Academic literature on the topic 'Chimica verde'

The late 20th and early 21st centuries have seen a phenomenal growth of the global economy and a continuous improvement of the standard of living in industrialized countries. Sustainable development has consequently become an ideal goal and, in the early 1990s, the concept of Green Chemistry was launched in the USA as a new paradigm.

Le recyclage du verre ne date pas de 1974, année où la première collecte en France de verres d’emballage est organisée en Haute-Marne. Si cette initiative est désormais intégrée à notre quotidien, elle n’est néanmoins qu’un jalon récent de l’histoire de cette pratique. À partir de plusieurs exemples de cargaisons antiques et byzantines chargées de verre brisé, de récits de vols de fenêtres et de vestiges archéologiques d’ateliers, nous proposons d’en retracer le cours, de l’Antiquité romaine au Moyen Âge. La physique et la chimie permettent désormais de reconnaître ces activités de recyclage à partir d’analyses de la composition élémentaire du verre, nous faisant cheminer à la croisée des sciences humaines et des sciences dures.

Les entreprises électro-intensives sont une catégorie particulière d’industriels qui concentrent, sur quelques centaines de sites, plus de la moitié de la consommation électrique de l’ensemble de l’industrie en France. Il s’agit de secteurs variés : chimie, aluminium, papier et carton, sidérurgie, ciment, plastiques, verre. Dans ces secteurs, la maîtrise de la facture d’électricité est un critère déterminant de compétitivité. Elle représente de l’ordre de 10 à 20 % des coûts de production, voire jusqu’à 80 % dans des cas extrêmes d’hyper-intensivité.

The term ‘caesura’ (or ‘pause’) has featured in discussion of English iambic pentameter for four centuries, and yet it still lacks what the Latin hexameter or the French alexandrine have: a definition of the term that might be usefully applied in stylistic description. Despite the temptation to dismiss it as a prosodic chimera or a mere epiphenomenon of syntax, this article will investigate a rough consensus that emerged amongst 18th-century theorists and practitioners about the bisecting caesura as both a normative element of versification and an aesthetic instrument, and attempt to formalize that consensus into a taxonomy based on linguistic features that will allow the caesura to function as a feature of stylistic description and analysis, not just for the heroic couplet but for the pentameter more generally, in terms of three independent and objectively definable properties that I term ‘balance’, ‘juncture’ and ‘integration’.

Les matériaux semi-conducteurs ont des propriétés optoélectroniques intéressantes pour de nombreuses applications microélectroniques. Leur introduction sous forme de films minces sur des substrats fragiles, tels que du verre fin, des feuilles de plastique souple ou des pièces imprimées en 3D, permet de créer de nouveaux matériaux intelligents en introduisant des capteurs ou des photodétecteurs. Dans cet article, nous illustrons l’intérêt de nouvelles approches basées sur des technologies laser et une chimie sol-gel pour intégrer des matériaux fonctionnels inorganiques semi-conducteurs ou diélectriques, dans des procédés rapides, agiles, avec des résolutions spatiales aux échelles micro et nanométriques.

Purpose: To determine the effectiveness of the “Tantum Verde®” drug for the prevention of inflammatory complications in patients after performing an extraction operation of impacted and ectopic wisdom teeth. Materials and Methods: Seventy patients after an extraction operation of impacted and ectopic wisdom teeth were examined. We have divided the surveyed patients into two observation groups: the main group is 34 patients, who have used “Tantum Verde®” drug (Aziende Chimiche Riunite Angelini Francesco A.C.R.A.F. S.p.A., Ancona, Italy) to prevent inflammatory complications in the oral cavity for 4-5 days and a control group – 36 patients with common preventive Furacilin mouthwash (also for 4-5 days). Results and Discussion: Inflammatory infiltration of the mucous membrane of the retromolar region in the area of the postoperative wound, on the next day after the surgery, was in all patients (100%), both in the main and in the control group. In the main group, 20 patients had moderate inflammatory infiltration of the mucous membrane (58.8%), and insignificant – in 14 patients (41.2%). In the control group: moderate infiltration – in 22 patients (61.1%), and insignificant – in 14 patients (38.9%). 2-3 days after surgery, in the main group, moderate inflammatory infiltration of the retromolar region was in 13 patients (38.2%), and insignificant – in 21 patients (61.8%). In the control group: moderate infiltration – in 24 patients (in 66.7%), and insignificant – in 12 patients (in 33.3%). In 5-6 days after the surgery, in the main group an inflammatory infiltration of the mucous membrane of the retromolar region was insignificant in all patients (in 100%). In the control group: moderate infiltration persisted in 8 patients (in 22.2%), and insignificant – in 30 patients (in 77.8%). Conclusions: Based on our researches we can conclude that the hygienic care of the oral cavity with the “Tantum Verde®” drug in patients after the removal of impacted wisdom teeth is more effective, than traditional means. It has been proven that the non-steroidal drug “Tantum Verde” has an expressed anti-inflammatory effect, and also provides a good cleaning of the postoperative wound in the retromolar region. The use of our method of hygienic treatment of the oral cavity in this contingent of patients can significantly reduce the number of postoperative inflammatory complications. The proposed method of the oral cavity care in patients after surgical treatment for the removal of impacted wisdom teeth is the most effective for preventing the development of inflammatory complications and is recommended for use both in maxillofacial hospitals and in surgical departments of dental clinics.

