1,721,095 research outputs found
Efficient Method of Fabricating Polymeric Solar Cells in Multilayered Configuration Using Electrospray
Full text linkElectrospray deposition (ESD) for the fabrication of multilayered (ML) bulk heterojunction polymeric solar cells via direct/inverted configurations was investigated. The active layer heterojunction (P3HT/PCBM) is deposited both in single and multilayered architectures. In ML configuration, the P3HT/PCBM blend film is sandwiched between thin donor (P3HT) and acceptor (PCBM) layers. In ZnO-based inverted solar cells, ZnO film synthesized by sol-gel process was deposited on ITO substrate using spin coatinng. Solar cells were fabricated via ESD and spin coating and the device's performance parameters were compared. Higher efficiency was obtained in the case of (ML) ESD device (direct structure). Post thermal treatment showed that ESD devices exhibit a power conversion efficiency (PCE) of 1.85% ML and 1.64% SL in direct structure while in the case of inverted structure PCEs of 1.30% ML and 0.82% SL were obtained as compared to 1.64% from the spin coated device at 120 degrees C. The ML ESD devices have shown an overall efficiency enhancement of 13% (direct) and 58% (inverted) over the single layer (SL) ESD devices. The enhanced performance in ML devices is because there is a spatially uninterrupted pathway to the charge carrier transport towards their respective electrodes
Pd catalysts supported on different hydrophilic or hydrophobic carbonaceous substrate for furfural and 5-(hydroxymethyl)-furfural hydrogenation in water
No full textWe hydrogenated furfural and 5-(hydroxymethyl)furfural (HMF) in water in
a reaction catalyzed by Pd nanoparticles on carbonaceous materials with
different morphology and hydrophobic degree. The different Pd catalysts
were prepared by dipping the carbonaceous material into a Pd-0
micro-emulsion. The catalyst support affected the catalytic
hydrogenation of furfural and HMF. By using micrometric active carbon
(AC) combined with cup-stacked carbon nanotubes (CSCNTs) and Pd0/2+
nanoparticles (Pd), we obtained a micro/nanostructured material
designated Pd/CSCNT-AC, which performed better than the other
carbonaceous materials containing similar Pd nanoparticle loading.
Pd/CSCNT-AC produced tetrahydrofurfuryl alcohol from furfural with
excellent selectivity (>99 %). Unlike Pd on hybrophobic spheroid
graphite or hydrophilic AC, Pd/CSCNT-AC hydrogenated both the C=O and
C=C double bonds of furfural and catalyzed HMF hydrogenation at the C=O
double bond more selectively: between 85 % and 99 % selectivity toward
2,5-dihydroxymethylfuran. We also investigated how temperature, hydrogen
pressure, and reaction time affected HMF hydrogenation in water.
Finally, Pd/CSCNT-AC was recycled several times without significant
catalytic activity loss
Electro-insertion of Mn2+ions into V2O5·: N H2O on MWCNTs coated carbon felt for binder-free Na+ion battery electrodes
Full text linkIn the present article, we report the electrochemical deposition of hydrated and amorphous V2O5·nH2O nanostructures and related Mn2+ cations insertion during anodic polarization. The hydrated phase was synthesized on hydrophilic carbon felt substrates coated by defective multiwall carbon nanotubes (MWCNTs). From the combined data of micro-Raman scattering and X-ray photoelectron spectroscopy (XPS), it was possible to see that the Mn2+ cations were intercalated into V2O5 under anodic polarization. When MnOOH is inserted between atomic bilayers of V2O5·nH2O (V5+), a 3D complex monoclinic-MnxV2O5 system arises. This novel method of Mn doping into V2O5·nH2O/MWCNT produces an amorphous MnxV2O5/MWCNT but without hydration. The resulting binder-free MnxV2O5/MWCNT/felt composite electrode provides remarkable Na+ reversible specific capacities of 400 mA h g-1 and 224 mA h g-1 in the 3.5-1.0 V and 3.5-1.5 V ranges, respectively, while the V2O5·nH2O/MWCNT/felt provides only 120 mA h g-1 between the smaller cut-off potential limits. The MnxV2O5/MWCNT nanostructures synthesis onto fibers of graphitic felt does not present a fading capacity during the polarization of 100 discharge/charge cycles
Structure properties of nanostructured Fe films grown on c(2x2)N/Cu(100) self organised surface
No full textThe growth of Fe on the c(2x2)N/Cu(100) surface was studied with XAFS assisted by LEED. Previous STM work had shown that atomic N on Cu(100) forms periodic arrays of c(2x2) N islands with a size of about 5x5 nm channelling the growth of Fe onto the clean Cu areas. From XAFS multishell analysis we describe the growth in terms of fcc phase with strong lattice distortion, deviation from the layer by layer growth, and presence of surface complex phases, some with different geometry. The differences between the Fe growth on the clean and N saturated Cu(100) surface are explained in terms of Fe-N atoms interaction, and we could obtain the adsorption geometry of Fe on N-saturated surface
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Does Alumina Coating Alter the Solid Permeable Interphase Dynamics in LiMn2O4 Cathodes?
Full text linkIt is well known that the Al2O3 coating of the LiMn2O4 cathodes leads to improvement of the performance of these electrodes. However, the effect of the coating on the fundamental processes occurring on the interface with the active material which results in the formation of the solid permeable interphase is yet to be investigated. These effects should be more pronounced in the first cycle when a dynamic interaction of the active material at high voltage with the electrolyte and binder leads to the formation of this passivation layer. Here, we present a detailed investigation of the solid permeable interphase formation in alumina-coated and uncoated LiMn2O4 electrodes using X-ray absorption spectroscopy and analysis on the electrodes at the predesigned charging/ discharging states. We demonstrate that the alumina coating leads to modification of the solid permeable layer and its dynamics. We also discuss the possible influences of interface modifications via coating on the battery performance
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