Evolution of magnetic and microstructural properties of thick sputtered NdFeB films with processing temperature

Ta (100 nm) / NdFeB (5 $\mu$m) / Ta (100 nm) films have been deposited onto Si substrates using triode sputtering (deposition rate ~ 18 $\mu$m/h). A 2-step procedure was used : deposition at temperatures up to 400 C followed by ex-situ annealing at higher temperatures. Post-deposition annealing temperatures above 650 C are needed to develop high values of coercivity. The duration of the annealing time is more critical in anisotropic samples deposited onto heated substrates than in isotropic samples deposited at lower temperatures. For a given set of annealing conditions (750 C/ 10'), high heating rates (≥ 2000 C / h) favour high coercivity in both isotropic and anisotropic films. The shape and size of Nd2Fe14B grains depend strongly on the heating rate

Quantum gates using electronic and nuclear spins of Yb+^{+} in a magnetic field gradient

An efficient scheme is proposed to carry out gate operations on an array of trapped Yb$^+$ ions, based on a previous proposal using both electronic and nuclear degrees of freedom in a magnetic field gradient. For this purpose we consider the Paschen-Back regime (strong magnetic field) and employ a high-field approximation in this treatment. We show the possibility to suppress the unwanted coupling between the electron spins by appropriately swapping states between electronic and nuclear spins. The feasibility of generating the required high magnetic field is discussed

Impact of Preoperative Chemotherapy Features on Patient Outcomes after Hepatectomy for Initially Unresectable Colorectal Cancer Liver Metastases: A LiverMetSurvey Analysis

Background: Prognostic factors have been extensively reported after resection of colorectal liver metastases (CLM); however, specific analyses of the impact of preoperative systemic anticancer therapy (PO-SACT) features on outcomes is lacking. Methods: For this real-world evidence study, we used prospectively collected data within the international surgical LiverMetSurvey database from all patients with initially-irresectable CLM. The main outcome was Overall Survival (OS) after surgery. Disease-free (DFS) and hepatic-specific relapse-free survival (HS-RFS) were secondary outcomes. PO-SACT features included duration (cumulative number of cycles), choice of the cytotoxic backbone (oxaliplatin- or irinotecan-based), fluoropyrimidine (infusional or oral) and addition or not of targeted monoclonal antibodies (anti-EGFR or anti-VEGF). Results: A total of 2793 patients in the database had received PO-SACT for initially irresectable diseases. Short (<7 or <13 cycles in 1st or 2nd line) PO-SACT duration was independently associated with longer OS (HR: 0.85 p = 0.046), DFS (HR: 0.81; p = 0.016) and HS-RFS (HR: 0.80; p = 0.05). All other PO-SACT features yielded basically comparable results. Conclusions: In this international cohort, provided that PO-SACT allowed conversion to resectability in initially irresectable CLM, surgery performed as soon as technically feasible resulted in the best outcomes. When resection was achieved, our findings indicate that the choice of PO-SACT regimen had a marginal if any, impact on outcomes.info:eu-repo/semantics/publishedVersio

Global overview of the management of acute cholecystitis during the COVID-19 pandemic (CHOLECOVID study)

