Eicosapentaenoic acid (20∶5n-3) from the marine microalgaPhaeodactylum tricornutum

Eicosapentaenoic acid (EPA, 20∶5n-3) was obtained from the marine microalgaePhaeodactylum tricornutum by a three-step process: fatty acid extraction by direct saponification of biomass, polyunsaturated fatty acid (PUFA) concentration by formation of urea inclusion compounds, and EPA isolation by semipreparative high-performance liquid chromatography (HPLC). Alternatively, EPA was obtained by a similar two-step process without the PUFA concentration step by the urea method. Direct saponification of biomass was carried out with two solvents that contained KOH for lipid saponification. An increase in yield was obtained because the problems associated with emulsion formation were avoided by separating the biomass from the soap solution before adding hexane for extraction of insaponifiables. The most efficient solvent, ethanol (96%) at 60°C for 1 h, extracted 98.3% of EPA. PUFA were concentrated by the urea method with a urea/fatty acid ratio of 4∶1 at a crystallization temperature of 28°C and by using methanol and ethanol as urea solvents. An EPA concentration ratio of 1.73 (55.2∶31.9) and a recover yield of 78.6% were obtained with methanol as the urea solvent. This PUFA concentrate was used to obtain 93.4% pure EPA by semipreparative HPLC with a reverse-phase, C₁₈, 10 mm i.d.×25-cm column and methanol/water (1% acetic acid), 80∶20 w/w, as the mobile phase. Eighty-five percent of EPA loaded was recovered, and 65.7% of EPA present inP. tricornutum biomass was recovered in highly pure form by this three-step downstream process. Alternatively, 93.6% pure EPA was isolated from the fatty acid extract (without the PUFA concentration step) with 100% EPA recovery yield. This two-step process increases the overall EPA yield to 98.3%, but it is only possible to obtain 20% as much EPA as that obtained by three-step downstream processing.     

Effects of allelochemicals on plant respiration and oxygen isotope fractionation by the alternative oxidase

The goal of this investigation was to determine the effects of allelochemicals on plant respiration that thereby may be responsible for their role in growth inhibition. We have tested the effects of juglone, quercetin, cinnamic acid, and-pinene on respiration rates, and electron partitioning through the cytochrome and alternative respiratory pathways, by measuring on-line oxygen consumption and oxygen isotope fractionation in soybean cotyledon tissue. Cinnamic acid and-pinene decreased the oxygen consumption rate and increased the relative partitioning of electron transport to the alternative pathway. Possible biochemical mechanisms of these effects are discussed.     

Silica Gel- and MCM-41-Supported MoS2 Catalysts for HDS Reactions

MCM-41- and silica gel-supported MoS₂ catalysts were prepared. MCM-41 was synthesized and impregnated with precursor, then activated to obtain the active phase. The sol–gel method was used for providing the SiO₂ support as well as for including the catalyst precursors in one single step of preparation. Such catalysts have applications particularly in hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) processes. A comparison of the activities of the catalysts was made. The catalytic activity results showed the method of preparation used in this study was successful in producing very efficient catalysts for the HDS of dibenzothiophene (DBT).A higher selectivity for direct C–S bond cleavage was observed for the MoS₂ catalyst supported on SiO₂ by the sol–gel method. X-ray diffraction studies showed that the catalysts were poorly crystallized with a very weak intensity of the (002) line of 2H-MoS₂.     

Al ionic radius influence on molecular dynamics simulations ofγ-Al2O3

Molecular dynamics (MD) simulations of-Al₂O₃, using a pairwise additive interaction potential of Pauling's type with four different radii for aluminum atoms, were analysed in order to determine the influence of the radius on the modification of coordination numbers of A1 relative to the ideal structure, at two different temperatures of 300 and 1500 K. It is found that the best choice is the radius of penta-coordinated aluminum, reproducing structural and vibrational properties of the compound in excellent agreement with experimentally observed properties.     

Margarines: A rheological study

Time-dependent flow properties of both commercial and pilot plant-made margarines were characterized under steady shear. Flow curves were fitted to the kinetic expression τ = τ _i +a e ^−k1t +b e ^−k2t . A first-order kinetic model did not describe the observed destruction process of the margarine structure in an adequate manner. In the proposed model, two structures with different destruction rates are postulated. Each structure contributes to a part of the shear stress necessary to deform the margarine sample. The parameters τ _i a andb are temperature-dependent. Decreasing temperatures produce an exponential increase of τ _i , a linear increase ofb and an increase ofa up to a point beyond which it remains constant. A physical interpretation of the model is proposed. The role of the aqueous phase was also studied. Greater hardness was detected at higher water content. Parameter τ _i increased, at any selected temperature, with increasing aqueous phase content of the sample. Parametera increased with decreasing temperatures and higher water content. On the other hand, parameterb was not affected by the amount of aqueous phase. This kinetic model could be employed to perform studies on the influence of different parameters of margarine formulation on its rheologic behavior.     

