30 research outputs found
Controlled Dispersion of Polystyrene-Capped Au Nanospheres in P3HT:PC61BM and Consequences upon Active Layer Nanostructure
No full textNumerous recent publications detail higher absorption and photovoltaic performance within organic photovoltaic (OPV) devices which are loaded with Au or Ag nanoparticles to leverage the light management properties of the localized surface plasmon resonance (LSPR). This report details the impact upon film morphology and polymer/nanoparticle interactions caused by incorporation of polystyrene-coated Au nanoparticles (Au/PS) into the P3HT:PC61BM bulk heterojunction film. Nanostructural analysis by transmission electron microscopy and X-ray scattering reveals tunable Au/PS particle assembly that depends upon the choice of casting solvent, polymer chain length, film drying time, and Au/PS particle loading density. This Au/PS particle assembly has implications on the spectral position of the Au nanoparticle LSPR, which shifts from 535 nm for individually dispersed particles in toluene to 650 nm for particles arranged in large clusters within the P3HT:PC61BM matrix. These results suggest a critical impact from PS/P3HT phase separation, which causes controlled assembly of a separate Au/PS phase in the nanoparticle/OPV composite; controlled Au/PS phase formation provides a blueprint for designing AuNP/OPV hybrid films that impart tunable optical behavior and potentially improve photovoltaic performance
Synthesis and functionalization of gold nanorods for probing plasmonic enhancement mechanisms in organic photovoltaic active layers
No full textIncorporation of plasmonic nanostructures into organic photovoltaic solar cells (OPVs) is proposed to address photovoltaic losses within these devices, such as radiative and non-radiative charge recombination, and insufficient light trapping. Plasmonic nanostructures are sub-wavelength antennae that harness light energy through localized surface plasmon resonances (LSPRs), providing energy-specific light management through far-field Rayleigh-scattering. Furthermore, induction of LSPRs produces high electric fields local to the nanostructure, which have been shown to enhance absorption and emission in fluorescent organic molecules; both manifestations of plasmon resonance are expected to enhance OPV performance through increased light-trapping, and active layer absorbance or emission, respectively. Herein, we employ the aspect ratio-dependent longitudinal-LSPR (L-LSPR) of gold nanorods to investigate plasmonic enhancement in OPVs. In this dissertation, gold nanorods (Au NRs) are fabricated by a seed-mediated synthesis. Methods are developed to provide L-LSPRs between 667 nm and 1018 nm using identical growth conditions; altering aspect ratio is performed by controlling the introduction time of the co-surfactant benzyldimethylammonium chloride (BDAC) to the NR growth reaction. The time-dependent influence of BDAC on Au NR aspect ratio is most evident during early times of NR growth (0-20 minutes), directly correlating to growth stages which are susceptible to epitaxial micellar adsorption and passivation of the growing crystalline facets. Analysis of Au NR morphology indicate that increased aspect ratio is brought about through BDAC’s inhibition of Au adatom adsorption to longitudinal facets, and a simultaneous increase in adatom adsorption to tip facets. A series of Au NRs are then fabricated, functionalized, and dispersed within poly (3-hexylthiophene): phenyl-C61-butyric acid methyl ester (P3HT: PCBM) bulk-heterojunction active layers. Au NRs with L-LSPRs of varying spectral overlap with the absorption and emission bands of the electron donor’s (P3HT) spectrum are prepared, in order to probe far-field and near-field enhancement mechanisms. OPV devices are fabricated from the nanoparticle-active layer composites, and their photovoltaic performance characterized. Substantial improvements in power conversion efficiency, up to 30%, are reported. Device performance increases with increasing L-LSPR wavelength. Evidence of plasmonic enhancements is not explicit; increased efficiency is attributed to improvements in molecular ordering of P3HT, as indicated by grazing incidence x-ray diffraction studies.Ph. D.Includes bibliographical referencesby Robert Christopher Wadam
Screening for left ventricular hypertrophy in patients with type 2 diabetes mellitus in the community
