Metal tolerance

Adaptation of metal tolerances to plastics is not advisable. With plastics reaction to moisture and heat, for example, is drastically different from metals, so that pilot testing under extreme use conditions is almost mandatory for establishing adequate tolerance requirements. Also important to control cost is that close tolerances should be indicated only where needed, carefully analyzed for their magnitude, and proven out as to their usefulness. 

Metal template reactions, 1, 416, 433 equilibrium kinetic, 1, 434 thermodynamic, 1, 434 Metal tolerance amino acid complexes, 2, 964 plants, 2, 963 Metal toxicity... 

B. A. Tomsett, Genetic and molecular biology of metal tolerance in fungi, Stre.ss Tolerance of Fungi (D. H. Jennings, ed.), M. Dekker, New York, 1993, p. 69-82. 

Diaz-Ravina, M. and Baath, E., Development of metal tolerance in soil bacterial communities exposed to experimentally increased metal levels, Appl Environ Microbiol, 62 (8), 2970-2977, 1996. 

Three cyanide-degrading nitrilases were recently cloned and purified and their kinetic profiles were evaluated in order to better understand their applicability to cyanide bioremediation. CynD from Bacilluspumilus Cl and DyngD from Pseudomonas stutzeri exhibit fairly broad pH profiles with >50% activity retained across pH 5.2 to pH 8.0 while the CHT (NHase) from Gloeocercospora sorghi exhibited a more alkaline pH activity profile with almost all of its activity retained at pH 8.5, slightly lower thermal tolerance, and quite different metal tolerance compared with the two bacterial enzymes [46]. 

Baker A.J.M., Walker P.L. Ecophysiology of metal uptake by tolerant plants. In Heavy Metal Tolerance in Plants Evolutionary Aspects, A.J. Shaw, ed. Boca Raton, FL CRC Press. 1989. 

Some heavy metal-tolerant bacterial strains and their sorption capacities for Cu and Cd are listed in Table 1. These bacteria show great potential for remediating soils that are contaminated with toxic metals. Our pot culture experiments showed that the growth of tobacco plants in a Cd-polluted Yellow Brown Soil (Alfisol) was significantly promoted by inoculating the soil with P. Putida in comparison with the non-inoculated soil (Fig. 2). 

Benson, W.H. and W.J. Birge. 1985. Heavy metal tolerance and metallothionein induction in fathead minnows results from field and laboratory investigations. Environ. Toxicol. Chem. 4 209-217. 

Suzuki, K.T., H. Sunaga, S. Hatakeyama, Y. Sumi, and T. Suzuki. 1989. Differential binding of cadmium and copper to the same protein in a heavy metal tolerant species of mayfly (Baetis thermicus) larvae. Comp. Biochem. Physiol. 94C 99-103. 

Grant, A., J.G. Hateley, and N.V. Jones. 1989. Mapping the ecological impact of heavy metals on the estuarine polychaete Nereis diversicolor using inherited metal tolerance. Mar. Pollut. Bull. 20 235-238. 

NeumannD, zurNiedenU, SchwiegerW, Leopoldl, Lichtenberger O. Heavy metal tolerance of Minuartia verna. J Plant Physiol 1997 151 101-108. 

Goldsbrough P., 2000, Metal tolerance in plants The role of phytochelatins and metallothioneins, in Phytoremediation of contaminated soil and water, N. Terry, G. Banuelos, eds, Lewis Publishers, Boca Raton. 

Keywords genetic engineering, genetic diversity, heavy metals, metal accumulation, metal tolerance, model plants, organic contaminants, quantitative trait loei... 

Candidate gene Metal tolerance Metal accumulation Organics tolerance Organics metabolism... 

Kawashima, C., G., Noji, M., Nakamura, M., Ogra, Y., Suzuki, K. T., and Saito, K., 2004, Heavy metal tolerance of transgenic tobacco plants over-expressing cysteine synthase, Biotechnol. Lett. 26 153-157. 

Meerts, P., and Van Isacker, N., 1997, Heavy metal tolerance and accumulation in metallicolous and non-metaUicolous populations of Thlaspi caerulescens from continental Europe, Plant Ecol. 133 221-231. 

Verret, F., Gravot, A., Auroy, P., Leonhardt, N., David, P., Nussaume, L., Vavasseur, A., and Richaud, P., 2004, Overexpression of AtHMA4 enhances root-to-shoot translocation of zinc and cadmium and plant metal tolerance, FEBS Lett. 576 306-312. 

The demonstrated performance of ZSM-5 in over 35 cracking units is reviewed. The main features of ZSM-5 are its high activity and stability, favorable selectivity, metals tolerance and flexibility, particularly when used as an additive catalyst. ZSM-5 cracks and isomerizes low octane components in the naphtha produced by the faujasite cracking catalyst. As a result and olefins are produced and gasoline compositional changes occur which explain its increased research and motor octanes. A model was developed which predicts ZSM-5 performance in an FCC unit. 

ZSM-5 has been used successfully in commercial operations when processing high boiling range feedstock and resids. This is principally due to its ability to maintain activity despite the presence of a high concentration of feed metals. ZSM-5 s excellent metals tolerance has been demonstrated commercially at equilibrium catalyst metals levels up to 10,000 ppm nickel plus vanadium and 6,000 ppm sodium with very little detrimental effect. Laboratory tests show that ZSM-5 is far less affected by metals than Y-zeolite catalysts. Metals were introduced, as follows ... 

The use of ZSM-5 in cracking affords a refiner greater operating flexibility. Ultimately, it permits reoptimization of not only the cracking unit, but the entire refinery. Intrinsic features of ZSM-5 are its high activity, excellent stability, favorable selectivity, versatility, flexibility and metals tolerance. 

We have found that Additive R has very good metals tolerance. Laboratory metals-impregnation studies show that 5,000 ppm Ni + V (33% Ni, 67% V) has no effect on the SOx reduction capability of Additive R. At a higher metals level of 10,000 ppm Ni + V (33% Ni, 67% V), Additive R loses only 9% of its SOx reduction capability. This is seen in Figure 5 for DA-250 + 10% Additive R + 0.37% CP-3. In this study, the DA-250 and Additive R were impregnated with metals then CP-3 was added and the 3-component blend steam deactivated at 1350 F, 100% steam, 15 psig, 8 hours. 

DFCr systems appear to have the necessary metals tolerance to process residual oils and the abundant, cheaper, but heavily vanadium-contaminated, Venezuelan and Mexican crudes (1-4). Therefore, the dual function fluid cracking catalyst (DFCC) concept could lead to the generation of important catalysts for U.S. refineries should Middle East politics cause another sudden escalation in crude oil prices and availability. The concept is... 

In this paper, XPS and Raman spectroscopy have been used to study the chemical state and location of Ni and V contaminants. The effects of thermal and hydrothermal treatments on catalyst surface properties, and the role of sepiolite in promoting metals tolerance has been observed and reported. 

Generally speaking, resid FCC (RFCC) catalysts should be very effective in bottoms cracking, be metals tolerant, and coke and dry gas selective. Based on many years of fundamental research and industrial experiences, a series of RFCC catalysts, such as Orbit, DVR, and MLC, have been developed by the SINOPEC Research Institute of Petroleum Processing (RIPP) and successfully commercialized [1]. These catalysts are very effective in paraffinic residue cracking. However, in recent years more and more intermediate-based residue has been introduced into FCC units, and the performances of conventional RFCC catalysts are now unsatisfactory. Therefore, novel zeolites and matrices have been developed to formulate a new generation of RFCC catalysts with improved bottoms cracking activity and coke selectivity. 

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