Effect Of Various Oxides Research Articles

Ferroxime(II)-catalyzed oxygenation of nitroalkanes by tert-butyl hydroperoxide and its relevance to 2-nitropropane dioxygenase

The complex [Fe(Hdmg) 2(py) 2], referred to as ferroxime(II), was found to be a selective catalyst for the oxidative denitrification of nitroalkanes such as 1-nitroethane, 1-nitropropane, 2-nitropropane, 1-nitropentane and nitrocyclohexane to the corresponding aldehydes or ketones. The oxidation was performed in DMF and EtOH under Ar in the presence of various oxidants such as O 2, TBHP, H 2O 2 at room temperature, and was followed by glc. The substrate specificity of the catalyst either in DMF or EtOH solution shows that there are no significant differences in the conversions with the exception of 1-nitropentane and nitrocyclohexane. The effect of various oxidants shows that the catalytic oxidations were effective only with TBHP and H 2O 2. No oxidation products could be detected when O 2 was used. The best conversions (TN) have been obtained with TBHP in EtOH (up to 24%, TN=9.3), followed by H 2O 2 (1.7%, TN=0.5).

Peroxynitrite formed by simultaneous generation of nitric oxide and superoxide selectively inhibits bovine aortic prostacyclin synthase

The effect of various oxidants on bovine aortic prostacyclin synthase was tested with 14C-labelled prostaglandia endoperoxide as substrate. No sensitivity against hydrogen peroxide, superoxide or hydroxyl radicals was observed but hypochlorite inhibited with an IC 50 value of 7 μM. Among the reactive nitrogen species nitric oxide and nitrogen dioxide radicals were ineffective, but peroxynitrite irreversibly blocked prostacyclin biosynthesis with an IC 50 value of 50 nM. Peroxynitrite acted within seconds whereas hypochlorite required up to 30 min for completion. Simultaneous generation of nitric oxide and superoxide also caused inhibition which suggested that under pathological conditions like ischemia-reperfusion not only the vasodilatory effects of nitric oxide but also those of prostacyclin could be eliminated.

The effects of impurity oxides on YBa 2Cu 3O 7− x microstructure development

Diffusion-couple experiments in conjunction with scanning electron (SEM) and energy dispersive X-ray analysis were used to determine the effect of various oxides on the microstructural development of YBa 2Cu 3O 7− x ceramic superconductors. The interaction of a number of impurity oxides including SiO 2, Bi 2O 3, Pr 6O 11, TiO 2, SnO 2, In 2O 3 and Sb 2O 3 resulted in exaggerated grain growth and domain formation in bulk specimens through a liquid-phase wetting mechanism. Reaction sequencing was determined by thermal analysis (DTA) and real-time dynamic X-ray diffraction. The ability and extent of domain formation for samples coupled with SiO 2, Bi 2O 3, Pr 6O 11 and TiO 2 was determined to be a function of oxygen partial pressure during sintering as well as of the sintering temperature in the range 940°C–980°C. The use of Bi 2O 3 coupled to pre-oriented samples (i.e. hot forged) resulted in extensive domain growth at 980°C. The presence of SiO 2 in conjunction with hot forging resulted in a lower magnetization response, due to the presence of larger 211 particles and or extensive cracking during sintering.

Oxidative Inactivation of Plasmin and Other Serine Proteases by Copper and Ascorbate

AbstractFibrin thrombi form at sites of injury, where leukocytes release a variety of oxidants. To determine whether oxidants might affect proteins of the fibrinolytic system, we examined the effects of various oxidants on plasmin. Plasmin was not inhibited by micromolar concentrations of hypo-chlorous acid, chloramine T, or H2O2. Neither Fe nor Cu affected plasmin alone or in the presence of H2O2 ▪ However, incubation of plasmin with 5 μmol/L Cu(l or II) in the presence of the reducing agent ascorbic acid resulted in a loss of its hydrolytic activity towards proteins as well as towards small synthetic substrates. The addition of EDTA, but not mannitol, prevented its inactivation. Inactivation was prevented by the addition of catalase and accelerated by hydrogen peroxide. Preincubation of plasmin with the competitive inhibitor α-N-acetyl-L-lysine methyl ester prevented inactivation by Cu(ll) and ascorbate. These results together suggest site-specific oxidation of plasmin's active site. Treatment of the plasminogen activators tissue plasminogen activator and two-chain urokinase-type plasminogen activator, as well as trypsin, neutrophil elastase, and thrombin with Cu(ll) and ascorbate resulted in a loss of their amidolytic and proteolytic activity, indicating the general susceptibility of serine proteases to this type of oxidation. Oxidation of the zymogens Glu-plasminogen and single-chain urokinase-type plasminogen activator by Cu(ll) and ascorbate resulted in the failure of these molecules to generate active enzymes when treated with plasminogen activators or plasmin, respectively. The active site His residue may be the target of oxidative inactivation, as evidenced by the partial protection afforded plasmin by the addition of Zn(ll), histidine, or the platinum derivative, plati-num(ll)(2,2:6,2“-terpyridine) chloride. Because platelets contain micromolar concentrations of Cu and leukocytes are rich in ascorbate, Cu-dependent site-specific oxidation might play a role in modulating proteolytic events and the life span of thrombi formed at sites of tissue injury.

