Mössbauer spectroscopy study of the aging and tempering of high nitrogen quenched Fe-N alloys: Kinetics of formation of Fe16N2 nitride by interstitial ordering in martensite

The distribution of nitrogen atoms in austenite and during the different stages of aging and tempering of martensite is studied by Mössbauer spectroscopy, X-ray diffraction, and transmission electron microscopy (TEM). Transmission Mössbauer spectroscopy (TMS) and conversion electron Mössbauer spectroscopy (CEMS) are used for studying the austenite phase where the distribution of nitrogen atoms is found to depend on the nitriding method, gas nitriding in our case, or ion implantation. Conversion electron Mössbauer spectroscopy, which concerns a depth predominantly less than 200 nm, reveals a nitrogen atom distribution different from that found in the bulk by TMS. The identification and kinetics of the stages of aging and tempering of martensite are followed by TMS measurements, and the phase characterization is confirmed by X-ray diffraction and TEM. The major stages are the early ordering of nitrogen atoms, which leads to small coherent precipitates of α-Fe₁₆N₂; the passage by thickening to semicoherent precipitates of α-Fe₁₆N₂; the dissolution of α-Fe₁₆N₂ with the concomitant formation of /gg’-Fe₄N; and the decomposition of retained austenite by tempering. The three first stages correspond to activation energies of 95, 126, and 94 kJ/mole, respectively, consistent with the nitrogen diffusion for the first and third stages and the dislocation pipe diffusion of iron for the second.     

Survey of pathology associated with the use of video display terminals]

BACKGROUND: Bacterial vaginosis in pregnant women is an established risk factor for premature labor, rupture of membranes, and preterm delivery, but information on its natural history during pregnancy is limited. METHOD AND MATERIAL: In this study, 635 pregnant women at less than 35 weeks' gestation were screened for bacterial vaginosis. RESULTS: The prevalence of bacterial vaginosis, as assessed by Gram stain examination of vaginal smears, was 19.7% (125/635). Ninety-two women were retested 4 to 8 weeks later, and bacterial vaginosis persisted in 51.1% (47/92). The incidence of preterm delivery was significantly increased in women with bacterial vaginosis at enrollment (RR 3.1, 95% CI: 1.8-5.4). However, the risk of prematurity was similar in women with or without a persistence of bacterial vaginosis. CONCLUSION: These results suggest that the diagnosis of bacterial vaginosis at any point during pregnancy is associated with an increased risk of perinatal complications in spite of spontaneous recovery in subsequent examinations.     

Warm tub bath during labor. A study of 1385 women with prelabor rupture of the membranes after 34 weeks of gestation

BACKGROUND: To evaluate the influence of a bath on infectious morbidity in mothers and neonates in women with prelabor rupture of the membranes after 34 weeks of gestation. METHODS: A nonrandomized study of 1385 healthy women. During the first stage of labor 538 women wanted a bath while 847 did not. The women awaited spontaneous contractions up to 24 or 72 hours after the membranes had ruptured before labor was induced with oxytocin. Digital examinations of the cervix were avoided until onset of active labor or until the time induction was planned. For statistical analysis Fisher's exact test was used. RESULTS: Chorioamnionitis during labor occurred in 1.1% of the women in the bath group and in 0.2% in the reference group (p = 0.06). Postpartum endometritis was found in three cases both in the bath group (0.6%) and in the reference group (0.4%) (p = 0.68). The frequency of neonates receiving antibiotics was 3.7% and 4.8% respectively (p = 0.43). CONCLUSION: A tub bath did not increase the risk of maternal or neonatal infection after premature rupture of the membranes and prolonged latency.     

Multivariate Study on Phenanthrene Sorption in Soils

Batch tests and different statistical tools of data analysis were used to re-evaluate the overall effect of soil characteristics and liquid phase composition on the extent of phenanthrene adsorption in complex soil-water systems. The linear isotherm models was capable of adequately describing the equilibrium data under extremely varying conditions of soil type, environmental conditions (pH, temperature, ionic strength) and amendments (surfactant, oil, dispersing agent, glucose). Consistent with existing mechanistic models, the multivariate approach also identified the organic carbon content (foc) of soil as the key parameter controlling the phenanthrene adsorption constant (Kd) in nonamended systems (Koc was 17,700 mL/g). From studying the effect of the amendments, two interactions (surfactant-pH and surfactant-oil) and two main effects (surfactant and oil) have been detected. An empirical linear model of Kd as a function of foc, pH, oil content of soil, and surfactant dose was developed for the range of conditions studied. The proposed model and modeling approach can be adapted to other types of contaminants or variables for specific natural and engineered systems.     

