Elastoviscous Systems Based on Solutions of Chitosan–Methyl Acrylate and Chitosan Succinamide–Methyl Acrylate Copolymers

Rheological studies of solutions of amphiphilic copolymers based on hydrophilic polysaccharides chitosan (CT) and chitosan succinamide (CTS) sodium salt with methyl acrylate (MA) synthesized by radical copolymerization have been conducted. It has been found that the hydrophobic interaction of poly(methyl acrylate) blocks in solutions of CT–MA and CTS–MA copolymers leads to an increase in the degree of structuring of macromolecules; this feature leads to the formation of an elastoviscous system without introducing of an additional crosslinking agent.     

Fluorescence Microscopy of Nanoscale Silver Oxide Thin Films

The experimental conditions for photoactivated intermittent fluorescence from nanoscale silver oxide were studied with fluorescence microscopy.Strong fluorescence was observed from the Ag2O particles with size of 10-20nm excited with both blue and green light .We observed the saturation of Photoexcitation with blue light and explained the experimental results using the model of agglomeration of silver atoms to form small clusters and the fluorescence of Ag2 and Ag3 clusters.     

Preparation of Silver—Coated Polystyrene Composite Particles

We report a feasible approach to the preparation of monodispersed metal-shell composite microspheres based on a combination of surface reaction and surface seeding techniques. The method was implemented for coating polystyrene (PS) spheres with silver shell having a variable thickness by controlling the amount of reagents in the reaction procedure. These composite spherical particles in dimensions of the submicrometer range may become attractive building blocks for the creation of metallo-dielectric photonic band gap materials when they are organized into crystals.     

Refit Silver Nanostructures Using a Convergent Electron Beam

Using a superionic conductor AgI thin film and a direct current electric field, we synthesize silver nanowires in diameter of about lOOnm. In order to refit the prepared nanowires, the samples are irradiated by a convergent electron beam （200 k V） inside a transmission electron microscope to prepare new small silver nanostructures. The new nanostructures are investigated in situ by high-resolution transmission electron microscope. This electron- induced crystal growth method is useful for technical applications in fabrication of nanodevices.     

Electric Field Enhancement of Nano Gap of Silver Prisms

Using numerical calculation, we examine the effects of gap distance of a pair of nano gap silver prisms with rounded corners on the local light intensity enhancement. Two peaks due to localized surface plasmon （LSP） excitation are observed in a wavelength range from 900nm to 300nm. The results demonstrate that peaks at a longer and a shorter wavelength corresponded to dipole-like and quadrupole-like LSP resonances, respectively. It is found that a gap distance up to 20 nm provides larger light intensity enhancement than that of a single silver nano prism with rounded corners. Furthermore, nano gap silver prisms are fabricated by direct focused ion beam processing, and we measure the scattering light spectrum of a pair of nano prisms by a confocal optical system. However, the two LSP peaks are not observed in visible range because the sizes of the nano gap and prisms are too large.     

New Silver Halide Sensitized Gelatin Material: Its Processing

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Total Integration of the Sample Injection,Microdroplet Reaction,Phase Separation,Real-Time Optical Detection,and Recovery of Diverse Silver–Gold Bimetallic Nanoalloys in a Continuous Process

Microfluidic droplet generators have garnered great attention due to the uniformity, high-throughput capability, and facile experimental setup. To maximize the potentials of droplet technology as a chemical/biological nanoliter-scale reactor, the downstream processes such as separation of the aqueous and oil phase, real-time monitoring of the products formed in droplets, and the final product recovery from the droplets is necessary. In this study, the droplet is utilized as a chemical reactor to synthesize a variety of Ag and Au bimetallic nanoalloys in a fully integrated microsystem including sample injection, a T-junction droplet generator, droplet reaction, water–oil phase separation, real-time UV–vis absorbance detection, and product recovery. The flow rate of the Ag nanoparticle (NP) solution and the HAuCl₄ solution was tuned to generate different molar ratios of Ag and Au components. The in-line UV–vis absorbance spectrometer displays a peak shift of the Ag/Au bimetallic alloys depending on the molar ratio of Ag/Au in the continuous process, enabling to judge the kind of the Ag/Au alloys in situ and collect a variety of Ag/Au nanoalloys. Thus, the desired nanomaterials can be obtained with minimal trial and error, saving time and cost.     

