Kinetics of formation of fluorescent products from hexanal andl-lysine in a two-phase system

Kinetics of formation of fluorescent condensation products from hexanal andl-lysine (or itsN-acetylated forms) including mass-transfer has been studied in a two-phase system consisting of lysine (or lysine derivative) in a aqueous phosphate buffer and a 1-octanol solution of hexanal as model for formation of fluorophores between protein and carbonyl compounds in peroxidizing biological systems. The initial rate of formation of fluorescent products in the aqueous phase was found to be proportional to the concentration of hexanal and lysine and to increase in both phases with increasing pH in the aqueous phase, in contrast to a higher-order dependence on hexanal in the octanol phase. At pH=6.8, the temperature dependence of the appearance of fluorescent products corresponds to apparent energies of activation of 63 kJ·mol⁻¹ and 87 kj·mol⁻¹ in the aqueous phase and the octanol phase, respectively. Fluorescent condensation products appeared faster in the octanol phase. However, by a kinetic analysis, the fluorescent products were shown to be formed in the aqueous phase, corresponding to the lower energy of activation and to the simple second-order kinetics, and subsequently distributed between the aqueous phase and the octanol phase.l-Lysine reacted faster thanN _α-acetyl-l-lysine which reacted faster thanN _ε-acetyl-l-lysine. Using fluorescence quantum yields, determined to be 1.4·10⁻² in octanol and 8·10⁻³ in water at pH 6.8, an apparent partition coefficient of 17 (octanol/water) was determined for the condensation product ofl-lysine. The steady-state fluorescence in the octanol phase was attributed to two components with fluorescence life-time at 25°C of 0.7±0.05 ns and 5.1±0.2 ns, assigned to hexanal and the condensation product, respectively. The emission spectra, were resolved in the two components using phase-sensitive detection, and the condensation product had emission maximum at 405 nm.     

Mechanism of potassium loss by desorption from an iron oxide catalyst for the styrene process

Several types of experiments have been done with molecular beam and mass spectrometric methods to characterize the desorption processes of potassium from a commercial styrene (potassium promoted iron oxide) catalyst. The loss of potassium as desorption of K is found to be mainly thermal, with an activation energy close to 1.0 eV (97 kJ/mole), which probably is associated with release of K from the initially bound positions in the bulk. The directly measured rate of loss as K appears too small to account for the experimentally observed total rate of loss. A new loss mechanism as electronically excited but not easily field ionizable potassium atoms is detected with an activation barrier of 1.7 eV (164 kJ/mole). Excited states may be important for the total loss both through direct emission of excited K atoms, and since excited states may give rise to cluster formation at the surface and more rapid loss as clusters K_n.     

Walking On Broken Mesh: Defect‐Tolerant Geodesic Distances and Parameterizations

Efficient methods to compute intrinsic distances and geodesic paths have been presented for various types of surface representations, most importantly polygon meshes. These meshes are usually assumed to be well‐structured and manifold. In practice, however, they often contain defects like holes, gaps, degeneracies, non‐manifold configurations – or they might even be just a soup of polygons. The task of repairing these defects is computationally complex and in many cases exhibits various ambiguities demanding tedious manual efforts. We present a computational framework that enables the computation of meaningful approximate intrinsic distances and geodesic paths on raw meshes in a way which is tolerant to such defects. Holes and gaps are bridged up to a user‐specified tolerance threshold such that distances can be computed plausibly even across multiple connected components of inconsistent meshes. Further, we show ways to locally parameterize a surface based on geodesic distance fields, easily facilitating the application of textures and decals on raw meshes. We do all this without explicitly repairing the input, thereby avoiding the costly additional efforts. In order to enable broad applicability we provide details on two implementation variants, one optimized for performance, the other optimized for memory efficiency. Using the presented framework many applications can readily be extended to deal with imperfect meshes. Since we abstract from the input applicability is not even limited to meshes, other representations can be handled as well.     

