Chromatographic separation of americium from europium using bis-2,6-(5,6,7,8-tetrahydro-5,9,9-trimethyl-5,8-methano-1,2,4-benzotriazin-3-yl) pyridine

The separation of americium(III) from europium(III) was achieved utilizing a bis-2,6-(5,6,7,8-tetrahydro-5,9,9-trimethyl-5,8-methano-1,2,4-benzotriazin-3-yl) pyridine (CA-BTP) chromatographic resin. The extraction chromatographic materials were prepared using various concentrations of CA-BTP. This new, hydrolytically stable extractant was impregnated on an inert polymeric support at 40% loading. The uptake of Am(III) and Eu(III) by this material from 0.1 to 4.0 M aqueous HNO₃ solutions was measured. The resulting dry weight distribution ratios, D _w , indicated a strong preference for Am(III) with little affinity for Eu(III). These results are similar to recently reported solvent extraction studies indicating a maximum uptake of Am(III) in the 0.5–1.0 M HNO₃ range. The resin preparation, performance, and characterization of the Am/Eu separation are reported herein.

     

In situ measurements of the spectral emittance of coal ash deposits

The spectral emittance of deposits left by bituminous and sub-bituminous coals under oxidizing conditions have been measured in situ. Pulverized coal is injected into a down-fired entrained-flow reactor. Ash accumulates on a probe in the reactor effluent and radiation emitted by the ash layer is recorded using a Fourier transform infrared (FTIR) spectrometer. Values for the spectral emissive power emitted by the ash and the surface temperature of the ash are extracted from these data. These results are then used to calculate the spectral emittance of the deposit. The spectral emittances of ash deposits formed by burning Illinois #6 (bituminous) coal and Powder River Basin (sub-bituminous) coal were measured between 3000 and 500 wavenumbers. The spectral emittance of the deposit left by the bituminous coal has a constant value of approximately 0.46 between 3000 and 2400 wavenumbers. Between 2200 and 1200 wavenumbers, the spectral emittance of the deposit increases from approximately 0.47 to approximately 0.61. Between 1200 and 500 wavenumbers, the spectral emittance is relatively constant at 0.61. The spectral emittance of the deposit left by the sub-bituminous coal is also relatively constant between 3000 and 2400 wavenumbers at a value of 0.29. Between 2200 and 500 wavenumbers, the spectral emittance of deposits from the sub-bituminous coal increases from approximately 0.29 to 0.55. Differences between these spectral emittance measurements and those measured ex situ illustrate the importance of making in situ measurements. Band emittances were calculated using the measured spectral emittances, and band emittances of the deposits are reported as functions of temperature.     

Self-avoiding Walks and Polymer Adsorption: Low Temperature Behaviour

We give a brief review of the self-avoiding walk model of polymer adsorption highlighting some open problems in the area. We then discuss the low temperature behaviour and derive some results about the behaviour of the free energy at low temperatures.     

C(α) preserving operators on separable Banach spaces

Let T be a bounded linear operator from a separable Banach space X to a Banach space Y. A necessary and sufficient condition on T for the existence of a subspace Z of X such that Z is isomorphic to C(α) and the restriction of T to Z is an isomorphism is given. The special case where X is the disc algebra is then considered and results similar to those previously obtained by the author for C(K) spaces are obtained for the disc algebra. Finally some additional results of the same type are proved for subspaces of C(K) with small annihilator.     

Poly­[lead(II)‐μ2‐aqua‐μ4‐tereph­thalato]

The title compound, [Pb(C₈H₄O₄)(H₂O)]_n, forms as an insoluble product in the reaction of sodium terephthalate(2−) with Pb(NO₃)₂ in water. Analysis has shown that the crystal structure is centrosymmetric, with the asymmetric unit containing one formula unit. The lead geometry is hemidirected seven‐coordinate, with both monodentate and bidentate carboxyl­ate coordination modes present. The combination of hydrogen bonds and coordination bonds produces a three‐dimensional structure, including the first example, in a lead complex, of the common metal‐coordinated carboxyl­ate/water (6) graph‐set motif.     

