695915 research outputs found
Sort by
Hierarchical zeolites: controllable synthesis, diffusion study and catalysis
No full textHierarchical zeolites refer to zeolitic materials having bi-/multi-modal interconnective pores arranged in order of certain ranks, which improve the molecular diffusion within their frameworks, and hence the performance in their applications such as adsorption and heterogeneous catalysis. Hierarchical zeolites are commonly produced via the ‘top-down’ post-synthetic treatments (such as dealumination and/or desilication) of pre-synthesised zeolites (i.e. the parent zeolites) and the ‘bottom-up’ synthesis-by-design methods (such as soft/hard templating). This review presents the recent advances (from 2001 to 2020) in the strategies of making hierarchical zeolites, with the emphasis on the ‘top-down’ approaches due to their relatively high practicality. Since hierarchical zeolites are proposed to improve intracrystalline diffusion, experimental studies of guest molecules diffusion in hierarchical zeolites is also reviewed. Additionally, catalytic applications of hierarchical zeolites, in comparison with the conventional microporous pristine zeolites, are also commented to highlight the advantages of hierarchical zeolites to improve catalysis.Keywords Hierarchical zeolites; Post-synthetic treatment; Diffusion; Pulsed-field gradient nuclear magnetic resonance (PFG-NMR); Catalysis<br/
Modelling annual scintillation arc variations in PSR J1643−1224 using the large european array for pulsars
No full textIn this work we study variations in the parabolic scintillation arcs of the binary millisecond pulsar PSR J1643−1224 over five years using the Large European Array for Pulsars (LEAP). The 2D power spectrum of scintillation, called the secondary spectrum, often shows a parabolic distribution of power, where the arc curvature encodes the relative velocities and distances of the pulsar, ionised interstellar medium (IISM), and Earth. We observe a clear parabolic scintillation arc which varies in curvaturethroughout the year. The distribution of power in the secondary spectra are inconsistent with a single scattering screen which is fully 1D, or entirely isotropic. We fit the observed arc curvature variations with two models; an isotropic scattering screen, and a model with two independent 1D screens. We measure the distance to the scattering screen to be in the range 114-223 pc, depending on the model, consistent with the known distance of the foreground large-diameter HII region Sh 2-27 (112 ± 17 pc), suggesting that it is the dominant source of scattering. We obtain only weak constraints on the pulsar’s orbital inclination and angle of periastron, since the scintillation pattern is not very sensitive to the pulsar’s motion, since the screen is much closer to the Earth than the pulsar. More measurements of this kind - where scattering screens can be associated with foreground objects - will help to inform the origins and distribution of scattering screens within our galaxy.Key words: pulsars: general – pulsars:individual ( PSR J1643−1224) – ISM:HII regio
Summary of Model Checking C++ Programs
No full textThis is an extended abstract of the article “Model Checking C++ Programs” by Felipe R. Monteiro, Mikhail R. Gadelha, and Lucas C. Cordeiro. We describe and evaluate anovel verification approach based on bounded model checking (BMC) and satisfiability modulo theories (SMT) to verify C++ programs. Our verification approach analyzes bounded C++ programs by encoding into SMT various sophisticated features that the C++ programming language offers, such as templates, inheritance, polymorphism, exception handling, and the StandardTemplate Libraries. We implemented our verification approach on top of ESBMC. We compare ESBMC to LLBMC and DIVINE, which are state-of-the-art verifiers to check C++ programs directly from the LLVM bitcode. Experimental results show thatESBMC can handle a wide range of C++ programs, presenting a higher number of correct verification results. Additionally, ESBMC has been applied to a commercial C++ application in the telecommunication domain and successfully detected arithmeticoverflow errors, which could lead to security vulnerabilities.Index Terms—C++, memory safety, model checking, SMT, software verification<br/
Connecting Communities GM PCIE Forum 2021 Sharing Event Week of the 18th October 2021
