Détermination par analyse thermique des seuils d'amorçage des fissures sous chargement de Fretting

La sollicitation de Fretting est un phénomène associé à des micro-déplacements de faibles amplitudes entre deux solides en contact inférieur à la dimension de contact. L’endommagement généré par le Fretting sur la surface de contact est contrôlé par l’amplitude de glissement et dans le cas du glissement partiel l’endommagement prépondérant est la fissuration. La détermination des conditions d’amorçages passe par des méthodes expérimentales destructives très couteuses en temps et matériaux. Le but de notre étude est de développer une nouvelle méthode expérimentale basée sur la réponse thermique des matériaux, à l’image de celles s’appuyant sur les courbes d’auto-échauffement en fatigue. L’étude présentée ici a été réalisé sur un acier et nous nous sommes placés dans la configuration Cylindre/Plan. Un essai de Fretting consiste à appliquée une force normale constante sur le Plan. Un déplacement cyclique relatif est imposé, donnant naissance à une force tangentielle macroscopique. Une caméra thermique maintenue fixe et perpendiculaire à la surface latérale de l’échantillon lors des essais est utilisée. Les mesures thermiques ont été couplées à une méthode de suivi des marqueurs afin d’éliminer les mouvements de solide rigide. Une méthode de lissage local de la température est utilisée. Lors d’un test de Fretting à paramètres de chargement constants, l’évolution de la température moyennée sur une zone d’intérêt(ZI) peut être décomposée en trois parties, une dérive thermique globale, un signal périodique de même fréquence que la sollicitation et un signal périodique à deux fois cette fréquence. La dérive et les amplitudes des signaux périodiques atteignent rapidement une valeur stabilisée. Les résultats montrent que la valeur stabilisée de la dérive et les amplitudes des signaux périodiques de la température moyenne sur la ZI peuvent être empiriquement lié au seuil d’amorçage des fissures déterminée par les méthodes destructives. Les différences entre les deux méthodes restent inférieures à 10%

Accidental ulcer infestation due Tenebrio molitor in an AIDS patient: canthariasis

Canthariasis is a disease of humans caused by the infestation of beetle larvae. It is the second important insectal disease after myiasis. Several species of beetles are reported to cause the disease in gastrointestinal tract, urogenital system, nasal sinuses, ears and faces of mammals. The mealworm beetle, Tenebrio molitor, a species of darkling beetle, is a widespread pest that usually feeds on stored grain. The human infestation by this worm is extremely rarely reported, we described a case of T. molitor infestation in a AIDS patient in Colombia

Alteration of ribosome function upon 5-fluorouracil treatment favors cancer cell drug-tolerance.

Mechanisms of drug-tolerance remain poorly understood and have been linked to genomic but also to non-genomic processes. 5-fluorouracil (5-FU), the most widely used chemotherapy in oncology is associated with resistance. While prescribed as an inhibitor of DNA replication, 5-FU alters all RNA pathways. Here, we show that 5-FU treatment leads to the production of fluorinated ribosomes exhibiting altered translational activities. 5-FU is incorporated into ribosomal RNAs of mature ribosomes in cancer cell lines, colorectal xenografts, and human tumors. Fluorinated ribosomes appear to be functional, yet, they display a selective translational activity towards mRNAs depending on the nature of their 5'-untranslated region. As a result, we find that sustained translation of IGF-1R mRNA, which encodes one of the most potent cell survival effectors, promotes the survival of 5-FU-treated colorectal cancer cells. Altogether, our results demonstrate that "man-made" fluorinated ribosomes favor the drug-tolerant cellular phenotype by promoting translation of survival genes

Near-Field Scanning Optical Microscope Combined with Digital Holography for Three-Dimensional Electromagnetic Field Reconstruction

International audienceNear-field scanning optical microscopy (NSOM) has proven to be a very powerful imaging technique that allows overcoming the diffraction limit and obtaining information on a scale much smaller than what can be achieved by classical optical imaging techniques. This is achieved using nanosized probes that are placed in close proximity to the sample surface, and thus allow the detection of evanescent waves that contain important information about the properties of the sample on a subwavelength scale. In particular, some aperture-based probes use a nanometer-sized hole to locally illuminate the sample. The far-field radiation of such probes is essential to their imaging properties, but cannot be easily estimated since it highly depends on the environment with which it interacts. In this chapter, we tackle this problem by introducing a microscopy method based on full-field off-axis digital holography that allows us to study in details the three-dimensional electromagnetic field scattered by a NSOM probe in different environments. We start by describing the NSOM and holography techniques independently, and continue by highlighting the advantage of combining both methods. We present a comparative study of the reconstructed light from a NSOM tip located in free space or coupled to transparent and plasmonic media. While far-field methods, such as back focal plane imaging, can be used to infer the directionality of angular radiation patterns, the advantage of our technique is that a single hologram contains information on both the amplitude and phase of the scattered light, allowing to reverse numerically the propagation of the electromagnetic field towards the source. We also present Finite Difference Time Domain (FDTD) simulations to model the radiation of the NSOM tip as a superposition of a magnetic and an electric dipole. We finally propose some promising applications that could be performed with this combined NSOM-holography technique

