Magnetic anisotropy determination and magnetic hyperthermia properties of small Fe nanoparticles in the superparamagnetic regime

We report on the magnetic and hyperthermia properties of iron nanoparticles synthesized by organometallic chemistry. They are 5.5 nm in diameter and display a saturation magnetization close to the bulk one. Magnetic properties are dominated by the contribution of aggregates of nanoparticles with respect to individual isolated nanoparticles. Alternative susceptibility measurements are been performed on a low interacting system obtained after eliminating the aggregates by centrifugation. A quantitative analysis using the Gittleman s model allow a determination of the effective anisotropy Keff = 1.3 * 10^5 J.m^{-3}, more than two times the magnetocristalline value of bulk iron. Hyperthermia measurements are performed on agglomerates of nanoparticles at a magnetic field up to 66 mT and at frequencies in the range 5-300 kHz. Maximum measured SAR is 280 W/g at 300 kHz and 66 mT. Specific absorption rate (SAR) displays a square dependence with the magnetic field below 30 mT but deviates from this power law at higher value. SAR is linear with the applied frequency for mu_0H=19 mT. The deviations from the linear response theory are discussed. A refined estimation of the optimal size of iron nanoparticles for hyperthermia applications is provided using the determined effective anisotropy value

Magnetic hyperthermia in single-domain monodisperse FeCo nanoparticles: Evidences for Stoner-Wohlfarth behaviour and large losses

We report on hyperthermia measurements on a colloidal solution of 15 nm monodisperse FeCo nanoparticles (NPs). Losses as a function of the magnetic field display a sharp increase followed by a plateau, which is what is expected for losses of ferromagnetic single-domain NPs. The frequency dependence of the coercive field is deduced from hyperthermia measurement and is in quantitative agreement with a simple model of non-interacting NPs. The measured losses (1.5 mJ/g) compare to the highest of the literature, though the saturation magnetization of the NPs is well below the bulk one.Comment: 14 pages, 3 figure

Tuning complex shapes in Pt(0) nanoparticles : from cubic dendrites to five-fold stars

A platinum star performance: Quasi-single-crystalline Pt nanoparticles with peculiar morphologies—cubic dendrites, planar tripods, and fivefold stars—were synthesized in high yield. Shape selectivity was achieved by finely tuning the growth kinetics under a dihydrogen atmosphere

Large specific absorption rates in the magnetic hyperthermia properties of metallic iron nanocubes

We report on the magnetic hyperthermia properties of chemically synthesized ferromagnetic 11 and 16 nm Fe(0) nanoparticles of cubic shape displaying the saturation magnetization of bulk iron. The specific absorption rate measured on 16 nm nanocubes is 1690+-160 W/g at 300 kHz and 66 mT. This corresponds to specific losses-per-cycle of 5.6 mJ/g, largely exceeding the ones reported in other systems. A way to quantify the degree of optimization of any system with respect to hyperthermia applications is proposed. Applied here, this method shows that our nanoparticles are not fully optimized, probably due to the strong influence of magnetic interactions on their magnetic response. Once protected from oxidation and further optimized, such nano-objects could constitute efficient magnetic cores for biomedical applications requiring very large heating power

Fragmentation branching ratios of highly excited hydrocarbon molecules CnH and their cations CnH+ (n<4)

We have measured fragmentation branching ratios of neutral CnH and CnH+ cations produced in high velocity (4.5 a.u) collisions between incident CnH+ cations and helium atoms. Electron capture gives rise to excited neutral species CnH and electronic excitation to excited cations CnH+. Thanks to a dedicated set-up, based on coincident detection of all fragments, the dissociation of the neutral and cationic parents were recorded separately and in a complete way. For the fragmentation of CnH, the H-loss channel is found to be dominant, as already observed by other authors. By contrast, the H-loss and C-loss channels equally dominate the two-fragment break up of CnH+ species. For these cations, we provide the first fragmentation data (n > 2). Results are also discussed in the context of astrochemistry

