Pulse-shape discrimination with PbWO4_4 crystal scintillators

The light output, $\alpha/\beta$ ratio, and pulse shape have been investigated at $-25^\circ$ C with PbWO$_4$ crystal scintillators undoped, and doped by F, Eu, Mo, Gd and S. The fast $0.01-0.06 \mu$s and middle $0.1-0.5 \mu$s components of scintillation decay were observed for all the samples. Slow components of scintillation signal with the decay times $1-3 \mu$s and $13-28 \mu$s with the total intensity up to $\approx50$ have been recognized for several samples doped by Molybdenum. We found some indications of a pulse-shape discrimination between $\alpha$ particles and $\gamma$ quanta with PbWO$_4$ (Mo doped) crystal scintillators.Comment: 12 pages, 5 figures, submitted to NIM

Lipid-coated zinc oxide nanocrystals as innovative ROS-generators for photodynamic therapy

Photodynamic Therapy (PDT) is a medical treatment that combines the administration of a nontoxic drug, called photosensitizer (PS), with light irradiation of the targeted region. It has been proposed as a new cancer therapy, promising better selectivity and fewer side-effects compared to traditional chemo- and radio-therapies. PSs indeed can accumulate specifically within the region of interest so that when the light is directly focused only in that region the therapeutic effect is highly localized. Traditional PSs, like chlorins and porphyrins, suffer from several drawbacks such as aggregation in biological media and poor biocompatibility. Thus, the development of innovative photosensitizers able to overcome these issues is crucial to the therapeutic action of PDT. Among the others, nanostructured Zinc Oxide (ZnO) has been recently proposed as new therapeutic agent and PS thanks to its semiconducting properties, biocompatible features, and ease of functionalization [1]. Nevertheless, further efforts are needed in order to improve its colloidal stability in biological media and to unravel the effective therapeutic mechanism. Here, we propose the synthesis and characterization of lipid-coated ZnO nanoparticles as new photosensitizer for cancer PDT [2]. First, by Dynamic Light Scattering (DLS) experiments, we show that the lipid-coating increases the colloidal stability of the ZnO NPs in Phosphate buffered saline (PBS). Then, using Electron Paramagnetic Resonance (EPR) coupled with the spin-trapping technique, we demonstrate and characterize the ability of bare and lipid-coated ZnO NPs to generate Reactive Oxygen Species (ROS) in water only when remotely actuated via light irradiation. Interestingly, our results aware that the surface chemistry of the NPs greatly influence the type of photo-generated ROS. Finally, we show that our NPs are effectively internalized inside human epithelial carcinoma cells (HeLa) via a lysosomal pathway and that they are able to generate ROS inside cancer cells. [1] B. Dumontel, M. Canta, H. Engelke, A. Chiodoni, L. Racca, A. Ancona, T. Limongi, G. Canavese and V. Cauda, ‎J. Mater. Chem. B. under revision. [2] A. Ancona, H. Engelke, N. Garino, B. Dumontel, W.Fazzini and V. Cauda, to be submitted. The support from ERC Starting Grant – Project N. 678151 “Trojananohorse” is gratefully acknowledged

Response of CdWO4 crystal scintillator for few MeV ions and low energy electrons

The response of a CdWO4 crystal scintillator to protons, alpha particles, Li, C, O and Ti ions with energies in the range 1 - 10 MeV was measured. The non-proportionality of CdWO4 for low energy electrons (4 - 110 keV) was studied with the Compton Coincidence Technique. The energy dependence of the quenching factors for ions and the relative light yield for low energy electrons was calculated using a semi-empirical approach. Pulse-shape discrimination ability between gamma quanta, protons, alpha particles and ions was investigated.Comment: 20 pages, 8 figs, accepted in Nucl. Instrum. Meth.

Endovascular stenting of the ascending aorta for type A aortic dissections in patients at high risk for open surgery

Background: Open repair is the gold standard for type A aortic dissection (TAAD). Endovascular option has been proposed in very limited and selected TAAD patients. We report our experience with endovascular TAAD repair. Methods: Inclusion criteria were: (1) entry tear in the ascending aorta; (2) proximal landing zone of at least 2 cm; (3) distance between entry tear and brachio-cephalic trunk of at least 0.5 cm; (4) no signs of cardiac tamponade or severe aortic regurgitation and (5) no signs of aortic branches ischaemia. Patients with cardiac revascularisation from ascending aorta were excluded. Results: From April 2009 to June 2012, 37 patients with TAAD were admitted to our hospital. As many as 28 underwent surgical repair and 9 were considered at high surgical risk in a multidisciplinary meeting. Four met our inclusion criteria for an endovascular approach. Two of them had previous ascending aortic repair for TAAD and one had aortic valve replacement. Technical success was achieved in 100% of the patients. No mortality was registered during a median follow-up of 15 months (range 4-39 months), no migration of the graft and complete false lumen thrombosis of the ascending aorta in three patients. Conclusion: Endovascular treatment of TAAD is challenging but feasible in a selected subset of patients. Further research remains mandatory. © 2013 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved

