Solid phase extractive preconcentration of trace metals using p-tert-butylcalix[4]arene-1,2-crown-4-anchored chloromethylated polymeric resin beads

5,11,17,23-Tetrakis(1,1-dimethylethyl)-25,26-dihydroxy-27,28-crown-4-calix[4]arene in the cone conformation was synthesized. This p-tert-butylcalix[4]arene-1,2-crown-4 compound was then anchored with Merrifield chloromethylated resin beads. The modified polymeric resin was characterized by ¹H NMR, FT-IR and elemental analysis and used successfully for the separation and preconcentration of Cu(II), Cd(II), Co(II), Ni(II) and Zn(II) prior to their determination by FAAS. Effective extraction conditions were optimized in both batch and column methods. The resin exhibits good separating ability with maximum between pH 6.0-7.0 for Cu(II), pH 6.0 for Cd(II), pH 5.0 for Co(II), pH 4.0-4.5 for Ni(II), and pH 4.5 for Zn(II). The elution studies were carried out with 0.5 mol L⁻¹ HCl for Cu(II), Co(II) and Co(II), 1.0 mol L⁻¹ HCl for Cd(II) and Zn(II). The sorption capacity, preconcentration factor and distribution coefficient of each metal ion were determined. The detection limits were 1.10, 1.25, 1.83, 1.68 and 2.01 μg L⁻¹ for Cu(II), Cd(II), Co(II), Ni(II) and Zn(II). The influence of several ions on the resin performance was also investigated. The validity of the proposed method was checked for these metal ions in NIST standard reference material 2709 (San Joaquin Soil) and 2711 (Montana Soil).     

In vitro bioactivity and crystallization behavior of bioactive glass in the system SiO2-CaO-Al2O3-P2O5-Na2O-MgO-CaF2

In this study, bioactivity of glass in the system SiO₂-CaO-Al₂O₃-P₂O₅-Na₂O-MgO-CaF₂ was investigated. For this purpose, a glass sample was prepared by the traditional melting method. Crystallization behavior of bioactive glass was also investigated using differential thermal analyses. The Avrami constant of bioactive glass sample calculated according to the Ozawa equation was 3.72 ± 0.4, which indicates bulk crystallization. Using the Matusita-Sakka and the Kissinger equations, activation energy of crystal growth was determined as (394 ± 17) kJ mol⁻¹ and (373 ± 12) kJ mol⁻¹, respectively. These results indicate that the crystallization activation energy data of bioactive glass obtained in this study are accurate and reliable. Bioactivity of the resultant glass sample was analyzed by immersion in simulated body fluid. Scanning electron microscopy, thin film X-ray diffraction, ultraviolet spectroscopy and inductively coupled plasma techniques were used to monitor changes in the glass surface and the simulated body fluid composition. The results revealed that a hydroxyapatite layer was formed on the glass surface after 21 days of immersion in SBF. Formation of the hydroxyapatite layer confirmed the bioactivity of the glass in the system SiO₂-CaO-Al₂O₃-P₂O₅-Na₂O-MgO-CaF₂. In addition, physical and mechanical properties of the sample were measured to determine changes in the properties with the immersion time. The results show that bioactive glass maintained its strength during the immersion in a simulated body fluid solution.     

Control of specific attachment of proteins by adsorption of polymer layers

This study concerns the design of protein-resistant polymer adsorbed layers for the control of surface binding of biospecific recognition entities. Polymer surface layers were prepared using the adsorption of poly(allylamine hydrochloride) (PAH), poly(l-lysine) (PL), and branched and linear polyethyleneimine (PEI) and further modified by the covalent attachment of biotin for specific avidin attachment. The adsorption of PAH, PL, and PEI on silicon substrates was studied as a function of pH and ionic strength using ellipsometry. Average dry layer thicknesses of approximately 10, approximately 5, approximately 9, and approximately 3 A (+/-1 A) were obtained when polymer adsorption occurred from solutions at pH 9.5 that contained 0.5 M NaCl for PAH, PL, branched PEI, and linear PEI, respectively. These polymers showed significant differences in their efficiency to suppress nonspecific avidin adsorption. At low ionic strength, avidin adsorption occurred on all polymer-coated surfaces at basic pH values, despite the same positive electrostatic charge for protein globules and the surface. Though the net electrostatic repulsion between avidin molecules and branched PEI was efficiently screened in a protein solution of pH 7 and 0.15 M NaCl, branched-PEI coatings of high molecular weight were unique in their ability to provide avidin-resistant surfaces as a result of steric hindrance from the branched architecture of adsorbed polymer chains. All polymers studied were effective in suppressing avidin adsorption at pH 3 as a result of protonation of the avidin surface functional groups at this pH. Branched-PEI-coated surfaces were also effective for the suppression of smaller positively charged proteins such as lysozyme and ribonuclease A at pH 7 and 0.15 M NaCl. They were also resistant to the adsorption of negatively charged proteins such as BSA and fibrinogen at pH 7 and 0.75 M NaCl. Furthermore, by using PEI-modified protein-repellent surfaces, selective binding of avidin was achieved to surface-bound silver nanoparticles, which should provide a promising application for the label-free detection of biological species using surface-enhanced Raman scattering (SERS).     

