113 results on '"David McNulty"'
Search Results
2. The impact of changes in coding on mortality reports using the example of sepsis
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Catherine Atkin, Tanya Pankhurst, David McNulty, Ann Keogh, Suzy Gallier, Domenico Pagano, Elizabeth Sapey, and Simon Ball
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Morbidity ,Clinical coding ,Real world data ,Epidemiology ,Sepsis ,Mortality ,Computer applications to medicine. Medical informatics ,R858-859.7 - Abstract
Abstract Objectives NHS Digital issued new guidance on sepsis coding in April 2017 which was further modified in April 2018. During these timeframes some centres reported increased sepsis associated mortality, whilst others reported reduced mortality, in some cases coincident with specific quality improvement programmes. We hypothesised that changes in reported mortality could not be separated from changes in coding practice. Methods Hospital Episode Statistics from the Admitted Patient Care dataset for NHS hospitals in England, from April 2016 to March 2020 were analysed. Admissions of adults with sepsis: an International Classification of Diseases 10 (ICD-10) code associated with the Agency for Healthcare Research and Quality Clinical Classifications Software class ‘Septicaemia (except in labour)’, were assessed. Patient comorbidities were defined by other ICD-10 codes recorded within the admission episode. Results 1,081,565 hospital episodes with a coded diagnosis of sepsis were studied. After April 2017 there was a significant increase in admission episodes with sepsis coded as the primary reason for admission. There were significant changes in the case-mix of patients with a primary diagnosis of sepsis after April 2017. An analysis of case-mix, hospital and year treated as random effects, defined a small reduction in sepsis associated mortality across England following the first change in coding guidance. No centre specific improvement in outcome could be separated from these random-effects. Conclusion Changes in sepsis coding practice altered case-mix and case selection, in ways that varied between centres. This was associated with changes in centre-specific sepsis associated mortality, over time. According to the direction of change these may be interpreted either as requiring local investigation for cause or as supporting coincident changes in clinical practice. A whole system analysis showed that centre specific changes in mortality cannot be separated from system-wide changes. Caution is therefore required when interpreting sepsis outcomes in England, particularly when using single centre studies to inform or support guidance or policy.
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- 2022
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3. Variability and performance of NHS England’s ‘reason to reside’ criteria in predicting hospital discharge in acute hospitals in England: a retrospective, observational cohort study
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Elizabeth Sapey, Simon Ball, David McNulty, Felicity Evison, Suzy Gallier, and Katherine Reeves
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Medicine - Abstract
Objectives NHS England (NHSE) advocates ‘reason to reside’ (R2R) criteria to support discharge planning. The proportion of patients without R2R and their rate of discharge are reported daily by acute hospitals in England. R2R has no interoperable standardised data model (SDM), and its performance has not been validated. We aimed to understand the degree of intercentre and intracentre variation in R2R-related metrics reported to NHSE, define an SDM implemented within a single centre Electronic Health Record to generate an electronic R2R (eR2R) and evaluate its performance in predicting subsequent discharge.Design Retrospective observational cohort study using routinely collected health data.Setting 122 NHS Trusts in England for national reporting and an acute hospital in England for local reporting.Participants 6 602 706 patient-days were analysed using 3-month national data and 1 039 592 patient-days, using 3-year single centre data.Main outcome measures Variability in R2R-related metrics reported to NHSE. Performance of eR2R in predicting discharge within 24 hours.Results There were high levels of intracentre and intercentre variability in R2R-related metrics (p
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- 2022
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4. Early renal function trajectories, cytomegalovirus serostatus and long-term graft outcomes in kidney transplant recipients
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Jonathan P. Law, Richard Borrows, David McNulty, Adnan Sharif, and Charles J. Ferro
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Allograft function ,Bayesian ,Cytomegalovirus serostatus ,Estimated glomerular filtration rate ,Kidney transplantation ,Diseases of the genitourinary system. Urology ,RC870-923 - Abstract
Abstract Background Improved recognition of factors influencing graft survival has led to better short-term kidney transplant outcomes. However, efforts to prevent long-term graft decline and improve graft survival have seen more modest improvements. The adoption of electronic health records has enabled better recording and identification of donor-recipient factors through the use of modern statistical techniques. We have previously shown in a prevalent renal transplant population that episodes of rapid deterioration are associated with graft loss. Methods Estimated glomerular filtration rates (eGFR) between 3 and 27 months after transplantation were collected from 310 kidney transplant recipients. We utilised a Bayesian approach to estimate the most likely eGFR trajectory as a smooth curve from an average of 10,000 Monte Carlo samples. The probability of having an episode of rapid deterioration (decline greater than 5 ml/min/1.73 m2 per year in any 1-month period) was calculated. Graft loss and mortality data was collected over a median follow-up period of 8 years. Factors associated with having an episode of rapid deterioration and associations with long-term graft loss were explored. Results In multivariable Cox Proportional Hazard analysis, a probability greater than 0.8 of rapid deterioration was associated with long-term death-censored graft loss (Hazard ratio 2.17; 95% Confidence intervals [CI] 1.04–4.55). In separate multivariable logistic regression models, cytomegalovirus (CMV) serostatus donor positive to recipient positive (Odds ratio [OR] 3.82; 95%CI 1.63–8.97), CMV donor positive (OR 2.06; 95%CI 1.15–3.68), and CMV recipient positive (OR 2.03; 95%CI 1.14–3.60) were associated with having a greater than 0.8 probability of an episode of rapid deterioration. Conclusions Early episodes of rapid deterioration are associated with long-term death-censored graft loss and are associated with cytomegalovirus seropositivity. Further study is required to better manage these potentially modifiable risks factors and improve long-term graft survival.
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- 2021
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5. Development of risk prediction models to predict urine culture growth for adults with suspected urinary tract infection in the emergency department: protocol for an electronic health record study from a single UK university hospital
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Patrick Rockenschaub, Martin J. Gill, David McNulty, Orlagh Carroll, Nick Freemantle, and Laura Shallcross
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Protocol ,Diagnosis ,Urinary tract infection ,Prediction models ,Hospital ,Medicine (General) ,R5-920 - Abstract
Abstract Background Urinary tract infection (UTI) is a leading cause of hospital admissions and is diagnosed based on urinary symptoms and microbiological cultures. Due to lags in the availability of culture results of up to 72 h, and the limitations of routine diagnostics, many patients with suspected UTI are started on antibiotic treatment unnecessarily. Predictive models based on routinely collected clinical information may help clinicians to rule out a diagnosis of bacterial UTI in low-risk patients shortly after hospital admission, providing additional evidence to guide antibiotic treatment decisions. Methods Using electronic hospital records from Queen Elizabeth Hospital Birmingham (QEHB) collected between 2011 and 2017, we aim to develop a series of models that estimate the probability of bacterial UTI at presentation in the emergency department (ED) among individuals with suspected UTI syndromes. Predictions will be made during ED attendance and at different time points after hospital admission to assess whether predictive performance may be improved over time as more information becomes available about patient status. All models will be externally validated for expected future performance using QEHB data from 2018/2019. Discussion Risk prediction models using electronic health records offer a new approach to improve antibiotic prescribing decisions, integrating clinical and demographic data with test results to stratify patients according to their probability of bacterial infection. Used in conjunction with expert opinion, they may help clinicians to identify patients that benefit the most from early antibiotic cessation.
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- 2020
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6. Diagnostic uncertainty and urinary tract infection in the emergency department: a cohort study from a UK hospital
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Laura J. Shallcross, Patrick Rockenschaub, David McNulty, Nick Freemantle, Andrew Hayward, and Martin J. Gill
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Antimicrobial resistance ,Antimicrobial stewardship ,Urinary tract infection ,Emergency department ,Electronic health records ,Special situations and conditions ,RC952-1245 ,Medical emergencies. Critical care. Intensive care. First aid ,RC86-88.9 - Abstract
Abstract Background Suspected urinary tract infection (UTI) syndromes are a common reason for empirical antibiotics to be prescribed in the Emergency Department (ED), but differentiating UTI from other conditions with a similar presentation is challenging. We investigated how often an ED diagnosis of UTI is confirmed clinically/microbiologically, and described conditions which present as UTI syndromes. Methods Observational study using electronic health records from patients who attended the ED with suspected UTI and had a urine sample submitted for culture. We compared the ED diagnosis to diagnosis at discharge from hospital (ICD-10 codes), and estimated the proportion of cases with clinical/microbiological evidence of UTI. Results Two hundred eighty nine patients had an ED diagnosis of UTI syndrome comprising: lower UTI (191), pyelonephritis (56) and urosepsis (42). In patients admitted to hospital with an ED diagnosis of lower UTI, pyelonephritis or urosepsis, clinical/microbiological evidence of UTI was lacking in 61/103, 33/54 and 31/42 cases respectively. The ED diagnosis was concordant with the main reason for admission in less than 40% of patients with UTI syndromes, and antibiotics were stopped within 72 h in 37/161 patients. Conclusions Clinical/microbiological evidence of UTI was lacking in 60–70% of patients, suggesting scope to revise empirical prescribing decisions for UTI syndromes in light of microbial culture and clinical progression.
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- 2020
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7. Ethnicity and risk of death in patients hospitalised for COVID-19 infection in the UK: an observational cohort study in an urban catchment area
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Elizabeth Sapey, Krishnarajah Nirantharakumar, Paul Cockwell, Simon Ball, Alastair K Denniston, Peter Nightingale, David McNulty, Domenico Pagano, Felicity Evison, Tanya Pankhurst, Katharine Reeves, Suzy Gallier, Peter Diggle, M Ahmed, Jamie Coleman, Rifat Rashid, Chris Mainey, Hannah Crothers, Lylah Irshad, Maxim Harris, Theodore Nabav, A Kolesnyk, A Liaqat, Chirag Dave, and Khaled ElFandi
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Medicine ,Diseases of the respiratory system ,RC705-779 - Abstract
Background Studies suggest that certain black and Asian minority ethnic groups experience poorer outcomes from COVID-19, but these studies have not provided insight into potential reasons for this. We hypothesised that outcomes would be poorer for those of South Asian ethnicity hospitalised from a confirmed SARS-CoV-2 infection, once confounding factors, health-seeking behaviours and community demographics were considered, and that this might reflect a more aggressive disease course in these patients.Methods Patients with confirmed SARS-CoV-2 infection requiring admission to University Hospitals Birmingham NHS Foundation Trust (UHB) in Birmingham, UK between 10 March 2020 and 17 April 2020 were included. Standardised admission ratio (SAR) and standardised mortality ratio (SMR) were calculated using observed COVID-19 admissions/deaths and 2011 census data. Adjusted HR for mortality was estimated using Cox proportional hazard model adjusting and propensity score matching.Results All patients admitted to UHB with COVID-19 during the study period were included (2217 in total). 58% were male, 69.5% were white and the majority (80.2%) had comorbidities. 18.5% were of South Asian ethnicity, and these patients were more likely to be younger and have no comorbidities, but twice the prevalence of diabetes than white patients. SAR and SMR suggested more admissions and deaths in South Asian patients than would be predicted and they were more likely to present with severe disease despite no delay in presentation since symptom onset. South Asian ethnicity was associated with an increased risk of death, both by Cox regression (HR 1.4, 95% CI 1.2 to 1.8), after adjusting for age, sex, deprivation and comorbidities, and by propensity score matching, matching for the same factors but categorising ethnicity into South Asian or not (HR 1.3, 95% CI 1.0 to 1.6).Conclusions Those of South Asian ethnicity appear at risk of worse COVID-19 outcomes. Further studies need to establish the underlying mechanistic pathways.
