179566 research outputs found
Sort by
Proton Exchange Membrane Electrolysis Revisited: Advancements, Challenges, and Two-Phase Transport Insights in Materials and Modelling
Get PDFThe transition to clean energy has accelerated the pursuit of hydrogen as a sustainable fuel. Among various production methods, proton exchange membrane electrolysis cells (PEMECs) stand out due to their ability to generate ultra-pure hydrogen with efficiencies exceeding 80% and current densities reaching 2 A/cm2. Their compact design and rapid response to dynamic energy inputs make them ideal for integration with renewable energy sources. This review provides a comprehensive assessment of PEMEC technology, covering key internal components, system configurations, and efficiency improvements. The role of catalyst optimization, membrane advancements, and electrode architectures in enhancing performance is critically analyzed. Additionally, we examine state-of-the-art numerical modelling, comparing zero-dimensional to three-dimensional simulations and single-phase to two-phase flow dynamics. The impact of oxygen evolution and bubble dynamics on mass transport and performance is highlighted. Recent studies indicate that optimized electrode architectures can enhance mass transport efficiency by up to 20%, significantly improving PEMEC operation. Advancements in two-phase flow simulations are crucial for capturing multiphase transport effects, such as phase separation, electrolyte transport, and membrane hydration. However, challenges persist, including high catalyst costs, durability concerns, and scalable system designs. To address these, this review explores non-precious metal catalysts, nanostructured membranes, and machine-learning-assisted simulations, which have demonstrated cost reductions of up to 50% while maintaining electrochemical performance. Future research should integrate experimental validation with computational modelling to improve predictive accuracy and real-world performance. Addressing system control strategies for stable PEMEC operation under variable renewable energy conditions is essential for large-scale deployment. This review serves as a roadmap for future research, guiding the development of more efficient, durable, and economically viable PEM electrolyzers for green hydrogen production
Luteal phase oral dexamethasone administration alters endometrial steroid milieu
Get PDFWe previously published the DexFEM trial which showed in women with heavy menstrual bleeding oral dexamethasone reduces menstrual blood loss. Here, we report pharmacodynamic analysis exploring the likely mechanism for this effect. We studied oral dosing with dexamethasone during the mid-luteal phase of two menstrual cycles (1.5 mg daily, 5 days) in 5 women with HMB (6 recruited aged 41-50 years, 1 withdrew before treatment). Steroid hormones were profiled in serum and endometrium by liquid chromatography tandem mass spectrometry (LC-MS/MS). We found that following oral dosing, dexamethasone reached the endometrium, and that compared to preceding control cycle, cortisol (active), cortisone (inactive), and intermediate 11-deoxycortisol, were reduced in all samples assessed, both endometrial (n=4) and serum (n=5). Concentrations of androgens, androstenendione and testosterone, were reduced in serum but not in all tissue samples. This proof-of-concept pharmacodynamic study supports the inference that dexamethasone is effective in HMB by altering endometrial glucocorticoid concentrations.</p
Recently reported SARS-CoV-2 genomes suggested to be intermediate between the two early main lineages are instead likely derived
Get PDFUnderstanding the genomic diversity of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) at the outset of the coronavirus disease 2019 pandemic can provide insight into the circumstances leading to its emergence. Early SARS-CoV-2 genomic diversity has been classified into two distinct viral lineages, denoted “A” and “B,” which we hypothesized were separately introduced into humans. Recently published data contain two genomes with a haplotype suggested to be an evolutionary intermediate to these two lineages, known as “T/T.” We used a phylodynamic approach to analyze SARS-CoV-2 genomes from early 2020 to determine whether these two T/T genomes represent an evolutionarily intermediate haplotype between lineages A and B, or if they are a later descendent of either of these two lineages. We find that these two recently published T/T genomes do not represent an evolutionarily intermediate haplotype and were, instead, derived from either lineage A or lineage B. However, we cannot conclusively determine from which lineage they were derived. After including additional data from the start of the pandemic, including these two T/T genomes, we again find a discrepancy in the molecular clock when inferring the ancestral haplotype of SARS-CoV-2, corroborating existing evidence for the separate introductions of SARS-CoV-2 lineages A and B into the human population in late 2019
