Passive Corrosion Behavior of Alloy 22

Alloy 22 (N06022) was designed to stand the most aggressive industrial applications, including both reducing and oxidizing acids. Even in the most aggressive environments, if the temperature is lower than 150 F (66 C) Alloy 22 would remain in the passive state having particularly low corrosion rates. In multi-ionic solutions that may simulate the behavior of concentrated ground water, even at near boiling temperatures, the corrosion rate of Alloy 22 is only a few nanometers per year because the alloy is in the complete passive state. The corrosion rate of passive Alloy 22 decreases as the time increases. Immersion corrosion testing also show that the newer generation of Ni-Cr-Mo alloys may offer a better corrosion resistance than Alloy 22 only in some highly aggressive conditions such as in hot acids

Respuesta de hipersensibilidad retardada en pacientes candidatos a artroplastia de cadera

Se estudiaron 100 pacientes escogidos de manera aleatoria de entre los candidatos a artroplastia de cadera (47 por fractura subcapital de fémur Garden IV, y 53 por coxartrosis). En el momento del ingresos se determinaron en sangre niveles de albúmina, proteínas totales y hemoglobina; y se midió la respuesta de hipersensibilidad retardada mediante la inoculación de siete antígenos de memoria con un aplicador Multitest® (Mérieux). La lectura de la reacción de induración se realizó a las 48 horas. Los pacientes fueron clasificados en: normoérgicos (+) a dos o más antígenos) y anérgicos (una o ninguna respuesta (+). La población normoérgica representó el 61% de los pacientes, con una edad 12,5 años menor que la población anérgica (p<0,001). Los pacientes normoérgicos presentaron cifras significativamente más altas de hemoglobina (p<0,001), proteínas totales (p<0,05) y albúmina (p<0,001). La situación de anergia fue más frecuente en el grupo de mujeres (29/57) frente al de hombres (10/43; p<0,001), y en el grupo de fracturas subcapitales (31/47) que en el de coxartrosis (8/53) (p<0,001). No se hallaron relaciones estadísticamente significativas entre los distintos parámetros estudiados y la aparición de infección en el postoperatorio. Las diferencias aparecidas reflejan alteraciones en la respuesta inmunológica que, sin embargo, no resultan pronósticas frente a la aparición de infección en nuestra serie.One hundred candidates for hip arthroplasty were chosen at random (47 Garden IV femoral neck fractures, and 53 osteoarthrosis). Before surgery, serum albumin, total proteins and haemoglobin were determined in peripheral blood. All patients were skin tested with seven memory antigens (Multitest®, Mérieux) in order to measure the delayed hypersensitivity response. The diameter of the resulting induration was measured 48 hours after injection. Patients were classified as reactive if they responded to one antigen or showed no response. Reactive patients supposed 61% of total, and anergic patients were 12,5 years older (p<0,001). Levels of haemoglobin (p<0,001), total proteins (p<0,05) and albumin (p<0,001) were higher in reactive patients. Anergy was more frequent in women (29/57) than in men (10/43; p<0,001), and in fractures (31/47) than in osteoarthrosis (8/53) (p<0,001). No association between the variables studied and postoperative infection was found. These differences show immunologic alterations. However, they have no prognostic value for postoperative infection in hip arthroplasty patients

The osteoporosis treatment gap in patients at risk of fracture in European primary care : a multi-country cross-sectional observational study

