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A one-dimensional (1D) mechanical model for nanogranular films, based on a structural interface, is presented. The analytical dispersion relation for the frequency and lifetimes of the acoustics breathing modes is obtained in terms of the interface layer thickness and porosity. The model is successfully benchmarked both against three-dimensional finite element method simulations and experimental photoacoustic data on a paradigmatic system available from the literature. A simpler 1D model, based on an homogenized interface, is also presented and its limitations and pitfalls discussed at the light of the more sophisticated pillar model. The pillar model captures the relevant physics responsible for acoustic dissipation at a disordered interface. Furthermore, the present findings furnish to the experimentalist an easy-to-adopt, benchmarked analytical tool to extract the interface layer physical parameters upon fitting of the acoustic data. The model is scale invariant and may be deployed, other than the case of granular materials, where a patched interface is involved.

Plasmonic metal NPs such as Au and Ag are proven to channel visible-light photon energy to nearby metal complexes effectively and allow the conventional metal cationic catalysts to work at moderate temperatures under light irradiation. A key finding is that reactant molecules can be significantly concentrated at the active sites simply by light and thus increase the chance of activation. The merging of plasmonic antenna and metal cationic catalysis will be an inspiring strategy for designing efficient photocatalytic systems.

Accessing fluid infiltration in nanogranular coatings is an outstanding challenge, of relevance for applications ranging from nanomedicine to catalysis. A sensing platform, allowing quantifying the amount of fluid infiltrated in a nanogranular ultrathin coating, with thickness in the 10-40 nm range, is here proposed and theoretically investigated by multiscale modeling. The scheme relies on impulsive photoacoustic excitation of hypersonic mechanical breathing modes in engineered gas-phase-synthesized nanogranular metallic ultrathin films and time-resolved acousto-optical read-out of the breathing modes frequency shift upon liquid infiltration. A superior sensitivity, exceeding 26 × 103 cm2/g, is predicted upon equivalent areal mass loading of a few ng/mm2. The capability of the present scheme to discriminate among different infiltration patterns is discussed. The platform is an ideal tool to investigate nanofluidics in granular materials and naturally serves as a distributed nanogetter coating, integrating fluid sensing capabilities. The proposed scheme is readily extendable to other nanoscale and mesoscale porous materials.

We have studied light induced processes in nanocolloids and composite materials containing ordered and disordered aggregates of plasmonic nanoparticles accompanied by their strong heating. A universal comprehensive physical model that combines mechanical, electrodynamical, and thermal interactions at nanoscale has been developed as a tool for investigations. This model was used to gain deep insight on phenomena that take place in nanoparticle aggregates under high-intensity pulsed laser radiation resulting in the suppression of nanoparticle resonant properties. Verification of the model was carried out with single colloidal Au and Ag nanoparticles and their aggregates., Funding text: This work was performed within the State contract of the RF Ministry of Education and Science for Siberian Federal University for scientific research in 2017-2019 and SB RAS Program No II.2P (0358-2015-0010). The calculations were performed using the MVS-1000 M cluster at the Institute of Computational Modeling, Federal Research Center KSC SB RAS.QC 20170530

Hybrid organic/inorganic thin film nanocomposites based on poly(styrene)-b-poly(butadiene)-b-poly(methyl methacrylate) (SBM) triblock copolymer and silver nanoparticles (Ag) have been prepared and characterized. In order to improve the compatibility of nanoparticles with the polymeric matrix, their surface has been modified with dodecanethiol surfactant, which enabled a good dispersion of nanoparticles through the triblock copolymer, without the formation of aggregates. By atomic force microscopy (AFM), the dispersion level of nanoparticles has been analyzed, together with their effect on the thin film morphology, for nanocomposites up to 15 wt% of nanoparticles. Dielectric properties of nanocomposites have been studied by dielectric relaxation spectroscopy (DRS), analyzing the effect of nanoparticles on dielectric properties. Even if conductivity and permittivity of composites increased with nanoparticle content, percolation threshold was found to be at around 15 % in volume. Morphologically analyzed nanocomposites were, in this way, below the threshold.

Hollow fiber membranes with satisfied blood compatibility and antibacterial property are desired in blood purification. Herein, a series of heparin-like copolymers of poly(methyl methacrylate-vinyl pyrrolidone -sodium styrene sulfonate-sodium acrylate) (poly(MMA-VP-SSNa-SA)) were synthesized by free radical solution polymerization. The mixture was directly blended with polyethersulfone (PES) solution to prepare hollow fiber membranes. The membranes were characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Blood compatibility of the hollow fiber membranes was evaluated via protein adsorption, platelet adhesion, clotting time, and hemolysis assay. Besides, Ag nanoparticles were immobilized onto the hollow fiber membranes efficiently by a simple and green method, and the antibacterial property and blood compatibility of the Ag-loaded membranes were then investigated. The results indicated that the approach towards blood compatible and antibacterial hollow fiber membrane is efficient and flexible for the modification for membrane materials., QC 20160223

Carbendazim (MBC) is a fungicide widely used in agriculture, and there are serious concerns regarding the health risks that could be caused by this fungicide. Here, we explore its ultrasensitive detection by surface-enhanced Raman scattering (SERS). First, to obtain maximum SERS signal, the adsorption of the target molecule onto metallic surface is essential. Therefore, we study the adsorption of the MBC onto the nanoparticle surface by SERS under different experimental conditions, such as different synthesis methods of nanoparticle, variable excitation wavelength, and fungicide concentration with the aim to detect MBC at low concentrations. Experiments are carried out with three kinds of colloidal nanoparticles: Ag and Au reduced by citrate and Ag reduced by hydroxylamine. However, mainly Ag colloids are highly efficient in the SERS detection of MBC. In addition, theoretical calculations of MBC Raman spectrum and that of the surface complex are used to help with the understanding the mechanisms responsible for the interaction between MBC and Ag. Ultraviolet-visible absorption spectroscopy showed displacement to the red of the plasmon resonance of Ag colloid in the presence of MBC. Copyright © 2015 John Wiley & Sons, Ltd.

