Modelling the evaporation of nanoparticle suspensions from heterogeneous surfaces

We present a Monte Carlo (MC) grid-based model for the drying of drops of a nanoparticle suspension upon a heterogeneous surface. The model consists of a generalised lattice-gas in which the interaction parameters in the Hamiltonian can be varied to model different properties of the materials involved. We show how to choose correctly the interactions, to minimise the effects of the underlying grid so that hemispherical droplets form. We also include the effects of surface roughness to examine the effects of contact-line pinning on the dynamics. When there is a `lid' above the system, which prevents evaporation, equilibrium drops form on the surface, which we use to determine the contact angle and how it varies as the parameters of the model are changed. This enables us to relate the interaction parameters to the materials used in applications. The model has also been applied to drying on heterogeneous surfaces, in particular to the case where the suspension is deposited on a surface consisting of a pair of hydrophilic conducting metal surfaces that are either side of a band of hydrophobic insulating polymer. This situation occurs when using inkjet printing to manufacture electrical connections between the metallic parts of the surface. The process is not always without problems, since the liquid can dewet from the hydrophobic part of the surface, breaking the bridge before the drying process is complete. The MC model reproduces the observed dewetting, allowing the parameters to be varied so that the conditions for the best connection can be established. We show that if the hydrophobic portion of the surface is located at a step below the height of the neighbouring metal, the chance of dewetting of the liquid during the drying process is significantly reduced.Comment: 14 pages, 14 figure

Simplifying Algebra in Feynman Graphs, Part III: Massive Vectors

A T-dualized selfdual inspired formulation of massive vector fields coupled to arbitrary matter is generated; subsequently its perturbative series modeling a spontaneously broken gauge theory is analyzed. The new Feynman rules and external line factors are chirally minimized in the sense that only one type of spin index occurs in the rules. Several processes are examined in detail and the cross-sections formulated in this approach. A double line formulation of the Lorentz algebra for Feynman diagrams is produced in this formalism, similar to color ordering, which follows from a spin ordering of the Feynman rules. The new double line formalism leads to further minimization of gauge invariant scattering in perturbation theory. The dualized electroweak model is also generated.Comment: 39 pages, LaTeX, 8 figure

Singularity Hypotheses: An Overview

Bill Joy in a widely read but controversial article claimed that the most powerful 21st century technologies are threatening to make humans an endangered species. Indeed, a growing number of scientists, philosophers and forecasters insist that the accelerating progress in disruptive technologies such as artificial intelligence, robotics, genetic engineering, and nanotechnology may lead to what they refer to as the technological singularity: an event or phase that will radically change human civilization, and perhaps even human nature itself, before the middle of the 21st century

Exploring the challenge of health research priority setting in partnership: reflections on the methodology used by the James Lind Alliance Pressure Ulcer Priority Setting Partnership

Background: Studies identifying a mismatch between the priorities of academics and clinicians and those of people with direct experience of a health condition pose a challenge to the assumption that professional researchers can represent the interests of patients and the public in setting priorities for health research. The James Lind Alliance (JLA) brings patients, carers and clinicians together in Priority Setting Partnerships (PSPs) to identify and prioritise shared uncertainties about the effects of treatment. There is no formal evaluation yet to examine the different approaches used by individual PSPs and the impact these methods have on the quality of the partnership and subsequent outputs. There is no gold standard method for health research topic identification and priority setting and reporting on public involvement in this area is predominantly descriptive rather than evaluative. Methods and Findings: The JLA Pressure Ulcer PSP (JLAPUP) was developed and worked between 2009 and 2013 to identify and prioritise the top 10 ‘uncertainties’, or ‘unanswered questions’, about the effects of pressure ulcer interventions. JLAPUP identified a mismatch between the nature and quality of RCTs in pressure ulcer prevention and treatment and the kind of research evidence desired by patients or service users, carers and health professionals. Results and methods have been reported fully elsewhere. The consultative and deliberative methods used to establish health research priorities in PSPs are fundamentally interpretive. PSPs are therefore an arena in which ‘hard’ evidence-informed ideals meet ‘soft’ participatory practices. This article provides an account of the challenges faced in one particular PSP. We explain the rationale for the approaches taken, difficulties faced and the limitations at each stage, because these aspects are particularly under-reported. The JLAPUP case is used to identify possible areas for evaluation and reporting across PSPs. Conclusion: Engaging people with very different health and life experiences in the complexities of health science based discussions of uncertainty is challenging. This is particularly the case when engaging groups routinely excluded from participating in health research, for example, older people with multiple comorbidities. The JLA principles of transparency, inclusivity and avoiding waste in research require paying close critical attention to PSP methodology, including full evaluation and reporting of PSP processes and outcomes. Assessing the impact of PSPs is contingent on the decision making processes of commissioners and funders

Tailoring the surface charge of dextran-based polymer coated SPIONs for modulated stem cell uptake and MRI contrast

Tracking stem cells in vivo using non-invasive techniques is critical to evaluate the efficacy and safety of stem cell therapies. Superparamagnetic iron oxide nanoparticles (SPIONs) enable cells to be tracked using magnetic resonance imaging (MRI), but to obtain detectable signal cells need to be labelled with a sufficient amount of iron oxide. For the majority of SPIONs, this can only be obtained with the use of transfection agents, which can adversely affect cell health. Here, we have synthesised a library of dextran-based polymer coated SPIONs with varying surface charge from −1.5 mV to +18.2 mV via a co-precipitation approach and investigated their ability to be directly internalised by stem cells without the need for transfection agents. The SPIONs were colloidally stable in physiological solutions. The crystalline phase of the particles was confirmed with powder X-ray diffraction and their magnetic properties were characterised using SQUID magnetometry and magnetic resonance. Increased surface charge led to six-fold increase in uptake of particles into stem cells and higher MRI contrast, with negligible change in cell viability. Cell tracking velocimetry was shown to be a more accurate method for predicting MRI contrast of stem cells compared to measuring iron oxide uptake through conventional bulk iron quantification

SYSTEMS-2: a randomised phase II study of radiotherapy dose escalation for pain control in malignant pleural mesothelioma

SYSTEMS-2 is a randomised study of radiotherapy dose escalation for pain control in 112 patients with malignant pleural mesothelioma (MPM). Standard palliative (20Gy/5#) or dose escalated treatment (36Gy/6#) will be delivered using advanced radiotherapy techniques and pain responses will be compared at week 5. Data will guide optimal palliative radiotherapy in MPM