278 research outputs found

    Polymer-supported l-prolinol-based catalysts for the enantioselective addition of dialkylzinc reagents to N-(diphenylphosphinyl)imines

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    l-Prolinol-based ligands anchored to Merrifield or Wang-type resins have been shown to form efficient catalysts for the enantioselective addition of dialkylzinc reagents to N-(diphenylphosphinyl)imines. The enantioselectivity achieved with the polymeric catalyst (ee up to 88%) is slightly lower than the one obtained with the homogeneous ligand N-benzyl-l-prolinol, but the polymer-supported ligand presents the advantage of its recyclability: it can be recovered and used in up to six consecutive catalytic cycles with only a slight decrease in the enantiomeric excess. The phosphinamides obtained as addition products can be transformed into the corresponding enantiomerically enriched α-branched primary amines under mild acidic conditions.This work was generously supported by the Spanish Ministerio de Ciencia e Innovación (MICINN; grant no. CONSOLIDER INGENIO 2010, CSD2007-00006, CTQ2007-65218 and CTQ11-24151) and the Generalitat Valenciana (PROMETEO/2009/039, FEDER and GV/2007/036). R.A. thanks the Spanish Ministerio de Educación y Ciencia for a predoctoral fellowship. J.F.C. thanks the Instituto de Síntesis Orgánica for a fellowship

    An instability criterion for nonlinear standing waves on nonzero backgrounds

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    A nonlinear Schr\"odinger equation with repulsive (defocusing) nonlinearity is considered. As an example, a system with a spatially varying coefficient of the nonlinear term is studied. The nonlinearity is chosen to be repelling except on a finite interval. Localized standing wave solutions on a non-zero background, e.g., dark solitons trapped by the inhomogeneity, are identified and studied. A novel instability criterion for such states is established through a topological argument. This allows instability to be determined quickly in many cases by considering simple geometric properties of the standing waves as viewed in the composite phase plane. Numerical calculations accompany the analytical results.Comment: 20 pages, 11 figure

    Perbandingan Sifat Mekanik Bioplastik Terhadap Penambahan Zinc Oxide (Zno)

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    Bioplastik merupakan jenis plastik yang terbuat dari bahan alami sehingga dapat dengan mudah terdegradasi oleh aktivitas mikroorganisme salah bahannya adalah pati singkong. Akan tetapi bioplastik belum bisa diproduksi secara masal dan digunakan sehari-hari karena mamiliki sifat yang belum sesuai untuk menggantikan plastik yang ada saat ini. Penelitian ini bertujuan untuk mengetahui perbandingan sifat dan karakterisasi bioplastik tanpa penambahan filler lain dan bioplastik dengan penambahan nanopartikel Zinc Oxide. Beberapa pengujian dan karakterisasi dilakukan dalam penelitian ini, meliputi struktur morfologi, kekuatan mekanik, dan biodegradasi. Dari karakterisasi SEM dihasilkan bahwa bioplastik dengan penambahan nanopartikel Zinc Oxide cenderung memiliki morfologi yang lebih baik, tidak retak, walaupun terdapat agregasi partikel. Pengujian lain menunjukan bahwa nanopartikel Zinc Oxide mampu meningkatkan kekuatan tarik bioplastik namun menghambat pertumbuhan mikroorganism

    What do we evaluate in sport mindfulness interventions? A systematic review of commonly used questionnaires

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    Interest of the study: mindfulness is a concept describing the focus on the present moment, intentionally and without judgement. This approach has only recently been applied to sport psychology. Objectives: the aim of the current review is to investigate which indicators and questionnaires are used in mindfulness research in sport, being specifically interested in mindfulness assessment. Methods: PRISMA guidelines for systematic reviews and the recommendations of the Cochrane Collaboration were used. Literature searches were conducted in Psychinfo, PubMed, EMBASE and the Cochrane Library. Results: From 2, 203 records initially retrieved, 17 articles were included. The results show that mindfulness, anxiety and acceptance are the most commonly studied psychological indicators. The Five Facet Mindfulness Questionnaire is the most frequently used mindfulness scale. We also discuss the possibility of using physiological indicators as complementary assessment. Conclusions: It is recommended to specifically adapt some questionnaires, such is already done with the Sport Anxiety Scale or the Mindfulness Inventory for Sport, for their use in sport psychology

    Flow properties of Ficus deltoidea extract powder and the binders, Acdisol and Avicel

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    This work aimed to investigate the flowability properties of the basic powders used to make tablets by means of direct compression. The main product in this study is Ficus deltoidea extract powder, while the excipients operated as binder were croscarmellose sodium (NaCMC or Acdisol) and microcrystalline cellulose (MCC or Avicel). Such excipient powders are essentially water insoluble and can also act as a filler, disintegrator and dissolver in tablet form. In order to compare and optimize powders regarding flowability, a Jenike shear tester was used to measure the flow properties of the powder particle, such as the effective angle of internal friction, flow function and the angle of wall friction. The experimental results showed higher flow property values for binders compared with F. deltoidea extract powder. These results provide essential information for the processing and handling of these powders during storage, transportation and also for the next processing step of powder – tabletting

