2,321 research outputs found
Ressenya dâErotisme i tabĂșs en lâetnopoĂštica, dâAnna FrancĂ©s i Jaume GuiscafrĂš (ed.) (Institut AlacantĂ de Cultura Juan Gil-Albert - Arxiu de Tradicions de lâAlguer â Grup dâEstudis EtnopoĂštics, Alacant-lâAlguer-Barcelona, 2013, 300 pĂ gines)
Light Generation and Harvesting in a Van der Waals Heterostructure
Two-dimensional (2D) materials are a new type of materials under intense
study because of their interesting physical properties and wide range of
potential applications from nanoelectronics to sensing and photonics.
Monolayers of semiconducting transition metal dichalcogenides MoS2 or WSe2 have
been proposed as promising channel materials for field-effect transistors
(FETs). Their high mechanical flexibility, stability and quality coupled with
potentially inexpensive production methods offer potential advantages compared
to organic and crystalline bulk semiconductors. Due to quantum mechanical
confinement, the band gap in monolayer MoS2 is direct in nature, leading to a
strong interaction with light that can be exploited for building
phototransistors and ultrasensitive photodetectors. Here, we report on the
realization of light-emitting diodes based on vertical heterojunctions composed
of n-type monolayer MoS2 and p-type silicon. Careful interface engineering
allows us to realize diodes showing rectification and light emission from the
entire surface of the heterojunction. Electroluminescence spectra show clear
signs of direct excitons related to the optical transitions between the
conduction and valence bands. Our pn diodes can also operate as solar cells,
with typical external quantum efficiency exceeding 4%. Our work opens up the
way to more sophisticated optoelectronic devices such as lasers and
heterostructure solar cells based on hybrids of two-dimensional (2D)
semiconductors and silicon.Comment: Submitted versio
Cornea regeneration as an alternative to human donor transplantation
There is a need for an alternative to human donor corneas as the availability of good-quality tissues remains limited, with this situation
potentially worsening as the population in many countries is progressively ageing. There have been numerous attempts to develop
corneal equivalent as alternatives to donated human corneas as well as prostheses. In this short review, we focus on the efforts in
bioengineering implants that promote regeneration by Canadian researchers, including our current team of authors. The examples of
technologies developed that we describe include biomaterials that allow for partial regeneration of corneal tissue, self-assembled cornea
constructs and cell-free corneal implants that promoted regeneration when evaluated in clinical trials in Europe
Baryon masses and \sigma-terms in SU(3) BChPT x 1/Nc
Baryon masses and nucleon \sigma-terms are studied with the effective theory
that combines the chiral and 1/Nc expansions for three flavors. In particular
the connection between the deviation of the Gell-Mann-Okubo relation and the
\sigma-term corresponding to the scalar density associated with the hypercharge
is emphasized. The latter is at lowest order related to a mass combination
whose low value has given rise to a \sigma- term puzzle. It is shown that while
the nucleon \sigma-terms have a well behaved low energy expansion, that mass
combination is affected by large higher order corrections non-analytic in quark
masses. Adding to the analysis lattice QCD baryon masses, it is found that
{\sigma}{\pi}N=69(10) MeV and {\sigma}s has natural magnitude within its
relative large uncertainty.Comment: 8 pages, 1 table, 1 figur
Phylogeography Gene Flow and Population Structure of "Crambe Crambe" (Porifera: Poecilosclerida)
The main goal of this thesis has been to study the population structure of a marine sponge species (Crambe crambe) at different geographic levels using different molecular markers.In many organisms, particularly terrestrials, molecular markers have been used to answer questions about the structure and connectivity of populations, the potential of dispersal or the history of species, and these data were of crucial help in conservation and management of species. Most of these studies used allozymes and, more recently, mitochondrial or nuclear sequences with success. Also, microsatellite markers are being developed and applied with terrific success in many species. Unfortunately, application of molecular markers in marine environments lags much behind, especially for invertebrate organisms, where population genetic studies are still scarce and most of them involve only allozymes. Thus, this study attempts to be contribute to the development and application of molecular markers for ecologic and population genetic studies in marine invertebrates. Most marine invertebrate organisms are benthic, and many of them sessile, with larvae as the main form of dispersal. Because of the intrinsic difficulty on following larval movements in natural environments, molecular markers appear as the perfect tool to track and characterize populations, and even individuals. Hence, in this thesis several molecular markers have been applied in a sponge species, and with the complementary help of previous ecological and biological knowledge of the species, the present-day population structure of this sponge has been studied, trying to uncover which factors are affecting and might have affected in the past the structure found, while comparing the resolution and the "snapshot" information recovered with each of the markers used