In a media saturated world, doodles have recently received the kind of attention usually reserved for coverage of racy extra marital affairs, corrupt governance, and product malfunction. Former British Prime Minister Blair’s private doodling at a World Economic Forum meeting in 2005 raised suspicions that he, according to one keen graphologist, struggled “to maintain control in a confusing world," which infers he was attempting to cohere a scattershot, fragmentary series of events (Spiegel). However, placid-faced Microsoft CEO Bill Gates, who sat nearby, actually scrawled the doodles. In this case, perhaps the scrawls mimicked the ambience in the room: Gates might have been ‘tuning’–registering the ‘white noise’ of the participants, letting his unconscious dictate doodles as a way to cope with the dissonance trekking in with the officialspeak. The doodles may have documented and registered the space between words, acting like deposits from his gestalt.Sometimes the most intriguing doodles co-exist with printed texts. This includes common vernacular graffiti that lines public and private books and magazines. Such graffiti exposes tensions in the role of readers as well as horror vacui: a fear of unused, empty space. Yet, school children fingering fresh pages and stiff book spines for the first few times often consider their book pages as sanctioned, discreet, and inviolable. The book is an object of financial and cultural investment, or imbued both with mystique and ideologies. Yet, in the e-book era, the old-fashioned, physical page is a relic of sorts, a holdover from coarse papyrus culled from wetland sage, linking us to the First Dynasty in Egypt. Some might consider the page as a vessel for typography, a mere framing device for text. The margins may reflect a perimeter of nothingness, an invisible borderland that doodles render visible by inhabiting them. Perhaps the margins are a bare landscape, like unmarred flat sand in a black and white panchromatic photo with unique tonal signature and distinct grain. Perhaps the margins are a mute locality, a space where words have evaporated, or a yet-to-be-explored environment, or an ambient field. Then comes the doodle, an icon of vernacular art.As a modern folklorist, I have studied and explored vernacular art at length, especially forms that may challenge and fissure aesthetic, cultural, and social mores, even within my own field. For instance, I contend that Grandma Prisbrey’s “Bottle Village,” featuring millions of artfully arranged pencils, bottles, and dolls culled from dumps in Southern California, is a syncretic culturescape with underlying feminist symbolism, not merely the product of trauma and hoarding (Ensminger). Recently, I flew to Oregon to deliver a paper on Mexican-American gravesite traditions. In a quest for increased multicultural tolerance, I argued that inexpensive dimestore objects left on Catholic immigrant graves do not represent a messy landscape of trinkets but unique spiritual environments with links to customs 3,000 years old. For me, doodles represent a variation on graffiti-style art with cultural antecedents stretching back throughout history, ranging from ancient scrawls on Greek ruins to contemporary park benches (with chiseled names, dates, and symbols), public bathroom latrinalia, and spray can aerosol art, including ‘bombing’ and ‘tagging’ hailed as “Spectacular Vernaculars” by Russell Potter (1995). Noted folklorist Alan Dundes mused on the meaning of latrinalia in Here I Sit – A Study of American Latrinalia (1966), which has inspired pop culture books and web pages for the preservation and discussion of such art (see for instance, www.itsallinthehead.com/gallery1.html). Older texts such as Classic American Graffiti by Allen Walker Read (1935), originally intended for “students of linguistics, folk-lore, abnormal psychology,” reveal the field’s longstanding interest in marginal, crude, and profane graffiti.Yet, to my knowledge, a monograph on doodles has yet to be published by a folklorist, perhaps because the art form is reconsidered too idiosyncratic, too private, the difference between jots and doodles too blurry for a taxonomy and not the domain of identifiable folk groups. In addition, the doodles in texts often remain hidden until single readers encounter them. No broad public interaction is likely, unless a library text circulates freely, which may not occur after doodles are discovered. In essence, the books become tainted, infected goods. Whereas latrinalia speaks openly and irreverently, doodles feature a different scale and audience.Doodles in texts may represent a kind of speaking from the ‘margin’s margins,’ revealing the reader-cum-writer’s idiosyncratic, self-meaningful, and stylised hieroglyphics from the ambient margins of one’s consciousness set forth in the ambient margins of the page. The original page itself is an ambient territory that allows the meaning of the text to take effect. When those liminal spaces (both between and betwixt, in which the rules of page format, design, style, and typography are abandoned) are altered by the presence of doodles, the formerly blank, surplus, and soft spaces of the page offer messages coterminous with the text, often allowing readers to speak, however haphazardly and unconsciously, with and against the triggering text. The bleached whiteness can become a crowded milieu in the hands of a reader re-scripting the ambient territory. If the book is borrowed, then the margins are also an intimate negotiation with shared or public space. The cryptic residue of the doodler now resides, waiting, for the city of eyes.Throughout history, both admired artists and Presidents regularly doodled. Famed Italian Renaissance painter Filippo Lippi avoided strenuous studying by doodling in his books (Van Cleave 44). Both sides of the American political spectrum have produced plentiful inky depictions as well: roughshod Democratic President Johnson drew flags and pagodas; former Hollywood fantasy fulfiller turned politician Republican President Reagan’s specialty was western themes, recalling tropes both from his actor period and his duration acting as President; meanwhile, former law student turned current President, Barack Obama, has sketched members of Congress and the Senate for charity auctions. These doodles are rich fodder for both psychologists and cross-discipline analysts that propose theories regarding the automatic writing and self-styled miniature pictures of civic leaders. Doodles allow graphologists to navigate and determine the internal, cognitive fabric of the maker. To critics, they exist as mere trifles and offer nothing more than an iota of insight; doodles are not uncanny offerings from the recesses of memory, like bite-sized Rorschach tests, but simply sloppy scrawls of the bored.Ambient music theory may shed some light. Timothy Morton argues that Brian Eno designed to make music that evoked “space whose quality had become minimally significant” and “deconstruct the opposition … between figure and ground.” In fact, doodles may yield the same attributes as well. After a doodle is inserted into texts, the typography loses its primacy. There is a merging of the horizons. The text of the author can conflate with the text of the reader in an uneasy dance of meaning: the page becomes an interface revealing a landscape of signs and symbols with multiple intelligences–one manufactured and condoned, the other vernacular and unsanctioned. A fixed end or beginning between the two no longer exists. The ambient space allows potential energies to hover at the edge, ready to illustrate a tension zone and occupy the page. The blank spaces keep inviting responses. An emergent discourse is always in waiting, always threatening to overspill the text’s intended meaning. In fact, the doodles may carry more weight than the intended text: the hierarchy between authorship and readership may topple.Resistant reading may take shape during these bouts. The doodle is an invasion and signals the geography of disruption, even when innocuous. It is a leveling tool. As doodlers place it alongside official discourse, they move away from positions of passivity, being mere consumers, and claim their own autonomy and agency. The space becomes co-determinant as boundaries are blurred. The destiny of the original text’s meaning is deferred. The habitus of the reader becomes embodied in the scrawl, and the next reader must negotiate and navigate the cultural capital of this new author. As such, the doodle constitutes an alternative authority and economy of meaning within the text.Recent studies indicate doodling, often regarded as behavior that announces a person’s boredom and withdrawal, is actually a very special tool to prevent memory loss. Jackie Andrade, an expert from the School of Psychology at the University of Plymouth, maintains that doodling actually “offsets the effects of selective memory blockade,” which yields a surprising result (quoted in “Doodling Gets”). Doodlers exhibit 29% more memory recall than those who passively listen, frozen in an unequal bond with the speaker/lecturer. Students that doodle actually retain more information and are likely more productive due to their active listening. They adeptly absorb information while students who stare patiently or daydream falter.Furthermore, in a 2006 paper, Andrew Kear argues that “doodling is a way in which students, consciously or not, stake a claim of personal agency and challenge some the values inherent in the education system” (2). As a teacher concerned with the engagement of students, he asked for three classes to submit their doodles. Letting them submit any two-dimensional graphic or text made during a class (even if made from body fluid), he soon discovered examples of “acts of resistance” in “student-initiated effort[s] to carve out a sense of place within the educational institution” (6). Not simply an ennui-prone teenager or a proto-surrealist trying to render some automatic writing from the fringes of cognition, a student doodling may represent contested space both in terms of the page itself and the ambience of the environment. The doodle indicates tension, and according to Kear, reflects students reclaiming “their own self-recognized voice” (6).In a widely referenced 1966 article (known as the “doodle” article) intended to describe the paragraph organisational styles of different cultures, Robert Kaplan used five doodles to investigate a writer’s thought patterns, which are rooted in cultural values. Now considered rather problematic by some critics after being adopted by educators for teacher-training materials, Kaplan’s doodles-as-models suggest, “English speakers develop their ideas in a linear, hierarchal fashion and ‘Orientals’ in a non-liner, spiral fashion…” (Severino 45). In turn, when used as pedagogical tools, these graphics, intentionally or not, may lead an “ethnocentric, assimilationist stance” (45). In this case, doodles likely shape the discourse of English as Second Language instruction. Doodles also represent a unique kind of “finger trace,” not unlike prints from the tips of a person’s fingers and snowflakes. Such symbol systems might be used for “a means of lightweight authentication,” according to Christopher Varenhorst of MIT (1). Doodles, he posits, can be used as “passdoodles"–a means by which a program can “quickly identify users.” They are singular expressions that are quirky and hard to duplicate; thus, doodles could serve as substitute methods of verifying people who desire devices that can safeguard their privacy without users having to rely on an ever-increasing number of passwords. Doodles may represent one such key. For many years, psychologists and psychiatrists have used doodles as therapeutic tools in their treatment of children that have endured hardship, ailments, and assault. They may indicate conditions, explain various symptoms and pathologies, and