The development of innovative technologies to modify natural textiles holds an important impact f... more The development of innovative technologies to modify natural textiles holds an important impact for medical applications, including the prevention of contamination with microorganisms, particularly in the hospital environment. In our study, Fe and N co-doped TiO₂ nanoparticles have been obtained via the hydrothermal route, at moderate temperature, followed by short thermal annealing at 400 °C. These particles were used to impregnate polyester (PES) materials which have been evaluated for their morphology, photocatalytic performance, antimicrobial activity against bacterial reference strains, and in vitro biocompatibility on human skin fibroblasts. Microscopic examination and quantitative assays have been used to evaluate the cellular morphology and viability, cell membrane integrity, and inflammatory response. All treated PES materials specifically inhibited the growth of Gram-negative bacilli strains after 15 min of contact, being particularly active against Pseudomonas aeruginosa. PES fabrics treated with photocatalysts did not affect cell membrane integrity nor induce inflammatory processes, proving good biocompatibility. These results demonstrate that the treatment of PES materials with TiO₂-1% Fe-N particles could provide novel biocompatible fabrics with short term protection against microbial colonization, demonstrating their potential for the development of innovative textiles that could be used in biomedical applications for preventing patients' accidental contamination with microorganisms from the hospital environment.
Journal of Photochemistry and Photobiology A-chemistry, 2010
Two different types of mesoporous silicon-phosphate supports using different surfactants (a mixtu... more Two different types of mesoporous silicon-phosphate supports using different surfactants (a mixture of (CH3)3C13H27NBr with an organophosphorus coupling molecule (HO-PO(i-C3H7)2) and with a co-surfactant ((C2H5)3(C6H5)PCl), respectively) were synthesized. Trivalent europium (Eu) ions were immobilized via ion-exchange on these supports. The resulting materials were characterized using nitrogen adsorption isotherms at −196°C, thermogravimetric analysis, SEM, TEM, FT-IR, PXRD, CP/MAS.1H29Si and 31P NMR,
The crystal structure of Bi-2212 phase was studied by transmission electron microscopy. Two Bi-22... more The crystal structure of Bi-2212 phase was studied by transmission electron microscopy. Two Bi-2212 specimens with different Sr/Ca ratios have the same displacive incommensurate Bi modulation vector q---0.21 b*+ c* but exhibit different superconducting critical temperatures T c. Typical structural disordering (stacking faults, Bi-layer delineation effects, a-b plane misorientation) was found. * Corresponding author. Fax: 49 711 6861131. bution of Bi on the Sr sites should be taken into consideration . Since the Bi-2212 phase has a large stability range in the phase diagram [13], it would be expected that the Sr/Ca ratio influences the structural modulation of the Bi-2212 phase. It would be also interesting to study the correlation between the substitution of Bi by Pb and the alteration of modulation vector in the HTSL Bi-2212 phase, because the largest distortions are found in the Bi-O double layers .
In this paper, we present the results of structural and photoluminescence (PL) studies on vertica... more In this paper, we present the results of structural and photoluminescence (PL) studies on vertically aligned, 20-period In 0.33 Ga 0.67 As/GaAs quantum dot stacks, grown by molecular beam epitaxy (MBE). Two different In 0.33 Ga 0.67 As/GaAs quantum dot stacks were compared. In one ...
In Pb(ZrxTi1−x)O3 solid solutions corresponding to the morphotropic phase boundary. the molar vol... more In Pb(ZrxTi1−x)O3 solid solutions corresponding to the morphotropic phase boundary. the molar volume fraction xVCR+ (1-x)VCT and porosity per volume unit P exhibits a similar variation trend on sintering temperature, reaching simultaneously a minimum for 1140°C. This specific behaviour is explained by a simple mechanism of pore closure induced by thermal lattice expansion. evaluated on the basis of FT and FR unit cell volume variation. previously measured by X-ray diffraction.
Carbon nitride thin films (CN x ) were produced by UV laser (ArF, l=193 nm) induced chemical vapo... more Carbon nitride thin films (CN x ) were produced by UV laser (ArF, l=193 nm) induced chemical vapour deposition from C 2 H 2 /NH 3 mixtures, on Si and TiN/Si substrates. The surface and bulk composition of the deposited layers were investigated by X-ray photoelectron spectrometry ( XPS) and elastic recoil detection analysis ( ERDA), respectively. Nitrogen was found to be singly and doubly bonded to carbon, as revealed by FTIR spectrometry. Specific morphology of the films was evidenced by transmission electron microscopy (TEM ), while selected area electron diffraction (SAED) confirms the presence of nano-crystallites in the layers. The calculated d-lattice spacings fit rather well with theoretical and experimental data for a-and b-C 3 N 4 .