Bimetallic Silver–Gold Film Waveguide Surface Plasmon Resonance Sensor

Abstract

It is desirable that a surface plasmon resonance (SPR) sensor is highly sensitive to binding interactions within the sensing region, generate evanescent fields with long penetration depths, and utilize a metal film that is very stable even in extreme environmental conditions. In this study, we present the first example of a wavelength-modulated waveguide SPR sensor with a bimetallic silver–gold film for surface plasmon excitation. The underlying silver yields better evanescent field enhancement of the sensing surface, while the overlying gold ensures that the stability of the metallic film is not compromised. It is shown experimentally that in terms of dλ/dn, the bimetallic film waveguide SPR configuration has a sensitivity of 1232 nm/RIU, greater than two times improvement from the 594 nm/RIU achievable with single gold film waveguide SPR sensor. The higher sensitivity, compact nature, and better evanescent field enhancement of this configuration provides the potential to biosensing applications.     

Laser and Thermal Modification of Silver–Ion Implanted Glasses

We investigate sodium–calcium silicate glasses implanted with 60 keV Ag⁺ ions with a dose of 3·10¹⁶ cm^–2 at an ion current density of 10 A/cm². As a result of the ion implantation, a composite layer with silver nanoparticles is synthesized in the region near the surface. However, this layer is characterized by high nonuniformity in the size distribution of these particles over the depth of the layer. Subsequent pulsed laser irradiation in combination with equilibrium heat treatment makes it possible to modify this composite layer, improving the uniformity in the size distribution of the nanoparticles. This is particularly promising for the improvement of the technology of obtaining nonlinear optical materials. To control the parameters of the layers obtained we suggest a method based on an analysis of the optical reflection and transmission spectra measured on the side of the implanted and opposite surfaces of glass samples.     

Studies on the Miscibility of Chitosan/Poly(vinyl pyrrolidone) Blend in Solution by Viscometry,Ultrasonic Velocity,Density and Refractometry Techniques at 30, 40, and 50°C

Polymer blends of chitosan (CHI) with poly(vinyl pyrrolidone) (PVP) have been prepared by solution blending, and their miscibility studies were carried out by using physical techniques over an extended range of concentration and composition in buffer solution. The viscosity, ultrasonic velocity, density, and refractive index were measured at 30, 40, and 50°C, respectively. Using viscosity data, the interaction parameter μ and α were computed to probe the miscibility. These values revealed that the blend is miscible when the chitosan content is more than 60% in the blend at all temperatures. The obtained results were further confirmed by the ultrasonic velocity, density, and refractive index measurements.     

Silver–titanium dioxide nanocomposites as effective antimicrobial and antibiofilm agents

Recent studies have revealed the existence of liver cancer stem cells (CSCs). Therefore, there is an urgent need for new and effective treatment strategies specific to liver CSCs. In this work, the poly(d,l-lactide-coglycolide) nanoparticles containing paclitaxel were prepared by emulsification-solvent evaporation method. The nanoparticles decorated with anti-CD133 antibody, termed targeted nanoparticles, were prepared by carbodiimide chemistry for liver CSCs. The physicochemical characteristics of the nanoparticles (i.e., encapsulation efficiency, particle size distribution, morphology, and in vitro release) were investigated. Cellular uptake and accumulation in tumor tissue of nanoparticles were observed. To assess anti-tumor activity of nanoparticles in vitro and in vivo, cell survival assay and tumor regression study were carried out using liver cancer cell lines (Huh7 and HepG2) and their xenografts. Particle size of targeted nanoparticles was 429.26 ± 41.53 nm with zeta potential of ?11.2 mV. Targeted nanoparticles possessed spherical morphology and high encapsulation efficiency (87.53 ± 5.9 %). The accumulation of targeted nanoparticles depends on dual effects of passive and active targeting. Drug-loaded nanoparticles showed cytotoxicity on the tumor cells in vitro and in vivo. Targeted nanoparticles resulted in significant improvement in therapeutic response through selectively eliminating CD133 positive subpopulation. These results suggested that the novel nanoparticles could be a promising candidate with excellent therapeutic efficacy for targeting liver CSCs.     

Structural Thermo‐ and Phototransformations of Oxaindane Spiropyrans Adsorbed on Silver Films

Using giant Raman scattering spectroscopy methods, we have studied the structure and also the thermo and phototransformations of dimethylphthalanspirobenzopyran (PhSBP) adsorbed on the surface of silver films. It is shown that on adsorption of PhSBP from ethanol solutions, on the surface of the silver films there are predominantly open forms of molecules which do not exhibit photochromic properties. It is established that cooling of the specimen to 77 K initiates thermoreversible reconstruction of the adsorption layer with formation of the aggregates of the PhSBP molecules. These reversible structural changes in frozen specimens are enhanced on exposure to the light of a visible range.     

