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1.
Artículo en Inglés | MEDLINE | ID: mdl-37924398

RESUMEN

The reuse of biomass waste has been gaining attention in adsorption processes to remove pollutants of emerging concern from water and wastewater. In this work, the potential of alginate-extracted macro-algae waste to uptake synthetic dyes and metal cations was evaluated in comparison with raw algae. In affinity assays, both materials were able to remove metal cations and cationic dyes up to maximum rates, and no significant removal was observed for an anionic dye in an acidic medium. Competition was observed in multi-component systems of metal cations and dyes. For binary samples containing organic and inorganic contaminants, kinetic modeling evidenced the distinct nature of both types of adsorbates. Pb(II) biosorption was best described as a first-order process, while second-order and Elovich models better fitted methyl blue (MB) uptake data. For equimolar binary samples, the Sips isothermal model fitted the experimental data more satisfactorily at room temperature. Isotherms for 20, 30, 40, and 60 °C exhibited favorable adsorption profiles with spontaneous ΔG values for both raw macro-algae and waste from alginate extraction. Maximum adsorption capacities were competitive with previous reports in the literature for a wide range of biomaterials, pointing to the slightly higher efficiency with algae waste in batch experiments. In elution tests, HNO3 (0.5 M) showed the best recovery rates of metal cations. Continuous biosorption operation revealed the performance of the brown algae waste was considerably more efficient than raw algae with breakthrough biosorption capacities up to 3.96 and 0.97 mmol.g-1 for the removal of Pb(II) and MB, respectively. A total of 3.0 g of algae and algae waste were able to deliver 1.20 and 1.62 L of contaminant-free water, respectively. XPS analyses corroborate previous assays that pointed to the prevalence of physisorption with evidence of complexation, ionic exchange, and hydrogen displacement mechanisms.

2.
RSC Adv ; 13(40): 28042-28050, 2023 Sep 18.
Artículo en Inglés | MEDLINE | ID: mdl-37746337

RESUMEN

The present work is on a comprehensive surface atomic structure investigation of ß-Ga2O3 (100). The ß-Ga2O3 single crystal was studied by a structural model system in the simulations and in situ characterization via X-ray photoelectron spectroscopy (XPS), low-energy electron diffraction (LEED) and X-ray photoelectron diffraction (XPD) allowed for probing the outermost layers' properties. In situ XPD characterization allows for the collection of valuable element-specific short-range information from the ß-Ga2O3 surface, and the results were compared to a systematic and precise multiple scattering simulation approach. The experiments, characterizations, and simulations indicated strong evidence of considerable structural variations in the interatomic layer's distances. Such atomic displacement could clarify the electronic phenomena observed in theoretical studies. The comparison between experimental and theoretical XPD results involving multiple scattering calculations indicated that the ß-Ga2O3 surface has two possible terminations. The best fits to the photoelectron diffraction curves are used to calculate the interplanar relaxation in the first five atomic layers. The results show good agreement with previous density functional theory calculations, establishing XPD as a useful tool for probing the atomic structure of oxide surfaces.

3.
Am Psychol ; 78(1): 36-49, 2023 01.
Artículo en Inglés | MEDLINE | ID: mdl-35157476

RESUMEN

Researchers, governments, ethics watchdogs, and the public are increasingly voicing concerns about unfairness and bias in artificial intelligence (AI)-based decision tools. Psychology's more-than-a-century of research on the measurement of psychological traits and the prediction of human behavior can benefit such conversations, yet psychological researchers often find themselves excluded due to mismatches in terminology, values, and goals across disciplines. In the present paper, we begin to build a shared interdisciplinary understanding of AI fairness and bias by first presenting three major lenses, which vary in focus and prototypicality by discipline, from which to consider relevant issues: (a) individual attitudes, (b) legality, ethicality, and morality, and (c) embedded meanings within technical domains. Using these lenses, we next present psychological audits as a standardized approach for evaluating the fairness and bias of AI systems that make predictions about humans across disciplinary perspectives. We present 12 crucial components to audits across three categories: (a) components related to AI models in terms of their source data, design, development, features, processes, and outputs, (b) components related to how information about models and their applications are presented, discussed, and understood from the perspectives of those employing the algorithm, those affected by decisions made using its predictions, and third-party observers, and (c) meta-components that must be considered across all other auditing components, including cultural context, respect for persons, and the integrity of individual research designs used to support all model developer claims. (PsycInfo Database Record (c) 2023 APA, all rights reserved).


