Étude de la cinétique de formation et du bris de l'inhibition des réactions FE/ZN lors de la production de revêtements galvanisés et galvanisés-alliés

Survol de l'industrie de la galvanisation -- Revue de la littérature -- Méthode expérimentale -- Résultats expérimentaux -- Discussion et synthèse des résultats

A serine-substituted P450 catalyzes highly efficient carbene transfer to olefins in vivo

Whole-cell catalysts for non-natural chemical reactions will open new routes to sustainable production of chemicals. We designed a cytochrome 'P411' with unique serine-heme ligation that catalyzes efficient and selective olefin cyclopropanation in intact Escherichia coli cells. The mutation C400S in cytochrome P450_(BM3) gives a signature ferrous CO Soret peak at 411 nm, abolishes monooxygenation activity, raises the resting-state FeIII-to-FeII reduction potential and substantially improves NAD(P)H-driven activity

Can we make human plague history? A call to action

Plague is a communicable rodent-borne disease caused by Yersinia pestis, a Gram-negative bacillus member of the Enterobacteriaceae family. As a zoonosis, plague is primarily a wildlife disease that occasionally spills over to the human population, resulting in seasonal surges in human cases and localised outbreaks. The predominant clinical form among humans is bubonic plague, which, if untreated, has a lethality of 60%–90% but is readily treatable with antibiotics, reducing the death rate to around 5% if administered shortly after the infection. One to two per cent of all bubonic cases develop into secondary pneumonic plague, which in turn may be transmitted from person to person through respiratory droplets, producing primary pneumonic plague in close contacts. Without antibiotic treatment, pneumonic plague is nearly 100% fatal, but early antibiotic treatment substantially improves survival. Today, Y. pestis is present in at least 26 countries, with more than 30 different flea vectors and over 200 mammal host species. Although human plague cases continue to be reported from Asia and the Americas, most cases currently occur in remote, rural areas of sub-Saharan Africa, mostly in Democratic Republic of Congo and Madagascar (around300–500 per year). However, large-scale transmission may also occur. During the 14th century, the Black Death, caused by Y. pestis, is estimated to have killed 30%–40% of the European population. It is important to emphasise that human plague is mostly a poverty-related disease. Therefore, given that population density and the absolute number of people living in extreme poverty are both increasing in sub-Saharan Africa, there is no likelihood of plague being eliminated as a public health threat in the foreseeable future. However, the WHO does not consider plague to be either a neglected tropical disease or a ‘priority pathogen’ that poses a public health risk because of its epidemic potential. In September 2017, an unprecedented urban outbreak of pneumonic plague was declared in Madagascar, striking primarily its capital Antananarivo and the major seaport of Toamasina. This episode once again brought international attention to plague, reminding us of the capacity for human plague to spread in urban settings and cause substantial societal and economic disruption. This should raise alarm bells that a research agenda is needed

Human plague: An old scourge that needs new answers

Yersinia pestis, the bacterial causative agent of plague, remains an important threat to human health. Plague is a rodent-borne disease that has historically shown an outstanding ability to colonize and persist across different species, habitats, and environments while provoking sporadic cases, outbreaks, and deadly global epidemics among humans. Between September and November 2017, an outbreak of urban pneumonic plague was declared in Madagascar, which refocused the attention of the scientific community on this ancient human scourge. Given recent trends and plague’s resilience to control in the wild, its high fatality rate in humans without early treatment, and its capacity to disrupt social and healthcare systems, human plague should be considered as a neglected threat. A workshop was held in Paris in July 2018 to review current knowledge about plague and to identify the scientific research priorities to eradicate plague as a human threat. It was concluded that an urgent commitment is needed to develop and fund a strong research agenda aiming to fill the current knowledge gaps structured around 4 main axes: (i) an improved understanding of the ecological interactions among the reservoir, vector, pathogen, and environment; (ii) human and societal responses; (iii) improved diagnostic tools and case management; and (iv) vaccine development. These axes should be cross-cutting, translational, and focused on delivering context-specific strategies. Results of this research should feed a global control and prevention strategy within a “One Health” approach

