51 research outputs found
BIOCATALYSIS FOR BIOMASS VALORIZATION: PROTEIN HYDROLYSATES AND SUGAR ESTERS FROM AGRI-FOOD WASTES
No full textDuring this doctorate work, two research topics have been studied within the aim of valorization of waste and by-products derived from the agri-food industry using a biotechnological approach for the production of high-value chemicals. The first topic was the preparation and characterization of hydrolysates from rice bran protein. Rice bran (RB) is a waste derived from the milling process of the rice and is a rich source of highly nutritional proteins, lipids, carbohydrates, and a number of micronutrients (e.g. vitamins, minerals, antioxidants, and phytosterols). The sequential treatment of RB with carbohydrases and proteases was used to prepare mixtures of water-soluble peptides which were tested for their biological activity (ACE-inhibition) and as flavor enhancers. Carbohydrases, that catalyze the hydrolysis of the glycosidic linkages of rice bran polysaccharides, enhanced the extractability of the entrapped protein components. Then, proteases (Flavourzyme or/and Alcalase) allowed converting the protein fraction of rice bran into mixtures of more water-soluble peptides. The prepared samples were submitted to ultrafiltration by using membranes with molecular weight cut-off of 10, 5 and 1 kDa and characterized by SDS-PAGE (Sodium dodecyl sulphate-polyacrylamide gel electrophoresis), Gel Permeation Chromatography (GPC) and by sensory analysis. All samples with a molecular weight under 10 kDa exhibited ACE-inhibitory activity. The highest activity was found for the samples P4’’ (68.70%) with a molecular weight under 1 kDa and P2’ (60.19 %) with a molecular weight under 5 kDa and the lowest activity for the sample “P5” (20.28 %) with a molecular weight under 5 kDa. It is noticeable that the choice of the enzyme for the first step treatment (carbohydrases) has a great effect on the ACE – inhibitory activity of the final hydrolysate. Interestingly, the sensory analysis revealed that the resulting protein hydrolysates exert only sweet and umami taste. It should be mentioned that the bitter taste was completely eliminated, which could be considered very promising for the application and utilization of the rice bran protein hydrolysates as food enhancers. The second topic of this PhD work was the enzymatic synthesis of sugar-fatty acid esters that can be used as bio-surfactants. Surfactants constitute an important class of chemicals widely used in almost every sector of industry. Environmental and health concerns about the effects of the conventional surfactants have increased the demand for surfactants from natural raw materials that possess good biodegradability and low toxicity, along with the desired functional performance. Sugar fatty acid esters (SFAEs), usually called sugar esters, are fully biodegradable, non-ionic surfactants which are characterized by excellent emulsifying, stabilizing and detergency properties. Depending on carbon chain length and nature of the sugar head group, together with the many possibilities for linkage between the hydrophilic sugar and the hydrophobic alkyl chain, SFAEs cover a wide range of hydrophilic-lipophilic balance (HLB) values which result in tunable surfactant properties. Chemical synthesis of SFAEs requires harsh reaction conditions which result, in most cases, in complex mixtures of isomers and by-products. Enzyme-based synthesis is an alternative strategy that can overcome the above-mentioned drawbacks. Sugar fatty acid esters can be prepared, indeed, through an esterification reaction between a sugar and a fatty acid catalyzed by a lipase. SFAEs, including glucose monooleate (GluMO), monostearate (GluMS), monopalmitate (GluMP), monolaurate (GluML), and galactose monooleate (GalMO), monostearate (GalMS), monopalmitate (GalMP), monolaurate (GalML), were synthesized by enzymatic esterification of fatty acids and the corresponding sugar. After a screening of several lipases both in free and immobilized form, an immobilized lipase CALB (Candida antarctica lipase B) was selected as the biocatalyst to promote the ester bond formation. Reactions were carried out in organic solvent by using molecular sieves (4 Å) to scavenge the water by-product and thus shift the reaction toward sugar ester formation. Reaction yields and product characterization were assessed by NMR. Rational design of enzymatic reactions was carried out by using the synthesis of GluMP as the model reaction. Sugar: fatty acid ratio, temperature, and reaction time were selected as variables (response: product yield)
Tragically Speaking
No full textFrom German idealism onward, Western thinkers have sought to revalue tragedy, invariably converging at one cardinal point: tragic art risks aestheticizing real violence. Tragically Speaking critically examines this revaluation, offering a new understanding of the changing meaning of tragedy in literary and moral discourse. It questions common assumptions about the Greeks’ philosophical relation to the tragic tradition and about the ethical and political ramifications of contemporary theories of tragedy.