No full textThe aim of this session will be to describe how we have co-produced a guide for patients and carers to help to address key patient safety questions and identify key points where they can make their care safer. We worked with patients, carers, general practitioners and pharmacists from across Greater Manchester. Background: Patients and carers should be actively involved in their patient safety and empowered to use person-centred approaches where they are asked to both identify safety concerns and partner in preventing them.Approach: We conducted three workshops with patients, carers, community pharmacists and general practitioners to develop and refine the patient safety guide. Alongside these workshops we worked with a public involvement group to develop the approach and the guide.Results: Co-developing the patient safety guide provided insight to improve care. The approach helped to identify the main factors that influenced people’s engagement with patient safety and actions that people could do to improve their patient safety. The importance of communication, understanding roles and responsibilities, and developing partnerships between patients and healthcare providers were considered essential for actively involving patients in patient safety. Discussion:Using a co-design approach identified important points where patient safety in routine primary care can be improved using patient and clinician experiences with a key focus on how the guide could be used in practice. The patient safety guide is the first guide to be developed for primary care, co-designed with patients, carers, general practitioners and pharmacists. <br/
The long-term influence of Open Access on the scientific and social impact of dental journal articles: An updated analysis
No full textObjectives: To investigate whether dental journal articles that are open access (OA) receive greater citation counts and higher Altmetric Attention Scores (AAS) than articles that are non-OA in the long term.Methods: Eligible dental journal articles published in 2013 were identified via PubMed, and Web of science, Unpaywall and corresponding URLs were manually checked to determine the OA status of each included article 7 years after publication. Citation counts were extracted from Web of Science and Scopus, and AAS was harvested from the Altmetric Explorer. Multivariable general linear regression analyses were performed to investigate the association between OA and citation count, as well as between OA and AAS.Results: Among the 755 included articles, 309 (40.9%) were freely available online. Among the 309 OA articles, articles available from publishers accounted for 64.4% (199/309) of all OA articles, and those available through self-archiving accounted for 56.0% (173/309). According to regression analyses, OA articles had significantly greater citation counts (P = 0.001) and AAS (P < 0.001) than non-OA articles.Conclusions/clinical significance: In the field of dentistry, about 41% of journal articles are OA 7 years after publication, and OA articles available from the publishers are more common than those from authors through self-archiving. OA articles tend to have greater scientific and social impact than non-OA articles in the long term.Keywords: open access; dentistry; bibliometrics; altmetrics; evidence-based dentistry; research wast
Non-thermal plasma catalytic ammonia synthesis over Ni catalyst supported on MgO/SBA-15
No full textNon-thermal plasma (NTP) enabled ammonia synthesis is recently considered a sustainable technique as compared to the Haber–Bosch (HB) process. Herein we demonstrate the NTP catalytic ammonia synthesis in an dielectric barrier discharge (DBD) plasma reactor using mesoporous silica (SBA-15) supported Ni catalysts under ambient condition. Specifically, two types of MgO modified SBA-15 were developed (as the catalyst support) by the in situ doping and incipient wetness impregnation (IWI) methods, respectively. Experimental results demonstrated that the addition of Mg in SBA-15 via the IWI method favored the ammonia synthesis rate under NTP conditions. The developed Ni-Mg0.02/SBA-15-IWI catalyst exhibited the highest ammonia synthesis rate and energy efficiency value of 4.4 mmol h−1 gcat−1 and 1.05 gNH3 kWh−1, outperformed the Ni/SBA-15 and Ni-Mg0.02/SBA-15-In situ catalyst (i.e. the doping of Mg via in situ method). HRTEM and EDS mapping analysis showed that the addition of Mg (on SBA-15) via the IWI method favored the dispersion of Ni on the catalyst surface and the Ni-support interaction, i.e., uniform distribution of Ni nanoparticles of 5.1 ± 1.1 nm in the Ni-Mg0.02/SBA-15-IWI catalyst, which enhanced the ammonia synthesis performance. Finally, the developed Ni-Mg0.02/SBA-15-IWI catalyst displayed a slight decrease of ammonia synthesis rate from ~4.42 to ~3.89 mmol h−1 gcat−1 over a 40 h on stream, which could be attriburated to the aggregation of Ni particles based on the post-reaction HRTEM analysis.<br/
Home-working and e-communications with colleagues during COVID-19: impact on psychological health and productivity