reveal patterns that otherwise may go unnoticed. For instance, doodles may “reflect a specific physical illness and point to family stress, accidents, difficult sibling relationships, and trauma” (Lowe 307). Lowe reports that children who create a doodle featuring their own caricature on the far side of the page, distant from an image of parent figures on the same page, may be experiencing detachment, while the portrayal of a father figure with “jagged teeth” may indicate a menace. What may be difficult to investigate in a doctor’s office conversation or clinical overview may, in fact, be gleaned from “the evaluation of a child’s spontaneous doodle” (307). So, if children are suffering physically or psychologically and unable to express themselves in a fully conscious and articulate way, doodles may reveal their “self-concept” and how they feel about their bodies; therefore, such creative and descriptive inroads are important diagnostic tools (307). Austrian born researcher Erich Guttman and his cohort Walter MacLay both pioneered art therapy in England during the mid-twentieth century. They posited doodles might offer some insight into the condition of schizophrenics. Guttman was intrigued by both the paintings associated with the Surrealist movement and the pioneering, much-debated work of Sigmund Freud too. Although Guttman mostly studied professionally trained artists who suffered from delusions and other conditions, he also collected a variety of art from patients, including those undergoing mescaline therapy, which alters a person’s consciousness. In a stroke of luck, they were able to convince a newspaper editor at the Evening Standard to provide them over 9,000 doodles that were provided by readers for a contest, each coded with the person’s name, age, and occupation. This invaluable data let the academicians compare the work of those hospitalised with the larger population. Their results, released in 1938, contain several key declarations and remain significant contributions to the field. Subsequently, Francis Reitman recounted them in his own book Psychotic Art: Doodles “release the censor of the conscious mind,” allowing a person to “relax, which to creative people was indispensable to production.”No appropriate descriptive terminology could be agreed upon.“Doodles are not communications,” for the meaning is only apparent when analysed individually.Doodles are “self-meaningful.” (37) Doodles, the authors also established, could be divided into this taxonomy: “stereotypy, ornamental details, movements, figures, faces and animals” or those “depicting scenes, medley, and mixtures” (37). The authors also noted that practitioners from the Jungian school of psychology often used “spontaneously produced drawings” that were quite “doodle-like in nature” in their own discussions (37). As a modern folklorist, I venture that doodles offer rich potential for our discipline as well. At this stage, I am offering a series of dictums, especially in regards to doodles that are commonly found adjacent to text in books and magazines, notebooks and journals, that may be expanded upon and investigated further. Doodles allow the reader to repopulate the text with ideogram-like expressions that are highly personalised, even inscrutable, like ambient sounds.Doodles re-purpose the text. The text no longer is unidirectional. The text becomes a point of convergence between writer and reader. The doodling allows for such a conversation, bilateral flow, or “talking back” to the text.Doodles reveal a secret language–informal codes that hearken back to the “lively, spontaneous, and charged with feeling” works of child art or naïve art that Victor Sanua discusses as being replaced in a child’s later years by art that is “stilted, formal, and conforming” (62).Doodling animates blank margins, the dead space of the text adjacent to the script, making such places ripe for spontaneous, fertile, and exploratory markings.Doodling reveals a democratic, participatory ethos. No text is too sacred, no narrative too inviolable. Anything can be reworked by the intimate graffiti of the reader. The authority of the book is not fixed; readers negotiate and form a second intelligence imprinted over the top of the original text, blurring modes of power.Doodles reveal liminal moments. Since the reader in unmonitored, he or she can express thoughts that may be considered marginal or taboo by the next reader. The original subject of the book itself does not restrict the reader. Thus, within the margins of the page, a brief suspension of boundaries and borders, authority and power, occurs. The reader hides in anonymity, free to reroute the meaning of the book. Doodling may convey a reader’s infantalism. Every book can become a picture book. This art can be the route returning a reader to the ambience of childhood.Doodling may constitute Illuminated/Painted Texts in reverse, commemorating the significance of the object in hitherto unexpected forms and revealing the reader’s codex. William Blake adorned his own poems by illuminating the skin/page that held his living verse; common readers may do so too, in naïve, nomadic, and primitive forms. Doodling demarcates tension zones, yielding social-historical insights into eras while offering psychological glimpses and displaying aesthetic values of readers-cum-writers.Doodling reveals margins as inter-zones, replete with psychogeography. While the typography is sanctioned, legitimate, normalised, and official discourse (“chartered” and “manacled,” to hijack lines from William Blake), the margins are a vernacular depository, a terminus, allowing readers a sense of agency and autonomy. The doodled page becomes a visible reminder and signifier: all pages are potentially “contested” spaces. Whereas graffiti often allows a writer to hide anonymously in the light in a city besieged by multiple conflicting texts, doodles allow a reader-cum-writer’s imprint to live in the cocoon of a formerly fossilised text, waiting for the light. Upon being opened, the book, now a chimera, truly breathes. Further exploration and analysis should likely consider several issues. What truly constitutes and shapes the role of agent and reader? Is the reader an agent all the time, or only when offering resistant readings through doodles? How is a doodler’s agency mediated by the author or the format of texts in forms that I have to map? Lastly, if, as I have argued, the ambient space allows potential energies to hover at the edge, ready to illustrate a tension zone and occupy the page, what occurs in the age of digital or e-books? Will these platforms signal an age of acquiescence to manufactured products or signal era of vernacular responses, somehow hitched to html code and PDF file infiltration? Will bytes totally replace type soon in the future, shaping unforeseen actions by doodlers? Attached Figures Figure One presents the intimate graffiti of my grandfather, found in the 1907 edition of his McGuffey’s Eclectic Spelling Book. The depiction is simple, even crude, revealing a figure found on the adjacent page to Lesson 248, “Of Characters Used in Punctuation,” which lists the perfunctory functions of commas, semicolons, periods, and so forth. This doodle may offset the routine, rote, and rather humdrum memorisation of such grammatical tools. The smiling figure may embody and signify joy on an otherwise machine-made bare page, a space where my grandfather illustrated his desires (to lighten a mood, to ease dissatisfaction?). Historians Joe Austin and Michael Willard examine how youth have been historically left without legitimate spaces in which to live out their autonomy outside of adult surveillance. For instance, graffiti often found on walls and trains may reflect a sad reality: young people are pushed to appropriate “nomadic, temporary, abandoned, illegal, or otherwise unwatched spaces within the landscape” (14). Indeed, book graffiti, like the graffiti found on surfaces throughout cities, may offer youth a sense of appropriation, authorship, agency, and autonomy: they take the page of the book, commit their writing or illustration to the page, discover some freedom, and feel temporarily independent even while they are young and disempowered. Figure Two depicts the doodles of experimental filmmaker Jim Fetterley (Animal Charm productions) during his tenure as a student at the Art Institute of Chicago in the early 1990s. His two doodles flank the text of “Lady Lazarus” by Sylvia Plath, regarded by most readers as an autobiographical poem that addresses her own suicide attempts. The story of Lazarus is grounded in the Biblical story of John Lazarus of Bethany, who was resurrected from the dead. The poem also alludes to the Holocaust (“Nazi Lampshades”), the folklore surrounding cats (“And like the cat I have nine times to die”), and impending omens of death (“eye pits “ … “sour breath”). The lower doodle seems to signify a motorised tank-like machine, replete with a furnace or engine compartment on top that bellows smoke. Such ominous images, saturated with potential cartoon-like violence, may link to the World War II references in the poem. Meanwhile, the upper doodle seems to be curiously insect-like, and Fetterley’s name can be found within the illustration, just like Plath’s poem is self-reflexive and addresses her own plight. Most viewers might find the image a bit more lighthearted than the poem, a caricature of something biomorphic and surreal, but not very lethal. Again, perhaps this is a counter-message to the weight of the poem, a way to balance the mood and tone, or it may well represent the larval-like apparition that haunts the very thoughts of Plath in the poem: the impending disease of her mind, as understood by the wary reader. References Austin, Joe, and Michael Willard. “Introduction: Angels of History, Demons of Culture.” Eds. Joe Austion and Michael Willard. Generations of Youth: Youth Cultures and History in Twentieth-Century America. New York: NYU Press, 1998. “Doodling Gets Its Due: Those Tiny Artworks May Aid Memory.” World Science 2 March 2009. 15 Jan. 2009 ‹http://www.world-science.net/othernews/090302_doodle›. Dundes, Alan. “Here I Sit – A Study of American Latrinalia.” Papers of the Kroeber Anthropological Society 34: 91-105. Ensminger, David. “All Bottle Up: Reinterpreting the Culturescape of Grandma Prisbey.” Adironack Review 9.3 (Fall 2008). ‹http://adirondackreview.homestead.com/ensminger2.html›. Kear, Andrew. “Drawings in the Margins: Doodling in Class an Act of Reclamation.” Graduate Student Conference. University of Toronto, 2006. ‹http://gradstudentconference.oise.utoronto.ca/documents/185/Drawing%20in%20the%20Margins.doc›. Lowe, Sheila R. The Complete Idiot’s Guide to Handwriting Analysis. New York: Alpha Books, 1999. Morton, Timothy. “‘Twinkle, Twinkle Little Star’ as an Ambient Poem; a Study of Dialectical Image; with Some Remarks on Coleridge and Wordsworth.” Romantic Circles Praxis Series (2001). 6 Jan. 2009 ‹http://www.rc.umd.edu/praxis/ecology/morton/morton.html›. Potter, Russell A. Spectacular Vernaculars: Hip Hop and the Politics of Postmodernism. Albany: State University of New York, 1995. Read, Allen Walker. Classic American Graffiti: Lexical Evidence from Folk Epigraphy in Western North America. Waukesha, Wisconsin: Maledicta Press, 1997. Reitman, Francis. Psychotic Art. London: Routledge, 1999. Sanua, Victor. “The World of Mystery and Wonder of the Schizophrenic Patient.” International Journal of Social Psychiatry 8 (1961): 62-65. Severino, Carol. “The ‘Doodles’ in Context: Qualifying Claims about Contrastive Rhetoric.” The Writing Center Journal 14.1 (Fall 1993): 44-62. Van Cleave, Claire. Master Drawings of the Italian Rennaissance. Cambridge, Mass.: Harvard UP, 2007. Varenhost, Christopher. Passdoodles: A Lightweight Authentication Method. Research Science Institute. Cambridge, Mass.: Massachusetts Institute of Technology, 2004.