Asunto(s)
Inteligencia Artificial , Humanos
4.
Psychol Methods ; 2022 Aug 25.
Artículo en Inglés | MEDLINE | ID: mdl-36006759

RESUMEN

Content analysis is a common and flexible technique to quantify and make sense of qualitative data in psychological research. However, the practical implementation of content analysis is extremely labor-intensive and subject to human coder errors. Applying natural language processing (NLP) techniques can help address these limitations. We explain and illustrate these techniques to psychological researchers. For this purpose, we first present a study exploring the creation of psychometrically meaningful predictions of human content codes. Using an existing database of human content codes, we build an NLP algorithm to validly predict those codes, at generally acceptable standards. We then conduct a Monte-Carlo simulation to model how four dataset characteristics (i.e., sample size, unlabeled proportion of cases, classification base rate, and human coder reliability) influence content classification performance. The simulation indicated that the influence of sample size and unlabeled proportion on model classification performance tended to be curvilinear. In addition, base rate and human coder reliability had a strong effect on classification performance. Finally, using these results, we offer practical recommendations to psychologists on the necessary dataset characteristics to achieve valid prediction of content codes to guide researchers on the use of NLP models to replace human coders in content analysis research. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

5.
J Appl Psychol ; 107(10): 1655-1677, 2022 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-34672652

RESUMEN

Games, which can be defined as an externally structured, goal-directed type of play, are increasingly being used in high-stakes testing contexts to measure targeted constructs for use in the selection and promotion of employees. Despite this increasing popularity, little is known about how theory-driven game-based assessments (GBA), those designed to reflect a targeted construct, should be designed, or their potential for achieving their simultaneous goals of positive reactions and high-quality psychometric measurement. In the present research, we develop a theory of GBA design by integrating game design and development theory from human-computer interaction with psychometric theory. Next, we test measurement characteristics, prediction of performance, fairness, and reactions of a GBA designed according to this theory to measure latent general intelligence (g). Using an academic sample with GPA data (N = 633), we demonstrate convergence between latent GBA performance and g (ß = .97). Adding an organizational sample with supervisory ratings of job performance (N = 49), we show GBA prediction of both GPA (r = .16) and supervisory ratings (r = .29). We also show incremental prediction of GPA using unit-weighted composites of the g test battery beyond that of the g-GBA battery but not the reverse. We also show the presence of similar adverse impact for both the traditional test battery and GBA but the absence of differential prediction of criteria. Reactions were more positive across all measures for the g-GBA compared to the traditional test battery. Overall, results support GBA design theory as a promising foundation from which to build high-quality theory-driven GBAs. (PsycInfo Database Record (c) 2022 APA, all rights reserved).


Asunto(s)
Rendimiento Laboral , Cognición , Humanos , Inteligencia , Motivación , Psicometría
6.
PLoS One ; 16(1): e0245460, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33471835

RESUMEN

In the social and cognitive sciences, crowdsourcing provides up to half of all research participants. Despite this popularity, researchers typically do not conceptualize participants accurately, as gig-economy worker-participants. Applying theories of employee motivation and the psychological contract between employees and employers, we hypothesized that pay and pay raises would drive worker-participant satisfaction, performance, and retention in a longitudinal study. In an experiment hiring 359 Amazon Mechanical Turk Workers, we found that initial pay, relative increase of pay over time, and overall pay did not have substantial influence on subsequent performance. However, pay significantly predicted participants' perceived choice, justice perceptions, and attrition. Given this, we conclude that worker-participants are particularly vulnerable to exploitation, having relatively low power to negotiate pay. Results of this study suggest that researchers wishing to crowdsource research participants using MTurk might not face practical dangers such as decreased performance as a result of lower pay, but they must recognize an ethical obligation to treat Workers fairly.


