1,726,907 research outputs found
Rh ve Ru katkılı NiO/CeO₂/ZrO₂ katalizörlerinin sentezi, karakterizasyonu ve seçici CO metanlaşması için aktivitelerinin incelenmesi
No full textBu çalışmada birlikte çöktürme yöntemi ve yüzey aktif madde destekli birlikte çöktürme yöntemi ile hazırlanmış Rh ve Ru katkılı NiO/CeO₂/ZrO₂ katalizörleri üzerinden CO ve seçici CO metanlaşması reaksiyonları gerçekleştirildi. Katalizörler 500 °C de kalsine edilmiştir. Katalizörlerin karakteristik özelliklerini belirlemek için N2 fizisorpsiyon çalışmaları, X-ışını kırınımı desenleri analizleri ve taramalı elektron mikroskopisi (SEM) kullanıldı. X-ışını kırınımı desenleri analizleri ile katalizörlerde belirgin şekilde NiO, CeO₂, ZrO₂ fazlarına ait pikler gözlenmiştir. En yüksek yüzey alanı Yüzey aktif madde destekli birlikte çöktürme yöntemiyle hazırlanan %5 Ru katkılı NiO/CeO₂/ZrO₂ katalizöründen elde edilmiştir. Katalizörlerin katalitik aktiviteleri CO metanlaşması ve seçici CO metanlaşması için yapılmıştır. CO metanlaşma deneylerinde gaz karışımı olarak 1% CO, %50 H2 ve kalanı He olan besleme gaz karışımı kullanılmıştır. CO' in seçici oksidasyonu için katalitik aktivite çalışmalarında ise %1 CO, % 25 CO2, % 50 H2 ve kalanı He olan besleme gaz karışımı kullanılmıştır. CO metanlaşma reaksiyonları sonucunda en iyi aktivite sonucu yüzey aktif madde destekli birlikte çöktürme yöntemiyle hazırlanmış %4 Ru katkılı NiO/CeO₂/ZrO₂ katalizöründen elde dilmiştir. %4 v Ru katkılı NiO/CeO₂/ZrO₂ katalizörü 184,2 °C de %50 CO dönüşümü verirken 225 °C den sonra %100 dönüşüm vermiştir. Seçici CO metanlaşmasında sonuçlarına genel olarak bakıldığında 300-400 oC aralığında CH4 dönüşümünde ciddi bir artış gözlenmiştir. Buna paralel olarak H2 dönüşümünde de artış belirlenmiştir. CO bileşiminde ise bu sıcaklık aralığında hızlı bir azalma gözlenmiştir. Bu aralıktan sonra RWSGR' nin etkisiyle CH4 dönüşümünde hızlı bir düşüş belirlenmiştir.In this study, CO and selective CO methanation reactions were made over the Rh and Ru mixed NiO/CeO₂/ZrO₂. The catalysts were both was prepared by co-precipitation and surafacant assisted co-precipitation method. All catalyts were calcined at 500 °C. The characteristic properties of the catalysts were determined by using the X-ray diffraction pattern , scanning electron microscopy (SEM) and , N2-physisorption measurements. According to the XRD studies, NiO/CeO₂/ZrO₂ phases were obtained prominently from the catalyts. The highest surface area was obtained from the mixed NiO/CeO₂/ZrO catalyst %5 Ru that was prepared by surafacant assisted co-precipitation method. The CO methanation and selective CO methanation experiments were made in order to NiO/CeO2/ZrO2 calatytic activities. The feed gas for CO methanation experiments had a composition of %1 CO, %50H2 and remaining He. The catalytic activities of the catalysts were determined for the selective CO oxidation reaction in H2 rich gas stream in which the compositions are 10/90 CO/He, %100 CO2, %100 H2, %100 He. The best activity for the CO methanation reaction was obtained from %4 Ru mixed NiO/CeO₂/ZrO₂ vii prepared by surafacant assisted co-precipitation method. This catalyst gave 50% CO conversion at 184,2 °C and 100% CO conversation at 225 °C. CH4 and H2 conversation increased prominently at 300-400 °C at selective of CO methanation reaction. There was a sharp decrease in CO composition at this temperatures. Later this temperrature range, Depending on RWSGR, a rapid decrease in CH4 conversation was observed after this temperature range
Synthesis of Rh and Ru mixed NiO/CeO₂/ZrO₂ catalysts, characterization and the investigation of activities for selective CO methanation
No full textBu çalışmada birlikte çöktürme yöntemi ve yüzey aktif madde destekli birlikte çöktürme yöntemi ile hazırlanmış Rh ve Ru katkılı NiO/CeO₂/ZrO₂ katalizörleri üzerinden CO ve seçici CO metanlaşması reaksiyonları gerçekleştirildi. Katalizörler 500 °C de kalsine edilmiştir. Katalizörlerin karakteristik özelliklerini belirlemek için N2 fizisorpsiyon çalışmaları, X-ışını kırınımı desenleri analizleri ve taramalı elektron mikroskopisi (SEM) kullanıldı.
