Solar fuels design: Porous cathodes modeling for electrochemical carbon dioxide reduction in aqueous electrolytes.

The reduction of carbon dioxide emissions is crucial to reduce the atmospheric greenhouse effect, fighting climate change and global warming. Electrochemical CO2 reduction is one of the most promising carbon capture and utilization technologies, that can be powered by solar energy and used to make added-value chemicals and green fuels, providing grid-stability, energy security, and environmental benefits. A two-dimensional finite-elements model for porous electrodes was developed and validated against experimental data, allowing the design and performance improvement of a porous zinc cathode morphology and its operational conditions for an electrolyzer producing syngas via the co-electrolysis of CO2 and water. Porosity, pore length, fiber geometric shape, inlet pressure, system temperature, and catholyte flow rate were explored, and these parameters were thoroughly tuned by using the smart-search Nelder-Mead's multi-parameter optimization algorithm to achieve pronouncedly higher, industrial-relevant current density values than those previously reported, up to 263.6 mA/cm2 at an applied potential of -1.1 V vs. RHE.

Microwave Synthesis of Visible-Light-Activated g-C3N4/TiO2 Photocatalysts.

The preparation of visible-light-driven photocatalysts has become highly appealing for environmental remediation through simple, fast and green chemical methods. The current study reports the synthesis and characterization of graphitic carbon nitride/titanium dioxide (g-C3N4/TiO2) heterostructures through a fast (1 h) and simple microwave-assisted approach. Different g-C3N4 amounts mixed with TiO2 (15, 30 and 45 wt. %) were investigated for the photocatalytic degradation of a recalcitrant azo dye (methyl orange (MO)) under solar simulating light. X-ray diffraction (XRD) revealed the anatase TiO2 phase for the pure material and all heterostructures produced. Scanning electron microscopy (SEM) showed that by increasing the amount of g-C3N4 in the synthesis, large TiO2 aggregates composed of irregularly shaped particles were disintegrated and resulted in smaller ones, composing a film that covered the g-C3N4 nanosheets. Scanning transmission electron microscopy (STEM) analyses confirmed the existence of an effective interface between a g-C3N4 nanosheet and a TiO2 nanocrystal. X-ray photoelectron spectroscopy (XPS) evidenced no chemical alterations to both g-C3N4 and TiO2 at the heterostructure. The visible-light absorption shift was indicated by the red shift in the absorption onset through the ultraviolet-visible (UV-VIS) absorption spectra. The 30 wt. % of g-C3N4/TiO2 heterostructure showed the best photocatalytic performance, with a MO dye degradation of 85% in 4 h, corresponding to an enhanced efficiency of almost 2 and 10 times greater than that of pure TiO2 and g-C3N4 nanosheets, respectively. Superoxide radical species were found to be the most active radical species in the MO photodegradation process. The creation of a type-II heterostructure is highly suggested due to the negligible participation of hydroxyl radical species in the photodegradation process. The superior photocatalytic activity was attributed to the synergy of g-C3N4 and TiO2 materials.

Enhanced Fe-TiO2 Solar Photocatalysts on Porous Platforms for Water Purification.

In this study, polyethylene glycol-modified titanium dioxide (PEG-modified TiO2) nanopowders were prepared using a fast solvothermal method under microwave irradiation, and without any further calcination processes. These nanopowders were further impregnated on porous polymeric platforms by drop-casting. The effect of adding iron with different molar ratios (1, 2, and 5%) of iron precursor was investigated. The characterization of the produced materials was carried out by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. Optical characterization of all the materials was also carried out. SEM showed that pure TiO2 and Fe-TiO2 nanostructures presented similar nanosized and spherical particles, which uniformly covered the substrates. From XRD, pure TiO2 anatase was obtained for all nanopowders produced, which was further confirmed by Raman spectroscopy on the impregnated substrates. XPS and UV-VIS absorption spectroscopy emission spectra revealed that the presence of Fe ions on the Fe-TiO2 nanostructures led to the introduction of new intermediate energy levels, as well as defects that contributed to an enhancement in the photocatalytic performance. The photocatalytic results under solar radiation demonstrated increased photocatalytic activity in the presence of the 5% Fe-TiO2 nanostructures (Rhodamine B degradation of 85% after 3.5 h, compared to 74% with pure TiO2 for the same exposure time). The photodegradation rate of RhB dye with the Fe-TiO2 substrate was 1.5-times faster than pure TiO2. Reusability tests were also performed. The approach developed in this work originated novel functionalized photocatalytic platforms, which were revealed to be promising for the removal of organic dyes from wastewater.

GluA4 facilitates cerebellar expansion coding and enables associative memory formation.

