In order to increase the loading of rare earth- and molybdenum-rich high-level waste in the waste forms, zirconolite- and powellite-based multi-phase borosilicate glass-ceramics were synthesized via an in-situ heat treatment method. The effects of the CTZ (CaO, TiO2 and ZrO2) content on the crystallization, microstructure and aqueous durability of the multi-phase borosilicate glass-ceramics were studied. The results indicate that the increase of CTZ content can promote crystallization. The glass-ceramics presented even structures when the CTZ content was ≥ 40 wt%. For the glass-ceramic with 40 wt% CTZ, only zirconolite and powellite crystals were detected and powellite crystals were mainly distributed around zirconolite, whereas for the glass-ceramics with 50 wt% CTZ, perovskite was detected. Furthermore, the leaching rates of Na, Ca, Mo and Nd were in the ×10−3, ×10−4, ×10−3 and ×10−5 g·m−2·d·−1 orders of magnitude on the 28th leaching day, respectively.
Surfactant-like
short peptides are a kind of ideal model for the
study of chiral self-assembly. At present, there are few studies on
the chiral self-assembly of multicharged surfactant-like peptides.
In this study, we adopted a series of short peptides of Ac-I4KGK-NH2 with different combinations of L-lysine and D-lysine residues as the model
molecules. TEM, AFM and SANS results showed that Ac-I4
L
KG
L
K-NH2, Ac-I4
L
KG
D
K-NH2, and Ac-I4
D
KG
L
K-NH2 formed the
morphologies of nanofibers, and Ac-I4
D
KG
D
K-NH2 formed nanoribbons.
All the self-assembled nanofibers, including the intermediate nanofibers
of Ac-I4
D
KG
D
K-NH2 nanoribbons, showed the chirality of left
handedness. Based on the molecular simulation results, it has been
demonstrated that the supramolecular chirality was directly dictated
by the orientation of single β strand. The insertion of glycine
residue demolished the effect of lysine residues on the single strand
conformation due to its high conformational flexibility. The replacement
of L-isoleucine with Da-isoleucine
also confirmed that the isoleucine residues involved in the β-sheet
determined the supramolecular handedness. This study provides a profound
mechanism of the chiral self-assembly of short peptides. We hope that
it will improve the regulation of chiral molecular self-assembly with
achiral glycine, as well.
In this paper, the effect of doping phosphorus in a borosilicate glass matrix to improve the solubility of Mo was investigated by X-ray diffraction (XRD), Raman, and solid-state nuclear magnetic resonance (NMR) spectroscopy, and the effectiveness of Na content on P species inhibiting the growth of the crystallization of Mo was assessed. The results indicate that phosphate-doped borosilicate glass can host 4 mol% of Mo, and that such a borosilicate glass matrix could only accommodate 1 mol% of Mo without phosphate doping. The effectiveness of phosphorus may be correlated with the Na content in borosilicate glass, and a high Na content borosilicate glass matrix requires more P doping to accommodate Mo. In addition, incorporating large amounts of P can compromise the aqueous durability of the glass matrix.
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