Dicyanmethanido- und Cyanamido-oxoanionen. Untersuchungen zum sauerstoffanalogen Charakter der C(CN)2- und NCN-Gruppen

The equivalence of the C(CN)₂- and the NCN-groups with oxygen in the series of homologous ions C(CN), N(CN), OCN^? and NOC(CN), NO causes us to postulate a more general value of this relation. Arguments for the formulation of a pseudochalkogen series C(CN)₂? NCN? O are discussed. Synthesis, structure and reactivity of some dicyanmethanido- and cyanamido-oxoanions RCOY^?, CO₂Y^2?, COY, NOY^?, NO₂Y^?, PO₃Y^3?, PO₂Y and SO₂Y^2? are described. (Y ? C(CN)₂, NCN.) The preparation of some triorganoleadacyles is reported.     

Excitation wavelength-dependent electron-phonon and electron-vibrational coupling in the CP29 antenna complex of green plants

Electron-phonon and electron-vibrational coupling strengths of a weakly (excitonically) coupled chlorophyll a S1-->S0 transition of the CP29 antenna complex of plant photosystem II were studied by difference fluorescence-line-narrowing spectroscopy at 4.5 K. A strong, almost linear increase of the electron-phonon coupling strength toward longer wavelengths was observed, with Huang-Rhys factors Sph increasing from 0.41+/-0.05 at 680 nm to about 0.66+/-0.07 at 688 nm. The former and latter wavelengths are located close to the peak and on the red edge of the inhomogeneous site distribution function, respectively. The experimentally obtained wavelength dependence of Sph may originate either from an alteration of the electron-phonon coupling strength by the local environment of the fluorescing chromophore and/or from the presence of two isoforms of CP29, which are characterized by different coupling strengths to the protein environment. The one-phonon profile peaks at omegam=22 cm(-1) and is described by an asymmetric function composed of a Gaussian low-energy wing and a Lorentzian high-energy tail with half-widths at half-maximum of 10+/-1 and 60+/-10 cm(-1), respectively. Thirty-nine individual vibrational modes between 90 and 1665 cm(-1) were resolved, and their Huang-Rhys factors were determined, which fall in the range between 0.0004 and 0.032. The broad feature present in the overlap region of phonon and vibrational modes at about 90 cm(-1) is characterized by S=0.048. An integral value of vibrational coupling strengths Svib=0.36+/-0.05 was determined, which is similar to that observed earlier for the trimeric LHC II complex.     

Insights and decision support for home health care services in times of disasters

Central European Journal of Operations Research - Home health care (HHC) services are of vital importance for the health care system of many countries. Further increases in their demand must be...     

Comparison of different technologies for alginate beads production

This paper describes the results of the round robin experiment “Bead production technologies” carried out during the COST 840 action “Bioencapsulation Innovation and Technologies” within the 5th Framework Program of the European Community. In this round robin experiment, calcium alginate hydrogel beads with the diameter of (800 ± 100) μm were produced by the most common bead production technologies using 0.5–4 mass % sodium alginate solutions as starting material. Dynamic viscosity of the alginate solutions ranged from less than 50 mPa s up to more than 10000 mPa s. With the coaxial air-flow and electrostatic enhanced dropping technologies as well as with the JetCutter technology in the soft-landing mode, beads were produced from all alginate solutions, whereas the vibration technology was not capable to process the high-viscosity 3 % and 4 % alginate solutions. Spherical beads were generated by the electrostatic and the JetCutter technologies. Slightly deformed beads were obtained from high-viscosity alginate solutions using the coaxial airflow and from the 0.5 % and 2 % alginate solutions using the vibration technology. The rate of bead production using the JetCutter was about 10 times higher than with the vibration technology and more than 10000 times higher than with the coaxial air-flow and electrostatic technology. In memory of our colleague Stefan Rosinski     

Effect of doping, microstructure, and CO2 on La2NiO4+δ-based oxygen-transporting materials

