1,720,972 research outputs found
Enhancing magnetosome biomanufacturing: understanding biomineralization and process development
Full text linkMagnetosomes, membrane-bound magnetic nanocrystals produced by magnetotactic bacteria, offer a promising alternative to chemically synthesized magnetic nanoparticles due to their unique properties, enabling great potential in nanobiotechnology and biomedicine. However, several challenges hinder their large-scale production, including limited understanding of the biomineralization processes, cell physiology, batch-to-batch reproducibility, and lack of rapid and efficient characterization techniques. This thesis addresses these challenges by exploring ironuptake and its role in biomineralization, assessing the impact of oxidative stress on magnetosome formation, and evaluating cell disruption techniques on magnetosome chain integrity. Correlative microscopy, combined with a range of analytical methods, was employed to elucidate magnetosome biomineralization and the associated physiological changes of Magnetospirillum gryphiswaldense MSR-1 under various stress conditions. The research revealed a direct correlation between the labile Fe2+ pool size and magnetosome content, as higher intracellular iron concentrations were associated with increased magnetosome production. An intracellular iron pool, distinct from magnetite, was identified, being present throughout all stages of biomineralization. The potential role of magnetosomes in mitigating oxidative stress is further evidenced as magnetosome-producing cells maintained high levels of intracellular iron with minimal oxidative stress, while non-producing cells exhibited reduced magnetosome and iron content alongside elevated reactive oxygen species levels. The observed changes in MSR-1 cell morphology and viability under external stress conditions highlight the importance of monitoring physiological changes to enhance bioprocess efficiency and robustness, crucial for the production of high-quality magnetosomes. Furthermore, downstream processing technologies were shown to compromise magnetosome chain integrity, essential for certain applications. Among the tested disruption techniques, high-pressure homogenization was found to be the most effective in preserving magnetosome chain length, while nano-flow cytometry emerged as a promising technique for rapid quality assessment of single-magnetosome preparations. The findings contribute to a broader understanding of magnetosome production, emphasizing the importance of optimizing culture conditions and developing reliable characterization methods
Production of Polyhydroxyalkanoates From Cassava Peel Waste: an Integrated Chemical and Biological Approach
Full text linkPolyhydroxyalkanoates (PHA) are biodegradable polymers synthesised by microorganisms, offering a promising sustainable alternative to petroleum-based plastics because they can be synthesised from renewable resources such as biomass. A significant challenge in the industrial production of PHA is the high manufacturing cost, primarily associated with expensive commercial refined carbon sources used as feedstock. Therefore, the use of waste biomass resources to produce PHA has the potential to improve the economic feasibility. Cassava (Manhiot esculenta) is a crop widely cultivated in tropical regions. Cassava processing industries produce large amounts of cassava waste, of which 20% are cassava peels (CP), that are predominantly dumped into landfills, resulting in greenhouse gas emissions. Therefore, this thesis aims to explore the potential of CP as biomass resource for efficient PHA production. Enzymatic and acid hydrolysis of CP were assessed. 97% of conversion from CP to fermentable sugars was achieved through a systematic approach using a design of experiments (DoE) to optimise acid concentration, time, and temperature in acid hydrolysis using H2SO4. Subsequently, cassava peel hydrolysates (CPH) were used as the sole carbon source at plate, shake flask, and benchtop stirred tank bioreactor scales for Cupriavidus necator (C. necator) growth and PHA production. Small-scale (plate and flask cultures) yielded up to 1.5 g/L of PHA, equivalent to approximately 30% (gPHA/gDCW). The optimization of the cultivation strategy in bioreactor, using defined media in the batch and CPH in the feeding phase, resulted in enhanced production, reaching 12.1 g/L of PHA, equivalent to 86% (gPHA/gDCW). An efficient process for producing PHA by integrating a chemical process for the hydrolysis of CP with a biological process for the conversion of CP into PHA using C. necator is presented. This work contributes to the advancement of efficient and sustainable PHA production in biorefinery platforms, and the replacement of petroleum-based plastics, toward achieving Net Zero targets
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
Enhancing students’ digital skills through a Biotechnology & Bioprocessing module designed for chemical engineers
Full text linkThe transformation of the chemical engineering profession is occurring in response to the industry needs of the rapidly-developing bioeconomy and biosector across Europe. To meet these requirements, a new Biotechnology and Bioprocessing module has been designed and offered to Chemical Engineering undergraduates at Aston University, UK. This module bridges chemical engineering and biosciences disciplines, providing students with new skills and knowledge to better understand the opportunities available to chemical engineering professionals within the biosector. Here, we evaluate how the use of digital technologies enhances the student’s learning experience using a range of innovative learning activities delivered in a digital environment. The student’s and author’s perceptions are evaluated, and future improvements identified. This module will contribute to preparing graduates for a successful career in the highly competitive landscape of the bioeconomy and biosector. This pedagogical approach prepares graduates for, hybrid and remote study and working patterns and; changing industrial and digital learning demands
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
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