Oxidative inactivation of plasmin and other serine proteases by copper and ascorbate

Fibrin thrombi form at sites of injury, where leukocytes release a variety of oxidants. To determine whether oxidants might affect proteins of the fibrinolytic system, we examined the effects of various oxidants on plasmin. Plasmin was not inhibited by micromolar concentrations of hypochlorous acid, chloramine T, or H2O2. Neither Fe nor Cu affected plasmin alone or in the presence of H2O2. However, incubation of plasmin with 5 mumol/L Cu(I or II) in the presence of the reducing agent ascorbic acid resulted in a loss of its hydrolytic activity towards proteins as well as towards small synthetic substrates. The addition of EDTA, but not mannitol, prevented its inactivation. Inactivation was prevented by the addition of catalase and accelerated by hydrogen peroxide. Preincubation of plasmin with the competitive inhibitor alpha-N-acetyl-L-lysine methyl ester prevented inactivation by Cu(II) and ascorbate. These results together suggest site-specific oxidation of plasmin's active site. Treatment of the plasminogen activators tissue plasminogen activator and two-chain urokinase-type plasminogen activator, as well as trypsin, neutrophil elastase, and thrombin with Cu(II) and ascorbate resulted in a loss of their amidolytic and proteolytic activity, indicating the general susceptibility of serine proteases to this type of oxidation. Oxidation of the zymogens Glu-plasminogen and single-chain urokinase-type plasminogen activator by Cu(II) and ascorbate resulted in the failure of these molecules to generate active enzymes when treated with plasminogen activators or plasmin, respectively. The active site His residue may be the target of oxidative inactivation, as evidenced by the partial protection afforded plasmin by the addition of Zn(II), histidine, or the platinum derivative, platinum(II) (2,2′:6′,2″- terpyridine) chloride. Because platelets contain micromolar concentrations of Cu and leukocytes are rich in ascorbate, Cu-dependent site-specific oxidation might play a role in modulating proteolytic events and the life span of thrombi formed at sites of tissue injury.

Promotion effects of various oxides on oxidation of benzene over vanadium pentoxide catalysts

The effect of promoters on the activity and selectivity of the active sites was investigated in the selective oxidation of benzene over vanadium pentoxide catalysts. The activity per surface area is increased by addition of MoO 3, WO 3, P 2O 5 and SnO 2, but the activity of each redox sites, i.e., turnover frequency (TF), was not. This indicates that the promoters enhanced the activity by increasing the redox sites, such as the surface V O species. The selectivity to maleic anhydride (MA) was improved by the addition of MoO 3, WO 3 and P 2O 5, while it was lowered by SnO 2. The effect on the selectivity was discussed in the light of the electronegativity of promoter cations. The additions of MoO 3, WO 3 and P 2O 5, of which the cations are more electronegative than V 5+, decreased TF of the production of carbon oxides more seriously than that of MA. On the other hand, the addition of less electronegative cation, i.e., Sn 4+, increased TF of the production of carbon oxides at the sacrifice of MA.

Systematic Composition Studies on the Durability of Waste Glass WV205

AbstractA systematic study of the chemical durability of glass compositions developed for the immobilization of high-level radioactive wastes at West Valley is described. Most of the compositions studied here represent variations around the nonradioactive WV205 composition. The results from this study indicate that the effectiveness of the various oxides tested in increasing the durability of WV205, when considered in terms of 2% additions by weight to the central composition, decreases in the following order: A12O3>ZrO2>SiO2>Cr2O3>Fe2O3>TiO2>CuO>ZnO>NiO. The addition of 2–6% Cr2O3 or NiO to WV205 was observed to cause extensive crystallization. The addition of 2% or 6% ZnO or 2% TiO2, CuO or NiO to the glass actually enhances corrosion rates. A12O3 and ZrO2 are the best additives in terms of increasing the durability. The additions of ThO2 and U3O8 slightly increase the durability. The effects of various oxides on the durability of WV-205-based glasses with ThO2 and U3O8 were found to be very similar to the effects of these oxides on the durability of the corresponding glasses which did not contain ThO2 and U3O8. This study also showed that Fe2O3 has little effect on the durability. However, FeO greatly enhances the corrosion rates of WV205-based glasses. Much less pronounced effects of the redox state of iron were found in the case of more durable base glass compositions.

The Effect of Various Oxidants on the Performance of Activated Carbon used in Water Reclamatoin

Abstract Pilot plant studies were conducted in parallel to determine the effect of pre-chlorination, pre-ozonation and pre-oxygenation on biological activated carbon (BAC). Pre-ozonation resulted in longer life for the activated carbon treating high quality secondary effluent but not when treating primary effluent clarified with alum. The effect is probably due to a relative increase in the proportion of biodegradable to non-biodegradable compounds in the secondary effluent. Oxygenation and chlorination did not discernibly extend activated carbon life.