Abnormal predicates:Learning categorical defaults from probabilistic rules
Get PDFLearning defaults is a longstanding goal in the field of knowledge representation and reasoning. We provide a novel method for learning defaults by way of introducing a new predicate: the abnormal predicate, which explicitly covers all the exceptions to a rule, thus forming a default theory. Our proposed method for learning defaults is sound and complete for all rule-exceptions, and can be extended for use on other frameworks
PML mutants from arsenic-resistant patients reveal SUMO1-TOPORS and SUMO2/3-RNF4 degradation pathways
Get PDFArsenic effectively treats acute promyelocytic leukemia by inducing SUMO and ubiquitin-dependent degradation of the promyelocytic leukemia (PML)-retinoic acid receptor alpha oncogenic fusion protein. However, some patients relapse with arsenic-resistant disease because of missense mutations in PML. To determine the mechanistic basis for arsenic resistance, PML-/- cells were reconstituted with YFP fusions of wild-type PML-V and two common patient mutants: A216T and L217F. Both mutants were resistant to degradation by arsenic but for different biochemical reasons. Arsenic did not trigger SUMOylation of A216T PML, which failed to recruit the SUMO-targeting ubiquitin ligases RNF4 and TOPORS. L217F PML did respond with increased SUMO2/3 conjugation that facilitated RNF4 engagement but failed to reach the threshold of SUMO1 conjugation required to recruit TOPORS. Thus, neither mutant accumulated the appropriate polyubiquitin signal required for p97 binding. These PML mutants have revealed a convergence of SUMO1, SUMO2/3, TOPORS, and RNF4 that facilitates the arsenic-induced degradation of PML.</p
PRNP E146G mutation inherited prion disease:distinctive clinical, pathological and fluid biomarker features
Get PDFInherited prion diseases (IPDs) are phenotypically diverse neurodegenerative conditions caused by mutations in the prion protein gene (PRNP). We describe IPD due to a novel PRNP E146G mutation in a 50-year-old man presenting with slowly progressive dysarthria, prominent myoclonus especially in the lower limbs, and less prominent gait ataxia, pyramidal and extrapyramidal signs. Cognitive impairment was not overt at disease onset. MRI revealed cerebellar atrophy and white matter hyperintensities. His 46-year-old sister carries the mutation and has subtle gait ataxia and dysarthria. Both patients exhibit a distinctive fluid biomarker profile: in CSF S100B is > twofold upper limit of normal, total tau is moderately elevated, and neurofilament light chain, 14-3-3 and RT-QuIC are negative; in plasma there is marked elevation of GFAP but repeatedly normal neurofilament light chain. The proband's father died aged 55 following an 8-year dementing illness with similar presentation. Post-mortem revealed cerebellar cortical atrophy and profuse large PrP amyloid plaques across cerebral and cerebellar grey matter. Immunoblotting identified low molecular weight protease-resistant PrP fragments. E146G mutation IPD broadly fits into the historical Gerstmann-Sträussler-Scheinker disease spectrum but, based on deep clinical phenotyping of this initial pedigree, we highlight some distinctive features, which may aid in identification of this disease.</p
The Cultural Heritage Framework Programme:Highlighting the contribution of Marine Cultural Heritage to the UN decade of Ocean Science for sustainable development (2021–2030)
Get PDFThis paper considers the importance of including Marine Cultural Heritage (MCH) in the UN Decade of Ocean Science for Sustainable Development (2021–2030) in order to fully address the challenges facing the health of our oceans. It outlines the aims and objectives of the Cultural Heritage Framework Programme (CHFP), an official action of the UN Decade of Ocean Science and the only one that specifically deals with cultural heritage. The role of MCH in the Decade is discussed, and its under-appreciation in the UNESCO Cultural Conventions is outlined. The paper then presents the activities of the CHFP, discussing the main themes identified to date, and finishes by outlining the initiative’s next steps
A propositional encoding for first-order clausal entailment over infinitely many constants
Get PDFThere is a fundamental trade-off between the expressiveness of the language and the tractability of the reasoning task in knowledge representation. On the one hand it is widely acknowledged that relations and more generally, the expressiveness of first-order logic is extremely useful for capturing concepts required for common-sense reasoning. But at the same time the entailment problem is only semi-decidable.There have been a wide range of approaches to deal with this trade-off, from restricting the language to propositional logic to limit the expressiveness of the language in terms of the arity of the predicates (as in description logics) or the use of negation (as in Horn logic) to limit reasoning by weakening the entailment relation using non-standard semantics.In