Fetal growth and coronary heart disease in south India

BACKGROUND: Coronary heart disease is predicted to become the commonest cause of death in india within 15 years People from India living overseas already have high rates of the disease that are not explained by known coronary risk factors. Small size at birth is a newly described risk factor for coronary heart disease, but associations between size at birth and the disease have not been examined in India. METHODS: We studied 517 men and women who were born between 1934 and 1954 in a mission hospital in Mysore, South India, and who still lived near to the hospital. We related the prevalence of coronary heart disease, defined by standard criteria, to their birth size. FINDINGS: 25 (9%) men and 27 (11%) women had coronary heart disease. Low birthweight, short birth length, and small head circumference at birth were associated with a raised prevalence of the disease. Prevalence fell from 11% in people whose birthweights were 5.5 lb (2.5 kg) or less to 3% in those whose birthweights were more than 7 lb (3.1 kg), p for trend = 0.09. The trends were stronger and statistically significant among people aged 45 years and over (p = 0.03 for birthweight, 0.04 for length, and 0.02 for head circumference). High rates of disease were also found in those whose mothers had a low body weight during pregnancy. The highest prevalence of the disease (20%) was in people who weighted 5.5 lb (2.5 kg) or less at birth and whose mothers weighted less than 100 lb (45 kg) in pregnancy. These associations were largely independent of known coronary risk factors. INTERPRETATION: In India, as in the UK, coronary heart disease is associated with small size at birth, suggesting that its pathogenesis is influenced by events in utero. The association with low maternal bodyweight is further evidence that the disease originates through fetal undernutrition. Prevention of the rising epidemic of the disease in India may require improvements in the nutrition and health of young women.     

The voices of registered play therapists as supervisors.

This study examined the background, perceived training needs, and issues of Registered Play Therapist Supervisors (n = 305) and their supervisees. Supervisors completed a four-part survey regarding demographics, supervisor and supervisee issues, and perceptions of training needs for supervisors of play therapists. Important findings are the lack of training in and possible understanding of clinical supervision, the lack of perceived need for supervision of supervision, and the absence of countertransference as an important issue for supervisors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Coupling binder hydration,temperature and compressive strength development of underground cemented paste backfill at early ages

Cemented paste backfill (CPB) is an engineered mixture containing up to 60% solid tailings, and 3–7% binder (often) and water. CBP is used in backfilling underground mine voids. It receives great interest as one of the most commonly used ways in mine backfilling around the world. The usage of CPB greatly contributes to the disposal of mining tailings waste from the surface, increasing working place stability to extract more minerals safely. The key parameter for the design of CPB structure is its strength; namely, unconfined compressive strength (UCS). Knowing the time at which the CPB reaches its reasonable strength is very important for reducing the mining cycle and ensuring the safety of mine workers. As a cemented material, CPB strength is time and temperature dependent, and a function of the degree of hydration. The objective of this paper is to develop a numerical model for predicting the UCS of undrained CPB. Strength development is coupled with temperature and degree of hydration. For validation purposes, the predicted UCS will be compared with three groups of experimental results. The results show a good agreement between the predicted and measured values, and a new formula is suggested for including the effect of temperature into the UCS of CPB.     

New accelerated charge methods using early destratification applied on flooded lead acid batteries

A traditional charge process for flooded lead acid batteries (FLABs) lasts generally from 8 to 14 h. Nowadays, many applications of FLABs require reduction of the charge duration, for instance, a 4 h-charge for FLABs in grid energy storage or 1 h-charge for FLABs in electric buses. These are called accelerated charge and fast charge. Such reductions of charge time imply the use of a new charge process. One way to reduce the charge duration is to perform an early destratification step without waiting for the end of charge. The new charge method proposed in this paper (early destratification method - ED) focuses on the reduction of the charge time for FLABs using early destratification, which is performed and controlled using charge acceptance measurement during the charge. Laboratory experiments presented here aim first to develop charge acceptance measurements followed by an ED charge method compared to an IUi traditional charge process.     

Mechanical response of a mine composite material to extreme heat

The use of cemented paste backfills (CPB, a mine composite tailings material) in underground mining is currently increasing in importance globally. However, despite the tremendous progress made in understanding the factors affecting the performance of CPB, little attention has been devoted to the impact of high temperatures on its mechanical properties. This article presents the results of experimental investigations into the mechanical responses of CPB when subjected to high thermal loads. Samples made with silicate and pure cement or a mix of 50/50 cement and slag or fly ash were heated at 100, 200, 400 and 600°C, and the unconfined compressive strength, tensile strength, modulus of elasticity, stress–strain behaviour and microstructure evaluated by laboratory tests. The results show that high temperatures have a significant influence on the mechanical properties of CPB, which should be taken into account when determining an appropriate mix for the binder.