Hypothesis: Response of lipid bilayers to external mechanical stimuli is an active area of research with implications for fundamental and synthetic cell biology. Developing novel tools for systematically imposing mechanical strains and non-invasively mapping out interfacial (membrane) stress distributions on lipid bilayers can accelerate research in this field. Experiments: We report a miniature platform to manipulate model cell membranes in the form of droplet interface bilayers (DIBs), and non-invasively measure spatio-temporally resolved interfacial stresses using two photon fluorescence lifetime imaging of an interfacially active molecular flipper (Flipper-TR). We established the effectiveness of the developed framework by investigating interfacial stresses accompanying three key processes associated with DIBs: thin film drainage between lipid monolayer coated droplets, bilayer formation, and bilayer separation. Findings: The measurements revealed fundamental aspects of DIBs including the existence of a radially decaying interfacial stress distribution post bilayer formation, and the simultaneous build up and decay of stress respectively at the bilayer corner and center during bilayer separation. Finally, utilizing interfacial rheology measurements and MD simulations, we also reveal that the tested molecular flipper is sensitive to membrane fluidity that changes with interfacial stress expanding the scientific understanding of how molecular flippers sense stress.

Superpuffs are planets with exceptionally low densities (rho less than or similar to 0.1 g cm-3) and core masses (M c less than or similar to 5M circle plus). Many lower-mass (M p less than or similar to 10M circle plus) superpuffs are expected to be unstable to catastrophic mass loss via photoevaporation and/or boil-off, whereas the larger gravitational potentials of higher-mass (M p greater than or similar to 10M circle plus) superpuffs should make them more stable to these processes. We test this expectation by studying atmospheric loss in the warm, higher-mass superpuff TOI-1420b (M = 25.1M circle plus, R = 11.9R circle plus, rho = 0.08 g cm-3, T eq = 960 K). We observed one full transit and one partial transit of this planet using the metastable helium filter on Palomar/WIRC and found that the helium transits were 0.671% +/- 0.079% (8.5 sigma) deeper than the TESS transits, indicating an outflowing atmosphere. We modeled the excess helium absorption using a self-consistent 1D hydrodynamics code to constrain the thermal structure of the outflow given different assumptions for the stellar XUV spectrum. These calculations then informed a 3D simulation, which provided a good match to the observations with a modest planetary mass-loss rate of 1010.82 g s-1 ( M p / M approximate to 70 Gyr). Superpuffs with M p greater than or similar to 10M circle plus, like TOI-1420b and WASP-107b, appear perfectly capable of retaining atmospheres over long timescales; therefore, these planets may have formed with the unusually large envelope mass fractions they appear to possess today. Alternatively, tidal circularization could have plausibly heated and inflated these planets, which would bring their envelope mass fractions into better agreement with expectations from core-nucleated accretion.

China has announced its ambitious targets towards carbon neutrality by 2060. The Guangdong-Hongkong-Macau (GHM) region, as a pilot demonstration area for China's reform and opening-up, faces dual pressures on providing low-carbon electricity for meeting its surging demand while limiting carbon emissions. Here, we develop an energy system optimization model with high spatio-temporal resolution that integrates investment planning and operation optimization to explore transition pathways for the GHM power system under various decarbonization scenarios. Power system operations in hourly resolution are included to quantify spatio-temporal variability of generation and demand. We show that reducing carbon emissions by 70%, 85%, and 100% in 2050 requires a total system cost of 619.1, 628.3, and 653.1 billion USD (values in 2021 USD), with an average decarbonization cost of 4.79, 5.27, and 7.11 USD per ton, respectively. Accelerating transition to carbon neutrality by 2035 incurs a total system cost of 686.9 billion USD and an average decarbonization cost of 9.11 USD per ton. Moreover, nuclear, offshore-wind, and imported electricity cover over 80% of electricity demand when achieving carbon neutrality and thus serve as cornerstones for supporting the GHM power system transition. Furthermore, we observe that a high fossil fuel price benefits emission mitigation, while reinforcing transmission networks considerably reduces system transition costs. Combing low renewable and storage prices, a high electricity import ratio, and transmission network expansion delivers a lower bound for system transition and a negative average decarbonization cost for the GHM region.

As the decarbonization of the electric power sector gathers pace, electric power systems will need to evolve in multiple ways: larger amounts of intermittent renewables will need to be deployed, as will dispatchable power generators, transmission lines, and energy storage solutions. Some of these resources could provide the electric power system with much-needed dispatchability, but the value of each will evolve over time and space, as will the impact of their deployment on economic costs and carbon emissions. This study systematically compares the roles that different sources of dispatchability could play in a power system's decarbonization and the evolution of its topology over the period from 2020 to 2060, with China as a case study. Results show that adding these resources to a system's operation yields multiple benefits for decarbonization. These include higher levels of renewables integration (+46 000 TWh, +19%), cost reductions (-5800 billion RMB, -13%), and lower GHG emissions (-23 billion tonnes, -23%). The role of different resources changes throughout the transition: transmission always plays the dominant role; dispatchable coal and nuclear generation reduces renewable curtailment up to 2030; pumped-hydro storage reduces curtailment from 2030 to 2040; and battery storage and concentrating solar power become critical after 2040. This evolution could redraw the economic and environmental maps of China by redistributing infrastructure, renewables integration and carbon emissions to less-developed, remote areas. These results help prioritize efforts to facilitate power system decarbonization over several decades; they also yield insights regarding the regional and sustainable development impact of the low-carbon transition.