negotiate potentially competing commercial, regulatory and moral requirements through processes of discretionary decision-making. Throughout, the article considers the extent to which these negotiations are presented through a series of ‘imaginings’ – of C4 and its audience – which serve to simultaneously guide and legitimate the decisions made. This manifestation of imaginings moves us beyond more blanket explanations of ‘branding’ and instead allows us to see the final programmes as the end product of a series of complex negotiations and interactions between C4 and those multiple external parties significant to the workings of their organization. The insights gleaned from this case study are important beyond the workings of C4 because they help elucidate how all institutions and organizations may view, organize and justify their practices (to both themselves and others) within the perceived constraints in which they operate

Socially sensitive lactation: Exploring the social context of breastfeeding

Many women report difficulties with breastfeeding and do not maintain the practice for as long as intended. Although psychologists and other researchers have explored some of the difficulties they experience, fuller exploration of the relational contexts in which breastfeeding takes place is warranted to enable more in-depth analysis of the challenges these pose for breastfeeding women. The present paper is based on qualitative data collected from 22 first-time breastfeeding mothers through two phases of interviews and audio-diaries which explored how the participants experienced their relationships with significant others and the wider social context of breastfeeding in the first five weeks postpartum. Using a thematic analysis informed by symbolic interactionism, we develop the overarching theme of ‘Practising socially sensitive lactation’ which captures how participants felt the need to manage tensions between breastfeeding and their perceptions of the needs, expectations and comfort of others. We argue that breastfeeding remains a problematic social act, despite its agreed importance for child health. Whilst acknowledging the limitations of our sample and analytic approach, we suggest ways in which perinatal and public health interventions can take more effective account of the social challenges of breastfeeding in order to facilitate the health and psychological well-being of mothers and their infants

Factors Governing Pasting Properties of Waxy Wheat Flours

Citation: Purna, S. K. G., Shi, Y. C., Guan, L., Wilson, J. D., & Graybosch, R. A. (2015). Factors Governing Pasting Properties of Waxy Wheat Flours. Cereal Chemistry, 92(5), 529-535. doi:10.1094/cchem-10-14-0209-rWaxy wheat (Triticum aestivum L.) contains endosperm starch lacking in amylose. To realize the full potential of waxy wheat, the pasting properties of hard waxy wheat flours as well as factors governing the pasting properties were investigated and compared with normal and partial waxy wheat flours. Starches isolated from six hard waxy wheat flours had similar pasting properties, yet their corresponding flours had very different pasting properties. The differences in pasting properties were narrowed after endogenous alpha-amylase activity in waxy wheat flours was inhibited by silver nitrate. Upon treatment with protease, the extent of protein digestibility influenced the viscosity profile in waxy wheat flours. Waxy wheat starch granules swelled extensively when heated in water and exhibited a high peak viscosity, but they fragmented at high temperatures, resulting in more rapid breakdown in viscosity. The extensively swelled and fragmented waxy wheat starch granules were more susceptible to a-amylase degradation than normal wheat starch. A combination of endogenous a-amylase activity and protein matrix contributed to a large variation in pasting properties of waxy wheat flours

Pleiotropic functions of the tumor- and metastasis-suppressing Matrix Metalloproteinase-8 in mammary cancer in MMTV-PyMT transgenic mice

Matrix metalloproteinase-8 (MMP-8; neutrophil collagenase) is an important regulator of innate immunity which has onco-suppressive actions in numerous tumor types

Surrender, catch and the imp of fieldwork

We build on the work of Kurt Wolff to capture some distinctive aspects of ethnographic fieldwork. Drawing on the sociology of knowledge and phenomenology, Wolff introduced and developed the idea of surrender-and- catch in order to encapsulate the twin processes of engagement and reflection. We extend the idea to incorporate what we call the 'imps’ of ethnographic fieldwork. For neither surrender nor catch are themselves predictable or perfectly under the ethnographer’s control. While fieldwork is itself unpredictable, there may be many unanticipated ‘catches’. Moreover, there is often an ethnographic ‘imp’ that intrudes itself, questioning the very desirability or good sense of the fieldwork itself. The imps arise unbidden but can pose searching, sometimes unwelcome – though ultimately productive – questions. We illustrate the paper from a brief fieldwork encounter with the world of studio photography

Diffuse charge and Faradaic reactions in porous electrodes

Porous electrodes instead of flat electrodes are widely used in electrochemical systems to boost storage capacities for ions and electrons, to improve the transport of mass and charge, and to enhance reaction rates. Existing porous electrode theories make a number of simplifying assumptions: (i) The charge-transfer rate is assumed to depend only on the local electrostatic potential difference between the electrode matrix and the pore solution, without considering the structure of the double layer (DL) formed in between; (ii) the charge-transfer rate is generally equated with the salt-transfer rate not only at the nanoscale of the matrix-pore interface, but also at the macroscopic scale of transport through the electrode pores. In this paper, we extend porous electrode theory by including the generalized Frumkin-Butler-Volmer model of Faradaic reaction kinetics, which postulates charge transfer across the molecular Stern layer located in between the electron-conducting matrix phase and the plane of closest approach for the ions in the diffuse part of the DL. This is an elegant and purely local description of the charge-transfer rate, which self-consistently determines the surface charge and does not require consideration of reference electrodes or comparison with a global equilibrium. For the description of the DLs, we consider the two natural limits: (i) the classical Gouy-Chapman-Stern model for thin DLs compared to the macroscopic pore dimensions, e.g., for high-porosity metallic foams (macropores >50 nm) and (ii) a modified Donnan model for strongly overlapping DLs, e.g., for porous activated carbon particles (micropores <2 nm). Our theory is valid for electrolytes where both ions are mobile, and it accounts for voltage and concentration differences not only on the macroscopic scale of the full electrode, but also on the local scale of the DL. The model is simple enough to allow us to derive analytical approximations for the steady-state and early transients. We also present numerical solutions to validate the analysis and to illustrate the evolution of ion densities, pore potential, surface charge, and reaction rates in response to an applied voltage

Everyday life and locative play: an exploration of Foursquare and playful engagements with space and place

Foursquare is a location-based social network (LBSN) that combines gaming elements with features conventionally associated with social networking sites (SNSs). Following two qualitative studies, this article sets out to explore what impact this overlaying of physical environments with play has on everyday life and experiences of space and place. Drawing on early understandings of play, alongside the flâneur and ‘phoneur’ as respective methods for conceptualizing play in the context of mobility and urbanity, this article examines whether the suggested division between play and ordinary life is challenged by Foursquare, and if so, how this reframing of play is experienced. Second, this article investigates what effect this LBSN has on mobility choices and spatial relationships. Finally, the novel concept of the ‘phoneur’ is posited as a way of understanding how pervasive play through LBSNs acts as a mediating influence on the experience of space and place