ABSTRACT We present evidence that the microstructure of the metastable fluorite phase Pb2(Zr,Ti)2... more ABSTRACT We present evidence that the microstructure of the metastable fluorite phase Pb2(Zr,Ti)2O6, which forms during the pyrolysis treatment of sol-gel PZT layers by homogeneous nucleation throughout the film, has a larger impact on orientation selection than has previously been realized. Elaborate TEM studies demonstrate that by varying the pyrolysis time, temperature and duration, the crystallinity of the transient fluorite phase can be greatly influenced. Pyrolysis at 350°C leads to the formation of a well crystallized fluorite phase with a cubic structure (Fd3m space group) and a= 10.5-10.6 Å. Rapid crystallization of the transient fluorite phase is attributed to the low oxygen partial pressure conditions, prevailing during burnoff of acetate groups originating from the lead starting compound. A possible connection between the fluorite formation kinetics and orientation selection in the layers is discussed.
ABSTRACT Rare-earth free (RE-free) exchange coupling nanocomposite magnets are intensively studie... more ABSTRACT Rare-earth free (RE-free) exchange coupling nanocomposite magnets are intensively studied nowadays due to their potential use in applications demanding stable high-temperature operation and corrosion resistance. In this respect, the FePt alloy system is one of the most actively addressed potential permanent magnet solutions. In FePt alloys, promising magnetic features arise from the co-existence of hard magnetic L10 FePt and soft magnetic L12 Fe3Pt phases emerged from the same metastable precursor. The present work deals with an in-situ temperature-resolved synchrotron radiation study of the thermal stability, thermal expansion and microstructure evolution in exchange-coupled FePtAgB alloys. The as-cast microstructural state as well as the optimized magnetic behavior are given as reference and correlated to the observed microstructural evolution with temperature. The melt-spun Fe48Pt28Ag6B18 alloy ribbons were examined in situ by synchrotron X-ray powder diffraction from ambient temperature up to 600 °C. The FePt–Fe3Pt exchange-coupled microstructure achieved by rapid solidification is not significantly altered during the high temperature exposure. The thermal expansion of the FePt L10 unit cell has been found to be strongly anisotropic, being essentially an in-plane expansion which may be seen as an anisotropic invar effect. For the FePt L10 phase, a significant deviation from linear thermal expansion is observed at the Curie temperature TC = 477 °C. This non-linear behavior above TC is tentatively linked to a diffusion/segregation mechanism of Ag. The promising hard magnetic properties as well as the direct formation of the L10 phase from the as-cast state are directly related to the presence of Ag in the intergranular regions.
The effect of electron irradiation having the energy of 75, 100, and 200 keV on structural modifi... more The effect of electron irradiation having the energy of 75, 100, and 200 keV on structural modifications of Bi-2212 superconducting samples has been studied. For the last energy, the irradiation time from zero to 150 min was used. At a constant energy of the electrons, the observed phenomena consist in the disappearance of the incommensurate unidimensional modulation, in the decreasing of spots' intensity and their elongation along the equivalent crystallographic axis a, and even spot splitting with the occurrence of double extra spots, with the increase of the irradiation time.
TiO 2 nanopowders, doped with Fe 3? and Eu 3? were obtained by high-energy ball milling and their... more TiO 2 nanopowders, doped with Fe 3? and Eu 3? were obtained by high-energy ball milling and their physical properties were investigated as a function of the doping content and ball milling time. A noticeable red shift and high photoactivity in the degradation and catalytic oxidation reactions of styrene and phenol were found for all doped specimens.