The quality of green coffee represents the main condition for the production of a good end product at a cup level. Nowadays among the fields which the scientific publications deal with about the green coffee quality there are the development of methodologies for the authenticity assurance, and the study of the most appropriate methods for the water quantification. In the former case, because of the increased diffusion of adulteration practises along the coffee commercial chain, recently the need of rapid methods for coffee autentication is increased. However, the number of developed methods for the geographical origin are still limited; furthermore, the low number of analized samples in all the works carried out about this topic makes the achieved results not sufficiently statistically significant. Ambiguity also remains about the markers to be used for the geographical discrimination of coffee qualities. Thus are required, on the one hand, suitable routine methods to control as many samples as possible, on the other hand a unique set of markers has to be established. In the field of the studies carried out on water the problem of its distribution within the coffee matrix is still open. The understanding of this phanomenon is of great importance, since a correlation between the degree of hydration and the mechanical properties of the green coffee bean has been observed in literature, for instance. The research presented in this PhD work has tried to give answers to open questions mentioned above with the help of the magnetic resonance technique, which has been successfully employed in the food field . In this work two different methods have been developed to achieve the geographical origin determination of green coffee, by using the time domain NMR (TD NMR), and with the help of the high resolution NMR technique combined to multivariate statistical analysis , respectively methods. The first one, based on the time domain NMR has been realized by means of a benchtop analyser operating at a resonance frequency 1H of 20 MHz (Bruker Minispec Mq20), and also enables the fast simultaneous determination of water and oil percents of a high number of samples in a non destructive, and reproducible way, through the NMR spin echo sequence. The percentages of water and oil in the analised samples has beeen obtained by using two distinct calibration lines, respectively . The results obtained by the application of the method on 500 green coffee samples have been subjected to statistical analysis (ANOVA) The obtained results indicate that a good discrimination of the continental origins of the samples is possible by using the oil percent value as a marker. To correctly evaluate water and oil components by means of the spin echo sequence the preliminary analysis of the transverse relaxation times (T2) in the green bean with the help of by using the CPMG NMR sequence. The continous T2 distributions were obtained by inverting the experimental CPMG curves with the Laplace transformation with the help of a suitable Upen program The preliminary assignement of the the t2 mobility populations relative to water phase in the region spanning from 0.1 to 3 ms was achieved by comparing the relaxation profiles of a serie of green beans to the corrisponding profiles of the same ovendried beans The T2 region of the lipid component of the was assigned by comparing either the relaxation profiles of a some green beans at different hydration levels, or by comparing the T2 distribution of the untreated bean with the one of the fresly extracted oil from the same bean. To shed light on the water distribution in green coffee bean, the T2 region, which was previously assigned to water proton mobility, was analised in details by means of systematic gradual rehydration experiments on previously dessiccated coffee beans. The T2 distributions obtained either from manually rehydrated beans either with H2O or D2O up to 35% (dry basis) or, alternatively, wetted by exposure of a controlled air environment, were compared to the untreated beans. Data obtained indicate that up to about 10% water embedded in the bean exhibits a rather restricted mobility, likely as a result of interaction with the cell walls or hydrogen bond formation. Furthermore, the relaxation profiles obtained by rehydrating the dry beans with D2O highlighted the contribution of the proton exchance mechanism to the overall Laplace inversion signal. By the analysis of the profile of water distributions was found that this is determined by the convolution of two distinct proton mobility populations, positioned at 0.5 and 1 ms, respectively. In the green bean as well as in the rehydrated ones, which were analysed, it was found that at hydration levels up to 4%, only the fast relaxing population can be observed (i.e. the one at a lower T2), while at intermediate water contents they are both present. The fast relaxing component could be assigned to the antiplasticization effect of water, while the one which is characterized by a slower relaxation rate may be associated to water plasticizing the macromolecular polymers. In this sense our observation could provide an interpretation in terms of proton mobiliy to the so called antiplasticization effect, which was first discovered at a macroscopic level. The analysis of the T2s distribution of the region assigned to the lipid phase (i.e the one by about 10 ms to about 300 ms) shows a multimodal profile, which in particular suggests the presence of three different proton mobility populations. This observation, which was observed in the green bean as well as in the freshly extracted oil from the same bean, was then confirmed either by analysing the temperature dependence of the components and or by literature. An alternative method for the geographical autentication was also elaborated by means of the multivariate statistical of the NMR resonances obtained either from the organic or the aqueous extracts of 48 samples belonging to di different geographical origins. The obtained data indicate that in the organic extract the fatty acids seem to be effective as a markers for the discrimination the African samples among all the other ones, while the resonances of the minor costituents are able to differentiate all the samples of different origin. In particular kaweohl compound positively correlates with the Brazilian samples, while the caffeine peaks and other minor compounds discriminate the middle American samples from the ones of the south. Finally, other minor costituents characterize African and Asian samples.characterization of acqueous extract throught bidimensional NMR experiments allowed the identification of characteristic spin sistems of the other not identified components. DOSY diffusion experiments were carried out on the acqueous extract of African samples and supported the hypothesis of an interaction occurring between caffein and chlorogenic acids. In particular, the obtained data allow one to suppose that in the aqueous extract of the analized African sample the caffein is present in solution both in the free form and as a complex with the chlorogenic acid.
La qualità del caffè verde rappresenta il principale requisito per la realizzazione di una bevanda apprezzata a livello commerciale. Attualmente tra i vari campi interessati dalla produzione scientifica sulla qualità del caffè verde vi sono lo sviluppo di metodologie per garantire l’autenticità e lo studio delle metodiche più appropriate per la quantificazione dell’acqua. Nel primo caso la necessità di metodi rapidi per l’autenticazione del caffè è divenuta in tempi recenti un’esigenza sempre più pressante a causa della crescente diffusione di pratiche di adulterazione nella filiera commerciale di questo prodotto. Tuttavia sono ancora limitati i metodi formulati per la determinazione dell’origine geografica; inoltre, la bassa numerosità di campioni analizzati nei lavori compiuti in tale ambito rende i risultati trovati non sufficientemente significativi. Rimane infine ambiguità sui possibili markers da utilizzare nella discriminazione. Occorrono da un lato quindi metodi adatti ad analisi routinarie per il controllo del maggior numero possibile di campioni, e dall’altro una scelta univoca di possibili markers per la discriminazione geografica delle varie qualità di caffè. Nell’ambito degli studi compiuti sull’acqua rimane ancora aperta la problematica della distribuzione dell’acqua stessa all’interno della matrice. La comprensione di questo fenomeno è di notevole importanza in quanto è stata osservata ad esempio in letteratura la correlazione fra il grado di idratazione e le proprietà meccaniche del chicco verde. La ricerca presentata in questo dottorato ha cercato di dare una risposta alle problematiche aperte appena descritte con il ricorso alla Risonanza Magnetica Nucleare, recentemente utilizzata con successo in ambito alimentare. In questo lavoro sono stati sviluppati infatti due metodi per la determinazione dell’origine geografica del caffè verde, rispettivamente con l’NMR nel dominio dei tempi, e con l’NMr ad alta risoluzione, quest’ultimo in combinazione con l’analisi statistica multivariata. Il primo metodo, basato sull’NMR nel dominio dei tempi, è stato realizzato per mezzo di uno spettrometro operante alla frequenza di 20 MHz (Bruker Minispec Mq20), e permette la determinazione simultanea delle percentuali di acqua e olio di un elevato numero di campioni in maniera rapida e riproducibile tramite l’utilizzo della sequenza spin echo. I valori delle percentuali di acqua e olio nei campioni sottoposti ad analisi è stato ricavato utilizzando due differenti calibrazioni per l’acqua e per l’olio. Le percentuali di acqua e olio ottenute dall’applicazione del metodo su 500 campioni di caffè verde sono stati sottoposti ad analisi statistica (ANOVA). I risultati ottenuti indicano che una buona discriminazione dei continenti di provenienza dei campioni è possibile utilizzando il valore di percentuale di olio come marker. Per quantificare correttamente le componenti acqua e olio con la sequenza spin echo è stata necessaria l’analisi preliminare dei tempi di rilassamento trasversale (T2) nel chicco verde con l’NMR nel dominio dei tempi mediante l’applicazione della sequenza CPMG. Le distribuzioni continue di tempi di rilassamento trasversale sono state ricavate invertendo con la trasformata di Laplace con l’aiuto del software Upen le curve CPMG ottenute. L’assegnazione preliminare della popolazioni di T2 relative alla fase acqua nella regione compresa fra 0.1 e 3 ms è stata realizzata confrontando i profili di rilassamento di una serie di chicchi verdi con i corrispondenti profili ottenuti per essicazione in stufa. La regione di T2 relativa alla componente lipidica dei chicchi verdi è stata invece assegnata sia confrontando i profili di rilassamento di una serie di chicchi a diversi livelli di idratazione sia confrontando le distribuzioni di T2 nel chicco con quella dell’olio estratto dallo stesso. Allo scopo di far luce sulla distribuzione dell’acqua nel caffè verde la regione della distribuzione di T2 attribuita all’acqua è stata studiata in dettaglio con una serie di esperimenti sistematici di reidratazione graduale di chicchi precedentemente essiccati. Le distribuzioni di T2 ottenute da chicchi essiccati e reidratati manualmente fino al 35% (su base secca) sia con H2O che con D2O e, alternativamente, per esposizione in atmosfera di umidità controllata, sono state confrontate con quelle di chicchi verdi tal quali. I dati ottenuti indicano che fino a circa 10% l’acqua incorporata nel chicco manifesta una mobilità ridotta, in quanto probabilmente adsorbita o legata con le pareti cellulari mediante ponti idrogeno. La reidratazione con acqua deuterata ha evidenziato inoltre il contributo dello scambio protonico al segnale della distribuzione osservato. L’analisi dei profili di distribuzioni dell’acqua ha inoltre portato all’osservazione che questo risulta determinato dalla convoluzione di due popolazioni di mobilità protonica, rispettivamente centrate a circa 0.5 e 1 ms. Sia nel chicco verde che in quelli reidratati è stato trovato che a contenuti di acqua fino a 4% delle due popolazioni è visibile solo quella a mobilità inferiore, mentre a percentuali intermedie sono presenti entrambe. Con riferimento all’articolo di Pittia e collaboratori, la componente a rilassamento rapido potrebbe essere associata all’effetto di antiplasticizzazione dell’acqua, mentre la popolazione caratterizzata da rilassamento più lento può essere correlata all’effetto plasticizzante dell’acqua. In questo senso i nostri dati forniscono una conferma ed un’interpretazione in termini di mobilità protoniche al co-siddetto effetto di antiplasticizzazione, scoperto a livello macroscopico. La distribuzione dei tempi di rilassamento trasversale dei T2 della regione associata ai lipidi (cioè quella compresa fra circa10 ms e circa 300 ms) mostra un profilo multimodale, che suggerisce la presenza di tre diverse mobilità protoniche. Tale osservazione è stata confermata sia con lo studio della dipendenza dalla temperatura delle mobilità protoniche, compiuto sia per la fase lipidica all’interno dei chicchi, sia per l’olio fresco isolato mediante estrazione soxhlet, sia dal confronto con dati di letteratura. Questa osservazione ha trovato inoltre conferma nei dati di letteratura. Un metodo per la discriminazione geografica è stato infine elaborato mediante l’analisi statistica multivariata delle risonanze NMR sia degli estratti organici che acquosi di 48 campioni di caffè verde di diversa provenienza. I dati ottenuti indicano che nell’estratto organico gli acidi grassi sembrano essere efficaci nel discriminare i campioni africani da tutti gli altri analizzati, mentre le componenti minoritarie sono efficaci nella differenziazione tra i campioni con diversa provenienza. In particolare il Kahweolo correla positivamente con i campioni del Brasile, mentre la caffeina e i composti minoritari differenziano i campioni centro americani da quelli del sud America, e altri componenti minoritari non identificati che caratterizzano i campioni africani e quelli asiatici. La caratterizzazione dell’estratto acquoso mediante esperimenti bidimensionali ha permesso inoltre l’identificazione di sistemi di spin caratteristici degli estratti protonici del campioni di caffè brasiliano, quali zuccheri minoritari e isomeri dell’acido clorogenico. Esperimenti di diffusione DOSY condotti sull’estratto acquoso dei campioni di origine africana hanno inoltre avvalorato l’ipotesi di una possibile interazione caffeina/ acidi clorogenici. In particolare i dati ottenuti fanno supporre che nell’estratto acquoso del campione africano analizzato, la caffeina è presente in soluzione sia in forma libera che complessata con l’acido clorogenico.

