Effect of Manganese

X Value Vh (A ) Qmax (mAhg ) n, H atoms per unit cell %AV/V Corrosion (wt%/cycle) 

Notten etal. [51, 52] reported that the electrochemical cycUng stability can be improved dramatically when using nonstoichiometric La(NiCu)5+x alloys. They attributed such improvement to an alteration of the crystal structure in which the excess of B-type atoms is accommodated in the AB5 lattice by the occupation of empty A sites (La) with dumbbell pairs of Ni atoms oriented along the c-axis, although the hexagonal P6/mmm space group is preserved. 

The La(Ni, Sn)5+x materials are most interesting as they constitute a new class of compounds which may provide alloys that could be fabricated into low-cost, corrosion-resistant electrodes. We also note that the existence of transition metal dumbbells is not unique. They exist in LaNis+x [54] and RE2Fei7Cx whose A2B17 type structure is an ordered superstructure of the CaCus lattice and AB7 compounds where B is Cu or Ni [55, 56]. 

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Nitrogen is normally supplied as an ammonium compound in dtric acid fermentations and suffident has to be supplied to enable the effect of manganese deficiency (increased levels of ammonium in the metabolic pool) to occur. Remember that increased metabolic pool ammonium has the effect of releasing the allosteric controls exerted on phosphofructokinase. 

The effects of manganese on the cobalt/bromide-catalyzed autoxidation of alkylaromatics are summarized in Figure 17. The use of the Mn/Co/Br system allows for higher reaction temperatures and lower catalyst concentrations than the bromide-free processes. The only disavantage is the corrosive nature of the bromide-containing system which necessitates the use of titanium-lined reactors. 

In the presence of manganese(II) ions the rate of oxidation of H2R by chromic acid decreases . Under favourable experimental conditions (high concentration of alcohol and low concentration of chromate) the diminution of rate is about 50 % which is in accordance with results listed in Table 6, according to which ci = 0.5. The inhibiting effect of manganese(II) on the oxidation of H2R can be explained by reaction (23) followed by step (24). Therefore the induced oxidation of manganese(II) can be described by reactions (26), (23) and (24). 

In a demonstration of the powerful oxidant effect of manganese heptoxide on ethanol layered on top of sulfuric acid, it is essential to observe all the precautions given to prevent violent exothermic reactions. 

Shindo H, Huang PM (1984) Catalytic effects of manganese (IV), iron (III), aluminum, and silicon oxides on the formation of phenolic polymers. Soil Sci Soc Am J 48 927-934... 

Morales F., de Smit E., de Groot F.M.F., Visser T., and Weckhuysen B.M. 2007. Effects of manganese oxide promoter on the CO and H2 adsorption properties of titania-supported cobalt Fischer-Tropsch catalysts. J. Catal. 246 91-99. 

Bezemer, G. L., Radstake, P. B., Falke, U., Oosterbeek, H., Kuipers, H. P. C. E., van Dillen, A., and de Jong, K. P. 2006. Investigation of promoter effects of manganese oxide on carbon nanofiber-supported cobalt catalysts for Fischer-Tropsch synthesis. Journal of Catalysis 237 152-61. 

Thus, the mechanism of MT antioxidant activity might be connected with the possible antioxidant effect of zinc. Zinc is a nontransition metal and therefore, its participation in redox processes is not really expected. The simplest mechanism of zinc antioxidant activity is the competition with transition metal ions capable of initiating free radical-mediated processes. For example, it has recently been shown [342] that zinc inhibited copper- and iron-initiated liposomal peroxidation but had no effect on peroxidative processes initiated by free radicals and peroxynitrite. These findings contradict the earlier results obtained by Coassin et al. [343] who found no inhibitory effects of zinc on microsomal lipid peroxidation in contrast to the inhibitory effects of manganese and cobalt. Yeomans et al. [344] showed that the zinc-histidine complex is able to inhibit copper-induced LDL oxidation, but the antioxidant effect of this complex obviously depended on histidine and not zinc because zinc sulfate was ineffective. We proposed another mode of possible antioxidant effect of zinc [345], It has been found that Zn and Mg aspartates inhibited oxygen radical production by xanthine oxidase, NADPH oxidase, and human blood leukocytes. The antioxidant effect of these salts supposedly was a consequence of the acceleration of spontaneous superoxide dismutation due to increasing medium acidity. 

