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1.
Assignment of π → 3d rydberg transitions in ethylene around 9 eV using MCD and synchrotron radiation
Magnetic circular dichroism measurements on ethylene are reported over the region of the 3R00 and 4R00? origins around 9 eV. The results show conclusively that each origin is a composite of two electronic transitions. The 3R00 origin is assigned to the Rydberg transitions, tA1 → 1B2(3dδ) + 1B3(3dδ). 4R00? is assigned as 1A1 → 3R00 + ν3(u). 相似文献
2.
Three new serratanes were isolated from the nonsaponifiable fraction of western white pine ( Dougl.) bark. The compounds were shown to be 3β-methoxyserrat-14-ene-21α,30-diol (), 3β-methoxyserrat-14-ene-21α, 29-diol (), and 3β-methoxyserrat-14-ene-21β,30-diol (), by a combination of chemical, and spectral methods. 相似文献
3.
Although food is a necessity, compounds within food products can be dangerous and life-threatening for people with food allergies. These allergy-causing compounds, such as proteins from eggs and milk, must be identified on the labels of commercial products. Unintentional contamination of food with these compounds occurs as a result of storage, manufacturing procedures, or cleaning procedures. A sensitive, specific, and rapid method to identify foods containing allergens is required by the food industry. The array biosensor, a rapid detection system, may provide a solution to this need. The array biosensor performs fluorescent immunoassays on the surface of a planar waveguide by first running samples, then fluorescently labeled antibodies, over a surface patterned with capture antibodies. An optical image is captured by a charged-coupled device camera and converted into fluorescence values. Signal intensity and spot location provide information on the compound and its concentration. The array biosensor has been successfully demonstrated for toxin, bacteria, and virus detection at low levels in under 20 min in food, clinical samples, and environmental matrixes. An assay for detection of ovalbumin as an indicator of egg contamination has been developed with limits of detection of 25 pg/mL in buffer and 1.3 ng/mL (13 ng/g) in non-egg pasta extract (buffer:pasta 10:1, v/w). 相似文献
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Goulay F Rebrion-Rowe C Carles S Le Garrec JL Rowe BR 《The Journal of chemical physics》2004,121(3):1303-1308
In order to check the electron thermalization in the CRESU technique (Cinetique de Reaction en Ecoulement Supersonique Uniforme, e.g., "reaction kinetics in a uniform supersonic flow"), electron attachment on HI and DI has been studied in the 48-170 K range. Attachment to HI is exothermic and the reaction is expected to be fast and to proceed at a rate close to the capture limit. On the contrary, attachment to DI is slightly endothermic, and a strong positive temperature dependence of the measured rate coefficient is expected if the electrons are thermal. This dependence is not observed, and we conclude that the electrons are not in thermal equilibrium with the neutrals in the afterglow. A model, based on electron heating by superelastic collisions with the buffer gas, is proposed to explain this fact and implications for previously published results are discussed. 相似文献
6.
We have developed a new statically operated oxygen plasma method that allows direct14C dates to be obtained from ancient rock paintings. The method is applicable even to paintings on limestone (CaCO3) walls. A sample of a pictograph which had naturally spalled offa shelter wall in the Lower Pecos region of Texas was subjected to a low temperature ( 150°C) oxygen plasma to selectively remove the organic carbon-containing material used in the paint as CO2, without contamination from the limestone substrate. The Zürich EHT accelerator mass spectrometer was then used to determine the radiocarbon age of this prehistoric rock painting. It was successfully dated at 3865 ± 100 years BP, in good accord with the archaeological context which has set the onset of this Pecos River style of pictograph between 4100 and 3200 years BP. The method appears feasible and is applicable to rock art in which organic materials were used in the paint. 相似文献
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Harrison S. Ewan Christine S. Muli Steven Touba Amy T. Bellinghiere Anne M. Veitschegger Travis B. Smith William L. Pistel II William T. Jewell Rebecca K. Rowe John P. Hagen Hasan Palandoken 《Tetrahedron letters》2014
A straightforward synthesis of a novel class of sugar surfactants is described. The key step is the chemoselective condensation of a hydrophobic alkoxyamine with the resident aldehyde/ketone moiety on a hydrophilic sugar. Neither protection/deprotection of the sugars nor extensive product purification is required. The method allows for the facile adjustment of hydrophobic and hydrophilic domains of the sugar oxime ether surfactant and uses inexpensive, readily accessible, and renewable materials. 相似文献
10.
Xiaoge Qu Laura Rowe Emre Dikici Mark Ensor Sylvia Daunert 《Analytical and bioanalytical chemistry》2014,406(23):5639-5643
Bioluminescent labels can be especially useful for in vivo and live animal studies due to the negligible bioluminescence background in cells and most animals, and the non-toxicity of bioluminescent reporter systems. Significant thermal stability of bioluminescent labels is essential, however, due to the longitudinal nature and physiological temperature conditions of many bioluminescent-based studies. To improve the thermostability of the bioluminescent protein aequorin, we employed random and rational mutagenesis strategies to create two thermostable double mutants, S32T/E156V and M36I/E146K, and a particularly thermostable quadruple mutant, S32T/E156V/Q168R/L170I. The double aequorin mutants, S32T/E156V and M36I/E146K, retained 4 and 2.75 times more of their initial bioluminescence activity than wild-type aequorin during thermostability studies at 37 °C. Moreover, the quadruple aequorin mutant, S32T/E156V/Q168R/L170I, exhibited more thermostability at a variety of temperatures than either double mutant alone, producing the most thermostable aequorin mutant identified thus far. 相似文献