X-ışını kırınımı desenleri analizleri ile katalizörlerde belirgin şekilde NiO, CeO₂, ZrO₂ fazlarına ait pikler gözlenmiştir. En yüksek yüzey alanı Yüzey aktif madde destekli birlikte çöktürme yöntemiyle hazırlanan %5 Ru katkılı NiO/CeO₂/ZrO₂ katalizöründen elde edilmiştir. Katalizörlerin katalitik aktiviteleri CO metanlaşması ve seçici CO metanlaşması için yapılmıştır. CO metanlaşma deneylerinde gaz karışımı olarak 1% CO, %50 H2 ve kalanı He olan besleme gaz karışımı kullanılmıştır. CO' in seçici oksidasyonu için katalitik aktivite çalışmalarında ise %1 CO, % 25 CO2, % 50 H2 ve kalanı He olan besleme gaz karışımı kullanılmıştır. CO metanlaşma reaksiyonları sonucunda en iyi aktivite sonucu yüzey aktif madde destekli birlikte çöktürme yöntemiyle hazırlanmış %4 Ru katkılı NiO/CeO₂/ZrO₂ katalizöründen elde dilmiştir. %4
v
Ru katkılı NiO/CeO₂/ZrO₂ katalizörü 184,2 °C de %50 CO dönüşümü verirken 225 °C den sonra %100 dönüşüm vermiştir.
Seçici CO metanlaşmasında sonuçlarına genel olarak bakıldığında 300-400 oC aralığında CH4 dönüşümünde ciddi bir artış gözlenmiştir. Buna paralel olarak H2 dönüşümünde de artış belirlenmiştir. CO bileşiminde ise bu sıcaklık aralığında hızlı bir azalma gözlenmiştir. Bu aralıktan sonra RWSGR' nin etkisiyle CH4 dönüşümünde hızlı bir düşüş belirlenmiştir.In this study, CO and selective CO methanation reactions were made over the Rh and Ru mixed NiO/CeO₂/ZrO₂. The catalysts were both was prepared by co-precipitation and surafacant assisted co-precipitation method. All catalyts were calcined at 500 °C. The characteristic properties of the catalysts were determined by using the X-ray diffraction pattern , scanning electron microscopy (SEM) and , N2-physisorption measurements.
According to the XRD studies, NiO/CeO₂/ZrO₂ phases were obtained prominently from the catalyts. The highest surface area was obtained from the mixed NiO/CeO₂/ZrO catalyst %5 Ru that was prepared by surafacant assisted co-precipitation method. The CO methanation and selective CO methanation experiments were made in order to NiO/CeO2/ZrO2 calatytic activities. The feed gas for CO methanation experiments had a composition of %1 CO, %50H2 and remaining He. The catalytic activities of the catalysts were determined for the selective CO oxidation reaction in H2 rich gas stream in which the compositions are 10/90 CO/He, %100 CO2, %100 H2, %100 He. The best activity for the CO methanation reaction was obtained from %4 Ru mixed NiO/CeO₂/ZrO₂
vii
prepared by surafacant assisted co-precipitation method. This catalyst gave 50% CO conversion at 184,2 °C and 100% CO conversation at 225 °C.
