338 research outputs found
Microscopic calculation of the spin-dependent neutron scattering lengths on 3He
We report on the spin.dependent neutron scattering length on 3He from a
microscopic calculation of p-3H, n-3He, and d-2H scattering employing the
Argonne v18 nucleon-nucleon potential with and without additional three-nucleon
force. The results and that of a comprehensive R-matrix analysis are compared
to a recent measurement. The overall agreement for the scattering lengths is
quite good. The imaginary parts of the scattering lengths are very sensitive to
the inclusion of three-nucleon forces, whereas the real parts are almost
insensitive.Comment: 9 pages, 1 figur
Study of Biodiesel Production from Sunflower Oil Using Non Usual Basic Polymeric Resin as Catalyst
Biodiesel is defined as a long-chain mono alkyl (methyl, ethyl or propyl) ester of fatty acids obtained from renewable sources by transesterification reaction using an acid or base. In this work, a basic resin, Amberlyst A26, was used to produce methyl sunflower biodiesel. The iodine value, corrosion to copper, oxidative stability, specific mass, water content, acid value, cloud point and ester composition were evaluated. The heterogeneous catalyst was also characterized to verify its efficiency and its ability to be reused. We used the following analytical techniques: scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-rays fluorescence (XRF) and differential scanning calorimetry (DSC). The results showed that the characteristics of biodiesel made from sunflower oil using resin A26 as a catalyst are in accordance with Brazilian biodiesel regulations, except the oxidative stability. The techniques used to characterize the resin showed that it is possible to reuse the resin after regeneration
Elemental Chemometrics as Tools to Depict Stalked Barnacle (Pollicipes pollicipes) Harvest Locations and Food Safety
The stalked barnacle Pollicipes pollicipes is an abundant species on the very exposed rocky shore habitats of the Spanish and Portuguese coasts, constituting also an important economical resource, as a seafood item with high commercial value. Twenty-four elements were measured by untargeted total reflection X-ray fluorescence spectroscopy (TXRF) in the edible peduncle of stalked barnacles sampled in six sites along the Portuguese western coast, comprising a total of 90 individuals. The elemental profile of 90 individuals originated from several geographical sites (N = 15 per site), were analysed using several chemometric multivariate approaches (variable in importance partial least square discriminant analysis (VIP-PLS-DA), stepwise linear discriminant analysis (S-LDA), linear discriminant analysis (LDA), random forests (RF) and canonical analysis of principal components (CAP)), to evaluate the ability of each approach to trace the geographical origin of the animals collected. As a suspension feeder, this species introduces a high degree of background noise, leading to a comparatively lower classification of the chemometric approaches based on the complete elemental profile of the peduncle (canonical analysis of principal components and linear discriminant analysis). The application of variable selection approaches such as the VIP-PLS-DA and S-LDA significantly increased the classification accuracy (77.8% and 84.4%, respectively) of the samples according to their harvesting area, while reducing the number of elements needed for this classification, and thus the background noise. Moreover, the selected elements are similar to those selected by other random and non-random approaches, reinforcing the reliability of this selection. This untargeted analytical procedure also allowed to depict the degree of risk, in terms of human consumption of these animals, highlighting the geographical areas where these delicacies presented lower values for critical elements compared to the standard thresholds for human consumption
Laurus nobilis (laurel) aqueous leaf extract's toxicological and anti-tumor activities in HPV16-transgenic mice
Cancers induced by human papillomavirus (HPV) infection remain a significant public health threat,
fueling the study of new therapies. Laurel (Laurus nobilis) compounds and extracts recently showed
in vitro activity against HPV-transformed cell lines. This work aims to evaluate the in vivo efficacy and
hepatic toxicity of a laurel extract in a transgenic mouse model of HPV16-induced cancer. The extract was
administered in drinking water (20 mg per animal per day) for three consecutive weeks, using four experimental
groups (n = 10) (group I: HPV16−/− without treatment, group II: treated HPV16−/−, group III: HPV16+/−
without treatment and group IV: treated HPV16+/−). Following the treatment period, animals were sacrificed
and skin samples were used to classify skin lesions histologically. Toxicological parameters included hematological
and biochemical blood markers, splenic and hepatic histology and hepatic oxidative stress. The
extract did not prevent the progression of HPV16-induced cutaneous lesions in this model. The treated wildtype
animals showed mild hepatitis, while transgenic animals suffered weight loss. However, there were no
changes concerning hematological, biochemical and hepatic oxidative stress markers.This work was supported by: Integrative Research in
Environment, Agro-Chains and Technology no. NORTE-01-
0145-FEDER-000017, in its line of research entitled ISAC, cofinanced
by the European Regional Development Fund (ERDF)
through NORTE 2020 (North Regional Operational Program
2014/2020). European Investment Funds by FEDER/COMPETE/
POCI– Operational Competitiveness and Internationalization
Programme, under Project POCI-01-0145-FEDER-006958 and
National Funds by FCT - Portuguese Foundation for Science
and Technology, under the project UID/AGR/04033/2013. This
study was also funded by Liga Portuguesa Contra o Cancro, by
the Research Center of the Portuguese Institute of Oncology of
Porto (CI-IPOP 37-2016), by project POCI-01-0145-
FEDER-006939 (Laboratory for Process Engineering,
Environment, Biotechnology and Energy – LEPABE), project
POCI-01-0145-FEDER-006958 and UID/AGR/04033/2013,
funded by FEDER funds through COMPETE2020 - Programa
Operacional Competitividade e Internacionalização (POCI) –
and by national funds through FCT – Fundação para a Ciência
e a Tecnologia; Rui M. Gil da Costa was funded by grant
number SFRH/BPD/85462/2012 from FCT, funded by the
Portuguese Government and the Social European Fund. The
authors are also grateful to FCT, Portugal and FEDER under
Programme PT2020 for financial support to CIMO (UID/AGR/
00690/2013), and to the Interreg España-Portugal for financial
support through the project 0377_Iberphenol_6_E.info:eu-repo/semantics/publishedVersio
Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment
This paper describes an analysis of the angular distribution of W->enu and
W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with
the ATLAS detector at the LHC in 2010, corresponding to an integrated
luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and
the missing transverse energy, the W decay angular distribution projected onto
the transverse plane is obtained and analysed in terms of helicity fractions
f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV
and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw
> 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour,
are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017
+/- 0.030, where the first uncertainties are statistical, and the second
include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables,
revised author list, matches European Journal of Physics C versio
Observation of a new chi_b state in radiative transitions to Upsilon(1S) and Upsilon(2S) at ATLAS
The chi_b(nP) quarkonium states are produced in proton-proton collisions at
the Large Hadron Collider (LHC) at sqrt(s) = 7 TeV and recorded by the ATLAS
detector. Using a data sample corresponding to an integrated luminosity of 4.4
fb^-1, these states are reconstructed through their radiative decays to
Upsilon(1S,2S) with Upsilon->mu+mu-. In addition to the mass peaks
corresponding to the decay modes chi_b(1P,2P)->Upsilon(1S)gamma, a new
structure centered at a mass of 10.530+/-0.005 (stat.)+/-0.009 (syst.) GeV is
also observed, in both the Upsilon(1S)gamma and Upsilon(2S)gamma decay modes.
This is interpreted as the chi_b(3P) system.Comment: 5 pages plus author list (18 pages total), 2 figures, 1 table,
corrected author list, matches final version in Physical Review Letter
- …