Materials and Systems Research (United States)

Calcium sulfate, and especially its hemihydrate form (bassanite), is crucial in the construction industry, primarily used as a hydraulic binder in cements, mortars, and wallboards. Because of the rapid transformation of bassanite into thermodynamically stable gypsum (calcium sulfate dihydrate) upon contact with water, natural deposits are scarce, rendering it one of the most extensively produced inorganic materials worldwide. Currently, bassanite is derived from mined or waste gypsum through a thermal dehydration process, which is energy-intensive and costly. As sustainability has become a key target for industrial processes and products, a series of studies aiming to increase the energy efficiency and reduce the carbon footprint of bassanite production was published recently. Two primary approaches are pursued: conversion of gypsum and direct precipitation of bassanite from solution. In both cases, organic solvents, (specific) additives and/or elevated temperatures have been used to control the activity/availability of water in the reaction medium and thus direct phase selection towards bassanite. This review offers a comprehensive overview of alternative bassanite production methods, critically examining their benefits, potential downsides, and overall impact on the sustainability of industrial-scale use.

Background: Effective formative feedback is an important educational intervention in clinical learning. Receiving formative feedback enhances knowledge and skill acquisition and promotes reflective practice. The provision of feedback is a critical component of this education and requires a bidirectional process between learner and preceptor. Despite this critical role in health profession learning, there has been limited exploration of how preceptors provide feedback in the Ontario midwifery education setting. Aim: To determine strategies for how formative feedback could be provided in the Ontario midwifery education setting to maximize students’ clinical learning. Methods: We conducted a narrative literature review using PubMed, Ovid MEDLINE, and CINAHL databases. Following our initial search, each title and abstract was assessed for inclusion for full text review. The final data set was reviewed and coded in order to undertake a descriptive thematic analysis. Findings: There is little Ontario-specific midwifery feedback literature. Thematic analysis identified that understanding best practices for feedback, preparing both student and preceptor for a feedback relationship, and using a written format and a standardized assessment tool for feedback are strategies that can optimize learning in the clinical setting. The need for improved formative feedback provision has been identified in other midwifery jurisdictions, resulting in the introduction of workplace-based assessment tools to provide structured, high-quality feedback. The introduction of such a tool, specifically the midwifery mini-clinical evaluation exercise tool, may promote improved learning for students. This article has been peer reviewed.

We report a successful fabrication of long-length rolling-assisted biaxially-textured substrate-based coated conductors (CCs) via chemical solution deposition starting from colloidal YBa2Cu3O7-δ (YBCO) solutions containing 5 mol-% preformed BaMO3 (M = Hf, Zr) (BMO) nanocrystals. Partial optimization of the existing continuous reel-to-reel YBCO processing via design of experiments approach allowed us to obtain YBCO nanocomposites that retain 80%–90% self-field performance of the pristine CC and show a 10%–40% improvement of in-field critical current, which is only a moderate performance improvement compared to similar films on single-crystal substrates prepared on lab-scale. Based on x-ray diffraction and transmission electron microscopy studies, we attribute this to worsening of the YBCO texture and strong coarsening of BMO nanoparticles, particularly, BaZrO3, during processing. Possible process improvements to overcome these effects are discussed.

Abstract We examine the nature of the chemical reactions taking place in a waterborne two‐component polyurethane formulation consisting of an acrylic polyol latex and a hydrophilically modified polyisocyanate (hmPIC) based on the trimer of hexamethylene diisocyanate. The hmPIC was diluted with 30 wt.% of an organic solvent to reduce its viscosity and formed small (~20 nm) droplets when dispersed in water. In mixtures of the polyol and hmPIC, we monitored the rate of NCO group disappearance in the dispersed state by FTIR and showed that it varied with the choice of organic solvent. We developed a method based upon 19F NMR to distinguish the reaction of the NCO groups with OH groups from the polyol from its reaction with water. FTIR measurements on films formed from these dispersions showed how the disappearance of NCO groups depended on relative humidity. In a more semi‐quantitative way, these measurements indicated the relative extent of urethane versus urea formation in these model coatings.

Herein, the proof of concept of a sodium polysulfide battery consisting of two electrode chambers being separated by a solid electrolyte is described. The concept is suited for dissolved polysulfide cathodes and has the advantage that both half reactions can be optimized separately. The formation of solid sulfide discharge products is identified as the major limiting factor for cell cycling. This issue can be alleviated by adding solid P2S5. Further improvement can be achieved by replacing diglyme (2G) as the cathode compartment solvent with tetramethylurea (TMU). Using TMU, the cell cycles with Coulombic efficiencies >99% and capacities of 800 mAh g−1 are maintained for at least 30 cycles. Viscosity, density, conductivity, and the electrochemical stability window values of the 2G‐ and TMU‐based electrolytes are compared. The latter shows higher viscosity (2.806 vs 1.603 mPa s), higher density (1.016 vs 0.996 g cc−1), and higher conductivity (4.27 vs 1.45 mS cm−1). The oxidative stability limit of the TMU electrolyte is 3.2 V versus Na+/Na, which is sufficient for polysulfide redox reactions. Vis spectroscopy is used to follow the electrode reaction. In case of TMU, the reaction is based on the redox activity of S3−• radicals (blue coloration of the catholyte solution).

The life cycle of nanoscale pigments in plastics may cause environmental or human exposure by various release scenarios. We investigated spontaneous and induced release with mechanical stress during/after simulated sunlight and rain degradation of polyethylene (PE) with organic and inorganic pigments. Additionally, primary leaching in food contact and secondary leaching from nanocomposite fragments with an increased surface into environmental media was examined. Standardized protocols/methods for release sampling, detection, and characterization of release rate and form were applied: Transformation of the bulk material was analyzed by Scanning Electron Microscopy (SEM), X-ray-tomography and Fourier-Transform Infrared spectroscopy (FTIR); releases were quantified by Inductively Coupled Plasma Mass Spectrometry (ICP-MS), single-particle-ICP-MS (sp-ICP-MS), Transmission Electron Microscopy (TEM), Analytical Ultracentrifugation (AUC), and UV/Vis spectroscopy. In all scenarios, the detectable particulate releases were attributed primarily to contaminations from handling and machining of the plastics, and were not identified with the pigments, although the contamination of 4 mg/kg (Fe) was dwarfed by the intentional content of 5800 mg/kg (Fe as Fe2O3 pigment). We observed modulations (which were at least partially preventable by UV stabilizers) when comparing as-produced and aged nanocomposites, but no significant increase of releases. Release of pigments was negligible within the experimental error for all investigated scenarios, with upper limits of 10 mg/m2 or 1600 particles/mL. This is the first holistic confirmation that pigment nanomaterials remain strongly contained in a plastic that has low diffusion and high persistence such as the polyolefin High Density Polyethylene (HDPE).

The Front Cover picture shows silica gardens, a peculiar form of tubular precipitates that grow spontaneously in purely inorganic environments. Two synchrotron-based techniques were applied to investigate their growth on a fundamental physicochemical level. More information can be found in the Full Paper by W. Kunz, M. Kellermeier et al. on page 338 in Issue 4, 2017 (DOI: 10.1002/cphc.201600748).

GO-imbedded nanocomposite hollow fiber membranes were investigated for oily water treatment, with the aim to improve GO-polymer interfacial interaction and membrane anti-fouling properties via the formation of a simultaneously covalent and ionic inter-network.