3,218 research outputs found
Sviluppo di sensori amperometrici per l’analisi in situ di matrici reali. Il caso di studio della Cannabis sativa L.
No full textI sensori elettrochimici sono dispositivi analitici apprezzati per la loro affidabilità, rapidità, facilità d’uso, basso costo e portabilità, caratteristiche che li rendono ideali per analisi in situ. Lo sviluppo di un sensore elettrochimico segue un processo iterativo che inizia con l’analisi del contesto applicativo, passa per la scelta del materiale elettrodico e la definizione delle condizioni di misura, e termina con l’analisi della matrice target.
In questa tesi, si esamina lo sviluppo di un sensore amperometrico per l'analisi dei campioni di Cannabis sativa L., un caso di studio particolarmente rilevante. Esistono vari chemotipi di C. sativa che differiscono per la composizione in cannabinoidi. La C. sativa ricreativa, o marijuana, è ricca di Δ9-tetraidrocannabinolo (Δ9-THC), un composto psicoattivo, mentre la C. sativa da fibra contiene basse quantità di Δ9-THC e alti livelli di cannabidiolo (CBD), non psicoattivo. Normative europee e statunitensi consentono la commercializzazione di prodotti a base di C. sativa solo se il contenuto di Δ9-THC è inferiore allo 0.3 % p/p, rendendo essenziale un controllo accurato dei livelli di questo cannabinoide. In questo studio proponiamo, per la prima volta, un metodo basato sulla sensoristica amperometrica per lo screening rapido delle piante di C. sativa.
Le molecole target identificate per l'analisi elettrochimica sono il Δ9-THC, il CBD e i loro precursori acidi, Δ9-THCA e CBDA, tutte facilmente ossidabili. I test iniziali su soluzioni standard dei singoli cannabinoidi hanno dimostrato l’efficacia degli elettrodi screen-printed modificati con carbon black (SPE-CB) in definite condizioni di misura. Le prestazioni del sensore sono state valutate in condizioni critiche, come la rilevazione di Δ9-THC in presenza di grandi quantità di CBD, problematica frequente nei campioni reali. Data la somiglianza delle risposte voltammetriche di Δ9-THC e CBD, si sono impiegate tecniche multivariate per ottenere le informazioni desiderate. L'analisi elettrochimica dei precursori acidi, caratterizzati da voltammogrammi distinti rispetto alle forme neutre, ha evidenziato l'importanza delle condizioni di misura nel determinare la forma del segnale ottenuto. L'integrazione di tecniche di spettroscopia UV-Vis e di fluorescenza ha ulteriormente arricchito il quadro analitico, aprendo nuove prospettive di ricerca.
Successivamente, lo studio è stato esteso a campioni reali, costituiti da estratti alcolici di C. sativa. Il sensore è stato utilizzato per due obiettivi principali: la quantificazione dei principali cannabinoidi e la rapida identificazione di campioni illegali. Questo ha richiesto l'analisi di numerosi campioni di C. sativa da fibra e ricreativa, impiegando sia approcci univariati che multivariati per l’elaborazione dei dati. È stato sviluppato un metodo per la quantificazione del Δ9-THCA, il cannabinoide principale nelle varietà di C. sativa ricreativa, e costruiti modelli di classificazione in grado di distinguere i campioni legali da quelli illegali sulla base del contenuto di Δ9-THC. In entrambi i casi, i risultati ottenuti sono stati soddisfacenti e in linea con i dati cromatografici.
Infine, è stato sviluppato un prototipo di dispositivo portatile per l'analisi in situ degli estratti di C. sativa, in collaborazione con un gruppo di ricerca di ingegneria. Questo dispositivo automatizza la preparazione della soluzione per l’analisi elettrochimica a partire dal campione vegetale, riducendo al minimo l’intervento dell’operatore. Il sistema integra micropompe, sensori di flusso e una cella elettrochimica in cui è alloggiato l’SPE-CB. I test preliminari hanno confermato l’efficacia del dispositivo, dimostrando che consente un'analisi completa e rapida di campioni vegetali di C. sativa.Electrochemical sensors are analytical devices valued for their reliability, speed, ease of use, low cost, and portability, qualities that make them ideal for in situ analyses. The development of an electrochemical sensor follows an iterative process that begins with the analysis of the application context, proceeds through the selection of electrode material and the definition of measurement conditions, and concludes with the analysis of the target matrix.
In this thesis, the development of an amperometric sensor for the analysis of Cannabis sativa L. samples is examined, a particularly relevant case study. There are various chemotypes of C. sativa that differ in cannabinoid composition. Recreational C. sativa, or marijuana, is rich in Δ9-tetrahydrocannabinol (Δ9-THC), a psychoactive compound, whereas fiber-type C. sativa contains low amounts of Δ9-THC and high levels of cannabidiol (CBD), a non-psychoactive compound. European and U.S. regulations allow the commercialization of C. sativa products only if the Δ9-THC content is below 0.3% w/w, making precise control of this cannabinoid essential. In this study, we propose for the first time a method based on amperometric sensor for the rapid screening of C. sativa plants.
