Structures based on the 3-connected net 103-b

The net 10³-b, one of the two simplest 3D 3-connected nets, is a periodic network of 3-connected points in which all the shortest circuits are 10-gons. Some configurations of this net are described, and examples are given of structures based on the net, in particular those formed from tetrahedral or octahedral coordination groups each joined to three other similar groups by sharing appropriate numbers of X atoms. Structures in which each X atom is 2-connected may be constructed from tetrahedral AX₄ groups (AX₂ and A₂X₅) and from octahedral AX₆ groups (AX₃, A₂X₇, AX₄, and A₂X₉). At present, however, examples are known only of A₂X₅ structures.     

Measurement of the structure functionsF 2 andxF 3 and comparison with QCD predictions including kinematical and dynamical higher twist effects

The isoscalar nucleon structure functionsF ₂(x, Q ²) andxF ₃(x, Q ²) are measured in the range 0<Q ²<64 GeV², 1.7<W ²<250 GeV²,x<0.7 using ν and \(\bar v\) interactions on neon in BEBC. The data are used to evaluate possible higher twist contributions and to determine their impact on the evaluation of the QCD parameter Λ. In contrast to previous analyses reaching to such lowW ² values, it is found that a low \(\Lambda _{\overline {MS} } \) value in the neighbourhood of 100 MeV describes the data adequately and that the contribution of dynamical higher twist effects is small and negative.     

Lanthanide-daunomycin interactions. Predominance of ML2 at low metal to ligand ratios

Spectroscopic investigations have been undertaken on the effects of lanthanide ions on the spectrum of the anticancer agent, daunomycin. The visible spectral perturbations due to the metal ions resulted in hypochromic effects in the 480 nm region and in shifts towards longer wavelength. The different metal ions investigated did not give any significant difference in the, spectral character. Data analysis according to the methods of molar ratio, continuous variation and graphical approaches based on simplex matrix theory indicated the presence of predominantly a ML₂ species at metal to ligand ratios, less than one. Data also suggested the presence of ML and ML₃ as well.     

Taonianone,a new diterpene from the brown alga Taonia australasica

Taonianone, a diterpene with a novel carbocyclic ring system has been isolated from the brown alga $\text{Taonia australasica}$.     

Ions in Aqueous Acetic Acid Mixtures: Solvent Reorganization around Protons and Gibbs Energies of Transfer from Water

The photo-absorbing, basic sensor, 4-nitroaniline, has been used to determine theequilibrium constant for solvent reorganization around the proton in mixtures ofvarying composition of water with acetic acid. In all the mixtures used, theself-ionization of the acetic acid was suppressed. In contrast to mixtures of waterwith the related ethanol or acetone, this equilibrium is shifted more toward thewater-solvated species as the mole fraction x ₂ of the cosolvent increases. TheGibbs energy of transfer of protons from water into the mixture G ^o _t (H⁺) can bederived with the aid of this equilibrium constant for the solvent reorganization.Using G ^o _t (H⁺), G ^o _t (i) for i denoting anions and other cations can be evaluated.In comparison the G ^o _t (i) for cations have lower negative values than when eitherethanol or acetone is added to water. Correspondingly, for halide anions, thepositive G ^o _t (i) with added acetic acid are rather less than is found with eitherethanol or acetone added. The influence on the ion-solvent interaction of bothelectron withdrawing hydroxy and carbonyl groups in acetic acid may beresponsible for this. Although G ^o _t (i) for C10^– ₄ and Re0^– ₄ are also positive, both picrateions and OH^– give negative values with acetic acid added to water. With picrateions, the hydrophobic effect of the carbon ring produces stabilization in themixture relative to water. With OH^–, complete conversion to acetate anionsoccurs. As is found with other cosolvents, the contribution of the charge onacetate anion to G ^o _t (CH₃COO^–) is found to increase as x ₂ rises. The aciddissociation constant K _a for acetic acid is found to decrease slowly as x ₂ rises to0.5, followed by a rapid decrease for x ₂ greater than 0.7 where dimerization ofacetic acid occurs.     

Ueber die Bestimmung der Phosphors?ure

Ohne Zusammenfassung     

Solubility of dichlorotetraalkylpyridinecobalt III hexachlororhenate(IV) in water + methanol mixtures: Free energies of transfer of the complex cation from water into the mixtures

The solubility of salts [Co(3Rpy)₄Cl₂]₂]ReCl₆] has been determined in water + methanol mixtures. By comparing these with the solubilities of the salt Cs₂ReCl₆ and using calculated activity coefficients for the ions in the water+methanol mixtures, values for {G _t ^o (Co(3Rpy)₄Cl ₂ ⁺ )–G _t ^o (Cs⁺)} can be determined where G _t ^o is the standard Gibbs free energy of transfer from water to an aqueous mixture. G _t ^o (Cs⁺) from the solvent sorting scale and from the TPTB scale are then used to calculate G _t ^o (Co(3Rpy)₄Cl ₂ ⁺ ). These two sets of values for G _t ^o (Co(3Rpy)₄Cl ₂ ⁺ ) on the differing scales are then inserted into a free energy cycle applied to the bond extension Co(3Rpy)₄Cl ₂ ⁺ (initial state)Co(3Rpy)₄Cl²⁺+Cl^– (transition state) for the solvolysis in water and in water + methanol mixtures to produce values for G _t ^o (Co(3Rpy)₄Cl²⁺) using both scales. Data for the solubilites of [Copy₄Cl₂]₂[ReCl₆] and [Co(4Rpy)₄Cl₂]₂[ReCl₆] have been re-calculated to compare free energies of transfer for these complex cations with those specified above.     

Measurement of bumetanide in plasma and urine by high-performance liquid chromatography and application to bumetanide disposition.

A high-performance liquid chromatographic method for the measurement of bumetanide in plasma and urine is described. Following precipitation of proteins with acetonitrile, bumetanide was extracted from plasma or urine on a 1-ml bonded-phase C18 column and eluted with acetonitrile. Piretanide dissolved in methanol was used as the internal standard. A C18 Radial Pak column and fluorescence detection (excitation wavelength 228 nm; emission wavelength 418 nm) were used. The mobile phase consisted of methanol-water-glacial acetic acid (66:34:1, v/v) delivered isocratically at a flow-rate of 1.2 ml/min. The lower limit of detection for this method was 5 ng/ml using 0.2 ml of plasma or urine. Nafcillin, but not other semi-synthetic penicillins, was the only commonly used drug that interfered with this assay. No interference from endogenous compounds was detected. For plasma, the inter-assay coefficients of variation of the method were 7.6 and 4.4% for samples containing 10 and 250 ng/ml bumetanide, respectively. The inter-assay coefficients of variation for urine samples containing 10 and 2000 ng/ml were 8.1 and 5.7%, respectively. The calibration curve was linear over the range 5-2000 ng/ml.