Synthesis,characterization and biological studies of Co(II), Ni(II), Cu(II) and Zn(II) complexes involving a potentially tetradentate Schiff base ligand

Co(II), Ni(II), Cu(II) and Zn(II) complexes of the Schiff base derived from vanillinidene-4-aminoantipyrine and o-phenylenediamine were synthesized and characterized by elemental analysis, ¹H-NMR, ¹³C-NMR, molar conductance, infrared, electronic, magnetic measurements, cyclic voltammetry, powder XRD and SEM. The IR results demonstrate that the co-ordination sites are the four azomethine nitrogen atoms. The electronic spectral and magnetic measurement data indicate that the complexes exhibit octahedral geometry. Powder XRD displays the crystalline nature of Co(II) and Zn(II) complexes. The SEM images reveal that all the complexes have almost similar morphologies with broken-stone like structure. The in vitro biological screening effects of the synthesized compounds were tested against the bacterial species, Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa and Staphylococcus aureus; fungal species, Aspergillus niger, Aspergillus flavus and Candida albicans by the disc diffusion method and the results show that the metal complexes are more biological active than the ligand.     

Use of waste anode dust for sorption of Ni(II) from aqueous solution

Abstract

This study was aimed at investigating the sorption of Ni(II) ions on anode dust which is an industrial waste material of aluminium production. The effects of various parameters such as the initial pH, contact time, temperature and initial concentration were studied. The thermodynamic parameters were determined. The positive values of enthalpy change ΔH suggested the endothermic nature of the sorption process. The sorption kinetic data could be described well using a pseudo‐second‐order model and the equilibrium data could be fitted well to the Langmuir and Freundlich isotherm. It can be concluded that the obtained sorption capacity for Ni(II) ions is a good indicator of the anode dust potential for use in an aqueous sorption system.

Cette étude avait pour but l’investigation de la sorption des ions de Ni(II) sur la poussière d’anode, un matériau de rejet industriel de la production de l’aluminium. On a étudié l’effet de divers paramètres comme le pH initial, la durée de contact, la température, et la concentration initiale. On a déterminé les paramètres thermodynamiques. Les valeurs positives du changement d’enthalpie ΔH suggéraient la nature endothermique du procédé de sorption. On pourrait bien décrire les données cinétiques de la sorption en utilisant un modèle de pseudo deuxième ordre et l’on pourrait bien ajuster les données d’équilibre à l’isotherme de Langmuir et Freundlich. On peut conclure que la capacité de sorption obtenue pour les ions de Ni(II) est un bon indicateur du potentiel de la poussière d’anode pour utilisation dans un système aqueux de sorption.     

Extraction of Ni (II) from Spent Hydrodesulfurization HDS Catalyst Through Leaching and Electroless Precipitation of Ni(OH)2

The extraction of nickel (II) from a spent hydro-desulfurization catalyst containing 11.6 pct Ni was carried out through sulfuric acid leaching. Variations of parameters such as the concentration of acid, temperature, and time, were studied and optimized. Nickel hydroxide was precipitated from the leach liquor via neutralization with 1 M sodium hydroxide up to pH 12 in three different methods: normal neutralization precipitation, and then neutralization precipitation followed by aging at 353 K (80 °C) for 4 hours and neutralization of the leach liquor with 10 pct (v/v) of 0.1 N sodium lauryl sulfate. X-ray diffraction (XRD) and transmission electron microscopy (TEM) microanalysis shows a difference in crystallinity with the method of precipitation. The nickel hydroxide contains Cu(II), Co(II), Zn(II), and Mn(II) as trace impurities. The discharge capacities of the precipitated nickel hydroxides were 120 mAhg^?1, 140.72 mAhg^?1, and 145.2 mAhg^–1 for aged sample, sample without surfactant, and with surfactant respectively.     

