Proton conductivity of imidazole entrapped in microporous molecular sieves.

Imidazole embedded in molecular sieves shows remarkable and steady proton conductivity (>1 × 10-5 S cm-1 above 360 K). It can be considered to be a promising solid high proton conducting electrolyte for fuel cells. The conductivity depends on imidazole loading and mobility, which result from the pore geometry, the chemical nature of matrices and the preparation method.

Linear coordination polymers based on aluminum phosphates: synthesis, crystal structure and morphology.

Several aluminum tris(diorganophosphates) have been synthesized and characterized via elemental analysis, NMR, FT-IR and Raman spectroscopy, as well as powder XRD, and SEM. Single-crystal X-ray diffraction studies revealed that the aluminum tris(diethylphosphate) crystal structure comprises two crystallographically nonequivalent catena-Al[O2P(OEt)2]3 chains propagating along the c-axis. Their parallel orientation favors the formation of closely packed hexagonal domains. PXRD data suggest that other homologues have a similar structure, with the interchain distance closely corresponding to the dimensions of organic ligands. They are also susceptible to a reversible dissociation to ionic species under the effect of primary amines. This feature can be utilized for the synthesis of epoxy nanocomposites.

Application of PERALS™ alpha spectrometry and gamma spectrometry for analysis and investigation of environmental spills at ISL uranium mining projects.

Radiation protection and environmental monitoring in mining requires effective and reliable radionuclide analysis at all stages of the mine project-prior to mining, during operation and through to remediation and decommissioning. The approach presented in this paper was specially developed for the monitoring of radioactive waste resulting from spills during mining and mineral processing operations and uses a combination of high resolution gamma spectrometry, and PERALS™ alpha spectrometry to identify and reliably quantify the activity of the major members of the U-238 decay chain at activities down to 10 mBq g(-1) by direct radionuclide counting and by assessment of the activity of their decay products. This approach has reduced sample preparation and analysis time while providing effective analysis and quantification of naturally occurring radionuclides in environmental samples. It has been successfully applied to several in situ leach (ISL) mining-related projects involving investigations of process material spill impacts and also to routine environmental monitoring.

Importance of eps genes from Bacillus subtilis in biofilm formation and swarming.

Unicellular organisms naturally form multicellular communities, differentiate into specialized cells, and synchronize their behaviour under certain conditions. Swarming, defined as a movement of a large mass of bacteria on solid surfaces, is recognized as a preliminary step in the formation of biofilms. The main aim of this work was to study the role of a group of genes involved in exopolysaccharide biosynthesis during pellicle formation and swarming in Bacillus subtilis strain 168. To assess the role of particular proteins encoded by the group of epsI-epsO genes that form the eps operon, we constructed a series of insertional mutants. The results obtained showed that mutations in epsJ-epsN, but not in the last gene of the eps operon (epsO), have a severe effect on pellicle formation under all tested conditions. Moreover, the inactivation of 5 out of the 6 genes analysed caused total inhibition of swarming in strain 168 (that does not produce surfactin) on LB medium. Following restoration of the sfp gene (required for production of surfactin, which is essential for swarming of the wild-type bacteria), the sfp+ strains defective in eps genes (except epsO) generated significantly different patterns during swarming on synthetic B medium, as compared to the parental strain 168 sfp+.

Low temperature short-range ordering caused by Mn²(+) doping of Rb3H(SO4)2.

The low temperature behaviour of Rb3H(SO4)2 and Rb3D(SO4)2 and their doped analogues was investigated by means of their dielectric response. Electron paramagnetic resonance was used to control the impurity concentration. Influence of different admixtures on ferroic properties is discussed. It has been shown that an appropriately chosen impurity in doped Rb3H(SO4)2 can lead to a short-range ordering similar to that observed for doped incipient ferroelectric-like SrTiO3 and KTaO3.

Proton dynamics in Rb(3)H(SO(4))(2) doped with Mn(2+) studied by EPR and impedance spectroscopy.

The temperature dependence of the linewidth ΔB(pp) and spin Hamiltonian parameters of Rb(3)H(SO(4))(2) (RHS) crystals were studied by X-band continuous-wave electron paramagnetic resonance. Direction cosines of the zero-field-splitting (ZFS) tensor and the coordination of the Mn(2+) impurities in the crystal lattice were determined in the temperature range 20-450 K. The EPR spectra of crystalline samples and their irreversible changes into pseudo-powder spectra after heating above the superprotonic phase transition temperature were found. Our studies of electric conductivity have shown that, for crystals doped with Mn(2+) ions, the conductivity values increase after heating by about one order of magnitude at intermediate temperatures (below the transition temperature to the superionic phase) in comparison with those of the pure RHS.

Reduction of the spin-orbit splittings at the n = 28 shell closure.

The N = 28 shell closure has been investigated via the 46Ar(d,p)47Ar transfer reaction in inverse kinematics. Energies and spectroscopic factors of the neutron p(3/2), p(1/2), and f(5/2) states in 47Ar were determined and compared to those of the 49Ca isotone. We deduced a reduction of the N = 28 gap by 330(90) keV and spin-orbit weakenings of approximately 10(2) and 45(10)% for the f and p states, respectively. Such large variations for the f and p spin-orbit splittings could be accounted for by the proton-neutron tensor force and by the density dependence of the spin-orbit interaction, respectively. This contrasts with the picture of the spin-orbit interaction as a surface term only.

N=82 shell quenching of the classical r-process "waiting-point" nucleus 130Cd.

First beta- and gamma-spectroscopic decay studies of the N=82 r-process "waiting-point" nuclide 130Cd have been performed at CERN/ISOLDE using the highest achievable isotopic selectivity. Several nuclear-physics surprises have been discovered. The first one is the unanticipatedly high energy of 2.12 MeV for the [pi g(9/2) multiply sign in circle nu g(7/2)] 1(+) level in 130In, which is fed by the main Gamow-Teller transition. The second surprise is the rather high Q(beta) value of 8.34 MeV, which is in agreement only with recent mass models that include the phenomenon of N=82 shell quenching. Possible implications of these new results on the formation of the A approximately 130 r-process abundance peak are presented.

Application of a radiometric method for evaluation of loss of salicylic acid during isolation from biologic material.

A radiometric method for evaluation of loss of salicylic acid in the process of isolation from biologic material is described. According to this study the mean loss during the total process of isolation amounts to 33.59%, the specific values being 19.47% during protein precipitation, 10.68% during extraction, and 3.44% during evaporation of solvent.

Effects of listener uncertainty on articulatory inconsistency.

This investigation determined the effects of listener uncertainty on articulatory inconsistency. Subjects were 15 children between three and five years of age. Each subject was tested to find a set of 45 pictures to which articulatory responses would contain sound errors on: /f,v,th,s,ts,dz/. After one week, articulatory responses to these 45 stimuli elicited by traditional picture naming techniques were compared to productions of the same words elicited in an experimental communication setting. The number of sound errors decreased significantly (p less than or equal to 0.01) in the experimental communication setting when the listener pretended to be uncertain of what the speaker said. This finding was interpreted to mean that listener uncertainty may increase the effectiveness of articulatory remediation procedures if included in treatment programs.