Asunto(s)
Colaboración de las Masas/economía , Reembolso de Incentivo , Investigación/economía , Adulto , Femenino , Humanos , Estudios Longitudinales , Masculino , Motivación , Satisfacción Personal , Análisis de Regresión
7.
J Phys Condens Matter ; 33(10): 105001, 2021 Mar 10.
Artículo en Inglés | MEDLINE | ID: mdl-33254156

RESUMEN

CVD graphene grown on metallic substrates presents, in several cases, a long-range periodic structure due to a lattice mismatch between the graphene and the substrate. For instance, graphene grown on Ir(111), displays a corrugated supercell with distinct adsorption sites due to a variation of its local electronic structure. This type of surface reconstruction represents a challenging problem for a detailed atomic surface structure determination for experimental and theoretical techniques. In this work, we revisited the surface structure determination of graphene on Ir(111) by using the unique advantage of surface and chemical selectivity of synchrotron-based photoelectron diffraction. We take advantage of the Ir 4f photoemission surface state and use its diffraction signal as a probe to investigate the atomic arrangement of the graphene topping layer. We determine the average height and the overall corrugation of the graphene layer, which are respectively equal to 3.40 ± 0.11 Å and 0.45 ± 0.03 Å. Furthermore, we explore the graphene topography in the vicinity of its high-symmetry adsorption sites and show that the experimental data can be described by three reduced systems simplifying the moiré supercell multiple scattering analysis.

8.
Mater Sci Eng C Mater Biol Appl ; 118: 111438, 2021 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-33255031

RESUMEN

Photofunctionalization mediated by ultraviolet (UV) light seems to be a promising approach to improve the physico-chemical characteristics and the biological response of titanium (Ti) dental implants. Seeing that photofunctionalization is able to remove carbon from the surface, besides to promote reactions on the titanium dioxide (TiO2) layer, coating the Ti with a stable TiO2 film could potentialize the UV effect. Thus, here we determined the impact of UV-photofunctionalized mixed-phase (anatase and rutile) TiO2 films on the physico-chemical properties of Ti substrate and cell biology. Mixed-phase TiO2 films were grown by radiofrequency magnetron sputtering on commercially pure titanium (cpTi) discs, and samples were divided as follow: cpTi (negative control), TiO2 (positive control), cpTi UV, TiO2 UV (experimental). Photofunctionalization was performed using UVA (360 nm - 40 W) and UVC (250 nm - 40 W) lamps for 48 h. Surfaces were analyzed in terms of morphology, topography, chemical composition, crystalline phase, wettability and surface free energy. Pre-osteoblastic cells (MC3T3E1) were used to assess cell morphology and adhesion, metabolism, mineralization potential and cytokine secretion (IFN-γ, TNF-α, IL-4, IL-6 and IL-17). TiO2-coated surfaces exhibited granular surface morphology and greater roughness. Photofunctionalization increased wettability (p < 0.05) and surface free energy (p < 0.001) on both surface conditions. TiO2-treated groups featured normal cell morphology and spreading, and greater cellular metabolic activity at 2 and 4 days (p < 0.05), whereas UV-photofunctionalized surfaces enhanced cell metabolism, cell adhered area, and calcium deposition (day 14) (p < 0.05). In general, assessed proteins were found slightly affected by either UV or TiO2 treatments. Altogether, our findings suggest that UV-photofunctionalized TiO2 surface has the potential to improve pre-osteoblastic cell differentiation and the ability of cells to form mineral nodules by modifying Ti physico-chemical properties towards a more stable context. UV-modified surfaces modulate the secretion of key inflammatory markers.


Asunto(s)
Citocinas , Osteoblastos , Células 3T3-L1 , Animales , Comunicación Celular , Ratones , Propiedades de Superficie , Titanio/farmacología , Rayos Ultravioleta
9.
Polymers (Basel) ; 12(9)2020 Sep 18.
Artículo en Inglés | MEDLINE | ID: mdl-32961866

