Contribution of secondary currents to momentum fluxes in natural river flows

River hydrodynamicsBed roughness and flow resistanc

Magnetotransport in the presence of a longitudinal barrier: multiple quantum interference of edge states

Transport in a two-dimensional electron gas subject to an external magnetic field is analyzed in the presence of a \textit{longitudinal barrier.} We show that \textit{quantum interference of the edge states} bound by the longitudinal barrier results in a drastic change of the electron motion: the degenerate discrete Landau levels are transformed into an alternating sequence of energy bands and energy gaps. These features of the electron spectrum should result in a high sensitivity of thermodynamic and transport properties of the 2D electron gas to external fields. In particular, we predict giant oscillations of the ballistic conductance and discuss nonlinear current-voltage characteristics, coherent Bloch oscillations and effects of impuritiesComment: 4 pages, 3 figure

Temperature dependent transient surface photovoltage spectroscopy of a Cu1.95Zn1.1Sn0.96Se4 kesterite single phase powder

An off-stoichiometric but single phase Cu1.95Zn1.1Sn0.96Se4 kesterite powder was investigated by temperature dependent transient surface photovoltage (SPV) spectroscopy. SPV signals excited at different wavelengths were transformed into SPV spectra that depended on the response time of measurement. Shallow electronic states and states with transition energies at 0.83 eV or 0.78… 0.9 eV were distinguished. The temperature dependence of the band gap of Cu1.95Zn1.1Sn0.96Se4 was obtained. Results were discussed on the basis of defects in Cu-poor and Zn-rich kesterite

Charge Generation and Selective Separation at PbS Quantum Dot Metal Oxide Interfaces

Charge separation and transfer at the interface between layers of oleic acid capped PbS quantum dots QDs and Titanium and Indium Tin oxide TiO2 and ITO films were investigated by surface photovoltage SPV measurements. Photoluminescence PL measurements were performed in order to check for excitonic transitions and determine the QD band gaps. The QDs diameter of 4.2 nm and 5.0 nm were estimated by using the PL band gaps and the theoretical equation derived by Wang et al. [J. Chem. Phys. 87 1987 7315]. The SPV spectra of the PbS QDs TiO2 system reveal a positive charge on the PbS film surface and show three distinguished regions which demonstrate i the charge separation across QDs, ii the electron injection from QDs into TiO2 and iii the fundamental absorption in TiO2. The on set of the electron injection depends on the QD size QD band gap it shifts to lower photon energies for lower QD dimensions for higher QD band gaps . Thus, a better conduction band alignment is achieved in the latter case. In contrast to PbS QDs TiO2, the SPV spectra of the PbS QDs ITO structure reveal the negative charge on PbS surface. Moreover, the charge transfer at this interface is not observed. Instead, the SPV peculiarities in the photon energy range 1.4 3.0 eV point out to trapped holes on the ITO surface state

Hybridization in parasites: consequences for adaptive evolution, pathogenesis and public health in a changing world

[No abstract available

Giant tunable magnetoresistance of electrically gated graphene ribbon with lateral interface under magnetic field

Quantum dynamics and kinetics of electrically gated graphene ribbons with lateral n–p and n–p–n junctions under magnetic field are investigated. It is shown that the snake-like states [C. W. J. Beenakker, Rev. Mod. Phys. 80, 1337 (2008)] of quasiparticles skipping along the n–p interface do not manifest themselves in the main semi-classical part of the ribbon conductance. Giant oscillations of the conductance of a ribbon with an n–p–n junction are predicted and analytically calculated. Depending on the number of junctions inside the ribbon its magneto-resistance may be controllably changed by 50%–90% by an extremely small change of the magnetic field or the gate voltage