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- 2020
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8. Sex‐Specific Differences in Survival and Heart Failure Hospitalization After Cardiac Resynchronization Therapy With or Without Defibrillation
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Francisco Leyva, Tian Qiu, Abbasin Zegard, David McNulty, Felicity Evison, Daniel Ray, and Maurizio Gasparini
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cardiac resynchronization therapy ,female sex ,implantable cardioverter defibrillator ,Diseases of the circulatory (Cardiovascular) system ,RC666-701 - Abstract
Background Women are underrepresented in cardiac resynchronization therapy (CRT) trials. Some studies suggest that women fare better than men after CRT. We sought to explore clinical outcomes in women and men undergoing CRT‐defibrillation or CRT‐pacing in real‐world clinical practice. Methods and Results A national database (Hospital Episode Statistics for England) was used to quantify clinical outcomes in 43 730 patients (women: 10 890 [24.9%]; men: 32 840 [75.1%]) undergoing CRT over 7.6 years, (median follow‐up 2.2 years, interquartile range, 1–4 years). In analysis of the total population, the primary end point of total mortality (adjusted hazard ratio [aHR], 0.73; 95% CI, 0.69–0.76) and the secondary end point of total mortality or heart failure hospitalization (aHR, 0.79, 95% CI 0.75–0.82) were lower in women, independent of known confounders. Total mortality (aHR, 0.73; 95% CI, 0.70–0.76) and total mortality or heart failure hospitalization (aHR, 0.79; 95% CI, 0.75–0.82) were lower for CRT‐defibrillation than for CRT‐pacing. In analyses of patients with (aHR, 0.89; 95% CI, 0.80–0.98) or without (aHR, 0.70; 95% CI, 0.66–0.73) a myocardial infarction, women had a lower total mortality. In sex‐specific analyses, total mortality was lower after CRT‐defibrillation in women (aHR, 0.83; P=0.013) and men (aHR, 0.69; P
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- 2019
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9. 2D and 3D photonic crystal materials for photocatalysis and electrochemical energy storage and conversion
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Gillian Collins, Eileen Armstrong, David McNulty, Sally O’Hanlon, Hugh Geaney, and Colm O’Dwyer
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photonic crystal ,inverse opal ,photoelectrochemistry ,li-ion battery ,energy storage ,energy conversion ,catalysis ,Materials of engineering and construction. Mechanics of materials ,TA401-492 ,Biotechnology ,TP248.13-248.65 - Abstract
This perspective reviews recent advances in inverse opal structures, how they have been developed, studied and applied as catalysts, catalyst support materials, as electrode materials for batteries, water splitting applications, solar-to-fuel conversion and electrochromics, and finally as photonic photocatalysts and photoelectrocatalysts. Throughout, we detail some of the salient optical characteristics that underpin recent results and form the basis for light-matter interactions that span electrochemical energy conversion systems as well as photocatalytic systems. Strategies for using 2D as well as 3D structures, ordered macroporous materials such as inverse opals are summarized and recent work on plasmonic–photonic coupling in metal nanoparticle-infiltrated wide band gap inverse opals for enhanced photoelectrochemistry are provided.
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- 2016
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10. A review of Li-ion batteries for autonomous mobile robots: perspectives and outlook for the future
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David McNulty, Aaron Hennessy, Mei Li, Eddie Armstrong, and Kevin M. Ryan
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Chemical sciences ,autonomous mobile robots (AMRs) ,Renewable Energy, Sustainability and the Environment ,FOS: Chemical sciences ,AMRs ,Li-ion batteries ,Energy Engineering and Power Technology ,Electrical and Electronic Engineering ,Physical and Theoretical Chemistry ,34 Chemical sciences - Abstract
The development of advanced autonomous mobile robots (AMRs) is essential for achieving the flexible work environment necessary for smart manufacturing. Complex perception, locomotion and navigation systems comprised of many sensors and powerful processors allow AMRs to continuously monitor their surroundings and internal systems. AMRs that can move freely around an industrial facility are increasingly required for 24/7 industrial processes. The energy requirements of AMRs can include the need for high power for tasks such as lifting and transporting as well as low power for the various onboard sensors. Total operating time between charges is dependent on factors such as distance travelled, payload power consumption, payload/cargo mass and AMR attachments such as tilt trays or robotic arms. This review discusses pre-existing commercial AMRs, their power consumption and compares the specifications of battery packs which are being used in the current generation of AMRs. This is followed by a detailed discussion about lithium-ion battery operation and recommendations for cathode and anode materials to replace traditionally used electrode materials to meet the growing power demands of next generation AMRs in the short to medium term (5–10 years) and in the long term (10+ years).
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- 2023
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11. Can the application of machine learning to electronic health records guide antibiotic prescribing decisions for suspected urinary tract infection in the Emergency Department?
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Patrick Rockenschaub, Martin J. Gill, David McNulty, Orlagh Carroll, Nick Freemantle, and Laura Shallcross
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BackgroundUrinary tract infections (UTIs) are a major cause of emergency hospital admissions, but it remains challenging to diagnose them reliably. Application of machine learning (ML) to routine patient data could support clinical decision-making. We developed a ML model for bacteriuria in the ED and evaluated its performance in key patient groups to determine scope for its future use in clinical practice.MethodsWe used retrospective electronic health records from a large UK hospital (2011-2019). Non-pregnant adults who attended the ED and had a urine sample cultured were eligible for inclusion. The primary outcome was predominant bacterial growth ≥104 cfu/mL in urine. Predictors included demography, medical history, ED diagnoses, blood tests, and urine flow cytometry. Linear and tree-based models were trained via repeated cross-validation, re-calibrated, and validated on data from 2018/19. Changes in performance were investigated by age, sex, ethnicity, and suspected ED diagnosis, and compared to clinical judgement.ResultsAmong 12,680 included samples, 4,677 (36.9%) showed bacterial growth. Relying primarily on flow cytometry parameters, our best model achieved an area under the ROC curve (AUC) of 0.813 (95% CI 0.792-0.834) in the test data, and achieved both higher sensitivity and specificity compared to proxies of clinician’s judgement. Performance remained stable for white and non-white patients but was lower during a period of laboratory procedure change in 2015, in patients ≥65 years (AUC 0.783, 95% CI 0.752-0.815), in men (AUC 0.758, 95% CI 0.717-0.798). Performance was also slightly reduced in patients with recorded suspicion of UTI (AUC 0.797, 95% CI 0.765-0.828).ConclusionsOur results suggest scope for use of ML in ED decision making for suspected UTI but performance varied with patient characteristics. Clinical utility of predictive models for UTI is therefore likely to differ for important patient subgroups including women
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- 2022
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12. The variability and performance of NHS England’s 'Reason to Reside' criteria in predicting hospital discharge in acute hospitals in England. An observational study
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Elizabeth Sapey, Suzy Gallier, Felicity Evison, James Hodson, David McNulty, Katherine Reeves, and Simon Ball
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ObjectivesNHS England (NHSE) advocates using “reason to reside” (R2R) criteria to generate a binary outcome, which supports discharge related clinical decision making. The proportion of patients without R2R and their rate of discharge are reported daily, by acute hospitals in England. R2R is however, not based upon an inter-operable standardised data model (SDM), nor has its performance been validated against its purpose. We aimed to understand the degree of inter- and intra-centre variation in R2R related metrics reported to NHSE, define a SDM implemented within a single centre Electronic Health Record to generate an eR2R, and evaluate its performance in predicting subsequent discharge.DesignRetrospective observational cohort study using routinely collected health data.Setting122 NHS Trusts in England for national reporting and an adult acute hospital in England for local reporting.Participants6,602,706 patient-days were analysed using 3 months national data and 1,039,592 patient-days, using 3 years single centre data.Main outcome measuresVariability in R2R related metrics reported to NHSE. Performance of eR2R in predicting discharge within 24 hours.ResultsThere were high levels of intra and inter-centre variability in R2R related metrics (pConclusionsR2R related performance metrics are highly variable between and within acute Trusts in England. Although case-mix or community care provision may account for some variability, the absence of a SDM is a major barrier to meaningful interpretation of these metrics. The performance of eR2R based on two alternative SDM’s was poor, such that they could not meaningfully contribute to clinical decision making or evaluation of performance.SummaryWhat is knownThere is considerable pressure on hospital bed capacity and significant variation in hospital discharges with concerns raised about delays in discharge planning across National Health Service Trusts. To address this, the UK Government developed a policy and criteria to identify in-patients in whom discharge home, or to a less acute setting, should be considered. The criteria, called “reasons to reside” (R2R) have been promoted as a tool to improve discharge planning and are a mandated metric for central reporting. The performance of R2R has not been assessed.What this study addsThis study suggests a low performance of the R2R criteria as a clinical tool to identify patients suitable for discharge, and questions its usefulness as a reported metric in its current form. There is significant intra and inter-centre variability in both the reported proportion of patients not meeting R2R criteria, and the proportion of patients not meeting R2R criteria who were later discharged. The proportion of patients not meeting R2R criteria correlates poorly with their rate of discharge over the subsequent 24 hours and the performance of the R2R criteria as dichotomous test to identify patients suitable for discharge is low. Further, the R2R criteria are not a stable phenomenon, with more than half of those who remain in hospital without R2R, subsequently acquiring a R2R during the admission.
