A multiscale model for the rupture of linear polymers in strong flows

Abstract Polymer-containing solutions used across research and industry are commonly exposed to mechanically harsh fluid processes, for example shear and extensional forces during flow through porous media or rapid micro-dispensing of biopharmaceutical molecules. These forces are strong enough to break the covalent bonds in the polymer backbone. As this scission phenomenon can change the functional and fluid-flow properties as well as introduce reactive radicals into the solution, it must be understood and controlled. Experiments and models to-date have only provided partial or qualitative insights into this behaviour. Here we build a link between the molecular-scale degradation models and the macro-scale laminar flow of dilute solutions in any given geometry. A free-draining bead-rod model is used to investigate rupture events at the molecular scale. It is shown by uniaxial extension simulations of an ensemble of chains that scission can be conveniently described at the macroscopic scale as a first order reaction whose rate is a function of the conformation tensor of the macromolecules and the velocity gradient of the flow. This approach is implemented in the finite volume code OpenFOAM by elaborating an appropriate constitutive equation for the conformation tensor. The macroscopic model is run and analysed for ultra-dilute solutions of poly(methyl methacrylate) in ethyl acetate and polyethylene oxide in water, using the geometry of an abrupt contraction flow and neglecting any viscoelastic effect. This multi-scale approach bridges the gap between phenomenological observations of mechanically-induced chemical degradation in large scale applications and the rich field of molecular-scale models of macromolecules under flow.King Abdulaziz City for Science and Technology (KACST

Going with the Flow : Tunable Flow-Induced Polymer Mechanochemistry

Mechanical forces can drive chemical transformations in polymers, directing reactions along otherwise inaccessible pathways, providing exciting possibilities for developing smart, responsive materials. The state-of-the-art test for solution-based polymer mechanochemistry development is ultrasonication. However, this does not accurately model the forces that will be applied during device fabrication using processes such as 3D printing or spray coating. Here, a step is taken toward predictably translating mechanochemistry from molecular design to manufacturing by demonstrating a highly controlled nozzle flow setup in which the shear forces being delivered are precisely tuned. The results show that solvent viscosity, fluid strain rate, and the nature of the breaking bond can be individually studied. Importantly, it is shown that the influence of each is different to that suggested by ultrasonication (altered quantity of chain breakage and critical polymer chain length). Significant development is presented in the understanding of polymer bond breakage during manufacturing flows to help guide design of active components that trigger on demand. Using an anthracene-based mechanophore, the triggering of a fluorescence turn-on is demonstrated through careful selection of the flow parameters. This work opens the avenue for programmed chemical transformations during inline manufacturing processes leading to tunable, heterogeneous final products from a single source material. © 2020 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinhei

How blogs support the transfer of knowledge into practice in the field of dementia palliative care: a survey of facilitators and barriers

BACKGROUND: Blogging can help to maximise the impact of one’s work in academia and beyond by making research findings accessible for multiple knowledge users, such as healthcare professionals and the public, as well as other researchers. As part of the knowledge exchange and dissemination activities of the Model for Dementia Palliative Care Project, this study explored stakeholders’ views of blogs as a means to translate research findings. METHODS: A web-based survey was developed, piloted, and revised. It was distributed electronically via key dementia and palliative care organisations websites, newsletters, social media platforms, and within the staff mailing lists of five Universities in Ireland. Data were analysed using descriptive statistics and content analysis. RESULTS: Complete responses were received from 128 participants. The majority of respondents were healthcare researchers (n = 53), followed by healthcare providers (n = 46). The preferred methods of reviewing research findings were scientific papers, websites and news articles. Respondents read healthcare blogs “sometimes” (39.1%), with < 19% reading them “often” or “very often”. Receiving an email notification might increase the likelihood of reading a new blog post for 83% of respondents. Barriers to engaging with blogs included lack of time, preference for other media, lack of awareness regarding available blogs, and concerns about the credibility and source of information. An appropriate length and the author of the blog were key features that encouraged engagement with a blog. CONCLUSIONS: Despite respondents choosing a scientific paper as their preferred method to consume research findings, many indicated an openness to reading blogs on their area of interest. Creating concise, relevant, and credible blogs, and suitably promoting them, could increase the impact and reach of healthcare research, such as in the emerging field of dementia palliative care, and thus promote translation of research findings into practice. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12904-022-01001-7

A scoping review of the evidence for community-based dementia palliative care services and their related service activities

