1,721,012 research outputs found
Extraction of astaxanthin from Haematococcus pluvialis with hydrophobic deep eutectic solvents based on oleic acid
Full text linkThree novel hydrophobic deep eutectic solvents (DESs) based on oleic acid and terpenes (thymol, DL-menthol, and geraniol) were prepared, characterized, and used to extract astaxanthin from the microalga Haematococcus pluvialis without any pre-treatment of the cells. The three DES were composed of Generally Recognized As Safe (GRAS) and edible ingredients. All the tested DESs gave astaxanthin recovery values of about 60 and 30% in 6 h if applied on freeze-dried biomass or directly on algae culture, respectively. The carotenoid profile was qualitatively identical to what was obtained by using traditional organic solvents, regardless of the DES used; the monoesters of astaxanthin with C18-fatty acids were the main compounds found in all the carotenoid extracts. The thymol:oleic acid DES (TAO) could preserve astaxanthin content after prolonged oxidative stress (40% of the astaxanthin initially extracted was still present after 13.5 h of light exposure), thanks to the superior antioxidant properties of thymol. The capacity of improving astaxanthin stability combined with the intrinsic safety and edibility of the DES components makes the formulation astaxanthin-TAO appealing for the food ingredients/additives industry
Extraction and milking of astaxanthin from: Haematococcus pluvialis cultures
Full text linkWe thank the University of Bologna (RFO program) for funding.The microalga Haematococcus pluvialis is capable of accumulating natural astaxanthin when subjected to external stress and shifted towards a red-cyst phase, characterized by a robust and multilayered cell wall. In the present study, still-unexplored solvents were applied for extracting astaxanthin from H. pluvialis, directly from algae culture and without any pre-treatment of the cells. Among the tested solvents, some of them (e.g. ethyl acetate and 2-methyltehydrofuran) gave excellent astaxanthin recovery (>80%) in a short time (30 min) and others (e.g. isoamyl acetate, well known as a human-compatible solvent and already in use as a food additive) gave an astaxanthin recovery close to 90% in 1 hour and thus they are exploitable in the natural astaxanthin market. Almond oil is proved to be able to extract astaxanthin and keep H. pluvialis alive, without affecting the algal photosynthetic activity, providing the possibility to milk and regeneratively cultivate H. pluvialis and avoid an uneconomical loss of biomass
CROSS-LIFE: poly(vinyl acetate-co-crotonic acid) from bio-based synthesis - preliminary LCA results
No full textRecovery of Polyhydroxyalkanoates From Single and Mixed Microbial Cultures: A Review
Full text linkAn overview of the main polyhydroxyalkanoates (PHA) recovery methods is here reported, by considering the kind of PHA-producing bacteria (single bacterial strains or mixed microbial cultures) and the chemico-physical characteristics of the extracted polymer (molecular weight and polydispersity index). Several recovery approaches are presented and categorized in two main strategies: PHA recovery with solvents (halogenated solvents, alkanes, alcohols, esters, carbonates and ketones) and PHA recovery by cellular lysis (with oxidants, acid and alkaline compounds, surfactants and enzymes). Comparative evaluations based on the recovery, purity and molecular weight of the recovered polymers as well as on the potential sustainability of the different approaches are here presented
Novel Strategies for Recycling Poly(butylene adipate-co-terephthalate)-Starch-Based Plastics: Selective Solubilization and Depolymerization-Repolymerization Processes
Full text linkStarch-based plastics (SBPs) containing poly(butylene adipate-co-terephthalate) (PBAT) are among the most produced bioplastics on the market and are currently managed at their end of life (EoL) through composting. In view of developing novel EoL approaches, SBPs were characterized here in terms of their main components (PBAT, starch, and plasticizer), and three strategies for their recycling were investigated: (I) the selective solubilization of PBAT with ethyl acetate; (II) a two-step depolymerization-repolymerization process that consists of the catalytic selective alcoholysis of PBAT into its oligomers, followed by their repolymerization to PBAT with no need of adding a new catalyst; and (III) the complete selective depolymerization of PBAT, followed by the recovery and purification of butanediol (1,4-BD), dimethyl terephthalate (DMT), and dimethyl adipate (DMA). Up to 99, 95, and 93% recovery of the SBP components was obtained, respectively, following these three methods. Extensive characterization of the recovered PBAT was performed through molecular weight and thermal and thermomechanical analyses, demonstrating the efficiency of the processes. The environmental sustainability of the proposed approaches was also preliminarily evaluated through the calculation of their environmental factor (E-factor)
Digitally-Intensive Fast Frequency Modulators for FMCW Radars in CMOS: (Invited Paper)
No full textDigitally-intensive PLLs have already demonstrated their effectiveness as frequency synthesizers for cellular applications, being able to fulfill the specifications in terms of phase noise, spurs and power dissipation thanks to the adoption of embedded digital processing that efficiently reduces the analog impairments. In this paper we review how these techniques further enable other capabilities, namely both wideband and linear frequency modulation. The application considered as a case study is the fast chirp generation for frequency-modulated continuous wave radar at millimeter waves. We illustrate how the combination of the two-point modulation of a digital PLL and the background digital pre-distortion of the DCO enable both fast and linear modulation
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
Biomass Valorization: Sustainable Methods for the Production of Chemicals
No full textWith the depletion of fossil raw materials a readily ascertainable inevitability, the exploitation of biomass-based renewable derivatives becomes ever more practical and realistic. In Biomass Valorization: Sustainable Methods for the Production of Chemicals, accomplished researchers and authors Davide Ravelli and Chiara Samori deliver a thorough compilation of state-of-the-art techniques and most advanced strategies used to convert biomass into useful building blocks and commodity chemicals.
Each chapter in this collection of insightful papers begins by detailing the core components of the described technology, along with a fulsome description of its advantages and limitations, before moving on to a discussion of recent advancements in the field. The discussions are grouped by the processed biomass, such as terrestrial biomass, aquatic biomass, and biomass-deriving waste
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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