Manipulation and Optical Detection of Colloidal Functional Plasmonic Nanostructures in Microfluidic Systems

The very strong optical resonances of plasmonic nanostructures can be harnessed for sensitive detection of chemical and biomolecular analytes in small volumes. Here we describe an approach towards optical biosensing in microfluidic systems using plasmonic structures (functionalized gold nanoparticles) in colloidal suspension. The plasmonic nanoparticles provide the optical signal, in the form of resonant light scattering or absorption, and the microfluidic environment provides means for selectively manipulating the nanoparticles through fluid dynamics and electric fields. In the first part we discuss recent literature on functionalized colloidal particles and the methods for handling them in microfluidic systems. Then we experimentally address aspects of nanoparticle functionalization, detection through plasmonic resonant light scattering under dark-field illumination and the electrokinetic behavior of the particles under the action of an alternating electric field

Listeria monocytogenes in Milk Products

peer-reviewedMilk and milk products are frequently identified as vectors for transmission of Listeria monocytogenes. Milk can be contaminated at farm level either by indirect external contamination from the farm environment or less frequently by direct contamination of the milk from infection in the animal. Pasteurisation of milk will kill L. monocytogenes, but post-pasteurisation contamination, consumption of unpasteurised milk and manufacture of unpasteurised milk products can lead to milk being the cause of outbreaks of listeriosis. Therefore, there is a concern that L. monocytogenes in milk could lead to a public health risk. To protect against this risk, there is a need for awareness surrounding the issues, hygienic practices to reduce the risk and adequate sampling and analysis to verify that the risk is controlled. This review will highlight the issues surrounding L. monocytogenes in milk and milk products, including possible control measures. It will therefore create awareness about L. monocytogenes, contributing to protection of public health

Optical extinction and scattering cross sections of plasmonic nanoparticle dimers in aqueous suspension

Absolute extinction and scattering cross sections for gold nanoparticle dimers were determined experimentally using a chemometric approach involving singular-value decomposition of the extinction and scattering spectra of slowly aggregating gold nanospheres in aqueous suspension. Quantitative spectroscopic data on plasmonic nanoparticle assemblies in liquid suspension are rare, in particular for particles larger than 40 nm, and in this work we demonstrate how such data can be obtained directly from the aggregating suspension. Our method can analyse, non invasively, the evolution of several sub-populations of nanoparticle assemblies. It may be applied to other self-assembling nanoparticle systems with an evolving optical response. The colloidal systems studied here are based on 20, 50 and 80 nm gold nanospheres in aqueous solutions containing sodium lipoate. In these systems, the reversible dimerisation process can be controlled using pH and ionic strength, and this control is rationalised in terms of DLVO theory. The dimers were identified in suspension by their translational and rotational diffusion through scattering correlation spectroscopy. Moreover, their gigadalton molecular weight was measured using electrospray charge-detection mass spectrometry, demonstrating that mass spectrometry can be used to study nanoparticles assemblies of very high molecular mass. The extinction and scattering cross sections calculated in the discrete-dipole approximation (DDA) agree very well with those obtained experimentally using our approach

Remote Monitoring of Positive Airway Pressure Data Challenges, Pitfalls, and Strategies to Consider for Optimal Data Science Applications

Over recent years, positive airway pressure (PAP) remote monitoring has transformed the management of OSA and produced a large amount of data. Accumulated PAP data provide valuable and objective information regarding patient treatment adherence and efficiency. However, the majority of studies that have analyzed longitudinal PAP remote monitoring have summarized data trajectories in static and simplistic metrics for PAP adherence and the residual apnea-hypopnea index by the use of mean or median values. The aims of this article are to suggest directions for improving data cleaning and processing and to address major concerns for the following data science applications: (1) conditions for residual apnea-hypopnea index reliability, (2) lack of standardization of indicators provided by different PAP models, (3) missing values, and (4) consideration of treatment interruptions. To allow fair comparison among studies and to avoid biases in computation, PAP data processing and management should be conducted rigorously with these points in mind. PAP remote monitoring data contain a wealth of information that currently is underused in the field of sleep research. Improving the quality and standardizing data handling could facilitate data sharing among specialists worldwide and enable artificial intelligence strategies to be applied in the field of sleep apnea

Black spot diseases in seven commercial fish species from the English Channel and the North Sea: infestation levels, identification and population genetics of Cryptocotyle spp.

Fish are often speckled with “black spots” caused by metacercarial trematode infection, inducing a host response. Cryptocotyle spp. (Opisthorchiidae) are among the parasites responsible for this phenomenon. So far, the impact on human health is still unknown. In addition, few publications dealing with black spot recovery, identification, distribution and diversity among commercially important fish are available. Moreover, “black spots” have been observed by fishermen on marine fish, revealing an appreciable but unquantified presence in consumed fish. An epidemiological survey of 1,586 fish from seven commercial species (herring, sprat, whiting, pout, dab, flounder, and plaice) was conducted in the Eastern English Channel and the North Sea in January 2019 and 2020. Encysted metacercariae were found in 325 out of 1,586 fish, with a total prevalence of 20.5%. Intensity of infection varied from 1 to 1,104 parasites. The recorded encysted metacercariae were identified either by microscopic examination or with molecular tools. Partial sequences of the mtDNA cox1 gene and of the rDNA ITS region were obtained. Two species of Cryptocotyle, Cryptocotyle lingua (Creplin, 1825) and Cryptocotyle concava (Creplin, 1825) were found. Metacercariae belonging to other trematode families were also identified. Molecular phylogenetic analysis and haplotype network construction were performed to confirm the identification and to study the potential presence of different populations of Cryptocotyle spp. This survey enabled us to describe the distribution of two species of Cryptocotyle in the English Channel and North Sea ecosystems. The observed differences in infestation levels between fish species and geographical areas will contribute to better understanding of the ecology of these parasites

