Carrier‐Mediated Transport of Hg(II) through Bulk and Supported Liquid Membranes

The transport of Hg (II) ions from an aqueous solution into an aqueous receiving solution through bulk and supported liquid membranes containing a calix[4]arene derivative 1 as a carrier was examined. The kinetic parameters of bulk liquid membrane studies were analyzed assuming two consecutive, irreversible first‐order reactions. The influence of temperature, stirring rate, carrier concentration and solvent on the kinetic parameters (k₁, k₂, R_m ^max, t_max, J_d ^max, J_a ^max) has also been investigated. The membrane entrance rate, k₁, and the membrane exit rate, k₂, increased with increasing temperature and stirring rate. The activation energy values are calculated as 4.87 and 48.63 kj mol^?1 for extraction and reextraction, respectively. The values of calculated activation energy indicate that the process is diffusionally controlled by species. Also, the transport behavior of Hg²⁺ from aqueous solution through a flat‐sheet supported liquid membrane has been investigated by the use of calix[4]arene derivative 1 as carrier and Celgard 2500 as the solid support. A Danesi mass transfer model was used to calculate the permeability coefficients for each parameter studied. The highest values of permeability were obtained with 2‐nitrophenyloctyl‐ether (NPOE) solvent and the influence was found to be in the order of NPOE>chloroform>xylene.     

Heavy Metal Removal from Synthetic Solutions with Magnetic Beads Under Magnetic Field

The aim of this study is to prepare magnetic beads which can be used for the removal of heavy metal ions from synthetic solutions. Magnetic poly(ethylene glycol dimethacrylate‐vinyl imidazole) [m‐poly(EGDMA‐VIM)] beads were produced by suspension polymerization in the presence of magnetite Fe₃O₄ nano‐powder. The specific surface area of the m‐poly(EGDMA‐VIM) beads was found to be 63.1 m²/g with a size range of 150–200 µm in diameter and the swelling ratio was 85%. The average Fe₃O₄ content of the resulting m‐poly(EGDMA‐VIM) beads was 12.4%. The maximum binding capacities of the m‐poly(EGDMA‐VIM) beads were 32.4 mg/g for Cu²⁺, 45.8 mg/g for Zn²⁺, 84.2 mg/g for Cd²⁺and 134.5 mg/g for Pb²⁺. The affinity order on mass basis is Pb²⁺>Cd²⁺>Zn²⁺>Cu²⁺. Equilibrium data agreed well with the Langmuir model. pH significantly affected the binding capacity of the magnetic beads. Binding of heavy metal ions from synthetic wastewater was also studied. The binding capacities were 26.2 mg/g for Cu²⁺, 33.7 mg/g for Zn²⁺, 54.7 mg/g for Cd²⁺ and 108.4 mg/g for Pb²⁺. The magnetic beads could be regenerated up to about 97% by treating with 0.1 M HNO₃. These features make m‐poly(EGDMA‐VIM) beads a potential candidate for support of heavy metal removal under magnetic field.     

Electronic structure and related properties for quasi-binary (GaP)1−x (ZnSe) x crystals

The results of pseudopotential calculations of the band structure and related electronic and optical properties of quasi-binary (GaP)_1?x (ZnSe) _x crystals in the zinc blende structure are presented. Trends in bonding and ionicity are discussed in terms of electronic charge densities. Moreover, the composition dependence of the refractive index and dielectric constants are reported. The computed values are in reasonable agreement with experimental data. The results suggest that for a proper choice of the composition x, (GaP)_1?x (ZnSe) _x could provide more diverse opportunities to achieve the desired electronic and optical properties of the crystals which would improve the performances of devices fabricated on them.     

Matching extension in the powers of n-connected graphs

Let G be a graph on p vertices. Then for a positive integer n₁ G is said to be n-extendible if (i) n < p/2, (ii) G has a set of n independent edges, and (iii) every such set is contained in a perfect matching of G. In this paper we will show that if p is even and G is n-connected, then G^k is -extendible for every integer k ≥ 2 such that . © 1996 John Wiley & Sons, Inc.     