Investigating particle acceleration dynamics in interpenetrating magnetized collisionless super-critical shocks

Colliding collisionless shocks appear in a great variety of astrophysical phenomena and are thought to be possible sources of particle acceleration in the Universe. We have previously investigated particle acceleration induced by single super-critical shocks (whose magnetosonic Mach number is higher than the critical value of 2.7) (Yao et al. 2021, 2022), as well as the collision of two sub-critical shocks (Fazzini et al. 2022). Here, we propose to make measurements of accelerated particles from interpenetrating super-critical shocks to observe the ''phase-locking effect'' (Fazzini et al. 2022) from such an event. This effect is predicted to significantly boost the energy spectrum of the energized ions compared to a single supercritical collisionless shock. We thus anticipate that the results obtained in the proposed experiment could have a significant impact on our understanding of one type of primary source (acceleration of thermal ions as opposed to secondary acceleration mechanisms of already energetic ions) of ion energization of particles in the Universe

The new educational project Televascular Games during the Coronavirus Disease 2019 pandemic

Objective: To report methodology and first-year results of a new educational project called Televascular Games,” which took place during coronavirus disease 2019 pandemic. Methods: Complex aneurysmal aortic disease was discussed during a 2-hour competition webinar, according to three modalities. (1) Planning case competition (PCC): Two to four preoperative computed tomography angiography (CTA) scans of an already performed selected case were submitted for the competition. CTA scans were uploaded anonymously, without any reference to the center or the surgeon who performed the case. The competitor had to prepare a presentation of how he or she would have diagnosed, sized, planned, treated, and followed up the case, of the medical therapy and of the bail-out maneuvers. (2) Challenging case competition (CCC): The competitor elaborates a presentation of an already treated case concerning an aortic topic and discusses sizing, planning, treatment, possible bail-out maneuvers and obtained results. For the CCC and PCC, the competitors with the best score were preselected to present and discuss their plan during the webinars. (3) Quiz competition: Two to six CTA scans of already performed selected aortic cases were submitted for the competition. A quiz with multiple choice questions was answered by the competitors. The top four competitors were selected for the webinars and then they discussed the cases during the webinar. Finally, at the end of the case discussion, the effective case resolution and follow-up were shown. A final winner was voted via televoting, based on six preestablished criteria. The project was endorsed by different national and international societies. Results: Between October 2020 and December 2021, there were 12 Italian and 1 international webinars with 1695 participants overall (mean, 130; range, 86-177). Competitors were 54 years of age (mean, 27 years; range, 22-38 years). Two editions were CCCs, two quiz competitions, and nine PCCs. The reliability of the interobserver sizing of competitors was κ = 0.43 and κ = 0.62 for the proximal and distal sealing measurements respectively and very good (κ = 0.88-0.95) in the evaluation of orientation of the vessels, presence of angulations, calcifications, and thrombus. The sizing discrepancy resulted in a significant variability of the planning (κ = 0.45). The project ranked 9.6 on a 10-point rating scale by all the participants and competitors. Conclusions: The formula of gaming and collegial discussion of aortic cases herein reported has proved valid and attractive during coronavirus disease 2019 pandemic period. The variability of the results on sizing and planning suggested to confer with a second opinion, especially for less experienced surgeons

Assessment of digital image correlation measurement errors: methodology and results

Optical full-field measurement methods such as Digital Image Correlation (DIC) are increasingly used in the field of experimental mechanics, but they still suffer from a lack of information about their metrological performances. To assess the performance of DIC techniques and give some practical rules for users, a collaborative work has been carried out by the Workgroup “Metrology” of the French CNRS research network 2519 “MCIMS (Mesures de Champs et Identification en Mécanique des Solides / Full-field measurement and identification in solid mechanics, http://www.ifma.fr/lami/gdr2519)”. A methodology is proposed to assess the metrological performances of the image processing algorithms that constitute their main component, the knowledge of which being required for a global assessment of the whole measurement system. The study is based on displacement error assessment from synthetic speckle images. Series of synthetic reference and deformed images with random patterns have been generated, assuming a sinusoidal displacement field with various frequencies and amplitudes. Displacements are evaluated by several DIC packages based on various formulations and used in the French community. Evaluated displacements are compared with the exact imposed values and errors are statistically analyzed. Results show general trends rather independent of the implementations but strongly correlated with the assumptions of the underlying algorithms. Various error regimes are identified, for which the dependence of the uncertainty with the parameters of the algorithms, such as subset size, gray level interpolation or shape functions, is discussed