A new combined computational and NMR-spectroscopical strategy for the identification of additional conformational constraints of the bound ligand in an aprotic solvent

This study documents the feasibility of switching to an aprotic medium in sugar receptor research. The solvent change offers additional insights into mechanistic details of receptor--carbohydrate ligand interactions. If a receptor retained binding capacity in an aprotic medium, solvent-exchangeable protons of the ligand would not undergo transfer and could act as additional sensors, thus improving the level of reliability in conformational analysis. To probe this possibility, we first focused on hevein, the smallest lectin found in nature. The NMR-spectroscopic measurements verified complexation, albeit with progressively reduced affinity by more than 1.5 orders of magnitude, in mixtures of up to 50% dimethyl sulfoxide (DMSO). Since hevein lacks the compact beta-strand arrangement of other sugar receptors, such a structural motif may confer enhanced resistance to solvent exchange. Two settings of solid-phase activity assays proved this assumption for three types of alpha- and/or beta-galactoside-binding proteins, that is, a human immunoglobulin G (IgG) subfraction, the mistletoe lectin, and a member of the galectin family of animal lectins. Computer-assisted calculations and NMR experiments also revealed no conspicuous impact of the solvent on the conformational properties of the tested ligands. To define all possible nuclear Overhauser effect (NOE) contacts in a certain conformation and to predict involvement of exchangeable protons, we established a new screening protocol applicable during a given molecular dynamics (MD) trajectory and calculated population densities of distinct contacts. Experimentally, transferred NOE (tr-NOE) experiments with IgG molecules and the disaccharide Gal'alpha1-3Galbeta1-R in DMSO as solvent disclosed that such an additional crosspeak, that is, Gal'OH2--GalOH4, was even detectable for the bound ligand under conditions in which spin diffusion effects are suppressed. Further measurements with the plant lectin and galectins confirmed line broadening of ligand signals and gave access to characteristic crosspeaks in the aprotic solvent and its mixtures with water. Our combined biochemical, computational, and NMR-spectroscopical strategy is expected to contribute notably to the precise elucidation of the geometry of ligands bound to compactly folded sugar receptors and of the role of water molecules in protein--ligand (carbohydrate) recognition, with relevance to areas beyond the glycosciences.     

A formal representation for context-aware business processes

A business process is a set of activities performed in a coordinated manner within an organizational and technical environment that is aimed toward a business goal. The flexibility of a process is related to an understanding of the unexpected events that occur when people, systems and resources interact and require adjustments. Thus, business processes must be designed to respond to information about different events and their specificity. This information defines what the literature calls “context”. To broaden the perception of context in the case of a business process, this work proposes an approach to characterize the context of a business process activity in a given domain through conceptual models structured in layers. A case study was conducted to evaluate the proposal, which provided evidence of the applicability of the model.     

HumanTop: a multi-object tracking tabletop

In this paper, a computer vision based interactive multi-touch tabletop system called HumanTop is introduced. HumanTop implements a stereo camera vision subsystem which allows not only an accurate fingertip tracking algorithm but also a precise touch-over-the-working surface detection method. Based on a pair of visible spectra cameras, a novel synchronization circuit makes the camera caption and the image projection independent from each other, providing the minimum basis for the development of computer vision analysis based on visible spectrum cameras without any interference coming from the projector. The assembly of both cameras and the synchronization circuit is not only capable of performing an ad-hoc version of a depth camera, but it also introduces the recognition and tracking of textured planar objects, even when contents are projected over them. On the other hand HumanTop supports the tracking of sheets of paper and ID-code markers. This set of features makes the HumanTop a comprehensive, intuitive and versatile augmented tabletop that provides multitouch interaction with projective augmented reality on any flat surface. As an example to exploit all the capabilities of HumanTop, an educational application has been developed using an augmented book as a launcher to different didactic contents. A pilot study in which 28 fifth graders participated is presented. Results about efficiency, usability/satisfaction and motivation are provided. These results suggest that HumanTop is an interesting platform for the development of educational contents.     

Personalized video adaptation framework (PIAF): high-level semantic adaptation

Despite much work on Universal Multimedia Experience (UME), existing video adaptation approaches cannot yet be considered as truly user-centric, mostly due to their poor handling of semantic user preferences. Indeed, these works mainly concentrate on lower-level user preferences but do neither consider any fine-grained object-level adaptation nor evaluate different adaptation options based on predicted user expectations. Moreover, these works do not provide owners with property rights that enable them to place restrictions on the types of modifications to be made to the video content. To address these shortcomings, we propose the Personalized vIdeo Adaptation Framework (PIAF) for high-level semantic video adaptation. PIAF is a fully integrated framework providing all the requirements for a semantic video adaptation. It defines a video annotation model and a user profile model comprising semantic constraints that are delineated in a consistent way, based on the standards MPEG-7 and MPEG-21. At the heart of the framework, the Adaptation Decision Taking Engine (ADTE) computes utility values for different adaptation options, considering each shot separately. The corresponding utility function evaluates the possible choices by evaluating multiple parameters that capture different dimensions of a multimedia experience: amount of modified content, modifications to key objects and shots with respect to the semantic integrity of the original content, expected processing cost of the adaptation, and the anticipated visual and temporal quality of the adapted content. Furthermore, the ADTE can deal with intellectual property issues by selecting an adaptation plan of good quality that also satisfies constraints specified by the content owner. This paper places a significant emphasis on theoretical details of the utility function and the computation of the adaptation plan. It also presents the results and evaluation of the adaptation process both in simulation and user study.     

Enantiospecific synthesis of (R)-1,7-dioxaspiro [5.5]undecane [major component of olive fruit fly (Dacus Oleae) sex pheromone] from d-Fructose

The synthesis of the title compound13 has been carried out through the preparation of its precursor, (3R,4R,5S,6R)-3,4,5-trihydroxy-1,7-dioxaspiro[5.5]undecane (6), obtained fromd-fructose using Wittig's methodology, reduction, and spiroketalation. Compound6 was transformed into13 by a Barton deoxygenation at C-5 followed by a Corey dideoxygenation at C-3,4 of the appropriately protected derivatives.Enantiospecific synthesis of spiroacetals. Part II. For Part I, see Izquierdo and Plaza (1990).