| 1. |
- Griffiths, P. C., et al.
(author)
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Small-angle neutron scattering, electron paramagnetic resonance, electrophoretic NMR, and time-resolved fluorescence quenching studies of sodium dodecyl sulfate and tetra(ethylene oxide) dodecyl ether mixed surfactant micelles
- 2004
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In: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 108:4, s. 1351-1356
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Journal article (peer-reviewed)abstract
- Small-angle neutron scattering (SANS), time-resolved fluorescence quenching (TRFQ), electrophoretic NMR (ENMR), and electron paramagnetic resonance (EPR) have been used to study mixed micelles formed from the two dodecyl tailed surfactants, sodium dodecyl sulfate (SDS) and tetra(ethylene oxide) dodecyl ether. By combining the TRFQ and EPR techniques, one is essentially able to calculate the SANS data, lending significant weight to the micelle characteristics thus obtained. EPR reports the degree of hydration of the surfactant headgroups; TRFQ, the micelle aggregation number and inter alia the volume of the hydrophobic core. Given the physical dimensions of the surfactant, i.e., alkyl chain length, headgroup volumes, etc., it is then possible to calculate the micelle ellipticity and shell thickness. The ENMR studies provide a rather different but complementary estimate of the ionic character of the micelle. With increasing nonionic content, the aggregation number increases, the micelle becomes more elliptical, and the headgroup region of the micelle becomes less hydrated and significantly more viscous. The degree of sodium counterion dissociation shows an initial small decrease with decreasing SDS micelle mole fraction but subsequently increases, reflecting the interplay between the electrostatic character of the micelle surface and the micelle curvature.
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| 2. |
- Heenan, Peter B., et al.
(author)
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Morphological and phylogenetic relationships of the threatened geophyte Wurmbea novae-zelandiae (Colchicaceae) from New Zealand, with notes on typification
- 2017
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In: Phytotaxa. - : MAGNOLIA PRESS. - 1179-3155 .- 1179-3163. ; 307:2, s. 123-132
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Journal article (peer-reviewed)abstract
- The new combination Wurmbea novae-zelandiae was recently made based on published phylogenetic studies, but little information was provided on its relationships based on morphology. This species was originally described as Anguillaria novae-zelandiae, for which a lectotype is designated. Morphological characters of W. novae-zelandiae are re-evaluated and shown to be characteristic of Wurmbea, thereby supporting the revised generic placement. However, W. novae-zelandiae differs from all other Wurmbea species in its diminutive stature, fewer tepals and stamens, and variable floral morphology, with 1-3 carpels, often leaf-like tepals, and aberrant tepal shape and number. DNA sequence data places W. novae-zelandiae as the sister species of W. uniflora, a species not included in earlier phylogenetic studies. These two species share mostly solitary flowers with white tepals, nectaries two per tepal and similar in form and position, small yellow anthers, and styles that are relatively short and recurve as flowering proceeds, with the inner style surface stigmatic for up to half of its length. A revised generic description of Wurmbea is provided to take account of the recently widened concept.
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| 3. |
- Hendriks, Kasper P., et al.
(author)
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Global Brassicaceae phylogeny based on filtering of 1,000-gene dataset
- 2023
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In: Current Biology. - : Elsevier. - 0960-9822 .- 1879-0445. ; 33:19, s. 4052-4068
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Journal article (peer-reviewed)abstract
- The mustard family (Brassicaceae) is a scientifically and economically important family, containing the model plant Arabidopsis thaliana and numerous crop species that feed billions worldwide. Despite its relevance, most phylogenetic trees of the family are incompletely sampled and often contain poorly supported branches. Here, we present the most complete Brassicaceae genus-level family phylogenies to date (Bras-sicaceae Tree of Life or BrassiToL) based on nuclear (1,081 genes, 319 of the 349 genera; 57 of the 58 tribes) and plastome (60 genes, 265 genera; all tribes) data. We found cytonuclear discordance between the two, which is likely a result of rampant hybridization among closely and more distantly related lineages. To eval-uate the impact of such hybridization on the nuclear phylogeny reconstruction, we performed five different gene sampling routines, which increasingly removed putatively paralog genes. Our cleaned subset of 297 genes revealed high support for the tribes, whereas support for the main lineages (supertribes) was moder-ate. Calibration based on the 20 most clock-like nuclear genes suggests a late Eocene to late Oligocene origin of the family. Finally, our results strongly support a recently published new family classification, dividing the family into two subfamilies (one with five supertribes), together representing 58 tribes. This includes five recently described or re-established tribes, including Arabidopsideae, a monogeneric tribe accommodating Arabidopsis without any close relatives. With a worldwide community of thousands of researchers working on Brassicaceae and its diverse members, our new genus-level family phylogeny will be an indispensable tool for studies on biodiversity and plant biology.
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| 4. |
- Paul, A., et al.
(author)
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Nuclear magnetic resonance and small-angle neutron scattering studies of anionic surfactants with macrocounterions : Tetramethylammonium dodecyl sulfate
- 2005
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In: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 109:33, s. 15775-15779
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Journal article (peer-reviewed)abstract
- Micellar solutions of tetramethylammonium dodecyl sulfate have been studied to determine the degree of counterion binding. Tetramethylammonium chloride was added over a wide range of surfactant concentrations such that the total concentration of tetramethylammonium ions in solution remained constant. Small angle neutron scattering experiments showed a constancy in aggregation number across this series, consistent with the constant C-aq concept of Bales et al. (J. Phys. Chent. B 2001, 105, 6798). Pulsed-field gradient and electrophoretic NMR experiments were used to determine the degree of counterion dissociation, alpha, which was found to be 0.33. This value is in contrast to the value from conductivity measurements (alpha = 0.2), but supports the concept of an aggregation number based definition of alpha.
