Hydrogen Embrittlement of Automotive Ultra-High-Strength Steels: Mechanism and Minimisation

Automotive manufacturers are increasingly using ultra-high-strength steels in vehicle components to facilitate mass reduction via downgauging. Unfortunately, as the strength of steels increases, so does susceptibility to ‘hydrogen embrittlement’, a process in which ductility is significantly impaired by ingress of hydrogen. Mechanisms and environmental conditions by which this degradation occurs are not fully understood. In this work, 2 fully-ferritic, 2 fully-martensitic boron, and 2 ferrite-martensite dual-phase, ultra-high-strength steels, were assessed for susceptibility to hydrogen embrittlement via 3 key characteristics: firstly, with particular regard to hydrogen evolution under corrosion conditions, through well-established open circuit potential and potentiodynamic polarisation experiments. Exacerbation of hydrogen evolution through galvanic corrosion of a zinc coating was assessed by scanning vibrating electrode technique (SVET), and an attempt made to quantify increased risk of hydrogen evolution during crevice corrosion through a novel time-lapse photography experiment. Secondly, hydrogen diffusivity was assessed via permeation experiments. Finally, degradation in mechanical properties due to diffusing hydrogen was evaluated through slow strain rate tests (SSRT), whereby susceptibility to embrittlement was equated to reduction in ductility of hydrogen-charged test specimens. The fully-ferritic steels showed the greatest resistance to mechanical degradation, attributed to micro-alloy nano-precipitates within their microstructure acting as ‘traps’, leading to lower diffusivity compared to dual-phase steels of equivalent strength. Indeed, lower diffusivity showed a strong correlation with lower levels of embrittlement across all steels. 1000 MPa dual-phase steel showed the greatest degradation in mechanical properties, with fully-martensitic boron steels also found to be particularly susceptible. 1000 MPa dual-phase steel also showed the largest increase in hydrogen evolution reaction in response to polarisation, thought to result from the inherent potential difference between ferrite and martensite phases. Galvanic corrosion of a damaged zinc coating was found to polarise the exposed steel substrate, triggering sufficient hydrogen evolution to reach critical concentrations for embrittlement

Studies of Himalayan pheasants in Nepal with reference to their conservation

The Blood Pheasant Ithaginis cruentus, Satyr Tragopan Tragopan Satyra, Koklass Pheasant Pucrasia macrolopha, and Himalayan Monal Lophophurus impeyanus, were studied for seven months in the South Annapurna region, North of Pokhara, Nepal, in 1979 and 1980. Study was concentrated in the Pipar area, between 3000m and 4000m altitude, where population densities were estimated by counting the numbers of calling males (Tragopan and Koklass), and by Direct Counts of birds (Blood Pheasant and Monal). Population densities ranged from 2.5 t o 4.8 pairs per km for the first three species, and although a slight decline was noted in the 1980 densities, the populations were considered to be quite healthy. An assessment of the habit at preferences of each species was made, which showed that these overlapped considerably. Diet and feeding behaviour were studied and compared with observations made by previous workers. All species showed overlapping food preferences, but these were different in detail. Aspects of the behaviour of each species were studied, including protective behaviour, daily activities, breeding behaviour, and vocalizations. The latter were tape recorded, analysed sonagraphically, and most are described here in detail. The male Tragopan and Koklass were observed to make dawn challenge calls; the function of these and the calls of the other species are discussed. Observations made on breeding biology and territoriality were compared with those in the literature and are also discussed. A fifth species, the Cheer Pheasant Catreus wallichii, was sought for in the Athhazar Parbat region, North-west of Pokhara, Nepal. A small population was located in 1980, and observations were made on these for four days in May. The Cheer is included in the relevant sections along with the other four species. A study of human influence on all the species was undertaken, which included the effects of livestock herds, hunting, burning, and forest clearance. In the South Anna puma region, pressure on the pheasants was not considered to be too great at present, but it is thought likely to increase in the near future. The status of the study species is considered and recommendations for their conservationare made. These include the setting up of a reserve, regulations for hunting, forest production and pastoralism, and recommendations for education and research

