Effects of Other Metals

Kanematsu et al. 1980) except for the induction of lambda prophage in E. coli (Rossman et al. 1984). 

Hg(II) enhanced cell transformation by SA7 virus in Syrian hamster embryo cells, but did not induce transformation of human fibroblasts (Casio et al. 1979 Biederman and Landolph 1987). It also inhibited alkylguanine-DNA-alkyltransferase, suggesting the possibility of synergism with small alkylating agents (Scicchitano and Pegg 1987 Bhattacharyya et al. 1988). 

Me-Hg-Cl is more toxic than Hg(II), and both forms can induce DNA strand breaks in cells (reviewed in Costa et al. 1991). Hg(II)-induced strand breaks are not repaired, and, in fact, Hg(II) may itself inhibit repair of its own lesions since it has been found to inhibit X-ray-induced strand breaks (Christie et al. 1986 Snyder et al. 1989) as well as UV-induced damage (Snyder et al. 1989). Hg(II) is capable of generating oxygen radicals in cells. 

Hg(II) induced SCEs only slightly in CHO cells but a greater response was seen in human lymphocytes (Howard et al. 1991 Morimoto et al. 1982). Chromosomal aberrations have been induced by Hg(II) and by organomercury compounds in a variety of cells (Leonard et al. 1983 Howard et al. 1991). In addition to its clastogenic effects, mercury compounds cause a disturbance of mitosis due to their reactions with the sulfhydryl groups in the spindle fiber proteins. Deleterious effects on the spindle apparatus were seen with Me-Hg-Cl in a number of studies (Watanabe et al. 1982 Curle et al. 1987). Effects on the spindle apparatus are likely to lead to errors of chromosomal segregation (i.e., aneuploidy) (Ramel and Magnusson 1979 Verschaeve et al. 1984). 

Compounds of antimony have not been assayed for mutagenicity in mammalian cells. Sb(III) was shown to enhance transformation by SA7 virus (Casio et al. 1979). Because antimonite resembles arsenite, and can induce arsenite tolerance (Wang and Rossman 1993), one might speculate that antimonite could have a comutagenic effect similar to that of arsenite. 

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Clearly, at this point, there is a need for additional data concerning the effect of other metal ions on the recrystallization of aragonite. With-... 

To eliminate the effect of other metals which form oxinates in slightly acidic medium, the following procedure has been recommended. The chloroform extract which is obtained at pH 4, and contains V and Fe(lII), and partly also Al, Co, Zn, Ni, Mo, W, Cu, Ti, and Bi oxinates, is shaken with an aqueous alkaline solution (pH 9.4), thereby stripping vanadium into the aqueous phase and leaving behind Fe together with the other metals in the CHCI3 solution. From the acidified aqueous phase, V is re-extracted with a CHCI3 solution of oxine and the absorbance is measured. In this manner the oxine method becomes specific for V(V). 

Figure 9.1. Effect of other metals on cobalt calibration curves...

Table 14.III. Effect of Other Metals on the Determination of Nickel and Vanadium0,6...

In spite of this evidence it is difficult to exclude the effect of other metals besides the titanium. For example, the most active titanium trichorides are generally prepared by the reduction of TiCU by an Aluminium alkyl and these precipitates invariably contain some Aluminium (probably as AICI3) as an impurity. Even though these may play no direct part in the catalysis, their presence probably has an appreciable effect on the activity of the Titanium atoms... 

Jiang ef a J [3 8] investigated the effect of other metals (Y, La, Fe, Co and Ni) on the WGS activity of Cu-Ce-Zr catalysts. The WGS activity results of various metal-doped Cu-Ce-Zr catalysts are presented in Figure 3.5. Among the various dopants Fe shows higher activity compared to other dopants. Then they investigated the effect of Fe content. The CO conversion increased with increasing Fe content up to 3 wt% and further increase in Fe content decreases the WGS activity. 

Coagulation of silver halide by hydrolyzed aluminum salts was shown by Matijevi6, Kratohvil, and Sticles (267) to be inhibited by fluoride ion which formed complex ions with aluminum. Similar reduction in coagulation effectiveness of other metal cations such as Fe and Th on colloidal silica may be anticipated. 

Effect of other Metals on Iron Assimilation.— Iron metabolism in higher animals appears to be catalysed by traces of copper. Similar effects have been claimed for related metals, including manganese, nickel, and cobalt, but the results of different investigations are at variance. 

The expression template reaction indicates mostly a reaction in which a complexed me) ion holds reactive groups in the correct orientation to allow selective multi-step reactions. T1 template effect of the metal is twofold (i) polymerization reactions are suppressed, since th local concentration of reactants around the metal ion is very high (ii) multi-step reactions are possible, since the metal holds the reactants together. In the following one-step synthesis eleven molecules (three ethylenediamine — en , six formaldehyde, and two ammonia molecules) react with each other to form one single compound in a reported yield of 95%. It is ob vious that such a reaction is dictated by the organizing power of the metal ion (I.I. Creasei 1977),... 

During the 1980s, antimony was widely used in FCCUs that had a problem with contaminant metals. In the late 1980s, other additives were introduced to combat the contaminant metals, eg. Chevron introduced a bismuth-based additive, which is claimed to provide performance similar to antimony (18). Also in the late 1980s, cracking catalysts were developed with metals traps that appear to be so effective in containing the adverse effects of contaminant metals that additive-type inhibitors are no longer needed (19). 

