Large-Scale Robot-Based Polymer and Composite Additive Manufacturing: Failure Modes and Thermal Simulation.

Additive manufacturing (AM) of large-scale polymer and composite parts using robotic arms integrated with extruders has received significant attention in recent years. Despite the contributions of great technical progress and material development towards optimizing this manufacturing method, different failure modes observed in the final printed products have hindered its application in producing large engineering structures used in aerospace and automotive industries. We report failure modes in a variety of printed polymer and composite parts, including fuel tanks and car bumpers.

Identification and Characterization of the miRNAs and Cytokines in Response to Leishmania infantum Infection with Different Response to Treatment.

Purpose: Due to the complexity of cytokine and microRNA function in progression and/or suppression of an infection, in this study, we examined miR-3473f, miR-2128, miR-6994-5p, miR-7093-3p, miR-5128, miR-574-5p, miR-7235, IL-2, IL-4, IL-5, IL-10 and IL-13 in patients with VL caused by Leishmania infantum in an in vivo study.

Methods: Sampling was carried out from patient with leishmaniasis and with different responses to treatment during March 2016-January 2020. DNA was extracted and purified using QIAamp Kit.

Does the addition of a heteropoly acid change the water percolation threshold of PFSA membranes?

A large system containing heteropoly acids (HPAs) and Nafion® 117 was simulated and studied to verify whether the additive particles affect the formation of the water percolating network or not. Two structures of HPA particles were considered as dopants, i.e.

An Experimental Study on Hydrodynamic Retention of Low and High Molecular Weight Sulfonated Polyacrylamide Polymer.

Polymers are often added with water as a viscosifier to improve oil recovery from hydrocarbon reservoirs. Polymer might be lost wholly or partially from the injected polymer solution by adsorption on the grain surfaces, mechanical entrapment in pores, and hydrodynamic retention in stagnant zones. Therefore, having a clear picture of polymer losses (and retention) is very important for designing a technically and economically successful polymer flood project.

A New Empirical Model for Viscosity of Sulfonated Polyacrylamide Polymers.

Copolymers of acrylamide with the sodium salt of 2-acrylamido-2-methylpropane sulfonic acid-known as sulfonated polyacrylamide polymers-had been shown to produce very promising results in the enhancement of oil recovery, particularly in polymer flooding. The aim of this work is to develop an empirical model through the use of a design of experiments (DOE) approach for bulk viscosity of these copolymers as a function of polymer characteristics (i.e.

Elucidating the morphological aspects and proton dynamics in a hybrid perfluorosulfonic acid membrane for medium-temperature fuel cell applications.

A perfluorosulfonic acid (PFSA) membrane, i.e. Nafion® 117, was doped with the heteropoly salts (HPS) Cs3PW12O40, Rb3PW12O40, and (NH4)3PW12O40.

Assessment of Polyacrylamide Based Co-Polymers Enhanced by Functional Group Modifications with Regards to Salinity and Hardness.

This research aims to test four new polymers for their stability under high salinity/high hardness conditions for their possible use in polymer flooding to improve oil recovery from hydrocarbon reservoirs. The four sulfonated based polyacrylamide co-polymers were FLOCOMB C7035; SUPERPUSHER SAV55; THERMOASSOCIATIF; and AN132 VHM which are basically sulfonated polyacrylamide copolymers of AM (acrylamide) with AMPS (2-Acrylamido-2-Methylpropane Sulfonate). AN132 VHM has a molecular weight of 9⁻11 million Daltons with 32 mol % degree of sulfonation.

Effect of Aging, Antioxidant, and Mono- and Divalent Ions at High Temperature on the Rheology of New Polyacrylamide-Based Co-Polymers.

The viscosity of four new polymers was investigated for the effect of aging at high temperature, with varying degrees of salinity and hardness. The four sulfonated based polyacrylamide co-polymers were FLOCOMB C7035; AN132 VHM; SUPERPUSHER SAV55; and THERMOASSOCIATIF copolymers. All polymer samples were aged at 80 °C for varying times (from zero to at least 90 days) with and without isobutyl alcohol (IBA) as an antioxidant.

Water Dynamics and Proton-Transport Mechanisms of Nafion 117/Phosphotungstic Acid Composite Membrane: A Molecular Dynamics Study.

The use of a Nafion/phosphotungstic acid composite membrane and the impact of varying concentration of heteropoly acid (HPA) on the well-known effective mechanisms of proton transport were investigated by using classical and quantum hopping molecular dynamics simulation. Our simulations demonstrated that the HPA particles have a favorable influence on the Grotthuss mechanism in proton transportation at low hydration levels. From radial distribution function examinations, it was found that HPA particles were solvated with water and also exhibited stronger affinity toward hydronium ions.

Flexible shape-memory scaffold for minimally invasive delivery of functional tissues.

Despite great progress in engineering functional tissues for organ repair, including the heart, an invasive surgical approach is still required for their implantation. Here, we designed an elastic and microfabricated scaffold using a biodegradable polymer (poly(octamethylene maleate (anhydride) citrate)) for functional tissue delivery via injection. The scaffold's shape memory was due to the microfabricated lattice design.

Increase in intraocular pressure is less with propofol and remifentanil than isoflurane with remifentanil during cataract surgery: A randomized controlled trial.

Background: This double-blinded, randomized clinical trial was designed to evaluate intraocular pressure (IOP) change in cataract surgery using the combination of propofol and remifentanil or the combination of isoflurane and remifentanil.

Materials And Methods: One hundred sixty patients were randomly allocated to a maintenance anesthetic consisting of remifentanil + isoflurane (group I), normal saline + isoflurane (group II), propofol + remifentanil (group III) or normal saline + propofol (group IV). IOP was measured at seven predefined time points, baseline (T0), 3 min after the start of continuous remifentanil infusion (T2), after induction of anesthesia (T3), immediately after laryngoscopy and intubation (T4), 5 min after laryngoscopy (T5), immediately after the block of continuous remifentanil infusion (T6) and 3 min after T6 (T7).

Nitrogen in chromium-manganese stainless steels: a review on the evaluation of stacking fault energy by computational thermodynamics.

Nitrogen in austenitic stainless steels and its effect on the stacking fault energy (SFE) has been the subject of intense discussions in the literature. Until today, no generally accepted method for the SFE calculation exists that can be applied to a wide range of chemical compositions in these systems. Besides different types of models that are used from first-principle to thermodynamics-based approaches, one main reason is the general lack of experimentally measured SFE values for these steels.