Removal of phenol and chlorophenols from water with reusable dye-affinity hollow fibers

Reactive Green HE 4BD carrying polyamide hollow fibers were investigated as dye-affinity adsorbents for removal of chlorophenols (i.e., phenol, o-chlorophenol, p-chlorophenol and 2,4,6-trichlorophenol). Adsorption rates of chlorophenols were very high. Equilibrium was achieved in about 30 min. The applicability of two kinetic models including pseudo-first order and pseudo-second order model was estimated on the basis of comparative analysis of the corresponding rate parameters, equilibrium capacity and correlation coefficients. Results suggest that chemisorption process could be the rate-limiting step in the adsorption process. The maximum adsorption values of chlorophenols onto the Reactive Green HE 4BD carrying hollow fibers were 145.9 micromol/g for phenol, 179.2 micromol/g for 2,4,6-trichlorophenol, 194.5 micromol/g for p-chlorophenol and 202.8 micromol/g for o-chlorophenol. The affinity order was as follows: o-chlorophenol>p-chlorophenol>2,4,6-trichlorophenol>phenol. The adsorption capacity of chlorophenols decreased with increasing pH. Desorption of chlorophenols was achieved using methanol solution (30%, v/v). The Reactive Green HE 4BD-carrying hollow fibers are suitable for repeated use for more than 10 cycles without noticeable loss of adsorption capacity.     

Investigating the effects of ingredient levels on physical quality properties of cooked hamburger patties using response surface methodology and image processing technology

A three-factor central composite design was adopted to determine the interactive effects of fat (15–30%), water (10–20%) and textured soy protein (3–9%) content on the shrinkage, fat loss and moisture loss of hamburger patties after cooking. Image processing was used to estimate the shrinkage of hamburger patties. Textured soy protein (TSP) content was found to be the most important factor for minimizing fat and moisture loss. Both fat and water content were found to be significantly effective (P < 0.05) in the model for shrinkage and moisture loss in linear form. The changes in shrinkage due to fat, water and TSP content were also in linear form. The model for fat loss was in linear and quadratic form, whereas the model for moisture loss was in full quadratic form. The models for shrinkage, fat loss and moisture loss had the R-square values of 0.954, 0.969 and 0.964, respectively.     

A pattern recognition framework to blind audio watermark decoding

Conventional blind audio watermark (WM) decoders use matched-filtering techniques because of their simplicity. In these methods, WM decoding and WM detection are often considered as separate problems and the WM signal embedded by spreading a secret key through the spectrum of a host signal is extracted by maximizing correlation between the secret key and the received audio. Conventionally decoding is achieved by using a pre-defined decoding/detection threshold and tradeoff between the false rejection ratio and false acceptance ratio constitutes main drawback of the conventional decoders. Unlike the conventional methods, this paper introduces a pattern recognition (PR) framework to WM extraction and integrates WM decoding and detection problems into a unique classification problem that eliminates thresholding. The proposed method models statistics of watermarked and original audio signals by a Gaussian mixture model (GMM) with K components. Learning of the embedded WM data is achieved in a principal component analysis (PCA) transformed wavelet space and a maximum likelihood (ML) classifier is designed for WM decoding. Robustness of the proposed method is evaluated under compression, additive noise and Stirmark benchmark attacks. It is shown that both WM decoding and detection performances of the introduced decoder outperform the conventional decoders.     

Chiral recognition of proteins having L-histidine residues on the surface with lanthanide ion complex incorporated-molecularly imprinted fluorescent nanoparticles

In this study, lanthanide ion complex incorporated molecularly imprinted fluorescent nanoparticles were synthesized. A combination of three novel approaches was applied for the purpose. First, lanthanide ions [Terbium(III)] were complexed with N-methacryloyl-L-histidine (MAH), polymerizable derivative of L-histidine amino acid, in order to incorporate the complex directly into the polymeric backbone. At the second stage, L-histidine molecules imprinted nanoparticles were utilized instead of whole protein imprinting in order to avoid whole drawbacks such as fragility, complexity, denaturation tendency, and conformation dependency. At the third stage following the first two steps mentioned above, imprinted L-histidine was coordinated with cupric ions [Cu(II)] to conduct the study under mild conditions. Then, molecularly imprinted fluorescent nanoparticles synthesized were used for L-histidine adsorption from aqueous solution to optimize conditions for adsorption and fluorimetric detection. Finally, usability of nanoparticles was investigated for chiral biorecognition using stereoisomer, D-histidine, racemic mixture, D,L-histidine, proteins with surface L-histidine residue, lysozyme, cytochrome C, or without ribonuclease A. The results revealed that the proposed polymerization strategy could make significant contribution to the solution of chronic problems of fluorescent component introduction into polymers. Additionally, the fluorescent nanoparticles reported here could be used for selective separation and fluorescent monitoring purposes.     

Precursor route poly(thienylene vinylene) for organic solar cells: Photophysics and photovoltaic performance

Photophysical studies and photovoltaic devices on a low bandgap, high-charge carrier mobility poly(thienylene vinylene) (PTV), prepared from a soluble precursor polymer synthesised via the “dithiocarbamate route”, are reported. In composites with an electron acceptor ([6,6]-phenyl C₆₁-butyric acid methyl ester (PCBM), a soluble fullerene derivative), photoinduced absorption characteristic for charged excitations together with photoluminescence quenching are observed indicating photoinduced electron transfer. The “bulk heterojunction” photovoltaic devices using PTV and PCBM composites show short-circuit currents up to 4 mA/cm² under AM 1.5 white-light illumination. The photocurrent spectrum of the photovoltaic device shows an onset about 1.65 eV (750 nm), which corresponds to the absorption spectrum of the polymer.     

