Dynamic fracture surrounds us in our day-to-day lives, but animating this phenomenon is notoriously difficult and only further complicated by anisotropic materials---those with underlying structures that dictate preferred fracture directions. Thus, we present AnisoMPM: a robust and general approach for animating the dynamic fracture of isotropic, transversely isotropic, and orthotropic materials. AnisoMPM has three core components: a technique for anisotropic damage evolution, methods for anisotropic elastic response, and a coupling approach. For anisotropic damage, we adopt a non-local continuum damage mechanics (CDM) geometric approach to crack modeling and augment this with structural tensors to encode material anisotropy. Furthermore, we discretize our damage evolution with explicit and implicit integration, giving a high degree of computational efficiency and flexibility. We also utilize a QR-decomposition based anisotropic constitutive model that is inversion safe, more efficient than SVD models, easy to implement, robust to extreme deformations, and that captures all aforementioned modes of anisotropy. Our elasto-damage coupling is enforced through an additive decomposition of our hyperelasticity into a tensile and compressive component in which damage is used to degrade the tensile contribution to allow for material separation. For extremely stiff fibered materials, we further introduce a novel Galerkin weak form discretization that enables embedded directional inextensibility. We present this as a hard-constrained grid velocity solve that poses an alternative to our anisotropic elasticity that is locking-free and can model very stiff materials.

Bi 2 WO 6 is one of the simplest members of the versatile Aurivillius oxide family of materials. An intriguing model system for Aurivillius oxides, BiVO 4 exhibits low water oxidation onset potentials (~0.5-0.6 V RHE ) for driven solar water oxidation. Despite this, Bi 2 WO 6 also produces low photocurrents in comparison to other metal oxides. Due to a lack of in-situ studies, the reasons for such poor performance are not understood. In this study, Bi 2 WO 6 photoanodes are synthesised by aerosol-assisted chemical vapour deposition. The charge carrier dynamics of Bi 2 WO 6 are studied in-situ under water oxidation conditions and the rate of both bulk recombination and water oxidation is found to be comparable to other metal oxide photoanodes. However, the rate of electron extraction is at least 10 times slower than slowest kinetics previously reported in an oxide photoanode. First-principles analysis indicates that the slow electron extraction kinetics are linked to a strong anisotropy in the conduction band. Preferred or epitaxial growth along the conductive axes is a strategy to overcome slow electron transport and low photocurrent densities in layered materials such as Bi 2 WO 6.

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Microfibrillar biochars of chitin (CTF), chitosan (CSF), and cellulose (CLF) were fabricated via green homogenization and a pyrolysis process, and were subsequently explored as adsorbents for removing over-released sodium benzoate (SB) in aqueous systems. The structure, composition, morphology, and adsorption behavior of the as-fabricated biochars were characterized. Results suggest that all biochars, with a microscaled fibrillar structure and foam-like network morphology, underwent severe chemical transition during the pyrolysis process, thereby causing an enhancement of the Brunauer–Emmett–Teller surface area, pore volume, and aromatic and carbonaceous composition. Consequently, N-doped porous CTF/CSF microfibrillar biochars displayed a distinguished capture capacity toward SB compared to that of their fibrillar precursors. Tailoring the chemical composition, porous structure, and sorption mechanism constitutes a possible strategy to achieve adequate structural effects of polysaccharide microfibrillar chars for potential application in environmental treatment or bioenergy.

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