New and Unforeseen Crystal Growth Processes for a Metal Oxide

The synthesis of corundum (α-Al2O3) via a layered Al2O3–MoO3 system was directly observed for the first time. This revealed a new crystal growth process with three key features: (1) the formation of an Al2(MoO4)3 intermediate layer through a solid–solid interaction in the temperature range of ∼705–860 °C; (2) the melting of the Al2(MoO4)3 layer between approximately 870 and 890 °C; and (3) the decomposition of Al2(MoO4)3 to corundum between 950 and 1100 °C. This molten intermediate decomposition (MIND) mechanism produced corundum, which was light bluish-gray in color and was defined in CIE (L* a* b*) color space as L* = 76.65, a* = −1.09, and b* = −6.20. The reagents used in this study were the same as those used in MoO3 flux growth studies on the synthesis of corundum, therefore demonstrating that the previous work only gave a superficial treatment of the mechanism of formation

New and Unforeseen Crystal Growth Processes for a Metal Oxide

The synthesis of corundum (α-Al2O3) via a layered Al2O3–MoO3 system was directly observed for the first time. This revealed a new crystal growth process with three key features: (1) the formation of an Al2(MoO4)3 intermediate layer through a solid–solid interaction in the temperature range of ∼705–860 °C; (2) the melting of the Al2(MoO4)3 layer between approximately 870 and 890 °C; and (3) the decomposition of Al2(MoO4)3 to corundum between 950 and 1100 °C. This molten intermediate decomposition (MIND) mechanism produced corundum, which was light bluish-gray in color and was defined in CIE (L* a* b*) color space as L* = 76.65, a* = −1.09, and b* = −6.20. The reagents used in this study were the same as those used in MoO3 flux growth studies on the synthesis of corundum, therefore demonstrating that the previous work only gave a superficial treatment of the mechanism of formation

Revealing early stage nuleation events of pharmaceutical crystals using liquid phase electron microscopy

Liquid phase electron microscopy has enabled the direct observation of liquid phase events that had previously been unexplored in situ at the nanoscale such as nanoparticle nucleation, electrochemical dynamics, catalysis transformations.[1, 2, 3] So far the information gathered utilising this invaluable in situ technique has gathered traction for inorganic materials as well as soft materials owing to the performance of instrumentation paired with in situ equipment e.g. TEM environmental holders and direct electron detectors

Non‑classical crystallisation pathway directly observed for a pharmaceutical crystal via liquid phase electron microscopy

Non‑classical crystallisation (NCC) pathways are widely accepted, however there is conflicting evidence regarding the intermediate stages of crystallisation, how they manifest and further develop into crystals. Evidence from direct observations is especially lacking for small organic molecules, as distinguishing these low‑electron dense entities from their similar liquid‑phase surroundings presents signal‑to‑noise ratio and contrast challenges. Here, Liquid Phase Electron Microscopy (LPEM) captures the intermediate pre‑crystalline stages of a small organic molecule, flufenamic acid (FFA), a common pharmaceutical. High temporospatial imaging of FFA in its native environment, an organic solvent, suggests that in this system a Pre‑Nucleation Cluster (PNC) pathway is followed by features exhibiting two‑step nucleation. This work adds to the growing body of evidence that suggests nucleation pathways are likely an amalgamation of multiple existing non‑classical theories and highlights the need for the direct evidence presented by in situ techniques such as LPE

Visualising early-stage liquid phase organic crystal growth via liquid cell electron microscopy†

Here, we show that the development of nuclei and subsequent growth of a molecular organic crystal system can be induced by electron beam irradiation by exploiting the radiation chemistry of the carrier solvent. The technique of Liquid Cell Electron Microscopy was used to probe the crystal growth of flufenamic acid; a current commercialised active pharmaceutical ingredient. This work demonstrates liquid phase electron microscopy analysis as an essential tool for assessing pharmaceutical crystal growth in their native environment while giving insight into polymorph identification of nano-crystals at their very inception. Possible mechanisms of crystal nucleation due to the electron beam with a focus on radiolysis are discussed along with the innovations this technique offers to the study of pharmaceutical crystals and other low contrast materials

