Tetrameric self-assembling of water-lean solvents enables carbamate anhydride-based CO2 capture chemistry

Carbon capture, utilization and storage is a key yet cost-intensive technology for the fight against climate change. Single-component water-lean solvents have emerged as promising materials for post-combustion CO2 capture, but little is known regarding their mechanism of action. Here we present a combined experimental and modelling study of single-component water-lean solvents, and we find that CO2 capture is accompanied by the self-assembly of reverse-micelle-like tetrameric clusters in solution. This spontaneous aggregation leads to stepwise cooperative capture phenomena with highly contrasting mechanistic and thermodynamic features. The emergence of well-defined supramolecular architectures displaying a hydrogen-bonded internal core, reminiscent of enzymatic active sites, enables the formation of CO2-containing molecular species such as carbamic acid, carbamic anhydride and alkoxy carbamic anhydrides. This system extends the scope of adducts and mechanisms observed during carbon capture. It opens the way to materials with a higher CO2 storage capacity and provides a means for carbamates to potentially act as initiators for future oligomerization or polymerization of CO2.

Modulating Nanoparticle Size to Understand Factors Affecting Hemostatic Efficacy and Maximize Survival in a Lethal Inferior Vena Cava Injury Model

Intravenous nanoparticle hemostats offer a potentially attractive approach to promote hemostasis, in particular for inaccessible wounds such as noncompressible torso hemorrhage (NCTH). In this work, particle size was tuned over a range of <100-500 nm, and its effect on nanoparticle-platelet interactions was systematically assessed using in vitro and in vivo experiments. Smaller particles bound a larger percentage of platelets per mass of particle delivered, while larger particles resulted in higher particle accumulation on a surface of platelets and collagen. Intermediate particles led to the greatest platelet content in platelet-nanoparticle aggregates, indicating that they may be able to recruit more platelets to the wound. In biodistribution studies, smaller and intermediate nanoparticles exhibited longer circulation lifetimes, while larger nanoparticles resulted in higher pulmonary accumulation. The particles were then challenged in a 2 h lethal inferior vena cava (IVC) puncture model, where intermediate nanoparticles significantly increased both survival and injury-specific targeting relative to saline and unfunctionalized particle controls. An increase in survival in the second hour was likewise observed in the smaller nanoparticles relative to saline controls, though no significant increase in survival was observed in the larger nanoparticle size. In conjunction with prior in vitro and in vivo experiments, these results suggest that platelet content in aggregates and extended nanoparticle circulation lifetimes are instrumental to enhancing hemostasis. Ultimately, this study elucidates the role of particle size in platelet-particle interactions, which can be a useful tool for engineering the performance of particulate hemostats and improving the design of these materials.

Synthesis of Unzipping Polyester and a Study of its Photochemistry

Preparation of an unzipping polyester is reported. The monomer was prepared from benzoic acid in a four-step sequence. Step growth polymerization of the monomer provides the target polymer. Efficient depolymerization upon irradiation at 254 nm was confirmed with a quantum yield of >0.8. The photolysis mechanism was investigated, and the results of radical trapping experiments are consistent with an initial Norrish type I like homolysis followed by a radical mediated depropagation reaction driven by aromatization.

Design, synthesis and study of a photochromic α,ω-diene: toward new classes of photoswitchable polymers

A 4,5-dithienylimidazolium salt outfitted with pendant styrenyl groups was synthesized and studied. The salt was found to undergo reversible electrocyclization upon UV irradiation; subsequent exposure to visible light reversed the reaction. Acyclic diene metathesis (ADMET) polymerization of the salt afforded a novel fluorescent polyelectrolyte.

Training-induced Increase in Bone Mineral Density between Growing Male and Female Rats

The purpose of this study was to determine the existence of sex differences in the resistance training-induced elevation in bone mineral density (BMD) and bone strength (Fmax) during the growth period in rats. 16 male (M) and 16 female (F) rats (approx. 8 weeks old) were randomly divided into sedentary control (MC=8, FC=8), and resistance-trained (RT) groups (M-RT=8, F-RT=8). The RT groups were conditioned to climb a vertical ladder 4 consecutive times (per exercise session) with weights attached to their tail 3 days per week for a total of 6 weeks. After 6 weeks, there were no interaction effects (sex×exercise). The main effect of sex indicated no difference in tibial BMD (in g/cm(2)) for males (0.226±0.005) compared to females (0.221±0.004). However, Fmax (in Newtons) was significantly greater for males (131.3±5.3) compared to females (89.9±3.0). The main effect of exercise indicated that tibial BMD and Fmax were significantly greater for RT groups (0.234±0.004 g/cm(2) and 120.9±7.4 Newtons) compared to controls (0.212±0.003 g/cm(2) and 100.3±5.1 Newtons). The results indicate that during growth, there were no sex differences in the training-induced elevation in BMD and bone mechanical properties.

Automated interferogram analysis based on an integrated expert system

Interferometric data, either from single-frame fringe-tracking and Fourier-transform techniques or from multiframe phase-shifting techniques, pose a problem of 2π ambiguity, that is, wrapped-phase information. As the degree of noise level increases, especially in high-speed aerodynamics, these techniques encounter difficulties in phase extraction to provide continuous unwrapped-phase information. Here, a new hybrid approach, called the integrated expert system, which is developed primarily for aerodynamic interferogram evaluation, is presented. The integrated expert system utilizes interferometric-specific knowledge rules to compensate for the limitations associated with conventional techniques. It integrates in a single structure an expert system and algorithmic programming to provide, as much as possible, a unified approach for all the interferogram evaluation techniques. This initial attempt may provide a useful groundwork for future development in intelligent interferogram processing.