Modeling the effects of particles,interstitials, vacancies and tip geometry on indentation-induced plasticity

In this work, which is a follow-up of an earlier work by the authors in this journal, we discuss the effects of particles, interstitials, vacancies and indenter-tip geometry on indentation-induced plasticity. A nano-indentation model based on a close-packed array of straws was used. Upon indentation with a cylindrical indenter, the results observed in situ, match qualitatively computer atomistic and finite-element simulation models. This model helps explain the phenomenon and physical reasons for annihilation of vacancies. It also shows the strong effect of interstitials on the inception of plasticity at their sites. It shows that a rigid particle acts as a stress concentrator even away from the indenter. On indentation with a flat indenter, curling of atoms at the indenter edges was observed, along with slip lines reported in the literature.     

Characterization and partial purification of <Emphasis Type="Italic">Candida albicans</Emphasis> Secretory IL-12 Inhibitory Factor

Background  

We have previously shown that supernatant from Candida albicans (CA) culture contains a Secretory Interleukin (IL)-12 Inhibitory Factor (CA-SIIF), which inhibits IL-12 production by human monocytes. However, the effect of CA-SIIF on secretion of other cytokines by monocytes is unknown, and detailed characterization of this factor has not been performed.     

Nonselective inhibition of messenger RNA translation by highly purified low molecular weight RNA species from ribosomal salt wash of chick embryonic muscle

A low molecular weight RNA species, in the 70–90 nucleotide size range (iRNA), has been purified from the ribosomal salt wash of chick embryonic muscle by a combination of DEAE-cellulose and hydroxyapatite chromatography. This method yields iRNA free from contaminating tRNA and gives better and more reproducible yields than those obtained with our previous method involving lengthy dialysis of the salt wash. The iRNA at a concentration of 20–80 ng range strongly inhibits the translation of homologous and heterologous mRNAs i.e. chick muscle poly(A)⁺mRNA and rabbit globin mRNA; uncapped mRNA; and poly(A)^-mRNA in micrococcal nuclease-treated reticulocyte lysate indicating that inhibition by iRNA is nonselective in nature. The translation of endogenous globin mRNA and polysomes in the lysate is strikingly less sensitive to iRNA suggesting that the initiation step is primarily affected by iRNA. The iRNA does not appear to be double-stranded RNA. It is concluded that iRNA is distinct from other low molecular weight RNA species described in the literature which modulate protein synthesis in cell-free systems.