Experiments on the dynamic wetting of growing icicles

The distinctive shape of an icicle is the outcome of a highly non-equilibrium process involving heat and mass transport in the presence of fluid flowing over an evolving topography. It has previously been shown that the ripple patterns with a near universal wavelength that are observed on many icicles are correlated with small levels of impurities in the feed water. Models of icicle shape evolution, and of the origin of the ripple pattern, require a detailed understanding of how liquid water flows over a growing icicle. The impurity effect is not accounted for by any existing model of ripple formation. Here, we explore this flow dynamics using laboratory-grown icicles with a fluorescent dye as an impurity. Contrary to previous models, we find that the ice is incompletely wetted by the liquid phase, and that the whole process is much more stochastic than has been previously assumed. In addition, the presence of impurities modifies the wetting properties of the ice surface, while the emerging topography interacts with the liquid distribution. There is evidence for mixed-phase ice. These observations must inform any successful model of an impurity-driven rippling instability. Our results have general implications for the morphological evolution of many natural, gravity-driven, wet ice growth processes.

Impurity effect on hysteric magnetoconductance: holographic approach

In this paper we study a hysteric phase transition from weak localization phase to hysteric magnetoconductance phase using gauge/gravity duality. This hysteric phase is triggered by a spontaneous magnetization related to ℤ2 symmetry and time reversal symmetry in a 2+1 dimensional system with momentum relaxation. We derive thermoelectric conductivity formulas describing non-hysteric and hysteric phases. At low temperatures, this magnetoconductance shows similar phase transitions of topological insulator surface states. We also obtain hysteresis curves of Seebeck coefficient and Nernst signal. It turns out that our impurity parameter changes magnetic properties of the dual system. This is justified by showing increasing susceptibility and the spontaneous magnetization with increasing impurity parameter.

Tuning of Quantum Entanglement of a Superconductor by Transition-Metal and Rare-Earth Impurity Effect and the Role of Potential Scattering on Quantum Phase Transition

By considering transition-metal (Shiba-Rusinov model) and rare-earth metal impurities (Abrikosov-Gorkov theory) effect on a many-body system, i.e., a BCS s-wave superconductor, quantum bipartite entanglement of two electrons of the Cooper pairs in terms of the exchange interaction, J, the potential scattering, V(playing an important role, unexpectedly), and the distance of two electron spins of the Cooper pair is calculated at zero temperature by using two-electron spin-space density matrix (Werner state). In transition-metal case, we find new quantum phase transitions (QPTs). The changes of J, which causes to have localized excited state, V and the pairing interaction (via energy gap) lead to the displacement of the QPTs (interactions act in the same direction, however sometimes the pairing interaction causes the competition with other interactions), regardless of their effects on the value of concurrence. Determining the allowable values of all interactions by itself is not possible, due to the smallness of the perturbed Green’s functions (appearing in the density matrix). For non-magnetic and magnetic (rare-earth) impurity cases, concurrence versus the distance and collision times is discussed for all finite and infinite Debye frequency. The quantum correlation, instability of the system and what's more important QPT can be tuned by the impurity.

Curse or Blessing? Influence of Impurities on Cross-Coupling— Guideline for Elucidating Catalysts

Several efforts have been made for the replacement of noble metal palladium in cross-coupling reactions, maintaining high efficiency of the target transformation. In several cases it is possible to perform the chemistry of palladium with related metals, and their activity was supported with mechanistic studies. Moreover, the complete exclusion of palladium is also in focus. Very recently it was demonstrated that special amine organocatalysts could catalyse Suzuki-Miyaura coupling reaction. Here we show that in this recent transformation homeopathic palladium impurities and trace phosphorous species originated from the conditions used for the organocatalyst synthesis are responsible for the catalytic effect instead of the amine species. This finding confirms the power of palladium in cross-coupling and draw the attention of impurity effect in this field of chemical research. In this article, we represent general guidelines for elucidating the real catalyst of reactions.<br>

Curse or Blessing? Influence of Impurities on Cross-Coupling— Guideline for Elucidating Catalysts

Several efforts have been made for the replacement of noble metal palladium in cross-coupling reactions, maintaining high efficiency of the target transformation. In several cases it is possible to perform the chemistry of palladium with related metals, and their activity was supported with mechanistic studies. Moreover, the complete exclusion of palladium is also in focus. Very recently it was demonstrated that special amine organocatalysts could catalyse Suzuki-Miyaura coupling reaction. Here we show that in this recent transformation homeopathic palladium impurities and trace phosphorous species originated from the conditions used for the organocatalyst synthesis are responsible for the catalytic effect instead of the amine species. This finding confirms the power of palladium in cross-coupling and draw the attention of impurity effect in this field of chemical research. In this article, we represent general guidelines for elucidating the real catalyst of reactions.<br>