Creating pseudo Kondo-resonances by field-induced diffusion of atomic hydrogen

In low temperature scanning tunneling microscopy (STM) experiments a cerium adatom on Ag(100) possesses two discrete states with significantly different apparent heights. These atomic switches also exhibit a Kondo-like feature in spectroscopy experiments. By extensive theoretical simulations we find that this behavior is due to diffusion of hydrogen from the surface onto the Ce adatom in the presence of the STM tip field. The cerium adatom possesses vibrational modes of very low energy (3-4meV) and very high efficiency (> 20%), which are due to the large changes of Ce-states in the presence of hydrogen. The atomic vibrations lead to a Kondo-like feature at very low bias voltages. We predict that the same low-frequency/high-efficiency modes can also be observed at lanthanum adatoms.Comment: five pages and four figure

Cellular and receptor mechanisms of impairment of myocardium and aorta contractility at Alzheimer's disease model

Introduction: Recent studies certify the existence of link between Alzheimer's disease and cardiovascular pathology, however the mechanisms of this phenomenon is unclear. Here we studied the influence of Alzheimer's β-amyloid peptide (βAP) on the contractility of rat myocardium and aorta. Material and methods: Contractility of myocardium ventricle strips and transverse fragments of abdominal aorta was measured at Power Lab setup using conventional myographic technique. Contractile responses of aorta strips were evoked by application of receptor agonists, contractile responses of myocardium - by electrical stimulation. Contractile responses of aorta strips after application of carbachol (10-6-10-4 M), histamine (10 -6-10-4 M), norepinephrine (10-5-10 -3 M) and ATP (10-6-10-4 M) were measured. Results and discussion: We found the impairment of carbachol- and histamine-induced contractility of aorta, appearing as perverse contractile reactions (relaxation instead of contraction) under the action of βAP (10-6 M). Next, we found βAP-induced impairments of ventricle myocardium contractility, appearing as decrease of relaxation phase duration and increase of relaxation speed (positive lusitropic effect). Also, own positive lusitropic effect of norepinephrine was absent in presence of βAP (10 -6M). Thus, βAP(25-35) significantly impairs the contractility of rat myocardium and aorta, as well as processes of its regulation. Obtained data significantly broad our understanding of mechanisms of Alzheimer's disease pathogenesis and pathophysiology of cardiovascular system

Electron scattering in atomic force microscopy experiments

It has been shown that electron transitions, as measured in a scanning tunnelling microscope (STM), are related to chemical interactions in a tunnelling barrier. Here, we show that the shape and apparent height of subatomic features in an atomic force microscopy (AFM) experiment on Si(111) depend directly on the available electron states of the silicon surface and the silicon AFM tip. Simulations and experiments confirm that forces and currents show similar subatomic variations for tip-sample distances approaching the bulk bonding length.Comment: 5 pages and 4 figure

Higher-order contributions to the Rashba-Bychkov effect with application to Bi/Ag(111) surface alloy

In order to explain the anisotropic Rashba-Bychkov effect observed in several metallic surface-state systems, we use k.p perturbation theory with a simple group-theoretical analysis and construct effective Rashba Hamiltonians for different point groups up to third order in the wavenumber. We perform relativistic ab initio calculations for the Bi/Ag(111) ordered surface alloy and from the calculated splitting of the band dispersion we find evidence of the predicted third-order terms. Furthermore, we derive expressions for the corresponding third-order Rashba parameters to provide a simple explanation to the qualitative difference concerning the Rashba-Bychkov splitting of the surface states at Au(111) and Bi/Ag(111).Comment: 7 pages, 3 figure

Role of hydrogen in giant spin polarization observed on magnetic nanostructures

We demonstrate that the giant spin contrast observed by scanning tunneling microscopy for double-layer Coislands on Pt(111) is caused by adsorbates at the apex of the Cr-coated W tip. The most likely candidate, in ab initio simulations, is hydrogen. Here, the electron charge is highly polarized by the adjacent Cr layers. The hydrogen adsorption site is shown to change from hollow to on top due to the electric field at the tip apex, created by the tunnel voltage

Deformability Tests of Pure Niobium

research team at the University of Miskolc's Faculty of Materials Science and Technology has signed a cooperation agreement with the Geneva-based European Organization for Nuclear Research (CERN) for testing of the materials employed in the Crab Cavities will be installed in the next generation of the LHC (the so-called High Luminosity Large Hadron Collider – HL-LHC). At the University of Miskolc, high purity niobium rolling experiments were carried out in conventional (unidirectional) and cross-rolled manners in order to increase the deep drawability of the final sheet. The deformability of niobium was measured by Watts- Ford and compression tests. The microstructure and anisotropy (texture) results of the initial material and the straight-rolled products are reported

Gene expression biomarkers of response to citalopram treatment in major depressive disorder

There is significant variability in antidepressant treatment outcome, with ∼30–40% of patients with major depressive disorder (MDD) not presenting with adequate response even following several trials. To identify potential biomarkers of response, we investigated peripheral gene expression patterns of response to antidepressant treatment in MDD. We did this using Affymetrix HG-U133 Plus2 microarrays in blood samples, from untreated individuals with MDD (N=63) ascertained at a community outpatient clinic, pre and post 8-week treatment with citalopram, and used a regression model to assess the impact of gene expression differences on antidepressant response. We carried out technical validation of significant probesets by quantitative reverse transcriptase PCR and conducted central nervous system follow-up of the most significant result in post-mortem brain samples from 15 subjects who died during a current MDD episode and 11 sudden-death controls. A total of 32 probesets were differentially expressed according to response to citalopram treatment following false discovery rate correction. Interferon regulatory factor 7 (IRF7) was the most significant differentially expressed gene and its expression was upregulated by citalopram treatment in individuals who responded to treatment. We found these results to be concordant with our observation of decreased expression of IRF7 in the prefrontal cortex of MDDs with negative toxicological evidence for antidepressant treatment at the time of death. These findings point to IRF7 as a gene of interest in studies investigating genomic factors associated with antidepressant response