The Experts below are selected from a list of 4401 Experts worldwide ranked by ideXlab platform
Hervé Leclerc - One of the best experts on this subject based on the ideXlab platform.
-
Microwave Synthesis of an Aluminum Fluoride Hydrate with Cationic Vacancies: Structure, Thermal Stability, and Acidic Properties
Chemistry of Materials, 2008Co-Authors: Damien Dambournet, Alain Demourgues, Charlotte Martineau, Etienne Durand, Jérôme Majimel, Christophe Legein, Jean-yves Buzaré, Franck Fayon, Alexandre Vimont, Hervé LeclercAbstract:Aluminum Fluoride hydrate was synthesized by a microwave hydrothermal process. The structure derives from the ReO3 type structure, that is, the high temperature structure of α-AlF3. The cubic symmetry adopted by this compound arises from water molecules, stabilized as ligand surrounding Al3+ cations which induces cationic vacancies as revealed by Rietveld refinement. The following chemical formula Al0.82◻0.18F2.46(H2O)0.54 is supported by chemical analysis and TGA measurements. This represents the first example of Aluminum vacancy compound in the Al-based Fluorides chemistry. High field 27Al NMR spectroscopy enabled identification and quantification of the following species: AlF6 and AlF6−x(H2O)x with x = 1, 2, 3, and showed that vacancies are mainly surrounded by water molecules but also by a low content of Fluoride ions as also evidenced by 19F NMR. The hydrogen bonding network, which takes place in the vicinity of the cationic vacancies, was characterized by FTIR and 1H NMR spectroscopies. A 2:1 comple...
-
Microwave synthesis of an Aluminum Fluoride hydrate with cationic vacancies: structure, thermal stability, and acidic properties
Chemistry of Materials, 2008Co-Authors: Damien Dambournet, Alain Demourgues, Charlotte Martineau, Etienne Durand, Jérôme Majimel, Christophe Legein, Jean-yves Buzaré, Franck Fayon, Alexandre Vimont, Hervé LeclercAbstract:Aluminum Fluoride hydrate was synthesized by a microwave hydrothermal process. The structure derives from the ReO3 type structure, that is, the high temperature structure of α-AlF3. The cubic symmetry adopted by this compound arises from water molecules, stabilized as ligand surrounding Al3+ cations which induces cationic vacancies as revealed by Rietveld refinement. The following chemical formula Al0.82◻0.18F2.46(H2O)0.54 is supported by chemical analysis and TGA measurements. This represents the first example of Aluminum vacancy compound in the Al-based Fluorides chemistry. High field 27Al NMR spectroscopy enabled identification and quantification of the following species: AlF6 and AlF6−x(H2O)x with x = 1, 2, 3, and showed that vacancies are mainly surrounded by water molecules but also by a low content of Fluoride ions as also evidenced by 19F NMR. The hydrogen bonding network, which takes place in the vicinity of the cationic vacancies, was characterized by FTIR and 1H NMR spectroscopies. A 2:1 complex X···H−O−H···X where X is a proton acceptor, which is related to a shift of the νsym(OH) and νasym(OH), was detected. This complex appears to be stable up to 773 K. The phase transition into the rhombohedral form occurs at around 573 K, but at such a temperature a large amount of water molecules associated to cationic vacancies still remained thanks to the 2:1 complex. The acidic properties have been revealed by pyridine and CO probe molecules. At 573 K, the solid exhibits both strong Lewis and Brønsted acidities with an equivalent number of sites providing bifunctionality. The strong acidic behavior highlights the effect of water molecules/cationic vacancies on the surface structure. Whereas the Lewis strength acidity progressively decreases with dehydration, Brønsted acidity remains strong even at 773 K.
Damien Dambournet - One of the best experts on this subject based on the ideXlab platform.
