Oxidation behavior of nano-Fe(0) particles in an anoxic environment was determined using differen... more Oxidation behavior of nano-Fe(0) particles in an anoxic environment was determined using different state-of-the-art analytical approaches, including high resolution transmission electron microscopy (HR-TEM) combined with energy filtered transmission electron microscopy (EFTEM), X-ray absorption spectroscopy (XAS), and magnetic measurements. Oxidation in controlled experiments was compared in standard double distilled (DD) water, DD water spiked with trichloroethene (TCE), and TCE contaminated site water. Using HR-TEM and EFTEM, we observed a surface oxide layer (∼3 nm) formed immediately after the particles were exposed to water. XAS analysis followed the dynamic change in total metallic iron concentration and iron oxide concentration for the experimental duration of 35 days. The metallic iron concentration in nano-Fe(0) particles exposed to water, was ∼40% after 35 days; in contrast, the samples containing TCE were reduced to ∼15% and even to nil in the case of TCE contaminated sit...
This paper presents a comparison between several methods dedicated to the interpretation of V K-e... more This paper presents a comparison between several methods dedicated to the interpretation of V K-edge X-ray absorption near-edge structure (XANES) features. V K-edge XANES spectra of several V-bearing standard compounds were measured in an effort to evaluate advantages and limits of each method. The standard compounds include natural minerals and synthetic compounds containing vanadium at various oxidation state (from +3 to +5) and in different symmetry (octahedral, tetrahedral, and square pyramidal). Correlations between normalized pre-edge peak area and its centroid position have been identified as the most reliable method for determining quantitative and accurate redox and symmetry information for vanadium. This methodology has been previously developed for the Fe K edge. It is also well adapted for the V K edge and is less influenced by the standard choice than other methods. This methodology was applied on an "environmental sample," i.e., a well-crystallized leached steel slag containing vanadium as traces. Micro-XANES measurements allowed elucidating the microdistribution of vanadium speciation in leached steel slag. The vanadium exhibits an important evolution from the unaltered to the altered phases. Its oxidation state increases from +3 to +5 together with the decrease of its symmetry (from octahedral to tetrahedral).
A simple aqueous synthesis yielded about 100 times more structurally well-organized single-walled... more A simple aqueous synthesis yielded about 100 times more structurally well-organized single-walled aluminogermanate nanotubes than previously reported "standard" procedures. The structure analyses using XRD, IRTF, TEM, and XAS were greatly facilitated by the high concentrations available, and they ascertained the imogolite-like structure of the nanotubes. Simplicity and yield of the synthesis protocol are likely to favor commercial applications of theses materials as well as simplified syntheses of other nanophases.
A multi-scale methodology was used to characterize the long-term behavior and chemical stability ... more A multi-scale methodology was used to characterize the long-term behavior and chemical stability of a CeO2-based nanocomposite used as UV filter in wood stains. ATR-FTIR and (13)C NMR demonstrated that the citrate coated chelates with Ce(IV) through its central carboxyl- and its α-hydroxyl- groups at the surface of the unaged nanocomposite. After 42 days under artificial daylight, the citrate completely disappeared and small amount of degradation products remained attached to the surface even after 112 days. Moreover, the release/desorption of the citrate layer led to a surface reorganization of the nano-sized CeO2 core observed by XANES (Ce L3-edge). Such a surface and structural transformation of the commercialized nanocomposite could have implications in term of fate, transport, and potential impacts towards the environment.
The synthesis protocol for Ge-imogolite (aluminogermanate nanotubes) consists of 3 main steps:
ba... more The synthesis protocol for Ge-imogolite (aluminogermanate nanotubes) consists of 3 main steps: base hydrolysis of a solution of aluminum and germanium monomers, stabilization of the suspension and heating at 95 1C. The successful synthesis of these nanotubes was found to be sensitive to the hydrolysis step. The impact of the hydrolysis ratio (from nOH/nAl = 0.5 to 3) on the final product structure was examined using a combination of characterization tools. Thus, key hydrolysis ratios were identified: nOH/nAl = 1.5 for the formation of nanotubes with structural defects, nOH/nAl = 2 for the synthesis of a well crystallized Ge imogolite and nOH/nAl 4 2.5 where nanotube formation is hindered. The capability of controlling the degree of the nanotube’s crystallinity opens up interesting opportunities in regard to new potential applications.
A new beamline for macromolecular crystallography has been constructed and is currently under com... more A new beamline for macromolecular crystallography has been constructed and is currently under commissioning. Its source is the high-power wiggler at the 2 GeV storage ring ELETIRA. The optics consists of a double-crystal monochromator in nondispersive configuration followed by a toroidal focusing mirror, and is designed to allow both diffraction experiments with monochromatized beam in the energy range 4-25 keV, and Laue experiments with white beam. The experimental station is based on an imaging plate area detector from MarResearch and a model 5020 Huber 4-circle diffractometer. To control the second apparatus, a plug-in board interface for a personal computer and a crystallographic package, CS, have been developed. 0 1995 American Institute of Physics.
