Molar excess Gibbs free energies of mixtures of ethanolamines and water

Thermodynamic information about the vapor—liquid equilibria of systems containing water and ethanolamines is needed in the design and optimization of important industrial processes. This knowledge is also useful in the investigation of some phenomena such as the thermal conversion of ethanolamines or their complexation reactions with metals.Physico-chemical investigations involving aqueous solutions of ethanolamines are scarce, and sometimes contradictory, in the literature. It has been stated [1] that the system diethanolamine—water obeys Raoult's law. However, there have been studies [2] indicating departure from ideal behavior for this system.The purpose of this work was to determine the molar excess Gibbs free energies of the systems formed by water and the ethanolamines.     

Magnetic phase diagram of Ni(NO3)2 6NH3

The magnetic phase diagram of Ni(NO₃)₂6NH₃ was determined from the field and temperature dependence of the magnetic susceptibility. The zero temperature exchange and anisotropy fields were determined to be H_E(0) ≈ 26 kOe and H_A(0) ≈ 0.7 kOe respectively.     

Low temperature ESR in Ni(BrO3)26H2O2

ESR experiments on Ni(BrO₃)₂6H₂O were performed down to liquid helium temperatures, and the g-value, the magnitude and sign of the single-ion anistotropy parameter, and the strength of the Ni²⁺Ni²⁺ exchange interaction, were determined. The present data support a recent interpretation of the susceptibility data for this salt that assumes tetrahedral antiferromagnetism at very low temperatures.     

Short synthesis of the 6,6-spiroketal cores of spirofungins A and B

[reaction: see text] Initial efforts toward the total synthesis of the antifungal antibiotics spirofungins A and B are reported. A short and efficient synthesis of the C9-C20 6,6-spiroketal fragments of both compounds is described. This asymmetric approach uses a very efficient alkylation of a lithiated N,N-dimethylhydrazone followed by spiroketal formation under acidic conditions.     

Determination of mercury(II) by invertase enzyme inhibition coupled with batch injection analysis

The determination of mercury(II) ions at the trace level by inhibition of the invertase enzyme-catalysed hydrolysis of sucrose into glucose and fructose coupled to electrochemical batch injection analysis was investigated using two approaches. In the first, the glucose produced was detected by injection of 100 microliters samples into the batch injection cell containing a platinum electrode modified by immobilised glucose oxidase. In the second, the glucose and fructose present in injected samples were oxidised directly at a copper-modified glassy carbon electrode. The experimental parameters were optimised and the degree of enzyme inhibition by mercury(II) ions under both conditions was measured. Mercury concentrations in the ng ml-1 range were determined by these two techniques with low sample and reagent consumption. Comparison is made between the two methods and perspectives as a screening test for field application are indicated.     

Analysis of phenolic compounds in Spanish Albrariño and Portuguese Alvarinho and Loureiro wines by capillary zone electrophoresis and high-performance liquid chromatography

The concentration of different phenolic compounds was measured in Spanish Albari?o and Portuguese Alvarinho and Loureiro white wines by capillary zone electrophoresis (CZE), in order to characterize them. Although all samples presented the same qualitative pattern (characterized by tyrosol; (-)-epicatechin; syringic acid; ferulic acid; p-coumaric acid; caffeic acid, gallic acid; 3,4-dihydroxybenzoic acid; cis-coumaroyl tartaric acid (COUTA); trans-COUTA; trans-caffeoyl tartaric acid (CAFTA), and hydroxycinnamic esters), some quantitative differences were observed. When samples were analyzed by high-performance liquid chromatography (HPLC), in order to compare the results obtained by both techniques, no significant qualitative or quantitative differences were obtained. Nevertheless, CZE proved to be a more convenient technique for the routinary analyses of these wines, due to better separation of the different compounds, better peak shapes, and higher speed than HPLC.     

The Mass Programme at GANIL Using the CSS2 and CIME Cyclotrons

The mass-measurement programme at GANIL aims to measure the masses of heavy nuclei close to the N=Z line which is the ideal region to study neutron-proton pairing. An original direct time-of-flight mass-measurement method was developed at GANIL which uses the CSS2 cyclotron as a high-resolution spectrometer. The masses of ions of A=68,76,80 and 100 have been measured with a precision of a few 10⁻⁶. Mass measurements will be performed with the new CIME cyclotron of SPIRAL using a similar method based on the measurement of the phase of the accelerated ions for different radio-frequencies. A recently approved experiment will help develop this new technique and aims to measure the mass of ³¹Ar radioactive nuclei with a precision of 10⁻⁶. This revised version was published online in July 2006 with corrections to the Cover Date.     

Shape Coexistence and the N=28 Shell Closure Far from Stability

A mass measurement experiment by a time of flight method with the SPEG spectrometer at GANIL has been performed to investigate the N=20 and N=28 shell closures far from stability. The masses of 31 neutron-rich nuclei in the range A=29–47 have been measured. The precision of 19 masses has been significantly improved and 12 masses were measured for the first time. The neutron-rich Cl, S and P isotopes are seen to exhibit a change in shell structure around N=28. Comparison with shell model and relativistic mean field calculations demonstrate that the observed effects arise from deformed prolate ground state configurations associated with shape coexistence. The evidence of an isomeric state in the ⁴³S and its interpretation by a shell model calculation confirm the analysis of the masses and constitutes the first evidence of the predicted shape coexistence around N=28. This revised version was published online in July 2006 with corrections to the Cover Date.