Mathematical model for lactic acid production from lactose in batch culture: Model development and simulation

The models available to describe lactic acid production do not seem to fit the experimental data very well, especially at the end of batch cultures. From a careful analysis of batch data, an unstructured model of the process has been derived, in which the specific growth rate variations and lactic acid concentration with time have been described by complemented logistic functions. Also, an additional term has been introduced into the Luedeking–Piret expression, taking into account the reduction in rate of lactic acid production observed at very low growth rate.     

Analyse D’une Ligne Microruban Diélectrique Blindée Avec étude des Pertes Diélectriques et Métalliques

A shielded dielectric line is analyzed by Schelkunoff ’s method taking in account losses of the line, the substrate and the metallic shield. Phase and dielectric attenuation constants are first computed. Then the computation of the electric and magnetic fields allows to find the attenuation due to the shield. The results graphically presented for different lines are at last commented and compared to experimental values.     

Phosphorus saturation potential: a parameter for estimating the longevity of constructed wetland systems

Phosphorus (P) adsorption capacities of materials derived from batch experiments can vary by several orders of magnitude depending on the method used, leading to potential misinterpretation of the P retention capacity on a long-term basis and unrealistic estimations of constructed wetland systems (CWS) longevity. The objective of this study was to determine if the P saturation of the material in a column could be used for this purpose with an improved accuracy. A 278-d column experiment with a synthetic P solution was conducted to investigate the long-term P retention capacity of electric arc furnace (EAF) steel slag up to its P saturation point. EAF slag showed a high affinity for P, reaching a saturation value of 1.35 g of P kg(-1). Investigations of the regeneration of the P adsorbing capacity by this material showed that, after 4 weeks of water desaturated resting, EAF steel slag was able to increase its initial P adsorptive capacity to 2.35 g of P kg(-1). A sequential P fractionation experiment was performed to quantify the proportion of P bound to mineral compounds in EAF. From the most loosely bound to the most strongly bound P fraction, P was associated with resin extractable (14%), Fe extractable (0.5 M Na2CO3, 47%), Al extractable (0.1 M NaOH, 1%), Ca extractable (1 M HCl, 12%), and Ca in a stable residual pool (concentrated hot HCl, 26.5%). X-ray fluorescence analyses of EAF steel slag chemical composition revealed that the continuous application of a P solution resulted in 75% and 59% increases in K2O and P2O5 respectively; Al2O3 and FeO increased by 8%, while the portion of CaO remained unchanged. The investigated properties (P retention potential, regeneration of P adsorption, P fractionation) provide useful data about the suitability of slag material as a media for long-term P removal and should enable an improved prediction of the longevity of full-scale CWS.     

Separation in slalom chromatography: stretching and velocity dependence

Slalom chromatography (SC) is used for the separation of large double-stranded DNA molecules. In this technique, the progression of the DNA fragments through the closed column packing follows the flow direction and is like a snake edging is way into long grass. A novel mathematical model is developed in this paper to describe this hydrodynamic phenomenon. The results obtained provided a model for the resolution between two adjacent peaks on a chromatogram. As well, a chromatographic response function was used to obtain the most efficient separation conditions for a mixture of DNA fragments with sizes higher than 15 kbp in a minimum analysis time.     

Correlation image velocimetry: a spectral approach

A method, believed to be new, is introduced to evaluate displacement fields from the analysis of a deformed image compared with a reference image. In contrast to standard methods, which determine a piecewise constant displacement field, the present method gives direct access to spectral decomposition of the displacement field. A minimization procedure is derived and used twice: first, to determine an affine displacement field and, then, the spectral components of the residual displacement. Although the method is applicable to any space dimension, only cases dealing with one-dimensional signals are reported: First, a purely synthetic example is discussed to estimate the intrinsic performance of the method, and a second case deals with a profile extracted from a sample of compressed glass wool.     

Open terminations for periodic structures

This letter presents the results of a study of open terminations of a cylindrical waveguide periodically loaded by metallic irises. To interpret and explain the action of these open terminations on the resonance modes of the periodic cavities, a systematic study of the dimensions influence on resonant frequency, mode configuration and quality factor has been undertaken.     

Use Of Ozone For The Treatment Of A Combined Urban And Industrial Effluent: A Case History

This paper describes the treatment of highly colored urban wastewater containing a high percentage of industrial effluents and a significant concentration of detergents. The kinetics of detergent ozonation were established through a series of pilot tests including variation of the ozone concentrations in the carrier gas. The results obtained concerning the optimum conditions of ozonation - treatment dose and contact time - have been used for the design of an industrial ozonation plant.     

Synthesis of furoates and 5-nitrofuroates in cyclohexane in the presence of cation-exchange resins

The use of ion-exchange resins for the esterification of furoic acid and 5-nitrofuroic acid was characterised by an excellent yield and the absence of side reactions, particularly when the reaction was carried out in cyclohexane in the presence of the resin, SPC 118. The use of this solvent for such a reaction in a biphasic medium is thus reported for the first time. This procedure might therefore be considered on a larger scale.     

Characterization of γ-linolenic acid inRibes seed

The total lipid content of fruit seeds of theRibes family ranges by weight from 18.3% in gooseberries (Ribes uva Crispa) to 30.5% in black currants (Ribes nigrum). Isolation procedures and analytical methods (gas chromatography, mass spectrometry, high performance thin layer chromatography and stereospecific analysis) demonstrate that the oils fromRibes seeds contain up to 19% by weight of γ-linolenic acid (γ-LA, C18∶3, n−6) in black currant oil. This lastRibes species thus constitutes one of the richest natural sources in γ-LA yet described. These oils appear promising for critically ill patients who seem unable to convert linoleic acid into subsequent EFA fractions.