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Though not often discussed explicitly in literature, sample handling and preparation for advanced characterization techniques is a significant challenge for radiological materials. In this contribution, a detailed description is given of method development associated with characterization of highly radioactive and, in some cases, hygroscopic oxides of technetium. Details are given on developed protocols, fixtures, and tooling designed for x-ray and neutron diffraction, x-ray absorption, Raman spectroscopy, magic angle spinning nuclear magnetic resonance, and electron paramagnetic resonance. In some cases, multiple iterations of improved sample holder design are described. Lessons learned in handling Tc compounds for these and similar characterization methods are discussed.
Non-invasive survey in the Stonehenge ‘Triangle’, Amesbury, Wiltshire, has highlighted a number of features that have a significant bearing on the interpretation of the site. Geophysical anomalies may signal the position of buried stones adding to the possibility of former stone arrangements, while laser scanning has provided detail on the manner in which the stones have been dressed; some subsequently carved with axe and dagger symbols. The probability that a lintelled bluestone trilithon formed an entrance in the north-east is signposted. This work has added detail that allows discussion on the question of whether the sarsen circle was a completed structure, although it is by no means conclusive in this respect. Instead, it is suggested that it was built as a façade, with other parts of the circuit added and with an entrance in the south.
Despite being one of the most intensively explored prehistoric monuments in western Europe, Stonehenge continues to hold surprises. The principal elements of the complex are well known: the outer bank and ditch, the sarsen circle capped by lintels, the smaller bluestone settings and the massive central trilithons. They represent the final phase of Stonehenge, the end product of a complicated sequence that is steadily being refined (most recently in Darvill et al. ‘Stonehenge remodelled’, Antiquity 86 (2012): 1021–40). Yet Stonehenge in its present form is incomplete—some of the expected stones are missing—and it has sometimes been suggested that it was never complete; that the sarsen circle, for example, was only ever finished on the north-eastern side, facing the main approach along the Avenue. A chance appearance of parchmarks, however, provides more evidence.
Integrated non-invasive survey in the Stonehenge ‘triangle’, Amesbury, Wiltshire, has highlighted a number of features that have a significant bearing on the interpretation of the site. Among them are periglacial and natural topographical structures, including a chalk mound that may have influenced site development. Some geophysical anomalies are similar to the post-holes in the car park of known Mesolithic date, while others beneath the barrows to the west may point to activity contemporary with Stonehenge itself. Evidence that the ‘North Barrow’ may be earlier in the accepted sequence is presented and the difference between the eastern and western parts of the enclosure ditch highlighted, while new data relating to the Y and Z Holes and to the presence of internal banks that mirror their respective circuits is also outlined.
Gyps vulture populations across the Indian subcontinent collapsed in the 1990s and continue to decline. Repeated population surveys showed that the rate of decline was so rapid that elevated mortality of adult birds must be a key demographic mechanism. Post mortem examination showed that the majority of dead vultures had visceral gout, due to kidney damage. The realisation that diclofenac, a non-steroidal anti-inflammatory drug potentially nephrotoxic to birds, had become a widely used veterinary medicine led to the identification of diclofenac poisoning as the cause of the decline. Surveys of diclofenac contamination of domestic ungulate carcasses, combined with vulture population modelling, show that the level of contamination is sufficient for it to be the sole cause of the decline. Testing on vultures of meloxicam, an alternative NSAID for livestock treatment, showed that it did not harm them at concentrations likely to be encountered by wild birds and would be a safe replacement for diclofenac. The manufacture of diclofenac for veterinary use has been banned, but its sale has not. Consequently, it may be some years before diclofenac is removed from the vultures' food supply. In the meantime, captive populations of three vulture species have been established to provide sources of birds for future reintroduction programmes.
‘The huts are now roofless, the fires of the hearths quenched for ever, the fortifications levelled; yet these ruins have out-lasted the erections of more civilized times, and they still remain to tell us something of the busy population who hunted, tended flocks, tilled the ground, and quarrelled and fought, at a very distant period (in the valley of the Breamish)’. George Tate (1863, 302)
This paper describes the results of the South East Cheviots Project undertaken by the former Royal Commission on the Historical Monuments of England (RCHME; now part of English Heritage) during the 1980s. An area of 66 square kilometres was analytically recorded, ranging from the Breamish Valley in the north to Alnham in the south and from Brandon in the east to Schill Moor in the west. The project recorded with metrical accuracy all forms of cultivation remains, field systems, and settlements of all periods (only the prehistoric evidence will be reviewed in this paper). This landscape approach has led to a greater understanding of settlement histories in these remarkably well-preserved uplands. Recent excavations undertaken by the Northumberland Archaeological Group (NAG) and Durham University, under the auspices of the Northumberland National Park Authority (NNPA), have helped to clarify and contextualise further aspects of the chronology of settlement and landscape change recorded by the SECP.
Nanostructured anodic alumina membranes have been utilized as high-temperature stable supports for 150 nm thick continuous palladium films. The palladium has been deposited by vacuum evaporation onto the rotating substrate. The thermal stability of the resulting compound membranes has been demonstrated for temperatures up to 700ºC under a reducing atmosphere. Hydrogen permeation has been measured up to 280ºC, where the permeability has a value of 2.5·10-7 mol m-2 s-1 Pa-1. At the same time the selectivity factor over carbon dioxide is at least 33.
Recesses in the entrance passages of British hillforts have been found throughout the 20th century, mainly on sites in north Wales and the Welsh Marches, though some occur elsewhere. From their first discovery they have been assumed to be ‘guard rooms’ or ‘guard chambers’ and no discussion about their function has taken place. This paper is, an attempt to start such a discussion. The idea that these recesses were necessarily of defensive use is challenged and an alternative ritual or symbolic ‘explanation’ is suggested.
Ammonia borane (NH3BH3) is a molecular solid with a high volumetric and gravimetric density of hydrogen. We report room temperature structural data which shows how the freely rotating NH3 and BH3 groups allow a N-H…H-B dihydrogen bond in which hydrogen atoms on adjacent molecules are separated by only 1.90Å. The initial decomposition of ammonia borane at 80-100°C into (NH2BH2)n and H2 has been studied by in-situ nmr spectroscopy and kinetic studies using isotopic substitution. The reaction proceeds by a bimolecular pathway involving a [NH3BH2NH3]+BH4− intermediate with an activation energy of 136kJmol−1.
In their article ‘Romancing the stones: towards a virtual and elemental Avebury’ (Archaeological dialogues 1998, 5.2, 143–64), Joshua Pollard and Mark Gillings argued that traditional cartography no longer suffices to understand sites like Avebury. In the absence of excavation, new technological possibilities like Virtual Reality and GIS were according to them more than electronic gadgets but genuine alternatives to the usual maps and plans. Mark Bowden takes issues with what he perceives to be exaggerated criticisms of traditional archaeological survey techniques. In particular, he suggests that, far from being ‘sterile’ as Pollard and Gillings state, conventional survey plans are imbued with meaning, and are essential tools of analysis and interpretation. Users of archaeological earthwork plans must study them carefully and be critically aware to get the greatest benefit from them. Innovative new approaches must be pursued vigorously, but well-tested traditional techniques which still have value should not be abandoned lightly, Bowden argues. Pollard and Gillings reply to this challenging criticism.