28,938 research outputs found

    Curricular and instructional influences on early literacy attainment: evidence from Beijing, Hong Kong and Singapore

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    This study considered curricular and instructional influences on early Chinese literacy attainment in Beijing, Hong Kong and Singapore. The participants included 198 preā€school children, their teachers and parents. Children were administered the Preā€school and Primary Chinese Literacy Scale at the age of either two or three years, and again one year later. Teachers were asked to report on their beliefs and practices related to literacy education, and classroom observations were conducted to determine the extent to which directives issued by the Beijing, Hong Kong and Singapore governments were implemented. Investigation showed that there were marked differences across the societies in curriculum guidelines and approaches to literacy teaching. Results indicated that by the age of four, preā€schoolers in Hong Kong and Singapore had significantly better Chinese literacy attainment than those in Beijing. Although age was the best predictor of attainment, location, teachersā€™ qualifications and classroom experience also significantly contributed to childrenā€™s literacy attainment.postprin

    Quenching of fluorescence of aromatic molecules by graphene due to electron transfer

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    Investigations on the fluorescence quenching of graphene have been carried out with two organic donor molecules, pyrene butanaoic acid succinimidyl ester (PyBS, I) and oligo(p-phenylenevinylene) methyl ester (OPV-ester, II). Absorption and photoluminescence spectra of I and II recorded in mixture with increasing the concentrations of graphene showed no change in the former, but remarkable quenching of fluorescence. The property of graphene to quench fluorescence of these aromatic molecules is shown to be associated with photo-induced electron transfer, on the basis of fluorescence decay and time-resolved transient absorption spectroscopic measurements.Comment: 18 pages, 6 figure

    Novel magnetic properties of graphene: Presence of both ferromagnetic and antiferromagnetic features and other aspects

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    Investigations of the magnetic properties of graphenes prepared by different methods reveal that dominant ferromagnetic interactions coexist along with antiferromagnetic interactions in all the samples. Thus, all the graphene samples exhibit room-temperature magnetic hysteresis. The magnetic properties depend on the number of layers and the sample area, small values of both favoring larger magnetization. Molecular charge-transfer affects the magnetic properties of graphene, interaction with a donor molecule such as tetrathiafulvalene having greater effect than an electron-withdrawing molecule such as tetracyanoethyleneComment: 16 pges, 5 figure

    The performance of modified jatropha-based nanofluid during turning process

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    The industry's extensive use of petroleum-based metalworking fluid (MWF) harms the environment and humans. The production of bio-based MWF, especially from crude jatropha oil (CJO), has therefore taken numerous initiatives. This aimed to formulate newly modified jatropha oil (MJO) with the addition of 0.05wt.% hBN and 0.05wt.% MoS2 as the nanofluid for MWF. The performance of the nanofluids was determined through the turning process in terms of cutting temperature, workpiece surface roughness, tool life and tool wear of the tool lubricated by the nanofluids. The performance of the nanofluid samples was compared with the synthetic ester (SE). From the results, after conducted 100mm axial cutting length MJO+hBN+MoS2 recorded the lowest in cutting temperature and surface roughness compared to all samples. The result shows that MJO+hBN+MoS2 has longer tool life (6500mm) compared to SE (6000mm). Abrasion and adhesion were observed as the dominant tool wear mechanism. In conclusion, MJO+hBN+MoS2 shows better machining performance and has the potential to be an environmentally friendly metalworking fluid
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