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Caro‐Briones R, García‐Pérez BE, Báez‐Medina H, San Martín‐Martínez E, Martínez‐Mejía G, Jiménez‐Juárez R, Martínez‐Gutiérrez H, Corea M. Influence of monomeric concentration on mechanical and electrical properties of poly(styrene‐
co
‐acrylonitrile) and poly(styrene‐
co
‐acrylonitrile/acrylic acid) yarns electrospun. J Appl Polym Sci 2020. [DOI: 10.1002/app.49166] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Rubén Caro‐Briones
- Escuela Superior de Ingeniería Química e Industrias Extractivas, Instituto Politécnico Nacional, Av. Luis Enrique Erro S/N, Unidad Profesional Adolfo López Mateos, Zacatenco Ciudad de México México
| | - Blanca Estela García‐Pérez
- Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Unidad Profesional Lázaro Cárdenas Prolongación de Carpio y Plan de Ayala S/N Col. Santo Tomas Ciudad de México México
| | - Héctor Báez‐Medina
- Centro de Investigación en ComputaciónInstituto Politécnico Nacional, Av. Juan de Dios Bátiz, Esq. Miguel Othón de Mendizábal, Col. Nueva Industrial Vallejo Ciudad de México México
| | - Eduardo San Martín‐Martínez
- Centro de Investigación en Ciencia Aplicada y Tecnología AvanzadaInstituto Politécnico Nacional Ciudad de México México
| | - Gabriela Martínez‐Mejía
- Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Unidad Profesional Lázaro Cárdenas Prolongación de Carpio y Plan de Ayala S/N Col. Santo Tomas Ciudad de México México
| | - Rogelio Jiménez‐Juárez
- Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Unidad Profesional Lázaro Cárdenas Prolongación de Carpio y Plan de Ayala S/N Col. Santo Tomas Ciudad de México México
| | - Hugo Martínez‐Gutiérrez
- Centro de Nanociencias y Micro‐NanotecnologíasInstituto Politécnico Nacional, Av. Luis Enrique Erro S/N, Unidad Profesional Adolfo López Mateos, Zacatenco Ciudad de México México
| | - Mónica Corea
- Escuela Superior de Ingeniería Química e Industrias Extractivas, Instituto Politécnico Nacional, Av. Luis Enrique Erro S/N, Unidad Profesional Adolfo López Mateos, Zacatenco Ciudad de México México
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Li W, Wang Q, Xu J, Aussenac F, Qi G, Zhao X, Gao P, Wang C, Deng F. Probing the surface of γ-Al 2O 3 by oxygen-17 dynamic nuclear polarization enhanced solid-state NMR spectroscopy. Phys Chem Chem Phys 2018; 20:17218-17225. [PMID: 29900471 DOI: 10.1039/c8cp03132k] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
γ-Al2O3 is an important catalyst and catalyst support of industrial interest. Its acid/base characteristics are correlated to the surface structure, which has always been an issue of concern. In this work, the complex (sub-)surface oxygen species on surface-selectively labelled γ-Al2O3 were probed by 17O dynamic nuclear polarization surface-enhanced NMR spectroscopy (DNP-SENS). Direct 17O MAS and indirect 1H-17O cross-polarization (CP)/MAS DNP experiments enable observation of the (sub-)surface bare oxygen species and hydroxyl groups. In particular, a two-dimensional (2D) 17O 3QMAS DNP spectrum was for the first time achieved for γ-Al2O3, in which two O(Al)4 and one O(Al)3 bare oxygen species were identified. The 17O isotropic chemical shifts (δcs) vary from 56.7 to 81.0 ppm and the quadrupolar coupling constants (CQ) range from 0.6 to 2.5 MHz for the three oxygen species. The coordinatively unsaturated O(Al)3 species is characterized by a higher field chemical shift (56.7 ppm) and the largest CQ value (2.5 MHz) among these oxygen sites. 2D 1H → 17O HETCOR DNP experiments allow us to discriminate three bridging (Aln)-μ2-OH and two terminal (Aln)-μ1-OH hydroxyl groups. The structural features of the bare oxygen species and hydroxyl groups are similar for the γ-Al2O3 samples isotopically labelled by 17O2 gas or H217O. The results presented here show that the combination of surface-selective labelling and DNP-SENS is an effective approach for characterizing oxides with complex surface species.
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Affiliation(s)
- Wenzheng Li
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, P. R. China.
