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146 results on '"Casula, Maria F."'

3. Cation distribution in ferrite nanoparticles and thin films using X-ray absorption spectroscopy methods

Author

Sing, Jitendra Pal, Chae, Keun Hwa, Srivastava, Ramesh Chandra, Caltun, Ovidiu Florin, Carta, Daniela, Mountjoy, Gavin, Casula, Maria F., Loche, Danilo, Corrias, Anna, Sing, Jitendra Pal, Chae, Keun Hwa, Srivastava, Ramesh Chandra, Caltun, Ovidiu Florin, Carta, Daniela, Mountjoy, Gavin, Casula, Maria F., Loche, Danilo, and Corrias, Anna

Abstract

Cation distribution in spinel ferrites strongly influences their magnetic and catalytic properties. Cation distribution depends on the electronic configuration and valence of ions, but rearrangement can occur at the nanometric scale. The optimization of the technological applications of ferrites is therefore reliant on detailed information on the distribution of cations between the octahedral and tetrahedral sites of the spinel structure. To this end, X-ray absorption spectroscopy has proven to be a very powerful method due to the ability to study selectively and independently the coordination environment of two cations present in ferrites. The information provided is reviewed in this chapter.

Published
2023

12. Evidence of a cubic iron sub-lattice in t-CuFe2O4 demonstrated by X-ray Absorption Fine Structure

Author

Caddeo, Francesco, Loche, Danilo, Casula, Maria F., and Corrias, Anna

Subjects
lcsh:R, lcsh:Medicine, lcsh:Q, lcsh:Science, Article
Abstract

Copper ferrite, belonging to the wide and technologically relevant class of spinel ferrites, was grown in the form of t-CuFe2O4 nanocrystals within a porous matrix of silica in the form of either an aerogel or a xerogel, and compared to a bulk sample. Extended X-ray absorption fine structure (EXAFS) spectroscopy revealed the presence of two different sub-lattices within the crystal structure of t-CuFe2O4, one tetragonal and one cubic, defined by the Cu2+ and Fe3+ ions respectively. Our investigation provides evidence that the Jahn-Teller distortion, which occurs on the Cu2+ ions located in octahedral sites, does not affect the coordination geometry of the Fe3+ ions, regardless of their location in octahedral or tetrahedral sites.

Published
2018

13. The concept of delayed nucleation in nanocrystal growth demonstrated for the case of iron oxide nanodisks

Author

Casula, Maria F., Jun, Young-Wook, Zaziski, David J., Chan, Emory M., Corrias, Anna, and Alivisatos, A.Paul

Subjects
Iron oxides -- Chemical properties, Iron oxides -- Structure, Nucleation -- Analysis, Oxidizing agents -- Chemical properties, Chemistry
Abstract

The size control, anisotropic shape evolution, and crystallographic phase transition of monodisperse iron oxide colloidal nanocrystals are being studied by examining the iron oxide nanocrystal growth through a thermal reaction of iron pentacarbonyl and an oxidizer. The results show that the features of the synthesis are directly related to the occurrence of the delayed nucleation process.

