Artículos SCI
2017
2017
Materiales Nanoestructurados y Microestructura
Incorporation of Calcium Containing Mesoporous (MCM-41-Type) Particles in Electrospun PCL Fibers by Using Benign Solvents
Liverani, L.;Boccardi, E.; Beltrán, A.M.; Boccaccini, A.R.Polymers, 9 (2017) 487
Show abstract ▽
![](https://icms.us-csic.es/sites/icms.us-csic.es/files/polymers-09-00487-g006.png)
The electrospinning technique is a versatile method for the production of fibrous scaffolds able to resemble the morphology of the native extra cellular matrix. In the present paper, electrospinning is used to fabricate novel SiO2particles (type MCM-41) containing poly(epsilon-caprolactone) (PCL) fibers. The main aims of the present work are both the optimization of the particle synthesis and the fabrication of composite fibers, obtained using benign solvents, suitable as drug delivery systems and scaffolds for soft tissue engineering applications. The optimized synthesis and characterization of calcium-containing MCM-41 particles are reported. Homogeneous bead-free composite electrospun mats were obtained by using acetic acid and formic acid as solvents; neat PCL electrospun mats were used as control. Initially, an optimization of the electrospinning environmental parameters, like relative humidity, was performed. The obtained composite nanofibers were characterized from the morphological, chemical and mechanical points of view, the acellular bioactivity of the composite nanofibers was also investigated. Positive results were obtained in terms of mesoporous particle incorporation in the fibers and no significant differences in terms of average fiber diameter were detected between the neat and composite electrospun fibers. Even if the Ca-containing MCM-41 particles are bioactive, this property is not preserved in the composite fibers. In fact, during the bioactivity assessment, the particles were released confirming the potential application of the composite fibers as a drug delivery system. Preliminary in vitro tests with bone marrow stromal cells were performed to investigate cell adhesion on the fabricated composite mats, the positive obtained results confirmed the suitability of the composite fibers as scaffolds for soft tissue engineering.
Octubre, 2017 | DOI: 10.3390/polym9100487
Materiales de Diseño para la Energía y Medioambiente
Cellulose-polyhydroxylated fatty acid ester-based bioplastics with tuning properties: Acylation via a mixed anhydride system
Heredia-Guerrero, JA; Goldoni, L; Benitez, JJ; Davis, A; Ceseracciu, L; Cingolani, R; Bayer, IS; Heinze, T; Koschella, A; Heredia, A; Athanassiou, ACarbohydrate Polymers, 173 (2017) 312-320
Show abstract ▽
![](https://icms.us-csic.es/sites/icms.us-csic.es/files/1-s2.0-S0144861717305866-gr5.jpg)
The synthesis of microcrystalline cellulose (MCC) and 9,10,16-hydroxyhexadecanoic (aleuritic) acid ester-based bioplastics was investigated through acylation in a mixed anhydride (trifluoroacetic acid (TFA)/trifluoroacetic acid anhydride (TFAA)), chloroform co-solvent system. The effects of chemical interactions and the molar ratio of aleuritic acid to the anhydroglucose unit (AGU) of cellulose were investigated. The degree of substitution (DS) of new polymers were characterized by two-dimensional solution-state NMR and ranged from 0.51 to 2.60. The chemical analysis by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) confirmed the presence of aleuritate groups in the structure induces the formation of new H-bond networks. The tensile analysis and the contact angle measurement confirmed the ductile behavior and the hydrophobicity of the prepared bioplastics. By increasing the aleuritate amounts, the glass transition temperature decreased and the solubility of bioplastic films in most common solvents was improved. Furthermore, this new polymer exhibits similar properties compared to commercial cellulose derivatives.
