ESC Publications - Cambridge Univesity
Not a member yet
4214 research outputs found
Sort by
Neutron irradiation and post-irradiation annealing of rutile (TiO2-x): effect on hydrogen incorporation and optical absorption
No full textNeutron irradiation and post-irradiation annealing under oxidising and reducing conditions have been used to investigate H incorporation in, and the optical properties of, reduced (TiO2−x ) rutile. Optical absorption in rutile is mainly due to a Ti3+ Ti4+ intervalence charge transfer effect. The main mechanism for H incorporation in rutile involves interstitial H not coupled to other defects, which has important implications for the rate of H diffusion, and possibly also on the electrical properties of rutile. Additional minor OH absorption bands in IR spectra indicate that a small amount of interstitial H is coupled to defects such as Ti3+ on the main octahedral site, and indicates that more than one H incorporation mechanism may operate. Concentration of oxygen vacancies has a controlling influence on the H affinity of rutile
The Nile on the move
No full textThe Nile, as a meandering river, has moved relative to habitation sites since antiquity, as attested in
historic documents. Geologists Katy Lutley and Juditl Bunbury combined maps and satellite
images with a walk-about in the Caio area to propose a map for its past movements.Their results
suggest that enviionmental change has been topical since the Old Kingdo
Glacial rapid variability in deep-water temperature and d18O from the Western Mediterranean Sea
No full textAbstract
Deep-water temperatures (DWTs) from the Western Mediterranean Sea are reconstructed for the last 50 ka based on the analysis of
Mg/Ca ratios in benthic foraminifera from core MD95-2043 collected in the Alboran Sea. The exceptionally high sedimentation rates of
this core and the robust chronology available allow discussion of the results in the context of the Dansgaard–Oeschger (D–O) rapid
climatic variability. The applicability of Mg/Ca thermometry in the Western Mediterranean Deep-Water mass (WMDW) is first tested by
the analysis of different benthic species in a collection of Mediterranean core tops. The results indicate the need of a readjustment of the
existing Cibicidoides spp. calibrations in order to reconstruct present Western Mediterranean DWT values (12.7 1C). Different
physiological effects in the Mg uptake between the C. pachydermus living in different regions could account for this offset in the
Mediterranean samples. Consequently, the obtained DWT record still has many uncertainties in absolute terms but trends provide
valuable information on past changes in WMDW conditions. The DWT record shows significant oscillations in relation to the D–O
cycles, colder values occurred during the time of D–O stadials and warmer ones during D–O interstadials. Surprisingly, the coldest
DWTs occurred during the time of Heinrich Event 4 (HE4) and not during the Last Glacial Maximum (LGM) when DWTs were mostly
warm. These and other particular features of the DWT reconstruction mimic changes in the vegetation from the Eastern Mediterranean
indicating the control of the Mediterranean climate on the DWT record. Paired analyses of Mg/Ca and d18Occ (calcite d18O) provide the
opportunity to reconstruct deep-water d18O (d18Odw) and past salinities and hence changes in past WMDW density. Due to the large
error associated with these calculations, they can only be discussed in terms of relative changes between different intervals. The results
suggest the dominance of a heavier water end member during glacial times and a lighter one during the early Holocene in relation to the
d18Odw conditions present today. Densest WMDW were formed during most of Marine Isotopic Stage (MIS) 2 and during the D–O
Stadials not associated with HEs, while lightest WMDW dominated during D–O Interstadials. The d18Odw record shows a D–O
variability pattern likely controlled by changes in the composition and intensity of the local run-off and also to changes in the d18Ow
signal of the Atlantic inflow. Changes in the residence time of the Mediterranean waters, governed by the global sea level, are also
considered to exert an important role governing Mediterranean d18Ow and salinity, particularly during MIS 2. Overall, our results are
consistent with the formation of dense WMDW during D–O stadials and even denser during most of MIS 2
Elastic anomalies accompanying phase transitions in (Ca,Sr)TiO3 perovskites Part III: experimental investigation of polycrystalline samples
No full textImprinted textures on apatite: A guide to palaeoporosity and metamorphic recrystallization
No full textPetrology igneous metamorphic and volcanic studies; marian
Giant sharp and persistent converse magnetoelectric effects in multiferroic epitaxial heterostructures
No full textMagnetoelectric coupling1,2 between magnetic and electrical
properties presents valuable degrees of freedom for applications.
