72 research outputs found
Inelastic neutron scattering due to acoustic vibrations confined in nanoparticles: theory and experiment
The inelastic scattering of neutrons by nanoparticles due to acoustic
vibrational modes (energy below 10 meV) confined in nanoparticles is calculated
using the Zemach-Glauber formalism. Such vibrational modes are commonly
observed by light scattering techniques (Brillouin or low-frequency Raman
scattering). We also report high resolution inelastic neutron scattering
measurements for anatase TiO2 nanoparticles in a loose powder. Factors enabling
the observation of such vibrations are discussed. These include a narrow
nanoparticle size distribution which minimizes inhomogeneous broadening of the
spectrum and the presence of hydrogen atoms oscillating with the nanoparticle
surfaces which enhances the number of scattered neutrons.Comment: 3 figures, 1 tabl
Carbon dioxide emissions from the flat bottom and shallow Nam Theun 2 Reservoir: drawdown area as a neglected pathway to the atmosphere
Freshwater reservoirs are a significant source of CO2 to the atmosphere.
CO2 is known to be emitted at the reservoir surface by diffusion at the
air–water interface and downstream of dams or powerhouses by degassing and
along the river course. In this study, we quantified total CO2 emissions
from the Nam Theun 2 Reservoir (Lao PDR) in the Mekong River watershed. The
study started in May 2009, less than a year after flooding and just a few
months after the maximum level was first reached and lasted until the end of
2013. We tested the hypothesis that soils from the drawdown area would be a
significant contributor to the total CO2 emissions.Total inorganic carbon, dissolved and particulate organic carbon and
CO2 concentrations were measured in 4 pristine rivers of the Nam Theun
watershed, at 9 stations in the reservoir (vertical profiles) and at 16
stations downstream of the monomictic reservoir on a weekly to monthly
basis. CO2 bubbling was estimated during five field campaigns between
2009 and 2011 and on a weekly monitoring, covering water depths ranging from
0.4 to 16 m and various types of flooded ecosystems in 2012 and 2013. Three
field campaigns in 2010, 2011 and 2013 were dedicated to the soils
description in 21 plots and the quantification of soil CO2 emissions
from the drawdown area. On this basis, we calculated total CO2
emissions from the reservoir and carbon inputs from the tributaries. We
confirm the importance of the flooded stock of organic matter as a source of
carbon (C) fuelling emissions. We show that the drawdown area contributes, depending
on the year, from 40 to 75 % of total annual gross emissions in this
flat and shallow reservoir. Since the CO2 emissions from the drawdown
zone are almost constant throughout the years, the large interannual
variations result from the significant decrease in diffusive fluxes and
downstream emissions between 2010 and 2013. This overlooked pathway in terms
of gross emissions would require an in-depth evaluation for the soil organic matter and
vegetation dynamics to evaluate the actual contribution of this area in
terms of net modification of gas exchange in the footprint of the reservoir,
and how it could evolve in the future
Proteomics of Parma Dry-Cured Ham: Analysis of Salting Exudates
The production of Parma dry-cured ham involves the steps of salting, drying, and ripening. Although sea salt is the only preserving agent, there are strategies being developed with the goal of reducing salt content in order to decrease its negative impact on consumer health. A 24 h pressure treatment was applied before salting to reduce thickness and inequalities in shape. To evaluate the potential impact of the pressure step on the process outcome, differential proteomic analyses by complementary 2D-PAGE and LC MS/MS were carried out on exudates collected at day 1, 5, and 18 of the salting phase for hams treated or untreated with pressure. Specific proteins were found differentially abundant in exudates from pressed vs unpressed hams and as a function of time. These changes include glycolytic enzymes and several myofibrillar proteins. These findings indicate that pressure causes a faster loosening of the myofibrillar structure with the release of specific groups of proteins
- …