RESUMEN

This work proposes the use of a dielectric barrier discharge (DBD) reactor operating at atmospheric pressure (AP) using air and sub-atmospheric pressure (SAP) using air or argon to treat polyamide 6.6 (PA6.6) fabrics. Here, plasma dosages corresponding to 37.5 kW·min·m-2 for AP and 7.5 kW·min·m-2 for SAP in air or argon were used. The hydrophilicity aging effect property of untreated and DBD-treated PA6.6 samples was evaluated from the apparent contact angle. The surface changes in physical microstructure were studied by field emission scanning electron microscopy (FE-SEM). To prove the changes in chemical functional groups in the fibers, Fourier transform infrared spectroscopy (FTIR) was used, and the change in surface bonds was evaluated by energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). In addition, the whiteness effect was investigated by the color spectrophotometry (Datacolor) technique. The results showed that the increase in surface roughness by the SAP DBD treatment contributed to a decrease in and maintenance of the hydrophilicity of PA6.6 fabrics for longer. The SAP DBD in air treatment promoted an enhancement of the aging effect with a low plasma dosage (5-fold reduction compared with AP DBD treatment). Finally, the SAP DBD treatment using argon functionalizes the fabric surface more efficiently than DBD treatments in air.

10.
J Colloid Interface Sci ; 579: 680-698, 2020 Nov 01.
Artículo en Inglés | MEDLINE | ID: mdl-32652323

RESUMEN

HYPOTHESIS: Although bioactive glass (BG) particle coatings were previously developed by different methods, poor particle adhesion to surfaces and reduced biological effects because of glass crystallization have limited their biomedical applications. To overcome this problem, we have untangled, for the first time, plasma electrolytic oxidation (PEO) as a new pathway for the synthesis of bioactive glass-based coating (PEO-BG) on titanium (Ti) materials. EXPERIMENTS: Electrolyte solution with bioactive elements (Na2SiO3-5H2O, C4H6O4Ca, NaNO3, and C3H7Na2O6P) was used as a precursor source to obtain a 45S5 bioglass-like composition on a Ti surface by PEO. Subsequently, the PEO-BG coating was investigated with respect to its surface, mechanical, tribological, electrochemical, microbiological, and biological properties, compared with those of machined and sandblasted/acid-etched control surfaces. FINDINGS: PEO treatment produced a coating with complex surface topography, Ti crystalline phases, superhydrophilic status, chemical composition, and oxide layer similar to that of 45S5-BG (~45.0Si, 24.5 Ca, 24.5Na, 6.0P w/v%). PEO-BG enhanced Ti mechanical and tribological properties with higher corrosion resistance. Furthermore, PEO-BG had a positive influence in polymicrobial biofilms, by reducing pathogenic bacterial associated with biofilm-related infections. PEO-BG also showed higher adsorption of blood plasma proteins without cytotoxic effects on human cells, and thus may be considered a promising biocompatible approach for biomedical implants.


Asunto(s)
Materiales Biocompatibles Revestidos , Titanio , Corrosión , Humanos , Oxidación-Reducción , Propiedades de Superficie
11.
Inorg Chem ; 59(11): 7666-7680, 2020 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-32338503

RESUMEN

The impact of Eu3+ doping at the Sr2+ and Sn4+ sites in SrSnO3 on its structural and electronic properties was studied and correlated with the photocatalytic efficiency. The compounds were synthesized using a modified Pechini method. Refinement of the synchrotron X-ray diffraction (S-XRD) data showed that the samples had an orthorhombic Pbnm symmetry. The incorporation of Eu into the lattice led to increased short- and long-range disorder, inducing additional distortion in the SnO6. XANES measurements revealed that mixed Eu valences (Eu3+ and Eu2+) were present in Eu-doped samples, and DFT calculations confirmed the presence of these ions at Sr2+/Sr4+ sites in the SrSnO3, resulting in changes in the electronic behavior. The catalytic performance toward Remazol yellow dye photodegradation and the catalysts' surface properties were also evaluated. The catalytic efficiency followed the order of Sr(Sn0.99Eu0.01)SnO3 > (Sr0.99Eu0.01)SnO3 > SrSnO3. The order was clearly related to selected-site doping that changed the degree of the inter- and intraoctahedral distortion and the introduction of different Eu midgap states, which apparently favor charge separation upon photoexcitation during photocatalysis. The results shown here are of great importance to the functionalization of SrSnO3 and other perovskite materials by lanthanoid ions, especially Eu3+, for effective applications as photocatalysts.

