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961.
Gjelstad A Rasmussen KE Pedersen-Bjergaard S 《Analytical and bioanalytical chemistry》2009,393(3):921-928
The present work describes the first systematic study of electromembrane extraction (EME) from biological matrices under physiological
conditions. Six basic drugs with protein binding in the range of 20–97% were extracted from untreated human plasma and whole
blood through a supported liquid membrane (SLM) consisting of 1-ethyl-2-nitrobenzene impregnated in the walls of a hollow
fiber, and into an acidified aqueous solution inside the lumen of the fiber. The electrical potential difference over the
membrane reduced the protein binding of the drugs and transported the free drug fraction over the membrane. Recoveries in
the range 25–65% were obtained with 10-min extraction time and an applied voltage of only 10 V over the SLM. Interday precision
better than 20% RSD and linearity in the range 0.5–10 μg/mL were obtained for nortriptyline and methadone. Extraction from
untreated whole blood was also demonstrated with recoveries in the range 19–51%. 相似文献
962.
We introduce a q-analogue of Wigner’s 9-j symbols following the notational scheme used by Wilson in identifying the 6-j symbols with Racah polynomials, which eventually led Askey and Wilson to obtain a q-analogue of them, namely, the q-Racah polynomials. Most importantly, we prove the orthogonality of our analogues in complete generality, as well as derive an explicit polynomial expression for these new functions. 相似文献
963.
We give a stratification of the GIT quotient of the Grassmannian G
2,n
modulo the normaliser of a maximal torus of SL
n
(k) with respect to the ample generator of the Picard group of G
2,n
. We also prove that the flag variety GL
n
(k)/B
n
can be obtained as a GIT quotient of GL
n+1(k)/B
n+1 modulo a maximal torus of SL
n+1(k) for a suitable choice of an ample line bundle on GL
n+1(k)/B
n+1.
Dedicated to Professor C De Concini on the occasion of his 60th birthday 相似文献
964.
R. V. Ambartzumian 《Journal of Contemporary Mathematical Analysis (Armenian Academy of Sciences)》2009,44(1):25-35
Combinatorial integral geometry possesses some results that can be interpreted as belonging to the field of Geometric Tomography. The main purpose of the present paper is to present a case of parallel X-ray approach to tomography of random convex polygons. However, the Introduction reviews briefly some earlier results by the author that refer to reconstruction of (non-random) convex domains by means of a point X-ray. The main tool in treating the parallel X-rays is disintegrated Pleijel identity, or rather, its averaged version, whose derivation is represented in complete detail. The paper singles out a class of random polygons called tomography models, that offer essential advantages for the analysis. The definition of a tomography model is given in terms of stochastic independence. Fortunately, random translation-invariant Poisson processes of lines in IR 2 suggest a class of examples. We recall that each such line process is determined by its rose of directions ρ(?). For rather general ρ(?), the number weighted typical polygon in the polygonal partition of the plane generated by the corresponding Poisson line process happens to be a tomography model. For general tomography models, a differential equation is derived for the Laplace transform for parallel X-rays, that rises several interesting computational problems. 相似文献
965.
966.
Analysis of the oligomeric state of a native protein usually requires analytical ultracentrifugation or repeated gel filtration to calculate the protein's size. We have developed a discontinuous native protein gel electrophoresis system that allows the separation of even basic proteins according to their size, oligomeric state, and shape. This gel system combines the addition of negative charges to the proteins by Serva Blue G with a discontinuous buffer system and gradient gels. As in SDS-PAGE, chloride constitutes the high mobility anion in the gel and anode buffer. However, for sample focusing this system employs histidine instead of glycine as the slow dipolar ion following from the cathode buffer to improve migration of basic proteins. In addition, proteins run into gel pores corresponding to their size and shape in the gradient gel. Using this gel system, we show that the polypyrimidine tract-binding protein (PTB) is a monomer. 相似文献
967.
The group PGL(2,q) has an embedding into PGL(3,q) such that it acts as the group fixing a nonsingular conic in PG(2,q). This action affords a coherent configuration (q) on the set (q) of non-tangent lines of the conic. We show that the relations can be described by using the cross-ratio. Our results imply that the restrictions
+(q) and
−(q) of (q) to the set
+(q) of secant (hyperbolic) lines and to the set
−(q) of exterior (elliptic) lines, respectively, are both association schemes; moreover, we show that the elliptic scheme
−(q) is pseudocyclic.We further show that the coherent configurations (q
2) with q even allow certain fusions. These provide a 4-class fusion of the hyperbolic scheme
+(q
2), and 3-class fusions and 2-class fusions (strongly regular graphs) of both schemes
+(q
2) and
−(q
2). The fusion results for the hyperbolic case are known, but our approach here as well as our results in the elliptic case are new. 相似文献
968.
An on-line sample stacking method, namely field-amplified sample injection, has been developed for the separation and determination of carnosine, anserine, and homocarnosine by capillary electrophoresis. Using electrokinetic injection, about 130- to 160-fold improvement of sensitivity was achieved without loss of separation efficiency when compared to conventional sample injection. For conventional injection, the samples were dissolved in running buffer and then hydrodynamically injected for 10 s (3.45 kPa). Various parameters affecting separation and sample stacking were optimized. Under optimum conditions, linear responses were obtained over two orders of magnitude and the detection limits (defined as S/N = 3) of carnosine, anserine, and homocarnosine were 1.5 x 10(-8) to 1.6 x 10(-8) mol/L. 相似文献
969.
In this paper, we discuss the effects of cannibalism on a basic stage-structured population model for a single species. A threshold condition for extinction versus persistence is obtained, and numerical simulations of the population dynamics are presented. These simulations suggest that cannibalism has a stabilizing effect on the population, promoting equilibrium of the adult population level. 相似文献
970.
Connectivity of iterated line graphs 总被引:1,自引:0,他引:1
Yehong Shao 《Discrete Applied Mathematics》2010,158(18):2081-2087
Let k≥0 be an integer and Lk(G) be the kth iterated line graph of a graph G. Niepel and Knor proved that if G is a 4-connected graph, then κ(L2(G))≥4δ(G)−6. We show that the connectivity of G can be relaxed. In fact, we prove in this note that if G is an essentially 4-edge-connected and 3-connected graph, then κ(L2(G))≥4δ(G)−6. Similar bounds are obtained for essentially 4-edge-connected and 2-connected (1-connected) graphs. 相似文献