Autoantibodies against type I IFNs in patients with critical influenza pneumonia

In an international cohort of 279 patients with hypoxemic influenza pneumonia, we identified 13 patients (4.6%) with autoantibodies neutralizing IFN-alpha and/or -omega, which were previously reported to underlie 15% cases of life-threatening COVID-19 pneumonia and one third of severe adverse reactions to live-attenuated yellow fever vaccine. Autoantibodies neutralizing type I interferons (IFNs) can underlie critical COVID-19 pneumonia and yellow fever vaccine disease. We report here on 13 patients harboring autoantibodies neutralizing IFN-alpha 2 alone (five patients) or with IFN-omega (eight patients) from a cohort of 279 patients (4.7%) aged 6-73 yr with critical influenza pneumonia. Nine and four patients had antibodies neutralizing high and low concentrations, respectively, of IFN-alpha 2, and six and two patients had antibodies neutralizing high and low concentrations, respectively, of IFN-omega. The patients' autoantibodies increased influenza A virus replication in both A549 cells and reconstituted human airway epithelia. The prevalence of these antibodies was significantly higher than that in the general population for patients 70 yr of age (3.1 vs. 4.4%, P = 0.68). The risk of critical influenza was highest in patients with antibodies neutralizing high concentrations of both IFN-alpha 2 and IFN-omega (OR = 11.7, P = 1.3 x 10(-5)), especially those <70 yr old (OR = 139.9, P = 3.1 x 10(-10)). We also identified 10 patients in additional influenza patient cohorts. Autoantibodies neutralizing type I IFNs account for similar to 5% of cases of life-threatening influenza pneumonia in patients <70 yr old

Direct oral anticoagulants versus no anticoagulation for the prevention of stroke in survivors of intracerebral haemorrhage with atrial fibrillation (PRESTIGE-AF): a multicentre, open-label, randomised, phase 3 trial.

Background Direct oral anticoagulants (DOACs) reduce the rate of thromboembolism in patients with atrial fibrillation but the benefits and risks in survivors of intracerebral haemorrhage are uncertain. We aimed to determine whether DOACs reduce the risk of ischaemic stroke without substantially increasing the risk of recurrent intracerebral haemorrhage. Methods PRESTIGE-AF is a multicentre, open-label, randomised, phase 3 trial conducted at 75 hospitals in six European countries. Eligible patients were aged 18 years or older with spontaneous intracerebral haemorrhage, atrial fibrillation, an indication for anticoagulation, and a score of 4 or less on the modified Rankin Scale. Patients were randomly assigned (1:1) to a DOAC or no anticoagulation, stratified by intracerebral haemorrhage location and sex. Only the events adjudication committee was masked to treatment allocation. The coprimary endpoints were first ischaemic stroke and first recurrent intracerebral haemorrhage. Hierarchical testing for superiority and non-inferiority, respectively, was performed in the intention-to-treat population. The margin to establish non-inferiority regarding intracerebral haemorrhage was less than 1·735. The safety analysis was done in the intention-to-treat population. The trial is registered with ClinicalTrials.gov, NCT03996772, and is complete. Findings Between May 31, 2019, and Nov 30, 2023, 319 participants were enrolled and 158 were randomly assigned to the DOAC group and 161 to the no anticoagulant group. Patients' median age was 79 years (IQR 73–83). 113 (35%) of 319 patients were female and 206 (65%) were male. Median follow-up was 1·4 years (IQR 0·7–2·3). First ischaemic stroke occurred less frequently in the DOAC group than in the no anticoagulant group (hazard ratio [HR] 0·05 [95% CI 0·01–0·36]; log-rank p<0·0001). The rate of all ischaemic stroke events was 0·83 (95% CI 0·14–2·57) per 100 patient-years in the DOAC group versus 8·60 (5·43–12·80) per 100 patient-years in the no anticoagulant group. For first recurrent intracerebral haemorrhage, the DOAC group did not meet the prespecified HR for the non-inferiority margin of less than 1·735 (HR 10·89 [90% CI 1·95–60·72]; p=0·96). The event rate of all intracerebral haemorrhage was 5·00 (95% CI 2·68–8·39) per 100 patient-years in the DOAC group versus 0·82 (0·14–2·53) per 100 patient years in the no anticoagulant group. Serious adverse events occurred in 70 (44%) of 158 patients in the DOAC group and 89 (55%) of 161 patients in the no anticoagulant group. 16 (10%) patients in the DOAC group and 21 (13%) patients in the no anticoagulant group died. Interpretation DOACs effectively prevent ischaemic strokes in survivors of intracerebral haemorrhage with atrial fibrillation but a part of this benefit is offset by a substantially increased risk of recurrent intracerebral haemorrhage. To optimise stroke prevention in these vulnerable patients, further evidence from ongoing trials and a meta-analysis of randomised data is needed, as well as the evaluation of safer medical or mechanical alternatives for selected patients

