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201.
Testosterone metabolism revisited: discovery of new metabolites 总被引:1,自引:0,他引:1
Oscar J. Pozo Josep Marcos Rosa Ventura Andreu Fabregat Jordi Segura 《Analytical and bioanalytical chemistry》2010,398(4):1759-1770
The metabolism of testosterone is revisited. Four previously unreported metabolites were detected in urine after hydrolysis
with KOH using a liquid chromatography–tandem mass spectrometry method and precursor ion scan mode. The metabolites were characterized
by a product ion scan obtained with accurate mass measurements. Androsta-4,6-dien-3,17-dione, androsta-1,4-dien-3,17-dione,
17-hydroxy-androsta-4,6-dien-3-one and 15-androsten-3,17-dione were proposed as feasible structures for these metabolites
on the basis of the mass spectrometry data. The proposed structures were confirmed by analysis of synthetic reference compounds.
Only 15-androsten-3,17-dione could not be confirmed, owing to the lack of a commercially available standard. That all four
compounds are testosterone metabolites was confirmed by the qualitative analysis of several urine samples collected before
and after administration of testosterone undecanoate. The metabolite androsta-1,4-dien-3,17-dione has a structure analogous
to that of the exogenous anabolic steroid boldenone. Specific transitions for boldenone and its metabolite 17β-hydroxy-5β-androst-1-en-3-one
were also monitored. Both compounds were also detected after KOH treatment, suggesting that this metabolic pathway is involved
in the endogenous detection of boldenone previously reported by several authors. 相似文献
202.
Javier Mazuela Alexander Paptchikhine Oscar Pàmies Pher G. Andersson Montserrat Diéguez 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(15):4567-4576
A library of readily available phosphite–oxazole/thiazole ligands ( L1 a – g – L7 a – g ) was applied in the Ir‐catalyzed asymmetric hydrogenation of several largely unfunctionalized E‐ and Z‐trisubstituted and 1,1‐disubstituted terminal alkenes. The ability of the catalysts to transfer chiral information to the product could be tuned by choosing suitable ligand components (bridge length, the substituents in the heterocyclic ring and the alkyl backbone chain, the configuration of the ligand backbone, and the substituents/configurations in the biaryl phosphite moiety), so that enantioselectivities could be maximized for each substrate as required. Enantioselectivities were therefore excellent (enantiomeric excess (ee) values up to >99 %) for a wide range of E‐ and Z‐trisubstituted and 1,1‐disubstituted terminal alkenes. The biaryl phosphite moiety was a very advantageous ligand component in terms of substrate versatility. 相似文献
203.
The present paper deals with the formulation of minimal loading conditions for the application of numerical homogenisation techniques, namely the FE2 methodology. Based on the set of volume averaging rules connecting the heterogeneous micro and the homogeneous macro scale, the minimal constraints on the deformation of a micro volume are derived for a classical Cauchy continuum as well as for a micromorphic continuum theory. For both cases, numerical studies are included highlighting the main aspects of the proposed procedure within the context of small deformations. (© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
204.
A completely automated flow-injection system was developed for the monitoring of biosorption studies of Cu(II) ion on vegetable waste by-products. The system employed flow-through Cu(II)-selective electrodes, of epoxy-resin-CuS/Ag2S heterogeneous crystalline type, and computer controlled pumps and valves for the flow operation. Computer automation was done through a specially devised virtual instrument, which commanded and periodically calibrated the system, allowing for the monitoring of Cu(II) ions between 0.6 and 6530 mg L−1 at a typical frequency of 15 h−1. Grape stalk wastes were used as biosorbent to remove Cu(II) ions in a fixed-bed column with a sorption capacity of 5.46 mg g−1, obtained by the developed flow system, while the reference determination performed by FAAS technique supplied a comparable value of 5.41 mg g−1. 相似文献
205.
Angel Mulero María I. Parra Francisco L. Román Santiago Velasco 《The Journal of chemical thermodynamics》2010,42(7):938-946
In this work, we use a general expression to accurately correlate the liquid density, the vaporization enthalpy, the surface tension, and the isobaric heat capacity of a saturated liquid versus temperature along the whole coexistence curve. The general expression used is the same for the four thermodynamic properties, and uses both critical and triple point values as reference. As representative examples of the use of the model, results are given for a set of 22 pure substances. We find that this general expression correlates the data with smaller or similar overall deviations when compared with other published models whose number of coefficients are the same or greater. 相似文献
206.
