1,720,978 research outputs found
Physical-chemical characteristics of lignins separated from biomasses for second-generation ethanol
No full textLignin was extracted by two extraction methods from two biomasses for energy (Mischantus and Giant Reed) and a lignocellulosic material resulting from a microbial treatment of giant reed. One method of extraction involved the use of H2SO4 (SA), providing a highly aromatic water-insoluble material, while a second method employed H2O2 at alkaline pH (Ox), resulting in a water-soluble lignin. Extraction yields were related to the total Klason lignin measured for the three materials. We compared the physical-chemical features of the isolated lignins, by employing solid-state nuclear magnetic resonance spectroscopy (13C-CPMAS spectra and derived T1ρH relaxation times), thermogravimetric analyses, infrared spectrometry and high performance size exclusion chromatography (HPSEC). We found that lignin separated by the Ox method owned a more mobile molecular conformation, and was largely more water-soluble and fragmented than the lignin obtained by the SA treatment. In line with T1ρH-NMR and thermogravimetric results, the HPSEC of Ox lignins showed nominal molecular weights less than 3kDa, indicating well depolymerized materials. Such low-molecular weight and fragmented lignin obtained from biomasses for energy may become useful for application of recycled products in agriculture and in green chemistry reactions, thereby promoting an increase in the economic sustainability of biorefineries. © 2014 Elsevier Ltd
Reduced complexity of multidimensional and diffusion NMR spectra of soil humic fractions as simplified by Humeomics
No full textTavola rotonda
No full textSi propone una sintesi dei temi relativi alla protezione del patrimonio cultural
Lo strumento della confisca tra istanze nazionali e prospettive di integrazione nello spazio di giustizia europeo
No full textThe aricle analizes the framework decision 2005/212 and its impact in the relevant national case -law.
On this basis it highlights the necessity of reforms as raccomanded in the proposal of directive 2012/0036
Replacing calcium with ammonium counterion in lignosulfonates from paper mills affects their molecular properties and bioactivity
No full textLignosulfonates are important by-products of the paper industry and may be transformed into different commodities. We studied the molecular properties of ammonium (LS-AM) and calcium Lignosulfonates (LS-C) and evaluated their bioactivity towards the early development of maize plantlets. The FT-IR, 13C NMR and 1H-13C-HSQC-NMR spectra showed that the two lignosulfonates varied in hydroxyl, sulfonate and phenolic content, while DOSY-NMR spectroscopy suggested a similar diffusivity. High Performance Size Exclusion Chromatography (HPSEC) was used to simulate the effects of root-exuded acids and describe the conformational dynamics of both LS substrates in acidic aqueous solutions. This technique showed that LS-C was stabilized by the divalent Ca2+ counterion, thus showing a greater conformational stability than LS-AM, whose components could not be as efficiently aggregated by the monovalent NH4+ counter-ion. The plant bioassays revealed that LS-AM enhanced the elongation of the root system, whereas LS-C significantly increased both total and shoot plant weights. We concluded that the lignosulfonate bioactivity on plant growth depended on the applied concentrations, their molecular properties and conformational stability
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
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