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231.
Simon Goodwin 《Indagationes Mathematicae》2004,15(2):189-207
Let G be a reductive linear algebraic group, P a parabolic subgroup of G and Pu its unipotent radical. We consider the adjoint action of P on the Lie algebra u of Pu. Each higher term u(l) of the descending central series of u is stable under this action. For classical G all instances when P acts on u(l) with a finite number of orbits were determined in [9], [10], [3] and [4]. In this note we extend these results to groups of type F4 and E6. Moreover, when P acts on u(l) with an infinite number of orbits, we determine whether P still acts with a dense orbit. For G of type E7 and E8 we investigate only the case of a Borel subgroup.We present a complete classification of all instances when u(l) is a prehomogeneous space for a Borel subgroup B of a reductive algebraic group for any l ≥ 0. 相似文献
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James C. Goodwin 《Journal of carbohydrate chemistry》2013,32(2):255-263
Sodium bis(3-O-hydroxy-2-furyl methyl ketone) (3) and sodium 3-O-hydroxy-2-methyl-4-pyrone hydrate (4) were isolated and characterized from the interaction of isomaltol and maltol with sodium methoxide in boiling benzene (toluene or acetone). Elemental analyses of 3 furnished the formula C12H11NaO6, and this composition was confirmed by conversion to isomaltol O-benzoyl ester. 相似文献
236.
W. E. Goodwin Raghu R. Rao A. Chatt 《Journal of Radioanalytical and Nuclear Chemistry》2013,296(1):489-494
A preconcentration neutron activation analysis method has been developed for the determination of trace levels of Cu in natural waters including seawater with an absolute detection limit of 0.106 μg. The method involves the preconcentration of Cu onto Amberlite XAD-4 resin coated with 1-(2-thiazolylazo)-2-naphthol using reversed-phase extraction chromatography (RPEC). Copper is assayed through its neutron activation product 66Cu (half-life = 5.10 min) by direct irradiation of the resin bed. Factors affecting the uptake of Cu onto the ligand-impregnated resin have been investigated; these include flow rate, pH, column height, presence of other trace elements, major elements, and interfering matrix. The RPEC–NAA method has been validated by analyzing NIST and NRC water reference materials. 相似文献
237.
Driehorst T O'Neill P Goodwin PM Pennathur S Fygenson DK 《Langmuir : the ACS journal of surfaces and colloids》2011,27(14):8923-8933
Silver-DNA nanoclusters (Ag:DNAs) are novel fluorophores under active research and development as alternative biomolecular markers. Comprised of a few-atom Ag cluster that is stabilized in water by binding to a strand of DNA, they are also interesting for fundamental explorations into the properties of metal molecules. Here, we use in situ calibrated electrokinetic microfluidics and fluorescence correlation spectroscopy to determine the size, charge, and conformation of a select set of Ag:DNAs. Among them is a pair of spectrally distinct Ag:DNAs stabilized by the same DNA sequence, for which it is known that the silver cluster differs by two atoms. We find these two Ag:DNAs differ in size by ~30%, even though their molecular weights differ by less than 3%. Thus a single DNA sequence can adopt very different conformations when binding slightly different Ag clusters. By comparing spectrally identical Ag:DNAs that differ in sequence, we show that the more compact conformation is insensitive to the native DNA secondary structure. These results demonstrate electrokinetic microfluidics as a practical tool for characterizing Ag:DNA. 相似文献
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Brigita Darminto Dr. Gregory J. Rees John Cattermull Dr. Kenjiro Hashi Dr. Maria Diaz-Lopez Dr. Naoaki Kuwata Dr. Stephen J. Turrell Emily Milan Yvonne Chart Dr. Camilla Di Mino Prof. Hyeon Jeong Lee Prof. Andrew L. Goodwin Prof. Mauro Pasta 《Angewandte Chemie (International ed. in English)》2023,62(51):e202314444
The sodium-rich antiperovskites (NaRAPs) with composition Na3OB (B=Br, Cl, I, BH4, etc.) are a family of materials that has recently attracted great interest for application as solid electrolytes in sodium metal batteries. Non-Arrhenius ionic conductivities have been reported for these materials, the origin of which is poorly understood. In this work, we combined temperature-resolved bulk and local characterisation methods to gain an insight into the origin of this unusual behaviour using Na3OBr as a model system. We first excluded crystallographic disorder on the anion sites as the cause of the change in activation energy; then identified the presence of a poorly crystalline impurities, not detectable by XRD, and elucidated their effect on ionic conductivity. These findings improve understanding of the processing-structure-properties relationships pertaining to NaRAPs and highlight the need to determine these relationships in other materials systems, which will accelerate the development of high-performance solid electrolytes. 相似文献