1,720,953 research outputs found
Continuous monoclonal antibody purification with capture via precipitation
No full textAugust2025School of EngineeringNew purification processes are required to meet the global need for high-purity, high-volume, high-dose protein therapeutics, such as monoclonal antibodies (mAbs) for the treatment of Alzheimer’s disease, high cholesterol, and infectious disease. We developed a novel intensified, continuous purification process comprised of a precipitation-based capture step followed by two flowthrough chromatography polishing steps that can meet this need by eliminating Protein A affinity chromatography, the bottleneck of the current “platform” mAb manufacturing process. We pre-process harvested cell culture fluid (HCCF) to deplete host cell DNA and remove media components that interfere with mAb precipitation, capture the mAb via precipitation using synergistic bulk precipitants (ZnCl2 and PEG), dewater and wash the precipitate slurry using hollow fiber microfiltration modules in a countercurrent flow configuration to enhance impurity removal, redissolve the washed precipitates at pH 3.5 to enable low pH viral inactivation, and employ two orthogonal flowthrough subtractive adsorbers with minimal intermediate conditioning for polishing. This process can be operated in an integrated, fully continuous mode. It addresses the volumetric throughput, process mass intensity, and cost-of-goods bottlenecks as well as the equipment and supply chain complexities associated with the platform Protein A-based capture step that currently limit global mAb manufacturing capacity. This eminently scalable process also readily accommodates increasing upstream product titers, as the precipitation-based capture step becomes more efficient as mAb concentration increases. We demonstrated precipitation-based capture with mAb HCCF feed materials from multiple industrial partners, gaining key insights which support further process development and suggest that the capture process may be platformable. During HCCF pre-processing, we deplete host cell DNA via CaCl2 precipitation to significantly reduce DNA persistence in the process, which facilitates complete redissolution at acidic pH and allows the redissolved precipitate stream to be directly applied to the first polishing step without further stream conditioning. We also pre-concentrate and diafilter the DNA-depleted HCCF in a single-pass tangential flow filtration step to remove culture media components that interfere with mAb precipitation and to standardize the precipitation feed concentration and buffer matrix, which permits the use of similar, low precipitant concentrations for quantitative precipitation (> 95%) for all mAbs studied. For the capture step, we found that the addition of CaCl2 during precipitation leads to the formation of more densely packed precipitate particles, resulting in higher sustainable flux values and better impurity removal in the dewatering and washing operations. We attained maximum sustainable conversions of 65-75% in the hollow fiber microfiltration modules, which led to host cell protein (HCP) levels as low as 11,500 ppm for redissolved precipitates. At maximum sustainable conversion conditions, we achieved yields as high as 94%, buffer consumption as low as 370 mL/g mAb, and throughput as high as 33 g mAb/m2/h (based on total membrane area of the dewatering and washing hollow fiber modules) for the precipitation capture step.
We integrated the precipitation-based capture step with two flowthrough polishing steps and demonstrated fully continuous operation of the monoclonal antibody purification process. Following precipitation capture, we redissolved the washed mAb precipitates via in-line dilution at low pH to enable loading of the first polishing step. We utilized novel flow attenuation hollow fiber ultrafiltration modules to match the flow rates of the redissolution and neutralization steps with the subsequent polishing operations, enabling fully continuous operation of the process without the use of surge tanks. For polishing, we employed two orthogonal flowthrough subtractive adsorbers and performed an in-line pH adjustment (neutralization) between the steps. We utilized the combination of a hydrophobic adsorbent (activated carbon) and a mixed-mode anion exchanger (Capto Adhere ImpRes), which results in excellent clearance of residual impurities including HCPs and aggregate species at high mAb yields. We achieved > 90% yield for each processing step and observed a significant increase in precipitation capture yield during prolonged operation at steady-state conditions, resulting in an overall purification process yield exceeding 82%. We reduced host cell protein concentrations to below 10 ppm and high molecular weight impurity levels to approximately 1% in the final purified product.
We intensified the precipitation-based capture step by increasing the precipitation feed concentration by a factor 3. We attained a maximum sustainable conversion of only 40% for the intensified process, leading to significantly lower impurity removal in the dewatering and washing steps and HCP levels of approximately 50,000 ppm for redissolved precipitates. In future implementations of the intensified precipitation capture process, filtration performance in the dewatering and washing steps must be improved to enable high-capacity flowthrough polishing chromatography operations that meet final purity targets. Intensification of the precipitation capture process resulted in significant improvements in throughput (147 g mAb/m2/h) and buffer consumption (93 mL/g mAb). We performed an environmental analysis which revealed that intensification via feed pre-concentration resulted in substantial improvements in sustainability metrics for the continuous precipitation capture process. However, additional process intensification, which can be achieved by further pre-concentration of the precipitation feed, will be required to make continuous precipitation capture competitive with continuous Protein A capture relative to environmental footprint. We also performed a simple scaling analysis of process economics which suggested that process intensification reduced the Cost of Goods for continuous precipitation capture to a value lower than continuous Protein A capture.Ph
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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