Determination of some banned stimulants in sports by micellar liquid chromatography

Summary A procedure has been developed for the determination, in <12 min, of several stimulants (amphetamine, ephedrine, methoxyphenamine, phenylephrine and phenylpropanolamine) in spiked urine samples after direct injection, using a hybrid micellar mobile phase of 0.15 M sodium dodecyl sulfate and 3% pentanol at pH 7, on a C₁₈ column with UV detection. Recoveries were 94–102% and limits of detection 4.5 ng·mL⁻¹ for methoxyphenamine and 0.39 μg·mL⁻¹ for amphetamine, similar to those obtained for aqueous solutions. Linearity reached 0.99 and intermediate precision was <8.4 and 5.3, for the two different concentrations tested.     

On actually computable bijections between ℕ and Q +

We present three different ways of getting an actually computable enumeration of Q ⁺ in the sense of being able to know exactly which rational occupies a given position and vice versa. The first enumeration is based on the Pierce expansion model for representing real numbers. The other two are based on regular continued fractions.The first and third authors were supported by UPF Grant, Support d'Iniciació a la Recerca, # F3087613.     

Processing effects of nanometric rare earth-doped tin oxides on the synthesis of methyl vinyl ketone

Nanoparticle catalysts based on SnO₂ were processed by two different methods, víz.the polymeric precursor and high-energy mechanical milling. The sample morphology and catalytic performance in the aldol condensation between methanol and acetone were modified by the processing and rare earth doping. This revised version was published online in August 2006 with corrections to the Cover Date.     

On complex structures in 8-dimensional vector bundles

Necessary and sufficient conditions for the existence of a complex structure in an 8-dimensional spin vector bundle over a closed connected spin manifold of dimension 8 are given in terms of characteristic classes. The result completes the papers by Heaps [H] and Thomas [T] on the same topic. Research supported by the grant 201/96/0310 of the Grant Agency of the Czech Republic.     

Cohomology of the Grothendieck construction

We consider cohomology of small categories with coefficients in a natural system in the sense of Baues and Wirsching. For any functor L : K → CAT, we construct a spectral sequence abutting to the cohomology of the Grothendieck construction of L in terms of the cohomology of K and of L(k), for k ∈ ObK.The first author was supported by DFG at University of BielefeldThe second author is a researcher from CONICET, Argentina     

On Lattice Structure of the Space of Pointwise Limits of Harmonic Functions

Let H¹(U) denote the space of all pointwise limits of bounded sequences from H(U), where H(U) consists of all continuous functions on the closure [`(U)]\overline{U} of a bounded open set U⊂ℝ^m that are harmonic on U. It is shown that the space H¹(U) is a lattice in the natural ordering if and only if the set ∂_regU of all regular points of U is an F_σ-set.     

On the existence of the derivative of the volume average

A general theorem on the derivative of the volume average is formulated and proved. Conditions for the existence of the derivative are presented and discussed. This is done in order to give a better base to the theory of spatial averaging.Latin Letters E ₃ three-dimensional vector space over the field of real numbers - K, K(x) averaging domain - G, G _w, G_s open sets in E ₃; components of the two-phase system - C ¹(G) the set of functions 1-times continuously differentiable in G - W1/2(G) Sobolev space - V volume of the domain K - f function defined in G, G _w - K _infi ^sup* (x), K _infi ^sup– (x) special parts of K(x) Greek Letters boundary of G, G _w, G_s; w-s interface - _ij Kronecker delta - v unit outward normal of G, G _w - _j j-dimensional Lebesgue measure Other M closure of a set M in the metric space E ₃ - f phase average of f for the w-phase - (u, v) scalar product of u, v in E ₃ - one-sided derivatives     

Regional Blow-up for a Doubly Nonlinear Parabolic Equation with a Nonlinear Boundary Condition

In this work, positive solutions to a doubly nonlinear parabolic equation with a nonlinear boundary condition are considered. We study the problem where 0 < m, r, α < ∞ are parameters. It is known that for some values of the parameters there are solutions that blow up in finite time. We determine in terms of α ,m, r the blow-up sets for these solutions. We prove that single point blow-up occurs if max{m, r} < α, global blow-up appears for the range of parameters 0 < m < α < r and regional blow-up takes place if 0 < m < α = r and . In this case the blow-up set consists of the interval .     

A comparison of fluorescein and deuterated water as tracers for determination of constructed wetland retention time

Retention time of treated water in a horizontal subsurface flow constructed wetland was determined in the non-vegetative period using fluorescein and deuterium oxide. Fluorescein served as one of the most frequent tracers detectable at extremely low concentrations by fluorimetry; however, deuterated water (concentrations of deuterium measured by IRMS and expressed as δ (‰) against VSMOW) was used to precisely simulate the treated water flow movement. Tracer retention time (TRT) of fluorescein was 194 h while deuterated water TRT was 192 h. TRT and nominal hydraulic retention time (nHRT, 190 h) were nearly exactly equal. The tracer behavior of deuterated water was almost ideal. On the other hand, the fluorescein movement through the system was slightly influenced by the interaction with the vegetation bed (sorption causing the tailing of tracer-response curves). Nevertheless, both tracers can be successfully used and provide similar results. Retention time is a very important characteristic of a constructed wetland. It is closely connected with the efficiency of the contaminant removal from treated water. It has to be determined correctly when wetland operation parameters are optimized. The choice of the suitable and reliable tracer is always necessary. Fluorescein takes preference with respect to its simple and inexpensive determination.