Influence of flow on the corrosion inhibition of carbon steel by fatty amines in association with phosphonocarboxylic acid salts

This work was carried out to study the inhibition mechanism of a carbon steel in a 200 mg l−1 NaCl solution by a non-toxic multi-component inhibitor used for water treatment in cooling circuits. The inhibitive formulation was composed of 50 mg l−1 fatty amines associated with 200 mg l−1 phosphonocarboxylic acid salts. Steady-state current–voltage curves, obtained with a rotating disc electrode, revealed that the properties of the protective layer were dependent on the electrode rotation rate and on the immersion time. The cathodic process of oxygen reduction was not modified in the presence of the inhibitive mixture. As expected, the current densities increased when the rotation rate was increased. In the anodic range, original behaviour was observed: the current densities decreased when the electrode rotation rate increased. The morphology and the chemical composition of the inhibitive layers allowed the electrochemical results to be explained. Two distinct surface areas were visualised on the metal surface and the ratio between the two zones was dependent on the flow conditions. This behaviour was attributed to a mechanical effect linked to centrifugal force. XPS analysis revealed that the formation of a chelate between the phosphonocarboxylic acid salt molecules and the iron oxide/hydroxide was enhanced by the increase of the electrode rotation rate

A study of the possibilities of cooperation between the General Electric Company and Pittsfield School Department in the improvement of the present program of vocational education.

Thesis (M.S.

Base Excision Repair Of Dna In Human Cells: The Apurinic/apyrimidinic Intermediate

Base excision repair of DNA and factors that affect DNA incision in human cells were considered in this study.;Treatment of alkylated HeLa cells with 3-aminobenzamide, and inhibitor of poly(ADP-ribose) polymerase, increased the number of DNA strand breaks but did not slow down their rejoining by DNA repair. Therefore, an increase in DNA incision, not a decrease in ligation, results from the inhibition of poly(ADP-ribose) polymerase in alkylated cells. This is consistent with recent findings by others that suggest that repair-patch frequency is increased in alkylated cells when polyADP-ribosylation is inhibited.;Apurinic/apyrimidinic (AP) sites were measured in HeLa cells by digestion of cellular DNA with Escherichia coli endonuclease IV, an AP-specific endonuclease, prior to alkaline elution. The absence of non-specific endonuclease activity allowed endonuclease IV-sensitive AP sites to be detected with the sensitivity of conventional alkaline elution. Cells that were alkylated with dimethylsulfate, but not benzo(a)pyrene diol epoxide, contained AP sites that were repaired along with DNA single-strand breaks during a post-alkylation recovery period. In addition, alkali-labile sites (that become single-strand breaks in the presence of alkali) other than AP sites were resolved in dimethylsulfate-treated cells by comparing the rate of elution of endonuclease IV-digested DNA at pH 12.1 and pH 12.6. Alkali-labile sites were also observed in benzo(a)pyrene diol epoxide-treated cells. However, these alkali-labile sites were not sensitive to endonuclease IV, and hence are not AP sites.;According to the base excision repair model, the sequential action of DNA glycosylases and AP endonucleases is thought to initiate the repair of DNA base damage. This model was tested in {dollar}\gamma{dollar}-irradiated HeLa cells by endonuclease IV-coupled alkaline elution. AP sites were detected as a transient DNA repair intermediate in {dollar}\gamma{dollar}-irradiated cells. This approach illuminated the operation of base excision repair in human cells by demonstrating the transit of ionizing radiation-induced base lesions, most of which are unknown, through this pathway

The Effect of the Cu:Fe\u27\u27\u27 Ratio Upon the Current Efficiency in the Electrolysis of a Copper Sulfate Solution Containing Iron Sulfate

It is a well-known fact that, in the electrolysis of a CuSO4 solution containing iron sulfate, using insoluble anodes, with the depletion of copper, the point is finally reached where the current efficiency becomes zero. This decrease in current efficiency is due to the oxidation of the ferrous sulfate to the ferric condition at the anode, by the oxygen liberated. The resulting ferric sulfate diffuses over to the cathode and there dissolves copper from the cathode according to the chemical equation Cu + Fe2 (SO4)3 = CuSO4 + 2FeSO4. This copper, which has been deposited at the cathode by the electric current, is thus redissolved by the Fe2(SO4)3. The solution of the copper causes at the same time a formation of FeSO4 which in turn diffuses over to the anode and is there oxidized to Fe2(SO4)3; and so the cycle continues, using electric current without rendering useful work. E. H. Larison has noted that a definite amount of ferric salts must be reduced to the ferrous condition before all the copper will remain on the cathode; he does not state, however, just what this point is. L. Addicks has plotted the relation between current efficiency and ferric sulphate content. The existence of the results scattered the points more or less, although the decrease in current efficiency with increased ferric sulphate content is clearly indicated. E. T.Kern has likewise noted that the smaller the amount of copper in the solution, the greater is the reduction of current efficiency. In this work, therefore, it was desired to determine what amount of ferric iron was permissible in a copper sulfate solution of definite concentration before the current efficiency would drop to zero, and what, if any, was the effect of definite Cu:Fe’’’ratio upon the current efficiency of the electrolysis