A model colloidal fluid with competing interactions: bulk and interfacial properties

Using a simple mean-field density functional theory theory (DFT), we investigate the structure and phase behaviour of a model colloidal fluid composed of particles interacting via a pair potential which has a hard core of diameter $\sigma$, is attractive Yukawa at intermediate separations and repulsive Yukawa at large separations. We analyse the form of the asymptotic decay of the bulk fluid correlation functions, comparing results from our DFT with those from the self consistent Ornstein-Zernike approximation (SCOZA). In both theories we find rich crossover behaviour, whereby the ultimate decay of correlation functions changes from monotonic to long-wavelength damped oscillatory decay on crossing certain lines in the phase diagram, or sometimes from oscillatory to oscillatory with a longer wavelength. For some choices of potential parameters we find, within the DFT, a $\lambda$-line at which the fluid becomes unstable with respect to periodic density fluctuations. SCOZA fails to yield solutions for state points near such a $\lambda$-line. The propensity to clustering of particles, which is reflected by the presence of a long wavelength $\gg \sigma$, slowly decaying oscillatory pair correlation function, and a structure factor that exhibits a very sharp maximum at small but non zero wavenumbers, is enhanced in states near the $\lambda$-line. We present density profiles for the planar liquid-gas interface and for fluids adsorbed at a planar hard wall. The presence of a nearby $\lambda$-transition gives rise to pronounced long-wavelength oscillations in the one-body densities at both types of interface.Comment: 14 pages, 11 figure

X-Ray Diffraction and Reflectance Spectroscopy of Murchison Powders (CM2) After Thermal Analysis Under Reducing Conditions to Final Temperatures Between 300 and 1300c

The asteroids Ryugu and Bennu have spectral characteristics in common with CI/CM type carbonaceous chondrites and are target bodies for JAXAs Hayabusa2 and NASAs OSIRIS-Rex missions, respectively. Analog studies, based primarily on the Murchison CM2 chondrite, provide a pathway to separate spectral properties resulting space weathering from those inherent to parent-body, mineralogy, chemistry, and processes. Ryugu shares spectral properties with thermally metamorphosed and partly dehydrated CI/CM chondrites. We have undertaken a multidisciplinary study of the thermal decomposition of Murchison powder samples as an analog to metamorphic process that may have occurred on Ryugu. Bulk analyses include thermal And evolved gas analysis, X-ray diffraction (XRD), and VIS-NIR and Mssbauer spectroscopy; micro- to nanoscale analyses included scanning and transmission electron microscopy and electron probe micro analysisWe report here XRD and VIS-NIR analyses of pre- and post-heated Murchison powders, and in a companion paper report results from multiple electron beam techniques

Patient safety and quality of care in mental health: a world of its own?

Quality and safety in healthcare, as an academic discipline, has made significant progress over recent decades, and there is now an active and established community of researchers and practitioners. However, work has predominantly focused on physical health, despite broader controversy regarding the attention paid to, and significance attributed to, mental health. Work from both communities is required in order to ensure that quality and safety is actively embedded within mental health research and practice and that the academic discipline of quality and safety accurately represents the scientific knowledge that has been accumulated within the mental health community

The Diversity Imperative Revisited: Racial and Gender Inclusion in Clinical Law Faculty

The demographics of clinical law faculties matter. As Professor Jon Dubin persuasively argued nearly twenty years ago in his article Faculty Diversity as a Clinical Legal Education Imperative, clinical faculty of color entering the legal academy in the 1980s and 1990s expanded the communities served by law school clinics and the lawyering methods used to serve clients in significant ways that enriched legal education and the profession. They also broadened clinical scholarship to include deconstructions and reconstructions of clinical teaching, offered crucial role modeling and mentorship to students of color, and helped to elevate cross-cultural communication and multiracial collaboration as core lawyering skills. Professor Dubin catalogued these contributions while pointing to data that showed that clinical faculties remained overwhelmingly White, and he urged law schools to recognize the urgency of diversifying clinical faculty. While there has been some research and scholarship devoted to the gender composition of clinical faculties, to our knowledge, there has been no substantive reexamination of the importance of racial composition since Professor Dubin’s article in 2000, nor any examination of clinical faculty diversity beyond race, ethnicity, and binary gender. The Clinical Legal Education Association created the Committee for Faculty Equity and Inclusion to draw attention to the crisis of diversity among clinical faculties, and to urge law schools to take proactive steps to remedy this longstanding failure. This Essay from the Committee assesses what progress has been made since Professor Dubin’s intervention and interrogates historical trends in the racial and gender composition of clinical faculty from 1980 to 2017, using existing data. We found that there has been limited progress on racial and ethnic inclusion in clinical law faculties. While the total percentage of people of color has grown from 10% to 21%, the inclusion of Black, Latinx, and Indigenous faculty has been largely stagnant. Black clinical faculty members reached 7% of all clinical faculty in 1999 and have never exceeded that percentage. Latinx clinical faculty representation, at 5%, is the same as it was in 1981. Indigenous faculty have never constituted even 1%. Overall, White faculty continue to hold nearly 8 out of 10 clinical faculty positions. With regard to gender, whereas women were underrepresented among clinical faculty in the 1980s, women now outnumber men in clinical faculty positions by nearly 2 to 1. Given that women remain underrepresented in law faculties as a whole, this seemingly positive development in the gender composition of clinical instructors nonetheless raises concerns about internal status inequities and the clustering of women faculty members in non-tenured positions with lower salaries and less job protection, including on clinical, legal research and writing and library faculties. Therefore, this trend may be a cautionary tale for the inclusion of other underrepresented groups moving forward. Acknowledging the limitations of existing data, we offer recommendations for future data collection that would recognize more inclusive identities and backgrounds. We suggest that future research assess job satisfaction and sustainability of faculty positions for people from historically disadvantaged groups to ensure that we are not just providing access to clinical law faculties, but also offering equitable and supportive working environments. New research will be crucial to developing a more meaningful understanding of inequities among clinical faculty, and to assessing equity and inclusion beyond descriptive representation. We conclude with a discussion of best practices for inclusive clinical faculty hiring and suggestions for future initiatives that may make the profession more accessible. Looking back on Professor Dubin’s arguments, we are disheartened by the lack of subsequent scholarship on clinical faculty diversity, particularly with regard to racial and ethnic representation. We are concerned that it reflects a degree of complacency with structural racism at our own institutions and a failure to recognize the dissonance between the values we promote in our lawyering and our participation in maintaining barriers to the profession. We hope this Essay will disrupt that complacency and revive Professor Dubin’s arguments for a diversity imperative, which are even more resonant in the current moment