The two most promising scenarios are magnetic-field sensors3
that could replace low-temperature superconducting quantum
interference devices, and electric-write magnetic-read memory
devices that combine the best2 of ferroelectric and magnetic
random-access memory. The former scenario requires
magnetically induced continuous and reversible changes in
electrical polarization. These are commonly observed, but the
coupling constants thus obtained are invalid for data-storage
applications, where the more difficult to achieve4,5 and rarely
studied magnetic response to an electric field is required.
Here, we demonstrate electrically induced giant, sharp and
persistent magnetic changes (up to 2.3×10−7 sm−1) at a single
epitaxial interface in ferromagnetic 40 nm La0.67Sr0.33MnO3 films
on 0.5mm ferroelectric BaTiO3 substrates. X-ray diffraction
confirms strain coupling via ferroelastic non-180◦ BaTiO3
domains. Our findings are valid over a wide range of
temperatures including room temperature, and should inspire
further study with single epitaxial interfaces
Quantification of actinide α-radiation damage in minerals and ceramics
No full textThere are large amounts of heavy α-emitters in nuclear waste and nuclear materials inventories stored in various sites around the world1. These include plutonium and minor actinides such as americium and curium. In preparation for geological disposal there is consensus2 that actinides that have been separated from spent nuclear fuel should be immobilized within mineral-based ceramics rather than glass2-4 because of their superior aqueous durability and lower risk of accidental criticality. However, in the long term, the α-decay taking place in these ceramics will severely disrupt their crystalline structure2-4 and reduce their durability5,6. A fundamental property in predicting cumulative radiation damage is the number of atoms permanently displaced per α-decay. At present, this number is estimated to be 1,000-2,000 atoms/a in zircon4. Here we report nuclear magnetic resonance, spin-counting experiments that measure close to 5,000 atoms/a in radiation-damaged natural zircons. New radiological nuclear magnetic resonance measurements on highly radioactive, 239Pu zircon show damage similar to that caused by 238U and 232Th in mineral zircons at the same dose, indicating no significant effect of half-life or loading levels (dose rate). On the basis of these measurements, the initially crystalline structure of a 10 weight per cent 239 Pu zircon would be amorphous after only 1,400 years in a geological repository (desired immobilization timescales are of the order of 250,000 years). These measurements establish a basis for assessing the long-term structural durability of actinide-containing ceramics in terms of an atomistic understanding of the fundamental damage event
Mixing ventilation can reduce energy costs
No full textThe article provides information on a study on the potential of mixing ventilation in reducing energy costs in buildings such as theaters and schools. The study found that neither Manchester's Contact Theatre and the Garrick Theatre in Lichfield in England is operating according to the displacement-ventilation principle upon which they were designed. Hybrid mixing ventilation has an important impact on both the ventilation rate and the thermal comfort of the theatres
Development of integumentary structures in Rousettus amplexicaudatus (Mammalia : Chiroptera : Pteropodidae) during late-embryonic and fetal stages
No full textThe pattern of development of integumentary structures and associated tissues in the megachiropteran bat Rousettus amplexicaudatus is described on the basis of 18 specimens ranging in crown–rump length (CRL) from 8.5 to 44.4 mm. The ontogenetic sample encompasses specimens that correspond to stages 16 through 22 of the phyllostomid Carollia perspicillata (late-embryonic) as well as fetal stages. Although the earlier stages of R. amplexicaudatus show little deviations in relative timing or anatomy from Carollia, later ones are increasingly different. Integumentary structures show different degrees of developmental penetrance. Derived features in embryonic stages are clearly reflected in adult structures such as a great enlargement of the handplate in relation to the footplate at the moment in which both are fully differentiated. We propose that patagium morphogenesis includes development of dactylopatagium by initial retention and posterior growth of interdigital tissue, coupled with digit elongation; and development of pro-, plagio-, and uropatagium in association with wing muscles unique to bats. Additionally, allometric trends in wingspan, total wing area, arm-wing area, and hand-wing area were estimated with respect to CRL. Changes in the terminology of some Carollia stages (16 and 18) are proposed to facilitate comparisons across bat species
