Water oxidation is the key kinetic bottleneck of photoelectrochemical devices for fuel synthesis. Despite advances in the identification of intermediates, elucidating the catalytic mechanism of this ...multi-redox reaction on metal-oxide photoanodes remains a significant experimental and theoretical challenge. Here, we report an experimental analysis of water oxidation kinetics on four widely studied metal oxides, focusing particularly on haematite. We observe that haematite is able to access a reaction mechanism that is third order in surface-hole density, which is assigned to equilibration between three surface holes and M(OH)-O-M(OH) sites. This reaction exhibits low activation energy (E
≈ 60 meV). Density functional theory is used to determine the energetics of charge accumulation and O-O bond formation on a model haematite (110) surface. The proposed mechanism shows parallels with the function of the oxygen evolving complex of photosystem II, and provides new insights into the mechanism of heterogeneous water oxidation on a metal oxide surface.
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FZAB, GEOZS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Molecular catalysis of fuel-forming half reactions such as proton and CO2 reduction is a key area of study for achieving electrical-to-chemical energy storage and solar fuel synthesis. Immobilization ...of these molecular catalysts on electrode surfaces often results in high turnover numbers and selectivities, even under the challenging conditions of an aqueous environment. This Perspective considers how the combination of electrochemistry and electronic spectroscopy can be used to characterize catalytic processes in operando, explaining the observed performance and therefore guiding the design principles for the next generation of material/molecule hybrid electrodes and devices. Numerous immobilization strategies and electrode materials are already available, of which wide band gap metal oxides offer transparency to visible light and are therefore ideal for spectroelectrochemical characterization. Spectroscopic analysis of emerging catalytic metal–organic framework and polymer films is also discussed.
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IJS, KILJ, NUK, PNG, UL, UM
Solar-powered electrochemical production of hydrogen through water electrolysis is an active and important research endeavor. However, technologies and roadmaps for implementation of this process do ...not exist. In this perspective paper, we describe potential pathways for solar-hydrogen technologies into the marketplace in the form of photoelectrochemical or photovoltaic-driven electrolysis devices and systems. We detail technical approaches for device and system architectures, economic drivers, societal perceptions, political impacts, technological challenges, and research opportunities. Implementation scenarios are broken down into short-term and long-term markets, and a specific technology roadmap is defined. In the short term, the only plausible economical option will be photovoltaic-driven electrolysis systems for niche applications. In the long term, electrochemical solar-hydrogen technologies could be deployed more broadly in energy markets but will require advances in the technology, significant cost reductions, and/or policy changes. Ultimately, a transition to a society that significantly relies on solar-hydrogen technologies will benefit from continued creativity and influence from the scientific community.
Several application fields can benefit from solar-hydrogen technologies
via
specific short-term and long-term pathways.
Regulatory B cells (Breg) express high levels of CD1d that presents lipid antigens to invariant natural killer T (iNKT) cells. The function of CD1d in Breg biology and iNKT cell activity during ...inflammation remains unclear. Here we show, using chimeric mice, cell depletion and adoptive cell transfer, that CD1d-lipid presentation by Bregs induces iNKT cells to secrete interferon (IFN)-γ to contribute, partially, to the downregulation of T helper (Th)1 and Th17-adaptive immune responses and ameliorate experimental arthritis. Mice lacking CD1d-expressing B cells develop exacerbated disease compared to wild-type mice, and fail to respond to treatment with the prototypical iNKT cell agonist α-galactosylceramide. The absence of lipid presentation by B cells alters iNKT cell activation with disruption of metabolism regulation and cytokine responses. Thus, we identify a mechanism by which Bregs restrain excessive inflammation via lipid presentation.
Abstract We review the first generations of clinical trials of novel cell therapies applied to a range of neurodegenerative diseases in the context of mechanisms of functional efficacy. This in turn ...helps to determine the best strategies to be adopted and the potential chances for success in developing new cell therapies to clinical application in different conditions. We then consider the scientific, technical, ethical, regulatory and logistic issues to be resolved in translating effective laboratory cell-based protocols to patients in clinical trials. We draw optimistic conclusions about the likelihood of success in developing radical new approaches to a range of devastating, and currently untreatable, neurodegenerative conditions, but caution that the problems are complex and the solutions are likely to be slow and costly to achieve in order to overcome significant ethical and regulatory as well as scientific challenges.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Obesity-associated metabolic dysfunction and inflammation can be ameliorated by bariatric surgery. While obesity is also linked to impaired B cell activation, differentiation, and persistence in ...response to infection and vaccination little is known about post-operative immune B cell compartment and to what extent dysregulation in B cell pathways can be reversed. To bridge this gap in knowledge, we carried out in-depth evaluation of B cell composition in individuals with obesity prior to and following bariatric surgery compared to lean controls.
We recruited individuals with obesity (BMI at least 35 kg/m
) before bariatric surgery (n = 21) and followed them up 6 months post-operatively (n = 17). As controls we recruited age- and sex-matched lean (BMI < 25) individuals (n = 18). We carried out comprehensive immunophenotyping of peripheral blood B cells as well as interrogated their association with inflammatory and metabolic parameters.
In obesity the balance of antigen-inexperienced and memory B cells in the peripheral blood is altered, with an expansion of naïve and a reduction in total memory B cells. 6 months following bariatric surgery this balance is restored. However, post-operative patients are uniquely characterised by an increase in B cell subsets associated with chronic inflammation - CD11c
CXCR5
IgD
CD27
double negative 2 (DN2) B cells and CD27
CD38
plasmablasts. Correlations between B cells subsets, inflammatory and metabolic parameters were distinct in lean people and individuals with obesity pre- and post-bariatric surgery.
