38 research outputs found
Three-Particle Correlations in Simple Liquids
We use video microscopy to follow the phase-space trajectory of a
two-dimensional colloidal model liquid and calculate three-point correlation
functions from the measured particle configurations. Approaching the
fluid-solid transition by increasing the strength of the pair-interaction
potential, one observes the gradual formation of a crystal-like local order due
to triplet correlations, while being still deep inside the fluid phase.
Furthermore, we show that in a strongly interacting system the Born-Green
equation can be satisfied only with the full triplet correlation function but
not with three-body distribution functions obtained from superposing
pair-correlations (Kirkwood superposition approximation).Comment: 4 pages, submitted to PRL, experimental paper, 2nd version: Fig.1 and
two new paragraphs have been adde
Triplet correlations in two-dimensional colloidal model liquids
Three-body distribution functions in classical fluids have been theoretically
investigated many times, but have never been measured directly. We present
experimental three-point correlation functions that are computed from particle
configurations measured by means of video-microscopy in two types of
quasi-two-dimensional colloidal model fluids: a system of charged colloidal
particles and a system of paramagnetic colloids. In the first system the
particles interact via a Yukawa potential, in the second via a potential
. We find for both systems very similar results: on increasing
the coupling between the particles one observes the gradual formation of a
crystal-like local order due to triplet correlations, even though the system is
still deep inside the fluid phase. These are mainly packing effects as is
evident from the close resemblance between the results for the two systems
having completely different pair-interaction potentials.Comment: many pages, 8 figures, contribution to the special issue in J.Phys.
Cond. Mat. of the CECAM meeting in LYON ''Many-body....'
Efeito da combinação de metatopolina e 2,4-D na calogênese a partir de explantes foliares de Manihot esculenta E M. fortalezensis.
Somatic embryogenesis in Acrocomia aculeata Jacq. (Lodd.) ex Mart using the thin cell layer technique
Anatomical and physiological modifications of micropropagated 'Caipira' banana plants under natural lighy
In vitro conservation of Piper aduncum and Piper hispidinervum under slow-growth conditions
The objective of this work was to evaluate in vitro storage of Piper aduncum and P. hispidinervum under slow-growth conditions. Shoots were stored at low temperatures (10, 20 and 25°C), and the culture medium was supplemented with osmotic agents (sucrose and mannitol - at 1, 2 and 3%) and abiscisic acid - ABA (0, 0.5, 1.0, 2.0 and 3.0 mg L-1). After six-months of storage, shoots were evaluated for survival and regrowth. Low temperature at 20ºC was effective for the in vitro conservation of P. aduncum and P. hispidinervum shoots. In vitro cultures maintained at 20ºC on MS medium showed 100% survival with slow-growth shoots. The presence of mannitol or ABA, in the culture medium, negatively affected shoot growth, which is evidenced by the low rate of recovered shoots