Abstract The Super‐ESCA beamline has been designed for high resolution core level spectroscopy of... more Abstract The Super‐ESCA beamline has been designed for high resolution core level spectroscopy of adsorbates on single crystal surfaces using soft x‐ray synchrotron radiation. It receives the light from an 81 period undulator with 5.6 cm period and 4.5 m length in the ...
EXAFS spectroscopies extract structural information from a sample by analyzing its X-ray ab- sorp... more EXAFS spectroscopies extract structural information from a sample by analyzing its X-ray ab- sorption spectrum. They make it possible to determine the chemical environment of an element in terms of the number and type of its neighbors, inter-atomic distances and structural disor- ders. This determination is confined to a distance of 4 to 8 Å radius from the element. The
A high flux Photon Beam Position Monitor (PBPM) has been designed, realized and installed at ELET... more A high flux Photon Beam Position Monitor (PBPM) has been designed, realized and installed at ELETTRA for increasing the beam stability with local-bump-orbit feedbacks (LF), for beam diagnostic and for beam alignment. An electronic equipment has been designed and built for the calculation of the photon beam center positions and the beam angles both on the vertical and horizontal planes.
The structure of a trigonal crystal form of N-terminally truncated [des-(1-9)] bovine annexin IV,... more The structure of a trigonal crystal form of N-terminally truncated [des-(1-9)] bovine annexin IV, an annexin variant that exhibits the distinctive property of binding both phospholipids and carbohydrates in a Ca2+-dependent manner, has been determined at 3 A (0.3 nm) resolution -space group: R3; cell parameters: a=b=118.560 (8) A and c=82.233 (6) A-. The overall structure of annexin IV, crystallized in the absence of Ca2+ ions, is highly homologous to that of the other known members of the annexin family. The trimeric assembly in the trigonal crystals of annexin IV is quite similar to that found previously in non-isomorphous crystals of human, chicken and rat annexin V and to the subunit arrangement in half of the hexamer of hydra annexin XII. Moreover, it resembles that found in two-dimensional crystals of human annexin V bound to phospholipid monolayers. The propensity of several annexins to generate similar trimeric arrays supports the hypothesis that trimeric complexes of such a...
Engineered nanomaterials (ENMs) are used to enhance the properties of many manufactured products ... more Engineered nanomaterials (ENMs) are used to enhance the properties of many manufactured products and technologies. Increased use of ENMs will inevitably lead to their release into the environment. An important route of exposure is through the waste stream, where ENMs will enter wastewater treatment plants (WWTPs), undergo transformations, and be discharged with treated effluent or biosolids. To better understand the fate of a common ENM in WWTPs, experiments with laboratory-scale activated sludge reactors and pristine and citrate-functionalized CeO2 nanoparticles (NPs) were conducted. Greater than 90% of the CeO2 introduced was observed to associate with biosolids. This association was accompanied by reduction of the Ce(IV) NPs to Ce(III). After 5 weeks in the reactor, 44 ± 4% reduction was observed for the pristine NPs and 31 ± 3% for the citrate-functionalized NPs, illustrating surface functionality dependence. Thermodynamic arguments suggest that the likely Ce(III) phase generated would be Ce2S3. This study indicates that the majority of CeO2 NPs (>90% by mass) entering WWTPs will be associated with the solid phase, and a significant portion will be present as Ce(III). At maximum, 10% of the CeO2 will remain in the effluent and be discharged as a Ce(IV) phase, governed by cerianite (CeO2).
The HIV-1 protease is essential for replication of in- fective virus HIV, and therefore is an att... more The HIV-1 protease is essential for replication of in- fective virus HIV, and therefore is an attractive target for the design of specific inhibitors. In search for new inhibi- tors, substantial effort is devoted to understanding the na- ture of the inhibitor binding modes in the active site, using X-ray diffraction on crystals as the primary source of struc- tural
Oxidation behavior of nano-Fe(0) particles in an anoxic environment was determined using differen... more Oxidation behavior of nano-Fe(0) particles in an anoxic environment was determined using different state-of-the-art analytical approaches, including high resolution transmission electron microscopy (HR-TEM) combined with energy filtered transmission electron microscopy (EFTEM), X-ray absorption spectroscopy (XAS), and magnetic measurements. Oxidation in controlled experiments was compared in standard double distilled (DD) water, DD water spiked with trichloroethene (TCE), and TCE contaminated site water. Using HR-TEM and EFTEM, we observed a surface oxide layer (∼3 nm) formed immediately after the particles were exposed to water. XAS analysis followed the dynamic change in total metallic iron concentration and iron oxide concentration for the experimental duration of 35 days. The metallic iron concentration in nano-Fe(0) particles exposed to water, was ∼40% after 35 days; in contrast, the samples containing TCE were reduced to ∼15% and even to nil in the case of TCE contaminated sit...
