5,006 research outputs found
Quasi-one-dimensional system as a high-temperature superconductor
It is well-known that quasi-one-dimensional superconductors suffer from the
pairing fluctuations that significantly reduce the superconducting temperature
or even completely suppress any coherent behavior. Here we demonstrate that a
coupling to a robust pair condensate changes the situation dramatically. In
this case the quasi-one-dimensional system can be a high temperature
superconductor governed by the proximity to the Lifshitz transition at which
the Fermi level approaches the lower edge of the single-particle spectrum.Comment: 5 pages, 1 figur
Physical mechanisms of interface-mediated intervalley coupling in Si
The conduction band degeneracy in Si is detrimental to quantum computing
based on spin qubits, for which a nondegenerate ground orbital state is
desirable. This degeneracy is lifted at an interface with an insulator as the
spatially abrupt change in the conduction band minimum leads to intervalley
scattering. We present a theoretical study of the interface-induced valley
splitting in Si that provides simple criteria for optimal fabrication
parameters to maximize this splitting. Our work emphasizes the relevance of
different interface-related properties to the valley splitting.Comment: 4 pages, revised versio
Timing resistive plate chambers for thermal neutron detection with 3D position sensitivity
An optimized design of a neutron detector based on timing RPCs (Resistive
Plate Chambers) with boron-10 neutron converters is presented. The detector is
composed of a stack of ten double gap RPCs with aluminium cathode plates coated
on both sides with . This design enables simultaneous
determination with high accuracy of both the neutron time-of-flight (down to ns
resolution) and the interaction position in 3D (down to 0.25 mm resolution
across and ~1 mm along the beam). It is shown that the detection efficiency can
approach 60% for neutrons with = 4.7 \.A. A new geometry with less
material budget is introduced for the signal pick-up strip arrays. The results
of simulation-based optimization of the design are reported considering the
trade-off between the detection efficiency, the count rate capability and the
amount of elastic scattering on the detector components
Anticancer ruthenium(ii) tris(pyrazolyl)methane complexes with bioactive co-ligands
In comparison with RuII-arene compounds, the medicinal potential of homologous RuII-tpm compounds [tpm = tris(pyrazolyl)methane] is underexplored. Pyridine, 4-pyridinemethanol and four functionalized pyridines, synthesized from the esterification of 4-pyridinemethanol with bioactive carboxylic acids (i.e., ethacrynic acid, ibuprofen, flurbiprofen and naproxen), react with the precursor [RuCl(κ3-tpm)(PPh3)2]Cl (1) to afford [RuCl(κ3-tpm)(PPh3)(L)]Cl (2-7, L = pyridine ligand), in 78-91% yields. All products were fully characterized by HR-ESI mass spectrometry, IR and multinuclear NMR spectroscopy and the solid-state structures of two of the complexes, i.e. where L = pyridine and 4-pyridinemethanol, were ascertained by single crystal X-ray diffraction. The {Ru-tpm-PPh3} assembly is stable in D2O and in biological medium (DMEM) at 37 °C, with a tendency to slowly dissociate the pyridine ligand. The antiproliferative activity of the complexes was assessed on the cancerous A2780 and A2780cisR cell lines, and the nontumoral HEK 293T cell line; moreover inhibition assays were carried out on the complexes towards COX-2 and GSTP1 enzymes
Introduction: Turnaround and let-down: making sense of Brazil and Africa after the surge
By improving political connections under a common South-South aegis, promoting new trade opportunities and expanding the disbursement of significant amounts of development cooperation, Brazil quickly secured a foothold of its own in Africa between 2003 and 2014. However, in the face of a political meltdown and of controversial judicial investigations back home, Brazil’s inversions in Africa have since then essentially collapsed. This abrupt turnaround calls for a more critical exegesis of the years of expansion. What were the main successes and failures of Brazil’s overall strategy towards Africa? And what does the dramatic change of events, with Brazil moving from a pivotal player to an almost invisible one in merely half a decade, tell us about the possibility of a new pick-up of interest for Africa? This introduction to the edited volume takes stock of the main trends in previous literature over the character and content of Brazil’s foreign policy towards the continent and sets the ground for the following chapters.info:eu-repo/semantics/acceptedVersio
PAR6C polarity protein expression pattern in male and female bovine embryos.
Proceedings of the 28th Annual Meeting of the Brazilian Embryo Technology Society (SBTE), August 14 to 17th, 2014, Natal, RN, Brazil. Abstracts
Dispersively detected Pauli Spin-Blockade in a Silicon Nanowire Field-Effect Transistor
We report the dispersive readout of the spin state of a double quantum dot
formed at the corner states of a silicon nanowire field-effect transistor. Two
face-to-face top-gate electrodes allow us to independently tune the charge
occupation of the quantum dot system down to the few-electron limit. We measure
the charge stability of the double quantum dot in DC transport as well as
dispersively via in-situ gate-based radio frequency reflectometry, where one
top-gate electrode is connected to a resonator. The latter removes the need for
external charge sensors in quantum computing architectures and provides a
compact way to readout the dispersive shift caused by changes in the quantum
capacitance during interdot charge transitions. Here, we observe Pauli
spin-blockade in the high-frequency response of the circuit at finite magnetic
fields between singlet and triplet states. The blockade is lifted at higher
magnetic fields when intra-dot triplet states become the ground state
configuration. A lineshape analysis of the dispersive phase shift reveals
furthermore an intradot valley-orbit splitting of 145 eV.
Our results open up the possibility to operate compact CMOS technology as a
singlet-triplet qubit and make split-gate silicon nanowire architectures an
ideal candidate for the study of spin dynamics
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