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 $^{10}B_{4}C$. 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 $\lambda$ = 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 $\Delta_{vo}$ of 145 $\mu$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