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Ferrer J.,University of Oviedo | Ferrer J.,Nanomaterials and Nanotechnology Research Center | Ferrer J.,Lancaster University | Lambert C.J.,Lancaster University | And 14 more authors.
New Journal of Physics | Year: 2014

We have developed an efficient simulation tool 'GOLLUM' for the computation of electrical, spin and thermal transport characteristics of complex nanostructures. The new multi-scale, multi-terminal tool addresses a number of new challenges and functionalities that have emerged in nanoscale-scale transport over the past few years. To illustrate the flexibility and functionality of GOLLUM, we present a range of demonstrator calculations encompassing charge, spin and thermal transport, corrections to density functional theory such as local density approximation +U (LDA+U) and spectral adjustments, transport in the presence of non-collinear magnetism, the quantum Hall effect, Kondo and Coulomb blockade effects, finite-voltage transport, multi-terminal transport, quantum pumps, superconducting nanostructures, environmental effects, and pulling curves and conductance histograms for mechanically-controlled break-junction experiments. © 2014 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.


Rahman G.,Quaid-i-Azam University | Din N.U.,Quaid-i-Azam University | Garcia-Suarez V.M.,University of Oviedo | Garcia-Suarez V.M.,Nanomaterials and Nanotechnology Research Center | And 2 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2013

The magnetism and electronic structure of Li-doped SnO2 are investigated using first-principles LDA/LDA+U calculations. We find that Li induces magnetism in SnO2 when doped at the Sn site but becomes nonmagnetic when doped at the O and interstitial sites. The calculated formation energies show that Li prefers the Sn site as compared with the O site, in agreement with previous experimental works. The interaction of Li with native defects (Sn VSn and O VO vacancies) is also studied, and we find that Li not only behaves as a spin polarizer, but also a vacancy stabilizer, i.e., Li significantly reduces the defect formation energies of the native defects and helps the stabilization of magnetic oxygen vacancies. The electronic densities of states reveals that these systems, where the Fermi level touches the conduction (valence) band, are nonmagnetic (magnetic). © 2013 American Physical Society.


Garcia-Suarez V.M.,University of Oviedo | Garcia-Suarez V.M.,Nanomaterials and Nanotechnology Research Center | Garcia-Suarez V.M.,Lancaster University | Ferradas R.,University of Oviedo | And 4 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2013

We show that the thermoelectric properties of nanoscale junctions featuring states near the Fermi level strongly depend on the type of resonance generated by such states, which can be either Fano- or Breit-Wigner-like. We give general expressions for the thermoelectric coefficients generated by the two types of resonances and calculate the thermoelectric properties of these systems, which encompass most nanoelectronics junctions. We include simulations of real junctions where metalloporphyrins dithiolate molecules bridge gold electrodes and prove that for some metallic elements the thermoelectric properties show a large variability with respect to the position of the resonance near the Fermi level. We find that the thermopower and figure of merit are largely enhanced when the resonance gets close to the Fermi level and reach values higher than typical values found in other nanoscale junctions. The specific value and temperature dependence are determined by a series of factors such as the strength of the coupling between the state and other molecular states, the symmetry of the state, the strength of the coupling between the molecule and the leads and the spin-filtering behavior of the junction. © 2013 American Physical Society.


Borrell A.,Nanomaterials and Nanotechnology Research Center | Fernandez A.,Fundacion ITMA | Merino C.,Grupo Antolin Ingenieria | Torrecillas R.,Nanomaterials and Nanotechnology Research Center
International Journal of Materials Research | Year: 2010

Graphitic materials obtained at low temperatures are interesting for a wide range of industrial applications including bipolar plates. In this work, graphite based nanocomposites have been obtained starting from carbon nanofibers and a mixture of carbon nanofibers with 20 vol.% of alumina nanopowders. High density carbon components were obtained by using Spark Plasma Sintering at temperatures as low as 1500-1800°C for this kind of materials. The effect of spark plasma sintering parameters on the final density, and the mechanical and electrical properties of resulting nanocomposites have been investigated. Pure carbon nanofibers with around 90% of theoretical density and fracture strength of 60 MPa have been obtained at temperatures as low as 1500°C applying a pressure of 80 MPa during sintering. It has been proved that attrition milling is a suitable method for preparing homogeneous mixtures of carbon nanofibers and alumina powders. © Carl Hanser Verlag GmbH & Co. KG.