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- 2022
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13. Ordered Macroporous Photonic Crystal Hot Electron Plasmonic Photocatalysts
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Changyu Hu, David McNulty, Colm O'Dwyer, Darragh Buckley, Gillian Collins, Colm Glynn, and Alex Lonergan
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Materials science ,business.industry ,Optoelectronics ,business ,Hot electron ,Plasmon ,Photonic crystal - Abstract
Plasmon-enhanced photocatalysis provides opportunities for controlling chemical reaction rates, especially when the influence of the light is to enhance or alter charge transfer properties. Semiconductor photocatalysts with an inverse opal or photonic crystal structure not only provide large, open and accessible surface area, they are electrically interconnected as a porous network. This becomes a useful scaffold to dock metallic nanoparticles whose size can be tuned to absorb specific frequencies resonant with their localised surface plasmon resonance. Coupling this with the nature of the metal-semiconductor band structure (where the metal oxide is wide band gap) and exploiting certain properties of photonic crystals, more efficient photocatalysts are possible. We demonstrate semiconducting photonic crystal plasmonic photocatalysts using V2O5 and TiO2 as visible light semiconductor catalysts that showed superior performance to a conventional TiO2 support for hydrogenation of 4-nitrophenol. The approach married the photonic band gap, metal oxide semiconductor bandgap, slow photon effect and localised surface plasmon polaritons to maximum photon absorption to modulate charge transfer and electron density either in the metal nanoparticle, or the conduction band of the semiconductor to give a better photocatalyst. References [1] S. Linic, U. Aslam, C. Boerigter, M. Morabito, Nat. Mater. 14, 567 (2015) [2] S. Linic, P. Christopher, D. B. Ingram, Nat. Mater. 10, 911 (2011) [3] G. Collins, A. Lonergan, D. McNulty, C. Glynn, D. Buckley, C. Hu, and C. O’Dwyer, Adv. Mater. Interfaces. 7, 1901805 (2020). [4] E. Armstrong, C. O’Dwyer, J. Mater. Chem. C 3, 6109 (2015) [5] C. O’Dwyer, Adv. Mater. 28, 5681 (2016) [6] T. Baba, Nat. Photon. 2, 465 (2008) [7] G. Collins, E. Armstrong, D. McNulty, S. O’Hanlon, H. Geaney, C. O’Dwyer, Sci. Technol. Adv. Mater. 17, 563 (2016) [8] A. Lonergan, D. McNulty, C. O’Dwyer, J. Appl. Phys. 124, 095106 (2018) [9] G. Collins, M. Blomker, M. Osaik, J. D. Holmes, M. Bredol, C. O’Dwyer, Chem. Mater. 25, 4312 (2013) [10] J. Liu, H. Zhao, M. Wu, B. Van der Schueren, Y. Li, O. Deparis, J. H. Ye, G. A. Ozin, T. Hasan, B. L. Su, Adv. Mater. 29, 1605349 (2017) [11] S. O’Hanlon, D. McNulty, C. O’Dwyer, J. Electrochem. Soc. 164, D111 (2017) [12] D. McNulty, E. Carroll, C. O’Dwyer, Adv. Energy Mater. 7, 1602291 (2017) Figure 1. V2O5 3D macroporous inverse opal photonic crystal decorated with Au nanoparticles. Figure 1
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- 2020
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14. Photoconductive Solution Processed ZnO Quasi-superlattice Films
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Vitaly Z. Zubialevich, Darragh Buckley, Colm O'Dwyer, Peter J. Parbrook, Farzan Gity, David McNulty, Saikumar Inguva, and Paul K. Hurley
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Materials science ,business.industry ,Superlattice ,Photoconductivity ,Optoelectronics ,business ,Solution processed - Abstract
Zinc oxide (ZnO) and Al-doped ZnO are important optoelectronic materials. ZnO in particular has a wide band gap (Eg ~ 3.3 eV at 300 K), large exciton binding energy (~66 meV) and especially for the variety of methods by which it can be processed. Moreover, ZnO is readily able to alloy with other metals in the oxide form and has a lattice that can facilitate interstitial doping using several metals, including Al and Sn. This gives ZnO a key role in optoelectronics, metal oxide thin films and thin film transistor (TFT) technologies. We demonstrate that crystalline, epitaxial-like and highly ordered ZnO and Al:ZnO (AZO) quasisuperlattice thin films can be achieved from a precursor liquid at relatively low temperature via spin-coating, which crystallize with near epitaxy with a pronounced c-plane texture. We also show the visible and near-infra red (VIS-NIR) light spectroscopy of ZnO and Al:ZnO multi-layered thin film structures grown on oxidized silicon substrates. We show measurements demonstrating sub-band optical pumping of AZO QSLs that enable significant photoconductivity. In AZO QSLs, conduction band electrons from valence band pumping at incident irradiation > Eg, are not required to initiate or enhance photoconductivity, and PL data indicate a donor level that enable enhance sub-band photoconductivity even up to bias voltages of 200 V. Photoexcitation with a 532 nm source efficiently pumps the AZO conduction band without increasing the density of electron-holes in the valence band, minimizing field-driven recombination and enabling significant photoconductance over wide voltage ranges. Density functional theory analysis on ZnO systems with Al-doping configurations of ~2% indicate that interstitial doping is required to generate a density of states that corroborates the proposed donor level to enable the photoconductive properties seen in this work. References [1] K. Nomura, H. Ohta, A. Takagi, T. Kamiya, M. Hirano and H. Hosono, Nature 432, 488 (2004). [2] T. Kamiya, K. Nomura and H. Hosono, Sci. Tech. Adv. Mater. 11, 044305 (2010). [3] R. A. Street, Adv. Mater. 21, 2007 (2009). [4] H. Lingling, H. Dedong, C. Zhuofa, C. Yingying, W. Jing, Z. Nannan, D. Junchen, Z. Feilong, L. Lifeng, Z. Shengdong, Z. Xing and W. Yi, Jpn. J. Appl. Phys 54, 04DJ07 (2015). [5] C. Glynn and C. O'Dwyer, Adv. Mater. Interfaces 4, 1600610 (2017). [6] D. Buckley, D. McNulty, V. Z. Zubialevich, P. J. Parbrook and C. O'Dwyer, J. Vac. Sci. Technol. A, 35, 061517 (2017). [7] D. Buckley, D. McNulty, V. Z. Zubialevich, P. J. Parbrook and C. O'Dwyer, ECS Trans., 77, 99 (2017). [8] D. Buckley, R. McCormack and C. O'Dwyer, J. Phys. D: Appl. Phys., 50, 16TL01 (2017). [9] D. Buckley, R. McCormack, D. McNulty, V. Z. Zubialevich, P. J. Parbrook and C. O'Dwyer, ECS Trans., 77, 75 (2017).
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- 2020
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15. The importance of sulfur host structural preservation for lithium–sulfur battery performance
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Sigita Trabesinger, Victor Landgraf, and David McNulty
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Materials science ,Renewable Energy, Sustainability and the Environment ,chemistry.chemical_element ,Lithium–sulfur battery ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Electrochemistry ,01 natural sciences ,Sulfur ,Cathode ,0104 chemical sciences ,law.invention ,chemistry ,Chemical engineering ,law ,Electrode ,General Materials Science ,Lithium ,Cyclic voltammetry ,0210 nano-technology ,Carbon - Abstract
The identification of sulfur host materials, which can overcome issues associated with the insulating nature of sulfur and the shuttling of soluble lithium polysulfides, is crucial in order to realize the practical applications of lithium–sulfur (Li–S) batteries. Therefore, the development of conductive electrode architectures with novel, porous structures is essential to improve the electrochemical performance of Li–S cells. To this end, carbon inverse opals (IOs) were prepared using sacrificial polystyrene spheres, directly on a current-collecting substrate, and were infilled with sulfur via a solution infiltration method. The electrochemical performance of S-infilled carbon IOs (S-CIO), prepared with spheres of different diameters, is evaluated through cyclic voltammetry and galvanostatic cycling. We demonstrate that S-CIO provide long cycle life and stable specific charge, when tested as cathode materials for Li–S batteries. IO samples, prepared with smaller spheres (100 and 200 nm diameters), achieve significantly higher specific charge values than samples prepared with larger spheres. The electrochemical performance of our S-CIO is compared with conventional slurry electrodes containing CIO powder. Mechanical stress during slurry preparation, grinding or ball-milling of material, destroys the IO structure, resulting in worse electrochemical performance as compared to as deposited IO samples. Consequently, this report offers insight into the importance of retaining and optimizing the structure of conductive S-hosts for improving electrochemical performance of Li–S cells.
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- 2020
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16. Technology and the ‘New Governance’ Techniques of Financial Regulation
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David McNulty, Andrea Miglionico, and Alistair K. L. Milne
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History ,Polymers and Plastics ,Business and International Management ,Industrial and Manufacturing Engineering - Published
- 2022
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17. High aspect-ratio germanium-tin alloy nanowires: potential as highly efficient Li-Ion battery anodes
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Adrià Garcia‐Gil, Subhajit Biswas, David McNulty, Ahin Roy, Kevin M. Ryan, Valeria Nicolosi, and Justin D. Holmes
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Supercritical growth conditions ,Germanium-tin nanowires ,Chemical sciences ,nanowires ,Super-thin nanowires ,FOS: Chemical sciences ,Mechanics of Materials ,Mechanical Engineering ,Li-ion battery anodes ,electrochemical performance ,Li-ion battery anode ,energy storage devices ,34 Chemical sciences - Abstract
Here, the fabrication of a high aspect ratio (>440) Ge1−xSnx nanowires with super-thin (≈9 nm) diameter, much below the Bohr radius, using a simple solvothermal-like growth method under supercritical toluene conditions at a reaction temperature of 440 °C is reported. Ge1−xSnx nanowires are grown with varying amounts of Sn in Ge lattice, between 3.1 to 10.2 at%. The growth of the Ge1−xSnx alloy nanowires is achieved without any additional catalysts, and directly on current collector substrates (titanium) for application as Li-ion battery anodes. The electrochemical performance of the binder-free Ge1−xSnx nanowires as an anode material for Li-ion batteries is investigated via galvanostatic cycling and detailed analysis of differential capacity plots. The dimensions of the nanowires, and the amount of Sn in Ge, are critical to achieving a high specific capacity and capacity retention. Ge1−xSnx nanowires with the highest aspect ratios and with the lowest Sn content (3.1 at%) demonstrate exceptional capacity retention of ≈90% and 86% from the 10th to the 100th and 150th cycles respectively, while maintaining a very high specific capacity value of 1176 and 1127 mAh g−1 after the 100 and 150 cycles respectively.
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- 2022
18. Tech Highlights - Spring 2023
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Mara Schindelholz, David McNulty, Chao (Gilbert) Liu, Zenghe Liu, Chock Karuppaiah, and Donald Pile
- Subjects
Electrochemistry - Abstract
A collection of technology highlights pulled from recent papers published in ECS journals.
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- 2023
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19. One-Step Grown Carbonaceous Germanium Nanowires and Their Application as Highly Efficient Lithium-Ion Battery Anodes
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Adrià Garcia, Subhajit Biswas, David McNulty, Ahin Roy, Sreyan Raha, Sigita Trabesinger, Valeria Nicolosi, Achintya Singha, and Justin D. Holmes
- Subjects
Nanowire ,Germanium ,Supercritical fluid ,Materials Chemistry ,Electrochemistry ,Li-ion battery ,Energy Engineering and Power Technology ,Chemical Engineering (miscellaneous) ,Self-seeded growth ,Electrical and Electronic Engineering - Abstract
Developing a simple, cheap, and scalable synthetic method for the fabrication of functional nanomaterials is crucial. Carbon-based nanowire nanocomposites could play a key role in integrating group IV semiconducting nanomaterials as anodes into Li-ion batteries. Here, we report a very simple, one-pot solvothermal-like growth of carbonaceous germanium (C-Ge) nanowires in a supercritical solvent. C-Ge nanowires are grown just by heating (380–490 °C) a commercially sourced Ge precursor, diphenylgermane (DPG), in supercritical toluene, without any external catalysts or surfactants. The self-seeded nanowires are highly crystalline and very thin, with an average diameter between 11 and 19 nm. The amorphous carbonaceous layer coating on Ge nanowires is formed from the polymerization and condensation of light carbon compounds generated from the decomposition of DPG during the growth process. These carbonaceous Ge nanowires demonstrate impressive electrochemical performance as an anode material for Li-ion batteries with high specific charge values (>1200 mAh g–1 after 500 cycles), greater than most of the previously reported for other “binder-free” Ge nanowire anode materials, and exceptionally stable capacity retention. The high specific charge values and impressively stable capacity are due to the unique morphology and composition of the nanowires.
- Published
- 2021
20. Tech Highlights - Winter 2022
- Author
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Donald Pile, David McNulty, Zenghe Liu, Chao Liu, Chock Karuppaiah, and Joshua Gallaway
- Subjects
Electrochemistry - Abstract
A collection of technology highlights pulled from recent papers published in ECS journals.
- Published
- 2022
- Full Text
- View/download PDF
21. Tech Highlights - Summer 2022
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Joshua Galloway, Mara Schindelholz, David McNulty, Chock Karuppaiah, and Donald Pile
- Subjects
Electrochemistry - Abstract
A collection of technology highlights pulled from recent papers published in ECS journals.
- Published
- 2022
- Full Text
- View/download PDF
22. One-Step Fabrication of GeSn Branched Nanowires
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Clive Downing, Achintya Singha, David McNulty, Sreyan Raha, Justin D. Holmes, Colm O'Regan, Colm O'Dwyer, Jessica Doherty, and Subhajit Biswas
- Subjects
Materials science ,Fabrication ,Nanostructure ,Nanowires ,General Chemical Engineering ,Nanowire ,Nanotechnology ,One-Step ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Materials Chemistry ,Li-ion battery ,Branched nanostructure ,0210 nano-technology ,Germanium-tin - Abstract
We report for the first time the self-catalyzed, single-step growth of branched GeSn nanostructures by a vapor–liquid–solid mechanism. These typical GeSn nanostructures consist of ⟨111⟩-oriented, Sn-rich (∼8 atom %) GeSn “branches” grown epitaxially on GeSn “trunks”, with a Sn content of ∼4 atom %. The trunks were seeded from Au0.80Ag0.20 nanoparticles followed by the catalytic growth of secondary branches (diameter ∼ 50 nm) from the excess of Sn on the sidewalls of the trunks, as determined by high-resolution electron microscopy and energy-dispersive X-ray analysis. The nanowires, with ⟨111⟩-directed GeSn branches oriented at ∼70° to the trunks, have no apparent defects or change in crystal structure at the trunk–branch interface; structural quality is retained at the interface with epitaxial crystallographic relation. The electrochemical performance of these highly ordered GeSn nanostructures was explored as a potential anode material for Li-ion batteries, due to their high surface-to-volume ratio and increased charge carrier pathways. The unique structure of the branched nanowires led to high specific capacities comparable to, or greater than, those of conventional Ge nanowire anode materials and Ge1–xSnx nanocrystals.