The coprecipitation behavior of Co(II) and Ni(II) with Fe(III), Cr(III) and Al(III) from aqueous ammoniacal solutions

The coprecipitation of cobalt(II) and nickel(II) with iron(III), chromium(III) and aluminum(III) from ammoniacal solutions has been investigated. The coprecipitation behavior was found to be very sensitive to the solution pH and total ammonia concentration. Co(II) and Ni(II) can be precipitated from low ammonia concentration solutions but are readily redissolved at higher ammonia concentrations. The coprecipitate of divalent and trivalent species was found to contain very large amounts of the divalent metals (up to a mole ratio M M(II)/M(III) of 2.5) when aluminum was the trivalent species, whereas with iron(III) or chromium(III), the ratio was only 0.5.     

Direct sequencing of double-stranded PCR products incorporating a chemiluminescent detection procedure

A simple and reliable method is described for direct sequencing of material generated by the polymerase chain reaction (PCR). Sequencing reactions can be performed directly on PCR products without the need for purification of the template by removal of residual deoxyribonucleoside triphosphates or primers. The coupling of a chemiluminescent detection system with the use of the same primers in the initial and sequencing PCR's allows for sequencing of a number of PCR products on the one gel.     

Study on the extraction mechanism and thermodynamics of Pb(II) with a o-phenylendiamine tetraacetic acid

The extraction mechanism and thermodynamics of Pb(II) with a novel o-phenylendiamine tetraacetic acid (H₄PDTA) were studied by high performance liquid chromatography with UV detector. The effects of extraction time, reciprocating oscillation frequency, Pb(II) concentration, H₄PDTA concentration and Pb(II) solution acidity on Pb(II) extraction were investigated. The results showed that the extraction ratio of Pb(II) increased with an increase of pH and H₄PEDTA concentration with a reciprocating oscillation frequency of 120 CPM (cycles per minute). The composition of the extraction complex was determined by slope methods and UV spectral analysis. The extraction mechanism of Pb(II) was proved to be a chelate extraction reaction and the values of thermodynamic function at 25°C were determined: \(\overline {K_{ex} } = 2.18 \times 10^3\), ΔG _r = –19.05 kJ mol^–1, ΔH _r = –9.965 kJ mol^–1 and ΔS _r = 30.47 J mol^–1 K^–1.     

CFD Benchmark for a Single Strand Tundish (Part II)

In a comparative benchmark, nine participants of the German Steel Institute VDEh working group “Fluid Mechanics and Fluid Simulation” studied the melt flow in a 16‐t single‐strand tundish. Starting with a steady‐state simulation of the melt flow, the transient flow behaviour was simulated for an idealized ladle change involving a sudden jump in temperature and concentration. In addition, the separation of non‐metallic particles to the melt surface was examined. No guidelines and limitations were made regarding the simulation strategy. The predicted flow profiles, temperature and concentration distributions coincide with each other within a good approximation. Systematic differences in the transient temperature and turbulence fields are explained by the selection of the boundary condition at the free surface. All CFD programs reproduce the fundamental flow structure with a good degree of accuracy. The separation rate for non‐metallic particles calculated on the basis of the Lagrange Method are greater than would be expected according to theory and measurement results obtained on the water model.     

Concentration of Cu(II), Co(II), and Ni(II) ions with <Emphasis Type="Italic">N</Emphasis>-(2-hydroxyethyl)alkyl amines

Regularities of the recovery of Cu(II), Co(II), and Ni(II) ions from ammonia solutions by N-(2-hydroxyethyl)alkyl amines (HEA), namely, regions of pH values of maximal recovery of M(II), the influence of the radical length in the HEA series, and precipitation time, were investigated. It is found by conductometric titration that the ratios in complexes are [Cu(II)] : [HEA] = 2 : 1, 1 : 1, and 1 : 2; [Co(II)] : [HEA] = 1 : 1 and 1 : 2; and [Ni(II)] : [HEA] = 1 : 1 and 1 : 2. Complexes of N-(2-hydroxyethyl)dodecyl amine with Cu(II) and Ni(II) ions are isolated and identified. Their composition is confirmed by the data of IR spectroscopy and elemental analysis. Using N-(2-hydroxyethyl)dodecylamine, a reagent of the HEA series,, which is optimal in regards to the totality of its properties, as an example, the effectiveness of compounds as collectors during the removal of nonferrous metals from waste waters by the ion flotation method is shown. The maximal degree of recovery of the M(II) ions from ammonia solutions by this method is 99.4% for Cu(II) ions (C _res = 0.34 mg/L), 96.8% for Co(II) (C _res = 1.55 mg/L), and 99% for Ni(II) (C _res = 0.60 mg/L).     

