1,720,967 research outputs found
Approcci NGS per migliorare la resa delle colture riducendo le perdite ambientali
No full textIn risposta alla crescente necessità di incrementare la produzione alimentare senza un eccessivo sfruttamento dei suoli coltivati, è cruciale perseguire la selezione di piante coltivate più resilienti e sostenibili. Una strategia per affrontare questa sfida coinvolge l'identificazione di sequenze di marcatori molecolari associate alla tolleranza agli stress ambientali per agevolare la selezione di nuove varietà coltivate. In alternativa, esiste la possibilità di valutare trattamenti innovativi, come i biostimolanti, che hanno il potenziale per migliorare sia la crescita che la resilienza delle colture.
Al fine di raggiungere questi obiettivi, la presente tesi si propone di indagare aspetti genetici associati alla risposta agli stress abiotici nella barbabietola da zucchero (Beta vulgaris L.) e al trattamento con biostimolanti nel pomodoro (Solanum lycopersicum L.) soggetto a stress da freddo. I primi due capitoli si sono concentrati principalmente sulla comprensione delle caratteristiche trascrittomiche e delle variazioni dovute alle condizioni di privazione di zolfo e alle temperature di congelamento nella barbabietola da zucchero. L'ultimo capitolo della tesi ha avuto lo scopo di investigare le variazioni trascrittomiche e biochimiche dopo un trattamento con biostimolante a base di alghe in piante di pomodoro sottoposte a stress da freddo.
Il primo capitolo ha previsto l'analisi di un dataset trascrittomico per svelare la risposta della barbabietola da zucchero alle condizioni di privazione di zolfo (-S). L'obiettivo principale è stato quello di generare una lista di sequenze geniche potenzialmente correlate alla tolleranza a stress nutrizionale. Le reads di alta qualità sono state mappate sulla più recente versione del genoma della barbabietola da zucchero EL10.2_2 (McGrath, J.M., 2023). La differential expression analysis (DEA), combinata con la co-expression network analysis (WGCNA), ha identificato oltre 3.000 geni significativamente associati alla condizione di zolfo-privazione sia nei campioni di foglia che di radice. Utilizzando genomica all'avanguardia, insieme a una robusta pipeline di analisi bioinformatica e statistica, abbiamo identificato 151 geni potenzialmente legati all'adattamento alla privazione di zolfo.
Il secondo capitolo ha preseguito l'obiettivo di rianalizzare un dataset prodotto da Moliterni et al. (2015) al fine di migliorare l'output dello studio precedente. Reads di alta qualità provenienti da campioni di foglie e radici di barbabietola da zucchero esposte a temperature di congelamento (< 0°C) sono state mappate sul genoma EL10.2_2 e analizzate. Rispetto allo studio precedente, si è osservato (i) un aumento del 51% nel numero totale di geni differenzialmente espressi (DEGs), e (ii) l'osservazione di nuovi termini di gene ontology (GO) associati all'attività chitinasi e all'ubiquitinazione delle proteine. L'applicazione di una moderna pipeline di analisi dati ha permesso la selezione di 142 sequenze geniche responsabili della risposta allo stress da freddo, potenzialmente associate alla tolleranza a tale stress.
Nel terzo capitolo, è stata analizzata l'azione biostimolante di un estratto di alghe brune (BSE) su piante di pomodoro sottoposte a stress da freddo. Per valutare gli effetti del biostimolante, sono state effettuate caratterizzazioni sia fisiologiche che molecolari. In seguito all'applicazione di BSE, l'indagine trascrittomica completa ha svelato l'influenza del trattamento su geni associati a risposte cruciali allo stress da freddo. I termini della GO associ
KRAFT LIGNIN AS A FEEDSTOCK TO PRODUCE BIOFUELS AND RENEWABLE CHEMICALS
No full textThe utilization of biomass, obtained from organic matter like plants and wastes, is crucial in the pursuit of sustainable and renewable resources. Its importance lies in its capability to serve as a renewable energy source, leading to a diversified energy mix, while also mitigating greenhouse gas emissions. Lignocellulosic biomass, particularly lignin, shows great potential for replacing fossil fuels. Despite this, its utilization remains at an early stage due to difficulties in its treatment. Nonetheless, it is imperative to develop new methodologies for exploiting lignin's potential to obtain chemicals and fuels from renewable materials, considering the limited nature of fossil resources. Kraft lignin is the most produced technical lignin in the market and its sustainable and valuable utilization holds significant implications for industry. This thesis focuses on the valorization of Kraft lignin and aims to overcome the challenges associated with its utilization.