- Published
- 2019
- Full Text
- View/download PDF
23. Tech Highlights - Fall 2022
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Joshua Galloway, Mara Schindelholz, David McNulty, Chock Karuppaiah, and Donald Pile
- Subjects
Electrochemistry - Abstract
A collection of technology highlights pulled from recent papers published in ECS journals.
- Published
- 2022
- Full Text
- View/download PDF
24. Directly grown germanium nanowires from stainless steel: high-performing anodes for Li-ion batteries
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David McNulty, Subhajit Biswas, Justin D. Holmes, Shane Garvey, and Colm O'Dwyer
- Subjects
Materials science ,Germanium ,business.industry ,Nanowire ,Energy Engineering and Power Technology ,chemistry.chemical_element ,Vapor−solid−solid ,7. Clean energy ,Stainless steel ,Catalysis ,Anode ,Ion ,chemistry ,Materials Chemistry ,Electrochemistry ,Li-ion battery ,Chemical Engineering (miscellaneous) ,Optoelectronics ,Electrical and Electronic Engineering ,Current (fluid) ,business - Abstract
Germanium (Ge) nanowires were fabricated directly on stainless steel current collectors for Li-ion batteries without any additional catalytic seeds. Substrates of stainless steel are unconventional materials for the direct growth of nanowires for battery applications. Stainless steel substrates were activated for nanowire growth by annealing them in air at a temperature of 450 °C to form a catalytic iron oxide surface layer. Large yields of Ge nanowires were obtained from oxidized stainless steel via a liquid injection chemical vapor deposition process, with diphenylgermane (DPG) as a Ge precursor. Fabricated Ge nanowires have uniform morphology and are single-crystalline. The capacity retention from a nanowire anode tested at 0.2 C is very stable, highlighted by reversible capacities of ∼1014 and 894 mAh/g after the 50th and 250th cycles, respectively. The large specific capacity values are one of the highest achieved for binder-free Ge nanomaterial-based anode materials. The high specific capacity values, good capacity retention, and voltage stability observed resulted from the excellent adhesion of the nanowires to the stainless steel current collectors, ensuring good electrical contact and electrical conductivity. Achieving such electrochemical performance from Ge nanowires grown via a significantly simplified direct growth process on a functional conductive substrate demonstrates the potential of directly grown Ge nanowires as a high-performing anode material for Li-ion batteries., {"references":["https://pubs.acs.org/doi/10.1021/acsaem.0c01977"]}
- Published
- 2021
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25. Feasibility study of hospital antimicrobial stewardship analytics using electronic health records
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Peter Dutey-Magni, Martin J Gill, David Mcnulty, Gurjit Sohal, Andrew Hayward, and Laura Shallcross
- Abstract
Background: Hospital antimicrobial stewardship (AMS) programmes are multidisciplinary initiatives to optimise the use of antimicrobials. Most hospitals depend on time-consuming manual audits to monitor clinicians’ prescribing. But much of the information needed could be sourced from electronic health records (EHRs).Objectives: To develop an informatics methodology to analyse characteristics of hospital AMS practice using routine electronic prescribing and laboratory records.Methods: Feasibility study using electronic prescribing, laboratory and clinical coding records from adult patients admitted to six specialties at Queen Elizabeth Hospital, Birmingham, UK (September 2017–August 2018). The study involved: (1) a review of antimicrobial stewardship standards of care; (2) their translation into concepts measurable from commonly available EHRs; (3) pilot application in an EHR cohort study (n=61,679 admissions).Results: We developed data modelling methods to characterise the use of antimicrobials (antimicrobial therapy episode linkage methods, therapy table, therapy changes). Prescriptions were linked into antimicrobial therapy episodes (mean 2.4 prescriptions/episode; mean length of therapy of 5.8 days) enabling production of several actionable findings. For example, 22% of therapy episodes for low-severity community acquired pneumonia were congruent with prescribing guidelines, with a tendency to use antibiotics with a broader spectrum. Analysis of therapy changes revealed a delay in switching from intravenous to oral therapy by an average 3.6 days [95% CI: 3.4; 3.7]. Performance of microbial cultures prior to treatment initiation occurred in just 22% of antibacterial prescriptions. The proposed methods enabled fine-grained monitoring of AMS practice all the way down to specialties, wards, and individual clinical teams by case mix, enabling more meaningful peer comparison. Conclusions: It is feasible to use hospital EHRs to construct rapid, meaningful measures of prescribing quality with potential to support quality improvement interventions (audit/feedback to prescribers), engagement with front-line clinicians on optimising prescribing, and AMS impact evaluation studies.
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- 2021
- Full Text
- View/download PDF
26. Feasibility study of hospital antimicrobial stewardship analytics using electronic health records
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Nadia Elsay, Gillian Forbes, Haydn Williams, Catherine M Smith, Patrick Rockenschaub, Rob Horne, Elizabeth Sutton, Andrew Hayward, Jennifer S. Mindell, John Robson, Anne Conolly, Lou Atkins, James Thomas, Ellen Fragaszy, Claire Royston, Patty Kostkova, Martin J. Gill, Rosanna Traina, Susan Michie, Carolyn Tarrant, Arnoupe Jhass, Peter Dutey-Magni, David McNulty, Emma Richardson, Laura Shallcross, Michelle Richardson, Niall C Anderson, Spiros Denaxas, Fabiana Lorencatto, Jonathan West, Christopher Fuller, Elise Crayton, and G Sohal
- Subjects
0301 basic medicine ,Microbiology (medical) ,030106 microbiology ,Immunology ,Psychological intervention ,Audit ,Microbiology ,03 medical and health sciences ,0302 clinical medicine ,Case mix index ,Electronic prescribing ,AcademicSubjects/MED00740 ,Immunology and Allergy ,Medicine ,Antimicrobial stewardship ,030212 general & internal medicine ,Medical prescription ,business.industry ,medicine.disease ,AcademicSubjects/MED00290 ,Infectious Diseases ,Informatics ,Original Article ,Medical emergency ,AcademicSubjects/MED00230 ,business ,Cohort study - Abstract
BackgroundHospital antimicrobial stewardship (AMS) programmes are multidisciplinary initiatives to optimize antimicrobial use. Most hospitals depend on time-consuming manual audits to monitor clinicians’ prescribing. But much of the information needed could be sourced from electronic health records (EHRs).ObjectivesTo develop an informatics methodology to analyse characteristics of hospital AMS practice using routine electronic prescribing and laboratory records.MethodsFeasibility study using electronic prescribing, laboratory and clinical coding records from adult patients admitted to six specialities at Queen Elizabeth Hospital, Birmingham, UK (September 2017–August 2018). The study involved: (i) a review of AMS standards of care; (ii) their translation into concepts measurable from commonly available EHRs; and (iii) a pilot application in an EHR cohort study (n = 61679 admissions).ResultsWe developed data modelling methods to characterize antimicrobial use (antimicrobial therapy episode linkage methods, therapy table, therapy changes). Prescriptions were linked into antimicrobial therapy episodes (mean 2.4 prescriptions/episode; mean length of therapy 5.8 days), enabling several actionable findings. For example, 22% of therapy episodes for low-severity community-acquired pneumonia were congruent with prescribing guidelines, with a tendency to use broader-spectrum antibiotics. Analysis of therapy changes revealed IV to oral therapy switching was delayed by an average 3.6 days (95% CI: 3.4–3.7). Microbial cultures were performed prior to treatment initiation in just 22% of antibacterial prescriptions. The proposed methods enabled fine-grained monitoring of AMS practice down to specialities, wards and individual clinical teams by case mix, enabling more meaningful peer comparison.ConclusionsIt is feasible to use hospital EHRs to construct rapid, meaningful measures of prescribing quality with potential to support quality improvement interventions (audit/feedback to prescribers), engagement with front-line clinicians on optimizing prescribing, and AMS impact evaluation studies.
- Published
- 2021
- Full Text
- View/download PDF
27. Bigger Fish to Fry: FinTech and the Digital Transformation of Financial Services
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David McNulty and Alistair Milne
- Subjects
Finance ,Competition (economics) ,Promotion (rank) ,business.industry ,restrict ,Corporate governance ,media_common.quotation_subject ,Digital transformation ,Systemic risk ,business ,Payment ,Financial services ,media_common - Abstract
FinTech has been promoted as an economic policy opportunity, for example, in the UK and in Singapore, with interventions made to support FinTech start-ups through favourable regulatory treatment. This has included the use of regulatory sandboxes, favourable tax treatment, and some limited financial support for start-up firms, alongside wider pro-competition policies in banking and payments. This chapter provides an economic analysis of these policies, arguing that they can lack coherence. Policies should focus on the broader and more significant challenge of digital transformation—using digital technology to address market and organisational failures across financial services—and addressing the governance challenges that restrict this digital transformation of finance. This requires measures, such as open banking, to eliminate barriers to competition. It further requires substantial regulatory engagement and dialogue with the industry on the development of the information and data infrastructures that will allow them to properly support customer needs, control prudential and systemic risk, and meet other key regulatory objectives. This argument is illustrated with reference to the UK, looking at both the promotion of FinTech as a policy goal and the ongoing digital transformation of UK insurance.
- Published
- 2021
- Full Text
- View/download PDF
28. O’Hanlon, Sally McNulty, David Tian, Ruiyuan Coleman, Jonathan O’Dwyer, Colm
- Author
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Sally O'Hanlon, Colm O'Dwyer, Ruiyuan Tian, Jonathan N. Coleman, and David McNulty
- Subjects
Battery (electricity) ,Raman scattering ,Conductivity ,Materials science ,Renewable Energy, Sustainability and the Environment ,020209 energy ,European Regional Development Fund ,02 engineering and technology ,Li battery ,Condensed Matter Physics ,Engineering physics ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Ion ,symbols.namesake ,0202 electrical engineering, electronic engineering, information engineering ,Materials Chemistry ,Electrochemistry ,symbols ,Electron microscopy ,Li-battery ,Charge and discharge - Abstract
Adding porosity to battery electrodes is sometimes useful for accommodating volumetric expansion, electrolyte access to active materials, or mitigating poor high-rate performance for thicker electrodes. Ordered macroporous electrode such as inverse opals, are a good model system: binder and conductive additive-free, interconnected electrically, have defined porosity consistent with thickness, good electrolyte wettability and surprisingly good behavior in half-cells and some Li-battery cells at normal rates. We show that at high charge and discharge rates, charge storage in macroporous electrode materials can be completely supressed, and then entirely recovered at low rates. Using a model system of inverse opal V2O5 in a flooded Li-battery three-electrode cell electrodes store almost no charge at rates >10 C, but capacity completely recovers when the rate is reduced to
- Published
- 2020
29. Development of risk prediction models to predict urine culture growth for adults with suspected urinary tract infection in the emergency department: protocol for an electronic health record study from a single UK university hospital
- Author
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Martin J. Gill, Orlagh Carroll, Nick Freemantle, Laura Shallcross, David McNulty, and Patrick Rockenschaub
- Subjects
medicine.medical_specialty ,Urinary system ,Urine ,Risk prediction models ,Prediction models ,01 natural sciences ,010104 statistics & probability ,03 medical and health sciences ,Hospital ,0302 clinical medicine ,Diagnosis ,Protocol ,Medicine ,030212 general & internal medicine ,0101 mathematics ,Protocol (science) ,lcsh:R5-920 ,Urinary tract infection ,business.industry ,Attendance ,Emergency department ,Culture growth ,Emergency medicine ,lcsh:Medicine (General) ,business ,Predictive modelling - Abstract
Background Urinary tract infection (UTI) is a leading cause of hospital admissions and is diagnosed based on urinary symptoms and microbiological cultures. Due to lags in the availability of culture results of up to 72 h, and the limitations of routine diagnostics, many patients with suspected UTI are started on antibiotic treatment unnecessarily. Predictive models based on routinely collected clinical information may help clinicians to rule out a diagnosis of bacterial UTI in low-risk patients shortly after hospital admission, providing additional evidence to guide antibiotic treatment decisions. Methods Using electronic hospital records from Queen Elizabeth Hospital Birmingham (QEHB) collected between 2011 and 2017, we aim to develop a series of models that estimate the probability of bacterial UTI at presentation in the emergency department (ED) among individuals with suspected UTI syndromes. Predictions will be made during ED attendance and at different time points after hospital admission to assess whether predictive performance may be improved over time as more information becomes available about patient status. All models will be externally validated for expected future performance using QEHB data from 2018/2019. Discussion Risk prediction models using electronic health records offer a new approach to improve antibiotic prescribing decisions, integrating clinical and demographic data with test results to stratify patients according to their probability of bacterial infection. Used in conjunction with expert opinion, they may help clinicians to identify patients that benefit the most from early antibiotic cessation.