Absorption and fluorescence properties of aryl substituted porphyrins in different media

Absorption and fluorescence properties of aryl substituted porphyrins, 5,10,15,20-tetra-4-oxy(aceticacid)phenylporphyrin (TAPP), 5,10,15,20-tetra-(4-phenoxyphenyl) porphyrin (TPPP), 5,10,15,20-tetra-(3-bromo-4-hydroxyphenyl) porphyrin (TBHPP), and 5,10,15,20-tetra-p-chloromethylphenyl porphyrin (CMPP) were investigated. The UV/vis absorption, fluorescence and excited spectra as the fluorescence quantum yields and fluorescence lifetimes for the compounds were measured in organic solvents (chloroform (CHCl₃), tetrahydrofuran (THF)) and immobilized media (PVC film, sol–gel matrix). The fluorescence quantum yields of TAPP and TPPP were higher than the others. The fluorescence lifetimes of all studied porphyrin derivates were found to be fifty percent lower and their fluorescence intensities were increased fifty percent more in both of immobilized mediums, as compared to organic solvents.     

Salicylate Ion‐Selective Electrode Based on a Calix[4]arene as Ionophore

A salicylate‐selective electrode based on calix[4]arene derivative was developed and its response characteristics were investigated. The optimum membrane composition was 1 % ionophore, 30 % PVC, 69 % DOS. The electrode exhibited a Nernstian slope of 58.8±0.5 mV/pSal in the range of 1.0×10^?5–1.0×10^?1 M with a detection limit of 4.3×10^?6 M at pH 4.0, 20±1 °C. The potentiometric response of the electrode in the presence of different anions was investigated by the separate solution method. The lifetime was found at least 4 months, and its response time was 5–10 s. It was successfully used for the potentiometric determination of salicylate in pharmaceutical preparations.     

Hydrogen bonding networks and proton transfer compounds of cobalt(II) and copper(II) with pyridine-2,5-dicarboxylate

Three Co(II) and Cu(II)-pyridine-2,5-dicarboxylate (pydc) proton transfer compounds with 1,4-butanediamine (ben) and 2,2-dimethylpropane-1,3-diamine (dmpen), trans-(H₂ben)[Co(pydc)₂(H₂O)₂]·4H₂O (1), trans-(H₂dmpen)[Co(pydc)₂(H₂O)₂]·2H₂O (2) and (H₂ben)₂[Cu₂(μ-pydc)₄(H₂O)₂] (3) have been synthesized and characterized by the methods of elemental, spectroscopic (IR and UV-Vis), thermal (TG/DTG, DTA) analysis, magnetic measurement and single crystal X-ray diffraction. The crystallographic analysis revealed that the complexes consist of [Co(pydc)₂(H₂O)₂]²⁻ anion, bis(protonated) diamine cation (H₂ben for 1 and H₂dmpen for 2) and four and two crystal water molecules, respectively. The Co(II) ions are coordinated by two pydc and two aqua ligands. The bis(deprotonated) pydc ligands coordinate to the Co(II) ions through the nitrogen atom of pyridine ring and the oxygen atom of carboxylate group, creating a chelate ring. The distorted octahedral geometries are completed by two trans aqua ligands at axial positions. The molecular structure of the complex 3 consists of dinuclear [Cu₂(μ-pydc)₄(H₂O)₂]⁴⁻ units and bis(protonated) 1,4-butanediammonium cation. In the structure, each Cu(II) ion is coordinated by two nitrogen and two oxygen atoms from two pydc ligands and one oxygen atom from aqua ligand, forming a distorted square pyramidal geometry.     