Strain and Architecture-Tuned Reactivity in Ceria Nanostructures; Enhanced Catalytic Oxidation of CO to CO₂

Atomistic simulations reveal that the chemical reactivity of ceria nanorods is increased when tensioned and reduced when compressed promising strain-tunable reactivity; the reactivity is determined by calculating the energy required to oxidize CO to CO₂ by extracting oxygen from the surface of the nanorod. Visual reactivity “fingerprints”, where surface oxygens are colored according to calculated chemical reactivity, are presented for ceria nanomaterials including: nanoparticles, nanorods, and mesoporous architectures. The images reveal directly how the nanoarchitecture (size, shape, channel curvature, morphology) and microstructure (dislocations, grain-boundaries) influences chemical reactivity. We show the generality of the approach, and its relevance to a variety of important processes and applications, by using the method to help understand: TiO₂ nanoparticles (photocatalysis), mesoporous ZnS (semiconductor band gap engineering), MgO (catalysis), CeO₂/YSZ interfaces (strained thin films; solid oxide fuel cells/nanoionics), and Li-MnO₂ (lithiation induced strain; energy storage)

Strain and Architecture-Tuned Reactivity in Ceria Nanostructures; Enhanced Catalytic Oxidation of CO to CO₂

Atomistic simulations reveal that the chemical reactivity of ceria nanorods is increased when tensioned and reduced when compressed promising strain-tunable reactivity; the reactivity is determined by calculating the energy required to oxidize CO to CO₂ by extracting oxygen from the surface of the nanorod. Visual reactivity “fingerprints”, where surface oxygens are colored according to calculated chemical reactivity, are presented for ceria nanomaterials including: nanoparticles, nanorods, and mesoporous architectures. The images reveal directly how the nanoarchitecture (size, shape, channel curvature, morphology) and microstructure (dislocations, grain-boundaries) influences chemical reactivity. We show the generality of the approach, and its relevance to a variety of important processes and applications, by using the method to help understand: TiO₂ nanoparticles (photocatalysis), mesoporous ZnS (semiconductor band gap engineering), MgO (catalysis), CeO₂/YSZ interfaces (strained thin films; solid oxide fuel cells/nanoionics), and Li-MnO₂ (lithiation induced strain; energy storage)

Effect of ISO-1 and dexamethasone on ozone-induced lung inflammation.

<p>Cytokine mRNA (A, C, E & G) and protein (B, D, F & H) expression levels in the lung of ozone exposed and ISO-1- or dexamethasone-treated mice. KC (A&B), GM-CSF (C&D), TNF-α (E&F), and MIF (G&H). Data are expressed as mean±SD for 6 animals per group. *<i>p</i><0.05 and **<i>p</i><0.01 compared to air controls, ^#<i>p</i><0.05 compared to ozone exposed group.</p

Effect of ISO-1 and dexamethasone on ozone-induced changes in AHR and lung function.

<p>Mouse lung function measurements of pulmonary resistance (R_L; A), -logPC₁₀₀ (B), FEV₇₅ (C), lung compliance (C_chord; D), total lung capacity (TLC; E) and functional residual capacity (FRC; F). Data are expressed as mean±SD for 6 animals per group. *<i>p</i><0.05 and **<i>p</i><0.01 compared to air controls, ^#<i>p</i><0.05 compared to ozone-exposed group.</p

Effect of ISO-1 and dexamethasone on ozone-induced BAL inflammation.

<p>Cytokine protein levels in mouse BAL of ozone exposed and ISO-1- or dexamethasone-treated mice measured by ELISA. KC (A), GM-CSF (B), TNF-α (C) and MIF (D). Data are expressed as mean±SD for 6 animals per group. *<i>p</i><0.05 and **<i>p</i><0.01 compared to air controls, # <i>p</i><0.05 compared to ozone exposed group.</p