Background: This study provides a global overview of the management of patients with acute cholecystitis during the initial phase of the COVID-19 pandemic. Methods: CHOLECOVID is an international, multicentre, observational comparative study of patients admitted to hospital with acute cholecystitis during the COVID-19 pandemic. Data on management were collected for a 2-month study interval coincident with the WHO declaration of the SARS-CoV-2 pandemic and compared with an equivalent pre-pandemic time interval. Mediation analysis examined the influence of SARS-COV-2 infection on 30-day mortality. Results: This study collected data on 9783 patients with acute cholecystitis admitted to 247 hospitals across the world. The pandemic was associated with reduced availability of surgical workforce and operating facilities globally, a significant shift to worse severity of disease, and increased use of conservative management. There was a reduction (both absolute and proportionate) in the number of patients undergoing cholecystectomy from 3095 patients (56.2 per cent) pre-pandemic to 1998 patients (46.2 per cent) during the pandemic but there was no difference in 30-day all-cause mortality after cholecystectomy comparing the pre-pandemic interval with the pandemic (13 patients (0.4 per cent) pre-pandemic to 13 patients (0.6 per cent) pandemic; P = 0.355). In mediation analysis, an admission with acute cholecystitis during the pandemic was associated with a non-significant increased risk of death (OR 1.29, 95 per cent c.i. 0.93 to 1.79, P = 0.121). Conclusion: CHOLECOVID provides a unique overview of the treatment of patients with cholecystitis across the globe during the first months of the SARS-CoV-2 pandemic. The study highlights the need for system resilience in retention of elective surgical activity. Cholecystectomy was associated with a low risk of mortality and deferral of treatment results in an increase in avoidable morbidity that represents the non-COVID cost of this pandemic

Approches novatrices à la génération de champs magnétiques intenses : optimisation d'une source de flux à aimants permanents

Notre recherche consiste à concevoir et réaliser une source de flux statique à aimants permanents générant un champ de 4 à 5 Tesla dans un volume de quelques mm3. Un des aspects novateurs de cette approche est que nous avons cherché à obtenir un champ magnétique intense (principe du dipôle ponctuel) et non pas un champ magnétique homogène (principe du dipôle infini utilisé dans les structures de Leupold/Halbach). Après optimisation du modèle analytique, nous avons discrétisé la structure de manière à obtenir un modèle réalisable à partir de pavé d'aimants réels. Une originalité du travail est la recherche d'une géométrie performante et une combinaison de divers matériaux magnétiques durs (nuances d'aimants Néodyme-Fer-Bore) et de matériau magnétique doux (Fer-Cobalt). Les configurations particulières d'aimants sont optimisées par simulation numérique grâce à des logiciels complémentaires, développés par le LEG : DIPOLE-3D (calcul analytique de champ), FLUX2D et FLUX3D (éléments finis). L'étude de faisabilité du projet a été réalisée en calculant les forces et les champs démagnétisants lors de la séquence de montage. Le modèle de source actuel fournit un champ atteignant 4,3 T dans un volume de diamètre de 6 mm pour une hauteur de 2,8 mm et ayant un diamètre extérieur de 100 mm

HIGH EFFICIENCY 3-PHASE CMOS RECTIFIER WITH STEP UP AND REGULATED

This paper presents several design issues related to the monolithic integration of a 3-phase AC to DC low voltage, low power rectifier for 3-phase micro source electrical conditioning. Reduced input voltage operation (down to 1V), high efficiency, and output voltage regulations are implemented, based on commercially available CMOS technology. Global design and system issues are detailed. The management of start-up sequences under self supplied conditions as well as output voltage regulations are specifically addressed. Simulation results, practical implementation and validation are presented. They are based on the association of three micro elements : a 3-phase micro-generator, a stand alone 3-phase AC to DC integrated rectifier, and an output voltage conditioner based on a commercially available IC

Deformable magnetic mirror for adaptive optics: first results

An alternative approach to compact deformable mirrors for adaptive optics is developed. A prototype of a two inch mirror composed of a thin polymer membrane covered with a matrix of permanent magnets and an array of microcoils was built. Several complementary modelling tools were used to study the behaviour of the device. Promising first results show regular deformations of up to 20 mu m, a good linearity and a bandwith of 200 Hz. This novel technology should enable higher resolution with smaller, lighter integrated mirrors

An induction micromotor on a permanent magnet bearing

A first operational prototype of induction electromagnetic micromotor (OE18*2 mm) mounted on a magnetic bearing was built and tested. The maximum speed reached is 4500 rpm, and the corresponding measured torque 1.2 mu Nm. Induction devices therefore seem viable to be miniaturised