This paper presents a comparison between several methods dedicated to the interpretation of V K-e... more This paper presents a comparison between several methods dedicated to the interpretation of V K-edge X-ray absorption near-edge structure (XANES) features. V K-edge XANES spectra of several V-bearing standard compounds were measured in an effort to evaluate advantages and limits of each method. The standard compounds include natural minerals and synthetic compounds containing vanadium at various oxidation state (from +3 to +5) and in different symmetry (octahedral, tetrahedral, and square pyramidal). Correlations between normalized pre-edge peak area and its centroid position have been identified as the most reliable method for determining quantitative and accurate redox and symmetry information for vanadium. This methodology has been previously developed for the Fe K edge. It is also well adapted for the V K edge and is less influenced by the standard choice than other methods. This methodology was applied on an "environmental sample," i.e., a well-crystallized leached steel slag containing vanadium as traces. Micro-XANES measurements allowed elucidating the microdistribution of vanadium speciation in leached steel slag. The vanadium exhibits an important evolution from the unaltered to the altered phases. Its oxidation state increases from +3 to +5 together with the decrease of its symmetry (from octahedral to tetrahedral).
A simple aqueous synthesis yielded about 100 times more structurally well-organized single-walled... more A simple aqueous synthesis yielded about 100 times more structurally well-organized single-walled aluminogermanate nanotubes than previously reported "standard" procedures. The structure analyses using XRD, IRTF, TEM, and XAS were greatly facilitated by the high concentrations available, and they ascertained the imogolite-like structure of the nanotubes. Simplicity and yield of the synthesis protocol are likely to favor commercial applications of theses materials as well as simplified syntheses of other nanophases.
A multi-scale methodology was used to characterize the long-term behavior and chemical stability ... more A multi-scale methodology was used to characterize the long-term behavior and chemical stability of a CeO2-based nanocomposite used as UV filter in wood stains. ATR-FTIR and (13)C NMR demonstrated that the citrate coated chelates with Ce(IV) through its central carboxyl- and its α-hydroxyl- groups at the surface of the unaged nanocomposite. After 42 days under artificial daylight, the citrate completely disappeared and small amount of degradation products remained attached to the surface even after 112 days. Moreover, the release/desorption of the citrate layer led to a surface reorganization of the nano-sized CeO2 core observed by XANES (Ce L3-edge). Such a surface and structural transformation of the commercialized nanocomposite could have implications in term of fate, transport, and potential impacts towards the environment.
The synthesis protocol for Ge-imogolite (aluminogermanate nanotubes) consists of 3 main steps:
ba... more The synthesis protocol for Ge-imogolite (aluminogermanate nanotubes) consists of 3 main steps: base hydrolysis of a solution of aluminum and germanium monomers, stabilization of the suspension and heating at 95 1C. The successful synthesis of these nanotubes was found to be sensitive to the hydrolysis step. The impact of the hydrolysis ratio (from nOH/nAl = 0.5 to 3) on the final product structure was examined using a combination of characterization tools. Thus, key hydrolysis ratios were identified: nOH/nAl = 1.5 for the formation of nanotubes with structural defects, nOH/nAl = 2 for the synthesis of a well crystallized Ge imogolite and nOH/nAl 4 2.5 where nanotube formation is hindered. The capability of controlling the degree of the nanotube’s crystallinity opens up interesting opportunities in regard to new potential applications.
A new beamline for macromolecular crystallography has been constructed and is currently under com... more A new beamline for macromolecular crystallography has been constructed and is currently under commissioning. Its source is the high-power wiggler at the 2 GeV storage ring ELETIRA. The optics consists of a double-crystal monochromator in nondispersive configuration followed by a toroidal focusing mirror, and is designed to allow both diffraction experiments with monochromatized beam in the energy range 4-25 keV, and Laue experiments with white beam. The experimental station is based on an imaging plate area detector from MarResearch and a model 5020 Huber 4-circle diffractometer. To control the second apparatus, a plug-in board interface for a personal computer and a crystallographic package, CS, have been developed. 0 1995 American Institute of Physics.
Abstract The Super‐ESCA beamline has been designed for high resolution core level spectroscopy of... more Abstract The Super‐ESCA beamline has been designed for high resolution core level spectroscopy of adsorbates on single crystal surfaces using soft x‐ray synchrotron radiation. It receives the light from an 81 period undulator with 5.6 cm period and 4.5 m length in the ...
