Extraction and analysis of plant volatiles

Mestrado de dupla diplomação com a Université Libre de TunisAs worldwide population is growing, the demand on food increases exponentially, which results in food overproduction, food spoilage, and in foodborne diseases. This issue has arisen many concerns related to public health, economy, and the environment, which led to exhaustive research on possible solutions to minimize costs and ensure safer food products that respond to consumers’ demand for clean-label foods with less collateral damages on the environment. Essential oils (E.Os) and volatiles are plant secondary metabolites and are considered as promising food preservatives seen their remarkable biological activities including antioxidant, antimicrobial, antiproliferative, and anti-inflammatory activities. E.Os from three aromatic plants: eucalyptus (Eucalyptus globulus Labill.), peppermint (Mentha x piperita L.), and pine (Pinus pinaster) were extracted by hydro distillation (HD) and microwave-assisted hydro distillation (MAHD), both optimized with response surface methodology (RSM), which generally showed higher yields in E.Os obtained with MAHD influenced primarily by solid/liquid ratio, with eucalyptus giving the highest yield from the three studied plants. Chromatographic identification resulted in high amounts of monoterpenes, followed by sesquiterpenes in both eucalyptus and peppermint E.Os, while pine E.O was proven to be richer in diterpenes. These volatile compounds led to interesting bioactive properties in all of the studied E.Os, especially the ones extracted using hydro distillation. The extracts showed an inhibitory capacity against the majority of the tested bacterial strains, specifically against Methicillin-resistant Staphylococcus aureus (MRSA), which is a multi- resistant bacteria. Also, a remarkable antifungal activity against Aspergillus brasiliensis and Aspergillus fumigatus. In terms of antiproliferative activity, the E.Os extracted through HD demonstrated higher tumoral cell growth inhibition against the majority of the studied cancer cell lines, with pine E.O standing out with the lowest GI50 value, and none of the tested E.O showed cytotoxicity against normal cell line studied in this case (PLP2). The E.Os also revealed an anti-inflammatory capacity that stood out mainly with those extracted using HD. This work highlights the promising use of essential oils as headspace preservatives for food packaging.Com o crescimento da população mundial, a necessidade de alimentos aumenta exponencialmente, o que resulta em sobreprodução de alimentos, desperdícios e doenças transmitidas por alimentos. Esta questão tem despertado muitas preocupações relacionadas com a saúde pública, economia e meio ambiente, o que levou a investigação sobre possíveis soluções para minimizar custos e garantir produtos alimentares mais seguros e que atendam à procura dos consumidores por alimentos sustentáveis e com menos danos ao ambiente. Os óleos essenciais (O.Es) e moléculas voláteis são metabolitos secundários de plantas e são considerados conservantes de alimentos promissores devido às suas notáveis atividades biológicas, incluindo atividades antioxidantes, antimicrobianas, antiproliverativas, e anti- inflamatórias O.Es de três plantas aromáticas: eucalipto (Eucalyptus globulus Labill.), hortelã-pimenta (Mentha x piperita L.) e pinheiro (Pinus pinaster L. ) foram extraídos por hidrodestilação (HD) e hidrodestilação assistida por microondas (MAHD), ambas otimizada com a metodologia de superfície de resposta (RSM), que apresentou geralmente maiores rendimentos em O.Es. obtidos com MAHD influenciados principalmente pela relação sólido/líquido, onde o eucalipto apresentou o maior rendimento das três plantas estudadas. A identificação cromatográfica resultou em altas quantidades de monoterpenos, seguidos de sesquiterpenos em O.Es de eucalipto e hortelã-pimenta, enquanto o O.E. de pinheiro provou ser mais rico em diterpenos. Esses compostos voláteis levaram a interessantes propriedades bioativas em todos os E.Os estudados, especialmente os extraídos por hidrodestilação. Os extratos mostraram capacidade inibitória contra a maioria das bacterias testadas, especificamente contra Staphylococcus aureus resistente à meticilina (MRSA), que é uma bactéria multirresistente. Além disso, uma notável atividade antifúngica foi detetada contra Aspergillus brasiliensis e Aspergillus fumigatus. Em termos de atividade antiproliferativa, os O.Es extraídos por HD demonstraram maior inibição do crescimento de células tumorais contra a maioria das linhagens de células cancerígenas estudadas, destacando-se o O.E. de pinheiro com o menor valor de GI50, e nenhum dos O.E. testados apresentou citotoxicidade contra a linha não tumoral estudada (PLP2). Os O.E. também revelaram uma capacidade anti-inflamatória que se destacou principalmente com os extraídos com HD. Este estudo revela uma boa possibilidade dos óleos essenciais poderem vir a ser estudados como conservantes alimentares em embalagens alimentares

