Cyanide is a well known toxicant that arises in the environment from both biological and industrial sources. Bacteria have evolved novel coping mechanisms for cyanide and function as principal agents in the biosphere for cyanide recycling. Some bacteria exhibit the unusual ability of growing on cyanide as the sole nitrogen source. One such organism is Pseudomonas fluorescens NCIMB 11764 (Pf11764) which employs a novel oxidative mechanism for detoxifying and assimilating cyanide. A unique complex of enzymes referred to as cyanide oxygenase (CNO) is responsible for this ability converting cyanide to ammonia which is then assimilated. Because one component of the four member CNO complex was previously shown to act on cyanide independent of the other members, its characterization was sought as a means of gaining a better understanding of the overall catalytic mechanism of the complex. Preliminary studies suggested that the enzyme belonged to a subset of nitrilase enzymes known as cyanide dihydratases (CynD), however, a cynD-like gene in Pf11764 could not be detected by PCR. Instead, a separate nitrilase (Nit) linked to cyanide metabolism was detected. The corresponding nit gene was shown to be one of a conserved set of nit genes traced to a unique cluster in bacteria known as Nit1C. To determine whether the previously described CynD enzyme was instead Nit, efforts were undertaken to isolate the enzyme. This was pursued by cloning and expressing the recombinant enzyme and by attempting to isolate the native enzyme. This thesis is concerned with the latter activity and describes the purification of a Nit-like cyanide-degrading nitrilase (NitCC) from Pf11764 to ~95% homogeneity. Purification was greatly facilitated by the discovery that fumaronitrile, as opposed to cyanide, was the preferred substrate for the enzyme (20 versus 1 U/mg protein, respectively). While cyanide was less effective as a substrate, the specificity for cyanide far outweighed that (10,000 fold) of the recombinant enzyme (NitPG) implying that the native NitCC protein purified in this work is different from that of the cloned recombinant. Further evidence of this was provided by molecular studies indicating that the two proteins differ in mass (34.5 and 38 kDa, respectively) and amino acid sequence. In summary, two different Nit enzymes are encoded by Pf11764. While the two share greater than 50% amino acid sequence identity, the results suggest that the native NitCC enzyme purified in this work functions better as a cyanide-degrading nitrilase and is one of four enzyme components comprising CNO required for Pf11764 cyanide assimilation.

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A Thesis presented in the University of the Witwatersrand, Johannesburg for the degree of Doctor of Philosophy, 1953 / Investigations have been carried out into the life of various Anion Exchange Resins employed on the Rand for the extraction of uranium from the uranium Leach Liquors. It was found that in the case of the leach liquors produced at the western Reefs pilot plant and at the West Rand Consolidated Uranium plant, the major factor causing a decrease in the efficiency of the Ion exchange resins was the presence of certain chemical poisons in these pregnant solutions. [No abstract provided. Information taken from General Summary] / AC2017

Ion exchange equilibria are presented for [ ]??? ??? Au(CN)2 / Cl , [ ]??? ??? Au(CN)2 / SCN and SCN??? / Cl??? in aqueous solution, and in various mixed solvents, at 303K using Purolite A500 as the ion-exchanger. The mixed solvents investigated include water-acetone, water-dimethylsulfoxide (DMSO) and water-N-methyl-2-pyrrolidone (NMP). In aqueous solution, the selectivity of Purolite A500 for a given anion increases in the order: [ ]??? ??? &lt ??? &lt Cl SCN Au(CN)2 . This selectivity sequence confirms the high affinity of the ion exchange resin for the [ ]??? Au(CN)2 species. In mixed solvents, however, the selectivity of Purolite A500 for [ ]??? Au(CN)2 decreases with an increase in the composition of the organic solvent in the external solution. Mixed solvents containing greater than 60 mol% organic solvent are preferred for the displacement of [ ]??? Au(CN)2 from the resin. The effectiveness of a given type of mixed solvent generally increases in the following order: DMSO &it acetone &it NMP. The ion exchange equilibria are correlated using the Law of Mass Action, modified with activity coefficients, to determine the equilibrium constant for each binary system. The fitted values of the equilibrium constants are consistent with the trends observed in the ion exchange isotherms. The accuracy of the correlation results in the mixed solvent systems range from 1 to 10% and this is similar to the level of accuracy obtained for the ion exchange equilibria in aqueous solution. From these results it can be concluded that the Law of Mass Action is equally valid in mixed solvent systems. The variation in the equilibrium constant with mixed solvent composition, for a given binary system, correlates well with the dielectric constant of the mixed solvent. For a given value of the dielectric constant, however, the equilibrium constant, however, the equilibrium constant is dependent on the type of mixed solvent. A fundamental relationship is derived between the equilibrium constants and the Gibbs energies of transfer associated with the solvation of the ions in the mixed solvents. Based on this relationship, the redistribution of ions between the pore solution and the bulk mixed solvent, appears to be the most significant factor that governs the selectivity of the resin in mixed solvent systems.