-
Microwave Synthesis of an Aluminum Fluoride Hydrate with Cationic Vacancies: Structure, Thermal Stability, and Acidic Properties
Chemistry of Materials, 2008Co-Authors: Damien Dambournet, Alain Demourgues, Charlotte Martineau, Etienne Durand, Jérôme Majimel, Christophe Legein, Jean-yves Buzaré, Franck Fayon, Alexandre Vimont, Hervé LeclercAbstract:Aluminum Fluoride hydrate was synthesized by a microwave hydrothermal process. The structure derives from the ReO3 type structure, that is, the high temperature structure of α-AlF3. The cubic symmetry adopted by this compound arises from water molecules, stabilized as ligand surrounding Al3+ cations which induces cationic vacancies as revealed by Rietveld refinement. The following chemical formula Al0.82◻0.18F2.46(H2O)0.54 is supported by chemical analysis and TGA measurements. This represents the first example of Aluminum vacancy compound in the Al-based Fluorides chemistry. High field 27Al NMR spectroscopy enabled identification and quantification of the following species: AlF6 and AlF6−x(H2O)x with x = 1, 2, 3, and showed that vacancies are mainly surrounded by water molecules but also by a low content of Fluoride ions as also evidenced by 19F NMR. The hydrogen bonding network, which takes place in the vicinity of the cationic vacancies, was characterized by FTIR and 1H NMR spectroscopies. A 2:1 comple...
-
Microwave synthesis of an Aluminum Fluoride hydrate with cationic vacancies: structure, thermal stability, and acidic properties
Chemistry of Materials, 2008Co-Authors: Damien Dambournet, Alain Demourgues, Charlotte Martineau, Etienne Durand, Jérôme Majimel, Christophe Legein, Jean-yves Buzaré, Franck Fayon, Alexandre Vimont, Hervé LeclercAbstract:Aluminum Fluoride hydrate was synthesized by a microwave hydrothermal process. The structure derives from the ReO3 type structure, that is, the high temperature structure of α-AlF3. The cubic symmetry adopted by this compound arises from water molecules, stabilized as ligand surrounding Al3+ cations which induces cationic vacancies as revealed by Rietveld refinement. The following chemical formula Al0.82◻0.18F2.46(H2O)0.54 is supported by chemical analysis and TGA measurements. This represents the first example of Aluminum vacancy compound in the Al-based Fluorides chemistry. High field 27Al NMR spectroscopy enabled identification and quantification of the following species: AlF6 and AlF6−x(H2O)x with x = 1, 2, 3, and showed that vacancies are mainly surrounded by water molecules but also by a low content of Fluoride ions as also evidenced by 19F NMR. The hydrogen bonding network, which takes place in the vicinity of the cationic vacancies, was characterized by FTIR and 1H NMR spectroscopies. A 2:1 complex X···H−O−H···X where X is a proton acceptor, which is related to a shift of the νsym(OH) and νasym(OH), was detected. This complex appears to be stable up to 773 K. The phase transition into the rhombohedral form occurs at around 573 K, but at such a temperature a large amount of water molecules associated to cationic vacancies still remained thanks to the 2:1 complex. The acidic properties have been revealed by pyridine and CO probe molecules. At 573 K, the solid exhibits both strong Lewis and Brønsted acidities with an equivalent number of sites providing bifunctionality. The strong acidic behavior highlights the effect of water molecules/cationic vacancies on the surface structure. Whereas the Lewis strength acidity progressively decreases with dehydration, Brønsted acidity remains strong even at 773 K.
K.-h. William Lau - One of the best experts on this subject based on the ideXlab platform.
-
Differential effects of bacterial toxins on mitogenic actions of sodium Fluoride and those of Aluminum Fluoride in human TE85 osteosarcoma cells.