12.
Environ Technol ; 41(11): 1464-1476, 2020 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-30339515

RESUMEN

In this study, treatment for the removal of 1,4-dioxane by ozone and by catalytic ozonation using CuO as the catalyst was investigated. While the removal of 1,4-dioxane was small (20%) and mineralization negligible after 6 h of ozonation treatment, the removals of 1,4-dioxane and total organic carbon increased by factors of 10.35 and 81.25, respectively, after catalytic ozonation in the presence of CuO. The mineralization during catalytic ozonation was favoured at pH 10 (94.91 min-1), although it proceeded even at pH 3 (54.41 min-1). The CuO catalyst decreased the equilibrium concentration of soluble ozone and favoured its decomposition to reactive oxidative species. Radical scavenging experiments demonstrated that superoxide radicals were the main species responsible for the degradation of 1,4-dioxane. Further scavenging experiments with phosphate confirmed the presence of Lewis active sites on the surface of CuO, which were responsible for the adsorption and decomposition of ozone. The reaction mechanism proceeded through the formation of ethylene glycol diformate, which quickly hydrolyzed to ethylene glycol and formic acid as intermediate products. The stability of CuO indicated weak copper leaching and high catalytic activity for five recycling cycles. The toxicity of the water, assessed by Vibrio fischeri bioluminescence assays, remained the same (low toxicity) after catalytic ozonation while it increased after treatment with ozonation alone.


Asunto(s)
Ozono , Contaminantes Químicos del Agua , Purificación del Agua , Catálisis , Cobre , Dioxanos
13.
J Hazard Mater ; 384: 121416, 2020 02 15.
Artículo en Inglés | MEDLINE | ID: mdl-31699477

RESUMEN

The recovery of metals from wastewater is a recurrent problem due to numerous productive activities that produce wastewaters rich in toxic metals. Within this context, this research presents the study and optimization of copper recovery of real wastewater using pulsed electrodeposition. The studied parameters - method, current, temperature, and rotation- influence both the removal of Cu and the composition of the formed deposit, noting that the variation of these parameters enables the removal of copper with formation from crystalline oxides to crystalline copper in its metallic form. The process was optimized, and a 33.59% copper removal from a real wastewater with a deposition efficiency of 84.36% in 30 min was deemed optimal, using fast galvanic pulse, ton = 1 ms, 190 mA, 70 rpm, and 37 °C. For coating in the optimum point, a metallic and crystalline copper with 100% purity was obtained.

14.
ACS Appl Mater Interfaces ; 11(38): 35068-35078, 2019 Sep 25.
Artículo en Inglés | MEDLINE | ID: mdl-31469537

RESUMEN

3D printing technologies have been considered an important technology due to the ease manufacturing of objects, freedom of design, waste minimization, and fast prototyping. In chemistry, this technology potentializes the fabrication of conductive electrodes in large scale for sensing applications. Herein, we reported the modification of a 3D printed graphene electrode with Prussian blue. The modified electrode (3DGrE/PB) was characterized by microscopy (SEM and AFM) and spectroscopic techniques, and its electrochemical properties were compared to the traditional electrodes: glassy carbon, gold, and platinum. The 3DGrE/PB was used in the sensing of hydrogen peroxide in real-world samples of milk and mouthwash, and the results obtained according to the technique of batch-injection analysis were satisfactory for the concentration range typically found in such samples. Thus, 3DGrE/PB can be used as a new platform for sensing of molecular targets.

15.
Dalton Trans ; 48(15): 4811-4822, 2019 Apr 09.
Artículo en Inglés | MEDLINE | ID: mdl-30801085

RESUMEN

The search for earth-abundant metal-based catalysts for the oxygen evolution reaction (OER) that operates under neutral conditions is a challenge in the field of sustainable energy. Many strategies have been used, and coordination polymers with structures similar to Prussian blue appear to be interesting electrocatalysts due to their efficiency, stability and tunable properties. In this paper, a novel catalyst produced from a cobalt-pentacyanidoferrate precursor is presented and applied in studies of the OER. This material showed a high surface active area and electrocatalytic activity comparable to traditional cobalt hexacyanidoferrate. According to the theoretical calculations, the improvement of these properties is an effect of the framework arrangement and it is not caused by changes of the electronic structure. Further experimental evidence is necessary to determine the active species. However, our results of spin densities obtained from DFT calculations suggest that the active species for water oxidation is the radical Fe(iii)-CN-Co(iii)-O˙.

