Luminescence properties of Eu2+, Sn2+, and Pb2+ in SrB6O10 and Sr1 − xMnxB6O10

The luminescence properties of Eu²⁺, Sn²⁺, and Pb²⁺ in SrB₆O₁₀ have been studied both at room-temperature and liquid-helium temperature and the decay times of Sn²⁺ and Pb²⁺ in this matrix have been measured and analyzed. According to the emission spectrum of Eu²⁺ there seems to be three different cation sites in SrB₆O₁₀. Europium, tin, and lead were also used as sensitizers for Mn²⁺ and the energy transfer processes were characterized. Eu²⁺-Mn²⁺ energy transfer was inefficient due to the transfer within different Eu²⁺ centers. The sensitization action of Sn²⁺ and Pb²⁺ on Mn²⁺ was different because lead-lead energy transfer occurs (even at 4.2 K) but tin-tin transfer can be neglected. A fast diffusion model for the Pb²⁺ system is suggested.     

Determination of the carboxylic acids in acidic and basic process samples by capillary zone electrophoresis

Capillary zone electrophoresis (CZE) with indirect UV detection was used in developing a method for the simultaneous determination of inorganic anions, aliphatic and heterocyclic organic acids in various processed samples. The analytes were determined simultaneously in 10 min using an electrolyte containing 20 mM 2,3-pyrazine dicarboxylic acid, 65 mM tricine, 2 mM BaCl₂, 0.5 mM cetyltrimethylammonium bromide, and 2 M urea at pH 8.06. Linear plots for the analytes were obtained in the concentration range of 2–150 mg L⁻¹. Relative standard deviations (RSDs) of peak areas during a 3-day analysis period varied from 5.5% for glycolate to 9.5% for oxalate. RSDs of migration times varied between 0.4% and 1.1%. The detection limit (at S/N 3) was 1 mg L⁻¹ for all the analytes studied. The proposed method was successfully demonstrated for the determination of carboxylic acids in eight oxygen treated samples of commercial softwood and hardwood kraft lignin and two red wine samples of Pinot Noir grapes. In the kraft lignin samples the concentrations of carboxylic acids correspond to the oxidation time. The acid concentrations of wine varied considerable.     

New PP/PLA/cellulose composites: effect of cellulose functionalization on accelerated weathering behavior (accelerated weathering behavior of new PP/PLA/cellulose composites)

Polylactic acid (PLA) was used as partial replacement for conventional thermoplastic matrix, new composites comprising cellulose, polypropylene (PP), and PLA being realized. In order to obtain a compatible interface between cellulosic pulp and polymeric matrix, two chemical modifications of cellulose with stearoyl chloride and toluene di‐isocyanate (TDI) were performed, structural changes being evidenced by X‐ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The composite materials were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, dynamic scanning calorimetry, impact, tensile and melt rheological tests, surface tension, and dynamic vapor sorption. Because promising results for impact strength and Young modulus were recorded when replacing 15% of PP with PLA in blends of PP with the same cellulosic pulp load, the aim of our study was to assess the behavior to accelerate weathering of composites comprising PP, cellulosic pulp, and PLA. Although the slight decrease in the mechanical properties was recorded after accelerated weathering, the use of functionalized cellulose successfully prevented the deterioration of surface materials, especially for composite comprising stearoyl chloride treated cellulose pulp. Copyright © 2015 John Wiley & Sons, Ltd.     

Componentwise adaptation for high dimensional MCMC

Summary  We introduce a new adaptive MCMC algorithm, based on the traditional single component Metropolis-Hastings algorithm and on our earlier adaptive Metropolis algorithm (AM). In the new algorithm the adaption is performed component by component. The chain is no more Markovian, but it remains ergodic. The algorithm is demonstrated to work well in varying test cases up to 1000 dimensions.     

The extendible cell method for closest point problems

The extendible cell method is an application of order preserving extendible hashing to multidimensional point files. We derive some of its performance characteristics and show its expected case optimality for closest point problems.     

Two levels are as good as any

The asymptotic expected efficiency of distributive sorting is studied showing that for “smooth” key distributions it suffices to consider 2-level methods. The expected cost of sorting n such keys satisfies asymptotically: C(n) ? Kn, where K does not depend on the distribution.     

Investigation of a Grey Alder Particleboard Bonded by Different Industrial Side-Stream Lignins

Mechanics of Composite Materials - Particleboards based on a mixture of grey alder (Alnus incana (L.) Moench) wood particles (sieve fraction 0.4-2 mm) and 15 or 25% of lignin powder obtained by hot...     

Radioactivity in the Baltic Sea: inventories and temporal trends of <Superscript>137</Superscript>Cs and <Superscript>90</Superscript>Sr in water and sediments

The Baltic Sea is ecologically unique as one of the world’s largest brackish water basins. It was significantly contaminated by radioactivity following the Chernobyl accident in 1986, the major contaminant being long-lived ¹³⁷Cs. Due to the slow exchange of water between the Baltic Sea and the North Sea and the relatively rapid sedimentation rates, radionuclides have prolonged residence times in the Baltic Sea. ¹³⁷Cs levels are consequently still clearly higher than in other water bodies around the world. In addition to the Chernobyl accident, artificial radionuclides in the Baltic Sea originate from the global fallout following nuclear weapons testing in the 1950s and 1960s, while discharges into the Baltic Sea from nuclear power plants and other facilities are of minor importance. Here, inventories and the temporal evolution of radionuclides both in seawater and sediments of the Baltic Sea are presented and discussed.     

Novel applications of the modified polonovski reaction - VII preparation of isoquinuclidines

The first successful preparations of the biochemically important isoquinuclidine ring system by the modified Polonovski reaction are described.