| 1. |
|
|
| 2. |
- Quinson, Jonathan, et al.
(författare)
-
Surfactant-Free Colloidal Syntheses of Gold-Based Nanomaterials in Alkaline Water and Mono-alcohol Mixtures
- 2023
-
Ingår i: Chemistry of Materials. - : American Chemical Society (ACS). - 0897-4756 .- 1520-5002. ; 35:5, s. 2173-2190
-
Tidskriftsartikel (refereegranskat)abstract
- Gold nanoparticles (Au NPs) and gold-based nanomaterials combine unique properties relevant for medicine, imaging, optics, sensing, catalysis, and energy conversion. While the Turkevich-Frens and Brust-Schiffrin methods remain the state-of-the-art colloidal syntheses of Au NPs, there is a need for more sustainable and tractable synthetic strategies leading to new model systems. In particular, stabilizers are almost systematically used in colloidal syntheses, but they can be detrimental for fundamental and applied studies. Here, a surfactant-free synthesis of size-controlled colloidal Au NPs stable for months is achieved by the simple reduction of HAuCl4 at room temperature in alkaline solutions of low-viscosity mono-alcohols such as ethanol or methanol and water, without the need for any other additives. Palladium (Pd) and bimetallic AuxPdy NPs, nanocomposites and multimetallic samples, are also obtained and are readily active (electro)catalysts. The multiple benefits over the state-of-the-art syntheses that this simple synthesis bears for fundamental and applied research are highlighted.
|
|
| 3. |
- Rasmussen, Mads, et al.
(författare)
-
Blood Pressure Thresholds and Neurologic Outcomes After Endovascular Therapy for Acute Ischemic Stroke: An Analysis of Individual Patient Data From 3 Randomized Clinical Trials.
- 2020
-
Ingår i: JAMA neurology. - : American Medical Association (AMA). - 2168-6157 .- 2168-6149. ; 77:5, s. 622-31
-
Tidskriftsartikel (refereegranskat)abstract
- The optimal blood pressure targets during endovascular therapy (EVT) for acute ischemic stroke (AIS) are unknown.To study whether procedural blood pressure parameters, including specific blood pressure thresholds, are associated with neurologic outcomes after EVT.This retrospective cohort study included adults with anterior-circulation AIS who were enrolled in randomized clinical trials assessing anesthetic strategy for EVT between February 2014 and February 2017. The trials had comparable blood pressure protocols, and patients were followed up for 90 days. A total of 3630 patients were initially approached, and 3265 patients were excluded.Endovascular therapy.The primary efficacy variable was functional outcome as defined by the modified Rankin Scale (mRS) score at 90 days. Associations of blood pressure parameters and time less than and greater than mean arterial blood pressure (MABP) thresholds with outcome were analyzed.Of the 365 patients included in the analysis, the mean (SD) age was 71.4 (13.0) years, 163 were women (44.6%), and the median National Institutes of Health Stroke Scale score was 17 (interquartile range [IQR], 14-21). For the entire cohort, 182 (49.9%) received general anesthesia and 183 (50.1%) received procedural sedation. A cumulated period of minimum 10 minutes with less than 70 mm Hg MABP (adjusted OR, 1.51; 95% CI, 1.02-2.22) and a continuous episode of minimum 20 minutes with less than 70 mm Hg MABP (adjusted OR, 2.30; 95% CI, 1.11-4.75) were associated with a shift toward higher 90-day mRS scores, corresponding to a number needed to harm of 10 and 4, respectively. A cumulated period of minimum 45 minutes with greater than 90 mm Hg MABP (adjusted OR, 1.49; 95% CI, 1.11-2.02) and a continuous episode of minimum 115 minutes with greater than 90 mm Hg MABP (adjusted OR, 1.89; 95% CI, 1.01-3.54) were associated with a shift toward higher 90-day mRS scores, corresponding to a number needed to harm of 10 and 6, respectively.Critical MABP thresholds and durations for poor outcome were found to be MABP less than 70 mm Hg for more than 10 minutes and MABP greater than 90 mm Hg for more than 45 minutes, both durations with a number needed to harm of 10 patients. Mean arterial blood pressure may be a modifiable therapeutic target to prevent or reduce poor functional outcome after EVT.
|
|
| 4. |
- Simonsen, S. B., et al.
(författare)
-
Coarsening of Pd nanoparticles in an oxidizing atmoshere studied by in situ TEM
- 2016
-
Ingår i: Surface Science. - : Elsevier BV. - 0039-6028. ; 648, s. 278-283
-
Tidskriftsartikel (refereegranskat)abstract
- The coarsening of supported palladiumnanoparticles in an oxidizing atmospherewas studied in situ by means of transmission electron microscopy (TEM). Specifically, the Pd nanoparticles were dispersed on a planar and amorphousAl2O3 support and were observed during the exposure to 10 mbar technical air at 650 °C. Time-resolved TEM image series reveal that the Pd nanoparticles were immobile and that a few percent of the nanoparticles grew or shrank, indicating a coarsening process mediated by the Ostwald ripening mechanism. The TEM image contrast suggests that the largest nanoparticles tended to wet the Al2O3 support to a higher degree than the smaller nanoparticles and that the distribution of projected particle sizes consequently broadens by the appearance of an asymmetric tail toward the larger particle sizes. A comparison with computer simulations based on a simple mean-fieldmodel for the Ostwald ripening process indicates that the observed change in the particle size distribution can be accounted for by wetting of the Al2O3 support by the larger Pd nanoparticles.
|
|
| 5. |
- Simonsen, S. B., et al.
(författare)
-
Effect of particle morphology on the ripening of supported Pt nanoparticles
- 2012
-
Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 116:9, s. 5646-5653
-
Tidskriftsartikel (refereegranskat)abstract
- To improve the understanding of sintering in diesel and lean-burn engine exhaust aftertreatment catalysts, we examined oxygen-induced sintering in a model catalyst consisting of Pt nanoparticles supported on a planar, amorphous Al2O3 substrate. After ageing at increasingtemperatures, transmission electron microscopy analysis reveals that highly monodisperse ensembles of nanoparticles transformed into ensembles with bimodal and subsequently Lifshitz-Slyozov-Wagner particle size distributions. Moreover, scanning transmission electron microscopy and atomic force microscopy analysis suggest that the Pt nanoparticles have size-dependent morphologies after sintering in oxidizing environment. The evolution of the particle sizes is described by a simple kinetic model for ripening and the size-dependent particle morphology is proposed as an explanation for the observed bimodal particle size distribution shapes.
|
|
| 6. |
|
|
