We calculate the primordial trispectrum of curvature perturbation in quasi-single field inflation, with general sound speeds for both the inflaton and the massive scalar. Special attention is paid to various soft limits of the trispectrum, where the shape function shows characteristic oscillatory pattern (known as the quantum primordial standard clock signal) as a function of the momentum ratio. Our calculation is greatly simplified by using the "mixed propagator" developed under a diagrammatic representation of the in-in formalism.

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Carbon dioxide plays a significant role in environmental scale and industrial utilization. As an essential gas in the atmosphere, CO 2 is crucial, however, a predictable trend shows that CO 2 will become excessive, even triggering severe issues to the planet. Some abnormal phenomenons have corroborated the predication and a pragmatic solution is urgently needed. This paper, through research review, gives examples of porous carbons which generally exhibit excellent carbon dioxide uptake capacity. The category of raw material of porous carbon is diverse, and the paper selects reports about porous carbons obtained from different precursors. Their CO 2 uptake capacities are estimated and discussed via some principles such as heat of adsorption, porosity, synergy. The paper finds that all the mentioned porous carbons such as Shrimp shell, Glucose, Sawdust, Date, Phenolic resin, Hyperlinked porous polymer show remarkable CO 2 uptake performance in the investigation. Using porous carbon as approaches of CO 2 adsorption will surely become one of the most prevailing trends in future material development.