1,004 research outputs found
Cardiovascular effects of an arginase II selective inhibitor
For the first time in vitro experiments there were studied the inhibitory activity and safety of potential molecules arginase II selective inhibitors from the group of norleucine derivatives. Also first the substance under the code ZB49-0010C from the group of norleucine derivatives showed the greatest selectivity and inhibitory activity against arginase II in experiments in vitro. However, this substance in vivo exerts dose-dependent hypotensive action and cardioprotective and endothelial protective effects on the L-NAME induced and homocysteine-induced endothelial dysfunction (ED), which are most pronounced at a dose of 10 mg/kg in intragastric administratio
Excitation power and temperature dependence of excitons in CuInSe2
Excitonic recombination processes in high quality CuInSe2 single crystals have been studied by photoluminescence (PL) and reflectance spectroscopy as a function of excitation powers and temperature. Excitation power dependent measurements confirm the identification of well-resolved A and B free excitons in the PL spectra and analysis of the temperature quenching of these lines provides values for activation energies. These are found to vary from sample to sample, with values of 12.5 and 18.4meV for the A and B excitons, respectively, in the one showing the highest quality spectra. Analysis of the temperature and power dependent PL spectra from the bound excitonic lines, labelled M1, M2, and M3 appearing in multiplets points to a likely assignment of the hole involved in each case. The M1 excitons appear to involve a conduction band electron and a hole from the B valence band hole. In contrast, an A valence band hole appears to be involved for the M2 and M3 excitons. In addition, the M1 exciton multiplet seems to be due to the radiative recombination of excitons bound to shallow hydrogenic defects, whereas the excitons involved in M2 and M3 are bound to more complex defects. In contrast to the M1 exciton multiplet, the excitonic lines of M2 and M3 saturate at high excitation powers suggesting that the concentration of the defects involved is low. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4709448
Diamagnetic shift of the A free exciton in CuGaSe2 single crystals
Single crystals of CuGaSe2 were studied using magnetophotoluminescence inmagnetic fields up to 20 T at 4.2 K. The rate of the diamagnetic shift in the A free exciton peak was determined to be 9.82 x 10(-6) eV/T-2. This rate was used to calculate the reduced mass as 0.115m(0), the binding energy as 12.9 meV, the Bohr radius as 5.1 nm and an effective hole mass of 0.64m(0) (m(0) is the free electron mass) of the free A exciton using a low-field perturbation approach and the hydrogenic model
Excited states of the free excitons in CuInSe2 single crystals
High-quality CuInSe2 single crystals were studied using polarization resolved photoluminescence (PL) and magnetophotoluminescence (MPL). The emission lines related to the first (n=2) excited states for the A and B free excitons were observed in the PL and MPL spectra at 1.0481 meV and 1.0516 meV, respectively. The spectral positions of these lines were used to estimate accurate values for the A and B exciton binding energies (8.5 meV and 8.4 meV, respectively), Bohr radii (7.5 nm), band gaps (E-g(A)=1.050 eV and E-g(B)=1.054 eV), and the static dielectric constant (11.3) assuming the hydrogenic model
Inference of the Russian drug community from one of the largest social networks in the Russian Federation
The criminal nature of narcotics complicates the direct assessment of a drug
community, while having a good understanding of the type of people drawn or
currently using drugs is vital for finding effective intervening strategies.
Especially for the Russian Federation this is of immediate concern given the
dramatic increase it has seen in drug abuse since the fall of the Soviet Union
in the early nineties. Using unique data from the Russian social network
'LiveJournal' with over 39 million registered users worldwide, we were able for
the first time to identify the on-line drug community by context sensitive text
mining of the users' blogs using a dictionary of known drug-related official
and 'slang' terminology. By comparing the interests of the users that most
actively spread information on narcotics over the network with the interests of
the individuals outside the on-line drug community, we found that the 'average'
drug user in the Russian Federation is generally mostly interested in topics
such as Russian rock, non-traditional medicine, UFOs, Buddhism, yoga and the
occult. We identify three distinct scale-free sub-networks of users which can
be uniquely classified as being either 'infectious', 'susceptible' or 'immune'.Comment: 12 pages, 11 figure
Characterization of carbon contamination under ion and hot atom bombardment in a tin-plasma extreme ultraviolet light source
Molecular contamination of a grazing incidence collector for extreme
ultraviolet (EUV) lithography was experimentally studied. A carbon film was
found to have grown under irradiation from a pulsed tin plasma discharge. Our
studies show that the film is chemically inert and has characteristics that are
typical for a hydrogenated amorphous carbon film. It was experimentally
observed that the film consists of carbon (~70 at. %), oxygen (~20 at. %) and
hydrogen (bound to oxygen and carbon), along with a few at. % of tin. Most of
the oxygen and hydrogen are most likely present as OH groups, chemically bound
to carbon, indicating an important role for adsorbed water during the film
formation process. It was observed that the film is predominantly sp3
hybridized carbon, as is typical for diamond-like carbon. The Raman spectra of
the film, under 514 and 264 nm excitation, are typical for hydrogenated
diamond-like carbon. Additionally, the lower etch rate and higher energy
threshold in chemical ion sputtering in H2 plasma, compared to
magnetron-sputtered carbon films, suggests that the film exhibits diamond-like
carbon properties.Comment: 18 pages, 10 figure
Anisotropy of effective masses in CuInSe2
Anisotropy of the valence band is experimentally demonstrated in CuInSe2, a key component of the absorber layer in one of the leading thin-film solar cell technology. By changing the orientation of applied magnetic fields with respect to the crystal lattice, we measure considerable differences in the diamagnetic shifts and effective g-factors for the A and B free excitons. The resulting free exciton reduced masses are combined with a perturbation model for non-degenerate independent excitons and theoretical dielectric constants to provide the anisotropic effective hole masses, revealing anisotropies of 5.5 (4.2) for the A (B) valence bands
Numerical and experimental studies of the carbon etching in EUV-induced plasma
We have used a combination of numerical modeling and experiments to study
carbon etching in the presence of a hydrogen plasma. We model the evolution of
a low density EUV-induced plasma during and after the EUV pulse to obtain the
energy resolved ion fluxes from the plasma to the surface. By relating the
computed ion fluxes to the experimentally observed etching rate at various
pressures and ion energies, we show that at low pressure and energy, carbon
etching is due to chemical sputtering, while at high pressure and energy a
reactive ion etching process is likely to dominate
Field studies of anoxic conditions in the Baltic Sea during the cruise of R/V Professor Albrecht Penck in July 2006
Resonant photoemission spectroscopy of Cu(InGa)Se2 materials for solar cells
The electron structure of CuIn1 - x Ga x Se 2 single crystals is determined via resonant photoemis-sion and the main regularities of its transformation upon varying concentration x from 0 to 1 are established. The dependence of the shape of valence band spectra on the photon energy is studied. Integral photoemission intensities are shown to be determined by atomic photoionization cross sections. Processes of the direct and two-step creation of photoelectrons accompanying photoemission and the participation of internal states in the spectra of electrons from valence bands are studied. Two-hole final states in photoemission are obtained upon threshold excitation of the Cu 2p level. The strong interaction of holes leads to the multiplet splitting of these states. Partial densities of the components' states are determined using the energy dependence of atomic photoionization cross sections. © 2013 Allerton Press, Inc
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