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Layek, R.K.,Uddin, Md.E.,Kim, N.H.,Tak Lau, A.K.,Lee, J.H. Elsevier Science Ltd 2017 Composites Part B, Engineering Vol.128 No.-
Nanocomposites of pluronic F127 modified reduced graphene oxide (PF127-rGO) with polyethylene glycol plasticize gum arabic (PGA) was prepared by evaporating an aqueous solution mixture of PF127-rGO and PGA. PF127-rGO was synthesized by the in-situ reduction of graphene oxide using hydrazine in presence of pluronic F127 and characterized by the Uv-Vis spectroscopy, transmission electron microscopy (TEM), wide angle x-ray scattering (WAXS), Fourier transforms infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and Raman spectroscopy. The Uv-Vis and Raman spectroscopy results indicate that pluronic F127 functionalization does not hamper the structure of rGO, and TEM image indicates, the pluronic F127 anchored rGO sheets remain exfoliated in diluted aqueous solution of PF127-rGO. WAXS, FTIR and TGA studies confirms the functionalization of rGO with pluronic F127. PF127-rGO 2.5, PF127-rGO 5 and PF127-rGO 7.5 nanocomposites were fabricated, where the numbers represent the weight percentage of PF127-rGO with respect to PGA. The composite films were characterized by field emission scanning electron microscopy (FESEM), FTIR, WAXS and mechanical property study. FESEM and WAXS studies show good dispersion of PF127-rGO sheets in the PGA matrix. The FTIR results indicate a significant interaction between functional groups of PF127-rGO and functional groups of PGA. PF127-rGO 7.5 shows a 124% increase of stress at break and 185% increase of Young's modulus compared to pure PGA.
Layek, Rama K.,Das, Ashok Kumar,Park, Min Jun,Kim, Nam Hoon,Lee, Joong Hee Elsevier 2015 Carbon Vol.81 No.-
<P><B>Abstract</B></P> <P>Sulfonated poly(ether-ether-ketone) functionalized graphene oxide (SPG)/poly(vinylidene fluoride) (PVDF) composites have been prepared by a solvent evaporation technique. The –SO<SUB>3</SUB>H group of SPG interact with the >CF<SUB>2</SUB> dipole of PVDF to integrate graphene uniformly into a PVDF matrix. The cross-sectional field emission scanning electron microscopy micrograph shows folded-chain lamella of spherulitic PVDF crystallites spread outwards from the growth center. The spherulitic crystallites decrease with the incorporation of SPG into the PVDF matrix and the composite containing 3wt.% SPG (SPG3) does not show spherulite, but fiber-like crystallites. Fourier transform infrared spectroscopy, wide angle X-ray scattering and differential scanning calorimetry (DSC) results suggest that piezoelectric β-polymorph formation begins with the incorporation of SPG into the PVDF matrix, and SPG3 shows the formation of the fully β-polymorph. DSC cooling curves show that SPG acts as an effective nucleating agent for the crystallization of PVDF. Study of the mechanical properties shows that there is a simultaneous enhancement of the stress and the strain at break indicating the enhanced toughness of the PVDF composites compared to pure PVDF. Young’s modulus increases 160% and the oxygen permeability coefficient decreases by 91% in the SPG3 composite film compared to pure PVDF.</P>
Layek Ujjwal,Das Uday,Karmakar Prakash 한국응용곤충학회 2022 Journal of Asia-Pacific Entomology Vol.25 No.2
Honey bees and stingless bees are generalist visitors of several wild and cultivated plants. They forage with a high degree of floral fidelity and thereby help in the pollination services of those plants. We hypothesized that pollination efficiency might be influenced by flowering phenology, floral characteristics, and resource collection modes of the worker bees. In this paper, we surveyed the foraging strategies of honey bees (Apis cerana, Apis dorsata, and Apis florea) and stingless bees (Tetragonula iridipennis) concerning their pollination efficiencies. Bees showed different resource gathering strategies, including legitimate (helping in pollination as mixed foragers and specialized foragers) and illegitimate (serving as nectar robbers and pollen thieves) types of flower visitation patterns. Foraging strategies are influenced by the shape of flowers, the timing of the visitation, floral richness, and bee species. Honey bees and stingless bees mainly acted as legitimate visitors in most plants studied. Sometimes honey bees served as nectar robbers in tubular flowers and stingless bees as pollen thieves in largesized flowers. Among the legitimate categories, mixed foragers have a comparatively lower flower visitation rate than the specialized nectar and pollen foragers. However, mixed foragers have greater abundance and higher values of the single-visit pollination efficiency index (PEi) than nectar and pollen foragers. The value of the combined parameter ‘importance in pollination (PI)’ was thus higher in mixed foragers than in nectar and pollen foragers.
Efficient Screen Splitting Methods - A Case Study in Block-wise Motion Detection
( Md. Abu Layek ),( Taechoong Chung ),( Eui-nam Huh ) 한국인터넷정보학회 2016 KSII Transactions on Internet and Information Syst Vol.10 No.10
Screen splitting is one of the fundamental tasks in different methods including video and image compression, screen classification, screen content coding and the like. These methods in turn support various applications in data communications, remote screen sharing, remote desktop delivery to assist teaching-learning, telemedicine, Desktop as a Service etc. In the literature we find systems requiring splitting assumes a fixed size split that do not change dynamically, also there is no analysis why that split is chosen in terms of performance. By doing mathematical analysis this paper first finds the efficient splitting schemes that can be easily automated to make a system adaptive. Thereafter, taking the screen motion detection as a case study, it demonstrates the effects of various splitting methods on motion detection performance. The simulation results clearly shows how classification performances varies with different splitting which will facilitate to choose the best splitting for a specific application scenario as well as making the system adaptive by providing dynamic splitting.