1,721,047 research outputs found
Reactive extraction of lactic acid with tricctylamine/methylene chloride/n-hexane
No full textThe trioctylamine (TOA)/methylene chloride (MC)/n-hexane system was used as the extraction agent for the extraction of lactic acid. Curves of equilibrium and hydration were obtained at various temperatures and concentrations of TOA. A modified mass action model was proposed to interpret the equilibrium and the hydration curves. The reaction mechanism and the corresponding parameters which best represent the equilibrium data were estimated, and the concentration of water in the organic phase was predicted by inserting the parameters into the simple mathematical equation of the modified model. The concentration of MC and the change of temperature were important factors for the extraction and the stripping process. The stripping was performed by a simple distillation which was a combination of temperature-swing regeneration and diluent-swing regeneration. The type of inactive diluent has no influence on the stripping. The stripping efficiencies were about 70%
Water-enhanced solubilities of lactic acid in reactive extraction using trioctylamine various active diluents systems
No full textTrioctylamine (TOA) was used as the extraction agent for reactive extraction in various active diluents. Equilibrium and hydration data for various active diluents were obtained in 0.6 M TOA systems. From these data we divided the active diluents used into three classes: active diluents containing chlorine atoms, carbon-bonded oxygen donor active diluents, and phosphorus-bonded oxygen donor active diluents. This classification was based on the characteristic groups of active diluents. The amounts of lactic acid and water in the organic phase were strongly affected by physical extraction of the active diluents. The relationships between coextracted water and lactic acid extracted were represented by slopes in drawings. The sensitivity index, which is defined as the inverse of a slope, was introduced as the measure of the water-enhanced solubilities of lactic acid. Factors affecting the reactive extraction of lactic acid and water, such as the type of active diluents, the moles of amine used, and the bulkiness of the active diluents, were explained based on the characteristic groups of the active diluents
STUDY ON THE POSSIBLE EXISTENCE OF MULTIPLICITY FEATURES IN ETHENE HYDROGENATION OVER PLATINUM BOEHMITE CATALYSTS
No full textThe possible existence of multiplicity features, including ignition and extinction phenomena, are examined in ethene hydrogenation over a very short fixed bed of platinum/boehmite catalysts. Ethene hydrogenation is compared with carbon monoxide oxidation for which it has been claimed in several studies that multiple steady states can occur within the kinetic region. In our experiments an important experimental parameters is the size of the catalyst charge in the reactor. In ethene hydrogenation the multiplicity feature cannot be observed below a certain size of catalyst charge. On the other hand, in carbon monoxide oxidation this multiplicity can be observed regardless of catalyst charge size. From our observations, it is concluded that the multiplicity in ethene hydrogenation cannot be attributed to a purely kinetic process, but it results from the interaction of the chemical reaction and the heat transfer process
Direct recovery of intracellular proteins from Candida utilis using reverse micelles in combination with reducing agent
No full textIntracellular proteins were directly extracted from Candida utilis using reverse micelles in combination with a reducing agent. Extraction at pH 10 using 80 mM cetyl trimethyl ammonium bromide (CTAB) and 0.2 % 2-mercaptoethanol was the most favorable condition for cell permeabilization and protein solubilization. Stripping at pH 7 in the presence of 0.5 M KCl resulted in the efficient recovery of solubilized proteins
Water enhanced solubilities of succinic acid in reactive extraction using tertiary amines/alcohols systems
No full textTertiary amines were used as the extractants for reactive extraction in alcohol diluents. Equilibrium and hydration data for various alcohol diluents and tertiary amines were obtained. From these data, the effect of coextracted water on extractability was investigated. For the measurement of the water-enhanced solubilities of succinic acid, the sensitivity index was introduced. The amount of coextracted water into organic phase was increased with the chain length of alcohol diluents. However, the water-enhanced solubility of succinic acid was almost constant with the chain length of alcohol diluents. The sensitivity indices were proportional to the chain length of tertiary amines; thus, the water-enhanced solubilities of succinic acid were increased
Separation characteristics of lactic acid in reactive extraction and stripping
No full textLactic acid has recently been drawing much interest as a raw material for biodegradable polymer. Various extractants for lactic acid separation were tested and TOA (trioctylamine) was found the most effective one. Lactic acid was separated by reactive extraction with TOA dissolved in various diluents. The effect of temperature on the extraction efficiency was smaller than that of composition for the system studied in this work
Supplementary variable method applied to the MAP/G/1 queueing system
No full textIn this paper we consider the MAP/G/1 queueing system with infinite capacity. In analysis, we use the supplementary variable method to derive the double transform of the queue length and the remaining service time of the customer in service (if any) in the steady state. As will be shown in this paper, our method is very simple and elegant. As a one-dimensional marginal transform. of the double transform, we obtain the generating function of the queue Length in the system for the MAP/G/1 queue, which is consistent with the known result.This work is partially supported by ROSET, the Center of Applied Mathematics at
KAIST
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
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