Surface modification of polyester and polyamide fabrics by low frequency plasma polymerization of acrylic acid

In this study, the surface characteristics of polyester and polyamide fabrics were changed by plasma polymerization technique utilizing acrylic acid as precursor. This monomer was used to produce hydrophilic materials with extended absorbency. The hydrophilicity, total wrinkle recovery angle (WRA°) and breaking strength of the fabrics were determined prior and after plasma polymerization treatment. The modification of surfaces was carried out at low pressure (<100 Pa) and low temperature (<50°C) plasma conditions. The effects of exposure time and discharge power parameters were optimized by comparing properties of the fabrics before and after plasma polymerization treatments. It was shown that two sides of polyester fabric samples were treated equally and homogeneously in plasma reactor. For polyester fabrics, the minimum wetting time, 0.5 s, was observed at two plasma processing parameters of 10 W–45 min and 10 W–20 min, where untreated fabric has a wetting time of 6 s. For polyester fabrics, the maximum value was obtained at 60 W–5 min with the wrinkle recovery angle of 306° where the untreated fabric has 290°. The optimum plasma conditions for polyamide fabrics were determined as 30 W–45 min where 2 s wetting time was observed. Wrinkle recovery angle of untreated polyamide fabric was 264°. In this study, after plasma polymerization of acrylic acid, wrinkle recovery angle values were increased by 13%. No significant change was observed in breaking strength of both fabrics after plasma treatment. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2318–2322, 2007     

UV curable lens production using molecular weight controlled PEEK based acrylic oligomer (Ac-PEEK)

We produced UV curable lenses with properties blocking short wave UV light. In the UV-curable formulations, we used an oligomer (Ac-PEEK) with another urethan oligomer (Mw = 2000). Radically active, molecular weight controlled Ac-PEEK was obtained by reacting 2-hydroxyl ethyl methacrylate with molecular- weight- controlled and isocyanate terminated PEEK (Mn = 4500). We characterized all synthesized monomer, oligomer and optical materials with UV/Vis spectrophotometer with interferogram, elemental analyser, mass spectrophotometer, proton nuclear magnetic resonance, Fourier transform infrared spectroscopy, thermal gravimetric analyzer, differential scanning calorimeter, scanning electron microscopy and gas chromatography. Results suggested that newly synthesized oligomer with the structure of PEEK absorbs short wave UV-light. Ageing tests [ISO 11979-5, Ophthalmic implants—intraocular lenses (IOL)—Part 5: Biocompatibility] performed on the IOL materials were successful. High contact angle of the obtained lenses suggests that all lenses were hydrophobic and SEM results revealed that lenses are morphologically homogeneous. Based on all positive properties just mentioned, we safely conclude that the lenses produced in this study are very promising for IOL production.     

Application of antimicrobial ice for extending shelf life of fish

In this study, we investigated whether wild-thyme (Thymus serpyllum) hydrosol had a preserving effect against spoilage of freshwater fish. Sensorial characteristics, chemical freshness indicator contents, and microbial counts (total aerobes, psychrotrophics, Enterobacteriaceae, fecal coliform bacteria, Aeromonas spp., and Pseudomonas spp.) of whole ungutted and gutted Transcaucasian barb (Capoeta capoeta capoeta Guldenstaedt, 1772) stored on ice produced from wild-thyme hydrosol and tap water at 4 degrees C for 20 days were compared. The results did not reveal any significant (P > 0.05) differences in the microbial counts, sensorial characteristics, pH, and total volatile basic nitrogen values between gutted and ungutted groups. Sensory evaluation and microbiological and chemical analyses indicated that the storage of the fish on ice produced from wild-thyme hydrosol had a significant increase in shelf life by at least 15 to 20 days.     

Assessment of antioxidant activity and phycocyanin release of Spirulina loaded poly(ε-caprolactone) electrospun nanofibers

PCL with biodegradable property and Spirulina with various biological activities offer good alternative ingredients for the fabrication of functional nanofibers in tissue engineering. The aim of the study is to obtain PCL/Spirulina nanofibers with low diameters and to determine their wettability, antioxidant activity, and phycocyanin release to evaluate their potential as bioactive scaffolds in different applications. PCL/acetic acid/pyridine solutions with three different Spirulina concentrations were electrospun and the obtained nanofibers were investigated. The thinnest PCL/Spirulina nanofibers (117.20 nm) were obtained at 1.5% Spirulina concentration. Although PCL nanofibers with 6% Spirulina concentration showed the highest antioxidant activity and amount of phycocyanin released, PCL nanofibers with 3% Spirulina concentration having similar in vitro results showed superiority when considering the diameter and uniformity of the nanofibers and the cost of the material. The PCL/Spirulina nanofibers with small diameters and antioxidant activity could be regarded as potential extracellular matrix material for tissue engineering.     

Notes on chlorinated polyethylene: Its preparation,some mechanical and thermal properties

Low density polyethylene was chlorinated via a mixed solution-suspension technique at three different temperatures. The products obtained at different conditions had properties ranging from hard brittle to tough elastomeric consistencies. Static mechanical, chemical, and thermal characterization of the products were made and the possibility of two different crystal structures is pointed out, one of which is consumed preferentially during chlorination.     

A new approach for measuring RMS value and phase angle of fundamental harmonic based on Wavelet Packet Transform

Traditional ways of calculating/measuring harmonics in power systems have been based on Fourier Transform and algorithms, such as Fast Fourier Transform and Goertzel that implements it. In this study, a novel approach based on Wavelet Packet Transform is presented to measure Root-Mean-Square (RMS) value and phase angle of the fundamental harmonic. To this end, analytical expressions were derived and using a Graphical User Interface (GUI) designed and experimental works the validity of analytical expressions was demonstrated.     

Visual enhancement of underwater images using Empirical Mode Decomposition

Most underwater vehicles are nowadays equipped with vision sensors. However, it is very likely that underwater images captured using optic cameras have poor visual quality due to lighting conditions in real-life applications. In such cases it is useful to apply image enhancement methods to increase visual quality of the images as well as enhance interpretability and visibility. In this paper, an Empirical Mode Decomposition (EMD) based underwater image enhancement algorithm is presented for this purpose. In the proposed approach, initially each spectral component of an underwater image is decomposed into Intrinsic Mode Functions (IMFs) using EMD. Then the enhanced image is constructed by combining the IMFs of spectral channels with different weights in order to obtain an enhanced image with increased visual quality. The weight estimation process is carried out automatically using a genetic algorithm that computes the weights of IMFs so as to optimize the sum of the entropy and average gradient of the reconstructed image. It is shown that the proposed approach provides superior results compared to conventional methods such as contrast stretching and histogram equalizing.