Predictive hydrogeochemical modelling of bauxite residue sand in field conditions

The suitability of residue sand (the coarse fraction remaining from Bayer's process of bauxite refining) for constructing the surface cover of closed bauxite residue storage areas was investigated. Specifically, its properties as a medium for plant growth are of interest to ensure residue sand can support a sustainable ecosystem following site closure. The geochemical evolution of the residue sand under field conditions, its plant nutrient status and soil moisture retention were studied by integrated modelling of geochemical and hydrological processes. For the parameterization of mineral reactions, amounts and reaction kinetics of the mineral phases natron, calcite, tricalcium aluminate, sodalite, muscovite and analcime were derived from measured acid neutralization curves. The effective exchange capacity for ion adsorption was measured using three independent exchange methods. The geochemical model, which accounts for mineral reactions, cation exchange and activity corrected solution speciation, was formulated in the geochemical modelling framework PHREEQC, and partially validated in a saturated-flow column experiment. For the integration of variably saturated flow with multi-component solute transport in heterogeneous 2D domains, a coupling of PHREEQC with the multi-purpose finite-element solver COMSOL was established. The integrated hydrogeochemical model was applied to predict water availability and quality in a vertical flow lysimeter and a cover design for a storage facility using measured time series of rainfall and evaporation from southwest Western Australia. In both scenarios the sand was fertigated and gypsum-amended. Results show poor long-term retention of fertilizer ions and buffering of the pH around 10 for more than 5 y of leaching. It was concluded that fertigation, gypsum amendment and rainfall leaching alone were insufficient to render the geochemical conditions of residue sand suitable for optimal plant growth within the given timeframe. The surface cover simulation demonstrates that the soil moisture status in the residue sand can be ameliorated by an appropriate design of the cover layer with respect to thickness, slope and distance between lateral drains.     

Assessment of cure-residual strains through the thickness of carbon–epoxy laminates using FBGs Part II: Technological specimen

This paper is a continuation of our previous study [Mulle M, Collombet F, Olivier P, Grunevald Y-H. Assessment of cure residual strains through the thickness of carbon–epoxy laminates using FBGs, part I: elementary specimen. Compos Part A 2008. doi:10.1016/j.compositesa. 2008.10.008] pertaining to the assessment of autoclave cure-induced strains through the thickness of carbon–epoxy laminates. In this first part, postulates and measurement procedures were established for cure of elementary specimens. Based on these, this study undertakes investigation on what are called technological specimens. These specimens are of the beam type and contain geometrical specificities which represent typical structural issues. In-plane process-induced strains were studied through the thickness of a thick reinforced zone using several optical fibre Bragg gratings (FBGs) sensors embedded at different levels of the ply stack. A non-uniform distribution of residual strains was detected. Once cured, the technological specimen was subjected to a heating test whose cycle was comparable to the cure cycle. Thermally induced strains were measured with the embedded FBGs. The values recorded were compared with those of cure-induced residual strains and FEM simulation. Discrepancies were observed that strongly suggest the possible influence of environmental effects and the need for the calculation to take into account the through-the-thickness variability of thermal properties.     

The evolution of a successful liver transplant program in 1996: the clinical and administrative role of the anesthesiologist

The establishment of a new liver transplant program requires enormous planning and resources. Extensive negotiations must take place to ensure institutional and departmental commitments to obtain the proper equipment, personnel, and other resources. The formation of a well-trained multidisciplinary team of physicians and nurses becomes the next step. Finally, ample time must be provided to adequately deploy resources, lobby referring physicians, recruit patients, and troubleshoot problems as they arise.     

Evolutionary analysis of "hagfish amelogenin"

Hagfishes lack mineralized tissues and teeth. Part of a cDNA strand, allegedly from amelogenin, the major gene involved in enamel formation in mammals, has recently been cloned in a hagfish (Slavkin and Diekwish, Anat. Rec., 1996;245:131-150). This cloning is of great interest because it could change the current view about the evolution of mineralized tissues, but no phylogenetic analysis of this piece of DNA has been made by the authors. Phylogenetic analysis of this part of cDNA has been conducted using both phenetic and cladistic methods. The cDNA amplified in hagfish does not fit with a nonmammalian origin but fits well with a degraded rodent sequence. The gene cloned in hagfish is probably of mammalian origin due to contamination during PCR.     

