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The use of shock resistant RT-PMMA in engineering structures potentially subject to accidental overloading requires an evaluation of its crack arrest capability under impact loading. Based on experimental results obtained from a series of Kalthoff and Winkler (KW)-type impact tests, the present study aims at numerically reproducing the conditions for brittle-like crack initiation and propagation in impact-loaded RT-PMMA. For that purpose, three-dimensional SPH numerical simulations were conducted and the performance of various failure criteria was evaluated. The numerical model together with a combination of stress- and strain- dependent failure criteria were shown to fairly reproduce the experimental results in terms of finite crack advance and orientation.

A new experimental set-up mounted at the muzzle of a singlestage gas gun has been designed in order to study the fragmentation of metallic rings under dynamic radial expansion. This concept takes advantage of the quasi-incompressibility of HDPE whose radial flow under plate impact-like loading is used to apply a pressure boundary condition at the ring’s inner surface. For the experimental configurations considered in the present work, the average strain rate in the ring reaches values close to 104 s-1. The repeatability and the reliability of the experiments are verified for rings made of steel and aluminium.

The complexity of ballistic protections increases with their efficiency. On this basis, an exclusively empirical approach is not adapted to optimise complex protection systems and the resort to numerical simulations is preferred if not mandatory. The present study proposes a methodology aiming at optimising complex multi-layer ballistic armours based on an experimental-numerical correlation. A multi-layer system is taken as example. A numerical model is first calibrated according to impact-on-monolithic-target test results. Once the model is validated, an optimisation process considering multi-layer configurations involving a sharp-nosed threat modifies the plates’ thicknesses in order to minimise the total mass while ensuring the system’s protective capacity in terms of residual velocity. The optimisation process shows that a single layer system is more efficient than a multi-layer one in the studied case.

In the context of the design of aeronautical structures regarding accidental events, we are here investigating and comparing the shear failure of two aluminum alloys, namely AA2024 and AA7175, under high strain rate loading. With this aim in view, two experiments were carried out: (i) high strain rate shear compression of hat shaped structures, and (ii) impact test on the edge of double notched plates. The fractured surfaces of post-mortem specimens were observed using optical and scanning electron microscopes (SEM) in order to identify the failure mechanisms.

We are here interested in the crack arrest capability under impact loading of metals and polymers used as structural and/or protection materials in aerospace engineering. Kalthoff and Winkler-type impact tests are carried out to that purpose on high strength AA7175 aluminum alloy and shock resistant polymethyl methacrylate (PMMA). Impact tests are carried out at impact velocities ranging from 50 m/s to 250 m/s and high speed camera is used to record the different steps of the failure process. For AA7175, early Mode II shear failure followed by late Mode I opening failure are seen. The premature ductile failure of the alloy is shown to result from a preceding stage of dynamic localization in the form of adiabatic shear bands. Impact tests on shock-resistant PMMA evidence the brittle feature of the material failure. It is notably shown that the higher the impact velocity (in the range 50-100 m/s) the larger the number of fragments. Moreover, depending on the impact velocity, changes in the crack path and thus in the mechanisms controlling the PMMA dynamic fracture can be seen.

Rationale and objectives: A new microcatheter was recently developed claiming to reduce beads reflux in drug-eluting bead transarterial chemoembolization (DEB-TACE). The aim of this study was to compare the reflux control microcatheter ability versus a standard microcatheter for TACE treatment in patients with hepatocellular carcinoma. Material and methods: Patients were prospectively included between November 2017 and February 2022. They received a DEB-TACE treatment with charged radiopaque beads using standard microcatheters or the SeQure reflux control microcatheter (Guerbet, France) and were assigned respectively to a control and a test group. Beads distribution mismatch was evaluated between the targeted territory on treatment planning CBCT and beads’ spontaneous opacities on the post-intervention CBCT and the 1-month CT scanner. Results: Twenty-three patients (21 men, median age 64 years [12.5 years]) with 37 hepatocellular carcinoma nodules were treated. The control group consisted of 13 patients – 19 nodules, while the test group included ten patients - 18 nodules. Non target embolization (NTE) was found in 20 % (2/10) of patients in the test group and 85 % (11/13) in the control group. NTE involved only an adjacent segment in the test group while it affected the adjacent biliary sector or even the contralateral liver lobe in the control group. No complication linked to NTE was found in the test group, while it led to one case of ischemic cholangitis and another case of biloma in the control group. Conclusion: The reflux control microcatheter may be efficient in reducing NTE and thus eventual adverse events in comparison to standard of care end-hole microcatheters.

