Redox and antimicrobial studies of transition metal(II) tetradentate Schiff base complexes

Neutral tetradentate chelate complexes of Cu^II, Ni^II, Co^II, Mn^II, Zn^II and VO^II have been prepared in EtOH using Schiff bases derived from acetoacetanilido-4-aminoantipyrine and 2-aminophenol/2-aminothiophenol. Microanalytical data, magnetic susceptibility, i.r., u.v.–vis., ¹H-n.m.r. and e.s.r. spectral techniques were used to confirm the structures of the chelates. Electronic absorption and i.r. spectra of the complexes suggest a square-planar geometry around the central metal ion, except for VO^II and Mn^II complexes which have square-pyramidal and octahedral geometry respectively. The cyclic voltammetric data for the Cu^II complexes in MeCN show two waves for copper(II) copper(III) and copper(II) copper(I) couples, whereas the VO^II complexes in MeCN show two waves for vanadium(IV) vanadium(V) and vanadium(IV) vanadium(III) couples. The e.s.r. spectra of the Cu^II, VO^II and Mn^II complexes were recorded in DMSO solution and their salient features reported. The in vitro antimicrobial activity of the investigated compounds was tested against the microorganisms such as Salmonella typhi, Staphylococcus aureus, Klebsiella pneumoniae, Bacillus subtilis, Shigella flexneri, Pseudomonas aeruginosa, Aspergillus niger and Rhizoctonia bataicola. Most of the metal chelates have higher antimicrobial activity than the free ligands.     

Copper(II) complex of 3-cinnamalideneacetylacetone: Synthesis and characterisation

A bidentate ligand derived from cinnamaldehyde and acetylacetone and its copper(II) complex have been synthesized and characterized by elemental analysis, UV-Vis, IR, ESR and magnetic susceptibility measurements. Magnetic susceptibility measurements, ESR and electronic spectral data indicate the presence of six coordinated Cu(II) ion. The ligand and complex are tested for antibacterial activity againstPseudomonas aeroginosa. They are found to show the antibacterial activity.     

Pressure sensitive paint demonstrates relationship between ejector wall pressure and aerodynamic performance

 This paper provides an example of the application of Pressure Sensitive Paint (PSP) to complex internal suspersonic flows and demonstrates the relationship between ejector wall pressure and aerodynamic performance. Details of such jet mixer-ejector nozzles are relevant to jet noise reduction programs. Several ejector configurations with straight, convergent, and divergent side walls were used in our experiments. The side-wall that was painted with PSP was also instrumented with an array of 156 pressure taps connected to Electronically Scanned Pressure (ESP) modules, enabling simultaneous measurement of “true” reference pressures. The PSP results agreed very well with the “true” reference pressures and also provided a detailed map of the complicated pressure patterns that could not be detected using the pressure taps. Finally, we also demonstrated the direct relationship between ejector side-wall pressure distribution and ejector performance characteristics such as exit mean flow uniformity, pumping, and thrust augmentation. Received: 16 December 1997/Accepted: 21 August 1998     

Product line selection and pricing analysis: Impact of genetic relaxations

A model for the product line selection and pricing problem (PLSP) is presented andthree solution procedures based on a genetic algorithm are developed to analyze the results based on consumer preference patterns. Since the PLSP model is nonlinear and integer, two of the solution procedures use genetic encoding to “relax” the NP hard model. The relaxations result in linear integer and shortest path models for the fitness evaluation which are solved using branch and bound and labeling algorithms, respectively. Performance of the quality of solutions generated by the procedures is evaluated for various problem sizes and customer preference structures. The results show that the genetic relaxations provide efficient and effective solution methodologies for the problem, when compared to the pure artificial intelligence technique of genetic search. The impact of the preference structure on the product line and the managerial implications of the solution characteristics generated by the genetic relaxations are also discussed. The models can be used to explicitly consider tradeoffs between marketing and operations concerns in designing a product line.     

