1,720,952 research outputs found
Interaction between membrane and protein properties on flux decline during sterile microfiltration
Get PDFDepartment Head: Stuart A. Tobet.Includes bibliographical references (pages 63-66).Microfiltration is widely used in industry to filter out particulate matter that contaminates or slows down the performance of the membrane. In the biopharmaceutical industry in particular, bacteria, microorganisms and viruses are filtered out using sterile microfiltration. Numerous studies have been conducted to further the understanding of flux decline due to protein fouling. Many times the operating conditions, the type of membrane and type of protein all interact to have an effect on protein fouling and flux decline. Normal-flow microfiltration experiments were conducted using uncoated polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF) membranes, and PTFE and PVDF membranes coated with polyvinyl alcohol (PVA). Feed streams consisted of lysozyme, β-lactoglobulin and ovalbumin. The pH values of the solution were set at the isoelectric point of each of the proteins (11.0, 5.8, and 4.7 respectively). The experiments were operated with a feed pressure of 2 or 10 psi. Each of the proteins was tested at 0.1 and 2 g/L with uncoated PTFE. No flux decline was seen using 0.1 g/L, so 2 g/L was focused on for PVA coated PTFE, PVA coated PVDF and uncoated PVDF membranes. Protein fouling of the membrane was investigated by determining the variation of permeate flux versus filtrate volume and by analysis of Attenuated Total Reflection-Fourier Transform Infrared (ATR-FTIR) spectra and Field Emission Scanning Electron Microscopy (FESEM) images of unfouled membranes and membranes after microfiltration. Results indicate that the greatest amount of fouling occurs with ovalbumin. The order of most to least fouling was found to be ovalbumin> β-lactoglobulin>lysozyme. Fouling was more severe at the higher protein concentration (2 g/L) and feed pressure (10 psi) and seen only when filtering the solution through uncoated and PVA coated PTFE. Flux decline under these conditions was analyzed using classical pore blockage models. In general, flux decline was found to be caused by complete pore blocking. In the case of ovalbumin filtered through PVA coated PTFE, the flux decline was first caused by pore blockage and then later transitioned to cake filtration. The proteins which showed significant fouling conditions were looked at more closely by pre-filtering the protein solution. The goal of pre-filtration was to decrease any protein aggregates present in solution. This pre-filtration step was conducted with 0.2, 0.45 and 1 μm diameter pore sizes. The flux decline when pre-filtering the feed solution with 1 μm pores was equivalent to the filtration experiments without pre-filtration. The only significant decrease in flux was present when pre-filtering with the 1μm pores. Additional experiments were conducted using hemoglobin (Hb) at 2 g/L and 10 psi operating conditions. Previous literature had shown that using 1 μm pre-filtration, there was severe flux decline for uncoated and PVA coated PTFE. To follow up on these experiments, Hb was pre-filtered using 0.2 and 0.45 μm pre-filtration membranes and then filtered through uncoated and PVA coated PTFE. These experiments resulted in no flux decline. The Hb experiments verified the results from the ovalbumin and β-lactoglobulin experiments. All together, these results indicate that there is an interaction among membrane properties, protein properties, operating conditions and pre-filtration characteristics that determine whether fouling occurs and to what extent
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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