The Determinants of Financial Covenants on Private Debt: The Case of Listed French Companies

The purpose of this paper is to identify factors that influence financial covenants in private debt agreements of listed French companies. We test whether borrower characteristic influence the presence of financial covenants in debt contract. Using a sample of large listed French firms over the period of 2003-2009, we find that profitable firms with growth options are likely to include financial covenants on their syndicated private debt. We also test whether debt characteristic influence the financial covenants in private debt. We find that type of debt and security dummy influence significantly financial covenants. Our results are consistent with prior studies in general. Keywords: financial covenants, private debt, borrower characteristic, debt characteristi

Supply chain cybersecurity and the implementation of blockchain technology

The same information that has massively contributed the evolution of the supply chain productivity for both private and public entities is the same posing companywide cybersecurity threats that has been on the rise due to the digitalization of multiple aspects of the supply chain and the lack of security protocols in thereof. Information and Communication Technologies (ICT) are essential for the flow of goods and services from the starting point until it reaches the end customer. Yet, cybersecurity has not been on the spotlight when it came to supply chain disruptions as much as terrorist attacks or global pandemics despite having the potential to inflict severe damage. Luckily, the evolution of these threats came in parallel with the evolution of technologies that can help prevent and minimize them with blockchain showcasing its ability to ensure transparency along the blockchain, fraud detection and ensuring a time and cost-efficient process. This research will discuss the application of Blockchain technologies in the supply chain network, its horizons and some of its setbacks

Sphincter artificiel contrôlé et alimenté en énergie sans fil

RÉSUMÉ L’incontinence urinaire est un trouble qui touche aussi bien les hommes que les femmes, les personnes âgées aussi bien que les jeunes. N’ayant pas une définition universellement admise, son incidence varie considérablement. Être incontinent implique l’impossibilité pour la personne de se retenir. Cela la place dans des situations très inconfortables. Appelée aussi « La maladie de la honte », elle a des répercussions psychologiques et sociales très importantes. Elle peut limiter les activités physiques et perturber la vie sexuelle et professionnelle. Grâce à la médecine moderne l’incontinence est soignable. Elle est initialement traitée avec la médication, l’hygiène de vie, ou la rééducation. Mais si ces mesures sont insuffisantes, l’urologue fait le plus souvent appel aux dispositifs implantables tels que l’AMS 800™. En l’état actuel des connaissances, l’implantation du sphincter urétral artificiel AMS 800™ est en effet le traitement standard pour l’incontinence urinaire sévère (Gold standard) due à une insuffisance sphinctérienne. Le dispositif en question est un implant hydromécanique mimant le comportement d’un sphincter urétéral sain. Il exerce une pression constante sur l’urètre du patient pour fermer sa lumière et garder l’urine dans la vessie. Pour uriner, le patient contrôle l’ouverture de son urètre en pressant sur une pompe manuelle située dans le scrotum ou la Labia Majora. Malgré le principe simple et l’efficacité de cet implant, les études cliniques lui attribuent certaines limitations. Certains patients à dextérité réduite (Parkinsoniens, âgés, obèses, etc.) ont des difficultés à localiser et actionner la pompe manuelle. Par ailleurs et bien que faisable chez les femmes, l’implantation de l’AMS 800 est compliquée. La pression constante appliquée sur l’urètre provoque l’atrophie et l’érosion. La pompe est sujette à des pannes mécaniques. Ces évènements peuvent engendrer le retour de l’incontinence, affecter la qualité de vie du patient, et nécessiter une chirurgie de révision. L’objectif de nos recherches est de développer une nouvelle génération de sphincters artificiels intelligents, dans le but de corriger ces limitations, et développer les capacités des sphincters actuels dont la conception est âgée de plus de 30 ans.---------- ABSTRACT Urinary incontinence is a complication that affects both men and women, the elderly as well as young people. Without a universally accepted definition, its incidence varies widely. Being incontinent implies the impossibility for the patient to control his micturition, which makes him very uncomfortable. Also called "the shameful disease", urinary incontinence has negative psychological and social impacts. It may limit physical activities and disrupt sexual and professional life. Thanks to modern medicine, urinary incontinence is treatable. It is initially treated with medication, lifestyle changes, or rehabilitation. If these measures are insufficient, the urologist recommends the use of implantable devices such as the AMS 800 ™. In the current state of knowledge, the implantation of the artificial urinary sphincter AMS 800 ™ is the gold standard treatment for severe urinary incontinence due to intrinsic sphincter deficiency. This device is a hydro-mechanical implant imitating the behavior of a healthy urethral sphincter. It exerts a constant pressure on the patient's urethra to close it, and keeps urine in the bladder. To urinate, the patient opens his urethra by pressing a manual pump located in the scrotum or Labia Majora. Despite the simple mechanism and the effectiveness of this implant, clinical studies report certain limitations. Some patients with limited dexterity (Parkinson, aged, obese, etc.) have difficulties to locate and operate the manual pump. Furthermore and although it is feasible in women, the implantation of the AMS 800 is complicated. The constant pressure applied on the urethra causes atrophy and erosion. The pump is subject to mechanical failure. These events can cause the return of incontinence, affect the patient's quality of life, and may require revision surgery. The aim of our research is to develop a new generation of intelligent artificial sphincters, in order to correct the limitations and extend the capabilities of current sphincters that are over 30 years old. Our hypothesis assumes that, an artificial urinary sphincter equipped with embedded electronics and precise micro-actuators allows the remote control of the implant and the variation of the pressure exerted on the urethra