Antimicrobial and Antioxidant Properties of Total Polyphenols of Anchusa italica Retz

Anchusa italica Retz has been used for a long time in phytotherapy. The aim of the present study was to determine the antioxidant and antibacterial activities of extracts from the leaves and roots of Anchusa italica Retz. We first determined the content of phenolic compounds and flavonoids using Folin–Ciocalteu reagents and aluminum chloride (AlCl₃). The antioxidant activity was determined using three methods: reducing power (FRAP), 2.2-diphenyl-1-picrylhydrazyl (DPPH), total antioxidant capacity (TAC). The antimicrobial activity was investigated against four strains of Escherichia coli, two strains of Klebsiella pneumoniae and coagulase-negative Staphylococcus, and one fungal strain of Candida albicans. The results showed that the root extract was rich in polyphenols (43.29 mg GAE/g extract), while the leave extract was rich in flavonoids (28.88 mg QE/g extract). The FRAP assay showed a strong iron reduction capacity for the root extract (IC₅₀ of 0.11 µg/mL) in comparison to ascorbic acid (IC₅₀ of 0.121 µg/mL). The DPPH test determined an IC₅₀ of 0.11 µg/mL for the root extract and an IC₅₀ of 0.14 µg/mL for the leaf extract. These values are low compared to those for ascorbic acid (IC₅₀ of 0.16 µg/mL) and BHT (IC₅₀ 0.20 µg/mL). The TAC values of the leaf and root extracts were 0.51 and 0.98 mg AAE/g extract, respectively. In vitro, the extract showed inhibitory activity against all strains studied, with diameters of zones of inhibition in the range of 11.00–16.00 mm for the root extract and 11.67–14.33 mm for the leaf extract. The minimum inhibitory concentration was recorded for the leaf extract against E. coli (ATB:57), corresponding to 5 mg/mL. Overall, this research indicates that the extracts of Anchusa italica Retz roots and leaves exert significant antioxidant and antibacterial activities, probably because of the high content of flavonoids and polyphenols.     

Synthesis and anti-leukaemic activity of pyrrolo[3,2,1-hi]indole-1,2-diones,pyrrolo[3,2,1-ij]quinoline-1,2-diones and other polycyclic isatin derivatives

To further expand the structure–cytotoxic activity relationships of isatin derivatives and to reduce flexibility in substituent groups at nitrogen, 20 analogues incorporating a ring system between the N1 and C7 atoms of isatin were prepared using a variety of synthetic strategies. This yielded pyrroloindole-, pyrroloquinoline-, pyrroloacridine-, pyrrolophenanthridine- and benzopyrrolophenanthridine-based systems with embedded isatin moieties, the latter possessing a novel carbon skeleton. These compounds were subsequently assessed for their in vitro cytotoxicity against human U937 lymphoma cells, with the brominated pyrroloacridine dione 27 showing the most promising activity (IC₅₀ 3.01 μM) after 24 h.     

Investigation of energy and structural changes of Lin (n=3, 4) microclusters based on temperature

The energy and structural changes of lithium microclusters based on temperature has been investigated by using Molecular-Dynamic simulation Method. Two and three-body interacted semi-empiric potential energy formula that characterized the interaction has been used. It has been calculated that the dissociation of atoms from cluster has started after 1300 K for Li₃ and 1350 K for Li₄, respectively. Dissociations at the fixed temperatures are very close to the expected values of the lithium metal. Additionally, it has been observed that Li₄ microclusters above 1000 K and Li₃ clusters above 700 K temperatures have steady structures in two different energy values.     

Calculation of Two-Center Nuclear Attraction Integrals over Integer and Noninteger n-Slater Type Orbitals in Nonlined-Up Coordinate Systems

Two-center nuclear attraction integrals over Slater type orbitals with integer and noninteger principal quantum numbers in nonlined up coordinate systems have been calculated by means of formulas in our previous work (T. Özdoan and M. Orbay, Int. J. Quant. Chem. 87 (2002) 15). The computer results for integer case are in best agreement with the prior literature. On the other hand, the results for noninteger case are not compared with the literature due to the scarcity of the literature, but also compared with the limit of integer case and good agreements are obtained. The proposed algorithm for the calculation of two-center nuclear attraction integrals over Slater type orbitals with noninteger principal quantum numbers in nonlined-up coordinate systems permits to avoid the interpolation procedure used to overcome the difficulty introduced by the presence of noninteger principal quantum numbers. Finally, numerical aspects of the presented formulae are analyzed under wide range of quantum numbers, orbital exponents and internuclear distances.     

Symmetries,Conservation Laws and Multipliers via Partial Lagrangians and Noether’s Theorem for Classically Non-Variational Problems

We show how one can construct conservation laws of equations that are not variational but are Euler–Lagrange in part using Noether-type symmetries associated with partial Lagrangians. These Noether-type symmetries are, usually, not symmetries of the system. The resultant construction of the conservation law resorts to a formula equivalent to Noether’s theorem. A variety of examples are given.