Octubre, 2017 | DOI: 10.1016/j.carbpol.2017.05.068
Química de Superficies y Catálisis
Synthesis and characterization of Rh/MnO2-CeO2/Al2O3 catalysts for CO-PrOx reaction
Martinez, TLM; Laguna, OH; Lopez-Cartes, C; Centeno, MAMolecular Catalysis, 440 (2017) 9-18
Show abstract ▽
![](https://icms.us-csic.es/sites/icms.us-csic.es/files/1-s2_121.png)
Rh/MnO2-CeO2/Al2O3 catalysts with different manganese-to-ceria ratios have been synthesized, characterized and tested in CO-PrOx reaction. The physicochemical properties of the solids were studied by XRD, Raman spectroscopy, BET surface area, H-2-TPR, TGA-DTG and TEM. The differences observed in the textural, structural and redox properties were related to the Mn-to-ceria ratio of the samples. The segregation of Mn species was observed at high Mn-to-Ce ratios. In opposite way, MnO2-CeO2 solid solutions were obtained at low Mn to Ce ones. In this last case, the physicochemical properties of the solids were favored by the intimate Rh-Ce-Mn contact. The effect of the Mn-Ce presence on Rh catalysts which promotes the catalytic behavior towards selective CO oxidation was observed to be better at low temperatures. At higher temperatures, Mn species promote the Reverse Water Gas Shift reaction, whilst ceria promotes the H-2 oxidation in the whole range of working temperatures.
Octubre, 2017 | DOI: 10.1016/j.mcat.2017.06.018
Materiales y Procesos Catalíticos de Interés Ambiental y Energético - Materiales Nanoestructurados y Microestructura
Towards Extending Solar Cell Lifetimes: Addition of a Fluorous Cation to Triple Cation-Based Perovskite Films
Salado, M; Fernandez, MA; Holgado, JP; Kazim, S; Nazeeruddin, MK; Dyson, PJ; Ahmad, SChemsuschem, 10 (2017) 3846-3853
Show abstract ▽
![](https://icms.us-csic.es/sites/icms.us-csic.es/files/cssc201700797-fig-0005.png)
Organohalide perovskites have emerged as highly promising replacements for thin-film solar cells. However, their poor stability under ambient conditions remains problematic, hindering commercial exploitation. The addition of a fluorous-functionalized imidazolium cation during the preparation of a highly stable cesium-based mixed perovskite material Cs-0.05(MA(0.15)FA(0.85))(0.95)Pb(I0.85Br0.15)(3) (MA= methylammonium; FA= formamidinium) has been shown to influence its stability. The resulting materials, which vary according to the amount of the fluorous-functionalized imidazolium cation present during fabrication, display a prolonged tolerance to atmospheric humidity (> 100 days) along with power conversion efficiencies exceeding 16%. This work provides a general route that can be implemented in a variety of perovskites and highlights a promising way to increase perovskite solar cell stability.
Octubre, 2017 | DOI: 10.1002/cssc.201700797
Reactividad de Sólidos
Dense graphene nanoplatelet/yttria tetragonal zirconia composites: Processing, hardness and electrical conductivity
Gallardo-Lopez, A; Marquez-Abril, I; Morales-Rodriguez, A; Munoz, A; Poyato, RCeramics International, 43 (2017) 11743-11752
Show abstract ▽
![](https://icms.us-csic.es/sites/icms.us-csic.es/files/1-s2_119.png)
Yttria tetragonal zirconia ceramic composites with 1, 2.5, 5 and 10 vol% nominal contents of graphene nanoplatelets (GNPs) were fabricated and characterized. First, the GNP dispersion in isopropanol was optimized to de-agglomerate the GNPs without damaging their structure. Then, submicrometric fully dense composites were obtained via spark plasma sintering (SPS) at 1250 degrees C with a 5 min holding time. The processing routine produced a nearly homogeneous GNP dispersion in the ceramic matrix, and the GNPs preferential orientation was perpendicular to the sintering compression axis. A ceramic grain refinement due to the GNPs was also detected. The Vickers hardness measured on the plane perpendicular to the sintering compression axis (basal plane) was lower than on the cross sections. This anisotropy increased with the increasing GNP content, while the average hardness decreased. The electrical conductivity was also highly anisotropic, up to seven times higher for the basal planes. The electrical percolation threshold for these composites was estimated to be between 2.2 and 4.4 vol% of the GNP measured content.
Octubre, 2017 | DOI: 10.1016/j.ceramint.2017.06.007
- ‹ anterior
- 183 of 420
- siguiente ›