The influence of the sintering time and pressing force on the pellets on the occurrence and morph... more The influence of the sintering time and pressing force on the pellets on the occurrence and morphology of the superconducting phases in BSCCO system were studied. Scanning electron microscopy, X-ray microanalysis and X-ray diffraction were used to identify the phases and their morphologies. The 2223 crystals had a plate-like morphology and 2212, a polyhedral-like one. The optimum parameters in order to obtain a majority of 2223 phase were identified: i.e. a longer sintering time and medium pressing force. C 2000 Kluwer Academic Publishers
The development of innovative technologies to modify natural textiles holds an important impact f... more The development of innovative technologies to modify natural textiles holds an important impact for medical applications, including the prevention of contamination with microorganisms, particularly in the hospital environment. In our study, Fe and N co-doped TiO₂ nanoparticles have been obtained via the hydrothermal route, at moderate temperature, followed by short thermal annealing at 400 °C. These particles were used to impregnate polyester (PES) materials which have been evaluated for their morphology, photocatalytic performance, antimicrobial activity against bacterial reference strains, and in vitro biocompatibility on human skin fibroblasts. Microscopic examination and quantitative assays have been used to evaluate the cellular morphology and viability, cell membrane integrity, and inflammatory response. All treated PES materials specifically inhibited the growth of Gram-negative bacilli strains after 15 min of contact, being particularly active against Pseudomonas aeruginosa. PES fabrics treated with photocatalysts did not affect cell membrane integrity nor induce inflammatory processes, proving good biocompatibility. These results demonstrate that the treatment of PES materials with TiO₂-1% Fe-N particles could provide novel biocompatible fabrics with short term protection against microbial colonization, demonstrating their potential for the development of innovative textiles that could be used in biomedical applications for preventing patients' accidental contamination with microorganisms from the hospital environment.
Journal of Photochemistry and Photobiology A-chemistry, 2010
Two different types of mesoporous silicon-phosphate supports using different surfactants (a mixtu... more Two different types of mesoporous silicon-phosphate supports using different surfactants (a mixture of (CH3)3C13H27NBr with an organophosphorus coupling molecule (HO-PO(i-C3H7)2) and with a co-surfactant ((C2H5)3(C6H5)PCl), respectively) were synthesized. Trivalent europium (Eu) ions were immobilized via ion-exchange on these supports. The resulting materials were characterized using nitrogen adsorption isotherms at −196°C, thermogravimetric analysis, SEM, TEM, FT-IR, PXRD, CP/MAS.1H29Si and 31P NMR,
The crystal structure of Bi-2212 phase was studied by transmission electron microscopy. Two Bi-22... more The crystal structure of Bi-2212 phase was studied by transmission electron microscopy. Two Bi-2212 specimens with different Sr/Ca ratios have the same displacive incommensurate Bi modulation vector q---0.21 b*+ c* but exhibit different superconducting critical temperatures T c. Typical structural disordering (stacking faults, Bi-layer delineation effects, a-b plane misorientation) was found. * Corresponding author. Fax: 49 711 6861131. bution of Bi on the Sr sites should be taken into consideration . Since the Bi-2212 phase has a large stability range in the phase diagram [13], it would be expected that the Sr/Ca ratio influences the structural modulation of the Bi-2212 phase. It would be also interesting to study the correlation between the substitution of Bi by Pb and the alteration of modulation vector in the HTSL Bi-2212 phase, because the largest distortions are found in the Bi-O double layers .
In this paper, we present the results of structural and photoluminescence (PL) studies on vertica... more In this paper, we present the results of structural and photoluminescence (PL) studies on vertically aligned, 20-period In 0.33 Ga 0.67 As/GaAs quantum dot stacks, grown by molecular beam epitaxy (MBE). Two different In 0.33 Ga 0.67 As/GaAs quantum dot stacks were compared. In one ...
In Pb(ZrxTi1−x)O3 solid solutions corresponding to the morphotropic phase boundary. the molar vol... more In Pb(ZrxTi1−x)O3 solid solutions corresponding to the morphotropic phase boundary. the molar volume fraction xVCR+ (1-x)VCT and porosity per volume unit P exhibits a similar variation trend on sintering temperature, reaching simultaneously a minimum for 1140°C. This specific behaviour is explained by a simple mechanism of pore closure induced by thermal lattice expansion. evaluated on the basis of FT and FR unit cell volume variation. previously measured by X-ray diffraction.
Carbon nitride thin films (CN x ) were produced by UV laser (ArF, l=193 nm) induced chemical vapo... more Carbon nitride thin films (CN x ) were produced by UV laser (ArF, l=193 nm) induced chemical vapour deposition from C 2 H 2 /NH 3 mixtures, on Si and TiN/Si substrates. The surface and bulk composition of the deposited layers were investigated by X-ray photoelectron spectrometry ( XPS) and elastic recoil detection analysis ( ERDA), respectively. Nitrogen was found to be singly and doubly bonded to carbon, as revealed by FTIR spectrometry. Specific morphology of the films was evidenced by transmission electron microscopy (TEM ), while selected area electron diffraction (SAED) confirms the presence of nano-crystallites in the layers. The calculated d-lattice spacings fit rather well with theoretical and experimental data for a-and b-C 3 N 4 .