16.
Environ Sci Pollut Res Int ; 26(28): 28470-28480, 2019 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-30091076

RESUMEN

The alginate extraction residue (RES) from the Brazilian Sargassum filipendula was successfully employed as biosorbent in this binary equilibrium study, revealing a greater affinity and selectivity for Cr(III) than for Zn(II). Experimental results also revealed that the process is of endothermic nature and well adjusted by Langmuir-Freundlich binary model. The X-ray photoelectron spectroscopy (XPS) analysis revealed that coordination with hydroxyl groups of RES prevailed in Cr removal, followed by carboxyl-metal complexation. As far as Zn(II) is concerned, ion exchange with carboxylate groups of RES was the largest contributor. Nevertheless, scanning electron microscopy coupled with Fourier transform infrared spectroscopy indicated the participation of sulfate functions in a minor degree.


Asunto(s)
Cromo/análisis , Algas Marinas/química , Zinc/análisis , Adsorción , Brasil , Cromo/metabolismo , Intercambio Iónico , Espectroscopía de Fotoelectrones , Espectroscopía Infrarroja por Transformada de Fourier , Zinc/metabolismo
17.
J Hazard Mater ; 365: 581-589, 2019 03 05.
Artículo en Inglés | MEDLINE | ID: mdl-30469038

RESUMEN

Volatile organic compounds (VOCs) are responsible for environmental problems and may affect human health. Several treatment technologies minimize VOCs emissions; among those, catalytic oxidation appears as a promising alternative. In this study, a pilot-scale catalytic reactor was developed and the influence of process parameters on toluene degradation were investigated. Inlet gases were heated by electrical resistances and the catalyst employed was a honeycomb shape commercial automotive catalyst (Umicore, model AFT). Toluene degradation higher than 99% was achieved for several conditions and temperature showed to be the most important process variable for it. For all concentrations, it was observed that when increasing temperature led to a decrease on the space time. At 800 ppmv, varying from 543 K to 633 K, the space time decreased from 0.121 s to 0.08 s, respectively. At 1600 ppmv for the same temperature range, space time was reduced from 0.098 s to 0.040 s, respectively. At 2400 ppmv, varying from 543 K to 633 K, space time decreased from 0.081 s to 0.048 s. The catalytic reactor developed proved to be efficient for VOCs treatment, showing a high potential of application at industrial emission sources.

18.
J Prosthet Dent ; 121(3): 538-543, 2019 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-30503151

RESUMEN

STATEMENT OF PROBLEM: Maxillofacial prostheses made of silicone elastomers undergo undesirable color degradation over time. How this color change can be prevented is unclear. PURPOSE: The purpose of this in vitro study was to evaluate the ability of an oxide nanocoating to prevent color degradation of maxillofacial silicone elastomers after artificial accelerated aging. MATERIAL AND METHODS: A silicone elastomer with functional intrinsic pigment was tested. Specimens (N=20) were fabricated, and half of them were coated with a nanolayer of titanium dioxide (TiO2) using atomic layer deposition. Both coated and noncoated specimens (control) were exposed to artificial aging at 450 kJ/m2 of total energy. Changes in the color of all the specimens with and without TiO2 nanocoating were measured before and after the atomic layer deposition coating and before and after aging. The obtained color data were analyzed by using independent t tests and the 1-sample t test (α=.05). RESULTS: Color change (ΔE1=3.4 ±1.4) was observed for the silicone elastomers after the specimens were surface coated with TiO2 nanofilm, although this change was not statistically significant (P=.369) compared with the acceptability threshold (ΔE=3.0). Upon exposure to artificial aging, the noncoated control specimens underwent color change (ΔE2=2.5 ±0.7, P=.083 compared with the acceptability threshold). The specimens with TiO2 nanocoated surface experienced the least color change (ΔE3=1.4 ±0.6) when subjected to artificial aging, and this change was significantly lower (P<.001) than the established acceptability threshold of ΔE=3.0. In addition, the chemical analyses confirmed that the TiO2 nanocoating remained on the surface after exposure to artificial aging. CONCLUSIONS: TiO2 nanocoating was shown to be effective in reducing color degradation of the silicone elastomer exposed to artificial aging for 120 hours with 450 kJ/m2 of total energy.