Experimental analysis of fracture mechanisms is a key point to understand and further reproduce physical phenomena involved in structural material failure. Actually, crack propagation under high loading rate is a strongly coupled thermo-mechanical problem involving large deformation, high strain rate and (quasi) adiabatic conditions. The work presented herein aims at analyzing the successive steps of the dynamic deterioration of a high strength structural material, namely the ARMOX500T armor steel, leading to the ultimate fracture. The Kalthoff and Winkler impact test, consisting in impacting the edge of a double notched plate, was retained for that purpose. Images are captured at high frame rate (1M frame/s) during the impact loading then analyzed according to a line tracking method. Three stages are accordingly observed: first the progressive development of a weak localization of the deformation within a wide zone behind the notch tips, second the propagation of a narrow band of strong localization, and finally the propagation of a crack. The propagation of the white band is associated to the development of an adiabatic shear band (ASB), as a precursor of the crack. Corresponding displacement fields are identified thanks to the adopted line tracking method, allowing for determining the evolution of mechanical quantities, including notably notch tip shear displacement and velocity, ASB-related white band velocity, global and local shear strain and shear strain rate magnitudes, in view of being implemented into numerical models.

A methodology is developed based on the coupling of a finite element code with an optimisation module for the design of land vehicle armouring composed of lightweight aluminium alloy and high strength steel plate. Following an experiment/simulation correlation, a numerical model has been built and calibrated considering monolithic plates and then verified considering a bi-metal protection against tungsten carbide projectile mimicking the core of a 7.62×51 AP8 ammunition. In addition, a method is proposed to obtain the vres−vi curve for the full 7.62×51 AP8 bullet from the vres−vi curve obtained from the core only.

Enteroviruses are a frequent source of infection and among the most common central nervous system viral pathogens. Enteroviruses – in particular, the Coxsackie B viruses – are a known cause of myocarditis. Rituximab is a genetically engineered chimeric anti-CD20 monoclonal antibody. Many reports in the literature suggest a higher risk of infection following repeated rituximab therapy, including viral infection. However, observations of enterovirus-related myocarditis in the context of rituximab treatment are scarce. The authors describe the case of a patient with neuromyelitis optica spectrum disorder who developed severe and fatal enterovirus-related myocarditis after rituximab therapy with a difficult differential diagnosis of autoimmune or giant-cell myocarditis. This case highlights the importance of complete diagnostic workup in difficult cases of myocarditis, including endomyocardial biopsies.

Illicit drugs are a global health problem, since both their acute and chronic consumption have negative impacts on the drug user's health. Drug checking facilities are receiving growing interest as they allow drug users to chemically analyze their product prior to consumption to assess the presence of adulterants or other non-expected substances. Such harm reduction programs allow the reduction of the risks associated with drug consumption without encouraging it. In particular, the emergence of new psychoactive substances (NPS) emphasizes the risk for the population increasing the diversity and the lability of illicit drugs on the market. Analytical developments are required to catch up with this rapid evolution and reduce the potential harm caused by such consumption. In this study, we developed a matrix-assisted laser desorption/ionization (MALDI) high-resolution mass spectrometry (HRMS) strategy for the high-throughput qualitative and quantitative analysis of drug checking samples. The use of online-based m/z cloud library for untargeted compound search improved the ability to identify unknown compounds. Sixty-seven drug checking samples were analyzed using this analytical strategy, allowing the detection of 10 designer drugs and several classical drugs of abuse (mainly cocaine and MDMA) as well as adulterants and contaminants. The results were then compared with routine analyses of the same samples using conventional approaches showing similar performance while removing the use of chromatographic separation thus resulting in a significant reduction of the time required for sample preparation and analysis. This study enlightens the potential of MALDI-HRMS as a high-throughput approach allowing to speed-up up to six times the identification and quantification of substances enabling to catch the fast changes on the drug of abuse market. This strategy could be an interesting alternative analytical approach, allowing better prevention and harm reduction for drug users.

Adiabatic shear banding (ASB) is a dynamic localization phenomenon resulting from thermomechanical instability under high strain rate and low stress triaxiality loading conditions. High strength, steels and lightweight alloys of titanium and aluminum are highly susceptible to this phenomenon which leads to premature material failure. At an advanced stage of the localization process, the adiabatic shear bands have been shown to contain micro-voids which coalesce to form cracks and ultimately lead to the fracture of the structure. A physics-motivated, unified constitutive model accounting for the coupled effects of ASB and micro-voiding has been developed in the context of large deformation, high strain rate and high temperature rise. The enlarged model is herein implemented as user material into the engineering finite element (FE) computation code LS-DYNA in the context of standard FE kinematic formulation and its performances are assessed. [ABSTRACT FROM AUTHOR]

