Search results for "ALLOYS"
showing 10 items of 1689 documents
Growth of large liquid crystalline domains of phospholipids at air-water interfaces
1990
Abstract The fusion of condensed phase domains in a fluid environment in monolayers is studied. A system of electrodes permits the non-invasive and predetermined movement of single domains while the film is observed by fluorescence microscopy. Two domains fuse when they are brought into contact with special positions of their borderlines. The experiment yields information about the molecular structure of the domains and allows us to fabricate very large domains. The equilibrium size is estimated and verified.
Magnetic coiffure: Engineering of human hair surfaces with polyelectrolyte-stabilised magnetite nanoparticles
2022
Here we report a spontaneous electrostatic coating of human hair with aqueous Fe3O4 colloids capable to tailor magnetic properties to hair, orienting and even moving them under the influence of the external magnetic field. Magnetite particles were modified by cationic and anionic polyelectrolytes and then successfully deposited in dense arrays, starting from cuticle gaps and spreading further over a major hair surface. These biocompatible and biodegradable magnetic nanoparticles may serve as carriers for drug loading and delivery for topical pharmaceutical treatments. The deposition process was imaged in real-time using dark-field microscopy. The hair specimens were further studied using a …
Photostability assessment of natural pyrethrins using halloysite nanotube carrier system
2022
Natural pyrethrins are one of the most used pesticides and insect repellents employed for domestic or agronomic use. However, they are highly hydrophobic and suffer from insolubility in water media and ready decomposition by photochemical, and oxidative actions. These aspects hamper their long-term storage and applicability. Herein, we report the synthesis and characterization of a nanomaterial based on the loading of pyrethrum extract (PE) into natural, low-cost, and eco-compatible halloysite nanotubes (Hal). The Hal/PE nanomaterial was thoroughly characterized, and the morphology was imaged by TEM and SEM investigations. Release experiments showed a slow release of pyrethrins from the car…
Sweet (hetero)aromatics: glycosylated templates for the construction of saccharide mimetics
2011
Mono- and diglycosylated aromatics and heteroaromatics may serve as building blocks for the construction of metabolically stable mimetics of oligosaccharides. Methods for their preparation from monosaccharidic precursors by direct C-glycosylation, dipolar cycloaddition or Larock cyclization are described.
A topological isomer of the Au25(SR)18−nanocluster
2020
Energetically low-lying structural isomers of the much-studied thiolate-protected gold cluster Au25(SR)18− are discovered from extensive (80 ns) molecular dynamics (MD) simulations using the reactive molecular force field ReaxFF and confirmed by density functional theory (DFT). A particularly interesting isomer is found, which is topologically connected to the known crystal structure by a low-barrier collective rotation of the icosahedral Au13 core. The isomerization takes place without breaking of any Au–S bonds. The predicted isomer is essentially iso-energetic with the known Au25(SR)18− structure, but has a distinctly different optical spectrum. It has a significantly larger collision cr…
Comparison of analytical methods and AI tools for material characterisation in hot forming
2002
Abstract Hot forming processes probably represent the most ancient of forming operations and what is more they are still today commonly used in modern mechanical industry in order to obtain sound parts, achieving large deformations with a limited required power. Hot metal forming operations are characterised by a large number of physical and thermal phenomena which have to be taken into account in order to model and design the processes themselves. Actually several thermally activated phenomena occur during the forming processes such as recovery, recrystallisation, grain growth, precipitation, allotropic transformations, etc. In this paper the comparison between an analytical method based o…
Closer to nature: an ATP-driven bioinspired catalytic oxidation process
2013
The capability of DNA to acquire enzyme-like properties has led to the emergence of the so-called DNAzyme field; herein, we take a further leap along this nature-inspired road, demonstrating that a template assembled synthetic G-quartet (TASQ) can act as a pre-catalyst for catalytic peroxidase-mimicking oxidation reactions, whatever its nature (guanine or guanosine-based G-quartets), in an ATP-dependent manner, thereby bringing this bioinspired TASQzyme process even closer to nature.
An oxidatively damaged G-quadruplex/hemin DNAzyme.
2020
International audience; Oxidative damage of guanine to 8-oxoguanine triggers a partial and variable loss of G-quadruplex/hemin DNAzyme activity and provides clues to the mechanistic origins of DNAzyme deactivation, which originates from an interplay between decreased G-quadruplex stability, lower hemin affinity and a modification of the nature of hemin binding sites.
Direct chemical grafted curcumin on halloysite nanotubes as dual-responsive prodrug for pharmacological applications
2016
Covalently functionalized halloysite nanotubes (HNTs) were successfully employed as dual-responsive nanocarriers for curcumin (Cur). Particularly, we synthesized HNT-Cur prodrug with a controlled curcumin release on dependence of both intracellular glutathione (GSH) and pH conditions. In order to obtain HNT-Cur produgs, halloysite was firstly functionalized with cysteamine through disulphide linkage. Afterwards, curcumin molecules were chemically conjugated to the amino end groups of halloysite via Schiff's base formation. The successful functionalization of halloysite was proved by thermogravimetric analysis, FT-IR spectroscopy, dynamic light scattering and scanning electron microscopy. Ex…
1,2,3-Oligotriazoles modified halloysite nanotubes as potential active biological species: synthesis and characterization
2022
In the last years, the development of nano-formulations for cancer treatment represents one of the major challenges of the scientific research. The prodrug strategy, that combines chemotherapeutic agents with nanocarriers such as halloysite nanotubes (HNTs), is a promising strategy both to improve the biological activity of the drug molecules and to reduce the side effects of drugs. Herein we report the synthesis and characterization of a HNTs prodrug based on 1,2,3-triazole units covalently linked to HNTs external surface, bearing different positively charged moieties, which could present interesting pharmacological activities.