1,720,969 research outputs found
Towards Environmentally Benign Wastewater Treatment - Photocatalytic Study of Degradation of Industrial Dyes
Full text linkPollution created by textile dyeing operations attracts significant attention because an effluent containing a complex mixture of coloured and potentially toxic compounds can be released with the discharged water. Developing dyes and dyeing conditions to reduce the amount of residual dye contained in any effluent has been one of many approaches to minimise this environmental impact. However, the presence of coloured discharge cannot be totally eliminated using only this strategy. Thus, development of efficient post-dyeing wastewater treatment methods capable of removing coloured products from the water is of paramount importance.
TiO2-mediated photocatalytic degradation of organic dye molecules via oxidation is the focus of the study reported in this thesis. TiO₂ significantly increases the rate of photodegradation of a wide range of organic dyes under mild operating conditions, and is able to mineralise a wide spectrum of organic contaminants. TiO₂ is also one of the very few substances appropriate for the industrial applications.
One of primary aims of this thesis is to test the hypothesis that augmenting standard TiO₂ photocatalysts with Au nanoparticles could increase performance of a catalyst, while immobilizing TiO₂ on SiO₂ support may improve the cost of the process efficiency, i.e. more photocatalytic degradation per particle of TiO₂. Combining TiO₂ doped with gold nanoparticles on SiO₂ support has the potential to provide the highest photocatalytic ability at the lowest cost.
The first half of the thesis is concerned with establishing and optimizing experimental conditions for monitoring photodegradation via UV-Visible spectroscopy. Effects of various conditions such as temperature, sequence of addition of reagents, exposure to light vs. experiments in dark, sampling methods, and the use of quenching agent were examined.
The main conclusions from this study are that light-induced photodegradation using titanium dioxide nanoparticles catalysts is comparatively more efficient than purely chemical catalytic (e.g. non-light mediated) degradation, even if the latter is performed at elevated temperature. Further, the rate of dye degradation is affected considerably by the parameters of the system.
The degradation rate depends strongly on the pH of the solution, due to charges on both the catalyst surface and in the dye. In general, at pH ≤ 6.8, which is the zero charge point for TiO₂, reactions proceeded faster than those at higher pH. Six dyes from four different classes of dyes used in industry were used in this study, and all showed different photodegradation behaviour.
The second half of thesis tests the photocatalytic abilities of various TiO₂-based catalysts: pure TiO₂ (commercial and custom-made in our laboratory), TiO₂-supported gold nanoparticles (Au/TiO₂), SiO₂-supported TiO₂ (TiO₂/SiO₂), and SiO₂-supported Au/TiO₂. The best photocatalytic performance was observed for the custom-made TiO₂ code-named as e-TiO₂, which was synthesized using the sol-gel method in dry ethanol. TiO₂-supported Au55 nanoparticles showed a similar level of catalytic ability but are significantly more expensive. It was observed that dye adsorption played a significant role in the case of SiO₂-immobilized photocatalysts
Fully integrated rechargeable pedot : PSS energy storage device for smart textiles applications