1. Colorimetric Assay for Cyanide and Cyanogenic Glycoside Using Polysorbate 40-Stabilized Gold Nanoparticles. This study described a simple and homogeneous method for the selective and sensitive detection of cyanide and endogenous biological cyanide using polysorbate 40-stabilized gold nanoparticles (PS 40-AuNPs). Neutral PS 40 molecules enable citrate-capped AuNPs to stabilize in a high-salinity solution. The addition of cyanide to a solution of PS 40-AuNPs resulted in the formation of AuCN(s) on the NP surface and Au(CN)2¡V in an aqueous solution. The removal of PS 40 molecules from the NP surface rendered the AuNPs unstable in a high-salinity solution, leading to NP aggregation. The formation of AuCN(s) and Au(CN)2¡V was demonstrated by means of surface-assisted laser desorption/ionization time of flight mass spectrometry and inductively coupled plasma mass spectroscopy, respectively. PS 40-AuNPs were capable of selectively detecting cyanide at concentrations as low as 500 nM. Additionally, the minimum detectable concentration of linamarin (cyanogenic glycoside) was measured to be 1 uM using PS 40-AuNPs. This probe was successfully applied to the determination of cyanide in tap water, the monitor of cyanide removal during food processing, and the quantification of linamarin in cassava root. 2. Colorimetric detoxification and monitored cyanogenic glycoside in plants/fruit using polysorbate 40-stabilized gold nanoparticles. Developing rapid, highly sensitive, and selective detection/inhibition of cyanide/cyanogenic glycoside from plants and foods is extremely essential for human life safety. Here we report a strategy for the colormetric visualization of cyanogenic glycoside using polysorbate 40 stabilized gold nanoparticle (PS 40-AuNPs). Two cyanogenic glycosides (amygdalin and linamarin) were chosen to determine the efficiency of acid hydrolysis. According to US Department and Health and Human Services standard cyanide antidote kit, sodium thiosulfate and hydroxocobalamin (vitamin B12a) seems to be an appropriate antidote for treatment cyanide poisoning victims. The addition of thiosulfate/vitamin B12a to a solution of cyanide/cyanogenic glycosides resulted in the formation of thiocyanate/vitamin B12 in an aqueous solution, which couldn¡¦t etch PS 40-AuNPs and inhibit the aggregation of PS 40-AuNPs in a high-salt solution. The inhibition/detoxification efficiency (IC50) of thiosulfate and vitamin B12a were studied for treatment of cyanide and hydrolyzed cyanogenic glycoside. This probe was also used to monitor the removal of cyanide, estimated the concentration of cyanide and detoxification of cyanide by thiosulfate in plants/fruit sample.

Ferric ferrocyanide (Prussian blue) and its analogues are renowned for the variety of properties and applications associated with them. At the same time, however, they suffer from issues related to their variable composition and poor crystallinity. As a result, we are preparing discrete cyanide-bridged clusters both to mimic these materials and to search for properties unique to the molecule, such as single molecule magnetism. The work in this dissertation has focused on the expansion of series of trigonal bipyramidal (TBP) cyanide-bridged clusters, [M(tmphen)2]3[M′(CN)6]2, that exhibit a variety of properties including spin crossover, charge-transfer-induced spin transition, and photomagnetism. One goal of the work was focused on the preparation of new paramagnetic TBP clusters incorporating various 3d metal ion combinations. Nine new clusters were prepared and characterized, including several “model compounds” with only one type of paramagnetic metal ion. The magnetic properties of these model compounds were combined to better explain the coupling through the cyanide ligands in clusters with two paramagnetic metal centers. An additional two clusters were also prepared that were found to exhibit a thermally induced LS Fe^II -> HS Fe^II transition. The spin crossover event was confirmed by magnetic susceptibility and Mössbauer spectroscopy, and variable temperature X-ray crystallography revealed the transitions to be distinct for each FeII center and dependant on the interstitial solvent. Another major goal of the work was to investigate the TBP clusters for their potential to be used as building-blocks to prepare 1-D extended structures of linked clusters, such as a {[Co(tmphen)2]3[Fe(CN)6]2[Mn(MeOH)4]}∞(ClO4)3 chain. A final research goal was a search for photomagnetic behavior, the change in magnetic properties with irradiation, related to spin transitions in several key TBP clusters. The Fe3Fe2 and Fe3Co2 TBP clusters were found to exhibit a light-induced excited spin state trapping (the LIESST effect) similar to that observed in mononuclear FeII compounds, and the photo-induced charge transfer that has been observed in Co-Fe Prussian blue materials is mimicked by the Co3Fe2 TBP molecular analogue.

This study examined the impact of reformed fishing and reef management practices in a community-based marine ornamental fishery in Tejakula sub-district, Bali, Indonesia, on the development of effective community-based natural resource management. With the absence of cyanide fishing for one decade, the coral reef condition has improved from 26% of area coverage to 53%. T-test result shows that there is no significant difference in individual fishing revenue and a considerable decrease in total fishery revenue. The fishers have benefited in resource conservation and a 73% decrease in fishing costs. The overall number of ornamental fishers has declined, due to social pressure, a smaller overall fishing space because of No Take Zones (NTZ), and fewer orders for ornamental fish.Environmental education for local community members is critical to maintain adherence to the reformed method of fishing. Clear definition of the NTZS policy should be acknowledged to avoid recurring conflict among stakeholders.