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P. D. T. A. Elliott 《Monatshefte für Mathematik》1986,102(1):3-6
The subgroup of the positive rationals, generated by a sequence of upper density , has index essentially not exceeding –1.In honor of the seventieth birthday of Professor E. HlawkaPartially supported by N.S.F. Contract No. DMS-8500949. 相似文献
24.
Sokoloff MD Anjos JC Appel JA Bracker SB Browder TE Cremaldi LM Elliott JR Escobar CO Estabrooks P Gibney MC Hartner GF Karchin PE Kumar BR Losty MJ Luste GJ Mantsch PM Martin JF McHugh S Menary SR Morrison RJ Nash T Ong P Pinfold J Purohit MV Raab JR Santoro AF Sidhu JS Sliwa K Souza MH Spalding WJ Streetman ME Stundia AB Witherell MS 《Physical review letters》1986,57(24):3003-3006
25.
Production and characterisation of polyclonal antibodies to a derivative of 3-amino-2-oxazolidinone, a metabolite of the nitrofuran furazolidone 总被引:6,自引:0,他引:6
Kevin M. Cooper Anthony Caddell Christopher T. Elliott D. Glenn Kennedy 《Analytica chimica acta》2004,520(1-2):79-86
Polyclonal antibodies were produced to detect 3-amino-2-oxazolidinone (AOZ), a stable metabolite of the nitrofuran antibiotic furazolidone, following derivatisation with o-nitrobenzaldehyde. A carboxyphenyl derivative of AOZ was prepared, purified and conjugated to immunogenic carrier protein. Six antisera were produced from the immunisation of seven rabbits using various immunogen doses and time-scales. IC50 values, as determined by competitive enzyme-linked immunosorbent assay (ELISA) suggested that reducing immunogen dose from 0.3 to 0.05 mg, while lengthening rest periods between booster immunisations from 2 to 8 weeks, increased the sensitivity of the antibodies to 3-{[(2-nitrophenyl)methylene]amino}-2-oxazolidinone (NPAOZ) from 3.8 to 0.3 μg l−1. An IC50 of 0.065 μg l−1 (AOZ in the form of NPAOZ) was achieved with antiserum R670 by altering ELISA conditions. This antibody was highly specific for NPAOZ and did not cross-react with various nitrofuran metabolites, their nitrophenyl derivatives or a range of veterinary drugs. Antibody R670 is suitable for incorporation into an immunoassay for AOZ with sufficient sensitivity to satisfy current criteria for monitoring of veterinary drug residues. This is the first publication of an antibody for detection of a nitrofuran metabolite. 相似文献
26.
C. L. McCormick D. L. Elliott 《Journal of polymer science. Part A, Polymer chemistry》1987,25(5):1329-1337
Spectroscopic and potentiometric methods have been used to study the ionic properties of several N-substituted acrylamide copolymers that display unusual ion-binding character. The ionic groups and the amide groups (both on the same repeating unit and on adjacent acrylamide units) in the copolymers are found to chelate calcium ions. The stabilizing effect of this amide chelation is found to be dependent on copolymer composition. A model is proposed to explain the unusual binding behavior of the acrylamide polymers. This involves the formation of an intramonomer chelate or one with neighboring acrylamide units that prevent precipitation of the polymers. 相似文献
27.
Several aspects of past and current studies in the area of iminium salt photochemistry are discussed. Investigations of olefin-iminium salt photoaddition and photocyclization reactions are reviewed and conclusions about electron-transfer pathways for fluorescence quenching and reaction are discussed. The results of recent studies of alcohol and ether photoaddition to 2-phenyl-1-pyrrolinium salts are presented. These C-C bond forming processes occur in moderate yields to produce β-amino alcohol or ether products. In addition, alcohols and ethers serve as efficient quenchers of pyrrolinium salt fluorescence. Rate constants for quenching appear to be dependent upon both the oxidation potential of the alcohols and ethers and the availability of C-H bond α to oxygen. This data along with deuterium isotope effects on quenching combine to suggest a common mechanism for both fluorescence quenching and photoaddition. The nature of this mechanism is tested using the comparative quenching effeciencies of the tertiary alcohols t-butyl alcohol and 1,2,2-trimethyl-1-cyclopropanol. The latter alcohol having a weak C-C bond adjacent to the hydroxyl function quenches the fluorescence of 2-phenyl-1-pyrrolium salts at a rate two orders of magnitude greater than for t-butyl alcohol. The observations made are interpreted in terms of a sequential electron-proton transfer mechanism for quenching and photoaddition. Lastly, the relationship of iminium salt photochemical studies to other investigations of electron-transfer photochemistry is discussed. 相似文献
28.
C T Elliott G A Baxter S A Hewitt C J Arts M van Baak K E Hellen?s A Johannson 《The Analyst》1998,123(12):2469-2473
The drug salbutamol (SBL) is a beta-agonist that may be used illegally as an animal growth promoter. SBL is also a good example of a drug which is excreted in the form of glucuronides and sulfates. Such metabolites cause complexities in analysing for the presence of drug residues. In the majority of cases a process of deconjugation and sample clean-up is required prior to analysis. This is both time consuming and causes some loss of accuracy. In this study, the urine of calves treated with SBL orally for 3 d was collected during and after medication. Samples were assayed before and after hydrolysis by two different methods, radioimmunoassay (RIA) and a newly developed biosensor immunoassay (BIA). Some samples were also analysed by GC-MS. The results clearly showed that both screening assays (RIA and BIA) found high concentrations of SBL residues throughout the study. This was especially true in the BIA method. It was also demonstrated that urine sample analysis without the need for deconjugation or clean-up could be achieved. Results obtained by GC-MS tended to be an order of magnitude lower than the corresponding screening test results. This work showed that biosensor based veterinary drug residue testing procedures can be developed which can generate results in real time without the need for time consuming sample preparation. 相似文献
29.
The photochemistry of the stereoisomeric 1,3-dimethyl-3(2-phenylethenyl)cyclohexenes has been explored Direct irradiation of the cis- and trans-β-styrylcyclohexenes leads to di-π-methane rearrangement, producing the endo- and exo-3,7-dimethyl-8-phenybicyclo[5.1.0]oct-2-enes, and cis -trans isomerization, interconverting the 1,4-diene containing substrates. Triplet sensitized photolysis of both substituted cyclohexenes leads exclusively to cis-trans isomerization. Results from low conversion direct irradiations of the cis- and trans-β-styrylcyclohexenes indicate that the singlet rearrangements are stereospecific, and lead to formation of the 8-exo and 8-endo-phenylbicyclic octenes, respectively. The relationship between di-π-methane structure and triplet reaction efficiency, and the effect of conformation on the rearrangement stereochemistry are discussed. 相似文献
30.
Bayó N Jiménez JC Rivas L Nicolás E Albericio F 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(5):1096-1103
An optimized solid-phase strategy for the preparation of the cyclic lipononadepsipeptide [N-Mst(L-Ser1), D-Ser4, L-Thr6, L-Asp8, L-Thr9]syringotoxin is reported. The strategy is based on the use of a mild orthogonal protection scheme and the incorporation of the nonproteinogenic amino acid (Z)-Dhb into the peptide chain as the dipeptide Fmoc-Thr(tBu)-(Z)-Dhb-OH. The didehydrodipeptide was synthesized by a water-soluble carbodiimide-induced beta-elimination of a protected dipeptide containing a residue of Thr with its free hydroxy side chain unprotected. 相似文献