114 research outputs found
Rheological properties vs Local Dynamics in model disordered materials at Low Temperature
We study the rheological response at low temperature of a sheared model
disordered material as a function of the bond rigidity. We find that the flow
curves follow a Herschel-Bulkley law, whatever is the bond rigidity, with an
exponent close to 0.5. Interestingly, the apparent viscosity can be related to
a single relevant time scale , suggesting a strong connection between
the local dynamics and the global mechanical behaviour. We propose a model
based on the competition between the nucleation and the avalanche-like
propagation of spatial strain heterogeneities. This model can explain the
Herschel-Bulkley exponent on the basis of the size dependence of the
heterogeneities on the shear rate.Comment: 9 pages, 7 figure
Alteration of ribosome function upon 5-fluorouracil treatment favors cancer cell drug-tolerance.
Mechanisms of drug-tolerance remain poorly understood and have been linked to genomic but also to non-genomic processes. 5-fluorouracil (5-FU), the most widely used chemotherapy in oncology is associated with resistance. While prescribed as an inhibitor of DNA replication, 5-FU alters all RNA pathways. Here, we show that 5-FU treatment leads to the production of fluorinated ribosomes exhibiting altered translational activities. 5-FU is incorporated into ribosomal RNAs of mature ribosomes in cancer cell lines, colorectal xenografts, and human tumors. Fluorinated ribosomes appear to be functional, yet, they display a selective translational activity towards mRNAs depending on the nature of their 5'-untranslated region. As a result, we find that sustained translation of IGF-1R mRNA, which encodes one of the most potent cell survival effectors, promotes the survival of 5-FU-treated colorectal cancer cells. Altogether, our results demonstrate that "man-made" fluorinated ribosomes favor the drug-tolerant cellular phenotype by promoting translation of survival genes
Atomistic simulations of elastic and plastic properties in amorphous silicon
We present here potential-dependent mechanical properties of amorphous silicon studied through molecular dynamics (MD) at low temperature.
On average, the localization of elementary plastic events and the co-ordination defect sites appears to be correlated. For Tersoff potential and SW potential the plastic events centered on defect sites prefer 5-fold defect sites, while for modified Stillinger-Weber potential such plastic events choose 3-fold defect sites. We also analyze the non-affine displacement field in amorphous silicon obtained for different shear regime.
The non-affine displacement field localizes when plastic events occur and shows elementary shear band formation at higher shear strains
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