1,388 research outputs found
Coherent coupling between surface plasmons and excitons in semiconductor nanocrystals
We present an experimental demonstration of strong coupling between a surface
plasmon propagating on a planar silver substrate, and the lowest excited state
of CdSe nanocrystals. Variable-angle spectroscopic ellipsometry measurements
demonstrated the formation of plasmon-exciton mixed states, characterized by a
Rabi splitting of 82 meV at room temperature. Such a coherent
interaction has the potential for the development of plasmonic non-linear
devices, and furthermore, this system is akin to those studied in cavity
quantum electrodynamics, thus offering the possibility to study the regime of
strong light-matter coupling in semiconductor nanocrystals at easily accessible
experimental conditions.Comment: 12 pages, 4 figure
Sources of total, non-milk extrinsic, and intrinsic and milk sugars in the diets of older adults living in sheltered accommodation
The WHO recommends limiting non-milk extrinsic sugars (NMES) consumption to ≤ 10 % energy to reduce the risk of unhealthy weight gain and dental caries, and to restrict frequency of intake to ≤ 4 times/d to reduce risk of dental caries. Older adults, especially those from low-income backgrounds, are at increased risk of dental caries, yet there is little information on sugars intake (frequency of intake and food sources) in this age group. The aim of this report is to present baseline data from a community-based dietary intervention study of older adults from socially deprived areas of North East England, on the quantity and sources of total sugars, NMES, and intrinsic and milk sugars, and on frequency of NMES intake. Dietary intake was assessed using two 3-d estimated food diaries, completed by 201 participants (170 female, thirty-one male) aged 65–85 years (mean 76·7 (sd 5·5) years) recruited from sheltered housing schemes. Total sugars represented 19·6 %, NMES 9·3 %, and intrinsic and milk sugars 10·3 % of daily energy intake. Eighty-one (40·3 %) exceeded the NMES intake recommendation. Mean frequency of NMES intake was 3·4 times/d. The fifty-three participants (26·4 %) who exceeded the frequency recommendation ( ≤ 4 times/d) obtained a significantly greater percentage of energy from NMES compared with those participants who met the recommendation. The food groups ‘biscuits and cakes’ (18·9 %), ‘soft drinks’ (13·1 %) and ‘table sugar’ (11·1 %) made the greatest contributions to intakes of NMES. Interventions to reduce NMES intake should focus on limiting quantity and frequency of intake of these food groups
Scanning nano-spin ensemble microscope for nanoscale magnetic and thermal imaging
Quantum sensors based on solid-state spins provide tremendous opportunities
in a wide range of fields from basic physics and chemistry to biomedical
imaging. However, integrating them into a scanning probe microscope to enable
practical, nanoscale quantum imaging is a highly challenging task. Recently,
the use of single spins in diamond in conjunction with atomic force microscopy
techniques has allowed significant progress towards this goal, but
generalisation of this approach has so far been impeded by long acquisition
times or by the absence of simultaneous topographic information. Here we report
on a scanning quantum probe microscope which solves both issues, by employing a
nano-spin ensemble hosted in a nanodiamond. This approach provides up to an
order of magnitude gain in acquisition time, whilst preserving sub-100 nm
spatial resolution both for the quantum sensor and topographic images. We
demonstrate two applications of this microscope. We first image nanoscale
clusters of maghemite particles through both spin resonance spectroscopy and
spin relaxometry, under ambient conditions. Our images reveal fast magnetic
field fluctuations in addition to a static component, indicating the presence
of both superparamagnetic and ferromagnetic particles. We next demonstrate a
new imaging modality where the nano-spin ensemble is used as a thermometer. We
use this technique to map the photo-induced heating generated by laser
irradiation of a single gold nanoparticle in a fluid environment. This work
paves the way towards new applications of quantum probe microscopy such as
thermal/magnetic imaging of operating microelectronic devices and magnetic
detection of ion channels in cell membranes.Comment: 22 pages including Supporting Information. Changes to v1:
affiliations and funding information updated, plus minor revisions to the
main tex
Real-time diagnostics of gas/water assisted injection moulding using integrated ultrasonic sensors
YesAn ultrasound sensor system has been applied to the mould of both the water and gas assisted
injection moulding processes. The mould has a cavity wall mounted pressure sensor and instrumentation to
monitor the injection moulding machine. Two ultrasound sensors are used to monitor the arrival of the fluid
(gas or water) bubble tip through the detection of reflected ultrasound energy from the fluid polymer
boundary and the fluid bubble tip velocity through the polymer melt is estimated. The polymer contact with
the cavity wall is observed through the reflected ultrasound energy from that boundary. A theoretically
based estimation of the residual wall thickness is made using the ultrasound reflection from the fluid (gas or
water) polymer boundary whilst the samples are still inside the mould and a good correlation with a physical
measurement is observed
A reconstruction of the past trend of atmospheric CO based on firn air samples from Berkner Island, Antarctica
International audienceAlthough for several atmospheric trace gases trends over the past 100 year have been reconstructed using firn air analyses, little is known about one of the chemically most significant trace gases, namely CO. Among the 3 Antarctic drilling expeditions reported, the one from Berkner Island appears to have given results of sufficient analytical quality to warrant a modelling with the aim to reconstruct past changes in atmospheric CO. Based on our reconstructions, CO in high latitudes of the Southern Hemisphere has been increasing since beginning of the 20th century from ~38 ppbv to a recent value of about 52.5 ppbv. The increase in CO is mainly explained by the known increase in CH4, with biomass burning output being most likely responsible for an additional increase. Which, if any, role changes in OH have played cannot be derived
Changing the fine structure aluminum alloys under intensive plastic deformation
This chapter shows the experimental data on the effect of different methods of plastic deformation on the evolution of structural and phase transformations in the AMC and AMG6 alloys
Chlorine isotope composition in chlorofluorocarbons CFC-11, CFC-12 and CFC-113 in firn, stratospheric and tropospheric air
The stratospheric degradation of chlorofluorocarbons (CFCs) releases chlorine, which is a major contributor to the destruction of stratospheric ozone (O3). A recent study reported strong chlorine isotope fractionation during the breakdown of the most abundant CFC (CFC-12, CCl2F2, Laube et al., 2010a), similar to effects seen in nitrous oxide (N2O). Using air archives to obtain a long-term record of chlorine isotope ratios in CFCs could help to identify and quantify their sources and sinks. We analyse the three most abundant CFCs and show that CFC-11 (CCl3F) and CFC-113 (CClF2CCl2F) exhibit significant stratospheric chlorine isotope fractionation, in common with CFC-12. The apparent isotope fractionation (εapp) for mid- and high-latitude stratospheric samples are (-2.4±0.5) ‰ and (-2.3±0.4) ‰ for CFC-11, (-12.2±1.6) ‰ and (-6.8±0.8) ‰ for CFC-12 and (-3.5±1.5) ‰ and (-3.3±1.2) ‰ for CFC-113, respectively. Assuming a constant isotope composition of emissions, we calculate the expected trends in the tropospheric isotope signature of these gases based on their stratospheric 37Cl enrichment and stratosphere-troposphere exchange. We compare these projections to the long-term δ(37Cl) trends of all three CFCs, measured on background tropospheric samples from the Cape Grim air archive (Tasmania, 1978 – 2010) and tropospheric firn air samples from Greenland (NEEM site) and Antarctica (Fletcher Promontory site). From 1970 to the present-day, projected trends agree with tropospheric measurements, suggesting that within analytical uncertainties a constant average emission isotope delta is a compatible scenario. The measurement uncertainty is too high to determine whether the average emission isotope delta has been affected by changes in CFC manufacturing processes, or not. Our study increases the suite of trace gases amenable to direct isotope ratio measurements in small air volumes (approximately 200 ml), using a single-detector gas chromatography-mass spectrometry system
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