Costs,CO2- and primary energy balances of forest-fuel recovery systems at different forest productivity

Here we examine the cost, primary energy use, and net carbon emissions associated with removal and use of forest residues for energy, considering different recovery systems, terrain, forwarding distance and forest productivity. We show the potential recovery of forest fuel for Sweden, its costs and net carbon emissions from primary energy use and avoided fossil carbon emissions. The potential annual net recovery of forest fuel is about 66 TWh, which would cost one billion €₂₀₀₅ to recover and would reduce fossil emissions by 6.9 Mt carbon if coal were replaced. Of the forest fuel, 56% is situated in normal terrain with productivity of >30 t dry-matter ha^?1 and of this, 65% has a forwarding distance of <400 m. In normal terrain with >30 t dry-matter ha^?1 the cost increase for the recovery of forest fuel, excluding stumps, is around 4–6% and 8–11% for medium and longer forwarding distances, respectively. The stump and small roundwood systems are less cost-effective at lower forest fuel intensity per area. For systems where loose material is forwarded, less dry-matter per hectare increases costs by 6–7%, while a difficult terrain increases costs by 3–4%. Still, these systems are quite cost-effective. The cost of spreading ash is around 40 €₂₀₀₅ ha^?1, while primary energy use for spreading ash in areas where logging residues, stumps, and small roundwood are recovered is about 0.025% of the recovered bioenergy.     

Development of a Catch-damage-index to assess the quality of cod at landing

Quality and quality management are of increasing concern and importance in all parts of the fishery chain. Fishing gears and handling onboard the vessel have multiple impacts on fish quality, and damages caused during these operations may affect the product quality considerably, resulting in downgrading of the end products. The European fish sector consider measurement of quality defects and other quality factors as important, but methods for systematic evaluation of quality defects caused during catching operations have not been published to any extent.In this work cod caught by different fishing gears commonly used in the Norwegian coastal fisheries were examined for catch-related damages at landing. Other species like saithe and haddock may suffer the same damages, but due to being the economically most important specie in Norway, cod is chosen as model. The severities of the damages are described, and the influence of the damages on the quality of cod products is considered. Based on this, a Catch-damage-index (CDI) scheme is elaborated.     

Antioxidative effects of leaves from Azadirachta species of different provenience

Twenty extracts of leaves from Azadirachta plants (Siamese neem tree of different provenience, neem tree and marrango tree), a traditional medicine, and frequently eaten in large amounts as parts of meals in Thailand, showed proportionality between total phenolics and radical-scavenging as measured, as reduction of Fremy’s salt by ESR-spectroscopy. Scavenging effect of extracts from the neem tree was significantly lower than those of the Siamese neem tree and the marrango tree. The ability of the extracts to trap carbon-centred 1-hydroxyethyl radicals indicates prooxidative activity for a very high concentration of extract. The extracts were found to be efficient scavengers of compounds known to initiate lipid oxidation, as demonstrated by rate constants (25 °C) for reaction with ferrylmyoglobin: k = (1.7 ± 0.3) × 10³ M⁻¹ s⁻¹ at pH 5.5 and k = (7.7 ± 1.4) × 10² M⁻¹ s⁻¹ at pH 7.4, respectively, and with riboflavin triplet-state: k = (1.30 ± 0.02) × 10⁹ M⁻¹ s⁻¹ at pH 7.4. The rate constants for deactivation of ferrylmyoglobin by the extracts were larger than the rate constant for deactivation by the pure phenolic compounds present in the extract, demonstrating synergistic effects. All extracts showed high efficiencies as chain-breaking antioxidants. This was indicated by lowering of oxygen consumption rates in a peroxidising lipid emulsion, suggesting a role as dietary antioxidants. Siamese neem tree leaf extracts were found to interact with α-tocopherol in peroxidising liposomes, resulting in synergistic effects.     

Decomposition Mechanisms in Aluminum Oxide–Apatite Systems

Aluminum oxide was mixed with solid solutions of hydroxyapatite and fluorapatite, prepared by solid-state reactions, for a study of the relation between composites of apatite and of their phase stability in the presence of aluminum oxide. The amount of water released from the apatite was quantified from thermogravimetric measurements, and the fraction of vacancies present at the onset temperature of its decomposition in the presence of aluminum oxide was estimated. The results show that the decomposition takes place when a certain fraction of vacancies has been formed. By incorporation of F⁻ in the structure, the fraction of vacancies was reduced and the thermal stability of apatite was improved. Based on these findings, a modified mechanism describing the thermal decomposition of hydroxyapatite in the aluminum oxide–hydroxyapatite system is formulated.