191 research outputs found

    Supercapacitor Degradation: Understanding Mechanisms of Cycling-Induced Deterioration and Failure of a Pseudocapacitor

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    Owing to a reputation for long lifetimes and excellent cycle stability, degradation in supercapacitors has largely been overlooked. In this work, we demonstrate that significant degradation in some commercial supercapacitors can in fact occur early in their life, leading to a rapid loss in capacitance, especially when utilized in full voltage range, high charge-discharge frequency applications. By using a commercial 300 F lithium-ion pseudocapacitor rated for 100,000 charge/discharge cycles as an example system, it is shown that a ∼96 % loss in capacitance over the first ∼2000 cycles is caused by significant structural and chemical change in the cathode active material (LiMn2O4, LMO). Multi-scale in-situ and ex-situ characterization, using a combination of X-ray computed tomography, Raman spectroscopy and X-ray photoelectron spectroscopy, shows that while minimal material loss (∼5.5 %), attributed to the dissolution of Mn2+, is observed, the primary mode of degradation is due to manganese charge disproportionation (Mn3+→Mn4++Mn2+) and its physical consequences (i. e. microstrain formation, particle fragmentation, loss of conductivity etc.). In contrast to prior understanding of LMO material degradation in battery systems, negligible contributions from cubic-to-tetragonal phase transitions are observed. Hence, as supercapacitors are becoming more widely utilized in real-world applications, this work demonstrates that it is vital to understand the mechanisms by which this family of devices change during their lifetimes, not just for lithium-ion pseudocapacitors, but for a wide range of commercial chemistries

    Targeted, structured text messaging to improve dietary and lifestyle behaviours for people on maintenance haemodialysis (KIDNEYTEXT): Study protocol for a randomised controlled trial

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    Introduction Managing nutrition is critical for reducing morbidity and mortality in patients on haemodialysis but adherence to the complex dietary restrictions remains problematic. Innovative interventions to enhance the delivery of nutritional care are needed. The aim of this phase II trial is to evaluate the feasibility and effectiveness of a targeted mobile phone text messaging system to improve dietary and lifestyle behaviours in patients on long-term haemodialysis. Methods and analysis Single-blinded randomised controlled trial with 6 months of follow-up in 130 patients on haemodialysis who will be randomised to either standard care or KIDNEYTEXT. The KIDNEYTEXT intervention group will receive three text messages per week for 6 months. The text messages provide customised dietary information and advice based on renal dietary guidelines and general healthy eating dietary guidelines, and motivation and support to improve behaviours. The primary outcome is feasibility including recruitment rate, drop-out rate, adherence to renal dietary recommendations, participant satisfaction and a process evaluation using semistructured interviews with a subset of purposively sampled participants. Secondary and exploratory outcomes include a range of clinical and behavioural outcomes and a healthcare utilisation cost analysis will be undertaken. Ethics and dissemination The study has been approved by the Western Sydney Local Health District Human Research Ethics Committee-Westmead. Results will be presented at scientific meetings and published in peer-reviewed publications. Trial registration number ACTRN12617001084370; Pre-results

    Mental health in UK Biobank: development, implementation and results from an online questionnaire completed by 157 366 participants

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    Background UK Biobank is a well-characterised cohort of over 500 000 participants that offers unique opportunities to investigate multiple diseases and risk factors. Aims An online mental health questionnaire completed by UK Biobank participants was expected to expand the potential for research into mental disorders. Method An expert working group designed the questionnaire, using established measures where possible, and consulting with a patient group regarding acceptability. Case definitions were defined using operational criteria for lifetime depression, mania, anxiety disorder, psychotic-like experiences and self-harm, as well as current post-traumatic stress and alcohol use disorders. Results 157 366 completed online questionnaires were available by August 2017. Comparison of self-reported diagnosed mental disorder with a contemporary study shows a similar prevalence, despite respondents being of higher average socioeconomic status than the general population across a range of indicators. Thirty-five per cent (55 750) of participants had at least one defined syndrome, of which lifetime depression was the most common at 24% (37 434). There was extensive comorbidity among the syndromes. Mental disorders were associated with high neuroticism score, adverse life events and long-term illness; addiction and bipolar affective disorder in particular were associated with measures of deprivation. Conclusions The questionnaire represents a very large mental health survey in itself, and the results presented here show high face validity, although caution is needed owing to selection bias. Built into UK Biobank, these data intersect with other health data to offer unparalleled potential for crosscutting biomedical research involving mental health

    The Exotic Eclipsing Nucleus of the Ring Planetary Nebula SuWt2

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    SuWt2 is a planetary nebula (PN) consisting of a bright ionized thin ring seen nearly edge-on. It has a bright (V=12) central star, too cool to ionize the PN, which we discovered to be an eclipsing binary. A spectrum from IUE did not reveal a UV source. We present extensive ground-based photometry and spectroscopy of the central binary collected over the ensuing two decades, resulting in the determination that the orbital period of the eclipsing pair is 4.9 d, and consists of two nearly identical A1 V stars, each of mass ~2.7 M_sun. The physical parameters of the A stars, combined with evolutionary tracks, show that both are in the short-lived "blue-hook" evolutionary phase that occurs between the main sequence and the Hertzsprung gap, and that the age of the system is about 520 Myr. One puzzle is that the stars' rotational velocities are different from each other, and considerably slower than synchronous with the orbital period. It is possible that the center-of-mass velocity of the eclipsing pair is varying with time, suggesting that there is an unseen third orbiting body in the system. We propose a scenario in which the system began as a hierarchical triple, consisting of a ~2.9 M_sun star orbiting the close pair of A stars. Upon reaching the AGB stage, the primary engulfed the pair into a common envelope, leading to a rapid contraction of the orbit and catastrophic ejection of the envelope into the orbital plane. In this picture, the exposed core of the initial primary is now a white dwarf of ~0.7 M_sun, orbiting the eclipsing pair, which has already cooled below the detectability possible by IUE at our derived distance of 2.3 kpc and a reddening of E(B-V)=0.40. The SuWt2 system may be destined to perish as a Type Ia supernova. (Abridged)Comment: 60 pages, 11 figure, to appear in the Astronomical Journa

