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  • 1
    Electronic Resource
    Electronic Resource
    Cathodes for chlorate electrolysis with nanocrystalline Ti–Ru–Fe–O catalyst (2000)
    Springer
    Journal of applied electrochemistry 30 (2000), S. 1061-1067 
    Details
    ISSN: 1572-8838
    Keywords: chlorate electrolysis ; high activity ; hydrogen cathodes ; nanocrystalline Ti–Ru–Fe–O catalyst
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Cathodes for chlorate electrolysis were prepared by mixing nanocrystalline Ti–Ru–Fe–O catalyst powder with small amounts of Teflon and subsequent hot pressing on a carbon–Teflon sublayer. Initially, the electrode materials were characterized by SEM, EDX, XRD and BET measurements. The behaviour of electrodes with catalyst loadings from 300 mg cm−2 reduced to 10 mg cm−2 was investigated in chlorate electrolyte with pH 6.5 and in part, for comparison, in 1 M sodium hydroxide solution at 70 ∘C. Several methods have been used: cyclic voltammetry for the determination of double layer capacitance, Tafel plot analysis, cathodic potentiodynamic polarization and potentiostatic tests at i = −250 mA cm−2. The as-milled catalyst powder electrodes showed a high activity for the HER in chlorate electrolyte particularly expressed in low overpotentials of about 580 mV at −250 mA cm−2 for catalyst loadings down to 20 mg cm−2 and high double layer capacitances in the freshly prepared state. These electrodes show increased activity at low polarization. The long-term stability during electrolysis was also analysed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004030706423
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of oxygen and titanium contents on the stability of nanocrystalline Ti–Ru–Fe–O cathode materials for chlorate electrolysis (2000)
    Springer
    Journal of applied electrochemistry 30 (2000), S. 491-498 
    Details
    ISSN: 1572-8838
    Keywords: ball milling ; chlorate electrolysis ; electrocatalysis ; hydrogen evolution ; nanocrystalline
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Electrodes made from nanocrystalline Ti:Ru:Fe (2−y:1+y/2:1+y/2), with y varying from 0 to 1 by step of 0.25, and Ti:Ru:Fe:O (2:1:1:w), with w varying from 0 to 2 by step of 0.5, were prepared and tested as activated cathodes for the hydrogen evolution reaction in typical chlorate electrolysis conditions. These electrodes were subjected to an accelerated aging test, consisting of a succession of cycles of hydrogen discharge (HER) and open-circuit (OCP) conditions. In addition to monitoring the cathodic overpotential value during the aging test, visual inspection and mass loss measurements were performed on the electrodes at the end of the test to assess their stability. In the case of Ti:Ru:Fe (2:1:1), a large increase of the cathodic overpotential value is observed after 20 cycles. Adding O to the formulation causes a remarkable improvement of the long-term stability of the electrodes. As little as [O] = 10 at.% in nanocrystalline Ti:Ru:Fe:O (2:1:1:w) materials is sufficient for the electrode to show absolutely no sign of degradation after 50 cycles of HER/OCP, the longest accelerated test conducted. Adding more O to the formulation of the material does not lead to further stability improvement. A better stability under the conditions of the accelerated aging test can also be observed for nanocrystalline Ti:Ru:Fe (2−y:1+y/2:1+y/2) materials with y 〉 0. In that case however, the level of improvement is dependent on the value of y. The best results are obtained for y = 0.75. A hypothesis is proposed to explain the improved stability obtained by lowering the Ti content and/or by adding O. The similarity and difference between both ways of improving the stability of the nanocrystalline Ti:Ru:Fe materials are also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003961417762
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  • 3
    Electronic Resource
    Electronic Resource
    Rat folic acid reductase activity during the perinatal period, in newborns, and after trimethoprim administration (1972)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 274 (1972), S. 229-237 
    Details
    ISSN: 1432-1912
    Keywords: Rat Folic Acid Reductase ; Pregnancy ; Fetus ; Newborns ; Trimethoprim
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The folic acid reductase activity in various organs of adult rats was studied in comparison to pregnant females (20th day of gestation) and fetal rats. The enzyme activities in the tissues of pregnant rats were in general about 30% higher than in normal adults. Fetal rats also possess the ability to catalyze the reduction of dihydrofolic acid, but it is evident that the liver and kidney have a considerably reduced capacity to form tetrahydrofolate. The folic acid reductase activity in liver and kidney rises for 10 days after birth and then declines to normal enzyme levels by the 4th week of life. Further studies concerning the interaction between trimethoprim and folic acid reductase in adult rats demonstrate that an oral dose of 5 or 50 mg/kg results in about a 30% increase of folic acid reductase activity in liver and kidney. The experiments suggest that there is a stimulation of enzyme synthesis following trimethoprim administration; because, the trimethoprim induced increase of the reductase activity is blocked by the administration of either puromycin or actinomycin D.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00501932
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  • 4
    Electronic Resource
    Electronic Resource
    Inhibition of rat folic acid reductase activity by trimethoprim during the later stages of gestation (1973)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 278 (1973), S. 227-230 
    Details
    ISSN: 1432-1912
    Keywords: Trimethoprim ; Rat Folic Acid Reductase ; Pregnancy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The increased level of folic acid reductase activity in rats during the perinatal period is inhibited following the oral administration of 5 or 50 mg/kg Trimethoprim. When the enzyme activity was tested in vitro, the highest sensitivity to the antimetabolite was displayed by the liver reductase isolated from rats the 20th day of pregnancy, the lowest was observed in the foetal liver extract. It is proposed that the stimulated reductase activity during the pregnancy is caused by a newly synthesized, Trimethoprim-sensitive enzyme form. The results of the in vitro experiments could contribute to the suggested hypothesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00500653
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    Paper (German National Licenses)
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