EXAFS spectroscopies extract structural information from a sample by analyzing its X-ray ab- sorp... more EXAFS spectroscopies extract structural information from a sample by analyzing its X-ray ab- sorption spectrum. They make it possible to determine the chemical environment of an element in terms of the number and type of its neighbors, inter-atomic distances and structural disor- ders. This determination is confined to a distance of 4 to 8 Å radius from the element. The
A high flux Photon Beam Position Monitor (PBPM) has been designed, realized and installed at ELET... more A high flux Photon Beam Position Monitor (PBPM) has been designed, realized and installed at ELETTRA for increasing the beam stability with local-bump-orbit feedbacks (LF), for beam diagnostic and for beam alignment. An electronic equipment has been designed and built for the calculation of the photon beam center positions and the beam angles both on the vertical and horizontal planes.
The structure of a trigonal crystal form of N-terminally truncated [des-(1-9)] bovine annexin IV,... more The structure of a trigonal crystal form of N-terminally truncated [des-(1-9)] bovine annexin IV, an annexin variant that exhibits the distinctive property of binding both phospholipids and carbohydrates in a Ca2+-dependent manner, has been determined at 3 A (0.3 nm) resolution -space group: R3; cell parameters: a=b=118.560 (8) A and c=82.233 (6) A-. The overall structure of annexin IV, crystallized in the absence of Ca2+ ions, is highly homologous to that of the other known members of the annexin family. The trimeric assembly in the trigonal crystals of annexin IV is quite similar to that found previously in non-isomorphous crystals of human, chicken and rat annexin V and to the subunit arrangement in half of the hexamer of hydra annexin XII. Moreover, it resembles that found in two-dimensional crystals of human annexin V bound to phospholipid monolayers. The propensity of several annexins to generate similar trimeric arrays supports the hypothesis that trimeric complexes of such a...
Engineered nanomaterials (ENMs) are used to enhance the properties of many manufactured products ... more Engineered nanomaterials (ENMs) are used to enhance the properties of many manufactured products and technologies. Increased use of ENMs will inevitably lead to their release into the environment. An important route of exposure is through the waste stream, where ENMs will enter wastewater treatment plants (WWTPs), undergo transformations, and be discharged with treated effluent or biosolids. To better understand the fate of a common ENM in WWTPs, experiments with laboratory-scale activated sludge reactors and pristine and citrate-functionalized CeO2 nanoparticles (NPs) were conducted. Greater than 90% of the CeO2 introduced was observed to associate with biosolids. This association was accompanied by reduction of the Ce(IV) NPs to Ce(III). After 5 weeks in the reactor, 44 ± 4% reduction was observed for the pristine NPs and 31 ± 3% for the citrate-functionalized NPs, illustrating surface functionality dependence. Thermodynamic arguments suggest that the likely Ce(III) phase generated would be Ce2S3. This study indicates that the majority of CeO2 NPs (>90% by mass) entering WWTPs will be associated with the solid phase, and a significant portion will be present as Ce(III). At maximum, 10% of the CeO2 will remain in the effluent and be discharged as a Ce(IV) phase, governed by cerianite (CeO2).
The HIV-1 protease is essential for replication of in- fective virus HIV, and therefore is an att... more The HIV-1 protease is essential for replication of in- fective virus HIV, and therefore is an attractive target for the design of specific inhibitors. In search for new inhibi- tors, substantial effort is devoted to understanding the na- ture of the inhibitor binding modes in the active site, using X-ray diffraction on crystals as the primary source of struc- tural
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Papers by Luca Olivi
base hydrolysis of a solution of aluminum and germanium monomers, stabilization of the
suspension and heating at 95 1C. The successful synthesis of these nanotubes was found to be
sensitive to the hydrolysis step. The impact of the hydrolysis ratio (from nOH/nAl = 0.5 to 3) on
the final product structure was examined using a combination of characterization tools. Thus, key
hydrolysis ratios were identified: nOH/nAl = 1.5 for the formation of nanotubes with structural
defects, nOH/nAl = 2 for the synthesis of a well crystallized Ge imogolite and nOH/nAl 4 2.5
where nanotube formation is hindered. The capability of controlling the degree of the nanotube’s
crystallinity opens up interesting opportunities in regard to new potential applications.
base hydrolysis of a solution of aluminum and germanium monomers, stabilization of the
suspension and heating at 95 1C. The successful synthesis of these nanotubes was found to be
sensitive to the hydrolysis step. The impact of the hydrolysis ratio (from nOH/nAl = 0.5 to 3) on
the final product structure was examined using a combination of characterization tools. Thus, key
hydrolysis ratios were identified: nOH/nAl = 1.5 for the formation of nanotubes with structural
defects, nOH/nAl = 2 for the synthesis of a well crystallized Ge imogolite and nOH/nAl 4 2.5
where nanotube formation is hindered. The capability of controlling the degree of the nanotube’s
crystallinity opens up interesting opportunities in regard to new potential applications.