3D-Printability of PPG-poly(hydroxyurethane) elastomers using thermal or UV curing processes

The abstract is provided as supporting informatio

Functionalization of polyhydroxyurethanes by α-alkylidene cyclic carbonates towards new elastomers for 3D-printed biomedical devices

The abstract is provided as supporting informatio

Design, manufacturing and testing of a green non-isocyanate polyurethane prosthetic heart valve.

peer reviewedThe sole effective treatment for most patients with heart valve disease is valve replacement by implantation of mechanical or biological prostheses. However, mechanical valves represent high risk of thromboembolism, and biological prostheses are prone to early degeneration. In this work, we aim to determine the potential of novel environmentally-friendly non-isocyanate polyurethanes (NIPUs) for manufacturing synthetic prosthetic heart valves. Polyhydroxyurethane (PHU) NIPUs are synthesized via an isocyanate-free route, tested in vitro, and used to produce aortic valves. PHU elastomers reinforced with a polyester mesh show mechanical properties similar to native valve leaflets. These NIPUs do not cause hemolysis. Interestingly, both platelet adhesion and contact activation-induced coagulation are strongly reduced on NIPU surfaces, indicating low thrombogenicity. Fibroblasts and endothelial cells maintain normal growth and shape after indirect contact with NIPUs. Fluid-structure interaction (FSI) allows modeling of the ideal valve design, with minimal shear stress on the leaflets. Injection-molded valves are tested in a pulse duplicator and show ISO-compliant hydrodynamic performance, comparable to clinically-used bioprostheses. Poly(tetrahydrofuran) (PTHF)-NIPU patches do not show any evidence of calcification over a period of 8 weeks. NIPUs are promising sustainable biomaterials for the manufacturing of improved prosthetic valves with low thrombogenicity

3D-Printability of PPG-poly(hydroxyurethane) elastomers using thermal and UV curing processes

No abstract is availabl

Thermal and UV curable formulations of poly(propylene glycol)−poly(hydroxyurethane) elastomers toward nozzle-based 3D photoprinting

peer reviewedIn this work, isocyanate-free formulations for poly(propylene glycol) polyurethane elastomers are studied. These formulations are based on poly(propylene glycol) end-capped by CO2-sourced cyclic carbonate (bisCC PPG) macro-monomers able to react with amines leading to poly-(hydroxyurethane)s. In order to obtain covalent networks, two curing approaches are studied. First, the direct thermally activated cross-linking of bisCC PPG with a mixture of various aliphatic or aromatic diamines and a triamine is investigated, and in particular the nature of the diamine on the mechanical properties. In the second approach, UV-activated formulations are developed by reacting bisCC PPG with allylamine followed by the addition of a trithiol by photoactivated thiol−ene reaction. The swelling tests show that both systems provide highly cross-linked polymer networks and complementary characterizations highlighted excellent mechanical properties. Thanks to the fast curing and adapted viscosity of the developed photoactive formulation, the latter was found suitable for use as a photoresin for 3D printing as demonstrated by printing a vaginal ring by a nozzle-based photoprinter

Structural changes in the labor market and the rise of early retirement in France and Germany

The rise of early retirement in Europe is typically attributed to the European system of taxes and transfers. A model with an imperfectly competitive labor market allows us to consider also the effects of bargaining power and of matching efficiency on pre‐retirement. We find that lower bargaining power of workers and declining matching efficiency have been important determinants of early retirement in France and Germany. These structural changes, combined with early retirement transfers and population aging, are also consistent with the employment and unemployment rates, labor share and seniority premia

Structural changes in the labor market and the rise of early retirement in Europe

The rise of early retirement in Europe is typically attributed to the European system of taxes and transfers. Contrary to a purely neoclassical framework, a model with imperfectly competitive labor market also allows to consider the effect of the bargaining power of labor and matching efficiency on preretirement. We find that lower bargaining power of workers and less efficient labor markets characterized by the declining matching efficiency have been an important determinant of early retirement in France and Germany. These structural changes, combined with early-retirement transfers and population ageing, are also consistent with the joint evolution of employment and unemployment rates, the labor share and the seniority premium

Declining bargaining power of workers and the rise of early retirement in Europe

We offer an alternative explanation for the decline in labor force participation of senior workers. Typically, tax and transfer explanations have been proposed. On the contrary, a model with imperfectly competitive labor market allows to consider as well the effects of a drop in bargaining power, which would not be possible in a purely neoclassical framework. We find that a decline in the bargaining power of workers, which has taken place in the last four decades, has largely contributed to the rise in inactivity in Europe. However, we need a combination of these two explanations, along with population aging and a fall in the matching efficiency, in order to correctly reproduce the joint evolutions of other labor market variables such as the employment and unemployment rates

Structural changes in the labor market and the rise of early retirement in France and Germany

The rise of early retirement in Europe is typically attributed to the European system of taxes and transfers. A model with an imperfectly competitive labor market allows us to consider also the effects of bargaining power and of matching efficiency on pre-retirement. We find that lower bargaining power of workers and declining matching efficiency have been important determinants of early retirement in France and Germany. These structural changes, combined with early-retirement transfers and population aging, are also consistent with the employment and unemployment rates, labor share and seniority premia

Selective reductions in labor taxation: Labor market adjustments and macroeconomic performance

We use a calibrated general equilibrium model with heterogeneous labor and search to evaluate the quantitative effects of various labor tax cut scenarios. The focus is on skill heterogeneity combined with downward wage rigidities at the low end of the skill ladder. Workers can take jobs for which they are overeducated. We compare targeted and non-targeted tax cuts, both with or without over-education effects. Introducing over-education changes substantially the employment, productivity and welfare effects of a tax cut, although tax cuts targeted on the least skilled workers always have larger effects