Performance of a BGO calorimeter in a tagged photon beam from 260 to 1150 MeV

20 BGO crystals with photomultiplier readout that form one sector of a large solid angle BGO calorimeter, were exposed to an intermediate energy tagged photon beam. Linearity, multiplicity and resolution results are presented and discussed.     

Carbon nanotube superconducting quantum interference device

A superconducting quantum interference device (SQUID) with single-walled carbon nanotube (CNT) Josephson junctions is presented. Quantum confinement in each junction induces a discrete quantum dot (QD) energy level structure, which can be controlled with two lateral electrostatic gates. In addition, a backgate electrode can vary the transparency of the QD barriers, thus permitting change in the hybridization of the QD states with the superconducting contacts. The gates are also used to directly tune the quantum phase interference of the Cooper pairs circulating in the SQUID ring. Optimal modulation of the switching current with magnetic flux is achieved when both QD junctions are in the 'on' or 'off' state. In particular, the SQUID design establishes that these CNT Josephson junctions can be used as gate-controlled pi-junctions; that is, the sign of the current-phase relation across the CNT junctions can be tuned with a gate voltage. The CNT-SQUIDs are sensitive local magnetometers, which are very promising for the study of magnetization reversal of an individual magnetic particle or molecule placed on one of the two CNT Josephson junctions.     

Computer generation of binary Fresnel holography

Binarization of Fresnel holograms by direct thresholding based on the polarity of the fringe pattern is studied. It is found that if the hologram is binarized (i.e., for black and white hologram pixels) in this manner, only the edges of the object are preserved in the reconstructed image. To alleviate the errors caused by binarization, the use of error diffusion has been routinely employed. However, the reconstructed image using such standard technique is heavily contaminated with random noise. In this paper, we propose a novel noniterative method for generating Fresnel holograms that are suitable for binarization. Our method is capable of preserving good visual quality on the reconstructed images.     

La Geologie de l’Ingenieur au site de la gare souterraine Saint-Georges,a Liege (Belgique)

Resume Au site de la gare souterraine Saint-Georges du future métro de Liège, les études géologiques, hydrogéologiques et géotechniques ont été réalisées conjointement avant l’établissement de l’avant-projet. Elles ont permis de déterminer la constitution détaillée de la plaine alluviale et du bed rock, l’hydrogéologie dans les alluvions et le terrain houiller, les propriétés géomécaniques des roches présentes et leur modification dans les massifs saturés en eau. La confrontation de toutes les données recueillies permet non seulement d’établir de meilleures corrélations entre les divers phénomènes examinés: nature, structure, texture des roches, allure et comportement des nappes aquifères, qualité des matériaux, … mais encore, par la synthèse, de fournir aux ingénieurs de projet une somme intéressante de renseignements quantitatifs propres au site investigué et à l’ensemble des conditions qui y règnent.

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At the site of the underground station of the intended Metro of Liège the geological, hydrogeological and geotechnical investigations have been carried out jointly before the realization of the preliminary plan. They have enabled to determine the detailed geological constitution of the alluvial plain and of the bed-rock, the hydrogeology in the alluvial deposits and in the coal measures, the geomechanical properties of the rocks and their modifications in the massives saturated with water. The comparison of all the data gathered enables not only to obtain better correlations between the different phenomena investigated as nature, structure, texture of the rocks, aspect and behaviour of the underground water levels, quality of the materials, and so on, but also, through the synthesis, to supply the engineers of the plan with a useful amount of quantitative information which is peculiar to the site investigated and to the whole of the conditions existing in it.

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Ingénieur civil des mines et ingénieur géologue — Professeur à l’Université de Liège.

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Ingénieur civil des mines et ingénieur géologue — Premier assistant à l’Université de Liège.

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Ingénieur civil des constructions — Assistant à l’Université de Liège

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Ingénieur géologue.     

A very promising new glucolipidic surfactant: Lipowheat

Lipowheat is an entirely biodegradable 100% natural active ingredient, extracted from non-transgenic wheat. Thanks to its very interesting properties, it can integrate the composition of most cosmetic and pharmaceutical products. The aim of this work was first to realize a large range of stable simple or multiple emulsions, in order to determine and evaluate the ability of a new glucolipidic surfactant Lipowheat to form and stabilize emulsions. The rheological properties of these emulsions were tested during a 30-day storage period at three different storage conditions (cold, room temperature and at 40 degrees C). In addition to dynamic and static rheological tests, droplet size distribution of the cream was also determined. Furthermore, a stable simple emulsion was selected to realize percutaneous absorption and evaluate the properties of Lipowheat.     

