Negative Emotions Recruit the Parabrachial Nucleus Efferent to the VTA to Disengage Instrumental Food Seeking.

The parabrachial nucleus (PBN) interfaces between taste and feeding systems and is also an important hub for relaying distress information and threats. Despite that the PBN sends projections to the ventral tegmental area (VTA), a heterogeneous brain region that regulates motivational behaviors, the function of the PBN-to-VTA connection remains elusive. Here, by using male mice in several behavioral paradigms, we discover that VTA-projecting PBN neurons are significantly engaged in contextual fear, restraint or mild stress but not palatable feeding, visceral malaise, or thermal pain. These results suggest that the PBN-to-VTA input may relay negative emotions under threat. Consistent with this notion, optogenetic activation of PBN-to-VTA glutamatergic input results in aversion, which is sufficient to override palatable feeding. Moreover, in a palatable food-reinforced operant task, we demonstrate that transient optogenetic activation of PBN-to-VTA input during food reward retrieval disengages instrumental food-seeking behaviors but spares learned action-outcome association. By using an activity-dependent targeting approach, we show that VTA DA neurons are disengaged by the PBN afferent activation, implicating that VTA non-DA neurons may mediate PBN afferent regulation. We further show that optogenetic activation of VTA neurons functionally recruited by the PBN input results in aversion, dampens palatable feeding, and disengages palatable food self-administration behavior. Finally, we demonstrate that transient activation of VTA glutamatergic, but not GABAergic, neurons recapitulates the negative regulation of the PBN input on food self-administration behavior. Together, we reveal that the PBN-to-VTA input conveys negative affect, likely through VTA glutamatergic neurons, to disengage instrumental food-seeking behaviors.SIGNIFICANCE STATEMENT The PBN receives multiple inputs and thus is well positioned to route information of various modalities to engage different downstream circuits to attend or respond accordingly. We demonstrate that the PBN-to-VTA input conveys negative affect and then triggers adaptive prioritized responses to address pertinent needs by withholding ongoing behaviors, such as palatable food seeking or intake shown in the present study. It has evolutionary significance because preparing to cope with stressful situations or threats takes priority over food seeking to promote survival. Knowing how appropriate adaptive responses are generated will provide new insights into circuitry mechanisms of various coping behaviors to changing environmental stimuli.

Operando Revealing the Crystal Phase Transformation and Electrocatalytic Activity Correlation of MnO2 toward Glycerol Electrooxidation.

In this work, we report for the first time a comprehensive operando investigation of the intricate correlation between dynamic phase evolution and glycerol electrooxidation reaction (GEOR) performance across three primary MnO2 crystallographic phases (α-, ß-, and γ-MnO2). The results showed that all three electrocatalysts exhibited comparable selectivity toward three-carbon products (∼90%), but γ-MnO2 exhibited superior performance, with a low onset potential of ∼1.45 VRHE, the highest current density of ∼1.9 mA cm-2 at 1.85 VRHE, and reasonable stability. Operando Raman spectroscopy revealed the potential-induced surface reconstruction of different MnO2 structures from which a correlation among the applied potential, electrocatalytic activity, and product distribution was identified. The higher the applied potential, the greater conversion from the original structure to δ-MnO2, resulting in lower C-C cleavage and higher 3C product selectivity. This study not only provides a systematic understanding of structure-controlled electrocatalytic activity for high selectivity toward 3C products of MnO2 but also contributes to the development of a non-noble and environmentally friendly catalyst for valorizing glycerol.

Anion-induced morphological regulation of cupric oxide nanostructures and their application as co-catalysts for solar water splitting.

