Multimodal wide-field two-photon excitation imaging: characterization of the technique for in vivo applications

We report fast, non-scanning, wide-field two-photon fluorescence excitation with spectral and lifetime detection for in vivo biomedical applications. We determined the optical characteristics of the technique, developed a Gaussian flat-field correction method to reduce artifacts resulting from non-uniform excitation such that contrast is enhanced, and showed that it can be used for ex vivo and in vivo cellular-level imaging. Two applications were demonstrated: (i) ex vivo measurements of beta-amyloid plaques in retinas of transgenic mice, and (ii) in vivo imaging of sulfonated gallium(III) corroles injected into tumors. We demonstrate that wide-field two photon fluorescence excitation with flat-field correction provides more penetration depth as well as better contrast and axial resolution than the corresponding one-photon wide field excitation for the same dye. Importantly, when this technique is used together with spectral and fluorescence lifetime detection modules, it offers improved discrimination between fluorescence from molecules of interest and autofluorescence, with higher sensitivity and specificity for in vivo applications

Optimisation de la loi de calage d’un propulseur cycloïdal

Les propulseurs cycloïdaux sont caractérisés par la rotation de plusieurs pales autour d’un axe vertical, associée à un mouvement de chaque pale autour de son axe propre. L’objet de cet article concerne l’étude des lois de calage d’un propulseur à axe transverse dans le domaine de la propulsion cycloïdale navale. Avec ce type de propulsion, deux modes de cinématiques sont observés : le mode épicycloïdal utilisé pour les basses vitesses d’avance de navire (1). L’objectif final est de pouvoir établir des lois de calage, pour chacun des deux modes, maximisant l’effort propulsif. Les lois de calage sont d’abord définies cinématiquement par une approche quasi statique en utilisant la base de données SANDIA. Pour un paramètre d’avance particulier (=1,6), la loi de calage est corrigée par un processus itératif afin de prendre en compte la dynamique de l’écoulement au sein de la turbine par un calcul URANS 2D. Les lois de calage sont ensuite approchées par des fonctions paramétrables, afin de permettre leur optimisation par une méthode d’optimisation par processus Gaussiens (EGO). Dans le but de diminuer le temps d’optimisation EGO et de mieux comprendre l’influence des paramètres dans le processus d’optimisation, une périodicité et une non parité sont imposées pour ces fonctions à 2 ou 3 paramètres. Le processus d’optimisation est mis en œuvre sur l’approche quasi statique pour valider la méthode. Des essais futurs dans le bassin du centre Ifremer de Boulogne-sur-Mer avec la plateforme académique SHIVA seront mis en place pour une optimisation expérimentale des lois de calage pour les deux modes de fonctionnement. Cycloidal propulsors are characterized by the rotation of several blades around a vertical axis, associated with a movement of each blade around its own axis. The purpose of this article is to study the pitch laws of a transverse axis propulsor in the field of cycloidal marine propulsion. With this type of propulsion, two kinematic modes are observed: the epicycloidal mode used for low ship speeds (1). The final aim is to be able to establish pitch laws, for each of those two modes, maximizing thrust. The pitch laws are first defined kinematically by a quasi-static approach using the SANDIA database. For a particular advance parameter (=1,6), the pitch law is corrected by an iterative process in order to take into account the flow dynamics within the turbine by a 2D URANS calculation. The pitch laws are then modeled by configurable functions, in order to allow their optimization using surrogate-model based optimization methods (EGO). In order to reduce the EGO optimization time and to better understand the influence of parameters in the optimization process, a periodicity and odd parity are imposed for these 2 or 3-parameter functions. The optimization process is implemented on the quasi-static approach to validate the method. Future tests in the facilities of the Ifremer center in Boulogne-sur-Mer with the SHIVA academic platform will be conducted for an experimental optimization of the pitch laws for the two operating modes

Analyse expérimentale et simulations numériques de l'interaction fluide-structure d'un hydofoil élastique en écoulements subcavitant et cavitant