- Published
- 2020
30. Towards Data-Driven Hospital Antimicrobial Stewardship: Secondary use of Routine Electronic Care and Prescribing Records to Inform Antimicrobial Stewardship Programmes
- Author
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Laura Shallcross, Gurjit Sohal, Martin J. Gill, Peter Dutey-Magni, Andrew Hayward, and David McNulty
- Subjects
Nursing ,Antimicrobial stewardship ,Business - Abstract
Background Hospital antimicrobial stewardship (AMS) programmes are multidisciplinary initiatives to optimise the use of antimicrobials. Most AMS programmes rely on time-consuming manual audits to monitor clinicians’ antibiotic prescribing practice. Much of the information needed is already contained within electronic health records (EHRs) and could be used to inform AMS programmes. The objective of this study was to evaluate the feasibility of building analytics from hospital EHRs to facilitate AMS interventions. Methods This study used electronic prescribing, laboratory and clinical coding records of adult patients admitted to six specialties at Queen Elizabeth Hospital, Birmingham, UK between September 2017 and August 2018 (n = 61,679 admissions). Duration of prescribing, compliance with clinical guidelines, and timing of switch from intravenous to oral antibiotics in relation to clinical progression were assessed. Outputs were visualised at ward, specialty and consultant levels. Results A total of 59,884 antibacterial prescription records were linked into 24,653 therapy episodes. Among the 35% of admissions prescribed an antibacterial, the mean days of therapy per admission was 4.3 days and 9.9 days in elective and emergency hospitalisations respectively. Twenty-two percent (207/997) of therapy episodes for low-severity community-acquired pneumonia were initiated with the antibiotic recommended by locally-approved prescribing guidelines. Data suggested average delays in switching from intravenous to oral therapy of up to 3.6 days [95% CI: 3.4; 3.7]. Microbial cultures were performed prior to treatment initiation in just 22% of antibacterial prescriptions. Conclusions Hospital EHRs can be used to construct meaningful measures of antibiotic stewardship, demonstrating potential value for audit and feedback interventions.
- Published
- 2020
- Full Text
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31. Diagnostic uncertainty and urinary tract infection in the emergency department: a cohort study from a UK hospital
- Author
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Andrew Hayward, Martin J. Gill, Laura Shallcross, Nick Freemantle, David McNulty, and Patrick Rockenschaub
- Subjects
Adult ,Male ,medicine.medical_specialty ,Microbiological culture ,medicine.drug_class ,Urinary system ,lcsh:Special situations and conditions ,Antibiotics ,Antimicrobial stewardship ,Antimicrobial resistance ,urologic and male genital diseases ,Diagnosis, Differential ,03 medical and health sciences ,0302 clinical medicine ,Antibiotic resistance ,Internal medicine ,medicine ,Humans ,Electronic health records ,030212 general & internal medicine ,Aged ,Retrospective Studies ,Urinary tract infection ,0303 health sciences ,Emergency department ,030306 microbiology ,business.industry ,lcsh:RC952-1245 ,lcsh:Medical emergencies. Critical care. Intensive care. First aid ,Uncertainty ,lcsh:RC86-88.9 ,Middle Aged ,bacterial infections and mycoses ,United Kingdom ,female genital diseases and pregnancy complications ,Anti-Bacterial Agents ,Hospitalization ,Urinary Tract Infections ,Emergency Medicine ,Female ,Observational study ,Emergency Service, Hospital ,business ,Research Article ,Cohort study - Abstract
Background Suspected urinary tract infection (UTI) syndromes are a common reason for empirical antibiotics to be prescribed in the Emergency Department (ED), but differentiating UTI from other conditions with a similar presentation is challenging. We investigated how often an ED diagnosis of UTI is confirmed clinically/microbiologically, and described conditions which present as UTI syndromes. Methods Observational study using electronic health records from patients who attended the ED with suspected UTI and had a urine sample submitted for culture. We compared the ED diagnosis to diagnosis at discharge from hospital (ICD-10 codes), and estimated the proportion of cases with clinical/microbiological evidence of UTI. Results Two hundred eighty nine patients had an ED diagnosis of UTI syndrome comprising: lower UTI (191), pyelonephritis (56) and urosepsis (42). In patients admitted to hospital with an ED diagnosis of lower UTI, pyelonephritis or urosepsis, clinical/microbiological evidence of UTI was lacking in 61/103, 33/54 and 31/42 cases respectively. The ED diagnosis was concordant with the main reason for admission in less than 40% of patients with UTI syndromes, and antibiotics were stopped within 72 h in 37/161 patients. Conclusions Clinical/microbiological evidence of UTI was lacking in 60–70% of patients, suggesting scope to revise empirical prescribing decisions for UTI syndromes in light of microbial culture and clinical progression.
- Published
- 2020
- Full Text
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32. Simplifying the synthesis of carbon inverse opals
- Author
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Sigita Trabesinger, Victor Landgraf, and David McNulty
- Subjects
chemistry.chemical_classification ,Thermogravimetric analysis ,Materials science ,General Chemical Engineering ,chemistry.chemical_element ,Infrared spectroscopy ,General Chemistry ,Polymer ,Toluene ,chemistry.chemical_compound ,symbols.namesake ,chemistry ,Chemical engineering ,symbols ,Polystyrene ,Dispersion (chemistry) ,Raman spectroscopy ,Carbon - Abstract
Carbon inverse opals (IOs) were prepared via a facile synthesis approach using a sucrose-based precursor and polystyrene (PS) spheres as a sacrificial template. During IO preparation, polymer spheres are typically removed by dispersion in organic solvents, such as toluene or tetrahydrofuran. In this study, carbon IOs are prepared with and without removal of PS spheres by toluene to determine the influence of template removal prior to high-temperature treatment on the morphology and chemistry of the resulting carbons. Properties of samples are compared through a systematic investigation by electron microscopy, Fourier-transform infrared spectroscopy and Raman spectroscopy. We demonstrate that a commonly used processing step—polymer sphere template chemical removal—does not make any significant difference to the IO morphology. A correlation of Raman spectroscopy with SEM imaging and TGA analysis indicates that carbon IOs prepared without the solvent-treatment step are more ordered than samples prepared with this processing step. The key finding of this report is the simplified IO synthesis procedure, which can be adapted to the preparation of IOs of other materials besides carbon.
- Published
- 2020
33. Development of risk prediction models to predict urine culture growth for patients with suspected urinary tract infection in the emergency department: protocol for an electronic health record study from a single UK hospital
- Author
-
Patrick Rockenschaub, Martin J Gill, David McNulty, Orlagh Carroll, Nick Freemantle, and Laura Shallcross
- Abstract
Background: Urinary tract infection (UTI) is a leading cause of hospital admissions and is diagnosed based on urinary symptoms and microbiological cultures. Due to lags in the availability of culture results of up to 72 hours, and the limitations of routine diagnostics, many patients with suspected UTI are started on antibiotic treatment unnecessarily. Predictive models based on routinely collected clinical information may help clinicians to rule out a diagnosis of bacterial UTI in low-risk patients shortly after hospital admission, providing additional evidence to guide antibiotic treatment decisions.Methods: Using electronic hospital records from Queen Elizabeth Hospital Birmingham (QEHB) collected between 2011 and 2017, we aim to develop a series of models that estimates the probability of bacterial UTI at presentation in the emergency department (ED) among individuals with suspected urinary tract infection syndromes. Predictions will be made during ED attendance and at different time points after hospital admission to assess whether predictive performance may be improved over time as more information becomes available about patient status. All models will be externally validated for expected future performance using QEHB data from 2018/19.Discussion: Risk prediction models using electronic health records offer a new approach to improve antibiotic prescribing decisions, integrating clinical and demographic data with test results to stratify patients according to their probability of bacterial infection. Used in conjunction with expert opinion, they may help clinicians to identify patients that benefit the most from early antibiotic cessation.
- Published
- 2020
- Full Text
- View/download PDF
34. Early renal function trajectories, cytomegalovirus serostatus and long-term graft outcomes in kidney transplant recipients
- Author
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Richard Borrows, Charles J. Ferro, Adnan Sharif, Jonathan P Law, and David McNulty
- Subjects
Nephrology ,Adult ,Male ,medicine.medical_specialty ,Time Factors ,Population ,030232 urology & nephrology ,Cytomegalovirus ,030230 surgery ,lcsh:RC870-923 ,Antibodies, Viral ,Bayesian ,03 medical and health sciences ,0302 clinical medicine ,Postoperative Complications ,Cytomegalovirus serostatus ,Internal medicine ,medicine ,Humans ,Estimated glomerular filtration rate ,education ,Kidney transplantation ,education.field_of_study ,business.industry ,Hazard ratio ,Odds ratio ,Middle Aged ,lcsh:Diseases of the genitourinary system. Urology ,medicine.disease ,Kidney Transplantation ,Confidence interval ,Allograft function ,Transplantation ,Treatment Outcome ,Cytomegalovirus Infections ,Female ,business ,Serostatus ,Research Article - Abstract
Background Improved recognition of factors influencing graft survival has led to better short-term kidney transplant outcomes. However, efforts to prevent long-term graft decline and improve graft survival have seen more modest improvements. The adoption of electronic health records has enabled better recording and identification of donor-recipient factors through the use of modern statistical techniques. We have previously shown in a prevalent renal transplant population that episodes of rapid deterioration are associated with graft loss. Methods Estimated glomerular filtration rates (eGFR) between 3 and 27 months after transplantation were collected from 310 kidney transplant recipients. We utilised a Bayesian approach to estimate the most likely eGFR trajectory as a smooth curve from an average of 10,000 Monte Carlo samples. The probability of having an episode of rapid deterioration (decline greater than 5 ml/min/1.73 m2 per year in any 1-month period) was calculated. Graft loss and mortality data was collected over a median follow-up period of 8 years. Factors associated with having an episode of rapid deterioration and associations with long-term graft loss were explored. Results In multivariable Cox Proportional Hazard analysis, a probability greater than 0.8 of rapid deterioration was associated with long-term death-censored graft loss (Hazard ratio 2.17; 95% Confidence intervals [CI] 1.04–4.55). In separate multivariable logistic regression models, cytomegalovirus (CMV) serostatus donor positive to recipient positive (Odds ratio [OR] 3.82; 95%CI 1.63–8.97), CMV donor positive (OR 2.06; 95%CI 1.15–3.68), and CMV recipient positive (OR 2.03; 95%CI 1.14–3.60) were associated with having a greater than 0.8 probability of an episode of rapid deterioration. Conclusions Early episodes of rapid deterioration are associated with long-term death-censored graft loss and are associated with cytomegalovirus seropositivity. Further study is required to better manage these potentially modifiable risks factors and improve long-term graft survival.
