Mesoporous Iron(III)-Doped Hydroxyapatite Nanopowders Obtained via Iron Oxalate

Mesoporous hydroxyapatite (HA) and iron(III)-doped HA (Fe-HA) are attractive materials for biomedical, catalytic, and environmental applications. In the present study, the nanopowders of HA and Fe-HA with a specific surface area up to 194.5 m2/g were synthesized by a simple precipitation route using iron oxalate as a source of Fe3+ cations. The influence of Fe3+ amount on the phase composition, powders morphology, Brunauer–Emmett–Teller (BET) specific surface area (S), and pore size distribution were investigated, as well as electron paramagnetic resonance and Mössbauer spectroscopy analysis were performed. According to obtained data, the Fe3+ ions were incorporated in the HA lattice, and also amorphous Fe oxides were formed contributed to the gradual increase in the S and pore volume of the powders. The Density Functional Theory calculations supported these findings and revealed Fe3+ inclusion in the crystalline region with the hybridization among Fe-3d and O-2p orbitals and a partly covalent bond formation, whilst the inclusion of Fe oxides assumed crystallinity damage and rather occurred in amorphous regions of HA nanomaterial. In vitro tests based on the MG-63 cell line demonstrated that the introduction of Fe3+ does not cause cytotoxicity and led to the enhanced cytocompatibility of HA.

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Time-Resolved X-ray Operando Observations of Lithiation Gradients across the Cathode Matrix and Individual Oxide Particles during Fast Cycling of a Li-Ion Cell

Journal of The Electrochemical Society ◽

10.1149/1945-7111/ac393f ◽

2021 ◽

Author(s):

Tianlong Zheng ◽

Jing He ◽

Pingwei Cai ◽

Xi Liu ◽

Duojie Wu ◽

...

Keyword(s):

Electronic Structure ◽

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

High Performance ◽

Density Functional ◽

Density Functional Theory Calculations ◽

Carbon Paper ◽

Free Energy Barrier ◽

Active Components

Abstract Self-supporting three-dimensional (3D) transition metal electrodes have been considered for designing high-performance non-noble metal oxygen evolution reaction (OER) catalysts owing to their advantages such as binder-free, good mass transfer, and large specific surface area. However, the poor conductivity of ((oxy)hydr)oxides and the difficulty in adjusting their electronic structure limit their application. As an alternative strategy, instead of constituting the array electrode by the active components themselves, we herein report 3D Co(OH)2@MnO2 heterostructure decorated carbon nanoarrays grown directly on carbon paper (Co(OH)2@MnO2-CNAs). This unique structure can not only enhance electrical conductivity but also provide a larger specific surface area, and facilitate electrolyte diffusion and ion transport. The core-shell heterostructured Co(OH)2@MnO2 formed via incorporation with MnO2 facilitates the transition of CoII to CoIII in Co(OH)2 and it increases the storage of oxidative charge in the catalyst, leading to an OER activity with benchmark RuO2 and good stability. Density functional theory calculations suggest that the improved OER performance can be attributed to the formation of the heterojunction structure, resulting in the modulation of the electronic structure of Co atoms and the reduction of the free energy barrier of the rate-determining step for the OER.

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Surface Analysis of Etched Molar Enamel by Gas Adsorption

Journal of Dental Research ◽

10.1177/154405910808700607 ◽

2008 ◽

Vol 87 (6) ◽

pp. 532-536 ◽

Cited By ~ 5

Author(s):

M.F. Orellana ◽

A.E. Nelson ◽

J.P.R. Carey ◽

G. Heo ◽

D.G Boychuk ◽

...

Keyword(s):

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Gas Adsorption ◽

Third Molar ◽

Dental Enamel ◽

Total Surface Area ◽

Gas Absorption ◽

Etch Pattern

Much research has been devoted to the study of etched enamel, since it is critical to bonding. Currently, there are no precise data regarding the etched-enamel specific surface area. The aim of this study was to characterize, by two different methods, the surface of human dental enamel in vitro after being etched. It was hypothesized that differences would be observed between specimens in terms of specific surface area and grade of etching. Sixteen third molar enamel samples were etched for 30 sec with 37% phosphoric acid prior to being viewed by SEM. Etched enamel surfaces were graded according to the Galil and Wright classification. The total surface area of etched samples was determined by the BET gas absorption method. A substantial variability in total surface area was observed between and among samples. A Pearson’s Correlation Coefficient showed a lack of relationship between etch pattern and total surface area.

