Hydrogen chloride gas for effecting staining of internal structures in Escherichia coli.
The cells were smeared in water or water which had stood over about 10 mg. of magnesium powder per ml. for 30 minutes or longer. After the smear was dry and whitish in appearance it was held over a beaker of hot water (60-65° C.) until it was translucent or becoming translucent and exposed immediately to hydrogen chloride (gas) for a few seconds. After drying, it was covered with a 0.1% aqueous solution of neutral red for 5-8 minutes. The excess stain was washed from the slide with water and, while wet, placed in a saturated aqueous solution of mercuric nitrate for 5-15 seconds. The smear was rinsed in water and allowed to dry. When dry the slide was placed on a 50° C. warm plate and covered with a thin film of a 5% aqueous solution of nigrosin adjusted to a pH of about 3. The film dried quickly and upon cooling was ready for study. The stained material in the cells varied in shape and location with the moisture content of the smear and the time of exposure to hydrogen chloride. In the area of the smear d...
A STUDY OF BACTERIAL SUBSTANCES STAINABLE BY THE HYDROGEN CHLORIDE METHOD
In a recent paper (Chance, 1955) a new procedure was given for staining material inside the cells of Escherichia coli (figure 8). In brief, the procedure was to make a smear on a slide in water and allow it to dry. While the cells in the smear were still moist they were exposed to hydrogen chloride for 1 to 3 sec and then stained with neutral red for 5 to 8 min. The excess stain was washed off with water and the slide placed in a saturated solution of mercuric nitrate for 10 to 15 sec. The slide was removed and washed with water. After drying it was placed on a warm plate and the smear covered with a thin film of nigrosin. The cells were then ready for observation. Since the role of the nigrosin was largely that of a relief stain it will not be considered further. In the above procedure the order of use of the reagents was hydrogen chloride, stain, and mordant. When the reagents were used in this order it could be reasoned, in the light of much of the previous work, that the function of the hydrogen chloride was to hydrolyze the deoxyribonucleic acid in the cell. Later work has shown, however, that the reagents may be used in most any order. For instance the order may be stain, mordant, and hydrogen chloride or it may be mordant, stain, and hydrogen chloride. It should be noted that in either procedure the cells were stained prior to exposure to hydrogen chloride. The results obtained (figures 10 and 11) show clearly that acid hydrolysis of some cell component is not necessary prior to staining by these procedures and strongly indicate that the role of hydrogen chloride in the original procedure is not one of hydrolysis. These findings and the fact that a new method of staining was used make it desirable to investigate the nature of the stainable material. This becomes
ROOM- AND HIGH-TEMPERATURE MAGNETIC PROPERTIES OF Sm(CobalFexCu0.088Zr0.025)7.5 (x=0.30) SINTERED MAGNETS
The effect of Fe content on room- and high-temperature magnetic properties of Sm(CobalFexCu0.088Zr0.025)7.5 (x=0-0.30) sintered magnets, prepared by the conventional powder metallurgy method, has been systematically studied. With increasing Fe content, the remanences BT and maximum energy products (BH)max at room temperature gradually increase and reach optimal values of 1.055 T with x=0.27 for BT, and 205 kJ/m3 with x=0.21 for (BH)max, respectively, and then drop sharply with further Fe increase. An excessive addition of Fe (x≥0.24) results in rapid deterioration of permanent magnetic properties due to the formation of a considerable amount of FeCo soft magnetic phase. It was found that the effect of Fe content on high temperature stability is huge. The lower the Fe content, the smaller the temperature coefficient of coercivity. When x=0.07, a temperature coefficient of coercivity of -0.14%/K (293-723 K) can be achieved, as compared with -0.23%/K for x=0.21. BT of 0.725 T, bHc of 517 kA/m, iHc of 764 kA/m, and (BH)max of 95 kJ/m3 at 723 K were obtained, and the B-H demagnetization curve remains a straight line.