300 research outputs found
Oxygen enhanced atomic chain formation
We report experimental evidence for atomic chain formation during stretching
of atomic-sized contacts for gold and silver, that is strongly enhanced due to
oxygen incorporation. While gold has been known for its tendency to form atomic
chains, for silver this is only observed in the presence of oxygen. With oxygen
the silver chains are as long as those for gold, but the conductance drops with
chain length to about 0.1 conductance quantum. A relation is suggested with
previous work on surface reconstructions for silver (110) surfaces after
chemisorption of oxygen.Comment: 4 pages, 4 figure
Vibrationally Induced Two-Level Systems in Single-Molecule Junctions
Single-molecule junctions are found to show anomalous spikes in dI/dV
spectra. The position in energy of the spikes are related to local vibration
mode energies. A model of vibrationally induced two-level systems reproduces
the data very well. This mechanism is expected to be quite general for
single-molecule junctions. It acts as an intrinsic amplification mechanism for
local vibration mode features and may be exploited as a new spectroscopic tool.Comment: 4 pages, 4 figure
Formation and properties of metal-oxygen atomic chains
Suspended chains consisting of single noble metal and oxygen atoms have been
formed. We provide evidence that oxygen can react with and be incorporated into
metallic one-dimensional atomic chains. Oxygen incorporation reinforces the
linear bonds in the chain, which facilitates the creation of longer atomic
chains. The mechanical and electrical properties of these diatomic chains have
been investigated by determining local vibration modes of the chain and by
measuring the dependence of the average chain-conductance on the length of the
chain. Additionally, we have performed calculations that give insight in the
physical mechanism of the oxygen-induced strengthening of the linear bonds and
the conductance of the metal-oxygen chains.Comment: 10 pages, 9 fig
Tuning the oriented deposition of gold nanorods on patterned substrates
The controlled patterning of anisotropic gold nanoparticles is of crucial importance for many applications related to their optical properties. In this paper, we report that gold nanorods prepared by a seed-mediated synthesis protocol (without any further functionalization) can be selectively deposited on hydrophilic parts of hydrophobic–hydrophilic contrast patterned substrates. We have seen that, when nanorods with lengths much smaller than the width of the hydrophilic stripe are used, they disperse on these stripes with random orientation and tunable uniform particle separation. However, for nanorods having lengths comparable to the width of the hydrophilic stripes, confinement-induced alignment occurs. We observe that different interactions governing the assembly forces can be modulated by controlling the concentration of assembling nanorods and the width of the hydrophilic stripes, leading to markedly different degrees of alignment. Our strategy can be replicated for other anisotropic nanoparticles to produce well-controlled patterning of these nanoentities on surfaces
The erythrocyte membrane in human muscular dystrophy
More than 250 different forms of human neuromuscular
diseases are known. They differ in age of onset, severity
of weakness, rate of progression, type of inheritance,
groups of muscles affected, frequency of incidence.
Sometimes the clinical symptoms are not restricted to
nervous and/or muscular tissue. The muscular dystrophies
form an extensive subdivision of the neuromuscular
diseases. This group of disorders is inheritable and it
is accompanied by progressive weakness and degeneration
of skeletal muscle. The aetiology is not known. The most
progressive type of the dystrophies is the Duchenne form,
first described in detail by Duchenne de Boulogne in
1868 (83) . Another representative, with several
dissimilarities with the Duchenne type, is the myotonic
dystrophy, also called dystrophia myotonica, myotonia
atrophica or Steinert•s disease. This disorder shows,
apart from dystrophic characteristics, myotonic symptoms,
i.e. there exists a delay in relaxation of the affected
muscles after contraction. The myotonic and Duchenne types
are the most frequently occurring forms of human muscular
dystrophy. These types of muscular dystrophy have been the
subject of this thesis, and details of the disorders will
be given first
Efficient seed-mediated method for the large-scale synthesis of Au nanorods
Quantum Matter and Optic
One-step synthesis of cetyltrimethylammonium bromide stabilized spherical gold nanoparticles
Quantum Matter and Optic
The signature of subsurface Kondo impurities in the local tunnel current
The conductance of a tunnel point-contact in an STM-like geometry having a
single defect placed below the surface is investigated theoretically. The
effect of multiple electron scattering by the defect after reflections by the
metal surface is taken into account. In the approximation of s-wave scattering
the dependence of the conductance on the applied voltage and the position of
the defect is obtained. The results are illustrated for a model s-wave phase
shift describing Kondo-resonance scattering. We demonstrate that multiple
electron scattering by the magnetic impurity plays a decisive role in the
point-contact conductance at voltages near the Kondo resonance. We find that
the sign and shape of the Kondo anomaly depends on the position of the defect.Comment: 13 pages, 4 figures. To be published in J. Phys.: Cond. Ma
An Asymptomatic Case of Wolff-Parkinson-White Syndrome with Right-sided Free-wall Accessory Pathway and Left Ventricular Dysfunction
AbstractA 16-year-old girl with a known history of asymptomatic Wolff-Parkinson-White syndrome exhibited signs of left ventricular (LV) septal akinesia and LV dysfunction during routine follow-up. A 12-lead surface ECG showed pre-excitation, a predominantly negative delta wave in V1 and left axis deviation, which was consistent with the presence of a right free-wall accessory pathway. Radiofrequency ablation of the anterolateral right atrium around the local shortest atrium-to-ventricle interval created the accessory pathway block. An echocardiogram taken one month after the procedure revealed that LV septal wall motion had normalized and that LV ejection fraction had improved from 50% before the ablation to 64% after the ablation. Most previous reports of asymptomatic patients of WPW with LV septal dyskinesia and dysfunction have described right septal or posteroseptal accessory pathways. This patient reported here represents a rare case with right free-wall accessory pathway and LV dysfunction without tachycardia
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