A good catalyst is also stable. It must not deactivate at the high temperature levels (1300 to 1400°F) experienced in regenerators. It must also be resistant to contamination. While all catalysts are subject to contamination by certain metals, such as nickel, vanadium, and iron in extremely minute amounts, some are affected much more than others. While metal contaminants deactivate the catalyst slightly, this is not serious. The really important effect of the metals is that they destroy a catalyst s selectivity. The hydrogen and coke yields go up very rapidly, and the gasoline yield goes down. While Zeolite catalysts are not as sensitive to metals as 3A catalysts, they are more sensitive to the carbon level on the catalyst than 3A. Since all commercial catalysts are contaminated to some extent, it has been necessary to set up a measure that will reflect just how badly they are contaminated. 

A remarkable feature of the Birch reduction of estradiol 3-methyl ether derivatives, as well as of other metal-ammonia reductions, is the extreme rapidity of reaction. Sodium and -butyl alcohol, a metal-alcohol combination having a comparatively slow rate of reduction, effects the reduction of estradiol 3-methyl ether to the extent of 96% in 5 minutes at —33° lithium also effects complete reduction under the same conditions as is to be expected. Shorter reaction times were not studied. At —70°, reduction with sodium occurs to the extent of 56 % in 5 minutes, although reduction with lithium is virtually complete (96%) in the same time. (The slow rates of reduction of compounds of the 5-methoxytetralin type is exemplified by 5-methoxy-tetralin itself with sodium and f-butyl alcohol reduction occurs to the extent of only 50% in 6 hours vs. 99+% with lithium.) The iron catalyzed reaction of sodium with alcohols must be very fast since it competes so well with the rapid Birch reduction. One cannot compensate for the presence of iron in a Birch reduction mixture containing sodium by adding additional metal to extend the reaction time. The iron catalyzed sodium-alcohol reaction is sufficiently rapid that the aromatic steroid still remains largely unreduced. 

Selective extraction experiments were then performed to see transference of some transition elements (Cu ", Ni ", Co ", and Fe " ) from the aqueous phase to the organic phase by the synthesized polymeric calixarenes. Phase-transfer studies in water-chloroform confirmed that polymer 2b and 3b were Fe ion-selective as was its monomer (1). Extraction of Fe " cation with 2b and 3b was observed to be maximum at pH 5.4. Only trace amounts of other metal cations such as Cu, Ni ", and Co " were transferred from the aqueous to the organic phase (Table 3). Furthermore, the extracted quantities of these cations remained unaffected with increasing pH. The effect of pH on the extraction of 3b was lower and 56% extraction was accomplished even at pH 2.2. The extraction experiments were also performed with calix[4]arene (1) the ratio was 8.4% at pH 2.2. The polymeric calix[4]arenes were selective to extract Fe " from an aqueous solution, which contained Cu +, Ni, Co ", and Fe " cations, and it was observed that the... 

The metals most commonly used for water systems are iron and steel. These metals often have some sort of applied protective coating galvanised steel, for example, relies on a thin layer of zinc, which is anodic to the steel except at high temperatures. Many systems, however, contain a wide variety of other metals and the effect of various water constituents on these must be considered. The more usual are copper, brasses, bronzes, lead, aluminium, stainless steel and solder. 

There is an accelerating trend away from the use of lead-containing solders in contact with potable water. The effects of galvanic corrosion of one of the substitute alloys (Sn3%Ag) in contact with a number of other metals including copper have therefore been studied . The corrosion of tin/Iead alloys in different electrolytes including nitrates, nitric and acetic acids, and citric acid over the pH range 2-6 were reported. The specific alloy Pb/15%Sn was studied in contact with aqueous solutions in the pH range... 

The nature of the metal Since the majority of inhibitors are specific in their action towards particular metals, an inhibitor for one metal may have no effect and even an adverse effect on other metals. Table 17.1 is a general guide to the effectiveness of various inhibitors for metals in the near-neutral pH... 

Cu, Ni, Co, Cr, Fe, or Al, even in traces, must be absent when conducting a direct titration of the other metals listed above if the metal ion to be titrated does not react with the cyanide ion or with triethanolamine, these substances can be used as masking reagents. It has been stated that the addition of 0.5-1 mL of 0.001 M o-phenanthroline prior to the EDTA titration eliminates the blocking effect of these metals with solochrome black and also with xylenol orange (see below). 

Determination of copper as copper(I) thiocyanate Discussion. This is an excellent method, since most thiocyanates of other metals are soluble. Separation may thus be effected from bismuth, cadmium, arsenic, antimony, tin, iron, nickel, cobalt, manganese, and zinc. The addition of 2-3 g of tartaric acid is desirable for the prevention of hydrolysis when bismuth, antimony, or tin is present. Excessive amounts of ammonium salts or of the thiocyanate precipitant should be absent, as should also oxidising agents the solution should only be slightly acidic, since the solubility of the precipitate increases with decreasing pH. Lead, mercury, the precious metals, selenium, and tellurium interfere and contaminate the precipitate. 

The shift of the half-wave potentials of metal ions by complexation is of value in polarographic analysis to eliminate the interfering effect of one metal upon another, and to promote sufficient separation of the waves of metals in mixtures to make possible their simultaneous determination. Thus, in the analysis of copper-base alloys for nickel, lead, etc., the reduction wave of copper(II) ions in most supporting electrolytes precedes that of the other metals and swamps those of the other metals present by using a cyanide supporting electrolyte, the copper is converted into the difficultly reducible cyanocuprate(I) ion and, in such a medium, nickel, lead, etc., can be determined. 

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