Dispersions of magnetic nanoparticles in water/ionic liquid mixtures.

Nanoparticles (NPs) of iron oxide are dispersed in mixtures of water and ionic liquid, here ethylammonium nitrate (EAN), and the NP/NP and NP/solvent interactions are studied. They are analysed via small-angle X-ray scattering and dynamic light scattering coupled to forced Rayleigh scattering, from 22 °C to 80 °C. The NPs are well-dispersed as individual objects in the whole range of compositions and temperatures thanks to sufficient repulsion due to the organization of the solvents at the interface. The surface changes from hydrophilic to hydrophobic around a proportion of 50 vol% water : 50 vol% EAN, following the evolution of the bulk mixtures, which remain heterogeneous in the whole range of compositions.

Ion specific tuning of nanoparticle dispersion in an ionic liquid: a structural, thermoelectric and thermo-diffusive investigation.

Dispersions of charged maghemite nanoparticles (NPs) in EAN (ethylammonium nitrate) a reference Ionic Liquid (IL) are studied here using a number of static and dynamical experimental techniques; small angle scattering (SAS) of X-rays and of neutrons, dynamical light scattering and forced Rayleigh scattering. Particular insight is provided regarding the importance of tuning the ionic species present at the NP/IL interface. In this work we compare the effect of Li+, Na+ or Rb+ ions. Here, the nature of these species has a clear influence on the short-range spatial organisation of the ions at the interface and thus on the colloidal stability of the dispersions, governing both the NP/NP and NP/IL interactions, which are both evaluated here. The overall NP/NP interaction is either attractive or repulsive. It is characterised by determining, thanks to the SAS techniques, the second virial coefficient A2, which is found to be independent of temperature. The NP/IL interaction is featured by the dynamical effective charge ξeff0 of the NPs and by their entropy of transfer SNP (or equivalently their heat of transport ) determined here thanks to thermoelectric and thermodiffusive measurements. For repulsive systems, an activated process rules the temperature dependence of these two latter quantities.

[CT scan in syncope : diagnostic yield and prescription habits]. / Imagerie CT des syncopes : apport diagnostique et habitudes de prescription.

Syncope is a frequent reason for emergency department admission. Brain imaging is theoretically not recommended. After exclusion of features orienting towards non-syncopal events, we retrospectively included 206 patients who underwent head CT scans in the University Hospital of Liège for transient loss of consciousness between December 2020 and July 2021. We surveyed physicians involved in the emergency department concerning their imaging prescription habits and motivations. CT diagnostic yield is 1 %. The oncologic background is associated with pathological findings (odds ratio 84,1, p = 0,005). Cervical angio-CT scans only lead to incidental findings and increased dose exposure. Only a minority (6.6 %) of physicians systematically prescribe brain imaging. Radioprotection is an important notion for only 10 % of the less experimented physicians. Obligation of means is an occasional justification for resort to imaging. A prospective decisional rule based on the exclusion of features orienting towards non-syncopal loss of cousciousness, old age and oncologic history might reduce the number of useless scans. Radioprotection is too often neglected by less experimented physicians. Obligation of means should not be mingled with reassurance behaviors as part of defensive medicine.

La syncope est un motif fréquent d'admission aux Urgences. La réalisation d'une imagerie encéphalique n'est, théoriquement, pas recommandée. Après exclusion de critères évocateurs d'une étiologie non syncopale, nous avons rétrospectivement inclus 206 patients ayant passé un CT cérébral entre décembre 2020 et juillet 2021 au CHU de Liège pour perte de connaissance brève. Nous avons sondé les médecins impliqués dans le service des Urgences concernant leur habitudes de prescription. L'apport diagnostique du CT est de 1 %. Un contexte oncologique est associé aux résultats iconographiques pathologiques (odds ratio 84,1; p = 0,005). L'angio-CT cervical ne permet que la mise en évidence d'incidentalomes au prix d'une majoration de l'irradiation. Une minorité (6,6 %) de prescripteurs a systématiquement recours à l'imagerie. La radioprotection est jugée importante par seulement 10 % des intervenants les moins expérimentés et l'obligation de moyens est parfois avancée comme justification de prescription. Des critères décisionnels prospectifs (exclusion d'éléments évocateurs de pertes de connaissance non syncopales, âge et contexte oncologique) permettraient de réduire le nombre d'examens inutiles. La radioprotection est trop souvent négligée par les prescripteurs les moins expérimentés. L'obligation de moyens ne doit pas être confondue avec des comportements de réassurance dans le cadre de la médecine défensive.