Asunto(s)
Prótesis Maxilofacial , Coloración de Prótesis , Color , Ensayo de Materiales , Óxidos , Elastómeros de Silicona
19.
ACS Appl Mater Interfaces ; 9(45): 39830-39838, 2017 Nov 15.
Artículo en Inglés | MEDLINE | ID: mdl-29058402

RESUMEN

CoFe2O4 and NiFe2O4 nanoparticles (NPs) represent promising candidates for biomedical applications. However, in these systems, the knowledge over how various physical and chemical parameters influence their cytotoxicity remains limited. In this article, we investigated the effect of different calcination temperatures over cytotoxicity of CoFe2O4 and NiFe2O4 NPs, which were synthesized by a sol-gel proteic approach, toward L929 mouse fibroblastic cells. More specifically, we evaluated and compared CoFe2O4 and NiFe2O4 NPs presenting low crystallinity (that were calcined at 400 and 250 °C, respectively) with their highly crystalline counterparts (that were calcined at 800 °C). We found that the increase in the calcination temperature led to the reduction in the concentration of surface defect sites and/or more Co or Ni atoms located at preferential crystalline sites in both cases. A reduction in the cytotoxicity toward mouse fibroblast L929 cells was observed after calcination at 800 °C. Combining with inductively coupled plasma mass spectrometry data, our results indicate that the calcination temperature can be employed as a facile strategy to reduce the cytotoxicity of CoFe2O4 and NiFe2O4, in which higher temperatures contributed to the decrease in the dissolution of Co2+ or Ni2+ from the NPs. We believe these results may shed new insights into the various parameters that influence cytotoxicity in ferrite NPs, which may pave the way for their widespread applications in biomedicine.

20.
Dent Mater ; 33(11): 1244-1257, 2017 11.
Artículo en Inglés | MEDLINE | ID: mdl-28778495

RESUMEN

OBJECTIVE: The aim of this study was to develop binary and ternary titanium (Ti) alloys containing zirconium (Zr) and niobium (Nb) and to characterize them in terms of microstructural, mechanical, chemical, electrochemical, and biological properties. METHODS: The experimental alloys - (in wt%) Ti-5Zr, Ti-10Zr, Ti-35Nb-5Zr, and Ti-35Nb-10Zr - were fabricated from pure metals. Commercially pure titanium (cpTi) and Ti-6Al-4V were used as controls. Microstructural analysis was performed by means of X-ray diffraction and scanning electron microscopy. Vickers microhardness, elastic modulus, dispersive energy spectroscopy, X-ray excited photoelectron spectroscopy, atomic force microscopy, surface roughness, and surface free energy were evaluated. The electrochemical behavior analysis was conducted in a body fluid solution (pH 7.4). The albumin adsorption was measured by the bicinchoninic acid method. Data were evaluated through one-way ANOVA and the Tukey test (α=0.05). RESULTS: The alloying elements proved to modify the alloy microstructure and to enhance the mechanical properties, improving the hardness and decreasing the elastic modulus of the binary and ternary alloys, respectively. Ti-Zr alloys displayed greater electrochemical stability relative to that of controls, presenting higher polarization resistance and lower capacitance. The experimental alloys were not detrimental to albumin adsorption. SIGNIFICANCE: The experimental alloys are suitable options for dental implant manufacturing, particularly the binary system, which showed a better combination of mechanical and electrochemical properties without the presence of toxic elements.


Asunto(s)
Aleaciones Dentales/síntesis química , Implantes Dentales , Niobio/química , Titanio/química , Circonio/química , Albúminas/química , Materiales Biocompatibles/síntesis química , Módulo de Elasticidad , Electroquímica , Dureza , Ensayo de Materiales , Microscopía de Fuerza Atómica , Microscopía Electrónica de Rastreo , Espectroscopía de Fotoelectrones , Espectrometría por Rayos X , Difracción de Rayos X
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