Role of some biologically important compounds on the corrosion of mild steel and copper in sodium chloride solutions

The performance of amino acids and carboxylic acids of biological importance on the corrosion of mild steel and copper in sodium chloridesolutionswas investigated. Manyofthe amino acidsare inhibitive. Aspartic acid, cysteine, cystine, threonine and histidine enhance the corrosion of mild steel. For copper, however, all the compounds except 4-amino n-butyric acid and hippuric acid, promote corrosion. The specific influence of the benzoyl group in hippuric acid is brought out. Of the carboxylic acids investigated propionate, oxalate, succinate and a-ketoglutarate bring about considerable inhibition for mild steel. For copper all the anions, except formate, acetate and propionate, increase corrosion and thioglycollate ions are highly aggressive. With a view to study the antimicrobial properties, the effects of papaverine, brucine, strychnine, ephedrine and cinchonidine were also examined. Papaverine is inhibitive for mild steel while brucine, strychnine and cinchonidine are inhibitive for copper. The results are presented in the light of their structural relationships

Corrosion inhibitors for zinc in organic and inorganic acids

Some alkaloids of vegetable origin namely narcotine, papaverine, brucine, strychnine, cinchonidine, quinidine and ephedrine were examined by weight loss and polarization measurements with regard to their inhibitive effect on the corrosion of zinc in 1M solutions of tartaric, citric, acetic, propionic, mono-, di- and trichloracetic acids. In the hydroxy acids the opium and the nuxvomica alkaloids give inhibition efficiency ranging from 58 to 82%, papaverine leading the others. In the mono carboxylic acids the performance of all the alkaloids is poor except that of papaverine. In chloracetic acids narcotine, papaverine and brucine give inhibition efficiency of 70% or more at the higher concentrations only in monochloracetic acid. The polarization experiments of zinc in the systems giving more than 50% inhibition efficiency have also been carried out. The effect of cetyl trimethyl ammonium bromide (CTAB) and hexadecyl pyridinium chloride (HDPC) on the corrosion of zinc in hydrochloric and sulphuric acids has also been investigated. It has been observed that the performance of HDPC is better (I.E. 99.0%) than that of CTAB in both the media and this has been attributed to the presence of a pyridine ring in the former. From polarization experiments it is concluded that the inhibitive action of HDPC is under cathodic control as evidenced by appreciable cathodic polarization, whereas that of CTAB is under mixed control. The results are discussed

Stock discrimination of Sperata aor

High genetic variation is an important requirement for long term survival of wild populations through adaptations to changing environmental conditions. High levels of variability and the potential to isolate large number of loci make microsatellites the marker of choice to study intraspecific genetic variation in fish. Seventy Sperata aor samples each from four sites along the river Ganga were successfully cross amplified at six loci. All the selected loci were highly polymorphic showing a slight heterozygosity excess. The mean observed and expected heterozygosities across all investigated populations were 0.971 and 0.913, respectively. FST statistics, Bayesian model-based clustering analysis and analysis of molecular variance (AMOVA) revealed three different genetic stocks of S. aor (Narora–Kanpur, Varanasi and Bhagalpur), showing moderate genetic differentiation among them (total FST = 0.069). Genetic differentiation was significantly correlated with the distance among stocks. The populations of S. aor are currently stable in the river Ganga as evident from high levels of genetic variability and no inbreeding. However, a precautionary approach to fishery management and conservation of S. aor should be undertaken at priority in view of the anthropogenic as well as natural threats to the fishes of river Ganga