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Using dyes of known redox potentials the specific mechanisms of dark and light potential generation is analyzed in pigmented lipid membranes. The role of the ionic and electronic conductance, as well as the redox potential gradient is specifically related to the observed open circuit voltage developed across the membrane. The results can be most easily explained by the redox electrode model. 相似文献
3.
Jimmy Yuk Kristina L. McIntyre Christian Fischer Joshua Hicks Kimberly L. Colson Ed Lui Dan Brown John T. Arnason 《Analytical and bioanalytical chemistry》2013,405(13):4499-4509
The use of 1H-NMR-based metabolomics to distinguish and identify unique markers of five Ontario ginseng (Panax quinquefolius L.) landraces and two ginseng species (P. quinquefolius and P. ginseng) was evaluated. Three landraces (2, 3, and 5) were distinguished from one another in the principal component analysis (PCA) scores plot. Further analysis was conducted and specific discriminating metabolites from the PCA loadings were determined. Landraces 3 and 5 were distinguishable on the basis of a decreased NMR intensity in the methyl ginsenoside region, indicating decreased overall ginsenoside levels. In addition, landrace 5 was separated by an increased amount of sucrose relative to the rest of the landraces. Landrace 2 was separated from the rest of the landraces by the increased level of ginsenoside Rb1. The Ontario P. quinquefolius was also compared with Asian P. ginseng by PCA, and clear separation between the two groups was detected in the PCA scores plot. The PCA loadings plot and a t-test NMR difference plot were able to identify an increased level of maltose and a decreased level of sucrose in the Asian ginseng compared with the Ontario ginseng. An overall decrease of ginsenoside content, especially ginsenoside Rb1, was also detected in the Asian ginseng’s metabolic profile. This study demonstrates the potential of NMR-based metabolomics as a powerful high-throughput technique in distinguishing various closely related ginseng landraces and its ability to identify metabolic differences from Ontario and Asian ginseng. The results from this study will allow better understanding for quality assessment, species authentication, and the potential for developing a fully automated method for quality control. Figure
Principal component analysis scores and loadings plot for differentiating between closely-related ginseng landraces in Ontario, Canada 相似文献
4.
Jong Seol Yuk Colette McDonagh Brian D. MacCraith 《Analytical and bioanalytical chemistry》2010,398(5):1947-1954
The technique of surface plasmon-coupled emission (SPCE) involves the coupling of light which is emitted from a fluorophore
into the surface plasmon of an adjacent thin metal film, giving rise to highly directional emission. We have combined the
advantages of SPCE with the high light collection efficiency of supercritical angle fluorescence by carrying out an immunoassay
on a paraboloid array biochip in the absence of the conventional SPCE spacer layer normally used to minimize metal quenching
of the fluorescence. In this work, we have successfully demonstrated an SPCE-based assay by utilizing the protein assay layer
as the spacer layer. A novel 3 × 3 injection molded polymer biochip with paraboloid elements was used. The paraboloid elements
served to enhance the light collection efficiency while the top surface was coated with a gold layer to use excitation of
surface plasmons and detection of SPCE emission. Theoretical modeling of the gold-protein layer structure showed that the
surface plasmon resonance angles were located in the detection range of the paraboloid biochip. The polarization dependence
of SPCE emission was also demonstrated. Finally, a human IgG sandwich immunoassay was carried out which exhibited a limit
of detection of ~10 ng/ml using 3σ. The results demonstrate the potential of the SPCE-based paraboloid array biochip as a novel platform for high-throughput
analysis of biomolecular interactions. 相似文献
5.
Glyphosate and its metabolite aminomethylphosphonic acid in environmental water can be preconcentrated with an anion-exchange column, eluted with potassium citrate solution and determined directly by liquid chromatography with a post-column reactor and a fluorescence detector. The limit of detection and average recovery are 1 μg 1?1 and 89.3% for glyphosate and 0.4 μg l?1 and 86.3% for the metabolite. 相似文献
6.
Catalytic Asymmetric 1,6‐Conjugate Addition of para‐Quinone Methides: Formation of All‐Carbon Quaternary Stereocenters 下载免费PDF全文
Dr. Zhaobin Wang Yuk Fai Wong Prof. Jianwei Sun 《Angewandte Chemie (International ed. in English)》2015,54(46):13711-13714
Described herein is a general and mild catalytic asymmetric 1,6‐conjugate addition of para‐quinone methides (p‐QMs), a class of challenging reactions with previous limited success. Benefiting from chiral Brønsted acid catalysis, which allows in situ formation of p‐QMs, our reaction expands the scope to general p‐QMs with various substitution patterns. It also enables efficient intermolecular formation of all‐carbon quaternary stereocenters with high enantioselectivity. 相似文献
7.
Visible light of the solar spectrum is directly converted to stored chemical energy of hydrogen from artificial sea water in a novel electrochemical photovoltaic cell. The principal element of the cell, modeled after the photosynthetic thylakoid membrane, is a semiconductor septum made of polycrystalline n-CdSe thin film deposited on nickel foil, which separates two aqueous solutions. Under short-circuit conditions, vigorous hydrogen evolution was seen at the Ni surface and continued as long as the cell was operated. The novel cell, the concept of which was derived from pigmented bilayer lipid membrane studies, is easy to construct, simple to operate, and appears to be a practical approach to the photochemical conversion and storage of solar energy. 相似文献
8.
We propose a simple moiré method of visualizing electromagnetic force lines. The indicial equation is first derived for the tangent (or normal) curve to the electric field (or magnetic induction) around two parallel-line charges (or currents). The derived equation is then shown to have a one-to-one correspondence with that of the moiré fringe formed by two overlapped radial gratings. Since the tangent (or normal) curve to the electric field (or the magnetic induction) corresponds to the direction of the electric (or magnetic) force on a test charge (or current), the radial grating moirés can be used for the visualization of electric (or magnetic) force lines. 相似文献
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