Advances in modeling transport phenomena in material-extrusion additivemanufacturing: Coupling momentum, heat, and mass transfer

Material-extrusion (MatEx) additive manufacturing involves layer-by-layer assembly ofextruded material onto a printer bed and has found applications in rapid prototyping.Both material and machining limitations lead to poor mechanical properties of printedparts. Such problems may be addressed via an improved understanding of thecomplex transport processes and multiphysics associated with the MatEx process.Thereby, this review paper describes the current (last 5 years) state of the art modelingapproaches based on momentum, heat and mass transfer that are employed in aneffort to achieve this understanding. We describe how specific details regardingpolymer chain orientation, viscoelastic behavior and crystallization are often neglectedand demonstrate that there is a key need to couple the transport phenomena. Such acombined modeling approach can expand MatEx applicability to broader applicationspace, thus we present prospective avenues to provide more comprehensive modelingand therefore new insights into enhancing MatEx performanc

A Comparative Study of Methanol Adsorption and Dissociation over WO₃(001) and ReO₃(001)

Tungsten (5d46s2) and rhenium (5d56s2) form MO3 oxides (M = W or Re) with similar structures. The adsorption and dissociation of methanol on these oxide surfaces, often used to probe the surface redox centers, have been analyzed using periodic density functional calculations. Molecular adsorption of methanol at the metal site on both surfaces with 0.5 ML oxygen coverage was found to be exothermic with adsorption energies of -74 and -106 kJ/mol on WO3(001) and ReO3(001), respectively. In contrast, heterolytic dissociation of methanol to adsorbed methoxide species at the metal site and H at the surface oxygen site is not energetically favored on WO3(001) but favored on ReO3(001). The dissociation energies to form coadsorbed methoxide and hydrogen adatom are 35 kJ/mol on WO3 and -112 kJ/mol on ReO3, respectively. The activation barrier for dissociating the molecularly adsorbed methanol on ReO3(001) was determined to be 19 kJ/mol. Dehydrogenation to form coadsorbed hydroxymethyl and hydrogen adatom is not energetically favorable on both surfaces with respect to the molecularly adsorbed methanol. However, the dehydrogenation path is exothermic with respect to the gas phase methanol on ReO3, with the heats of reaction of -25 kJ/mol, but highly endothermic on WO3, with the heats of reaction of 114 kJ/mol

Delayed Neuropathy Due to Organophosphate Insecticide Injection in an Attempt to Commit Suicide

Organophosphates (OPs) are commonly used as pesticides throughout the world. Exposures to OPs cause a significant number of poisonings and deaths every year. Organophosphate-induced delayed polyneuropathy is a sensory-motor distal axonopathy which usually occurs after exposure of certain OP insecticides. Neuropathies due to ingestion of OPs have rarely been reported in the literature. Moreover, until now, there is no report of a patient developing organophosphorus injection-induced delayed neuropathy in the literature. We report a patient with serious organophosphorus-induced delayed neuropathy due to malathion injection. The patient was a 32-year-old female who self-injected undetermined amounts of malathion over the median nerve trace on the forearm crease in a suicide attempt which resulted in peripheral neuropathy

A three-dimensional strain measurement method in elastic transparent materials using tomographic particle image velocimetry

The mechanical interaction between blood vessels and medical devices can induce strains in these vessels. Measuring and understanding these strains is necessary to identify the causes of vascular complications. This study develops a method to measure the three-dimensional (3D) distribution of strain using tomographic particle image velocimetry (Tomo-PIV) and compares the measurement accuracy with the gauge strain in tensile tests.The test system for measuring 3D strain distribution consists of two cameras, a laser, a universal testing machine, an acrylic chamber with a glycerol water solution for adjusting the refractive index with the silicone, and dumbbell-shaped specimens mixed with fluorescent tracer particles. 3D images of the particles were reconstructed from 2D images using a multiplicative algebraic reconstruction technique (MART) and motion tracking enhancement. Distributions of the 3D displacements were calculated using a digital volume correlation. To evaluate the accuracy of the measurement method in terms of particle density and interrogation voxel size, the gauge strain and one of the two cameras for Tomo-PIV were used as a video-extensometer in the tensile test. The results show that the optimal particle density and interrogation voxel size are 0.014 particles per pixel and 40 × 40 × 40 voxels with a 75% overlap. The maximum measurement error was maintained at less than 2.5% in the 4-mm-wide region of the specimen.We successfully developed a method to experimentally measure 3D strain distribution in an elastic silicone material using Tomo-PIV and fluorescent particles. To the best of our knowledge, this is the first report that applies Tomo-PIV to investigate 3D strain measurements in elastic materials with large deformation and validates the measurement accuracy

Enhanced extraction of proteins using cholinium-based ionic liquids as phase-forming components of aqueous biphasic systems

Aqueous biphasic systems (ABS) composed of ionic liquids (ILs) are promising platforms for the extraction and purification of proteins. In this work, a series of alternative and biocompatible ABS composed of cholinium-based ILs and polypropylene glycol were investigated. The respective ternary phase diagrams, tie-lines, tie-line lengths and critical points were determined at 25 degrees C. The extraction performance of these systems for commercial bovine serum albumin (BSA) was then evaluated. The stability of BSA at the IL-rich phase was ascertained by size exclusion high-performance liquid chromatography and Fourier transform infrared spectroscopy. Appropriate ILs lead to the complete extraction of BSA for the IL-rich phase, in a single step, while maintaining the protein's native conformation. Furthermore, to evaluate the performance of these systems when applied to real matrices, the extraction of BSA from bovine serum was additionally carried out, revealing that the complete extraction of BSA was maintained and achieved in a single step. The remarkable extraction efficiencies obtained are far superior to those observed with typical polymer-based ABS. Therefore, the proposed ABS may be envisaged as a more effective and biocompatible approach for the separation and purification of other value-added proteins