No full textAbstract Background Left ventricular hypertrophy (LVH) is a strong predictor of cardiovascular disease and is common among patients with type 2 diabetes. However, no systematic screening for LVH is currently recommended for patients with type 2 diabetes. The purpose of this study was to determine whether NT-proBNP was superior to 12-lead electrocardiography (ECG) for detection of LVH in patients with type 2 diabetes. Methods Prospective cross-sectional study comparing diagnostic accuracy of ECG and NT-proBNP for the detection of LVH among patients with type 2 diabetes. Inclusion criteria included having been diagnosed for > 5 years and/or on treatment for type 2 diabetes; patients with Stage 3/4 chronic kidney disease and known cardiovascular disease were excluded. ECG LVH was defined as either the Sokolow-Lyon or Cornell voltage criteria. NT-proBNP level was measured using the Roche Diagnostics Elecsys assay. Left ventricular mass was assessed from echocardiography. Receiver operating characteristic curve analysis was carried out and area under the curve (AUC) was calculated. Results 294 patients with type 2 diabetes were recruited, mean age 58 (SD 11) years, BP 134/81 ± 18/11 mmHg, HbA1c 7.3 ± 1.5%. LVH was present in 164 patients (56%). In a logistic regression model age, gender, BMI and a history of hypertension were important determinants of LVH (p Conclusions LVH was highly prevalent in asymptomatic patients with type 2 diabetes. ECG was an inadequate test to identify LVH and while NT-proBNP was superior to ECG it remained unsuitable for detecting LVH. Thus, there remains a need for a screening tool to detect LVH in primary care patients with type 2 diabetes to enhance risk stratification and management.</p
Common, low-frequency, rare, and ultra-rare coding variants contribute to COVID-19 severity
No full textThe combined impact of common and rare exonic variants in COVID-19 host genetics is currently insufficiently understood. Here, common and rare variants from whole-exome sequencing data of about 4000 SARS-CoV-2-positive individuals were used to define an interpretable machine-learning model for predicting COVID-19 severity. First, variants were converted into separate sets of Boolean features, depending on the absence or the presence of variants in each gene. An ensemble of LASSO logistic regression models was used to identify the most informative Boolean features with respect to the genetic bases of severity. The Boolean features selected by these logistic models were combined into an Integrated PolyGenic Score that offers a synthetic and interpretable index for describing the contribution of host genetics in COVID-19 severity, as demonstrated through testing in several independent cohorts. Selected features belong to ultra-rare, rare, low-frequency, and common variants, including those in linkage disequilibrium with known GWAS loci. Noteworthily, around one quarter of the selected genes are sex-specific. Pathway analysis of the selected genes associated with COVID-19 severity reflected the multi-organ nature of the disease. The proposed model might provide useful information for developing diagnostics and therapeutics, while also being able to guide bedside disease management. © 2021, The Author(s)
Prehospital transdermal glyceryl trinitrate in patients with ultra-acute presumed stroke (RIGHT-2): an ambulance-based, randomised, sham-controlled, blinded, phase 3 trial
No full text© 2019 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license Background: High blood pressure is common in acute stroke and is a predictor of poor outcome; however, large trials of lowering blood pressure have given variable results, and the management of high blood pressure in ultra-acute stroke remains unclear. We investigated whether transdermal glyceryl trinitrate (GTN; also known as nitroglycerin), a nitric oxide donor, might improve outcome when administered very early after stroke onset. Methods: We did a multicentre, paramedic-delivered, ambulance-based, prospective, randomised, sham-controlled, blinded-endpoint, phase 3 trial in adults with presumed stroke within 4 h of onset, face-arm-speech-time score of 2 or 3, and systolic blood pressure 120 mm Hg or higher. Participants were randomly assigned (1:1) to receive transdermal GTN (5 mg once daily for 4 days; the GTN group) or a similar sham dressing (the sham group) in UK-based ambulances by paramedics, with treatment continued in hospital. Paramedics were unmasked to treatment, whereas participants were masked. The primary outcome was the 7-level modified Rankin Scale (mRS; a measure of functional outcome) at 90 days, assessed by central telephone follow-up with masking to treatment. Analysis was hierarchical, first in participants with a confirmed stroke or transient ischaemic attack (cohort 1), and then in all participants who were randomly assigned (intention to treat, cohort 2) according to the statistical analysis plan. This trial is registered with ISRCTN, number ISRCTN26986053. Findings: Between Oct 22, 2015, and May 23, 2018, 516 paramedics from eight UK ambulance services recruited 1149 participants (n=568 in the GTN group, n=581 in the sham group). The median time to randomisation was 71 min (IQR 45–116). 597 (52%) patients had ischaemic stroke, 145 (13%) had intracerebral haemorrhage, 109 (9%) had transient ischaemic attack, and 297 (26%) had a non-stroke mimic at the final diagnosis of the index event. In the GTN group, participants' systolic blood pressure was lowered by 5·8 mm Hg compared with the sham group (
