Modified Gellan Gum hydrogels with tunable physical and mechanical properties

Gellan Gum (GG) has been recently proposed for tissue engineering applications. GG hydrogels are produced by physical crosslinking methods induced by temperature variation or by the presence of divalent cations. However, physical crosslinking methods may yield hydrogels that become weaker in physiological conditions due to the exchange of divalent cations by monovalent ones. Hence, this work presents a new class of GG hydrogels crosslinkable by both physical and chemical mechanisms. Methacrylate groups were incorporated in the GG chain, leading to the production of a methacrylated Gellan Gum (MeGG) hydrogel with highly tunable physical and mechanical properties. The chemical modification was confirmed by proton nuclear magnetic resonance (1H NMR) and Fourier transform infrared spectroscopy (FTIR-ATR). The mechanical properties of the developed hydrogel networks, with Young's modulus values between 0.15 and 148 kPa, showed to be tuned by the different crosslinking mechanisms used. The in vitro swelling kinetics and hydrolytic degradation rate were dependent on the crosslinking mechanisms used to form the hydrogels. Three-dimensional (3D) encapsulation of NIH-3T3 fibroblast cells in MeGG networks demonstrated in vitro biocompatibility confirmed by high cell survival. Given the highly tunable mechanical and degradation properties of MeGG, it may be applicable for a wide range of tissue engineering approaches.This research was funded by the US Army Engineer Research and Development Center, the Institute for Soldier Nanotechnology, the NIH (HL092836, DE019024, EB007249), and the National Science Foundation CAREER award (AK). This work was partially supported by FCT, through funds from the POCTI and/or FEDER programs and from the European Union under the project NoE EXPERTISSUES (NMP3-CT-2004-500283). DFC acknowledges the Foundation for Science and Technology (FCT), Portugal and the MIT-Portugal Program for personal grant SFRH/BD/37156/2007. HS was supported by a Samsung Scholarship. SS acknowledges the postdoctoral fellowship awarded by Fonds de Recherche sur la Nature et les Technologies (FQRNT), Quebec, Canada. We would like to thank Dr. Che Hutson for scientific discussions

A guaranteed immediate payout reduces impatience of financially constrained individuals

A large stream of literature found that individuals who experience financial strain are particularly concerned about their present needs—that is, they are more likely to choose smaller immediate payoffs over larger future payoffs. In contrast, some recent findings suggest that financially constrained individuals may be more concerned about future needs instead (e.g., they are relatively more likely to invest in long-lived durables than in short-lived experiences). We propose that the use of traditional intertemporal choice tasks has made prior studies overly sensitive to the myopia-inducing effects of financial constraint. These tasks typically offer a choice between receiving a smaller payoff in the present versus a larger payoff in the future. Across three studies, we observe that, as long as some immediate payout is guaranteed, financially constrained individuals are as likely as nonconstrained individuals to accept a delay for a larger payoff. These findings qualify prior demonstrations of the myopic effects of financial constraint and suggest that the traditionally used choice paradigm might not accurately capture time preferences, particularly for financially constrained individuals. Furthermore, they provide possible interventions for those interested in reducing the myopia of financially constrained individuals who are facing all now versus all later decisions

On the release of proteins from degrading dextran methacrylate hydrogels and the correlation with the rheologic properties of the hydrogels.

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Opportunities for a CO2-enhanced oil recovery project in the North Sea: Analysis of profitability and environmental impact

peer reviewedThe economic and environmental impact of an integrated CO2-EOR project in the Buzzard field in the North Sea is investigated through a life cycle analysis, a standard economic analysis and a more advanced geo-economic simulation. Results show the benefits of combining EOR with CO2 storage. However, the current economic environment provides insufficient long-term outlooks to justify the investment. © 2018 European Association of Geoscientists and Engineers, EAGE. All rights reserved

Opportunities for a CO2-enhanced oil recovery project in the North Sea: Analysis of profitability and environmental impact

The economic and environmental impact of an integrated CO2-EOR project in the Buzzard field in the North Sea is investigated through a life cycle analysis, a standard economic analysis and a more advanced geo-economic simulation. Results show the benefits of combining EOR with CO2 storage. However, the current economic environment provides insufficient long-term outlooks to justify the investment