Quantification of rotenone in seeds of different species of yam bean (Pachyrhizus sp.) by a SPE HPLC-UV method

This study describes the development of a validated method for the quantification of rotenone in yam bean. The milled seeds were submitted to a Soxhlet dichloromethane extraction which allowed extracting 90% of the seeds rotenone. Elimination of the lipids was obtained via solid phase extraction. Rotenone was eluted with dichloromethane/methanol and the solution dried under vacuum and solubilised directly in methanol before injection in HPLC. The whole process was realised as much as possible protected from light and at temperatures lower than 40 °C which allowed high recovery rates of spiked rotenone. Total error was used as criterion for the validation process and accuracy profiles drawn. The method allows the quantification of rotenone in yam bean seeds from 0.07% up to 1.25% (w/w). This method was applied to the quantification of rotenone in the seeds of several accessions of Pachyrhizus erosus and Pachyrhizus ahipa. The results range from 1.13 to 2.76 mg/g dry material.     

A new Lagrangian decomposition approach applied to the integration of refinery planning and crude-oil scheduling

The aim of this paper is to introduce a methodology to solve a large-scale mixed-integer nonlinear program (MINLP) integrating the two main optimization problems appearing in the oil refining industry: refinery planning and crude-oil operations scheduling. The proposed approach consists of using Lagrangian decomposition to efficiently integrate both problems. The main advantage of this technique is to solve each problem separately. A new hybrid dual problem is introduced to update the Lagrange multipliers. It uses the classical concepts of cutting planes, subgradient, and boxstep. The proposed approach is compared to a basic sequential approach and to standard MINLP solvers. The results obtained on a case study and a larger refinery problem show that the new Lagrangian decomposition algorithm is more robust than the other approaches and produces better solutions in reasonable times.     

Sporopollenin exines: A novel natural taste masking material

Sporopollenin exines extracted from the spores of the plant Lycopodium clavatum were used to encapsulate water, sunflower oil (0.5 g/g) and differing amounts of cod liver oil (cod liver oil per gram of sporopollenin exines: 0.5 g/g, 1.0 g/g, 2.0 g/g, 4.0 g/g). A double-blind taste trial, involving 20 volunteers, was conducted to compare the products. The encapsulated oils were in the form of a fine powder up to an oil loading of 1/1 (w/w). Blind tasting could not distinguish the cod liver oil preparation up to 1/1 (w/w) loading compared to the sporopollenin exines filled with either water or sunflower oil. At a loading of 2/1 and 4/1, the cod liver oil was uniformly identified. Therefore, sporopollenin exines can be loaded highly, at up to 1 g oil to 1 g of the exines, and still remain as a dry powder and retain flavor masking, thus disguising the contents.     

Apodized fiber Bragg gratings manufactured with the phase plate process

We present a manufacturing method based on the dynamic use of phase plates to photowrite Bragg gratings. This process allows for control of the local value of the index modulation envelope in the grating. The application to apodized fiber Bragg gratings is discussed.     

A Surface Reconstruction Method Using Global Graph Cut Optimization

Surface reconstruction from multiple calibrated images has been mainly approached using local methods, either as a continuous optimization problem driven by level sets, or by discrete volumetric methods such as space carving. We propose a direct surface reconstruction approach which starts from a continuous geometric functional that is minimized up to a discretization by a global graph-cut algorithm operating on a 3D embedded graph. The method is related to the stereo disparity computation based on graph-cut formulation, but fundamentally different in two aspects. First, existing stereo disparity methods are only interested in obtaining layers of constant disparity, while we focus on high resolution surface geometry. Second, most of the existing graph-cut algorithms only reach approximate solutions, while we guarantee a global minimum. The whole procedure is consistently incorporated into a voxel representation that handles both occlusions and discontinuities. We demonstrate our algorithm on real sequences, yielding remarkably detailed surface geometry up to 1/10th of a pixel. Author has worked on this project during his Ph. D. at ARTIS     

Expressiveness of Probabilistic π-calculus

In this work we propose a probabilistic extension of the π-calculus. The main novelty is a probabilistic mixed choice operator, that is, a choice construct with a probability distribution on the branches, and where input and output actions can both occur as guards. We develop the operational semantics of this calculus, and then we investigate its expressiveness. In particular, we compare it with the sublanguage with the two separate choices, where input and output guards are not allowed together in the same choice construct. Our main result is that the separate choices can encode the mixed one. Further, we show that input-guarded choice can encode output-guarded choice and viceversa. In contrast, we conjecture that neither of them can encode the pair of the two separate choices.     

Effect of yttrium on the performances of zirconia based catalysts for the decomposition of N2O at high temperature

Abatement processes for the reduction of N₂O emissions from acid nitric plants can be implemented in different positions. Among the different possibilities, a catalytic process set up between the ammonia converter and the absorber could be a practicable solution. In those running conditions, at high temperature, in the presence of NO, O₂ and water, the catalytic decomposition of N₂O (in the absence of a reducing agent) can take place. However, catalysts usually suffer from a strong deactivation owing to the occurrence of thermal sintering which significantly lowers their specific surface area. Catalytic testing performed at laboratory scale showed that zirconia based catalysts stabilised by yttrium incorporation could be of potential interest. However, the mode of yttrium incorporation seems to be a key factor. According to the preparation procedure, surface yttrium enrichment may occur and then strongly inhibit the catalytic decomposition of N₂O. Co-precipitation methods can be profitably used for the preparation of modified-ZrO₂ catalysts in order to obtain yttrium homogeneously distributed in the bulk material. According to this preparation method, a synergy effect on the catalytic activity and also on the stability has been observed on ZrO₂ containing low amount of yttrium whereas an inhibiting effect prevails on highly loaded yttrium based catalysts irrespective of the mode of yttrium incorporation.     

Molecular Orientational Ordering in Solid C60

Single-crystal X-ray diffraction studies of the orientational ordering in solid C₆₀ are reviewed. The temperature dependence of selected Bragg reflections was carefully examined, allowing to obtain original information on the first-order orientational ordering transition at T_o = 259K, the unusual behavior of both fundamental and superstructure reflections below T_o and the freezing in of the C₆₀ reorientations at T_g ≈ 85K. The diffuse intensity due to orientational disorder of the C₆₀ molecules at room temperature is found to be strongly modulated, both radially and azimuthally. showing that the molecular orientations are indeed correlated. The corresponding intensity distribution has been calculated within a mean-field theory for different microscopic models of inter molecular interactions. It should allow a better understanding of these interactions.