Proton diffusion in polyethylene oxide: Relevance to electrochromic device design

Polyethylene oxide is a frequently used component in polymer electrolytes developed for applications in electrochromic devices. The transmittance variation may occur as a result of either proton or lithium ion intercalation into the electrochromic films. Impedance spectroscopy data in the low-frequency space-charge relaxation regime can be used to obtain estimates of ion concentrations and ion diffusion coefficients in ion-conducting materials. We apply this method to literature data for pure polyethylene oxide where the residual conductivity is believed to be due to protons. The obtained diffusion coefficient is found to be in the order of, or higher than, reported lithium ion diffusion coefficients in low molecular weight polyethylene oxide. Hence it is likely that proton intercalation will be of importance for electrochromic devices, provided there is a significant amount of protons present.     

Species,individual and kin specific blends in Dufour's gland secretions of halictine bees

The compositions of Dufour's gland secretions of four sympatric halictine bee species were chemically studied by combined gas chromatography-mass spectrometry. The secretion is composed of C₁₆-C₂₄ macrocyclic lactones, isopentenyl esters, and hydrocarbons. Comparative analyses have revealed that the blends of compounds are species specific. Studies of individual glands belonging to bees of the speciesEvylaeus malachurum have demonstrated that each bee exhibits a specific blend in its Dufour's gland. Nestmate bees (considered as sister bees), however, are more similar to each other than nonrelated bees. The relative importance of species specificity, individual specificity, and similarities between kins are discussed.     

Preparation of targets for the gas-filled recoil separator TASCA by electrochemical deposition and design of the TASCA target wheel assembly

The Transactinide Separator and Chemistry Apparatus (TASCA) is a recoil separator with maximized transmission designed for performing advanced chemical studies as well as nuclear reaction and structure investigations of the transactinide elements (Z>103) on a one-atom-at-a-time basis. TASCA will provide a very clean transactinide fraction with negligible contamination of lighter elements from nuclear side reactions in the target.For TASCA a new target chamber was designed and built at GSI including the rotating target wheel assembly ARTESIA for beam intensities up to 2 μA (particle). For the production of longer-lived isotopes of neutron-rich heavier actinide and transactinide elements, hot fusion reactions with actinide targets are required. Here, possible target materials range from thorium up to curium or even heavier elements.For the deposition of lanthanide and actinide elements on thin aluminum and titanium backings by means of Molecular Plating (MP), a new deposition cell has been constructed that allows precise temperature control of the organic solvent and stirring of the solution. The electrode geometry ensures homogeneity of the electric field inside the cell. With the new set-up, holmium and gadolinium layers (500 μg/cm²) on 2–5 μm thin titanium backings have been produced with deposition yields of the order of 90%. Systematic investigations are under way to further optimize the deposition conditions for other lanthanide and actinide elements including uranium and plutonium on different backing materials.