Starting with the poet Friedrich Hölderlin and continuing to the present, Kalliopi Nikolopoulou traces how tragedy was translated into an idea (“the tragic”) that was then revised further into the “beyond the tragic” of postmetaphysical contemporary thought. While recognizing some of the merits of this revaluation, Tragically Speaking concentrates on the losses implicit in such a turn. It argues that by translating tragedy into an idea, these rereadings effected a problematic subordination of politics to ethics: the drama of human conflict gave way to philosophical reflection, bracketing the world in favor of the idea of the world. Where contemporary thought valorizes absence, passivity, the Other, rhetoric, writing, and textuality, the author argues that their “deconstructed opposites” (presence, will, the self, truth, speech, and action, all of which are central to tragedy) are equally necessary for any meaningful discussion of ethics and politics
Distribution of sequences related to L-functions
No full textThis thesis consists of three projects.
The first project focuses on the distribution of zeros of linear combinations of derivatives of -functions. We consider a collection of such combinations and prove asymptotic formulas for the supremum of the real parts of their zeros. Moreover, an investigation of an inverse-type question related to the case of the Riemann zeta function is included.
In the second part of this thesis, we expand the class of Dirichlet series whose monotonicity properties are known. In particular, we describe a large class of Dirichlet series that are not logarithmically completely monotonic. Using similar techniques, an equivalent formulation of the Riemann Hypothesis for the Ramanujan-tau -function is provided.
The last project is related to walks to infinity. Our main object is the subset of the complex plane that includes all the primes of all rings of integers of all imaginary quadratic fields. One would want to know if it is possible to walk to infinity stepping only on points in and such that the sequence of lengths of steps used in the process is bounded. However, the problem is surprisingly connected to some famous and notoriously difficult unsolved problems. We study more general walks on the set , where the length of the steps is not forced to be bounded throughout the walk.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2021-08-01The student, Kalliopi Koutsaki, accepted the attached license on 2019-05-28 at 20:11.The student, Kalliopi Koutsaki, submitted this Dissertation for approval on 2019-05-28 at 20:19.This Dissertation was approved for publication on 2019-06-03 at 14:10.DSpace SAF Submission Ingestion Package generated from Vireo submission #13999 on 2019-11-26 at 13:01:05Made available in DSpace on 2019-11-26T20:49:01Z (GMT). No. of bitstreams: 2
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Biocatalysis for rice bran valorization
No full textThe use of biocatalysis for the conversion of biomass into value added products is rapidly growing. We report here the application of biocatalytic processes to the valorization of rice bran oil and protein.
Because of the large amount of rice produced annually, by-products of rice milling, such as rice bran (ca. 70 kg/tonn of rice), are plentiful and readily available. Although rice bran is a rich source of highly nutritional proteins (10-16%), lipids (15-22%), carbohydrates (34-52%), and a number of micronutrients (e.g. vitamins, minerals, antioxidants, and phytosterols), it is currently under-utilized. The aim of this work is to exploit the protein and the oil fraction of rice bran by using a biotechnological approach to obtain high-added value products.
Rice bran protein (RBP) are valuable because they contain essential amino acids and are hypoallergenic. However, the heterogeneous and complex nature as well as the poor solubility of RBP due to strong aggregation and/or extensive disulfide bond cross-linking are limiting factors in their utilization as food ingredients. A biocatalyzed process based on the use of proteases, also in combination with carbohydrate-hydrolyzing enzymes, was developed to solubilize RBP and to enhance the extractability of the entrapped protein components.