Le développement de structures portantes flexibles dans le domaine naval, telles que les hélices ou les safrans, pose de nouveaux problèmes de dimensionnement. Cette thèse a pour but de développer une méthode de dimensionnement validée par des essais pour des structures portantes déformables soumises à des écoulements, éventuellement diphasiques de type cavitant. Les essais sont réalisés sur un hydrofoil de type NACA66-312(mod.), fabriqué en polyacetate, au sein du tunnel hydrodynamique de l'Institut de Recherche de l'Ecole Navale. Lors des essais, des mesures de déformations du profil portant ainsi que de niveaux vibratoires sont réalisées. Une méthode numérique couplant un code structure éléments finis (ANSYS Mechanical) avec un code fluide volumes finis (ANSYS CFX) par une méthode partitionnée, itérative, synchrone et séquentielle, laquelle est validée en terme de prédiction du déplacement et des contraintes pour des écoulements subcavitants dans un premier temps, puis pour des écoulements cavitants stables et instables.The design of flexible lifting bodies in the naval industry, such as propelleror rudders, create some new design problems. This thesis proposes a numerical method validated by experimental comparison for solving the case of lifting bodies loaded by flow with or whitout cavitation. The tests are carried out in the hydrodynamic tunnel of the French Naval Academy Research Institute, on a polyacetate flexible hydrofoil NACA66-312 (mod.). During tests, strains and vibrations are measured for comparisons with numerical results. The numerical method uses a sequential synchrone iterative partitionned coupling betweena structural finite-element code (ANSYS Mechanical) and a finite-volume code (ANSYS CFX). Good agreement between numerical and experimental results for displacements, and stresses of the structure is highlighted. For the cavitating flow, a good agreement for the cavitation dynamic is observed and the stresses are evaluated with satisfying accuracy.PARIS-Arts et Métiers (751132303) / SudocSudocFranceF

In vivo structural imaging of the cornea by polarization-resolved second harmonic microscopy

The transparency and mechanical strength of the cornea are related to the highly organized three-dimensional distribution of collagen fibrils. It is of great interest to develop specific and contrasted in vivo imaging tools to probe these collagenous structures, which is not available yet. Second Harmonic Generation (SHG) microscopy is a unique tool to reveal fibrillar collagen within unstained tissues, but backward SHG images of cornea fail to reveal any spatial features due to the nanometric diameter of stromal collagen fibrils. To overcome this limitation, we performed polarization-resolved SHG imaging, which is highly sensitive to the sub-micrometer distribution of anisotropic structures. Using advanced data processing, we successfully retrieved the orientation of the collagenous fibrils at each depth of human corneas, even in backward SHG homogenous images. Quantitative information was also obtained about the submicrometer heterogeneities of the fibrillar collagen distribution by measuring the SHG anisotropy. All these results were consistent with numerical simulation of the polarization-resolved SHG response of cornea. Finally, we performed in vivo SHG imaging of rat corneas and achieved structural imaging of corneal stroma without any labeling. Epi-detected polarization-resolved SHG imaging should extend to other organs and become a new diagnosis tool for collagen remodeling

An alternative radiolytic route for synthesizing conducting polymers in an organic solvent

