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81.
Carbon nanotubes (CNTs) are one of the most extensively studied nanomaterials in the 21st century. Since their discovery in 1991, many studies have been reported advancing our knowledge in terms of their structure, properties, synthesis, and applications. CNTs exhibit unique electrothermal and conductive properties which, combined with their mechanical strength, have led to tremendous attention of CNTs as a nanoscale material in the past two decades. To introduce the various types of CNTs, we first provide basic information on their structure followed by some intriguing properties and a brief overview of synthesis methods. Although impressive advances have been demonstrated with CNTs, critical applications require purification, positioning, and separation to yield desired properties and functional elements. Here, we review a versatile technique to manipulate CNTs based on their dielectric properties, namely dielectrophoresis (DEP). A detailed discussion on the DEP aspects of CNTs including the theory and various technical microfluidic realizations is provided. Various advancements in DEP-based manipulations of single-walled and multiwalled CNTs are also discussed with special emphasis on applications involving separation, purification, sensing, and nanofabrication. 相似文献
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83.
Jared M. Schwartz Oluwadamilola Phillips Anthony Engler Alexandra Sutlief Jihyun Lee Paul A. Kohl 《Journal of polymer science. Part A, Polymer chemistry》2017,55(7):1166-1172
Low ceiling temperature, thermodynamically unstable polymers have been troublesome to synthesize and keep stable during storage. In this study, stable poly(phthalaldehyde) has been synthesized with BF3‐OEt2 catalyst. The role of BF3 in the polymerization is described. The interaction of BF3 with the monomer is described and used to maximize the yield and molecular weight of poly(phthalaldehyde). Various Lewis acids were used to investigate the effect of catalyst acidity on poly(phthalaldehyde) chain growth. In situ nuclear magnetic resonance was used to identify possible interactions formed between BF3 and phthalaldehyde monomer and polymer. The molecular weight of the polymer tracks with polymerization yield. The ambient temperature stability of poly(phthalaldehyde) was investigated and the storage life of the polymer has been improved. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 55, 1166–1172 相似文献
84.
Russian Physics Journal - The paper presents a study of weakly nonlinear wave processes in the cylindrical region of a hole gas surrounding a negatively charged dislocation in an n-type... 相似文献
85.
86.
Defect Chemistry of Singly and Doubly Doped Ceria: Correlation between Ion Transport and Energetics
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Dr. Salih Buyukkilic Prof. Sangtae Kim Prof. Alexandra Navrotsky 《Angewandte Chemie (International ed. in English)》2014,53(36):9517-9521
Earlier studies have shown a strong correlation between the enthalpy of formation, ΔHf,ox, and the ionic conductivity, σi, near room temperature in doped ceria systems, which are promising solid electrolytes for intermediate‐temperature solid oxide fuel cells (IT‐SOFCs). The present work demonstrates that this correlation holds at the operating temperature of IT‐SOFCs, 600–700 °C. Solid solutions of Ce1?xNdxO2?0.5x, Ce1?xSmxO2?0.5x, and Ce1?xSm0.5xNd0.5xO2?0.5x are studied. The ΔHf,ox at 702 °C is determined by considering the excess heat content between 25 and 702 °C combined with the value of ΔHf,ox at 25 °C. Both σi and ΔHf,ox show maxima at x=0.15 and 0.20 for the singly and doubly doped ceria, respectively, suggesting that the number of mobile oxygen vacancies in these solid solutions reaches a maximum near those compositions. An increase in temperature results in a shift of the maximum in both ΔHf,ox and σi towards higher concentrations. This shift results from a gradual increase in dissociation of the defect associates. 相似文献
87.
Andrew A. Tolmachev Sergei P. Ivonin Alexandra A. Chaikovskaya Tamara N. Kudrya Tat'jana E. Terekovskaya 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4)
Abstract C-phosphorylation of pyrrole, furan, thiophene derivatives and their benzanalogs by phosphorus tribromide has been studied. Perspective methods for involving trivalent phosphorus residues at a different position of the rings have been developed. Unknown early the heterocycle's derivatives with tri- and tetracoordinated phosphorus substituents (1–5) and novel types of phosphoruscontaining heterocycles (6,7) have been obtained. 相似文献
88.
Nickolay I. Tyryshkin Viktor V. Gavrilov Alexandra V. Fuzhenkova 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4)
Abstract It has been known more than for 100 year that triethylphosphine forms the 1:1 adducts with carbon disulfide and isothiocyanates. However, little is know on the reaction of the adducts and the formation of reactive alkylidenephosphoranes was recently reported by the reaction of adducts with electron-poor double bonds. 相似文献
89.
Manolis M. Antonakis Alexandra Tsirigotaki Katerina Kanaki Constantinos J. Milios Spiros A. Pergantis 《Journal of the American Society for Mass Spectrometry》2013,24(8):1250-1259
In this study, we report on the development of a novel nebulizer configuration for sonic-spray ionization (SSI) mass spectrometry (MS), more specifically for a version of SSI that is referred to as Venturi easy ambient sonic-spray ionization (V-EASI) MS. The developed nebulizer configuration is based on a commercially available pneumatic glass nebulizer that has been used extensively for aerosol formation in atomic spectrometry. In the present study, the nebulizer was modified in order to achieve efficient V-EASI-MS operation. Upon evaluating this system, it has been demonstrated that V-EASI-MS offers some distinct advantages for the analysis of coordination compounds and redox active inorganic compounds over the predominantly used electrospray ionization (ESI) technique. Such advantages, for this type of compounds, are demonstrated here for the first time. More specifically, a series of labile heptanuclear heterometallic [CuII 6LnIII] clusters held together with artificial amino acid ligands, in addition to easily oxidized inorganic oxyanions of selenium and arsenic, were analyzed. The observed advantages pertain to V-EASI appearing to be a “milder” ionization source than ESI, not requiring electrical potentials for gas phase ion formation, thus eliminating the possibility of unwanted redox transformations, allowing for the “simultaneous” detection of negative and positive ions (bipolar analysis) without the need to change source ionization conditions, and also not requiring the use of syringes and delivery pumps. Because of such features, especially because of the absence of ionization potentials, EASI can be operated with minimal requirements for source parameter optimization. We observed that source temperature and accelerating voltage do not seem to affect labile compounds to the extent they do in ESI-MS. In addition, bipolar analysis of proteins was demonstrated here by acquiring both positive and negative ion mass spectra from the same protein solutions, without the need to independently adjust solution and source conditions in each mode. Finally, the simple and efficient operation of a dual-nebulizer configuration was demonstrated for V-EASI-MS for the first time. Figure
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90.
Alexandra Hütteroth Martin Jekel 《International journal of environmental analytical chemistry》2013,93(6):415-424
For the detection of unknown organic bromine compounds, a liquid chromatography–mass spectrometry (LC-MS) method with negative-ion electrospray ionization (NI-ESI) and induced in-source fragmentation (IISF) was established. After LC separation, the molecules are fragmentized in the source, and bromide is detected via m/z 79 and m/z 81 based on the isotopic occurrence of bromine. In this way, the retention times of the unknown organobromine compounds are determined, and this can be used to extract additional structural information (number of bound bromine atoms, molecular mass and fragmentation scheme) from measurements in the commonly used but less sensitive scan mode. The analysis of known organobromine compounds shows that LC/NI-ESI-IISF mass spectrometry with detection of m/z 79 and 81 is more sensitive than the detection of daughter ions (LC/ESI/MS-MS). Therefore, we present a method not only for the detection of unknown organic bromine compounds, but also for the selective and sensitive detection and quantification of known organobromine compounds. 相似文献