Investigation of Structural,Electronic and Biological Properties of Two Zn(II) Complexes with Pentaaza Macrocyclic Schiff-Base Ligand: A DFT Approach

Two zinc(II) complexes, [ZnL¹Br]⁺ (1), and [ZnL²]²⁺ (2), are optimized by using density functional theory at B3LYP method with mix basis sets which are LANL2DZ/6–31G(d,p) and LANL2TZ+/6–31++G(d,p) basis sets. L¹ and L² are pentadentate macrocyclic Schiff-base ligands containing piperazine moiety. The optimized structures and structural parameters are obtained by using each basis set. IR and UV–VIS spectra of complex (1) and (2) are investigated in detail. NLO properties of Zn(II) complexes are investigated and it is found that NLO properties of complex (2) is better than complex (1). Solvent effects on biological activity are investigated in gas phase, water and chloroform for studied complexes and no solvent effects are monitored for complex (1) and (2). Biological reactivity of complex (1) is higher than that of complex (2).     

Small signal intensity modulation of external cavity lasers with fiber Bragg gratings

The small signal intensity modulation (IM) of a hybrid soliton pulse source (HSPS) utilizing Gaussian apodized fiber Bragg grating (FBG) is described using electric field approach. The HSPS is modeled by a time-domain solution of the coupled-mode equations. It is shown that type of external cavity is important effect on resonance peak spectral splitting (RPSS) in IM response as well as effect of laser and FBG parameters. It is also shown that the RPSS can be suppressed by using linearly chirped Gaussian apodized FBG as an external cavity insted of Gaussian apodized FBG.     

Preparation and characterisation of thiol functionalised p-tert-butylcalix[4]arene-embedded polymer inclusion membranes: performance and selectivity

ABSTRACT

Here in we report the syntheses of the thiol functionalised p-tert-butylcalix[4]arene from the reaction of p-tert-butylcalix[4]arene-dialkylbromide derivative with thiourea. The structure of the thiol functionalised p-tert-butylcalix[4]arene was determined by using ¹HNMR, ¹³CNMR and elemental analysis techniques. Furthermore, the thiol functionalised p-tert-butylcalix[4]arene, cellulose triacetate (CTA) and 2-nitrophenyl octyl ether (o-NPPE) in dichloromethane were used to make a new calixarene-embedded polymer inclusion membrane (Bu^t-C@PIM). The surface and structure morphology of Bu^t-C@PIM was detected using thermogravimetric analysis, elemental analysis techniques and scanning electron microscopy. The affinity (the percentage of metal ion transferred from the source solution) of a PIM towards a range of divalent cations was found to follow the order Pb²⁺ > Zn²⁺ > Ni²⁺ > Cu²⁺ > Cd²⁺ > Co²⁺. The results also indicated that the transport efficiency of Bu^t-C@PIM was repeatable and may be beneficial in the development of a simplistic and highly influential trace metal recovery method from aqueous solution.     

Cytotoxic effects,microbiological analysis and inhibitory properties on carbonic anhydrase isozyme activities of 2-hydroxy-5-methoxyacetophenone thiosemicarbazone and its Cu(II), Co(II), Zn(II) and Mn(II) complexes

Research on Chemical Intermediates - Metal complexes of thiosemicarbazones have been receiving considerable attention in biological applications such as antimicrobial and anticancer therapies. In...     

Optimal Decentralized Regulation for a Class of Flow Networks

Optimal decentralized regulation is considered for a class of flow networks where, at each intersection, a selective switch links a single input–output pair at anytime. It is shown that a special case of the above is an urban traffic network with signalized intersection. We analyze first the traffic situation of an isolated intersection based on the point-queuing model of traffic and model the intersection dynamics via two states: either unsaturated or saturated. According to the different traffic characteristics of the two states, we design two intersection controllers and then combine them into one hybrid controller. This hybrid controller is extended to the multi-intersection case and becomes a decentralized hybrid intersection controller. A simulation study is given in this paper and it shows that this decentralized hybrid intersection control method can improve the performance of traffic networks and by extension the performance of more general flow networks.     

Molecular structure and vibrational spectra of alpha-benzoinoxime by density functional method

In the present study, an exhaustive conformational search of the Alpha-benzoinoxime has been performed. The FT-IR spectrum of this compound was recorded in the region 4000–400 cm^?1. The FT-Raman spectrum was also recorded in the region 3500–50 cm^?1. Vibrational frequences of the title compound were calculated by B3LYP method using 6–311++G(d, p) basis set. The calculated vibrational frequences were analysed and compared with experimental results.     

