526 research outputs found
Methane hydrate formation in confined nanospace can surpass nature
Natural methane hydrates are believed to be the largest source of hydrocarbons on Earth. These structures are formed in specific locations such as deep-sea sediments and the permafrost based on demanding conditions of high pressure and low temperature. Here we report that, by taking advantage of the confinement effects on nanopore space, synthetic methane hydrates grow under mild conditions (3.5 MPa and 2 degrees C), with faster kinetics (within minutes) than nature, fully reversibly and with a nominal stoichiometry that mimics nature. The formation of the hydrate structures in nanospace and their similarity to natural hydrates is confirmed using inelastic neutron scattering experiments and synchrotron X-ray powder diffraction. These findings may be a step towards the application of a smart synthesis of methane hydrates in energy-demanding applications (for example, transportation).We acknowledge UK Science and Technlology Facilities Council for the provision of beam time on the TOSCA spectrometer (Projects RB1410624 and RB122099) and financial support from the European Commission under the 7th Framework Programme through the 'Research Infrastructures' action of the 'Capacities' Programme (NMI3-II Grant number 283883). J.S.-A. and F.R. acknowledges the financial support from MINECO: Strategic Japanese-Spanish Cooperation Program (PLE2009-0052), Concert Project-NASEMS (PCIN-2013-057) and Generalitat Valenciana (PROMETEO/2009/002). F.R. and J.L.J. thank the financial support from MINECO (MAT2012-38567-C02-01, Consolider Ingenio 2010-Multicat CSD-2009-00050 and SEV-2012-0267). K.K. thanks Grant-in-Aid for Scientific Research (A) (2424-1038), Japan. A.B. and A.U. thank the financial support from MINECO (SEV-2013-0319). J.L.J. and I.P. thank synchrotron ALBA for beamtime availability.Casco, M.; Silvestre Albero, J.; Ramirez-Cuesta, A.; Rey Garcia, F.; Jorda Moret, JL.; Bansode, A.; Urakawa, A.... (2015). Methane hydrate formation in confined nanospace can surpass nature. Nature Communications. 6(6432):1-8. https://doi.org/10.1038/ncomms7432S1866432Sloan, E. D. Jr., & Koh, C. A. Clathrate Hydrates of Natural Gases 3rd edn CRC Press (2007).Gutt, C. et al. The structure of deuterated methane-hydrate. J. Chem. Phys. 113, 4713–4721 (2000).Holbrook, W. S., Hoskins, H., Wood, W. T., Stephen, R. A. & Lizarralde, D. Methane hydrate and free gas on the Blake Ridge from vertical seismic profiling. Science 273, 1840–1843 (1996).Sloan, E. D. Jr., Fundamental principles and applications of natural gas hydrates. Nature 426, 353–363 (2003).Rodríguez-Reinoso, F., Almansa, C. & Molina-Sabio, M. Contribution to the evaluation of density of methane adsorbed on activated carbon. J. Phys. Chem. B 109, 20227–20231 (2005).Kockrick, E. et al. Ordered mesoporous carbide derived carbons for high pressure gas storage. Carbon 48, 1707–1717 (2010).Klein, N. et al. A mesoporous metal-organic framework. Angew. Chem. Int. Ed. 48, 9954–9957 (2009).Makal, T. A., Li, J.-R., Lu, W. & Zhou, H.-C. Methane storage in advanced porous materials. Chem. Soc. Rev. 41, 7761–7779 (2012).Peng, Y. et al. Methane storage in metal-organic frameworks: Current records, surprise findings, and challenges. J. Am.Chem. Soc. 135, 11887–11894 (2013).Casco, M. E. et al. High-pressure methane storage in porous materials: are carbon materials in the pole position? Chem. Mater 27, 959–964 (2015).Ramos-Fernández, J. M., Martínez-Escandell, M. & Rodríguez-Reinoso, F. Production of binderless activated carbon monoliths by KOH activation of carbon mesophase materials. Carbon 46, 384–386 (2008).Marsh, H. & Rodríguez-Reinoso, F. Activated Carbon Elsevier (2006).Kubo, T. et al. Diffusion-barrier-free porous carbon monoliths as a new form of activated carbon. ChemSusChem 5, 2271–2277 (2012).Kaneko, K., Itoh, T. & Fujimori, T. Collective interactions of molecules with an interfacial solid. Chem. Lett. 41, 466–475 (2012).Nakamura, M., Ohba, T., Branton, P., Kanoh, H. & Kaneko, K. Equilibrium-time and pore-width dependent hysteresis of water adsorption isotherm on hydrophobic microporous carbons. Carbon 48, 305–308 (2010).Vysniauskas, A. & Bishnoi, P. R. A kinetic study of methane hydrate formation. Chem. Eng. Sci. 38, 1061–1072 (1983).Junhong, Q. & Tianmin, G. Kinetics of methane hydrate formation in pure water and inhibitor containing systems. Chin. J. Chem. Eng 10, 316–322 (2002).Liu, J., Zhou, Y., Sun, Y., Su, W. & Zhou, L. Methane storage