J. Oscar Gonz??lez-Cervantes M. E. Luna-Elizarrar??s M. Shapiro 《Complex Analysis and Operator Theory》2011,5(1):237-251
This is a continuation of our work (González-Cervantes et al. in On the Bergman theory for solenoidal and irrotational vector
fields. I. General theory. Operator theory: advances and applications. Birkhauser, accepted) where for solenoidal and irrotational
vector fields theory as well as for the Moisil–Théodoresco quaternionic analysis we introduced the notions of the Bergman
space and the Bergman reproducing kernel and studied their main properties. In particular, we described the behavior of the
Bergman theory for a given domain whenever the domain is transformed by a conformal map. The formulas obtained hint that the
corresponding objects (spaces, operators, etc.) can be characterized as conformally covariant or invariant, and in the present
paper we construct a series of categories and functors which allow us to give such characterizations in precise terms. 相似文献
207.
Time and space assembly line balancing considers realistic multi-objective versions of the classical assembly line balancing industrial problems. It involves the joint optimisation of conflicting criteria such as the cycle time, the number of stations, and/or the area of these stations. The different problems included in this area also inherit the precedence constraints and the cycle time limitations from assembly line balancing problems. The presence of these hard constraints and their multi-criteria nature make these problems very hard to solve. Multi-objective constructive metaheuristics (in particular, multi-objective ant colony optimisation) have demonstrated to be suitable approaches to solve time and space assembly line balancing problems. The aim of this contribution is to present a new mechanism to induce diversity in an existing multi-objective ant colony optimisation algorithm for the 1/3 variant of the time and space assembly line balancing problem. This variant is quite realistic in the automative industry as it involves the joint minimisation of the number and the area of the stations given a fixed cycle time limit. The performance of our proposal is validated considering ten real-like problem instances. Moreover, the diversity induction mechanism is also tested on a real-world instance from the Nissan plant in Barcelona (Spain). 相似文献
208.
Martín Egozcue Luis Fuentes García Wing-Keung Wong Ričardas Zitikis 《Central European Journal of Mathematics》2011,9(6):1288-1297
We show that Grüss-type probabilistic inequalities for covariances can be considerably sharpened when the underlying random
variables are quadrant dependent in expectation (QDE). The herein established covariance bounds not only sharpen the classical
Grüss inequality but also improve upon recently derived Grüss-type bounds under the assumption of quadrant dependency (QD),
which is stronger than QDE. We illustrate our general results with examples based on specially devised bivariate distributions
that are QDE but not QD. Such results play important roles in decision making under uncertainty, and particularly in areas
such as economics, finance, and insurance. 相似文献
209.
Janssen SA Vos H van Kempen EE Breugelmans OR Miedema HM 《The Journal of the Acoustical Society of America》2011,129(4):1953-1962
Recently, it has been suggested that the annoyance of residents at a given aircraft noise exposure level increases over the years. The objective of the present study was to verify the hypothesized trend and to identify its possible causes. To this end, the large database used to establish earlier exposure-response relationships on aircraft noise was updated with original data from several recent surveys, yielding a database with data from 34 separate airports. Multilevel grouped regression was used to determine the annoyance response per airport, after which meta-regression was used to investigate whether study characteristics could explain the heterogeneity in annoyance response between airports. A significant increase over the years was observed in annoyance at a given level of aircraft noise exposure. Furthermore, the type of annoyance scale, the type of contact, and the response percentage were found to be sources of heterogeneity. Of these, only the scale factor could statistically account for the trend, although other findings rule it out as a satisfactory explanation. No evidence was found for increased self-reported noise sensitivity. The results are of importance to the applicability of current exposure-annoyance relationships for aircraft noise and provide a basis for decisions on whether these need to be updated. 相似文献
210.
We study slow-light performance of molecular aggregates arranged in nanofilms by means of coherent population oscillations. The molecular cooperative behavior inside the aggregate enhances the delay of input signals in the gigahertz range in comparison with other coherent population oscillation-based devices. Moreover, the problem of residual absorption present in coherent population oscillation processes is removed. We also propose an optical switch between different delays by exploiting the optical bistability of these aggregates. 相似文献