- Published
- 2020
35. Ethnicity and Risk of Death in Patients Hospitalised for COVID-19 Infection: An Observational Cohort Study in an Urban Catchment Area
- Author
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Katharine Reeves, Krishnarajah Nirantharakumar, Adiva Liaqat, Peter Nightingale, Hannah Crothers, Paul Cockwell, Felicity Evison, A. Kolesnyk, Lylah Irshad, Elizabeth Sapey, Alastair K Denniston, David McNulty, Maxim Harris, Christopher Mainey, Mohammed Tabish Ahmed, Dominco Pagano, Theodore Nabavi, Suzy Gallier, and Simon Ball
- Subjects
Social deprivation ,business.industry ,Proportional hazards model ,Intensive care ,Hazard ratio ,Pandemic ,Ethnic group ,Medicine ,Retrospective cohort study ,business ,Cohort study ,Demography - Abstract
Background: Studies during the COVID-19 pandemic have suggested patient characteristics with increased risk of death. Most studies have not included populations which reflect an urban UK demographic but emerging case reports have suggested poorer outcomes in certain ethnic groups. It was hypothesised that people from South Asian ethnic groups would be more susceptible to severe manifestations of COVID-19. Methods: Patients with confirmed SARS-CoV-2 infection by positive polymerase chain reaction testing and requiring admission to University Hospitals Birmingham NHS Foundation Trust in Birmingham UK between 10th March 2020 and 17th April 2020 were included. Demographics, ethnicity, baseline co-morbidities, social deprivation index and outcome (death within the censor date) were assessed and Cox regression analysis conducted. Using observed sex-specific age distributions of COVID-19 admissions/deaths and 2011 census data for Birmingham/Solihull, expected numbers of admissions and deaths were estimated and ratios of observed to expected numbers calculated, providing standardised admission ratios (SAR) and standardised mortality ratios (SMR). Results: 2217 patients admitted to UHB with a proven diagnosis of COVID-19 were included. 58.2% were male, 69.5% White and the majority (80.2%) had co-morbidities. 18.5% were of South Asian ethnicity, and these patients were more likely to be younger (median age 61 vs.77), have no co-morbidities (27.8% vs. 16.6%) but a higher prevalence of diabetes mellitus (48.1% vs 28.2%) than White patients. SAR and SMR suggested more admissions and deaths in South Asian patients than would be predicted. These patients were more likely to present with severe disease. South Asian ethnicity was associated with an increased risk of death (Hazard Ratio 1.67 (95%CI 1.34 – 2.10)) after adjusting for age, sex, deprivation and comorbidities. Interpretation: Current evidence suggests those of South Asian ethnicity may be at risk of worse COVID019 outcomes, further studies needs to establish the underlying mechanistic pathways. Funding Statement: HDRUK Hub PIONEER Declaration of Interests: S Gallier, C Mainey, P Nightingale, D McNulty, A Kolesnyk, M Ahmed, H Crothers, F Evison, A Liaqat, L Irshad, M. Harris, T Nabavi, P Cockwell, D Pagano, report no conflicts of interest. S Ballreports funding support from the HDFR-UK, K Reeves reports funding support from the NIHR, E Sapey reports funding support from the MRC, Wellcome Trust, NIHR and British Lung Foundation. K. Nirantharakumar reports funding from MRC, Wellcome Trust, NIHR, Vifor and AstraZeneca. A.K Dennistonreports funding from HDR-UK, Wellcome Trust and Fight for Sight. Ethics Approval Statement: This retrospective cohort study, using prospectively collected data was conducted as part of DECOVID, an HRA and London - City & East Research Ethics Committee approved research database (Ethics number 20/HRA/1689).
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- 2020
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36. Germanium tin alloy nanowires as anode materials for high performance Li-Ion batteries
- Author
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Michele Conroy, Jessica Doherty, David McNulty, Ursel Bangert, Kalani Moore, Justin D. Holmes, Colm O'Dwyer, Subhajit Biswas, and SFI
- Subjects
GeSn alloy ,Materials science ,Alloy ,GeSn allow ,Nanowire ,chemistry.chemical_element ,Bioengineering ,Germanium ,02 engineering and technology ,Substrate (electronics) ,engineering.material ,010402 general chemistry ,Electrochemistry ,7. Clean energy ,01 natural sciences ,Li-ion battery ,General Materials Science ,Electrical and Electronic Engineering ,Mechanical Engineering ,General Chemistry ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Anode ,chemistry ,Chemical engineering ,Mechanics of Materials ,nanowire ,Electrode ,engineering ,0210 nano-technology ,Tin - Abstract
The combination of two active Li-ion materials (Ge and Sn) can result in improved conduction paths and higher capacity retention. Here we report; for the first time; the implementation of Ge1-xSnx alloy nanowires as anode materials for Li-ion batteries. Ge1-xSnx alloy nanowires have been successfully grown via vapor-liquid-solid (VLS) technique directly on stainless steel current collectors. Ge1-xSnx (x = 0.048) nanowires were predominantly seeded from the Au0.80Ag0.20 catalysts with negligible amount of growth was also directly catalysed from stainless steel substrate. The electrochemical performance of the the Ge1-xSnx nanowires as an anode material for Li-ion batteries was investigated via galvanostatic cycling and detailed analysis of differential capacity plots. The nanowire electrodes demonstrated an exceptional capacity retention of 93.4 % from the 2nd to the 100th charge at a C/5 rate, while maintaining a specific capacity value of ~921 mAh/g after 100 cycles. Voltage profiles and differential capacity plots revealed that the Ge1-xSnx nanowires behave as an alloying mode anode material, as reduction/oxidation peaks for both Ge and Sn were observed, however it is clear that the reversible lithiation of Ge is responsible for the majority of the charge stored.
- Published
- 2020
37. Cobalt Phosphate-Based Supercapattery as Alternative Power Source for Implantable Medical Devices
- Author
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David McNulty, Colm O'Dwyer, N. Padmanathan, Han Shao, and Kafil M. Razeeb
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Materials science ,Energy Engineering and Power Technology ,02 engineering and technology ,010402 general chemistry ,Electrochemistry ,01 natural sciences ,7. Clean energy ,Energy storage ,Nanomaterials ,chemistry.chemical_compound ,Hardware_GENERAL ,Materials Chemistry ,Chemical Engineering (miscellaneous) ,Electrical and Electronic Engineering ,Power density ,Supercapacitor ,Ideal (set theory) ,business.industry ,Electrochemical ,Nanomaterial ,021001 nanoscience & nanotechnology ,Supercapattery ,0104 chemical sciences ,Power (physics) ,Cobalt phosphate ,chemistry ,Optoelectronics ,0210 nano-technology ,business ,Energy storage device - Abstract
The supercapattery is an ideal energy storage device that combines excellent power density and rate capability of supercapacitors and the greater energy density of batteries. With superior storage capacity and long life, this device can be employed in next-generation artificial cardiac pacemakers as a rechargeable energy source for the lifetime of the pacemaker (at least 15-20 years). However, current hybrid energy storage devices are often limited by less than ideal performance of either the supercapacitor or battery. Here, we develop a low cost and scalable prototype supercapattery with cobalt phosphate as positive and activated carbon as negative electrodes. This positive electrode exhibits a maximum specific capacity of 215.6 mAh g-1 (≈1990 F g-1), ever reported in a metal phosphate based electrode. The supercapattery delivers a high energy density of 3.53 mWh cm-3 (43.2 Wh kg-1) and a power density of 425 mW cm-3 (5.8 kW kg-1). Furthermore, the device can retain 79% voltage even after 4 minutes self-discharge, enough to provide power during cardiac emergencies. This hybrid device provide excellent performance and stability under physiological temperature range (35-41 °C), retaining 68% of specific capacity after 100,000 cycles at room temperature (25 °C) and up to 81.5% after 20,000 cycles at 38 °C, demonstrating its effectiveness as a potential power source for the next-generation implanted medical devices.
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- 2018
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38. Polysulfide Binding to Several Nanoscale Magnéli Phases Synthesized in Carbon for Long-Life Lithium-Sulfur Battery Cathodes
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Usman Zubair, David McNulty, Carlotta Francia, Julia Ginette Nicole Amici, Colm O'Dwyer, and Silvia Bodoardo
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Materials science ,General Chemical Engineering ,Oxide ,chemistry.chemical_element ,Lithium–sulfur battery ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,7. Clean energy ,Sulfur ,0104 chemical sciences ,chemistry.chemical_compound ,General Energy ,chemistry ,Chemical engineering ,Environmental Chemistry ,General Materials Science ,Lithium ,0210 nano-technology ,Tin ,Carbon ,Polysulfide ,Faraday efficiency - Abstract
In Li-S batteries, it is important to ensure efficient reversible conversion of sulfur to lithium polysulfide (LiPS). Shuttling effects caused by LiPS dissolution can lead to reduced performance and cycle life. Although carbon materials rely on physical trapping of polysulfides, polar oxide surfaces can chemically bind LiPS to improve the stability of sulfur cathodes. We show a simple synthetic method that allows high sulfur loading into mesoporous carbon preloaded with spatially localized nanoparticles of several Magneli-phase titanium oxide (Tin O2n-1 ). This material simultaneously suppresses polysulfide shuttling phenomena by chemically binding Li polysulfides onto several Magneli-phase surfaces in a single cathode and ensures physical confinement of sulfur and LiPS. The synergy between chemical immobilization of significant quantities of LiPS at the surface of several Tin O2n-1 phases and physical entrapment results in coulombically efficient high-rate cathodes with long cycle life and high capacity. These cathodes function efficiently at low electrolyte-to-sulfur ratios to provide high gravimetric and volumetric capacities in comparison with their highly porous carbon counterparts. Assembled coin cells have an initial discharge capacity of 1100 mAh g-1 at 0.1C and maintain a reversible capacity of 520 mAh g-1 at 0.2C for more than 500 cycles. Even at 1C, the cell loses only 0.06 % per cycle for 1000 cycles with a coulombic efficiency close to 99 %.
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- 2018
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39. A non enzymatic glutamate sensor based on nickel oxide nanoparticle
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David McNulty, Han Shao, Sumon Chakrabarty, Hidemitsu Furukawa, Mamun Jamal, Mohammad A. Yousuf, Kafil M. Razeeb, and Ajit Khosla
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Detection limit ,Materials science ,Nickel oxide ,010401 analytical chemistry ,Non-blocking I/O ,Glutamate receptor ,Nanoparticle ,Nanotechnology ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Ascorbic acid ,01 natural sciences ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,Non enzymatic ,Hardware and Architecture ,Electrode ,Electrical and Electronic Engineering ,0210 nano-technology ,Nuclear chemistry - Abstract
This work reports an enzyme-less glutamate sensor based on nickel oxide modified glassy carbon electrode. The nanoparticles of NiO were synthesized by sol–gel method, and showed high electro-catalytic activity towards glutamate oxidation in 0.1 M NaOH solution. The sensor displays a fast response time of
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- 2018
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40. NiVO3 fused oxide nanoparticles – an electrochemically stable intercalation anode material for lithium ion batteries
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David McNulty, Gillian Collins, and Colm O'Dwyer
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Battery (electricity) ,Materials science ,Intercalation (chemistry) ,Oxide ,chemistry.chemical_element ,Nanoparticle ,02 engineering and technology ,010402 general chemistry ,Electrochemistry ,7. Clean energy ,01 natural sciences ,Vanadium oxide ,chemistry.chemical_compound ,Intercalation ,General Materials Science ,NiVO3 ,Renewable Energy, Sustainability and the Environment ,General Chemistry ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Anode ,Chemical engineering ,chemistry ,Lithium ,Reversible lithiation efficiency ,0210 nano-technology - Abstract
For oxides, especially as lithium-ion battery anodes, it is important to engineer the material not only to improve the kinetics of reversible lithiation efficiency, but to avoid capacity and voltage fading, and side reactions from conversion mode processes that can sometimes occur in tandem with intercalation. We report the first electrochemical evaluation of NiVO3 as an intercalation anode material for Li-ion batteries, which offers a high capacity with negligible fading without conversion mode side reactions. Binary metal oxide NiVO3 fused oxide nanoparticles (Ni–FONPs) are formed via thermal reduction of Ni-doped vanadium oxide nanotubes (Ni-VONTs). The electrochemical performance of Ni–FONPs is contrasted with that of a composite of Fe2O3 and V2O3 (Fe–FONPs) with a similar morphology, synthesized using a similar process from Fe-doped VONTs. Galvanostatic cycling reveals that the binary metal oxide Ni–FONPs exhibit superior electrochemical performance compared to the Fe–FONPs by avoiding segregation into two oxides, one of which ordinarily cycles as a conversion mode material. The new anode material, Ni–FONPs, demonstrates state-of-the-art specific capacity retention (78% from the 2nd to the 500th cycle) and significantly long cycle life (500 cycles) when cycled using a specific current of 200 mA g−1 in a conductive additive and binder-free formulation. Limiting the lower voltage to ∼0.2 V avoids separate oxides of Ni and V, which independently, are detrimental to cycle life and capacity retention. Systematic analysis of differential capacity obtained from galvanostatic voltage profiles over 500 cycles offers a detailed insight into the charge storage mechanism and electrochemical behaviour of this stable NiVO3 anode material.