Enhancing effect of manganese on L-DOPA-induced apoptosis in PC12 cells Role of oxidative stress. J Neurochem 73 1155-1163. 

Ericksson H, Magiste K, Plantin LO et al Effects of manganese oxide on monkeys as revealed by a combined neurochemical, histological and neurophysiological evaluation. Arch Toxicol 61A6-52, 1987... 

Sunderman FW Jr, McCully KS. 1983. Effects of manganese compounds on carcinogenicity of nickel subsulfide in rats. Carcinogenesis 4 461-465. 

Shen X, Sun L, Benassi E et al (2010) Spin filter effect of manganese phthalocyanine contacted with single-walled carbon nanotube electrodes. J Chem Phys 132 054703/ 1-054703/6... 

Experimental observations indicate that the oxidation of cobalt (II) to cobalt (III) and the formation of ethylenediamine from N-hydroxyethylethylene-diamine occur simultaneously. This is quite the opposite to what is usually assumed in other instances of transition metal catalysis of organic reactions—for example, the catalytic effect of manganese in the oxidation of oxalic acid (7, 8), of iron in the oxidation of cysteine to cystine (22) and of thioglycolic acid to dithioglycolic acid (5, 23), of copper in the oxidation of pyrocatechol to quinone and in the oxidation of ascorbic acid (29, 30), and of cobalt in the oxidation of aldehydes and unsaturated hydrocarbons (4). In all these reactions the oxidation of the organic molecule occurs by the abstraction of an electron by the oxidized form of the metal ion. 

In contrast to the effect of manganese, cupric salt strongly retards the oxidation, reducing the rate of p-xylene by a factor of more than 10 when 20% of cobalt is replaced by cupric acetate. 

Figure 2. Effect of manganese acetate on peracetic acid decomposition at...

Figure 2.16. Changes in the degree of darkening of hydroquinone solution at pH 4.0 and 6.0 as influenced by various oxides as a function of time Reprinted from Shindo, H., and Huang, P. M. (1984). Catalytic effects of manganese(IV), iron(III), aluminum, and silicon oxides on the formation of phenolic polymers. Soil Sci. Soc. Am. J. 48, 927-934, with permission from the Soil Science Society of America.

Sunderman FW, Lau TJ, Cralley LJ. 1974. Inhibitory effect of manganese upon muscle tumorigenesis by nickel subsulfide. Cancer Res 34 92-95. 

Table 2. Effect of manganese concentration on 24-h Mn retention in d 15 rats 1,2,3...

Little is known of the in vivo effect of manganese on cholesterol metabolism. Doisy (6) observed a decrease in serum cholesterol (from 206 to 80 mg/dl) in a single manganese deficient human subject. Reports of other human studies conducted to determine the influence of dietary manganese on cholesterol metabolism were not found. 

Manganese has a further role as a lipotropic agent. Amdur and associates (9) found that hepatic lipid concentration was increased by manganese deficiency. Plumlee et al. (10) conducted four experiments to determine the effect of manganese deficiency in swine and found that total body fat and liver lipid concentrations were increased by manganese deficiency. 

Paul, A., Hauck, M. Fritz, E. (2003). Effects of manganese on element distribution and structure in thalli of the epiphytic lichens Hypogymnia physodes and Lecanora conizaeoides. Environmental and Experimental Botany, 50, 113—24. 

Hage R, Iburg JE, Kerschner J, Koek HH, Lempers E, Martens RJ, Racheria US, Russe WW, Suarthoff T, Vliet M, Warner JB, Wolf L, Krijnen B. Effect of manganese catalysts for low-temperature bleaching. Nature 1994 369 637-639. 

FIGURE 7.7 Effect of manganese, silicon, phosphorus, and sulfur content on critical stress intensity factor for crack extension K j in low-alloy steels. Data are for high-strength steel tested in low-pressure hydrogen gas. 

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