High strength, lightweight materials, including notably titanium and aluminium alloys are widely used in aircraft and other structures. When subjected to high strain rate loading involving quasi adiabatic conditions, these materials may be subjected to a thermomechanical instability resulting in a dynamic localization in the form of narrow adiabatic shear bands (ASBs) which cause a premature structural failure. A physics-motivated unified model is presented, based on a specific scale postulate amounting to a global insight into the material response (the representative volume element contains the band, and not the opposite as usually considered) and aiming at reproducing the coupled effects of dynamic plasticity, strain localization and microvoiding in the context of large deformation, high strain rate and high temperature rise. The model is implemented as user material in the engineering finite element computation code LS-DYNA and its performances are evaluated regarding various available experimental results. [ABSTRACT FROM AUTHOR]

Background: The potential benefit of transcatheter aortic valve replacement (TAVR) in patients with nonsevere aortic stenosis (AS) and heart failure is controversial. This study aimed to assess outcomes of patients with nonsevere low-gradient AS (LGAS) and reduced left ventricular ejection fraction undergoing TAVR or medical management. Methods: Patients undergoing TAVR for LGAS and reduced left ventricular ejection fraction (<50%) were included in a multinational registry. True-severe low-gradient AS (TS-LGAS) and pseudo-severe low-gradient AS (PS-LGAS) were classified according to computed tomography-derived aortic valve calcification thresholds. A medical control group with reduced left ventricular ejection fraction and moderate AS or PS-LGAS was used (Medical-Mod). Adjusted outcomes between all groups were compared. Among patients with nonsevere AS (moderate or PS-LGAS), outcomes after TAVR and medical therapy were compared using propensity score-matching. Results: A total of 706 LGAS patients undergoing TAVR (TS-LGAS, N=527; PS-LGAS, N=179) and 470 Medical-Mod patients were included. After adjustment, both TAVR groups showed superior survival compared with Medical-Mod patients (all P <0.001), while no difference was found between TS-LGAS and PS-LGAS TAVR patients (P =0.96). After propensity score-matching among patients with nonsevere AS, PS-LGAS TAVR patients showed superior 2-year overall (65.4%) and cardiovascular survival (80.4%) compared with Medical-Mod patients (48.8% and 58.5%, both P ≤0.004). In a multivariable analysis including all patients with nonsevere AS, TAVR was an independent predictor of survival (hazard ratio, 0.39 [95% CI, 0.27–0.55]; P <0.0001). Conclusions: Among patients with nonsevere AS and reduced left ventricular ejection fraction, TAVR represents a major predictor of superior survival. These results reinforce the need for randomized-controlled trials comparing TAVR versus medical management in heart failure patients with nonsevere AS. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT04914481. [ABSTRACT FROM AUTHOR]

Background: Stereotactic body radiotherapy (SBRT) has been reported as a safe and efficient therapy for treating refractory ventricular tachycardia (VT) despite optimal medical treatment and catheter ablation. However, data on the use of SBRT in patients with electrical storm (ES) is lacking. The aim of this study was to assess the clinical outcomes associated with SBRT in the context of ES.Methods: This retrospective study included patients who underwent SBRT in the context of ES from March 2020 to March 2021 in one tertiary center (CHU Lille). The target volume was delineated according to a predefined workflow. The efficacy was assessed with the following end points: sustained VT recurrence, VT reduced with antitachycardia pacing, and implantable cardioverter defibrillator shock.Results: Seventeen patients underwent SBRT to treat refractory VT in the context of ES (mean 67±12.8 age, 59% presenting ischemic heart disease, mean left ventricular ejection fraction: 33.7± 9.7%). Five patients presented with ES related to incessant VT. Among these 5 patients, the time to effectiveness ranged from 1 to 7 weeks after SBRT. In the 12 remaining patients, VT recurrences occurred in 7 patients during the first 6 weeks following SBRT. After a median 12.5 (10.5-17.8) months follow-up, a significant reduction of the VT burden was observed beyond 6 weeks (-91% [95% CI, 78-103]), P<0.0001). The incidence of implantable cardioverter defibrillator shock and antitachycardia pacing was 36% at 1 year.Conclusions: SBRT is associated with a significant reduction of the VT burden in the event of an ES; however, prospective randomized control trials are needed. In patients without incessant VT, recurrences are observed in half of patients during the first 6 weeks. VT tolerance and implantable cardioverter defibrillator programming adjustments should be integrated as part of an action plan defined before SBRT for each patient. [ABSTRACT FROM AUTHOR]

Adiabatic shear bands are known to cause premature structural failure in high strength metals and alloys. The observation of adiabatic shear bands inside partially fractured specimens evidences the presence of micro-voids as the precursor of the ultimate failure. An enriched model containing the effects of adiabatic shear banding and micro-voiding mechanisms was developed and it is here taken through a calibration procedure. The aim of the present work is to evaluate the performances of the enriched model considering an initial-boundary value problem. To that purpose, the model has been implemented as user material in the engineering finite element computation code LS-DYNA. Numerical simulation of the dynamic shearing of hat shaped structures is conducted and the interest of accounting for the pre-failure stage consisting of micro-voiding in the ASB wake is emphasized.