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Scientific Papers in SCI

2018


Strong activation effect on a ru-co-c thin film catalyst for the hydrolysis of sodium borohydride


Arzac, GM; Paladini, M; Godinho, V; Beltran, AM; de Haro, MCJ; Fernandez, A
Scientific Reports, 8 (2018) art. 9755

ABSTRACT

In this work, we prepared a series of Ni foam supported Ru-Co, Ru-Co-B and Ru-Co-C catalysts in the form of columnar thin films by magnetron sputtering for the hydrolysis of sodium borohydride. We studied the activity and durability upon cycling. We found a strong activation effect for the Ru-Co-C sample which was the highest ever reported. This catalyst reached in the second cycle an activity 5 times higher than the initial (maximum activity 9310 ml.min(-1).g(CoRu)(-1) at 25 degrees C). Catalytic studies and characterization of the fresh and used samples permitted to attribute the strong activation effect to the following factors: (i) small column width and amorphous character (ii) the presence of Ru and (iii) dry state before each cycle. The presence of boron in the initial composition is detrimental to the durability. Our studies point out to the idea that after the first cycle the activity is controlled by surface Ru, which is the most active of the two metals. Apart from the activation effect, we found that catalysts deactivated in further cycles. We ascribed this effect to the loss of cobalt in the form of hydroxides, showing that deactivation was controlled by the chemistry of Co, the major surface metal component of the alloy. Alloying with Ru is beneficial for the activity but not for the durability, and this should be improved.


June, 2018 | DOI: 10.1038/s41598-018-28032-6

Effects of milling time, sintering temperature, Al content on the chemical nature, microhardness and microstructure of mechanochemically synthesized FeCoNiCrMn high entropy alloy


Alcala, MD; Real, C; Fombella, I; Trigo, I; Cordoba, JM
Journal of Alloys and Compounds, 749 (2018) 834-843

ABSTRACT

FeCoNiCrMn(Al)-based powdered high entropy alloys were synthesized by a short time mechanical alloying process in a high energy planetary ball milling from mixtures of elemental powders, and subsequently sintered by a pressureless procedure. The composition and microstructure of the HEA phases before and after the sintering process were studied by X-ray diffraction, energy dispersive X-ray analysis (EDX) and scanning electron microscopy. The microhardness and tensile strength values for Fe1,8Co1,8Ni1,8Cr1,8Mn1,8Al1,0 HEA sintered at 1400 degrees C sample were 3,7 GPa and 1011 MPa, respectively. Statistical Fisher-Pearson coefficient of skewness and kurtosis were played to determine the optimum synthesis milling time. The use of NaCl as additive led on to a reduction of the as-milled grain size. After sintering, SEM study confirmed a segregation of the initial HEA phase directly related to the melting temperature of the elements. Three melting temperature groups were described (Cr, FeCoNi and Mn) and they agree with the observation in the elemental mapping study. The presence of Al favored the segregation of Cr. 


June, 2018 | DOI: 10.1016/j.jallcom.2018.03.358

Heteroatom framework distribution and layer charge of sodium Taeniolite


Perdigon, AC; Pesquera, C; Cota, A; Osuna, FJ; Pavon, E; Alba, MD
Applied Clay Science, 158 (

ABSTRACT

The most advanced applications of clays depend crucially on their hydration state and swelling is probably the most important feature of expandable 2:1 layered silicate. Sodium Taeniolite, Na-TAE, a swelling trioctahedral fluormica, has been synthesized and studied using thermogravimetric analysis, X-ray diffraction, scanning electron microscopy and infrared and solid state NMR spectroscopies. The results indicated the formation of a swelling 2:1 phyllosilicate with actual layer charge lower than the nominal one. Herein, a new heteroatom distribution and more accurate composition could be deduced.


