N,N′-methylene-bis-acrylamide-crosslinked polyacrylamides as supports for dithiocarbamate ligands for metal ion complexation

The complexation behaviour of dithiocarbamate functions supported on polyacrylamides with varying extents (2-20 mol%) of N,N′-methylene-bis-acrylamide (NNMBA) crosslinks was investigated. The crosslinked polyacrylamides were prepared by the free radical solution polymerization of the monomers in water at 80°C using potassium persulphate as initiator. The dithiocarbamate ligands were introduced by polymer-analogous reaction involving transamidation with ethylenediamine and dithiocarbamylation with carbon disulphide and alkali. The complexation behaviour of these dithiocarbamate resins with the ligand functions in different macromolecular environments were investigated towards Co(II), Ni(II), Cu(II), Zn(II) and Hg(II) ions by a batch equilibration technique. The metal ion intake varied with the extent of the NNMBA-crosslinking. Thus the 8% crosslinked system has the highest complexation capacity. The values for metal ion intake followed the order Hg(II)> Cu(II)> Zn(II)> Ni(II)> Co(II). The time-course of complexation, the possibility of recycling and the swelling characteristics of the uncomplexed and complexed resins were considered, and IR characterization and thermal studies were undertaken. The swelling values of the complexed resins are lower than those of the uncomplexed resins. The thermal stability of dithiocarbamates varied with the extent of NNMBA-crosslinks and with the metal ion.     

Studies on the hydrogenation of alkenes and alkynes using polymer coated silica-Pd catalysts

Palladium complexes of crosslinked polyacrylamide and poly-N-vinylimidazole coated on silica gel have been prepared and used as hydrogenation catalysts for alkenes, dienes and alkynes under ambient conditions. The characterisation of the catalysts, the kinetic and mechanistic aspects of the hydrogenation of a few substrates, the effect of temperature, selectivity and the recycling efficiency of the catalysts are presented. A comparison of their activity is made with other silica supported and silica free polymer-Pd catalysts.     

Quantitation of Cefaclor in Pharmaceutical Dosage Forms Using High Performance Liquid Chromatography

A stability-indicating high-performance liquid chromatography for the quantitation of cefaclor in pharmaceutical dosage forms has been developed. The method is accurate and precise with a percent relative standard deviation of 1.2 based on 5 readings. A number of inactive ingredients present in the capsules and suspensions did not interfere with the assay procedure. The extraction procedure from the dosage forms is very simple. The recovery from the synthetic mixtures was quantitative. The capsules which had expired 3 years ago lost only 3% of the potency. The drug appears to be very sensitive to strong acids or bases since a 5 minute boiling caused 100% degradation of drug in both the solutions.     

Quantitation of Nizatidine in Capsules Using High-Performance Liquid Chromatography

A stability-indicating high-performance liquid chromatography method for the quantitation of nizatidine in capsules has been developed. The method is accurate and precise with a percent relative standard deviation of 0.34 based on 6 readings. A number of inactive ingredients present in the capsules did not interfere in the assay procedure. The recovery from the synthetic mixtures was quantitative. The extraction procedure from the capsules is very simple. The drug appears to be very sensitive to bases (such as sodium hydroxide) since 100% of the drug decomposed on boiling for 35 minutes. The drug was very stable when boiled with sulfuric acid.     

Synthesis of LiFePO4 nanoparticles by solvothermal process using various polyol media and their electrochemical properties

Olivine structured LiFePO4 samples were synthesized by solvothermal process using various polyol media of ethylene glycol (EG), diethylene glycol (DEG), triethylene glycol (TEG), and tetraethylene glycol (TTEG) without any heating as a post procedure. The X-ray diffraction patterns of the samples prepared in EG and DEG showed the crystalline peaks with well-fitted to the positions on the basis of an olivine type structure without any impurities. In order to determine the unit cell parameters, synchrotron powder XRD patterns were fitted with whole-pattern profile matching method using FULLPROF program. The obtained samples exhibited well dispersed nanoplate morphologies excepting for the sample prepared in EG. The samples prepared in EG, DEG, TEG, and TTEG showed the reversible capacity of 118, 167, 90, and 105 mAh/g at current density of 0.1 mA/cm2, respectively. Among them, the samples reacted in DEG and TTEG showed good performances at high rate of 16C with high capacities retention.     

Monckeberg's calciphylaxis with necrosis of the glans penis: a case presentation

Monckeberg's calcific sclerosis of the media of the small-sized and medium-sized arteries is a well described and potentially life-threatening condition seen almost exclusively in patients with end-stage renal disease (ESRD) and with hyperparathyroidism. Penile gangrene resulting from this entity is associated with a mortality as high as 64%. A 65-year-old man with ESRD on dialysis for 6 years was referred to Harborview Medical Center with severe penile pain and partial necrosis of his glans penis, which progressed despite medical management. The patient had previously undergone amputations on all four extremities. After intraoperative biopsies of the proximal corpora cavernosa and spongiosum demonstrated viable tissue, he underwent partial penectomy. Pathologic evaluation revealed calciphylaxis within the media of the penile vessels. Two months later the patient had persistent wound-healing issues with intractable pain and thus underwent a complete penectomy with ultimate resolution of his severe pain.