Morphological control of nanomaterials is essential for their properties and potential applications, and many strategies have been developed. In this work, a new strategy for simultaneously preparing and modulating the morphological structure evolution of copper layered hydroxyl salts and oxides is introduced. By changing the nature of the anions in the electroplating solution, significant variations in the size and porosity of nanosheets are achieved. Porous CuO nanosheets with a higher surface area were obtained by the use of copper nitrate as a copper source, while CuO nanoflakes were produced from copper sulfate. Photoanodes combining these porous CuO nanomaterials and a typical light absorber (BiVO4) exhibited good morphology-dependent activities for photoelectrochemical water splitting. The composite electrode displays a negative shift of 180 mV for the onset potential and an approximately 2-fold enhancement in the photocurrent compared to the bare BiVO4. The charge recombination rate in the photoelectrode with the porous CuO nanosheets was significantly lower than the bare photoanode due to the favorable electron diffusion path and effective charge collection. This research offers an effective method for constructing a highly active photoelectrocatalytic system for overall water splitting.

Controllable electrodeposition of binary metal films from deep eutectic solvent as an efficient and durable catalyst for the oxygen evolution reaction.

In this work, we present an easy and scalable electrodeposition protocol that operates in a deep eutectic solvent, used to prepare self-supported Ni-Fe alloy films directly grown on copper foils. Unlike electrodeposition in aqueous baths, alloy compositions deposited in deep eutectic solvent are found to be the same as in plating solution owing to the enlargement of the deposition window and secondary reaction suppression. By rationally tuning the Ni/Fe ratio in deep eutectic solvent plating solution, the best oxygen evolution reaction performance was achieved by a Ni75Fe25 catalyst, which requires only a 316 mV overpotential to reach a current density of 10 mA cm-2, while its Tafel slope is as low as 62 mV dec-1. This catalyst can operate at 10 mA cm-2 with negligible activity degradation for over 10 h, promising its potential use as a low-cost, high-performance and stable electrocatalyst in water splitting devices.

Unraveling the critical effects of the preoxidation process toward the morphological evolution and intrinsic properties of novel ZnCoMn trimetallic hydroxides.

A strategy for simultaneously preparing and modulating the morphological structure evolution and physical properties of novel trimetallic hydroxides is introduced. The interrelations among the level of pre-oxidation, the nanostructure evolution and the physicochemical properties of the material are thoroughly investigated. In addition, the growth mechanism for this new type of ternary hydroxide is also proposed. This work provides not only a convincing demonstration of a novel composite being used as a cheap and promising material for energy conversion, but also an effective method for rationally designing other hydroxide-based materials.

Molybdenum Sulfide for Hydrogen Evolution Reaction: The Importance of Solution Dynamic Wetting Behavior in The Drying Process.

MoSx serving as a hydrogen evolution reaction electrocatalyst is known for its morphology sensitive characteristic. The low temperature thermo-decomposition method provides an easy and energy saving pathway to produce highly active MoSx on carbon paper substrates. However, during the precursor solution drying process, the dynamics of liquid wetting behavior dominates the morphology of the precursor salt and eventually the morphology of MoSx. As a result, here, for the first time, by carefully pairing the substrate hydrophobicity and solvent polarity, the cohesive force between solvent molecules and adhesive force between solvent and carbon substrate can be tuned, and thus the MoSx morphology can be controlled. Pairing hydrophilic carbon paper with DMF + H2O mixing solvent results in a relatively strong adhesive force, as a result, we are able to lower the overpotential required at the benchmark current density, 10 mA/cm2, to as low as 0.160 V and boost the current density to 40 mA/cm2 at -0.2 V vs RHE. This mainly results from the low charge transfer resistance and the well wrapped MoSx on carbon paper fiber structure. Furthermore, this well wrapped MoSx on hydrophilic carbon paper was proved to be comparably stable for constant voltage electrolysis operation.

The response of relativistic outflowing gas to the inner accretion disk of a black hole.

