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1.
A route for bulk separation of semiconducting from metallic single-wall carbon nanotubes 总被引:9,自引:0,他引:9
Chattopadhyay D Galeska I Papadimitrakopoulos F 《Journal of the American Chemical Society》2003,125(11):3370-3375
Substantial separation of single-wall carbon nanotubes (SWNTs) according to type (metallic versus semiconducting) has been achieved for HiPco and laser-ablated SWNTs. We presently argue that stable dispersions of SWNTs with octadecylamine (ODA) in tetrahydrofuran (THF) originate from the physisorption and organization of ODA along the SWNT sidewalls in addition to the originally proposed zwitterion model. Furthermore, the reported affinity of amine groups for semiconducting SWNTs, as opposed to their metallic counterparts, contributes additional stability to the physisorbed ODA. This provides a venue for the selective precipitation of metallic SWNTs upon increasing dispersion concentration, as indicated by Raman investigations. 相似文献
2.
A three-component coupling was used to prepare a series of 1,4-disubstituted-1,2,3-triazoles from the corresponding acetylated Baylis-Hillman adducts, sodium azide and terminal alkynes. This one-pot reaction further increases the efficacy of ‘Click’ synthesis and diversifies the preparation of multi-functional 1,4-disubstituted-1,2,3-triazoles. 相似文献
3.
In this Letter, we describe the novel synthetic approach to the tricyclic core of (±)-galanthamine from the easily available starting material isovanillin. 相似文献
4.
Molecular Diversity - In this study, an efficient and convenient domino Michael addition/intramolecular cyclization protocol is presented for the synthesis of biologically relevant... 相似文献
5.
In this paper, Mg-doped ZnO nanoparticles were synthesized by the facile sol–gel method. The crystalline structure, characteristic absorption bands and morphology of the obtained Mg-doped ZnO nanoparticles were studied by XRD, FTIR and TEM. The thermal degradation behaviour of the samples was investigated by differential scanning calorimetry (DSC) and thermogravimetry (TG). The effect of Mg concentrations and annealing temperatures on the antibacterial properties of the obtained nanoparticles was investigated in detail. The results indicated that doping Mg ions into ZnO lattice could enhance its antibacterial activity. Antibacterial assay demonstrated that Mg-doped ZnO with 7% Mg content annealed at 400 °C had the strongest antibacterial activity against Listeria monocytogenes (98.7%). This study indicated that the inhibition rate of ZnO nanoparticles increased with the formation of granular structure and the decrease of ZnO size due to the doping of Mg ions into the ZnO lattice. 相似文献
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7.
Dutta D Pulsipher A Luo W Yousaf MN 《Journal of the American Chemical Society》2011,133(22):8704-8713
Proper cell-cell communication through physical contact is crucial for a range of fundamental biological processes including, cell proliferation, migration, differentiation, and apoptosis and for the correct function of organs and other multicellular tissues. The spatial and temporal arrangements of these cellular interactions in vivo are dynamic and lead to higher-order function that is extremely difficult to recapitulate in vitro. The development of three-dimensional (3D), in vitro model systems to investigate these complex, in vivo interconnectivities would generate novel methods to study the biochemical signaling of these processes, as well as provide platforms for tissue engineering technologies. Herein, we develop and employ a strategy to induce specific and stable cell-cell contacts in 3D through chemoselective cell-surface engineering based on liposome delivery and fusion to display bio-orthogonal functional groups from cell membranes. This strategy uses liposome fusion for the delivery of ketone or oxyamine groups to different populations of cells for subsequent cell assembly via oxime ligation. We demonstrate how this method can be used for several applications including, the delivery of reagents to cells for fluorescent labeling and cell-surface engineering, the formation of small, 3D spheroid cell assemblies, and the generation of large and dense, 3D multilayered tissue-like structures for tissue engineering applications. 相似文献
8.
Arenes, heteroarenes, 1,3-dicarbonyls and organosilicon nucleophiles undergo highly efficient alkylation with allylic, propargylic and benzylic alcohols in the presence of a new 'Pd-Sn' bimetallic catalyst in nitromethane; water being the sole byproduct. The plausible mechanism of alkylation and the intermediacy of ether has been enumerated. 相似文献
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In situ dynamics of colloidal cluster formation from nanoparticles is yet to be addressed. Using two-photon fluorescence (TPF) that has been amply used for single particle tracking, we demonstrate in situ measurement of effective three-dimensional optical trap stiffness of nanoparticles and their aggregates without using any position sensitive detector. Optical trap stiffness is an essential measure of the strength of an optical trap. TPF is a zero-background detection scheme and has excellent signal-to-noise-ratio, which can be easily extended to study the formation of colloidal cluster of nanospheres in the optical trapping regime. TPF tracking can successfully distinguish colloidal cluster from its monomer. 相似文献
10.
Dr. Biswajit Bhattacharya Dr. Debjit Roy Dr. Somnath Dey Anisha Puthuvakkal Surojit Bhunia Saikat Mondal Rituparno Chowdhury Dr. Manjima Bhattacharya Mrinal Mandal Dr. Kochunnoonny Manoj Prof. Prasun K. Mandal Prof. C. Malla Reddy 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(45):20050-20055
Single crystals of optoelectronic materials that respond to external stimuli, such as mechanical, light, or heat, are immensely attractive for next generation smart materials. Here we report single crystals of a green fluorescent protein (GFP) chromophore analogue with irreversible mechanical bending and associated unusual enhancement of the fluorescence, which is attributed to the strained molecular packing in the perturbed region. Soft crystalline materials with such fluorescence intensity modulations occurring in response to mechanical stimuli under ambient pressure conditions will have potential implications for the design of technologically relevant tunable fluorescent materials. 相似文献