NMR imaging of water flow in packed beds

Measurements by magnetic resonance imaging (MRI) of water flow within granular porous media are presented in this study. Our goal was not only to obtain visualizations of velocity field in porous media but rather to make accurate measurements of interstitial and averaged velocities in bead packs. Two situations were examined: the first for a packed bed with a large beads diameter where it was possible to visualize the interstitial velocities and the second with a packed bed with a small beads diameter where only averaged interstitial velocities were measured

Testicular biodistribution of silica-gold nanoparticles after intramuscular injection in mice

International audienceWith the continuing development of nanomaterials, the assessment of their potential impact on human health, and especially human reproductive toxicity, is a major issue. The testicular biodistribution of nanoparticles remains poorly studied. This study investigated whether gold-silica nanoparticlescould be detected in mouse testes after intramuscular injection, with a particular focus on their ability to cross the blood– testis barrier. To that purpose, well-characterized 70-nm gold core–silica shell nanoparticles were used to ensure sensitive detection using high-resolution techniques. Testes were collected at different time points corresponding to spermatogenesis stages in mice. Transmission electronmicroscopy and confocal microscopy were used for nanoparticle detection, and nanoparticle quantification was performed by atomic emission spectroscopy. All these techniques showed that no particles were able to reach the testes. Results accorded with the normal histological appearance of testes even at 45 days post sacrifice.High-resolution techniques did not detect 70-nm silica-gold nanoparticles in mouse testes after intramuscular injection.These results are reassuring about the safety of nanoparticles with regard to male human reproduction, especially in the context of nanomedicine

Drogues, sexe et risques dans la communauté gaie montréalaise : 1997-2003

Cet article décrit l’évolution de la consommation de drogues entre 1997 et 2003 chez des hommes gais et bisexuels séronégatifs de la grande région montréalaise, selon l’âge et selon les comportements sexuels à risque pour le VIH. Les données proviennent d’Oméga, une étude longitudinale sur l’incidence et les déterminants psychosociaux de l’infection au VIH chez ces hommes. Les participants ont rempli un questionnaire tous les six mois, et les données sont celles de leur première visite de suivi. Des analyses de tendance par période de calendrier ont été réalisées et un modèle de régression logistique utilisant une estimation par équations généralisées a été généré pour chaque type de drogues. Les résultats révèlent une augmentation de la consommation de cocaïne, de l’ecstasy, des hallucinogènes, du speed et du GHB entre 1997 et 2003. En revanche, la consommation de marijuana, de poppers et d’héroïne ne semble pas avoir changé de façon significative. Les moins de 30 ans et ceux qui ont eu des relations anales à risque semblent avoir été plus enclins à consommer certaines drogues pendant cette même période. Indices de transformations possibles dans les modes de vie de ces hommes, ces résultats soulèvent de nouveaux défis pour la prévention du VIH dans la communauté gaie.This article describes the evolution of drug use between 1997 and 2003 in HIV-negative men who have sex with men living in the Montreal region, according to age and HIV risk-taking behaviours. Data come from Omega, a longitudinal study on the incidence and on the psychosocial determinants of HIV infection among these men. Participants completed a questionnaire every six months and data are from the first follow-up visit. Trends analyses by calendar period were done and a logistic regression model using generalised equations for parameter estimation was generated for each type of drug. Results reveal an increase in cocaine, ecstasy, hallucinogen, speed and GHB use between 1997 and 2003. On the other hand, marijuana, poppers and heroin use do not seem to have change significantly. Men who are younger than 30 years old and who had risky anal intercourse seem to be more likely to have used specific drugs in the same period. This indicates possible transformations in the way of life of these men and these results suggest new challenges for HIV prevention in the gay community.Este artículo describe la evolución del consumo de drogas entre 1997 y 2003 entre los hombres gay y bisexuales seronegativos de la gran región montrealesa, según la edad y los comportamientos sexuales de riesgo con respecto al VIH. Los datos provienen de Oméga, un estudio longitudinal sobre la incidencia y los determinantes psicosociales de la infección de VIH en los hombres. Los participantes respondieron un cuestionario cada seis meses y los datos son los de su primera visita de seguimiento. Se realizaron análisis de tendencia por período de calendario y se generó un modelo de regresión logística, utilizando una estimación por ecuaciones generalizadas para cada tipo de droga. Los resultados revelan un aumento del consumo de cocaína, éxtasis, alucinógenos, speed y GHB entre 1997 y 2003. Por el contrario, el consumo de marihuana, poppers y heroína no parece haber cambiado de manera significativa. Los menores de 30 años y quienes tienen relaciones sexuales anales a riesgo parecen haber tenido una mayor tendencia a consumir ciertas drogas durante este mismo período. Estos resultados, índices de transformaciones posibles en los modos de vida de estos hombres, plantean nuevos desafíos en la prevención del VIH en la comunidad gay

Catalytic ozonation with γ-Al2O3 to enhance the degradation of refractory organics in water