A new and simple promising method for synthesizing conducting polymers in organic solvents was successfully achieved for the first time thanks to the oxidative polymerization of 3,4-ethylenedioxythiophene (EDOT) monomers dissolved in dichloromethane by means of gamma-radiolysis. The EDOT polymerization was controlled and optimized thanks to the study of the dose effect under an inert atmosphere. UV-Vis absorption spectroscopy was used to follow the polymerization process and to estimate both the radiolytic yield of EDOT oxidation and the required irradiation dose for quantitative poly(3,4-ethylenedioxythiophene) (PEDOT) preparation. Size exclusion chromatography (SEC) was used to determine the molar mass of the PEDOT polymers and thus their degree of polymerization. Polymers containing up to 20 EDOT units were detected. After deposition, ATR-FTIR spectroscopy and Energy-Dispersive X-ray (EDX) analysis highlighted the in situ doping of PEDOT polymers with chloride ions generated during dichloromethane radiolysis, while XRD analysis demonstrated the amorphous structure of the polymers. The morphology of the radiosynthesized PEDOT polymers was characterized in solution by Cryo-TEM microscopy and after deposition by SEM microscopy as well as by high-resolution AFM-IR microscopy coupled with infrared nanospectroscopy. In all cases, aggregated and packed spheroidal PEDOT particles with diameters comprising between 100 nm and 1.5 μm were observed. Besides, cyclic voltammetry (CV), four-point probe measurements and thermogravimetric analysis (TGA) showed that the PEDOT polymers radiosynthesized in dichloromethane are characterized by interesting electrical properties and good thermal stability. The present study bears witness to the tremendous potential of our radiation-based methodology and gives us a glimpse of future promising syntheses of different kinds of conducting polymers in organic solvents and even in complex matrices

Urinary tract infection inducing stones: some clinical and chemical data

Most papers on kidney stones arising from infection concentrate on the mineral struvite. In this contribution, we would like to call attention to other mineral phases such as highly carbonated calcium phosphate apatite, ammonium urate, and whitlockite, by presenting clinical and chemical data. We start with epidemiological data which emphasize the increase in the prevalence of kidney stones related to infection. Then we present a statistical analysis of more than 85,000 stones which have been analysed at the Laboratoire des Lithiases of Assistance Publique-Hôpitaux de Paris which gives insights regarding the link between urinary tract infection and struvite, carbonated calcium phosphate apatite (carbapatite), and also surprisingly whitlockite. Some information regarding the pathogenesis of kidney stones linked to infection, the nature of the bacteria which have been identified, and the approach to precisely analyse infrared spectra to identify struvite, carbapatite, and whitlockite, conclude this first part. To complete this clinical description, we describe the crystallographic structure and the chemistry of three relevant compounds namely carbonated calcium phosphate, struvite, and whitlockite. To conclude this second part, the dependence of crystallite morphology of struvite on pH and on the presence, or absence, of bacteria, is described. Based on clinical and chemical data, it is becoming clear that struvite is not the only mineral intimately related to renal infectious processes, but that whitlockite and carbapatite with a high carbonation rate are strongly associated with urinary tract infection as well

Urinary tract infection inducing stones: some clinical and chemical data

Most papers on kidney stones arising from infection concentrate on the mineral struvite. In this contribution, we would like to call attention to other mineral phases such as highly carbonated calcium phosphate apatite, ammonium urate, and whitlockite, by presenting clinical and chemical data. We start with epidemiological data which emphasize the increase in the prevalence of kidney stones related to infection. Then we present a statistical analysis of more than 85,000 stones which have been analysed at the Laboratoire des Lithiases of Assistance Publique-Hôpitaux de Paris which gives insights regarding the link between urinary tract infection and struvite, carbonated calcium phosphate apatite (carbapatite), and also surprisingly whitlockite. Some information regarding the pathogenesis of kidney stones linked to infection, the nature of the bacteria which have been identified, and the approach to precisely analyse infrared spectra to identify struvite, carbapatite, and whitlockite, conclude this first part. To complete this clinical description, we describe the crystallographic structure and the chemistry of three relevant compounds namely carbonated calcium phosphate, struvite, and whitlockite. To conclude this second part, the dependence of crystallite morphology of struvite on pH and on the presence, or absence, of bacteria, is described. Based on clinical and chemical data, it is becoming clear that struvite is not the only mineral intimately related to renal infectious processes, but that whitlockite and carbapatite with a high carbonation rate are strongly associated with urinary tract infection as well

Optimal strategy based on radiation chemistry for facile and direct synthesis of poly(3-thiophene acetic acid) polymers in water and dichloromethane

