Luminous Activity Study of a Long Atmospheric Pressure DBD Afterglow

The experimental work reported here is devoted to the study of the luminous activity of a long dielectric barrier discharge （DBD） afterglow at atmospheric pressure. The discharge plasma is generated in a commercially available （AcXys Technologies） reactor, using a N2 flow of a few tens SL/min, whereas the luminous afterglow when channelled into a quartz tube extends at a distance of 50 cm, finishing in a luminous arrow at the tube＇s exit. The luminous activity of the afterglow is studied by means of photomultiplier scans and optical emission spectroscopy, revealing an interesting transient phase. An attempt is made to correlate this effect with the active species＇ creation and destruction mechanisms.     

Elaboration d'une carte d'occupation du sol du bassin versa lilt de la Leysse a partir d'images HRV de SPOT

Dans le cadre de travaux, menés au sein Laboratoire de Chimie et lngénierie de l'Environnemcnt de l'Universite de Savoie, sur Ie suivi de la qualite des eaux superficielles du bassin versant de la Leysse, une carte d'occupations du sol est rélisée á partir d'images satellites de HRV de SPOT. Deux images ont été utilisées, une multibande (XS) et une panchromatique (P). Par la superposition de ces deux images, l'images (P + XS) de resolution 10m est créée, Deux méthodes de classification automatique (maximum de vraisemblance et hypercubes généralisés) sont testees sur les images (XS) et (P + S). La methode par hypercubes généralisés classe plus de surface que la méthode par maximum de vraisemblance. Sur I'image (P + XS) dix huit themes sont identifies, contre treize pour (XS). Aprés vérification sur Ie terrain, la carte issue de l'imagc (P + XS) est la plus representative de la realité.     

THE EFFECTS OF β-METHYLGLUCOSE, 3-0-METHYLGLUCOSE and THIOGLUCOSE ON AFLATOXIN PRODUCTION BY ASPERGILLUS PARASTICUS

Earlier work characterizing the effects of glucose analogs on growth and aflatoxin production by Aspergillus parasiticus was expanded by assessing the effects of β-methylglucose (βMG), 3-0-methylglucose (3MG) and thioglucose (TG). As sole carbon source of conidia-initiated cultures, βMG and 3MG, but not TG, supported growth, but none supported toxin production. In glucose-containing replacement cultures, MG appeared to stimulate toxin production, while TG was inhibitory and 3MG had no effect. Preliminary assessment of the effects of βMG, 3MG, TG, 2-deoxyglucose and α-methylglucose on glucose uptake and utilization by glucose-containing replacement cultures indicated that under conditions that favor aflatoxin production, none of the analogs inhibited the uptake of ¹⁴C-labelled glucose. It appears that the glucose transport system(s) of A. parasiticus may be unusual in that it is insensitive to a variety of glucose analogs.     

Titanium Alloy Surface Modification by a Spatio-Temporal Atmospheric Pressure DBD Afterglow

The experimental work reported here is devoted to the study of the modifications inflicted on the surface of titanium alloy specimens by an atmospheric pressure dielectric barrier discharge（DBD） reactor in both spatial and temporal afterglow conditions. A commercially available （AcXys Technologies） modified reactor system was used for the surface treatment of the TiA6V4 titanium alloy that is widely used in the aeronautical industry. Wettability surface characterisation and XPS analyses are performed to give a macroscopic and microscopic insight to the surface modifications. Best operating conditions, at constant input energy, were obtained for a duty cycle equal to 10%.     

ANALYSIS OF MULTIPLE PARTICLE TRAJECTORIES AND DEPOSITION LAYER GROWTH IN POROUS CONDUITS

In the present paper a rather general method is outlined for the prediction of particle deposition on porous surfaces. In the numerical analysis a continuous dilute stream of small spherical particles subject to a laminar flow field in a porous-walled conduit has been considered. The coupled simultaneous interactions between particle trajectories, viscous fluid flow, deposition layer formation and permeation volume flux have been simulated using a unique matching scheme which relates discrete entrance positions of particle substreams with their associated landing areas, Existing analyses consider only single particles and prescribed permeation fluxes, i.e. d_ν is either a constant or an exponentially decaying function.

The new multi-particle trajectory and deposition model was compared with published results from single particle trajectory studies and hemoglobin recovery experiments. The simulator was then employed to investigate the effects of initial operational conditions, particle layer growth, and cake layer movement on permeation flux decline and particle retention efficiency of a representative membrane separation unit.

The flexible Simula don model can be used for basic investigations of internal fluid-particle systems and can be applied to study membrane fouling in pressure-driven separation devices.     