Clinical utility and prognostic implications of the novel 4S-AF scheme to characterize and evaluate patients with atrial fibrillation: a report from ESC-EHRA EORP-AF Long-Term General Registry
No full textAims: The 4S-AF classification scheme comprises of four domains: stroke risk (St), symptoms (Sy), severity of atrial fibrillation (AF) burden (Sb), and substrate (Su). We sought to examine the implementation of the 4S-AF scheme in the EORP-AF General Long-Term Registry and compare outcomes in AF patients according to the 4S-AF-led decision-making process. Methods and results: Atrial fibrillation patients from 250 centres across 27 European countries were included. A 4S-AF score was calculated as the sum of each domain with a maximum score of 9. Of 6321 patients, 8.4% had low (St), 47.5% EHRA I (Sy), 40.5% newly diagnosed or paroxysmal AF (Sb), and 5.1% no cardiovascular risk factors or left atrial enlargement (Su). Median follow-up was 24 months. Using multivariable Cox regression analysis, independent predictors of all-cause mortality were (St) [adjusted hazard ratio (aHR) 8.21, 95% confidence interval (CI): 2.60-25.9], (Sb) (aHR 1.21, 95% CI: 1.08-1.35), and (Su) (aHR 1.27, 95% CI: 1.14-1.41). For CV mortality and any thromboembolic event, only (Su) (aHR 1.73, 95% CI: 1.45-2.06) and (Sy) (aHR 1.29, 95% CI: 1.00-1.66) were statistically significant, respectively. None of the domains were independently linked to ischaemic stroke or major bleeding. Higher 4S-AF score was related to a significant increase in all-cause mortality, CV mortality, any thromboembolic event, and ischaemic stroke but not major bleeding. Treatment of all 4S-AF domains was associated with an independent decrease in all-cause mortality (aHR 0.71, 95% CI: 0.55-0.92). For each 4S-AF domain left untreated, the risk of all-cause mortality increased substantially (aHR 1.35, 95% CI: 1.16-1.56). Conclusion: Implementation of the novel 4S-AF scheme is feasible, and treatment decisions based on this scheme improve mortality rates in AF
Impact of malignancy on outcomes in European patients with atrial fibrillation: A report from the ESC-EHRA EURObservational research programme in atrial fibrillation general long-term registry
No full textBackground: The management of patients with atrial fibrillation (AF) and malignancy is challenging given the paucity of evidence supporting their appropriate clinical management. Purpose: To evaluate the outcomes of patients with active or prior malignancy in a contemporary cohort of European AF patients. Methods: Patients enrolled in the EURObservational Research Programme in AF General Long-Term Registry were categorized into 3 categories: No Malignancy (NoMal), Prior Malignancy (PriorMal) and Active Malignancy (ActiveMal). The primary outcomes were all-cause death and the composite outcome MACE. Results: A total of 10 383 patients were analysed. Of these, 9597 (92.4%) were NoMal patients, 577 (5.6%) PriorMal and 209 (2%) ActiveMal. Lack of any antithrombotic treatment was more prevalent in ActiveMal patients (12.4%) as compared to other groups (5.0% vs 6.3% for PriorMal and NoMal, p <.001). After a median follow-up of 730 days, there were 982 (9.5%) deaths and 950 (9.7%) MACE events. ActiveMal was independently associated with a higher risk for all-cause death (HR 2.90, 95% CI 2.23–3.76) and MACE (HR 1.54, 95% CI 1.03–2.31), as well as any haemorrhagic events and major bleeding (OR 2.42, 95% CI 1.49–3.91 and OR 4.18, 95% CI 2.49–7.01, respectively). Use of oral anticoagulants was not significantly associated with a higher risk for all-cause death or bleeding in ActiveMal patients. Conclusions: In a large contemporary cohort of AF patients, active malignancy was independently associated with all-cause death, MACE and haemorrhagic events. Use of anticoagulants was not associated with a higher risk of all-cause death in patients with active malignancies
Impact of renal impairment on atrial fibrillation: ESC-EHRA EORP-AF Long-Term General Registry
No full textBackground: Atrial fibrillation (AF) and renal impairment share a bidirectional relationship with important pathophysiological interactions. We evaluated the impact of renal impairment in a contemporary cohort of patients with AF. Methods: We utilised the ESC-EHRA EORP-AF Long-Term General Registry. Outcomes were analysed according to renal function by CKD-EPI equation. The primary endpoint was a composite of thromboembolism, major bleeding, acute coronary syndrome and all-cause death. Secondary endpoints were each of these separately including ischaemic stroke, haemorrhagic event, intracranial haemorrhage, cardiovascular death and hospital admission. Results: A total of 9306 patients were included. The distribution of patients with no, mild, moderate and severe renal impairment at baseline were 16.9%, 49.3%, 30% and 3.8%, respectively. AF patients with impaired renal function were older, more likely to be females, had worse cardiac