No full textBACKGROUND: During the COVID-19 pandemic, there has been a wide-scale shift to home working for many employees in the UK. We hypothesised that during the lockdown, employees working from home would rely more heavily on work emails and other forms of e-communications to remain connected to colleagues and the work place. We additionally hypothesised that an increase in e-communications with colleagues outside of normal working hours would be associated with poorer health and productivity. METHODS: We surveyed N=204 full-time UK-based employees during October 2019 (pre-COVID) and during April 2020 (n=153, during-COVID). Ninety-three two participants indicated that they were working exclusively from home during-COVID, and were therefore included in analyses. RESULTS: Email volume was higher during-COVID than pre-COVID, and the use of instant messaging and video calls outside of normal working hours increased. Change in email engagement outside of normal working hours was not associated with health and productivity Change in email engagement outside of normal working hours was not associated with poorer health and productivity. However, increases in other forms of e-communications during leisure time was associated with poorer physical and mental health. CONCLUSIONS: A legacy of COVID-19 may be to accelerate a trend towards greater levels of home working, therefore understanding how to maintain health and productivity when working from home will be critical to ensure business continuity. Ours is the first study to suggest that increases in work-related video calls, instant messages and social media engagement outside of normal working hours may be detrimental to employee health and productivity
Elucidating Heterogeneous Iron Biomineralization Patterns in a Denitrifying As(III)-Oxidizing Bacterium: Implications for Arsenic Immobilization
No full textAnaerobic nitrate-dependent iron(II) oxidation is a process common to many bacterial species, which promotes the formation of Fe(III) minerals that can influence the fate of soil and groundwater pollutants, such as arsenic. Herein, we investigated simultaneous nitrate-dependent Fe(II) and As(III) oxidation by Acidovorax sp. strain ST3 with the aim of studying the Fe biominerals formed, their As immobilization capabilities and the metabolic effect on cells. X-ray powder diffraction (XRD) and scanning transmission electron microscopy (STEM) nanodiffraction were applied for biomineral characterization in bulk and at the nanoscale, respectively. NanoSIMS (nanoscale secondary ion mass spectrometry) was used to map the intra and extracellular As and Fe distribution at the single-cell level and to trace metabolically active cells, by incorporation of a 13C-labeled substrate (acetate). Metabolic heterogeneity among bacterial cells was detected, with periplasmic Fe mineral encrustation deleterious to cell metabolism. Interestingly, Fe and As were not co-localized in all cells, indicating delocalized sites of As(III) and Fe(II) oxidation. The Fe(III) minerals lepidocrocite and goethite were identified in XRD, although only lepidocrocite was identified via STEM nanodiffraction. Extracellular amorphous nanoparticles were formed earlier and retained more As(III/V) than crystalline “flakes” of lepidocrocite, indicating that longer incubation periods promote the formation of more crystalline minerals with lower As retention capabilities. Thus, the addition of nitrate promotes Fe(II) oxidation and formation of Fe(III) biominerals by ST3 cells which retain As(III/V), and although this process was metabolically detrimental to some cells, it warrants further examination as a viable mechanism for As removal in anoxic environments by biostimulation with nitrate
Glucose Treatment Targets in Pregnancy - A Review of Evidence and Guidelines
No full textBackgroundMaternal diabetes mellitus during pregnancy is associated with an increased risk of pregnancy complications for both the mother and the fetus. One of the most prevalent complications is pathological fetal growth, and particularly infants are born large for gestational age (LGA), which leads to problematic deliveries, including the need for caesarean section, instrumental delivery and further perinatal complications. Glucose monitoring during pregnancy is essential for ensuring appropriate glycaemic control and to reduce these associated risks. The current methods of glucose monitoring include measuring glycosylated haemoglobin (HbA1c), self-monitoring of capillary blood glucose (SMBG), and more recently, continuous glucose monitoring (CGM). Observational studies and randomised controlled trials (RCTs) have assessed the appropriate glycaemic targets for HbA1c, SMBG, and CGM in relation to pregnancy outcomes. ObjectiveIn this review we identify current international guidelines on glycaemic targets and review the supporting evidence. MethodWe performed an extensive literature search on glycaemic targets in pregnancies affected by diabetes and we researched international guidelines from recognised societies.Results and ConclusionThe majority of studies used to define the glucose targets associated with the best pregnancy outcomes, across all modalities, were in women with type 1 diabetes. There were limited studies in women with type 2 diabetes and gestational diabetes. We therefore suggest that further research needs to be conducted on glucose targets and clinical outcomes specifically in these populations where CGM technology offers the greatest potential for monitoring glucose and improving pregnancy outcomes.<br/