Molecular and Cellular Biochemistry, 2001Co-Authors: Hideki Hashimoto, K.-h. William LauAbstract:This study compared the effects of cholera toxin (CTX) and pertussis toxin (PTX) on the actions of sodium Fluoride (NaF) and those of Aluminum Fluoride (AlF3) on cell proliferation and differentiation, as well as tyrosine phosphorylation level of MAP kinase (MAPK) in human bone cells. NaF and AlF3 each significantly stimulated the proliferation of human TE85 osteosarcoma cells, increased cellular alkaline phosphatase (ALP) activity, and increased MAPK tyrosine phosphorylation level. CTX completely blocked the bone cell anabolic activities of both NaF and AlF3. While PTX (2 ng/ml) inhibited the bone cell actions of NaF, it had no significant effect on those of AlF3. Both CTX and PTX completely blocked the stimulatory action of AlF3 on MAPK tyrosine phosphorylation, but neither toxin had an effect on the action of NaF on MAPK tyrosine phosphorylation. In conclusion, PTX and CTX had contrasting effects on the anabolic bone cell actions of NaF and AlF3 actions. These findings argue against the hypothesis that the osteogenic activity of NaF is mediated via the formation of AlF3 in human TE85 osteosarcoma cells.
-
Differential effects of bacterial toxins on mitogenic actions of sodium Fluoride and those of Aluminum Fluoride in human TE85 osteosarcoma cells.
Molecular and cellular biochemistry, 2001Co-Authors: Hideki Hashimoto, K.-h. William LauAbstract:This study compared the effects of cholera toxin (CTX) and pertussis toxin (PTX) on the actions of sodium Fluoride (NaF) and those of Aluminum Fluoride (AlF3) on cell proliferation and differentiation, as well as tyrosine phosphorylation level of mitogen activated protein kinase (MAPK) in human bone cells. NaF and AlF3 each significantly stimulated the proliferation of human TE85 osteosarcoma cells, increased cellular alkaline phosphatase (ALP) activity, and increased MAPK tyrosine phosphorylation level. CTX completely blocked the bone cell anabolic activities of both NaF and AlF3. While PTX (2 ng/ml) inhibited the bone cell actions of NaF, it had no significant effect on those of AlF3. Both CTX and PTX completely blocked the stimulatory action of AlF3 on MAPK tyrosine phosphorylation, but neither toxin had an effect on the action of NaF on MAPK tyrosine phosphorylation. In conclusion, PTX and CTX had contrasting effects on the anabolic bone cell actions of NaF and AlF3 actions. These findings argue against the hypothesis that the osteogenic activity of NaF is mediated via the formation of AlF3 in human TE85 osteosarcoma cells.
Mario Held - One of the best experts on this subject based on the ideXlab platform.
-
optical properties of uv transparent Aluminum oxide Aluminum Fluoride mixture films prepared by plasma ion assisted evaporation and ion beam sputtering
Optical Materials Express, 2014Co-Authors: Olaf Stenzel, Steffen Wilbrandt, Christian Franke, Norbert Kaiser, Andreas Tunnermann, Mathias Mende, Henrik Ehlers, Mario HeldAbstract:Electron beam evaporation (without and with plasma assistance) as well as ion beam sputtering are used to prepare optical mixture coatings for applications in the ultraviolet spectral range. It is demonstrated that intermixing Aluminum oxide/ Aluminum Fluoride materials by these physical vapor deposition techniques results in optical coatings with flexible refractive indices varying between 1.40 and 1.75 in the deep ultraviolet spectral region. At the same time, extinction coefficients vary between less than 1x10−4 and 2x10−3. For evaporated layers, at certain mixture ratios, mechanical stress appears to be close to zero.
-
Optical properties of UV-transparent Aluminum oxide / Aluminum Fluoride mixture films, prepared by plasma-ion assisted evaporation and ion beam sputtering
Optical Materials Express, 2014Co-Authors: Olaf Stenzel, Steffen Wilbrandt, Christian Franke, Norbert Kaiser, Andreas Tunnermann, Mathias Mende, Henrik Ehlers, Mario HeldAbstract:Electron beam evaporation (without and with plasma assistance) as well as ion beam sputtering are used to prepare optical mixture coatings for applications in the ultraviolet spectral range. It is demonstrated that intermixing Aluminum oxide/ Aluminum Fluoride materials by these physical vapor deposition techniques results in optical coatings with flexible refractive indices varying between 1.40 and 1.75 in the deep ultraviolet spectral region. At the same time, extinction coefficients vary between less than 1x10−4 and 2x10−3. For evaporated layers, at certain mixture ratios, mechanical stress appears to be close to zero.