    Changes in metabolites in the brain of patients with fibromyalgia after treatment with an NMDA receptor antagonist

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    The aims of this work were to evaluate whether the treatment of patients with fibromyalgia with memantine is associated with significant changes in metabolite concentrations in the brain, and to explore any changes in clinical outcome measures. Magnetic resonance spectroscopy was performed of the right anterior and posterior insula, both hippocampi and the posterior cingulate cortex. Questionnaires on pain, anxiety, depression, global function, quality of life and cognitive impairment were used. Ten patients were studied at baseline and after three months of treatment with memantine. Significant increases were observed in the following areas: N-acetylaspartate (4.47 at baseline vs. 4.71 at three months, p¿=¿0.02) and N-acetylaspartate+N-acetylaspartate glutamate in the left hippocampus (5.89 vs. 5.98; p¿=¿0.007); N-acetylaspartate+N-acetylaspartate glutamate in the right hippocampus (5.31 vs 5.79; p¿=¿0.01) and the anterior insula (7.56 vs. 7.70; p¿=¿0.033); glutamate+glutamine/creatine ratio in the anterior insula (2.03 vs. 2.17; p¿=¿0.022) and the posterior insula (1.77 vs. 2.00; p¿=¿0.004); choline/creatine ratio in the posterior cingulate (0.18 vs. 0.19; p¿=¿0.023); and creatine in the right hippocampus (3.60 vs. 3.85; p¿=¿0.007). At the three-month follow-up, memantine improved cognitive function assessed by the Cognition Mini-Exam (31.50, SD¿=¿2.95 vs. 34.40, SD¿=¿0.6; p¿=¿0.005), depression measured by the Hamilton Depression Scale (7.70, SD¿=¿0.81 vs. 7.56, SD¿=¿0.68; p¿=¿0.042) and severity of illness measured by the Clinical Global Impression severity scale (5.79, SD¿=¿0.96 vs. 5.31, SD¿=¿1.12; p¿=¿0.007). Depression, clinical global impression and cognitive function showed improvement with memantine. Magnetic resonance spectroscopy could be useful in monitoring response to the pharmacological treatment of fibromyalgia

    Alpha band disruption in the AD-continuum starts in the subjective cognitive decline stage: a MEG study

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    The consideration of Subjective Cognitive Decline (SCD) as a preclinical stage of AD remains still a matter of debate. Alpha band alterations represent one of the most significant changes in the electrophysiological profile of AD. In particular, AD patients exhibit reduced alpha relative power and frequency. We used alpha band activity measured with MEG to study whether SCD and MCI elders present these electrophysiological changes characteristic of AD, and to determine the evolution of the observed alterations across AD spectrum. The total sample consisted of 131 participants: 39 elders without SCD, 41 elders with SCD and 51 MCI patients. All of them underwent MEG and MRI scans and neuropsychological assessment. SCD and MCI patients exhibited a similar reduction in alpha band activity compared with the no SCD group. However, only MCI patients showed a slowing in their alpha peak frequency compared with both SCD and no SCD. These changes in alpha band were related to worse cognition. Our results suggest that AD-related alterations may start in the SCD stage, with a reduction in alpha relative power. It is later, in the MCI stage, where the slowing of the spectral profile takes place, giving rise to objective deficits in cognitive functioning.This study was supported by two projects from the Spanish Ministry of Economy and Competitiveness, PSI2009-14415-C03-01 and PSI2012-38375-C03-01, a predoctoral fellowship from the Ministry of Economy and Competitiveness to DLS (PSI2012-38375-C03-01), and three predoctoral fellowships from the Ministry of Education to RB,NS,ICRR (FPU13/06009, FPU14/07164, FPU13/02064)

    SK channels contribution to ventricular electrophysiology in heart failure patients

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    Heart failure (HF) is characterized by deterioration of the electrical and contractile function of the heart due to structural and functional remodelling, leading to development of arrhythmias and increased sudden cardiac death risk. SK channels are a type of calcium-activated potassium channels that do not play a relevant role in normal ventricular electrophysiology. However, it has been hypothesized that these channels become more relevant in pathologies such as HF. Nontheless, their role in human ventricular electrophysiology is not fully characterized

    Can pictures have explicatures?

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    This paper considers the question of whether pictures can be understood to give rise to explicit meanings. In relevance-theoretic terms, this means asking whether pictures give rise to ‘explicatures’. The definition of the term ‘explicature’ seems to rule out this possibility except in cases where pictures include or are accompanied by material with coded meanings. The paper considers a range of non-verbal phenomena with coded meanings, including pictograms (Forceville 2011, Forceville et al 2014). It then considers whether the explicature-implicature distinction could be relevant to pictures without such elements. Some assumptions communicated by pictures seem to be more ‘explicature-like’ than others, so it is possible that the distinction will be useful. The question is not merely terminological as the discussion leads to a fuller understanding of ways in which pictures communicate
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