ABSTRACT We present evidence that the microstructure of the metastable fluorite phase Pb2(Zr,Ti)2... more ABSTRACT We present evidence that the microstructure of the metastable fluorite phase Pb2(Zr,Ti)2O6, which forms during the pyrolysis treatment of sol-gel PZT layers by homogeneous nucleation throughout the film, has a larger impact on orientation selection than has previously been realized. Elaborate TEM studies demonstrate that by varying the pyrolysis time, temperature and duration, the crystallinity of the transient fluorite phase can be greatly influenced. Pyrolysis at 350°C leads to the formation of a well crystallized fluorite phase with a cubic structure (Fd3m space group) and a= 10.5-10.6 Å. Rapid crystallization of the transient fluorite phase is attributed to the low oxygen partial pressure conditions, prevailing during burnoff of acetate groups originating from the lead starting compound. A possible connection between the fluorite formation kinetics and orientation selection in the layers is discussed.
ABSTRACT Rare-earth free (RE-free) exchange coupling nanocomposite magnets are intensively studie... more ABSTRACT Rare-earth free (RE-free) exchange coupling nanocomposite magnets are intensively studied nowadays due to their potential use in applications demanding stable high-temperature operation and corrosion resistance. In this respect, the FePt alloy system is one of the most actively addressed potential permanent magnet solutions. In FePt alloys, promising magnetic features arise from the co-existence of hard magnetic L10 FePt and soft magnetic L12 Fe3Pt phases emerged from the same metastable precursor. The present work deals with an in-situ temperature-resolved synchrotron radiation study of the thermal stability, thermal expansion and microstructure evolution in exchange-coupled FePtAgB alloys. The as-cast microstructural state as well as the optimized magnetic behavior are given as reference and correlated to the observed microstructural evolution with temperature. The melt-spun Fe48Pt28Ag6B18 alloy ribbons were examined in situ by synchrotron X-ray powder diffraction from ambient temperature up to 600 °C. The FePt–Fe3Pt exchange-coupled microstructure achieved by rapid solidification is not significantly altered during the high temperature exposure. The thermal expansion of the FePt L10 unit cell has been found to be strongly anisotropic, being essentially an in-plane expansion which may be seen as an anisotropic invar effect. For the FePt L10 phase, a significant deviation from linear thermal expansion is observed at the Curie temperature TC = 477 °C. This non-linear behavior above TC is tentatively linked to a diffusion/segregation mechanism of Ag. The promising hard magnetic properties as well as the direct formation of the L10 phase from the as-cast state are directly related to the presence of Ag in the intergranular regions.
The effect of electron irradiation having the energy of 75, 100, and 200 keV on structural modifi... more The effect of electron irradiation having the energy of 75, 100, and 200 keV on structural modifications of Bi-2212 superconducting samples has been studied. For the last energy, the irradiation time from zero to 150 min was used. At a constant energy of the electrons, the observed phenomena consist in the disappearance of the incommensurate unidimensional modulation, in the decreasing of spots' intensity and their elongation along the equivalent crystallographic axis a, and even spot splitting with the occurrence of double extra spots, with the increase of the irradiation time.
TiO 2 nanopowders, doped with Fe 3? and Eu 3? were obtained by high-energy ball milling and their... more TiO 2 nanopowders, doped with Fe 3? and Eu 3? were obtained by high-energy ball milling and their physical properties were investigated as a function of the doping content and ball milling time. A noticeable red shift and high photoactivity in the degradation and catalytic oxidation reactions of styrene and phenol were found for all doped specimens.
The influence of the sintering time and pressing force on the pellets on the occurrence and morph... more The influence of the sintering time and pressing force on the pellets on the occurrence and morphology of the superconducting phases in BSCCO system were studied. Scanning electron microscopy, X-ray microanalysis and X-ray diffraction were used to identify the phases and their morphologies. The 2223 crystals had a plate-like morphology and 2212, a polyhedral-like one. The optimum parameters in order to obtain a majority of 2223 phase were identified: i.e. a longer sintering time and medium pressing force. C 2000 Kluwer Academic Publishers
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