880 research outputs found

    Tuning the Electronic and Magnetic Properties of Nitrogen-Functionalized Few-Layered Graphene Nanoflakes

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    In this work, we report on the modification of electronic and magnetic properties of few layered graphene (FLG) nanoflakes via nitrogen functionalisation carried out using radio frequency (rf-PECVD) and electron cyclotron resonance (ECR) plasma processes. Even though the rf-PECVD N2 treatment leads to higher N-doping levels in the FLGs (4.06 at%) as compared to the ECR process (2.18 at.%), the ferromagnetic behaviour of ECR FLG(118.62 x 10‚ĀĽ‚Āī emu/gm) was significantly higher than the rf-PECVD (0.39 x 10‚ĀĽ‚Āī emu/gm) and pristine graphene (3.47 x 10‚ĀĽ‚Āī emu/gm). While both plasma processes introduce electron donating N-atoms in the graphene structure, distinct dominant nitrogen bonding configurations (pyridinic, pyrrolic) were observed for each FLG type. While, the ECR plasma introduces more sp2 type nitrogen moieties, the rf-PECVD process led to the formation of sp3 coordinated nitrogen functionalities, as confirmed through Raman measurements. The samples further characterised using X-ray absorption near edge spectroscopy (XANES) and X-ray, ultraviolet photoelectron spectroscopies revealed an increased electronic density of states and a significantly higher concentration of pyrrolic groups in the rf-PECVD samples. Due to the formation of reactive edge structures and pyridinic nitrogen moieties, the ECR functionalised FLGs expressed highest saturation magnetisation behaviour with the lowest field hysteretic features. In comparison, the rf-PECVD samples, displayed the lowest saturation magnetisation owing to the disappearance of magnetic edge states and formation of stable non-radical type defects in the pyrrole type structures. Our experimental results thus provide new evidence to control the magnetic and electronic properties of few layered graphene nanoflakes via control of the plasma-processing route

    The association of a novel digital tool for assessment of early childhood cognitive development, 'DEvelopmental assessment on an E-Platform (DEEP)', with growth in rural India: A proof of concept study.

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    BACKGROUND: There is an urgent need to fill the gap of scalable cognitive assessment tools for preschool children to enable identification of children at-risk of sub-optimal development and to support their timely referral into interventions. We present the associations between growth in early childhood, a well-established marker of cognitive development, and scores on a novel digital cognitive assessment tool called DEvelopmental Assessment on an E-Platform (DEEP) on a sample of 3-year old pre-schoolers from a rural region in north India. METHODS: Between February 2018 and March 2019, 1359 children from the Sustainable Programme Incorporating Nutrition and Games (SPRING) programme were followed up at 3-years age and data on DEEP, anthropometry and a clinical developmental assessment, the Bayley's Scale of Infant and Toddler Development, 3rd edition (BSID-III) was collected. DEEP data from 200 children was used to train a machine learning algorithm to predict their score on the cognitive domain of BSID-III. The DEEP score of the remaining 1159 children was then predicted using this algorithm to examine the cross-sectional and prospective association of growth with the DEEP score. FINDINGS: The magnitude of the concurrent positive association between height-for-age and cognitive z-scores in 3-year olds was similar when cognition was measured by BSID-III (0.20 standard deviations increase for every unit change in specifically age-adjusted height (HAZ), 95% CI = 0.06-0.35) and DEEP (0.26 CI, 0.11-0.41). A similar positive prospective relationship was found between growth at 18 (0.21 CI, 0.17-0.26) and 12-months (0.18 CI, 0.13-0.23) and DEEP score measured at 3-years. Additionally, the relationship between growth and cognitive development was found to be dependant on socioeconomic status (SES). INTERPRETATION: In this study, we suggest the utility of DEEP, a scalable, digital cognitive assessment tool, to measure cognition in preschool children. Further validation in different and larger datasets is necessary to confirm our findings. FUNDING: The SPRING Programme was funded through a Wellcome Trust programme grant and the follow-up study by the Corporate Social Responsibility initiative grant from Madura Microfinance Ltd

    The effect of cumulative early life adversities, and their differential mediation through hair cortisol levels, on childhood growth and cognition: Three-year follow-up of a birth cohort in rural India.

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    Background: Early adversities negatively impact children's growth and development, putatively mediated by chronic physiological stress resulting from these adverse experiences. We aimed to estimate the associations between prospectively measured cumulative early adversities with growth and cognition outcomes in rural Indian preschool children and to explore if hair cortisol concentration (HCC), a measure of chronic physiological stress, mediated the above association. Methods: Participants were recruited from the SPRING cRCT in rural Haryana, India. Adversities experienced through pregnancy and the first year of life were measured in 1304 children at 12-months. HCC was measured at 12-months in 845 of them. Outcome measures were height-for-age-z-score (HAZ), weight-for-age-z-score (WAZ) and cognition, measured in 1124 children followed up at 3-years. Cognition was measured using a validated tablet-based gamified tool named DEEP. Results: Cumulative adversities at 12-months were inversely associated with all outcomes measures at 3-years. Each unit increase in adversity score led to a decrease of 0·08 units [95% confidence interval (CI):-0·11,-0·06] in DEEP-z-score; 0·12 units [-0·14,-0·09] in HAZ and 0·11 units [-0·13,-0·09] in WAZ. 12-month HCC was inversely associated with DEEP-z-score (-0·09 [-0·16,-0·01]) and HAZ (-0·12 [-0·20,-0·04]), but the association with WAZ was not significant (p = 0·142). HCC marginally mediated the association between cumulative adversities and HAZ (proportion mediated = 0·06, p = 0·014). No evidence of mediation was found for the cognition outcome. Conclusions: Cumulative early adversities and HCC measured at 12-months have persistent negative effects on child growth and cognition at 3-years. The association between adversities and these two child outcomes were differentially mediated by HCC, with no evidence of mediation observed for the cognitive outcome. Future studies should focus on other stress biomarkers, and alternate pathways such as the immune, inflammation and cellular ageing pathways, to unpack key mechanisms underlying the established relationship between early adversities and poor child outcomes

    Optimasi Portofolio Resiko Menggunakan Model Markowitz MVO Dikaitkan dengan Keterbatasan Manusia dalam Memprediksi Masa Depan dalam Perspektif Al-Qur`an

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    Risk portfolio on modern finance has become increasingly technical, requiring the use of sophisticated mathematical tools in both research and practice. Since companies cannot insure themselves completely against risk, as human incompetence in predicting the future precisely that written in Al-Quran surah Luqman verse 34, they have to manage it to yield an optimal portfolio. The objective here is to minimize the variance among all portfolios, or alternatively, to maximize expected return among all portfolios that has at least a certain expected return. Furthermore, this study focuses on optimizing risk portfolio so called Markowitz MVO (Mean-Variance Optimization). Some theoretical frameworks for analysis are arithmetic mean, geometric mean, variance, covariance, linear programming, and quadratic programming. Moreover, finding a minimum variance portfolio produces a convex quadratic programming, that is minimizing the objective function √į√į¬•with constraints√į √į √į¬• ¬• √įand√į¬ī√į¬• = √į. The outcome of this research is the solution of optimal risk portofolio in some investments that could be finished smoothly using MATLAB R2007b software together with its graphic analysis

    Differential cross section measurements for the production of a W boson in association with jets in proton‚Äďproton collisions at ‚ąös = 7 TeV