June, 2018 | DOI: 10.1016/j.clay.2018.03.036

Growth of nanocolumnar porous TiO2 thin films by magnetron sputtering using particle collimators


Garcia-Valenzuela, A; Alvarez, R; Rico, V; Cotrino, J; Gonzalez-Elipe, AR; Palmero, A
Surface & Coatings Technology, 343 (2018) 172-177

ABSTRACT

The selective incorporation of deposition species with preferential directionality is analyzed during the growth of TiO2 thin films by magnetron sputtering. Using wisely-designed collimators, tilted nanocolumnar morphologies are grown in a ballistic deposition regime, i.e. when most deposition species arrive at the film surface along well-defined preferential directions, and also in a thermalized deposition regime, when these species follow an isotropic momentum distribution in the plasma gas. The obtained results suggest that the use of particle collimators may promote the growth of porous thin films even in the classical magnetron sputtering configuration, when the target and the substrate are parallel. General insights are given on this approach and, as a proof of concept, its principles applied for the synthesis of nanostructured films in a laboratory-size reactor.


June, 2018 | DOI: 10.1016/j.surfcoat.2017.09.039

Chemical CO2 recycling via dry and bi reforming of methane using Ni-Sn/Al2O3 and Ni-Sn/CeO2-Al2O3 catalysts


Stroud, T; Smith, TJ; Le Sache, E; Santos, JL; Centeno, MA; Arellano-Garcia, H; Odriozola, JA; Reina, TR
Applied Catalysis B-Environmental, 224 (2018) 125-135

ABSTRACT

Carbon formation and sintering remain the main culprits regarding catalyst deactivation in the dry and bi-reforming of methane reactions (DRM and BRM, respectively). Nickel based catalysts (10 wt.%) supported on alumina (Al2O3) have shown no exception in this study, but can be improved by the addition of tin and ceria. The effect of two different Sn loadings on this base have been examined for the DRM reaction over 20 h, before selecting the most appropriate Sn/Ni ratio and promoting the alumina base with 20 wt.% of CeO2. This catalyst then underwent activity measurements over a range of temperatures and space velocities, before undergoing experimentation in BRM. It not only showed good levels of conversions for DRM, but exhibited stable conversions towards BRM, reaching an equilibrium H-2/CO product ratio in the process. In fact, this work reveals how multicomponent Ni catalysts can be effectively utilised to produce flexible syngas streams from CO2/CH4 mixtures as an efficient route for CO2 utilisation.


May, 2018 | DOI: 10.1016/j.apcatb.2017.10.047

Carbonation of Limestone Derived CaO for Thermochemical Energy Storage: From Kinetics to Process Integration in Concentrating Solar Plants


Ortiz, C; Valverde, JM; Chacartegui, R; Perez-Maqueda, LA
ACS Sustainable Chemistry & Engineering, 6 (2018) 6404-6417

ABSTRACT

Thermochemical energy storage (TCES) is considered as a promising technology to accomplish high energy storage efficiency in concentrating solar power (CSP) plants. Among the various possibilities, the calcium-looping (CaL) process, based on the reversible calcination–carbonation of CaCO3 stands as a main candidate due to the high energy density achievable and the extremely low price, nontoxicity, and wide availability of natural CaO precursors such as limestone. The CaL process is already widely studied for CO2 capture in fossil fuel power plants or to enhance H2 production from methane reforming. Either one of these applications requires particular reaction conditions to which the sorbent performance (reaction kinetics and multicycle conversion) is extremely sensitive. Therefore, specific models based on the conditions of any particular application are needed. To get a grip on the optimum conditions for the carbonation of limestone derived CaO in the CaL-CSP integration, in the present work is pursued a multidisciplinary approach that combines theoretical modeling on reaction kinetics, lab-scale experimental tests at relevant CaL conditions for TCES, process modeling, and simulations. A new analytic equation to estimate the carbonation reaction rate as a function of CO2 partial pressure and temperature is proposed and validated with experimental data. Using the kinetics analysis, a carbonator model is proposed to assess the average carbonation degree of the solids. After that, the carbonator model is incorporated into an overall process integration scheme to address the optimum operation conditions from thermodynamic and kinetics considerations. Results from process simulations show that the highest efficiencies for the CaL-CSP integration are achieved at carbonator absolute pressures of ∼3.5–4 bar, which leads to an overall plant efficiency (net electric power to net solar thermal power) around 41% when carbonation is carried out at 950 °C under pure CO2