Thermodiffusion anisotropy under a magnetic field in ionic liquid-based ferrofluids.

Ferrofluids based on maghemite nanoparticles (NPs), typically 10 nm in diameter, are dispersed in an ionic liquid (1-ethyl 3-methylimidazolium bistriflimide - EMIM-TFSI). The average interparticle interaction is found to be repulsive by small angle scattering of X-rays and of neutrons, with a second virial coefficient A2 = 7.3. A moderately concentrated sample at Φ = 5.95 vol% is probed by forced Rayleigh scattering under an applied magnetic field (up to H = 100 kA m-1) from room temperature up to T = 460 K. Irrespective of the values of H and T, the NPs in this study are always found to migrate towards the cold region. The in-field anisotropy of the mass diffusion coefficient Dm and that of the (always positive) Soret coefficient ST are well described by the presented model in the whole range of H and T. The main origin of anisotropy is the spatial inhomogeneities of concentration in the ferrofluid along the direction of the applied field. Since this effect originates from the magnetic dipolar interparticle interaction, the anisotropy of thermodiffusion progressively vanishes when temperature and thermal motion increase.

[Concepts of medical imaging in the work up and follow-up of cancer : oncological imaging at a glance]. / Concepts d'imagerie médicale dans la mise au point et le suivi des cancers : regard sur l'imagerie oncologique.

Oncological imaging is a subspecialty of medical imaging and focuses on the workup and the follow-up of cancer. Oncological imaging takes into account all the specificities of cancer diseases, which is a constantly evolving field, especially in the era of precision medicine, and plays a key role in the care of cancer patients. It permits reliable diagnosis and gives precious information concerning disease extension at diagnosis, which is essential for the treatment planning. Oncological imaging allows also followup of patients under treatment, using response evaluation scores. Interventional imaging, which provides minimally invasive procedures, is useful in order to obtain a histological diagnosis, to treat some tumour or to improve quality of life of cancer patients. Finally, numerous perspectives, among them the advent of artificial intelligence (radiomics), will further strengthen the role of oncologic imaging in the near future.

L'imagerie oncologique, qui est une sous-discipline de l'imagerie médicale, s'intéresse spécifiquement à la mise au point et au suivi des cancers. Elle prend en compte toutes les spécificités de la maladie oncologique, dont les traitements évoluent constamment à l'ère de la médecine de précision. Elle joue un rôle primordial à toutes les étapes du trajet de soin du patient. Elle permet la réalisation de diagnostics fiables et donne des informations sur l'étendue de la maladie au moment du diagnostic, nécessaires à l'établissement d'un plan de traitement. L'imagerie oncologique s'intéresse également au suivi des patients sous traitement, grâce notamment à l'utilisation de score d'évaluation de la réponse thérapeutique. L'imagerie interventionnelle, à travers la réalisation de procédures faiblement invasives, joue un rôle dans l'obtention du diagnostic, dans le traitement de certaines tumeurs ou dans l'amélioration de la qualité de vie du patient. Enfin, de nombreuses perspectives, et notamment l'avènement de l'intelligence artificielle (radiomique), ne vont faire que renforcer le rôle central de l'imagerie oncologique dans les prochaines années.

Submicrometric Films of Surface-Attached Polymer Network with Temperature-Responsive Properties.

Temperature-responsive properties of surface-attached poly(N-isopropylacrylamide) (PNIPAM) network films with well-controlled chemistry are investigated. The synthesis consists of cross-linking and grafting preformed ene-reactive polymer chains through thiol-ene click chemistry. The formation of surface-attached and cross-linked polymer films has the advantage of being well-controlled without any caution of no-oxygen atmosphere or addition of initiators. PNIPAM hydrogel films with same cross-link density are synthesized on a wide range of thickness, from nanometers to micrometers. The swelling-collapse transition with temperature is studied by using ellipsometry, neutron reflectivity, and atomic force microscopy as complementary surface-probing techniques. Sharp and high amplitude temperature-induced phase transition is observed for all submicrometric PNIPAM hydrogel films. For temperature above LCST, surface-attached PNIPAM hydrogels collapse similarly but without complete expulsion of water. For temperature below LCST, the swelling of PNIPAM hydrogels depends on the film thickness. It is shown that the swelling is strongly affected by the surface attachment for ultrathin films below ∼150 nm. For thicker films above 150 nm (to micrometers), surface-attached polymer networks with the same cross-link density swell equally. The density profile of the hydrogel films in the direction normal to the substrate is confronted with in-plane topography of the free surface. It results that the free interface width is much larger than the roughness of the hydrogel film, suggesting pendant chains at the free surface.