Developing application and detection methods for Listeria monocytogenes and fish extract on open surfaces in order to optimize cleaning protocols

© 2014 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved. Surfaces in the food industry are often fouled with bacteria and organic materials. A range of fouling and testing methods using two Listeria monocytogenes strains (Scott A and N53-1) and organic material (0.4 g/ml fish extract) were designed to determine the efficacy of two different cleaning methods (spray and wipe) in 1% sodium hypochlorite. The optimum method for applying the cells and organic material to substrata occurred when the cells and organic material were mixed together, dried onto the surface and stained. As the number of cleaning and re-foulings increased, cells were removed from the surfaces but the organic material remained. The pattern of organic material retention was different on the surfaces with the different cleaning protocols, but neither method was better at removing the retained organic material. More cells were removed from the surfaces by the spray than the spray with wipe clean. There was no difference in cell number retention for either of the L. monocytogenes strains. These findings are valid for a 'dirty material' as classified in BS EN1276. To determine cleaning method efficacy, the application of cells and organic material to a surface is important, as is the detection methods used

Élèves d'ULIS, penser l'orientation dés la première année

National audienceLe dispositif UPI (Unité Pédagogique d’Intégration) est implanté depuis 6 ans au sein du Lycée Clément Ader à Bernay. Il accueille des jeunes présentant des troubles des fonctions cognitives. L’équipe est composée d’une coordinatrice (titulaire du 2CA-SH), d’un professeur des écoles spécialisé (titulaire du CAPA-SH option D) et d’une AVS. Plusieurs enseignants du second degré prennent en charge les élèves du dispositif notamment en Anglais, en PSE, en EPS, en atelier Cuisine, en Mathématiques/Sciences, en Français/Histoire/Géographie, en documentation.Si le nom change d’UPI à ULIS (Unité Localisée pour l’Inclusion Scolaire) à partir de la rentrée 20101, l’équipe en charge du dispositif reste la même.Présente sur le dispositif depuis trois ans maintenant, j’ai suivi l’évolution de ces jeunes qui, arrivés tous en même temps lors de la création du dispositif et ayant sensiblement le même âge, se rapprochent peu à peu de la sortie du système scolaire

Traitement du syndrome d'apnée obstructive du sommeil par pression positive continue : étude des données de télésuivi pour comprendre l'impact des modifications du traitement et prédire les évènements aigus

