Zero-bias conductance peak and Josephson effect in graphene-NbTiN junctions

We report electronic transport measurements of graphene contacted by NbTiN electrodes, which at low temperature remain superconducting up to at least 11 Tesla. In devices with a single superconducting contact, we find a more than twofold enhancement of the conductance at zero bias, which we interpret in terms of reflectionless tunneling. In devices with two superconducting contacts, we observe the Josephson effect, bipolar supercurrents and Fraunhofer patterns.Comment: 6 pages, 5 figure

DNA Translocation through Graphene Nanopores

Nanopores -- nanosized holes that can transport ions and molecules -- are very promising devices for genomic screening, in particular DNA sequencing. Both solid-state and biological pores suffer from the drawback, however, that the channel constituting the pore is long, viz. 10-100 times the distance between two bases in a DNA molecule (0.5 nm for single-stranded DNA). Here, we demonstrate that it is possible to realize and use ultrathin nanopores fabricated in graphene monolayers for single-molecule DNA translocation. The pores are obtained by placing a graphene flake over a microsize hole in a silicon nitride membrane and drilling a nanosize hole in the graphene using an electron beam. As individual DNA molecules translocate through the pore, characteristic temporary conductance changes are observed in the ionic current through the nanopore, setting the stage for future genomic screening

Trophic web structure and ecosystem attributes of a temperate coastal lagoon

A high quality data collection has been carried out between 2004 and 2014 to develop the first trophic ECOPATH model for the functioning of the sub and intertidal zones of Ria de Aveiro. This schematic representation allows the characterization of the most important compartments of biomass and flows of energy representing the functioning of the ecosystem, and can be used in the fields of decision-making and management. The model considered 26 functional groups from primary producers to top-predators and two different fisheries (artisanal and leisure), and showed that Ria de Aveiro is a dynamic ecosystem dominated by a high biomass of primary producers, where the transference of energy among compartments is, to a large extent, accomplished through the detritus path. The model also provides several ecological indicators on the state of maturity of the ecosystem, showing that Ria de Aveiro is in an intermediate state of maturity with a relatively complex food web and resilience to environmental changes. As discussed, this state of maturity is probably determined by human action pervading the system to advance in the expectable ecological succession of a coastal lagoon. These aspects, together with indicators of elevated fishing pressure and predation within the system, underline the necessity of controlling illegal extraction activities and monitoring the biomass of the main functional groups of the system, especially top predators, in order to keep the functioning of the ecosystem of Ria de Aveiro in its current condition.info:eu-repo/semantics/publishedVersio

Genetic variant in the telomerase gene modifies cancer risk in Lynch syndrome

Lynch syndrome (LS) is an inherited cancer-predisposing disorder caused by germline mutations in the mismatch repair (MMR) genes. The high variability in individual cancer risk observed among LS patients suggests the existence of modifying factors. Identifying genetic modifiers of risk could help implement personalized surveillance programs based on predicted cancer risks. Here we evaluate the role of the telomerase (hTERT) rs2075786 SNP as a cancer-risk modifier in LS, studying 255 and 675 MMR gene mutation carriers from Spain and the Netherlands, respectively. The study of the Spanish sample revealed that the minor allele (A) confers increased cancer risk at an early age. The analysis of the Dutch sample confirmed the association of the A allele, especially in homozygosity, with increased cancer risk in mutation carriers under the age of 45 (relative riskLSca<45_AA=2.90; 95% confidence interval=1.02–8.26). Rs2075786 is associated with colorectal cancer (CRC) risk neither in the general population nor in non-Lynch CRC families. In silico studies predicted that the SNP causes the disruption of a transcription binding site for a retinoid receptor, retinoid X receptor alpha, probably causing early telomerase activation and therefore accelerated carcinogenesis. Notably, cancer-affected LS patients with the AA genotype have shorter telomeres than those with GG. In conclusion, MMR gene mutation carriers with hTERT rs2075786 are at high risk to develop a LS-related tumor at an early age. Cancer-preventive measures and stricter cancer surveillance at early ages might help prevent or early detect cancer in these mutation carriers.MTG2 - Moleculaire genetica van gastrointestinale tumore