Comparison between hypo- and hyperglucidic diets on protein sparing in major visceral surgery (author's transl)

The authors compare the protein sparing effect of two diets, exclusively intravenous, including the same protein intake, but a different caloric intake, 21 calories/gm nitrogen for diet "A" (20 cases); 138 calories/gm nitrogen for diet "B" (20 cases). This has been observed during the six post-operative days of major visceral surgery: oesophagectomy, total gastrectomy, colic or rectocolic exeresis, sequestrectomy for acute pancreatitis, lots having been drawn for the diets. Daily nitrogen balances have been made and plasmatic and urinary levels of amino-acids have been measured before surgery and on the third and fifth post-operative days. Statistical exploitation is done by variance analysis (linear model of three factors) with a 99% confidence ratio: 1) Patient factor has no influence whatsoever on cumulative nitrogen balance. 2) Time factor arises only on the fourth post-operative day and only in the hypocaloric diet, leading to catabolism. 3) Metabolic condition is determinant. On no cancerous disease, superiority of hypercaloric diet is well demonstrated. On cancerous disease, nitrogen loss is only significantly different on 4th and 5th post-operative day: hypercaloric diet gives a better nitrogen balance.     

Displacement field measurements and capitalizing on experience: Application to the analysis of the rupture of holed composite plates

In this paper, we have concentrated on the use of the technique of measuring displacement fields by digital image correlation during tensile tests on different holed composite laminates. This technique is of particular use in validating the FE computation results with the aim of “capitalizing on experience”, i.e. identifying certain parameters of the material’s behavior directly from structure tests. We have demonstrated the feasibility of such an approach with the analysis of the rupture of holed composite plates (improved confidence in the failure criteria).     

Extracellular Vesicles from 50,000 Generation Clones of the Escherichia coli Long-Term Evolution Experiment

Extracellular vesicles (EVs) are critical elements of cell–cell communication. Here, we characterized the outer membrane vesicles (OMVs) released by specific clones of Escherichia coli isolated from the Long-Term Evolution Experiment after 50,000 generations (50K) of adaptation to glucose minimal medium. Compared with their ancestor, the evolved clones produce small OMVs but also larger ones which display variable amounts of both OmpA and LPS. Tracking ancestral, fluorescently labelled OMVs revealed that they fuse with both ancestral- and 50K-evolved cells, albeit in different proportions. We quantified that less than 2% of the cells from one 50K-evolved clone acquired the fluorescence delivered by OMVs from the ancestral strain but that one cell concomitantly fuses with several OMVs. Globally, our results showed that OMV production in E. coli is a phenotype that varies along bacterial evolution and question the contribution of OMVs-mediated interactions in bacterial adaptation.     

Is High-Intensity Interval Training Suitable to Promote Neuroplasticity and Cognitive Functions after Stroke?

Stroke-induced cognitive impairments affect the long-term quality of life. High-intensity interval training (HIIT) is now considered a promising strategy to enhance cognitive functions. This review is designed to examine the role of HIIT in promoting neuroplasticity processes and/or cognitive functions after stroke. The various methodological limitations related to the clinical relevance of studies on the exercise recommendations in individuals with stroke are first discussed. Then, the relevance of HIIT in improving neurotrophic factors expression, neurogenesis and synaptic plasticity is debated in both stroke and healthy individuals (humans and rodents). Moreover, HIIT may have a preventive role on stroke severity, as found in rodents. The potential role of HIIT in stroke rehabilitation is reinforced by findings showing its powerful neurogenic effect that might potentiate cognitive benefits induced by cognitive tasks. In addition, the clinical role of neuroplasticity observed in each hemisphere needs to be clarified by coupling more frequently to cellular/molecular measurements and behavioral testing.     

Optical fibre musical instruments: making sense of the senseless

This paper demonstrates how the light transmitted through a stretched optical fibre may be used to detect its modes of vibration. In particular, replacing strings of a musical instrument with optical fibre allows the fabrication of a simple acoustic instrument with a single laser source and single detector. The detected signal contains rich harmonics of the vibrating fibre. This device may be used as a vibration, temperature or strain sensor, or simply as a musical instrument. Coating the optical fibre with novel materials such as PZLT may well allow a modification of vibration properties to enhance, suppress certain harmonics or lead to the development of simple electric field sensors.