Cis-regulatory elements are harbored in Intron5 of the RUNX1 gene
BACKGROUND: Human RUNX1 gene is one of the most frequent target for chromosomal translocations associated with acute myeloid leukemia (AML) and acute lymphoid leukemia (ALL). The highest prevalence in AML is noted with (8; 21) translocation; which represents 12 to 15% of all AML cases. Interestingly, all the breakpoints mapped to date in t(8;21) are clustered in intron 5 of the RUNX1 gene and intron 1 of the ETO gene. No homologous sequences have been found at the recombination regions; but DNase I hypersensitive sites (DHS) have been mapped to the areas of the genes involved in t(8;21). Presence of DHS sites is commonly associated with regulatory elements such as promoters, enhancers and silencers, among others. RESULTS: In this study we used a combination of comparative genomics, cloning and transfection assays to evaluate potential regulatory elements located in intron 5 of the RUNX1 gene. Our genomic analysis identified nine conserved non-coding sequences that are evolutionarily conserved among rat, mouse and human. We cloned two of these regions in pGL-3 Promoter plasmid in order to analyze their transcriptional regulatory activity. Our results demonstrate that the identified regions can indeed regulate transcription of a reporter gene in a distance and position independent manner; moreover, their transcriptional effect is cell type specific. CONCLUSIONS: We have identified nine conserved non coding sequence that are harbored in intron 5 of the RUNX1 gene. We have also demonstrated that two of these regions can regulate transcriptional activity in vitro. Taken together our results suggest that intron 5 of the RUNX1 gene contains multiple potential cis-regulatory elements
Rational Strain Engineering in Delafossite Oxides for Highly Efficient Hydrogen Evolution Catalysis in Acidic Media
The rational design of hydrogen evolution reaction (HER) electrocatalysts
which are competitive with platinum is an outstanding challenge to make
power-to-gas technologies economically viable. Here, we introduce the
delafossites PdCrO, PdCoO and PtCoO as a new family of
electrocatalysts for the HER in acidic media. We show that in PdCoO the
inherently strained Pd metal sublattice acts as a pseudomorphic template for
the growth of a strained (by +2.3%) Pd rich capping layer under reductive
conditions. The surface modification continuously improves the electrocatalytic
activity by simultaneously increasing the exchange current density j from 2
to 5 mA/cm and by reducing the Tafel slope down to 38 mV/decade,
leading to overpotentials < 15 mV for 10 mA/cm, superior
to bulk platinum. The greatly improved activity is attributed to the in-situ
stabilization of a -palladium hydride phase with drastically enhanced
surface catalytic properties with respect to pure or nanostructured palladium.
These findings illustrate how operando induced electrodissolution can be used
as a top-down design concept for rational surface and property engineering
through the strain-stabilized formation of catalytically active phases
Factor V Leiden and prothrombin G20210A among Chilean patients with venous and arterial thrombosis
IvĂĄn Palomo. Departamento de
BioquĂmica ClĂnica e InmunohematologĂa, Facultad de Ciencias de la Salud. Universidad de Talca, Talca, Chile. Casilla 747,Talca, Chile.Factor V Leiden and G20210A mutation of
prothrombin gene are two important genetic polymorphisms associated with an increased risk for
thrombosis. Aim: To establish the prevalence of factor V Leiden and prothrombin G20210A mutation
in the Chilean population and their association to venous and arterial thromboembolism. Material
and methods: A case-control study was conducted where 149 patients with thrombosis (87 with
arterial and 62 with venous thrombosis) confirmed by CAT-scan, electrocardiogram and cardiac
enzymes or Doppler depending on the case, and 160 healthy blood donors were genetically analyzed
for the presence of both polymorphisms. Results: Factor V Leiden mutation was found in 5.4% of
patients and in 1.3% of healthy controls (p=0.04). Heterozygosity for G20210A prothrombin mutation
was found in 5.4% of patients and in 2.5% of the control group (p=NS). When arterial and venous
thrombosis were considered as separate entities, 4.6% of patients with arterial thrombosis and 6.5%
with venous thrombosis presented factor V Leiden (p=NS). Likewise, 8.1% of patients with venous
thrombosis and 3.5% of patients with arterial thrombosis had G20210A prothrombin mutation
(p=NS). Conclusions: In non selected consecutive Chilean patients with arterial and venous
thrombosis the frequency of factor V Leiden and prothrombin G20210A is less than we could expect
from their prevalence in the general populatio
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