Vertical Heterophoria and Postural Control in Nonspecific Chronic Low Back Pain

The purpose of this study was to test postural control during quiet standing in nonspecific chronic low back pain (LBP) subjects with vertical heterophoria (VH) before and after cancellation of VH; also to compare with healthy subjects with, and without VH. Fourteen subjects with LBP took part in this study. The postural performance was measured through the center of pressure displacements with a force platform while the subjects fixated on a target placed at either 40 or 200 cm, before and after VH cancellation with an appropriate prism. Their postural performance was compared to that of 14 healthy subjects with VH and 12 without VH (i.e. vertical orthophoria) studied previously in similar conditions. For LBP subjects, cancellation of VH with a prism improved postural performance. With respect to control subjects (with or without VH), the variance of speed of the center of pressure was higher, suggesting more energy was needed to stabilize their posture in quiet upright stance. Similarly to controls, LBP subjects showed higher postural sway when they were looking at a target at a far distance than at a close distance. The most important finding is that LBP subjects with VH can improve their performance after prism-cancellation of their VH. We suggest that VH reflects mild conflict between sensory and motor inputs involved in postural control i.e. a non optimal integration of the various signals. This could affect the performance of postural control and perhaps lead to pain. Nonspecific chronic back pain may results from such prolonged conflict

Effect of porosity on the properties of open cell titanium foams intended for orthopedic applications

Porous metals have been used in various orthopedic applications as coating to promote implant fixation or as scaffolds for bone reconstruction. Since these materials were up to recently only used as thin coating (i.e. sintered beads or mesh) and not available into shapes adequate for detailed characterization, the effect of the structure on the static and dynamic properties of these materials has not been widely reported in the literature. This paper presents the effect of the porosity (49.3\u201366.7%) on the static and dynamic properties of titanium foams produced with a powder metallurgy process. All materials exhibited compression curves with three stages, typical of ductile porous materials. When the porosity level increases, the materials become more brittle. The compression yield strength increases while the modulus is more or less unaffected when the porosity increases from 49.3 to 66.7% and does not follow the power law model accepted for porous medium. The shear strength/adhesion with dense substrates increases with density and is proportional to the compression yield strength. The fatigue limit is not directly link with the porosity. The discrepancies observed are attributed to differences in the structure as the porosity increases.Peer reviewed: YesNRC publication: Ye

High-temperature interaction of titanium with ceramic materials

Manuscript title : Low-Interaction Support Materials for High-Temperature Sintering of Ti and Ti-6AI-4V for Biomedical DevicesPeer reviewed: NoNRC publication: Ye

The effect of oxygen, nitrogen and carbon on the microstructure and compression properties of titanium foams

This paper presents the effect of oxygen, nitrogen, and carbon concentration on the microstructure and properties of titanium foams produced with a powder metallurgy process. Oxygen and nitrogen reduce the ductility and increase the compression yield strength of CpTi foams. The effect of nitrogen appears to be similar to the effect of oxygen, a trend different from the ones reported in the literature for dense titanium in tension, where the effect of nitrogen is recognized to be significantly more important than the effect of oxygen. For carbon, the levels investigated were above the room temperature solubility limit of carbon in \u3b1-Ti and titanium carbides were observed in the microstructure. The volume fraction of carbides observed in the microstructure increased with carbon content. The effect of the carbides on the compression properties and ductility of the titanium foams is, however, small compared to the effect of oxygen and nitrogen. \ua9 Crown Copyright, Published by the Materials Research Society 2013.Peer reviewed: YesNRC publication: Ye

Initial Evaluation of Bone Ingrowth into a Novel Porous Titanium Coating

Porous metals (sintered beads and meshes) have been used for many years for different orthopedic applications. Metal foams have been recently developed. These foams have the advantage of being more porous than the traditional coatings. Their high porosity provides more space for bone ingrowth and mechanical interlocking and presents more surface for implant-bone contact. The objective of this study was to evaluate in vivo bone ingrowth into Ti implants covered with a novel Ti foam coating. This foam contains 50% in volume of interconnected pores and a higher surface area compared to dense Ti. Both coated implants and dense Ti controls were placed transcortically in the rat tibia. The animals were sacrificed at 2 weeks after implantation, and the amount of bone in the implants was determined using backscattered electron imaging and X-ray microtomography. Already at this time interval, the pores within the Ti foam showed 97.7% bone filling, and the bone-implant contact area was significantly increased compared to dense Ti controls. These initial results indicate that this novel Ti foam is biocompatible, has the capacity to sustain bone formation, and can potentially improve osseointegration.Peer reviewed: YesNRC publication: Ye

Determination of bulk and surface contributions to the pressure drop in metallic foams

Peer reviewed: YesNRC publication: Ye