752 research outputs found
The hydrogenation of metals upon interaction with water
Hydrogen evolution at 600 deg and 5 x 10 to the 7th power - 10 to the 6th power torr from AVOOO Al samples, which were pickled in 10 percent NaOH, is discussed. An H evolution kinetic equation is derived for samples of equal vol. and different surfaces (5 and 20 sq cm). The values of the H evolution coefficient K indicated an agreement with considered H diffusion mechanism through an oxide layer. The activation energy for the H evolution process, obtained from the K-temp. relation, was 13,000 2000 cal/g-atom
The detection of patients at risk of gastrointestinal toxicity during pelvic radiotherapy by electronic nose and FAIMS : a pilot study
It is well known that the electronic nose can be used to identify differences between human health and disease for a range of disorders. We present a pilot study to investigate if the electronic nose and a newer technology, FAIMS (Field Asymmetric Ion Mobility Spectrometry), can be used to identify and help inform the treatment pathway for patients receiving pelvic radiotherapy, which frequently causes gastrointestinal side-effects, severe in some. From a larger group, 23 radiotherapy patients were selected where half had the highest levels of toxicity and the others the lowest. Stool samples were obtained before and four weeks after radiotherapy and the volatiles and gases emitted analysed by both methods; these chemicals are products of fermentation caused by gut microflora. Principal component analysis of the electronic nose data and wavelet transform followed by Fisher discriminant analysis of FAIMS data indicated that it was possible to separate patients after treatment by their toxicity levels. More interestingly, differences were also identified in their pre-treatment samples. We believe these patterns arise from differences in gut microflora where some combinations of bacteria result to give this olfactory signature. In the future our approach may result in a technique that will help identify patients at “high risk” even before radiation treatment is started
Structural evolution in Pt isotopes with the Interacting Boson Model Hamiltonian derived from the Gogny Energy Density Functional
Spectroscopic calculations are carried out, for the description of the
shape/phase transition in Pt nuclei in terms of the Interacting Boson Model
(IBM) Hamiltonian derived from (constrained) Hartree-Fock-Bogoliubov (HFB)
calculations with the finite range and density dependent Gogny-D1S Energy
Density Functional. Assuming that the many-nucleon driven dynamics of nuclear
surface deformation can be simulated by effective bosonic degrees of freedom,
the Gogny-D1S potential energy surface (PES) with quadrupole degrees of freedom
is mapped onto the corresponding PES of the IBM. Using this mapping procedure,
the parameters of the IBM Hamiltonian, relevant to the low-lying quadrupole
collective states, are derived as functions of the number of valence nucleons.
Merits of both Gogny-HFB and IBM approaches are utilized so that the spectra
and the wave functions in the laboratory system are calculated precisely. The
experimental low-lying spectra of both ground-state and side-band levels are
well reproduced. From the systematics of the calculated spectra and the reduced
E2 transition probabilities (E2), the prolate-to-oblate shape/phase
transition is shown to take place quite smoothly as a function of neutron
number in the considered Pt isotopic chain, for which the -softness
plays an essential role. All these spectroscopic observables behave
consistently with the relevant PESs and the derived parameters of the IBM
Hamiltonian as functions of . Spectroscopic predictions are also made for
those nuclei which do not have enough experimental E2 data.Comment: 11 pages, 5 figure
Shape of primary proton spectrum in multi-TeV region from data on vertical muon flux
It is shown, that primary proton spectrum, reconstructed from sea-level and
underground data on muon spectrum with the use of QGSJET 01, QGSJET II, NEXUS
3.97 and SIBYLL 2.1 interaction models, demonstrates not only model-dependent
intensity, but also model-dependent form. For correct reproduction of muon
spectrum shape primary proton flux should have non-constant power index for all
considered models, except SIBYLL 2.1, with break at energies around 10-15 TeV
and value of exponent before break close to that obtained in ATIC-2 experiment.