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Physicochemical and Biological Characterization of Ti6Al4V Particles Obtained by Implantoplasty: An In Vitro Study. Part I

Materials ◽

10.3390/ma14216507 ◽

2021 ◽

Vol 14 (21) ◽

pp. 6507

Author(s):

Jorge Toledano-Serrabona ◽

Francisco Javier Gil ◽

Octavi Camps-Font ◽

Eduard Valmaseda-Castellón ◽

Cosme Gay-Escoda ◽

...

Keyword(s):

Cell Viability ◽

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

In Vitro Study ◽

Vitro Study ◽

Equivalent Diameter ◽

Metal Debris ◽

Aluminum Ions

Implantoplasty is a mechanical decontamination technique that consists of polishing the supra-osseous component of the dental implant with peri-implantitis. This technique releases metal particles in the form of metal swarf and dust into the peri-implant environment. In the present in vitro study, the following physicochemical characterization tests were carried out: specific surface area, granulometry, contact angle, crystalline structure, morphology, and ion release. Besides, cytotoxicity was in turn evaluated by determining the fibroblastic and osteoblastic cell viability. As a result, the metal debris obtained by implantoplasty presented an equivalent diameter value of 159 µm (range 6–1850 µm) and a specific surface area of 0.3 m2/g on average. The particle had a plate-like shape of different sizes. The release of vanadium ions in Hank’s solution at 37 °C showed no signs of stabilization and was greater than that of titanium and aluminum ions, which means that the alloy suffers from a degradation. The particles exhibited cytotoxic effects upon human osteoblastic and fibroblastic cells in the whole extract. In conclusion, metal debris released by implantoplasty showed different sizes, surface structures and shapes. Vanadium ion levels were higher than that those of the other metal ions, and cell viability assays showed that these particles produce a significant loss of cytocompatibility on osteoblasts and fibroblasts, which means that the main cells of the peri-implant tissues might be injured.

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CCCM SPECIFIC SURFACE ESTIMATION IN PROCESS OF LOW-TEMPERATURE OXIDATION

Periódico Tchê Química ◽

10.52571/ptq.v17.n34.2020.817_p34_pgs_793_802.pdf ◽

2020 ◽

Vol 17 (34) ◽

pp. 793-802

Author(s):

Veniamin A POGODIN ◽

Alexey N ASTAPOV ◽

Lev N RABINSKIY

Keyword(s):

Low Temperature ◽

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Carbon Fibers ◽

Density Functional ◽

Functional Model ◽

Contact Boundary ◽

Low Temperature Oxidation ◽

Temperature Oxidation

The low-temperature oxidation process of carbon-carbon composite materials (CCCM) with a pyrocarbon matrix has been examined. Oxidation at temperatures of 450 to 700 °C is characterized by internal burnout of the carbon phase without a noticeable change in the experimental samples external volume. Oxidation resistance analysis of CCCM structural components was performed. CCCM and carbon fibers specific surface area were estimated by the low-temperature adsorption of nitrogen and krypton using the Brunauer-Emmett-Teller model and the theory of density functional model. Pore size distribution was calculated by the semi-empirical Horvath-Kawazoe method. A significant increase (about 10-15 times) in specific surface area of the composite material, together with a rise in free volume ~5%, was accompanied by total weight loss of about 5%. Specific surface area changes occur as a result of anisotropic etching of carbon fibers surface with the formation of micropores with 0.5–2.0 nm diameter range. Although macropores are formed mainly due to the oxidation of thermosetting binder pyrolysis residue, they do not contribute to the specific surface increase but solely provide access to micropores. Microporosity evolution leads to an increase of structural discontinuity degree and, ultimately, to the loss of matrix-filler contact boundary. As a result, an overall weakening of material mechanical characteristics is to be noted. Thus, oxidative degradation is closely related to the increase in void space. A follow-up study is on-going. In fact, an open question remains, namely whether the oxidative process occurs differently in the micropores of diameter less than 2 nm and how it may contribute to the oxidative stress resistance behavior of CCCM.

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