1,249 research outputs found
Interaction of carbon clusters with Ni(100) : Application to the nucleation of carbon nanotubes
In order to understand the first stages of the nucleation of carbon nanotubes
in catalytic processes, we present a tight-binding Monte Carlo study of the
stability and cohesive mechanisms of different carbon structures deposited on
nickel (100) surfaces. Depending on the geometry, we obtain contrasted results.
On the one hand, the analysis of the local energy distributions of flat carbon
sheets, demonstrate that dangling bonds remain unsaturated in spite of the
presence of the metallic catalyst. Their adhesion results from the energy gain
of the surface Ni atoms located below the carbon nanostructure. On the other
hand, carbon caps are stabilized by the presence of carbon atoms occupying the
hollow sites of the fcc nickel structure suggesting the saturation of the
dangling bonds
Finite-size and pressure effects in YBa_2Cu_4O_8 probed by magnetic field penetration depth measurements
We explore the combined pressure and finite-size effects on the in-plane
penetration depth \lambda_{ab} in YBa_2Cu_4O_8. Even though this cuprate is
stoichiometric the finite-size scaling analysis of \lambda_{ab}^{-2}(T)
uncovers the granular nature and reveals domains with nanoscale size L_{c}
along the c-axis. L_{c} ranges from 33.2 Angstrom to 28.9 Angstrom at pressures
from 0.5 to 11.5 kbar. These observations raise serious doubts on the existence
of a phase coherent macroscopic superconducting state in cuprate
superconductors.Comment: 7 pages, 6 figure
Molecular and clinical determinants of drug-induced long QT syndrome: an iatrogenic channelopathy.
More than 70 drugs present on the Swiss market can cause drug-induced long QT syndrome (LQTS), which is associated with torsades de pointes (TdP) arrhythmias, potentially leading to sudden cardiac death. Basic and clinical investigations performed during the last decade have helped a better understanding of the mechanisms and risk factors of this serious public health problem. In their vast majority, QT interval prolonging drugs block the human ERG (hERG) channel involved in the repolarisation phase of the cardiac action potential, and thus lengthen the QT interval. Beside the well-known QT interval prolonging action of class IA, IC and III anti-arrhythmic drugs, many antibiotics, neurotropic, antifungal, and antimalarial drugs are also able to cause drug-induced LQTS. Reviewing the literature indicates that the risk of QT interval prolongation and TdP is increased in females, in patients with organic heart diseases and hypokalaemia. Furthermore in a few cases, genetic factors have also been reported. However thus far, no genetic test is available to detect at-risk patients, and in consequence, drug prescribers are still relying only on the clinical history and findings to perform an evaluation of the risk. Treatment of drug-induced LQTS and TdP includes identifying and withdrawing the culprit drug(s), infusing magnesium and, in resistant cases acceleration of the heart rate. In this review article we provide a list of QT interval prolonging drugs adapted to the pharmaceuticals found on the Swiss market that can be used as a check-list for drug prescribers and at-risk patients
Successful outcome of pregnancy post-allogeneic stem cell transplant despite severe RH1 alloimmunization: A case report.
Pressure effects on the transition temperature and the magnetic field penetration depth in the pyrochlore superconductor RbOs_2O_6
We report magnetization measurements under high hydrostatic pressure in the
newly discovered pyrochlore superconductor RbOs_2O_6 (T_c\simeq6.3K at p=0). A
pronounced and {\it positive} pressure effect (PE) on T_c with dT_c/dp
=0.090(1)K/kbar was observed, whereas no PE on the magnetic penetration depth
\lambda was detected. The relative pressure shift of T_c [ dlnT_c/dp \simeq
1.5%/kbar] is comparable with the highest values obtained for highly underdoped
high-temperature cuprate superconductors. Our results suggest that RbOs_2O_6 is
an adiabatic BCS-type superconductor.Comment: 11 pages, 4 figure
Molecular Dynamics Study of Bamboo-like Carbon Nanotube Nucleation
MD simulations based on an empirical potential energy surface were used to
study the nucleation of bamboo-like carbon nanotubes (BCNTs). The simulations
reveal that inner walls of the bamboo structure start to nucleate at the
junction between the outer nanotube wall and the catalyst particle. In
agreement with experimental results, the simulations show that BCNTs nucleate
at higher dissolved carbon concentrations (i.e., feedstock pressures) than
those where non-bamboolike carbon nanotubes are nucleated
SU(3) Mixing for Excited Mesons
The SU(3)-flavor symmetry breaking and the quark-antiquark annihilation
mechanism are taken into account for describing the singlet-octet mixing for
several nonets assigned by Particle Data Group(PDG). This task is approached
with the mass matrix formalism
Variable Na<sub>v</sub>1.5 Protein Expression from the Wild-Type Allele Correlates with the Penetrance of Cardiac Conduction Disease in the <em>Scn5a</em><sup>+/-</sup> Mouse Model
A partial wave analysis of the centrally produced K+K- and K0K0 systems in pp interactions at 450 GeV/c and new information on the spin of the fJ(1710)
A partial wave analysis of the centrally produced K+K- and K0K0 channels has
been performed in pp collisions using an incident beam momentum of 450 GeV/c.
An unambiguous physical solution has been found in each channel. The striking
feature is the observation of peaks in the S-wave corresponding to the f0(1500)
and fJ(1710) with J = 0. The D-wave shows evidence for the f2(1270)/a2(1320),
the f2(1525) and the f2(2150) but there is no evidence for a statistically
significant contribution in the D-wave in the 1.7 GeV mass region.Comment: 15 pages, Latex, 5 Figure
Intestinal function and transit associate with gut microbiota dysbiosis in cystic fibrosis
Background: Most people with cystic fibrosis (pwCF) suffer from gastrointestinal symptoms and are at risk of gut complications. Gut microbiota dysbiosis is apparent within the CF population across all age groups, with evidence linking dysbiosis to intestinal inflammation and other markers of health. This pilot study aimed to investigate the potential relationships between the gut microbiota and gastrointestinal physiology, transit, and health. Study design: Faecal samples from 10 pwCF and matched controls were subject to 16S rRNA sequencing. Results were combined with clinical metadata and MRI metrics of gut function to investigate relationships. Results: pwCF had significantly reduced microbiota diversity compared to controls. Microbiota compositions were significantly different, suggesting remodelling of core and rarer satellite taxa in CF. Dissimilarity between groups was driven by a variety of taxa, including Escherichia coli, Bacteroides spp., Clostridium spp., and Faecalibacterium prausnitzii. The core taxa were explained primarily by CF disease, whilst the satellite taxa were associated with pulmonary antibiotic usage, CF disease, and gut function metrics. Species-specific ordination biplots revealed relationships between taxa and the clinical or MRI-based variables observed. Conclusions: Alterations in gut function and transit resultant of CF disease are associated with the gut microbiota composition, notably the satellite taxa. Delayed transit in the small intestine might allow for the expansion of satellite taxa resulting in potential downstream consequences for core community function in the colon
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