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| 5. |
- Rennie, Adrian R., et al.
(author)
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Learning about SANS instruments and data reduction from round robin measurements on samples of polystyrene latex
- 2013
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In: Journal of applied crystallography. - 0021-8898 .- 1600-5767. ; 46:5, s. 1289-1297
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Journal article (peer-reviewed)abstract
- Measurements of a well-characterized `standard' sample can verify the performance of an instrument. Typically, small-angle neutron scattering instruments are used to investigate a wide range of samples and may often be used in a number of configurations. Appropriate `standard' samples are useful to test different aspects of the performance of hardware as well as that of the data reduction and analysis software. Measurements on a number of instruments with different intrinsic characteristics and designs in a round robin can not only better characterize the performance for a wider range of conditions but also, perhaps more importantly, reveal the limits of the current state of the art of small-angle scattering. The exercise, followed by detailed analysis, tests the limits of current understanding as well as uncovering often forgotten assumptions, simplifications and approximations that underpin the current practice of the technique. This paper describes measurements of polystyrene latex, radius 720 Å, with a number of instruments. Scattering from monodisperse, uniform spherical particles is simple to calculate and displays sharp minima. Such data test the calibrations of intensity, wavelength and resolution as well as the detector response. Smoothing due to resolution, multiple scattering and polydispersity has been determined. Sources of uncertainty are often related to systematic deviations and calibrations rather than random counting errors. The study has prompted development of software to treat modest multiple scattering and to better model the instrument resolution. These measurements also allow checks of data reduction algorithms and have identified how they can be improved. The reproducibility and the reliability of instruments and the accuracy of parameters derived from the data are described.
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| 6. |
- Shoamanesh, Ashkan, et al.
(author)
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Factor XIa inhibition with asundexian after acute non-cardioembolic ischaemic stroke (PACIFIC-Stroke) : an international, randomised, double-blind, placebo-controlled, phase 2b trial
- 2022
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In: The Lancet. - 0140-6736. ; 400:10357, s. 997-1007
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Journal article (peer-reviewed)abstract
- Background: Asundexian (Bayer AG, Leverkusen, Germany), an oral small molecule factor XIa (FXIa) inhibitor, might prevent thrombosis without increasing bleeding. Asundexian's effect for secondary prevention of recurrent stroke is unknown. Methods: In this randomised, double-blind, placebo-controlled, phase 2b dose-finding trial (PACIFIC-Stroke), patients with acute (within 48 h) non-cardioembolic ischaemic stroke were recruited from 196 hospitals in 23 countries. Patients were eligible if they were aged 45 years or older, to be treated with antiplatelet therapy, and able to have a baseline MRI (either before or within 72 h of randomisation). Eligible participants were randomly assigned (1:1:1:1), using an interactive web-based response system and stratified according to anticipated antiplatelet therapy (single vs dual), to once daily oral asundexian (BAY 2433334) 10 mg, 20 mg, or 50 mg, or placebo in addition to usual antiplatelet therapy, and were followed up during treatment for 26–52 weeks. Brain MRIs were obtained at study entry and at 26 weeks or as soon as possible after treatment discontinuation. The primary efficacy outcome was the dose–response effect on the composite of incident MRI-detected covert brain infarcts and recurrent symptomatic ischaemic stroke at or before 26 weeks after randomisation. The primary safety outcome was major or clinically relevant non-major bleeding as defined by International Society on Thrombosis and Haemostasis criteria. The efficacy outcome was assessed in all participants assigned to treatment, and the safety outcome was assessed in all participants who received at least one dose of study treatment. This study is registered with ClinicalTrials.gov, NCT04304508, and is now complete. Findings: Between June 15, 2020, and July 22, 2021, 1880 patients were screened and 1808 participants were randomly assigned to asundexian 10 mg (n=455), 20 mg (n=450), or 50 mg (n=447), or placebo (n=456). Mean age was 67 years (SD 10) and 615 (34%) participants were women, 1193 (66%) were men, 1505 (83%) were White, and 268 (15%) were Asian. The mean time from index stroke to randomisation was 36 h (SD 10) and median baseline National Institutes of Health Stroke Scale score was 2·0 (IQR 1·0–4·0). 783 (43%) participants received dual antiplatelet treatment for a mean duration of 70·1 days (SD 113·4) after randomisation. At 26 weeks, the primary efficacy outcome was observed in 87 (19%) of 456 participants in the placebo group versus 86 (19%) of 455 in the asundexian 10 mg group (crude incidence ratio 0·99 [90% CI 0·79–1·24]), 99 (22%) of 450 in the asundexian 20 mg group (1·15 [0·93–1·43]), and 90 (20%) of 447 in the asundexian 50 mg group (1·06 [0·85–1·32]; t statistic –0·68; p=0·80). The primary safety outcome was observed in 11 (2%) of 452 participants in the placebo group versus 19 (4%) of 445 in the asundexian 10 mg group, 14 (3%) of 446 in the asundexian 20 mg group, and 19 (4%) of 443 in the asundexian 50 mg group (all asundexian doses pooled vs placebo hazard ratio 1·57 [90% CI 0·91–2·71]). Interpretation: In this phase 2b trial, FXIa inhibition with asundexian did not reduce the composite of covert brain infarction or ischaemic stroke and did not increase the composite of major or clinically relevant non-major bleeding compared with placebo in patients with acute, non-cardioembolic ischaemic stroke. Funding: Bayer AG.
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