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11.
Abstract— This paper presents the analysis and identification of an unstable product previously undescribed from furocoumarin photolysis, 5-formyl-6-hydroxybenzofuran. Reverse-phase chromatography and solid-phase extraction techniques allowed its isolation. 相似文献
12.
Richard A. Larson Karen A. Marley Robert W. Tuveson May R. Berenbaum 《Photochemistry and photobiology》1988,48(5):665-674
Abstract— Phototoxicity of five naturally occurring (3-carboline alkaloids was assayed against a series of Escherichia coli strains and against the insect Trichoplusia ni (Lepidoptera: Noctuidae). Rank order efficacy of the compounds was comparable in both organisms. Although the bacterial assay demonstrated oxygen dependence, the degree of phototoxicity did not correlate with the relative efficiency of in vitro singlet oxygen or hydrogen peroxide photoproduction by the alkaloids. A better correlation was observed between chromatographic migration distances (lipophilicity) and phototoxicity. Therefore, hydrophobic mechanisms in which the alkaloids diffuse with varying efficiencies into cells or into the vicinity of target molecules may be important modes of phototoxicity for these compounds. 相似文献
13.
Hilbert Coefficients and the Depths of Associated Graded Rings 总被引:2,自引:0,他引:2
This work was motivated in part by the following general question:given an ideal I in a CohenMacaulay (abbreviated to CM)local ring R such that dim R/I=0, what information about I andits associated graded ring can be obtained from the Hilbertfunction and Hilbert polynomial of I? By the Hilbert (or HilbertSamuel)function of I, we mean the function HI(n)=(R/In) for all n1,where denotes length. Samuel [23] showed that for large valuesof n, the function HI(n) coincides with a polynomial PI(n) ofdegree d=dim R. This polynomial is referred to as the Hilbert,or HilbertSamuel, polynomial of I. The Hilbert polynomialis often written in the form
where e0(I), ..., ed(I) are integers uniquely determined byI. These integers are known as the Hilbert coefficients of I. 相似文献
14.
Two approaches are taken to a new utility representation of binary gambles that is called “ratio rank-dependent utility.” Both are based on known axiomatizations of a ranked-additive representation of consequence pairs (x, y) in binary gambles (x, C; y) of gains with C held fixed and of a separable one of the special gambles (x, C; e), where e denotes the status quo. The axiomatized version imposes the condition of status-quo event commutativity to get a functional equation that leads to the result. The other assumes, but does not axiomatize, a separable representation of the (C; y) portion of the gamble. These assumptions lead to two difficult functional equations that are solved in the mathematical literature, but the former only under the assumption that the function is twice differentiable. Three behavioral conditions are shown to force this new utility representation to reduce to the standard rank-dependent utility one for gains. They are co-monotonic trade-off consistency, ranked bisymmetry, and segregation, the latter requiring the addition of an operation of joint receipt. 相似文献
15.
Thomas Marley Janet C. Vassilev 《Proceedings of the American Mathematical Society》2004,132(12):3485-3490
In this paper we prove the following generalization of a result of Hartshorne: Let be a commutative Noetherian local ring of dimension at least two, , and . Let be a homogeneous element of such that the coefficients of form a system of parameters for . Then the socle of is infinite dimensional.
16.
Peter M. Marley Tesfaye A. Abtew Katie E. Farley Gregory A. Horrocks Robert V. Dennis Peihong Zhang Sarbajit Banerjee 《Chemical science》2015,6(3):1712-1718
The classical orthorhombic layered phase of V2O5 has long been regarded as the thermodynamic sink for binary vanadium oxides and has found great practical utility as a result of its open framework and easily accessible redox states. Herein, we exploit a cation-exchange mechanism to synthesize a new stable tunnel-structured polymorph of V2O5 (ζ-V2O5) and demonstrate the subsequent ability of this framework to accommodate Li and Mg ions. The facile extraction and insertion of cations and stabilization of the novel tunnel framework is facilitated by the nanometer-sized dimensions of the materials, which leads to accommodation of strain without amorphization. The topotactic approach demonstrated here indicates not just novel intercalation chemistry accessible at nanoscale dimensions but also suggests a facile synthetic route to ternary vanadium oxide bronzes (MxV2O5) exhibiting intriguing physical properties that range from electronic phase transitions to charge ordering and superconductivity. 相似文献
17.
This communication describes the first paper-based microfluidic device that is capable of generating its own power when a sample is added to the device. The microfluidic device contains galvanic cells (that we term "fluidic batteries") integrated directly into the microfluidic channels, which provides a direct link between a power source and an analytical function within the device. This capability is demonstrated using an example device that simultaneously powers a surface-mount UV LED and conducts an on-chip fluorescence assay. 相似文献
18.
In this paper the currents associated with the streamer discharges generated from the head of a person located in the vicinity of a lightning strike are investigated. In the analysis the location of the person with respect to the lightning strike is selected in such a way that only a streamer burst, without the formation of a connecting leader, is emitted from the head. The current associated with these streamer bursts could exceed several hundreds of mA and may last for several hundreds of microseconds. The results of the calculation show that the passage of the streamer currents through the body of the person could create electric fields in the brain large enough to excite neurons. Depending on the strength of lightning flash and the distance to the strike point these streamer bursts can give rise to phosphenes which are a form of visual experience that occurs when the visual cortex is stimulated by electric currents. 相似文献
19.
SANGUINARINE, A PHOTOTOXIC H2 O2 -PRODUCING ALKALOID 总被引:2,自引:0,他引:2
R. W. Tuveson Richard A. Larson Karen A. Marley Gui-rong Wang May R. Berenbaum 《Photochemistry and photobiology》1989,50(6):733-738
Sanguinarine chloride, a quaternary salt of a benzophenanthrene alkaloid, was phototoxic to catalase-deficient strains of Escherichia coli but not to Trichoplusia ni (cabbage looper moth larvae), an insect with high levels of catalase activity. Chemical analyses confirm that sanguinarine is an efficient producer of H2O2. This differential toxicity suggests that the mode of phototoxic action involves production of H2O2 which could be detoxified in many organisms by catalase. 相似文献
20.
Separation of radioactive histamine and some of its metabolites by one-dimensional paper chromatography 总被引:2,自引:0,他引:2
A simple one-dimensional paper chromatograph technique is described for the separation of radioactive histamine and some of its metabolites in blood and tissues. After removal of protein, the supernatant fluid (200 microliter) is subjected to two-stage one-dimensional paper chromatography. This enables large numbers of samples to be chromatographed simultaneously. Using this technique in conjunction with liquid scintillation counting, it was possible to monitor the small amounts (0.02 nCi) of radioactive histamine and its metabolites in serial blood samples. 相似文献