May, 2018 | DOI: 10.1021/acssuschemeng.8b00199

Multicomponent Ni-CeO2 nanocatalysts for syngas production from CO2/CH4 mixtures


le Sache, E.; Santos, J. L.; Smith, T. J.; Centeno, M. A.; Arellano-Garcia, H.; Odriozola, J. A.; Reina, T. R.
Journal of CO2 utilization, 25 (2018) 68-78

ABSTRACT

The dry reforming of methane with CO2 is a common route to transform CO2/CH4 mixtures into added value syngas. Ni based catalysts are highly active for this goal but suffer from deactivation, as such promoters need to be introduced to counteract this, and improve performance. In this study, mono- and bi-metallic formulations based on 10 wt.% Ni/CeO2-Al2O3 are explored and compared to a reference 10 wt.% Ni/gamma-Al2O3. The effect of Sn and Pt as promoters of Ni/CeO2-Al2O3 was also investigated. The formulation promoted with Sn looked especially promising, showing CO2 conversions stabilising at 65% after highs of 95%. Its increased performance is attributed to the additional dispersion Sn promotion causes. Changes in the reaction conditions (space velocity and temperature) cement this idea, with the Ni-Sn/CeAl material performing superiorly to the mono-metallic material, showing less deactivation. However, in the long run it is noted that the mono- metallic Ni/CeAl performs better. As such the application is key when deciding which catalyst to employ in the dry reforming process.


May, 2018 | DOI: 10.1016/j.jcou.2018.03.012

Influence of gold particle size in Au/C catalysts for base-free oxidation of glucose


Megias-Sayago, C; Santos, JL; Ammari, F; Chenouf, M; Ivanova, S; Centeno, MA; Odriozola, JA
Catalysis Today, 306 (2018) 183-190

ABSTRACT

A series of gold colloids were prepared and immobilized on commercial activated carbon. The influence of the colloid preparation and stability were studied and related to the gold particle size in the final catalyst. The catalysts show an important activity in the glucose to gluconic acid oxidation reaction, leading to gluconic acid yield close to 90% in base free mild conditions (0.1 MPa O-2 and 40 degrees C). The size-activity correlation and probable mechanism were also discussed. Finally, the viability of the catalyst was tested by recycling it up to four times. 


May, 2018 | DOI: 10.1016/j.cattod.2017.01.007

Development of a novel TiNbTa material potentially suitable for bone replacement implants


Chicardi, E; Gutierrez-Gonzalez, CF; Sayagues, MJ; Garcia-Garrido, C
Materials & Design, 145 (2018) 88-96

ABSTRACT

A novel (beta + gamma)-TiNbTa alloy has been developed by a combined low energy mechanical alloying (LEMA) and pulsed electric current sintering process (PECS). Microstructurally, this material presents interesting characteristics, such as a submicrometric range of particle size, a body-centered phase (beta-TiNbTa) and, mainly, a novel face-centered cubic Ti-based alloy (gamma-TiNbTa) not previously reported. Related to mechanical performance, the novel (beta + gamma)-TiNbTa shows a lower E (49 +/- 3 GPa) and an outstanding yield strength (sigma(y) 1860 MPa). This combination of original microstructure and properties makes to the (beta + gamma)-TiNbTa a novel material potentially suitable as biomaterial to fabricate bone replacement implants, avoiding the undesirable and detrimental stressshielding problem and even the usual damage on the mechanical strength of Ti-based foams biomaterials. 


May, 2018 | DOI: 10.1016/j.matdes.2018.02.042

Multicomponent Au/Cu-ZnO-Al2O3 catalysts: Robust materials for clean hydrogen production


Santos, JL; Reina, TR; Ivanov, I; Penkova, A; Ivanova, S; Tabakova, T; Centeno, MA; Idakiev, V; Odriozola, JA
Applied Catalysis A-General, 558 (2018) 91-98

ABSTRACT

Clean hydrogen production via WGS is a key step in the development of hydrogen fuel processors. Herein, we have designed a new family of highly effective catalysts for low-temperature WGS reaction based on gold modified copper-zinc mixed oxides. Their performance was controlled by catalysts' composition and the Au-Cu synergy. The utilization of hydrotalcite precursors leads to an optimal microstructure that ensures excellent Au and Cu dispersion and favors their strong interaction. From the application perspective these materials succeed to overcome the major drawback of the commercial WGS catalysts: resistance towards start/stop operations, a mandatory requisite for H-2-powered mobile devices.