AMPA receptors (AMPARs) mediate excitatory neurotransmission in the central nervous system (CNS) and their subunit composition determines synaptic efficacy. Whereas AMPAR subunits GluA1-GluA3 have been linked to particular forms of synaptic plasticity and learning, the functional role of GluA4 remains elusive. Here, we demonstrate a crucial function of GluA4 for synaptic excitation and associative memory formation in the cerebellum. Notably, GluA4-knockout mice had ~80% reduced mossy fiber to granule cell synaptic transmission. The fidelity of granule cell spike output was markedly decreased despite attenuated tonic inhibition and increased NMDA receptor-mediated transmission. Computational network modeling incorporating these changes revealed that deletion of GluA4 impairs granule cell expansion coding, which is important for pattern separation and associative learning. On a behavioral level, while locomotor coordination was generally spared, GluA4-knockout mice failed to form associative memories during delay eyeblink conditioning. These results demonstrate an essential role for GluA4-containing AMPARs in cerebellar information processing and associative learning.

Self- and proxy-rating of the ICECAP-O for people with dementia: A cross-sectional linguistic validation study in Germany and Portugal.

BACKGROUND: The capability concept became a recognized approach to the measurement of quality of life. The ICECAP-O for older people aims to measure capabilities and has recently been used in people with dementia (self-rating) and informal carers (substituted judgement). However, linguistic validation studies have so far been lacking. METHODS: A cross-sectional cognitive interview study with 15 people with dementia (PwD) and 23 informal carers (ICs) was conducted in Germany and Portugal. Respondents were asked to reveal their understanding of the ICECAP-O and the capability approach as well as the response process. A summarising content analysis was performed. RESULTS: Despite the small sample, our linguistic validation of the German and Portuguese translations detected considerable difficulties or deviations in item comprehension when compared with the intended meaning. In some cases, the item interpretations did not reflect the entire scope of the associated capability dimension, though they were basically correct. Moreover, participants were not able to differentiate some items appropriately from one another, and some misinterpretations occurred. ICs relied mainly on observable behaviour, emotions, or verbal expressions of the PwD. Therefore, ICs found items that ask about the achievement of individual expectations or thoughts about the future difficult to assess. Only very few PwD clearly indicated that they understood the capability approach. ICs in Germany had more difficulties in understanding the capability concept than in ICs Portugal. DISCUSSION: This linguistic validation study in Germany and Portugal indicates a need for some rephrasing and refinements of the ICECAP-O translated items in both countries to fully encompass some dimensions and avoid misinterpretations. Further studies with larger samples are necessary. Based on our findings, the current German version for ICs' substituted judgement cannot be recommended for this kind of respondents without further advancements.

Shared and specific signatures of locomotor ataxia in mutant mice.

Several spontaneous mouse mutants with deficits in motor coordination and associated cerebellar neuropathology have been described. Intriguingly, both visible gait alterations and neuroanatomical abnormalities throughout the brain differ across mutants. We previously used the LocoMouse system to quantify specific deficits in locomotor coordination in mildly ataxic Purkinje cell degeneration mice (pcd; Machado et al., 2015). Here, we analyze the locomotor behavior of severely ataxic reeler mutants and compare and contrast it with that of pcd. Despite clearly visible gait differences, direct comparison of locomotor kinematics and linear discriminant analysis reveal a surprisingly similar pattern of impairments in multijoint, interlimb, and whole-body coordination in the two mutants. These findings capture both shared and specific signatures of gait ataxia and provide a quantitative foundation for mapping specific locomotor impairments onto distinct neuropathologies in mice.

Transient inhibition and long-term facilitation of locomotion by phasic optogenetic activation of serotonin neurons.

Serotonin (5-HT) is associated with mood and motivation but the function of endogenous 5-HT remains controversial. Here, we studied the impact of phasic optogenetic activation of 5-HT neurons in mice over time scales from seconds to weeks. We found that activating dorsal raphe nucleus (DRN) 5-HT neurons induced a strong suppression of spontaneous locomotor behavior in the open field with rapid kinetics (onset ≤1 s). Inhibition of locomotion was independent of measures of anxiety or motor impairment and could be overcome by strong motivational drive. Repetitive place-contingent pairing of activation caused neither place preference nor aversion. However, repeated 15 min daily stimulation caused a persistent increase in spontaneous locomotion to emerge over three weeks. These results show that 5-HT transients have strong and opposing short and long-term effects on motor behavior that appear to arise from effects on the underlying factors that motivate actions.

A quantitative framework for whole-body coordination reveals specific deficits in freely walking ataxic mice.

The coordination of movement across the body is a fundamental, yet poorly understood aspect of motor control. Mutant mice with cerebellar circuit defects exhibit characteristic impairments in locomotor coordination; however, the fundamental features of this gait ataxia have not been effectively isolated. Here we describe a novel system (LocoMouse) for analyzing limb, head, and tail kinematics of freely walking mice. Analysis of visibly ataxic Purkinje cell degeneration (pcd) mice reveals that while differences in the forward motion of individual paws are fully accounted for by changes in walking speed and body size, more complex 3D trajectories and, especially, inter-limb and whole-body coordination are specifically impaired. Moreover, the coordination deficits in pcd are consistent with a failure to predict and compensate for the consequences of movement across the body. These results isolate specific impairments in whole-body coordination in mice and provide a quantitative framework for understanding cerebellar contributions to coordinated locomotion.