Il progetto di ricerca si concentra sullo sviluppo di nuove strategie sintetiche per la preparazione di semiconduttori organici stampabili e scalabili industrialmente. A tal fine, è stato introdotto un nuovo metodo sintetico per una facile, economica ed eco-sostenibile produzione di semiconduttori organici coniugati. Oggigiorno, il concetto di sostenibilità è una questione molto importante per le aziende che si impegnano nel rispettare i principi della Green Chemistry al fine di ridurre l'impatto ambientale dei processi chimici. In questo quadro, la catalisi micellare si è dimostrata un'ottima soluzione permettendo di condurre le reazioni utilizzando l’acqua come l’unico mezzo di reazione generalmente in presenza di piccoli quantitativi di surfattante. Ma purtroppo non sempre la catalisi micellare risulta essere riproducibile e facilmente scalabile industrialmente. A tal proposito, è stato studiato un sistema auto-emulsionante composto da una miscela di L-α-Lecitina e Tween 80 (TL82) per la preparazione di piccole molecole organiche. La caratteristica unica di questa miscela di tensioattivi offre un nuovo ambiente per l'esecuzione di comuni reazioni di cross-coupling come le reazioni di Suzuki-Miyaura, Sonogashira e Heck in modo riproducibile su larga scala. La versatilità di questo approccio è stata verificata attraverso la sintesi di semiconduttori organici complessi basati su pigmenti insolubili. La grande attenzione all'introduzione della sostenibilità non riguarda solo la sintesi, ma anche il processing dei materiali per la produzione di dispositivi. È stato introdotto un processo innovativo che consente la preparazione di dispositivi a film sottile ad alte prestazioni a partire da dispersioni acquose di semiconduttori organici sia di tipo p- che n-. La miscela di tensioattivi auto-emulsionante TL82 viene utilizzata sia come mezzo di sintesi che di processing. Questo metodo consente la preparazione di Transistor Organici ad Effetto di Campo utilizzando esclusivamente l’acqua in tutte le fasi di preparazione, ottenendo prestazioni paragonabili ai dispositivi ottenuti dai processi svolti utilizzando solventi organici. Sono stati inoltre progettati nuovi materiali innovativi performanti per l'(opto)elettronica. In particolari sono stati progettati sia piccole molecole che polimeri coniugati originali ponendo una grande attenzione al selezionamento di materie prime a basso costo, limitando severamente l'utilizzo di sostanze chimiche tossiche e pericolose e progettando tutti i processi per un possibile up-scaling. In dettaglio, buona parte del lavoro è stata dedicata allo sviluppo di materiali sostenibili per applicazione in concentratori solari luminescenti. Le prestazioni dei materiali sintetizzati sono state confrontate con quelle dei lumofori commercialmente disponibili con caratteristiche spettrali simili. Nel complesso, i nuovi materiali sviluppati mostrano prestazioni comparabili, ma col vantaggio di essere sintetizzati in maniera green e facilmente scalabili industrialmente. Infine, è stato sviluppato un monomero derivato tiofenico asimmetrico con caratteristiche intrinseche di donatore e accettore al fine di sviluppare uno dei primi esempi di polimero regio-regolare ambipolare.
The research focuses on the development of new synthetic routes for the preparation of printable organic semiconductors, devised to be suitable for industrial scaling up. As such, a novel synthetic method for facile, cheap, and environmentally friendly production of π-extended organic semiconductors is explored. The concept sustainability is becoming a very important issue for chemical industries which are approaching green chemistry to reduce the environmental impact of chemical processes. In this frame, micellar catalysis has been demonstrated to be profitably performed in water under very mild conditions in the presence of a bit surfactant. Firstly, a self-emulsifying system L-α-Lecithin-Tween 80 mixture (TL82) is explored for the preparation of organic small molecules. The unique characteristic of this surfactant’s mixture offers a new environment for carrying out common cross coupling reactions such as Suzuki-Miyaura, Sonogashira and Heck cross-couplings in a reproducible up-scale way. The versatility of this approach is verified through the synthesis of complex organic semiconductors such as π-extended insoluble pigments. The emphasis on sustainability is not only applied to the synthesis but also to the processing of the active materials into the final target devices. Indeed, an innovative process is introduced enabling the preparation of high-performance thin film devices starting from waterborne dispersions of p- and n-type organic semiconductors. The TL82 self-emulsifying surfactant’s mixture is used both as the synthesis and processing medium. This method allows the preparation of Organic Field Effect Transistor using exclusively water in all steps with performances comparable to those synthesized and processed using common organic solvents. From the standpoint of the design of innovative materials, additional guidelines beside those aiming at achieving high performances are introduced. Original small molecules and polymers are designed selecting low-cost raw materials, severely the limiting the use of toxic and hazardous chemicals and designing all processes with up-scaling already in mind. These materials find an application in the field of (opto)electronics. An example of a good compromise between a simple design-good performance of a class of materials was investigated. In detail, a good part of the work was dedicated to the technology of luminescent solar concentrators devices, where the performances of the newly designed intrinsically sustainable materials are compared with those commercially available luminophores having similar spectral features. In the overall, we demonstrate comparable performance, but greatly improved sustainability and scalability. The final project was dedicated to the presentation of the first example of D-A regioregular polythiophene with an ambipolar character.