Subgrade geology beneath railways in Manchester

It is not sufficient to identify fine-grained soils, only, as locations for potential subgrade problems as could be done using a traditional 2D geological map. More information is required about the geological structure, lithological variability, mineralogy, moisture content and geotechnical properties of the soil, much of which can be supplied by modern 3D geospatial databases. These databases can be interrogated at key depths to show the wide variability of geological materials and conditions beneath the ground surface. Geological outcrop and thickness of bedrock an superficial deposits (soils), plus the permeability and water table level are predicted from the Manchester geospatial model that is based on 6500 borehole records. Geological sections along railway routes are modelled and the locations of problem soils such as alluvium, till and glaciolacustrine deposits at outcrop and shallow subcrop are identified. Spatial attribution of geotechnical data and simple methods to recast sections in engineering geological terms are demonstrated

The role of sex and body weight on the metabolic effects of high-fat diet in C57BL/6N mice.

BACKGROUND: Metabolic disorders are commonly investigated using knockout and transgenic mouse models on the C57BL/6N genetic background due to its genetic susceptibility to the deleterious metabolic effects of high-fat diet (HFD). There is growing awareness of the need to consider sex in disease progression, but limited attention has been paid to sexual dimorphism in mouse models and its impact in metabolic phenotypes. We assessed the effect of HFD and the impact of sex on metabolic variables in this strain. METHODS: We generated a reference data set encompassing glucose tolerance, body composition and plasma chemistry data from 586 C57BL/6N mice fed a standard chow and 733 fed a HFD collected as part of a high-throughput phenotyping pipeline. Linear mixed model regression analysis was used in a dual analysis to assess the effect of HFD as an absolute change in phenotype, but also as a relative change accounting for the potential confounding effect of body weight. RESULTS: HFD had a significant impact on all variables tested with an average absolute effect size of 29%. For the majority of variables (78%), the treatment effect was modified by sex and this was dominated by male-specific or a male stronger effect. On average, there was a 13.2% difference in the effect size between the male and female mice for sexually dimorphic variables. HFD led to a significant body weight phenotype (24% increase), which acts as a confounding effect on the other analysed variables. For 79% of the variables, body weight was found to be a significant source of variation, but even after accounting for this confounding effect, similar HFD-induced phenotypic changes were found to when not accounting for weight. CONCLUSION: HFD and sex are powerful modifiers of metabolic parameters in C57BL/6N mice. We also demonstrate the value of considering body size as a covariate to obtain a richer understanding of metabolic phenotypes

Italy's 'Zampa' Law: Increasing Protection for Unaccompanied Children

Italy has enacted comprehensive legislation to protect the rights of unaccompanied children arriving in Italy. While flaws remain in Italy’s treatment of these particularly vulnerable migrants, the country’s protection-focused approach sets an example to other countries. This short article briefly analyses the new legislation and comments on its significance

La ley “Zampa” en Italia: aumentar la protección para los menores no acompañados

Italia promulgó leyes integrales para proteger los derechos de los menores no acompañados que llegan al país. Si bien se observan algunos defectos en el trato de Italia a estos migrantes particularmente vulnerables, su enfoque centrado en la protección sirve de ejemplo para otros países

The tailored suit : a reimagining of Can Themba's The Suit

This research report examines the period of 1950s Sophiatown and its socio-­‐cultural legacy pertaining to race and gender. Though the establishment of a cosmopolitan black identity was significant in its undermining of Nationalist Party segregationist ideology, the struggle for equality was predicated on a racial struggle that subsumed a gendered agenda. The work of Can Themba and Drum magazine, which have become mythologized in the contemporary South African imaginary, are interrogated with particular emphasis on one of Themba’s iconic pieces, The Suit. Through engagement with Themba’s text, this research report foregrounds the processes through which black women have been subjected to multiple, compounded subjugation. In response to the representations of black femininity in The Suit, the film component of this report, The Tailored Suit, privileges the black woman, Matilda’s, articulations. It thus functions to foreground the agency of marginalised subjects. In articulating from the periphery, the subjugated destabilise the hierarchical social structures that would subordinate and objectify them. By engaging the representations in The Suit, part of an iconic historic moment prefiguring the contemporary socio-­‐cultural milieu, the reimagining in The Tailored Suit offers a fragmented frame of reference, positing an alternative to a homogenising masculine discourse on history