Alkaline earth-free La₂NiO_4+δ based materials were synthesized by a sol-gel method and studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques as well as oxygen permeation experiments. Effects of doping the nickel position with a variety of cations (Al, Co, Cu, Fe, Mg, Ta, and Zr) were investigated with regards to oxygen flux and microstructure. Doping was always found to diminish the oxygen flux as compared to the reference composition. However, larger grains, which were achieved by longer annealing times at 1723 K have a minor negative impact on oxygen permeation flux in case of La₂NiO_4+δ and La₂Ni_0.9Fe_0.1O_4+δ system. Mössbauer spectroscopy shows that the iron-doped system exhibits a secondary phase, which was identified by high-resolution transmission electron microscopy (HRTEM) as a higher Ruddlesden-Popper phase. In-situ XRD in an atmosphere containing 50 vol% CO₂ and long-term oxygen permeation experiments using pure CO₂ as the sweep gas revealed a high tolerance of the materials towards CO₂.     

Measurements of intrinsic ion Bernstein waves in a tokamak by collective Thomson scattering

In this Letter we report measurements of collective Thomson scattering (CTS) spectra with clear signatures of ion Bernstein waves and ion cyclotron motion in tokamak plasmas. The measured spectra are in accordance with theoretical predictions and show clear sensitivity to variation in the density ratio of the main ion species in the plasma. Measurements with this novel diagnostic demonstrate that CTS can be used as a fuel ion ratio diagnostic in burning fusion plasma devices.     

Kinetics of cation distribution in non-stoichiometric nickel gallate spinel

Cations in the spinel structure are distributed over sites of tetrahedral and octahedral coordination. The cation distribution and its kinetics in non-stoichiometric nickel gallate spinel were studied by high-temperature optical spectroscopy combined with the temperature-jump relaxation technique. It is found that up to 1200 °C the optical absorption spectra of the spinel are dominated by ligand field transitions of Ni²⁺ ions on octahedral sites. The kinetics of cation site-exchange were investigated from 850 to 1100 °C by monitoring the temporal evolution of the absorbance due to Ni²⁺ ions in octahedral sites after sudden changes in temperature. The temperature dependence of cation kinetics shows two regimes, one below and one above about 950 °C with activation energies of about 230 kJ/mol and 60 kJ/mol, respectively. Due to sample preparation, the low-temperature activation energy corresponds to an extrinsic vacancy migration regime. The activation energy of kinetics in the upper temperature regime is discussed in connection with the increasing reactivity of the optical absorber at high temperatures.     

Interfacial Ferromagnetism in a Co/CdTe Ferromagnet/Semiconductor Quantum Well Hybrid Structure

The magnetization properties of a ferromagnet-semiconductor Co/CdMgTe/CdTe quantum well hybrid structure are investigated by several techniques. Exploiting the proximity effect between acceptor bound holes and magnetic ions we detect the magnetization curves by measuring the circular polarization of photoluminescence in an out-of-plane magnetic field. We show that magnetization originates from interfacial ferromagnet on Co-CdMgTe interface and the proximity effect is caused by magnetization of interfacial Co-CdMgTe ferromagnetic layer whose magnetic properties are very different from Co.     

Pulse Radiolytic Studies of 1-Halo-2-(methylthio)ethanes in Hexane and 1,2-Dichloroethane: Formation of an Intermolecular Species with a Three-Electron Bond between Sulfur and Iodine

1-Iodo-2-(methylthio)ethane was synthesized via a ring-opening reaction of thiirane with MeI in MeCN. The S-centered radical cation of this compound undergoes an intermolecular stabilization with the I substituent of a second unattacked substrate molecule to yield an bonded radical cation. The oxidation was initiated by solvent radical cations in irradiated 1,2-dicloroethane and hexane solutions. The 2ρ/ρ* three-electron-bonded species exhibits an optical absorption band at 410 nm, detectable by pulse radiolysis. During its decay, a new, longer-lived absorption band is formed at 380 nm which is assigned to . The latter is suggested to result from anchimeric assistance in the generation of a cyclic sulfonium salt. The radical cations of 1-bromo-and 1-chloro-2-(methylthio)ethane are assumed to undergo raped cyclization to the sulfonium salt without stabilization in any intermolecular S-Br or S-Cl interaction.