647 research outputs found

    Fluorescence-Based Ratiometric Nanosensor for Selective Imaging of Cancer Cells

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    Herein, we report the synthesis and characterization of a nanosensor developed from a group of uniform materials based on organic salts (GUMBOS). This sensor is composed of three ionic species, namely, fluorescein, rhodamine B, and tetradecyltrihexyl phosphonium (P-66614) ions. Nanoparticles prepared from this three-component GUMBOS, termed nanoGUMBOS, exhibited increased fluorescence at two wavelengths with increases in pH values. The ratio of fluorescence emission corresponding to FL and RhB components of these nanoGUMBOS also changed with pH, allowing ratiometric analysis of pH through fluorescence measurements. Peak ratios were significantly different at pH 5 and pH 7, indicating potential applications of this nanomaterial as a cancer diagnostic tool. In this regard, in vitro fluorescence microscopy was employed to image cancerous and normal breast cells incubated with nanoGUMBOS. Fluorescence imaging of cancer cells showed higher uptake of these nanoGUMBOS and more pervasive fluorescence intensity in comparison with normal cells. Thus, the synthesized novel nanomaterial shows a great potential for rapid visual imaging of cancer cells

    Impact of Principals' Managerial Roles Under School-based Management on School Improvement at Urban Secondary Schools of Bangladesh

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    This article aims al observing the relationship between principals' managerial roles and the improvement of schools and the impacts of principals' managerial roles toward school improvement based on the school-based management. This research uses 127 principals and 694 teachers of urban secondary schools of Bangladesh as the sample. Schools are becoming better when the principals give more emphasizing on strategic plan, supportive and comprehensive roles but less emphasizing on shared decision making. The findings of this study offer valuable information for policy makers and educational managers, especially the principals and teachers. Key words: Principals managerial roles, school-based management, teachers' Professional development activities, school improvement &nbsp

    Infrared Lightcurves of Near Earth Objects

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    We present lightcurves and derive periods and amplitudes for a subset of 38 near earth objects (NEOs) observed at 4.5 microns with the IRAC camera on the the Spitzer Space Telescope, many of them having no previously reported rotation periods. This subset was chosen from about 1800 IRAC NEO observations as having obvious periodicity and significant amplitude. For objects where the period observed did not sample the full rotational period, we derived lower limits to these parameters based on sinusoidal fits. Lightcurve durations ranged from 42 to 544 minutes, with derived periods from 16 to 400 minutes. We discuss the effects of lightcurve variations on the thermal modeling used to derive diameters and albedos from Spitzer photometry. We find that both diameters and albedos derived from the lightcurve maxima and minima agree with our previously published results, even for extreme objects, showing the conservative nature of the thermal model uncertainties. We also evaluate the NEO rotation rates, sizes, and their cohesive strengths.Comment: 16 pages, 4 figures, 3 tables, to appear in the Astrophysical Journal Supplement Serie

    Establishing the Effects of Quality in Early Childhood: Comparing Evidence from England

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    This is the final version. Available from Early Education via the URL in this record.This occasional paper examines the robustness of a paper published by Blanden, Hansen and McNally in February 2017 which sought to investigate the effects of quality within early education and care settings in England (Quality in Early Years Settings and Children's School Achievement, CEP Discussion Paper 1468, The London School of Economics). The authors question the validity of the conclusions reached by Blanden et al about the impact of quality in early childhood education in England

    Ultrafast and nonlinear spectroscopy of brilliant green-based nanoGUMBOS with enhanced near-infrared emission

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    The synthesis, characterization, ultrafast dynamics, and nonlinear spectroscopy of 30 nm nanospheres of brilliant greenā€“bis(pentafluoroethylsulfonyl)imide ([BG][BETI]) in water are reported. These thermally stable nanoparticles are derived from a group of uniform materials based on organic salts (nanoGUMBOS) that exhibit enhanced near-infrared emission compared with the molecular dye in water. The examination of ultrafast transient absorption spectroscopy results reveals that the overall excited-state relaxation lifetimes of [BG][BETI] nanoGUMBOS are longer than the brilliant green molecular dye in water due to steric hindrance of the torsional degrees of freedom of the phenyl rings around the central carbon. Furthermore, the second harmonic generation signal of [BG][BETI] nanoGUMBOS is enhanced by approximately 7 times and 23 times as compared with colloidal gold nanoparticles of the same size and the brilliant green molecular dye in water, respectively. A very clear third harmonic generation signal is observed from the [BG][BETI] nanoGUMBOS but not from either the molecular dye or the gold nanoparticles. Overall, these results show that [BG][BETI] nanoGUMBOS exhibit altered ultrafast and nonlinear spectroscopy that is beneficial for various applications including nonlinear imaging probes, biomedical imaging, and molecular sensing
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