نتایج جستجو برای: nucleation
تعداد نتایج: 18405 فیلتر نتایج به سال:
Despite the relevance to most aspects of crystallization, a comprehensive understanding of the kinetics of heterogeneous nucleation has not been well established yet. In this paper, a new kinetic model based on the ‘‘steady-state’’ approach will be put forward to describe both heterogeneous and homogeneous nucleation. As a key point in this model, the effect of foreign particles on both the nuc...
Organization of microtubules into ordered arrays involves spatial and temporal regulation of microtubule nucleation. Here, we show that acentrosomal microtubule nucleation in plant cells involves a previously unknown regulatory step that determines the geometry of microtubule nucleation. Dynamic imaging of interphase cortical microtubules revealed that the ratio of branching to in-bundle microt...
Dislocation nucleation is central to our understanding of the onset of plasticity during nanoindentation. The shear stress in small volumes beneath the nanoindenter can achieve the theoretical limit of a perfect crystal. The ensuing nonlinear elastic instability can trigger homogenous dislocation nucleation inside the crystal. Here we employ the interatomic potential finite element method to si...
Nucleation of vortex rings accompanies the collapse of ultrasound bubbles in superfluids. Using the Gross-Pitaevskii equation for a uniform condensate we elucidate the various stages of the collapse of a stationary spherically symmetric bubble and establish conditions necessary for vortex nucleation. The minimum radius of the stationary bubble, whose collapse leads to vortex nucleation, was fou...
Homogeneous nucleation of a vapor in the presence of the loss of clusters by diffusion and thermophoretic drift is investigated. Analytical results are obtained for the cluster size distribution and the rate of nucleation by solving the modified kinetic equation for nucleation. The implications of cluster loss by diffusion and phoretic drift on the onset of the homogeneous nucleation of silicon...
Experimental results on bubble nucleation in the solid-state polystyrene–nitrogen system are presented. It was found that the bubble nucleation occurs over a period of approximately 30 s, and is not instantaneous as previously suggested. Over the range of nitrogen pressures explored, 4–14 MPa, the cell nucleation density increased exponentially. However this increase was many orders of magnitud...
Nucleation from solution is a ubiquitous process that plays important roles in physics, chemistry, engineering, and material science. Despite its importance, nucleation is far from being completely understood. In this work (pp. E6–E14), we combine advanced molecular-dynamics simulation techniques and theory to provide a description of urea nucleation from aqueous solution. In particular, our an...
We find that profilin contributes in several ways to Cdc42-induced nucleation of actin filaments in high speed supernatant of lysed neutrophils. Depletion of profilin inhibited Cdc42-induced nucleation; re-addition of profilin restored much of the activity. Mutant profilins with a decreased affinity for either actin or poly-l-proline were less effective at restoring activity. Whereas Cdc42 must...
[1] Several different ice nucleation parameterizations in two different General Circulation Models (GCMs) are used to understand the effects of ice nucleation on the mean climate state, and the Aerosol Indirect Effects (AIE) of cirrus clouds on climate. Simulations have a range of ice microphysical states that are consistent with the spread of observations, but many simulations have higher pres...
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