Potential application of mesh-free SPH method in turbulent river flows

A comprehensive review has been completed on the simulation of turbulent flow over rough beds using mesh-free particle models. Based on the outcomes of this review, an improved Smoothed Particle Hydrodynamics (SPH) method has been developed for open channel flows over a rough bed, in which a mixing length model is used for modeling the 2D turbulence and a drag force equation is proposed for treating the boundary shear. The proposed model was applied to simulate a depth-limited open channel flow over a rough bed surface. The results of the velocity profile and shear stress distribution show a good agreement with the experimental data and existing analytical solutions. This work reveals that in order to correctly model turbulent open channel flow over a rough bed, the treatment of both flow turbulence and bed roughness effect is equally important

Tailoring Stimuli Responsiveness using Dynamic Covalent Cross-Linking of Poly(vinyl alcohol)-Heparin Hydrogels for Controlled Cell and Growth Factor Delivery

Heparin-based hydrogels are attractive for cell encapsulation and drug delivery because of the ability of heparin to bind native proteins. However, heparin-based hydrogels have received little attention for their potential as stimuli-sensitive materials. Biosynthetic, poly(vinyl alcohol) (PVA)-heparin hydrogels were formed using dynamic, covalent cross-linking. Hydrogel stimuli-sensitivity was tailored by tuning the concentration of heparin to PVA. Relatively thermally and pH stable hydrogels were produced when formed from only the synthetic, nonionic PVA polymer cross-linked via hydrazone bonds. Cross-linking in the ionic biopolymer heparin, to form PVA-heparin gels, has a profound impact on thermal stability, with degradation ranging from over 6 months to only 4 days across 25-50°C. PVA-heparin hydrogels degrade within 18 days at basic pH (10), while not fully degrading over 6 months at lower pH (4, 7.4). This finding is attributed to the anionic repulsion of carboxyls and sulfates in heparin. PVA-heparin macromers were cytocompatible and enabled mild cell encapsulation, in addition to providing pH-controlled growth factor release. Overall, it is demonstrated that the biopolymer heparin can be used to create pH and temperature-responsive hydrogel biomaterials for cell and drug delivery

How best to link poverty reduction and debt sustainability in IMF-World Bank models?

This paper attempts to provide an economic model in the context of developing countries to address the policy strategies related to poverty reduction. With a view to deal with the shortcomings of the existing approaches as regards poverty reduction, this paper develops a model on the basis of the policy framework of the IMF and the World Bank to show how demand growth can be a crucial mechanism in determining the potential rate of growth, and then to suggest ways in which poverty—conceptualised officially in absolute terms with a subjective cut-off point (e.g. US $1/$2 a day), and a new objective measure in terms of consumption deprivation—can be linked with the key policy variables contained in the adjustment programmes. A strategy of investment in infrastructure and in human development, and improving access to credit markets, particularly in rural areas to encourage or 'crowd in' private investment is a precondition for growth and poverty alleviation. Debt relief can only provide a temporary, not a sustainable, solution to the problem of reducing poverty.Stabilisation, growth, poverty reduction, debt sustainability,