K-shell ionization in 7.5- and 8.6-MeV/a.m.u. U+U collisions at very small impact parameters

K-vacancy production probabilities in elastic 7.5- and 8.6-MeV/a.m.u. U+U collisions are reported for impact parameters less than 15 fm. In 7.5-MeV/a.m.u. U+U collisions the ionization probability rises above the trend indicated by larger impact parameter measurements, increasing to 1.8 vacancies per collision at the smallest impact parameter. The measured probabilities for 8.6-MeV/a.m.u. collisions increase to a maximum value of slightly less than 2 vacancies per collision at the smallest impact parameters. The data is compared to previous results and existing theory.     

Capillary gas chromatography-mass spectrometry of volatile and semi-volatile compounds of Salvia officinalis

The essential oil and infusion of Salvia officinalis leaves have been widely applied in traditional medicine since ancient times and nowadays subjected to extensive research of their antibacterial, antiviral and cytotoxic properties. This paper shows chemical composition data of S. officinalis leaves essential oil isolated by steam distillation using a Clevenger-type apparatus. Also, the paper presents the chemical content of volatile and semi-volatile compounds of S. officinalis leaves infusion. The volatile and semi-volatile compounds of S. officinalis leaves infusion were isolated by solid-phase extraction (SPE) and liquid-liquid extraction with hexane and dichloromethane. SPE was carried out on 500 mg octadecylsilane (C18) cartridges and elution with dichloromethane. Liquid-liquid extraction was performed with hexane and dichloromethane. The essential oil in dichloromethane and infusion extracts in hexane and dichloromethane were analyzed by gas chromatography coupled with mass spectrometry. The quantitative results obtained by solid-phase extraction and liquid-liquid extraction showed that SPE on C18 performed the highest recovery of the volatile compounds from infusion sample.     

Amination of 3,6-dinitro-1,8-naphthyridines

Treatment of 2-amino-3,6-dinitro-1,8-naphthyridines with liquid ammonia/potassium permanganate gives 2,4-diamino-3,6-dinitro-1,8-naphthyridine. From 2-ethoxy-3,6-dinitro-1,8-naphthyridine a mixture of 4-amino-and 5-amino-3,6-dinitro-1,8-naphthyridine was obtained. 2-Chloro-3,6-dinitro-1,8-naphthyridine afforded a mixture of four compounds i. e. 2,4- and 2,5-diamino-3,6-dinitro-1,8-naphthyridine and 2-chloro-5-amino-3,6-dinitro-1,8-naphthyridine and 2-amino-3,6-dinitro-1,8-naphthyridine. A study on covalent amination has shown that 4-amino-2-ethoxy-3,6-dinitro-1,8-naphthyridine undergoes covalent amination at C-5, whereupon in this adduct amino-deethoxylation takes place. In a similar way, 2-chloro- and 2-ethoxy-5-amino-3,6-dinitro-1,8-naphthyridine give covalent amination at C-4.     

Refinement of the (NH4)3H(SO4)2 crystal structure: II. X-ray and neutron single-crystal diffraction from phase II at room temperature

The crystal of (NH₄)₃H(SO₄)₂ is of special interest due to the possible influence of ammonium ion on the series of phase transitions: I↔II↔ III↔IV↔V↔VII. Earlier, the x-ray single-crystal diffraction study of phase II of the (NH₄)₃H(SO₄)₂ crystal showed that the crystal structure of this compound had two crystallographically independent groups of the ammonium ions NH₄(1) and NH₄(2) but orientational positions of these ammonium ions were not determined exactly. The refinement of the NH₄(1) and NH₄(2) orientational positions in phase II was carried out by the x-ray and neutron single-crystal diffraction study. The analysis of difference Fourier maps of electron charge density and nuclear density suggested the possibility of disordering of NH₄(2) ammonium ions. The text was submitted by the authors in English.     

Nuclear multifragmentation, percolation, and the fisher droplet model: common features of reducibility and thermal scaling

It is shown that the Fisher droplet model, percolation, and nuclear multifragmentation share the common features of reducibility (stochasticity in multiplicity distributions) and thermal scaling (one-fragment production probabilities are Boltzmann factors). Barriers obtained, for cluster production on percolation lattices, from the Boltzmann factors show a power-law dependence on cluster size with an exponent of 0.42+/-0.02. The EOS Collaboration Au multifragmentation data yield barriers with a power-law exponent of 0.68+/-0.03. Values of the surface energy coefficient of a low density nuclear system are also extracted.     

Particle-image-velocimetry applied to thermocapillary convection

Thermocapillary convection is studied experimentally using particle-image-velocimetry for flow visualization and analysis. This method offers the advantage of measuring the entire flow field (velocity field, streamlines etc.) in a selected plane within the fluid at a given instant of time in contrast to point by point methods like laser-Doppler-velocimetry (LDV). The paper describes the method and presents quantitative results for different Marangoni numbers.Presented in part at the VIIth European Symposium on Materials and Fluid Sciences in Microgravity, Oxford University, UK, September 10–15, 1989     

Angular momentum,statistical equilibrium and sequential fission in very asymmetric systems

The in-and out-of-plane angular distributions for fission fragments in coincidence with projectile-like products from the reaction of 252 MeV²⁰Ne with¹⁹⁷Au and²³⁸U have been measured. The results are compared to a statistical model which has successfully explainedγ-ray anisotropies from a heavy symmetric system. The agreement is rather good after proper consideration of the direction of the line-of-centers at contact.     

Acidites et complexes des acides (alkyl- et aminoalkyl-) phosphoniques—II: Affinement multiparametrique applique aux complexations suivies par potentiometrie

The determinations are based on potentiometric titration data (volume of reagent, potential). To avoid any systematic error, the acidity constants are refined together with every other significant parameter (initial protolyte concentration, concentration of impurities, electrode chain characteristics …) with the program MUPROT. Comparison of the multiparametrically adjusted results with those obtained by the usual methods reveals noticeable discrepancies. Particular attention is paid to carbonate as impurity; to take it into account, modified expressions for the titrant volume are established. The current of nitrogen used in the classical methods shifts the liquid-gas equilibrium of carbonic acid; in that case, only the approximate equations are to be considered. Working with a closed system is proposed as a more rigorous procedure.     

Very light neutron-rich nuclei studied via the (6Li, 8B) reaction

Results from investigations of the $\text{T}{}_{\mathrm{z}}\text{=}\text{3}\text{2}$ nuclei ⁵H, ⁷He and ⁹Li and of the T = 1 nuclide ⁴H employing the (⁶Li, ⁸B) reaction at 80 and 93 MeV are presented. In ⁹Li the locations of several low-lying Ip shell levels are indicated; in ⁷He and ⁴H the ground states are clearly observed. No evidence is found for the formation of a narrow ⁵H ground state.