May, 2018 | DOI: 10.1016/j.apcata.2018.04.002

Tribological properties of TiC/a-C:H nanocomposite coatings prepared via HiPIMS


Sanchez-Lopez, JC; Dominguez-Meister, S; Rojas, TC; Colasuonno, M; Bazzan, M; Patelli, A
Applied Surface Science, 440 (2018) 458-466

ABSTRACT

High power impulse magnetron sputtering (HiPIMS) technology has been employed to prepare TiC/a-C:H nanocomposite coatings from a titanium target in acetylene (C2H2) reactive atmospheres. Gas fluxes were varied from 1.3 to 4.4 sccm to obtain C/Ti ratios from 2 to 15 as measured by electron probe microanalysis (EPMA). X-ray diffraction and transmission electron microscopy demonstrate the presence of TiC nanocrystals embedded in an amorphous carbon-based matrix. The hardness properties decrease from 17 to 10 GPa as the carbon content increases. The tribological properties were measured using a pinon-disk tribometer in ambient air (RH = 30-40%) at 10 cm/s with 5 N of applied load against 6-mm 100Cr6 balls. The friction coefficient and the film wear rates are gradually improved from 0.3 and 7 x 10(-6) mm(3)/N m to 0.15 and 2 x 10(-7) mm(3)/N m, respectively, by increasing the C2H2 flux. To understand the tribological processes appearing at the interface and to elucidate the wear mechanism, microstructural and chemical investigations of the coatings were performed before and after the friction test. EPMA, X-ray photoelectron and electron energy-loss spectroscopies were employed to obtain an estimation of the fraction of the a-C:H phase, which can be correlated with the tribological behavior. Examination of the friction counterfaces (ball and track) by Raman microanalysis reveals an increased ordering of the amorphous carbon phase concomitant with friction reduction. The tribological results were compared with similar TiC/a-C(:H) composites prepared by the conventional direct current process. 


May, 2018 | DOI: 10.1016/j.apsusc.2018.01.135

Engineering of III-Nitride Semiconductors on Low Temperature Co-fired Ceramics


Manuel, JM; Jimenez, JJ; Morales, FM; Lacroix, B; Santos, AJ; Garcia, R; Blanco, E; Dominguez, M; Ramirez, M; Beltran, AM; Alexandrov, D; Tot, J; Dubreuil, R; Videkov, V; Andreev, S; Tzaneva, B; Bartsch, H; Breiling, J; Pezoldt, J; Fischer, M; Muller, J
Scientific Reports, 8 (2018) art. 6879

ABSTRACT

This work presents results in the field of advanced substrate solutions in order to achieve high crystalline quality group-III nitrides based heterostructures for high frequency and power devices or for sensor applications. With that objective, Low Temperature Co-fired Ceramics has been used, as a non-crystalline substrate. Structures like these have never been developed before, and for economic reasons will represent a groundbreaking material in these fields of Electronic. In this sense, the report presents the characterization through various techniques of three series of specimens where GaN was deposited on this ceramic composite, using different buffer layers, and a singular metal-organic chemical vapor deposition related technique for low temperature deposition. Other single crystalline ceramic-based templates were also utilized as substrate materials, for comparison purposes.