Correction: Breaking of the Bancroft rule for multiple emulsions stabilized by a single stimulable polymer.

Correction for 'Breaking of the Bancroft rule for multiple emulsions stabilized by a single stimulable polymer' by L. Besnard et al., Soft Matter, 2014, 10, 7073-7087.

Tuning the colloidal stability in ionic liquids by controlling the nanoparticles/liquid interface.

To shed light on the origin of colloidal stability in ionic liquids,we focus on a model colloidal system (maghemite nanoparticles) in which surface charge and counterion nature can be controlled at will. We thus evidence the crucial role of interfacial features on dispersion quality in a standard ionic liquid, ethylammonium nitrate.

Breaking of the Bancroft rule for multiple emulsions stabilized by a single stimulable polymer.

We investigated emulsions of water and toluene stabilized by (co)polymers consisting of styrene (S) and 2-(dimethylamino)ethyl methacrylate (DMAEMA) monomer units with different compositions and structures such as a PDMAEMA homopolymer, a P(S-co-DMAEMA) random copolymer and various PS-b-PDMAEMA and PS-b-(S-co-DMAEMA) block copolymers. The model system is used to study the fundamental conditions under which the different kinds of polymer-stabilized emulsions (direct oil in water, inverse water in oil and multiple emulsions) are stabilized or destabilized by pH change (at constant temperature). Polymer properties like chain conformation at the toluene-water interface as probed by SANS and neutron reflectivity at the liquid-liquid interface, the oil-water partitioning of the polymer chains (Bancroft's rule of thumb) as determined by UV spectroscopy and interfacial tensions measured by the rising and spinning drop techniques are determined. Overall, results evidence that the curvature sign, as defined by positive and negative values as the chain segments occupy preferentially the water and toluene sides of the interface respectively, reliably predicts the emulsion kind. In contrast, the Bancroft rule failed at foreseeing the emulsion type. In the region of near zero curvature the crossover from direct to inverse emulsions occurs through the formation of either unstable coexisting direct and inverse emulsions (i) or multiple emulsions (ii). The high compact adsorption of the chains at the interface as shown by low interfacial tension values does not allow to discriminate between both cases. However, the toluene-water partitioning of the polymeric emulsifier is still a key factor driving the formation of (i) or (ii) emulsions. Interestingly, the stabilization of the multiple emulsions can be tuned to a large extent as the toluene-water polymer partitioning can be adjusted using quite a large number of physico-chemical parameters linked to polymer architecture like diblock length ratio or polymer total molar mass, for example. Moreover, we show that monitoring the oil-water partitioning aspect of the emulsion system can also be used to lower the interfacial tension at low pH to values slightly higher than 0.01 mN m(-1), irrespective of the curvature sign.

[Crohn's disease and MRI: assessment of inflammatory activity and tissue damage]. / Maladie de Crohn et entéro-IRM évaluation de l'activité de la maladie et du dommage tissulaire.

Crohn's disease is an inflammatory bowel disease that affects mainly young people and includes periods of remission interspersed with occasional flare-ups. Entero-MR (Magnetic Resonance) is a non-radiating and a non-invasive tomography imaging technique. Entero-MR has recently proven its ability to assess inflammatory activity and structural damage of the bowel in Crohn's disease which are fundamental elements in the therapy planning. These considerations explain why entero-MR is playing an increasing role in the evaluation of Crohn's disease.

[RÉALITÉ LT, a pharmacoepidemiological study of semiology and therapeutic strategy of patients with schizophrenia treated by antipsychotic loxapine in routine clinical practice]. / RÉALITÉ LT : Recherche Épidémiologique sur l'Activité de la Loxapine et ses Indications en Thérapeutique quotidiennE lors d'une utilisation à Long Terme. Étude pharmacoépidémiologique : sémiologie et stratégie thérapeutique d'une population de patients présentant des troubles schizophréniques traités par loxapine.