On the other hand, rice bran oil (RBO) is characterized by a high free fatty acids (FFA) content. This feature makes RBO unsuitable for processing into edible oil; however, it can be a valuable feedstock for the production of chemicals. In fact, a significant number of high-value products require FFA in their manufacturing. RBO was submitted to a preparative lipase-catalyzed hydrolysis affording pure FFA in a moderate yield.
This work is supported by Fondazione Cariplo (RiceRes Project, 2014-0558
Enzymatic transformation of biomass: Valorization of rice bran oil and protein
No full textThe valorization of rice bran, a by-product derived from the rice productive chain, has attracted the attention of the scientific community for the production of high added-value products, because of its great availability (around 700 million tons are produced per year). The composition of rice bran is 15-22% lipids, 34-52% carbohydrates, 7-11% fibers, 8-12% moisture and 10-16% highly nutritional proteins1. The fatty fraction of rice bran is rich in bioactive phytochemicals that have antioxidant and chemopreventive properties2. Also, the protein hydrolyzates of rice bran could be used as flavor enhancers; moreover, due to their highly nutritional value and according to some studies they have a therapeutic potential2,3. It is a challenge though to hydrolyze the rice bran and achieve the selective separation of its useful components. In this work, a combined process for the transformation of rice bran through enzymatic catalysis is studied
Towards a more sustainable circular bioeconomy. Innovative approaches to rice residue valorization: The RiceRes case study
No full textThe paper reports an overview of the RiceRes project aiming at the multivalorization of all the wastes of the rice value chain, namely straw, husk and bran in order to improve resources eco-efficiency. A wide range of bio-products and bio-materials with different added value has been produced starting from these wastes in the framework of the RiceRes project. Among them, insulating materials for green building have been obtained from rice straw mixed with waste wool, biofillers from husk for polymer composites, mono- and di-glyceride mixtures and high-added value molecules for the food industry from bran
Forex News Annotated Dataset for Sentiment Analysis
No full textThis dataset contains news headlines relevant to key forex pairs: AUDUSD, EURCHF, EURUSD, GBPUSD, and USDJPY. The data was extracted from reputable platforms Forex Live and FXstreet over a period of 86 days, from January to May 2023. The dataset comprises 2,291 unique news headlines. Each headline includes an associated forex pair, timestamp, source, author, URL, and the corresponding article text. Data was collected using web scraping techniques executed via a custom service on a virtual machine. This service periodically retrieves the latest news for a specified forex pair (ticker) from each platform, parsing all available information. The collected data is then processed to extract details such as the article's timestamp, author, and URL. The URL is further used to retrieve the full text of each article. This data acquisition process repeats approximately every 15 minutes.
To ensure the reliability of the dataset, we manually annotated each headline for sentiment. Instead of solely focusing on the textual content, we ascertained sentiment based on the potential short-term impact of the headline on its corresponding forex pair. This method recognizes the currency market's acute sensitivity to economic news, which significantly influences many trading strategies. As such, this dataset could serve as an invaluable resource for fine-tuning sentiment analysis models in the financial realm.
We used three categories for annotation: 'positive', 'negative', and 'neutral', which correspond to bullish, bearish, and hold sentiments, respectively, for the forex pair linked to each headline. The following Table provides examples of annotated headlines along with brief explanations of the assigned sentiment.
Examples of Annotated Headlines
Forex Pair
Headline
Sentiment
Explanation
GBPUSD
Diminishing bets for a move to 12400
Neutral
Lack of strong sentiment in either direction
GBPUSD
No reasons to dislike Cable in the very near term as long as the Dollar momentum remains soft
Positive
Positive sentiment towards GBPUSD (Cable) in the near term
GBPUSD
When are the UK jobs and how could they affect GBPUSD
Neutral
Poses a question and does not express a clear sentiment
JPYUSD
Appropriate to continue monetary easing to achieve 2% inflation target with wage growth
Positive
Monetary easing from Bank of Japan (BoJ) could lead to a weaker JPY in the short term due to increased money supply
USDJPY
Dollar rebounds despite US data. Yen gains amid lower yields
Neutral
Since both the USD and JPY are gaining, the effects on the USDJPY forex pair might offset each other
USDJPY
USDJPY to reach 124 by Q4 as the likelihood of a BoJ policy shift should accelerate Yen gains
Negative
USDJPY is expected to reach a lower value, with the USD losing value against the JPY
AUDUSD
RBA Governor Lowe’s Testimony High inflation is damaging and corrosive
Positive
Reserve Bank of Australia (RBA) expresses concerns about inflation. Typically, central banks combat high inflation with higher interest rates, which could strengthen AUD.