Alexandre Vimont - One of the best experts on this subject based on the ideXlab platform.
-
Microwave Synthesis of an Aluminum Fluoride Hydrate with Cationic Vacancies: Structure, Thermal Stability, and Acidic Properties
Chemistry of Materials, 2008Co-Authors: Damien Dambournet, Alain Demourgues, Charlotte Martineau, Etienne Durand, Jérôme Majimel, Christophe Legein, Jean-yves Buzaré, Franck Fayon, Alexandre Vimont, Hervé LeclercAbstract:Aluminum Fluoride hydrate was synthesized by a microwave hydrothermal process. The structure derives from the ReO3 type structure, that is, the high temperature structure of α-AlF3. The cubic symmetry adopted by this compound arises from water molecules, stabilized as ligand surrounding Al3+ cations which induces cationic vacancies as revealed by Rietveld refinement. The following chemical formula Al0.82◻0.18F2.46(H2O)0.54 is supported by chemical analysis and TGA measurements. This represents the first example of Aluminum vacancy compound in the Al-based Fluorides chemistry. High field 27Al NMR spectroscopy enabled identification and quantification of the following species: AlF6 and AlF6−x(H2O)x with x = 1, 2, 3, and showed that vacancies are mainly surrounded by water molecules but also by a low content of Fluoride ions as also evidenced by 19F NMR. The hydrogen bonding network, which takes place in the vicinity of the cationic vacancies, was characterized by FTIR and 1H NMR spectroscopies. A 2:1 comple...
-
Microwave synthesis of an Aluminum Fluoride hydrate with cationic vacancies: structure, thermal stability, and acidic properties
Chemistry of Materials, 2008Co-Authors: Damien Dambournet, Alain Demourgues, Charlotte Martineau, Etienne Durand, Jérôme Majimel, Christophe Legein, Jean-yves Buzaré, Franck Fayon, Alexandre Vimont, Hervé LeclercAbstract:Aluminum Fluoride hydrate was synthesized by a microwave hydrothermal process. The structure derives from the ReO3 type structure, that is, the high temperature structure of α-AlF3. The cubic symmetry adopted by this compound arises from water molecules, stabilized as ligand surrounding Al3+ cations which induces cationic vacancies as revealed by Rietveld refinement. The following chemical formula Al0.82◻0.18F2.46(H2O)0.54 is supported by chemical analysis and TGA measurements. This represents the first example of Aluminum vacancy compound in the Al-based Fluorides chemistry. High field 27Al NMR spectroscopy enabled identification and quantification of the following species: AlF6 and AlF6−x(H2O)x with x = 1, 2, 3, and showed that vacancies are mainly surrounded by water molecules but also by a low content of Fluoride ions as also evidenced by 19F NMR. The hydrogen bonding network, which takes place in the vicinity of the cationic vacancies, was characterized by FTIR and 1H NMR spectroscopies. A 2:1 complex X···H−O−H···X where X is a proton acceptor, which is related to a shift of the νsym(OH) and νasym(OH), was detected. This complex appears to be stable up to 773 K. The phase transition into the rhombohedral form occurs at around 573 K, but at such a temperature a large amount of water molecules associated to cationic vacancies still remained thanks to the 2:1 complex. The acidic properties have been revealed by pyridine and CO probe molecules. At 573 K, the solid exhibits both strong Lewis and Brønsted acidities with an equivalent number of sites providing bifunctionality. The strong acidic behavior highlights the effect of water molecules/cationic vacancies on the surface structure. Whereas the Lewis strength acidity progressively decreases with dehydration, Brønsted acidity remains strong even at 773 K.