May, 2018 | DOI: 10.1038/s41598-018-25416-6

Crystallization Kinetics of Nanocrystalline Materials by Combined X-ray Diffraction and Differential Scanning Calorimetry Experiments


Gil-Gonzalez, E; Perejon, A; Sanchez-Jimenez, PE; Medina-Carrasco, S; Kupcik, J; Subrt, J; Criado, JM; Perez-Maqueda, LA
Crystal Growth & Design, 18 (2018) 3107-3116

ABSTRACT

Crystallization is one key aspect in the resulting properties of nanocrystalline functional materials, and much effort has been devoted to understanding the physical mechanisms involved in these processes as a function of temperature. The main problems associated with crystallization kinetic studies come from the limitations of the employed techniques, and the obtained results may vary significantly depending on the choice of the measurement method. In this work, a complete description of the thermal crystallization event of nanocrystalline BiFeO3 has been performed by combining the information obtained from three different experimental techniques: in situ high-temperature X-ray diffraction, transmission electron microscopy, and differential scanning calorimetry. Interestingly, the kinetic analysis of the X-ray diffraction and differential scanning calorimetry data yields almost identical results, although the physical properties measured by both techniques are different. This allows the unambiguous determination of the kinetic parameters. The importance of a proper definition of the conversion degree, which is limited by the employed measurement technique, is also highlighted.


May, 2018 | DOI: 10.1021/acs.cgd.8b00241

High-temperature compressive creep of novel fine-grained orthorhombic ZrO2 ceramics stabilized with 12 mol% Ta doping


Sponchia, G; Moshtaghioun, BM; Riello, P; Benedetti, A; Gomez-Garcia, D; Dominguez-Rodriguez, A; Ortiz, AL
Journal of the European Ceramic Society, 38 (2018) 2445-2448

ABSTRACT

A novel fine-grained orthorhombic ZrO2 ceramic stabilized with 12 mol% Ta doping was fabricated by spark plasma sintering from home-made powders, and its high-temperature mechanical properties evaluated for the first time by compressive creep tests in both Ar and air. It was found that the high-temperature plasticity of the ceramic deformed in Ar, under which the Ta-doped orthorhombic ZrO2 is a black suboxide with abundant oxygen vacancies in its crystal structure, is controlled by grain boundary sliding (stress exponent similar to 2, and activation energy similar to 780-800 kJ/mol). However, the high-temperature plasticity of the ceramic deformed in air, under which the Ta-doped orthorhombic ZrO2 is a white oxide due to the elimination in situ of oxygen vacancies, is controlled by recovery creep (stress exponent 3, and activation energy similar to 750 kJ/mol). It was also observed that black Ta-doped orthorhombic ZrO2 is more creep resistant than its white counterpart with the same grain size, and that the former deforms as the more conventional Y2O3-stabilized ZrO2 does.


May, 2018 | DOI: 10.1016/j.jeurceramsoc.2017.12.055

Fabrication and characterization of WC-HEA cemented carbide based on the CoCrFeNiMn high entropy alloy


Velo, IL; Gotor, FJ; Alcala, MD; Real, C; Cordoba, JM
Journal of Alloys and Compounds, 746 (2018) 1-8

ABSTRACT

A high entropy alloy (HEA, CoCrFeNiMn) synthesized by mechanical alloying was used as the binder for the densification of WC by a pressureless high temperature procedure. Three different WC were used by modifying its microstructure with a high energy ball milling treatment. The alloy content in the HEA-WC mixture was varied from 10 to 30% vol. The microstructure and properties of the sintered composites were studied by X-ray diffraction, scanning electron microscopy and microindentation.


May, 2018 | DOI: 10.1016/j.jallcom.2018.02.292

Influence of the Mn content on the TiNbxMn alloys with a novel fcc structure


Chicardi, E; Aguilar, C; Sayagues, MJ; Garcia-Garrido, C
Journal of Alloys and Compounds, 746 (2018) 601-610

ABSTRACT

This work studies the structural evolution of TiNbxMn alloys (x: 0-12 wt%) synthetized by mechanical alloying in a planetary ball mill with different milling times between 1 h and 120 h. The specimens were characterized by X-ray diffraction patterns, scanning and transmission electron microscopies and Energy-dispersive X-ray spectroscopy. It was observed an evolution of the alloys developed from the raw Ti, Nb and Mn elements to bcc-TiNbxMn alloys and, finally, novel fcc-TiNbxMn alloys, with Fm3m space group symmetry, not previously observed. The presence of Mn promotes other interesting effects: a) the decreasing of the crystallite and the particle sizes, reaching values close to 4 nm and 400 nm, respectively, b) the partial amorphization of the fcc-TiNbxMn alloys due to the combined effect of the Mechanical Alloying and the difference of Mn atomic size in comparison with Ti and Nb and c) the presence of Mn that decreases the Fe amount (from milling media) in the as-milled powders. 