Moreover, the dataset includes two columns with the predicted sentiment class and score as predicted by the FinBERT model. Specifically, the FinBERT model outputs a set of probabilities for each sentiment class (positive, negative, and neutral), representing the model's confidence in associating the input headline with each sentiment category. These probabilities are used to determine the predicted class and a sentiment score for each headline. The sentiment score is computed by subtracting the negative class probability from the positive one.If you use this in your research, please cite the following research article:
Fatouros, G., Soldatos, J., Kouroumali, K., Makridis, G., & Kyriazis, D. (2023). Transforming Sentiment Analysis in the Financial Domain with ChatGPT. arXiv preprint arXiv:2308.07935.
@article{fatouros2023transforming,
title={Transforming Sentiment Analysis in the Financial Domain with ChatGPT},
author={Fatouros, Georgios and Soldatos, John and Kouroumali, Kalliopi and Makridis, Georgios and Kyriazis, Dimosthenis},
journal={arXiv preprint arXiv:2308.07935},
year={2023}
Supply chain mapping for concrete recycling: The design of a closed-loop supply chain concerning the integration of novel technologies in conventional concrete production in the Netherlands
No full textConcrete is the most widely used artificial material, and shapes the largest area of the built environment in the Netherlands. Its waste stream is responsible for the highest percentage of construction and demolition waste and fundamental knowledge for affordable high-grade applications from old concrete has already been introduced. More precisely, the development of technologies that can separate End-of-life (EoL) concrete into its constituents, facilitates its recycling and reuse into new building materials and not in low-quality applications. However, in terms of concrete recycling, there is insufficient communication of the novel technologies in the construction sector and supply chain systems are not introduced in real-world problems. The current research focuses on a closed-loop approach concerning the production of conventional concrete based on a supply chain design. Specifically, the conventional and closed-loop supply chain of the production of concrete are designed in accordance with the SCOR Model. The main differences are identified and a ‘Concrete-to-concrete Recycling Plant’ is proposed as a solution to the EoL problem. It argues to change completely the conventional supply chain of concrete, and therefore recommendations for its future location in an urban environment are given. Additionally, a calculation tool regarding the recycling plant is developed in order to evaluate the suggested solution. The present study demonstrates that for each category of concrete, either prefabricated or site-cast, a recycling plant should be located next to the prefabricated or mortar industry in order to diminish transportation and inventory costs, as well as take advantage of the operating speeds of the novel technologies that compose the plant. Results indicate that a recycling plant is in accordance with the current market conditions and constitutes an efficient solution to the EoL concrete treatment by making concrete a circular material. Further research is required on a laboratory scale in order to collect quantitative data, communicate the results, and consequently, increase the awareness and acceptance of recycled aggregates in the construction sector.Management of Technology (MoT
Photographs of selected 'Skopje 2014' projects taken in April 2017, Skopje, North Macedonia
No full textPhotographs of selected 'Skopje 2014' projects taken in April 2017, Skopje, North Macedonia.
Author attribution necessary.
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/4.0/.</p
Marketing and compromising for sustainability : Competing orders of worth in the North Atlantic
No full textEarlier versions were presented at the workshop on Anthropology of Markets and Consumption, University of California Irvine (March 2013) and at the Strategic Management Society’s conference in Glasgow (June 2013). We are grateful to participants at those meetings, our colleagues Thomas Anker and Kalliopi Chatzipanagiotou, and Markus Giesler, Eileen Fischer and this journal’s referees for comments and criticisms as we developed this article. The usual disclaimer applies. Funding The author(s) disclosed receipt of the following financial support for the research, authorship, and/ or publication of this article: The research upon which this article reports was funded by the Leverhulme Trust, grant F/00 273/N.Peer reviewe
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