Burden of intracerebral haemorrhage in Europe: forecasting incidence and mortality between 2019 and 2050

Background: Anticipating the burden of intracerebral haemorrhage is crucial for proactive management and building resilience against future health challenges. Prior forecasts are based on population demography and to a lesser extent epidemiological trends. This study aims to utilise selected modifiable risk factors and socio-demographic indicators to forecast the incidence and mortality of intracerebral haemorrhage in Europe between 2019 and 2050. Methods: Three intracerebral haemorrhage risk factors identified in the Global Burden of Diseases, Injuries, and Risk Factors study (GBD 2019)—high systolic blood pressure, high fasting plasma glucose, and high body mass index—were utilised to predict the risk-attributable fractions between 2019 and 2050. Disease burden not attributable to these risk factors was then forecasted using time series models (autoregressive integrated moving average [ARIMA]), incorporating the Socio-demographic Index (SDI) as an external predictor. The optimal parameters of ARIMA models were selected for each age-sex-country group based on the Akaike Information Criterion (AIC). Different health scenarios were constructed by extending the past 85th and 15th percentiles of annualised rates of change in risk factors and SDI across all location-years, stratified by age and sex groups. A decomposition analysis was performed to assess the relative contributions of population size, age composition, and intracerebral haemorrhage risk on the projected changes. Findings: Compared with observed figures in 2019, our analysis predicts an increase in the burden of intracerebral haemorrhage in Europe in 2050, with a marginal rise of 0.6% (95% uncertainty interval [UI], −7.4% to 9.6%) in incident cases and an 8.9% (−2.8% to 23.6%) increase in mortality, reaching 141.2 (120.6–166.5) thousand and 144.2 (122.9–172.2) thousand respectively. These projections may fluctuate depending on trajectories of the risk factors and SDI; worsened trends could result in increases of 16.7% (8.7%–25.3%) in incidence and 31.2% (17.7%–48%) in mortality, while better trajectories may lead to a 10% (16.4%–2.3%) decrease in intracerebral haemorrhage cases with stabilised mortality. Individuals aged ≥80 years are expected to contribute significantly to the burden, comprising 62.7% of the cases in 2050, up from 40% in 2019, and 72.5% of deaths, up from 50.5%. Country-wide variations were noted in the projected changes, with decreases in the standardised rates across all nations but varying crude rates. The largest relative reductions in counts for both incidence and mortality are expected in Latvia, Bulgaria, and Hungary—ranging from −38.2% to −32.4% and −37.3% to −30.2% respectively. In contrast, the greatest increases for both measures were forecasted in Ireland (45.7% and 74.4%), Luxembourg (45% and 70.7%), and Cyprus (44.5% and 74.2%). The modelled increase in the burden of intracerebral haemorrhage could largely be attributed to population ageing. Interpretation: This study provides a comprehensive forecast of intracerebral haemorrhage in Europe until 2050, presenting different trajectories. The potential increase in the number of people experiencing and dying from intracerebral haemorrhage could have profound implications for both caregiving responsibilities and associated costs. However, forecasts were divergent between different scenarios and among EU countries, signalling the pivotal role of public health initiatives in steering the trajectories. Funding: TheEuropean Union's Horizon 2020 Research and Innovation Programme under grant agreement No.754517. TheNational Institute for Health and Care Research (NIHR) under its Programme Grants forApplied Research (NIHR202339)