    Randomized, phase II selection study of ramucirumab and paclitaxel versus FOLFIRI in refractory small bowel adenocarcinoma: SWOG S1922

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    Background: Small bowel adenocarcinoma is a rare malignancy with limited evidence to support the choice of systemic chemotherapy beyond the frontline setting. Though second-line therapy has historically been extrapolated from colorectal cancers, recent molecular data has demonstrated small bowel adenocarcinoma to be genomically unique when compared to either colon or gastric cancer. Retrospective analyses of irinotecan- and taxane-based therapies and one prospective phase II clinical trial of nab-paclitaxel have demonstrated clinical activity in this cancer. Ramucirumab/paclitaxel represents an active combination in the management of gastric cancer. SWOG 1922 evaluates the use of FOLFIRI or ramucirumab/paclitaxel in the second- and later-line setting for small bowel adenocarcinoma. Methods: This is randomized, phase II, selection design clinical trial of FOLFIRI (5-fluorouracil, leucovorin and irinotecan) every two weeks or ramucirumab D1,15 and paclitaxel D1,8,15 every 4 weeks with the primary endpoint of progression-free survival (PFS). Secondary endpoints include response rate, overall survival, and safety. Archived paraffin tumor tissue collection and serial blood collections are included for correlative analyses. Key eligibility criteria include having mismatch repair proficient/microsatellite stable small bowel adenocarcinoma (ampullary location excluded); metastatic or locally advanced unresectable disease; prior fluoropyrimidine and/or oxaliplatin therapy; no prior treatment with irinotecan, ramucirumab, or taxanes; no recent bleeding, blood clots, or bowel perforation/fistula; and Zubrod performance status of 0/1. Measurable disease is not required. The null hypothesis is median PFS of 2.5 months. If a median PFS of at least 3.5 months is observed in one or both arms, the goal is to choose the better regimen with respect to this endpoint. The design provides a 90% probability of selecting the more active arm, assuming a hazard ratio of 1.4, if both arms meet this threshold. This trial is open and, as of September 1, 2021, 21 of 94 planned patients have been enrolled

    A coaching program to improve dietary intake of patients with CKD: ENTICE-CKD

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    The dietary self-management of CKD is challenging. Telehealth interventions may provide an effective delivery method to facilitate sustained dietary change.This pilot, randomized, controlled trial evaluated secondary and exploratory outcomes after a dietitian-led telehealth coaching intervention to improve diet quality in people with stage 3-4 CKD. The intervention group received phone calls every 2 weeks for 3 months (with concurrent, tailored text messages for 3 months), followed by 3 months of tailored text messages without telephone coaching, to encourage a diet consistent with CKD guidelines. The control group received usual care for 3 months, followed by nontailored, educational text messages for 3 months.Eighty participants (64% male), aged 62±12 years, were randomized to the intervention or control group. Telehealth coaching was safe, with no adverse events or changes to serum biochemistry at any time point. At 3 months, the telehealth intervention, compared with the control, had no detectable effect on overall diet quality on the Alternative Health Eating Index (3.2 points, 95% confidence interval, -1.3 to 7.7), nor at 6 months (0.5 points, 95% confidence interval, -4.6 to 5.5). There was no change in clinic BP at any time point in any group. There were significant improvements in several exploratory diet and clinical outcomes, including core food group consumption, vegetable servings, fiber intake, and body weight.Telehealth coaching was safe, but appeared to have no effect on the Alternative Healthy Eating Index or clinic BP. There were clinically significant changes in several exploratory diet and clinical outcomes, which require further investigation.Evaluation of Individualized Telehealth Intensive Coaching to Promote Healthy Eating and Lifestyle in CKD (ENTICE-CKD), ACTRN12616001212448

    Gaps and opportunities in refractory status epilepticus research in children: A multi-center approach by the Pediatric Status Epilepticus Research Group (pSERG)

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    PURPOSE: Status epilepticus (SE) is a life-threatening condition that can be refractory to initial treatment. Randomized controlled studies to guide treatment choices, especially beyond first-line drugs, are not available. This report summarizes the evidence that guides the management of refractory convulsive SE (RCSE) in children, defines gaps in our clinical knowledge and describes the development and works of the \u27pediatric Status Epilepticus Research Group\u27 (pSERG). METHODS: A literature review was performed to evaluate current gaps in the pediatric SE and RCSE literature. In person and online meetings helped to develop and expand the pSERG network. RESULTS: The care of pediatric RCSE is largely based on extrapolations of limited evidence derived from adult literature and supplemented with case reports and case series in children. No comparative effectiveness trials have been performed in the pediatric population. Gaps in knowledge include risk factors for SE, biomarkers of SE and RCSE, second- and third-line treatment options, and long-term outcome. CONCLUSION: The care of children with RCSE is based on limited evidence. In order to address these knowledge gaps, the multicenter pSERG was established to facilitate prospective collection, analysis, and sharing of de-identified data and biological specimens from children with RCSE. These data will allow identification of treatment strategies associated with better outcomes and delineate evidence-based interventions to improve the care of children with SE

    Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial

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    Background Findings from the RESTART trial suggest that starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. Brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases (such as cerebral microbleeds) are associated with greater risks of recurrent intracerebral haemorrhage. We did subgroup analyses of the RESTART trial to explore whether these brain imaging features modify the effects of antiplatelet therapy
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