Permutable pairs of quasi-uniformities

We continue investigating the lattice (q(X),⊆) of quasi-uniformities on a set X. In particular in this article we start investigating permutable pairs of quasi-uniformities. Among other things, we show that the Pervin quasi-uniformity of a topological space X permutes with its conjugate if and only if X is normal and extremally disconnected.     

LC-MS/MS fast analysis of androgenic steroids in urine

The liquid chromatography-tandem mass spectrometry method (LC-MS/MS) was developed and validated to detect androgenic steroids: trenbolone, nortestosterone, boldenone, methylboldenone, testosterone, methyltestosterone, 17β-1-testosterone and their metabolites in bovine urine. Sample preparation before LC-MS/MS analysis involved an enzymatic hydrolysis with glucuronidase AS-HP, isolation of free hormones from urine on C(18) SPE column and purification of the extract using liquid-liquid extraction with n-pentane and SPE NH(2) column. For the chromatographic separation of steroids, the Poroshell 120-EC C18 column (150?×?2.1 mm, 2.7 μm) was used. Mass spectrometric measurement was achieved using the API 4000 triple quadrupole (QqQ) instrument with a TurboIon-Spray source operating in positive electrospray ionization mode. The procedure was validated according to the Decision 2002/657/EC. Recovery ranged from 76.5% to 118.9% for all examined compounds. The repeatability was below 20% and reproducibility did not exceed the 25%. The linearity was good for all analytes in the whole range of tested concentrations, as proved by the correlation coefficients greater than 0.99. The decision limit (CCα) ranged from 0.10 to 0.17 μg L(-1) for all analytes, whereas the detection capability (CCβ) ranged from 0.17 to 0.29 μg L(-1). The application of an innovative Poroshell column allowed for very good chromatographic separation of steroids with a much shorter time of analysis.     

Investigation of temperature dependence of neutron yield and electron screening potential for the d(d, n)3He reaction proceeding in deuterides ZrD2 and TiD2

The temperature dependence of the enhancement factor for the dd reaction proceeding in TiD₂ and ZrD₂ is investigated. The experiments were carried out at the Hall pulsed ion accelerator (INP, Polytechnic University, Tomsk, Russia) in the deuteron energy interval 7.0?C12.0 keV and at temperatures ranging from 20 to 200°C. The values obtained for the electron screening potentials indicate that the dd reaction enhancement factor does not depend on the target temperature in the range 20?C200°C. This result contradicts the conclusions drawn by the LUNA Collaboration from their work.     

Experimental determination of the electron screening potential energy for the d(d, n)3He Reaction in ZrD2 and D2O in the ultralow energy region

This work is devoted to measuring of the values of the astrophysical S-factors and electron screening potential energy for a d(d,n)³He reaction occurring at ultralow energies in zirconium deuteride ZrD₂ (3.5–7.0 keV) and heavy water D₂O (2.2–6.0 keV). The experiment was performed on the Hall pulsed plasma accelerator at the TPU Nuclear Physics Institute (Tomsk) with ZrD₂ and D₂O targets produced by the magnetron sputtering of zirconium in a deuterium environment and heavy water freezing-out on a copper support, respectively. A χ ² analysis of the dependence of the neutron yields and astrophysical S-factors for the dd reaction on the deuteron collision energy E revealed that the upper bounds of the electron screening potential energy for interacting deuterons in ZrD₂ and D₂O and of the astrophysical S-factors at the deuteron collision energy E = 0 were U _e (ZrD₂) < 30 eV, U _e (D₂O) < 25 eV, S(0) = (57.2 ± 3.9) keV · b (ZrD₂), S(0) = (58.6 ± 3.6) keV · b (D₂O) at the 90% confidence level.     

Synthesis and Characterization of Some Ru(tmeda) Complexes Containing Chloride, Hydride, and Vinylidene Ligands

Summary.  The polymeric compound [Ru(cod)Cl₂] _x (cod = cyclooctadiene) reacts with 2 equivalents of tmeda (N,N,N′,N′-tetramethylethylenediamine) in refluxing MeOH to afford trans-[Ru(cod)(tmeda)(Cl)(H)] (1), which upon treatment with CHCl₃ is readily converted to the dichloro complex trans-[Ru(cod)(tmeda)Cl₂] (2). When [Ru(cod)Cl₂] _x is reacted with tmeda under an atmosphere of H₂ (3 bar), the bis-tmeda complex trans-[Ru(tmeda)₂Cl₂] (3) is obtained in 80% yield. DFT calculations revealed that 3 is by 52 kJ/mol more stable than the corresponding cis isomer. Attempts to prepare the coordinatively unsaturated complex [Ru(tmeda)₂Cl]⁺ by reacting 1 with TICF₃SO₃ were unsuccessful. According to DFT calculations, however, such a complex should be stable and, interestingly, should adopt a square pyramidal rather than a trigonal bipyramidal structure. If halide abstraction of 3 is performed in the presence of terminal alkynes HC*CR (R*t-Bu, n-Bu), the cationic vinylidene complexes [Ru(tmeda)₂(Cl)(*C*CHR)]⁺ (4a,b) are obtained. Received March 26, 2001. Accepted April 26, 2001     

Correlation of Metal and trans-Resveratrol Concentrations in Red Wine

Red wine samples were analyzed for Al, Cu, Zn, and Pb by inductively coupled plasma–mass spectrometry following microwave digestion. trans-Resveratrol was determined by high-performance liquid chromatography with a diode array detector using a C18 column and 25% aqueous acetonitrile as the mobile phase. trans-Resveratrol was present at concentrations of 0.4863–1.1840?mg?L^?1 and the values were inversely proportional to the results for aluminum and copper.     

Early construction of number as position with young children: a teaching experiment

Our study is motivated by the importance of the number line in the visualisation of elementary properties of operations and numbers. For the number line to be an aid for visualisation, first it must be conceived as a coordinate system (origin, orientation and unit). This paper focuses on the construction of the concept of position on a line, and on the number as a means of remembering position, for pre-elementary school children aged 5–6 years. Using didactic design as a methodology, we conducted an experiment to observe how knowledge was constructed while carrying out a certain kind of task in a situation where position had to be designated. Our study shows that pupils, despite recognising number as a quantity, fail to apprehend number as something which represents position. They are, however, capable of understanding the characteristic elements of the number line in suitable situations. Our research suggests that it is possible to teach the use of ordinal numbers to young pupils.     

Evidence for the characterization of heavy-ion reactions by the ratioE/B

The connection between the characteristic features of reactions involving very heavy target-projectile combinations (e.g.⁸⁶Kr+¹⁹⁷Au) and lighter systems (e.g.⁴⁰Ar+^natAg) is discussed. Evidence for an empirical scaling law based upon the ratioE/B (center-of-mass kinetic energy to Coulomb barrier) is presented. This scaling is justified in terms of semiquantitative arguments whereby the different charge and angular distribution patterns from light and heavy target-projectile combinations are correlated with different lifetime regimes for the “intermediate complex” as it diffuses along the mass-asymmetry coordinate.     

Multiplicity in proton-nucleus interactions in emulsion at 800 GeV

The experimental data on multiplicities of charged particles of different type produced in incoherent interactions of 800 GeV proton with emulsion nuclei are reported and discussed. The data are compared with the results of other experiments on protonnucleus collisions at lower energies. It is shown that the Lund model describes well the data on multiplicities of relativistic particles.