The target molecules identified for electrochemical analysis are Δ9-THC, CBD, and their acidic precursors, Δ9-THCA and CBDA, all of which are easily oxidizable. Initial tests on standard solutions of individual cannabinoids demonstrated the effectiveness of screen-printed electrodes modified with carbon black (SPE-CB) under defined measurement conditions. Sensor performance was evaluated under critical conditions, such as the detection of Δ9-THC in the presence of large amounts of CBD, a common issue in real samples. Given the similarity of the voltammetric responses of Δ9-THC and CBD, multivariate techniques were employed to obtain the desired information. The electrochemical analysis of the acidic precursors, characterized by voltammograms distinct from their neutral forms, highlighted the importance of the measurement conditions in determining the shape of the obtained signal. The integration of UV-Vis spectroscopy and fluorescence techniques further enriched the analytical framework, opening new avenues for research.
Subsequently, the study was extended to real samples consisting of alcoholic extracts of C. sativa. The sensor was used for two main objectives: the quantification of major cannabinoids and the rapid identification of illegal samples. This required the analysis of numerous C. sativa samples from both fiber-type and recreational varieties, employing both univariate and multivariate approaches for data processing. A method for the quantification of Δ9-THCA, the main cannabinoid in recreational C. sativa varieties, was developed, and classification models capable of distinguishing legal from illegal samples based on Δ9-THC content were constructed. In both cases, the results obtained were satisfactory and consistent with chromatographic data.
Finally, a prototype of a portable device for in situ analysis of C. sativa extracts was developed in collaboration with an engineering research group. This device automates the preparation of the solution for the electrochemical analysis, starting from the plant sample, minimizing operator intervention. The system integrates micropumps, flow sensors, and an electrochemical cell housing the SPE-CB. Preliminary tests confirmed the device’s effectiveness, demonstrating that it enables rapid and comprehensive analysis of C. sativa plant samples
A imagem de Alessandro Baricco no Brasil
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Comunicação e Expressão, Programa de Pós-Graduação em Estudos da Tradução, Florianópolis, 2013.Com a intenção de delinear o modo pelo qual o escritor italiano Alessandro Baricco se inseriu no sistema literário brasileiro e os caminhos percorridos pelos seus livros traduzidos, esta dissertação dá voz às experiências tradutórias de seus tradutores. A inserção de Bariccono Brasil tem seu início em 1997, através de uma proposição da Profa. Dra. Roberta Barni à editora Iluminuras da tradução de Oceano Mare. A partir daí, outras sete obras foram publicadas no Brasil, sendo três delas traduzidas por Roberta Barni e as outras quatro por quatro tradutores diferentes. De um lado, considera-se o tradutor como figura principal namediação entre culturas, e, de outro, se analisa a realidade desta figuradentro do sistema literário, sua invisibilidade, seus limites e o exercíciode sua profissão. A pesquisa conta, ainda, com críticas e resenhas referentes ao autor italiano publicadas em jornais consagrados no Brasil, considerando estas como parte constituinte da imagem de Baricco refletida em território nacional. Abstract : Intending to delineate the way the Italian writer Alessandro Baricco has been inserted in the Brazilian literary system and the paths his translated books have followed, this thesis gives voice to the translating experiences of his translators. Baricco's insertion in Brazil began in 1997, through a personal project of Dr. Roberta Barni, with her translation of Oceano Mare. Since then, seven other of his works have been published in Brazil, three of which were translated by Roberta Barni and the other four by four different translators. On the one hand,the translator is considered as the main figure in mediation betweencultures and, on the other, this figure's reality is analyzed within theliterary system: its invisibility, its limits and its professional practice. Criticisms and reviews of this Italian author published in well established Brazilian newspapers are also considered, with the understanding that they are part of Baricco's image reflected here
La maturità di Alessandro Fei del Barbiere, in bilico tra Maniera e Riforma
No full textThis article studies the mature career of the Florentine painter Alessandro Fei del Barbiere (1537-1592), beginning with the rediscovery of the 'Ascension' altarpiece formerly in the Albizi Chapel in the destroyed church of San Pier Maggiore, Florence. Studying this painting and others recorded in 1584 by the biographer Raffaello Borghini, such as the two altarpieces for Santa Maria delle Grazie and the Madonna dell'Umiltà in Pistoia, the author reconstructs a body of works showing how in the 1580s Fei gradually went beyond the archaic style of his apprenticeship - he had been trained by Ridolfo del Ghirlandaio and Pierfrancesco Foschi, but was also marked by the Maniera of Vasari - evolving towards naturalism in both mimesis and pictorial handling. In Florence, his development partly parallels that of Santi di Tito and his circle, but Fei was also influenced by a probable sojourn during the early part of that decade in Rome, where he could have been inspired by Girolamo Muziano and the painters working for Pope Gregory XIII. Among other proposals, the author suggests that the artist was responsible for decorating the chancel of Fiesole Cathedral (c. 1584-1589), which consisted of an altarpiece, only rarely discussed by scholars, and a cycle of frescoes hitherto attributed to Nicodemo Ferrucci