Sorption of uranium using silica gel with benzoylthiourea derivatives

Benzoylthiourea derivatives (N,N-diphenyl-N′-(3-methylbenzoyl)thiourea and diphenyl-N′-(4-methylbenzoyl)thiourea) were impregnated onto silica gel. The preconcentration of uranium(VI) from aqueous solution was investigated. Extraction conditions were optimized in batch method prior to determination by uv–visible absorption spectrometry using arsenazo(III). The optimum pH for quantitative adsorption was found as 3–7. Quantitative recovery of uranium (VI) was achieved by stripping with 0.1 mol L^?1 HCl. Equilibration time was determined as 30 min for 99% sorption of U(VI). Under optimal conditions, dynamic linear range of for U(VI) was found as 0.25–10 μg mL^?1. The relative standard deviation as percentage and detection limit were 5.0% (n = 10) for 10 μg mL^?1 U(VI) solution and 8.7 ng mL^?1, respectively. The method was employed to the preconcentration of U(VI) ions in soil and tap water samples.     

An improved solution for diffusion waves to overland flow

Diffusion wave equation describes the flood wave propagation which is used in solving overland and open channel flow problems. Therefore, it is important to understand and solve the diffusion wave equations accurately. For this purpose, researchers have previously developed several analytical and numerical methods for the solution of the partial differential equation of diffusion waves. The solution derived by Kazezy?lmaz-Alhan and Medina (2007) [12] can be used to solve overland flow problems during rainfall events with both constant and variable rainfall intensity, and with constant hydraulic diffusivity and wave celerity. In this paper, this method is improved by employing the De Hoog algorithm instead of Stehfest algorithm for Laplace inversion and adapting the solution to variable hydraulic diffusivity and wave celerity. In addition, the performances of the Stehfest and the De Hoog algorithms are compared. Synthetic examples are solved by using both Stehfest and De Hoog algorithms incorporated into the existing analytical solution to present the accuracy of the De Hoog algorithm over the Stehfest algorithm. The examples are also solved by using the new method in order to demonstrate the improvement over the existing method.     

Improving the appearance of all textile products from clothing to home textile using laser technology

Denim trousers, commonly known as “blue jeans”, have maintained their popularity for many years. For the purpose of supporting customers’ purchasing behaviour and to address their aesthetic taste, companies have been trying in recent years to develop various techniques to improve the visual aspects of denim fabrics. These techniques mainly include printing on fabrics, embroidery and washing the final product. Especially, fraying certain areas of the fabric by sanding and stone washing to create designs is a popular technique. However, due to certain inconveniences caused by these procedures and in response to growing demands, research is underway to obtain a similar appearance by creating better quality and more advantageous manufacturing conditions.

As is known, the laser is a source of energy which can be directed on desired objects and whose power and intensity can be easily controlled. Use of the laser enables us to cut a great variety of material from metal to fabric. Starting off from this point, we thought it would be possible to transfer certain designs onto the surface of textile material by changing the dye molecules in the fabric and creating alterations in its colour quality values by directing the laser to the material at reduced intensity.

This study mainly deals with a machine specially designed for making use of laser beams to transfer pictures, figures as well as graphics of desired variety, size and intensity on all kinds of surfaces in textile manufacturing such as knitted—woven fabrics, leather, etc. at desired precision and without damaging the texture of the material.

In the designed system, computer-controlled laser beams are used to change the colour of the dye material on the textile surface by directing the laser beams at a desired wavelength and intensity onto various textile surfaces selected for application. For this purpose, a laser beam source that can reach the initial level of power and that can be controlled by means of a computer interface; reflecting mirrors that can direct this beam at two axes; a galvanometer which comprised of an optical aperture; and a computer program that can transfer images obtained in standard formats to the galvanometer control card were used.

Developing new designs by using the computer and transferring the designs that are obtained on textile surfaces will not only increase and facilitate the production in a more practical manner, but also help you to create identical designs. This means serial manufacturing of the products at a standard quality and increasing their added values. Moreover, creating textile designs using laser will also contribute to the value of the product as far as the consumer is concerned because it will not cause any wearing off and deformation in the texture of the fabric unlike the sanding and stoning processes.

Another advantage of this system is that it gives a richer look to the product by causing the textile surfaces to get wrinkled and become three-dimensional by deformation as well as enabling you to create pictures and patterns on leather and synthetic fabrics by means of heat.

As for the results of the study, the first step was to prepare 40 pairs of denim trousers, half of which were prepared manually and the other half by using laser beam. Time studies were made at every step of the production. So as to determine the abrasion degrees of the trousers in design applications, tensile strength as well as tensile extension tests were conducted for all the trousers.