Sleep apnea is one of the most frequent chronic diseases affecting nearly one billion people worldwide. The reference treatment for obstructive sleep apnea is continuous positive airway pressure (CPAP). The most widely used index for monitoring sleep apnea resolution under CPAP is the residual apnea-hypopnea index (rAHI) which quantifies the number of central and obstructive apneas and hypopneas per hour of sleep persisting under CPAP. This measurement is provided every night through remote monitoring platforms in millions of patients. There is a growing interest of care givers to use this information for early identification of treatment failures and incident acute or chronic cardiovascular events. The work presented in this thesis aims at identifying data science methods and mathematical models to better understand and automatically analyze the time series of rAHI and airflow, and demonstrate the clinical relevance of the indicators resulting from these algorithms.First, we formulated recommendation for pre-processing and cleaning of CPAP telemonitoring data. We developed a method to extract features from rAHI times series and identify clusters of trajectories.Then, we focused on the deviations of the rAHI from its expected trajectory. We identified a time series forecast model with synthetic controls to evaluate the impact of setting and mask on the evolution of the rAHI. We realized a comparative analysis of changepoint detection methods to identify a method generalizable to all patients to raise relevant alerts.Also, the goal of this thesis was to understand the relationship between telemonitoring data and comorbidities. On the one hand, we characterized the clinical profiles associated to clusters of rAHI trajectories. On the other hand, we developed a framework to extract relevant features from raw airflow signal of Cheyne-Stokes respiration in order to identify the specific features associated to the presence of heart failure.Our work paves the way for building shared clinical and technical databases with the parallel collection of both CPAP telemonitoring data and acute events information. This would allow the training of multi-dimensional multi-scale algorithms to predict the occurrence of acute events.Le syndrome d’apnées-hypopnées obstructives du sommeil (SAHOS) est une maladie chronique multi-organe et multifactorielle qui touche plusieurs millions de personnes en France et s’accompagne souvent de comorbidités cardiovasculaires. Environ 1.4 million de personnes en France sont traitées par pression positive continue (PPC). Ce traitement connecté génère quotidiennement de gros volumes de données depuis plusieurs années. Ces données permettent notamment de suivre l’observancedu patient au traitement et l’efficacité du traitement selon les réglages. Cependant, les méthodes de science des données sont à ce jour peu mobilisées pour extraire toute l’information pertinente contenue dans ces données et seul l'index apnées-hypopnées résiduel (IAHr) moyen est utilisé pour quantifier l'efficacité du traitement. Les travaux menés au cours de cette thèse consistent en l’identification deméthodes permettant la compréhension et l’analyse automatique des séries temporelles d’événements respiratoires résiduels et de débit aérien, et l’évaluation de la pertinence clinique des indicateurs issusde ces algorithmes.Tout d’abord, cette thèse a visé à mieux comprendre les données d’IAHr. D’une part, nous avons identifié les facteurs de variation de l’IAHr à contrôler dans touteanalyse. Puis, une méthode a été développée pour changer la représentation des séries temporellesafin d’identifier des clusters de trajectoires d’évolution de l’IAHr.Dans la suite de cette thèse, nous nous sommes intéressés aux déviations de l’IAHr de sa trajectoire habituelle.D'une part, nous avons identifié un modèle de prévision de séries temporelles avec contrôles synthétiques pour évaluer automatiquement l'impact d'un changement de réglage sur l'évolution de l'IAHr, avec comme cas d'usage le changement de masque. D'autre part, une analyse comparative des méthodes de détection de points de changement a été réalisée pour identifier une méthode généralisable à tous les patients pour lever des alertes pertinentes.Enfin, cette thèse a visé à comprendre le lien entre les données de télésuivi et les comorbidités des patients. Dans un premier temps, nous avons caractérisé les profils cliniques associés aux clusters de trajectoires d'IAHr. Dans un second temps, nous avons identifié une méthode d'extraction de caractéristiques du signal de débit aérien enregistré par la PPC en présence de respirations de Cheyne Stokes, afin d'identifier des caractéristiques spécifiques en présence d'insuffisance cardiaque.Nous avons montré que les données de télésuivi de PPC sont porteuses d’information pertinente etque l’utilisation de méthodes avancées d’analyse de données permet d’en extraire toute l’information.Des analyses prospectives seront nécessaires pour valider les algorithmes d’alertes et la pertinence des indicateurs calculés. Ces travaux ouvrent la voie à des analyses de données multi-dimensionnelles multi-échelles pour prédire la survenue d’événements aigus

Dielectrophoresis of nanoparticles in microfluidic systems ˸ investigation using digital video microscopy and application to optical spectroscopic analysis

La manipulation de micro- et nano- particules en solution peut être réalisée grâce aux interactions de ces objets avec des champs électromagnétiques. La lumière ou bien encore les champs électriques continus (DC) ou alternatifs (AC) peuvent être utilisés. Dans le cas d’un champ électrique non uniforme appliqué entre deux électrodes séparées par quelques micromètres, des gradients de champs très intenses et localisés sont ainsi créés. Ces gradients de champ localisés au niveau des électrodes engendrent la création de mouvements de charges composant la solution (effets électro-hydrodynamique). Mais aussi des charges confinées au niveau des particules à l’interface liquide/solide. Les particules en suspension subissent alors une force attractive ou répulsive appelée diélectrophorèse. Cette force est décrite dans la littérature pour des particules isolantes de taille supérieure à 200 nm. Dans cette étude par détection optique (videomicroscopie par champ sombre ou spectroscopie en microfluidique) la gamme de taille de particules est élargie (40-150 nm) pour étudier leurs réponses diélectrophorètique. En effet la diélectrophorèse dépend de la taille des particules, de son environnement et des paramètres du champ appliqué (fréquence, amplitude, topologie) La diélectrophorèse est mise en compétition avec le mouvement Brownian pour des particules d’or d’aussi petites tailles. La réponse pour des nanoparticules d’or en solution alors connue, il est envisageable de faire varier les paramètres, comme l’environnement de la particule ou bien la complexité des systèmes étudiés.The manipulation of micro- and nano- particles in solution can be achieved through the interactions of these objects with electromagnetic fields. Emitted light, continuous (DC) or alternating (AC) electric fields can be used. In the case of a non-uniform electric field applied between two electrodes separated by a few micrometers, very intense and localized field gradients are created. These field gradients localised close to the electrodes generates a motion of the mass solution (electro-hydrodynamic effects). The charges confined onto particles at the liquid/solid interface are also subjected to motion. Suspended particles undergo an attractive or repulsive force called dielectrophoresis.This force is described in the literature for insulating particles larger than 200 nm. In this study optical detection was used (dark field videomicroscopy or microfluidic spectroscopy) to expand the range of particle size (40-150 nm) and to study their dielectrophoretic responses. Indeed, the dielectrophoresis is dependent on the size of particles, their environment and the parameters of the applied electric field (frequency, amplitude, topology). The dielectrophoresis is in competition with the Brownian motion of these gold nanoparticles. By, knowing the dielectrophoretic response of these particles in solution, it is possible to vary parameters, such as the suspension composition of the particles or the complexity of the systems studied