A level-set method for the simulation of fluid interfaces with insoluble surfactant is presented in two-dimensions. The method can be straightforwardly extended to three-dimensions and to soluble surfactants. The method couples a semi-implicit discretization for solving the surfactant transport equation recently developed by Xu and Zhao  with the immersed interface method originally developed by LeVeque and Li and  for solving the fluid flow equations and the Laplace-Young boundary conditions across the interfaces. Novel techniques are developed to accurately conserve component mass and surfactant mass during the evolution. Convergence of the method is demonstrated numerically. The method is applied to study the effects of surfactant on single drops, dropdrop interactions and interactions among multiple drops in Stokes flow under a steady applied shear. Due to Marangoni forces and to nonuniform Capillary forces, the presence of surfactant results in larger drop deformations and more complex drop-drop interactions compared to the analogous cases for clean drops. The effects of surfactant are found to be most significant in flows with multiple drops. To our knowledge, this is the first time that the level-set method has been used to simulate fluid interfaces with surfactant.
International audienceCompared to precipitation extremes calculated from a high-resolution daily observational dataset in China during 1960–2005, simulations in 31 climate models from phase 5 of the Coupled Model Intercomparison Project (CMIP5) have been quantitatively assessed using skill-score metrics. Four extreme precipitation indices , including the total precipitation (PRCPTOT), maximum consecutive dry days (CDD), precipitation intensity (SDII), and fraction of total rainfall from heavy events (R95T) are analyzed. Results show that CMIP5 models still have wet biases in western and northern China. Especially in western China, the models' median relative error is about 120% for PRCPTOT; the 25th and 75th percentile errors are of 70% and 220%, respectively. However, there are dry biases in southeastern China, where the underestimation of PRCPTOT reach 200 mm. The performance of CMIP5 models is quite different between western and eastern China. The simulations are more reliable in the east than in the west in terms of spatial pattern and interannual variability. In the east, precipitation indices are more consistent with observations, and the spread among models is smaller. The multimodel ensemble constructed from a selection of the most skillful models shows improved behavior compared to the all-model ensemble. The wet bias in western and northern China and dry bias over southeastern China are all decreased. The median of errors for PRCPTOT has a decrease of 69% and 17% in the west and east, respectively. The good reproduction of the southwesterlies along the east coast of the Arabian Peninsula is revealed to be the main factor explaining the improvement of precipitation patterns and extreme events
A combination of theory and experiment is used to identify a novel variable excitonic coupling in a series of building blocks for small phenylacetylene dendrons. Systematic changes in the experimental emission spectra, radiative lifetimes, and polarization anisotropies as the number of meta-conjugated branches increases provide evidence for a qualitative change in the electronic structure in the relaxed excited state. The excited state electronic structure is investigated theoretically using ab initio CASSCF and CASPT2 calculations, which indicate the presence of large electronic coupling in the emitting geometry that is not seen for the absorbing geometry of the same molecules. The changes in electronic structure that occur upon excited-state relaxation can be understood in terms of a variable excitonic coupling between the phenylactylene branches, which takes these molecules from the weak coupling to the strong coupling regime as they relax on the excited state. The origin of this geometry-dependent coupling is investigated through the interpretation of ab initio calculations in terms of Fo ¨rster, Dexter, and through-bond charge-transfer interactions. We find that the change in the coupling arises primarily from an increase in the through-bond or charge-transfer component of the coupling, despite the absence of large changes in charge distribution. A theoretical comparison of metaversus para-substituted phenylacetylenes clarifies why this effect is so pronounced in the meta-substituted molecules.
Treatment with TXA is effective in reducing blood loss in patients undergoing CS. Although the study was not adequately powered to address safety issues, the observed side effects were mild and transient.
Spleen tyrosine kinase (Syk) is an attractive drug target in autoimmune, inflammatory, and oncology disease indications. The most advanced Syk inhibitor, R406, 1 (or its prodrug form fostamatinib, 2), has shown efficacy in multiple therapeutic indications, but its clinical progress has been hampered by dose-limiting adverse effects that have been attributed, at least in part, to the off-target activities of 1. It is expected that a more selective Syk inhibitor would provide a greater therapeutic window. Herein we report the discovery and optimization of a novel series of imidazo[1,2-a]pyrazine Syk inhibitors. This work culminated in the identification of GS-9973, 68, a highly selective and orally efficacious Syk inhibitor which is currently undergoing clinical evaluation for autoimmune and oncology indications.
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