CH4 and H2 conversation increased prominently at 300-400 °C at selective of CO methanation reaction. There was a sharp decrease in CO composition at this temperatures. Later this temperrature range, Depending on RWSGR, a rapid decrease in CH4 conversation was observed after this temperature range
Wood ash suspensions in water as a solvent in CO₂ absorption processes biogas upgrading applications
No full textA implantação de um projeto de utilização do biogás como fonte renovável de energia em pequena escala, requer a pesquisa de processos de limpeza do biogás e de captura de CO₂, que contemplem os aspectos de sustentabilidade e de uma tecnologia que possa ser aplicada em pequenas instalações. Visando uma matéria-prima de baixo custo, o presente estudo utilizou cinzas de madeira como fonte de carbonatos para a absorção de CO₂, buscando usar um resíduo como solvente, para melhorar a eficiência energética de um combustível de fonte renovável. As cinzas de madeira, geralmente possuem elevados valores de pH e são compostas, principalmente, por óxidos de potássio, magnésio e cálcio. O objetivo deste trabalho foi estudar a absorção do CO₂ por soluções de carbonatos totais e solúveis provenientes de suspensões de cinzas de madeira em água, através de experimentos realizados em escala laboratorial e de simulação empregando como base o carbonato de cálcio equivalente. A célula de absorção é uma ferramenta eficaz para estimar a capacidade de reter CO₂ em um solvente desconhecido, à temperatura e pressão ambientes. Os carbonatos solúveis extraídos das cinzas de madeira, com 5,33 % de CCE, têm a capacidade de absorver, em média, 0,77 g de CO₂ por 100g de cinzas de madeira, em condições ambientes. Já as cinzas com 89,74 % de CCE absorveram, em média, 12,6 g de CO₂ por 100 g de cinzas de madeira, em condições ambientes. Assim, podem-se caracterizar as cinzas de madeira como um potencial solvente para a absorção de CO₂. A simulação de uma coluna de pratos perfurados, equivalente a uma coluna de pratos tipo chicana, através da tranferência da sua área de cortina, foi satisfatória.The implementation of a project for the use of biogas as a renewable source of energy on a small scale, requires research into cleaning the biogas and CO₂ capture processes, with sustainability and technology that can be applied in small installations. The present study uses wood ash as a source of carbonate for CO₂ absorption, seeking to use waste as a solvent, to improve the energy efficiency of a renewable fuel source. Wood ash is a solid waste with organic and inorganic components, obtained from combustion of wood. Its chemical composition may vary according the tree species, soil type, climate and combustion characteristics. The resulting suspension of ash in water has typical properties of high pH values and high concentrations of carbonates. The aim of this work is to study the absorption of CO₂ by solutions of total carbonates and soluble carbonates from suspensions of wood ashes in water, through experiments conducted in laboratory scale and employing simulation based on the calcium carbonate equivalent. A simple device was successfully developed that could predict the absorption potential for CO₂ of a solvent with unknown composition in ambient conditions of temperature and pressure. The soluble carbonates had 5.33% of calcium carbonate equivalence absorbed 0.77g CO₂ / 100g ashes, at approx. 700 mmHg and 20°C. Ashes with 89.74% of calcium carbonate equivalence absorbed 12.6g CO₂ / 100g ashes, at approx. 700 mmHg and 20°C. This study suggests that wood fuel ashes are a potential solvent for CO₂ absorption. The simulation of an equivalent column of perforated plates to a column of baffle plates, through the transfer of its area curtain was satisfactory
Risky business: how elevated CO₂ and energetic resources affect anti-predator behaviour in a reef fish
No full text<p>This dataset is available as a spreadsheet in MS Excel (.xlsx) and Open Document formats (.ods)</p><p>This data set contains trial/experimental measurements and water chemistry data. Units are:</p><ul><li>Length - mm</li><li>Weight - g</li><li>Parent treatment and CO₂ treatment - pCO₂</li></ul><p>Abstract [Related Publication]: The appropriate behavioural response to predation risk is critical to survival; however, behavioural responses can be subjected to trade-offs. For example, individuals may engage in riskier foraging behaviour to secure sufficient energy if resources are limited. Additionally, elevated CO₂ can influence foraging and antipredator behaviour of marine organisms. Yet, how the availability of energetic resources may influence antipredator behaviour in an elevated CO₂ environment is unknown. We tested the effects of food ration (low and high: 4% and 8%of body weight per day, respectively) on antipredator behaviour at ambient (489 μatm) and elevated (1022 μatm) CO₂ in juvenile Amphiprion percula at 50 d post-hatching. Juveniles were from parents held at either ambient or elevated CO₂, as parental exposure can influence phenotypic response in offspring. Antipredator behaviour was severely impaired by elevated CO₂, with juveniles reared at elevated CO₂ exhibiting no change in feeding rate in the presence of the predator cue compared with a >67% reduction in feeding rate in ambient CO₂ fish. By contrast, food ration had a minor effect on the change in feeding rate in response to the predator cue, with only a 2.3% difference between high and low food ration fish. The effect of elevated CO₂ on antipredator behaviour of juveniles was not influenced by food ration. Parental exposure to elevated CO₂ influenced the baseline feeding rate and exhibited a small carry-over effect in elevatedCO₂ juveniles. These results suggest that reef fish could exhibit riskier behaviour at elevated CO₂ levels, regardless of the energetic resources available.</p><p>The full methodology is available in the publication shown in the Related Publications link below.</p><p> </p>
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
Peklaj, C. (Ed.) (2010), Teacher Competencies and Educational Goals, Aachen, Sahaker Verlag, 171 p., ISBN 978-3-8322-9661-2
No full textPeklaj, C. (Ed.) (2010), Teacher Competencies and Educational Goals, Aachen: Sahaker Verlag, 171 p., ISBN 978-3-8322-9661-
Sensing mixtures of H₂, CH₄ and CO through an array of chemiresistors.