this work, we address a gap in this literature. We show that there is an intuitive fragment of first-order disjunctive knowledge, for which reasoning is decidable and can be reduced to propositional satisfiability. Knowledge bases in this fragment correspond to universally quantified first-order clauses, but without arity restrictions and without restrictions on the appearance of negation. Queries, however, are expected to be ground formulas. We achieve this result by showing how the entailment over infinitely many infinite-sized structures can be reduced to a search over finitely many finite-size structures. The crux of the argument lies in showing that constants not mentioned in the knowledge base and/or query behave identically (in a suitable formal sense). We then go on to also show that there is also an extension to this result for function symbols
Experimental Investigations of the Impact of H2, He, CH4, and CO2 Exposure on Kerogen Adsorption, Wettability, and Geomechanical Characteristics at Geo-Storage Conditions
Get PDFKerogen is the most abundant form of organic matter in the subsurface and its properties of adsorption, wettability, and geomechanics affect gas (H 2, He, CH 4, and CO 2) geo-storage (GGS) capacity and leakage risk. However, the impact of H 2, He, CH 4 and CO 2 exposure on kerogen adsorption, wettability and geomechanical characteristics at in-situ GGS conditions is still unclear, and thus large uncertainties exist in evaluating on GGS integrity. Therefore herein, kerogen properties were investigated experimentally at GGS conditions, based on isothermal adsorption, contact angle, and nanoindentation measurements. It is demonstrated that (1) the maximum adsorption capacity for H 2, CH 4, and CO 2 is 0.3789, 3.5360, and 5.2625 mol/kg, respectively (occurring at various thermophysical conditions), thus following the order H 2 < CH 4 < CO 2; (2) kerogen wettability ranges from weakly water-wet to gas-wet with its affinity to gases following the order He < CO 2 < H 2 < CH 4; and (3) after exposure to H 2, He, CH 4, and H 2 O for 3 minutes and to liquid CO 2 for 5 minutes, the Young’s modulus of kerogen decreases by 45, 32, 1, 50, and 70% respectively, while the kerogen pellet disintegrates after exposure to supercritical CO 2 for 3 minutes. This study provides key data for evaluating GGS, an important pathway for accelerating the energy transition, promoting advanced technology development, balancing the energy supply and demand, and mitigating carbon emissions.</p
Increased risk of provisional premenstrual dysphoric disorder (PMDD) among females with attention-deficit hyperactivity disorder (ADHD):A cross-sectional survey study
Get PDFBACKGROUND: Due to historical under-recognition of attention-deficit hyperactivity disorder (ADHD) among girls and women, little is known about female-specific factors that may affect individuals with ADHD, including those related to changes in ovarian hormones (e.g. across the menstrual cycle).AIMS: We investigated whether females with a self-reported clinical diagnosis of ADHD are more likely to experience premenstrual dysphoric disorder (PMDD). We also examined associations between PMDD and ADHD defined by a symptom and impairment threshold.METHOD: Participants were aged between 18 and 34 years, were assigned female at birth and were recruited via Prolific.com ( n = 715). Participants self-reported clinician diagnosis of ADHD, depression and anxiety. ADHD symptoms were assessed via the Adult ADHD Self-Report Scale (ASRS), to which we applied a DSM-5-based symptom and impairment cut-off ('ASRS-based ADHD'). PMDD symptoms were assessed via the Premenstrual Symptoms Screening Tool (PSST), which identifies provisional PMDD. Using Poisson regression models, we compared risk for provisional PMDD among females with ADHD (self-reported clinical diagnosis [ n = 102] or ASRS-based [ n = 229]) with a non-ADHD reference group ( n = 305). We additionally compared risk for provisional PMDD among individuals with ADHD and depression/anxiety diagnoses, ADHD only and a non-ADHD reference group. RESULTS: The prevalence of provisional PMDD was elevated among individuals with a self-reported clinical ADHD diagnosis (31.4%), and among participants with ASRS-based ADHD (41.1%), compared with the non-ADHD reference group (9.8%). Individuals with ASRS-based ADHD and depression and/or anxiety diagnoses were at highest risk for provisional PMDD (relative risk 4.53 [3.10, 6.61]) compared with the non-ADHD reference group.CONCLUSIONS: Clinicians should be aware that individuals with a diagnosis of ADHD, or with high ADHD symptom levels, and who have a menstrual cycle may be more likely to experience PMDD. Future research should investigate the underlying mechanisms that link ADHD and disorders associated with hormonal sensitivity, such as PMDD
Access Repository Dashboard
Do you manage Edinburgh Research Explorer? Access insider analytics, issue reports and manage access to outputs from your repository in the CORE Repository Dashboard!