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- 2018
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41. High capacity binder-free nanocrystalline GeO2 inverse opal anodes for Li-ion batteries with long cycle life and stable cell voltage
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Darragh Buckley, Colm O'Dwyer, Hugh Geaney, and David McNulty
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Nanostructure ,Materials science ,Li-ion ,Inverse ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Ion ,Nanomaterials ,General Materials Science ,Electrical and Electronic Engineering ,Renewable Energy, Sustainability and the Environment ,business.industry ,Semiconductor ,021001 nanoscience & nanotechnology ,Nanocrystalline material ,0104 chemical sciences ,Anode ,Chemical engineering ,GeO2 ,Inverse opal ,0210 nano-technology ,business ,Voltage - Abstract
We demonstrate that crystalline macroporous GeO2 inverse opals exhibit state-of-the-art capacity retention, voltage stability and a very long cycle life when tested as anode materials for Li-ion batteries. The specific capacities and capacity retention obtained from GeO2 IOs are greater than values reported for other GeO2 nanostructures and comparable to pure Ge nanostructures. Unlike pure Ge nanostructures, GeO2 IOs can be prepared in air without complex processing procedures, potentially making them far more attractive from an industrial point of view, in terms of cost and ease of production. Inverse opals are structurally and electrically interconnected, and remove the need for additives and binders. GeO2 IOs show gradual capacity fading over 250 and 1000 cycles, when cycled at specific currents of 150 and 300 mA/g, respectively, while maintaining high capacities and a stable overall cell voltage. The specific capacities after the 500th and 1000th cycles at a specific current of 300 mA/g were ~ 632 and 521 mA h/g respectively, corresponding to a capacity retention in each case of ~ 76% and 63% from the 2nd cycle. Systematic analysis of differential capacity plots obtained from galvanostatic voltage profiles over 1000 cycles offers a detailed insight into the mechanism of charge storage in GeO2 anodes over their long cycle life. Rate capability testing and asymmetric galvanostatic testing demonstrate the ability of GeO2 IO samples to deliver significantly high capacities even at high specific currents (1 A/g).
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- 2018
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42. Reduced graphene oxide/VSB-5 composite micro/nanorod electrode for high energy density supercapattery
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P. Mohanapriya, David McNulty, M.K. Raihana, S. Esakki Muthu, Jhelai Sahadevan, N. Padmanathan, and V. Eswaramoorthi
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Materials science ,Graphene ,General Chemical Engineering ,Oxide ,Electrolyte ,Microporous material ,Electrochemistry ,Cathode ,law.invention ,chemistry.chemical_compound ,Chemical engineering ,chemistry ,law ,Electrode ,Nanorod - Abstract
Nickel Phosphate (Ni20[(OH)12(H2O)6][(HPO4)8(PO4)4]•12H2O) – VSB-5 nano/micro rods composite with reduced graphene oxide (rGO) was successfully synthesized using a Polyvinyl Pyrrolidone (PVP) aided hydrothermal technique and applied as a battery-type cathode for supercapatteries. The uniform meso/microporous structure provides more electro-active sites for surface redox reaction and nano-paths for electrolyte ion diffusion which can significantly improve the device performance. From the electrochemical analysis, it was found that VSB-5/rGO exhibited a specific capacity of 117.3 mAh g−1 (1056.1 F g−1) which was noticeably higher than the pristine VSB-5 (60.7 mAh g−1) at 5 mA cm−2. These excellent electrochemical performances may be due to rGO modification and well-defined nano/micro rods. Furthermore, supercapatteries were fabricated by pairing a commercially available activated carbon (AC) electrode with VSB-5/rGO as a positrode. The fabricated cell was tested and showed a high specific capacity of 86.8 mAh g−1 (208.4 F g−1) with 88% capacity retention after 5000 cycles. Finally, the assembled supercapattery delivered a maximum specific energy of 80.5 Wh kg−1 at a power output of 2216.5 W kg−1. In comparison with a pristine VSB-5 based device, the AC/VSB-5/rGO device shows remarkable electrochemical performance, demonstrating that VSB-5/rGO is a promising, new electrode material for high performance supercapatteries.
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- 2021
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43. V2 O3 Polycrystalline Nanorod Cathode Materials for Li-Ion Batteries with Long Cycle Life and High Capacity Retention
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David McNulty, Colm O'Dwyer, and D. Noel Buckley
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Lithium-ion batteries ,Energy storage ,Materials science ,Cathode materials ,Oxide ,Li-ion batteries ,Vanadium ,chemistry.chemical_element ,Nanocrystal ,02 engineering and technology ,Thermal treatment ,010402 general chemistry ,Electrochemistry ,01 natural sciences ,Li metal ,Catalysis ,law.invention ,V203 ,chemistry.chemical_compound ,law ,Polycrystalline nanorods ,021001 nanoscience & nanotechnology ,Cathode ,0104 chemical sciences ,Anode ,chemistry ,Chemical engineering ,Nanorods ,Nanorod ,Crystallite ,0210 nano-technology - Abstract
We report on the electrochemical performance of V2O3 polycrystalline nanorods (poly-NRs) as a cathode material for Li-ion batteries. Poly-NRs are formed through the thermal treatment of V2O5 nanotubes in a N2 atmosphere. X-ray and electron diffraction techniques are used to confirm the thermal reduction. Through galvanostatic cycling, we demonstrate that poly-NRs offer excellent capacity retention over 750 cycles. The capacity retention from the 50th to the 750th cycle was an impressive 94 %, retaining a capacity of approximately 120 mAh g−1 after 750 cycles. The outstanding stability of the nanocrystal-containing V2O3 poly-NRs over many cycles demonstrates that vanadium(III) oxide (V2O3) performs very well as a cathode material. Full Li-ion cells with paired a V2O3 poly-NR cathode and a pre-charged Co3O4 inverse opal (IO) conversion mode anode demonstrated high initial capacities and retained a capacity of 153 mAh g−1 after 50 cycles. The capacities achieved with our V2O3 poly-NRs/Co3O4 IO full cells are comparable to the capacities obtained from the most commonly used cathode materials when cycled in a half-cell arrangement versus pure Li metal.
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- 2017
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44. Highly-Ordered Growth of Solution-Processable ZnO for Thin Film Transistors
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Vitaly Z. Zubialevich, Colm O'Dwyer, David McNulty, Darragh Buckley, and Peter J. Parbrook
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Morphology ,Morphology (linguistics) ,Materials science ,X ray diffraction ,Thin films ,Crystalline materials ,chemistry.chemical_element ,Zinc ,Super-lattice structures ,Atomic force microscopy ,Effect of temperature ,Surface roughness ,Coatings ,Zinc oxide ,Annealing condition ,Thin film ,Metallic films ,Photoluminescence spectroscopy ,business.industry ,Temperature ,Electrical engineering ,Thin film circuits ,Preferential orientation ,X-ray photoelectrons ,chemistry ,Thin-film transistor ,Solution processable ,X-ray crystallography ,Thickness variation ,Film growth ,Optoelectronics ,Transmission electron ,Surface defects ,business - Abstract
Zinc oxide is an important optoelectronic material, of particular interest due to its wide band gap (Eg ~ 3.3 eV at 300 K), large exciton binding energy (~66 meV) and especially for the variety of methods by which it can be processed. Moreover, ZnO is readily able to alloy with other metals in the oxide form and has a lattice that can facilitate interstitial doping. This gives ZnO a key role in the area of optoelectronics, metal oxide thin films and thin film transistor (TFT) technologies. We demonstrate that crystalline, epitaxial-like and highly ordered ZnO thin films can be achieved from a precursor liquid at relatively low temperature via spin-coating. The synthesised films are smooth, stoichiometric ZnO with controllable thickness. An iterative layer-by-layer coating schematic is employed to demonstrate the effects of film thickness on structure, morphology as well as the surface and internal defects. Characterisation of the crystallinity, morphology, O-vacancy formation, stoichiometry, surface roughness and thickness variation was determined through X-ray diffraction, scanning and transmission electron and atomic force microscopy, X-ray photoelectron and photoluminescence spectroscopy, and the data of multi-layered ZnO correlated to defect formation and electrical conductivity. It is imperative that high crystal quality epitaxial-like thin films can be formed from solution processing to compete with physical deposition methods. We demonstrate that iterative spin-coating of deposited ZnO films results in a transition in crystal texture with increasing thickness (number of layers) from the [] m-plane to the [] c-plane. The films attain a c-axis preferential orientation, with no other crystalline peaks present. Results show that the film’s surface morphology was very smooth, with average rms roughness
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- 2017
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45. The Influence of Colloidal Opal Template and Substrate Type on 3D Macroporous Single and Binary Vanadium Oxide Inverse Opal Electrodeposition
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Sally O'Hanlon, David McNulty, and Colm O'Dwyer
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Materials science ,Binary number ,Inverse ,Mineralogy ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Vanadium oxide ,Colloid ,Electrodeposition ,Materials Chemistry ,Electrochemistry ,Porosity ,Technology innovation ,Metal oxide ,Renewable Energy, Sustainability and the Environment ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Porous ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Substrate type ,Chemical engineering ,Inverse opal ,0210 nano-technology - Abstract
We report on the electrodeposition of 3D macroporous vanadium oxide inverse opals and binary inverse opals on transparent conducting oxide substrates and stainless steel and thermally oxidized stainless steel substrates. The electrodeposition follows a diffusion limited growth mode to form 3D porous crystalline V2O5 after removal of a colloid photonic crystal template of self-assembled polystyrene spheres. Inverse opals were grown using spheres ranging in diameter from 0.5 μm to 6 μm, and binary inverse opals were also electrodeposited using binary mixtures of sphere sizes. We demonstrate that the ionic diffusion that leads to growth has charge-to-mass Coulombic efficiency ranging from 60–90%, depending on the voltage used. Additionally, the tortuosity in ionic diffusion through the opal to the substrate is significantly increased when large sphere diameter templates and binary opal templates are used. Analysis of the contribution of true substrate active area and the influence of template structure on ionic diffusivity confirms that inverse opal growth is dictated by the size of opal spheres, interstitial void clogging by smaller spheres in binary opals, and the conductivity of the substrate active area. The crystallinity of the inverse opal is consistent and a function of applied voltage, and attains phase pure orthorhombic V2O5.
