References of "Costa, Carlos A. R"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailUnraveling the Role of Sn Segregation in the Electronic Transport of Polycrystalline Hematite: Raising the Electronic Conductivity by Lowering the Grain-Boundary Blocking Effect
Soares, Mario R. S.; Costa, Carlos A. R.; Martin Lanzoni, Evandro UL et al

in Advanced Electronic Materials (2019), 0(0), 1900065

This paper describes the role of SnO2 in the electronic transport of polycrystalline hematite (α-Fe2O3). The proper sintering process allows for freezing of a state of electronic defects, in which the ... [more ▼]

This paper describes the role of SnO2 in the electronic transport of polycrystalline hematite (α-Fe2O3). The proper sintering process allows for freezing of a state of electronic defects, in which the electrical properties of hematite are controlled by the grain boundary and Sn segregation. Impedance spectroscopy and dc conductivity measurements show that current flows through preferential pathways associated with Sn segregation that occurs at the grain boundary, leading to a decrease in grain-boundary resistance. Atomic force microscopy and electric force microscopy measurements confirm the results of the impedance analysis. The identification of preferential grain boundaries for electrical conductivity may have a direct influence on the light-induced water-splitting performance of the hematite photoanode. [less ▲]

Detailed reference viewed: 31 (0 UL)
Full Text
Peer Reviewed
See detailPredicting Ligand-Free Cell Attachment on Next-Generation Cellulose–Chitosan Hydrogels
Johns, Marcus A.; Bae, Yongho; Guimarães, Francisco E. G. et al

in ACS Omega (2018), 3(1), 937--945

There is a growing appreciation that engineered biointerfaces can regulate cell behaviors, or functions. Most systems aim to mimic the cell-friendly extracellular matrix environment and incorporate ... [more ▼]

There is a growing appreciation that engineered biointerfaces can regulate cell behaviors, or functions. Most systems aim to mimic the cell-friendly extracellular matrix environment and incorporate protein ligands; however, the understanding of how a ligand-free system can achieve this is limited. Cell scaffold materials comprised of interfused chitosan–cellulose hydrogels promote cell attachment in ligand-free systems, and we demonstrate the role of cellulose molecular weight, MW, and chitosan content and MW in controlling material properties and thus regulating cell attachment. Semi-interpenetrating network (SIPN) gels, generated from cellulose/ionic liquid/cosolvent solutions, using chitosan solutions as phase inversion solvents, were stable and obviated the need for chemical coupling. Interface properties, including surface zeta-potential, dielectric constant, surface roughness, and shear modulus, were modified by varying the chitosan degree of polymerization and solution concentration, as well as the source of cellulose, creating a family of cellulose–chitosan SIPN materials. These features, in turn, affect cell attachment onto the hydrogels and the utility of this ligand-free approach is extended by forecasting cell attachment using regression modeling to isolate the effects of individual parameters in an initially complex system. We demonstrate that increasing the charge density, and/or shear modulus, of the hydrogel results in increased cell attachment. [less ▲]

Detailed reference viewed: 29 (0 UL)
Full Text
Peer Reviewed
See detailSeparating the influence of electric charges in magnetic force microscopy images of inhomogeneous metal samples
Arenas, Mónica P.; Martin Lanzoni, Evandro UL; Pacheco, Clara J. et al

in Journal of Magnetism and Magnetic Materials (2018), 446

In this study, we investigate artifacts arising from electric charges present in magnetic force microscopy images. Therefore, we use two austenitic steel samples with different microstructural conditions ... [more ▼]

In this study, we investigate artifacts arising from electric charges present in magnetic force microscopy images. Therefore, we use two austenitic steel samples with different microstructural conditions. Furthermore, we examine the influence of the surface preparation, like etching, in magnetic force images. Using Kelvin probe force microscopy we can quantify the charges present on the surface. Our results show that electrical charges give rise to a signature in the magnetic force microscopy, which is indistinguishable from a magnetic signal. Our results on two differently aged steel samples demonstrate that the magnetic force microscopy images need to be interpreted with care and must be corrected due to the influence of electrical charges present. We discuss three approaches, how to identify these artifacts – parallel acquisition of magnetic force and electric force images on the same position, sample surface preparation to decrease the presence of charges and inversion of the magnetic polarization in two succeeding measurement. [less ▲]

Detailed reference viewed: 19 (0 UL)
Full Text
Peer Reviewed
See detailAdhesive and Reinforcing Properties of Soluble Cellulose: A Repulpable Adhesive for Wet and Dry Cellulosic Substrates
Ferreira, Elisa UL; Martin Lanzoni, Evandro UL; Costa, Carlos A. R. et al

in ACS Applied Materials Interfaces (2015), 7(33), 18750--18758

Detailed reference viewed: 95 (1 UL)