INTRODUCTION: Data concerning the clinical and therapeutic characteristics of patients with schizophrenia treated by antipsychotic in naturalistic conditions are useful. Two national pharmacoepidemiological studies were conducted in France, a retrospective survey RÉALITÉ and a prospective study RÉALITÉ LT, to examine the use of loxapine, first in acute and chronic psychotic states and second in long-term treatment prescribed for patients with schizophrenia. AIM OF STUDY: The aim of RÉALITÉ LT is to specify the clinical characteristics of schizophrenic patients treated by loxapine for at least 4 months and the description of the methods of use of this antipsychotic medication during a 6-month follow-up in "real life" conditions. DESIGN OF STUDY: RÉALITÉ LT is an epidemiologic, observational, longitudinal, prospective (during a half-year period), multicenter and national study of the prescription of loxapine in routine clinical practice. For this study, 645 patients with schizophrenia treated by loxapine were recruited, assessed by PANSS, CGI, GAF, MeDra-SOC-PT for side effects and Girerd questionnaire for compliance; statistical analysis used SAS 9.2. RESULTS: Six hundred and forty-five adult patients were included and assessed at inclusion, month 3 and 6. These patients were mostly male (69%), with an average age of 41, inactive (68%), lonely with no child (79%), under psychiatric care for more than 5 years (81%), less than one third were inpatients. The subtypes of schizophrenia were paranoid (59%), disorganised (21%), undifferentiated or residual (10%), the outcome of psychotic illness was episodic (50%) or continuous (33%). The daily mean dosage of loxapine was 168,4 mg/d, in antipsychotic loxapine monotherapy (27%) or in combination with other antipsychotics (63%); it was often associated with psychotropic medications (anxiolytic [72%], antidepressant [21%], normothymic [19%]). The stability of the dosage of loxapine during the 6 months follow-up (60%) was associated with strict loxapine monotherapy or antipsychotic monotherapy (loxapine associated with other psychotropic medication). Safety, side effects and compliance were compared with previous studies. DISCUSSION AND CONCLUSION: These results are discussed, comparing the two pharmacoepidemiological studies RÉALITÉ and RÉALITÉ LT, loxapine is used in compliance with the two indications (smpc) and French guidelines (HAS, Haute Autorité de santé).

Design of concentrated colloidal dispersions of iron oxide nanoparticles in ionic liquids: Structure and thermal stability from 25 to 200 °C.

HYPOTHESIS: Some of the most promising fields of application of ionic liquid-based colloids imply elevated temperatures. Their careful design and analysis is therefore essential. We assume that tuning the structure of the nanoparticle-ionic liquid interface through its composition can ensure colloidal stability for a wide temperature range, from room temperature up to 200 °C. EXPERIMENTS: The system under study consists of iron oxide nanoparticles (NPs) dispersed in ethylmethylimidazolium bistriflimide (EMIM TFSI). The key parameters of the solid-liquid interface, tuned at room temperature, are the surface charge density and the nature of the counterions. The thermal stability of these nanoparticle dispersions is then analysed on the short and long term up to 200 °C. A multiscale analysis is performed combining dynamic light scattering (DLS), small angle X-ray/neutron scattering (SAXS/SANS) and thermogravimetric analysis (TGA). FINDINGS: Following the proposed approach with a careful choice of the species at the solid-liquid interface, ionic liquid-based colloidal dispersions of iron oxide NPs in EMIM TFSI stable over years at room temperature can be obtained, also stable at least over days up to 200 °C and NPs concentrations up to 12 vol% (≈30 wt%) thanks to few near-surface ionic layers.

Evidence of deep water penetration in silica during stress corrosion fracture.

We measure the thickness of the heavy water layer trapped under the stress corrosion fracture surface of silica using neutron reflectivity experiments. We show that the penetration depth is 65-85   Å, suggesting the presence of a damaged zone of ∼100   Šextending ahead of the crack tip during its propagation. This estimate of the size of the damaged zone is compatible with other recent results.

Rodlike complexes of a polyelectrolyte (hyaluronan) and a protein (lysozyme) observed by SANS.

We study by small-angle neutron scattering (SANS) the structure of hyaluronan -lysozyme complexes. Hyaluronan (HA) is a polysaccharide of 9 nm intrinsic persistence length that bears one negative charge per disaccharide monomer (M(mol) = 401.3 g/mol); two molecular weights, M(w) = 6000 and 500,000 Da were used. The pH was adjusted at 4.7 and 7.4 so that lysozyme has a global charge of +10 and +8, respectively. The lysozyme concentration was varied from 3 to 40 g/L at constant HA concentration (10 g/L). At low protein concentration, samples are monophasic, and SANS experiments reveal only fluctuations of concentration, although, at high protein concentration, clusters are observed by SANS in the dense phase of the diphasic samples. In between, close to the onset of the phase separation, a distinct original scattering is observed. It is characteristic of a rod-like shape, which could characterize "single" complexes involving one or a few polymer chains. For the large molecular weight (500,000), the rodlike rigid domains extend to much larger length scale than the persistence length of the HA chain alone in solution and the range of the SANS investigation. They can be described as a necklace of proteins attached along a backbone of diameter of one or a few HA chains. For the short chains (M(w) ≈ 6000), the rod length of the complexes is close to the chain contour length (∼ 15 nm).