Le développement de catalyseurs actifs et stables exempts de métaux nobles est de plus en plus requis pour les applications environnementales et la valorisation des ressources renouvelables. Le réglage aisé de la réactivité des oxydes mixtes à structure pérovskite par des substitutions de cations et d’anions en fait un domaine prometteur d’innovation des catalyseurs. Dans cette thèse, deux classes de matériaux à base de pérovskite ont été synthétisées, caractérisées et testées en catalyse. La substitution de Al par des cations Co et Ga dans LaAlO3 a permis de modifier les propriétés rédox et acide-base, alors que les substitutions partielles de l’oxygène par l’hydrure dans LaSrCoO4 ont permis de nouveaux essais d’activité d’hydrogénation.La maîtrise des propriétés redox de l'oxyde mixte LaAlO3 par substitution de Co a permis de développer un catalyseur multifonctionnel actif dans la décontamination des NOx et de la suie des gaz d'échappement de moteurs diesel. L'oxydation des suies assistée par NOx implique une conversion de NO en NO2 et une oxydation ultérieure des suies par le NO2 formé à une température relativement basse. Des matériaux LaAlO3 avec différents degrés de substitution de Co pour Al ont été préparés par la méthode sol-gel et leur activité catalytique a été corrélée à la cristallinité, aux propriétés redox et à la mobilité de l'oxygène de réseau. Parmi les échantillons étudiés, LaAl1-xCoxO3 avec x 0,75 présente une activité catalytique supérieure pour l'oxydation du NO en NO2 et l'oxydation de la suie assistée par le NOx. L'excellente performance est attribuée à l'interaction synergique entre Al-Co dans le site B de la structure et peut être liée à l' élevé oxygène de surface supporté par une structure de pérovskite bien cristallisée.La production de bioéthanol est l’un des éléments essentiels du remplacement des combustibles fossiles par des ressources renouvelables issues de la biomasse. La valorisation du bioéthanol pour la production de produits chimiques nécessite un contrôle minutieux des propriétés acido-basiques des catalyseurs. Alors que la plupart des recherches sur les catalyseurs pérovskites ont porté sur leurs propriétés rédox, les études sur leurs propriétés acide-base ont été beaucoup moins développées. La substitution partielle de Al par Co et Ga dans LaAlO3 a permis d’ajuster l’acidité et la basicité du matériau et de contrôler l’activité relative de déshydratation et de déshydrogénation de l’éthanol, en contrôlant le rapport entre éthylène et acétaldéhyde formés. La nature du cation introduit a permis de former différentes paires base-acide de Lewis, orientant la réactivité de l’intermédiaire acétaldéhyde vers le couplage de Tishchenko ou le couplage aldolique, permettant ainsi d'orienter la cascade réactionnelle vers la formation de butadiène ou d'acétone et oxygénés a nombre de carbones impair.Alors que la plupart de la littérature sur la réactivité des pérovskites est centrée sur leurs modifications de structure et propriétés par substitution de cations, il existe un nombre limité de travaux sur les substitutions dans les sites anioniques. Les pérovskites oxyhydrures, ABO3-xHx, où les anions hydrure H- peuvent remplacer O2- à n’importe quel site de l’octaèdre BO6, ont présenté une mobilité d’hydrures importante, suggérant des applications potentielles en catalyse d’hydrogénation. Les oxyhydrures LaSrCoO3H0.7 et BaTiO3-xHx ont été préparés, caractérisés et testés dans une réaction d'hydrogénation modèle. La réactivité des espèces hydrures a été testée par titrage chimique du toluène à des températures auxquelles les hydrures devraient être mobiles. Les résultats montrent que LaSrCoO4-xHy présente une activité nettement supérieure au BaTiO3-xHx, activité qui doit être attribuée aux sites métalliques formés par réduction partielle de LaSrCoO4-xHy, indiquant une utilisation possible des pérovskites comme support pour les catalyseurs d'hydrogénation
Development of active and stable noble metal-free catalysts is more and more required for environmental applications and valorization of renewable resources. Easy tuning of the reactivity of mixed oxide perovskites by cation and anion substitutions render them a promising field of catalyst innovation. In the thesis, two classes of perovskite materials have been synthesized, characterized and tested in catalysis. Cation substitution of Co and Ga for Al in LaAlO3 has allowed to modify both redox and acid-base properties, whereas partial hydride substitutions for oxygen in LaSrCoO4 has provided a test-bed of hydrogenation activity.Tailoring the redox properties of the LaAlO3 mixed oxide by Co substitution has allowed to develop a multifunctional catalysts dealing with NOx and soot decontamination of diesel exhausts. NOx-assisted soot oxidation involves NO to NO2 conversion and subsequent soot oxidation by the formed NO2 at relatively low temperature. LaAlO3 materials with different degrees of Co substitution for Al were prepared by sol-gel method and their catalytic activity was correlated with crystallinity, redox properties and mobility of lattice oxygen. Among the studied samples LaAl1-xCoxO3 with x 0.75 exhibits superior catalytic activity for both NO to NO2 oxidation and NOx-assisted soot oxidation. The excellent performance is attributed to the synergetic interaction between Al-Co in B-site of the structure and may be linked to the high lattice surface oxygen supported by a well-crystallized perovskite structure.The production of bio-ethanol is one of the staples of the replacement of fossil fuels with renewable biomass-derived resources. Valorisation of bio-ethanol for the production of chemicals requires a fine control of the acid-base properties of catalysts. While most of the research on perovskite catalysts has focused on their redox properties, studies on their acid-base properties have been much less developed. Partial substitution of Co and Ga for Al in LaAlO3 has allowed to tune the acidity and basicity of the material and to control the relative activity of dehydration and dehydrogenation of ethanol, controlling the ratio between ethylene and acetaldehyde. The nature of the introduced cation allowed to form different Lewis acid-base pairs, orienting the reactivity of the acetaldehyde intermediates towards Tishchenko or aldol coupling, allowing to direct the reaction cascade towards the formation of butadiene or acetone and odd-C oxygenates.While most of the literature on perovskite reactivity has focused on their structure/properties modifications by cation substitutions, there is a limited number of works on substitutions in the anion sites. Oxyhydride perovskites, ABO3-xHx, where hydride anions H- can substitute O2- in any sites of the BO6 octahedron, have been reported presenting important hydride mobility, suggesting potential applications in hydrogenation catalysis. Oxyhydrides LaSrCoO3H0.7 and BaTiO3-xHx have been prepared, characterized and tested in a model hydrogenation reaction. The reactivity of hydride species has been tested using chemical titration of toluene at temperatures at which hydrides are expected to be mobile. The results show that LaSrCoO4-xHy exhibited a much higher activity than BaTiO3-xHx, due to the metallic sites formed by partial reduction of LaSrCoO4-xHy,, indicating a possible use of perovskites as support for hydrogenation catalysts