in wet carbon of tailored pore sizes. Carbon 49, 3731–3736 (2011).Perrin, A., Celzard, A., Marêché, J. F. & Furdin, G. Methane storage within dry and wet activated carbons: a comparative study. Energy Fuels 17, 1283–1291 (2003).Zhou, L., Liu, L., Su, W., Sun, Y. & Zhou, Y. Progress in studies of natural gas storage with wet adsorbents. Energy Fuels 24, 3789–3795 (2010).Celzard, A. & Marêché, J. F. Optimal wetting of activated carbons for methane hydrate formation. Fuel 85, 957–966 (2006).Webb, E. B. et al. High pressure rheology of hydrate slurries formed from water-in-oil emulsions. Energy Fuels 26, 3504–3509 (2012).Urita, K. et al. Confinement in carbon nanospace-induced production of KI nanocrystals of high-pressure phase. J. Am. Chem. Soc. 133, 10344–10347 (2011).Fujimori, T. et al. Conducting linear chains of sulphur inside carbon nanotubes. Nat. Commun. 4, 2162 (2013).Tse, J. S., Ratcliffe, C. L., Powell, B. M., Sears, V. F. & Handa, Y. P. Rotational and translational motions of trapped methane. Incoherent inelastic neutron scattering of methane hydrate. J. Phys. Chem. A 101, 4491–4495 (1997).Gutt, C. et al. Quantum rotations in natural methane-clathrates from the Pacific sea-floor. Europhys. Lett. 48, 269–275 (1999).Stern, L. A., Kirby, S. H. & Durham, W. B. Peculiarities of methane clathrate hydrate formation and solid-state deformation, including possible superheating of water ice. Science 273, 1843–1848 (1996).Gutt, C. et al. The structure of deuterated methane hydrate. J. Chem. Phys. 113, 4713–4721 (2000).Everett, S. M. et al. Kinetics of methane hydrate decomposition studies via in situ low temperature X-ray powder diffraction. J. Phys. Chem. A 117, 3593–3598 (2013).Miyawaki, J. et al. Macroscopic evidence of enhanced formation of methane nanohydrates in hydrophobic nanospaces. J. Phys. Chem. B 102, 2187–2192 (1998)
Effectiveness of an mHealth intervention combining a smartphone app and smart band on body composition in an overweight and obese population: Randomized controlled trial (EVIDENT 3 study)
Background: Mobile health (mHealth) is currently among the supporting elements that may contribute to an improvement in health markers by helping people adopt healthier lifestyles. mHealth interventions have been widely reported to achieve greater weight loss than other approaches, but their effect on body composition remains unclear.
Objective: This study aimed to assess the short-term (3 months) effectiveness of a mobile app and a smart band for losing weight and changing body composition in sedentary Spanish adults who are overweight or obese.
Methods: A randomized controlled, multicenter clinical trial was conducted involving the participation of 440 subjects from primary care centers, with 231 subjects in the intervention group (IG; counselling with smartphone app and smart band) and 209 in the control group (CG; counselling only). Both groups were counselled about healthy diet and physical activity. For the 3-month intervention period, the IG was trained to use a smartphone app that involved self-monitoring and tailored feedback, as well as a smart band that recorded daily physical activity (Mi Band 2, Xiaomi). Body composition was measured using the InBody 230 bioimpedance device (InBody Co., Ltd), and physical activity was measured using the International Physical Activity Questionnaire.
Results: The mHealth intervention produced a greater loss of body weight (–1.97 kg, 95% CI –2.39 to –1.54) relative to standard counselling at 3 months (–1.13 kg, 95% CI –1.56 to –0.69). Comparing groups, the IG achieved a weight loss of 0.84 kg more than the CG at 3 months. The IG showed a decrease in body fat mass (BFM; –1.84 kg, 95% CI –2.48 to –1.20), percentage of body fat (PBF; –1.22%, 95% CI –1.82% to 0.62%), and BMI (–0.77 kg/m2, 95% CI –0.96 to 0.57). No significant changes were observed in any of these parameters in men; among women, there was a significant decrease in BMI in the IG compared with the CG. When subjects were grouped according to baseline BMI, the overweight group experienced a change in BFM of –1.18 kg (95% CI –2.30 to –0.06) and BMI of –0.47 kg/m2 (95% CI –0.80 to –0.13), whereas the obese group only experienced a change in BMI of –0.53 kg/m2 (95% CI –0.86 to –0.19). When the data were analyzed according to physical activity, the moderate-vigorous physical activity group showed significant changes in BFM of –1.03 kg (95% CI –1.74 to –0.33), PBF of –0.76% (95% CI –1.32% to –0.20%), and BMI of –0.5 kg/m2 (95% CI –0.83 to –0.19).
