Mutual phase stabilization of aluminium phosphate and titania in AlPO4-TiO2 binary system

Crystallization behaviour of amorphous aluminium phosphate (AlPO4) an titania (TiO2) in a mixed system of the two (5:1) has been reviewed in the light of our recent results. The polymorphous aluminium phosphate in such a binary system grows exclusively in a single phase over a temperature range 500-1150-degrees-C. The phase is reported to have a tridymite-like structure belonging to orthorhombic system with cell parameters a = 9.638 +/-0-0019, b = 8.664 +/- 0-0017 and c = 18.280 +/- 0036 angstrom. Titania in the system preferentially retains its anatase phase morphology up to a temperature (950-degrees-C) well beyond its normal anatase —> rutile transformation temperature showing a phenomenon of stabilization of this phase in such mixture. An interfacial reaction mechanism that can explain the observed phenomenon of mutual phase stabilization has been discussed and implications of this result towards the use of such technique for stabilization of various polymorphous compounds in a single phase has been pointed out

Matrix stiffness drives epithelial–mesenchymal transition and tumour metastasis through a TWIST1–G3BP2 mechanotransduction pathway

Matrix stiffness potently regulates cellular behavior in various biological contexts. In breast tumours, the presence of dense clusters of collagen fibrils indicates increased matrix stiffness and correlates with poor survival. It is unclear how mechanical inputs are transduced into transcriptional outputs to drive tumour progression. Here we report that TWIST1 is an essential mechano-mediator that promotes epithelial-mesenchymal transition (EMT) in response to increasing matrix stiffness. High matrix stiffness promotes nuclear translocation of TWIST1 by releasing TWIST1 from its cytoplasmic binding partner G3BP2. Loss of G3BP2 leads to constitutive TWIST1 nuclear localization and synergizes with increasing matrix stiffness to induce EMT and promote tumour invasion and metastasis. In human breast tumours, collagen fiber alignment, a marker of increasing matrix stiffness, and reduced expression of G3BP2 together predict poor survival. Our findings reveal a TWIST1-G3BP2 mechanotransduction pathway that responds to biomechanical signals from the tumour microenvironment to drive EMT, invasion, and metastasis

Surface-bound titania-induced selective growth and stabilization of tridymite aluminum phosphate

The crystallization behavior of amorphous aluminum phosphate (AlPO4) has been studied by X-ray diffraction as a function of the treatment temperature (500–1150°C) in the presence of small amounts of titania (TiO2) anchored onto its surface. The compound, which like silica can exist in several possible crystalline modifications depending on the treatment temperature, is found to grow in the presence of TiO2 exclusively in a single phase in the entire range of temperatures studied. The phase has been shown to have the tridymite structure belonging to the orthorhombic system with cell parameters a = 9.638 ± 0.0019, b = 8.664 ± 0.0017, and c = 18.280 ± 0036Å

Coordination structure and the bonding properties of UV-laser induced photo-generated Cu(II) in a monovalent copper-containing silica glass

Observation of a phenomenon of UV-light-induced photo-oxidation of copper(I) under doped conditions in a silica glass has been reported and a mechanism of electron transfer from the photo-excited precursor (Cu+)(*) to a neighbouring ionized aluminium centre [AlO4Na+](+) which is also generated in the glass as a result of W irradiation has been proposed. Calculation of the metal-ligand interaction parameters of the photo-produced CU2+, revealed that the oxygens surrounding the majority of the ions in the glass have a square planar coordination structure where the ligands form a strong covalent bond with the cation

Site-dependent thermoluminescence of copper(I) ions in silica glass

Similar to our earlier observations of site-dependent photoluminescence of Cu+ ions in a silica glass a phenomenon of site-sensitive copper(I)-related thermoluminescence has been observed in the glass after gamma-irradiation. The results have been interpreted in terms of a process of site-to-site direct recombination of different copper-associated aluminium hole centres with their respective electrons

Optical-absorption and epr of Cu(II) in an alumina rich phosphate-glass

Optical absorption and electron paramagnetic properties of Cu(II) in a potassium barium phosphate glass containing as high as 20 mol% alumina (Al2O3) have been investigated. Results suggest that the oxygen field surrounding the ion in the glass should be an elongated rhombic octahedron. Rhombic distortions of the field structure have been shown to originate from the structural change of the glass network as a result of crosslinking of the phosphate chains by the alumina of the system

Inhibiting effect of AlPO4 and SiO2 on the anatase → rutile transformation reaction: An x-ray and laser Raman study

The anatase —> rutile transformation reaction of TiO2 prepared in contact with amorphous aluminum phosphate and with fume silica has been investigated as a function of temperature by x-ray diffraction methods. It is observed that the anatase —> rutile transformation in such systems becomes greatly inhibited and the Raman spectra of titania on such surfaces exhibit features that indicate substrate-TiO2 interfacial reactions