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- 2017
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46. Comparing nanoparticles for drug delivery: The effect of physiological dispersion media on nanoparticle properties
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Aisling M. Ross, Andreas M. Grabrucker, John J.E. Mulvihill, Ciara I. Leahy, David McNulty, Paul Murray, Tadhg Kennedy, and Darragh R. Walsh
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Modern medicine ,Materials science ,Silver ,Hydrodynamic size ,Nanoparticle ,Bioengineering ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Ferric Compounds ,Silver nanoparticle ,Biomaterials ,Metal nanomaterials ,Zeta potential ,Humans ,Particle Size ,Titanium ,Drug Carriers ,Material type ,Water ,021001 nanoscience & nanotechnology ,Biomedical applications ,0104 chemical sciences ,Culture Media ,Nanomedicine ,Mechanics of Materials ,Drug delivery ,Nanoparticles ,Gold ,Zinc Oxide ,0210 nano-technology ,Dispersion (chemistry) - Abstract
peer-reviewed The full text of this article will not be available in ULIR until the embargo expires on the 23/04/2022 Delivering therapeutics to disease sites is a challenge facing modern medicine. Nanoparticle delivery systems are of considerable interest to overcome this challenge, but these systems suffer from poor clinical translation. It is believed this is, in part, due to incomplete understanding of nanoparticle physico-chemical properties in vivo. To understand how nanoparticle properties could change following intravenous delivery, Au, Ag, Fe2O3, TiO2, and ZnO nanoparticles of 5, 20, and 50 nm were characterised in water and physiological fluids. The effects of the dispersion medium, concentration, and incubation time on size, dispersion, and zeta potential were measured. Properties varied significantly depending on material type, size, and concentration over 24 h. Gold and silver nanoparticles were generally the most stable. Meanwhile, 20 nm nanoparticles appeared to be the least stable size, across materials. These results could have important implications for selecting nanoparticles for drug delivery that will elicit the desired physiological response. ACCEPTED peer-reviewed
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- 2019
47. Semiconducting Metal Oxide Photonic Crystal Plasmonic Photocatalysts
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Changyu Hu, Darragh Buckley, Alex Lonergan, Colm Glynn, Gillian Collins, David McNulty, and Colm O'Dwyer
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Materials science ,Oxide ,FOS: Physical sciences ,Physics::Optics ,Nanotechnology ,Applied Physics (physics.app-ph) ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Metal ,chemistry.chemical_compound ,Condensed Matter::Materials Science ,Photonic crystal ,Photocatalysis ,Physics::Chemical Physics ,Plasmonic nanoparticles ,Plasmon ,Mechanical Engineering ,Physics - Applied Physics ,Nitrophenol reduction ,021001 nanoscience & nanotechnology ,3. Good health ,0104 chemical sciences ,chemistry ,13. Climate action ,Mechanics of Materials ,Research council ,visual_art ,visual_art.visual_art_medium ,Catalyst ,0210 nano-technology - Abstract
Plasmonic photocatalysis has facilitated rapid progress in enhancing photocatalytic efficiency under visible light irradiation. Poor visible-light-responsive photocatalytic materials and low photocatalytic efficiency remain major challenges. Plasmonic metal-semiconductor heterostructures where both the metal and semiconductor are photosensitive are promising for light harvesting catalysis, as both components can absorb solar light. Efficiency of photon capture can be further improved by structuring the catalyst as a photonic crystal. Here we report the synthesis of photonic crystal plasmonic photocatalyst materials using Au nanoparticle-functionalized inverse opal (IO) photonic crystals. A catalyst prepared using a visible light responsive semiconductor (V2O5) displayed over an order of magnitude increase in reaction rate under green light excitation ($\lambda$=532 nm) compared to no illumination. The superior performance of Au-V2O5 IO was attributed to spectral overlap of the electronic band gap, localized surface plasmon resonance and incident light source. Comparing the photocatalytic performance of Au-V2O5 IO with a conventional Au-TiO2 IO catalyst, where the semiconductor band gap is in the UV, revealed that optimal photocatalytic activity is observed under different illumination conditions depending on the nature of the semiconductor. For the Au-TiO2 catalyst, despite coupling of the LSPR and excitation source at $\lambda$=532 nm, this was not as effective in enhancing photocatalytic activity compared to carrying out the reaction under broadband visible light, which is attributed to improved photon adsorption in the visible by the presence of a photonic band gap, and exploiting slow light in the photonic crystal to enhance photon absorption to create this synergistic type of photocatalyst., Comment: 19 pages, 8 figures, + Supporting information
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- 2019
48. Identifying cardiac surgery operations in hospital episode statistics administrative database, with an OPCS-based classification of procedures, validated against clinical data
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Giacomo, Bortolussi, David, McNulty, Hina, Waheed, Jamie A, Mawhinney, Nick, Freemantle, and Domenico, Pagano
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Adult ,Male ,Time Factors ,Adolescent ,Risk Assessment ,risk management ,quality in health care ,Young Adult ,Humans ,Cardiac Surgical Procedures ,Coronary Artery Bypass ,Aged ,Aged, 80 and over ,Heart Valve Prosthesis Implantation ,Models, Statistical ,Research ,clinical audit ,Reproducibility of Results ,Middle Aged ,Prognosis ,England ,cardiovascular system ,Hospital Information Systems ,Female ,Health Services Research ,cardiac surgery - Abstract
Objectives Administrative databases with dedicated coding systems in healthcare systems where providers are funded based on services recorded have been shown to be useful for clinical research, although their reliability is still questioned. We devised a custom classification of procedures and algorithms based on OPCS, enabling us to identify open heart surgeries from the English administrative database, Hospital Episode Statistics, with the objective of comparing the incidence of cardiac procedures in administrative and clinical databases. Design A comparative study of the incidence of cardiac procedures in administrative and clinical databases. Setting Data from all National Health Service Trusts in England, performing cardiac surgery. Participants Patients classified as having cardiac surgery across England between 2004 and 2015, using a combination of procedure codes, age >18 and consultant specialty, where the classification was validated against internal and external benchmarks. Results We identified a total of 296 426 cardiac surgery procedures, of which majority of the procedures were coronary artery bypass grafting (CABG), aortic valve replacement (AVR), mitral repair and aortic surgery. The matching at local level was 100% for CABG and transplant, >90% for aortic valve and major aortic procedures and >80% for mitral. At national level, results were similar for CABG (IQR 98.6%–104%), AVR (IQR 105%–118%) and mitral valve replacement (IQR 86.2%–111%). Conclusions We set up a process which can identify cardiac surgeries in England from administrative data. This will lead to the development of a risk model to predict early and late postoperative mortality, useful for risk stratification, risk prediction, benchmarking and real-time monitoring. Once appropriately adjusted, the system can be applied to other specialties, proving especially useful in those areas where clinical databases are not fully established.
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- 2019
49. NaV2O5 from sodium ion-exchanged vanadium oxide nanotubes and its efficient reversible lithiation as a Li-ion anode material
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D. Noel Buckley, David McNulty, Colm O'Dwyer, SFI, and Irish Government's Programme for Research in Third Level Institutions, Cycle 4
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Battery (electricity) ,Materials science ,Energy storage ,Sodium ,Inorganic chemistry ,Oxide ,Energy Engineering and Power Technology ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,7. Clean energy ,Vanadium oxide ,Ion ,chemistry.chemical_compound ,Materials Chemistry ,Electrochemistry ,Chemical Engineering (miscellaneous) ,Li-ion battery ,Electrical and Electronic Engineering ,Nanotubes ,021001 nanoscience & nanotechnology ,Sodium vanadate ,0104 chemical sciences ,Anode ,chemistry ,Electrode ,0210 nano-technology - Abstract
peer-reviewed The full text of this article will not be available in ULIR until the embargo expires on the 03/01/2020 Efficient synthetic protocols for stable oxide materials as Li-ion battery electrodes are important not only for improving long-term battery performance but also for tackling potential material abundance issues and understanding the nature of ion intercalation for beyond lithium technologies. Oxide anodes are denser, typically, than graphite, leading to a doubling or more of the energy density. Using oxides as lower voltage battery anodes that efficiently and reversibly intercalate cations while avoiding dominating conversion-mode side reactions is much less common. We show that ion-exchanging the molecular templates used to form scrolled, layered vanadium oxide nanotubes (VONTs) with sodium ions allows us to form NaV2O5 crystals that behave as Li-ion battery anodes with efficienct capacity retention over 1000 cycles. We also track and analyze the thermal recrystallization of intralayer Na+ ion-exchange in vanadium oxide nanotubes (Na-VONTs) to NaV2O5 by thermogravimetric analysis, X-ray and electron diffraction, transmission and scanning electron microscopy, and infrared spectroscopy. The quantification and understanding of the electrochemical performance of ion-exchanged nanotubes before and after thermal treatment was determined by cyclic voltammetry and galvanostatic cycling. NaV2O5 in the form of micro- and nanoparticles demonstrates exceptional capacity retention during long cycle life galvanostatic cycling with Li+, retaining 93% of its capacity from the 100th to the 1000th cycle, when cycled using an applied specific current of 200 mA/g in a conductive additive and binder-free formulation. Intercalation reactions dominate over much of the voltage range. Conversion mode processes are negligible and the material reversibly lithiates with charge compensation by cation (V) redox. This report offers valuable insight into the use of group I (Li, Na, etc.) elements to make vanadate bronzes as long cycle life and stable Li-ion battery anode materials with higher volumetric energy density.
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- 2019
50. A Comparison of Transition Metal Oxide Ordered Macroporous Materials Used in Battery Electrodes
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Sally O'Hanlon, Alex Lonergan, David McNulty, Aoife Carroll, and Colm O'Dwyer
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Battery (electricity) ,chemistry.chemical_compound ,Materials science ,Chemical engineering ,Transition metal ,chemistry ,Electrode ,Oxide - Abstract
This talk will summarize recent results of ordered macroporous (inverse opal) materials made from a range of transition metal oxides when used as Li-ion battery electrodes. The basic methodology for macroporous material formation will be presented for electrodes fabricated with macroporous ordered materials included TiO2, SnO2, GeO2, V2O5, their mixtures and other compounds. The talk will compare the basic lithiation response in these porous materials in Li-in battery half cells and detail the electrochemical response of each oxide and porous structure as a function of specific current (rate) and cycle life. Several of these materials offer surprisingly good electrochemical stability during long (>5000 cycles in the case of TiO2) cycle life, in a binder and conductive additive-free electrode formulation. We also summarize limits of some macroporous oxide materials at very high charge and discharge rates when used in Li-ion batteries and compare the influence of phase and structure on reversible lithiation. Related work and References O'Hanon, D. McNulty, R. Tian, J. Coleman, and C. O'Dwyer, High Charge and Discharge Rate Limitations in Ordered Macroporous Li-ion Battery Materials, J. Electrochem. Soc. 167, 140532 (2020). McNulty, H. Geaney, Q. Ramasse, and C. O'Dwyer, Long Cycle Life, Highly Ordered SnO2/GeO2 Nanocomposite Inverse Opal Anode Materials for Li‐Ion Batteries, Adv. Funct. Mater., 2005073 (2020). McNulty, H. Geaney, D. Buckley, and C. O'Dwyer, High Capacity Binder-free Nanocrystalline GeO2 Inverse Opal Anodes for Li-ion Batteries with Long Cycle Life and Stable Cell Voltage, Nano Energy 43, 11 (2018). McNulty, E. Carroll, and C. O'Dwyer, Rutile TiO2 Inverse Opal Anodes for Li-ion Batteries with Long Cycle Life, High-rate Capability and High Structural Stability, Adv. Energy Mater. 7, 1602291 (2017). McNulty, A. Lonergan, S. O'Hanlon, and C. O'Dwyer, 3D open-worked inverse opal TiO2 and GeO2 materials for long life, high capacity Li-ion battery anodes, Solid State Ionics 314, 195 (2018). Lonergan, D. McNulty, and C. O'Dwyer, Tetrahedral framework of inverse opal photonic crystals defines the optical response and photonic band gap, J. Appl. Phys. 124, 095106 (2018). O'Hanlon, D. McNulty, and C. O'Dwyer, The influence of colloidal opal template and substrate type on 3D macroporous single and binary vanadium oxide inverse opal electrodeposition, J. Electrochem. Soc. 164, D111 (2017). O'Dwyer, Colour-Coded Batteries – Inverse Opal Materials Circuitry for Enhanced Electrochemical Energy Storage and Optically Encoded Diagnostics, Adv. Mater. 28, 5681 (2016).
- Published
- 2021
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