May, 2018 | DOI: 10.1016/j.jallcom.2018.02.306

Effects of additives on the synthesis of TiCxN1-x by a solid-gas mechanically induced self-sustaining reaction


Chicardi, E; Gotor, FJ; Alcala, MD; Cordoba, JM
Ceramics International, 44 (2018) 7605-7610

ABSTRACT

The synthesis of TiCxN1-x from Ti/C mixtures in a N-2 atmosphere performed in a high-energy planetary mill was used as example to study the influence of the use of additives in mechanically induced self-sustaining reaction (MSR) processes. In particular, the effect of the addition of TiN, TiC, Si3N4 and SiC was analyzed. The self-sustaining reaction was extinguished when additive contents of 50, 40, 40 and 30 wt% for TiN, TiC, Si3N4 and SiC, respectively, were employed. These additives cannot be regarded as real inert since they served as an extra solid source for nitrogen and carbon, modifying the final stoichiometry of the TiCxN1-x phase. The adiabatic temperature (T-ad) determined for the mixtures with no MSR effect was well above the empirical limit value of 1800 K adopted as criterion for the occurrence of the self-propagating high-temperature synthesis (SHS) process. The ignition time (t(ig)) of the MSR process was practically invariant for low additive contents (approximately 50 min) and tended to increase up to maximum values of 85-95 min for the larger additive contents.


May, 2018 | DOI: 10.1016/j.ceramint.2018.01.179

Study of the effectiveness of the flocculation-photocatalysis in the treatment of wastewater coming from dairy industries


Murcia, J.J., Hernández-Laverde, M., Rojas, Muñoz, E., Navío, J.A., Hidalgo, M.C.
Journal of Photochemistry and Photobiology A: Chemistry, 358 (2018) 256-264

ABSTRACT

The aim of the present work was to evaluate the effectiveness of flocculation-photocatalysis as combined processes in the treatment of dairy industries wastewater. Different commercial and lab prepared flocculants and photocatalysts were evaluated. All the materials prepared were extensively characterized. Commercial materials presented the best physicochemical properties and performance in the treatment of the studied wastewater. On one hand, all the photocatalysts evaluated showed bactericidal activity for E. Coli, total coliforms and other enterobacteriaceae. Total elimination of E. coli was obtained by using commercial TiO2 P25 Evonik, under 120 W/m2 of UV–vis light intensity and 5 h of total illumination time. Other species of bacteria remained after treatment under these conditions. It was also found that the highest light intensity of 120 W/m2 led to increase the Chemical Oxygen Demand and Total Organic Carbon in the samples treated, it can be due to the faster formation of new organic compounds as intermediaries during the photocatalytic reactions at the highest photonic flux. Flocculation pre-treatment of the wastewater samples led to improve the effectiveness of the photocatalytic treatment; thus, the combination of flocculation-photocatalysis treatments at low light intensity of 30 W/m2 leads to achieve the total elimination of E. coli, and under this intensity the elimination of total coliforms and other enterobacteriaceae increased 5.48% compared to the photocatalytic treatment alone. These treatment conditions led to comply the Colombian regulations for dairy wastewater.


May, 2018 | DOI: 10.1016/j.jphotochem.2018.03.034

Photo-induced processes on Nb2O5 synthesized by different procedures


Jaramillo-Páez, C., Sánchez-Fernández, F.J., Navío, J.A., Hidalgo, M.C.
Journal of Photochemistry and Photobiology A: Chemistry, 359 (2018) 40-52