Full text linkEnergievoorziening en opslag is een belangrijk onderdeel van slimme textielsystemen omdat het de vereiste energie levert om het systeem van stroom te voorzien. Deze thesis is een voortzetting van een vorige studie, en was vooral gericht op het verbeteren van de prestaties en het uiterlijk van het onderdeel door de verbetering van de fabricagetechnieken en het onderzoeken van het werkingsprincipe en mechanisme van de TESD component. De ontwikkelde component transformeerde, van de vroegste naar de nieuwste vorm, via vier verschillende en verbeterde fabricagemethoden die de prestaties en het uiterlijk van het apparaat verbeterden. De component met de naam TESD 1.2 THL is de beste vorm van ons textiel-energieopslagonderdeel tot nu toe. Uit de studie van het mechanisme werd complex gedrag van ionische en elektronische oorsprong waargenomen in het grensvlakgebied van het gebruikte geleidende polymeer, PEDOT:PSS. Een grotere verhouding van PEDOT tot PSS, met een hogere soortelijke weerstand, is wenselijk, maar verder onderzoek is nodig. Weerstand tegen wassen van het apparaat en het conceptontwerp voor de integratie van onze TESD in kleding werd ook uitgewerkt. Over het geheel genomen lieten de resultaten veelbelovend potentieel zien voor de verdere ontwikkeling van een op textiel gebaseerd energieopslagapparaat
Charge-discharge characteristics of textile energy storage devices having different PEDOT:PSS ratios and conductive Yarns configuration
Full text linkConductive polymer PEDOT:PSS, sandwiched between two conductive yarns, has been proven to have capacitive behavior in our textile energy storage devices. Full understanding of its underlying mechanism is still intriguing. The effect of the PEDOT to PSS ratio and the configuration of the electrode yarns are the focus of this study. Three commercial PEDOT:PSS yarns, Clevios P-VP-AI-4083, Ossila AI 4083, and Orgacon ICP 1050, as well as stainless steel and silver-coated polybenzoxazole (Ag/PBO) yarns, in various combinations, were used as solid electrolytes and electrodes, respectively. Analyses with NMR, ICP-OES, TGA, and resistivity measurement were employed to characterize the PEDOT:PSS. The device charge-discharge performance was measured by the Arduino microcontroller. Clevios and Ossila were found to have identical characteristics with a similar ratio, that is, 1:5.26, hence a higher resistivity of 1000 Ω.cm, while Orgacon had a lower PEDOT to PSS ratio, that is, 1:4.65, with a lower resistivity of 0.25–1 Ω.cm. The thermal stability of PEDOT:PSS up to 250 °C was proven. Devices with PEDOT:PSS having lower conductivity, such as Clevios P-VP-AI-4083 or Ossila AI 4083, showed capacitive behavior. For a better charge-discharge profile, it is also suggested that the PEDOT to electrode resistance should be low. These results led to a conclusion that a larger ratio of PEDOT to PSS, having higher resistivity, is more desirable, but further research is needed
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
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
KARAKTERSITIK ZAT WARNA TERMOKROMIK TOUCH ACTIVATED DAN HASIL PENCAPANNYA PADA KAIN KAPAS
Full text linkZat warna termokromik, yang dikategorikan sebagai salah satu jenis smart dyes, dikembangkan terutama untuk memperoleh aspek-aspek fungsional pada bahan tekstil melalui kemampuannya untuk merespon rangsangan tertentu. Zat warna termokromik jenis touch activated dapat memudar warnanya ketika disentuh (pada suhu 29 o C / 84 o F). Kebutuhan untuk melengkapi informasi mengenai aspek-aspek teknis aplikasi dan karakteristik zat warna termokromik komersial jenis touch activated mendorong dilakukannya penelitian ini. Penelitian dilakukan dengan mengaplikasikan zat warna tersebut pada kain kapas dengan metode pencapan. Perbandingan zat warna:binder sebesar 1:1 dan diikuti dengan fiksasi pada temperatur ruang selama 30 menit. Hasil analisa FTIR menunjukkan bahwa zat warna tersusun atas senyawa organik aromatik dengan beberapa puncak serapan yang dominan seperti C=O, C=C, dll. Kain hasil pencapan memudar setelah menerima rangsangan sentuhan dan bersifat reversibel. Perbedaan usia dan jenis kelamin responden yang melakukan stimulus sentuhan tidak berpengaruh secara signifikan pada waktu retensi respon perubahan warna kembali. Ketahanan luntur warna kain hasil pencapan terhadap pencucian cukup rendah (nilai staining scale mencapai 2-3). Zat warna termokromik jenis touch activated lebih tepat digunakan untuk kepentingan teknis dan estetis pada aplikasi di bidang garmen atau untuk aplikasi sensor dan sejenisnya
- …
