Synthesis and characterization of polyaniline films using Fenton reagent

The chemical oxidation of aniline to form polyaniline (PANI) films and powder samples was made using Fenton reagent as an oxidizing agent in aqueous sulfuric acid medium. The PANI films were monitored by using the quartz crystal microbalance and the electronic absorption techniques. The optimum concentration was determined and the results were justified by measuring the UV–vis absorption spectra for the in situ PANI films. The conductivity for the PANI films and powder samples, prepared in different conditions, was measured. Also, the IR spectra, X‐ray and the thermogravimetric analysis for the PANI powder formed in the bulk were measured and compared with the polymer prepared using ammonium peroxydisulfate. A preliminary investigation to the dielectric properties of the polymer powder was measured and discussed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Mucosal Adjuvants Delivered by a Mucoadhesive Patch for Sublingual Administration of Subunit Vaccines

Among mucosal administration routes for vaccines, the sublingual route has been proven capable of inducing a potent systemic and mucosal immune response. However, the absence of a simple and compliant delivery system and the lack of robust mucosal adjuvants impede the development of sublingual vaccines. Here, we describe a mucoadhesive patch made of a layer-by-layer assembly of polysaccharides, chitosan, and hyaluronic acid. The mucoadhesive patch was covered by adjuvanted nanoparticles carrying viral proteins. We showed that the nanoparticles effectively cross the outer layers of the sublingual mucosa to reach the epithelium. Furthermore, the encapsulated adjuvants, 3M-052 and mifamurtide, targeting toll-like receptor (TLR) 7/8 and nucleotide-binding oligomerization domain-2 (NOD2), respectively, remain fully active after encapsulation into nanoparticles and exhibit a cytokine/chemokine signature similar to the mucosal gold-standard adjuvant, the cholera toxin. However, the particulate adjuvants induced more moderate levels of proinflammatory interleukin (IL)-6 and keratinocyte chemoattractant (KC), suggesting a controlled activation of the innate immune response.     

Retardation of High-Temperature Fuel Ash Corrosion of Fireside Boiler Tubes via Nanoparticles

The high-temperature corrosion rate of boiler tubes was studied as a function of inhibitor concentration, time, and temperature in the absence and presence of fuel ash. Samples of steel tubes were taken from boilers that operate in Northern Baghdad Station for Electric Power Generation. Fuel ash was collected from the boiler combustion chamber, as well. Normal and nano-MgO were used as a corrosion inhibitor in different mixing ratios. A weight loss technique was used to evaluate the corrosion rates, while scanning electron microscopy was used to study the surface morphology. It was seen that corrosion rates increased with both time and temperature, and decreased with the addition of inhibitors. The maximum inhibitor efficiency was 81 %, obtained via using nano-MgO at mixing weight ratio 2:1, 600 °C, and 10 h. The Presence of fuel ash had harmful effects on the steel surface.     

Design considerations of high performance optical code division multiple access: a new spectral amplitude code based on laser and light emitting diode light source

A new code of optical code division multiple access (OCDMA) based on spectral amplitude coding (SAC) is described and analysed. The coding technique is called random diagonal (RD) code. One of the important properties of this code is that the cross-correlation at data segment is always zero, which means that phase intensity induced noise (PIIN) is reduced. From the construction of RD code sequence, the authors can see that the RD code is constructed using code segment and data segment. Using this code property, RD code is implemented using coherent source (multi-laser) and incoherent source (light emitting diode) for the code segment and data segment, respectively. RD code using two multi-sources (incoherent and coherent) can be considered as an effective way for maximising the capacity while minimising the cost of SAC-OCDMA. It is shown that the system using this new code matrices not only suppresses PIIN, but also allows a larger number of active users compared with other codes.     

Four-wave mixing reduction technique based on smart filter approach

This paper proposed a new technique to suppress the four-wave mixing (FWM) effect by using a smart filter technique. The behaviour of FWM and the performance of wavelength division multiplexing systems with 4 and 16 channels were simulated in the presence of the proposed technique. The simulation was also performed under different parameters such as input power, number of channels and channel spacing. The FWM power drastically decreases by 12 and 19 dB for the 4 and 16 channels, respectively, when the smart filter is used as compared with the conventional system. In terms of system performance, the suggested approach for 4 and 16 channels at the first channel offers low bit error rate (BER) values of 3.23 × 10^?23 and 1.7 × 10^?21, respectively. The smart filter with the channel spacing variation for the 4-channel system subsequently improved the BER value at the fourth channel. Results confirm that the smart filter approach is an active solution that can suppress the FWM effect in optical transmission systems.     

Determination of the dopant weight fraction in polyaniline films using a quartz-crystal microbalance

The electrical conductivity of polyaniline depends on factors such as degree of oxidation, type of protonation, and dopant weight fraction. The last of these factors is connected with the loss of mass during the deprotonation of polyaniline, and can thus conveniently be determined in situ by the use of a quartz microbalance. This is illustrated in the present paper which concerns the determination of the weight fraction of acid in thin polyaniline films prepared by the chemical oxidation of aniline in the aqueous solutions of sulfuric and phosphoric acids. It is illustrated that the deprotonation-reprotonation processes are fast, complete, and reversible. Polyaniline has sulfate counter-ions in 0.1 M sulfuric acid while, in 0.5-1 M sulfuric acid, hydrogen sulfate counter-ions are present. The quartz microbalance involving polyaniline films can be used in the sensing of the acidity.     

A modified SAR range-Doppler algorithm with Gaussian frequency waveforms

High-resolution synthetic aperture radar (SAR) imaging based on airborne representation has attracted much attention and considerable interest in many remote-sensing fields due to its potential for improving the data quality of various applications. To obtain the intended resolution, different effective algorithms have been proposed and improved by using several techniques, methods, and modifications of the radar waveforms. The range-Doppler is one of these algorithms where different waveforms are used to achieve the focusing of targets, especially chirp signals. In this article, we propose the use a new modulation called Gaussian linear frequency modulation to perform the Gaussian range-Doppler algorithm and compare its performance with the conventional range-Doppler algorithm. The comparison is carried out in several bands of the SAR. Also, the effectiveness of the proposed algorithm is performed and discussed for a simple point target. The simulation results show that the proposed algorithm can improve significantly the target focusing.     

Spectrophotometric and atomic absorption spectrometric determination of ramipril and perindopril through ternary complex formation with eosin and Cu(II)

Two sensitive, spectrophotometric and atomic absorption spectrometric procedures are developed for the determination of ramipril and perindopril. Both methods are based on the formation of a ternary complex, extractable with chloroform, between copper(II), eosin and the two cited drugs. Spectrophotometrically under the optimum condition, the ternary complexes showed an absorption maximum at 535 nm, with apparent molar absorptivities of 6.55 and 4.00 x 10(3) mol(-1) x cm(-1) and Sandell's sensitivities of 5.80 x 10(-2) and 1.04 x 10(-1) microg x cm(-2) for perindopril and ramipril, respectively. The solution of ternary complex obeyed Beer's law in concentration ranges 10-60 and 20-100 microg x ml(-1) for perindopril and ramipril, respectively. The proposed method was applied to the determination of the two cited drugs in pharmaceutical tablets. The atomic absorption spectrometric method, directly through the quantitative determination of copper content of the organic extract of the complex, was also investigated for the purpose of enhancing the sensitivity of the determination. The spectrophotometric and atomic absorption spectrometric procedures hold their accuracy and precision well when applied to the determination of ramipril and perindopril dosage forms.