Gauged and historical abrupt wave front floods (\u27walls of water\u27) in Pennine rivers, northern England

\ua9 2024 The Authors. Journal of Flood Risk Management published by Chartered Institution of Water and Environmental Management and John Wiley & Sons Ltd. Extremely rapid rates of rise in level and discharge in a subset of flash floods (‘abrupt wave front floods’, AWF) are separate hazards from peak level. Such flood events are investigated for Pennine catchments in northern England using both gauged and historical information. Gauged level and flow digital records at 15-min intervals provide recent data. Historical information for 122 AWF events is extracted from a chronology of flash floods for Britain. Historical AWF events are mapped and found to occur on every major Pennine catchment; catchment descriptors are derived as a basis for assessing catchment vulnerability. We discuss the disputed origin of AWF. Using gauged data, we contrast the rising limb of AWF and ‘normal’ floods. We investigate time series of historical AWF, noting a puzzling peak in the late 19th century. Current rainfall and river monitoring does not provide a reliable basis for understanding AWF processes or for operational response and we suggest improvements. Similarly, current models for design flood estimation and forecasting do not generate the observed rapid increase in level in AWF floods

Intrinsic point defects and volume swelling in ZrSiO4 under irradiation

The effects of high concentration of point defects in crystalline ZrSiO4 as originated by exposure to radiation, have been simulated using first principles density functional calculations. Structural relaxation and vibrational studies were performed for a catalogue of intrinsic point defects, with different charge states and concentrations. The experimental evidence of a large anisotropic volume swelling in natural and artificially irradiated samples is used to select the subset of defects that give similar lattice swelling for the concentrations studied, namely interstitials of O and Si, and the anti-site Zr(Si), Calculated vibrational spectra for the interstitials show additional evidence for the presence of high concentrations of some of these defects in irradiated zircon.Comment: 9 pages, 7 (color) figure

Generation of defects and disorder from deeply quenching a liquid to form a solid

We show how deeply quenching a liquid to temperatures where it is linearly unstable and the crystal is the equilibrium phase often produces crystalline structures with defects and disorder. As the solid phase advances into the liquid phase, the modulations in the density distribution created behind the advancing solidification front do not necessarily have a wavelength that is the same as the equilibrium crystal lattice spacing. This is because in a deep enough quench the front propagation is governed by linear processes, but the crystal lattice spacing is determined by nonlinear terms. The wavelength mismatch can result in significant disorder behind the front that may or may not persist in the latter stage dynamics. We support these observations by presenting results from dynamical density functional theory calculations for simple one- and two-component two-dimensional systems of soft core particles.Comment: 25 pages, 11 figure

Exchange interactions and magnetic phases of transition metal oxides: benchmarking advanced ab initio methods

The magnetic properties of the transition metal monoxides MnO and NiO are investigated at equilibrium and under pressure via several advanced first-principles methods coupled with Heisenberg Hamiltonian MonteCarlo. The comparative first-principles analysis involves two promising beyond-local density functionals approaches, namely the hybrid density functional theory and the recently developed variational pseudo-self-interaction correction method, implemented with both plane-wave and atomic-orbital basis sets. The advanced functionals deliver a very satisfying rendition, curing the main drawbacks of the local functionals and improving over many other previous theoretical predictions. Furthermore, and most importantly, they convincingly demonstrate a degree of internal consistency, despite differences emerging due to methodological details (e.g. plane waves vs. atomic orbitals

Thermodynamically consistent description of the hydrodynamics of free surfaces covered by insoluble surfactants of high concentration

In this paper we propose several models that describe the dynamics of liquid films which are covered by a high concentration layer of insoluble surfactant. First, we briefly review the 'classical' hydrodynamic form of the coupled evolution equations for the film height and surfactant concentration that are well established for small concentrations. Then we re-formulate the basic model as a gradient dynamics based on an underlying free energy functional that accounts for wettability and capillarity. Based on this re-formulation in the framework of nonequilibrium thermodynamics, we propose extensions of the basic hydrodynamic model that account for (i) nonlinear equations of state, (ii) surfactant-dependent wettability, (iii) surfactant phase transitions, and (iv) substrate-mediated condensation. In passing, we discuss important differences to most of the models found in the literature.Comment: 31 pages, 2 figure