On the Development of Thermo-Kinetic Eh-pH Diagrams

It is shown that thermo-kinetic Eh-pH diagrams can be generated through electrochemical measurements. These diagrams offer an accurate method of determining stability regions for leaching without relying on thermodynamic calculations, which may be inaccurate or for which data may be difficult to obtain. The Fe-NH₃-CO₃-H₂O system is studied here. Potentiodynamic polarization experiments were performed on an iron sample in ammoniacal solution in de-aerated condition at different temperature and pH. Polarization plots show that both active anodic dissolution and passive regions are present for pure iron in ammoniacal solution depending on the potential. The electrochemically obtained potential-pH data were used to generate the thermo-kinetic Eh-pH diagrams for the Fe-NH₃-CO₃-H₂O system.     

Damage mechanisms analysis of a multi-scale fibre reinforced cement-based composite subjected to impact and fatigue loading conditions

For several years, Laboratoire Central des Ponts et Chaussées (LCPC) has worked on the development of new cement composites in order to obtain materials sufficiently tough and ductile to be used in structures or structural elements without any other reinforcement that fibres.Then a multi-scale fibre reinforced cement-based composite (MSFRCC) has been developed and patented. It is principally characterized by a high percentage of fibres, percentage equal to 11% per m³.Three fibre dimensions are used in this composite.In the present article, a qualitative analysis of damage mechanisms of this material under impact and fatigue loadings is proposed.Concerning impact loading condition, the main conclusions are:

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Apparent fibre-matrix adherence, which increases with the loading rate, leads to an increase in material modulus of rupturel, an increase much greater than for all existing cement-based materials due to high percentage of fibres used;

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Mechanical homogenization of composite with loading rate is the result of cracks delocalization during cracking process. This delocalization results from viscous effects generated within the matrix and around the fibre-matrix interfaces.

Concerning fatigue loading condition, the main conclusions are:

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Intermediate fibre length (high percentage of meso-fibres) that is highly and positively involved in material static tensile strength, corresponds to scale of fibre that is sensitive to fatigue loading. As a matter of fact, meso-fibres become rapidly inactive and composite can no longer behave as a multi-scale reinforcement material. Material strength is then greatly affected.

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If the initial cracking state of the material before fatigue loading corresponds to a state of tensile strain that is less than or equal to 1.27 10^− 3, meso-fibres perfectly play their role with respect to relevant cracks (i.e. meso-cracks whose opening corresponds to their mechanical efficiency domain, that means less than 100 μm), material fatigue behaviour being then good (fatigue rupture after 2 millions of cycles).

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Specimens that did not break before 2 millions of cycles have better residual bending behaviour (gain of 6.5%) than reference specimens (specimens which were not previously loaded in fatigue) This result is the consequence of a morphological modification of cracks due to fatigue loading. Indeed, fatigue cycles lead to a gradual “blunting” of crack tips, cracks that subsequently become less dangerous with respect to their potential propagation.

     

From pore scale to wellbore scale: Impact of geometry on wormhole growth in carbonate acidization

Acid injection in carbonate reservoir is commonly used in the oil industry to improve, or at least recover, its productivity. The aim of this stimulation technique is to create empty channels called wormholes which, if successful, would bypass the damaged area near the wellbore. During production, wormholes become pathways for the reservoir oil to reach the well. This technique increases near-wellbore permeability, and therefore improves oil production. The interaction between the transport of acid, chemical reaction, and heterogeneities encountered at different scales, controls the unstable behaviour of wormholing and, thus, the success of the treatment. Most of the experimental and numerical studies done on this subject in the past have been limited in their observations because they only considered the dissolution process at a small scale (from pore scale to core scale). The purpose of this work is to study how the geometry of the domain can constrain wormhole competition, and influence wormholing dynamics in a core submitted to acidizing.After a short review of the literature on wormholing to see how the geometry effect could have influenced previous experiments, we study specifically the question of wormhole density. We emphasize that two mechanisms are involved in wormhole competition, with one of them being effective only at small scale. Thus we conclude that wormholing is not a full-scale independent process. We describe differences in the wormhole growth dynamics between “confined” and “unconfined” domains for different dissolution regimes. We focus on optimum conditions and their transition from “confined” to “unconfined” domain to realize that the flow rate in the dominant wormhole does not depend on geometric effects. We conclude by a comparison between 2D and 3D simulations, in both linear and radial flow, and observe changes in the wormholing process. All our results serve as a discussion about definitions of optimum conditions in the literature.     

