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991.
Surface modification of titanium with thermally treated polydimethylsiloxane coating and the effect on resin to titanium adhesion 下载免费PDF全文
Christie Y. K. Lung Markku Heinonen Edwin Kukk Jukka P. Matinlinna 《Surface and interface analysis : SIA》2015,47(1):105-112
In this study, titanium surface modification by a thermal treatment using a polydimethylsiloxane (PDMS) coating was investigated. The surfaces of four titanium samples were surface treated by polishing, sandblasting, and coating with a PDMS with a thermal treatment at 800 and 1100 °C. The titanium surfaces were characterized by X‐ray photoelectron spectroscopy (XPS) and atomic force microscopy. The effect of the surface treatments on adhesion of resin to titanium was assessed by shear adhesion strength test. XPS analysis showed that there was a change of elemental composition of titanium surfaces after surface treatment. Binding energy shifts for Si2p and O1s were observed after sandblasting and thermally treated PDMS. Therefore, chemical states of Si and O were changed. Atomic force microscopy analysis revealed that the surface topography of the Ti samples was different, and surface roughness was increased after sandblasting and thermal treatment of PDMS coating. Shear adhesion strength test results showed that the adhesion between resin and titanium is affected by the treatment temperature of PDMS coating. The highest adhesion is obtained at 1100 °C (14.7 ± 1.57 MPa). Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
992.
Radaram B Ivie JA Singh WM Grudzien RM Reibenspies JH Webster CE Zhao X 《Inorganic chemistry》2011,50(21):10564-10571
The synthesis, characterization, and water oxidation activity of mononuclear ruthenium complexes with tris(2-pyridylmethyl)amine (TPA), tris(6-methyl-2-pyridylmethyl)amine (Me(3)TPA), and a new pentadentate ligand N,N-bis(2-pyridinylmethyl)-2,2'-bipyridine-6-methanamine (DPA-Bpy) have been described. The electrochemical properties of these mononuclear Ru complexes have been investigated by both experimental and computational methods. Using Ce(IV) as oxidant, stoichiometric oxidation of water by [Ru(TPA)(H(2)O)(2)](2+) was observed, while Ru(Me(3)TPA)(H(2)O)(2)](2+) has much less activity for water oxidation. Compared to [Ru(TPA)(H(2)O)(2)](2+) and [Ru(Me(3)TPA)(H(2)O)(2)](2+), [Ru(DPA-Bpy)(H(2)O)](2+) exhibited 20 times higher activity for water oxidation. This study demonstrates a new type of ligand scaffold to support water oxidation by mononuclear Ru complexes. 相似文献
993.
Density and ultrasonic speed of four amino acids (glycine, l-alanine, l-valine, and l-leucine) in aqueous sodium fluoride solutions {(0.1 to 0.5) M} have been measured at T = (308.15, 313.15, and 318.15) K. Apparent molar volumes (Vφ), partial molar volumes , transfer volumes and hydration number (nH) are evaluated using density data. Adiabatic compressibility (βs), change (Δβs), and relative change in compressibility (Δβs/β0), apparent molar compressibility (Kφ), partial molar compressibility , transfer compressibility , and hydration number (nH) have been calculated using ultrasonic speed data. The linear correlation of and for a homologous series of amino acids have been used utilised to calculate the contribution of charged end groups (, COO?), CH2 group and other alkyl chain of the amino acids. The analysis shows that the ion–ion interactions are much stronger than ion–hydrophobic interactions over the entire concentration range of sodium fluoride. It is observed that sodium fluoride has a strong dehydration effect on amino acids. 相似文献
994.