Summary This study in 8 countries across Europe found that about 75% of elderly women seen in primary care who were at high risk of osteoporosis-related fractures were not receiving appropriate medication. Lack of osteoporosis diagnosis appeared to be an important contributing factor. Introduction Treatment rates in osteoporosis are documented to be low. We wished to assess the osteoporosis treatment gap in women ≥ 70 years in routine primary care across Europe. Methods This cross-sectional observational study in 8 European countries collected data from women 70 years or older visiting their general practitioner. The primary outcome was treatment gap: the proportion who were not receiving any osteoporosis medication among those at increased risk of fragility fracture (using history of fracture, 10-year probability of fracture above country-specific Fracture Risk Assessment Tool [FRAX] thresholds, T-score ≤ − 2.5). Results Median 10-year probability of fracture (without bone mineral density [BMD]) for the 3798 enrolled patients was 7.2% (hip) and 16.6% (major osteoporotic). Overall, 2077 women (55%) met one or more definitions for increased risk of fragility fracture: 1200 had a prior fracture, 1814 exceeded the FRAX threshold, and 318 had a T-score ≤ − 2.5 (only 944 received a dual-energy x-ray absorptiometry [DXA] scan). In those at increased fracture risk, the median 10-year probability of hip and major osteoporotic fracture was 11.2% and 22.8%, vs 4.1% and 11.5% in those deemed not at risk. An osteoporosis diagnosis was recorded in 804 patients (21.2%); most (79.7%) of these were at increased fracture risk. The treatment gap was 74.6%, varying from 53% in Ireland to 91% in Germany. Patients with an osteoporosis diagnosis were found to have a lower treatment gap than those without a diagnosis, with an absolute reduction of 63%. Conclusions There is a large treatment gap in women aged ≥ 70 years at increased risk of fragility fracture in routine primary care across Europe. The gap appears to be related to a low rate of osteoporosis diagnosis

Probing the phase diagram of CeRu_2Ge_2 by thermopower at high pressure

The temperature dependence of the thermoelectric power, S(T), and the electrical resistivity of the magnetically ordered CeRu_2Ge_2 (T_N=8.55 K and T_C=7.40 K) were measured for pressures p < 16 GPa in the temperature range 1.2 K < T < 300 K. Long-range magnetic order is suppressed at a p_c of approximately 6.4 GPa. Pressure drives S(T) through a sequence of temperature dependences, ranging from a behaviour characteristic for magnetically ordered heavy fermion compounds to a typical behaviour of intermediate-valent systems. At intermediate pressures a large positive maximum develops above 10 K in S(T). Its origin is attributed to the Kondo effect and its position is assumed to reflect the Kondo temperature T_K. The pressure dependence of T_K is discussed in a revised and extended (T,p) phase diagram of CeRu_2Ge_2.Comment: 7 pages, 6 figure

A nonlinear model for AC induced corrosion

The modeling of corrosion poses particular difficulties. The understanding of corrosion as an electrochemical process has led to simple capacitive-resistive models that take into account the resistance of the electrolytic cell and the capacitive effect of the surface potential at the interface between conductors and the electrolyte. In some models nonlinear conduction effects have been added to account for more complex observed behavior. While these models are sufficient to describe the behavior in systems with cathodic protection, the behavior in the presence of induced AC currents from power lines and from RF sources cannot be accounted for and are insufficient to describe the effects observed in the field. Field observations have shown that a rectifying effect exists that affects the cathodic protection potential and this effect is responsible for corrosion in the presence of AC currents. The rectifying effects of the metal-corrosion interface are totally missing from current models. This work proposes a nonlinear model based on finite element analysis that takes into account the nonlinear behavior of the metal-oxide interface and promises to improve modeling by including the rectification effects at the interface

Phase diagram of heavy fermion systems

The Meccano of heavy fermion systems is shown on different cases going from anomalous monochalcogenides to cerium intermetallic compounds with special focus on the ideal case of the CeRu2Si2 series. Discussion is made in the frame of the interplay between valence, electronic structure (Fermi surface), and magnetism. The nice tools given by the temperature, the pressure, and the magnetic field allow to explore different ground states as well as the slow downhill ''race'' before reaching a Fermi liquid finish line at very low temperature. Experimentally, the Gr"uneisen parameter i.e. the ratio of the thermal expansion by the specific heat is a coloured magic number; its temperature, pressure, and magnetic field dependence is a deep disclosure of competing hierarchies and the conversion of this adaptive matter to external responses.Comment: submitted ICM200

