Asymptotic integration of second-order impulsive differential equations

We initiate a study of the asymptotic integration problem for second-order nonlinear impulsive differential equations. It is shown that there exist solutions asymptotic to solutions of an associated linear homogeneous impulsive differential equation as in the case for equations without impulse effects. We introduce a new constructive method that can easily be applied to similar problems. An illustrative example is also given

Dye-affinity hollow-fibres and their lysozyme adsorption-desorption characteristics

Akgol, Sinan/0000-0002-8528-1854; AKGOL, Sinan/0000-0003-2836-7181WOS: 000171435700013Dye-affinity adsorption is increasingly used for protein separation. Hollow-fibres have advantages as adsorbents in comparison to conventional bead supports because they are not compressible and can eliminate internal diffusion limitations. The aim of this study was to explore in detail the performance of polyamide hollow-fibres to which Reactive Green HE-4BD was attached for adsorption of lysozyme. The hollow-fibre was characterized by scanning electron microscopy. These dye-carrying hollow-fibres (26.3 mu mol g(-1)) were used in the lysozyme adsorption-elution studies. The effect of initial concentration of lysozyme and medium pH on the adsorption efficiency of dye-attached hollow-fibres was studied in a batch system. The non-specific adsorption of lysozyme on the polyamide hollow-fibres was 1.8 mgg(-1). Reactive Green HE-4BD attachment significantly increased the lysozyme adsorption up to 41.1 mgg(-1). Langmuir adsorption model was found to be applicable in interpreting lead adsorption by Reactive Green HE-4BD attached hollow fibres. Significant amount of the adsorbed lysozyme (up to 95%) was eluted in lh in the elution medium containing 1.0M NaSCN at pH 8.0. In order to determine the effects of adsorption conditions on possible conformational changes of lysozyme structure, fluorescence spectrophotometry was employed. We concluded that polyamide dye-affinity hollow-fibres can be applied for lysozyme adsorption without causing any significant conformational changes. Repeated adsorption-elution processes showed that these dye-attached hollow-fibres are suitable for lysozyme adsorption. (C) 2001 Society of Chemical Industry

Concanavalin a immobilized affinity adsorbents for reversible use in yeast invertase adsorption

Akgol, Sinan/0000-0002-8528-1854; AKGOL, Sinan/0000-0003-2836-7181WOS: 000222909600006PubMed: 15468261Concanavalin A (Con A) immobilized poly(2-hydroxyethyl methacrylate) (PHEMA) beads were investigated for specific adsorption of yeast invertase from aqueous solutions. PHEMA beads were prepared by a suspension polymerization technique with an average size of 150-200 mum, and activated by epichlorohydrin. Con A was then immobilized by covalent binding onto these beads. The maximum Con A immobilization was found to be 10 mg/g. The invertase-loading capability of the PHEMA/Con A beads was observed at pH 5.0. The values of the Michaelis constant K-m of invertase were significanly larger upon adsorption, indicating decreased smaller for the adsorbed invertase. Adsorption improved the pH stability of the enzyme activity was found to be quite stable in repeated experiments

Removal of Acid Black 210 Dye from Leather Dyeing Effluent using Spherical Particles of P(HEMA-GMA)IDA-Cr(III) Hydrogel Membrane

WOS: 000406171400005Hydrogel membranes can swell by a high proportion of their weight and have a large surface area, and are nowadays preferred in adsorption studies. In this work, p(HEMA-GMA) poly(hydroxyethyl methacrylate-co-glycidyl methacrylate) spherical particulated hydrogel membrane (SPM) was produced by UV photopolymerization and the synthesized membrane was coupled with iminodiacetic acid (IDA) in order to bond the Cr(III) ions in the chrome tanning process effluent. Then p(HEMA-GMA)-IDA-Cr(III) SPM was used to remove Acid Black 210 dye from the dyeing process effluent. The membrane's chrome and dye adsorption capacities were determined using a UV/Vis Spectrophotometer at wavelengths of 601nm and 435nm respectively. After the membranes were used, the discharged tanning and dye process wastewaters were examined in order to see the differences in the wastewater in terms of COD, BOD5, conductivity, pH, salinity, total dissolved solids, total suspended solids, potassium, total nitrogen and chromium content. The results showed that the metal-chelated p(HEMA-GMA)-IDA SPMs chelated chrome ions between 398.47 and 619.10mg/g, and the adsorbed Acid Black 210 dye molecules were between 0.76 and 1.87mg/g. In conclusion, p(HEMA-GMA)-IDA SPM is an effective sorbent system for removing Cr(III) ions and acid dye molecules from leather discharge waters.Scientific and Technological Research Council of TurkeyTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [115Y310, 2211-C]This study was financially supported by the Scientific and Technological Research Council of Turkey (Project Number: 115Y310), the Scientific and Technological Research Council of Turkey (2211-C Doctorate Scholarship Program)

Phe-graft-poly(Hema) polymeric nanoparticle: A promising tool to design new agrochemicals

###EgeUn###In this study, L-phenylalanine grafted 2-hydroxyethyl methacrylate (Phe-graft-Poly(HEMA))polymericnanoparticles(PNPs)weresynthesizedandtheir using potential for agricultural purposes was evaluated through the assessment ofthe PNPs characterization and phytotoxicityon wheat(Triticum aestivum L. cv. Gonen). Characterization of Phe-graft-Poly(HEMA) PNPs was carried out by FT-IR spectroscopy, Zeta-Size analysis and SEM. FT-IR analysis showed L-phenylalanine amino acids incorporation into poly(HEMA) nanoparticles and theparticlesizewasmeasuredabout168nmbyZeta-Sizeanalysis. SEMimages showed spherical shape and narrow distribution of the PNPs. Surface area of the PNP was calculated to be 2723 m 2 g -1 . The phytotoxicity of the PNPs on wheat was explored in seed germination and seedling stage. Treated seedlings maintained high germination rate, fresh-dry weights and shoot-root lengths in early growth period. Leaves of 14-days-old wheat seedlings did not present any decrement on photosynthetic efficiency (Fv/Fm) and pigment contents in comparison to control. Hydrogen peroxide and reactive oxygen species (ROS) induced lipid peroxidation levels were measured similar to control level. These results show that Phe-graft-Poly(HEMA)PNPs may be used as non-phytotoxic hydrophobic carrier system to design unique nanoagrochemicals for different agricultural purposes. © 2019, Academic Publishing House. All rights reserved

Eggplant tissue homogenate-based bioselective membrane electrode for determination of catechol

WOS: 000080818900005PubMed ID: 10549158A novel eggplant tissue homogenate-based membrane electrode with high selective response to catechol (5x10(-6)-2.5x10(-5) M concentration) has been constructed by immobilizing tissue of eggplant (Solanum melangena L.) at dissolved oxygen probe. In order to optimize the stability of the electrode, general immobilization techniques are used to secure the eggplant tissue section physically in a gelatin-glutaraldehyde cross-linking matrix. The electrode response was maximum when 50 mM phosphate buffer was used at pH 7.0 and 35 degrees C. The sensor is stable for more than 3 months