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Dong J, Wang J, Shi L, Yang J, Wang J, Shan B, Shen M. Hydrogenous spinel γ-alumina structure. Phys Chem Chem Phys 2017; 19:27389-27396. [PMID: 28972601 DOI: 10.1039/c7cp04704e] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The structure of γ-Al2O3 is still under debate. Here we report a H spinel structure evolved from pseudo-boehmite. A unit cell with two octahedral cationic vacancies and one bulk H was preferential in terms of calculated Gibbs energy, which was well consistent with experimental data. Bulk H was found to migrate out with elevated temperatures. Through calculating the migration barriers of every step, we observed that the "hopping" step was rate-determining. The hopping rates were further estimated by assuming a Boltzmann distribution of energies, and as a result they increased by 2 to 3 orders of magnitude from 500 °C to 800 °C. This investigation will encourage us to study more uncertainties in material structures.
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Affiliation(s)
- Jinshi Dong
- Key Laboratory for Green Chemical Technology of State Education Ministry, School of Chemical Engineering & Technology, Tianjin University, Tianjin 300072, P. R. China.
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Xin S, Wang Q, Xu J, Feng N, Li W, Deng F. Heteronuclear correlation experiments of 23Na- 27Al in rotating solids. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2017; 84:103-110. [PMID: 28159456 DOI: 10.1016/j.ssnmr.2017.01.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 12/21/2016] [Accepted: 01/17/2017] [Indexed: 06/06/2023]
Abstract
We demonstrated that the heteronuclear correlation experiments between two quadrupolar nuclei, 23Na and 27Al, with close Larmor frequencies can be achieved via D-HMQC and D-RINEPT approaches by using a diplexer connected to a conventional probe in magic-angle-spinning solid-state NMR. Low-power heteronuclear dipolar recoupling schemes can be applied on 23Na or 27Al to establish polarization transfers between the central transitions of 23Na and 27Al for a model compound, NaAlO2. Further, we showed a practical implementation of the two dimensional 23Na-27Al dipolar-based heteronuclear correlation experiment on a heterogeneous catalyst, Na2CO3/γ-Al2O3. This allows to determine spatial proximities between different 23Na and 27Al sites, thus the surface Na species adjacent to octahedral-coordination Al can be clearly discriminated.
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Affiliation(s)
- Shaohui Xin
- National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Key Laboratory of Magnetic Resonance in Biological Systems, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China
| | - Qiang Wang
- National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Key Laboratory of Magnetic Resonance in Biological Systems, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China.
| | - Jun Xu
- National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Key Laboratory of Magnetic Resonance in Biological Systems, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China
| | - Ningdong Feng
- National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Key Laboratory of Magnetic Resonance in Biological Systems, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China
| | - Wenzheng Li
- National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Key Laboratory of Magnetic Resonance in Biological Systems, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China
| | - Feng Deng
- National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Key Laboratory of Magnetic Resonance in Biological Systems, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China.
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Surface oxide net charge of a titanium alloy: comparison between effects of treatment with heat or radiofrequency plasma glow discharge. Colloids Surf B Biointerfaces 2010; 82:173-81. [PMID: 20880672 DOI: 10.1016/j.colsurfb.2010.08.031] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2010] [Revised: 08/18/2010] [Accepted: 08/23/2010] [Indexed: 11/21/2022]
Abstract
In the current study, we have compared the effects of heat and radiofrequency plasma glow discharge (RFGD) treatment of a Ti6Al4V alloy on the physico-chemical properties of the alloy's surface oxide. Titanium alloy (Ti6Al4V) disks were passivated alone, heated to 600 °C, or RFGD plasma treated in pure oxygen. RFGD treatment did not alter the roughness, topography, elemental composition or thickness of the alloy's surface oxide layer. In contrast, heat treatment altered oxide topography by creating a pattern of oxide elevations approximately 50-100 nm in diameter. These nanostructures exhibited a three-fold increase in roughness compared to untreated surfaces when RMS roughness was calculated after applying a spatial high-pass filter with a 200 nm-cutoff wavelength. Heat treatment also produced a surface enrichment in aluminum and vanadium oxides. Both RFGD and heat treatment produced similar increases in oxide wettability. Atomic force microscopy (AFM) measurements of metal surface oxide net charge signified by a long-range force of attraction to or repulsion from a (negatively charged) silicon nitride AFM probe were also obtained for all three experimental groups. Force measurements showed that the RFGD-treated Ti6Al4V samples demonstrated a higher net positive surface charge at pH values below 6 and a higher net negative surface charge at physiological pH (pH values between 7 and 8) compared to control and heat-treated samples. These findings suggest that RFGD treatment of metallic implant materials can be used to study the role of negatively charged surface oxide functional groups in protein bioactivity, osteogenic cell behavior and osseointegration independently of oxide topography.
