1,720,959 research outputs found
Substituting TiCl4-carbon nanohorn interfaces for dye-sensitized solar cells
No full textAn easy-to-implement strategy to introduce carbon nanohorns as interlayers in the photoelectrode of a dye-sensitized solar cell without affecting its overall performance is presented. This provides a clean, easy, and ecofriendly alternative to achieve highly efficient cells
Carbon nanohorn-based electrolyte for dye-sensitized solar cells
No full textFor the first time, carbon nanohorns were implemented into solid-state electrolytes for highly efficient solid-state and quasi-solid-state DSSCs. They feature an effective catalytic behavior towards the reduction of I3 - and enhance the I3 - diffusivity in the electrolyte. In a final device, solar cells with 7.84% efficiency at room temperature were achieved. As a matter of fact, this is the highest reported efficiency for nanocarbon-based electrolytes up to date
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
Implementierung kohlenstoffreicher Farbstoffe und einwandiger Kohlenstoffnanohörner in Farbstoffsensibiliserte Solarzellen
Full text linkGiven the emerging field of nanostructured electronic devices, a multitude of different concepts for further improvements is discussed in the scientific community. Especially in the field of solar cells, vast varieties of approaches for improvements are proposed. However, in some cases the impact on the environment during the assembly procedure is left aside.
The thrust of this thesis was to tackle the concepts of improving the performance, long-term stability, and ecological footprint of dye-sensitized solar cells (DSSCs). This was accomplished by employing novel, carbon-rich photosensitizers and implementing single-walled carbon nanohorns (SWCNHs) into different parts of TiO2-based DSSCs.
To this end, two sensitizing schemes were adsorbed onto mesoporous TiO2 networks, namely i) benzoporphyrins (BPs) were introduced as a new dye class for DSSCs, and ii) carbon nanodots (CNDs) were implemented as novel nanocarbon photosensitizer for low-cost solar cell applications. The former exhibits a unique adsorption behavior depending on the metalation of the porphyrin unit, the TiO2-particle size, and the nature of the solvent. This enabled a selective adsorption onto different parts of the TiO2-network. As a consequence, unfavorable energy transfer processes between the two different chromophores could be circumvented.
In contrast to the conventional dye-TiO2 binding scheme, novel CNDs were tested as potential replacement for complex and, as a consequence, expensive dyes, which are synthesized via multi-step procedures or contain heavy metal elements. CNDs are, however, synthesized in a one-step procedure in water. With this approach, the costs of the photosensitizer and the environmental impact of the overall process of DSSC assembly could be minimized.
As another strategy, SWCNHs were implemented into different parts of the DSSC. Firstly, SWCNHs were employed as replacement for the standard TiCl4 treatment, which constitutes a health hazard and represents an increasing production of inorganic waste due to its fast degradation. To this end, nanometer-sized buffer layers of SWCNHs were deposited onto fluorine-doped tin oxide (FTO) transparent glass slides. A similar efficiency compared to the TiCl4-treated DSSCs could prove that SWCNHs are a sound alternative to TiCl4. Secondly, SWCNH layers were tested to replace the rare earth element Platinum (Pt), which is normally used as a counter electrode (CE) material. Due to their excellent catalytic activity towards electrolyte regeneration, SWCNH-based CEs featured similar efficiencies compared to Pt-based ones. Furthermore, no high temperature sintering of the SWCNH-based films was necessary, which facilitates the assembly process and lowers the energy footprint for the device assembly. Finally, since SWCNHs feature remarkable properties, such as their catalytic reduction of I3- to I-, and their good miscibility with common organic solvents and ionic liquids, SWCNH-based solid- and quasi solid-state ionic electrolytes were tested in DSSCs. Implementing SWCNHs introduced a higher ionic conductivity and a catalytically activity into the electrolyte, which improved both the performance and long-term stability of DSSCs.
For investigating the novel photosensitizer schemes and SWCNH-based DSSCs, a broad range of electrochemical, spectroscopic, and microscopic techniques was employed. In particular, current density vs. voltage (J-V) measurements, electrochemical impedance spectroscopy (EIS), incident photon-to-current efficiency (IPCE), and Raman experiments were at the forefront for characterizing the dynamic processes involved in DSSCs. Several techniques such as steady-state absorption and fluorescence spectroscopy, time-resolved femtosecond laser absorption spectroscopy, X-Ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscopy (TEM) complemented the investigations in order to unravel the mechanisms and working principles involved in SWCNH-based DSSCs
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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