On the unicellularity ofl p (w)

A method of D. V. Yakubovich is sharpened to give extensions of results by him and M. P. Thomas on the right translation-invariant subspace structure for weightedl ^p (Z ⁺) and weightedl ^p (⁺), when the weight tends to 0 at infinity faster than exponentially.     

AGP Propagator calculations

The use of the antisymmetrized geminal power (AGP ) consistent reference state for RPA polarization propagator calculations is explored. Illustrative applications to the three lowest electronic states (³B₁, ¹A₁, and ¹B₁) of the methylene radical are reported with comparisons to other theoretical methods and experiment.     

Study of the reaction products of flavonols with 2,2-diphenyl-1-picrylhydrazyl using liquid chromatography coupled with negative electrospray ionization tandem mass spectrometry

The products obtained after the reaction between flavonols and the stable free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH(*)) in both methanol and acetonitrile were characterized using liquid chromatography coupled with negative electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) and NMR spectroscopy. The flavonols studied were quercetin, kaempferol and myricetin. In methanol, two reaction products of oxidized quercetin were identified using LC/ESI-MS/MS and NMR. Quercetin was oxidized through a transfer of two H-atoms to DPPH(*) and subsequently incorporated either two CH(3)OH molecules or one CH(3)OH- and one H(2)O molecule giving the products 2-(3,4-dihydroxyphenyl)-3,5,7-trihydroxy-2,3-dimethoxy-2,3-dihydrochromen-4-one and 2-(3,4-dihydroxyphenyl)-3,3,5,7-tetrahydroxy-2-methoxy-2,3-dihydrochromen-4-one, respectively. LC/ESI-MS/MS analysis revealed that in methanol, kaempferol and myricetin also gave rise to methoxylated oxidation products similar to that identified for quercetin. Kaempferol, in addition, also exhibited products where a kaempferol radical, obtained by a transfer of one H-atom to DPPH(*), reacted with CH(3)OH through the addition of CH(3)O(*), yielding two isomeric products. When the reaction took place in acetonitrile, LC/ESI-MS/MS analysis showed that both quercetin and myricetin formed stable isomeric quinone products obtained by a transfer of two H-atoms to DPPH(*). In contrast, kaempferol formed two isomeric products where a kaempferol radical reacted with H(2)O through the addition of OH(*), i.e. similar to the reaction of kaempferol radicals with CH(3)OH.     

Efficient isolation of polyaromatic fraction from aliphatic compounds in complex extracts using dimethylformamide-pentane partitionings

A liquid-liquid partitioning method was optimized for the rapid and quantitative separation of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) from aliphatic hydrocarbons in complex primary extracts. This technique was based on the selective extraction of PAHs and PCBs from an aliphatic solvent into dimethylformamide (DMF). Partition experiments demonstrated that the optimal performance was achieved with a DMF (5% H2O)-n-pentane binary system. The optimized application of two consecutive DMF (5% H2O)-n-pentane treatments to extracts from two different polluted sediments facilitated the elimination of alkanes and unresolved complex mixture by more than 94% while the average recoveries of spiked deuterated-PAHs and 13C labeled PCBs ranged from 84 to 94 and 75 to 96%, respectively.     

Kinetic energy functional in hyperspherical coordinates

Hyperspherical coordinates and a generator coordinate representation are employed to find a simple form of the kinetic energy for a general three-particle problem. An expression is developed for the determination of adiabatic hyperangular states in a local potential using the finite element method.     

Studies on the Complexation Behavior of Thorium(IV). 1. Hydrolysis Equilibria

The stability constants of thorium(IV) hydrolysis species have been measured at15, 25, and 35°C (in 1.0 mol dm^–3 NaClO₄) using both potentiometry and solventextraction. The results indicate the presence of the monomeric speciesTh(OH)³⁺, Th(OH)²⁺ ₂, Th(OH)⁺ ₃, and Th(OH)₄, in addition to the polymericspecies Th₄(OH)^{8+ 8} and Th₆(OH)⁹⁺ ₁₅. The polymeric species were found to beimportant, although the total thorium concentration was limited to 0.01–0.1mmol-dm^–3. The solvent extraction measurements required the use of acetylacetone.As such, the stability constants of thorium(IV) with acetylacetone were alsomeasured using both potentiometry and solvent extraction. All logarithms of thestability constants were found to be linear functions of the reciprocal absolutetemperature indicating that H ^o and S^o of reaction are both independent oftemperature (over the temperature range examined in the study).     

Fe2O3–Al2O3 oxygen carrier materials for chemical looping combustion,a redox thermodynamic and thermogravimetric evaluation in the presence of H2S

Journal of Thermal Analysis and Calorimetry - Alumina-supported Fe2O3 oxygen carrier material (OCM) system is among the most promising OCM systems for solid and gaseous fuel CLC. This work utilizes...     

Efficient separation of oxidized cello-oligosaccharides generated by cellulose degrading lytic polysaccharide monooxygenases

We present an evaluation of HPLC-based analytical tools for the simultaneous analysis of native and oxidized cello-oligosaccharides, which are products of enzymatic cellulose degradation. Whereas cello-oligosaccharides arise from cellulose depolymerization by glycoside hydrolases, oxidized cello-oligosaccharides are produced by cellobiose dehydrogenase and the recently identified copper dependent lytic polysaccharide monooxygenases (LPMOs) currently classified as CBM33 and GH61. The latter enzymes are wide-spread and expected to play crucial roles in further development of efficient enzyme technology for biomass conversion. Three HPLC approaches with well documented performance in the field of oligosaccharide analysis have been investigated: high-performance anion-exchange chromatography (HPAEC), hydrophilic interaction chromatography (HILIC) and porous graphitized carbon liquid chromatography (PGC-LC). HPAEC with pulsed amperometric detection (PAD) was superior for analysis of oxidized oligosaccharides, combining the best separation with superior sensitivity for oligosaccharide species with a degree of polymerization (DP) ranging from 1 to 10. Furthermore, the HPAEC method can be optimized for operation in a high-throughput manner (run time 10 min). Both PGC-LC and HILIC allow reasonable run times (41 and 25 min, respectively), with acceptable separation, but suffer from poor sensitivity compared to HPAEC-PAD. On the other hand, PGC-LC and HILIC benefit from being fully compatible with online mass spectrometry. Using an LC–MS setup, these methods will deliver much better sensitivity than what can be obtained with conventional detectors such as ultraviolet-, charged aerosol-, or evaporative light scattering and may reach sensitivities similar to or even better than what is obtained in HPAEC-PAD. Pure oxidized cello-oligosaccharide standards, ranging from DP2 to DP5, were obtained by semi-preparative PGC and characterized by MS and NMR analysis.