Published
2006

15. List of contributors

Author

Agarwal, Shilpi, Ahmed, Faheem, Arora, Shefali, Aulakh, Jaspreet Singh, Bhardwaj, Richa, Borhan, Adrian Iulian, Brajpuriya, Ranjeet Kumar, Bulai, Georgiana, Caltun, Ovidiu Florin, Carta, Daniela, Casula, Maria F., Chae, Keun Hwa, Chagas, Edson Ferreira, Chahal, Surjeet, Chand, Prakash, Chauhan, Vishnu, Corrias, Anna, Datt, Gopal, Devarani Devi, Ksh., Devi, Seema, Dhyani, Archana, Dhyani, Reena, Dumitru, Ioan, Dwivedi, G.D., Espinosa, A., Ferreira, Edson Silva, Fleischer, Karsten, Ganjali, Mohammad Reza, Gherc, Daniel, Gómez-Cerezo, D., Goyal, Navdeep, Goyat, Manjeet Singh, Gupta, Deepika, Gupta, Tejendra K., Hannachi, Essia, Hashim, Mohd, Hoskins, Clare, Husain, Sajid, Iordan, Alexandra Raluca, Jayasimhadri, M., Jogi, Jayant, Joshi, Amit, Joshi, Deepika P., Joshi, S.K., Kandasami, Asokan, Kaur, Baljeet, Khichi, Abhimanyu Singh, Koo, B.H., Koprivica, Branko, Kumar, Akshay, Kumar, Ankit, Kumar, Ashok, Kumar, Hemaunt, Kumar, Manish, Kumar, Parmod, Kumar, Promod, Kumar, Rajesh, Kumar, Shalendra, Kumari, Kavita, Latwal, Mamta, Lim, Weon C., Loche, Danilo, López-Méndez, R., Lozano-Pedraza, C., Malaie, Keyvan, Manshian, Bella, Mathpal, Mohan Chandra, Maze, Jero, Mountjoy, Gavin, Mudoi, Manash Protim, Mullarkey, Daragh, Nandy, Subhajit, Nongjai, Razia, Oluwasamni, Adeolu, Ortega, Daniel, Ortega-Juliá, J., Paidi, Vinod K., Palamaru, Mircea Nicolae, Panday, Ganesh, Pavithra, S., Prigent, Christophe, Rani, Sunita, Ravi, G., Reddy, M.V., Sakunthala, A., Santana-Otero, Antonio, Sanz-de Diego, E., Shankar, S., Sharma, Aditya, Sharma, Ram K., Sharmin, Sonia, Shvets, Igor V., Singh, Jitendra Pal, Singh, Lalit, Singh, Varsha, Singhal, S.K., Singhal, Shailey, Slimani, Yassine, Soenen, Stefaan, Soler, Maria A.G., Srivastava, Ramesh Chandra, Steydly, Sébastien, Suman, Swart, H.C., Teran, F.J., Thakur, O.P., Trandafir, Elena Vasilica, Trassinelli, Martino, Vashisht, Garima, Vernhet, Dominique, Vij, Ankush, and Yuvakumar, R.

Published
2023
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16. X-ray absorption spectroscopy study of FeCo-SiO2 nanocomposites prepared by the sol-gel method

Author

Corrias, Anna, Casula, Maria F., Ennas, Guido, Marras, Sergio, Navarra, Gabriele, and Mountjoy, Gavin

Subjects
Iron compounds -- Chemical properties, Chemicals, plastics and rubber industries
Abstract

Extended X-ray absorption fine structure and X-ray absorption near edge structure techniques are used to study in detail the formation of FeCo alloy nanoparticles in a silica matrix during their sol-gel preparation. The final nanocomposites contain bcc FeCo nanoparticles, which are sometimes accompanied by fcc Co depending both on the intermediate products and on the porous structure of the samples.

Published
2003

21. The Role of Ligands in the Chemical Synthesis and Applications of Inorganic Nanoparticles

Author

Heuer-Jungemann, Amelie, primary, Feliu, Neus, additional, Bakaimi, Ioanna, additional, Hamaly, Majd, additional, Alkilany, Alaaldin, additional, Chakraborty, Indranath, additional, Masood, Atif, additional, Casula, Maria F., additional, Kostopoulou, Athanasia, additional, Oh, Eunkeu, additional, Susumu, Kimihiro, additional, Stewart, Michael H., additional, Medintz, Igor L., additional, Stratakis, Emmanuel, additional, Parak, Wolfgang J., additional, and Kanaras, Antonios G., additional

Published
2019
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24. Catalytic chemical vapour deposition on MFe2O4-SiO2 (M = Co, Mn, Ni) nanocomposite aerogel catalysts for the production of multi walled carbon nanotubes

Author

Loche, Danilo, Casula, Maria F, Corrias, Anna, Marras, Claudia, Gozzi, Daniele, and Latini, Alessandro

