1,720,952 research outputs found
High-pressure Solubility of Carbon Dioxide in Aqueous Sodium L- Prolinate Solution
No full textAbstractAn experimental evaluation of CO2 solubility in aqueous sodium L-prolinate (SP) solution was carried out using high-pressure solubility equipment at three different temperatures, 303.15, 313.15, and 333.15K. The study was conducted over the pressure range from 2 to 60bar for 30wt. % SP solution. It was found that, the CO2 loading (mole of CO2 / mole of SP) decreases with increasing temperature, while it increases with increasing the pressure of gas. ANOVA analysis was carried out to determine the statistical significance of the solubility data with respect to temperature and pressure. The CO2 loading of aqueous SP solution was also compared with MEA and aqueous sodium glycinate (SG) solution. It was observed that the aqueous SP solution has higher CO2 loading capacity as compared to 30wt. % MEA, and comparable with aqueous 30wt. % SG solution
Ionic liquid functionalized synthesis of gold nanoparticles in response to Elaise Guineensis (oil palm) leaves amount
No full textA comparative study on suitability of model-free and model-fitting kinetic methods to non-isothermal degradation of lignocellulosic materials
No full textThe thermal kinetic modeling is crucial for development of sustainable processes where lignocellulosic fuels are a part of chemical system and their thermal degradation eventuates. In this paper, thermal decomposition of three lignocellulosic materials (bagasse, rice husk, and wheat straw) was obtained by the thermogravimetric (TG) technique and kinetics was analyzed by both model-fitting and isoconversional (model-free) methods to compare their effectiveness. Two models selected from each class include Arrhenius and Coats–Redfern (model-fitting), and Kissinger–Akahira–Sunose (KAS) and Flynn–Wall–Ozawa (FWO) (model-free). The formal model-fitting approach simulating the thermal decomposition of solids by assuming a fixed mechanism was found to be unduly facile. However, activation energy (E) values calculated from two model-fitting techniques were considerably different from each other with a percentage difference in the range of 1.36% to 7.65%. Particularly, both model-fitting methods predicted different reaction mechanism for thermal disintegration of lignocellulosic materials (two-dimensional diffusion (D2) by Arrhenius and one-dimensional diffusion (D1) by Coat–Redfern method). Conversely, the model-free routine offers a transformation of mechanism and activation energy values throughout reaction and is, therefore, more authentic to illustrate the complexity of thermal disintegration of lignocellulosic particles. Based on the model-free kinetic analysis, the lignocellulosic materials may be devised in following order of activation energy: rice husk > bagasse > wheat straw, by both KAS and FWO methods with a percentage difference no more than 0.84% for fractional conversion up to 0.7. Isoconversional approach could be recommended as more realistic and precise for modeling non-isothermal kinetics of lignocellulosic residues compared to model-fitting approach.Rivers, Ports, Waterways and Dredging Engineerin
Kinetic modeling and optimization of parameters for biomass pyrolysis: A comparison of different lignocellulosic biomass
No full textA primitive element for the development of sustainable pyrolysis processes is the study of thermal degradation kinetics of lignocellulosic waste materials for optimal energy conversion. The study presented here was conducted to predict and compare the optimal kinetic parameters for pyrolysis of various lignocellulosic biomass such as wood sawdust, bagasse, rice husk, etc., under both isothermal and non-isothermal conditions. The pyrolysis was simulated over the temperature range of 500–2400 K for isothermal process and for heating rate range of 25–165 K/s under non-isothermal conditions to assess the maximum pyrolysis rate of virgin biomass in both cases. Results revealed that by increasing the temperature, the pyrolysis rate was enhanced. However, after a certain higher temperature, the pyrolysis rate was diminished which could be due to the destruction of the active sites of char. Conversely, a decrease in the optimum pyrolysis rate was noted with increasing reaction order of the virgin biomass. Although each lignocellulosic material attained its maximum pyrolysis rate at the optimum conditions of 1071 K and 31 K/s for isothermal and non-isothermal conditions, respectively, but under these conditions, only wood sawdust exhibited complete thermal utilization and achieved final concentrations of 0.000154 and 0.001238 under non-isothermal and isothermal conditions, respectively.Rivers, Ports, Waterways and Dredging Engineerin
Framework for Ecotoxicological Risk Assessment of Ionic Liquids
No full textAbstractAlthough ionic liquids (ILs) hold salient features and considered as a replacement of conventional organic solvents, but their possible toxicological and ecotoxicological impacts must be considered equally in the design and development stage. Predicted no-effect concentration (PNEC) plays a vital role in assessing the ecotoxicological hazards in the ILs. A systematic methodological framework is presented for assessing the predicted environmental concentration (PEC) of ionic liquids. Initially, an effect level is predicted with a general quantitative structure–activity relationship (QSAR). Secondly, predicted no-effect concentration (PNEC) is calculated by using assessment factor (AF). The PEC is compared to the PNEC to characterize the risk for the freshwater aquatic organisms. If the ratio continued to exceed one, ionic liquids under investigation will need further aquatic risk assessment procedures, which involve iterative steps to refine the PEC and PNEC
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
Physical Properties of Aqueous Sodium Salt Solution of α-Methylalanine (Na-AMALA)
No full textAbstractThe density, viscosity and refractive index of aqueous sodium salt of α-methylalanine (Na-AMALA) have been measured over the temperature range from (298.15 to 333.15) K in the mass fraction range of (0.05 to 0.30). Based on the results obtained, the three physical properties of the aqueous Na-AMALA solutions were found to decrease with the increasing temperature and increase with increasing concentration. Each physical property was correlated as a function of temperature by least-squares method, and the corresponding coefficients for each property were reported here. All properties were correlated well over the whole range of temperatures and concentrations. The determination of the thermal expansion coefficients of Na-AMALA solutions by using measured density was shown increased consistently with the increasing the temperatures and concentrations
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
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