Méthodes de sous-espaces de Krylov matriciels appliquées aux équations aux dérivées partielles

Cette thèse porte sur des méthode de résolution d'équations matricielles appliquées à la résolution numérique d'équations aux dérivées partielles ou des problèmes de contrôle linéaire. On s'intéressen en premier lieu à des équations matricielles linéaires. Après avoir donné un aperçu des méthodes classiques employées pour les équations de Sylvester et de Lyapunov, on s'intéresse au cas d'équations linéaires générales de la forme M(X)=C, où M est un opérateur linéaire matriciel. On expose la méthode de GMRES globale qui s'avère particulièrement utile dans le cas où M(X) ne peut s'exprimer comme un polynôme du premier degré en X à coefficients matriciels, ce qui est le cas dans certains problèmes de résolution numérique d'équations aux dérivées partielles. Nous proposons une approche, noté LR-BA-ADI consistant à utiliser un préconditionnement de type ADI qui transforme l'équation de Sylvester en une équation de Stein que nous résolvons par une méthode de Krylox par blocs. Enfin, nous proposons une méthode de type Newton-Krylov par blocs avec préconditionnement ADI pour les équations de Riccati issues de problèmes de contrôle linéaire quadratique. Cette méthode est dérivée de la méthode LR-BA-ADI. Des résultats de convergence et de majoration de l'erreur sont donnés. Dans la seconde partie de ce travail, nous appliquons les méthodes exposées dans la première partie de ce travail à des problèmes d'équations aux dérivées partielles. Nous nous intéressons d'abord à la résolution numérique d'équations couplées de type Burgers évolutives en dimension 2. Ensuite, nous nous intéressons au cas où le domaine borné est choisi quelconque. Nous établissons des résultats théoriques de l'existence de tels interpolants faisant appel à des techniques d'algèbre linéaire.This thesis deals with some matrix equations involved in numerical resolution of partial differential equations and linear control. We first consider some numerical resolution techniques of linear matrix equation. In the second part of this thesis, we apply these resolution techniques to problems related to partial differential equations.DUNKERQUE-SCD-Bib.electronique (591839901) / SudocSudocFranceF

Changing Mad2 Levels Affects Chromosome Segregation and Spindle Assembly Checkpoint Control in Female Mouse Meiosis I

The spindle assembly checkpoint (SAC) ensures correct separation of sister chromatids in somatic cells and provokes a cell cycle arrest in metaphase if one chromatid is not correctly attached to the bipolar spindle. Prolonged metaphase arrest due to overexpression of Mad2 has been shown to be deleterious to the ensuing anaphase, leading to the generation of aneuploidies and tumorigenesis. Additionally, some SAC components are essential for correct timing of prometaphase. In meiosis, we and others have shown previously that the Mad2-dependent SAC is functional during the first meiotic division in mouse oocytes. Expression of a dominant-negative form of Mad2 interferes with the SAC in metaphase I, and a knock-down approach using RNA interference accelerates anaphase onset in meiosis I. To prove unambigiously the importance of SAC control for mammalian female meiosis I we analyzed oocyte maturation in Mad2 heterozygote mice, and in oocytes overexpressing a GFP-tagged version of Mad2. In this study we show for the first time that loss of one Mad2 allele, as well as overexpression of Mad2 lead to chromosome missegregation events in meiosis I, and therefore the generation of aneuploid metaphase II oocytes. Furthermore, SAC control is impaired in mad2+/− oocytes, also leading to the generation of aneuploidies in meiosis I