University of Porto

About: University of Porto is a education organization based out in Porto, Portugal. It is known for research contribution in the topics: Population & Context (language use). The organization has 20807 authors who have published 64514 publications receiving 1557882 citations. The organization is also known as: U.Porto & Universidade do Porto.

Ruthenium Oxide Hydrogen Evolution Catalysis on Composite Cuprous Oxide Water‐Splitting Photocathodes

Abstract: Photocathodes based on cuprous oxide (Cu2O) are promising materials for large scale and widespread solar fuel generation due to the abundance of copper, suitable bandgap, and favorable band alignments for reducing water and carbon dioxide. A protective overlayer is required to stabilize the Cu2O in aqueous media under illumination, and the interface between this overlayer and the catalyst nanoparticles was previously identified as a key source of instability. Here, the properties of the protective titanium dioxide overlayer ofcomposite cuprous oxide photocathodes are further investigated, as well as an oxide-based hydrogen evolution catalyst, ruthenium oxide (RuO2). The RuO2-catalyzed photoelectrodes exhibit much improved stability versus platinum nanoparticles, with 94% stability after 8 h of light-chopping chronoamperometry. Faradaic efficiencies of approximate to 100% are obtained as determined by measurement of the evolved hydrogen gas. The sustained photocurrents of close to 5 mA cm(-2) obtained with this electrode during the chronoamperometry measurement (at 0 V vs. the reversible hydrogen electrode, pH 5, and simulated 1 sun illumination) would correspond to greater than 6% solar-to-hydrogen conversion efficiency in a tandem photoelectrochemical cell, where the bias is provided by a photovoltaic device such as a dye-sensitized solar cell.

The Mass of Kepler-93b and The Composition of Terrestrial Planets

Abstract: Kepler-93b is a 1.478 ± 0.019 R⊕ planet with a 4.7 day period around a bright (V = 10.2), astroseismically characterized host star with a mass of 0.911 ± 0.033 Mand a radius of 0.919 ± 0.011 R� . Based on 86 radial velocity observations obtained with the HARPS-N spectrograph on the Telescopio Nazionale Galileo and 32 archival Keck/HIRES observations, we present a precise mass estimate of 4.02 ± 0.68 M⊕. The corresponding high density of 6.88 ± 1.18 g cm −3 is consistent with a rocky composition of primarily iron and magnesium silicate. We compare Kepler-93b to other dense planets with well-constrained parameters and find that between 1 and 6 M⊕, all dense planets including the Earth and Venus are well-described by the same fixed ratio of iron to magnesium silicate. There are as of yet no examples of such planets with masses > 6 M⊕. All known planets in this mass regime have lower densities requiring significant fractions of volatiles or H/He gas. We also constrain the mass and period of the outer companion in the Kepler-93 system from the long-term radial velocity trend and archival adaptive optics images. As the sample of dense planets with well-constrained masses and radii continues to grow, we will be able to test whether the fixed compositional model found for the seven dense planets considered in this paper extends to the full population of 1-6 M⊕ planets.

Amidated and Ibuprofen-Conjugated Kyotorphins Promote Neuronal Rescue and Memory Recovery in Cerebral Hypoperfusion Dementia Model.

Abstract: Chronic brain ischemia is a prominent risk factor for neurological dysfunction and progression for dementias, including Alzheimer’s disease (AD). In rats, permanent bilateral common carotid artery occlusion (2VO) causes a progressive neurodegeneration in the hippocampus, learning deficits and memory loss as it occurs in AD. Kyotorphin (KTP) is an endogenous antinociceptive dipeptide whose role as neuromodulator/neuroprotector has been suggested. Recently, we designed two analgesic KTP-derivatives, KTP-amide (KTP-NH2) and KTP-NH2 linked to ibuprofen (IbKTP-NH2) to improve KTP brain targeting. This study investigated the effects of KTP-derivatives on cognitive/behavioral functions (motor/spatial memory/nociception) and hippocampal pathology of female rats in chronic cerebral hypoperfusion (2VO-rat model). 2VO-animals were treated with KTP-NH2 or IbKTP-NH2 for 7 days at weeks 2 and 5 post-surgery. After behavioral testing (week 6), coronal sections of hippocampus were H&E-stained or immunolabeled for the cellular markers GFAP (astrocytes) and NFL (neurons). Our findings show that KTP-derivatives, mainly IbKTP-NH2, enhanced cognitive impairment of 2VO-animals and prevented neuronal damage in hippocampal CA1 subfield, suggesting their potential usefulness for the treatment of dementia.