The initial stage of fretting fatigue crack growth is significantly influenced by tangential force induced by fretting action along the contact surface where a mixed-mode crack growth is involved. Fretting crack behavior of aluminum alloy 2024 was studied, taking into account the problem of contact asperities. Finite element was used for the determination of the stress field near the contact su...

An antibiotic is an organic substance produced by a 1)living organism which inhibits the growth of or kills some ,, other living organism. Two. of the more important antibiotic .that have been studied are penicillin and streptomycin. Although three structural formulae for penicillin have been presented, this antibiotic is generally thought of as Ia ring condensation of two amino acids: alanine ...

When Escherichia coli strain B/r is exposed to 10 to 20 mug of nitrofurazone per ml, mutants with roughly threefold resistance are obtained. Treatment of these mutants with higher concentrations of nitrofurazone yields strains with six- to seven-fold resistance over strain B/r. Each of these steps toward nitrofurazone resistance is accompanied by loss of soluble nitrofurazone reductase activity...

Chloramphenicol has been shown to exert a strong inhibitory action on microbial protein synthesis (Gale and Folkes, 1953; Maxwell and Nickel, 1954; Wisseman et al., 1954). Hence, the hypotheses that the antibiotic may act simply as the antagonist of one amino acid or another are especially attractive (Mentzer et al., 1950; Woolley, 1950; Bergmann and Sicher, 1952; Molho and Molho-Lacroix, 1952)...

Streptolydigin and rifamycin inhibit the catalytic function of ribonucleic acid (RNA) polymerase. Streptolydigin can inhibit polymerization after the reaction has started, whereas rifamycin is effective only if it is preincubated with RNA polymerase prior to the addition of substrates. The same relationships are observed with respect to these two antibiotics if the nucleoside triphosphate-pyrop...

In the present discussion, the author summarized the toxicological and biological features of thirty kinds of trichothecene mycotoxins which are produced by a wide range of Fusarium, Myrothecium and others. The 12, 13-epoxytrichothecenes induce nausea, emesis, vomiting, skin inflamation, leukopenia, diarrhea, hemorrhage in lung and brain, and destruction of bone marrow. Since these toxicologica...

The amphibian embryo develops into the three germ layers in a predictable fashion, the pigmented animal pole forming the ectoderm, the yolky vegetal pole forming the endoderm and the mesoderm developing from an annulus at the equator. Mesoderm formation is believed to require a TGF-β family signal originating from vegetal cells because a truncated dominant negative activin receptor, promiscuous...

The activity of netzahualcoyone on Bacillus subtilis and Escherichia coli was studied. The product inhibited the respiration of intact cells of B. subtilis but had no effect on the respiration of E. coli. However, when preparations of sonically disrupted cells were examined, inhibitory activity on both bacteria was observed.