Etude del'interaction laser-matière dans le cas des polymères semi-transparents (application au soudage des polymères)

L objectif de cette recherche doctorale a été d'estimer la soudabilité par laser des matériaux polymériques en fonction de leurs propriétés thermo-physiques. La première tâche, dans la recherche de cet objectif, a été de quantifier l'atténuation de la radiation dans les polymères semi-transparents en établissant la corrélation entre les propriétés optiques des inclusions et de la matrice du polymère, et la distribution spatiale de l'intensité laser les traversant, c'est à dire, en effectuant une modélisation des phénomènes optiques qui permet d estimer la forme de la distribution du faisceau laser à l interface des deux matériaux. Cette modélisation a permis aussi de découpler les facteurs influents et d explorer leurs effets sur l atténuation et l élargissement du faisceau laser à travers un milieu semi transparent. L étape suivante consiste à réaliser le couplage entre le modèle optique et le modèle thermique, fondé sur l équation de la diffusion de la chaleur, afin de déterminer les champs de températures dans le volume des composants. Cette étude constitue une ouverture vers l approche scientifique des processus de soudage par laser des thermoplastiques en offrant des méthodes et des techniques pour l optimisation globale de ceux-ci.The purpose of the present study was to estimate the weldability of a polymeric material couple according to their thermal and optical properties. The first task in pursuit of this goal was to quantify the beam attenuation in the semi-transparent polymer by making connection between the optical properties of the bulk materials of which the heterogeneities and the medium are made and the laser intensity spatial distribution into the medium. This modeling allowed establishing the importance of each scattering parameter on the beam attenuation and its broadening at the exit of the semi-transparent polymer. The second step was to realize a connection between the optical model and a thermical one, based on the general heat transfer equation in order to determine the temperature field inside the two materials to be welded. This study represents an opening in the scientific approach of polymers laser welding process, offering in the same time new possibilities in global optimization of the process.DIJON-BU Sciences Economie (212312102) / SudocSudocFranceF

laser beam scattering effects in non-homogeneous polymers

Laser Welding; Light Scattering ;Polymer; Mie Theory; Monte CarloInternational audienceIn this paper a numerical model for laser beam scattering in the semi-transparent polymers is presented, using a Monte Carlo algorithm and the Mie theory. The algorithm correctly accounts for the independent multiply-scattered light. We describe the algorithm, present a number of important parameters that account in the welding process, and explicitly show how the algorithm can be used to estimate the laser beam intensity both inside the semi-transparent component and at the welding interface and the beam widening. For the model validation an experimental bench test has been realized and some results from two test cases are presented

Through-transmission laser welding of polymers - temperature field modeling and infrared investigation

International audienceThe purpose of the present study is to estimate the weldability of a polymeric material couple according to their thermal and optical properties. A first model based on Mie theory and Monte Carlo method describes the laser beam behavior in semi-transparent media and makes it possible to approximate the laser power distribution at the interface of the two materials. A second model based on finite element method permits the temperature field estimation into both parts to be welded. The results are validated by infrared thermography

On-Target Pharmacodynamic Activity of the PI3K Inhibitor Copanlisib in Paired Biopsies from Patients with Malignant Lymphoma and Advanced Solid Tumors.

The PI3K inhibitor copanlisib has efficacy and manageable safety in patients with indolent lymphoma and solid tumors. Pharmacodynamic effects relative to copanlisib dose and plasma exposure were evaluated. Patients with lymphoma or solid tumors received copanlisib 0.4 mg/kg or 0.8 mg/kg on days 1, 8, and 15 of a 28-day cycle. Primary variables were maximum changes in phosphorylated AKT (pAKT) levels in platelet-rich plasma (PRP) and plasma glucose. Other evaluations included PI3K signaling markers and T-lymphocytes in paired tumor biopsies, the relationship between estimated plasma exposure and pharmacodynamic markers, response, and safety. Sixty-three patients received copanlisib. PRP pAKT levels showed sustained reductions from baseline following copanlisib (median inhibition: 0.4 mg/kg, 73.8% [range -94.9 to 144.0]; 0.8 mg/kg, 79.6% [range -96.0 to 408.0]). Tumor pAKT was reduced vs. baseline with copanlisib 0.8 mg/kg in paired biopsy samples (P < 0.05). Dose-related transient plasma glucose elevations were observed. Estimated copanlisib plasma exposure significantly correlated with changes in plasma pAKT and glucose metabolism markers. There were 2 complete responses and 6 partial responses; 7 of 8 responders received copanlisib 0.8 mg/kg. Adverse events (all grade) included hyperglycemia (52.4%), fatigue (46.0%), and hypertension (41.3%). Copanlisib demonstrated dose-dependent pharmacodynamic evidence of target engagement and PI3K pathway modulation/inhibition in tumor and immune cells. Results support the use of copanlisib 0.8 mg/kg (or flat-dose equivalent of 60 mg) in solid tumors and lymphoma, and provide a biomarker hypothesis for studies of copanlisib combined with immune checkpoint inhibitors (NCT03711058)