Structural analysis of nucleic acids by using fluorescence resonance energy transfer (FRET)

We examined changes in the extent of fluorescence resonance energy transfer (FRET) between two different fluorochromes attached to a single oligonucleotide in the presence or absence of target nucleic acids with a specific sequence and a higher-ordered structure. In our system, FRET was maximal when probes were free in solution and a decrease in FRET was evidence of successful hybridization. Incubation of the probe with a single-stranded complementary oligonucleotide reduced the FRET. While, a small change in FRET was also observed when the probe was incubated with an oligonucleotide in which the target site had been embedded in a stable hairpin structure. These results indicate that this spectrofluorometric method and FRET probes can be used to estimate the efficacy of hybridization between a probe and its target site within highly ordered structures. It should help us to estimate the suitability of designed functional molecules, such as antisense DNA and RNA and ribozymes, that target to specific sites.     

O-(fluoresceinylmethyl)hydroxylamine (OFMHA): a fluorescent reagent for detection of damaged nucleic acids

5- and 6-O-(Fluoresceinylmethyl)hydroxylamine (OFMHA, 5a, b) were prepared from the corresponding bis-pivaloyl-protected hydroxymethylfluoresceins (1a, b) in 50-70% yield. The hydroxylamine derivatives reacted smoothly with the abasic sites present in acid/heat stressed calf thymus DNA.     

Finding a universal low viscosity polymer for DNA separation (II)

When investigating the use of different polymers for capillary electrophoresis we found that poly-N,N-dimethylacrylamide (pDMA) has a very low viscosity compared to other polymers of comparable molecular mass and resolving power. This makes it a potentially useful matrix for DNA separation in multi-capillary electrophoresis, where short cycle times or low pressure for matrix replacement are preferred. We have characterized this matrix by systematic studies on concentration, chain length and field strength dependence. It is shown that pDMA performs well for the separation of oligonucleotides and double-stranded DNA fragments. Together with the application of DNA sequencing, pDMA is a universal polymer for the separation of biological macromolecules.     

Analysis of the mechanism of lipoprotein(a) assembly

We have assessed the ability of a battery of purified recombinant apolipoprotein(a) (r-apo(a)) derivatives to bind to immobilized low-density lipoprotein (LDL) by ELISA. Removal of the apo(a) kringle IV type 8 and type 9 sequences dramatically reduced apo(a) binding to LDL. The binding of apo(a) to LDL was effectively inhibited by arginine, lysine, the lysine analogue epsilon-aminocaproic acid and proline; comparable inhibition was observed using the 17K and KIV5-8 r-apo(a) derivatives, suggesting a direct role for sequences contained in the latter species in mediating the initial non-covalent interactions which precede specific disulfide bond formation. We also determined that r-apo(a) binds directly to a synthetic apoB peptide spanning amino acid residues 3732-3745; this interaction appeared to be mediated by sequences present in apo(a) kringle IV types 8 and 9, and could be inhibited by arginine, lysine and proline. The results of this study indicate that the efficiency of Lp(a) assembly is a direct function of the initial non-covalent interactions between apo(a) and LDL; in addition, these studies suggest that Cys3734 in apoB mediates covalent linkage with apo(a) by virtue of the ability of the apoB sequences surrounding this residue to directly interact with apo(a) KIV type 9.