BACKGROUND: Palliative care is identified internationally as a priority for efficacious dementia care. Research into “effective models” of palliative care for people with dementia has been recommended by several European countries. To build an effective service-delivery model we must gain an understanding of existing models used in similar settings. The study aim is to identify core components of extant models of palliative care for people with dementia, and their families, who are living at home in the community. METHODS: A scoping review was employed. The search strategy was devised to identify all peer-reviewed research papers relating to the above aim. This process was iterative, and the search strategy was refined as evidence emerged and was reviewed. All types of study designs and both quantitative and qualitative studies of non-pharmacological interventions were considered for inclusion. RESULTS: The search identified 2,754 unique citations, of which 18 papers were deemed eligible for inclusion. Although a palliative care approach is recommended from early in the disease process, most evidence involves end-of-life care or advanced dementia and pertains to residential care. The majority of the research reviewed focused on the effects of advance care planning, and end-of-life care; specialist palliative care input, and/or generalist palliative care provided by dementia services to enable people to remain at home and to reduce costs of care. Community staff training in palliative care appeared to improve engagement with Specialist Palliative Care teams. Integration of dementia and palliative care services was found to improve care received for people with dementia and their carers. CONCLUSIONS: While the evidence for integration of dementia and palliative care services is promising, further high-quality research is necessary particularly to identify the key components of palliative care for people living with dementia. This is imperative to enable people with dementia to inform their own care, to stay living at home for as long as possible, and, where appropriate, to die at home. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12904-022-00922-7

Synergistic photoluminescence enhancement in conjugated polymer-di-ureasil organic-inorganic composites.

Poly(fluorene) conjugated polyelectrolyte (CPE)-di-ureasil organic-inorganic composites have been prepared using a versatile sol-gel processing method, which enables selective localisation of the CPE within the di-ureasil matrix. Introduction of the CPE during the sol-gel reaction leads to a homogeneous distribution of the CPE throughout the di-ureasil, whereas a post-synthesis solvent permeation route leads to the formation of a confined layer of the CPE at the di-ureasil surface. The CPE and the di-ureasil both function as photoactive components, contributing directly to, and enhancing the optical properties of their composite material. The bright blue photoluminescence exhibited by CPE-di-ureasils is reminiscent of the parent CPE; however the distinct contribution of the di-ureasil to the steady-state emission profile is also apparent. This is accompanied by a dramatic increase in the photoluminescence quantum yield to >50%, which is a direct consequence of the synergy between the two components. Picosecond time-correlated single photon counting measurements reveal that the di-ureasil effectively isolates the CPE chains, leading to emissive trap sites which have a high radiative probability. Moreover, intimate mixing of the CPE and the di-ureasil, coupled with their strong spectral overlap, results in efficient excitation energy transfer from the di-ureasil to these emissive traps. Given the simple, solution-based fabrication method and the structural tunability of the two components, this approach presents an efficient route to highly desirable CPE-hybrid materials whose optoelectronic properties may be enhanced and tailored for a targeted application

A single-component photorheological fluid with light-responsive viscosity.

Viscoelastic fluids whose rheological properties are tunable with light have the potential to deliver significant impact in fields relying on a change in flow behavior, such as in-use tuning of combined efficient heat-transfer and drag-reduction agents, microfluidic flow and controlled encapsulation and release. However, simple, single-component systems must be developed to allow integration with these applications. Here, we report a single-component viscoelastic fluid, capable of a dramatic light-sensitive rheological response, from a neutral azobenzene photosurfactant, 4-hexyl-4'butyloxymonotetraethylene glycol (C6AzoOC4E4) in water. From cryo-transmission electron microscopy (TEM), small-angle X-ray scattering (SAXS) and rheology measurements, we observe that the photosurfactant forms an entangled network of wormlike micelles in water, with a high viscosity (28 Pa s) and viscoelastic behaviour. UV irradiation of the surfactant solution creates a less dense micellar network, with some vesicle formation. As a result, the solution viscosity is reduced by four orders of magnitude (to 1.2 × 10-3 Pa s). This process is reversible and the high and low viscosity states can be cycled several times, through alternating UV and blue light irradiation

Synchronous presentation of acute acalculous cholecystitis and appendicitis: a case report

<p>Abstract</p> <p>Introduction</p> <p>Acute acalculous cholecystitis is traditionally associated with elderly or critically ill patients.</p> <p>Case presentation</p> <p>We present the case of an otherwise healthy 23-year-old Caucasian man who presented with acute right-sided abdominal pain. An ultrasound examination revealed evidence of acute acalculous cholecystitis. A laparoscopy was undertaken and the dual pathologies of acute acalculous cholecystitis and acute appendicitis were discovered and a laparoscopic cholecystectomy and appendectomy were performed.</p> <p>Conclusion</p> <p>Acute acalculous cholecystitis is a rare clinical entity in young, healthy patients and this report describes the unusual association of acute acalculous cholecystitis and appendicitis. A single stage combined laparoscopic appendectomy and cholecystectomy is an effective treatment modality.</p