Bariatric surgery patients display a unique B cell profile 6 months post-operatively; this bears minimal resemblance to that of pre-operative patients and only partially overlaps with that of lean controls. Post-operative differences in the B cell compartment compared to lean controls are detected despite global amelioration of inflammation and restoration of metabolic health. Collectively, this indicates that bariatric surgery creates a specific immunometabolic state with potential implications for health outcomes.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The efficient generation of striatal neurons from human embryonic stem cells (hESCs) and induced pluripotent stem cells (hiPSCs) is fundamental for realising their promise in disease modelling, ...pharmaceutical drug screening and cell therapy for Huntington's disease. GABAergic medium-sized spiny neurons (MSNs) are the principal projection neurons of the striatum and specifically degenerate in the early phase of Huntington's disease. Here we report that activin A induces lateral ganglionic eminence (LGE) characteristics in nascent neural progenitors derived from hESCs and hiPSCs in a sonic hedgehog-independent manner. Correct specification of striatal phenotype was further demonstrated by the induction of the striatal transcription factors CTIP2, GSX2 and FOXP2. Crucially, these human LGE progenitors readily differentiate into postmitotic neurons expressing the striatal projection neuron signature marker DARPP32, both in culture and following transplantation in the adult striatum in a rat model of Huntington's disease. Activin-induced neurons also exhibit appropriate striatal-like electrophysiology in vitro. Together, our findings demonstrate a novel route for efficient differentiation of GABAergic striatal MSNs from human pluripotent stem cells.
Inhibitory GABAergic interneurons originate in the embryonic medial ganglionic eminence (MGE) and control network activity in the neocortex. Dysfunction of these cells is believed to lead to runaway ...excitation underlying seizure-based neurological disorders such as epilepsy, autism, and schizophrenia. Despite their importance in heath and disease, our knowledge about the development of this diverse neuronal population remains incomplete. Here we conducted single-cell RNA sequencing (scRNA-seq) of human foetal MGE from 10 to 15 weeks post conception. These MGE tissues are composed of largely cycling progenitors and immature post-mitotic interneurons with characteristic regional marker expression. Analysis of integrated human and mouse MGE data revealed species-conserved transcriptomic profiles and regulatory programs. Moreover, we identified novel candidate transcription regulators for human interneuron differentiation. These findings provide a framework for in vitro modelling of interneuron development and a strategy for potentially enhancing interneuron production from human pluripotent stem cells.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Irritable and impulsive behaviour are common in Huntington's disease (HD: an autosomal dominant disorder causing degeneration in cortico-striatal networks). However, the cognitive mechanisms ...underlying these symptoms remain unclear, and previous research has not determined if common mechanisms underpin both symptoms. Here we used established and novel tasks to probe different aspects of irritable and impulsive behaviour to determine the neural mechanisms involved.
We recruited a cohort of 53 gene positive HD participants and 26 controls from non-affected family members and local volunteers. We used established questionnaire measures of irritability in HD (Snaith Irritability Scale, Problem Behaviours Assessment) and impulsivity Urgency, Premeditation Perseverance, Sensation-seeking, Positive urgency scale (UPPSP), Barratt Impulsivity Scale, in addition to cognitive tasks of provocation, motor inhibition, delay discounting and decision making under uncertainty. We used generalised linear models to determine differences between cases and controls, and associations with irritability in the HD group.
We found differences between cases and controls on the negative urgency subscale of the UPPSP, which was associated with irritability in HD. The frustrative non-reward provocation task also showed differences between cases and controls, in addition to predicting irritability in HD. The stop signal reaction time task showed case-control differences but was not associated with irritability in HD. None of the other measures showed group differences or predicted irritability in HD after correcting for confounding variables.
Irritability in HD is mediated by excessive response to provocation, rather than a failure of motor inhibition.
Neurodegeneration associated with brain iron accumulation (NBIA) comprises a heterogeneous group of disorders in which disruption of cellular mechanisms leads to accumulation of iron in the basal ...ganglia. This group includes patients with recently discovered mutations in the PLA2G6 gene encoding a calcium-independent phospholipase A2 enzyme that catalyzes the hydrolysis of glycerophospholipids. Previously, children with PLA2G6 mutations have been diagnosed with several different disorders and we wished to better define the phenotype of PLA2G6- associated neurodegeneration.
Detailed review of the clinical and genetic features of 14 and radiologic features of 13 of these patients with PLA2G6 mutations was undertaken.
Median age of symptom presentation was 14 months. One third of the cohort presented following an intercurrent illness. The children had progressive cognitive and motor skill regression, with evidence of axial hypotonia, four limb spasticity, bulbar dysfunction, and strabismus. All patients developed cerebellar ataxia and dystonia. Most patients had optic atrophy. Brain imaging demonstrated cerebellar cortical atrophy and gliosis in all patients. Changes consistent with increased iron deposition were identified in the globus pallidus and substantia nigra. Novel corpus callosum changes are also reported.
We describe a cohort of patients with PLA2G6-associated neurodegeneration (PLAN). Although patients with PLAN have previously been diagnosed with infantile neuroaxonal dystrophy, neurodegeneration associated with brain iron accumulation, and Karak syndrome, they display a characteristic clinical and radiologic phenotype. PLA2G6 mutational analysis will negate the need for more invasive diagnostic procedures such as tissue biopsy.
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