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Autonomous Mobility-on-Demand (AMoD) systems represent an attractive alternative to existing transportation paradigms, currently challenged by urbanization and increasing travel needs. By centrally controlling a fleet of self-driving vehicles, these systems provide mobility service to customers and are currently starting to be deployed in a number of cities around the world. Current learning-based approaches for controlling AMoD systems are limited to the single-city scenario, whereby the service operator is allowed to take an unlimited amount of operational decisions within the same transportation system. However, real-world system operators can hardly afford to fully re-train AMoD controllers for every city they operate in, as this could result in a high number of poor-quality decisions during training, making the single-city strategy a potentially impractical solution. To address these limitations, we propose to formalize the multi-city AMoD problem through the lens of meta-reinforcement learning (meta-RL) and devise an actor-critic algorithm based on recurrent graph neural networks. In our approach, AMoD controllers are explicitly trained such that a small amount of experience within a new city will produce good system performance. Empirically, we show how control policies learned through meta-RL are able to achieve near-optimal performance on unseen cities by learning rapidly adaptable policies, thus making them more robust not only to novel environments, but also to distribution shifts common in real-world operations, such as special events, unexpected congestion, and dynamic pricing schemes. 

Rubisco is the enzyme responsible for CO₂ fixation in nature, and it is activated by CO₂ addition to the amine group of its lysine 201 side chain. We are designing rubisco-based biomimetic systems for reversible CO₂ capture from ambient air. The oligopeptide biomimetic capture systems are employed in aqueous solution. To provide a solid foundation for the experimental solution-phase studies of the CO₂ capture reaction, we report here the results of computational studies of the thermodynamics of CO₂ capture by small alkylamines in aqueous solution. We studied CO₂ addition to methyl-, ethyl-, propyl-, and butylamine with the consideration of the full conformational space for the amine and the corresponding carbamic acids and with the application of an accurate solvation model for the potential energy surface analyses. The reaction energies of the carbamylation reactions were determined based on just the most stable structures (MSS) and based on the ensemble energies computed with the Boltzmann distribution (BD), and it is found that ΔG_BD ≈ ΔG_MSS. The effect of the proper accounting for the molecular translational entropies in solution with the Wertz approach are much more significant, and the free energy of the capture reactions Δ^WA_BD is more negative by 2.9 kcal/mol. Further accounting for volume effects in solution results in our best estimates for the reaction energies of the carbamylation reactions of Δ^WA_BD = −5.4 kcal/mol. The overall difference is ΔG_BD – Δ^WA_BD = 2.4 kcal/mol for butylamine carbamylation. The full conformational space analyses inform about the conformational isomerizations of carbamic acids, and we determined the relevant rotational profiles and their transition-state structures. Our detailed studies emphasize that, more generally, solution-phase reaction energies should be evaluated with the Helmholtz free energy and can be affected substantially by solution effects on translational entropies. 

This paper reports completed empirical studies of a larger, STEAM-driven endeavor that bridges two continents and several disciplines, highlighting the role of the technical communicator. The research questions revolve around whether, and to what degree, scenario-based ethics training is effective in helping chemists understand the expectations for responsible publication practice in chemistry, as defined by prestigious universities, professional organizations, and reputable journals. We build on previous studies of scenario-based ethics training. We identify possible next steps for research and training in global science ethics. Ultimately, by building empirical and theoretical knowledge about challenges to ethical behavior, we will be able to identify effective instructional methods for culturally-inclusive, validated ethics training. 

Abstract We have been interested in the development of rubisco‐based biomimetic systems for reversible CO₂capture from air. Our design of the chemical CO₂capture and release (CCR) system is informed by the understanding of the binding of the activator CO₂(^ACO₂) in rubisco (ribulose‐1,5‐bisphosphate carboxylase/oxygenase). The active site consists of the tetrapeptide sequence Lys‐Asp‐Asp‐Glu (or KDDE) and the Lys sidechain amine is responsible for the CO₂capture reaction. We are studying the structural chemistry and the thermodynamics of CO₂capture based on the tetrapeptide CH₃CO−KDDE−NH₂(“KDDE”) in aqueous solution to develop rubisco mimetic CCR systems. Here, we report the results of¹H NMR and¹³C NMR analyses of CO₂capture by butylamine and by KDDE. The carbamylation of butylamine was studied to develop the NMR method and with the protocol established, we were able to quantify the oligopeptide carbamylation at much lower concentration. We performed a pH profile in the multi equilibrium system and measured amine species and carbamic acid/carbamate species by the integration of¹H NMR signals as a function of pH in the range 8≤pH≤11. The determination of ΔG₁(R) for the reaction R−NH₂+CO₂R−NH−COOH requires the solution of a multi‐equilibrium equation system, which accounts for the dissociation constantsK₂andK₃controlling carbonate and bicarbonate concentrations, the acid dissociation constantK₄of the conjugated acid of the amine, and the acid dissociation constantK₅of the alkylcarbamic acid. We show how the multi‐equilibrium equation system can be solved with the measurements of the daughter/parent ratioX, the knowledge of the pH values, and the initial concentrations [HCO₃⁻]₀and [R‐NH₂]₀. For the reaction energies of the carbamylations of butylamine and KDDE, our best values are ΔG₁(Bu)=−1.57 kcal/mol and ΔG₁(KDDE)=−1.17 kcal/mol. Both CO₂capture reactions are modestly exergonic and thereby ensure reversibility in an energy‐efficient manner. These results validate the hypothesis that KDDE‐type oligopeptides may serve as reversible CCR systems in aqueous solution and guide designs for their improvement. 

Self-assembled L,L-diphenylalanine (FF) nanostructures offer an attractive platform for photonics and nonlinear optics. The nonlinear optical (NLO) coefficients of FF nanotubes depend on the diameter of the tube [S. Khanra et al. Phys. Chem. Chem. Phys. 19(4), 3084–3093 (2017)]. To further enhance the NLO properties of FF, we search for structural modifications. Here, we report on the synthesis of fluorinated FF dipeptides by replacing one ortho-hydrogen atom in each of the phenyl groups of FF by a fluorine atom. Density-functional theoretical calculations yield insights into minimum energy conformers of fluorinated FF (Fl-FF). Fl-FF self-assembles akin to FF into micron-length tubes. The effects of fluorination are evaluated on the piezoelectric response and nonlinear optical properties. The piezoelectric d15 coefficient of Fl-FF is found to be more than 10 times higher than that of FF nanotubes, and the intensity of second harmonic generation (SHG) polarimetry from individual Fl-FF nanotubes is more than 20 times that of individual FF nanotubes. Furthermore, we obtain SHG images to compare the intensities of FF and Fl-FF tubes. This work demonstrates the potential of fluorine substitution in other self-assembled biomimetic peptides for enhancing nonlinear optical response and piezoelectricity.