A chaotic image encryption algorithm based on perceptron model

Based on the high-dimension Lorenz chaotic system and perceptron model within a neural network, a chaotic image encryption system with a perceptron model is proposed. This paper describes the algorithm flow in detail, and analyses the cryptographic security. The experimental results show that this algorithm has high security, and strong resistance to the existing attack methods.     

Color image encryption using skew tent map and hyper chaotic system of 6th-order CNN

The paper designs a color image encryption scheme based on skew tent map and hyper chaotic system of 6th-order CNN. The essence of the image encryption is to confuse and diffuse the pixels, the skew tent map is applied to generate the confusion sequence, and the hyper chaotic system of 6th-order CNN is applied to generate the diffusion sequence, for 6 state variables in the system, there are total 120 combinations. For each pixel of the plain image, one combination is chosen to encryption the red, green and blue components, and the combination is determined by one of the state variables. Each pixel is encrypted by the cipher value of the previous pixel and the combination value of the CNN system. Experimental results and security analysis demonstrate that the scheme can achieve good encryption result and larger key space, and can resist common attacks, so the scheme can be applied in secure communication to enhance the security of transmitting image.     

Electrochemical behavior of polyaniline films in acetonitrile

The electro-oxidation and electroreduction behavior of polyaniline films in acetonitrile in the absence and presence of added acid or base were investigated using cyclic voltammetry. A general mechanism is proposed that enables the interpretation of the electroactivity loss and the catalytic and autocatalytic properties of the film. The electroactivity loss was found to be a reversible phenomenon which is accelerated in alkaline solutions through deprotonation. Electroactivity was recovered when the electroinactive films were reduced in an acidic solution. The films that lose their electroactivity on electro-oxidation were found to be conducting, and various cation radicals in the structure are believed to be responsible for this nonprotonic conductivity. The proton content of the polyaniline film was found to be crucial in determining its electrochemical and physical properties. Autocatalysis was detected when protons were produced electrolytically in situ during electropolymerization.     

Metal-Enhanced Fluorescence of Phycobiliproteins from Heterogeneous Plasmonic Nanostructures

We report here the use of plasmonic metal nanostructures in the form of silver island films (SiFs) to enhance the fluorescence emission of five different phycobiliproteins. Our findings clearly show that the phycobiliproteins display up to a 9-fold increase in fluorescence emission intensity, with a maximum 7-fold decrease in lifetime when they are assembled as a monolayer above SiFs, as compared to a monolayer assembled on the surface of amine-terminated glass slides of the control sample. The study was also repeated with a thin liquid layer of the phycobiliproteins sandwiched between two glass substrates (and a SiFs and a glass substrate) clamped together. Similarly, the results show a maximum 10-fold increase in fluorescence emission intensity coupled with a 2-fold decrease in lifetime of the phycobiliproteins in the SiF-glass setup as compared to the glass control sample, implying that near-field enhancement of phycobiliprotein emission can be attained both with and without chemical linkage of the proteins to the SiFs. Hence, our results clearly show that metal-enhanced fluorescence (MEF) can potentially be employed to increase the sensitivity and detection limit of the plethora of bioassays that employ phycobiliproteins as fluorescence labels, such as in fluoro-immunoassays where the assay can be tethered on the surface of SiFs, and also in flow cytometry where analytes in the liquid phase could potentially flow through channels coated with SiFs without actually being attached to the silver.     

Electrochemically controlled solid-phase microextraction (EC-SPME) based on overoxidized sulfonated polypyrrole

A method for the extraction and selective determination of cations is proposed using electro-synthesized overoxidized sulfonated polypyrrole film. The polymer film is used for the selective extraction of trace levels of nickel and cadmium ions by solid-phase microextraction (SPME). The cation uptake and release properties of the overoxidized sulfonated polypyrrole film electrode were examined under both open circuit and controlled potential conditions for prospective applications in electrochemically controlled solid-phase microextraction. Increased extraction efficiency and selectivity toward cations were achieved in high saline content of water. Simple preparation of film coatings on a platinum wire was possible using a constant potential method. Applied positive and negative potentials facilitated the extraction and desorption of cations, respectively. Nickel and cadmium ions were desorbed into sample aliquot and determined by electrothermal atomic absorption spectrometry (ETAAS). The cation uptake and release mechanism is affected both by the cation exchange at the negative sulfonate and carboxylate moiety on the film and the altered solution pH occurring at the counter electrode caused by the applied potential. The method was validated using a standard reference material and tested for the determination of cadmium ion in commercial table salt samples.     

Metal-Enhanced Fluorescence from Plastic Substrates

We report the first findings of Metal-Enhanced Fluorescence (MEF) from modified plastic substrates. In the past several years our laboratories have reported the favorable effects of fluorophores in close proximity to silver nanoparticles. These effects include, enhanced fluorescence intensities, (increased detectability), and reduced lifetimes, (enhanced fluorophore photostability). All of these reports have featured silver nanostructures and fluorophores which have been immobilized onto clean glass or quartz surfaces. In this report we show how plastic surfaces can be modified to obtain surface functionality, which in turn allows for silver deposition and therefore metal-enhanced fluorescence of fluorophores positioned above the silver using a protein spacer. Our findings show that plastic substrates are ideal surfaces for metal-enhanced phenomena, producing similar enhancements as compared to clean glass surfaces. Subsequently, we speculate that plastic substrates for MEF will find common place, as compared to the more expensive and less versatile traditional silica based supports.     

Comparative solid phase extraction study on the U(VI) preconcentration by using immobilized thermotolerant <Emphasis Type="Italic">Bacillus vallismortis</Emphasis> and <Emphasis Type="Italic">Bacillus mojavensis</Emphasis>

Bacillus vallismortis and Bacillus mojavensis were loaded onto Amberlite XAD-4 resin and used for solid phase extraction (SPE) of uranium(VI). A quick and simple UV–Vis spectrophotometric method was used to determine U(VI) ion. The best experimental conditions were determined as being a pH of 5.0; a sample flow rate of 2.0 mL min^?1; 200.0 mg of biosorbent; 800 mg of Amberlite XAD-4, and 5.0 mL of 1 mol L^?1 HCl as desorption solution for both immobilized bacteria. The preconcentration factors were achieved as 80 for both solid phase extractor. The developed methods were validated by applying to reference water and tea samples.     

First Observation of Surface Plasmon-Coupled Chemiluminescence (SPCC)

In this letter, we report the first observation of surface plasmon-coupled chemiluminescence (SPCC), where the luminescence from chemically induced electronic excited states couples to surface plasmons in a thin continuous silver film. The SPCC is highly directional and predominantly p-polarized, strongly suggesting that the emission is from surface plasmons instead of the luminophores directly themselves. This indicates that surface plasmons can be directly excited from chemically induced excited states. With a wealth of assays that employ chemiluminescence based detection currently in use, then our findings suggest new chemiluminescence sensing strategies based on localized, directional and polarized chemiluminescence detection.