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Yang J, Zheng A, Zhang M, Luo Q, Yue Y, Ye C, Lu X, Deng F. Brönsted and Lewis Acidity of the BF3/γ-Al2O3 Alkylation Catalyst as Revealed by Solid-State NMR Spectroscopy and DFT Quantum Chemical Calculations. J Phys Chem B 2005; 109:13124-31. [PMID: 16852633 DOI: 10.1021/jp051268l] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Multinuclear solid-state NMR techniques and DFT quantum chemical calculations were employed to investigate the detailed structure of acid sites on the BF3/gamma-Al2O3 alkylation catalyst. The NMR experiment results indicate that gaseous BF3 is able to react with the hydroxyl groups present on the surface of gamma-Al2O3, leading to the formation of new Brönsted and Lewis acid sites. The 1H/11B and 1H/27Al TRAPDOR (TRAnsfer of Population in DOuble Resonance) experiments suggest that the 3.7 ppm signal in 1H NMR spectra of the BF3/gamma-Al2O3 catalyst is due to a bridging B-OH-Al group that acts as a Brönsted acid site of the catalyst. On the other hand, a Lewis acid site on the surface of the catalysts, as revealed by 31P MAS and 31P/27Al TRAPDOR NMR of adsorbed trimethylphosphine, is associated with three-coordinate -OBF2 species. 13C NMR of adsorbed 2-13C-acetone indicates that the Brönsted acid strength of the catalyst is slightly stronger than that of zeolite HZSM-5 but still weaker than that of 100% H2SO4, which is in good agreement with theoretical prediction. In addition, DFT calculations also reveal the detailed structure of various acid sites formed on the BF3/gamma-Al2O3 catalyst and the interaction of probe molecules with these sites.
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Affiliation(s)
- Jun Yang
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, The Chinese Academy of Sciences, Wuhan 430071, People's Republic of China
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MacDonald DE, Rapuano BE, Deo N, Stranick M, Somasundaran P, Boskey AL. Thermal and chemical modification of titanium–aluminum–vanadium implant materials: effects on surface properties, glycoprotein adsorption, and MG63 cell attachment. Biomaterials 2004; 25:3135-46. [PMID: 14980408 DOI: 10.1016/j.biomaterials.2003.10.029] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2003] [Accepted: 09/29/2003] [Indexed: 10/26/2022]
Abstract
The microstructure, chemical composition and wettability of thermally and chemically modified Ti-6Al-4V alloy disks were characterized and correlated with the degree of radiolabeled fibronectin-alloy surface adsorption and subsequent adhesion of osteoblast-like cells. Heating either in pure oxygen or atmosphere (atm) resulted in an enrichment of Al and V within the surface oxide. Heating (oxygen/atm) and peroxide treatment both followed by butanol treatment resulted in a reduction in content of V, but not in Al. Heating (oxygen/atm) or peroxide treatment resulted in a thicker oxide layer and a more hydrophilic surface when compared with passivated controls. Post-treatment with butanol, however, resulted in less hydrophilic surfaces than heating or peroxide treatment alone. The greatest increases in the adsorption of radiolabeled fibronectin following treatment were observed with peroxide/butanol-treated samples followed by peroxide/butanol and heat/butanol, although binding was only increased by 20-40% compared to untreated controls. These experiments with radiolabeled fibronectin indicate that enhanced adsorption of the glycoprotein was more highly correlated with changes in chemical composition, reflected in a reduction in V content and decrease in the V/Al ratio, than with changes in wettability. Despite promoting only a modest elevation in fibronectin adsorption, the treatment of disks with heat or heat/butanol induced a several-fold increase in the attachment of MG63 cells promoted by a nonadhesive concentration of fibronectin that was used to coat the pretreated disks compared to uncoated disks. Therefore, results obtained with these modifications of surface properties indicate that an increase in the absolute content of Al and/or V (heat), and/or in the Al/V ratio (with little change in hydrophilicity; heat+butanol) is correlated with an increase in the fibronectin-promoted adhesion of an osteoblast-like cell line. It would also appear that the thermal treatment-induced enhancement of cell adhesion in the presence of this integrin-binding protein is due to its increased biological activity, rather than a mass effect alone, that appear to be associated with changes in chemical composition of the metallic surface. Future studies will investigate the influence of the surface chemical composition of various implantable alloys on protein adsorption and receptor-mediated cell adhesion. In addition, by altering the properties of bound osteogenic protein enhancing exposure to cell integrin binding domains, it may be possible to develop implant surfaces which enhance the attachment, adhesion and developmental response of osteoblast precursors leading to accelerated osseointegration.
