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991.
Dörfler S Hagen M Althues H Tübke J Kaskel S Hoffmann MJ 《Chemical communications (Cambridge, England)》2012,48(34):4097-4099
Binder free vertical aligned (VA) CNT/sulfur composite electrodes with high sulfur loadings up to 70 wt% were synthesized delivering discharge capacities higher than 800 mAh g(-1) of the total composite electrode mass. 相似文献
992.
Fernández-Torrente I Kreikemeyer-Lorenzo D Stróżecka A Franke KJ Pascual JI 《Physical review letters》2012,108(3):036801
The electron-acceptor molecule TCNQ is found in either of two distinct integer charge states when embedded into a monolayer of a charge transfer complex on a gold surface. Scanning tunneling spectroscopy measurements identify these states through the presence or absence of a zero-bias Kondo resonance. Increasing the (tip-induced) electric field allows us to reversibly induce the oxidation or reduction of TCNQ species from their anionic or neutral ground state, respectively. We show that the different ground states arise from slight variations in the underlying surface potential, pictured here as the gate of a three-terminal device. 相似文献
993.
Goddard PA Manson JL Singleton J Franke I Lancaster T Steele AJ Blundell SJ Baines C Pratt FL McDonald RD Ayala-Valenzuela OE Corbey JF Southerland HI Sengupta P Schlueter JA 《Physical review letters》2012,108(7):077208
Gaining control of the building blocks of magnetic materials and thereby achieving particular characteristics will make possible the design and growth of bespoke magnetic devices. While progress in the synthesis of molecular materials, and especially coordination polymers, represents a significant step towards this goal, the ability to tune the magnetic interactions within a particular framework remains in its infancy. Here we demonstrate a chemical method which achieves dimensionality selection via preferential inhibition of the magnetic exchange in an S=1/2 antiferromagnet along one crystal direction, switching the system from being quasi-two- to quasi-one-dimensional while effectively maintaining the nearest-neighbor coupling strength. 相似文献
994.
A record is an entry in a time series that is larger or smaller than all previous entries. If the time series consists of independent, identically distributed random variables with a superimposed linear trend, record events are positively (negatively) correlated when the tail of the distribution is heavier (lighter) than exponential. Here we use these correlations to detect heavy-tailed behavior in small sets of independent random variables. The method consists of converting random subsets of the data into time series with a tunable linear drift and computing the resulting record correlations. 相似文献
995.
Susanne Friedreich Daniel Barna Fritz Caspers Andreas Dax Ryugo Hayano Masaki Hori Dezs? Horváth Bertalan Juhász Takumi Kobayashi Oswald Massiczek Anna Sótér Koichi Todoroki Eberhard Widmann Johann Zmeskal 《Hyperfine Interactions》2012,212(1-3):167-177
We shall present here the first experimental results for microwave spectroscopy of the hyperfine structure of antiprotonic He-3 and a comparison to numerical simulations of the measurement. Due to the helium nuclear spin, antiprotonic He-3 has a more complex hyperfine structure than antiprotonic He-4 which has already been studied before. Thus a comparison between theoretical calculations and the experimental results will provide a more stringent test of the three-body quantum electrodynamics (QED) theory. The comparison of measured data to simulations allows to investigate the collisional processes between the helium atoms of the target medium and the antiprotonic helium atomcules. The collision rates can not be calculated exactly, but estimated by comparison of numeric simulations with the experimental results. Two out of four super-super-hyperfine (SSHF) transition lines of the (n, L)?=?(36, 34) state were observed. The measured frequencies of the individual transitions are 11.12559(14)?GHz and 11.15839(18)?GHz, less than 1?MHz higher than the current theoretical values, but still within their estimated errors. The frequency difference between the two lines also agrees with theoretical calculations. 相似文献
996.
Franke AA Custer LJ Morimoto Y Nordt FJ Maskarinec G 《Analytical and bioanalytical chemistry》2011,401(4):1319-1330
Estrogens and other endogenous steroids are known risk markers for cancer. Gas chromatography (GC) with mass spectrometry
(MS) has traditionally predominated the analysis of estrogens and other endogenous steroids, but liquid chromatography (LC)
MS is increasingly favored. Direct comparisons of the two technologies have hitherto not been performed. Steroids were analyzed
from 232 urine samples of 78 premenopausal women in a blinded fashion by benchtop orbitrap LCMS and single quadrupole GCMS.
Sixteen steroidal estrogens including oxidized metabolites could be analyzed by LCMS. LCMS–GCMS Spearman rank correlations
of the major estrogens E1, E2, E3, 16α-OHE1, and 2-OHE1 were very high (r = 0.72–0.91), and absolute concentrations also agreed (<5% difference for E1, E2, E3, 16α-OHE1). LCMS allowed reinterrogation of the acquired data due to orbitrap technology, which permitted post-analysis quantitation
of progesterone, cortisol, and cortisone (LCMS–GCMS Spearman rank correlations = 0.80–0.84; absolute difference, <7%; n = 137). GCMS allows the measurement of a wide range of steroids including non-polar analytes that escape the presented LCMS
assay. In contrast, orbitrap-based LCMS can detect more estrogens, is faster, less costly, allows post-data acquisition reinterrogation
of certain analytes that had not been targeted a priori, and requires much less urine. 相似文献
997.
