Recovery of cobalt from secondary sector using extraction in Cyanex 923

2954-2958A process for the recovery of pure Co(II) from spent Co-Mn and Co-Mo catalysts by its extraction in Cyanex 923 is described. The metal ion is partitioned in the organic phase as H2CoCl4.2 Cyanex 923 and stripped with a solution of 1×10-3 molL-1 H2SO4. The extractant is stable towards prolonged contact with HCl and shows negligible loss in extraction capacity even after recycling for twenty cycles. The partition data have been utilized for developing conditions for the separation of Co(II) from other metal ions, viz., Mo(VI), AI(III), Cr(III), Fe(III), Mn(II), Ni(II), Cu(II), Zn(II) and Cd(II). The separation technique has been extended for the recovery of ~95% Co(II) from spent catalysts. The purity of the metal ions thus obtained approximates to 99%

Selective extractive spectrophotometric determination of cobalt using cyanex 923

470-474The present paper describes a selective extractive spectrophotometric method for the determination of Co (II)using toluene solution of cyanex 923. A blue coloured complex (λmax 685 nm) is quantitatively extracted in the organic phase from 7-10 mol L-1 HCl. The composition of this complex is proposed as H2CoCl4.2cyanex 923 . The Beer 's law is obeyed in the concentration range 0.0-4.2×10-3 mol L-1 Co(II) and the molar absorptivity of the complex is 5.6×102 L mol-1 cm-1. The presence of hundredfold excess of metal ions such as Mo(VI), W(VI), V(V), Ti(IV), V(IV), Al(III), Cr(III), Fe(III), Mn(III), Fe(III), Ni(II), Cu(II), Zn(II) and Cd(II) and fifty fold of anions namely PO43-, SO42-, C2O42-, citrate, tartrate, NO3- and SCN- do not interfere in the determination of Co(II). The accuracy of proposed procedure is checked by assaying the concentration of cobalt in two standard NBS steel samples. The applicability of the method is demonstrated by selective determination of Co(II) in a multielement system like polymetallic manganese sea nodules. The result is in fairly good agreement with those obtained by AAS and ICPAES

Serum Vitamin D levels in Chronic Obstructive Pulmonary Disease

Introduction: Lower serum 25 (0H) Vitamin D is associated with decreased lung function in healthy population and various lung disease. Information on the relationship of levels of serum 25 (OH) Vitamin D with severity of Chronic Obstructive Pulmonary Disease (COPD) is important in standardizing the treatment, in planning appropriate follow up and improving quality of life. This study also warranted further trial to assess the effect of serum 25 (OH) vitamin D on morbidity and mortality in COPD patients. Material and Methods: It was a prospective (observational), cross-sectional study which included all patients with Chronic Obstructive Pulmonary Disease (COPD) attended the Department of Pulmonary Medicine, People’s College of Medical Sciences & RC, Bhopal, over a period of 1 year 6 months. Results: The mean serum 25 (OH) vitamin D level in COPD patients was 27.86±16.47 ng/ml. There was no significant difference in serum 25 (OH) vitamin D between patients in different age groups. The serum 25 (OH) vitamin D levels varied significantly between different GOLD stages and different mMRC dyspnea grades. The patient who had a history of admission for twice or more in the past 1 year had a lower mean serum 25 (OH) vitamin D level as compared to patient with just one or no hospitalization in the past. Conclusion: Decrease serum 25(0H) vitamin D levels were associated with increase airway obstruction

Minor groove binding DNA ligands with expanded A/T sequence length recognition, selective binding to bent DNA regions and enhanced fluorescent properties

DNA minor groove ligands provide a paradigm for double-stranded DNA recognition, where common structural motifs provide a crescent shape that matches the helix turn. Since minor groove ligands are useful in medicine, new ligands with improved binding properties based on the structural information about DNA-ligand complexes could be useful in developing new drugs. Here, two new synthetic analogues of AT specific Hoechst 33258 5-(4-methylpiperazin-1-yl)-2-[2'-(3,4-dimethoxyphenyl)-5'-benzimidazolyl] benzimidazole (DMA) and 5-(4-methylpiperazin-1-yl)-2-[2'{2"-(4-hydroxy-3-methoxyphenyl)-5"-benzimidazolyl}-5'-benzimidazolyl] benzimidazole (TBZ) were evaluated for their DNA binding properties. Both analogues are bisubstituted on the phenyl ring. DMA contains two ortho positioned methoxy groups, and TBZ contains a phenolic group at C-4 and a methoxy group at C-3. Fluorescence yield upon DNA binding increased 100-fold for TBZ and 16-fold for DMA. Like the parent compound, the new ligands showed low affinity to GC-rich (κ ≈ 4 × 10<SUP>7</SUP> M<SUP>−1</SUP>) relative to AT-rich sequences (κ ≈ 5 × 10<SUP>8</SUP> M<SUP>−1</SUP>), and fluorescence lifetime and anisotropy studies suggest two distinct DNA-ligand complexes. Binding studies indicate expanded sequence recognition for TBZ (8-10 AT base pairs) and tighter binding (Δ T<SUB>m</SUB> of 23 ° C for d (GA<SUB>5</SUB>T<SUB>5</SUB>C). Finally, EMSA and equilibrium binding titration studies indicate that TBZ preferentially binds highly hydrated duplex domains with altered A-tract conformations d (GA<SUB>4</SUB>T<SUB>4</SUB>C)<SUB>2</SUB> (κ = 3.55 × 10<SUP>9</SUP> M<SUP>−1</SUP>) and alters its structure over d (GT<SUB>4</SUB>A<SUB>4</SUB>C)<SUB>2</SUB> (K = 3.3 × 10<SUP>8</SUP> M<SUP>−1</SUP>) sequences. Altered DNA structure and higher fluorescence output for the bound fluorophore are consistent with adaptive binding and a constrained final complex. Therefore, the new ligands provide increased sequence and structure selective recognition and enhanced fluorescence upon minor groove binding, features that can be useful for further development as probes for chromatin structure stability