Enzymatic hydrolysis of ammonia-treated sugar beet pulp

Sugar beet pulp is a carbohydrate-rich coproduct generated by the table sugar industry. Beet pulp has shown promise as a feedstock for ethanol production using enzymesto hydroly zepolymeric carbohydrates and engineered bacteria to ferment sugars to ethanol. In this study, sugar beet pulp underwent an ammonia pressurization depressurization (APD) pretreatment in which the pulp was exploded by the sudden evaporation of ammonia in a reactor vessel. APD was found to substantially increase hydrolysis efficiency of the cellulose component, but when hemicellulose- and pectindegrading enzymes wereadded, treated pulp hydrolysis was no better than the untreated control.     

Soy-oil-based segmented polyurethanes

Segmented polyurethanes were prepared from soy polyol, diphenyl methane diisocyanate (MDI), and ethylene glycol or butane diol as chain extenders. Samples were prepared with true hard-segment concentrations (HSC) of about 0, 10, and 40%. Both the soft MDI–polyol and hard MDI/diol segments are glassy at room temperature. These samples were also crosslinked through the polyfunctional polyol soft segment. Partial crystallinity and phase separation were detected in samples with 40% HSC, on the basis of DSC data. Small-angle X-ray scattering shows the existence of phase separation with domain sizes of about 10 nm in the 40% HSC samples, but not in the others. The distribution of domain sizes is considerably broader for the ethylene-glycol extended system compared with that for the butane-diol case. Although the presence of hard segments lowers the crosslink density, samples with higher HSC had higher glass transition temperatures, higher strengths, higher moduli, lower swelling, lower elongation at break, and lower impact strengths. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 3178–3190, 2005     

Preparation and characterization of some unusually transparent poly(dimethylsiloxane) nanocomposites

A technique was developed for preparing poly(dimethylsiloxane) nanocomposites having unusually high transparencies as quantitatively judged by ultraviolet–visible spectroscopy. The method was the in situ generation of silica particles by a two‐step sol–gel procedure in which the required water of hydrolysis was simply absorbed from the air, and the catalyst was generated in situ from a tin salt. Electron microscopy showed that the phase‐separated silica domains were very small (30–50 nm in diameter) and well dispersed, as expected from the transparency of the composites. Stress‐strain measurements in tension indicated that the particles provide very good reinforcement. Ultra‐small‐angle X‐ray scattering data showed that the domain morphology depends strongly on catalyst, but weakly on loading level. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1897–1901, 2003     

A study of the oxidation of europium(II) sulphide by europium-151 Mössbauer spectroscopy

The oxidation of solid europium(II) sulphide under mild conditions has been examined by¹⁵¹Eu Mössbauer spectroscopy. The results show that europium(II) sulphide is remarkably stable to oxidation at 25°C and is only partially converted to Eu³⁺ after exposure to air for four days. Treatment in air at a temperature of 250°C for six hours induces a similar degree of oxidation. The mechanism and kinetics of oxidation of curopium(II) sulphide under mild conditions in the solid state are therefore non-trivial matters.     

Quantitative analysis of the mono- and sesquiterpenoids of douglas-fir sapwood by solvent extraction and gas chromatography with mass selective detection

In order to investigate the relationship between terpenoid content and black bear foraging preference, an analytical method was required to quantify mono- and sesquiterpenoids present in Douglas-fir sapwood. Sapwood samples were scraped from trees, immediately frozen in liquid nitrogen, and then homogenized. A simple extraction requiring no clean-up step was performed with ethyl acetate. Extracts were analyzed by gas chromatography with mass selective detection versus external standards. The recoveries of 22 terpenoids from fortified controls were approximately 90% with good precision (relative standard deviations of approximately 10%).