Colloidal dispersions of oxide nanoparticles in ionic liquids: elucidating the key parameters.

The combination of ionic liquid and nanoparticle properties is highly appealing for a number of applications. However, thus far there has been limited systematic exploration of colloidal stabilisation in these solvents, which provides an initial direction towards their employment. Here, we present a new and comprehensive study of the key parameters affecting the colloidal stability in dispersions of oxide nanoparticles in ionic liquids. Twelve diverse and representative ionic liquids are used to disperse iron oxide nanoparticles. The liquid interface of these nanoparticles has been carefully tuned in a molecular solvent before transferring into an ionic liquid, without passing through the powder state. Multiscale-characterisation is applied, on both the micro and the nano scale, incorporating both small angle X-ray scattering and dynamic light scattering. The results show the surface charge of the nanoparticles to be a crucial parameter, controlling the layering of the surrounding ionic liquid, and hence producing repulsion allowing efficient counterbalancing of the attractive interactions. For intermediate charges the strength of the repulsion depends on the specific system causing varying levels of aggregation or even none at all. Several samples consist of sufficiently repulsive systems leading to single dispersed nanoparticles, stable in the long term. Thanks to the magnetic properties of the chosen iron oxide nanoparticles, true ferrofluids are produced, appropriate for applications using magnetic fields. The strength and breadth of the observed trends suggests that the key parameters identified here can be generalised to most ionic liquids.

Spatial structure and composition of polysaccharide-protein complexes from small angle neutron scattering.

We use small angle neutron scattering (SANS), with an original analysis method, to obtain both the characteristic sizes and the inner composition of lysozyme-pectin complexes depending on the charge density. Lysozyme is a globular protein and pectin a natural anionic semiflexible polysaccharide with a degree of methylation (DM) 0, 43, and 74. For our experimental conditions (buffer ionic strength I = 2.5 10(-2) mol/L and pH between 3 and 7), the electrostatic charge of lysozyme is always positive (from 8 to 17, depending on pH). The pectin charge per elementary chain segment is negative and can be varied from almost zero to one through the change of DM and pH. The weight molar ratio of lysozyme on pectin monomers is kept constant. The ratio of negative charge content per volume to positive charge content per volume, -/+, is varied between 10 and 0.007. On a local scale, for all charged pectins, a correlation peak appears at 0.2 A(-1) due to proteins clustering inside the complexes. On a large scale, the complexes appear as formed of spherical globules with a well-defined radius of 10 to 50 nm, containing a few thousands proteins. The volume fraction Phi of organic matter within the globules derived from SANS absolute cross sections is around 0.1. The protein stacking, which occurs inside the globules, is enhanced when pectin is more charged, due to pH or DM. The linear charge density of the pectin determines the size of the globules for pectin chains of comparable molecular weights whether it is controlled by the pH or the DM. The radius of the globules varies between 10 and 50 nm. In conclusion, the structure is driven by electrostatic interactions and not by hydrophobic interactions. The molecular weight also has a large influence on the structure of the complexes because long chains tend to form larger globules. This may be one reason why DM and pH are not completely equivalent in our system, because DM0 has a short mass, but this may not be the only one. For very low pectin charge (-/+ = 0.07), globules do not appear and the scattering signals a gel-like structure. We did not observe any beads-on-a-string structure.

Neutron reflectivity study of the kinetics of polymer-polymer interface formation.

We have investigated how the interface width between two thin polymer films approaches its equilibrium state. Neutron reflection for different polyolefin bilayers of various degrees of incompatibility as a function of the annealing time was measured. By tuning the interaction parameter, we have probed both an immiscible polymer couple and systems approaching criticality where the interface is wider. Since polymer chains have slow dynamics, we have observed the slow broadening of the interface connected to the growth at long times of the wavelength capillary-wave modes, which involve large-scale hydrodynamic flows.

Universal scattering behavior of coassembled nanoparticle-polymer clusters.

Water-soluble clusters made from 7-nm inorganic nanoparticles have been investigated by small-angle neutron scattering. The internal structure factor of the clusters was derived and exhibited a universal behavior as evidenced by a correlation hole at intermediate wave vectors. Reverse Monte Carlo calculations were performed to adjust the data and provided an accurate description of the clusters in terms of interparticle distance and volume fraction. Additional parameters influencing the microstructure were also investigated, including the nature and thickness of the nanoparticle adlayer.