Conclusions: The results from this multicenter, randomized controlled clinical trial study show that compared with standard counselling alone, adding a self-reported app and a smart band obtained beneficial results in terms of weight loss and a reduction in BFM and PBF in female subjects with a BMI less than 30 kg/m2 and a moderate-vigorous physical activity level. Nevertheless, further studies are needed to ensure that this profile benefits more than others from this intervention and to investigate modifications of this intervention to achieve a global effect
Anisotropy studies around the galactic centre at EeV energies with the Auger Observatory
Data from the Pierre Auger Observatory are analyzed to search for
anisotropies near the direction of the Galactic Centre at EeV energies. The
exposure of the surface array in this part of the sky is already significantly
larger than that of the fore-runner experiments. Our results do not support
previous findings of localized excesses in the AGASA and SUGAR data. We set an
upper bound on a point-like flux of cosmic rays arriving from the Galactic
Centre which excludes several scenarios predicting sources of EeV neutrons from
Sagittarius . Also the events detected simultaneously by the surface and
fluorescence detectors (the `hybrid' data set), which have better pointing
accuracy but are less numerous than those of the surface array alone, do not
show any significant localized excess from this direction.Comment: Matches published versio
Evidence for a mixed mass composition at the `ankle' in the cosmic-ray spectrum
We report a first measurement for ultra-high energy cosmic rays of the
correlation between the depth of shower maximum and the signal in the water
Cherenkov stations of air-showers registered simultaneously by the fluorescence
and the surface detectors of the Pierre Auger Observatory. Such a correlation
measurement is a unique feature of a hybrid air-shower observatory with
sensitivity to both the electromagnetic and muonic components. It allows an
accurate determination of the spread of primary masses in the cosmic-ray flux.
Up till now, constraints on the spread of primary masses have been dominated by
systematic uncertainties. The present correlation measurement is not affected
by systematics in the measurement of the depth of shower maximum or the signal
in the water Cherenkov stations. The analysis relies on general characteristics
of air showers and is thus robust also with respect to uncertainties in
hadronic event generators. The observed correlation in the energy range around
the `ankle' at differs significantly from
expectations for pure primary cosmic-ray compositions. A light composition made
up of proton and helium only is equally inconsistent with observations. The
data are explained well by a mixed composition including nuclei with mass . Scenarios such as the proton dip model, with almost pure compositions, are
thus disfavoured as the sole explanation of the ultrahigh-energy cosmic-ray
flux at Earth.Comment: Published version. Added journal reference and DOI. Added Report
Numbe
Measurement of the Bottom-Strange Meson Mixing Phase in the Full CDF Data Set
We report a measurement of the bottom-strange meson mixing phase \beta_s
using the time evolution of B0_s -> J/\psi (->\mu+\mu-) \phi (-> K+ K-) decays
in which the quark-flavor content of the bottom-strange meson is identified at
production. This measurement uses the full data set of proton-antiproton
collisions at sqrt(s)= 1.96 TeV collected by the Collider Detector experiment
at the Fermilab Tevatron, corresponding to 9.6 fb-1 of integrated luminosity.
We report confidence regions in the two-dimensional space of \beta_s and the
B0_s decay-width difference \Delta\Gamma_s, and measure \beta_s in [-\pi/2,
-1.51] U [-0.06, 0.30] U [1.26, \pi/2] at the 68% confidence level, in
agreement with the standard model expectation. Assuming the standard model
value of \beta_s, we also determine \Delta\Gamma_s = 0.068 +- 0.026 (stat) +-
0.009 (syst) ps-1 and the mean B0_s lifetime, \tau_s = 1.528 +- 0.019 (stat) +-
0.009 (syst) ps, which are consistent and competitive with determinations by
other experiments.Comment: 8 pages, 2 figures, Phys. Rev. Lett 109, 171802 (2012
Search for a W' boson decaying to a bottom quark and a top quark in pp collisions at sqrt(s) = 7 TeV
Results are presented from a search for a W' boson using a dataset
corresponding to 5.0 inverse femtobarns of integrated luminosity collected
during 2011 by the CMS experiment at the LHC in pp collisions at sqrt(s)=7 TeV.
