Publications by authors named "Bras W"
Mo-ZSM-5 is a well-studied catalyst for its ability to convert methane to aromatics and hydrogen. Since the process is thermodynamically 'uphill', high temperatures are necessary to achieve acceptable product yields. However, these temperatures have been shown to negatively impact the stability of the zeolite, with the formation of aluminum molybdates being proposed as particularly responsible for framework collapse.
View Article and Find Full Text PDFResearch on new conservation treatments for historical wood requires considerable amounts of appropriate wood material, which is hard to acquire. Thus, we produced biologically and chemically degraded model wood that could be used as a representative material in future research on consolidating agents. Using chemical composition determinations, we found that fungal decay targeted mainly polysaccharides, while alkaline treatment mostly reduced hemicelluloses and lignin content.
View Article and Find Full Text PDFSynthesis and Characterization of Stimuli-Responsive Polymer Brushes in Nanofluidic Channels.
ACS Appl Mater Interfaces
November 2023
Article Synopsis
- Nanochannels that can control their opening and closing are useful in applications like detecting viruses, sorting particles, and regulating fluid flow.
- The study investigates how changing the pH and ionic strength of solutions affects the behavior of a special brush coating inside these nanochannels.
- Results show that at high pH, the brush is collapsed (like an open gate), while lower pH and salt levels cause the brush to expand and partially close the gate, offering new ways to design advanced nanofluidic devices.
The barrier function of the skin is primarily located in the stratum corneum (SC), the outermost layer of the skin. The SC is composed of dead cells with highly organized lipid lamellae in the intercellular space. As the lipid matrix forms the only continuous pathway, the lipids play an important role in the permeation of compounds through the SC.
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- - The study explores the solubilization of melittin, an antimicrobial peptide, in bicontinuous microemulsions (BMEs) made with biocompatible oils, demonstrating its capacity to stay active and effective against bacteria in chronic wounds and surgical infections.
- - The researchers analyzed different BME systems, finding that melittin maintained an active α-helix configuration in an apolar environment, particularly in the Winsor-III system, which enhanced its interaction with surfactants and improved its antimicrobial properties.
- - The results revealed that while melittin-free BMEs already inhibited bacteria due to their oil content, adding melittin significantly increased antimicrobial activity, suggesting that BMEs could serve as effective delivery platforms
Article Synopsis
- * This stretching process involves heating the SPE films above the melting point of PEO in an inert atmosphere and allowing crystallization while the material is still under strain.
- * Experimental techniques like wide-angle and small-angle X-ray scattering reveal that this alignment creates a more efficient pathway for ion movement, resulting in a significant increase in ionic conductivity (1.4 to 3.5 times better).
Article Synopsis
- * This study focuses on compatibilization, testing three commercial ethylene copolymer compatibilizers (EAA, PTW, and Surlyn) on a blend of PET and HDPE, common packaging materials.
- * Researchers assess how the location of these compatibilizers within the polymer blend impacts compatibility, which helps in understanding their effectiveness and improving strategies for upcycling waste plastics.
Article Synopsis
- The physical changes in polymers due to external factors are influenced by their molecular length and energy balance, necessitating advanced studies to understand these transformations.
- Researchers suggest using a multi-technique approach combining X-ray scattering, Raman spectroscopy, and Differential Scanning Calorimetry to study the structural changes in polymers at various scales.
- To maximize the analysis of data from these techniques, they recommend using multivariate analysis and data mining strategies, which were successfully applied in crystallization studies of a PVDF blend with a fluoroelastomer.
Article Synopsis
- * A new type of hydrogel, made from low-crosslink-density polyacrylamide and hyperbranched silica nanoparticles, has been created that demonstrates hysteresis-free properties and remarkable fatigue resistance even after thousands of strain cycles.
- * This resilient hydrogel exhibits a high strain-ratio-at-break of 11.5 and effectively detects dynamic deformations under cyclic loading across various frequencies, making it superior to other materials in this aspect.
Article Synopsis
- Small angle x-ray scattering and x-ray absorption fine structure are key techniques that have utilized synchrotron sources since their beginning.
- The article highlights the evolution of these techniques and the advancements in sample environments that enhance experimental outcomes.
- It focuses on the achievements, current trends, and future prospects of these x-ray methods in the UK from 1980 to 2020.
Article Synopsis
- The advancements in synchrotron radiation have enabled innovative experiments that were previously unattainable, but intense radiation can damage samples.
- While radiation damage is noticeable in static experiments through changes in diffraction or spectroscopy curves, it can be misleading in dynamic experiments, leading to misinterpretation of results as genuine findings.
- The paper discusses how radiation affects time-resolved processes in various materials, emphasizing that these effects occur across a wide spectrum of materials research and are not confined to high-brilliance beamlines.