Larissa Brentano CapelettiClaudio Radtke João Henrique Z. Dos Santos Edwin MoncadaZenis N. Da Rocha Iuri Muniz Pepe 《Colloids and surfaces. A, Physicochemical and engineering aspects》2011,392(1):256-263
Solid acid-base sensors were prepared by encapsulating two pH indicators (brilliant yellow or acridine) within a silica matrix by the sol-gel method using three different routes: (1) non-hydrolytic, (2) acid catalyzed and (3) base catalyzed. The interactions of the silica-indicator with the resulting materials were then investigated by cyclic and differential pulse voltammetry. Complementary, ultraviolet-visible, photoacoustic spectroscopy was employed for the characterization of the interactions by monitoring the band shifts (bathochromic or hypsochromic, depending on the sol-gel route) between the neat pH indicators and those encapsulated within the silica network. Furthermore, X-ray photoelectron spectroscopy showed that the N 1s binding energy in brilliant yellow was shifted for the material resulting from the acid route. The electrochemical behavior and the pH indicator interactions with the silica network were dependent on the nature of the employed sol-gel route. For the sensors prepared with acridine, the interactions with the silica network took place through the nitrogen group from the pyridinic ring. For the brilliant yellow indicator, different behaviors were observed depending on the route, suggesting different processes during preparation or analysis. For the basic catalyzed and non-hydrolytic routes, it was not possible to assign a specific interaction. Nevertheless, it seemed that interactions might have taken place through the hydroxyl and/or sulphonic groups. Furthermore, for the brilliant yellow sensor prepared through the acid route, it was possible to show that the interaction probably or partially occurred through the azo groups. 相似文献
995.
Tan YS Chen S Hong WM Kan JM Kwek ES Lim SY Lim ZH Tessensohn ME Zhang Y Webster RD 《Physical chemistry chemical physics : PCCP》2011,13(28):12745-12754
The phenol, α-tocopherol, can be electrochemically oxidised in a -2e(-)/-H(+) process to form a diamagnetic cation that is long-lived in dry organic solvents such as acetonitrile and dichloromethane, but in the presence of water quickly reacts to form a hemiketal. Variable scan rate cyclic voltammetry experiments in acetonitrile with carefully controlled amounts of water between 0.010 M-0.6 M were performed in order to determine the rate of reaction of the diamagnetic cation with water. The water content of the solvent was accurately determined by Karl Fischer coulometric titrations and the voltammetric data were modelled using digital simulation techniques. The oxidation peak potential of α-tocopherol measured during cyclic voltammetry experiments was found to shift to less positive potentials as increasing amounts of water (0.01-0.6 M) were added to the acetonitrile, which was interpreted based on hydrogen-bonding interactions between the phenolic hydrogen atom and water. Several other phenols were examined and they displayed similar voltammetric features to α-tocopherol, suggesting that interactions of phenols with trace amounts of water were a common occurrence in acetonitrile. The H-bonding interactions of α-tocopherol with water were also examined via NMR and UV-vis spectroscopies, with the voltammetric and spectroscopic studies extended to include other coordinating solvents (dimethyl sulfoxide and pyridine). 相似文献
996.
Lee SE Chess EK Rabinow B Ray GJ Szabo CM Melnick B Miller RL Nair LM Moore EG 《Analytical and bioanalytical chemistry》2011,399(2):651-662
This article addresses the identification and quantification of the chemical species resulting in resonances at 2.17 and 2.25 ppm
in the 1H nuclear magnetic resonance (NMR) spectrum of pharmaceutical-grade heparin sodium. The NMR signals in question were first
confirmed to arise from chemical moieties covalently attached to the heparin molecule through NMR diffusion experiments as
well as chemical treatment of heparin active pharmaceutical ingredient (API) containing the resonances. The material responsible
for the extra NMR signals was then demonstrated by NMR spiking studies to be something other than oversulfated chondroitin
sulfate and was finally identified as an O-acetylation product of heparin through 13C labeling experiments with subsequent NMR analysis. The extent of O-acetylation was quantified using three orthogonal techniques: 1H NMR, ion chromatography, and headspace gas chromatography/mass spectrometry. The results of this work showed good agreement
between the three quantitative methods developed to analyze the signals in the United States Pharmacopeia-specified region
of 2.12–3.00 ppm for heparin API. 相似文献
997.
