109 research outputs found

    Surface Chemical Analysis of Solid-Electrolyte Interphase Layer on Germanium Thin Films and the Effect of Vinylene Carbonate Electrolyte Additive

    Get PDF
    Germanium thin-film anodes for Li-ion battery applications are the focus of the present work. As part of this chapter, we shall briefly review the use of germanium thin films in Li-ion batteries, and subsequently, new results pertaining to the effect of vinylene carbonate (VC) as electrolyte additive on the electrochemical performance are presented. We have used cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy to investigate the performance. Thin-film electrode performance with 0 wt. %, 5 wt. %, and 10 wt.% VC as electrolyte additive was compared to understand the role of additive’s concentration. The cell with 5 wt.% VC as electrolyte additive exhibited best performance with high specific capacity of 975 mAh/g, with a retention of 94 and 99% Coulombic efficiency at the end of 100 cycles. Ex situ surface chemical analysis of the solid-electrolyte interphase (SEI) layer has been studied in detail using X-ray photoelectron spectroscopy and correlated with the electrochemical performance

    Coronary Artery-Bypass-Graft Surgery Increases the Plasma Concentration of Exosomes Carrying a Cargo of Cardiac MicroRNAs: An Example of Exosome Trafficking Out of the Human Heart with Potential for Cardiac Biomarker Discovery

    Get PDF
    Introduction Exosome nanoparticles carry a composite cargo, including microRNAs (miRs). Cultured cardiovascular cells release miR-containing exosomes. The exosomal trafficking of miRNAs from the heart is largely unexplored. Working on clinical samples from coronary-artery by-pass graft (CABG) surgery, we investigated if: 1) exosomes containing cardiac miRs and hence putatively released by cardiac cells increase in the circulation after surgery; 2) circulating exosomes and exosomal cardiac miRs correlate with cardiac troponin (cTn), the current “gold standard” surrogate biomarker of myocardial damage. Methods and Results The concentration of exosome-sized nanoparticles was determined in serial plasma samples. Cardiac-expressed (miR-1, miR-24, miR-133a/b, miR-208a/b, miR-210), non-cardiovascular (miR-122) and quality control miRs were measured in whole plasma and in plasma exosomes. Linear regression analyses were employed to establish the extent to which the circulating individual miRs, exosomes and exosomal cardiac miR correlated with cTn-I. Cardiac-expressed miRs and the nanoparticle number increased in the plasma on completion of surgery for up to 48 hours. The exosomal concentration of cardiac miRs also increased after CABG. Cardiac miRs in the whole plasma did not correlate significantly with cTn-I. By contrast cTn-I was positively correlated with the plasma exosome level and the exosomal cardiac miRs. Conclusions The plasma concentrations of exosomes and their cargo of cardiac miRs increased in patients undergoing CABG and were positively correlated with hs-cTnI. These data provide evidence that CABG induces the trafficking of exosomes from the heart to the peripheral circulation. Future studies are necessary to investigate the potential of circulating exosomes as clinical biomarkers in cardiac patients

    The CH fraction of Carbon stars at high Galactic latitudes

    Full text link
    CH stars form a distinct class of objects with characteristic properties like iron deficiency, enrichment of carbon and overabundance in heavy elements. These properties can provide strong observational constraints for theoretical computation of nucleosynthesis at low-metallicity. An important question is the relative surface density of CH stars which can provide valuable inputs to our understanding on the role of low to intermediate-mass stars in the early Galactic chemical evolution. Spectroscopic characterization provides an effective way of identifying CH stars. The present analysis is aimed at a quantitative assessment of the fraction of CH stars in a sample of stars using a set of spectral classification criteria. The sample consists of 92 objects selected from a collection of candidate Faint High Latitude Carbon stars from the Hamburg/ESO survey. Medium resolution (R ~ 1300) spectra for these objects were obtained using OMR at VBO, Kavalur and HFOSC at HCT, IAO, Hanle, during 2007 - 2009 spanning a wavelength range 3800 - 6800 A. Spectral analysis shows 36 of the 92 objects to be potential CH stars; combined with our earlier studies (Goswami 2005, Goswami et al. 2007) this implies ~ 37% (of 243) objects as the CH fraction. We present spectral descriptions of the newly identified CH star candidates. Estimated effective temperatures, 12C/13C isotopic ratios and their locations on the two colour J-H vs H-K plot are used to support their identification.Comment: 18 pages, 8 figures,Accepted for publication in MNRA

