Synthesis of antibacterial amphiphilic elastomer based on polystyrene-block-polyisoprene-block-polystyrene via thiol-ene addition

A new type of amphiphilic antibacterial elastomer has been described. Thermoplastic elastomer, polystyrene–block-polyisoprene–block-polystyrene (PS–b-PI–b-PS) triblock copolymer was functionalized in toluene solution by free radical mercaptan addition in order to obtain an amphiphilic antibacterial elastomer. Thiol terminated PEG was grafted through the double bonds of PS–b-PI–b-PS via free radical thiol-ene coupling reaction. The antibacterial properties of the amphiphilic graft copolymers were observed. The original and the modified polymers were used to create microfibers in an electro-spinning process. Topology of the electrospun micro/nanofibers were studied by using scanning electron microscopy (SEM). The chemical structures of the amphiphilic comb type graft copolymers were elucidated by the combination of elemental analysis, ¹H NMR, ¹³C NMR, GPC and FTIR.     

Separation of gold(III) ions from copper(II) and zinc(II) ions using thiourea–formaldehyde or urea–formaldehyde chelating resins

Thiourea–formaldehyde (TF) and urea–formaldehyde (UF) chelating resins were synthesized and these resins were used in the separation of gold(III) ions from copper(II) and zinc(II) base metal ions. In the experimental studies, the effect of acidity on gold(III) uptake and gold(III) adsorption capacities by batch method, and loading and elution profiles of gold(III) ions, gold(III), copper(II), and zinc(II), dynamic adsorption capacities and the stability tests of TF and UF resins by column method were examined. By batch method, the optimum acidities were found as pH 2 and 0.5M HCl, and gold(III) adsorption capacities in the solutions including copper(II) and zinc(II) ions were obtained as 0.088 and 0.151 meq Au(III)/g for UF and TF resins, respectively. On the other hand, by column method, the dynamic adsorption capacities were calculated as 0.109 meq Au(III)/g with TF, 0.023 meq Au(III)/g with UF, 0.015 meq Cu(II)/g with TF, 0.0057 meq Cu(II)/g with UF, and under 6.1 × 10^?5 meq Zn(II)/g with TF or UF. TF resin was more effective in the separation and the concentration of gold(III) ions from copper(II) and zinc(II) ions than UF resin. It was seen that sulfur atoms contributed the gold(III) adsorption comparing with oxygen atoms. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

The microwave-assisted synthesis and characterization of novel metal-free and metallophthalocyanines peripherally fused to four 13-membered diazadithia macrocycles

The novel tetrasubstituted metal-free phthalocyanine and metallophthalocyanines 7, bearing four 13-membered diazadithia macrocycle moieties at peripheral positions were synthesized by cyclotetramerization of the corresponding phthalonitrile derivative in a multi-step reaction sequence. The metal-free phthalocyanine was synthesized by microwave irradiation of the corresponding dicyano compound in 2-(dimethylamino)ethanol for 10 min. Metallophthalocyanines were obtained from the respective dicyano derivative and corresponding anhydrous metal salts NiCl₂ and ZnCl₂, CoCl₂, CuCl₂, respectively, by microwave irradiation in 2-(dimethylamino)ethanol at 175 °C, 350 W for 10 min. The new compounds were characterized by a combination of IR, ¹H NMR, ¹³C NMR, UV–vis, elemental analysis and MS spectral data.     

Zinc oxide nanowire enhanced multifunctional coatings for cotton fabrics

Zinc oxide (ZnO) nanowires have been grown on cotton fabric to impart self-cleaning, superhydrophobicity and ultraviolet (UV) blocking properties. ZnO nanowires were grown by the microwave assisted hydrothermal method and subsequently functionalized with steraic acid to obtain a water contact angle of 150°, showing their superhydrophobic nature which is found to be stable up to 4 washings. UV protection of the resulting cotton fabric was also examined and significant decrease in the transmission of UV range was observed. Self-cleaning activity of the ZnO nanowire coated cotton fabric was also studied and it showed considerable degradation of methylene blue under UV light irradiation. These results suggest that ZnO nanowires could form ideal multifunctional coatings for textiles.     