In this work, synthesis of nanostructured conducting poly(3-thiophene acetic acid) (PTAA) polymers was developed by means of γ-induced oxidative polymerization of TAA monomers dissolved either in water or in dichloromethane. This synthesis was shown to be facile and directly feasible without any prior esterification of TAA and in the absence of oxidizing agents. Radiolytic yields of TAA oxidation as well as irradiation doses required for quantitative PTAA preparation were determined for each solvent. UV-Vis and ATR-FTIR spectroscopies demonstrated the successful formation of two PTAA polymers, so-called "PTAAH2O"and "PTAACH2Cl2". Size exclusion chromatography (SEC) highlighted convergent molecular weight values corresponding to approximately 13 monomer units. A similar behavior for both radio-synthesized PTAAs was monitored by thermogravimetric analysis (TGA). The morphological structures of PTAAH2O and PTAACH2Cl2 were analyzed in solution by Cryo-TEM and after deposition by SEM and AFM. Microscopic observations revealed the presence of two distinguishable nanostructures: nano-spherules of several hundreds of nanometers made of PTAAH2O and nano-granules of several tens of nanometers made of PTAACH2Cl2. Cyclic voltammetry analysis and the Tauc plot method were employed to calculate the electrical and optical band gaps. Both polymers possess similar electrical band gaps. However, PTAACH2Cl2 affords a lower optical band gap than PTAAH2O. Four-point probe measurements showed that the radio-synthesized PTAA polymers are characterized by interesting electrical properties: a higher electrical conductivity was nevertheless recorded for PTAACH2Cl2. This study highlights the powerful ability of the radiation chemistry-based methodology to lead, as a simple, versatile and reliable method, to nanostructured PTAA conducting polymers either in aqueous or organic solutions

Multiscale approach to provide a better physicochemical description of women breast microcalcifications

Despite the incidence of breast cancer among women, mammography and anatomopathology investigations are still the gold standard method for preventive screening and diagnosis. Several criteria are used to diagnose precisely the severity of the pathology like the distribution and shape of breast microcalcifications (BMCs). However, the link between the different chemical phases of BMCs and the cancer stage remains unclear. As BMCs physicochemical speciation has the potential to help clinicians during their diagnosis, this study aims to propose a methodology using advanced spectroscopical analysis techniques to finely characterize BMCs and uncover the relationship between mineralization processes and breast cancer. A state of the art in the domain is first proposed to highlight the role of BMCs and the importance of extensive analytical analysis using electron microscopy and vibrational techniques. Secondly, a detailed methodology for BMCs multiscale analysis is proposed and the relevance of each technique illustrated through the study of a biopsy from a patient suffering of an infiltrating low-grade ductal carcinoma: scanning electron microscopy analysis was used for the morphological description of BMCs, infrared micro and nanospectroscopy techniques for their chemical speciation at the micrometric and sub-micrometric scales

Multiscale approach to provide a better physicochemical description of women breast microcalcifications

Despite the incidence of breast cancer among women, mammography and anatomopathology investigations are still the gold standard method for preventive screening and diagnosis. Several criteria are used to diagnose precisely the severity of the pathology like the distribution and shape of breast microcalcifications (BMCs). However, the link between the different chemical phases of BMCs and the cancer stage remains unclear. As BMCs physicochemical speciation has the potential to help clinicians during their diagnosis, this study aims to propose a methodology using advanced spectroscopical analysis techniques to finely characterize BMCs and uncover the relationship between mineralization processes and breast cancer. A state of the art in the domain is first proposed to highlight the role of BMCs and the importance of extensive analytical analysis using electron microscopy and vibrational techniques. Secondly, a detailed methodology for BMCs multiscale analysis is proposed and the relevance of each technique illustrated through the study of a biopsy from a patient suffering of an infiltrating low-grade ductal carcinoma: scanning electron microscopy analysis was used for the morphological description of BMCs, infrared micro and nanospectroscopy techniques for their chemical speciation at the micrometric and sub-micrometric scales