    Exploring pre-main sequence variables of ONC: The new variables

    Full text link
    Since 2004, we have been engaged in a long-term observing program to monitor young stellar objects in the Orion Nebula Cluster. We have collected about two thousands frames in V, R, and I broad-band filters on more than two hundred nights distributed over five consecutive observing seasons. The high-quality and time-extended photometric data give us an opportunity to address various phenomena associated with young stars. The prime motivations of this project are i) to explore various manifestations of stellar magnetic activity in very young low-mass stars; ii) to search for new pre-main sequence eclipsing binaries; and iii) to look for any EXor and FUor like transient activities associated with YSOs. Since this is the first paper on this program, we give a detailed description of the science drivers, the observation and the data reduction strategies as well. In addition to these, we also present a large number of new periodic variables detected from our first five years of time-series photometric data. Our study reveals that about 72% of CTTS in our FoV are periodic, whereas, the percentage of periodic WTTS is just 32%. This indicates that inhomogeneities patterns on the surface of CTTS of the ONC stars are much more stable than on WTTS. From our multi-year monitoring campaign we found that the photometric surveys based on single-season are incapable of identifying all periodic variables. And any study on evolution of angular momentum based on single-season surveys must be carried out with caution.Comment: Accepted for publication by MNRAS, 26 pages, 17 figures, 6 table

    Pharmacology as a foreign language: A preliminary evaluation of podcasting as a supplementary learning tool for non-medical prescribing students

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>Nurses and other health professionals in the U.K. can gain similar prescribing rights to doctors by undertaking a non-medical prescribing course. Non-medical prescribing students must have a thorough understanding of the pharmacology of prescribing to ensure safe practice. Pharmacology education at this level is complicated by the variation in students' prior subject knowledge of, and anxiety about, the subject. The recent advances in technology, particularly the potential for mobile learning, provide increased opportunities for students to familiarise themselves with lecture materials and hence promote understanding. The objective of this study was therefore to evaluate both the subjective (student perception) and objective (student use and exam results) usefulness of podcasts of pharmacology lectures which were provided as an extra learning tool to two cohorts (n = 69) of non-medical prescribing students.</p> <p>Methods</p> <p>The podcasts were made available to students through the virtual learning environment WebCT. Use of podcasts by two successive cohorts of nurse prescribing students (n = 69) was tracked through WebCT. Survey data, which was collected from 44 of these students, investigated patterns of/reasons for podcast use and perceived usefulness of podcasts as a learning tool. Of these 69 students, 64 completed the pharmacology exam. In order to examine any impact of podcasts on student knowledge, their exam results were compared with those of two historical cohorts who did not have access to podcasts (n = 70).</p> <p>Results</p> <p>WebCT tracking showed that 91% of students accessed at least one podcast. 93% of students used the podcasts to revisit a lecture, 85% used podcasts for revision, and 61% used the podcasts when they had a specific question. Only 22% used the podcasts because they had missed a pharmacology session. Most students (81%) generally listened to the entire podcast rather than specific sections and most (73%) used them while referring to their lecture handouts. The majority of students found the podcasts helpful as a learning tool, as a revision aid and in promoting their understanding of the subject. Evaluation of the range of marks obtained, mode mark and mean mark suggested improved knowledge in students with access to podcasts compared to historical cohorts of students who did not have access to pharmacology podcasts.</p> <p>Conclusions</p> <p>The results of this study suggest that non-medical prescribing students utilised podcasts of pharmacology lectures, and have found the availability of these podcasts helpful for their learning. Exam results indicate that the availability of podcasts was also associated with improved exam performance.</p

    Role of microRNAs in diabetes and its cardiovascular complications

    Get PDF
    Diabetes is the most common metabolic disorder and is recognized as one of the most important health threats of our time. MicroRNAs (miRNAs) are a novel group of non-coding small RNAs that have been implicated in a variety of physiological processes, including glucose homeostasis. Recent research has suggested that miRNAs play a critical role in the pathogenesis of diabetes and its related cardiovascular complications. This review focuses on the aberrant expression of miRNAs in diabetes and examines their role in the pathogenesis of endothelial dysfunction, cardiovascular disease, and diabetic retinopathy. Furthermore, we discuss the potential role of miRNAs as blood biomarkers and examine the potential of therapeutic interventions targeting miRNAs in diabetes

    Common variation in PHACTR1 is associated with susceptibility to cervical artery dissection

    Get PDF
    Cervical artery dissection (CeAD), a mural hematoma in a carotid or vertebral artery, is a major cause of ischemic stroke in young adults although relatively uncommon in the general population (incidence of 2.6/100,000 per year). Minor cervical traumas, infection, migraine and hypertension are putative risk factors, and inverse associations with obesity and hypercholesterolemia are described. No confirmed genetic susceptibility factors have been identified using candidate gene approaches. We performed genome-wide association studies (GWAS) in 1,393 CeAD cases and 14,416 controls. The rs9349379[G] allele (PHACTR1) was associated with lower CeAD risk (odds ratio (OR) = 0.75, 95% confidence interval (CI) = 0.69-0.82; P = 4.46 × 10(-10)), with confirmation in independent follow-up samples (659 CeAD cases and 2,648 controls; P = 3.91 × 10(-3); combined P = 1.00 × 10(-11)). The rs9349379[G] allele was previously shown to be associated with lower risk of migraine and increased risk of myocardial infarction. Deciphering the mechanisms underlying this pleiotropy might provide important information on the biological underpinnings of these disabling conditions
    corecore