Nowadays, heterogeneous catalytic ozonation appears as a promising way to treat industrial wastewaters containing refractory pollutants, which resist to biological treatments. Several oxides and minerals have been used and their behavior is subject to controversy with particularly the role of Lewis acid sites and/or basic sites and the effect of salts. In this study, millimetric mesoporous γ-Al2O3 particles suitable for industrial processes were used for enhancing the ozonation efficiency of petrochemical effluents without pH adjustment. A phenol (2,4-dimethylphenol (2,4-DMP)) was first chosen as petrochemical refractory molecule to evaluate the influence of alumina in ozonation. Single ozonation and ozonation in presence of γ-Al2O3 led to the disappearance of 2,4-DMP in 25 min and a decrease in pH from 4.5 to 2.5. No adsorption of 2,4-DMP occurred on γ-Al2O3. Adding γ-Al2O3 in the process resulted in an increase of the 2,4–DMP oxidation level. Indeed, the total organic carbon (TOC) removal was 14% for a single ozonation and 46% for ozonation with γ-Al2O3. Similarly, chemical oxygen demand (COD) removal increases from 35 to 75%, respectively. Various oxidized by-products were produced during the degradation of 2,4-DMP, but after 5 h ozonation 90% of organic by-products were acetic acid > formic acid ≫ oxalic acid. Some of the carboxylic acids were adsorbed on γ-Al2O3. The use of radical scavengers (tert-butanol) highlighted the involvement of hydroxyl radicals during catalytic ozonation with γ-Al2O3 in contrary to single ozonation, which mainly involved direct ozone reaction. γ-Al2O3 is an amphoteric solid with Lewis acid AlOH(H+) sites and basicAl-OH sites. After ozonation the amount of basic sites decreased due to carboxylates adsorption, while the Lewis acid sites remained constant as evidenced by FTIR. Several ozonation runs with γ-Al2O3 reported a progressive decrease of its catalytic activity due to the cumulative sorption of carboxylates on the basic sites. After 80 h of ozonation, a calcination at 550 °C allowed to recover allAl-OH basic sites and the initial activity of γ-Al2O3. A synthetic petrochemical effluent containing various petrochemicals (phenol, acetic acid, naphtenic acid, pyrene, naphtalene) was then treated with γ-Al2O3 with and without NaCl. Sodium ions prevented carboxylates adsorption on γ-Al2O3 leading to a higher efficiency of γ-Al2O3 in presence of NaCl and allowed to decrease the toxicity of the petrochemical effluent

Clearance of defective muscle stem cells by senolytics reduces the expression of senescence-associated secretory phenotype and restores myogenesis in myotonic dystrophy type 1

Muscle weakness and atrophy are clinical hallmarks of myotonic dystrophy type 1 (DM1). Muscle stem cells, which contribute to skeletal muscle growth and repair, are also affected in this disease. However, the molecular mechanisms leading to this defective activity and the impact on the disease severity are still elusive. Here, we explored through an unbiased approach the molecular signature leading to myogenic cell defects in DM1. Single cell RNAseq data revealed the presence of a specific subset of DM1 myogenic cells expressing a senescence signature, characterized by the high expression of genes related to senescence-associated secretory phenotype (SASP). This profile was confirmed using different senescence markers in vitro and in situ. Accumulation of intranuclear RNA foci in senescent cells, suggest that RNA-mediated toxicity contribute to senescence induction. High expression of IL-6, a prominent SASP cytokine, in the serum of DM1 patients was identified as a biomarker correlating with muscle weakness and functional capacity limitations. Drug screening revealed that the BCL-XL inhibitor (A1155463), a senolytic drug, can specifically target senescent DM1 myoblasts to induce their apoptosis and reduce their SASP. Removal of senescent cells re-established the myogenic function of the non-senescent DM1 myoblasts, which displayed improved proliferation and differentiation capacity in vitro; and enhanced engraftment following transplantation in vivo. Altogether this study presents a well-defined senescent molecular signature in DM1 untangling part of the pathological mechanisms observed in the disease; additionally, we demonstrate the therapeutic potential of targeting these defective cells with senolytics to restore myogenesis

Heat transfer in a swirling fluidized bed with Geldart type-D particles

A relatively new variant in fluidized bed technology, designated as the swirling fluidized bed (SFB), was investigated for its heat transfer characteristics when operating with Geldart type D particles. Unlike conventional fluidized beds, the SFB imparts secondary swirling motion to the bed to enhance lateral mixing. Despite its excellent hydrodynamics, its heat transfer characteristics have not been reported in the published literature. Hence, two different sizes of spherical PVC particles (2.61mm and 3.65mm) with the presence of a center body in the bed have been studied at different velocities of the fluidizing gas. The wall-to-bed heat transfer coefficients were measured by affixing a thin constant foil heater on the bed wall. Thermocouples located at different heights on the foil show a decrease in the wall heat transfer coefficient with bed height. It was seen that only a discrete particle model which accounts for the conduction between the particle and the heat transfer surface and the gas-convective augmentation can adequately represent the mechanism of heat transfer in the swirling fluidized bed