Oxygen reduction on polycrystalline Au modified by nanosized Pd islands

Oxygen reduction reaction was studied on polycrystalline gold, Au(poly), modified by nanosized palladium islands. Linear sweep voltammetry measurements were performed using rotating Au-disk electrode in oxygen saturated 0.05 M H2SO4 solution. Morphology of obtained Pd/Au(poly) electrodes was characterized by tapping-mode atomic force microscopy, after each deposition from Pd containing solution. Only homogeneous distribution of deposited Pd islands nonuniform in size is observed. Active surface area of the deposited Pd was estimated from cyclic voltammetry profiles. Obtained Pd/Au(poly) surfaces have shown a significant catalytic activity towards oxygen reduction reaction which increases with the increase of the active surface area

Erratum: Systematic uncertainties in integrated luminosity measurement at CEPC (Journal of Instrumentation (2022) 17 (P09014) DOI: 10.1088/1748-0221/17/09/P09014)

The very forward region is one of the most challenging regions to instrument at a future + − collider. At CEPC, machine-detector interface includes, among others, a calorimeter dedicated for precision measurement of the integrated luminosity at a per mill level or better. Here we review a feasibility of such precision, from the point of view of systematic effects arising from luminometer mechanical precision and positioning, beam-related requirements and physics background from two-photon processes. The impact of the beam energy spread and its uncertainty on the integrated luminosity precision is also discussed, as well as the achievable beam energy spread precision with the post-CDR CEPC beamsLink to the corrected article: [https://vinar.vin.bg.ac.rs/handle/123456789/10567

Uloga receptora za epidermalni faktor rasta u trombinom regulisanoj proliferaciji glatkih mišićnih ćelija krvnih sudova

Zajednički činilac u nastanku vaskularnih oboljenja kao što su ateroskleroza, restenoza i hipertenzija je patološka proliferacija i akumulacija glatkih mišićnih ćelija krvnog suda (VSMC) u njegov unutrašnji (intima) sloj. Trombin, ključni hormon koagulacionoaterogenetske mreže posreduje u regulisanju tonusa i propustljivosti krvnih sudova, migracije i proliferacije VSMC, privlačenja monocita i raznih proinflamatornih markera u aterosklerotske lezije i svoje efekte ostvaruje direktno kao serinska proteinaza i aktivacijom svojih receptora spregnutih sa G proteinom (GPCR). Pokazano je da trombin posreduje u proliferaciji VSMC transaktivacijom receptora za epidermalni faktor rasta (EGFR). Proces transaktivacije EGFR preko aktivacije trombinskih receptora, uključuje metaloproteinaze koje generišu ligande proteolitičkim cepanjem membranskih prekursora, kao što je heparin vezujući epidermalni faktor rasta (HB-EGF) koji se vezuje za EGFR i aktivira ga, što vodi proliferaciji VSMC preko nishodnih, signalnih puteva mitogenom aktiviranih protein kinaza (MAPK). U okviru ovog preglednog članka su prikazani i diskutovani novi literaturni podaci koji se odnose na: ulogu aktivacije EGFR u posredovanju proliferativnog efekta trombina na VSMC, razumevanje i reviziju koncepta trostruke kaskade transaktivacije EGFR stimulisane trombinom u mehanizmu proliferacije VSMC.The common factor in the development of vascular diseases, such as atherosclerosis, hypertension and restenosis, is excessive accumulation and proliferation of vascular smooth muscle cells (VSMC) within inner (intima) layer of vessel wall. Thrombin, a key player in athero-coagulation maze, mediates the regulation of vascular permeability and contraction, migration and proliferation of VSMC, attracting monocytes and a variety of proinflammatory markers in atherosclerotic lesions. Thrombin exerts its effects either directly as serine proteinases and/or via activation of its G proteins coupled receptors (GPCR). It has been shown that thrombin mediates transactivation of epidermal growth factor receptor (EGFR) within the process of VSMC proliferation. EGFR transactivation process through the activation of thrombin protease activated receptor (PAR), includes a matrix metalloproteinase cleavage of membrane ligands precursors such as epidermal growth factor like growth factor that binds heparin (HB-EGF) that binds to the EGFR and activates it, leading to VSMC proliferation via downstream signaling pathways of mitogen activated protein kinase (MAPK). This review article presents review of the new literature data concerning: the role of EGFR activation in mediating the proliferative effect of thrombin in VSMC and understanding of the concept of the triple cascade of EGFR transactivation stimulated by thrombin in the mechanism of VSMC proliferation

Correction of beam-beam effects in luminosity measurement in the forward region at CLIC