Tony Bhle Frank Eissmann Edwin Weber Florian O. R. L. Mertens 《Acta Crystallographica. Section C, Structural Chemistry》2011,67(1):m5-m8
The title compounds, [Mn(C10H8O6)]n and [Zn(C10H8O6)]n, are isomorphous coordination polymers prepared from 2,5‐dimethoxyterephthalic acid (H2dmt) and the respective metal(II) salts. Both complexes form three‐dimensional metal–organic frameworks with each MII centre bridged by four 2,5‐dimethoxyterephthalate (dmt2−) anions, resulting in the same type of network topology. The asymmetric unit consists of one MII cation on a twofold axis and one half of a dmt2− anion (located on a centre of inversion). In the crystal structure, the MII centres are coordinated in a rather unusual way, as there is a distorted tetrahedral inner coordination sphere formed by four carboxylate O atoms of four different dmt2− anions, and an additional outer coordination sphere formed by two methoxy and two carboxylate O atoms, with each of the O atoms belonging to one of the four different dmt2− anions forming the inner coordination sphere. Consideration of both coordination spheres results in a super‐dodecahedral coordination geometry for the MII centres. Besides the numerous MII...O interactions, both structures are further stabilized by weak C—H...O contacts. 相似文献
998.
The importance of mechanotransduction for physiological systems is becoming increasingly recognized. The effect of mechanical stimulation is well studied in organs and tissues, for instance by using flexible tissue culture substrates that can be stretched by external means. However, on the cellular and subcellular level, dedicated technology to apply appropriate mechanical stimuli is limited. Here we report an organic electronic microactuator chip for mechanical stimulation of single cells. These chips are manufactured on silicon wafers using traditional microfabrication and photolithography techniques. The active unit of the chip consists of the electroactive polymer polypyrrole that expands upon the application of a low potential. The fact that polypyrrole can be activated in physiological electrolytes makes it well suited as the active material in a microactuator chip for biomedical applications. Renal epithelial cells, which are responsive to mechanical stimuli and relevant from a physiological perspective, are cultured on top of the microactuator chip. The cells exhibit good adhesion and spread along the surface of the chip. After culturing, individual cells are mechanically stimulated by electrical addressing of the microactuator chip and the response to this stimulation is monitored as an increase in intracellular Ca(2+). This Ca(2+) response is caused by an autocrine ATP signalling pathway associated with mechanical stimulation of the cells. In conclusion, the present work demonstrates a microactuator chip based on an organic conjugated polymer, for mechanical stimulation of biological systems at the cellular and sub-cellular level. 相似文献
999.
Dr. Edwin B. Clatworthy Dr. Stanislav V. Konnov Florent Dubray Dr. Nikolai Nesterenko Prof. Jean-Pierre Gilson Dr. Svetlana Mintova 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(44):19582-19600
The development of catalysts that can operate under exceptionally harsh and unconventional conditions is of critical importance for the transition of the energy and chemicals industries to low-emission and renewable chemical feedstocks. In this review we will highlight materials and more specifically metal-containing zeolite catalysts that have been tested under harsh reaction conditions such as high temperature light alkane conversion and biomass valorization. Particular attention will be given to studies that explore the stability and recyclability of metal-containing zeolite catalysts operating in continuous modes. Metal-containing zeolites are considered as an important class of catalysts operating outside the comfort zone of current heterogeneous catalytic reactions in both gas and liquid phase reactions. The relationship between the properties of the metal-containing zeolite and catalytic performance will be explored. 相似文献
1000.
Edwin C. Constable Catherine E. Housecroft Benson M. Kariuki Christopher B. Smith 《Supramolecular chemistry》2013,25(4):305-309
We have prepared two new 2,2′-bipyridine ligands bearing 3-aryl substituents at the 5 and 5′-positions using Suzuki methodology. The substituents differ only in the presence of a methoxy group or a phenolic hydroxy group. In the solid state a beautiful self-complementary hydrogen-bonded lattice incorporating one water molecule per ligand is formed with the phenolic compound. 相似文献