Time-parallel simulation of wireless ad hoc networks

In this paper, we study time-parallel simulation of wireless networks based upon the concept of the perturbation induced by a networking event and present a layer-by-layer analysis of the impact of perturbations on the wireless network. This analysis allows us to propose several methods to improve the accuracy of time-parallel simulation. We describe an implementation based on the widely used ns-2 simulator and on the iterative extension of the warmup period. We introduce a method for initial state approximation which can improve the accuracy of the simulation for table-driven ad hoc routing protocols. A series of experiments show that on typical scenarios time-parallel simulation leads to a significant speedup while maintaining a high level of accuracy.     

Mechanical and Thermal Properties of 3D-Printed Biocomposites of Polylactic Acid and Thermally Modified Wood Flour with Silver Nanoparticles

This study investigates the effects of thermal treatment and silver nanoparticles on the mechanical and thermal properties of additively manufactured wood/polylactic acid (PLA) specimens. The 5 and 10 wt% additions of the wood flour into the PLA matrix are done in the twin screw extruder. The test specimens are produced from the filaments with a diameter of 1.75 mm using 3D printer. The mechanical properties of the 3D-printed wood/PLA specimens are affected by the wood flour content, thermal treatment of wood, and silver nanoparticles. The 3D-printed neat PLA specimens have better mechanical properties than the wood flour-filled PLA specimens. The bending strength of the specimens enhances with increasing wood flour content while the tensile strength decreases. The increases in the mechanical properties reveal that the thermal treatment of the wood improves the compatibility between wood and PLA matrix, which hereby improves the interfacial adhesion. The addition of the silver nanoparticles positively affects the mechanical properties and it is more compatible with thermally modified wood particles as compared to the untreated wood particles.     

Reduction of methomyl and acetamiprid residues from tomatoes after various household washing solutions

The removal of pesticide residues is essential in order to control and reduce the harmful effects of pesticides commonly used in agriculture. The aim of this study was to investigate the effectiveness of 18 different household washing solutions for the reduction of methomyl and acetamiprid residues from tomatoes. These basic household solutions were used to prepare washing solution to remove pesticides. During this study, tomatoes were divided into two groups: in the first group, tomatoes were treated with the pesticides and the second group was washed with household solutions (distilled water, acetic acid, sodium chloride, ethanol, sodium bicarbonate, hydrogen peroxide, sodium hypochlorite, and liquid soap, lemon juice, mineral water, zam-zam water, whey, milk, and their combinations) after treating with pesticides. The pesticides residues in all samples were extracted by the QuEChERS technique, analyzed by LC-MS/MS. The results showed significant reduction in residues of all washed groups compared with the control (p < 0.01). Acetic acid, sodium chloride+sodium bicarbonate, zam-zam water, acetic acid+sodium chloride, sodium hypochlorite, milk, acetic acid+sodium chloride+sodium bicarbonate, liquid whey, liquid soap, lemon juice, ethanol, and sodium bicarbonate were found to remove more than 50% of both pesticide residues. The effectiveness of washing solutions was different for every type of pesticide. In the same way, blend of washing solutions has shown a synergetic effect on the removal of pesticides and was more effective compared to one solution. This research has raised the potential use of household solutions easily found at home that could be used to remove pesticide residues.     

Controlling phosphonic acid substitution degree on proton conducting polyphosphazenes

This paper is to describe the development of a synthetic strategy for the preparation of phosphonic acid functionalized poly(aryloxyphosphazene) membranes with different substitution degree of phosphonic acid. Synthesized polymers have been characterized by standard spectroscopic techniques; FT-IR, ¹H, ³¹P and ¹⁹F NMR and element analysis. Proton conductivities of phosphonic acid substituted polymers have been investigated with impedance spectroscopy at different temperatures. Furthermore, the correlations of the proton conductivity and ion exchange capacity with the substitution degree of phosphonic acid have also been investigated. Thermal properties and water uptake properties of the polymers are also investigated. It is found that the proton conductivity and initial decomposition temperature of the polymers increases up to an appropriate amount of phosphonic acid substitution degree, which can be a useful PEM candidate for fuel cells.