Tra socialdemocrazie e Perestrojka. Le relazioni internazionali del Pci attraverso le carte di Alessandro Natta
No full textThis essay reconstructs the foreign policy of the Italian Communist Party during the four
years of Alessandro Natta’s secretariat (1984-1988) through largely original archival documentation,
from the Alessandro Natta Fonds of the Historical Archive of the Chamber of
Deputies. Natta’s papers are also cross-referenced with those kept in the PCI Archive at the
Gramsci Foundation. The author analyses the relationship that the PCI establishes with
Gorbachev’s Perestroika, Deng’s China, and European social democracies during the last
years of the Cold War
Efficient Aldol-Type Reaction ofO-Protected α-Hydroxy Aldehydes andN-Trimethylsilyl Ketene Imines: Synthesis of β,γ-Dihydroxy-Nitriles
No full textAn uncatalyzed aldol-type reaction of aromatic N-trimethylsilyl ketene imines with O-protected -trialkylsilyloxy or -benzyloxy aldehydes is reported. It is shown that N-trimethylsilyl ketene imines (SKIs) are essential for the success of this aldol-type reaction, and that almost complete control of stereochemistry in the formation of the stereocentre vicinal to the stereogenic centre present in the starting aldehyde is seen when these compounds are used. A very high syn stereoselectivity was observed at room temperature, and a reversal of stereoselectivity to favour the formation of the anti product may be achieved at low temperature. Preliminary theoretical calculations support the hypothesis that the aldol-type reaction is facilitated by the formation of a cyclic transition state, with concomitant silatropic migration from the ketene imine-nitrogen to the aldehyde oxygen. The catalyst-free aldol reaction has been applied to aromatic N-trimethylsilyl ketene imines bearing two different aromatic groups. In these reactions, the diastereoselectivity for the stereocentre arising from aldehyde sp(2) carbon remained extremely high, but the stereoselectivity for the formation of the new quaternary stereocentre was unsatisfactory
Redox-Neutral Metal-Free Three-Component Carbonylative Dearomatization of Pyridine Derivatives with CO2
No full textThe TBD (1,3,5-triazabicyclodec-5-ene) assisted three-component carbonylation of pyridine-2-methana- mines is documented by means of CO2 as a benign CO surrogate. The redox-neutral methodology enables the re- alization of densely functionalized imidazo-pyridinones in high yields (up to 93%) and excellent chemoselectivity. Combined computational and experimental investigations revealed an unprecedented RCOCl/TBD concerted electro- philic activation of carbon dioxide
Volta Alessandro
No full textThe New Dictionary of Scientific Biography (extension and updating of the Dictionary of Scientific Biography) is one of the most substantial reference works in the field of the history of science. An up-to-date overview on Alessandro Volta's science with new perspectives offered by the author. Information and critical analysis is also provided on the main secondary literature produced on this main protagonist of enlightenment science after the 1976 entry "Volta Alessandro" in the Dictionary of Scientific Biography
"Muy señor nuestro Alessandro Varaldo". La ricognizione del mondo spagnolo e portoghese per riscoprire un autore italiano di successo ma dimenticato
No full textWho is Alessandro Varaldo (1876-1953)? This first analysis about what was said, adapted and translated of Varaldo’s work in the Iberian Peninsula and South America, maybe the only areas outside Italy where some traces of Italian author can be found, is a chance to go along his literary paths that overtook two temporal barriers (1900 and 1950), although it has not overtaken the oblivion’s threshold.Questa è una prima ricognizione di ciò che è stato detto, adattato e tradotto di Alessandro Varaldo (1876-1953) nella Penisola iberica e in Sud America, che si sospetta siano gli unici territori stranieri dove si riesca a ritracciare qualcosa dell’autore italiano, ed è un’occasione per ripercorrerne la traiettoria letteraria che ha superato due transenne temporali come il 1900 e il 1950 ma non quella della dimenticanza
Lean six sigma in a call centre : a case study
No full textThis paper, a case study, aims to illustrate the application of lean six sigma in a call centre of a service industry corporation. The study draws on process information and primary data from a real project. The study describes improvements in the operation of the call centre attributable to lean six sigma: increase in first-call resolution ratio, reduction in operator turnover and streamlining of processes. The introduction of lean six sigma into the call centre daily operations' management may have organizational benefits. Although lean six sigma has been extremely successful in the last two decades in the manufacturing sector, its applicability to the service sector has been a controversial topic. This study illustrates its application to a fast-growing area of the service sector, assisting companies in identifying areas of development for their call centres
First person – Alessandro Soloperto
No full textABSTRACT
First Person is a series of interviews with the first authors of a selection of papers published in Journal of Cell Science, helping early-career researchers promote themselves alongside their papers. Alessandro Soloperto is the first author on ‘Mechano-sensitization of mammalian neuronal networks through expression of the bacterial large-conductance mechanosensitive ion channel’, published in Journal of Cell Science. Alessandro is a PhD student in the lab of Francesco Difato at Istituto Italiano di Tecnologia, Genoa, Italy, investigating the potential of targeted modulation of the neuronal Ca2+ activity via remote mechanical stimulation.</jats:p
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