No full textA determinação de cada espécie que compõe uma mistura gasosa tem sido alvo de muitas pesquisas. Existem equipamentos para tal finalidade tais como, cromatografia gasosa, espectroscopia de infravermelho e sensores. A fim de viabilizar uma aplicação de baixo custo para a determinação da concentração de espécies em uma mistura gasosa, neste trabalho, é proposto um aparato para sensoriamento de H₂, CH₄ e CO encontrados em gases combustíveis. O sensoriamento é efetuado por quimioresistores de SnO₂ comercialmente disponíveis. O aparato consiste de um sistema de coleta da mistura gasosa e de sua diluição antes de seguir com a análise feita pelos sensores, obedecendo aos requisitos de segurança contra explosões. O aparato foi submetido a 125 diferentes misturas oriundas da combinação das concentrações de 0, 200, 800, 1500 e 2000 ppm de cada espécie gasosa utilizando o nitrogênio (99,999%) como gás de arraste. As amostragens foram avaliadas sob dois diferentes métodos de recuperação dos sensores: forçado e natural. Através dos resultados experimentais obtidos, foi observado que: a sensibilidade cruzada dos sensores de CO e de CH₄ é bastante elevada enquanto que o sensor de H₂ apresentou maior seletividade e, o método de recuperação natural apresentou melhores resultados em função da estabilidade térmica do sistema. Uma rede neural artificial foi desenvolvida e treinada com o objetivo de superar o problema das sensibilidades cruzadas. Os resultados obtidos pela rede neural são promissores e apresentaram erro máximo de 0,1 % para o hidrogênio, 23% para o metano e 29% para o monóxido de carbono para a obtenção da concentração absoluta de H₂, CH₄ e CO encontrados em misturas com composições conhecidas de antemão.The achievement of the content of each component of a gas mixture from gasifiers has been a matter of several studies. There are specific techniques for this purpose, such as: gas chromatography, infrared spectroscopy and sensors. In order to allow a low cost application for obtaining the concentrations in a gas mixture, this study proposes a set up for sensing H₂, CH₄ and CO found in fuel gases produced by gasifiers. The sensing is performed by commercially available chemiresistors of SnO₂. The proposed set up collects the gas mixture and dilutes it before proceeding the sensing step, based on the safety requirements to avoid explosion. 125 different gas mixtures were prepared from the combination of 0, 200, 800, 1500 and 2000 ppm of H₂, CH₄ and CO using nitrogen (99.999%) as the carrier gas. The samples were evaluated under two different methods for sensor recovery: forced and natural. Based on the results, it was established that: the cross sensitivity of the CO and CH₄ sensors is too high while the H₂ sensor presents higher selectivity (almost 100%) and the natural recovery method showed improved results because of the better thermal stability of the system. An artificial neural network was developed and trained with the purpose of overcoming the problem of cross sensitivities. The results achieved by means of the neural network are promising and indicated a maximum error of 0.1% for hydrogen, 23% for methane and 29% for carbon monoxide when the absolute concentration of H₂, CH₄ and CO found in the gas mixtures are obtained from well known compositions
Variations on the Author
No full text“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
No full textWe 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
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