The brightness of an active galactic nucleus is set by the gas falling onto it from the galaxy, and the gas infall rate is regulated by the brightness of the active galactic nucleus; this feedback loop is the process by which supermassive black holes in the centres of galaxies may moderate the growth of their hosts. Gas outflows (in the form of disk winds) release huge quantities of energy into the interstellar medium, potentially clearing the surrounding gas. The most extreme (in terms of speed and energy) of these-the ultrafast outflows-are the subset of X-ray-detected outflows with velocities higher than 10,000 kilometres per second, believed to originate in relativistic (that is, near the speed of light) disk winds a few hundred gravitational radii from the black hole. The absorption features produced by these outflows are variable, but no clear link has been found between the behaviour of the X-ray continuum and the velocity or optical depth of the outflows, owing to the long timescales of quasar variability. Here we report the observation of multiple absorption lines from an extreme ultrafast gas flow in the X-ray spectrum of the active galactic nucleus IRAS 13224-3809, at 0.236 ± 0.006 times the speed of light (71,000 kilometres per second), where the absorption is strongly anti-correlated with the emission of X-rays from the inner regions of the accretion disk. If the gas flow is identified as a genuine outflow then it is in the fastest five per cent of such winds, and its variability is hundreds of times faster than in other variable winds, allowing us to observe in hours what would take months in a quasar. We find X-ray spectral signatures of the wind simultaneously in both low- and high-energy detectors, suggesting a single ionized outflow, linking the low- and high-energy absorption lines. That this disk wind is responding to the emission from the inner accretion disk demonstrates a connection between accretion processes occurring on very different scales: the X-ray emission from within a few gravitational radii of the black hole ionizing the disk wind hundreds of gravitational radii further away as the X-ray flux rises.

Three-dimensional molybdenum sulfide sponges for electrocatalytic water splitting.

Electroactive MoSx catalysts on porous 3D sponges synthezied by a simple and scalable thermolysis process are proposed. Although no conducting materials are used to host the MoSx catalysts, they still serve as efficient electrodes for hydrogen evolution. The high current density of the MoSx-coated sponges are attributed to the large electrochemical surface area and their S-rich chemical structure.

Biological templates for antireflective current collectors for photoelectrochemical cell applications.

Three-dimensional (3D) structures such as nanowires, nanotubes, and nanorods have the potential to increase surface area, reduce light reflection, and shorten charge carrier transport distances. The assembly of such structures thus holds great promise for enhancing photoelectrochemical solar cell efficiency. In this study, genetically modified Tobacco mosaic virus (TMV1cys) was used to form self-assembling 3D nanorod current collectors and low light-reflecting surfaces. Photoactive CuO was subsequently deposited by sputtering onto these patterned nanostructures, and these structures were examined for photocurrent activity. CuO thicknesses of 520 nm on TMV1cys patterned current collectors produced the highest photocurrent density of 3.15 mA/cm(2) yet reported for a similar sized CuO system. Reflectivity measurements are in agreement with full-wave electromagnetic simulations, which can be used as a design tool for optimizing the CuO system. Thus the combined effects of reducing charge carrier transport distance, increasing surface area, and the suppression of light reflection make these virus-templated surfaces ideal for photoelectrochemical applications.

Evaluating the compatibility of three colorimetric protein assays for two-dimensional electrophoresis experiments.

To evaluate compatibility of commonly used colorimetric protein assays for 2-DE experiments, we investigated the interfering mechanisms of major 2-DE component(s) in the Lowry-based assay, the Bradford assay and the bicinchoninic acid (BCA) assay. It was found that some 2-DE components did not directly interfere with the assays' color development reaction, but possibly influenced the quantitation results by interacting with proteins. Generally, simultaneous presence of 2-DE components in the samples demonstrated a cooperative rather than additive interference. Interference by reductants in the Lowry-based assay and the BCA assay were too prominent and could not be completely eliminated by either the reported alkylation procedure or the water dilution procedure. The Bradford assay however, presented a more suitable method for quantitating 2-DE samples because it was less interfered by most 2-DE components. Furthermore, despite slightly compromising protein solubility, utilization of reductant free 2-DE sample buffers conferred application of the Lowry-based and BCA assays in the 2-DE experiments.