Nicholls IA Andersson HS Golker K Henschel H Karlsson BC Olsson GD Rosengren AM Shoravi S Suriyanarayanan S Wiklander JG Wikman S 《Analytical and bioanalytical chemistry》2011,400(6):1771-1786
In principle, molecularly imprinted polymer science and technology provides a means for ready access to nano-structured polymeric materials of predetermined selectivity. The versatility of the technique has brought it to the attention of many working with the development of nanomaterials with biological or biomimetic properties for use as therapeutics or in medical devices. Nonetheless, the further evolution of the field necessitates the development of robust predictive tools capable of handling the complexity of molecular imprinting systems. The rapid growth in computer power and software over the past decade has opened new possibilities for simulating aspects of the complex molecular imprinting process. We present here a survey of the current status of the use of in silico-based approaches to aspects of molecular imprinting. Finally, we highlight areas where ongoing and future efforts should yield information critical to our understanding of the underlying mechanisms sufficient to permit the rational design of molecularly imprinted polymers. 相似文献
998.
Foetisch K Dahl L Jansen B Becker WM Lidholm J van Ree R Broll H Kaul S Vieths S Holzhauser T 《Analytical and bioanalytical chemistry》2011,399(2):935-943
Even though carrot allergy is common in Europe, the amount of different allergens in carrots is still unknown due to a lack
of methods for quantitative allergen measurements. The current study aimed at the development of quantitative ELISA tests
for the known carrot allergens, namely Dau c 1.01, Dau c 1.02, and Dau c 4 in pure carrot extracts. Monoclonal antibodies
targeting the major carrot allergen isoforms Dau c 1.01 and Dau c 1.02 were generated and combined in sandwich ELISA with
rabbit antisera against Api g 1, the celery homologue of Dau c 1. A competitive ELISA for the carrot profilin Dau c 4 was
based on a polyclonal rabbit antiserum. The three ELISA tests were allergen-specific and displayed detection limits between
0.4 and 6 ng allergen/ml of carrot extract. The mean coefficient of variation (CV) as a means of intraassay variability of
the Dau c 1.01, Dau c 1.02 and Dau c 4 ELISA tests was 8.1%, 6.9%, and 11.9%, and the mean interassay CV 13.3%, 37.1% and
15.6%, respectively. Target recovery ranged between 93 and 113%. In conclusion, the specific, accurate and reproducible quantification
of three important carrot allergens may help to identify less allergenic carrot varieties, as well as to standardize the amount
of allergens in extracts used for carrot allergy diagnosis. 相似文献
999.
There are several methods for sensitive detection of oversulfated chondroitin sulfate (OSCS) in heparin. Although contamination
with OSCS is unlikely to be repeated, use of other compounds to counterfeit heparin must be considered. We have previously
developed a two-step fluorescence microplate assay (two-step FI assay) for detection of OSCS. First, the heparin sample is
incubated with heparinase I, then its increasing effect on the fluorescence intensity (FI) of the sensor molecule Polymer-H
is measured (PolyH assay). The high sensitivity of the assay is shown to be based on heparinase I inhibition by OSCS. The
objective of this study was to evaluate another assay option — indirect quantification of OSCS after heparinase I incubation
by means of the anti-Factor Xa (aXa) activity of the remaining undegraded heparin (two-step aXa assay). We also examined,
whether other heparin mimetics (HepM), direct Factor Xa inhibitors (DXI), and protein impurities are detectable by use of
these assays. Heparin was spiked with different amounts of HepM including OSCS, pentosan polysulfate, dextran sulfate, curdlan
sulfate, the natural contaminant dermatan sulfate, the DXI rivaroxaban, and BSA as a protein. These samples were compared
with pure heparin in the two-step FI assay, the two-step aXa assay, and in the PolyH assay and the aXa assay without heparinase
I incubation. Both two-step assays sensitively measured contamination with all the HepM (LOD ≤ 0.5%, LOQ ≤ 0.7%). The two-step
aXa assay also detected rivaroxaban (LOD 0.3%, LOQ 0.4%), whereas the two-step FI assay was shown to be suited to determination
of protein impurities (LOD 0.11%, LOQ 0.13%). Use of two different heparinase I inactivation procedures enabled clear differentiation
between protein, HepM, and both contaminants. Finally, with the aXa assay the heparin potency can be determined in the same
assay run, whereas the FI increase in the PolyH assay was shown to be useful for identification. In conclusion, both the two-step
FI assay and the two-step aXa assay are sensitive, rapid, and simple tests for the detection of counterfeit heparin. Comprehensive
information about heparin quality can be obtained by their combined use and the parallel measurement of non-incubated heparin
samples. 相似文献
1000.
Rabagny Y Herrmann W Geisel J Kirsch SH Obeid R 《Analytical and bioanalytical chemistry》2011,401(3):891-899
We describe a fast and robust ultra performance liquid chromatography tandem mass spectrometry method for the quantification
of phospholipid (PL) species in EDTA-plasma samples. We quantified total phosphatidylcholine (PC), phosphatidylethanolamine
(PE), lysophosphatidylcholine (LPC), and sphingomyelin (SM) and several species within these classes using one or two external
calibrators and one internal standard for each class. Inter-assay coefficients of variation were <10% for the most abundant
species and <20% for all quantified PC, LPC, and SM species and the three most abundant PE species. Coefficients of linear
regression were R
2 > 0.98. Mean recoveries were between 83% and 123%. The limits of detection were 0.37 μmol/L for PC, 4.02 μmol/L for LPC,
3.75 μmol/L for PE, and 0.86 μmol/L for SM. Quantification was linear over the physiological ranges for PE, LPC, and SM and
up to 500 μmol/L for PC. The concentrations of PLs in the plasma of healthy donors yielded results that were comparable with
those of previous works. 相似文献