New Raman spectrometer using a digital micromirror device and a photomultiplier tube detector for rapid on-line industrial analysis. Part I: description of the prototype and preliminary results

In this paper, a prototype of a new generation of Raman spectrometers, based on the use of a monochromator, a digital micromirror device as light modulator, and a photomultiplier tube as detector of the Raman light, is described. This spectrometer, containing no moving parts, is inexpensive, robust, and very precise. New in concept, this spectrometer makes it possible to record, in addition to classical Raman spectra, the intensity at several selected points of the spectrum and/or the total intensity in several selected intervals at the same time with great accuracy, thus giving new possibilities for analytical applications. Also, the work presented demonstrates the possibilities of this very simple prototype for rapid on-line industrial analysis, with an example of quantitative analysis of binary and ternary mixtures of xylene isomers. The precision obtained is satisfactory (errors of prediction approximately 3% in 5-6 seconds per sample).     

A better philosophy for a better psychology: Comment on Slaney and Racine (2011).

In their thought-provoking article, Slaney and Racine (2011) put forth several criticisms of the traditional view that concepts are mental representations used in the cognitive processes that underlie human higher cognitive competences (categorization, induction, etc.). Considerations of a broadly Wittgensteinian nature underlie their criticisms. In this article, I argue that the considerations advanced by Slaney and Racine do not undermine the clear account of the nature of mental states and psychological processes developed in the 1960s and 1970s and endorsed in my book Doing without Concepts (Machery, 2009). (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Control of visual conditions for open-plan offices

This paper reports insights about energy savings in buildings dedicated to tertiary activity. The goal is to employ as much as possible natural light flows to minimize the artificial light source consumption. Although the solar energy is power-efficient to light and heat a room, this natural source remains complex to manage and can generate inconveniences related to occupants visual comfort. The authors propose a global solution to deal with visual comfort by controlling the daylight contribution to the indoor light atmosphere. This control structure is based on the use of an innovative sensor of light conditions and it was implemented within an experimental room equipped with classic Venetian blinds. This paper focuses on the control laws to apply in order to meet visual needs for current tasks performed in offices.     

Methodological characteristics of the national dietary surveys carried out in the European Union as included in the European Food Safety Authority (EFSA) Comprehensive European Food Consumption Database

In 2009 competent organisations in the European Union provided the European Food Safety Authority (EFSA) with data from the most recent national dietary survey at the level of individuals' consumption. Twenty different Member States provided EFSA with data from 22 different national dietary surveys, with consumption figures for adults and, when available, for children. Member States' dietary data were assembled into the EFSA Comprehensive European Food Consumption Database. In this paper an overview of the methodologies and protocols employed in the different national dietary surveys is provided. Specifically, details about dietary assessment methods, interview administration, sampling design, portion size estimation, dietary software, evaluation of under-reporting and non-dietary information collected are described. This information is crucial to evaluate the level of accuracy of food consumption data and to anticipate and acknowledge the utmost important sources of heterogeneity of national databases included in the Comprehensive Database. The Comprehensive Database constitutes a unique resource for the estimation of consumption figures across the European Union and represents a useful tool to assess dietary exposure to hazardous substances and nutrient intake in Europe. Nevertheless, the many substantial methodological differences that characterise the Comprehensive Database are acknowledged and critically discussed.     

A predictive model based on tortuosity for pressure drop estimation in ‘slim’ and ‘fat’ foams

The use of porous structures with high external surface area represents an important breakthrough in several industrial applications. Foam structures have received an increasing scientific and industrial interest since the last decade. Knowledge of pressure drop induced by these foam structures is thus essential for successful design and operation of high performance industrial systems. In this context, an analytical investigation was conducted for the determination of the permeability and the inertial coefficient in foams. The theoretical model is based on modified cubic lattice, which allows to take into account the presence of matter at the junction of struts. The existing model developed in the literature is then modified to incorporate this geometrical approach for determining the tortuosity of the foam. Finally, the permeability and inertial coefficient analysis are performed in order to derive the pressure drop on foams. The modeling procedure is based only on physical principles and geometrical considerations with no adjustable parameters in order to reconcile the theoretical work with the experimental data of the literature. Finally, this model is validated for two marginal cases (i.e. ‘slim’ and ‘fat’ foams).     

The Characterisation of Pluripotent and Multipotent Stem Cells Using Fourier Transform Infrared Microspectroscopy

Fourier transform infrared (FTIR) microspectroscopy shows potential as a benign, objective and rapid tool to screen pluripotent and multipotent stem cells for clinical use. It offers a new experimental approach that provides a holistic measurement of macromolecular composition such that a signature representing the internal cellular phenotype is obtained. The use of this technique therefore contributes information that is complementary to that acquired by conventional genetic and immunohistochemical methods.     

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