Examination of the Mechanism of the Yield of N₂O from Nitroxyl (HNO) in the Solution Phase by Theoretical Calculations

The dimerization of HNO and subsequent yield of N₂O in aqueous solution are studied based on the theoretical calculations and kinetic simulations. The initial dimerization reactions were computed at various levels of theory, and large divergence was observed in the predictions of the gas-phase free energies. The <i>T</i>₁ diagnostics at CCSD­(T)/aug-cc-pVTZ suggests multireference characteristics of the HNO dimers and the transition states. The solution-phase free energies were obtained using the wB97XD method and the SMD solvation model. The p<i>K</i>_a values of the (HNO)₂ tautomers and their first protonated and deprotonated products were estimated using the cluster-continuum approach. The theoretical results confirmed the original conclusion that the favored <i>cis</i>-pathway is comprised of several rapid proton transfer steps leading to either <i>cis</i>-HONNOH or <i>cis</i>-HONNO¯ before decomposition. Several new water-catalyzed and H₃O⁺/water catalyzed reactions are presented to explain the fast kinetics observed in the experiments. To validate the proposed mechanism, kinetic simulations with the consideration of diffusion-limited kinetics were implemented on several related systems, based on which the previously reported global rate constant was explained as the kinetics of the initial dimerization step and the global kinetics in very dilute HNO solutions

Temporary Actuation of Bilayer Polymer Hydrogels Mediated by the Enzymatic Reaction

Most soft actuators have the ability of monotonic responsiveness. That is, there is only one response action after being stimulated once. In this work, a temporarily responsive bilayer hydrogel actuator is designed and fabricated by combining a tertiary amine-containing pH-responsive layer and a urease-containing non-responsive layer. The hydrogel actuator can achieve programed deformation and recovery driven by chemical fuels (i.e., acidic urea solutions), which is essentially regulated by rapid acidification and slow enzymatic production of ammonia for recovering the pH of the system. The actuation extent and duration can be simply controlled by the fuel levels, and the repeated actuations are also possible via refueling. Furthermore, we fabricate several hydrogel devices that can display specific patterns or lift an item. This enzymatic method shows new possibilities to control the temporary actuation of polymer hydrogels potentially useful in many fields such as soft robotics, biomimetic devices, and environmental sensing

Temporary Actuation of Bilayer Polymer Hydrogels Mediated by the Enzymatic Reaction

Most soft actuators have the ability of monotonic responsiveness. That is, there is only one response action after being stimulated once. In this work, a temporarily responsive bilayer hydrogel actuator is designed and fabricated by combining a tertiary amine-containing pH-responsive layer and a urease-containing non-responsive layer. The hydrogel actuator can achieve programed deformation and recovery driven by chemical fuels (i.e., acidic urea solutions), which is essentially regulated by rapid acidification and slow enzymatic production of ammonia for recovering the pH of the system. The actuation extent and duration can be simply controlled by the fuel levels, and the repeated actuations are also possible via refueling. Furthermore, we fabricate several hydrogel devices that can display specific patterns or lift an item. This enzymatic method shows new possibilities to control the temporary actuation of polymer hydrogels potentially useful in many fields such as soft robotics, biomimetic devices, and environmental sensing

Temporary Actuation of Bilayer Polymer Hydrogels Mediated by the Enzymatic Reaction

Most soft actuators have the ability of monotonic responsiveness. That is, there is only one response action after being stimulated once. In this work, a temporarily responsive bilayer hydrogel actuator is designed and fabricated by combining a tertiary amine-containing pH-responsive layer and a urease-containing non-responsive layer. The hydrogel actuator can achieve programed deformation and recovery driven by chemical fuels (i.e., acidic urea solutions), which is essentially regulated by rapid acidification and slow enzymatic production of ammonia for recovering the pH of the system. The actuation extent and duration can be simply controlled by the fuel levels, and the repeated actuations are also possible via refueling. Furthermore, we fabricate several hydrogel devices that can display specific patterns or lift an item. This enzymatic method shows new possibilities to control the temporary actuation of polymer hydrogels potentially useful in many fields such as soft robotics, biomimetic devices, and environmental sensing

Temporary Actuation of Bilayer Polymer Hydrogels Mediated by the Enzymatic Reaction

Most soft actuators have the ability of monotonic responsiveness. That is, there is only one response action after being stimulated once. In this work, a temporarily responsive bilayer hydrogel actuator is designed and fabricated by combining a tertiary amine-containing pH-responsive layer and a urease-containing non-responsive layer. The hydrogel actuator can achieve programed deformation and recovery driven by chemical fuels (i.e., acidic urea solutions), which is essentially regulated by rapid acidification and slow enzymatic production of ammonia for recovering the pH of the system. The actuation extent and duration can be simply controlled by the fuel levels, and the repeated actuations are also possible via refueling. Furthermore, we fabricate several hydrogel devices that can display specific patterns or lift an item. This enzymatic method shows new possibilities to control the temporary actuation of polymer hydrogels potentially useful in many fields such as soft robotics, biomimetic devices, and environmental sensing

Temporary Actuation of Bilayer Polymer Hydrogels Mediated by the Enzymatic Reaction

