Thermal fatigue of cast irons for automotive application

The thermal fatigue damage constitutes the major problem of the parts subject to a variation in temperature during their operation. Several materials have been used for such structures in order to limit their damage. The facility of implementation and low cost of cast iron constitute an advantage for its use for the Diesel motors.     

One-Sided Chronic Intervillositis of Unknown Etiology in Dizygotic Twins: A Description of 3 Cases

Chronic intervillositis of unknown etiology (CIUE) is a rare, poorly understood, histopathological diagnosis of the placenta that is frequently accompanied by adverse pregnancy outcomes including miscarriage, fetal growth restriction, and intrauterine fetal death. CIUE is thought to have an immunologically driven pathophysiology and may be related to human leukocyte antigen mismatches between the mother and the fetus. Dizygotic twins with one-sided CIUE provide an interesting context to study the influence of immunogenetic differences in such cases. The main immune-cell subsets were investigated using immunohistochemistry. We identified three dizygotic twin pregnancies in which CIUE was present in only one of the two placentas. Two of the pregnancies ended in term delivery and one ended in preterm delivery. Presence of CIUE was correlated with lower placental weight and lower birthweight. Relative number of CD68, CD56, CD20, and CD3 positive cells were comparable between co-twins. The presence of one-sided CIUE in dizygotic twin pregnancy was associated with selective growth restriction in the affected twin. This suggests a unique fetal immunogenetic contribution to the pathogenesis of CIUE. Further study of dizygotic and monozygotic placentas affected by CIUE could identify new insights into its pathophysiology and into the field of reproductive immunology.     

Selection of renewable energy technologies for Africa: Eight case studies in Rwanda,Tanzania and Malawi

Renewable energy technologies need to be implemented to improve the current lack of access to energy on the African continent. However, the implementation of renewable energy technologies in Africa often fails, or the technologies are found to be unsustainable in the longer term. Previous research determined eleven factors that should be taken into account for the selection of sustainable, renewable energy technologies in Africa. The purpose of this research was to confirm and build upon these findings by means of eight case studies that were conducted in Rwanda, Tanzania and Malawi. Various individuals from implementing agencies, as well as end users of the various technologies, were interviewed, while secondary data were gathered in the form of project reports and other documentation. The analyses of the data confirm the importance of the eleven factors that were previously identified. A final set of thirteen factors that should be used for the selection of renewable technologies are proposed.     

Modeling and Simulation of Activated Sludge Process with Cyclic Feeding for Treatment of Highly Loaded Wastewater

The treatment of strongly loaded wastewater (COD > 1,5 kg m^–3by an activated sludge process (aeration basin + clarifier) depends both on the ability of the activated sludge to remove the soluble organic pollution and on the efficiency of the separation of the treated water from the biomass. The separation ability of the activated sludge notably depends on the hydraulic configuration of the aeration basin: biomass settleability can be controlled by completely mixed reactors (CMR) in series, plug-flow reactors or intermittently fed systems. Moreover, the biomass settleability is linked to the extracellular polymers which are largely composed of microbial exopolysaccharides (EPS). A low level of EPSs indicates a sludge deflocculation problem, whereas a high level of EPSs means that sludge settleability could be hindered because of an excessive growth of filamentous organisms. Experiments show that the use of only one CMR, fed in a cyclic way with permanent oxygenation and return sludge flow, leads to good settleability and effluent quality. The purpose of this paper is to propose a very simple model, based on experiments, in order to optimize the cyclic feeding period by simulations.     

