Additional file 1 of A dual deep neural network for auto-delineation in cervical cancer radiotherapy with clinical validation

Additional file 1. Supplemental methods, tables, and figures

Systematic Study of Cr³⁺ Substitution into Octahedra-Based Microporous Aluminoborates

Single crystals of pure aluminoborate PKU-1 (Al₃B₆O₁₁(OH)₅·<i>n</i>H₂O) were obtained, and the structure was redetermined by X-ray diffraction. There are three independent Al atoms in the <i>R</i>3 structure model, and Al3 locates in a quite distorted octahedral environment, which was evidenced by ²⁷Al NMR results. This distortion of Al3O₆ octahedra release the strong static stress of the main framework and leads to a symmetry lowering from the previously reported <i>R</i>3̅ to the presently reported <i>R</i>3. We applied a pretreatment to prepare Al³⁺/Cr³⁺ aqueous solutions; as a consecquence, a very high Cr³⁺-to-Al³⁺ substitution content (∼50 atom %) in PKU-1 can be achieved, which is far more than enough for catalytic purposes. Additionally, the preference for Cr³⁺ substitution at the Al1 and Al2 sites was observed in the Rietveld refinements of the powder X-ray data of PKU-1:0.32Cr³⁺. We also systematically investigated the thermal behaviors of PKU-1:<i>x</i>Cr³⁺ (0 ≤ <i>x</i> ≤ 0.50) by thermogravimetric–differential scanning calorimetry, in situ high-temperature XRD in vacuum, and postannealing experiments in furnace. The main framework of Cr³⁺-substituted PKU-1 could be partially retained at 1100 °C in vacuum. When 0.04 ≤ <i>x</i> ≤ 0.20, PKU-1:<i>x</i>Cr³⁺ transferred to the PKU-5:<i>x</i>Cr³⁺ (Al₄B₆O₁₅:<i>x</i>Cr³⁺) structure at ∼750 °C by a 5 h annealing in air. Further elevating the temperature led to a decomposition into the mullite phase, Al₄B₂O₉:<i>x</i>Cr³⁺. For <i>x</i> > 0.20 in PKU-1:<i>x</i>Cr³⁺, the heat treatment led to a composite of Cr³⁺-substituted PKU-5 and Cr₂O₃, so the doping upper limit of Cr³⁺ in PKU-5 structure is around 20 atom %