ABSTRACT

The properties of Nb2O5 strongly depend on its synthesis procedure as well as the conditions of ulterior thermal treatment. We report the synthesis of Nb2O5 powders prepared by sol-gel precipitation method using niobium(V) ethoxide as precursor. Two chemical routes were chosen: the presence of tryethyl amine (TEA) as precipitant/template agent, or the oxidant peroxide method. In addition, microwave-assisted activation was also used. The as-prepared samples by the above procedures were amorphous. Structural changes upon heating from room temperature up to 800 °C were investigated by X-ray powder diffraction technique combined with thermogravimetric analysis. The sequential thermal treatment up to 800 °C promotes the crystallization of hexagonal phase to orthorhombic phase whereas the ulterior cooling to room temperature lead to a mixture of both phases. Samples calcined at selected temperatures of either 600 °C or 800 °C for 2 h, were characterized by XRD, SEM, N2-adsorption and diffuse reflectance spectroscopy (DRS). The synthetic approach routes as well as the combined microwave activation followed by ulterior thermal treatment lead to changes not only on particle size but also on the textural properties of the synthesized catalysts. The catalysts synthesized have been evaluated using Rhodamine B (RhB) as a substrate, under both UV and visible lighting conditions. None of the catalysts synthesized showed activity in the visible. Under UV-illumination conditions, some of the catalysts exhibited a relatively low photoactivity in the degradation of RhB, which is associated with a photo-sensitizing effect. However, the addition of Ag+ ions considerably increased the activity of all the catalysts in the degradation of RhB under UV-illumination conditions. A mechanism is proposed to explain the photo-induced processes obtained, leaving the door open to the possible implications of the observed results in relation to the interaction of RhB dye with noble metal nanoparticles such as silver.


May, 2018 | DOI: 10.1016/j.jphotochem.2018.03.040

In Vitro Comparative Study of Oxygen Plasma Treated Poly(Lactic-Co-Glycolic) (PLGA) Membranes and Supported Nanostructured Oxides for Guided Bone Regeneration Processes


Torres-Lagares, D; Castellanos-Cosano, L; Serrera-Figallo, MA; Lopez-Santos, C; Barranco, A; Rodriguez-Gonzalez-Elipe, A; Gutierrez-Perez, JL
Materials, 11 (2018) art. 752

ABSTRACT

(1) Background: The use of physical barriers to prevent the invasion of gingival and connective tissue cells into bone cavities during the healing process is called guided bone regeneration. The objective of this in-vitro study was to compare the growth of human osteoblasts on Poly(Lactic-co-Glycolic) (PLGA) membranes modified with oxygen plasma and Hydroxyapatite (HA), silicon dioxide (SiO2), and titanium dioxide (TiO2) composite nanoparticles, respectively. (2) Methods: All the membranes received a common treatment with oxygen plasma and were subsequently treated with HA nanostructured coatings (n = 10), SiO2 (n = 10) and TiO2 (n = 10), respectively and a PLGA control membrane (n = 10). The assays were performed using the human osteoblast line MG-63 acquired from the Center for Scientific Instrumentation (CIC) from the University of Granada. The cell adhesion and the viability of the osteoblasts were analyzed by means of light-field microphotographs of each condition with the inverted microscope Axio Observer A1 (Carl Zeiss). For the determination of the mitochondrial energy balance, the MitoProbe (TM) JC-1 Assay Kit was employed. For the determination of cell growth and the morphology of adherent osteoblasts, two techniques were employed: staining with phalloidin-TRITC and staining with DAPI. (3) Results: The modified membranes that show osteoblasts with a morphology more similar to the control osteoblasts follow the order: PLGA/PO2/HA > PLGA/PO2/SiO2 > PLGA/PO2/TiO2 > PLGA (p < 0.05). When analysing the cell viability, a higher percentage of viable cells bound to the membranes was observed as follows: PLGA/PO2/SiO2 > PLGA/PO2/HA > PLGA/PO2/TiO2 > PLGA (p < 0.05), with a better energy balance of the cells adhered to the membranes PLGA/PO2/HA and PLGA/PO2/SiO2. (4) Conclusion: The membrane in which osteoblasts show characteristics more similar to the control osteoblasts is the PLGA/PO2/HA, followed by the PLGA/PO2/SiO2.


May, 2018 | DOI: 10.3390/ma11050752

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