The W' boson is modeled as a heavy W boson, but different scenarios for the
couplings to fermions are considered, involving both left-handed and
right-handed chiral projections of the fermions, as well as an arbitrary
mixture of the two. The search is performed in the decay channel W' to t b,
leading to a final state signature with a single lepton (e, mu), missing
transverse energy, and jets, at least one of which is tagged as a b-jet. A W'
boson that couples to fermions with the same coupling constant as the W, but to
the right-handed rather than left-handed chiral projections, is excluded for
masses below 1.85 TeV at the 95% confidence level. For the first time using LHC
data, constraints on the W' gauge coupling for a set of left- and right-handed
coupling combinations have been placed. These results represent a significant
improvement over previously published limits.Comment: Submitted to Physics Letters B. Replaced with version publishe
Anisotropic flow of charged hadrons, pions and (anti-)protons measured at high transverse momentum in Pb-Pb collisions at TeV
The elliptic, , triangular, , and quadrangular, , azimuthal
anisotropic flow coefficients are measured for unidentified charged particles,
pions and (anti-)protons in Pb-Pb collisions at TeV
with the ALICE detector at the Large Hadron Collider. Results obtained with the
event plane and four-particle cumulant methods are reported for the
pseudo-rapidity range at different collision centralities and as a
function of transverse momentum, , out to GeV/.
The observed non-zero elliptic and triangular flow depends only weakly on
transverse momentum for GeV/. The small dependence
of the difference between elliptic flow results obtained from the event plane
and four-particle cumulant methods suggests a common origin of flow
fluctuations up to GeV/. The magnitude of the (anti-)proton
elliptic and triangular flow is larger than that of pions out to at least
GeV/ indicating that the particle type dependence persists out
to high .Comment: 16 pages, 5 captioned figures, authors from page 11, published
version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/186
Centrality dependence of charged particle production at large transverse momentum in Pb-Pb collisions at TeV
The inclusive transverse momentum () distributions of primary
charged particles are measured in the pseudo-rapidity range as a
function of event centrality in Pb-Pb collisions at
TeV with ALICE at the LHC. The data are presented in the range
GeV/ for nine centrality intervals from 70-80% to 0-5%.
The Pb-Pb spectra are presented in terms of the nuclear modification factor
using a pp reference spectrum measured at the same collision
energy. We observe that the suppression of high- particles strongly
depends on event centrality. In central collisions (0-5%) the yield is most
suppressed with at -7 GeV/. Above
GeV/, there is a significant rise in the nuclear modification
factor, which reaches for GeV/. In
peripheral collisions (70-80%), the suppression is weaker with almost independently of . The measured nuclear
modification factors are compared to other measurements and model calculations.Comment: 17 pages, 4 captioned figures, 2 tables, authors from page 12,
published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/284
Search for the standard model Higgs boson decaying into two photons in pp collisions at sqrt(s)=7 TeV
A search for a Higgs boson decaying into two photons is described. The
analysis is performed using a dataset recorded by the CMS experiment at the LHC
from pp collisions at a centre-of-mass energy of 7 TeV, which corresponds to an
integrated luminosity of 4.8 inverse femtobarns. Limits are set on the cross
section of the standard model Higgs boson decaying to two photons. The expected
exclusion limit at 95% confidence level is between 1.4 and 2.4 times the
standard model cross section in the mass range between 110 and 150 GeV. The
analysis of the data excludes, at 95% confidence level, the standard model
Higgs boson decaying into two photons in the mass range 128 to 132 GeV. The
largest excess of events above the expected standard model background is
observed for a Higgs boson mass hypothesis of 124 GeV with a local significance
of 3.1 sigma. The global significance of observing an excess with a local
significance greater than 3.1 sigma anywhere in the search range 110-150 GeV is
estimated to be 1.8 sigma. More data are required to ascertain the origin of
this excess.Comment: Submitted to Physics Letters
Measurement of charm production at central rapidity in proton-proton collisions at TeV
The -differential production cross sections of the prompt (B
feed-down subtracted) charmed mesons D, D, and D in the rapidity
range , and for transverse momentum GeV/, were
measured in proton-proton collisions at TeV with the ALICE
detector at the Large Hadron Collider. The analysis exploited the hadronic
decays DK, DK, DD, and their charge conjugates, and was performed on a
nb event sample collected in 2011 with a
minimum-bias trigger. The total charm production cross section at TeV and at 7 TeV was evaluated by extrapolating to the full phase space
the -differential production cross sections at TeV
and our previous measurements at TeV. The results were compared
to existing measurements and to perturbative-QCD calculations. The fraction of
cdbar D mesons produced in a vector state was also determined.Comment: 20 pages, 5 captioned figures, 4 tables, authors from page 15,
published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/307
- …