Inhibition kinetics of polyphenol oxidase by glutamic acid

The inhibition of polyphenol oxidase (PPO) by glutamic acid was investigated. Application of different concentrations of glutamic acid to mushroom solution and Ocimum basilicum L. extract showed that glutamic acid appeared to be an effective browning inhibitor. Glutamic acid showed uncompetitive inhibition for mushroom and Ocimum basilicum L. polyphenol oxidases using 4-methylcatechol as a substrate, for mushroom PPO using catechol as a substrate and for Ocimum basilicum L. polyphenol oxidase using pyrogallol as a substrate; mixed-type inhibition for mushroom polyphenol oxidase using pyrogallol as a substrate; and non-competitive inhibition for Ocimum basilicum L. polyphenol oxidase using catechol as a substrate. Furthermore, sodium azide was used as an inhibitor for comparison with the inhibition potency of glutamic acid. It was found that glutamic acid was a more power inhibitor than sodium azide. The type of inhibition observed depended on the substrate, inhibitor and enzyme source used.     

Crystallization kinetics and affecting parameters on polycaprolactone composites with inorganic and organic additives

The isothermal crystallization and mechanical behavior of biodegradable polycaprolactone (PCL) composites with organic (oleic acid and glycerol monooleate) and inorganic (zinc oxide, organoclay, and hydroxy apatite) additives used alone or simultaneously were investigated. The effect of all additives on the degree of crystallinity percentage (DOC%), isothermal crystallization kinetics parameters, and mechanical test results of PCL composites was studied. The PCL composite films were prepared by solvent casting by using dichloromethane as the solvent. The films were characterized by X‐ray diffraction, differential scanning calorimetry (DSC), and tensile tests. DSC of the first melting and X‐ray diffraction DOC% results (for composites by solvent casting) are compatible. The values by DSC of the second melting (for composites by extrusion method) are lower. Organoclay gives the highest crystallinity among the other inorganic additives used. Small amounts of inorganic additives act as a nucleating agent and increase the crystallinity; the higher amounts decrease. The organic additives act as the plasticizer. When used alone, it lowers the crystallinity, but when used with inorganic additives, it improves the dispersion of inorganic particles in the polymer matrix. The isothermal crystallization kinetics parameters by Avrami analysis showed that crystallization was controlled by nucleation and the crystals had spherical structure. The nucleation type changed between thermal and athermal nucleation. The Pukanzky model interaction parameter B indicated that the organic additives improved the dispersion of inorganic particles in the polymer matrix. Statistically significant, eight correlations (F > 6) were obtained for the crystallinity, crystallization parameters, Young's modulus, and tensile strength as a function of concentration of additives. J. VINYL ADDIT. TECHNOL., 21:174–182, 2015. © 2014 Society of Plastics Engineers     

A cis-directing effect towards diols by an exocyclic P-NHR moiety in cyclotriphosphazenes

Cyclophosphazenes containing the P-NHR moiety in an exocyclic spiro ring, N₃P₃Cl₄[NH(CH₂)₃O], (1), and N₃P₃Cl₄[NH(CH₂)₃NMe], (2), were used to investigate a possible directing effect of the P-NHR moiety on the formation of products in the nucleophilic substitution reactions with diols such as tetraethyleneglycol, 1,3-propanediol and 2,2-dimethyl-1,3-propanediol. The ³¹P NMR spectra of the reaction mixtures showed that only one kind of ansa product is formed in each of these reactions. X-ray crystallographic studies of the ansa products [(4a), (5a), (6a) and (7a)] have provided definitive proof of the cis-directing effect of the P-NHR moiety in cyclotriphosphazenes. It is likely that hydrogen-bond interaction between the incoming nucleophile and the P-NHR moiety of the reactant accounts for the preference for products with the substituents cis to the NH group.     

Inhibition kinetic and mechanism of polyphenol oxidase from various sources by diethyldithiocarbamic acid

Inhibition kinetics and mechanism of polyphenol oxidases (PPO) partially purified from various sources such as Thymbra spicata L. var. spicata and Ocimum basilicum L., and of mushroom PPO bought from Sigma by diethyldithiocarbamic acid have been described using catechol, 4-methylcatechol and pyrogallol as substrates. The inhibition type was competitive for O. basilicum L. PPO using catechol and 4-methylcatechol as substrates, for mushroom PPO using catechol, 4-methylcatechol and pyrogallol as substrates, and for T. spicata L. var. spicata PPO using 4-methylcatechol as a substrate; uncompetitive inhibition for T. spicata L. var. spicata PPO using pyrogallol as a substrate; and non-competitive inhibition for O. basilicum L. and T. spicata L. var. spicata PPO using pyrogallol and catechol as substrates, respectively. The inhibition effect of diethyldithiocarbamic acid on enzymatic browning varied greatly from one phenol to another and from one enzyme to another. Hence, no general rule can easily be established with regard to the type of inhibition observed.     

A neural network approach for prediction of critical submergence of an intake in still water and open channel flow for permeable and impermeable bottom

Free air-core vortex occurring at a water-intake pipe is an important problem encountered in hydraulic engineering. When the submergence of the intake pipe is not sufficient, air enters the pipe and reduction in discharge occurs. The most common solution for avoiding air entrainment is to provide sufficient submergence to the intake. In this study, the critical submergence of intakes is investigated in still water and open channel flow for permeable and impermeable bottom. It is seen that the permeability of the bottom is effective on the critical submergence. The main aim of this study is to develop a suitable model for the critical submergence for intake pipe. Therefore, an artificial neural network (ANN) and multi-linear regression models are used. Results of these experimental studies are compared with those obtained by the ANN and MLR approaches. The ANN model results are found to be in good agreement with the experimental results.