Part-type selection in flexible manufacturing systems: a bicriteria approach with due dates

We studied the part-type selection problem in a Flexible Manufacturing Environment. We formulated the problem as a bicriteria mathematical programming problem where the objectives are maximisation of a number of part-types selected and minimisation of a measure of total tardiness. Taking the vector optimisation approach, we found all of the efficient solutions to the problem. The efficient set to this problem portrays the trade-off information between the two objectives. We suggest that the Decision Maker should choose one of the efficient solutions for implementation depending on the dynamics of the system. We report computational results that highlight some characteristics of the efficient solutions. We compare the quality of solutions obtained through the bicriteria model with those of a more traditional approach: maximising the weighted sum of part-types selected where the weights are assigned based on due-dates. Our results imply a strong possibility of significant improvement in due date performance by taking a bicriteria approach to the part-type selection problem.     

The gas-sensing potential of nanocrystalline SnO2 produced by a mechanochemical milling via centrifugal action

In this work, the synthesis of undoped nanocrystalline tin dioxide powders and the subsequent preparation of SnO₂ thick-films were studied. An initial mixture of SnCl₂ and Ca(OH)₂ was sealed in a vial for milling in an air atmosphere. Heat treatment of the milled powder resulted in the formation of tetragonal and orthorhombic SnO₂ phases, which was confirmed by X-ray diffraction (XRD) analysis. It was found that crystallite size could be controlled by varying the milling time, the rotation speed and the temperature used for the heat treatment. Crystallite sizes in the range 20 to 30 nm (determined by XRD measurements) were obtained. The total pore volume was 0.22 ml/g for a measured particle size of 37 m²/g. No contamination of the powder during milling was found. The response of the prepared thick-films to H₂S gas in the concentration range 0.5 to 10 ppm in air was investigated as a function of the preparation conditions. The advantage of mechanochemical synthesis of powder is its relative simplicity, low cost and possibility of obtaining isolated, unagglomerated nanosized grains. It is shown that chemical reactions, which usually occur in the vibratory mill to produce the SnO phase, can also be initiated during a short processing time in the centrifugal mill. Received: 25 July 2001 / Accepted: 4 September 2001 / Published online: 20 December 2001     

Dissociation mechanism of a stable intermediate: perfluorohydroxylamine

The mechanism of dissociation of F2NOF has been studied using density-functional (B3LYP, BB1K, and MPWB1K) and wave function methods (CCSD). Variational transition state theory was used to calculate the rate constants for cis-F2NOF --> FNO + F2 (concerted), cis-F2NOF --> F2NO + F, and cis-F2NOF --> trans-F2NOF --> F3NO. Rate constants were also calculated for the dissociation of F2NOF by using transition state theory. The enthalpies of the transitions states (CCSD(T)/cc-pVQZ//B3LYP/6-311+G(d)) were very close to the enthalpy of separated F2NO + F radicals which implies temperature-dependent competition between concerted rearrangement and fragmentation-recombination. The picture is further complicated by the fact that F2NO undergoes fragmentation into FNO + F with a very low barrier. Thus, formation of F3NO, the global minimum on the potential energy surface, can only occur by a concerted process (not from F2NO + F). The data were fit to a temperature-dependent rate in the range 200-1000 K in the form k2 = 8.14 x 10(13) exp(-7860/T) s(-1), k(1) = 6.37 x 10(13) exp(-7855/T) s(-1), and k(10) = 1.42 x 10(12) exp(-7420/T) for cis-F2NOF --> FNO + F2 (concerted), cis-F2NOF --> F2NO + F, and cis-F2NOF --> F3NO, respectively. The calculated lifetime of cis-F2NOF at 298K is 2.5 x 10(-3) s via k1.     

Preparation and Application of Calix[4]arene Derivatives Bearing Pyridinium Units-Grafted Magnetite Nanoparticles for Removal of Dichromate and Arsenate Anions

Diamide derivatives of p-tert-butylcalix[4]arene (3a and 3b) have been immobilized onto [3-(2,3-epoxypropoxy)-propyl]-trimethoxysilane-modified Fe₃O₄ magnetite nanoparticles to obtain D-Calix-GEPPTMS-MNs (4a and 4b) and investigate their sorption capability toward arsenate and dichromate anions at different pH. The novel calixarene derivatives were characterized by a combination of FTIR and H-NMR analyses. The morphology of the magnetic nanoparticles was examined by Transmission Electron Microscopy (TEM) and Thermogravimetric Analyses (TGA). In addition, a simple and versatile method has been used for the determination of arsenate in aqueous solution. In this method, the absorption of the excess dye gradually decreases because of its conversion to colorless carbinol species by combining with methyl violet cation (MV⁺) and forming stable blue micro particles of (MV⁺)-molybdoarsenate.