Most soft actuators have the ability of monotonic responsiveness. That is, there is only one response action after being stimulated once. In this work, a temporarily responsive bilayer hydrogel actuator is designed and fabricated by combining a tertiary amine-containing pH-responsive layer and a urease-containing non-responsive layer. The hydrogel actuator can achieve programed deformation and recovery driven by chemical fuels (i.e., acidic urea solutions), which is essentially regulated by rapid acidification and slow enzymatic production of ammonia for recovering the pH of the system. The actuation extent and duration can be simply controlled by the fuel levels, and the repeated actuations are also possible via refueling. Furthermore, we fabricate several hydrogel devices that can display specific patterns or lift an item. This enzymatic method shows new possibilities to control the temporary actuation of polymer hydrogels potentially useful in many fields such as soft robotics, biomimetic devices, and environmental sensing

Temporary Actuation of Bilayer Polymer Hydrogels Mediated by the Enzymatic Reaction

Most soft actuators have the ability of monotonic responsiveness. That is, there is only one response action after being stimulated once. In this work, a temporarily responsive bilayer hydrogel actuator is designed and fabricated by combining a tertiary amine-containing pH-responsive layer and a urease-containing non-responsive layer. The hydrogel actuator can achieve programed deformation and recovery driven by chemical fuels (i.e., acidic urea solutions), which is essentially regulated by rapid acidification and slow enzymatic production of ammonia for recovering the pH of the system. The actuation extent and duration can be simply controlled by the fuel levels, and the repeated actuations are also possible via refueling. Furthermore, we fabricate several hydrogel devices that can display specific patterns or lift an item. This enzymatic method shows new possibilities to control the temporary actuation of polymer hydrogels potentially useful in many fields such as soft robotics, biomimetic devices, and environmental sensing

A New Diminishing Interface Method for Determining the Minimum Miscibility Pressures of Light Oil–CO₂ Systems in Bulk Phase and Nanopores

In this paper, a new interfacial thickness-based method, namely, the diminishing interface method (DIM), is developed to determine the minimum miscibility pressures (MMPs) of light oil–CO₂ systems in bulk phase and nanopores. First, a Peng–Robinson equation of state (PR-EOS) is modified to calculate the vapor–liquid equilibrium in nanopores by considering the effects of capillary pressure and shifts of critical temperature and pressure. Second, the parachor model is coupled with the modified PR-EOS to predict the interfacial tensions (IFTs) in bulk phase and nanopores. Third, a formula of the interfacial thickness between two mutually soluble phases is derived, based on which the novel DIM is developed by considering two-way mass transfer across the interface. The MMP is determined by extrapolating the derivative of the interfacial thickness with respect to the pressure (∂δ/∂<i>P</i>)<i>_T</i> to zero. It is found that the modified PR-EOS coupled with the parachor model is accurate for predicting the phase behavior and IFTs in bulk phase and nanopores. More specifically, in nanopores, the lighter components prefer to be in vapor phase by increasing the temperature or decreasing the pressure and the IFTs are decreased with the pore radius, especially at low pressures. The determined MMPs of 12.4, 15.0, and 22.1 MPa from the DIM agree well with the laboratory measured results for the three Pembina light oil–CO₂ systems in bulk phase at <i>T</i>_res = 53.0 °C. Moreover, the MMPs of the Pembina and Bakken live oil–pure CO₂ systems in the nanopores of 100, 20, 4 nm are determined from the DIM, which tend to be decreased at a smaller pore level. Physically, the interface between the light oil and CO₂ diminishes and the two-phase compositional change reaches its maximum at the determined MMP from the DIM

Building Lithium-Polycarbonsulfide Batteries with High Energy Density and Long Cycling Life

The polysulfide shuttling and restricted kinetics of existing sulfur cathodes of lithium–sulfur batteries need to be tackled. Herein, we synthesized a polycarbonsulfide active material with an atomically assembled π-conjugated 3D conductive matrix via the self-polymerization of carbon disulfide (CS2) monomers. The as-synthesized polycarbonsulfide features oligo-S heterocycles assembled to conjugated conductive carbon chains. The coupled lithium-polycarbonsulfide battery delivered a high capacity of 724.5 mAh g–1 at 1.0 C (corresponding to 827.3 Wh kg–1) with an ultralow capacity decay rate of 0.032% per cycle, as well as high-rate capability of 499.6 mAh g–1 at 3.0 C. Multiple ex situ spectroscopic analyses revealed that the robust π-conjugated conductive polymeric matrix was well preserved during repeated battery operation, which efficiently tethered the discharge products to greatly restrict the shuttling effect

Two new sesquiterpene lactone glycosides from <i>Cnicus benedictus</i>

<p>Two new sesquiterpene lactone glycosides, namely melitensin 15-<i>O</i>-<i>β</i>-D-glucoside (<b>1</b>) and 11<i>β</i>,13-dihydrosalonitenolide 15-<i>O</i>-<i>β</i>-D-glucoside (<b>2</b>), along with eight known compounds (<b>3–10</b>) were isolated from the aerial part of <i>Cnicus benedictus</i> L. Their structures were elucidated from analyses of extensive spectroscopic data. Compounds <b>1–6</b> all possessed an <i>α</i>-methyl-<i>γ</i>-lactone moiety. Moreover, compound <b>5</b> exhibited moderate activity against the growth of <i>Aspergillus fumigatus</i>, with IC₅₀ values of 17.67 μg mL⁻¹.</p