Subjects
chemistry (all), ferrite, aerogels, bioengineering, condensed matter physics, carbon nanotubes, nanocomposites, biomedical engineering, materials science (all), QD156
Abstract

Highly porous MFe2O4-SiO2 (M = Co, Mn, Ni) nanocomposite aerogels were tested for the first time as catalysts for multi walled carbon nanotubes production by Catalytic Chemical Vapour Deposition. Structural and textural characterization points out that the catalysts are made out of nanocomposites where nanocrystalline ferrite phases with controlled composition and size in the range 9-13 nm are finely dispersed into the highly porous silica support. Remarkably, CoFe2O4-SiO2 and MnFe2O4-SiO2 catalysts have shown poor catalytic activity, whereas NiFe2O4-SiO2 catalyst has given rise to good quality nanotubes with high yields at deposition temperatures in the range 500-650 °C. The different catalytic behaviour of the mixed ferrite-silica aerogels as a function of the bivalent metal (M = Co, Mn, Ni) can been ascribed to how easily the nanophase can be reduced. In particular, it was demonstrated that the most active NiFe2O4 nanoparticles undergo an in-situ reduction process during the Catalytic Chemical Vapour Deposition reaction, forming a NiFe alloy phase that is responsible for promoting the multi walled carbon nanotubes growth.

Published
2016

25. An X-ray absorption spectroscopy investigation of the formation of FeCo alloy nanoparticles in Al2O3 xerogel and aerogel matrixes

Author

Corrias, Anna, Navarra, Gabriele, Casula, Maria F., Marras, Sergio, and Mountjoy, Gavin

Subjects
Aluminum oxide -- Spectra, Aluminum oxide -- Structure, Aerogels -- Spectra, Aerogels -- Structure, X-ray spectroscopy -- Analysis, Chemicals, plastics and rubber industries
Abstract

Extended X-ray absorption fine structure and x-ray absorption near-edge structure techniques are used to study in detail the structural characteristics of FeCo-Al2O3 nanocomposite xerogels and aerogels. The investigation of the xerogels and aerogels calcined at increasing temperature indicates that Fe(III) and ions are present and they are located in the tetrahedral sites of the spinel is more ordered in the aerogel sample than the xerogel sample.

Published
2005

27. Surfactant-assisted elimination of a high energy facet as a means of controlling the shapes of TiO2 nanocrystals

Author

Jun, Young-wook, Casula, Maria F., Sim, Jae-Hwan, Kim, Sang Youl, and Cheon, Jinwoo ; Alivisatos, A. Paul

Subjects
Titanium dioxide -- Research, Titanium dioxide -- Structure, Chemistry
Abstract

A detailed study of the surfactant-mediated shape evolution of titanium dioxide anatase nanocrystals in nonaqueous media is provided. Their shape control are carried out by modulation of surface energies of the different crystallographic faces through surface selective surfactant use.

Published
2003

29. Uncommon Optical Properties and Silver‐Responsive Turn‐Off/On Luminescence in a PtII Heteroleptic Dithiolene Complex.

Author

Attar, Salahuddin S., Artizzu, Flavia, Marchiò, Luciano, Espa, Davide, Pilia, Luca, Casula, Maria F., Serpe, Angela, Pizzotti, Maddalena, Orbelli‐Biroli, Alessio, and Deplano, Paola

Subjects
OPTICAL properties, LUMINESCENCE, HETEROLEPTIC compounds, POLARIZABILITY (Electricity), OXIDATION-reduction reaction
Abstract