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Affiliation(s)
- D E MacDonald
- Langmuir Center for Colloids and Interfaces, School of Engineering, Columbia University, New York, NY 10027, USA.
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Luo Q, Deng F, Yuan Z, Yang J, Zhang M, Yue Y, Ye C. Using Trimethylphosphine as a Probe Molecule to Study the Acid Sites in Al−MCM-41 Materials by Solid-State NMR Spectroscopy. J Phys Chem B 2002. [DOI: 10.1021/jp0213093] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Qing Luo
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Science, Wuhan 430071, People's Republic of China, and Beijing Laboratory of Electron Microscopy, Institute of Physics and Center for Condensed Matter Physics, Chinese Academy of Science, Beijing 100080, People's Republic of China
| | - Feng Deng
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Science, Wuhan 430071, People's Republic of China, and Beijing Laboratory of Electron Microscopy, Institute of Physics and Center for Condensed Matter Physics, Chinese Academy of Science, Beijing 100080, People's Republic of China
| | - Zhongyong Yuan
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Science, Wuhan 430071, People's Republic of China, and Beijing Laboratory of Electron Microscopy, Institute of Physics and Center for Condensed Matter Physics, Chinese Academy of Science, Beijing 100080, People's Republic of China
| | - Jun Yang
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Science, Wuhan 430071, People's Republic of China, and Beijing Laboratory of Electron Microscopy, Institute of Physics and Center for Condensed Matter Physics, Chinese Academy of Science, Beijing 100080, People's Republic of China
| | - Mingjin Zhang
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Science, Wuhan 430071, People's Republic of China, and Beijing Laboratory of Electron Microscopy, Institute of Physics and Center for Condensed Matter Physics, Chinese Academy of Science, Beijing 100080, People's Republic of China
| | - Yong Yue
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Science, Wuhan 430071, People's Republic of China, and Beijing Laboratory of Electron Microscopy, Institute of Physics and Center for Condensed Matter Physics, Chinese Academy of Science, Beijing 100080, People's Republic of China
| | - Chaohui Ye
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Science, Wuhan 430071, People's Republic of China, and Beijing Laboratory of Electron Microscopy, Institute of Physics and Center for Condensed Matter Physics, Chinese Academy of Science, Beijing 100080, People's Republic of China
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Deng F, Yue Y, Ye C. “NMR invisible” aluminum species in dealuminated mordenite zeolite: a1H/27 AI TRAPDOR NMR study. ACTA ACUST UNITED AC 1998. [DOI: 10.1007/bf02877800] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Deng F, Yue Y, Ye C. 1H/27Al TRAPDOR NMR studies on aluminum species in dealuminated zeolites. SOLID STATE NUCLEAR MAGNETIC RESONANCE 1998; 10:151-160. [PMID: 9550343 DOI: 10.1016/s0926-2040(97)00028-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Aluminum species in several dealuminated zeolites (ultrastable HY, HZSM-5 and mordenite) were investigated in detail by means of the newly introduced 1H/27Al TRAPDOR method in combination with 27Al MAS NMR, and the quadrupole coupling constants (Q[CC]s) for aluminum atoms associated with these species were obtained. A signal at ca. 6.8 ppm, due to water molecules adsorbed on Lewis acid sites, was observed in the 1H MAS spectra for all the three zeolites. The TRAPDOR NMR provides direct evidence that there is a strong interaction between the adsorbed water molecules and the aluminum atoms of the Lewis-acid sites. The Q(CC) values for this aluminum species of 8.3, 6.7 and 11.3 MHz were determined from the TRAPDOR profiles for the ultrastable HY, HZSM-5 and mordenite zeolites, respectively. The Q(CC)s calculated from the TRAPDOR curves are usually larger than 10 MHz for both Bronsted-acid sites (SiOHAI) and non-framework aluminum species in the three zeolites. Three narrow peaks at 54, 30 and 0 ppm are separately superimposed on a broad hump in the 27Al MAS spectra of the three dehydrated zeolites, while the latter is associated with the 'NMR invisible' Al. The NMR experimental results suggest that the three kinds of aluminum species (non-framework aluminum species, Bronsted- and Lewis-acid sites) are all responsible for the resonance of the broad hump in dehydrated zeolites, which makes it difficult to explain the 27Al MAS spectra. Fortunately, the TRAPDOR NMR provides a direct method for individually studying different aluminum species with large Q(CC)s via their dipolar coupling to nearby proton nuclei.
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Affiliation(s)
- F Deng
- Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics, the Chinese Academy of Sciences
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