Learning about astronomy : a case study exploring how grade 7 and 8 students experience sites of informal learning in South Africa

Abstract All students are able to learn something about astronomy when they participate in a school visit to a site of informal learning such as a science centre. I examined how children from four schools experienced presentations and participated in activities about astronomy during a two to four hour visit to either the Hartebeesthoek Radio Astronomy Observatory or the Johannesburg Planetarium in South Africa. The case study involved observing thirty-four 12- to 14-year-old students at the science centre and interviewing them about astronomy concepts including those based on personal meaning maps they drew prior to and after their visit. The data were analysed using a human constructivist framework to determine both what and how students learnt during their visit. Despite a lack of teacher involvement I show how students collectively and individually learnt about concepts in astronomy, which I categorised into a set of seven Big Ideas: gravity, stars and the Sun, size and scale, the Solar System, day and night, Moon phases and parabolic dishes. Collectively, there was an improvement in their knowledge of Big Ideas dealt with at the study sites, including gravity, stars, the Sun, size and scale, and parabolic dishes. The students showed little change in their knowledge of day and night or the phases of the Moon. Individually, all students learnt principally by incremental addition of knowledge, while some students also demonstrated greater knowledge restructuring. Students with the least prior knowledge added additional basic facts to their repertoire, while those with greater prior knowledge were able to reorganise their knowledge and achieve greater understanding. All students also showed that the affective domain (for example enjoyment and wonder) contributed to their learning by encouraging interest in astronomy. Some students demonstrated examples of conative learning in which their experiences prompted them to further action after their visit. While the visit changed the misconceptions of some students, it made little difference to others, and promoted misconceptions in a few. Methodological findings included the value of using personal meaning maps, the importance of using models during the interview process and observations of how students used language in their description of astronomical processes. The study suggests that students learn best from a range of activities clustered around a central theme, and that enjoyable activities appear to enhance learning. I recommend that the astronomy presented at the centres focus on a limited number of concepts in astronomy, and that presentations and activities be structured around those Big Ideas. Science centresshould provide teachers with guidelines for their visit. I also propose that activities aim to recall students’ prior knowledge and provide situational interest to encourage motivation in the topic of astronomy and the subject of science. Finally I suggest that science centres should combine cognitive learning with affective fun, as recommended by students participating in the study. Keywords Astronomy, Astronomy Education, Constructivism, Human Constructivism, Informal Learning, Museum, Planetarium, Science Centre

The influence of host genetics on erythrocytes and malaria infection: is there therapeutic potential?

As parasites, Plasmodium species depend upon their host for survival. During the blood stage of their life-cycle parasites invade and reside within erythrocytes, commandeering host proteins and resources towards their own ends, and dramatically transforming the host cell. Parasites aptly avoid immune detection by minimizing the exposure of parasite proteins and removing themselves from circulation through cytoadherence. Erythrocytic disorders brought on by host genetic mutations can interfere with one or more of these processes, thereby providing a measure of protection against malaria to the host. This review summarizes recent findings regarding the mechanistic aspects of this protection, as mediated through the parasites interaction with abnormal erythrocytes. These novel findings include the reliance of the parasite on the host enzyme ferrochelatase, and the discovery of basigin and CD55 as obligate erythrocyte receptors for parasite invasion. The elucidation of these naturally occurring malaria resistance mechanisms is increasing the understanding of the host-parasite interaction, and as discussed below, is providing new insights into the development of therapies to prevent this disease.We acknowledge funding support from the National Health and Medical Research Council (Grant APP605524, 490037 and 1047082), the Australian Research Council (Grant DP12010061), the National Collaborative Research Infrastructure Strategy of Australia and the Education investment fund from the Department of Innovation, Industry, Science and Research. PML is a recipient of an Australian Postgraduate award