To validate presence of this break understanding of inclusive spectra behavior
in fragmentation region in p-air collisions should be improved, but we show,
that it is impossible to do on the basis of the existing experimental data on
primary nuclei, atmospheric muon and hadron fluxes.Comment: Submitted to Phys. Rev.
Intruder bands and configuration mixing in the lead isotopes
A three-configuration mixing calculation is performed in the context of the
interacting boson model with the aim to describe recently observed collective
bands built on low-lying states in neutron-deficient lead isotopes. The
configurations that are included correspond to the regular, spherical states as
well as two-particle two-hole and four-particle four-hole excitations across
the Z=82 shell gap.Comment: 20 pages, 4 figures, accepted by PRC, reference added for section 1
in this revised versio
Lifetime of 19Ne*(4.03 MeV)
The Doppler-shift attenuation method was applied to measure the lifetime of
the 4.03 MeV state in 19Ne. Utilizing a 3He-implanted Au foil as a target, the
state was populated using the 20Ne(3He,alpha)19Ne reaction in inverse
kinematics at a 20Ne beam energy of 34 MeV. De-excitation gamma rays were
detected in coincidence with alpha particles. At the 1 sigma level, the
lifetime was determined to be 11 +4, -3 fs and at the 95.45% confidence level
the lifetime is 11 +8, -7 fs.Comment: 6 pages, submitted to Phys. Rev.
Wolfram Syndrome protein, Miner1, regulates sulphydryl redox status, the unfolded protein response, and Ca2+ homeostasis.
Miner1 is a redox-active 2Fe2S cluster protein. Mutations in Miner1 result in Wolfram Syndrome, a metabolic disease associated with diabetes, blindness, deafness, and a shortened lifespan. Embryonic fibroblasts from Miner1(-/-) mice displayed ER stress and showed hallmarks of the unfolded protein response. In addition, loss of Miner1 caused a depletion of ER Ca(2+) stores, a dramatic increase in mitochondrial Ca(2+) load, increased reactive oxygen and nitrogen species, an increase in the GSSG/GSH and NAD(+)/NADH ratios, and an increase in the ADP/ATP ratio consistent with enhanced ATP utilization. Furthermore, mitochondria in fibroblasts lacking Miner1 displayed ultrastructural alterations, such as increased cristae density and punctate morphology, and an increase in O2 consumption. Treatment with the sulphydryl anti-oxidant N-acetylcysteine reversed the abnormalities in the Miner1 deficient cells, suggesting that sulphydryl reducing agents should be explored as a treatment for this rare genetic disease
Beta-delayed deuteron emission from 11Li: decay of the halo
The deuteron-emission channel in the beta-decay of the halo-nucleus 11Li was
measured at the ISAC facility at TRIUMF by implanting post-accelerated 11Li
ions into a segmented silicon detector. The events of interest were identified
by correlating the decays of 11Li with those of the daughter nuclei. This
method allowed the energy spectrum of the emitted deuterons to be extracted,
free from contributions from other channels, and a precise value for the
branching ratio B_d = 1.30(13) x 10-4 to be deduced for E(c.m.) > 200 keV. The
results provide the first unambiguous experimental evidence that the decay
takes place essentially in the halo of 11Li, and that it proceeds mainly to the
9Li + d continuum, opening up a new means to study of the halo wave function of
11Li.Comment: 4 pages, 3 figure
Early onset of ground-state deformation in the neutron-deficient polonium isotopes
In-source resonant ionization laser spectroscopy of the even- polonium
isotopes Po has been performed using the
to ( nm) transition in the polonium atom
(Po-I) at the CERN ISOLDE facility. The comparison of the measured isotope
shifts in Po with a previous data set allows to test for the first
time recent large-scale atomic calculations that are essential to extract the
changes in the mean-square charge radius of the atomic nucleus. When going to
lighter masses, a surprisingly large and early departure from sphericity is
observed, which is only partly reproduced by Beyond Mean Field calculations.Comment: As submitted to PR
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