13,886 research outputs found
Ion specificity and the theory of stability of colloidal suspensions
A theory is presented which allow us to accurately calculate the critical
coagulation concentration (CCC) of hydrophobic colloidal suspensions. For
positively charged particles the CCC's follow the Hofmeister (lyotropic)
series. For negatively charged particles the series is reversed. We find that
strongly polarizable chaotropic anions are driven towards the colloidal surface
by electrostatic and hydrophobic forces. Within approximately one ionic radius
from the surface, the chaotropic anions loose part of their hydration sheath
and become strongly adsorbed. The kosmotropic anions, on the other hand, are
repelled from the hydrophobic surface. The theory is quantitatively accurate
without any adjustable parameters. We speculate that the same mechanism is
responsible for the Hofmeister series that governs stability of protein
solutions.Comment: Phys. Rev. Lett. (in press
Estimação de parcelas perdidas em experimentos agrícolas utilizando-se o PROC GLM do SAS.
Introdução; Desenvolvimento e programas; Programa para estimação de parcelas perdidas em blocos ao acaso; Programa para estimação de parcelas perdidas em quadrado latino.bitstream/CNPA/14623/1/DOC76.pd
Comportamento de cultivares de coqueiros em dois locais dos Tabuleiros Costeiros.
bitstream/item/35491/1/f-11.pd
Immunization and Aging: a Learning Process in the Immune Network
The immune system can be thought as a complex network of different
interacting elements. A cellular automaton, defined in shape-space, was
recently shown to exhibit self-regulation and complex behavior and is,
therefore, a good candidate to model the immune system. Using this model to
simulate a real immune system we find good agreement with recent experiments on
mice. The model exhibits the experimentally observed refractory behavior of the
immune system under multiple antigen presentations as well as loss of its
plasticity caused by aging.Comment: 4 latex pages, 3 postscript figures attached. To be published in
Physical Review Letters (Tentatively scheduled for 5th Oct. issue
Utilização da técnica de SSH para detectar a expressão diferencial de genes de defesa ao nemátode da madeira do pinheiro
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