The anoxic extractive membrane bioreactor

The extractive membrane bioreactor (EMB) employs a dense silicone rubber membrane to selectively extract hydrophobic organic compounds from industrial wastewaters into a bioreactor in order to biodegrade them. The major drawback of the EMB is excess biofilm growth on the membrane, which limits mass transfer and creates oxygen limitations. In this work, nitrate has been used as an electron acceptor instead of oxygen. Due to the high solubility of nitrate in water, it is hypothesised that nitrate penetrates the whole biofilm, preventing the formation of inactive zones of bacteria. Four experiments have been performed with toluene as a model substrate under anoxic conditions. The effect of nitrate concentrations on the biofilm and on the toluene flux have been investigated. In addition, the production of soluble microbial products (SMPs), and bacterial hydrophobicity were studied.Under high nitrate concentrations, the performance of the anoxic EMB was stable and no biofilm was formed. The bacteria metabolised toluene, and the toluene flux remained approximately constant. Conversely, at low nitrate concentration, a decrease in pollutant flux concomitant with biofilm growth was observed. The production of SMPs increased under limiting nitrate concentrations, but the hydrophobicity of the suspended bacteria remained constant. However, the bacterial hydrophobicity of the attached cells was significantly greater than that of the suspended cells.     

Acute effects of Aspergillus versicolor aerosols on murine airways

Mice were exposed to aerosols from Aspergillus versicolor extract by inhalation (for 15-20 min). Changes in respiratory function parameters were monitored during the exposure to evaluate acute effects on the upper and lower respiratory tracts and the conductive airways. The single inhalation exposure to A. versicolor aerosols at the range of 12-151 mg/m3 provoked upper respiratory tract irritation in the airways of mice. The higher the exposure concentration the higher was the increase in the sensory irritation (SI) response. No bronchoconstriction or pulmonary irritation was observed. The causative agents for the SI response in the fungal extract are not known.     

A study of grease film thicknesses in elastorheodynamic rolling point contacts

An elastorheodynamic analysis and a numercial solution are presented for grease film thicknesses in rolling point contacts for fully flooded, isothermal and steady state conditions. The contact surfaces are smooth and a grease four-parameter rheological model is considered. A modified Reynolds equation is established and a complete numerical solution, including surface deformations, piezoviscous, and compressional effects is given.     

Characterisation of pectins extracted from banana peels (Musa AAA) under different conditions using an experimental design

An experimental design was used to study the influence of pH (1.5 and 2.0), temperature (80 and 90 °C) and time (1 and 4 h) on extraction of pectin from banana peels (Musa AAA). Yield of extracted pectins, their composition (neutral sugars, galacturonic acid, and degree of esterification) and some macromolecular characteristics (average molecular weight, intrinsic viscosity) were determined. It was found that extraction pH was the most important parameter influencing yield and pectin chemical composition. Lower pH values negatively affected the galacturonic acid content of pectin, but increased the pectin yield. The values of degree of methylation decreased significantly with increasing temperature and time of extraction. The average molecular weight ranged widely from 87 to 248 kDa and was mainly influenced by pH and extraction time.     

Comparative Study on the Starch Noodle Structure of Sweet Potato and Mung Bean

ABSTRACT:  Fine structure of sweet potato starch (SPS) and mung bean starch (MBS) by gel-permeation chromatography (GPC) showed that the amylose in SPS and MBS had 9.0 and 1.8 chains, respectively. The long chains of amylopectin in MBS (A_p-MB) were longer than those of amylopectin in SPS (A_p-SP), but the short chains of A_p-SP were shorter than those of A_p-MB. The structures of starch noodles of sweet potato (SPSN) and mung bean (MBSN) were analyzed by GPC, scanning electron micrograph (SEM), differential scanning calorimetry (DSC), and X-ray diffraction after hydrolysis by acid and enzymes. The results showed that the residues obtained with acid and enzymes in MBSN contained large amounts of high molecular weight fractions, and a relatively small amount of low molecular weight fractions, whereas those in SPSN contained some high molecular weight fractions and large amounts of low molecular weight fractions. SPSN exhibited higher digestibility by HCl, α-amylase, β-amylase, and pullulanase than MBSN. The surface of MBSN was more smooth than that of SPSN and the inside of MBSN contained long, thick, and orderly filaments, while there were many pore spaces inside SPSN from SEM. The DSC thermogram of the resistant residues from both starch noodles after acid/enzyme hydrolysis showed a broad endotherm peak near 100 °C (96 to 115 °C) due to the presence of the complexes of amylose-lipid and lipid-(long chains in amylopectin). Because of a lower content of branched amylose and a higher content of amylopectin in SPS, the structure of SPSN had a less distinct crystalline pattern and higher adhesiveness, whereas there was a higher content of amylose with a little branch and moderate amylopectin in MBS. Thus, the structure of MBSN had a stronger distinct crystalline pattern and good cohesiveness.