シリカ飽和スラッグ中FeOの活量について

The general relationship between oxygen in the liquid iron and iron oxide in the slag is well understood as the distribution of oxygen.There are many reports dealing with the equilibrium between ternary slag FeO-CaO-SiO2 and FeO-MnO-SiO2 and oxygen in the liquid iron. And also, thermodynamical consideration on the variation in chemical properties of oxides in the slag has been made by many workers. It is, however considered that their theories involved in themselves some questions and assumptions. Authors measured the effects of the following oxides, namely, CaO, Al2O3, MnO, CrO, on the distribution of oxygen and examined the distribution coefficients of chromium for the quaternary system, FeO-CrO-CaO-SiO2 saturated with silica and liquid Fe-Cr alloy.Authors discussed on the questions whether or not the distribution of chromium in this system could be given as a linear function of iron oxide as shown by KORBER et al., or activity of iron oxide, the same as FeO-CrO-MnO-SiO2 system reported previously by authors.The equilibrium between the molten iron and the slag was studied in the silica crucible at 1600°C. The results obtained are summarized as follows.1) The effects of various oxides on the silica content in the silica saturated slag correspond to the melting point of its silicate.2) The solubility of oxygen decreases with an increase in the added oxide in FeO-SiO2 system. It is recognized that there exists some relationship between the diminution rate of oxygen and the strength in terms of the basicity of added oxide.3) The effects of various oxides on the activity of iron oxide are relatedwith the strength in terms of the basicity of added oxide. The activity of iron oxide was representedby the following empirical formula.aFeO=0.388-(1.30NM2+-1.14N2M2+)/√Iwhere I refers to the ion-oxygen attraction.4) The equilibrium relation between three forms of oxygen in silicate melts as shown by RICHARDSON was studied for the ternary slags saturated with silica.The concentration of (O2-) was abruptly changed with the variation of cation in silica saturated slag.5) Distribution of chromium was obtained for the quaternary slag FeO-CaO-CrO-SiO2. The results show that the distribution coefficient of chromium is affected by CaO. And it can not be represented by the concentration of iron oxide as shown by KORBER et al., but by the activity of iron oxide. It showed good agreement with the results reported previously for the system FeO-CrO-MnO-SiO2 by authors.6) Expedient method of calculating the activity of iron oxide in the quaternary system can be obtained by using the activity of iron oxide in ternary system. The calculated values showed close agreement with the experimental results.

Argentaffin and Schiff reactions after periodic acid oxidation and aldehyde blocking reactions.

selective bistochemical localization of aldehydes. This belief undoubtedly rests on the statements of the organic chemists regarding the reactions of aldehydes. Karrer (10) states : “Ammoniacal silver solutions are reduced to the metal on warming with aldehydes”. Fieser and Fieser (5) state that aldehydes can be distinguished from ketones by their ability to reduce a solution of silver nitrate in an excess of ammonia to the metaffic state. But Feigi (4) does not include the reaction among his “spot tests” as specific for identification of aldehydes. Among the users of the reaction for histochemical purposes Pearse (14) states: “The reaction with ammoniacal silver solutions, in particular, is regarded as specific for aldehydes.” And Gomori (8) writes: “Another good analytical reagent for aldehydes is an alkaline solution of silver nitrate.” but points out that ascorbic acid, polyphenols, uric acid, etc. also exhibit the argentaffin reaction. Lison (13), discussing the argentaffin reaction of polyphenols, interpolates: “par exemple, les aldehydes la donnent aussi.” aldehydes give it also. Chu (3) utilized Gomori’s methenamine silver (pH 8.4) for the histochemical demonstration of aldehydes produced from a-amino acids by hypochlorite, chloramine T or ninhydrin. In the discussion following his paper, he insisted that this silver reaction was a true argentaffin reaction with aldehydes, while Seligman (15) asked whether other aldehyde reagents had been used to confirm the silver reaction, and Gomori (9) warned that methenamine silver ultimately blackens everything. No one questioned the validity of the methenamine silver method as an aldehyde reaction. G. C. Zorzoli (16) also refers to partial blackening of nerve cell (lipofuscin) pigment by the Masson argentaffin technic as due to a weak aldehydic function of the pigment, and (17) quotes Lison that aldehydes are also argentaffin. Glick (7), however, does not include the argentaffin reaction even as an alternative method for aldehyde localization and states, in relation to its use for localization of polyphenols: “The argentaffin test is quite unspecific, since many reducing substances can likewise give a positive reaction.” it is universally recognized that acid formaldehyde solutions rapidly reduce the silver in sections previously impregnated with ammoniacal silver solution. But it is also obvious that in combination with ammonia as methenamine, formaldehyde no longer reduces alkaline silver solutions. The conditions of the argentaffin reaction are such that “aldehyde” must stifi be capable of reacting in the presence of ammine complexes or even free ammonia. In the course of study of the effects of various oxidants on the argentaffin reaction of enterochromaffin, I observed that this reaction was largely or com-