Iron Oxidation at Low Temperature (260–500 °C) in Air and the Effect of Water Vapor

The oxidation of iron has been studied at low temperatures (between 260 and 500 °C) in dry air or air with 2 vol% H₂O, in the framework of research on dry corrosion of nuclear waste containers during long-term interim storage. Pure iron is regarded as a model material for low-alloyed steel. Oxidation tests were performed in a thermobalance (up to 250 h) or in a laboratory furnace (up to 1000 h). The oxide scales formed were characterized using SEM-EDX, TEM, XRD, SIMS and EBSD techniques. The parabolic rate constants deduced from microbalance experiments were found to be in good agreement with the few existing values of the literature. The presence of water vapor in air was found to strongly influence the transitory stages of the kinetics. The entire structure of the oxide scale was composed of an internal duplex magnetite scale made of columnar grains and an external hematite scale made of equiaxed grains. ¹⁸O tracer experiments performed at 400 °C allowed to propose a growth mechanism of the scale.     

An aerosol-based route to nanostructured powders synthesis in liquids

An alternative technique for synthesizing nanostructured powders in liquid solutions has been developed. The technique combines generation of charged aerosols via electrospray with reductive precipitation reactions in liquids. Electrospray of liquids is carried out to produce micrometric, nearly mono-dispersed airborne droplets from a precursor solution. The droplets, which are spatially separated due to electrostatic repulsion, are collected in a bath containing a reductive solution. The effect of some process parameters on the resulting material texture has been studied. Tin particles produced from tin chloride solutions are regarded as a model here, but it is stressed that this approach can be considered as a general method to synthesize many other metallic-like materials, such as alloys and intermetallics. Hence, the large variety of materials that can be produced in this way could find several relevant applications in different technological fields.     

Results of surgery of vitreomacular traction syndromes

PURPOSE: The vitreomacular traction syndrome is a rare entity in which partial posterior vitreous detachment is combined with persistent macular adherence, thus causing macular traction. In most cases, an epimacular membrane is associated with this vitreomacular traction. We evaluate here the results of vitreous surgery for this syndrome. METHODS: We reviewed 18 consecutive eyes that had undergone vitrectomy and posterior epiretinal membrane stripping, to define the visual results and complications of surgery for the vitreomacular traction syndrome. Minimum follow-up was 3 months. RESULTS: Patients' average age was 63.5 years. All had evidence of cystic macular changes on biomicroscopic examination. Sixteen patients had an epiretinal membrane, and two, a full-thickness macular hole. Cystoid macular edema was present in 7 eyes on fluorescein angiography. The release of vitreomacular traction improved vision in 72% of eyes, with six patients obtaining 20/40 visual acuity or better. Complications of surgery included progression of nuclear sclerosis, and epiretinal membrane formation. CONCLUSION: Vitrectomy for vitreomacular traction syndrome may improve visual acuity, but the visual prognosis remains poor.     

Multinucleated giant cells elicited around hydroxyapatite particles implanted in craniotomy defects are not osteoclasts

BACKGROUND: The nature of the multinucleated giant cells (MNGC) elicited in contact with implantable biomaterials is still indecisive. METHOD: In Wistar rats the MNGC recruited after the implantation of hydroxyapatite (HA) particles in standardized skull defects were examined morphologically (at both the light and electron microscope levels), enzymatically (tartrate-resistant acid phosphatase and non-specific esterase), and after a challenge with salmon calcitonin. RESULTS: The MNGC were of great size and contained abundant mitochondria, vacuoles, and vesicles throughout the cytoplasm; they were either tightly apposed to the HA surface or had long and thin processes penetrating the material. When processed for tartrate-resistant acid phosphatase, only a few cells were weakly stained. The staining was totally suppressed when samples were pretreated with cyanuric chloride in the MNGC but not in the host osteoclasts. Calcitonin induced the withdrawal of the host osteoclasts from the bone surface while the MNGC remained in contact with the HA material. CONCLUSION: The MNGC recruited to HA particles did not exhibit the morphologic, enzymatic and functional characteristics of the osteoclasts, and consequently must be regarded as macrophage polykaryons.     