Procedures for correcting the beam-beam effects in luminosity measurement at CLIC at 3 TeV CM energy are described and tested using Monte Carlo simulations: - Correction of the angular counting loss due to the combined Beamstrahlung and initial-state radiation (ISR) effects, based on the reconstructed velocity of the collision frame of the Bhabha scattering. - Deconvolution of the luminosity spectrum distortion due to the ISR emission. - Correction of the counting bias due to the finite calorimeter energy resolution. All procedures were tested by simulation. Bhabha events were generated using BHLUMI, and used in Guinea-PIG to simulate the outgoing momenta of Bhabha particles in the bunch collisions at CLIC. Residual uncertainties after correction are listed in a table in the conclusions. The beam-beam related systematic counting uncertainty in the luminosity peak can be reduced to the order of permille.Procedures for correcting the beam-beam effects in luminosity measurements at CLIC at 3 TeV center-of-mass energy are described and tested using Monte Carlo simulations. The angular counting loss due to the combined Beamstrahlung and initial-state radiation effects is corrected based on the reconstructed velocity of the collision frame of the Bhabha scattering. The distortion of the luminosity spectrum due to the initial-state radiation is corrected by deconvolution. At the end, the counting bias due to the finite calorimeter energy resolution is numerically corrected. To test the procedures, BHLUMI Bhabha event generator, and Guinea-Pig beam-beam simulation were used to generate the outgoing momenta of Bhabha particles in the bunch collisions at CLIC. The systematic effects of the beam-beam interaction on the luminosity measurement are corrected with precision of 1.4 permille in the upper 5% of the energy, and 2.7 permille in the range between 80 and 90% of the nominal center-of-mass energy.Procedures for correcting the beam-beam effects in luminosity measurements at CLIC at 3 TeV center-of-mass energy are described and tested using Monte Carlo simulations. The angular counting loss due to the combined Beamstrahlung and initial-state radiation effects is corrected based on the reconstructed velocity of the collision frame of the Bhabha scattering. The distortion of the luminosity spectrum due to the initial-state radiation is corrected by deconvolution. At the end, the counting bias due to the finite calorimeter energy resolution is numerically corrected. To test the procedures, BHLUMI Bhabha event generator, and Guinea-Pig beam-beam simulation were used to generate the outgoing momenta of Bhabha particles in the bunch collisions at CLIC. The systematic effects of the beam-beam interaction on the luminosity measurement are corrected with precision of 1.4 permille in the upper 5% of the energy, and 2.7 permille in the range between 80 and 90% of the nominal center-of-mass energy

Vista parcial de las Salinas Cabo de Gata

A method of investigation of semiconductors and metal–semiconductor structures based on two techniques: The elastic bending technique and pyropiezoelectric (PPE) technique was presented. The method was demonstrated on a metal–semiconductor–metal (MSM) structure, which is attached to a PPE detector. Two different ac voltages can be measured: One on the electrodes of MSM structure—the ac-photovoltage, and another on the electrodes of the PPE detector—the PPE voltage. The ac photovoltage is a consequence of the photogenerated plasma processes in the sample (MSM structure). Photogenerated plasma waves in a semiconductor are followed by the thermal and elastic waves (the elastic bending). Then, the pyroelectric voltage is a consequence of the thermal processes and the piezoelectric voltage is a consequence of elastic bending in the sample-PPE detector system. A theoretical model for a metal–semiconductor–metal-pyro(piezo)electric system is given including the space-charge regions and electronic states on the semiconductor surfaces, thermodiffusion, thermoelastic, and electronic deformation effects in a semiconductor. The photoelectric and pyropiezoelectric effects are investigated by analyzing the ac voltages as a function of the modulation frequency of excitation beam.Conference: 12th International Conference on Photoacoustic and Photothermal Phenomena (12 ICPPP) Location: Toronto, Canada; Date: JUN 24-27, 200

The Schottky barrier contribution to photoacoustic effect in Au-Si system

The photoacoustic effect in metal-semiconductor system, i.e., the influence of Schottky barrier on the thermal and electronic transport processes in semiconductor was investigated. The amplitude and phase spectra were measured for dependence on the modulation frequency of excitation optical beam, using the PA frequency transmission technique. Thermal, elastic and electronic transport parameters were obtained by the analysis of experimental and theoretical PA signals, including the Schottky barrier effect, for a metal film-semiconductor substrate sample. © 1999 IEEE

Extrinsic origin of the insulating behavior of polygrain icosahedral Al-Pd-Re quasicrystals

Polygrain icosahedral i-Al-Pd-Re quasicrystals are known to exhibit dramatically different electronic transport properties to other Al-based quasicrystals. By performing comparative experimental and theoretical studies of the electronic transport and electronic structure of polygrain and monocrystalline i-Al-Pd-Re samples, we show that the extraordinarily high electrical resistivity and the metal-to-insulator transition in the polygrain material are not intrinsic properties of the quasiperiodic lattice, but are of extrinsic origin due to the high porosity and the oxygen-rich weakly insulating regions in the material. We also compare theoretical electronic structures and experimental electrical resistivities of monocrystalline i-Al-Pd-Re and i-Al-Pd-Mn quasicrystals and show that there are no significant differences between these two isomorphous compounds, suggesting that i-Al-Pd-Re is on common ground with other Al-based quasicrystals. We present a structural model of i-Al-Pd-Re.This article is published as Dolinšek, J., Paul J. McGuiness, M. Klanjšek, I. Smiljanić, A. Smontara, E. S. Zijlstra, S. K. Bose, I. R. Fisher, M. J. Kramer, and P. C. Canfield. "Extrinsic origin of the insulating behavior of polygrain icosahedral Al− Pd− Re quasicrystals." Physical Review B 74, no. 13 (2006): 134201. DOI: 10.1103/PhysRevB.74.134201. Copyright 2006 American Physical Society. Posted with permission