Carrascal D.J.,University of Oviedo | Carrascal D.J.,Nanomaterials and Nanotechnology Research Center | Ferrer J.,University of Oviedo | Ferrer J.,Nanomaterials and Nanotechnology Research Center | And 2 more authors.
Journal of Physics Condensed Matter | Year: 2015

This review explains the relationship between density functional theory and strongly correlated models using the simplest possible example, the two-site Hubbard model. The relationship to traditional quantum chemistry is included. Even in this elementary example, where the exact ground-state energy and site occupations can be found analytically, there is much to be explained in terms of the underlying logic and aims of density functional theory. Although the usual solution is analytic, the density functional is given only implicitly. We overcome this difficulty using the Levy-Lieb construction to create a parametrization of the exact function with negligible errors. The symmetric case is most commonly studied, but we find a rich variation in behavior by including asymmetry, as strong correlation physics vies with charge-transfer effects. We explore the behavior of the gap and the many-body Green's function, demonstrating the 'failure' of the Kohn-Sham (KS) method to reproduce the fundamental gap. We perform benchmark calculations of the occupation and components of the KS potentials, the correlation kinetic energies, and the adiabatic connection. We test several approximate functionals (restricted and unrestricted Hartree-Fock and Bethe ansatz local density approximation) to show their successes and limitations. We also discuss and illustrate the concept of the derivative discontinuity. Useful appendices include analytic expressions for density functional energy components, several limits of the exact functional (weak- and strong-coupling, symmetric and asymmetric), various adiabatic connection results, proofs of exact conditions for this model, and the origin of the Hubbard model from a minimal basis model for stretched H2. © 2015 IOP Publishing Ltd.


PubMed | Institute Investigacion Hospital 12 Of Octubre I12, Nanomaterials and Nanotechnology Research Center, Hospital 12 Of Octubre and University of Oviedo
Type: Journal Article | Journal: Stem cell research | Year: 2016

Human iPSC line LND554SV.3 was generated from heteroplasmic fibroblasts of a patient with Leigh syndrome carrying a mutation in the MT-ND5 gene (m.13513GNA; p.D393N). Reprogramming factors Oct3/4, Sox2, Klf4,and cMyc were delivered using a non-integrative methodology that involves the use of Sendai virus.


PubMed | Institute Investigacion Hospital 12 Of Octubre I12, Nanomaterials and Nanotechnology Research Center, Hospital 12 Of Octubre and University of Oviedo
Type: Journal Article | Journal: Stem cell research | Year: 2016

Human iPSC line N44SV.5 was generated from primary normal human dermal fibroblasts belonging to the European mitochondrial haplogroup U. For this purpose, reprogramming factors Oct3/4, Sox2, Klf4, and cMyc were delivered using a non-integrative methodology that involves the use of Sendai virus.


PubMed | Ludwig Maximilians University of Munich, Nanomaterials and Nanotechnology Research Center, Hospital 12 Of Octubre, Institute Investigacion Hospital 12 Of Octubre I 12 and University of Oviedo
Type: Journal Article | Journal: Stem cell research | Year: 2016

Human iPSC line PG64SV.2 was generated from fibroblasts of a patient with a defect of intergenomic communication. This patient harbored a homozygous mutation (c.2243G>C; p.Trp748Ser) in the gene encoding the catalytic subunit of the mitochondrial DNA polymerase gamma gene (POLG). Reprogramming factors Oct3/4, Sox2, Klf4, and cMyc were delivered using a non integrative methodology that involves the use of Sendai virus.


PubMed | Institute Investigacion Sanitaria University Hospital Fundacion Jimenez Diaz, Nanomaterials and Nanotechnology Research Center, Institute Investigacion Hospital 12 Of Octubre I 12 and University of Oviedo
Type: Journal Article | Journal: Stem cell research | Year: 2016

Human iPSC line GFM1SV.25 was generated from fibroblasts of a child with a severe mitochondrial encephalopathy associated with mutations in the GFM1 gene, encoding the mitochondrial translation elongation factor G1. Reprogramming factors OCT3/4, SOX2, CMYC and KLF4 were delivered using a non integrative methodology that involves the use of Sendai virus.


PubMed | University of Medicine and Pharmacy, Cluj-Napoca, Nanomaterials and Nanotechnology Research Center, University of Houston, University of Ferrara and 5 more.
Type: Journal Article | Journal: Molecular cell | Year: 2016

Altered energy metabolism is a cancer hallmark as malignant cells tailor their metabolic pathways to meet their energy requirements. Glucose and glutamine are the major nutrients that fuel cellular metabolism, and the pathways utilizing these nutrients are often altered in cancer. Here, we show that the long ncRNA CCAT2, located at the 8q24 amplicon on cancer risk-associated rs6983267 SNP, regulates cancer metabolism in vitro and in vivo in an allele-specific manner by binding the Cleavage Factor I (CFIm) complex with distinct affinities for the two subunits (CFIm25 and CFIm68). The CCAT2 interaction with the CFIm complex fine-tunes the alternative splicing of Glutaminase (GLS) by selecting the poly(A) site in intron 14 of the precursor mRNA. These findings uncover a complex, allele-specific regulatory mechanism of cancer metabolism orchestrated by the two alleles of a long ncRNA.

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