Identification of β-Lactams Active against Mycobacterium tuberculosis by a Consortium of Pharmaceutical Companies and Academic Institutions

Rising antimicrobial resistance challenges our ability to combat bacterial infections. The problem is acute for tuberculosis (TB), the leading cause of death from infection before COVID-19. Here, we developed a framework for multiple pharmaceutical companies to share proprietary information and compounds with multiple laboratories in the academic and government sectors for a broad examination of the ability of β-lactams to kill Mycobacterium tuberculosis (Mtb). In the TB Drug Accelerator (TBDA), a consortium organized by the Bill & Melinda Gates Foundation, individual pharmaceutical companies collaborate with academic screening laboratories. We developed a higher order consortium within the TBDA in which four pharmaceutical companies (GlaxoSmithKline, Sanofi, MSD, and Lilly) collectively collaborated with screeners at Weill Cornell Medicine, the Infectious Disease Research Institute (IDRI), and the National Institute of Allergy and Infectious Diseases (NIAID), pharmacologists at Rutgers University, and medicinal chemists at the University of North Carolina to screen ∼8900 β-lactams, predominantly cephalosporins, and characterize active compounds. In a striking contrast to historical expectation, 18% of β-lactams screened were active against Mtb, many without a β-lactamase inhibitor. One potent cephaloporin was active in Mtb-infected mice. The steps outlined here can serve as a blueprint for multiparty, intra- and intersector collaboration in the development of anti-infective agents

Femte Dimensionen : en lärmodell som förenar forskning, utbildning och "tredje uppgiften".

Ett exempel på nya samarbetsformer mellan högskola och det omgivande samhället kallad "Femte Dimensionen" redovisas. Poängen är att den så kallade tredje uppgiften inte är något vid sidan av forskning och undervisning, utan är något integrerat, något som kan berika såväl undervisning som forskning.Den artikel som här publiceras i databasen är en version som i bearbetat skick utgör bokkapitlet.</p

Femte Dimensionen : en lärmodell som förenar forskning, utbildning och "tredje uppgiften".

Ett exempel på nya samarbetsformer mellan högskola och det omgivande samhället kallad "Femte Dimensionen" redovisas. Poängen är att den så kallade tredje uppgiften inte är något vid sidan av forskning och undervisning, utan är något integrerat, något som kan berika såväl undervisning som forskning.Den artikel som här publiceras i databasen är en version som i bearbetat skick utgör bokkapitlet.</p

One size does not fit all-evolution of opioid agonist treatment in a naturalistic setting over 23 years

Background and aims Opioid agonist treatment (OAT) is currently the most effective treatment for people with opioid dependence. In most countries, however, access to the whole range of effective medications is restricted. This study aims to model the distribution of different OAT medications within a naturalistic and relatively unrestricted treatment setting (Zurich, Switzerland) over time, and to identify patient characteristics associated with each medication. Methods We used generalized estimating equation analysis with data from the OAT register of Zurich and the Swiss register for heroin‐assisted treatment (HAT) to model and forecast the annual proportion of opioids applying exponential distributions until 2018 and patient characteristics between 1992 and 2015. Results Data from 11 895 patients were included in the analysis. Methadone remains the mainstay of OAT, being prescribed to two‐thirds of patients. Following its approval, the proportion of HAT increased rapidly and is now constant at 12.16% [95% confidence interval (CI) = 11.15–13.17]. The initial increase of proportions of buprenorphine or slow‐release oral morphine (SROM) following their approval for OAT was slower. While in 2014 both medications had a proportion of 10.2% and 10.3%, respectively, our model predicts a further increase of SROM to 19.9% in 2018, with a ceiling level of 25.19% (21.40–28.98%) thereafter. SROM patients display characteristics similar to those treated with methadone; buprenorphine patients show the highest social integration; and HAT patients are the most homogeneous group, with highest mean age, most widespread injecting experience and lowest social integration. Conclusions Based on data from Zurich, Switzerland from 1992 to 2015, there is no evidence for an excessive demand for a single medication in a naturalistic and liberal opioid agonist treatment setting. Rather, the specific patient characteristics associated with each medication underline the need for diversified treatment options for opioid dependence