Surface Plasmon Sensor Based on a Dual Dielectric–Silver Photonic Crystal

We present a new type of biosensor. The principle of operation of the device is similar to conventional surface plasmon sensors, except that the ordinary metallic film in surface plasmon sensors is replaced by a one-dimensional photonic bandgap array. The advantages of using a photonic bandgap structure, instead of a metallic film, include enhanced sensitivity, physical and chemical robustness, and the ability to engineer the optical response of the device. We propose and elaborate a biosensor based on a onedimensional (1D) photonic crystal (PC) with a surface plasmon resonance (SPR). In comparison with standard SPR sensors that use silver (Ag ) or gold (Au) films, PC–Ag–PC–Au structures have narrower resonance widths, lower minimum reflectance, and higher sensitivity, making them a much better choice for biosensing applications. Moreover, the structure is compact (H = 1.139 μm), providing a better option in biosensing in comparison with other PC-SPR and conventional SPR sensors.     

Thin Film Encapsulation of Light-Emitting Diodes with Photopolymerized Polyacrylate and Silver Films

A thin film encapsulation of organic light-emitting diodes （OLEDs） is investigated with a multi-layer stack of polyacrylate-Ag-polyacrylate-Ag-polyacrylate-Ag-polyacrylate （PAPAPAP）. It is shown that the fabrication of polyacrylate films by a wet process does not affect the electroluminescent （EL） characteristics of the devices and polyacrylate films together with the silver layers can perform to minimize oxygen and water diffusion into the organic light-emitting device. The structure of polyacrylate（20μm）-Ag（200nm）-polyacrylate（20μm）-Ag（200nm）- polyacrylate（20μm）-Ag（200nm）-polyacrylate（20μm） is demonstrated to enhance dramatically the lifetime of OLEDs.     

Silver nanoparticle size–dependent measurement of quantum efficiency of Rhodamine 6G

The plasmonic absorption band of silver nanoparticles in the visible range of electromagnetic spectrum has been successfully exploited to alter the emission characteristics of the Rhodamine 6G dye molecule. The influence of the nanoparticle size on the fluorescence quantum yield of Rhodamine 6G is interrogated via steady state fluorescence as well as dual beam thermal lens technique. The potential of the thermal lens technique that probe nonradiative path in contrast to radiative path exhibited in the fluorescence spectra as a complementary method to measure the quantum yield of a dye molecule is exploited. Analysis of the results clearly indicates that the particle size and the spectral overlap between the emission spectra of Rhodamine 6G, and absorption spectra of the silver nanoparticles determine the quantum yield value of dye–nanoparticle mixture.     

Gelatin–Chitosan composite capped gold nanoparticles: a matrix for the growth of hydroxyapatite

Growth of hydroxyapatite (HA) on gelatin–chitosan composite capped gold nanoparticles is presented for the first time by employing wet precipitation methods and we obtained good yields of HA. Fourier transform infrared spectroscopy (FTIR) spectrum has shown the characteristic bands of phosphate groups in the HA. Scanning electron microscopy (SEM) pictures have shown spherical nanoparticles with the size in the range of 70–250 nm, whereas ≥2–50 nm sized particles were visualized in high resolution transmission electron microscopy (HR-TEM). X-ray diffraction (XRD) spectrum has shown Bragg reflections which are comparable with the HA. Energy dispersive X-ray (EDX) studies have confirmed calcium/phosphate stoichiometric ratio of HA. The thermogravimetric analysis (TGA) has shown about 74% of inorganic crystals in the nanocomposite formed. These results have revealed that gelatin–chitosan capped gold nanoparticles, acted as a matrix for the growth of HA.     

Characteristics of Photoelectron Decay of Silver Halide Microcrystal Illuminated by a Short Pulse Laser

A YAG supershort pulse laser (355nm,35ps) is used as an exposure source and the microwave dielectric spectri, technique is used to quickly detect the photoelectron decay process in AgX microcrystals,because the free photoelectron lifetime and decay process can decide the sensitivity and other efficiencies of silver halide material.The result shows that the free photoelectron average lifetimes of Kodak-100 and Fuji-100 colour film samples are 8.5 and 9.5 ns,respectively.     

Influence of Femtosecond Laser Irradiation and Heat Treatment on Precipitation of Silver Nanoparticles in Glass

Silver nanoparticles were precipitated inside an Ag2O-doped glass by femtosecond laser irradiation and successive heat treatment. The influence of heat treatment temperature on the precipitation of silver nanoparticles was investigated. Absorption spectra show that the femtosecond laser irradiation results in an apparent decrease of the treatment temperature for the precipitation of Ag nanoparticles. We demonstrate the control of precipitation, dissolution and growth of silver nanoparticles inside glass by changing the heat treatment temperature of using further femtosecond laser irradiation.