TWO DROP MASS TRANSFER WITH CHEMICAL REACTION-ASYMPTOTIC CASE STUDIES

Mass transfer at very low and moderately high Peclet numbers has been analyzed for two interacting solid spheres and for drops in tandem. In the first case study, where the Peclet and Reynolds numbers approach zero, interactions between two drops with liquid phase chemical reaction affect the mass flux more drastically for gas resistance controlling cases than for liquid resistance controlling cases. The effects of drop size, spacing, and reaction rate on the Sherwood numbers have been considered and the various regimes of gas and liquid side control have been numerically established. The asymptotic value of the average Sherwood number as the interdrop distance approaches infinity is lower for the case of two drops than for two solid spheres, i.e. it was found that ¯Sh² _drops = ¯0.5Sh² _solidspheres, as (dAB/a)→∞

For the case of mass transfer at moderately high Peclet numbers potential flow, i.e. Re→∞, was assumed. This limited analysis indicates that there is no significant difference between the single drop and the two drop cases.     

Gas Concentrations in Modified Atmosphere Bulk Vegetable Packages as Affected by Package Orientation and Perforation Location

A perforated plexiglass package box was used to study the effects of package orientation and perforation location on gas concentration profiles during modified atmosphere packaging of broccoli (Brassica oleracea) florets. Three package orientations and perforation locations were studied. Two temperature conditions were studied namely: constant temperature at 2°C and variable temperature between 2 and 20°C. Package orientation and perforation location affected gas concentration gradients across the package. Placing the package in a vertical orientation with perforation at the top side, resulted in higher gas concentration gradients in the package. Lower gas concentration gradients were obtained when the package was placed in a vertical orientation with perforation at the lower side. Temperature variation resulted in gas concentration fluctuation in the package.     

EFFECT OF COOKING ON THE PROFILE OF PHENOLICS, TANNINS, PHYTATE, AMINO ACID, FATTY ACID AND MINERAL NUTRIENTS OF WHOLE-GRAIN AND DECORTICATED VEGETABLE COWPEA (VIGNA UNGUICULATA L. WALP)

ABSTRACT

An experiment was conducted to determine the profile of phenolics, tannins, phytate, amino acid, fatty acid and mineral nutrients in whole‐grain and decorticated vegetable cowpea before and after cooking. Two cowpea varieties: C‐152‐White, having big grain and S‐1552‐White, having small grain with black eye were used for the study. Decortication of cowpea grain resulted in significant reduction (P ≤ 0.05) of total phenolics, total tannins and phytate contents of the two cowpea varieties. Comparison showed that cooking resulted in 19, 28, 28 and 37% losses in phenolics in whole‐grain C‐152, decorticated C‐152, whole‐grain S‐1552 and decorticated S‐1552, respectively. After cooking, whole‐grain and decorticated C‐152 retained 52.1 and 57.7% tannins while S‐1552 retained 59.4 and 49.5%, respectively. In the whole grain, C‐152 lost 72.2% phytate after cooking while S‐1552 lost 70.3%. For the decorticated samples, C‐152 lost 72.4% phytate after cooking while S‐1552 lost 71.2%. For the two cowpea varieties, decortication resulted in significant (P ≤ 0.05) losses of Ca, Fe, Mn, Mg, Zn, K and Cu while there was no significant effect on protein and amino acid profile. Cooking did not cause any significant change in the mineral nutrient composition of either the whole‐grain or decorticated cowpea. For the two cowpea varieties, bulk of the fat consisted of palmitic acid (23.2–27.3%) and stearic acid (53.5–59.8%) in the ratio of 1:2, approximately. Upon cooking, losses of crude protein were recorded in the whole‐grain and decorticated samples of the two cowpea varieties.

PRACTICAL APPLICATIONS

Cowpea is an important cheap source of protein particularly for the low‐income countries, especially in Africa and Asia. However, there is the need for some pretreatments before its cooking because of the presence of some undesirable antinutrients which often cause flatulence after consumption or they can render some minerals unavailable for body assimilation. This study investigated the role that African traditional method of decortication and cooking could play in reducing the concentration of antinutritional factors. We also showed how the traditional treatments could affect the other nutritionally important component of cowpea.

     

Isolation of a Caffeine-Resistant Mutant of Aspergillus parasiticus

A caffeine-resistant mutant of Aspergillus parasiticus NRRL 2999 was isolated and subsequently designated strain BCR1. The mutant strain grew in the presence of > 8 mg/mL caffeine, while growth of the parent strain was delayed by 1 mg/mL and inhibited by 2 mg/mL. Strain BCR1 produced abundant amounts of aflatoxin only when cultured in media containing caffeine. Residual caffeine analyses indicated that caffeine-resistance in BCR1 was not due to the metabolic elimination of caffeine.