The sulfur content of Kraft Lignin has posed a challenging issue requiring the implementation of various strategies. These have included enhancing our understanding of the production mechanism of sulfur compounds and their evolution during the pyrolysis process. We attempted to establish pathways for enhancing the value of the oil, through combining pyrolysis steps and catalytic studies. Throughout the process, we always considered the undesirable effects of sulfur on both biofuel applications and chemical production
PsiNorm: a scalable normalization for single-cell RNA-seq data
Full text linkMotivation: Single-cell RNA sequencing (scRNA-seq) enables transcriptome-wide gene expression measurements at single-cell resolution providing a comprehensive view of the compositions and dynamics of tissue and organism development. The evolution of scRNA-seq protocols has led to a dramatic increase of cells throughput, exacerbating many of the computational and statistical issues that previously arose for bulk sequencing. In particular, with scRNA-seq data all the analyses steps, including normalization, have become computationally intensive, both in terms of memory usage and computational time. In this perspective, new accuratemethods able to scale efficiently are desirable. Results: Here, we propose PsiNorm, a between-sample normalization method based on the power-law Pareto distribution parameter estimate. Here, we show that the Pareto distribution well resembles scRNA-seq data, especially those coming from platforms that use unique molecular identifiers. Motivated by this result, ..
Upgrading of kraft lignin pyrolysis products: Managing sulfur impurities
No full textPyrolysis stands as a powerful method for the valorization of biomass like kraft lignin, an aromatic-rich and sulfur-containing polymeric by-product from the pulping industry. Sulfur in the raw matrix is released during thermal processes and is redistributed in pyrolysis products. However, the presence of sulfur lowers the quality of products due to its corrosive and toxic character. In this work, commercial activated carbons have been used as adsorbents to remove the main sulfur compounds from the gas phase (i.e., CH3SH, COS, H2S). The analysis of sulfur content in biochar has been performed through SEM-EDXS, while the sulfur content in oils has been obtained by GC–MS analysis. The adsorption of sulfur on the activated carbon bed results in an enhancement of the release of sulfur in the gas phase from 34 % without activated carbon to 44 %. Up to 88 % of H2S removal is achieved after the adsorption step, together with a reduction of the overall sulfur content in the bio-oil rich in intermediates such as guaiacols and alkylated phenols. The residual sulfur contained in the liquid product is lowered to 3 % of the total sulfur in the system, thus improving the quality of the liquid pyrolysis product. This process limits the amount of sulfur in the gas and improves its quality and market value. At the same time, this results in a redistribution of sulfur in pyrolysis products such as bio-oil, improving its range of application as a source of chemical intermediates from kraft lignin
Conversion of Lignin to Chemical Intermediates:a Study of Pyrolysis of Kraft Lignin
No full textExperiments of pyrolysis of commercial Kraft lignin have been realized in the 250-550 °C range. Product
analyses have been performed by FTIR, GC-MS, EDX analyses. The main goal of the work is to optimize the
experiments in terms of liquid yield, reduction of oxygen content in the resulting biochar, and removal of sulfur,
found mainly in the gas phase. It has been concluded that the amount of the starting lignin charged in the reactor
must be limited to be fully positioned in the heating chamber also during high temperature treatment. Sulfur may
be partially removed in the gas phase as H2S and CH3SH mainly, by a pre-treatment at 250 °C. The maximum
amount of liquid product, mainly constituted by methoxy- and alkyl-methoxy-phenols, and the maximum solid
deoxygenation are both obtained at 550 °C
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
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
- …