Ultra-SAXS can enhance the capabilities of existing synchrotron SAXS/WAXS beamlines. A compact ultra-SAXS module has been developed, which extends the measurable q-range with 0.0015 ≤ q (nm) ≤ 0.
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- The basic structure of bone is formed by mineralized collagen fibrils, which are thought to have a specific arrangement of hydroxyapatite (HAp) platelets embedded within collagen.
- Recent research challenges the traditional view of how HAp and collagen interact, revealing that the voids in collagen are actually cylindrical pores measuring about 2 nm in diameter.
- Through various studies, it was found that the confined environment of these pores influences how HAp crystals grow and align relative to collagen, suggesting a more complex relationship than previously understood.
Article Synopsis
- *The study uses Small Angle X-ray Scattering (SAXS) and molecular modeling to analyze the packing structure of fibrin fibers.
- *Results reveal a specific arrangement of fibrin molecules at both axial and lateral levels, enhancing our understanding of the structural basis behind blood clot properties.
Background: Neonatal Staphylococcus aureus (S. aureus) bacteremia is an important cause of morbidity and mortality. In this study, we examined whether methicillin-susceptible S.
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- * The decomposition of [Zn(SCNBu)] in oleylamine produces wurtzite nanowires, and adding thiuram disulfide increases their length.
- * X-ray absorption spectroscopy reveals the structural changes of [Zn(SCNMe)] under different conditions, showing that temperature influences its stability and leads to ZnS formation through a defined mechanistic process.
Article Synopsis
- * Iron dithiocarbamate complexes are used as single source precursors to produce these nanoparticles, with a novel Fe(II) precursor enabling simpler synthesis by losing carbonyls efficiently.
- * Research findings indicate that careful control of reaction conditions can yield pure greigite nanoparticles, while X-ray absorption spectroscopy helps clarify the decomposition pathway of the precursors in oleylamine, highlighting the role of reducing iron(III) to iron(II).
Article Synopsis
- Greigite (FeS) and other iron sulfides may serve as low-cost, earth-abundant electrocatalysts for the hydrogen evolution reaction (HER), but their surface chemistry is not well understood.* -
- When a greigite-modified electrode was studied under HER conditions, it was found that iron-sulfur bonds were replaced by iron-oxygen units, resulting in a mixture of 60% greigite and 40% iron hydroxide (goethite) with a core-shell structure.* -
- A significant increase in pH at the electrode surface (up to pH 12) was observed due to hydroxide generation; however, CO saturation inhibited this process, highlighting the need
Article Synopsis
- A new plug-and-play system using polycapillary X-ray optics allows for advanced 3D confocal X-ray fluorescence (XRF) and absorption spectroscopy with tiny spatial resolution at the European Synchrotron Radiation Facility.
- The setup has been tested through two experiments: mapping elements in an olivine-rich inclusion in a diamond and analyzing Iron Gall ink in a historical letter from King Philip II of Spain.
- The findings from the experiments highlight the detailed elemental imaging capacity of the system and provide insights into the structure of Iron Gall ink, indicating its fragile nature and absence of specific chemical bonding.
Article Synopsis
- - Hydrogen plays a significant role in the transition to clean energy and is being explored for applications like hydrogen storage, catalysis, and rechargeable batteries, all of which are influenced by the thermodynamics of metal-hydrogen systems.
- - The study highlights how incorporating small amounts of zirconium into yttrium can create elastic strain in the yttrium lattice, which stabilizes during hydrogen absorption and release cycles.
- - This modification allows for a dramatic tuning of hydrogen pressure in yttrium hydride (YH) operations, enabling the development of a hydrogen sensor that visually indicates changes in ambient hydrogen pressure across a wide range.
When subjected to flow, the structures of many soft-matter systems become anisotropic due to the symmetry breaking of the spatial arrangements of constituent particles at the microscopic level. At present, it is common practice to use various small-angle scattering techniques to explore flow-induced microstructural distortion. However, there has not been a thorough discussion in the literature on how a three-dimensional anisotropic structure can be faithfully reconstructed from two-dimensional small-angle scattering spectra.
View Article and Find Full Text PDFObjectives: To investigate an unusual outbreak of five patients with a total of eight episodes of a Clostridium difficile infection on a gastrointestinal surgical ward of a Dutch tertiary-care, university-affiliated hospital.
Methods: Clinical case investigations and laboratory analyses were performed. Laboratory analyses included PCR ribotyping, multiple-locus variable-number tandem repeat analysis typing, toxin typing, antimicrobial susceptibility testing and whole genome sequencing.
Article Synopsis
- * A novel setup allows for in situ small angle X-ray scattering during microwave annealing, enabling direct observation of its effects on a specific triblock copolymer system.
- * The study finds that the block copolymer alone doesn't absorb microwaves effectively, but adding a small microwave-interactive molecule can lead to significant morphological changes, paving the way for advanced "smart" manufacturing techniques.