Le travail présenté dans cette thèse visait à étendre le champ d’applications de ligands calix[4]arèniques. La première partie de ce travail est consacrée à l’utilisation en milieu aqueux ou sans solvant de bis-phosphitecalix[4]arènes hémisphériques. La transposition de réactions catalytiques à ces milieux non usuels permet d’accroître l’activité du catalyseur par rapport à une utilisation en milieu organique classique. Utilisés en hydroformylation d'oléfines, ces ligands conduisent sélectivement à l'aldéhyde linéaire, la régiosélectivité du système étant principalement contrôlée par les propriétés intrinsèques du ligand. De même, la réaction d’hydroaminovinylation des α-oléfines catalysée par du rhodium conduit, en milieu totalement dépourvu de solvant, à des rapports produit linéaire/produit branché très élevés d’énamines/amines (à partir d’amines secondaires) et d’imines (à partir d’amines primaires). Dans les chapitres suivants, des calix[4]arènes portant un groupement PPh2 ou N=PPh2 comme seul groupe fonctionnel ont été testés en couplage croisé catalysé par du palladium et du nickel. Avec les bromures d’aryle, des activités remarquablement élevées ont été obtenues. La capacité de ces ligands à catalyser efficacement les réactions de formation de liaison C-C est liée d’une part à l’encombrement stérique de l'entité calixarényle, mais aussi à l’aptitude de ce fragment à piéger de manière supramoléculaire des entités métal-(π-arène). Ces deux propriétés sont de nature à favoriser la formation d’une espèce mono-ligand M(0)L(ArX) (M = Pd, Ni), l’étape d’addition oxydante devenant alors plus facile à partir d’une telle espèce qu’à partir d’une espèce M(0)L2
The aim of this work was to extend the scope of catalytic applications of ligands based on a calix[4]arene skeleton. The first part of this work focusses on new applications of hemispherical bis-phosphites calix[4]arenes in the rhodium catalysed hydroformylation of α-olefins, either in aqueous medium or under solvent-free conditions. These particular conditions resulted in enhanced activities compared to tests carried out in toluene. The ligands turned out to efficiently drive reactions towards the formation of linear products. The selectivity of the system is mainly controlled by the intrinsic properties of the ligand, which is able to tightly envelope the catalytic centre. In keeping with these observations, the application of solvent-free conditions to the rhodium-catalysed hydroaminovinylation of α-olefins resulted in high linear/branched ratios of enamines/amines (starting from secondary amines) or imines (starting from primary amines). In the following chapters, calix[4]arenes bearing a PPh2 or a N=PPh2 group as the sole functional group anchored at their upper rim were assessed in palladium or nickel-catalysed cross-coupling reactions. With arylbromides, these monodentate ligands led to remarkably high activities. The high performances probably arise from a combination of the bulkiness of the calixarenyl fragment as well as its ability to temporarely entrap metal-(η6-arene) moieties in a supramolecular fashion. Both properties favour the formation of mono-ligand intermediates M(0)L(ArX) (M = Pd, Ni), from which the following oxidative addition step is facilitated with respect to a step involving M(0)L2 species

