H2S Addition Research Articles

定速ひずみ法による軟鋼の硫化物割れの研究

Effects of strain rate, applied potential, pH, temperature and H2S concentration on the sulfide cracking of mild steel were studied at constant strain rates by means of an Instron-type tensile test machine. The results obtained are as follows:(1) The susceptibility of sulfide cracking is highest in the strain rate region of 10−6∼10−5 sec−1 and decreases in the higher strain rate region.(2) In both solutions with and without H2S, the lower the pH of solutions the higher is the susceptibility to cracking, which varies almost linearly with pH. The H2S addition to the solution is most effective for the embrittlement at pH 4.7 and above pH 5 the embrittlement index decreases rapidly. The embrittlement indices below pH 4 are almost identical but slightly decrease with the lowering of pH.(3) The susceptibility to the sulfide cracking varies linearly with applied potential, decreasing with anodic polarization and increasing with cathodic polarization.(4) The embrittlement index is highest at 50°C.(5) The change in H2S concentration has little effect on the susceptibility to cracking.(6) The cracking susceptibility is not directly related to the presence of an iron sulfide film on the steel surface.(7) The dissolved species which promotes hydrogen embrittlement in hydrogen sulfide solutions has turned out to be an undissociated, molecular H2S.(8) The sulfide cracking of mild steel is caused by hydrogen embrittlement.(9) The constant strain rate method is suited for quantitative comparison of changes in susceptibility to the hydrogen embrittlement of steel.

Studies on the Physiological Function of the Crop Roots

Considering that the roots are not only the organs from which absorbs the nutrients and water, but also synthesize the various chemical substances necessary for growth, authors investigated the physiological functions of the roots of the rice plant by means of the several treatments, such as the cutting off the roots, low temperature, H2S addition to the culture solutions, and high reduction of the soil. Obtained results are as follows; 1) The cutting off the roots brings about the standstill of the plant growth and simultaneously the marked decrease in the protein content of the shoot with corresponding increase in the non protein nitrogen. 2) The roots apparently possess the functions not only absorbing the nutrients and water, but also maintaining the protein level of the plant. 3) This function is inhibited by the treatments of the roots, such as above mentioned, and the degree of the inhibition changes variously according to the kind of the treatments. 4) The results by means of the paperchromatographical analysis suggest that the protein breakdown brought by the cutting off the roots and low temperature is on account of the inhibition of the process concerning with the polymerization of the amino acids, in the case of high reduction of the soil it comes from the inhibition of the process involving many steps from the formation of α-keto acid to the transamination.