Clinical Significance of Stem Cell Biomarkers EpCAM,LGR5 and LGR4 mRNA Levels in Lymph Nodes of Colon Cancer Patients

The significance of cancer stem cells (CSCs) in initiation and progression of colon cancer (CC) has been established. In this study, we investigated the utility of measuring mRNA expression levels of CSC markers EpCAM, LGR5 and LGR4 for predicting survival outcome in surgically treated CC patients. Expression levels were determined in 5 CC cell lines, 66 primary CC tumors and 382 regional lymph nodes of 121 CC patients. Prognostic relevance was determined using Kaplan-Meier survival and Cox regression analyses. CC patients with lymph nodes expressing high levels of EpCAM, LGR5 or LGR4 (higher than a clinical cutoff of 0.07, 0.06 and 2.558 mRNA copies/18S rRNA unit, respectively) had a decreased mean survival time of 32 months for EpCAM and 42 months for both LGR5 and LGR4 at a 12-year follow-up (p = 0.022, p = 0.005 and p = 0.011, respectively). Additional patients at risk for recurrence were detected when LGR5 was combined with the biomarkers CXCL17 or CEA plus CXCL16. In conclusion, the study underscores LGR5 as a particularly useful prognostic biomarker and illustrates the strength of combining biomarkers detecting different subpopulations of cancer cells and/or cells in the tumor microenvironment for predicting recurrence.     

Solubility of magnesium oxide in calcium oxide-calcium chloride mixtures

Measurements and theoretical calculations of the solubility product of magnesium oxide in calcium chloride-calcium oxide mixtures at 1133 K are reported. A filtration technique in an inert atmosphere was used to obtain samples for analysis by atomic absorption for magnesium content. At low concentrations of O^-2, the data are in consonance with the very low solubility product of 10^-6.2 predicted by a simple thermodynamic cycle first proposed by Flood, Fϕrland and Grjotheim. Work performed under the auspices of the U.S. Energy Research and Development Administration.     

A statistical mechanical theory for activity coefficients of a dilute solute in a binary solvent

A statistical mechanical calculation of the activity coefficients of a dilute solute,C, in a binary solvent,A-B, was made using a model for the interactions of a coordination cluster consisting of a solute atom and its neighboring solvent atoms. The derived equations are applicable to a variety of types of ternary solutions including substitutional and interstitial alloys as well as additive and reciprocal molten salts. The theory takes into account the interactions between solute and solvent atoms (ions) as well as changes in interactions of the solvent atoms (ions) which are neighbors of solute atoms (ions). Prior theories such as those of Wagner and the quasi-chemical theories of Alcock and Richardson and Jacob and Alcock can all be shown to be special cases of the present theory. The dependence of the activity coefficients of a solute on the solvent composition is calculated from a knowledge of the activity coefficients of the solvent components, solute activity coefficients in the two pure solvent components, a coordination number, a geometric factor which depends upon the type of solution, and a term which represents the nonadditivity of pair bond interactions within the cluster of a solute atom (ion) and its neighboring solvent atoms (ions). In the model, the thermodynamic properties of the solute are related to the relative concentrations of the different coordination clusters as well as to the thermodynamic properties of the solvent.     

Stable hydrogen and oxygen isotope composition of waters from mine tailings in different climatic environments

The stable isotope composition of waters (delta2H, delta18O) can be used as a natural tracer of hydrologic processes in systems affected by acid mine drainage. We investigated the delta2H and delta18O values of pore waters from four oxidizing sulfidic mine tailings impoundments in different climatic regions of Chile (Piuquenes at La Andina with Alpine climate, Cauquenes and Carén at El Teniente with Mediterranean climate, and Talabre at the Chuquicamata deposit with hyperarid climate). No clear relationship was found between altitude and isotopic composition. The observed displacement of the tailings pore waters from the local meteoric water line toward higher delta18O values (by approximately +2 per thousand delta18O relative to delta2H) is partly due to water-rock interaction processes, including hydration and O-isotope exchange with sulfates and Fe(III) oxyhydroxides produced by pyrite oxidation. In most tailings, from the saturated zone toward the surface, isotopically different zones can be distinguished. Zone I is characterized by an upward depletion of 2H and 18O in the pore waters from the saturated zone and the lowermost vadose zone, due to ascending diffused isotopically light water triggered by the constant loss of water vapor by evaporation at the surface. In zone II, the capillary flow of a mix of vapor and liquid water causes an evaporative isotopic enrichment in 2H and 18O. At the top of the tailings in dry climate a zone III between the capillary zone and the surface contains isotopically light diffused and atmospheric water vapor. In temperate climates, the upper part of the profile is affected by recent rainfall and zone III may not differ isotopically from zone II.