Dynamic mechanical-thermal analysis (DMTA), differential scanning calorimetry (DSC), thermally stimulated depolarization currents (TSDC) and, mainly, broadband dielectric relaxation spectroscopy (DRS) were employed to investigate in detail glass transition and polymer dynamics in silver/poly(methyl methacrylate) (Ag/PMMA) nanocomposites. The nanocomposites were prepared by radical polymerization of MMA in the presence of surface modified Ag nanoparticles with a mean diameter of 5.6 nm dispersed in chloroform. The fraction of Ag nanoparticles in the final materials was varied between 0 and 0.5 wt%, the latter corresponding to 0.055 vol%. The results show that the nanoparticles have practically no effect on the time scale of the secondary ß and ¿ relaxations, whereas the magnitude of both increases slightly but systematically with increasing filler content. The segmental ¿ relaxation, associated with the glass transition, becomes systematically faster and stronger in the nanocomposites. The glass transition temperature T g decreases with increasing filler content of the nanocomposites up to about 10 °C, in good correlation by the four techniques employed. Finally, the elastic modulus decreases slightly but systematically in the nanocomposites, both in the glassy and in the rubbery state. The results are explained in terms of plasticization of the PMMA matrix, due to constraints imposed to packing of the chains by the Ag nanoparticles, and at the same time, of the absence of strong polymer-filler interactions, due to the surface modification of the Ag nanoparticles by oleylamine at the stage of preparation. © 2011 Elsevier Ltd. All rights reserved.

Two compounds, 4-methylthiobenzaldehyde oxime and 4-thiobenzaldehyde oxime, were synthesized for use as capture molecules for applications using surface-enhanced Raman as a means of detection. The thioether moiety was successfully attached to the silver nanoparticle substrate as evidenced by the change in the resulting spectrum. The oxime was shown to be reactive toward the nerve agent GD (Soman) in basic solution, as monitored by (31)P NMR., The original document contains color images. All DTIC reproductions will be in black and white.

The aim of this study was to examine the influence of dyeing on antibacterial efficiency of corona activated polyamide and polyester fabrics loaded with colloidal Ag nanoparticles as well as the influence of the presence of Ag nanoparticles on the color change of dyed fabrics. C.I. Acid Green 25 and C.I. Disperse Blue 3 were used for dyeing of polyamide fabrics and C.I. disperse violet 8 for polyester fabrics. The color change of polyamide fabrics depends on the dye type, which was generally lower compared to polyester fabrics. Antibacterial efficiency of Ag loaded fabrics was tested against Gram-positive bacterium Staphylococcus aureus and Gram-negative bacterium Escherichia coli. Corona activated polyester and polyamide fabrics showed excellent antibacterial efficiency independently of order of dyeing and Ag loading. The morphology of fibers loaded with Ag nanoparticles was assessed by SEM and atomic absorption spectroscopy for elemental analysis.

The aim of this study was to examine the influence of dyeing on antibacterial efficiency of corona activated polyamide and polyester fabrics loaded with colloidal Ag nanoparticles as well as the influence of the presence of Ag nanoparticles on the color change of dyed fabrics. C.I. Acid Green 25 and C.I. Disperse Blue 3 were used for dyeing of polyamide fabrics and C.I. disperse violet 8 for polyester fabrics. The color change of polyamide fabrics depends on the dye type, which was generally lower compared to polyester fabrics. Antibacterial efficiency of Ag loaded fabrics was tested against Gram-positive bacterium Staphylococcus aureus and Gram-negative bacterium Escherichia coli. Corona activated polyester and polyamide fabrics showed excellent antibacterial efficiency independently of order of dyeing and Ag loading. The morphology of fibers loaded with Ag nanoparticles was assessed by SEM and atomic absorption spectroscopy for elemental analysis.

The aim of this study was to examine the influence of dyeing on antibacterial efficiency of corona activated polyamide and polyester fabrics loaded with colloidal Ag nanoparticles as well as the influence of the presence of Ag nanoparticles on the color change of dyed fabrics. C.I. Acid Green 25 and C.I. Disperse Blue 3 were used for dyeing of polyamide fabrics and C.I. disperse violet 8 for polyester fabrics. The color change of polyamide fabrics depends on the dye type, which was generally lower compared to polyester fabrics. Antibacterial efficiency of Ag loaded fabrics was tested against Gram-positive bacterium Staphylococcus aureus and Gram-negative bacterium Escherichia coli. Corona activated polyester and polyamide fabrics showed excellent antibacterial efficiency independently of order of dyeing and Ag loading. The morphology of fibers loaded with Ag nanoparticles was assessed by SEM and atomic absorption spectroscopy for elemental analysis.