imaging parameters and multiple comorbidities. Among patients with an indication for anticoagulation, prescription of these agents was reduced in those with severe renal impairment, p <.001. Over 24 months, impaired renal function was associated with significantly greater incidence of the primary composite outcome and all secondary outcomes. Multivariable Cox regression analysis demonstrated an inverse relationship between eGFR and the primary outcome (HR 1.07 [95% CI, 1.01–1.14] per 10 ml/min/1.73 m2 decrease), that was most notable in patients with eGFR <30 ml/min/1.73 m2 (HR 2.21 [95% CI, 1.23–3.99] compared to eGFR ≥90 ml/min/1.73 m2). Conclusion: A significant proportion of patients with AF suffer from concomitant renal impairment which impacts their overall management. Furthermore, renal impairment is an independent predictor of major adverse events including thromboembolism, major bleeding, acute coronary syndrome and all-cause death in patients with AF
Impact of anthropometric factors on outcomes in atrial fibrillation patients: analysis on 10 220 patients from the European Society of Cardiology (ESC)-European Heart Rhythm Association (EHRA) EurObservational Research Programme on Atrial Fibrillation (EORP-AF) general long-term registry
No full textAim: To investigate the association of anthropometric parameters [height, weight, body mass index (BMI), body surface area (BSA), and lean body mass (LBM)] with outcomes in atrial fibrillation (AF). Methods and results: Ten-thousand two-hundred twenty patients were enrolled [40.3% females, median age 70 (62-77) years, followed for 728 (interquartile range 653-745) days]. Sex-specific tertiles were considered for the five anthropometric variables. At the end of follow-up, survival free from all-cause death was worse in the lowest tertiles for all the anthropometric variables analyzed. On multivariable Cox regression analysis, an independent association with all-cause death was found for the lowest vs. middle tertile when body weight (hazard ratio [HR] 1.66, 95%CI 1.23-2.23), BMI (HR 1.65, 95%CI 1.23-2.21), and BSA (HR 1.49, 95%CI 1.11-2.01) were analysed in female sex, as well as for body weight in male patients (HR 1.61, 95%CI 1.25-2.07). Conversely, the risk of MACE was lower for the highest tertile (vs. middle tertile) of BSA and LBM in males and for the highest tertile of weight and BSA in female patients. A higher occurrence of haemorrhagic events was found for female patients in the lowest tertile of height [odds ratio (OR) 1.90, 95%CI 1.23-2.94] and LBM (OR 2.13, 95%CI 1.40-3.26). Conclusions: In AF patients height, weight, BMI, BSA, and LBM were associated with clinical outcomes, with all-cause death being higher for patients presenting lower values of these variables, i.e. in the lowest tertiles of distribution. The anthropometric variables independently associated with other outcomes were also different between male and female subjects
Impact of clinical phenotypes on management and outcomes in European atrial fibrillation patients: a report from the ESC-EHRA EURObservational Research Programme in AF (EORP-AF) General Long-Term Registry
No full textBackground: Epidemiological studies in atrial fibrillation (AF) illustrate that clinical complexity increase the risk of major adverse outcomes. We aimed to describe European AF patients’ clinical phenotypes and analyse the differential clinical course. Methods: We performed a hierarchical cluster analysis based on Ward’s Method and Squared Euclidean Distance using 22 clinical binary variables, identifying the optimal number of clusters. We investigated differences in clinical management, use of healthcare resources and outcomes in a cohort of European AF patients from a Europe-wide observational registry. Results: A total of 9363 were available for this analysis. We identified three clusters: Cluster 1 (n = 3634; 38.8%) characterized by older patients and prevalent non-cardiac comorbidities; Cluster 2 (n = 2774; 29.6%) characterized by younger patients with low prevalence of comorbidities; Cluster 3 (n = 2955;31.6%) characterized by patients’ prevalent cardiovascular risk factors/comorbidities. Over a mean follow-up of 22.5 months, Cluster 3 had the highest rate of cardiovascular events, all-cause death, and the composite outcome (combining the previous two) compared to Cluster 1 and Cluster 2 (all P <.001). An adjusted Cox regression showed that compared to Cluster 2, Cluster 3 (hazard ratio (HR) 2.87, 95% confidence interval (CI) 2.27–3.62; HR 3.42, 95%CI 2.72–4.31; HR 2.79, 95%CI 2.32–3.35), and Cluster 1 (HR 1.88, 95%CI 1.48–2.38; HR 2.50, 95%CI 1.98–3.15; HR 2.09, 95%CI 1.74–2.51) reported a higher risk for the three outcomes respectively. Conclusions: In European AF patients, three main clusters were identified, differentiated by differential presence of comorbidities. Both non-cardiac and cardiac comorbidities clusters were found to be associated with an increased risk of major adverse outcomes