Dans notre ère d'innovation technologique, la surface des matériaux
est le terrain d'expression de procédés de fonctionnalisation
puissants et souvent peu coûteux. Ces procédés, les propriétés ainsi
obtenues, ou souhaitées, suscitent une grande variété de
développements de nature fondamentale. Parmi ceux-ci, la mécanique
de surface allie physico-chimie de l'interface et réponse mécanique.

Je décris ici un ensemble de projets de recherche que j'ai
développés dans ce domaine. Je traite de la question du couplage
entre surfaces et de leurs interactions à longue portée, de
l'adhésion considérée tant du point de vue macroscopique que
microscopique et enfin de la nécessité de comprendre le matériau à
l'échelle locale pour maîtriser la réponse mécanique de systèmes de
structures complexes.

Ce travail a pour objectif de mettre au point de nouveaux radiosensibilisateurs et de nouvelles techniques de synthèse pour les radiosensibilisateurs basées sur les porphyrines cationiques bromées dans le but d'améliorer la radiothérapie utilisée en clinique. Ce mémoire se divise en deux parties; une concernant la synthèse de porphyrines bromées tétracationiques (quatre charges positives) et l'autre sur la synthèse et caractérisation des porphyrines bromées tricationiques (trois charges positives) dont l'étape clé est une réaction de couplage catalysée par le palladium. L'hypothèse de travail est que les porphyrines bromées cationiques augmentent la mort radio-induite des cellules cancéreuses en les rendant plus sujettes aux dommages causés par la radiation ionisante (rayon--X, rayon gamma). La première partie vise la synthèse de porphyrines tétracationiques bromées. Les bromes ont été ajoutés soit sur la partie centrale de la porphyrine, sur les chaînes en périphérie ou les deux à la fois. Différentes méthodes ont été utilisées pour ajouter les bromes sur la porphyrine et divers substituts ont été ajoutés pour changer le caractère hydrophobe de la molécule et par le fait même, l'accumulation intracellulaire. Les porphyrines qui sont pourvues de bromes situés en périphérie seulement démontrent un meilleur potentiel radiosensiblilisateur que les porphyrines qui possèdent des bromes sur leur centre ou sur le centre et sur les chaînes en même temps. La méthode de synthèse développée pour la porphyrine pourvue de bromes sur ses chaînes latérales consiste en une simple alkylation alors que les autres se font par bromination avec du brome liquide. La deuxième partie vise la mise au point d'une méthode de synthèse pour les porphyrines tricationiques basée sur une réaction de couplage catalysée par le palladium en milieu aqueux. En premier lieu, les porphyrines ont été bromées, mais leur faible solubilité n'a pas permis d'étudier leur potentiel radiosensibilisant. Diverses réactions ont été investiguées (Suzuki, Sonogashira, Heck, et réactions catalysées par le palladium impliquants les thiols, amines et phosphores) pour ajouter une chaîne de carbone hydrophobe à la molécule dans le but de constituer une librairie de porphyrines et ainsi, étudier les effets des substituants sur la biodistribution et leur potentiel photosensibilisant. En conclusion, ce travail démontre que les porphyrines tétracationiques bromées peuvent être d'excellentes candidates dans un futur traitement basé sur la radiosensibilisation. En plus de posséder un potentiel radiosensibilisant, les porphyrines tricationiques présentent des propriétés intéressantes pour de futures applications en thérapie photodynamique.

L'objectif de ce travail a ete de mettre au point une sonde de detection optique, a base de fibres en verre de chalcogenures, utilisable en milieu chimique et biologique. La composition selectionnee te 2as 3se 5 presente une transmission optique dans l'infrarouge de 1 a 18 m. Ce verre a ete prepare a l'etat de haute purete, homogeneise et recuit de facon a obtenir un barreau mecaniquement resistant, dont la surface a egalement ete polie chimiquement. A partir de ces preformes de haute qualite, des fibres de structure simple indice ont ete obtenues avec un minimum d'attenuation de 0,5 db/m dans la region 5,59,5 m. Le gainage de ces fibres par un polyamide fait passer ce minimum a 1 db/m autour de 9 m. L'efficacite de ces fibres pour la spectroscopie dite par onde evanescente a ete montree dans la region 2-12 m. L'absorbance de l'ethanol, par exemple, est proportionnelle a la longueur de fibre a son contact et a sa concentration dans l'eau. D'autre part, il a ete demontre que les fibres, lorsqu'elles sont effilees, possedent une meilleure configuration optique pour cette spectroscopie : l'absorbance de l'ethanol augmente fortement lorsque le diametre de la fibre diminue. Les fibres effilees alors utilisees comme capteurs avaient typiquement un profil en diametre de 450-120-450 m. Le probleme de l'absorption parasite du polymere protegeant les fibres a ete mis en evidence. Une sonde etroite, a reponse rapide a ete mise au point pour le suivi de reactions organiques activees par micro-ondes. Nous avons ainsi suivi la disparition de la cyclohexanone par la decroissance de sa bande c=o au cours du temps. Des tissus de foie de souris sains et pathologiques ont ete analyses par coloration histologique et par spectroscopie infrarouge. Deux pathologies ont ete etudiees : la surcharge en fer et le developpement de tumeur. La spectroscopie infrarouge a confirme les resultats des analyses histologiques, concernant la presence de steatose (exces de lipides) dans les tumeurs.

L'objet de cette thèse est la conception, le développement et la caractérisation d'un réacteur micro-ondes en continu pour mener tout type de réactions chimiques à températures élevées de manière fiable et dans des conditions optimisées. Le développement de ce réacteur a tout d'abord nécessité la caractérisation diélectrique et magnétique des matériaux et milieux utilisés. La simulation numérique a ensuite été utilisée afin de prédire les distributions de champ et température au sein des matériaux. L'interaction entre les ondes et les différents milieux a été finement étudiée. Elle démontre non seulement l'influence de la nature diélectrique du milieu réactionnel et du ratio volumique du fluide dans le réacteur sur le chauffage micro-ondes, mais aussi celle des dimensions de l'applicateur et de la disposition du réacteur dans ce dernier. L'hydrodynamique a également été introduite dans la simulation permettant de prédire les profils de température dans le réacteur en fonctionnement continu. L'ensemble des résultats numériques a fait l'objet de validations expérimentales qui ont aussi permis d'affiner le modèle thermique de l'ensemble conçu. Au final, une réaction de diestérification a été mise en œuvre et démontre l'efficacité thermique et chimique du réacteur. Au-delà de ce prototype, cette thèse établit un schéma général de conception d'un procédé chimique continu sous micro-ondes en ordonnant les étapes, respectant les règles clés de l'électromagnétisme, optimisant la propagation des ondes et les performances thermiques du système
The aim of this thesis is the development and characterisation of an intensified continuous microwave reactor for green chemistry. The development of this reactor required, at first, the characterisation of the dielectric and magnetic properties of the used materials. A numerical simulation was then used to predict the field and temperature profiles within the materials. The influence of different parameters on the microwave heating was also studied, such as the influence of the dielectric nature of the reaction medium, the ratio of the fluid in the reactor, the arrangement of the reactor in the applicator and the size and shape of the latter. Hydrodynamics were also taken into account in the simulation to predict the temperature profiles in the reactor. All the numerical results were validated experimentally. Experimental results also made it possible to refine the thermal model of the reactor. In the end, an esterification reaction was carried out and it proved the thermal and chemical efficiency of the designed reactor. Beyond this prototype, this thesis establishes a general scheme for the design of a continuous chemical process under microwaves whilst following the key rules of electromagnetism and optimising the wave propagation and the thermal performance of the reactor

De nombreux nucléosides modifiés sont rapportés dans la littérature comme ayant une activité antibactérienne, antitumorale ou antivirale. Parmi ces derniers, la BVDU, est utilisée pour lutter contre le virus de l'herpès. Dans l'optique de réaliser des analogues de ce composé nous avons mis au point des méthodes de synthèse de composés de type 5-aryl-2-désoxyuridine. La synthèse de tels composés est souvent décrite via des réactions organo-palladées mais dans des conditions mettant en jeu des solvants organiques. La mise au point d'une méthodologie de synthèse de ces composés via la réaction de Suzuki-Miyaura dans l'eau pure a été réalisée. Des analogues de type 5-aryluridine et 6-aryluridine ont été synthétisés en utilisant des conditions similaires. L'importance du ligand, très souvent utilisé dans ce type de réaction, a été remise en cause, car nous avons montré que les composés peuvent être obtenus avec de très bon rendements en son absence. L'activation par irradiation micro-ondes a aussi été utilisée. Elle a permis d'obtenir les produits de couplage avec de bons rendements dans des temps de réactions très courts. En parallèle de ces travaux, dans l'optique d'une collaboration avec un laboratoire indien, la synthèse de composés de type5-allyluridine et 5-alllyl-2'-désoxyuridine a été étudiée
Many nucleosides analogues are reported in literature as antitumor, antibacterial or antiviral. Among them, the BVDU, is used as a drug against the herpes virus. In order to synthesize derivates of this compounds, we decided to develop new synthetic routes of 5-aryl-2'-deoxyrudine analogues. The synthesis of such compounds is widely described in literature using cross-coupling reaction with palladium but they often use organic solvents. A methodology to synthesize these analogues using the Suzuki-Miyaura reaction, in water, has been developed. 5-aryluridine and 6-aryluridine derivates were also synthetized using a similar methodology. The relevance of the ligand, commonly used in organo-palladated reactions, was studied. In our hands, the target compounds were obtained in good yiels using a free ligand methodology. Micro-wave activation was also studied. It allowed the synthesis of the nucleosides in good yields within very short reaction times. In collaboration with an Indian laboratory, the synthesis of 5-allyluridine and 5-allyl-2'-deoxyuridine was studied