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The results of the applications of computer learning techniques to decision making in the evaluation of mass spectral data are used to propose a model in which molecular complexity is related to binary decision prediction probability. This model is tested on the results from a mass spectrum interpretation programme and it is proposed that the method could be used to compare the effectiveness of programmes developed from different basic concepts. 相似文献
43.
The synthesis and properties including mass spectra of (o-diphenylphosphinophenyl)diphenylbismuthine, o-C6H4(PPh2)(BiPh2) and (o-diphenylarsinophenyl)-diphenylbismuthine, o-C6H4(AsPh2)(BiPh2) are described. The failure of attempts to prepare α, ω-bis(disphenylbismuthino)alkanes is discussed. 相似文献
44.
Jingqin Chen Adam C. Sedgwick Sajal Sen Yaguang Ren Qinchao Sun Calvin Chau Jonathan F. Arambula Tridib Sarma Liang Song Jonathan L. Sessler Chengbo Liu 《Chemical science》2021,12(29):9916
Photoacoustic imaging (PAI) relies on the use of contrast agents with high molar absorptivity in the NIR-I/NIR-II region. Expanded porphyrins, synthetic analogues of natural tetrapyrrolic pigments (e.g. heme and chlorophyll), constitute as potentially attractive platforms due to their NIR-II absorptivity and their ability to respond to stimuli. Here, we evaluate two expanded porphyrins, naphthorosarin (1) and octaphyrin (4), as stimuli responsive PA contrast agents for functional PAI. Both undergo proton-coupled electron transfer to produce species that absorb well in the NIR-II region. Octaphyrin (4) was successfully encapsulated into 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-poly(ethylene glycol) (DSPE-PEG2000) nanoparticles to afford OctaNPs. In combination with PAI, OctaNPs allowed changes in the acidic environment of the stomach to be visualized and cancerous versus healthy tissues to be discriminated.In this study, two expanded porphyrins, octaphyrin and naphthorosarin were evaluated as potential PA agents. The nanoparticle encapsulation of octaphyrin successfully enabled the visualization of acidic environments and the discrimination between cancerous and healthy tissues. 相似文献
45.
M Sedgwick RL Cole CD Rithner DC Crans NE Levinger 《Journal of the American Chemical Society》2012,134(29):11904-11907
The dramatic impact of differing environments on proton transfer dynamics of the photoacid HPTS prompted us to investigate these systems with two highly complementary methods: ultrafast time-resolved transient absorption and two-dimensional NMR spectroscopies. Both ultrafast time-resolved transient absorption spectroscopy and time-resolved anisotropy decays demonstrate the proton transfer dynamics depend intimately on the specific reverse micellar system. For w(0) = 10 reverse micelles formed with anionic AOT surfactant, the HPTS proton transfer dynamics are similar to dynamics in bulk aqueous solution, and the corresponding (1)H 2D NOESY NMR spectra display no cross peaks between HPTS and AOT consistent with the HPTS residing well hydrated by water in the interior of the reverse micelle water pool. In contrast, ultrafast transient absorption experiments show no evidence for HPTS photoinduced proton transfer reaction in reverse micelles formed with the cationic CTAB surfactant. In CTAB reverse micelles, clear cross peaks between HPTS and CTAB in the 2D NMR spectra show that HPTS embeds in the interface. These results indicate that the environment strongly impacts the proton transfer reaction and that complementary experimental techniques develop understanding of how location critically affects molecular responses. 相似文献
46.
Metabolic monitoring of the electrically stimulated single heart cell within a microfluidic platform 总被引:2,自引:0,他引:2
A device based on five individually addressable microelectrodes, fully integrated within a microfluidic system, has been fabricated to enable the real-time measurement of ionic and metabolic fluxes from electrically active, beating single heart cells. The electrode array comprised one pair of pacing microelectrodes, used for field-stimulation of the cell, and three other microelectrodes, configured as an electrochemical lactate microbiosensor, that were used to measure the amounts of lactate produced by the heart cell. The device also allowed simultaneous in-situ microscopy, enabling optical measurements of cell contractility and fluorescence measurements of extracellular pH and cellular Ca2+. Initial experiments aimed to create a metabolic profile of the beating heart cell, and results show well defined excitation-contraction (EC) coupling at different rates. Ca2+ transients and extracellular pH measurements were obtained from continually paced single myocytes, both as a function of the rate of cell contraction. Finally, the relative amounts of intra- and extra-cellular lactate produced during field stimulation were determined, using cell electroporation where necessary. 相似文献