Metal‐based antitumor,cytotoxic and antimicrobial activity: pharmacological evaluation of Knoevenagel condensate β‐diketone Schiff base thiosemicarbazone Cu(II) and Zn(II) complexes

Knoevenagel condensate Schiff base ligands [L = 3‐cinnamalideneacetylacetone‐thiosemicarbazone (CAT)/3‐cinnama‐ lideneacetylacetoneethylthiosemicarbazone (CAET)/3‐cinnamalideneacetylacetonephenylthiosemicarbazone (CAPT)] and their copper/zinc complexes were synthesized. They were characterized by analytical and spectral techniques. From these data it was found that the ligands adopt square‐planar geometry on metalation with Cu²⁺ and Zn²⁺. To evaluate the antitumor and cytotoxic activity of the synthesized complexes in mice and human cancer cell lines, the antitumor activity of the complexes was evaluated against an Ehrlich ascites carcinoma (EAC) tumor model. The activity was assessed using survival time and short‐term in vitro cytotoxic activity. Oral administration of complexes (100 mg/kg) increased the survival time. The cytotoxic activity of complexes was evaluated using human breast cancer (MDA‐MB‐231), colon cancer (HCT‐116) and nonsmall lung cancer (NCI‐H‐23) cell lines. Both the complexes possessed significant antitumor and cytotoxic activity on EAC and human cancer cell lines. The in vitro antimicrobial screening effect of the investigated compounds was also tested against the various organisms by well diffusion method. Copyright © 2009 John Wiley & Sons, Ltd.     

Synthesis,DNA binding,and antimicrobial studies of novel metal complexes containing a pyrazolone derivative Schiff base

A novel series of Co(II), Ni(II), Cu(II), Zn(II), and VO(IV) complexes has been synthesized from the Schiff base derived from 4-[(3,4-dimethoxybenzylidene)amino]-1,5-dimethyl-2-phenyl-1,2-dihydropyrazol-3-one and 1,2-diaminobenzene. Structural features were determined by analytical and spectral techniques. Binding of synthesized complexes with calf thymus DNA (CT DNA) was studied by spectroscopic methods and viscosity measurements. Experimental results indicate that the complexes are able to form adducts with DNA and to distort the double helix by changing the base stacking. Lower DNA affinity of the VO(IV) complex is caused by the change of coordination geometry by the vanadyl ion resulting in a somewhat unfavorable configuration for the DNA binding. Oxidative DNA cleavage activities of the complexes were studied with supercoiled (SC) pUC19 DNA using gel electrophoresis; the mechanism studies revealed that the hydroxyl radical is likely to be the reactive species responsible for the cleavage of pUC19 DNA by the synthesized complexes. The in vitro antimicrobial screening effects of the investigated compounds were monitored by the disc diffusion method. The synthesized Schiff base complexes exhibit higher antimicrobial activity than the respective free Schiff base.     

Preparation of electrodeless discharge lamps for emission studies of uranium isotopes at trace level

A simplified method for preparation of electrodeless discharge lamp for uranium isotopes with specific concerns for ²³²U is described. Micro-gram quantities of solid uranium oxides and aqueous solution of uranium nitrate have been used as a starting material for in situ synthesis of uranium tetraiodide. High temperature iodination reaction is carried out in the presence of inert gas neon. By careful design, the preparation time and surface area of quartz reaction tubes have been reduced considerably. The latter decreases the level of contamination which has a direct bearing on the operational lifetime of the lamps. Incorporation of steps to purify the product from an unwanted material improved the stability of the lamps. The procedure provides a safe and convenient way of handling ²³²U in particular but can be extended in general to any actinides having radioactivity similar to that of freshly separated ²³²U. Characteristic emission of uranium isotopes have been recorded by Fourier Transform Spectrometer to show the satisfactory operation of the lamps as well as their usage for studying emission spectra of the specific isotope.     

On the directed Full Degree Spanning Tree problem

We study the parameterized complexity of a directed analog of the Full Degree Spanning Tree problem where, given a digraph $D$ and a nonnegative integer $k$, the goal is to construct a spanning out-tree $T$ of $D$ such that at least $k$ vertices in $T$ have the same out-degree as in $D$. We show that this problem is W[1]-hard even on the class of directed acyclic graphs. In the dual version, called Reduced Degree Spanning Tree, one is required to construct a spanning out-tree $T$ such that at most $k$ vertices in $T$ have out-degrees that are different from that in $D$. We show that this problem is fixed-parameter tractable and that it admits a problem kernel with at most $8k$ vertices on strongly connected digraphs and $O\left(k^2\right)$ vertices on general digraphs. We also give an algorithm for this problem on general digraphs with running time $O(5.942^k?n^{O\left(1\right)})$, where $n$ is the number of vertices in the input digraph.