606 research outputs found
Serbia's Action against Transnational Organised Crime
This article examines the extent to which Serbia has implemented relevant international standards on action against transnational organised crime contained in the United Nations Convention against Transnational Organised Crime 2000. The first part explores key obligations with particular reference to prohibition of substantive offences, intelligence-led law enforcement (special investigative techniques), confiscation of criminal proceeds, as well as international law enforcement cooperation. The second part of the article analyses how these obligations are implemented by Serbia in reality by examining legislative frameworks as well as law enforcement practices. The main conclusion is that, while Serbia has taken some steps to implement international standards with a view to enhancing individual and collective actions against transnational organised crime, effective law enforcement is hampered by issues such as corruption and a lack of expertise, experience and resources
Superconductor-Ferromagnet Bi-Layers: a Comparison of s-Wave and d-Wave Order Parameters
We study superconductor-ferromagnet bi-layers, not only for s-wave but also
for d-wave superconductors. We observe oscillations of the critical temperature
when varying the thickness of the ferromagnetic layer for both s-wave and
d-wave superconductors. However, for a rotated d-wave order parameter the
critical temperature differs considerably from that for the unrotated case. In
addition we calculate the density of states for different thicknesses of the
ferromagnetic layer; the results reflect the oscillatory behaviour of the
superconducting correlations.Comment: 11 pages, 5 figures, accepted for publication in J. Phys.: Condens.
Matte
Photocatalytic degradation of metoprolol tartrate in suspensions of two TiO2-based photocatalysts with different surface area. Identification of intermediates and proposal of degradation pathways.
This study investigates the efficiency of the photocatalytic degradation of metoprolol tartrate (MET), a widely used β 1-blocker, in TiO 2 suspensions of Wackherr's " Oxyde de titane standard" and Degussa P25. The study encompasses transformation kinetics and efficiency, identification of intermediates and reaction pathways. In the investigated range of initial concentrations (0.01-0.1mM), the photocatalytic degradation of MET in the first stage of the reaction followed approximately a pseudo-first order kinetics. The TiO 2 Wackherr induced a significantly faster MET degradation compared to TiO 2 Degussa P25 when relatively high substrate concentrations were used. By examining the effect of ethanol as a scavenger of hydroxyl radicals (OH), it was shown that the reaction with OH played the main role in the photocatalytic degradation of MET. After 240min of irradiation the reaction intermediates were almost completely mineralized to CO 2 and H 2O, while the nitrogen was predominantly present as NH4+. Reaction intermediates were studied in detail and a number of them were identified using LC-MS/MS (ESI+), which allowed the proposal of a tentative pathway for the photocatalytic transformation of MET as a function of the TiO 2 specimen
Structural importance of Stone-Thrower-Wales defects in rolled and flat graphenes from surface-enhanced Raman scattering
We first survey the historical aspects of the term Stone-Thrower-Wales (STW) defect and its experimental identification. Physicochemical properties associated with the STW defect have been extensively investigated theoretically as well. However, it is difficult to verify the predicted properties by means of experiments. Here we demonstrate an experimental way to probe the vibrational properties of STW defects in single-wall carbon nanotubes (SWCNTs) using surface-enhanced Raman scattering (SEAS). We also performed density functional theory calculations to support our interpretation of the SERS spectra. The characteristic fluctuations of peak intensities and frequencies are ascribed to dynamic motion of an STW defect in the hexagonal SWCNT lattice. The role of an STW defect at edges is also discussed in terms of its relevance to the stability and O-2 reactivity of flat and curved graphene structures.ArticleCARBON. 50(9):3274-3279 (2012)journal articl
Bulk electronic structure of superconducting LaRu2P2 single crystals measured by soft x-ray angle-resolved photoemission spectroscopy
We present a soft X-ray angle-resolved photoemission spectroscopy (SX-ARPES)
study of the stoichiometric pnictide superconductor LaRu2P2. The observed
electronic structure is in good agreement with density functional theory (DFT)
calculations. However, it is significantly different from its counterpart in
high-temperature superconducting Fe-pnictides. In particular the bandwidth
renormalization present in the Fe-pnictides (~2 - 3) is negligible in LaRu2P2
even though the mass enhancement is similar in both systems. Our results
suggest that the superconductivity in LaRu2P2 has a different origin with
respect to the iron pnictides. Finally we demonstrate that the increased
probing depth of SX-ARPES, compared to the widely used ultraviolet ARPES, is
essential in determining the bulk electronic structure in the experiment.Comment: 4 pages, 4 figures, 1 supplemental material. Accepted for publication
in Physical Review Letter
Trivial topological phase of CaAgP and the topological nodal-line transition in CaAg(P1-xAsx)
By performing angle-resolved photoemission spectroscopy and first-principles
calculations, we address the topological phase of CaAgP and investigate the
topological phase transition in CaAg(P1-xAsx). We reveal that in CaAgP, the
bulk band gap and surface states with a large bandwidth are topologically
trivial, in agreement with hybrid density functional theory calculations. The
calculations also indicate that application of "negative" hydrostatic pressure
can transform trivial semiconducting CaAgP into an ideal topological nodal-line
semimetal phase. The topological transition can be realized by partial
isovalent P/As substitution at x = 0.38.Comment: 20 pages, 4 figure
Controllable pi junction in a Josephson quantum-dot device with molecular spin
We consider a model for a single molecule with a large frozen spin sandwiched
in between two BCS superconductors at equilibrium, and show that this system
has a junction behavior at low temperature. The shift can be
reversed by varying the other parameters of the system, e.g., temperature or
the position of the quantum dot level, implying a controllable junction
with novel application as a Josephson current switch. We show that the
mechanism leading to the shift can be explained simply in terms of the
contributions of the Andreev bound states and of the continuum of states above
the superconducting gap. The free energy for certain configuration of
parameters shows a bistable nature, which is a necessary pre-condition for
achievement of a qubit
Josephson current in superconductor-ferromagnet structures with a nonhomogeneous magnetization
We calculate the dc Josephson current for two types of
superconductor-ferromagnet (S/F) Josephson junctions. The junction of the first
type is a S/F/S junction. On the basis of the Eilenberger equation, the
Josephson current is calculated for an arbitrary impurity concentration. If the expression for the Josephson critical current is reduced
to that which can be obtained from the Usadel equation ( is the exchange
energy, is the momentum relaxation time). In the opposite limit
the superconducting condensate oscillates with period and
penetrates into the F region over distances of the order of the mean free path
. For this kind of junctions we also calculate in the case when the F
layer presents a nonhomogeneous (spiral) magnetic structure with the period
. It is shown that for not too low temperatures, the -state which
occurs in the case of a homogeneous magnetization (Q=0) may disappear even at
small values of . In this nonhomogeneous case, the superconducting
condensate has a nonzero triplet component and can penetrate into the F layer
over a long distance of the order of . The junction
of the second type consists of two S/F bilayers separated by a thin insulating
film. It is shown that the critical Josephson current depends on the
relative orientation of the effective exchange field of the bilayers. In
the case of an antiparallel orientation, increases with increasing .
We establish also that in the F film deposited on a superconductor, the
Meissner current created by the internal magnetic field may be both diamagnetic
or paramagnetic.Comment: 13 pages, 11 figures. To be published in Phys. Rev.
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