Oligochaete worms as biological describers of the interactions between surface and groundwaters: A first synthesis

The paper focuses on the definition of the vulnerability of phreatic waters to surface water pollution. The amplification of water exchanges between surface and underground waters, because of human activities, is considered as a risk of contamination of aquifers. The aim of this paper is to present a first synthesis of oligochaetes as biological describers of these exchanges. Field investigations have shown that several rare and/or stygophilous taxa are found in surface (coarse) sediments of rivers upstream and/or downstream of dams or gravel operations. These observations relate to species such as Propappus volki, Pristina spp., Chaetogaster parvus, Rhyacodrilus carsticus, R. falciformis, Phallodrilus spp. The data suggest that these species invade surface waters from phreatic or interstitial waters when water flows are amplified between the two. Flow amplification is considered as a consequence of dams' and gravel operations' hydraulic impact. But the lack of hydraulic validation of the presumed active exchanges describer's (AED) ecological status given to those species remains a problem, giving the opportunity to examine the link between hydraulics and biology. Preliminary results on two gravel pits of La Wantzenau (Rhine alluvial valley, France) have shown relations between the distribution of oligochaetes, especially Lumbriculidae, and soil filtration properties. Two other studies were planned along an industrially polluted tract of the River Rhǒne (Grand Gravier Island). Horizontal and vertical zonation of the river banks were performed by studying simultaneously hydraulics and oligochaetes. Preliminary results have shown that the absolute and relative abundances of taxa such as Phallodrilus sp. and S. velutinus increase in relation to the permeability of superficial coarse substrate in the horizontal plane, and to the current velocity in underground porous media in the vertical plane. The increasing percentages of P. barbatus and the decreasing percentages of Tubificidae reveal active exchange zones where superficial waters are renewed by groundwaters. Some other species such as P. vejdovskyi seem to be potential describers of water exchanges.     

Effects of dietary corn oil and salmon oil on lipids and prostaglandin E2 in rat gastric mucosa

Three groups of male rats were fed either a corn oilenriched diet (17%, w/w), a salmon oil-enriched diet (12.5%) supplemented with corn oil (4.5%) or a low-fat diet (4.4%) for eight wk to investigate the possible relationships between dietary fatty acids and lipid composition, and prostaglandin E₂ level and phospholipase A₂ activity in the rat gastric mucosa. High-fat diets induced no important variation in total protein, phospholipid and cholesterol contents of gastric mucosa. Compared with a low-fat diet, corn oil produced a higher n−6/n−3 ratio in mucosal lipids, whereas this ratio was markedly lowered by a fish oil diet. In comparison with the low-fat diet, the production of prostaglandin E₂(PGE₂) in gastric mucosa of rats fed salmon oil was significantly, decreased by a factor of 2.8. In the corn oil group, PGE₂ production tended to decrease, but not significantly. In comparison with the low-fat diet, both specific and total gastric mucosal phospholipase A₂ activities were increased (+18 and 23%, respectively) in the salmon oil group; they were unchanged in the corn oil group. It is suggested that the decrease of gastric PGE₂ in rats fed fish oil is not provoked by a decrease in phospholipase A₂ activity but may be the result of the substitution of arachidonic acid by n−3 PUFA or activation of PGE₂ catabolism.     

Clinical trial of 2 tobacco use cessation interventions in primary care

OBJECTIVE: To study the efficacy of two types of intervention to stop tobacco dependency. DESIGN: Randomised clinical trial. SETTING: Primary care centre. PATIENTS AND OTHER PARTICIPANTS: Smokers recruited from among the health centre users through the preventive activities and health promotion programme. INTERVENTIONS: Independent variable: type of intervention. General variables: age, sex, marital status, educational level, work situation, cohabitation with children, smokers at home, number of years smoking, type of tobacco. There were two types of intervention: a) Minimal Intervention (MI). b) Advanced Intervention (AI). 54 patients were included, with 6 losses. 21 were assigned at random to the MI group and 27 to the AI group. Progress was measured at 15 days, 1 month, 3 months, 6 months and a year. RESULTS: In the MI, 23.8% were abstinent at 15 days; the same percentage at one month and 3 months; 19% at 6 months; and 14.3% remained abstinent after a year. In the AI, 51.9% were abstinent at 15 days; 48.1% at both one and 3 months; 25.9% at 6 months; and 22.2% were still not smoking after a year. No significant differences between the two interventions were found in any of the observations. CONCLUSIONS: These data do not show that one intervention is better than the other. With the passage of time the effect of the intervention decreased in both groups.