Abstract: Complex [Pt(iPr2pipdt)(Quinoxdt)] (iPr2pipdt=1,4‐diisopropyl‐piperazine‐2,3‐dithione; Quinoxdt=[1,4]dithiino[2,3‐b]quinoxaline‐2,3‐dithiolate) exhibits a remarkable green emission at 570 nm (room temperature), which is above the lowest excited state. The complex is characterized by negative solvatochromism as well as a high second‐order polarizability. Addition of AgI ions induces 1) hypsochromic shift of the lowest frequencies and 2) reversible quenching of luminescence. The corresponding Ni and Pd complexes have also been prepared and investigated to assist interpretation of optical properties within the triad. Computational studies based on DFT and time‐dependent DFT highlight the electronic properties of [Pt(iPr2pipdt)(Quinoxdt)]. The preferential site of interaction between the Pt complex and incoming AgI is evidenced by the shape of the Fukui functions, pointing to the thiolic sulfur and platinum atoms as the most reactive sites towards a soft cation. Calculated optical properties are in agreement with experimental findings. This study sheds light on the structure–property relationship for this class of compounds. [ABSTRACT FROM AUTHOR]

Published
2018
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32. Adsorption of Lysozyme on Hyaluronic Acid Functionalized SBA-15 Mesoporous Silica: A Possible Bioadhesive Depot System

Author

Medda, Luca, Casula, Maria F, Monduzzi, Maura, Salis, Andrea, Medda, Luca, Casula, Maria F, Monduzzi, Maura, and Salis, Andrea

Abstract

Silica-based ordered mesoporous materials are very attractive matrices to prepare smart depot systems for several kinds of therapeutic agents. This work focuses on the well-known SBA-15 mesoporous silica and lysozyme, an antimicrobial protein. In order to improve the bioadhesion properties of SBA-15 particles, the effect of hyaluronic acid (HA) functionalization on lysozyme adsorption was investigated. SBA-15 samples having high (H-SBA) and low (L-SBA) levels of functionalization were analyzed during the three steps of the preparations: (1) introduction of the NH2 groups to obtain the SBA-NH2 samples; (2) functionalization with HA to obtain the SBA-HA matrices; (3) adsorption of lysozyme. All silica matrices were characterized through N2-adsorption/desorption isotherms, small-angle X-ray scattering, transmission electron microscopy, thermogravimetric analysis, and Fourier transform infrared spectroscopy. The whole of the experimental data suggests that a high level of functionalization of the silica surface allows for a negligible lysozyme adsorption mainly due to unfavorable electrostatic interactions (H-SBA-NH2) or steric hindrance (H-SBA-HA). A low degree of functionalization of the silica surface brings about a very good performance toward lysozyme adsorption, being 71% (L-SBA-NH2) and 63% (L-SBA-HA) respectively, compared to that observed for original SBA-15. Finally, two different kinetic models - pseudo-second order and a intraparticle diffusion - were compared to fit lysozyme adsorption data, the latter being more reliable than the former.

Published
2014

37. Exfoliated Graphene into Highly Ordered Mesoporous Titania Films: Highly Performing Nanocomposites from Integrated Processing

Author

Malfatti, Luca, primary, Falcaro, Paolo, additional, Pinna, Alessandra, additional, Lasio, Barbara, additional, Casula, Maria F., additional, Loche, Danilo, additional, Falqui, Andrea, additional, Marmiroli, Benedetta, additional, Amenitsch, Heinz, additional, Sanna, Roberta, additional, Mariani, Alberto, additional, and Innocenzi, Plinio, additional

Published
2013
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39. Biomedical tools based on magnetic nanoparticles

Author

Saba, Anna R., primary, Castillo, Paula M., additional, Fantechi, Elvira, additional, Sangregorio, Claudio, additional, Lascialfari, Alessandro, additional, Sbarbati, Andrea, additional, Casu, Alberto, additional, Falqui, Andrea, additional, and Casula, Maria F., additional

Published
2013
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41. Biological applications of magnetic nanoparticles

Author

Colombo, Miriam, primary, Carregal-Romero, Susana, additional, Casula, Maria F., additional, Gutiérrez, Lucía, additional, Morales, María P., additional, Böhm, Ingrid B., additional, Heverhagen, Johannes T., additional, Prosperi, Davide, additional, and Parak, Wolfgang. J., additional

Published
2012
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