Search results for "Microscopy"
showing 10 items of 3390 documents
Novel silver-based nanoclay as an antimicrobial in polylactic acid food packaging coatings.
2010
This paper presents a comprehensive performance study of polylactic acid (PLA) biocomposites, obtained by solvent casting, containing a novel silver-based antimicrobial layered silicate additive for use in active food packaging applications. The silver-based nanoclay showed strong antimicrobial activity against Gram-negative Salmonella spp. Despite the fact that no exfoliation of the silver-based nanoclay in PLA was observed, as suggested by transmission electron microscopy (TEM) and wide angle X-ray scattering (WAXS) experiments, the additive dispersed nicely throughout the PLA matrix to a nanoscale, yielding nanobiocomposites. The films were highly transparent with enhanced water barrier …
Enzymatic Synthesis and Surface Deposition of Tin Dioxide using Silicatein-α
2011
Nanostructured tin dioxide was synthesized by making use of the catalytic activity of silicatein-α. TEM, HRTEM, and XRD revealed the formation of cassiterite SnO2. Surface bound silicatein retains its biocatalytic activity. This was demonstrated by immobilizing silicatein on glass surfaces using a histidine-tag chelating anchor. The subsequent deposition of SnO2 on glass was monitored by quartz crystal microbalance (QCM) measurements and scanning electron microscopy (SEM). This new aspect of silicatein activity toward the formation of metal oxides other than SiO2, TiO2, and BaTiO3 opens up new vistas in composite material synthesis.
Diacetylene Linked Anthracene Oligomers Synthesized by One-Shot Homocoupling of Trimethylsilyl on Cu(111)
2018
On-surface chemical reaction has become a very powerful technique to conjugate small precursor molecules and several reactions have been proposed with the aim to fabricate functional nanostructures on surfaces. Here we present an unforeseen adsorption mode of 9,10-bis-((trimethylsilyl)ethynyl)anthracene on a Cu(111)surface and the resulting one-shot desilylative homocoupling of of the adsorbate by annealing at 400 K. With a combination of high-resolution atomic force microscopy and density functional theory calculations, we found that the triple bonds and silicon atoms of the monomer chemically interact with the copper surface. After the oligomerization, we discovered that the anthracene un…
Oscillator strengths of sulphur 3s23p34s3So-3s23p34p3P transitions measured by time resolved two-photon laser spectroscopy
1997
Oscillator strengths for the three 3s23p34s 3S1o-3s23p34p 3P0,1,2 transitions in neutral sulphur have been determined directly from lifetime measurements. Two-photon UV laser excitation and subsequent fluorescence detection have been used on atoms produced in a thermal sulphur beam or in a laser-driven plasma. A good agreement was found between data obtained in both schemes. The lifetime data obtained, τ(3P0) = 46.1(1.0) ns, τ(3P1) = 46.1(1.0) ns and τ(3P2) = 46.1(1.0) ns are compared with results of theoretical and experimental data from literature. The absorption oscillator strengths derived are f(3S1o-3P0) = 0.120(0.003), f(3S1o-3P1) = 0.360(0.008) and f(3S1o-3P2) = 0.600(0.013), respect…
Characterization and photoactivity of coupled ZnO-ZnWO4 catalysts prepared by a sol-gel method
2014
Abstract ZnO–ZnWO4 nanocomposites were synthesized by a novel sol–gel method and characterized through X-ray diffraction, BET specific surface area analysis, UV–Vis diffuse reflectance spectroscopy, scanning electron microscopy and transmission electron microscopy. The photocatalytic activity of the samples was evaluated using the degradation of 4-nitrophenol under UV light as probe reaction. The ZnO/ZnWO4 molar ratio was varied in order to study its influence on the photoefficiency of the mixed samples. The ZnO–ZnWO4 nanocomposites showed higher photoactivity than ZnO and ZnWO4. The high efficiency of the mixed samples was explained by the coupling and the intimate contact of two different…
A non-destructive X-ray microtomography approach for measuring fibre length in short-fibre composites
2012
An improved method based on X-ray microtomography is developed for estimating fibre length distribution of short-fibre composite materials. In particular, a new method is proposed for correcting th ...
Influence of the chemical dissolution of MnS inclusions on the composition of passive films and the local electrochemical behaviour of stainless stee…
2006
Abstract Immersion of stainless steel containing MnS inclusions in aqueous electrolytes leads to the chemical dissolution of these heterogeneities. Chemical dissolution of MnS inclusions in 1M NaCl, pH=3 was studied using in-situ AFM and the dissolution rate of MnS was estimated between 0.04 and 0.19 μm 3 /min. The local electrochemical measurements reveal that the chemical dissolution of MnS inclusions promotes pitting corrosion. Similary, chemical dissolution of MnS inclusions in IM NaClO 4 , pH=3 solution modified the surface close to the inclusions by the presence of FeSO 4 in the passive film.
One step continuous hydrothermal synthesis of very fine stabilized superparamagnetic nanoparticles of magnetite
2011
International audience; Stable suspensions of citrated SPIO nanoparticles were synthesised in one step using a hydrothermal continuous process. Citrates control the crystallite size and the oxidation degree of metallic ions despite the very short reaction time (4 s). Magnetite particles, Fe2.94O4, with an average size of 4 nm and good monodispersity were obtained.
Nanovectorization of TRAIL with single wall carbon nanotubes enhances tumor cell killing
2015
International audience; Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL or Apo2L) is a member of the tumor necrosis factor (TNF) superfamily. This type II transmembrane protein is able to bound specifically to cancer cell receptors (i.e., TRAIL-R1 (or DR4) and TRAIL-R2 (or DR5)) and to induce apoptosis without being toxic for healthy cells. Because membrane-bound TRAIL induces stronger receptor aggregation and apoptosis than soluble TRAIL, we proposed here to vectorize TRAIL using single-walled carbon nanotubes (SWCNTs) to mimic membrane TRAIL. Owing to their exceptional and revolutional properties, carbon nanotubes, especially SWCNTs, are used in a wide range of physical or,…
Transverse chemical interface detection with coherent anti-Stokes Raman scattering microscopy
2011
International audience; Transverse "chemical" interfaces are revealed with a conventional two beam narrowband coherent anti-Stokes Raman scattering microscopy setup in a collinear configuration. The exciting "pump" and "Stokes" beams are focused on the sample in two opposite directions. The subtraction of the two generated anti-Stokes signals gives rise to a signal that is directly proportional to the pure Raman spectrum of the resonant medium. This property is used to highlight an interface between glass and N,N-dimethylformamide (DMF) and recover the pure Raman spectrum of DMF around its 1408 cm−1 vibrational band.