Distribution of Breeding Shorebirds on the Arctic Coastal Plain of Alaska

Available information on the distribution of breeding shorebirds across the Arctic Coastal Plain of Alaska is dated, fragmented, and limited in scope. Herein, we describe the distribution of 19 shorebird species from data gathered at 407 study plots between 1998 and 2004. This information was collected using a single-visit rapid area search technique during territory establishment and early incubation periods, a time when social displays and vocalizations make the birds highly detectable. We describe the presence or absence of each species, as well as overall numbers of species, providing a regional perspective on shorebird distribution. We compare and contrast our shorebird distribution maps to those of prior studies and describe prominent patterns of shorebird distribution. Our examination of how shorebird distribution and numbers of species varied both latitudinally and longitudinally across the Arctic Coastal Plain of Alaska indicated that most shorebird species occur more frequently in the Beaufort Coastal Plain ecoregion (i.e., closer to the coast) than in the Brooks Foothills ecoregion (i.e., farther inland). Furthermore, the occurrence of several species indicated substantial longitudinal directionality. Species richness at surveyed sites was highest in the western portion of the Beaufort Coastal Plain ecoregion. The broad-scale distribution information we present here is valuable for evaluating potential effects of human development and climate change on Arctic-breeding shorebird populations.Les renseignements qui existent en matière de répartition des oiseaux de rivage en reproduction sur la plaine côtière de l’Arctique en Alaska sont anciens, fragmentés et restreints. Ici, nous décrivons la répartition de 19 espèces d’oiseaux de rivage à partir de données recueillies à 407 lieux de recherche entre 1998 et 2004. Cette information a été recueillie grâce à une technique de recherche consistant en une seule visite rapide durant les périodes d’établissement du territoire et de début d’incubation, périodes pendant lesquelles les comportements sociaux et les vocalisations permettent de bien repérer les oiseaux. Nous décrivons la présence ou l’absence de chaque espèce, de même que le nombre général d’espèces, ce qui procure une perspective régionale de la répartition des oiseaux de rivage. Nous comparons et contrastons nos cartes de répartition des oiseaux de rivage à celles d’études antérieures, en plus de décrire les tendances les plus marquées en matière de répartition des oiseaux de rivage. Notre examen de la variation latitudinale et longitudinale en matière de répartition et de nombre d’espèces d’oiseaux de rivage à l’échelle de la plaine côtière arctique de l’Alaska nous a permis de constater que la plupart des espèces d’oiseaux de rivage se manifestaient plus souvent dans la région écologique de la plaine côtière de Beaufort (c’est-à-dire plus proche de la côte) que dans la région écologique des contreforts de Brooks (c’est-à-dire plus à l’intérieur des terres). Par ailleurs, l’occurrence de plusieurs espèces indiquait une directionalité longitudinale substantielle. La richesse des espèces aux sites à l’étude était à son meilleur dans la partie ouest de la région écologique de la plaine côtière de Beaufort. Les renseignements sur la répartition à grande échelle que nous présentons ici jouent un rôle dans l’évaluation des effets éventuels des travaux de mise en valeur par l’être humain et du changement climatique sur les populations d’oiseaux de rivage en reproduction de l’Arctique

Modeling the Effects of Crevice Former, Particulates , and the Evolving Surface Profile in Crevice Corrosion

Crevice corrosion may initiate in confined regions due to transport limitations, followed by an accumulation of a highly corrosive chemistry, capable of dissolving the metal. The metal and the crevice former surface roughness, the presence of particulates under the crevice former and the accumulation of solid corrosion products at the corroding site would significantly affect the current and potential distribution at the anode by increasing the ohmic potential drop. Most crevice corrosion models focus on a smooth walled crevice of uniform gap and do not account for the changing profile after crevice corrosion has been initiated. In this work we analyze the crevice (anodic) region and apply current and potential distribution models to examine the effects of the perturbed surface topography. The analysis focuses on three related issues: (1) the effects of surface roughness of the metal and the crevice former, (2) the effects of particulates under the crevice former, and (3) the evolution of the crevice profile with corrosion product accumulation at the active, anodic region