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- ItemMixed Cu-Fe Sulfides Derived from Polydopamine-Coated Prussian Blue Analogue as a Lithium-Ion Battery Electrode(Washington, DC : ACS Publications, 2022) Bornamehr, Behnoosh; Presser, Volker; Husmann, SamanthaBatteries employing transition-metal sulfides enable high-charge storage capacities, but polysulfide shuttling and volume expansion cause structural disintegration and early capacity fading. The design of heterostructures combining metal sulfides and carbon with an optimized morphology can effectively address these issues. Our work introduces dopamine-coated copper Prussian blue (CuPB) analogue as a template to prepare nanostructured mixed copper-iron sulfide electrodes. The material was prepared by coprecipitation of CuPB with in situ dopamine polymerization, followed by thermal sulfidation. Dopamine controls the particle size and favors K-rich CuPB due to its polymerization mechanism. While the presence of the coating prevents particle agglomeration during thermal sulfidation, its thickness demonstrates a key effect on the electrochemical performance of the derived sulfides. After a two-step activation process during cycling, the C-coated KCuFeS2electrodes showed capacities up to 800 mAh/g at 10 mA/g with nearly 100% capacity recovery after rate handling and a capacity of 380 mAh/g at 250 mA/g after 500 cycles.
- ItemSynthesis of 3,4-Dihydro-2H-Pyrroles from Ketones, Aldehydes, and Nitro Alkanes via Hydrogenative Cyclization(Weinheim : Wiley-VCH, 2022) Klausfelder, Barbara; Blach, Patricia; de Jonge, Niels; Kempe, RhettSyntheses of N-heterocyclic compounds that permit a flexible introduction of various substitution patterns by using inexpensive and diversely available starting materials are highly desirable. Easy to handle and reusable catalysts based on earth-abundant metals are especially attractive for these syntheses. We report here on the synthesis of 3,4-dihydro-2H-pyrroles via the hydrogenation and cyclization of nitro ketones. The latter are easily accessible from three components: a ketone, an aldehyde and a nitroalkane. Our reaction has a broad scope and 23 of the 33 products synthesized are compounds which have not yet been reported. The key to the general hydrogenation/cyclization reaction is a highly active, selective and reusable nickel catalyst, which was identified from a library of 24 earth-abundant metal catalysts.
- Item3D Printed Tubular Scaffolds with Massively Tailorable Mechanical Behavior(Weinheim : Wiley-VCH, 2022) Pickering, Edmund; Paxton, Naomi C.; Bo, Arixin; O’Connell, Bridget; King, Mitchell; Woodruff, Maria A.Melt electrowriting (MEW) is a promising additive manufacturing technique for tissue scaffold biofabrication. Successful application of MEW scaffolds requires strictly controlled mechanical behavior. This requires scaffold geometry be optimized to match native tissue properties while simultaneously supporting cell attachment and proliferation. The objective of this work is to investigate how geometric properties can be exploited to massively tailor the mechanical behavior of tubular crosshatch scaffolds. An experimentally validated finite element (FE) model is developed and 441 scaffold geometries are investigated under tension, compression, bending, and radial loading. A range of pore areas (4–150 mm2) and pore angles (11°–134°) are investigated. It is found that scaffold mechanical behavior is massively tunable through the control of these simple geometric parameters. Across the ranges investigated, scaffold stiffness varies by a factor of 294× for tension, 204× for compression, 231× for bending, and 124× for radial loading. Further, it is discussed how these geometric parameters can be simultaneously tuned for different biomimetic material applications. This work provides critical insights into scaffold design to achieve biomimetic mechanical behavior and provides an important tool in the development of biomimetic tissue engineered constructs.