4,339 research outputs found
Large scale reactive additive manufacturing and what to expect when scaling up
Additive manufacturing as a whole offers tremendous savings in time and cost for rapid prototyping and tooling. At present there is a significant number of thermoplastic printers available from small-scale filament-based extrusion to large scale pellet-based extrusion. Thermosets have seen less growth and have been primarily limited to small scale research setups. Recently, a large-scale thermoset printer, the Reactive Additive Manufacturing (RAM) printer was developed (cf. Figure 1). This printer consists of an overall build volume of 450 ft3 and a gantry speed up to 50 in/s. The RAM system is also equipped with a modular pumping station capable of pumping feedstock material at pressures of 3000 psi in 5 or 55 gallon reservoirs. This work intends to reveal the challenges of working with a large scale Direct Ink Writing (DIW) process and how to overcome them. Two material chemistries have been scaled up for this system and are presented herein: a peroxide cured vinyl ester and latent cured epoxy-anhydrides. Factors such as pumpability, printability, and performance vary significantly between these systems and are discussed using rheological characterization, modeling, printing setup and parameters, and part design. Figure
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Strong pressure-energy correlations in van der Waals liquids
Strong correlations between equilibrium fluctuations of the configurational
parts of pressure and energy are found in the Lennard-Jones liquid and other
simple liquids, but not in hydrogen-bonding liquids like methanol and water.
The correlations, that are present also in the crystal and glass phases,
reflect an effective inverse power-law repulsive potential dominating
fluctuations, even at zero and slightly negative pressure. In experimental data
for supercritical Argon, the correlations are found to be approximately 96%.
Consequences for viscous liquid dynamics are discussed.Comment: Phys. Rev. Lett., in pres
Growth-differentiation factor-15 for early risk stratification in patients with acute chest pain
Molecular dynamics simulation of nanocolloidal amorphous silica particles: Part II
Explicit molecular dynamics simulations were applied to a pair of amorphous
silica nanoparticles of diameter 3.2 nm immersed in a background electrolyte.
Mean forces acting between the pair of silica nanoparticles were extracted at
four different background electrolyte concentrations. Dependence of the
inter-particle potential of mean force on the separation and the silicon to
sodium ratio, as well as on the background electrolyte concentration, are
demonstrated. The pH was indirectly accounted for via the ratio of silicon to
sodium used in the simulations. The nature of the interaction of the
counter-ions with charged silica surface sites (deprotonated silanols) was also
investigated. The effect of the sodium double layer on the water ordering was
investigated for three Si:Na+ ratios. The number of water molecules trapped
inside the nanoparticles was investigated as the Si:Na+ ratio was varied.
Differences in this number between the two nanoparticles in the simulations are
attributed to differences in the calculated electric dipole moment. The
implications of the form of the potentials for aggregation are also discussed.Comment: v1. 33 pages, 7 figures (screen-quality PDF), submitted to J. Chem.
Phys v2. 15 pages, 4 tables, 6 figures. Content, author list and title
changed; single space
Resolution of the clinical features of tyrosinemia following orthotopic liver transplantation for hepatoma
The clinical history before transplantation and subsequent clinical and biochemical course of 3 children and one adult with hereditary tyrosinemia treated by orthotopic hepatic transplantation is described. All four patients are now free of their previous dietary restrictions and appear to be cured of both their metabolic disease and their hepatic neoplasm. Ā© 1986 Elsevier Science Publishers B.V. All rights reserved
Combined cognitiveābehavioural and mindfulness programme for people living with dystonia : a proof-of-concept study
Objectives To design and test the delivery of an intervention targeting the non-motor symptoms of dystonia and pilot key health and well-being questionnaires in this population.
Design A proof-of-concept study to test the delivery, acceptability, relevance, structure and content for a 3-day group residential programme for the management of dystonia.
Setting Participants were recruited from a single botulinum toxin clinic. The intervention was delivered in the community.
Participants 14 participants consented to take part (2 withdrew prior to the starting of intervention). The average age was 60ā
years (range 44ā77), 8 of whom were female. After drop-out, 9 participants completed the 3-day programme.
Intervention A 3-day group residential programme.
Primary and secondary outcome measures Process evaluation and interviews were carried out before and after the intervention to explore participant's views and expectations, as well as experiences of the intervention. Select questionnaires were completed at baseline, 1-month and 3-month follow-up.
Results Although participants were not sure what to expect from the programme, they found it informative and for many this together with being in a group with other people with dystonia legitimised their condition. Mindfulness was accepted and adopted as a coping strategy. This was reflected in the 1-month follow-up.
Conclusions We successfully delivered a 3-day residential programme to help those living with dystonia manage their condition. Further improvements are suggested. The quantitative outcome measures were acceptable to this group of patients with dystonia
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